Pulse wave detection system

Abstract

Provided is a pulse wave detection system comprising: a detection unit that is brought into contact with an arm to be subjected to pulse wave detection; a swinging section that has the detection unit provided thereto and makes it possible to swing the detection unit; and a calculation unit that acquires a pulse wave signal on the basis of a signal detected by the detection unit.

Description

[Technical Field]

[0001] The present disclosure relates to a pulse wave detection system. [Background technology]

[0002] Pulse diagnosis is a unique diagnostic method in traditional Chinese medicine that has been developed through clinical experience over thousands of years. In recent years, pulse diagnosis has become increasingly digitalized, and instead of doctors measuring the patient's pulse with their fingers, sensor-based pulse wave detection and disease diagnosis technologies have been developed.

[0003] Various sensors that detect pulsation are used in this sensing core, such as piezoelectric sensors, silicon piezo-resistive sensors, acceleration sensors, angular velocity sensors, magnetic sensors, and force sensors, and each type of sensor has its own strengths and weaknesses.

[0004] A method for detecting the pulse wave of the radial artery using a barometric pressure sensor has been known for some time (for example, Patent Document 1). This method can measure the pulse over the entire sensing contact surface, which is similar to the sensation felt by a doctor's finger. Furthermore, the combination of an air chamber with an opening and a barometric pressure sensor makes pulse wave detection even more convenient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-48942 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional techniques have had the problem that even when a barometric pressure sensor is used, noise is mixed into the pulse wave signal due to the influence of external factors such as those described below, making it difficult to detect an accurate pulse wave.

[0007] For example, in the initial state when the sensing surface is attached to the skin surface or during the tens of seconds while measuring the pulse wave, the sensing surface and the skin surface may no longer satisfy the parallel condition. In this case, the difference in the contact between the sensing surface and the skin surface had an effect of up to approximately 1200 Pa on the obtained differential pressure (example of the results of a specified evaluation). Furthermore, depending on the environmental conditions, there may be a difference of several degrees to several tens of degrees between the sensor temperature and body temperature. In this case, the sensor temperature before and after measurement fluctuates due to the influence of body temperature, resulting in a difference of up to approximately 400 Pa in the obtained differential pressure (an example of the results of a specified evaluation). Additionally, air flow at the measurement site caused a momentary atmospheric pressure fluctuation of approximately 100 Pa (example of the results of a specified evaluation). In this case, the dynamic fluctuation of the environmental air pressure may be mixed into the differential pressure. In addition, the initial atmospheric pressure value can vary by up to 40,000 Pa depending on the altitude of the measurement area or the time of year, which can mean that pulse wave signals with the same output cannot be obtained even with the same pulsation.

[0008] Due to the influence of external factors such as those mentioned above, the pulsation signal detected from the differential pressure varies by several percent to several tens of percent. Therefore, in order to detect the pulse wave correctly, it is necessary to reduce the influence of external factors.

[0009] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a pulse wave detection system that can improve the accuracy of data used in pulse diagnosis. [Means for solving the problem]

[0010] One aspect of the present disclosure is a pulse wave detection system including a detection unit that is brought into contact with the arm whose pulse wave is to be detected, a swivel unit that has the detection unit mounted thereon and that can swivel the detection unit, and a calculation unit that acquires a pulse wave signal based on a signal detected by the detection unit. [Effects of the Invention]

