JP2022157247A - Blood pressure measuring device and blood pressure measuring program - Google Patents

Abstract

To avoid blood pressure measurement with a low degree of accuracy.SOLUTION: A blood pressure measuring device 1 measures a first pulse wave at a first position of an object person 15 and a second pulse wave at a second position whose distance from the heart is larger than that of the first position, obtains a delay time L of the second pulse wave with respect to the first pulse wave on a side close to the heart, and measures a blood pressure using relationships between the delay time and the blood pressure. It is determined whether the delay time of the second pulse wave with respect to the first pulse wave is larger than a reference value Th, and if it is larger than the reference value Th=0.08 sec., the blood pressure is measured from the delay time. If the delay time is the reference value Th or less, accurate blood pressure measurement is not possible so that reporting is executed, for prompting change in the measurement position (the second position) of the second pulse wave.SELECTED DRAWING: Figure 8

Description

TECHNICAL FIELD The present invention relates to a blood pressure measurement device and a blood pressure measurement program, and to a technique for measuring blood pressure from pulse waves measured at two points.

Demand for easy blood pressure measurement is increasing along with the recent rise in health consciousness, and a technology has been proposed that measures blood pressure using the correlation between pulse wave delay time and blood pressure measured at two locations on a subject. It is
For example, in Patent Document 1, as a technique for measuring relative blood pressure without contact, a moving image of a subject's face and fingers is captured by cameras placed on the front and back of a mobile terminal, and the color of the captured image is changed. Pulse wave waveforms of the face and fingers are detected using the R component and the G component (which change with the pulse wave) among the constituent RGB components. The blood pressure is measured by the amount of delay of the peak of the finger pulse wave with respect to the peak of the pulse wave of the face, which is detected by utilizing the correlation between the propagation time of the pulse wave from the heart to each part of the body and the blood pressure.

However, experiments by the inventors of the present application have revealed that when blood pressure is measured from pulse waves measured at two locations, it is not always possible to measure with high accuracy, depending on the measurement location, and there are cases where the accuracy is low. In particular, when using pulse waves measured at the face and fingertips, the accuracy of the measured blood pressure may be low.
Further, in the case of the technique described in Patent Document 1, the peak of the pulse wave is a region where disturbance due to changes in external light or the like is large, and there is a problem that highly accurate measurement is difficult due to the influence of the disturbance.

JP 2014-198198 A

Therefore, the first object of the present invention is to avoid blood pressure measurement with low accuracy.
A second object is to measure blood pressure with little influence of disturbance.

(1) In the invention according to claim 1, the first pulse wave acquiring means for acquiring the first pulse wave m1 measured at the first position of the subject, and the distance from the heart of the subject is the first A second pulse wave acquiring means for acquiring a second pulse wave m2 measured at a second position distant from the position, and a delay time acquiring means for acquiring a lag time L of the second pulse wave m2 with respect to the first pulse wave m1. means, reporting means for reporting when the obtained delay time L is equal to or less than a reference value Th, and delay time obtained by the delay time obtaining means when the delay time L is greater than the reference value Th. blood pressure acquiring means for acquiring the subject's systolic blood pressure SBP and diastolic blood pressure DBP using L; and output means for outputting the acquired systolic blood pressure SBP and diastolic blood pressure DBP. The first object is achieved by providing a blood pressure measuring device that
(2) In the invention according to claim 2, the delay time obtaining means obtains the lowest value V, the highest value T, the maximum slope D, and the correlation delay in the first pulse wave m1 and the second pulse wave m2. The blood pressure measuring device according to claim 1, wherein the delay time L is obtained using any pulse wave element of C.
(3) In the invention according to claim 3, the delay time obtaining means sets the delay time L used for comparison with the reference value Th and the delay time L used for obtaining the blood pressure to different pulse wave elements. The blood pressure measurement device according to claim 2, wherein the blood pressure measurement device is obtained by using
(4) In the invention according to claim 4, the delay time obtaining means obtains the delay time L used for comparison with the reference value Th using the minimum value V, and the delay time used for obtaining the blood pressure. 3. The blood pressure measuring device according to claim 2, wherein L is obtained using the correlation delay C.
(5) In the invention according to claim 5, the reference value Th is a time selected from a range of 0.1 seconds to 0.06 seconds. A blood pressure measuring device according to claim 1 is provided.
(6) In the invention according to claim 6, the reference value Th is 0.08 seconds. offer.
(7) The invention according to claim 7 is characterized in that the notification means uses at least one of image display and sound to perform notification prompting a change of the second position for acquiring the second pulse wave. A blood pressure measuring device according to any one of claims 1 to 6 is provided.
(8) In the invention according to claim 8, the first pulse wave acquiring means and the second pulse wave acquiring means are configured to measure pulse waves based on the amount of change in light transmitted or reflected inside the body of the subject. The blood pressure measuring device according to any one of claims 1 to 7 is provided, characterized in that a pulse wave is acquired using a sensor of the type.
(9) In the invention according to claim 9, the first pulse wave acquiring means acquires a first moving image obtained by photographing the first body surface of the subject under ambient light, and from the first moving image, A first pulse wave is acquired using a time change of a color component, and the second pulse wave acquiring means acquires a second moving image of a second body surface of the subject under predetermined illumination light. and obtaining a second pulse wave from the second moving image using a time change of a color component different from the color component. The second object is achieved by providing the blood pressure measuring device according to the above item.
(10) In the invention according to claim 10, the first pulse wave obtaining means obtains the first pulse wave using the Q component included in the YIQ component from the first moving image, and obtains the second pulse wave 10. The blood pressure measuring device according to claim 9, wherein the wave acquiring means acquires the second pulse wave from the second moving image using G components contained in RGB components.
(11) In the invention according to claim 11, a first pulse wave acquiring function for acquiring a first pulse wave m1 measured at a first position of the subject, and a distance from the heart of the subject to the first A second pulse wave acquisition function for acquiring a second pulse wave m2 measured at a second position distant from the position, and a delay time acquisition function for acquiring a delay time L of the second pulse wave m2 with respect to the first pulse wave m1. a notification function for notifying that when the obtained delay time L is less than or equal to a reference value Th; and a delay time obtained by the delay time obtaining function when the delay time L is greater than the reference value Th. To cause a computer to realize a blood pressure acquisition function of acquiring the subject's systolic blood pressure SBP and diastolic blood pressure DBP using L, and an output function of outputting the acquired systolic blood pressure SBP and diastolic blood pressure DBP. blood pressure measurement program.

According to the first aspect of the present invention, when it is determined that the measurement position is not appropriate from the delay time L of the pulse wave, the fact is notified, so blood pressure measurement with low accuracy can be avoided.
According to the ninth aspect of the present invention, blood pressure measurement can be performed with little influence of disturbance by using time changes of different types of color components in two moving images.

1 is an explanatory diagram of a configuration of a blood pressure measuring device according to a first embodiment; FIG. FIG. 4 is an explanatory diagram showing the arrangement positions of a first pulse wave measuring unit and a second pulse wave measuring unit; FIG. 4 is an explanatory diagram showing pulse wave elements of a first pulse wave and a second pulse wave used for measuring delay time L; It shows pulse waves measured simultaneously at five measurement positions. FIG. 4 shows the delay time L, the correlation coefficient of the systolic blood pressure SBP, and the correlation coefficient of the diastolic blood pressure DBP when the pulse wave is measured by the contact method. It shows the measurement results at the same measurement position by multiple subjects. FIG. 4 shows the delay time L, the correlation coefficient of the systolic blood pressure SBP, and the correlation coefficient of the diastolic blood pressure DBP when the pulse wave is measured by the non-contact method. 4 is a flow chart showing details of blood pressure measurement processing by the blood pressure measurement device. FIG. 10 is a flow chart of a delay time calculation process for calculating a delay time L using a pulse wave minimum value V; FIG. 4 is a flowchart of a delay time calculation process for calculating a delay time L using a maximum pulse wave gradient D; FIG. 11 is an explanatory diagram of the configuration of a blood pressure measurement device according to a second embodiment; It is a figure for demonstrating the usage pattern of a blood-pressure measuring device. FIG. 10 is a diagram for explaining inversion of a finger signal; FIG. FIG. 4 is a diagram for explaining a delay in pulse wave propagation; It is a figure showing the formula of cross-correlation. FIG. 4 is a diagram showing an example of cross-correlation; FIG. 10 is a diagram showing the relationship between the number of data points of delay and cross-correlation; FIG. 4 is a diagram for explaining interpolation of pulse waves; FIG. 5 is a diagram for explaining the effect of cross-correlation interpolation; FIG. 4 is a diagram for explaining optimization of a bandpass filter; 4 is a flowchart for explaining blood pressure measurement processing; It is a continuation of the flowchart for explaining the blood pressure measurement process. FIG. 10 is a flowchart for explaining a moving image frame reading process; FIG. 4 is a flowchart for explaining parameter setting/initialization processing; FIG. 10 is a flowchart and an explanatory diagram for explaining measurement area setting processing; 4 is a flowchart for explaining face signal acquisition processing; 4 is a flowchart for explaining face signal spectrum calculation processing; 4 is a flowchart for explaining face pulse rate detection processing; FIG. 10 is a flowchart and an explanatory diagram for explaining face signal strength evaluation processing; 4A and 4B are a flowchart and an explanatory diagram for explaining finger signal acquisition processing; 4 is a flow chart for explaining facial finger signal preprocessing; 4 is a flowchart for explaining blood pressure measurement processing; 4 is a flowchart for explaining moving image shooting processing; It is the figure which evaluated the performance of the blood-pressure measuring device.

(1) Outline of First Embodiment A blood pressure measuring device 1 according to the first embodiment provides a first pulse wave at a first position of the subject 15 and a second pulse wave at a second position that is farther from the heart than the first position. Two pulse waves are measured, the delay time L of the second pulse wave with respect to the first pulse wave near the heart is obtained, and the correlation between this delay time and blood pressure is used to measure the blood pressure.
This embodiment determines whether or not the delay time of the second pulse wave with respect to the first pulse wave is longer than a reference value Th, and if it is longer than the reference value Th, blood pressure is measured from the delay time.
On the other hand, if the delay time is equal to or less than the reference value Th, accurate blood pressure measurement cannot be performed.

This embodiment is based on new knowledge that when the delay time of the second pulse wave with respect to the first pulse wave is equal to or less than the reference value Th, the correlation between the delay time and the blood pressure is low, which is not preferable for blood pressure measurement. It is based on This finding was obtained by conducting experiments with various changes in the first and second positions. Something may be the cause.

Through experiments, it was found that the reference value Th should preferably be selected in the range of 0.1 seconds to 0.06 seconds, with an optimum value of 0.08 seconds.
Further, in order to obtain the delay time L from both pulse waves, it is necessary to use pulse wave elements such as the same characteristic positions of the first pulse wave and the second pulse wave. It was also found that any of the pulse wave minimum value V, maximum value T, maximum slope D, and correlation delay C can be used as the pulse wave element, and that the minimum value V is optimal.
Furthermore, the delay time for determining whether blood pressure can be measured (determining whether blood pressure can be measured) and the delay time for blood pressure measurement using the correlation are the same pulse wave elements (V, T, D, C) may also be used and different pulse wave components may be used.

(2) Details of First Embodiment FIG. 1 is a diagram for explaining the configuration of a blood pressure measurement device 1 according to this embodiment.
The blood pressure measuring device 1 is configured by a computer system including a CPU (Central Processing Unit) 2 .
The CPU 2 includes a ROM (Read Only Memory) 3, a RAM (Random Access Memory) 4, a display 5, a first pulse wave measurement section 7, a second pulse wave A measurement unit 8, a storage unit 10, and a communication control unit 11 are connected.

The CPU 2 is a central processing unit that performs various types of information processing and control according to programs stored in the storage unit 10, the ROM 3, and the like.
For example, according to the blood pressure measurement program 10a, the CPU 2 determines whether or not the pulse wave can be measured from the pulse wave delay time L measured by the first pulse wave measurement unit 7 and the second pulse wave measurement unit 8. The blood pressure is detected using a notice prompting a change in the measurement position based on the time and the delay time.

The ROM 3 is a read-only memory and stores basic programs and parameters for operating the blood pressure measuring device 1 .
The RAM 4 is a readable/writable memory and provides a working memory when the CPU 2 operates. In this embodiment, the CPU 2 temporarily stores data necessary for determining the systolic blood pressure SBP and the diastolic blood pressure DBP, such as the acquired first pulse wave, second pulse wave, and delay time L obtained from both pulse waves. Remember.

