Pulse wave signal processing device, biological information measuring device, and pressing force abnormality determination method

Abstract

The pulse wave feature amount calculation unit calculates a pulse wave feature amount relating to the gradient of the rising edge of the pulse wave measured by the photoelectric pulse wave sensor. The pressing force determination unit determines, on the basis of the value of the pulse wave feature amount calculated by the pulse wave feature amount calculation unit, whether or not the pressing force, which is the pressure applied to the measurement site by the photoelectric pulse wave sensor, is within an appropriate range.

Description

Technical Field

[0001] The present invention relates to a pulse wave signal processing device, a biological information measuring device and a pressing force abnormality determination method. Background Art

[0002] As an indicator used in estimating a person's health status, a pulse wave propagating in an artery is used. The pulse wave changes in accordance with changes in blood flow at a measurement site. In a small wearable electronic device, a method of measuring a pulse wave using a photoelectric pulse wave sensor is convenient. For example, light is incident from a light-emitting element onto a measurement site such as a finger, and the reflected light or transmitted light of the light is detected by a light-receiving element, and changes in blood flow are obtained as a pulse wave signal.

[0003] When the pressing force between the photoelectric pulse wave sensor and the measured part is outside the appropriate range, the amplitude of the detected pulse wave becomes smaller, so it is preferable to measure the pulse wave in a state where the photoelectric pulse wave sensor is in contact with the measured part with an appropriate pressing force. A wristwatch-type pulse wave signal processing device incorporating a pressure sensor in order to determine whether the pressing force is appropriate is known (Patent Document 1). The pulse wave signal processing device causes a display device to display the current pressing force level detected by the pressure sensor. When the pressing force value is outside the appropriate range, the pulse wave signal processing device is vibrated to inform the user.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 1094 / 15525 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In conventional pulse wave signal processing devices, a pressure sensor is worn to determine whether the pressing force is appropriate. If the pulse wave signal processing device is to be miniaturized, it is sometimes difficult to wear the pressure sensor. In addition, the mounting position of the pressure sensor is different from the mounting positions of the light emitting element and the light receiving element. Therefore, even if the value of the pressing force at the position of the pressure sensor is appropriate, the pressing force at the mounting positions of the light emitting element and the light receiving element may not be appropriate.

[0009] An object of the present invention is to provide a pulse wave signal processing device that can determine whether the pressing force of a light emitting element and a light receiving element on a measured part is within an appropriate range without using a pressure sensor. Another object of the present invention is to provide a biological information measuring device equipped with the pulse wave signal processing device. Still another object of the present invention is to provide a pressing force abnormality determination method that can determine whether the pressing force is within an appropriate range without using a pressure sensor.

[0010] Solutions for solving problems

[0011] According to one aspect of the present invention, a pulse wave signal processing device is provided.

[0012] The pulse wave signal processing device comprises:

[0013] a pulse wave feature value calculation unit that calculates a pulse wave feature value associated with a steepness of a rising edge of a pulse wave measured by the photoelectric pulse wave sensor; and

[0014] The pressing determination unit determines whether the pressing force, which is the pressure with which the photoelectric pulse wave sensor presses the measurement site, falls within an appropriate range based on the value of the pulse wave feature value calculated by the pulse wave feature value calculation unit.

[0015] According to another aspect of the present invention, there is provided a biological information measuring device,

[0016] The biological information measuring device comprises:

[0017] The pulse wave signal processing device mentioned above; and

[0018] The photoelectric pulse wave sensor measures the pulse wave of the measured part and inputs the measurement result to the pulse wave signal processing device.

[0019] The photoelectric pulse wave sensor includes at least one light emitting element and a light receiving element for detecting light outputted from the at least one light emitting element after being reflected at the measured part or light after being transmitted through the measured part.

[0020] According to another aspect of the present invention, a method for determining abnormal pressing force is provided, wherein:

[0021] calculating a pulse wave feature value associated with the steepness of the rising edge of the pulse wave measured by the photoelectric pulse wave sensor in contact with the measured part,

[0022] Based on the value of the pulse wave feature amount obtained by calculation, it is determined whether or not the pressing force, which is the pressure with which the photoelectric pulse wave sensor presses the measurement site, is abnormal.

[0023] Effects of the Invention

[0024] Whether the pressing force is within the appropriate range is determined based on the pulse wave feature associated with the steepness of the rising edge of the pulse wave, so there is no need to carry a pressure sensor that directly measures the pressing force. Therefore, it is possible to miniaturize the device that contacts the measured part. In addition, the pulse wave is used to determine whether the pressing force is within the appropriate range, so it is possible to calculate highly reliable biological information based on the pulse wave determined to be the appropriate pressing force. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the pulse wave signal processing device of the first embodiment and a schematic diagram of a biological information measuring device including the pulse wave signal processing device.

[0026] Figure 2 This is a graph showing an example of a pulse wave, a velocity pulse wave, and an acceleration pulse wave.

[0027] Figure 3 This is a graph showing an example of a pulse wave and an accelerated pulse wave.

[0028] Figure 4A , Figure 4B , Figure 4C as well as Figure 4D This is a graph showing the relationship between the value of the pulse wave characteristic quantity obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed and the height of the measured part is made consistent with the chest and then the vicinity of the elbow on the side of the finger that is the measured part is cooled, and the systolic blood pressure measured at the wrist.

[0029] Figure 5 This is a graph showing an example of a change over time in the amount of light received by the light receiving element when near-infrared light is output from the light emitting element in a state where the photoelectric pulse wave sensor is in contact with the measurement site.

[0030] Figure 6 This is a graph showing the waveform shape of the pulse wave corresponding to approximately one beat when the pressing force of the photoelectric pulse wave sensor on the measurement site is within an appropriate range and when it is excessive.

[0031] Figure 7 It is shown Figure 5 FIG. 2 is a graph showing changes in the elapsed time from the peak of the a wave to the peak of the b wave of the pulse wave over time.

[0032] Figure 8 It shows that according to Figure 5 FIG. 5 is a graph showing the change over time of the pulse wave feature value “1 / (VE0.5)” calculated by the pulse wave calculation.

[0033] Fig. 9 It shows that according to Figure 5 FIG. 4 is a graph showing the change over time of the pulse wave characteristic value “a / S” calculated from the pulse wave.

[0034] Fig.10 It shows that according to Figure 5 FIG. 4 is a graph showing the change over time of the pulse wave characteristic value “(ab) / (ad)” calculated from the pulse wave.

[0035] Fig.11 1 is a flowchart showing the process of the pressing force abnormality determination method according to the first embodiment.

[0036] Fig.12 It is a block diagram of a pulse wave signal processing device according to a second embodiment and a schematic diagram of a biological information measuring device including the pulse wave signal processing device.

[0037] Fig.13 This is a graph showing an example of a change over time in the amount of light received by a light receiving element when near-infrared light and green light are output from two light emitting elements respectively in a state where the photoelectric pulse wave sensor is in contact with a measurement site.

[0038] Fig.14 This is a graph showing the waveform shape of a pulse wave obtained using green light when the pressing force of the photoelectric pulse wave sensor on the measured part is within an appropriate range and when it is excessive, which is approximately the amount of one beat.

[0039] Fig.15 It shows that according to Fig.13 FIG. 4 is a graph showing the change over time of the pulse wave characteristic amount “ab time” calculated by the pulse wave calculation.

[0040] Fig.16 It shows that according to Fig.13 FIG. 5 is a graph showing the change over time of the pulse wave feature value “1 / (VE0.5)” calculated by the pulse wave calculation.