[0011] The pulse wave detection system according to the present disclosure can improve the accuracy of data used in pulse diagnosis. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an external view showing an example of a schematic configuration of a pulse wave detection system according to an embodiment. [Figure 2] FIG. 1 is a cross-sectional view showing an example of a schematic configuration of a sensing head according to an embodiment. [Figure 3] FIG. 2 is a side view showing an example of the configuration of the oscillating portion according to the embodiment. [Figure 4] FIG. 10 is a diagram illustrating the definition of a solid angle according to an embodiment. [Figure 5] FIG. 10 is a diagram showing a table showing evaluation results of the oscillating sections according to the examples and the comparative examples. [Figure 6] FIG. 10 is a diagram showing the relationship between the axial angle deviation and the signal amplitude in the examples and the comparative example. [Figure 7] FIG. 2 is a diagram showing an initial state before the tip of the pulse wave sensor according to the embodiment comes into contact with the skin. [Figure 8] 10A and 10B are diagrams illustrating a state after the tip of the pulse wave sensor according to the embodiment has been brought into close contact with the skin. [Figure 9] FIG. 10 is a diagram showing a state in which the tip of a pulse wave sensor according to a comparative example is in contact with the skin. [Figure 10] FIG. 10 is a diagram showing a table showing the evaluation results of the influence of steps according to an example and a comparative example. [Figure 11] 10A and 10B are diagrams illustrating the influence of noise caused by pressure in the examples and the comparative example. [Figure 12] FIG. 10 is a cross-sectional view showing an example of a head structure having a step according to an embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing an example of a head structure according to a comparative example that does not have the required step. [Figure 14] FIG. 10 is a diagram showing a table showing evaluation results of the rigidity center portion according to the example and the comparative example. [Figure 15] FIG. 10 is a diagram showing the relationship between positional deviation and intensity change in the examples and comparative examples. [Figure 16] FIG. 10 is a diagram showing an example of eccentricity evaluation according to the embodiment. [Figure 17] FIG. 2 is a cross-sectional view showing an example of the structure of a diaphragm having a rigid center according to an embodiment. [Figure 18] FIG. 10 is a cross-sectional view showing an example of the structure of a diaphragm having uniform hardness and thickness according to a comparative example. [Figure 19] FIG. 10 is a diagram showing a table showing evaluation results of hysteresis according to the examples. [Figure 20] FIG. 10 is a diagram showing the evaluation results of hysteresis according to the examples. [Figure 21] FIG. 10 is a diagram for explaining a method for evaluating hysteresis according to an embodiment. [Figure 22] FIG. 10 is a diagram showing a table showing evaluation results of temperature control according to an example and a comparative example. [Figure 23] FIG. 10 is a diagram showing the fluctuations in temperature and internal pressure inside the sealed space measured when the temperature of the sealed space in the example is controlled to a body surface temperature of 34° C. [Figure 24] FIG. 10 is a diagram showing fluctuations in temperature and internal pressure inside a sealed space when the body surface temperature is 34° C. and the sealed space is not heated or temperature controlled, according to a comparative example. [Figure 25] 10A and 10B are diagrams showing the configuration of a frame having a cut edge according to an embodiment. [Figure 26] FIG. 10 is a diagram showing the atmospheric pressure fluctuation cancellation effect of a frame having a cut edge according to an embodiment. [Figure 27] FIG. 10 is a diagram showing the atmospheric pressure fluctuation cancellation effect of a frame having no cut edge according to a comparative example. [Figure 28] FIG. 2 is a diagram showing an example of an installation mode of a laser pointer according to an embodiment. [Figure 29] FIG. 10 is a diagram showing an example of a cross mark of the laser pointer according to the embodiment. [Figure 30] FIG. 10 is a diagram showing a table showing the correction effect of the initial atmospheric pressure value according to an example and a comparative example. [Figure 31] FIG. 10 is a diagram showing the effect of correcting the initial atmospheric pressure value according to an example and a comparative example. [Figure 32]FIG. 10 is a diagram showing a table showing the correction effect of zero point correction according to the embodiment. [Figure 33] FIG. 10 is a diagram showing the correction effect of temperature fluctuation correction according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] [Pulse wave detection system] FIG. 1 is an external view showing an example of a schematic configuration of a pulse wave detection system 1 according to an embodiment. For convenience of explanation, an XYZ Cartesian coordinate system, which is a three-dimensional Cartesian coordinate system, is shown in Fig. 1. In this embodiment, the positive side of the Z axis is assumed to point upward, the negative side of the Z axis is assumed to point downward, and a plane perpendicular to the up-down direction (horizontal plane) is assumed to be parallel to the XY plane.

[0015] The pulse wave detection system 1 comprises a sensing head 11 that detects pulse waves, a housing unit 12 that moves the sensing head 11 up and down, and a positioner 13 that adjusts the position of the hand (beyond the wrist) connected to the arm 21. The positioner 13 is composed of a first member 13a that is placed on the wrist side of the arm 21, and a second member 13b on which the arm 21 is placed. The positioner 13 can adjust the hand (from the wrist down) in the X-axis direction, Z-axis direction, and rotation about the X-axis. The positioner 13 also allows the arm 21 to be adjusted for rotation about the Y axis.

[0016] <Sensing head> FIG. 2 is a cross-sectional view showing an example of a schematic configuration of the sensing head 11 according to the embodiment. FIG. 2 shows an XYZ Cartesian coordinate system similar to that shown in FIG. The sensing head 11 includes a housing (head housing 51), a support unit 53, a laser pointer unit 54, and a calculation unit 55. The sensing head 11 also includes a hollow portion 52 provided at the tip side (lower side) of the head housing 51, a swivel portion 61 (swivel head) in which a rotor (spherical rotor) is fitted into the hollow portion 52, and a detection portion W1 provided at the tip side (lower side) of the swivel portion 61.

[0017] In this embodiment, the detection unit W1 can be swung by the swiveling unit 61 on which the detection unit W1 is provided. The detection section W1 includes a frame 62, a diaphragm 63, and a sealed space (sealed space section 64) inside the upper side of the diaphragm 63. The detection unit W1 includes an internal air pressure sensor 82 and an internal temperature sensor 83 inside the sealed space portion 64. The detection unit W1 is a part that is brought into contact with the arm whose pulse wave is to be detected, and the lower part (tip) where the frame 62 and the diaphragm 63 are arranged is brought into contact with the arm. The detection unit W1 includes an analog temperature control unit 71. The analog temperature control unit 71 has a heater and a temperature control unit. The sensing head 11 includes an atmospheric pressure sensor 81 on the support portion 53 .

[0018] In this embodiment, the head housing 51 has a shape that extends in the vertical direction, and the support portion 53 has a shape that extends in the horizontal direction from above the head housing 51, but the shapes are not limited to this. The support portion 53 is a member for supporting the sensing head 11 by the housing portion 12.