The display 5 is configured using, for example, a liquid crystal panel, and displays icons for selecting various application programs and various screens provided by these applications.
The display 5 of the present embodiment functions as a notification means for displaying a warning message prompting a change in the measurement position of the second pulse wave measuring unit 8 when the pulse wave delay time L is equal to or less than the reference value Th, and It functions as display means and output means by displaying the measured blood pressure.
In the present embodiment, a warning message prompting the change is displayed on the display 5 as notification means, but instead of displaying the warning message, or/and a voice or warning sound prompting the change of the measurement position is output from the speaker. You may make it

The first pulse wave measuring unit 7 and the second pulse wave measuring unit 8 measure the first pulse wave and the second pulse wave of the subject 15 by various well-known methods such as transmission pulse wave measurement and reflection pulse wave measurement. Measure waves.
Transmissive pulse wave measurement is a method of irradiating a living body with infrared light or red light and measuring a pulse wave as the amount of change in the light that passes through the body. Reflective pulse wave measurement is a method in which a living body is irradiated with infrared light, red light, or green light, and a pulse wave is measured as a change in light reflected inside the living body using a light receiving element.
Both transmissive pulse wave measurement and reflective pulse wave measurement measure pulse waves by bringing a sensor into contact with the body surface. It is also possible to use non-contact measuring methods to measure the .
The first pulse wave measuring unit 7 and the second pulse wave measuring unit 8 employ the same measurement method, and in this embodiment, a reflective pulse wave sensor that emits green light that is less affected by disturbance is used. It should be noted that the blood pressure measurement device 1 of the second embodiment, which will be described later, uses a non-contact measurement method.

The storage unit 10 is configured using a storage medium such as a hard disk or EEPROM (Electrically Erasable Programmable Read-Only Memory), and stores a blood pressure measurement program 10a for the CPU 2 to measure blood pressure, other programs, and blood pressure measurement. stores various data 10b necessary for

The blood pressure measurement program 10a is a program that causes the CPU 2 to perform blood pressure measurement processing.
The blood pressure measurement device 1 can provide various functions as a blood pressure measurement device by the CPU 2 executing the blood pressure measurement program 10a.
The data 10b stores, for example, a reference value Th used to determine whether blood pressure measurement is possible, a parameter for calculating blood pressure from the delay time L, and the like, as data necessary for blood pressure measurement. The parameters are parameters PS1 and PS2 for calculating the systolic blood pressure SBP, and parameters PD1 and PD2 for calculating the diastolic blood pressure DBP.

The systolic blood pressure SBP and the diastolic blood pressure DBP are calculated from the following equations (A) and (B) using the delay time L. parameters PS2 and PD2.
Systolic blood pressure SBP=PS1×delay time L+PS2 Equation (A)
Diastolic blood pressure DBP=PD1×delay time L+PD2 Equation (B)

The linear equations represented by equations (A) and (B) are equations obtained in advance by regression analysis such as the least-squares method for a large number of measured values of delay times L and blood pressures (SBP, DBP).
Formulas (A) and (B) are defined in blood pressure measurement program 10a, and four parameters are stored in data 10b.
As will be described later, any pulse wave element (minimum value V, maximum value T, maximum slope D, correlation delay C in FIG. 3) can be used for calculating the delay time L. The parameters used in the above formulas (A) and (B) differ depending on the element.
Therefore, the data 10b stores four parameters according to the pulse wave element used, and in this embodiment using the lowest value V for calculating the delay time L, the following parameter values are stored in the data 10b: there is
PS1 = -1/0.0048, PS2 = 1.7391/0.0048
PD1 = -1/0.0071, PD2 = 1.6273/0.0071

The communication control unit 11 transmits and receives various programs and data to and from an external device connected wirelessly or by wire.
The communication control unit 11 functions as a pulse wave acquisition means by acquiring the first pulse wave and the second pulse wave of the subject 15 measured by the external device, and notifies the external device of the change in the measurement position. When the blood pressure is measured from the delay time L, it functions as an output means.

With the blood pressure measuring device 1 configured as described above, the blood pressure is determined from the delay time between the first pulse wave and the second pulse wave of the subject 15. However, in the present embodiment, it is known that the blood pressure cannot be measured depending on the delay time. Based on The experiments leading to this finding will be described below.
In this experiment, one first pulse wave measuring unit 7 and a plurality of second pulse wave measuring units 8 (four locations) were arranged, and four second pulse wave delays were performed with respect to the first pulse wave. Time, etc. were measured.

FIG. 2 shows the arrangement positions of the first pulse wave measuring unit 7 and the second pulse wave measuring unit 8 attached to the subject 15. As shown in FIG.
As shown in FIG. 2, the first pulse wave measurement unit 7 for first pulse wave measurement is placed on the forehead M1 of the subject 15 as a reference for calculating the pulse wave delay time L. As shown in FIG. A second pulse wave measuring unit 8 for measuring a second pulse wave is arranged at each position of the subject 15, such as the forearm M4, the wrist M5, the base of the thumb M6, and the fingertip M7.

The blood pressure measuring device 1 calculates the delay time L of the second pulse wave with respect to the measured first pulse wave. This delay time L is caused by the difference in the distance from the heart to the position where the pulse wave is measured. . Therefore, the second pulse wave measuring units 8 are arranged at positions M4 to M7 which are farther from the heart than the forehead M1 where the first pulse wave measuring units 7 are arranged.
In the blood pressure measuring device 1 of the present embodiment, as described with reference to FIG. 1, the first pulse wave measuring section 7 and the second pulse wave measuring section 8 are one set. On the other hand, in this experiment, in order to compare the pulse waves measured at the same time at each of the measurement positions M4 to M7 of the subject 15 and evaluate the calculated delay time L, a plurality of second pulse A wave measuring unit 8 is arranged.

FIG. 3 shows the pulse wave elements (same characteristic positions, etc.) of the first pulse wave and the second pulse wave used for measuring the delay time L. FIG.
As the pulse wave elements of the first pulse wave and the second pulse wave, the minimum value V, maximum value T, and maximum slope D, which are characteristic positions of the pulse wave m0 shown in FIG. 3, are used. It is possible to calculate the delay time L using the correlation delay C which is
The lowest value V is the value of the trough portion of the pulse wave m0, and the highest value T is the peak value of the pulse wave m0.
The maximum slope D is the maximum value of the differential values (slopes) D1, D2, .
Correlation delay C is to obtain delay time L using the entire waveform of the pulse wave. Although the details will be described in the second embodiment, one pulse wave is sequentially shifted in the time direction, and the delay time L is obtained from the shift amount with the highest cross-correlation between the two pulse waves.

FIG. 4 shows pulse waves m1, m4 to m7 simultaneously measured at five measurement positions (M1, M4 to M7) shown in FIG.
As shown in FIG. 4, the pulse wave m1 is the waveform of the forehead M1 measured by the first pulse wave measurement unit 7, and the pulse waves m4 to m7 are the waveforms of the forearm M4, wrist M5, and thumb measured by the second pulse wave measurement unit 8. Waveforms measured at each position of root M6 and fingertip M7.
In FIG. 4, the minimum value (trough) V is used as the pulse wave element, and the minimum values of each pulse wave are V1, V4 to V7. Then, with reference to the lowest value V1 of the pulse wave m1 of the forehead M1 at the position closest to the heart, the time from the lowest values V4 to V7 of the other pulse waves m4 to m7 are delay times L14 to L17.

Looking at each delay time L shown in FIG. 4, the arrival of the pulse wave is delayed as the distance from the heart increases. The lowest value V4 of the wave m4 is delayed by the delay time L14.
On the other hand, the delay time L15 at the lowest value V5 of the wrist M5, which is further away from the forearm M4, is longer than the delay time L14 of the forearm M4 (L15>L14).
However, the delay time L16 of the base of the thumb M6, which is further away from the wrist M5, is smaller than the delay time L15 of the wrist M5 (L16<L15).
Similarly, the delay time L17 of the fingertip M7 further away from the base of the thumb M6 is smaller than the delay time L16 of the base of the thumb M6 (L17<L16).

As for the pulse waves m4 and m5 in FIG. 4, the delay time L increases as the distance from the heart increases, so it is presumed that the pulse waves from the heart are accurately measured.
However, for the pulse waves m6 and m7, the delay time L is reduced even though the distance is increased. It is presumed that this is because the shape of the pulse wave from the heart is affected by reflected waves (pulse waves returning to the heart) and the like, and the shape changes.

Therefore, as another experiment, for each pulse wave m1, m4-7 measured at the measurement positions M1, M4-M7 shown in FIG. The correlation coefficient of blood pressure DBP was examined.
FIG. 5 shows the delay time L, the correlation coefficient of the systolic blood pressure SBP, and the correlation coefficient of the diastolic blood pressure DBP when the pulse wave is measured by the contact method.
The delay times L14 to L17 in FIG. 5(a) are obtained using the lowest value V among the pulse wave elements in FIG. On the other hand, the delay time L used to obtain the correlation coefficients in FIGS. It is what I asked for.

The measurement is based on the measurement position M1 on the forehead, and the lag time L is used at the measurement positions M4 to M7 that are farther from the heart than that, so the lag time and the blood pressure have a negative correlation coefficient. It should be. Therefore, as shown in FIGS. 5(b) and (c), the correlation coefficient of the pulse wave m6 measured at the base of the thumb M6 (hereinafter referred to as the correlation coefficient of the base of the thumb M6; the same shall apply hereinafter) and the phase of the fingertip M7 Since both blood pressures have positive correlation coefficients for all pulse wave components (VTDC), both are unsuitable for measuring blood pressure.

Regarding the correlation coefficient of the wrist M5, a total of eight correlation coefficients of four pulse wave components (VTDC) for systolic blood pressure SBP and diastolic blood pressure DBP show a weak correlation (correlation coefficient is -0.2 -0.4 or more) are recognized, but the remaining three have positive correlation coefficients, and since the correlation coefficients are small (0 or more, less than -0.2), no correlation is recognized. are two.
Therefore, as a whole, the pulse wave m5 measured at the wrist M5 is not suitable for blood pressure measurement.
On the other hand, the measurement position M4 on the forearm is suitable for blood pressure measurement because negative correlations are recognized with respect to all eight correlation coefficients.

In the example shown in FIG. 5, the pulse waves measured at the base of thumb M6 and fingertip M7 were not suitable for blood pressure measurement. In this example, the same subject 15 is targeted, and the results are obtained when the pulse wave is measured at a plurality of measurement positions (M1, M4 to M7).
Therefore, it was confirmed whether suitability for the same measurement position (the forehead M1 and the fingertip M7, which were regarded as inappropriate in FIG. 5), was determined for a plurality of persons.

FIG. 6 shows measurement results at the same measurement position (forehead M1 and fingertip M7) by a plurality of subjects. 6(a) to (c) show the delay time L obtained using the lowest value V of the pulse wave element and the correlation coefficient between both blood pressures (SBP, DBP) obtained from the delay time L. ing.
As shown in FIG. 6, the same measurement positions (forehead M1 and fingertips M7) are not always determined as appropriate/inappropriate positions, and the subject 15 who performs the measurement varies the systolic blood pressure SBP and the diastolic blood pressure SBP. When the correlation coefficient of the blood pressure DBP is positive and inappropriate, when the absolute value of the negative correlation coefficient is too small, and the absolute value of the negative correlation coefficient is large, a correlation may be recognized.

For each experiment described above, the contact-type first pulse wave measuring unit 7 and second pulse wave measuring unit 8 shown in the blood pressure measuring device 1 of FIG. 1 are used.
Therefore, a similar experiment was conducted for the case where the pulse wave of the subject 15 was measured without contact. Details of non-contact pulse wave measurement will be described in detail in the second embodiment.
FIG. 7 shows the delay time L, the correlation coefficient of the systolic blood pressure SBP, and the correlation coefficient of the diastolic blood pressure DBP when the pulse wave is measured by the non-contact method.
In FIG. 7(a), the pulse waves m1, m4, m5, and m6' of the forehead M1, forearm M4, wrist M5 (see FIG. 2), and palm M6' were measured, and the lowest value V of the pulse wave element was used. and delay times L14, L15 and L16' of pulse waves m4, m5 and m6' with reference to pulse wave m1.
On the other hand, in FIGS. 7B and 7C, blood pressure (SBP, DBP ) represents the correlation coefficient.
As shown in FIG. 7, the delay time L calculated using the pulse wave measured by the non-contact method and the blood pressure correlation coefficient have the same tendency as when measured by the contact method in FIG. .