[0041] Fig.17 It shows that according to Fig.13 FIG. 4 is a graph showing the change over time of the pulse wave characteristic value “a / S” calculated from the pulse wave.

[0042] Fig.18 It shows that according to Fig.13 FIG. 4 is a graph showing the change over time of the pulse wave characteristic value “(ab) / (ad)” calculated from the pulse wave.

[0043] Fig.19 : is a graph showing the pulse wave feature amount "ab time" calculated based on the pulse waves acquired from a plurality of subjects.

[0044] Fig. 20 : is a graph showing the pulse wave feature value "1 / (VE0.5)" calculated based on the pulse waves acquired from a plurality of subjects.

[0045] Fig.21 : is a graph showing the pulse wave feature value "a / S" calculated based on the pulse waves acquired from a plurality of subjects.

[0046] Fig. 22 : is a graph showing the pulse wave feature value "(ab) / (ad)" calculated based on the pulse waves acquired from a plurality of subjects.

[0047] Fig.23 It is a block diagram of a pulse wave signal processing device according to a modified example of the second embodiment and a schematic diagram of a biological information measuring device including the pulse wave signal processing device.

[0048] Fig.24 It is a perspective view and a block diagram of a part of the living body information measuring device of the third embodiment. DETAILED DESCRIPTION

[0049] [First embodiment]

[0050] Reference Figures 1 to 11 The pulse wave signal processing device, the biological information measuring device, and the pressing force abnormality determination method of the first embodiment are described with reference to the accompanying drawings.

[0051] Pulse waves are used to measure various biological information. For example, they are used to measure pulse rate and oxygen saturation. In addition, they are also used to measure autonomic nervous function caused by changes in pulse intervals, and to measure respiratory rate caused by changes in pulse wave baselines or pulse intervals. In addition, a technology for estimating blood pressure based on the waveform shape of the pulse wave has been developed. Pulse waves are classified into pressure pulse waves (piezoelectric pulse waves) measured using piezoelectric sensors and the like, and volume pulse waves (photoplethysmography) measured using photoelectric pulse wave sensors.

[0052] The pulse wave signal processing device of the first embodiment can be applied to both piezoelectric pulse wave and photoplethysmography. More information can be obtained from photoplethysmography than from piezoelectric pulse wave. The following description will be made by taking photoplethysmography as an example.

[0053] Figure 11 is a block diagram of the pulse wave signal processing device 30 of the first embodiment and a schematic diagram of a biological information measuring device including the pulse wave signal processing device 30. The biological information measuring device includes the pulse wave signal processing device 30 and a photoelectric pulse wave sensor 50. The photoelectric pulse wave sensor 50 includes a light emitting element 51 and a light receiving element 53. The pulse wave signal processing device 30 includes a light emitting control unit 31, a pulse wave feature amount calculation unit 32, a pressure determination unit 33, an abnormality notification unit 34, a control unit 35, and a pulse wave measurement unit 36.

[0054] The light emitting element 51 and the light receiving element 53 are used in contact with the body surface 70 of the user. The light emitting element 51 irradiates the light for measurement toward the body surface 70. The irradiated light is absorbed, reflected or scattered (hereinafter sometimes simply referred to as "reflection") by the epidermal area 71, the arteriole 72 and the capillary 73 in the body surface 70. A part of the reflected light is incident on the light receiving element 53.

[0055] The arteriole 72 is a thin blood vessel with a diameter of, for example, 20 μm or more and 200 μm or less, and exists between the artery and the capillary 73. A plurality of capillaries 73 branch out from the arteriole 72. The capillary 73 is a thin blood vessel with a diameter of, for example, about 10 μm, and connects the artery and the vein. A plurality of capillaries 73 are distributed in an area shallower than the area where the arteriole 72 is distributed. In addition, Figure 1 The arrows shown in do not indicate the path of light propagation, but indicate that the light output from the light emitting element 51 passes through the epidermal region 71, the region where the capillaries 73 are distributed, and the region where the arterioles are distributed, and then enters the light receiving element 53.

[0056] The light emitting element 51 is controlled by the light emitting control unit 31 to output the light for measurement. The signal indicating the intensity of the light measured by the light receiving element 53 is input to the pulse wave feature quantity calculation unit 32. The signal indicating the intensity of the light detected by the light receiving element 53 is called a "pulse wave signal". The blood in the artery contains hemoglobin, and hemoglobin has the property of absorbing the light for measurement. The blood flow rate changes with the pulsation of the heart, and the amount of light absorbed also changes according to the change in the blood flow rate. Therefore, the intensity of the pulse wave signal changes with the pulsation of the heart.

[0057] As the light emitting element 51, a light emitting element that outputs light in a wavelength range from blue to near infrared (a wavelength range of 450 nm to 950 nm) is used. For example, a light emitting diode (LED), a vertical cavity surface emitting laser (VCSEL), etc. are used in the light emitting element 51. For example, a photodiode (PD), a phototransistor, etc. are used in the light receiving element 53.

[0058] Light with a wavelength shorter than 450 nm can damage biological tissue. In a wavelength range longer than 950 nm, the absorbance of hemoglobin decreases. Therefore, in order to obtain a pulse wave signal, it is preferred to use light with a wavelength range of 450 nm to 950 nm. In addition, in detecting light in this wavelength range, an inexpensive Si photodiode can be used as the light receiving element 53.

[0059] The control unit 35 controls the start and end of measurement, the display of measurement results, etc. The light emission control unit 31 controls the pulse light emission of the light emitting element 51. For example, the light emitting element 51 is made to emit pulse light at a predetermined frequency of 100 Hz to 1000 Hz.

[0060] The pulse wave measuring unit 36 ​​generates a pulse wave waveform (hereinafter sometimes simply referred to as a "pulse wave") based on the measurement result (pulse wave signal) input from the light receiving element 53. For example, the pulse wave measuring unit 36 ​​generates a pulse wave by reading the measured value of the light intensity from the light receiving element 53 at a predetermined sampling rate in synchronization with the pulse light emission of the light receiving element 51.

[0061] The pulse wave feature calculation unit 32 calculates the feature of the pulse wave (hereinafter referred to as the pulse wave feature) based on the pulse wave generated by the pulse wave measurement unit 36. For example, the pulse wave is separated for each beat and the pulse wave feature is obtained from the pulse wave for each beat.

[0062] The pulse wave feature quantity reflects biological information such as pulse rate, oxygen saturation, respiratory rate, blood pressure in large arteries, blood pressure in capillaries or arterioles (peripheral blood pressure), blood flow, vascular resistance, arteriosclerosis, blood sugar level, hemodynamics, and the state of the autonomic nervous system. Therefore, it is possible to estimate these biological information based on the pulse wave feature quantity obtained by the pulse wave signal processing device 30. The pulse wave feature quantity obtained based on the pulse wave actually measured using the photoelectric pulse wave sensor 50 is easily affected by the pressing force of pressing the photoelectric pulse wave sensor 50 onto the biological body. Therefore, when estimating various biological information based on the pulse wave feature quantity, when the pressing force is not within an appropriate range, the reliability of the estimation result decreases.

[0063] The pressing determination unit 33 determines whether the pressing force of the light emitting element 51 and the light receiving element 53 on the body surface 70 is appropriate based on the pulse wave feature calculated by the pulse wave feature calculation unit 32. When the pressing force value is outside the appropriate range (when the pressing force value is abnormal), the abnormality notification unit 34 notifies the user of the abnormal pressing force. For example, the abnormal pressing force is notified by sound, vibration, light, etc.

[0064] Next, pulse wave feature quantities that can be used to estimate biological information will be described.