The following conclusions were obtained as a result of conducting more experiments based on the contents described in FIGS. 5 to 7 above.
(a) Blood pressure can be measured with high accuracy when the pulse wave m measured at two points on the subject 15 has a delay time L greater than the reference value Th.
That is, it is possible to determine whether or not blood pressure measurement is possible (blood pressure measurement determination) depending on whether or not the delay time L is greater than the reference value Th.
(b) The reference value Th is preferably selected in the range of 0.1 seconds to 0.06 seconds, and the optimum value is 0.08 seconds.
By selecting the reference value Th in the range of 0.1 seconds to 0.06 seconds, the systolic blood pressure SBP, diastolic blood pressure SBP, and diastolic blood pressure are more accurate than the conventional measurement without judging the measurement position. It becomes possible to measure the blood pressure DBP.
(c) As the pulse wave element for calculating the delay time L of the pulse wave m at two locations, any of the minimum value V, maximum value T, maximum slope D, and correlation delay C of the pulse wave can be used. It is possible.
(d) The blood pressure measurement propriety determination of (a) above can be performed with the delay time L calculated using any of the pulse wave elements (VTDC) of (c) above.
(e) The calculation of the delay time L when determining whether blood pressure measurement is possible can use any of the pulse wave elements (VTDC) in (c) above, but the use of the lowest value V of the pulse wave is optimal. .
The reason why the lowest value V of the pulse wave is optimal is that since the lowest value V corresponds to the minimum value of blood flow, it is considered to be most susceptible to reflected waves (pulse waves returning to the heart).
Therefore, by using the delay time L calculated from the minimum value V of the pulse wave, it is possible to further improve the accuracy of the blood pressure measurement propriety determination.
(f) The calculation of the delay time L used when obtaining the systolic blood pressure SBP and the diastolic blood pressure DBP can use any of the pulse wave elements (VTDC) in (c) above.
(g) Regarding the above (a) to (f), the pulse wave detection method is common to the contact type and the non-contact type.

Based on the above conclusion, FIG. 6 shows the result of blood pressure measurement propriety determination when the reference value Th=0.08 seconds.
When the reference value Th is set to 0.08 seconds as indicated by the dotted line in FIG. Since it is 0.08 or more, it is subject to blood pressure measurement at the current measurement position.
On the other hand, the 10 persons indicated by the black squares have the delay time L less than the reference value Th, so they are subject to a warning (notification) requesting a change in the measurement position of the second pulse wave m2.
When the correlation coefficients (FIGS. 6(b) and (c)) of the 10 subjects to be notified are confirmed, at least one of the systolic blood pressure SBP and the diastolic blood pressure DBP has a positive correlation coefficient for 8 people. Therefore, it is a pulse wave that cannot measure blood pressure correctly, and it can be evaluated that the information is correct. That is, erroneous blood pressure measurement using a pulse wave in which a negative correlation between the delay time L and blood pressure cannot be obtained has not been performed.

On the other hand, for the two patients who described failure, the delay time L was less than the reference value Th, so they were subject to notification. , the notification judgment is wrong.
However, although it is an erroneous judgment, the pulse wave at the current position is not measured, and the change of the measurement position is instructed, and an erroneous blood pressure value is not output.

Next, the blood pressure measurement process by the blood pressure measurement device 1 of the first embodiment described with reference to FIG. 1 will be described based on the above experimental results.
FIG. 8 is a flowchart showing the details of the blood pressure measurement process by the blood pressure measurement device 1. As shown in FIG.
According to the blood pressure measurement program 10a, the CPU 2 acquires the first pulse wave m1 of the subject 15 measured by the first pulse wave measurement unit 7, and stores it in the RAM 4 (step 705).
The CPU 2 also acquires the second pulse wave m2 of the subject 15, which is measured simultaneously with the first pulse wave m1 by the second pulse wave measuring unit 8, and stores it in the RAM 4 (step 715).
Since the first pulse wave m1 and the second pulse wave m are continuously measured and input from the first pulse wave measuring section 7 and the second pulse wave measuring section 8, the CPU 2 continuously stores them in the RAM 4. ing.

Next, the CPU 2 calculates the delay time L (step 720). That is, the CPU 2 calculates the delay time L of the second pulse wave m2 with respect to the first pulse wave m1 stored in the RAM 4 and stores it in the RAM4.
FIG. 9 is a flowchart showing details of the delay time L calculation process.
The CPU 2 searches for the lowest value (trough) V1 of the first pulse wave m1 stored in the RAM 4 (step 805).
Furthermore, the CPU 2 obtains the time t1 of the searched lowest value (trough) V1 and stores it in the RAM 4 (step 810).

Next, the CPU 2 searches for the lowest value (trough) V2 from the second pulse wave m2 stored in the RAM 4 (step 815).
That is, the CPU 2 searches the second pulse wave m2 for the lowest value Va between time (t1-0.1) and time t1 and the lowest value Vb after time t1 (later time).
If there is no lowest value Va, the CPU 2 sets the lowest value Vb as the lowest value (valley) V2. On the other hand, if there is a lowest value Va, the CPU 2 sets the lowest value (valley) V2 to the one closer to the time t1 out of Va and Vb.

Furthermore, the CPU 2 obtains the time t2 of the searched lowest value (trough) V2 and stores it in the RAM 4 (step 820).
Next, the CPU 2 calculates the delay time L=t2-t1 from the times t1 and t2 stored in the RAM 4, stores it in the RAM 4 (step 825), and returns to the main routine.

Returning to FIG. 8, the CPU 2 determines whether or not the delay time L stored in the RAM 4 is greater than the reference value Th (0.08 seconds in this embodiment) (step 725). That is, the CPU 2 determines whether blood pressure measurement is possible at the current pulse wave measurement position (blood pressure measurement availability determination) depending on whether the delay time L is greater than the reference value Th.
If the delay time L is equal to or less than the reference value Th (step 725; N), the CPU 2 notifies that effect (step 730) and terminates the process.
Here, the notification made by the CPU 2 is, for example, displaying an image on the display 5 stating, "Please change the measurement position of the second pulse wave measuring unit 8 because accurate blood pressure measurement cannot be performed.", and/or This is done by outputting sound from a speaker.

On the other hand, if the delay time L is greater than the reference value Th (step 725; Y), the CPU 2 reads the parameters PS1 and PS2 for the systolic blood pressure SBP stored in the data 10b and sets them in the RAM 4 (step 735). ).
Next, the CPU 2 uses the set parameters PS1 and PS2 and the delay time L to calculate the systolic blood pressure SBP according to the formula (A) and stores it in the RAM 4 (step 740).
Systolic blood pressure SBP=PS1×delay time L+PS2 Equation (A)

CPU 2 also reads parameters PD1 and PD2 for diastolic blood pressure DBP from data 10b and sets them in RAM 4 (step 745).
The CPU 2 uses the set parameters PD1 and PD2 and the delay time L to calculate the diastolic blood pressure DBP according to the above equation (B), and stores it in the RAM 4 (step 745).
Diastolic blood pressure DBP=PD1×delay time L+PD2 Equation (B)
The CPU 2 outputs the calculated systolic blood pressure SBP and diastolic blood pressure DBP to the external device via the display 5 and the communication control section 11 (step 750), and ends the process.

In the first embodiment described above, the case where the delay time L is calculated using the lowest values V1 and V2 of the pulse waves m1 and m2 in the delay time calculation process described with reference to FIG. 9 has been described.
On the other hand, as described in FIG. 3, the delay time L can also be calculated using the maximum value (peak) T, the maximum slope D, and the correlation delay (delay of the entire pulse wave) C. It is possible.

When calculating the delay time L using the maximum value (peak) T for the delay time L, in the delay time calculation process of FIG. It is possible to deal with it by reading it as "T", "T".
The process of calculating the delay time L using the correlation delay (delay of the entire pulse wave) C of the pulse wave m will be described in the second embodiment.

On the other hand, when calculating the delay time L using the maximum slope D, processing different from that in FIG. 9 is required.
FIG. 10 is a flow chart of the delay time calculation process for calculating the delay time L using the maximum gradient D of the pulse wave m.
The CPU 2 calculates the differential (inclination D1) of the first pulse wave m1 stored in the RAM 4 (step 905).
Further, the CPU 2 calculates the differential (inclination D2) of the second pulse wave m2 stored in the RAM 4 (step 910).

Next, the CPU 2 searches for the maximum value of the calculated slope D1 (step 915).
Then, the CPU 2 obtains the time t1 of the maximum value of the searched gradient D1 and stores it in the RAM 4 (step 920).
The CPU 2 also searches for the maximum value of the slope D2 (step 925). That is, the CPU 2 searches for the maximum value Da of the slope between the time (t1-0.1) obtained in step 920 and the time t1, and the maximum value Db of the slope after the time t1 (later time). , the larger one of the maximum value Da and the maximum value Db is set as the maximum value of the slope D2.
Then, the CPU 2 obtains the time t2 of the maximum value of the searched gradient D2 and stores it in the RAM 4 (step 930).
Next, the CPU 2 calculates the delay time L=t2-t1 from the times t1 and t2 stored in the RAM 4, stores it in the RAM 4 (step 935), and returns to the main routine.

In the first embodiment described, using the delay time L obtained from the lowest values V1 and V2 of the pulse waves m1 and m2, blood pressure measurement determination (step 725, FIG. 9) and formulas (A) and (B) The case of determining the blood pressure (steps 740, 750) has been described. That is, the case where the same pulse wave element (minimum value V) is used for both blood pressure measurement determination and blood pressure determination has been described.
On the other hand, the delay time L used in determining whether blood pressure can be measured and the delay time L used in determining the blood pressure in formulas (A) and (B) can be obtained using another pulse wave element (VTDC). is also possible.
For example, the delay time LV calculated using the minimum value V determines whether blood pressure measurement is possible (step 725), and the blood pressure (SBP, DBP) is calculated using the delay time LD calculated using the maximum slope D of the pulse wave m. It is also possible to determine (steps 740, 750).
In this case, step 727 is added between steps 725 and 730 to "calculate the delay time L".
For the calculation of each delay time L in steps 720 and 727, the calculation of the delay time L described with reference to FIGS.

As described above, according to the blood pressure measuring device 1 according to the first embodiment and the modified example, the delay time L between the first pulse wave m1 and the second pulse wave m2 measured at positions different in distance from the heart is obtained, Depending on whether or not this delay time L is greater than the reference value Th, it is possible to determine whether blood pressure can be measured (blood pressure measurement availability determination).
When the delay time L is equal to or less than the reference value Th, a notification is given to prompt the user to perform measurement at another measurement position. It becomes possible to measure high systolic blood pressure SBP and diastolic blood pressure DBP.
The reference value Th for determining whether blood pressure measurement is possible can be selected in the range of 0.1 seconds to 0.06 seconds, and by selecting the optimum value Th = 0.08 seconds, more accurate determination is performed. be able to.
In addition, as the pulse wave element used when calculating the delay time L, any of the pulse wave minimum value V, maximum value T, maximum slope D, and correlation delay C can be used. By using the lowest value V, which is most susceptible to reflected waves (pulse waves returning to the heart), in determining whether measurement is possible, determination accuracy can be further increased.

Next, a second embodiment of the blood pressure measuring device 1 will be described.
(3) Overview of Second Embodiment A blood pressure measurement device 1 according to the second embodiment is an embodiment in which the first pulse wave and the second pulse wave are acquired without contact. In this second embodiment, the delay time LV obtained from the minimum value V of the pulse wave is used to determine whether or not the blood pressure can be measured. The lag time LC is used to determine the systolic blood pressure SBP and the diastolic blood pressure DBP.
In the blood pressure measurement device 1 of the second embodiment, a terminal device such as a smartphone is used to obtain a first pulse wave from a video of a face and a second pulse wave from a video of a finger. The following three features are used to estimate blood pressure from both pulse waves.

The blood pressure measuring device 1 (FIG. 12) photographs the face of the subject 15 with the front camera 7, and at the same time photographs the fingers of the subject 15 with the back camera 8 while illuminating the finger of the subject 15 with the illumination 9. to get face and finger videos.
The blood pressure measuring device 1 detects a face using the H and S components of the HSV color space, and acquires the facial pulse wave of the detected face using the Q component of the YIQ color space (feature 1). Reliability of the pulse wave can be improved by detecting the pulse wave with the Q value for the face subject to external light or motion disturbance, and detecting the pulse wave with the G value for the finger not subject to the disturbance.

Furthermore, the blood pressure measuring device 1 uses the entire waveform of the facial pulse wave and the entire waveform of the finger pulse wave to detect the delay time of the finger pulse wave with respect to the facial pulse wave. For detection, the finger pulse wave is shifted in the time direction with respect to the facial pulse wave, and the delay data points are specified from the shift amount with the highest cross-correlation. Further, the delay time L is calculated from the number of delay data points (characteristic 2).
Since the facial pulse wave and the finger pulse wave are originally the same pulse wave, if the finger pulse wave is shifted by the amount of delay, the waveform approximately matches the facial pulse wave. This is measured by cross-correlation, and the fact that the maximum shift amount corresponds to the delay time L is utilized.

In addition, the blood pressure measurement device 1 spline-interpolates facial and finger moving images taken at about 30 [fps: frames per second (frames per second)] to obtain facial pulse waves and finger pulse waves at 240 [fps]. fps], the cross-correlation is measured with high resolution from the face pulse wave and the finger pulse wave after interpolation (feature 3).
As a result, blood pressure can be measured with a high resolution of about 5 [mmHg], and can be put to practical use.
The relationship between the delay time L and the blood pressure is determined by experiments, and the blood pressure measurement device 1 applies the delay time L obtained by applying the features 1 to 3 to the relational expression obtained by the experiment to determine the blood pressure of the subject 15. to measure.

(4) Details of Second Embodiment The blood pressure measurement device 1 is configured by, for example, a mobile terminal such as a smart phone.
FIG. 11 is a diagram for explaining the configuration of the blood pressure measurement device 1 of this embodiment.
The blood pressure measurement device 1 is configured by a mobile terminal such as a smart phone, for example, and can measure the blood pressure of the subject 15 in a non-contact and non-invasive manner using a moving image of the subject 15 .
The blood pressure measurement device 1 includes a CPU (Central Processing Unit) 2, a ROM (Read Only Memory) 3, a RAM (Random Access Memory) 4, a display 5, a touch panel 6, a front camera 7, a rear camera 8, a lighting 9, and a storage unit 10. etc.

The CPU 2 is a central processing unit that performs various types of information processing and control according to programs stored in the storage unit 10, the ROM 3, and the like. In this embodiment, the blood pressure is detected using moving images of the subject 15 captured by the front camera 7 and the rear camera 8 .
The ROM 3 is a read-only memory and stores basic programs and parameters for operating the blood pressure measuring device 1 .
The RAM 4 is a readable/writable memory and provides a working memory when the CPU 2 operates. In this embodiment, the CPU 2 detects the blood pressure from the moving image by developing and storing the image data of the frame images (one frame of still image) constituting the moving image, or by storing the calculation result. Assist.

The display 5 is configured using, for example, a liquid crystal panel, and displays icons for selecting various application programs and various screens provided by these applications. In this embodiment, for example, the display 5 displays the measured blood pressure.
Here, the display 5 functions as display means for displaying blood pressure, and thus the blood pressure measuring device 1 has output means for outputting blood pressure to the display 5 .

The touch panel 6 detects the touch of the user's finger, and thereby accepts selection of icons and input to various input screens provided by each application.
In this embodiment, the blood pressure measurement device 1 detects a touch on an icon for starting the blood pressure measurement program 10a and uses it to start the blood pressure measurement program 10a. Detecting touch on the measurement start button and starting blood pressure measurement.

The front camera 7 and rear camera 8 are video cameras (still images can also be taken), and are constructed using an optical system composed of lenses and an image element that converts the image formed by the lens into an electrical signal. It is
The front camera 7 is arranged on the surface on which the display 5 is provided, and the rear camera 8 is arranged on the opposite rear surface.

The front camera 7 and the back camera 8 photograph the subject's face and fingers at a predetermined frame rate, respectively, and output a facial moving image and a finger moving image composed of these continuous frame images.
The frame image is composed of an array of picture elements (pixels), which are the minimum units that constitute the image.
Also, the illumination 9 is formed integrally with (or in close proximity to) the rear camera 8 and illuminates the object photographed by the rear camera 8 .

Here, the front camera 7 is arranged on the first side and functions as a first camera for photographing the subject's first body surface under environmental light or the like.
The rear camera 8 is arranged on the second side opposite to the first side, and functions as a second camera that photographs the second body surface of the subject while illuminating it with predetermined illumination light. there is

The storage unit 10 is configured using a storage medium such as a hard disk or EEPROM (Electrically Erasable Programmable Read-Only Memory), and contains a blood pressure measurement program for the CPU 2 to measure blood pressure, other programs, and various data video data such as face videos and finger videos).

The blood pressure measurement program is a program that causes the CPU 2 to perform blood pressure measurement processing.
The blood pressure measurement device 1 can provide various functions as a blood pressure measurement device by executing a blood pressure measurement program.
In addition, the CPU 2 stores moving image data of the moving image of the face captured by the front camera 7 and the moving image of the finger captured by the back camera 8 in the storage unit 10, and detects the blood pressure using this data.

In this way, the blood pressure measurement device 1 captures the first moving image of the subject's first body surface under ambient light with the first camera, and captures the subject's second body surface with the second camera. A moving image acquiring means for acquiring a second moving image photographed under a predetermined illumination light is provided. Here, for example, the first body surface is the subject's face and the second body surface is the subject's fingers.

Each figure of FIG. 12 is a figure for demonstrating the usage pattern of the blood-pressure measuring device 1 which concerns on this embodiment.
In the following, as an example, the blood pressure measurement device 1 is configured with a mobile terminal such as a smart phone.
A subject 15 who is to be measured for blood pressure holds the blood pressure measuring device 1 while bringing the fingerprint surface of the finger into contact with the rear camera 8, faces the front camera 7 toward his/her face, and holds the posture. Any finger that can be easily applied according to the position of the rear camera 8 may be used as the finger to be applied to the rear camera 8 .

The blood pressure measuring device 1 held in this way takes an image of the face of the subject 15 with the front camera 7 and at the same time, images the fingers of the subject 15 with the rear camera 8 .
At this time, the finger is photographed while operating the illumination 9 to illuminate the fingerprint surface.
In the present embodiment, the fingers are photographed because they are easy to photograph, but blood pressure can also be measured at other sites such as the palm, the back of the hand, or the wrist.

The blood pressure measurement device 1 is affected by disturbance due to changes in the ambient light because the facial moving images captured by the front camera 7 are captured under ambient light such as outdoors or indoor lights. In addition, since the front camera 7 is held facing the face, the camera is also affected by motion disturbance in which the face moves within the screen due to hand shake.
On the other hand, the finger moving image captured by the back camera 8 is not affected by these disturbances because the finger is brought into close contact with the back camera 8 under the illumination of the illumination 9 .

Therefore, the blood pressure measuring device 1 detects the pulse wave from the temporal change of the Q value (the value of the Q component in the YIQ color space) that is robust against these disturbances for the face moving image, and detects the pulse wave for the finger moving image. A pulse wave is detected from the time change of the G value (the value of the G component in the RGB color space) suitable for detecting changes in blood flow.
The blood pressure measuring device 1 has three features, features 1 to 3, in order to detect the blood pressure well. .

In this way, the blood pressure measurement device 1 obtains the first pulse wave from the first moving image and the second moving image by using different types of temporal changes in color components from each of the first moving image and the second moving image. A pulse wave acquiring means for acquiring a second pulse wave from the second moving image is provided.
Then, the pulse wave obtaining means obtains a first pulse wave using the Q component included in the YIQ components from the first moving image, and obtains the second pulse wave using the G component included in the RGB components from the second moving image. to obtain the pulse wave of

As for the moving image of the face, the blood pressure measuring device 1 first converts the face frame image 31, which is the frame image of the moving image of the face captured by the front camera 7, from the RGB color space to the HSV color space, as shown in FIG. 12(a). Convert.
Then, when a region in which the H value of the H component and the S value of the S component are within a predetermined range is extracted, as shown in the face frame image 31b, the face region (pulse wave ) can be extracted. The fact that the H component and the S component can satisfactorily extract the face region is based on the new findings of the inventors of the present application.

Next, the blood pressure measuring device 1 converts the face frame image 31 from the RGB color space to the YIQ color space, obtains the Q value of each pixel in the measurement area 26 in the converted face frame image 31c, and averages these values. .
Obtaining the Q values averaged from each face frame image 31 constituting the face moving image in this way provides a time series of Q values, which becomes a face signal representing the pulse wave of the face (hereinafter referred to as the face pulse wave). Thus, the blood pressure measuring device 1 uses the Q channel of YIQ for the facial pulse wave.

As for the finger moving image, the blood pressure measuring device 1, as shown in FIG. Get the G values of the pixels and average them.
Obtaining the average G value from each finger frame image 32 constituting the finger moving image in this way provides a time series of G values, which becomes a finger signal representing the pulse wave of the finger (hereinafter referred to as finger pulse wave). In this way, the blood pressure measurement device 1 uses the RGB G channel for the finger pulse wave.

Each diagram in FIG. 13 is a diagram for explaining the inversion of the finger signal.
FIG. 13(a) shows temporal changes in amplitude of the finger signal 16 and the face signal 18. FIG.
For technical reasons, the amplitude of the finger signal 16 is detected inverted with respect to the amplitude of the face signal 18 . Therefore, the blood pressure measurement device 1 inverts the amplitude of the finger signal 16 to generate the finger signal 17 as shown in FIG. 13(b), and uses this to perform blood pressure measurement processing.
In this way, the pulse wave acquisition means provided in the blood pressure measurement device 1 acquires the second pulse wave using the value obtained by inverting the G component.

Each figure of FIG. 14 is a figure for demonstrating the delay of propagation of a pulse wave.
Generally, the propagation velocity of a pulse wave is about 6.84 [m/s].
According to this, since the distance from the heart to the face is about 0.3 m, the pulse wave propagation time from the heart to the face is about 0.0439 [s].
Also, since the distance from the heart to the finger is about 1 [m], the propagation time of the pulse wave from the heart to the finger is about 0.1462 [s].

As a result, the finger pulse wave lags behind the facial pulse wave by about 0.1023 [s]. The magnitude of the delay time (delay time) L due to this delay correlates with the magnitude of the blood pressure, and the blood pressure measurement device 1 measures the delay time L to obtain the blood pressure.
Thus, the blood pressure measuring apparatus 1 includes blood pressure acquisition means for acquiring the blood pressure of the subject using the propagation delay between the first pulse wave and the second pulse wave.

Since the blood pressure measuring device 1 detects the magnitude of such minute delay times, the band-pass filter removes unnecessary signals while maintaining the original shapes of the facial pulse wave and the finger pulse wave as much as possible.
FIG. 14A shows a finger signal 19 obtained by filtering the finger signal 17 and a face signal 20 obtained by filtering the face signal 18. FIG.

As shown in FIG. 14(a), the finger signal 19 and the face signal 20 have waveforms close to the original pulse wave due to the filtering process, which is suitable for comparison.
Since the blood pressure measuring device 1 detects the delay based on the correlation using the entire waveforms of the facial pulse wave and the finger pulse wave, by making the waveforms of the finger signal 19 and the facial signal 20 as original as possible, The delay time L can be detected more precisely.

In this way, the blood pressure measuring device 1 uses the entire waveform of the first pulse wave and the entire waveform of the second pulse wave to measure the propagation between the first pulse wave and the second pulse wave. delay acquisition means (delay time acquisition means) for acquiring the delay of
Then, the delay acquisition means acquires the propagation delay using the correlation between the waveform of the first pulse wave and the waveform of the second pulse wave.

FIG. 14(b) shows the cross-correlation with respect to the delay time L of the finger signal 19 with respect to the face signal 20. FIG.
The blood pressure measurement device 1 uses cross-correlation, which will be described later, as the correlation between the face signal 20 and the finger signal 19 .
The cross-correlation shifts the finger signal 19 with respect to the face signal 20 in the time axis direction, and the cross-correlation in that case, that is, how close the waveform shapes of the face signal 20 and the finger signal 19 are as a whole at the time of the shift. This is a plot of an index that indicates whether The delay time L is the amount of shift when the cross-correlation is the largest, that is, when the waveform shapes are the closest overall.

In this embodiment, the finger signal 19 is moved in the time direction with respect to the face signal 20. However, since both signals need only be moved relatively, the face signal 20 is moved with respect to the finger signal 19. Alternatively, both the finger signal 19 and the face signal 20 may be moved in the time direction.
Thus, the delay acquisition means acquires the correlation for each shift while shifting at least one of the waveform of the first pulse wave and the waveform of the second pulse wave in the time direction, The shift amount that maximizes the correlation is acquired as the propagation delay.

By the way, if the corresponding frames of the face frame image 31 and the finger frame image 32 are shot at the same time, if the finger signal 19 is shifted forward by the delay time, the cross-correlation will be maximized. The delay time L can be obtained from the shift amount that maximizes the correlation.
However, in a general portable terminal, the timing of photographing the face frame image 31 and the finger frame image 32 may differ, and this difference in photographing timing affects measurement of the delay. In some cases, the finger pulse wave may be transmitted faster than the facial pulse wave.

Therefore, the blood pressure measuring device 1 shifts the finger signal 19 in any direction to calculate the cross-correlation, and searches for peaks in areas where the delay is greater than 0 (because the finger pulse wave always lags behind the facial pulse wave). ), which is the delay time.
If the shooting timing of the front camera 7 and the rear camera 8 can be adjusted, it can be adjusted. , the propagation is delayed farther from the heart) is constant, and the delay time is constant, the delay time can be obtained by peak search in this way.

In the example of the figure, the cross-correlation peak is -0.0375 [s], but if you search for a peak in the range of delay time > 0, the delay of the right adjacent peak that satisfies the condition will be the delay time L. becomes.
In this manner, the blood pressure measurement device 1 can determine the correlation within the range in which the pulse wave acquired from the moving image captured on the body surface farther from the heart, out of the waveform of the first pulse wave and the waveform of the second pulse wave, is delayed. A peak is searched, and the shift amount is obtained from the position of the searched peak.