[0065] Figure 2 : is a graph showing an example of a pulse wave, a velocity pulse wave, and an acceleration pulse wave. The pulse wave feature amount calculation unit 32 performs first-order differentiation and second-order differentiation on the pulse wave. The waveform obtained by performing first-order differentiation on the pulse wave and the waveform obtained by performing second-order differentiation on the pulse wave are respectively called a velocity pulse wave and an acceleration pulse wave. For example, the velocity pulse wave is obtained by numerically differentiating the intensity of the pulse wave that is discretely distributed at a time interval corresponding to the sampling rate at a time interval corresponding to the sampling rate. In addition, the acceleration pulse wave is obtained by numerically differentiating the magnitude of the velocity pulse wave.

[0066] Figure 2 The horizontal axis represents time in units of [s], the left vertical axis represents the magnitudes of the velocity pulse wave and the acceleration pulse wave standardized so that the maximum value is 1, and the right vertical axis represents the magnitude of the pulse wave in arbitrary units. Figure 2 The solid line, long dashed line and short dashed line in the graph shown represent the pulse wave, velocity pulse wave and acceleration pulse wave respectively. Generally speaking, the acceleration pulse wave in one beat has five peaks. The first peak, second peak, third peak, fourth peak and fifth peak in one beat are called a wave, b wave, c wave, d wave and e wave respectively.

[0067] Figure 3 : is a graph showing an example of a pulse wave and an accelerated pulse wave. The horizontal axis represents time, the left vertical axis represents the magnitude of the pulse wave in arbitrary units, and the right vertical axis represents the magnitude of the accelerated pulse wave in arbitrary units. The 5 scales of the horizontal axis correspond to 0.2 seconds. The ratio of the amplitude S of the pulse wave to the peak value a of the a wave of the accelerated pulse wave is marked as "a / S". In addition, the amplitude S of the pulse wave is equivalent to the difference between the minimum value and the maximum value after the waveform is corrected in such a way that the minimum values ​​of the pulse waves of two consecutive beats are the same size.

[0068] Next, a method of estimating blood pressure based on the pulse wave will be described.

[0069] In this specification, the blood pressure in the peripheral arterioles and capillaries is referred to as peripheral blood pressure. Peripheral blood pressure is sometimes used to mean the blood pressure at the wrist or ankle measured by a cuff-type sphygmomanometer, but the blood pressure measured at the wrist or ankle is a measurement value at a thick artery (radial artery, etc.), which is different from the blood pressure measured at the arterioles or capillaries in this specification. As blood flows from thick arteries into arterioles and capillaries, the pressure in the blood vessels decreases. The degree of blood pressure drop varies depending on the measured site, the user's vascular condition (state of arteriosclerosis, etc.), mental state (state of the autonomic nervous system), environment (temperature, noise, etc.), type of clothing, etc.

[0070] The following two are assumed as characteristics of peripheral blood pressure. First, under the condition that blood vessels are healthy and vascular resistance does not change, peripheral blood pressure has a positive correlation with the blood pressure measured by a cuff-type blood pressure monitor at the upper arm or wrist. Second, when the vicinity of the measured part is cooled to constrict the blood vessels, the peripheral blood pressure decreases. In addition, when the peripheral blood vessels constrict and the vascular resistance increases, the blood pressure at the upper arm or wrist sometimes rises.

[0071] As pulse wave feature quantities reflecting the above two characteristics, the following three feature quantities can be cited.

[0072] The reciprocal of the full width at half maximum (hereinafter, the full width at half maximum is referred to as VE0.5) of the first upward peak of the velocity pulse wave ("1 / (VE0.5)")

[0073] The ratio of the amplitude S of the pulse wave to the peak value a of the a wave of the acceleration pulse wave (hereinafter referred to as "a / S").

[0074] The ratio of the difference between the peak value of the a wave and the peak value of the b wave of the acceleration pulse wave (ab) to the difference between the peak value of the a wave and the peak value of the d wave (ad) (hereinafter, indicated as "(ab) / (ad)").

[0075] In this specification, these pulse wave feature quantities are referred to as "peripheral blood pressure indices."

[0076] The following are pulse wave feature quantities having characteristics close to those of the peripheral blood pressure index.

[0077] The inverse of the time from the peak of the a wave to the peak of the b wave (hereinafter referred to as "1 / (ab time)").

[0078] Figure 4A , Figure 4B , Figure 4C as well as Figure 4D This is a graph showing the relationship between the value of the pulse wave characteristic amount obtained from the pulse wave measured when the height from the heart to the measured part (finger) is changed and the height of the measured part is made the same as the chest, and the vicinity of the elbow on the side of the finger as the measured part is cooled, and the systolic blood pressure measured at the wrist. In addition, near-infrared light is used in the measurement of the pulse wave. Near-infrared light not only penetrates Figure 1 The shallow region where the capillaries 73 are distributed as shown in FIG. 7 also invades into the deep region where the arterioles 72 are distributed. Therefore, the changes in the blood flow of both the arterioles 72 and the capillaries 73 are reflected in the measured pulse wave.

[0079] The distance L1 ( Figure 1). Here, the distance L1 refers to the straight-line distance from the light-emitting part of the light-emitting element 51 to the light-receiving part of the light-receiving element 53. When the distance L1 becomes shorter, the amount of light received after being reflected at an extremely shallow area of ​​the body surface 70 from the measured part is relatively strong compared to the amount of light received after being reflected at a deep area. Therefore, the influence of the blood flow of the arteriole 72 is difficult to appear in the pulse wave. On the contrary, when the distance L1 becomes longer, the amount of light received by the light-receiving element 53 decreases. In order to reflect the influence of the blood flow of the arteriole 72 in the pulse wave and ensure a sufficient amount of light received, it is preferred that the distance L1 is greater than 5 mm and less than 20 mm.

[0080] FIG. 4A to FIG. 4D The horizontal axis of each graph represents the systolic blood pressure at the wrist in [mmHg]. Figure 4A The vertical axis is in units of [s -1 ] represents the pulse wave feature value “1 / (VE0.5)”. Figure 4B The vertical axis represents the pulse wave characteristic quantity "a / S" using arbitrary units. Figure 4C The vertical axis represents the pulse wave characteristic quantity "(ab) / (ad)" in a dimensionless manner. Figure 4D The vertical axis is in units of [s -1 ] represents the pulse wave characteristic 1 / (ab time).

[0081] In each graph, the results of measurement for three subjects A, B, and C are shown by triangular marks, square marks, and circular marks, respectively. The three hollow marks shown for each subject respectively represent the values ​​of the pulse wave feature quantity obtained from the pulse wave obtained after setting the height of the measured part (finger) to the height of the abdomen (navel), chest, and face. The value of the pulse wave feature quantity decreases in the order of the height of the measured part to the abdomen, chest, and face. The blackened mark shown for each subject represents the value of the pulse wave feature quantity obtained from the pulse wave obtained in a state where the vicinity of the elbow is cooled after the height of the measured part is set to the height of the chest.

[0082] It is found that, although the degree varies depending on the subject, when the height of the measurement site is changed, each of the four pulse wave feature quantities has a substantially positive correlation with the systolic blood pressure at the wrist.

[0083] Regarding the pulse wave characteristic values ​​"1 / (VE0.5)", "a / S", and "(ab) / (ad)", it was confirmed that the pulse wave characteristic values ​​decreased and the systolic blood pressure increased when the elbow was cooled. These trends are consistent with the characteristics of the peripheral blood pressure described above. In addition, depending on the subject, the pulse wave characteristic value "1 / (ab time)" sometimes increased when the elbow was cooled.