FIG. 15 is a diagram showing a cross-correlation formula.
In the following, to prevent erroneous conversion of character codes, subscripts of formulas are written with normal characters.
In this embodiment, the cross-correlation calculation formula is defined by RS1S2 of formula (1) shown in FIG. 15(a). S 1 represents the finger signal 19 and S 2 represents the face signal 20 .

m is the number of data points to shift S1 with respect to S2, and N is the total number of data points.
When m is 0 or more, S1(n+m)×S2(n) from n=0 with m=0, 1, 2, . The cross-correlation for each m can be calculated by adding up to n=N−m−1.
For example, FIG. 15(b) shows the case of m=1, in which case the cross-correlation is S1(1) S2(0)+S1(2) S2(1)+ . . . +S1(N− 1) As S2(N-2), it is possible to calculate the cross-correlation of the finger signal 19 with respect to the face signal 20 shifted by one data point to a younger data point.
Thus, for each increment of m, the cross-correlation of the finger signal 19 shifted one data point to the younger data point can be calculated.

On the other hand, when m is negative, the sign of m is inverted and S1(n+m)×S2(n) is changed from n=-m to N Calculate the cross-correlation by adding up to -1.
For example, FIG. 15(c) shows the case of m=−1, in which case the cross-correlation is S1(0)S2(1)+S1(1)S2(2)+ . . . +S1(N -2) As S2(N-1), the cross-correlation of the finger signal 19 shifted forward by one data point with respect to the face signal 20 can be calculated.
Thus, for each decrement in m, a cross-correlation can be calculated that shifts the finger signal 19 forward by one data point.

Since the finger data is delayed more than the face data, in this embodiment, at least the data points of the finger data are shifted to the younger side with respect to the data points of the face data, and m that maximizes the cross-correlation is obtained.
A suitable value for the maximum value M of m can be obtained through experiments. In this embodiment, for example, when using a resolution equivalent to 240 [fps], which will be described later, M=480 as an example.

Note that formula (1) is an example and various modifications are possible. For example, in equation (1), the relative positions of the finger signal 19 and the face signal 20 are shifted in the time direction, and all overlapping data points are calculated and added. data points may be calculated and added.
Also, other calculation formulas can be adopted as long as the similarity of the entire waveforms is measured while moving at least one of the two signals in the time direction. In this case, the delay time L corresponds to the amount of relative movement in the time direction when both waveforms are most similar.

Considering the case where the corresponding frames of the front camera 7 and the rear camera 8 are not shot at the same time, or the case where the delay < 0 due to some relationship such as conversion of the color space, the time axis is shifted in the positive and negative directions in this way. Then, the condition that the finger signal lags behind the face signal can be satisfied by searching for the peak in the region where lag>0.

When the cross-correlation defined in this way is calculated, when the finger signal 19 is shifted with respect to the face signal 20, a large value is obtained when the waveform of the face signal 20 and the waveform of the finger signal 19 are generally close to each other. , is a small value if it is not close.

As described above, since the blood pressure measuring apparatus 1 measures the delay time based on the entire waveforms of the finger signal 19 and the face signal 20, it is less susceptible to external disturbances, and the delay time can be determined simply from the peaks of the finger signal 19 and the face signal 20. It is possible to measure the delay time more accurately and robustly than it is desired.

Each diagram in FIG. 16 is a diagram showing an example of cross-correlation.
The black circles in the figure represent the face data points forming the face signal 20, and the black triangles represent the finger data points forming the finger signal 19, which are created from the face frame image 31 and the finger frame image 32, respectively. It is.

FIG. 16(a) shows the case where the delay (shift amount of the finger signal 19) is 0 data points. In this case, the cross-correlation of both waveforms is not good and has a negative value.
FIG. 16B shows the case where the delay is 4 data points. In this case, the cross-correlation is improved to a value of about 0 as compared to the case where the delay is 0 data points.

After that, as shown in FIGS. 16(c) to 16(f), the cross-correlation increases as the number of delay data points becomes 8 and 12, and decreases as the number of delay data points becomes 16 and 20. FIG.
In the example of this figure, since the waveform shapes of the finger signal 19 and the face signal 20 generally match around 12 data points, the delay time L is estimated to be around 12 data points.

FIG. 17 is a diagram showing the relationship between the number of delay data points and the cross-correlation according to the example of FIG.
In the example of FIG. 166, when the cross-correlation is plotted against the number of lag data points, the cross-correlation becomes maximum when the number of data points is 11.
In this data example, if the delay time corresponding to 11 data points is positive, this time becomes a candidate for the delay time (as described later, the limit is 0 < peak delay time L < 1.1 seconds). ).
As described above, the method of measuring the delay time using the entire waveforms of the finger signal 19 and the face signal 20 without measuring the delay time L based on the peaks of the finger signal 19 and the face signal 20 constitutes the second feature.

By the way, the cross-correlation can be obtained discretely according to the number of data points in this way, which limits the resolution of the delay time L. FIG.
Since this discrete interval is defined by the frame rate of the face moving image and the finger moving image, if the raw data of the finger signal 19 and the face signal 20 are used as they are, the delay time L is higher than the resolution defined by the frame rate. cannot be calculated with precision.

For example, the delay of the finger signal 19 with respect to the face signal 20 is about 0.1 [s], but the frame rate of moving images that can be captured by a mobile terminal that is generally used is about 30 [fps]. Only about 3 frames can be photographed during 1 [s]. With this resolution, only a resolution of about 40 [mmHg] can be obtained.
In addition, even if the model is capable of increasing the frame rate, since the imaging device is not designed for a high frame rate, the image deteriorates, making it difficult to measure blood pressure with high resolution. .

The blood pressure measurement device 1 needs a frame rate of about 240 [fps] to measure blood pressure with a resolution of at least about 5 [mmHg].
Therefore, the blood pressure measurement device 1 interpolates the discrete data of the finger signal 19 and the face signal 20 acquired at the moving image frame rate, and samples this to create data points equivalent to 240 [fps]. .

Although there are various data interpolation methods, spline interpolation is used as an example here. This is because the pulse wave is a natural phenomenon caused by a living organism, and spline interpolation is suitable for smoothly connecting data without discontinuous abnormal values between data. Note that other interpolation methods such as Bezier interpolation may be used.

Each diagram in FIG. 18 is a diagram for explaining the interpolation of the pulse wave.
As shown in FIG. 18A, the face data points indicated by black circles and the finger data points indicated by black triangles before interpolation are 0.1 [ s], the values are discontinuous at about three time intervals.

On the other hand, as shown in FIG. 18(b), the blood pressure measuring device 1 interpolates the face data and the finger data by spline interpolation, samples the values on the interpolated curve, and obtains 240 fps equivalent. data points. This can generate 24 data points per 0.1 second.
Face data and finger data generated by interpolation are shown by solid lines and dashed lines, respectively, because the time intervals are too small to be shown by black circles or black triangles.

More specifically, the blood pressure measuring device 1 generates a spline curve 38 using face data points 36, 36, . . . Acquire face data points 37, 37, . . . corresponding to 240 [fps].
The blood pressure measurement device 1 similarly obtains spline-interpolated finger data points for finger data points.
Then, the blood pressure measuring device 1 calculates the cross-correlation using the whole interpolated face signal and finger signal.

In this way, the pulse wave acquiring means of the blood pressure measurement device 1 determines the frame rate of the first moving image, 2, a discrete first pulse wave and a discrete second pulse wave are acquired according to the frame rate of the moving image.
The blood pressure measuring device 1 has an interpolating means for interpolating discrete values of the first discrete pulse wave and the second discrete pulse wave.
Furthermore, the delay acquisition means of the blood pressure measurement device 1 acquires the first pulse wave using the entire interpolated waveform of the first pulse wave and the entire interpolated waveform of the second pulse wave. Acquiring the propagation delay during the second pulse wave.

FIG. 19 is a diagram for explaining the effect of cross-correlation interpolation.
FIG. 19A shows the cross-correlation before interpolation acquired from the face frame image 31 and the finger frame image 32 captured at 29 [fps]. From the cross-correlation sequence before correction, it is possible to search for the delay time peak in units of 1/29 seconds. The example of the figure is a schematic diagram, and according to this, the maximum delay data point is 11, which is about 0.379 [s] when converted to time.

FIG. 19B shows cross-correlation between face data points and finger data points interpolated at 240 [fps]. From the interpolated correlation sequence, it is possible to search for the peak of the delay time in units of 1/240 seconds with higher resolution. In the example shown, the maximum delay data point is 87, which translates to approximately 0.3625 seconds. This value is closer to the true value.

As described above, the blood pressure measurement device 1 can improve the resolution of the delay time L due to cross-correlation by interpolating the data points.
Feature 3 is a method of improving the resolution by spline-interpolating each data point of the finger signal 19 and the face signal 20 .

FIG. 20 is a diagram for explaining optimization of the bandpass filter.
When calculating the cross-correlation, it is desirable to leave waveforms derived from pulse waves as much as possible and exclude waveforms derived from other causes.
Therefore, the blood pressure measurement device 1 filters the finger signal 19 and the face signal 20 before interpolation using a bandpass filter.

The figure shows experimental values of cross-correlation with respect to the cutoff frequency on the lower limit side of the passband. As shown in the figure, when the frequency is about 20 [bpm: beats per minute (pulse rate per minute)] or less, the influence of factors other than pulse waves is large, so the cross-correlation value decreases sharply, making accurate measurement difficult. This is a low-correlation region where it is not possible to perform
The pulse rate region is 40 [bpm] or higher, and good cross-correlation can be obtained from around 20 [bpm].

As a result of trial and error, the inventor of the present application found that 20 [bpm] is appropriate for the lower limit of the passband of the bandpass filter.
Similarly, it was found that 250 [bpm] is appropriate for the upper limit of the passband.
Therefore, the blood pressure measuring device 1 employs a bandpass filter with a pass band of 20 to 250 [bpm].

21 and 22 are flowcharts for explaining the overall flow of blood pressure measurement processing performed by the blood pressure measurement device 1. FIG.
The following processing is performed by the CPU 2 according to the blood pressure measurement program stored in the storage unit 10. FIG.
First, the CPU 2 performs moving image frame reading processing (step 5).
In this process, both the front camera 7 and the back camera 8 are operated, and the face moving image taken by the front camera 7 and the finger moving image taken by the back camera 8 are stored in the storage unit 10 or the like, and read into the RAM 4. is.

Next, the CPU 2 performs parameter setting/initialization processing for setting the band-pass filter and setting other parameters (step 10).
Next, the CPU 2 extracts a face area by detecting skin in the face frame image 31, and performs measurement area setting processing for setting this as a measurement area (step 15).
Then, the CPU 2 performs face signal acquisition processing for acquiring a face signal using the Q value of the measurement area (step 20).

Next, when there is a face frame image 31 for which face signal acquisition processing has not yet been performed (step 25; N), the CPU 2 returns to step 15 and performs face signal acquisition processing on all face frame images 31. If so (step 25; Y), the spectrum of the face signal is subjected to frequency analysis by FFT (fast Fourier transform) to perform face signal spectrum calculation processing (step 30).

Then, the CPU 2 performs face pulse rate detection processing for detecting the face pulse rate from the spectrum of the face signal (step 35), and then calculates the signal strength of the detected face pulse rate by calculating the S/N ratio of the face signal. face signal intensity evaluation processing is performed (step 40).

The steps 30 to 40 described above are processes for evaluating the reliability of the facial signal based on the S/N ratio. The signal is weak and the blood pressure cannot be measured" is displayed on the display 5 (step 50), and the process is terminated.

On the other hand, when the reliability of the face signal is sufficient (step 45; Y), the CPU 2 performs finger signal acquisition processing for acquiring the finger signal using the G value of the finger frame image 32 (step 55).
Next, when there is a finger frame image 32 for which finger signal acquisition processing has not yet been performed (step 60; N), the CPU 2 returns to step 55 and performs finger signal acquisition processing on all finger frame images 32. If so (step 60; Y), a finger signal spectrum calculation process for frequency analysis of the spectrum of the finger signal by FFT is performed (step 65).

Then, the CPU 2 performs finger pulse rate detection processing for detecting the finger pulse rate from the spectrum of the finger signal (step 70), and then calculates the signal strength of the detected finger pulse rate by calculating the S/N ratio of the finger signal. is performed (step 75).

The above steps 65 to 75 are processes for evaluating the reliability of the finger signal based on the S/N ratio. Next, when the reliability of the finger signal is not sufficient (step 80; N), The signal is weak and the blood pressure cannot be measured" is displayed on the display 5 (step 95), and the process is terminated.

On the other hand, if the reliability of the finger signal is sufficient (step 80; Y), the CPU 2 performs preprocessing (hereinafter referred to as , facial finger signal preprocessing) is performed (step 85).

Next, the CPU 2 calculates the delay time L using the lowest value (trough) V of the pulse wave (face signal, finger signal) (step 720), and determines whether blood pressure measurement is possible (step 725).
If CPU 2 cannot determine whether blood pressure measurement is possible (step 725; N), CPU 2 notifies that effect (step 730), and terminates the process.
The details of each process of steps 720, 725, and 730 are the same as those of the first embodiment described with reference to FIG. 8, and therefore are omitted.