[0084] The pulse wave feature values ​​"1 / (VE0.5)", "a / S", "(ab) / (ad)", and "1 / (ab time)" depend on the steepness of the rising edge of the pulse wave. These feature values ​​are less likely to be affected by the intensity of the pulse wave signal. In addition, the peak value a of the a wave, the peak value b of the b wave, the peak value d of the d wave, and the amplitude S of the pulse wave, which are the basis for calculating the pulse wave feature values ​​"a / S" and "(ab) / (ad)", respectively vary according to the intensity of the pulse wave signal, but by taking the ratio of them, the influence of the intensity can be roughly eliminated.

[0085] Next, a method of determining whether the pressing force is outside the appropriate range (whether it is abnormal) will be described.

[0086] Figure 5 is a diagram showing the situation when the photoelectric pulse wave sensor 50 ( Figure 1 ) is a graph showing an example of the change in the amount of light received by the light receiving element 53 over time when the light emitting element 51 outputs near-infrared light in a state of contact with the measured part (photoplethysmogram). The horizontal axis represents time in units of [s], and the vertical axis represents the amount of light received in an arbitrary scale. A pulse wave appears in which the amount of light received increases and decreases with each beat. The shape of a pulse wave is generally known to be a triangle convex upward, but in Figure 5 In the figure, the waveform is inverted upside down to show a triangular shape convex downward.

[0087] Between 8s and 19s on the horizontal axis, the photoelectric pulse wave sensor 50 applies excessive pressure to the measured part. It can be seen that when the pressure becomes excessive, the average value of the received light amount increases and the amplitude of the pulse wave decreases. The increase in the average value of the received light amount is caused by the excessive pressure, which hinders blood flow.

[0088] Figure 6 1 is a graph showing the waveform shape of the pulse wave of approximately one beat when the pressing force of the photoelectric pulse wave sensor 50 on the measured part is within the appropriate range and when it is excessive. The horizontal axis represents time and the vertical axis represents the amount of light received. The thick solid line and the dotted line in the graph respectively represent the pulse wave when the pressing force is within the appropriate range and the pulse wave when the pressing force is excessive. In addition, the waveform is corrected in such a way that the minimum values ​​of the two are approximately equal and the amplitudes are approximately equal. It can be seen that when the pressing force becomes excessive, the rising edge of the pulse wave is steeper than when the pressing force is normal. In this way, when the pressing force becomes excessive, the waveform shape of the pulse wave changes. It is possible to determine whether the pressing force is within the appropriate range based on the change in the steepness of the rising edge of the pulse wave.

[0089] Figure 7 It is shown Figure 5The graph of the time from the peak of the a wave to the peak of the b wave of the pulse wave (hereinafter referred to as the pulse wave characteristic quantity "ab time") changes with time. The horizontal axis represents time in units of [s], and the vertical axis represents the magnitude of the pulse wave characteristic quantity "ab time" in units of [s]. It can be seen that during the period of excessive pressing force, the "ab time" becomes shorter. By detecting the change of this "ab time", it can be determined whether the pressing force is abnormal.

[0090] As a pulse wave feature quantity for determining an abnormal pressing force, "ab time" is used. For example, a determination threshold can be set in advance, and when "ab time" is below the determination threshold, it is determined that the pressing force is abnormal. In addition, the inverse of the pulse wave feature quantity "ab time" can be used in determining an abnormal pressing force, and when the inverse of "ab time" is above the determination threshold, it is determined that the pressing force is abnormal.

[0091] Figure 8 , Fig. 9 as well as Fig.10 It is shown respectively according to Figure 5 Graph showing changes over time of pulse wave characteristic quantities "1 / (VE0.5)", "a / S" and "(ab) / (ad)" calculated from the pulse wave shown in FIG. The horizontal axis represents time in units of [s]. Figure 8 The vertical axis is in units of [s -1 ] represents the pulse wave characteristic value "1 / (VE0.5)", Fig. 9 The vertical axis of represents the pulse wave characteristic quantity "a / S" in arbitrary units. Fig.10 The vertical axis of represents the pulse wave feature value "(ab) / (ad)" in dimensionless form. It can be seen that any pulse wave feature value becomes larger during the period of excessive pressing force than during the period of appropriate pressing force.

[0092] These pulse wave feature quantities are related to the steepness of the rising edge of the pulse wave. The fact that these feature quantities increase during the period of excessive pressing force can be explained as follows.

[0093] When the pressure applied to the skin increases, the capillaries are compressed and the blood flow is obstructed. As a result, blood is retained in the arterioles upstream of the capillaries, and the blood pressure in the arterioles increases. It is believed that when near-infrared light is used as the light for measurement, the effect of the increase in blood pressure in the arterioles 72 is significantly manifested, and thus, these pulse wave feature quantities used as peripheral blood pressure indicators become larger.

[0094] When the pressing force becomes excessive, the pulse wave characteristics "1 / (VE0.5)", "a / S" and "(ab) / (ad)" become larger. Therefore, for example, a judgment threshold can be set in advance, and when these pulse wave characteristics are above the judgment threshold, the pressing force is judged to be abnormal.

[0095] Fig.11 1 is a flowchart showing the process of the pressing force abnormality determination method according to the first embodiment. Fig.11 Each process shown in FIG. 1 is performed by the pulse wave feature quantity calculation unit 32 ( Figure 1 )implement.

[0096] First, the pulse wave feature quantity calculation unit 32 ( Figure 1 ) obtains the pulse wave signal from the light receiving element 53 (step S1). Then, the pulse wave is first differentiated to obtain the velocity pulse wave, and the pulse wave is second differentiated to obtain the acceleration pulse wave (step S2). Based on the pulse wave, velocity pulse wave, and acceleration pulse wave, the pulse wave feature is calculated for each heart beat and stored (step S3). For example, Figure 7 The pulse wave characteristic quantity "ab time" shown in Figure 8 The pulse wave feature value "1 / (VE0.5)" shown in Fig. 9 The pulse wave characteristic value "a / S" shown in Fig.10 At least one of the pulse wave feature quantities "(ab) / (ad)" shown in the figure is detected and stored.

[0097] Based on the calculated pulse wave feature, it is determined whether the pressing force is abnormal (step S4). For example, the magnitude of the calculated pulse wave feature is compared with a determination threshold, thereby determining whether the pressing force is abnormal (step S4). In addition, as the value of the pulse wave feature, the average value of the pulse wave feature values ​​calculated for a plurality of heart beats up to the current time point within a certain period of time or the average value of a certain number of beats may be used.

[0098] When the compression value is normal, various biological information, such as blood pressure, is obtained based on the pulse wave, velocity pulse wave, and acceleration pulse wave (step S5). In addition, the peak time of the waveform of each beat can be calculated, and the peak time difference between the beats can be calculated to calculate the pulse rate for each beat. The autonomic nervous function can be obtained based on the time series data of the pulse rate by using the maximum entropy method. The process of steps S1 to S5 is repeated until the user performs the end operation (step S7). In the case of an abnormal compression value, the abnormality notification unit 34 ( Figure 1 ) action to notify the user of the abnormality (step S6) and end the processing.

[0099] Next, the excellent effects of the first embodiment will be described.

[0100] In the first embodiment, when the pressing force is abnormal, the user is notified of the abnormality (step S6), so that the user can know that the reliability of the calculated values ​​of various indicators related to the biological information has decreased based on the abnormal pressing value. In addition, the user can adjust the pressing force to make it normal.

[0101] In the first embodiment, information for determining whether the pressing force is abnormal is obtained from the pulse wave, so it is not necessary to mount a pressure sensor for measuring the pressing force on the biological information measuring device. Therefore, the biological information measuring device can be miniaturized and reduced in cost.