In this embodiment, the pulse wave is measured while the fingerprint surface of the finger is in contact with the rear camera 8 .
Therefore, in the notification at step 730, the content of the notification can be changed according to the second embodiment, for example, "Since accurate blood pressure measurement cannot be performed, please place the rear camera 8 in contact with another position." preferable.

On the other hand, if it is possible to determine whether or not blood pressure measurement is possible (step 725; Y), the CPU 2 performs blood pressure measurement processing for measuring blood pressure using the face signal and the finger signal that have undergone face and finger signal preprocessing in step 85. (Step 90), the blood pressure measurement process is terminated.

Details of each process described with reference to FIGS. 21 and 22 will be described below.
FIG. 23 is a flowchart for explaining the moving image frame reading process in step 5 (FIG. 21).
First, the CPU 2 reads the moving image data of the face moving image and the finger moving image stored in the storage unit 10 into the RAM 4 (step 105).
Next, the CPU 2 acquires the frame rates of these moving images and stores them in the RAM 4 (step 110). The frame rate is attached to the face video and finger video files (may be calculated from the shooting time and the number of frames), and is obtained by reading this. In this embodiment, it is assumed that both moving images have the same frame rate, but they may have different frame rates.

Next, the CPU 2 obtains the number of frames of each moving image and stores it in the CPU 2 (step 115).
Next, the CPU 2 creates a time vector to be used later in FFT based on the frame rate stored in the RAM 4 in step 110 and the length (time) of the moving image for each of the face moving image and the finger moving image. are prepared and stored in the RAM 4 (step 120), and the process returns to the main routine.

FIG. 24 is a flow chart for explaining the parameter setting/initialization process in step 10 (FIG. 21).
First, the CPU 2 stores and sets parameters for setting the measurement area in the RAM 4 (step 125).
This extracts the face area in the HSV color space using the H and S values, and sets the H value range and the S value range for that purpose. The upper and lower limits of these H value and S value were determined by the inventor of the present application through experiments.

Next, the CPU 2 stores and sets a bandpass filter (BPF) stabilization time in the RAM 4 (step 130).
This sets the stabilization time until the signal stabilizes, because when a band-pass filter is applied to the signal, the first output value cannot be obtained due to digital processing. The portion of the band-pass filtered signal up to the stabilization time is deleted. Here, 2 seconds is set as the stabilization time.

Next, the CPU 2 stores and sets the frequency region of the bandpass filter in the RAM 4 (step 135). As described above, the frequency range is set to 20-250 [bpm] here.
CPU 2 then prepares the parameters of the filter by storing the transfer function in RAM 4 (step 140).

Next, the CPU 2 stores and sets standards of reliability (S/N ratio) for the face signal and the finger signal in the RAM 4 (step 145). Here, as an example, both signals have a reliability standard of 0.

Next, the CPU 2 stores and sets definition parameters of elements of morphological closing in the RAM 4 (step 150).
Here, a round-shaped element with 10 pixels was defined as a defining parameter.
Morphological closing is a process of filling a figure or joining a cut part by performing a dilation process and an erosion process based on defined elements.

For example, when wearing glasses with thick rims, the face is divided by the glasses and recognized as four parts: the forehead, the left and right eyes, and the part below the nose. , can be combined into one mass (a group of parts) by filling in the eyeglass part by morphological closing.
By morphological closing, the CPU 2 recognizes the four areas of the forehead, the left and right eyes, and the part below the nose as the face area, and sets these four areas as the measurement areas. be able to.

FIG. 25 is a flowchart (a) and an explanatory diagram (b) for explaining the measurement area setting process in step 15 (FIG. 21).
Steps 160 and 165 in FIG. 25(a) are steps for acquiring the face frame image 31 of the face moving image. is included, the CPU 2 selects the unprocessed frame with the shortest shooting time (step 160), extracts an image limited to the face area (step 165), and uses it as a face frame image 31 is stored in the RAM 4.
On the other hand, when the face moving image and the finger moving image are different moving images, the unprocessed face frame image 31 with the youngest photographing time is obtained from the facial moving image and stored in the RAM 4 .

Then, the CPU 2 converts the color space of the face frame image 31 stored in the RAM 4 from the RGB color space to the HSV color space, and stores the converted HSV image data in the RAM 4 (step 170).

Next, the CPU 2 reads from the RAM 4 the reference values for the upper and lower limits of the H component set in step 125 of FIG.
Then, the CPU 2 creates an H mask (BWH) for extracting (extracting) a region in which the H component is within the range of the upper and lower limit reference values in the HSV image, and stores it in the RAM 4 (step 175).

Further, the CPU 2 reads from the RAM 4 the reference values for the upper and lower limits of the S component set in step 125 of FIG.
Then, the CPU 2 creates an S mask (BWS) for extracting an area in the HSV image in which the S component is within the range of the upper and lower limit reference values, and stores it in the RAM 4 (step 180).

Next, the CPU 2 synthesizes the H mask (BWH) and the S mask (BWS) stored in the RAM 4 by logical product, and extracts an HS mask for extracting a region in which both the H component and the S component are within the respective reference values. (BWH×BWS) is created and stored in RAM 4 (step 185).

Next, the CPU 2 uses the HS mask stored in the RAM 4 to extract a region in which both the H component and the S component are within the reference values from the HSV image, thereby obtaining a mass region (a mass of exposed skin). 190).

When a blob area is detected in step 190 (step 195; Y), the CPU 2 selects up to four blob areas (bigBlobs) (step 200).
The reason why the maximum number is four is that in the case of the subject 15 wearing eyeglasses, the face may be divided by the edges of the eyeglasses and detected as four lump areas.

Next, the CPU 2 reads the parameters set in step 150 of FIG. 24 from the RAM 4, and uses them to perform morphological closing processing on the selected block region (step 205).
As a result, when the four mass regions are a face divided by eyeglasses, since these are close to each other, the eyeglasses are filled into one region by morphological closing.

Next, CPU 2 identifies the largest blob region (bigBlobf) after morphological closing (step 210).
As a result, regardless of whether glasses are worn or not, the face region can be specified as the largest mass region.

Then, the CPU 2 sets the pulse rate measurement area (bigBlob) by the logical product of bigBlobs and bigBlobf (bigBlobs×bigBlobf) (step 215).
As a result, the whole face becomes the pulse measurement area when the eyeglasses are not worn, and these four areas become the pulse measurement areas when the eyeglasses are worn and the face is divided into four parts.

Then, the CPU 2 stores the measurement area in the RAM 4 as a matrix in which the pixels in the measurement area are 1 and the other pixels are 0.
In this way, the CPU 2 sets a mass area within a range that can be grouped by morphological closing as a pulse rate measurement area.

In the example of FIG. 12(a), from the original face frame image 31 showing the background, clothes, etc., a mass region 25 around the face and neck where the skin is exposed is extracted, and the mass region 25 is measured as a measurement region 26. can be set to

On the other hand, if no lump area is detected (step 195; N), the CPU 2 stores the measurement area as a zero matrix in the RAM 4 (step 220).
After performing the above processing, the CPU 2 returns to the main routine.

FIG. 26 is a flow chart for explaining the face signal acquisition process of step 20 (FIG. 21).
First, the CPU 2 calculates the size (area) of the measurement region by the number of pixels and stores it in the RAM 4 (step 230).
Next, CPU 2 determines whether or not the size of the measurement area stored in RAM 4 is larger than the reference value (step 235).
This reference value is the area for the frame above which the pulse rate can be measured, and is set to, for example, 5% of the frame.

If the size of the measurement area is larger than the reference value (step 235; Y), the CPU 2 converts the face frame image 31 stored in the RAM 4 in step 165 (FIG. 25) from the RGB color space to the YIQ color space. YIQ image data is stored in RAM 4 (step 240).

Next, the CPU 2 adjusts the Q value of each pixel of the YIQ image data using camera characteristics prepared in advance (step 245). The camera characteristics are characteristics used to correct variations in the Q value of pixels originating from the imaging device.
Next, the CPU 2 calculates the logical product of the Q matrix whose components are the Q values of each pixel of the YIQ image data and the matrix of the measurement area stored in the RAM 4 in step 215 (FIG. 25), thereby obtaining the Q matrix. Limit to the measurement area (step 250).
The limited Q matrix has a Q value only in the measurement area, and the color component is 0 in other areas.

Next, the CPU 2 averages the Q values of the measurement region by calculating the average of the Q values of the limited Q matrix, and stores the average Q values in the RAM 4 (step 255). This Q value becomes the data point of the face signal. By repeating step 255, the time series of data points is stored in RAM 4 and becomes the face signal.

On the other hand, if the size of the measurement area does not satisfy the reference value (step 235; N), the CPU 2 determines whether the face frame image 31 is not the first frame image of the moving image (step 260).
If it is not the first frame image (step 260; Y), that is, if it is the second or later frame image of the moving image, the CPU 2 determines that the Q value is equal to the previous Q value because the size of the measurement area is not sufficient. , the previous Q value is adopted as the current estimate (step 265). This is because the pulse rate does not change significantly in the time interval of one frame rate, so the previous Q value and the current Q value do not differ greatly, so the current Q value is substituted with the previous Q value. It is.

On the other hand, if the face frame image 31 is the first frame image of the moving image (step 260; N), the CPU 2 sets the Q value to 0 and stores it in the RAM 4 (step 270).
After performing the above processing, the CPU 2 returns to the main routine.

FIG. 27 is a flow chart for explaining the facial signal spectrum calculation process of step 30 (FIG. 21).
First, the CPU 2 calculates the linear trend of the Q value, subtracts it from the original Q value, and stores the subtracted Q value in the RAM 4 (step 280). Below, the Q value after this subtraction is used.

Next, the CPU 2 uses the parameters prepared in step 120 (FIG. 23) to create time vectors of equal intervals (for example, 1 second) and stores them in the RAM 4 (step 285).
Furthermore, the CPU 2 interpolates the Q value so as to correspond to the created time vector and stores it in the RAM 4 (step 290). These are the preprocessing necessary for the FFT computation.
Then, the CPU 2 executes FFT using the time vector stored in the RAM 4 and the interpolated Q value to calculate the spectrum of the face signal and store it in the RAM 4 (step 295).

Next, the CPU 2 limits the spectrum of the face signal stored in the RAM 4 to the pulse rate measurement region, stores the limited spectrum of the face signal in the RAM 4 (step 300), and returns to the main routine. This pulse rate measurement area is, for example, 40 to 200 [bpm].

FIG. 28 is a flow chart for explaining the facial pulse rate detection process of step 35 (FIG. 21).
CPU 2 searches for the maximum peak in the spectrum stored in RAM 4 in step 300 (FIG. 27) (step 310).
Next, the CPU 2 calculates the frequency of the searched maximum peak, stores it in the RAM 4 as the pulse rate peak (step 315), and returns to the main routine. The pulse rate peak corresponds to the pulse rate of the fundamental wave of the facial pulse wave.

FIG. 29 is a flow chart (a) and an explanatory diagram (b) for explaining the face signal strength evaluation process of step 40 (FIG. 21).
First, the CPU 2 creates a fundamental wave mask (HR_M1) within a range of ±5 [bpm] as shown in FIG. and store it in RAM 4 (step 330).

Next, the CPU 2 similarly creates a ±5 [bpm] mask (HR_M2) as shown in FIG. 29(b) for harmonics of the fundamental wave and stores it in the RAM 4 (step 335).
Then, the CPU 2 creates one signal mask (HR_M) by combining HR_M1 and HR_M2 stored in the RAM 4 in steps 330 and 335, and stores it in the RAM 4 (step 340).

Next, the CPU 2 creates a disturbance mask (HRN_M=1-HR_M) covering areas other than the fundamental wave and harmonics, and stores it in the RAM 4 (step 345).
Then, the CPU 2 normalizes the spectrum of the face signal stored in the RAM 4 in step 300 (FIG. 27) and stores it in the RAM 4 (step 350).
If the normalized face signal spectrum is FFT_HRn, this is the value obtained by dividing the face signal spectrum FFT_HR by the maximum value of FFT_HR.

Next, the CPU 2 calculates num, which is a term used when calculating the S/N ratio, and stores it in the RAM 4 (step 355).
num is a value corresponding to the power of the masked fundamental wave and harmonics in the spectrum of the normalized face signal, and is obtained by multiplying the square of FFT_HRn(i) by HR_M(i) and taking the sum at i. It is. i is a parameter that specifies the discrete values of FFT_HRn and HR_M.

Next, the CPU 2 calculates den, which is another term used when calculating the S/N ratio, and stores it in the RAM 4 (step 360).
den is a value corresponding to the power of the region other than the masked fundamental wave and harmonics in the spectrum of the normalized face signal, which is obtained by multiplying the square of FFT_HRn(i) by HRn_M(i) and summing it by i. is taken.

Next, the CPU 2 reads num and den stored in the RAM 4 in steps 355 and 360, calculates the S/N ratio, and stores it in the RAM 4 (step 365).
The signal-to-noise ratio (HR_SNR) is calculated by multiplying the common logarithm of the ratio of num to den by ten.

FIG. 30 is a flowchart (a) and an explanatory diagram (b) for explaining the finger signal acquisition process of step 55 (FIG. 22).
Steps 380 and 385 are steps for acquiring the finger frame image 32 of the finger moving image. , the CPU 2 selects the frame with the shortest shooting time from among the unprocessed frames (step 380), extracts the image limited to the finger area (step 385), and stores it in the RAM 4 as the finger frame image 32. .
On the other hand, when the face moving image and the finger moving image are different moving images, the unprocessed finger frame image 32 with the youngest photographing time is obtained from the finger moving image and stored in the RAM 4 .

Next, the CPU 2 limits each pixel of the finger frame image 32 to the G channel, obtains the G value of each pixel, and stores it in the RAM 4 (step 390).
Then, the CPU 2 averages the G value of each pixel stored in step 390, stores it in the RAM 4 (step 395), and returns to the main routine. This G value becomes the data point of the finger signal. By repeating step 395, the time series of data points is stored in RAM 4 and becomes the finger signal.

After storing the average G value in the RAM 4, the CPU 2 performs finger signal spectrum calculation processing (FIG. 22, step 65), finger pulse rate detection processing (FIG. 22, step 70), and finger signal strength evaluation. Processing (FIG. 22, step 75) is performed, and these processings are face signal spectrum calculation processing (FIG. 27), face pulse rate detection processing (FIG. 28), and face signal strength evaluation processing (FIG. 29). Since they are the same, the description is omitted.

FIG. 31 is a flow chart for explaining the face finger signal preprocessing of step 85 (FIG. 22).
First, the CPU 2 reads out the frequency range (20 to 250 [bpm]) stored in the RAM 4 in step 135 (FIG. 24).
Then, a band-pass filter in the frequency domain is applied to the face signal stored in RAM 4 in step 255 (FIG. 26), and the filtered face signal is stored in RAM 4 (step 410).

Next, CPU 2 similarly applies the bandpass filter to the finger signal stored in RAM 4 in step 395 (FIG. 30), and stores the filtered finger signal in RAM 4 (step 415).

Next, the CPU 2 reads out the stabilization time stored in the RAM 4 in step 130 (FIG. 24), deletes the stabilization time portion (first 2 seconds) of the facial signal stored in the RAM 4 in step 410, and deletes it. The later face signal is stored in RAM 4 (step 420).
Similarly, the CPU 2 deletes the stabilization time portion of the finger signal stored in the RAM 4 in step 415, and stores the deleted finger signal in the RAM 4 (step 425).

Next, the CPU 2 stores and sets the interpolation time resolution in the RAM 4 (step 430). This is the time interval interpolated by spline interpolation, and here, the resolution is equivalent to 240 [fps].
Then, the CPU 2 creates an interpolated time vector used in FFT according to the resolution set in step 430 and stores it in the RAM 4 (step 435).

Next, CPU 2 reads the face signal (filtered, stabilization time deleted) stored in RAM 4 in step 420, and spline-interpolates it according to the time vector created in step 435 (step 440). As a result, data points of face signals corresponding to 240 [fps] are created.

Next, CPU 2 similarly reads the finger signal (filtered, stabilization time deleted) stored in RAM 4 at step 425 and spline-interpolates it according to the time vector created at step 435 (step 445). As a result, finger signal data points equivalent to 240 [fps] are created.

Next, CPU 2 normalizes the face signal stored in RAM 4 in step 440 and stores it in RAM 4 (step 450), and normalizes the finger signal stored in RAM 4 in step 445 and stores it in RAM 4 (step 455).
Normalization is performed by subtracting the mean of the signal from the signal (face signal or finger signal) (i) and dividing it by the standard deviation of the signal to obtain the normalized signal (i ) by calculating
Here, the normalized signal (i) is obtained by the following equation.
Normalized signal (i)=(signal (i)-average of signal)/standard deviation of signal After performing the above processing, the CPU 2 returns to the main routine.

FIG. 32 is a flow chart for explaining the blood pressure measurement process of step 90 (FIG. 22).
First, CPU 2 calculates cross-correlations and delays (step 505). That is, the CPU 2 reads out the normalized face signal stored in the RAM 4 in step 450 (FIG. 31) and the normalized finger signal stored in the RAM 4 in step 455 (FIG. 31), and reads these normalized face signals and finger signals. The relationship between the signal cross-correlation and the delay (delay time L) (relationship as shown in FIG. 14(b)) is calculated and stored in RAM 4 (step 505).
More specifically, the CPU 2 sets N and m in the RAM 4 and calculates the relationship between the cross-correlation and m according to the equation (1) as shown in FIG. 19(b).
Since m is the number of data points corresponding to the delay time, the CPU 2 applies the time interval between data points adjacent to m (here, 1/240 second for sampling at 240 [fps] equivalent). Thus, the relationship between cross-correlation and delay time as shown in FIG. 14(b) is calculated.
Then, the CPU 2 searches for a cross-correlation peak between 0 and 1.1 seconds, and stores the time of the searched peak in the RAM 4 as a delay time.

Next, the CPU 2 stores and sets the maximum cross-correlation search area in the RAM 4 (step 510). This sets the range of the delay time for searching for the cross-correlation peak, and since the delay time is positive, it is set to 0 to 1.1 [s] as an example with reference to experimental results.
Next, the CPU 2 limits the maximum search area for cross-correlation peaks to the range stored in the RAM 4 in step 510 (step 515).

Next, the CPU 2 searches for the peak of the cross-correlation delay time stored in the RAM 4 in step 505 in the maximum search area limited in step 515 (step 520), thereby identifying the cross-correlation peak (step 525). ).
Then, the CPU 2 determines the delay time L corresponding to the specified maximum peak of the cross-correlation, and stores it in the RAM 4 (step 530).

By the way, the relationship between the delay time L and the systolic blood pressure (systolic blood pressure SBP) and the diastolic blood pressure (diastolic blood pressure DBP) is expressed by the formulas (A) and (B) obtained by experiments as described in the first embodiment. By applying the delay time L, the systolic blood pressure estimation parameters (PS1, PS2), and the diastolic blood pressure estimation parameters (PD1, PD2), the absolute values of the systolic blood pressure and the diastolic blood pressure can be obtained, respectively.
These parameters may be set for each subject 15, or representative values applied to all subjects 15 may be used.
In the present embodiment, unlike the first embodiment, the delay time L is obtained using the correlation delay C instead of the minimum value V. Therefore, each parameter value corresponding to the correlation delay C is stored in the storage unit 10. ing.

The CPU 2 stores and sets the systolic blood pressure estimation parameters (PS1, PS2) in the RAM 4 (step 535).
Then, the CPU 2 substitutes the delay time L stored in the RAM 4 in step 530 and the systolic blood pressure estimation parameters (PS1, PS2) stored in the RAM 4 in step 535 into the formula (A) obtained by the experiment to obtain the systolic blood pressure. It is determined by calculation and stored in RAM 4 (step 540).
Systolic blood pressure SBP=PS1×delay time L+PS2 Equation (A)

Next, the CPU 2 stores and sets diastolic blood pressure estimation parameters (PD1, PD2) in the RAM 4 (step 545).
Then, the CPU 2 substitutes the delay time L stored in the RAM 4 in step 530 and the diastolic blood pressure estimation parameters (PD1, PD2) stored in the RAM 4 in step 545 into the formula (B) obtained by the experiment to obtain the systolic blood pressure. It is determined by calculation and stored in RAM 4 (step 550).
Diastolic blood pressure DBP=PD1×delay time L+PD2 Equation (B)
After the above processing, the CPU 2 displays the systolic blood pressure and the diastolic blood pressure stored in the RAM 4 on the display 5 and returns to the main routine.

(Modification)
In the embodiment described above, the facial and finger videos taken by the front camera 7 and the rear camera 8 are stored in advance in the storage unit 10 and analyzed to measure blood pressure. An example of measuring blood pressure by capturing a finger moving image in real time will be described.
In this modified example, the "moving image frame reading" process (step 5) in FIG. 21 is changed to "moving image shooting process". Other processing is the same as the embodiment.

FIG. 33 is a flowchart for explaining the moving image shooting process in step 5 after the change.
First, the CPU 2 captures the face of the subject 15 with the front camera 7, stores the face frame image 31 in the RAM 4 (step 560), further captures the finger of the subject 15 with the back camera 8, and The frame image 32 is stored in RAM 4 (step 565).

Next, the CPU 2 counts the number of photographed face frame images 31 and finger frame images 32, stores them in the RAM 4 (step 570), and determines whether or not these frame images have been collected for a sufficient period of time (step 575). ).
If the acquisition has not been performed for a sufficient period of time (step 575; N), the CPU 2 returns to step 560 and acquires more frame images.

On the other hand, if the collection has been performed for a sufficient time (step 575; Y), the CPU 2 stores the face frame images 31 collected by the front camera 7 as a face moving image in the RAM 4, and stores the finger frame images 32 collected by the back camera 8 as a finger moving image. is stored in RAM 4 (step 580).
The number of face frame images 31 and the number of finger frame images 32 stored in step 570 correspond to obtaining the number of frames in step 115 (FIG. 23).

Next, the CPU 2 acquires the frame rate and stores it in the RAM 4 (step 585), sets the time vector and stores it in the RAM 4 (step 590).
These are similar to steps 110, 120 (FIG. 23).
Other processing is the same as in the previously described embodiment.
According to this modified example, the blood pressure can be measured in real time and updated each time the face moving image and the finger moving image are collected for a sufficient period of time.

FIG. 34 is a diagram showing performance evaluation of the blood pressure measurement device 1. FIG.
The measured value 45 indicated by a thick line in FIG. 34(a) is the systolic blood pressure measured by the blood pressure measuring device 1, and the measured value 46 indicated by a thin line is a generally used finger-worn sphygmomanometer. Measured systolic blood pressure.
The vertical axis represents the systolic blood pressure [mmHg], and the horizontal axis represents the sample number for sampling the blood pressure, corresponding to the time axis.
As shown in the figure, the systolic blood pressure fluctuates over time, but both agree with high accuracy.

The measured value 47 indicated by a thick line in FIG. 34(b) is the diastolic blood pressure measured by the blood pressure measuring device 1, and the measured value 48 indicated by a thin line is the diastolic blood pressure measured by a general sphygmomanometer.
As shown in the figure, diastolic blood pressure fluctuates with time, but both agree with high accuracy.

In the embodiments described above, feature 1 provides the following configuration.
(First Configuration) Acquiring a first moving image of a first body surface of a subject under ambient light and a second moving image of a second body surface of the subject under predetermined illumination light. and acquiring a first pulse wave from the first moving image using time changes of different types of color components from each of the first moving image and the second moving image, and obtaining a first pulse wave from the first moving image, and Pulse wave acquiring means for acquiring a second pulse wave from a second moving image, and acquiring the blood pressure of the subject by using a propagation delay between the acquired first pulse wave and the second pulse wave. A blood pressure measuring device comprising: blood pressure acquisition means; and output means for outputting the acquired blood pressure.
(Second Configuration) The pulse wave acquiring means acquires a first pulse wave using the Q component included in the YIQ component from the first moving image, and the G component included in the RGB component from the second moving image. A blood pressure measuring device according to a first configuration, wherein a second pulse wave is acquired using
(Third Arrangement) The blood pressure measuring apparatus according to the second arrangement, wherein the pulse wave acquiring means acquires the second pulse wave using a value obtained by inverting the G component.
(Fourth Configuration) The first configuration, the second configuration, or the third configuration, wherein the first body surface is the subject's face and the second body surface is the subject's fingers. Configuration blood pressure measuring device.
(Fifth Configuration) A first camera disposed on a first side for photographing a first body surface of a subject; a second camera for photographing the second body surface of the subject while illuminating it with a predetermined illumination light; and a first moving image obtained by photographing the first body surface of the subject under ambient light with the first camera. and acquires a second moving image obtained by capturing the second body surface of the subject under a predetermined illumination light with the second camera; and the obtained first moving image and the second Pulse wave acquisition of acquiring a first pulse wave from the first moving image and acquiring a second pulse wave from the second moving image, using time changes of different types of color components from each of the moving images means, blood pressure acquisition means for acquiring the subject's blood pressure using a propagation delay between the acquired first pulse wave and second pulse wave, display means for displaying the acquired blood pressure, A mobile terminal comprising:
(Sixth Configuration) Acquiring a first moving image of a first body surface of a subject under ambient light and a second moving image of a second body surface of the subject under predetermined illumination light. and acquiring a first pulse wave from the first moving image by using temporal changes of different types of color components from each of the first moving image and the second moving image obtained from each of the obtained first moving image and the second moving image; Obtaining the subject's blood pressure using a pulse wave obtaining function of obtaining a second pulse wave from a second moving image and a propagation delay between the obtained first pulse wave and second pulse wave A blood pressure measurement program for realizing, on a computer, a blood pressure acquisition function and an output function for outputting the acquired blood pressure.