[0102] As another method of determining whether the pressing force is abnormal without using a pressure sensor, it is also possible to use the light receiving element 53 ( Figure 1 ) is used to determine whether the pressing force is abnormal. However, the absolute value of the amount of light received varies according to the blood circulation state of the measured part. For example, when the blood circulation is poor, the amount of light received increases. In addition, the absolute value of the amount of light received also varies according to the measured part. For example, the blood vessel density on the ventral side of the distal segment of a finger is higher than that on the dorsal side, middle segment, coxae, back of the hand or wrist of the finger. The absolute value of the amount of light received varies according to the blood vessel density of the measured part. In addition, the absolute value of the amount of light received also varies according to the color of the skin. For example, when there is more melanin and the skin is dark, the amount of light received decreases.

[0103] In this way, the absolute value of the amount of received light is affected by various factors other than the pressing force, so in the method of determining whether the pressing force is abnormal based on the absolute value of the amount of received light, the accuracy of the determination is reduced. In the first embodiment, the absolute value of the amount of received light is not used in determining whether the pressing force is normal, so the influence of various factors that affect the intensity of the amount of received light can be eliminated, and the determination accuracy can be maintained at a high accuracy.

[0104] Next, a modification of the first embodiment will be described.

[0105] In the first embodiment, in determining whether the pressing force is abnormal, at least one of the pulse wave feature quantities "ab time", "1 / (VE0.5)", "a / S", and "(ab) / (ad)" that are affected by the steepness of the rising edge of the pulse wave is used, but other pulse wave feature quantities that are affected by the steepness of the rising edge of the pulse wave may also be used. In addition, it is preferable to use a pulse wave feature quantity that is less affected by the change in the absolute value of the amount of light received by the light receiving element 53.

[0106] In the first embodiment, in the determination of abnormal pressing force, the measured value of the pulse wave characteristic quantity obtained by using near-infrared light is used, but light of other wavelength ranges in which the pulse wave characteristic quantity changes when the pressing force becomes excessive may be used as the light for measurement. In addition to near-infrared light, red light may be used. For example, light included in the wavelength range of 600 nm or more and 950 nm or less may be used as the light for measurement.

[0107] In the first embodiment, in step S4 ( Fig.11 ) is determined to be abnormal in the pressing force, in step S6 ( Fig.11 ) to notify the user of abnormal pressing force. In addition, various biological information calculated from the pulse wave, such as pulse wave number, oxygen saturation, autonomic nerve function, respiratory rate, blood pressure, vascular resistance, blood flow, peripheral blood pressure index, hemodynamics, blood sugar level, etc., can also be displayed, and it can be notified that the reliability of these measured values ​​is low due to abnormal pressing force. In addition, it is preferred to notify the user to reduce the pressing force.

[0108] If these notifications are frequently made to the user, the user may feel annoyed. Therefore, normally no notification may be made, but when the excessive pressing force state continues for a long period of time, for example, for more than several hours, a notification of abnormal pressing force may be made.

[0109] [Second embodiment]

[0110] Next, refer to Figures 12 to 22 The pulse wave signal processing device, the biological information measuring device and the pressing force abnormality determination method of the second embodiment are described with reference to the accompanying drawings. Figures 1 to 11 The following is a description of the common structure of the pulse wave signal processing device, the biological information measuring device, and the pressure abnormality determination method of the first embodiment, which are illustrated in the accompanying drawings.

[0111] Fig.12 1 is a block diagram of the pulse wave signal processing device 30 of the second embodiment and a schematic diagram of a biological information measuring device having the pulse wave signal processing device 30. Figure 1 ) includes a light emitting element 51 and a light receiving element 53. In contrast, the photoelectric pulse wave sensor 50 of the biological information measuring device of the second embodiment includes another light emitting element 52 in addition to the light emitting element 51.

[0112] The two light emitting elements 51 and 52 output light of different wavelengths. For example, the light emitting element 51 on one side outputs near infrared light with a wavelength of more than 850nm and less than 950nm, and the light emitting element 52 on the other side outputs green light with a wavelength of more than 500nm and less than 550nm. In addition, as the light emitting element 52, a light emitting element that outputs light of a wavelength included in the wavelength range from blue to yellow-green can also be used. From the perspective of the light receiving element 53, the light emitting element 52 is arranged at a position closer than the light emitting element 51. The distance from the light receiving element 53 to the light emitting element 52 is marked as L2. Compared with green light, near infrared light is less absorbed by the organism. Therefore, it invades deeper areas of the organism.

[0113] Therefore, when near-infrared light is used as the light for measurement, the change of blood flow in the arteriole 72 distributed in the deep area is significantly reflected in the pulse wave. When green light is used as the light for measurement, the light does not penetrate into the deep area where the arteriole 72 is distributed, so the change of blood flow in the capillary 73 distributed in the shallow area is significantly reflected in the pulse wave, and the change of blood flow in the arteriole 72 is difficult to be reflected in the pulse wave. Fig.12 The arrow from the light emitting element 51 toward the light receiving element 53 shown in FIG. 5 shows that the information related to the blood flow of the arteriole 72 is reflected in the amount of light received by the light receiving element 53. The arrow from the light emitting element 52 toward the light receiving element 53 shows that the information related to the blood flow of the capillary 73 is reflected in the amount of light received by the light receiving element 53, and the information related to the blood flow of the arteriole 72 is not substantially reflected in the amount of light received by the light receiving element 53.

[0114] As described in the first embodiment, the distance L1 is preferably 5 mm or more and 20 mm or less. The distance L2 is preferably 1 mm or more and 3 mm or less so that information of a region shallow from the body surface 70 can be efficiently acquired.

[0115] The light emission control unit 31 causes the two light emitting elements 51 and 52 to emit light at different timings. The pulse wave measurement unit 36 ​​synchronizes the timing of receiving the light intensity signal from the light receiving element 53 with the timing of light emission of the light emitting elements 51 and 52, thereby separately acquiring the pulse wave obtained by the near infrared light and the pulse wave obtained by the green light.

[0116] Fig.13 This is a graph showing an example of changes over time in the amount of light received by the light receiving element 53 when the photoelectric pulse wave sensor 50 is in contact with the measured part and near-infrared light and green light are output from the light emitting elements 51 and 52, respectively. The horizontal axis represents time in units of [s], and the vertical axis represents the amount of light received in an arbitrary scale. Fig.13The thick solid line and dotted line in the graph shown in FIG. 1 represent the change in the amount of light received over time (photoplethysmogram) when near infrared light is used as the light for measurement and the change in the amount of light received over time (photoplethysmogram) when green light is used as the light for measurement, respectively. Figure 5 The same photoplethysmogram is shown in FIG.

[0117] It can be seen that when the photoelectric pulse wave sensor 50 applies excessive pressure to the measured part, the average value of the received light amount increases and the amplitude of the pulse wave decreases, similar to the pulse wave obtained by near-infrared light. The increase in the average value of the received light amount is caused by the excessive pressure, which hinders the blood flow.

[0118] Fig.14 This is a graph showing the waveform shape of the pulse wave obtained using green light for approximately one beat when the pressure applied by the photoelectric pulse wave sensor 50 to the measured part is within an appropriate range and when it is excessive. The horizontal axis represents time and the vertical axis represents the amount of light received. The thick solid line and the dotted line in the graph represent the waveform of the pulse wave when the pressure is within an appropriate range and when the pressure is excessive, respectively. It can be seen that the change caused by the pressure change in the pulse wave obtained using green light is greater than the change caused by the pressure change in the pulse wave obtained using near-infrared light ( Figure 6 For example, the difference in the steepness of the rising edge of the waveform between the case where the pressing force is appropriate and the case where the pressing force is excessive is smaller than when near-infrared light is used.