Feature 2 provides the following configuration.
(21st configuration) moving image acquisition means for acquiring a first moving image of a first body surface of a subject and a second moving image of a second body surface of the subject; a pulse wave obtaining means for obtaining a first pulse wave from a change in a component that constitutes the color of the first moving image, and obtaining a second pulse wave from a change in the component that constitutes the color of the acquired second moving image; , the entire acquired first pulse wave waveform and the acquired entire second pulse wave waveform Propagation between the first pulse wave and the second pulse wave acquired using a delay acquisition means for acquiring the delay of the propagation, a blood pressure acquisition means for acquiring the blood pressure of the subject using the acquired propagation delay, and an output means for outputting the acquired blood pressure. blood pressure measuring device.
(22nd Configuration) The delay acquiring means acquires the propagation delay using a correlation between the waveform of the first pulse wave and the waveform of the second pulse wave. A blood pressure measuring device having a twenty-first configuration.
(Twenty-third configuration) The delay obtaining means shifts at least one of the waveform of the first pulse wave and the waveform of the second pulse wave in the time direction, and the correlation for each shift is and acquires the shift amount that maximizes the correlation as the propagation delay.
(24th configuration) Between the waveform of the first pulse wave and the waveform of the second pulse wave, the correlation is established within a range in which the pulse wave acquired from the moving image taken on the body surface farther from the heart is delayed. The blood pressure measuring device according to the 23rd configuration, wherein a peak is searched and the shift amount is obtained from the position of the searched peak.
(25th Configuration) Of the 21st to 24th configurations, wherein the first body surface is the subject's face and the second body surface is the subject's fingers. A blood pressure measuring device according to any one of the configurations.
(26th Configuration) A first camera disposed on a first side for photographing a first body surface of a subject; a second camera for photographing a second body surface of a person; obtaining a first video photographing the first body surface of the subject with the first camera; a moving image acquiring means for acquiring a second moving image obtained by photographing a second body surface of a person; A pulse wave acquisition means for acquiring a second pulse wave from a change in the components that make up the color of the second moving image, the entire waveform of the acquired first pulse wave, and the acquired second pulse wave and a delay acquisition means for acquiring the propagation delay between the acquired first pulse wave and the second pulse wave using the entire waveform, and the subject's blood pressure using the acquired propagation delay and a display means for displaying the obtained blood pressure.
(27th Configuration) A moving image acquisition function of acquiring a first moving image of a first body surface of a subject and a second moving image of a second body surface of the subject; A pulse wave acquisition function of acquiring a first pulse wave from a change in a component that constitutes the color of the first moving image, and acquiring a second pulse wave from a change in the component that constitutes the color of the acquired second moving image; , the entire acquired first pulse wave waveform and the acquired entire second pulse wave waveform Propagation between the first pulse wave and the second pulse wave acquired using A blood pressure measurement that realizes a delayed acquisition function of acquiring the delay of the blood pressure, a blood pressure acquisition function of acquiring the blood pressure of the subject using the acquired propagation delay, and an output function of outputting the acquired blood pressure. program.

Feature 3 provides the following configuration.
(31st configuration) moving image acquiring means for acquiring a first moving image of a first body surface of a subject and a second moving image of a second body surface of the subject; The frame rate of the first moving image and the frame rate of the second moving image are determined from the change in the component that constitutes the color of the first moving image and the change in the component that constitutes the color of the acquired second moving image. A pulse wave acquisition means for acquiring a discrete first pulse wave and a discrete second pulse wave according to the above, and the acquired discrete first pulse wave and discrete second pulse wave , the interpolating means for interpolating each discrete value, the waveform of the interpolated first pulse wave, and the waveform of the interpolated second pulse wave, the obtained first pulse wave and the second pulse wave delay acquisition means for acquiring a propagation delay between pulse waves, blood pressure acquisition means for acquiring the subject's blood pressure using the acquired propagation delay, output means for outputting the acquired blood pressure, A blood pressure measuring device comprising:
(32nd Configuration) The delay acquisition means acquires the propagation delay using a correlation between the waveform of the first pulse wave and the waveform of the second pulse wave. The blood pressure measuring device of the 31st configuration.
(33rd Configuration) The delay obtaining means shifts at least one of the interpolated waveform of the first pulse wave and the waveform of the interpolated second pulse wave in the time direction, The blood pressure measuring apparatus according to the 32nd configuration is characterized in that the correlation between the frequencies is obtained, and the shift amount that maximizes the correlation is obtained as the propagation delay.
(34th Configuration) A 31st configuration, a 32nd configuration, or a 33rd configuration, wherein the first body surface is the subject's face and the second body surface is the subject's fingers. Configuration blood pressure measuring device.
(35th Configuration) A first camera disposed on a first side for photographing a first body surface of a subject; a second camera for photographing a second body surface of a person; obtaining a first video photographing the first body surface of the subject with the first camera; moving image acquiring means for acquiring a second moving image obtained by photographing a second body surface of a person; changes in components constituting colors of the acquired first moving image; and forming colors of the acquired second moving image A discrete first pulse wave and a discrete second pulse wave corresponding to the frame rate of the first moving image and the frame rate of the second moving image, respectively, are obtained from changes in the components that wave acquiring means, interpolating means for interpolating discrete values of the acquired discrete first pulse wave and discrete second pulse wave, waveform of the interpolated first pulse wave, A delay acquisition means for acquiring the propagation delay between the acquired first pulse wave and the second pulse wave using the interpolated waveform of the second pulse wave, and the acquired propagation delay A mobile terminal, comprising: a blood pressure acquisition unit that acquires the blood pressure of the subject using a personal digital assistant; and a display unit that displays the acquired blood pressure.
(36th configuration) a moving image acquisition function of acquiring a first moving image of a first body surface of a subject and a second moving image of a second body surface of the subject; The frame rate of the first moving image and the frame rate of the second moving image are determined from the change in the component that constitutes the color of the first moving image and the change in the component that constitutes the color of the acquired second moving image. A pulse wave acquisition function that acquires a discrete first pulse wave and a discrete second pulse wave according to, and the acquired discrete first pulse wave and discrete second pulse wave , the interpolation function for interpolating each discrete value, the waveform of the interpolated first pulse wave, and the waveform of the interpolated second pulse wave, the acquired first pulse wave and the second pulse wave a delay acquisition function for acquiring a propagation delay between pulse waves, a blood pressure acquisition function for acquiring the subject's blood pressure using the acquired propagation delay, and an output function for outputting the acquired blood pressure; A computerized blood pressure measurement program.

As described above, the blood pressure measurement device 1 provides relative blood pressure measurement means using a smartphone. Here, regarding features 1 to 3, the following is a summary of the effects of the conventional embodiment and the present embodiment.
(Feature 1)
Conventionally, when blood pressure is measured with a smartphone, the relative blood pressure is measured using the RG components from images captured by the smartphone's front camera (capturing the face) and rear camera (capturing the finger).
In the present embodiment, the H component, the S component (extraction of the measurement area), and the Q component (face signal) are used in the image of the front camera (capturing the face). In the case of the rear camera (shooting the finger), by using the G component (finger signal) using the lighting of the smartphone, the reliability of the pulse wave signal (face signal, finger signal) is strengthened by countermeasures against movement and light disturbance. be able to.

(Feature 2)
Conventionally, when blood pressure is measured with a smartphone, RG components are extracted from images captured by a front camera (capturing a face) and a rear camera (capturing a finger) of the smartphone. Then, the relative blood pressure is measured from the peak time difference of the extracted waveform.
In this embodiment, the pulse wave delay (and blood pressure) can be measured with high accuracy by using the waveform of the entire wave instead of the peak (correlation method).

(Feature 3)
Conventionally, when blood pressure is measured with a smartphone, the relative blood pressure is measured using images from the smartphone's front camera (capturing the face) and rear camera (capturing the finger). However, since most of the cameras used in smartphones are 30 to 60 [fps], the resolution for blood pressure measurement is insufficient.
In the present embodiment, spline interpolation is applied to the pulse wave extracted from the video, and the correlation method is applied to the interpolated pulse wave, thereby estimating and measuring blood pressure with high resolution (time resolution).

1 blood pressure measuring device 2 CPU
3 ROMs
4 RAM
5 display 6 touch panel 7 first pulse wave measuring unit (front camera)
8 Second pulse wave measurement unit (back camera)
9 illumination 10 storage unit 10a blood pressure measurement program 10b data 11 communication control unit 15 subject person 16, 17, 19 finger signals 18, 20 face signal 25 lump region 26 measurement region 31 face frame image 32 finger frame image 36 face data points (interpolation Previous)
37 face data points (after interpolation)
38 spline curve 45, 46 measured value (systolic blood pressure)
47, 48 Measurements (diastolic blood pressure)
M1, M4-M7 measurement position (forehead, forearm, wrist, base of thumb, fingertip)
V lowest value (trough)
T highest value (peak)
D Maximum slope C Correlation delay (delay of whole pulse wave)

Claims (11)

a first pulse wave acquiring means for acquiring a first pulse wave m1 measured at a first position of the subject;
a second pulse wave acquiring means for acquiring a second pulse wave m2 measured at a second position that is farther from the subject's heart than the first position;
a delay time acquiring means for acquiring a delay time L of the second pulse wave m2 with respect to the first pulse wave m1;
when the obtained delay time L is equal to or less than the reference value Th, a notification means for notifying that fact;
blood pressure acquiring means for acquiring the subject's systolic blood pressure SBP and diastolic blood pressure DBP using the delay time L acquired by the delay time acquiring means when the delay time L is greater than the reference value Th;
output means for outputting the acquired systolic blood pressure SBP and diastolic blood pressure DBP;
A blood pressure measuring device comprising: The delay time obtaining means delays the first pulse wave m1 and the second pulse wave m2 using one of the pulse wave elements of the lowest value V, the highest value T, the maximum slope D, and the correlation delay C. get time L,
The blood pressure measuring device according to claim 1, characterized in that: The delay time acquisition means acquires the delay time L used for comparison with the reference value Th and the delay time L used for acquiring the blood pressure using the different pulse wave elements.
The blood pressure measuring device according to claim 2, characterized in that: The delay time acquisition means is
Acquiring the delay time L used for comparison with the reference value Th using the minimum value V,
Obtaining the delay time L used to obtain the blood pressure using the correlation delay C;
The blood pressure measuring device according to claim 2, characterized in that: The reference value Th is a time selected in the range of 0.1 seconds to 0.06 seconds,
The blood pressure measuring device according to any one of claims 1 to 4, characterized in that: The reference value Th is 0.08 seconds,
The blood pressure measuring device according to any one of claims 1 to 4, characterized in that: The notification means uses at least one of image display and sound to perform notification prompting a change of the second position for acquiring the second pulse wave,
The blood pressure measuring device according to any one of claims 1 to 6, characterized in that: The first pulse wave acquisition means and the second pulse wave acquisition means acquire a pulse wave using a contact type sensor that measures the pulse wave based on the amount of change in light that is transmitted or reflected inside the body of the subject. ,
The blood pressure measuring device according to any one of claims 1 to 7, characterized in that: The first pulse wave acquiring means acquires a first moving image obtained by photographing a first body surface of a subject under ambient light, and obtains a first pulse wave from the first moving image using a time change of a color component. get the waves,
The second pulse wave acquiring means acquires a second moving image obtained by photographing a second body surface of the subject under a predetermined illumination light, and obtains a color component of a type different from the color component from the second moving image. Acquiring a second pulse wave using the time change of
The blood pressure measuring device according to any one of claims 1 to 7, characterized in that: The first pulse wave acquiring means acquires a first pulse wave using a Q component included in a YIQ component from the first moving image,
The second pulse wave acquisition means acquires a second pulse wave from the second moving image using G components included in RGB components.
The blood pressure measuring device according to claim 9, characterized in that: a first pulse wave acquisition function for acquiring a first pulse wave m1 measured at a first position of the subject;
a second pulse wave acquisition function that acquires a second pulse wave m2 measured at a second position that is farther from the subject's heart than the first position;
a delay time acquisition function for acquiring a delay time L of the second pulse wave m2 with respect to the first pulse wave m1;
a notification function for notifying when the acquired delay time L is equal to or less than a reference value Th;
a blood pressure acquisition function for acquiring the subject's systolic blood pressure SBP and diastolic blood pressure DBP using the delay time L acquired by the delay time acquisition function when the delay time L is greater than the reference value Th;
an output function for outputting the acquired systolic blood pressure SBP and diastolic blood pressure DBP;
A blood pressure measurement program for realizing on a computer.

Images