[0119] Fig.15 It shows that according to Fig.13 Graph showing the change over time of the pulse wave feature value "ab time" calculated from the pulse wave shown in FIG. The horizontal axis represents time in [s], and the vertical axis represents the pulse wave feature value "ab time" in [s]. Fig.15 The thick solid line and dotted line in the graph represent the "ab time" calculated based on the pulse wave obtained using near-infrared light and the "ab time" calculated based on the pulse wave obtained using green light, respectively. The "ab time" calculated based on the pulse wave obtained using green light is different from the "ab time" calculated based on the pulse wave obtained using near-infrared light, and no significant change is confirmed when the pressing force is excessive.

[0120] Fig.16 , Fig.17 as well as Fig.18 It is shown respectively according to Fig.13 Graph showing changes over time of pulse wave characteristic quantities "1 / (VE0.5)", "a / S" and "(ab) / (ad)" calculated from the pulse wave shown in FIG. The horizontal axis represents time in units of [s]. Fig.16 The vertical axis is in units of [s -1 ] represents the pulse wave characteristic value "1 / (VE0.5)", Fig.17 The vertical axis of represents the pulse wave characteristic quantity "a / S" in arbitrary units. Fig.18 The vertical axis represents the pulse wave characteristic quantity "(ab) / (ad)" in a dimensionless manner. Fig.16 , Fig.17 , Fig.18 The thick solid line and dotted line in the graph represent the pulse wave feature calculated based on the pulse wave obtained using near-infrared light and the pulse wave feature calculated based on the pulse wave obtained using green light, respectively. Compared with the pulse wave feature calculated based on the pulse wave obtained using near-infrared light, these pulse wave feature values ​​calculated based on the pulse wave obtained using green light do not show significant changes even when the pressure is excessive. This is because: Fig.14 As shown, the change in the waveform of the pulse wave is small when the pressing force is excessive.

[0121] The reason why a large change is observed in the pulse wave feature amount calculated based on the pulse wave obtained using near-infrared light when the pressing force is excessive, but a significant change is not observed in the pulse wave feature amount calculated based on the pulse wave obtained using green light, can be explained as follows.

[0122] When the pressure applied to the skin increases, the capillaries 73 ( Fig.12 ) is compressed and blood flow is obstructed. As a result, blood is retained in the upstream of the capillary 73, that is, the arteriole 72 ( Fig.12 ), the blood pressure in the arteriole 72 rises. It is considered that when near-infrared light is used as the light for measurement, the rise in blood pressure in the arteriole 72 is reflected in the pulse wave, thereby increasing the pulse wave feature amount.

[0123] When green light is used as the light for measurement, the increase in blood pressure in the arteriole 72 is hardly reflected in the pulse wave, and the change in blood pressure in the capillary 73 is mainly reflected in the pulse wave. When the capillary 73 is compressed by excessive pressure, the vascular resistance increases and the blood flow rate decreases. Blood pressure depends on the product of blood flow rate and vascular resistance, so no significant change in blood pressure in the capillary 73 is seen. Therefore, it is believed that when green light is used as the light for measurement, no significant change in the pulse wave feature value is seen.

[0124] like Fig.15 , Fig.16 , Fig.17 as well as Fig.18As shown in FIG. 1 , when the pressing force becomes excessive, the pulse wave feature quantity obtained by the near-infrared light changes significantly, but no significant change is observed in the pulse wave feature quantity obtained by the green light. That is, when the pressing force becomes excessive, the difference between the pulse wave feature quantity obtained by the near-infrared light and the pulse wave feature quantity obtained by the green light becomes larger than when the pressing force is within the appropriate range. The pressing determination unit 33 ( Fig.12 ) The pulse wave characteristic quantity obtained by using near-infrared light is compared with the pulse wave characteristic quantity obtained by using green light, and based on the comparison result of the two, a judgment is made as to whether the pressing pressure is abnormal.

[0125] Fig.19 , Fig. 20 , Fig.21 as well as Fig. 22 The graphs respectively show pulse wave feature quantities "ab time", "1 / (VE0.5)", "a / S", and "(ab) / (ad)" calculated based on pulse waves obtained from a plurality of subjects. The horizontal axis of each graph represents the pulse wave feature quantity calculated based on the pulse wave obtained using green light, and the vertical axis represents the pulse wave feature quantity calculated based on the pulse wave obtained using infrared light. The hollow circular mark represents the pulse wave feature quantity based on the pulse wave obtained when the pressing force is within an appropriate range, and the blackened circular mark represents the pulse wave feature quantity based on the pulse wave obtained when the pressing force is excessive.

[0126] according to Fig.19 It can be seen that there are subjects whose pulse wave characteristic quantity "ab time" is approximately the same when using near-infrared light and when using green light, and there are also many subjects whose pulse wave characteristic quantity "ab time" obtained by near-infrared light is shorter than the pulse wave characteristic quantity "ab time" obtained by green light. In addition, it can be seen that in the case of excessive pressing force, the pulse wave characteristic quantity "ab time" obtained by near-infrared light is less than 0.06s for all subjects who were confirmed to have excessive pressing force. Therefore, it can be said that the pulse wave characteristic quantity "ab time" measured using near-infrared light does not depend on the subject and is ideal as an indicator for determining abnormal pressing force.

[0127] according to Fig. 20 It can be seen that there are subjects whose pulse wave characteristic value "1 / (VE0.5)" is approximately the same when using near-infrared light and when using green light, and there are also many subjects whose pulse wave characteristic value "1 / (VE0.5)" obtained by using near-infrared light is larger than that obtained by using green light. In the case of excessive pressing force, there are also subjects whose pulse wave characteristic value "1 / (VE0.5)" obtained by using near-infrared light is larger than that obtained by using green light, but there are also subjects whose pulse wave characteristic value "1 / (VE0.5)" is approximately the same.

[0128] Fig.21 The pulse wave characteristic quantity "a / S" and Fig. 22 The pulse wave characteristic value "(ab) / (ad)" shown in Fig.19 The pulse wave characteristic value "1 / (VE0.5)" shown in FIG. can be explained as follows Fig.19 , Fig. 20 , Fig. 22 The distribution of the feature quantities is shown in .

[0129] When the pressing force becomes excessive, the capillaries 73 are compressed and the blood flow is obstructed, and the blood is retained in the arterioles 72 upstream of the capillaries 73. As a result, the blood pressure in the arterioles 72 rises, and the pulse wave feature quantities "1 / (VE0.5)", "a / S", and "(ab) / (ad)" obtained by near-infrared light increase. At this time, no significant change in these pulse wave feature quantities obtained by green light is observed. A subject whose pulse wave feature quantity obtained by near-infrared light becomes larger than that obtained by green light when the pressing force becomes excessive is considered to be in this state.

[0130] When the pressing force becomes excessive, the arteriole 72 is also compressed and the blood flow is obstructed. Therefore, the difference between the pulse wave feature quantity obtained by the near-infrared light and the pulse wave feature quantity obtained by the green light becomes smaller. A subject whose pulse wave feature quantity obtained by the near-infrared light and the pulse wave feature quantity obtained by the green light are substantially the same when the pressing force becomes excessive is considered to be in this state.

[0131] From the above considerations, it can be seen that the pulse wave feature values ​​"1 / (VE0.5)", "a / S", and "(ab) / (ad)" are effective for determining whether the pressing force is excessive within a certain range.

[0132] In particular, Fig.19 As shown in the figure, the pulse wave feature "ab time" obtained using near-infrared light for all subjects is smaller when the pressing force becomes excessive than when the pressing force is within the appropriate range. Therefore, the determination threshold can be set to a certain value, and when the measured value of the pulse wave feature "ab time" becomes less than the determination threshold, it is determined that the pressing force is excessive. Alternatively, an estimation formula that makes the degree of excessive pressing force greater as the pulse wave feature "ab time" is shorter can be prepared in advance, and the degree of excessive pressing force can be estimated based on the measured value of the pulse wave feature "ab time".

[0133] Next, the excellent effects of the second embodiment will be described.

[0134] In the second embodiment, the measurement value of the pulse wave feature quantity obtained by using near-infrared light and the measurement value of the pulse wave feature quantity obtained by using green light are compared to determine abnormality in pressing force, thereby improving determination accuracy.

[0135] Next, refer to Fig.23 A living body information measuring device according to a modified example of the second embodiment will be described.

[0136] Fig.23 1 is a block diagram of a pulse wave signal processing device according to a variation of the second embodiment and a schematic diagram of a biological information measuring device having the pulse wave signal processing device. Fig.12 ), a light receiving element 53 detects light reflected from two light emitting elements 51 and 52 that output light of different wavelengths at a measured portion. Fig.23 In the modified example shown in FIG. 1 , the photoelectric pulse wave sensor 50 includes two light receiving elements 53 and 54. The light receiving element 53 detects the light reflected from the measured part outputted from the light emitting element 51, and the light receiving element 54 detects the light reflected from the measured part outputted from the light emitting element 52.

[0137] An optical filter that transmits light output from the light emitting element 51 and blocks light of other wavelength ranges is disposed on the light receiving surface of one light receiving element 53. An optical filter that transmits light output from the light emitting element 52 and blocks light of other wavelength ranges is disposed on the light receiving surface of the other light receiving element 54.

[0138] The preferred ranges of the distance L1 from the light receiving element 53 to the light emitting element 51 and the distance L2 from the light receiving element 54 to the light emitting element 52 are respectively the same as those of the biological information measuring device ( Fig.12 )The preferred ranges of distances L1 and L2 are the same.

[0139] As in this variation, a plurality of light receiving elements 53 and 54 may be respectively arranged for a plurality of light emitting elements 51 and 52. In this variation, it is not necessary to stagger the light emission timings of the two light emitting elements 51 and 52. The two light emitting elements 51 and 52 may be always illuminated, or the two light emitting elements 51 and 52 may be independently pulsed at a certain frequency.

[0140] [Third embodiment]

[0141] Next, refer to Fig.24 The third embodiment of the biological information measuring device is described below. Figures 12 to 22 The following is a description of the common structure of the pulse wave signal processing device and the biological information measuring device of the second embodiment, which is described with reference to the accompanying drawings.

[0142] Fig.24 It is a perspective view of a part of the biological information measuring device of the third embodiment and a block diagram of the pulse wave signal processing device 30.

[0143] Two light emitting elements 51, 52 and a light receiving element 53 are mounted on the inner surface of the ring-shaped wearing component 60. The wearing component 60 is worn on the user's finger for use. As the wearing component 60, a plurality of sizes of wearing components 60 are prepared according to the thickness of the user's finger. When the wearing component 60 is worn on the finger, the light emitting elements 51, 52 output light toward the finger. The light receiving element 53 is mounted at the position where the light reflected inside the finger is incident. The wearing component 60 is also assembled with a light control unit 31, a pulse wave measurement unit 36 ​​and a communication unit 55. The light control unit 31, the pulse wave measurement unit 36 ​​and the communication unit 55 can also be composed of an integrated circuit. The wearing component 60 and the light emitting elements 51, 52, the light receiving element 53, the light control unit 31, the pulse wave measurement unit 36 ​​and the communication unit 55 mounted on the wearing component 60 are called "ring-shaped device 61".

[0144] The functions of the pulse wave signal processing device 30 are realized by the ring device 61, the portable information terminal 62, and the server 63. As the information terminal 62, for example, a smartphone, a tablet terminal, a notebook personal computer, etc. are used. The information terminal 62 includes a communication unit 37, a control unit 35, and an abnormality notification unit 34. The server 63 includes a communication unit 38, a pulse wave feature amount calculation unit 32, and a pressure determination unit 33.

[0145] Data communication is performed between the communication unit 55 of the ring device 61 and the communication unit 37 of the information terminal 62, and between the communication unit 37 of the information terminal 62 and the communication unit 38 of the server 63. For example, various standard short-range wireless communication methods are used in the communication between the ring device 61 and the information terminal 62. For the communication between the information terminal 62 and the server 63, a communication network such as the Internet is used.

[0146] The light emission control unit 31 controls the pulse light emission of the light emitting elements 51 and 52. The pulse wave measurement unit 36 ​​reads the signal from the light receiving element 53. For example, the light emission control unit 31 of the ring device 61 receives an instruction from the control unit 35 of the information terminal 62, and causes the light emitting elements 51 and 52 to emit light based on the received instruction. The pulse wave measurement unit 36 ​​reads the intensity signal of the light received from the light receiving element 53 and transmits it to the server 63 via the information terminal 62. The pulse wave feature quantity calculation unit 32 and the pressure determination unit 33 of the server 63 are connected to the pulse wave signal processing device 30 ( Fig.12 ) Similarly, the pulse wave characteristic quantity is calculated based on the pulse wave to determine whether the pressing force is abnormal.

[0147] The pressing force determination unit 33 transmits the determination result to the control unit 35 of the information terminal 62. Upon receiving the determination result that the pressing force is abnormal, the control unit 35 controls the abnormality notification unit 34 to notify the user of the abnormal pressing force.

[0148] When the ring size is too large, a gap is generated between the photoelectric pulse wave sensor 50 and the skin, and the pulse wave signal cannot be stably measured. When the ring size is too small, the photoelectric pulse wave sensor 50 presses the skin too much, and the reliability of the biological information estimation result decreases. Next, a method of selecting a ring-shaped device 61 of a suitable size from a plurality of ring-shaped devices 61 of different sizes is described.

[0149] First, the user sequentially wears a plurality of ring-shaped devices 61 of different sizes, and operates the photoelectric pulse wave sensor 50 and the pulse wave signal processing device 30. A ring-shaped device 61 of a size slightly larger than the size of the ring-shaped device 61 when the pressing force is determined to be excessive, for example, a size one or two levels larger, can be selected as the most appropriate size of the ring-shaped device 61. By selecting a size one or two levels larger than the size determined to be excessive in the pressing force, it is possible to avoid selecting a ring-shaped device 61 of an inappropriate size.

[0150] Next, the excellent effects of the third embodiment will be described.

[0151] The epidermis of the finger is relatively thin, so it is suitable for obtaining the pulse wave obtained using the photoelectric pulse wave sensor 50. In addition, the capillary path is not complicated compared to the face, so the value of the pulse wave feature is easy to stabilize. Therefore, the reliability of various biological information obtained from the pulse wave is improved. In addition, the following excellent effect can be obtained: when the biological information measurement device is used continuously or intermittently, even if the ring-shaped device 61 is worn on the finger for a long time, there is little sense of discomfort or discomfort.

[0152] When the size of the ring-shaped device 61 is not appropriate, the pulse wave cannot be stably measured, or the reliability of the biological information estimation result decreases. In the third embodiment, a ring-shaped device 61 of an appropriate size can be selected from a plurality of ring-shaped devices 61 of different sizes. By selecting the ring-shaped device 61 of an appropriate size, the pulse wave can be stably measured, and the reliability of the biological information estimation result can be improved.

[0153] Next, a modification of the third embodiment will be described.

[0154] The information terminal 62 may be used to implement a part or all of the functions of the server 63. In addition, the ring-shaped device 61 may be used to implement a part of the functions of the information terminal 62. For example, the ring-shaped device 61 may be used to implement the function of the abnormality notification unit 34. For example, a vibration generator may be mounted on the wearing member 60, and when it is determined that the pressing force is abnormal, the vibration generator is activated to vibrate the wearing member 60.

[0155] The pressure determination unit 33 preferably has the following functions as described in the second embodiment: Fig.19 ) is shorter, the greater the excessive degree of pressing force is, the excessive degree of pressing force is estimated based on the measured value of the pulse wave feature "ab time", and the excessive degree is notified. When the finger is bent while wearing the ring-shaped device 61, the pressing force increases, and when the finger is extended, the pressing force decreases. The abnormality notification unit 34 indicates the bending or extension of the finger to the user.

[0156] The pressing determination unit 33 determines whether the size of the ring-shaped device 61 is appropriate based on the change in the excessive degree of pressing force when the user extends the finger and bends the finger, and the abnormality notification unit 34 notifies the user of the determination result. In this way, the ring-shaped device 61 of the appropriate size can be selected with high accuracy by a simple method.

[0157] Next, other modified examples of the third embodiment will be described.

[0158] The ring-shaped device 61 of the living body information measuring device of the third embodiment is worn on a finger, but a device of a shape worn on a part other than a finger may be used instead of the ring-shaped device 61. For example, a wearable device of a shape worn on a wrist, neck, face, ear, etc. may be used. In addition, the living body information measuring device is not necessarily wearable, and may be a device that measures living body information by pressing a finger against the photoelectric pulse wave sensor 50 as needed. For example, the living body information measuring device may be a mobile device such as a smart phone, or may be a fixed device.

[0159] In a mobile or fixed biological information measuring device, it is preferred that when the user brings the measured part into contact with the photoelectric pulse wave sensor 50, the pulse wave signal processing device 30 determines whether the pressing force is within an appropriate range. In the case where the photoelectric pulse wave sensor unit of the biological information measuring device is a wearable device, it is preferred that when the wearable device is worn, the pulse wave signal processing device 30 determines whether the pressing force is within an appropriate range. For example, in the case where the wearable device is a bracelet-type or watch-type device worn on the wrist, it is preferred that the pulse wave is measured while being worn, and when it is determined that the pressing force is abnormal, the abnormality notification unit 34 notifies the user to loosen the belt.

[0160] The above-mentioned embodiments are illustrative, and it is self-evident that the structures shown in different embodiments can be partially replaced or combined. The same effects brought about by the same structure of multiple embodiments are not mentioned one by one according to each embodiment. In addition, the present invention is not limited to the above-mentioned embodiments. For example, various changes, improvements, combinations, etc. can be made, which is obvious to those skilled in the art.

[0161] Description of Reference Numerals

[0162] 30: Pulse wave signal processing device; 31: Light emitting control unit; 32: Pulse wave characteristic quantity calculation unit; 33: Pressing judgment unit; 34: Abnormality notification unit; 35: Control unit; 36: Pulse wave measurement unit; 37, 38: Communication unit; 50: Photoelectric pulse wave sensor; 51, 52: Light emitting element; 53, 54: Light receiving element; 55: Communication unit; 56: Control unit; 60: Wearing component; 61: Ring-shaped device; 62: Information terminal; 63: Server; 70: Body surface; 71: Epidermal area; 72: Arteriole; 73: Capillary.

Claims

1. A pulse wave signal processing device, comprising: a pulse wave feature value calculation unit that calculates a pulse wave feature value associated with a steepness of a rising edge of a pulse wave measured by the photoelectric pulse wave sensor; and The pressing determination unit determines whether the pressing force, which is the pressure with which the photoelectric pulse wave sensor presses the measurement site, falls within an appropriate range based on the value of the pulse wave feature value calculated by the pulse wave feature value calculation unit.

2. The pulse wave signal processing device according to claim 1, wherein: The pulse wave feature includes information on a time difference between a peak of an a wave and a peak of a b wave of an acceleration pulse wave obtained by performing a second-order differentiation on the pulse wave.

3. The pulse wave signal processing device according to claim 1 or 2, wherein: The pulse wave feature includes information on the width of a peak that first appears in one beat of a velocity pulse wave obtained by first-order differentiation of the pulse wave.

4. The pulse wave signal processing device according to any one of claims 1 to 3, wherein: The pulse wave feature includes information on the ratio of the peak value of the a wave of the acceleration pulse wave obtained by performing a second-order differentiation on the pulse wave to the amplitude of the pulse wave.

5. The pulse wave signal processing device according to any one of claims 1 to 4, wherein: The pulse wave feature includes information on the ratio of the difference between the peak value of the a wave and the peak value of the b wave to the difference between the peak value of the a wave and the peak value of the d wave of the acceleration pulse wave obtained by performing a second-order differentiation on the pulse wave.

6. The pulse wave signal processing device according to any one of claims 1 to 5, wherein: The device further includes an abnormality notification unit configured to notify that the pressing force is abnormal when the pressing force determination unit determines that the pressing force does not fall within the appropriate range.

7. A biological information measuring device comprising: The pulse wave signal processing device according to any one of claims 1 to 6; and The photoelectric pulse wave sensor measures the pulse wave of the measured part and inputs the measurement result to the pulse wave signal processing device. in, The photoelectric pulse wave sensor includes at least one light emitting element and a light receiving element that detects light output from the at least one light emitting element after being reflected by the measurement site or light after being transmitted through the measurement site.

8. The biological information measuring device according to claim 7, wherein: The at least one light emitting element includes a first light emitting element that outputs light included in a wavelength range from red to near infrared.

9. The biological information measuring device according to claim 8, wherein: The light receiving element detects light reflected at the measured site, and a distance between the first light emitting element and the light receiving element is greater than or equal to 5 mm and less than or equal to 20 mm.

10. The biological information measuring device according to any one of claims 7 to 9, wherein: The at least one light emitting element includes two light emitting elements that output light of different wavelengths, The pressure determination unit calculates a pulse wave feature value associated with the steepness of rising edges of the two pulse waves measured using light outputted from the two light emitting elements, respectively. The pressing force determination unit compares the values ​​of the two pulse wave feature quantities obtained from the two pulse waves measured using the light outputted from the two light emitting elements, respectively, and determines whether the pressing force falls within the appropriate range based on the comparison result.

11. The biological information measuring device according to claim 10, wherein: One of the two light emitting elements includes a second light emitting element that outputs light included in a wavelength range from blue to yellow-green.

12. The biological information measuring device according to claim 11, wherein: The light receiving element detects light reflected at the measured site, and a distance between the second light emitting element and the light receiving element is greater than or equal to 1 mm and less than or equal to 3 mm.

13. The biological information measuring device according to any one of claims 7 to 12, wherein: It also includes a wearing member for wearing on a finger, The at least one light emitting element and the light receiving element are mounted on the wearing member, and when the wearing member is worn on a finger, the at least one light emitting element outputs light toward the finger, and the light reflected inside the finger is incident on the light receiving element.

14. The biological information measuring device according to claim 13, wherein: The pressing determination section has a function of determining whether the size of the wearing member is appropriate based on the pressing force.

15. A method for determining abnormal pressing force, wherein: calculating a pulse wave feature value associated with the steepness of the rising edge of the pulse wave measured by the photoelectric pulse wave sensor in contact with the measured part, Based on the value of the pulse wave feature amount obtained by calculation, it is determined whether or not the pressing force, which is the pressure with which the photoelectric pulse wave sensor presses the measurement site, is abnormal.

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