[0019] In this embodiment, the sensing head 11 is made up of a group of sensors, an attachment, and a calculation unit 55. The sensor group includes an atmospheric pressure sensor 81 , an internal air pressure sensor 82 , and an internal temperature sensor 83 . The attachment includes a swinging section 61 and a detection section W1 (an analog temperature control section 71, a frame 62, and a diaphragm 63).

[0020] In this embodiment, various values ​​may be expressed as follows. t represents time. In the following explanation, the time t may be omitted. S(t) represents the pulse wave signal at time t. Po represents the atmospheric pressure reference value of 101325 Pa. P1(0) represents the initial value of the atmospheric pressure (air pressure of the reference sensor / Pa). P1(t) represents the atmospheric pressure (air pressure of the reference sensor / Pa) at time t. P2(0) represents the initial value / Pa of the air pressure inside the sealed space (internal air pressure). P2(t) represents the air pressure (internal air pressure) / Pa inside the sealed space at time t. T2(0) represents the initial value / K of the temperature inside the sealed space (internal temperature). T2(t) represents the temperature (internal temperature) / K inside the sealed space at time t. C represents a correction coefficient due to the head structure and diaphragm characteristics. Note that one or more measurement results of P1(t), P2(t), and T2(t) may be acquired as absolute values.

[0021] In this embodiment, the pulse wave detection system 1 dynamically reduces the influence of external factors, and detects a pulse waveform with less distortion and accurate pulse wave intensity.

[0022] Atmospheric pressure sensor 81 measures atmospheric pressure (ambient atmospheric pressure). Atmospheric pressure sensor 81 is, for example, model number MEMS Sensor ICP-10100. In this embodiment, the atmospheric pressure sensor (atmospheric pressure sensor 81) built into pulse wave detection system 1 measures atmospheric pressure P1(t) with an accuracy of ±1 Pa. In this embodiment, the atmospheric pressure sensor 81 is placed at a distance of about 10 cm or more from the wrist and head portion so as not to be affected by body temperature or heat generated by the pulse wave monitor.

[0023] The internal air pressure sensor 82 measures the air pressure inside the sealed space. The internal air pressure sensor 82 is, for example, a MEMS Sensor ICP-10100 model. In this embodiment, the air pressure sensor (internal air pressure sensor 82) built into the pulse wave detection system 1 measures the internal pressure P2(t) of the sealed space with an accuracy of ±1 Pa. An internal air pressure sensor 82 is disposed within the sealed space.

[0024] The internal temperature sensor 83 measures the temperature inside the sealed space. In this embodiment, the internal temperature sensor 83 is configured using, for example, a thermometer built into the MEMS Sensor ICP-10100. The internal temperature sensor 83 measures the temperature T2(t) of the gas in the sealed space with an accuracy of ±0.4°C. An internal temperature sensor 83 is disposed within the sealed space.

[0025] In this embodiment, a swivel attachment (swivel portion 61) is employed. In this embodiment, a frame with four 0.3 mm cuts and a step of 0 mm is used. The step is set to, for example, 0 to 0.2 mm. The diaphragm used is one that is composed of a rigid center and a flexible peripheral portion. In this embodiment, a diaphragm 63 with a diameter of 8 mm is used, which is composed of a rigid center made of SUS with a diameter of 5 mm and a thickness of 0.2 mm, and a flexible peripheral portion made of silicone rubber with a diameter of 30 mm and a thickness of 0.3 mm. The flexible peripheral portion is made of soft resin with a hardness of 20 to 50 degrees and a thickness of 0.1 to 0.5 mm, for example. Φ represents the diameter. In this embodiment, a silicone rubber diaphragm is placed over the gas chamber, and the frame 62 is tightened to seal the air in the sealed space, thereby ensuring the formation of a sealed space. The maximum displacement (ΔZ) of the diaphragm 63 is 300 μm to 1000 μm, for example, 600 μm to 900 μm. The full scale span (FSS) is 3000 to 10000 Pa, and may be, for example, about 6000 Pa.

[0026] In this embodiment, an analog temperature control unit 71 is provided, which includes three heaters attached to the surface of the frame 62 and has a target temperature set to 34°C. The analog temperature control unit 71 is controlled using software. The temperature control unit controls the temperature to within ±0.5°C of the set temperature by controlling the on / off of the three heaters.

[0027] The laser pointer unit 54 includes two 1 mW line-focus laser pointers, which are positioned as shown in Figure 2 and operate to present a cross mark on the surface of the skin. Before measuring the pulse wave, use your finger to determine the position where the pulse is strongest (directly above the radial artery) and align the intersection of the cross marks on the laser pointer with that position. The tip of the pulse wave sensor is then brought into contact with the skin surface, and the pressure to be measured is applied, and the pulse wave signal is measured by the pulse wave sensor.

[0028] In this embodiment, a calculation unit 55 having the following correction function is employed. The calculation unit 55 performs calculations for three corrections: initial atmospheric pressure correction, zero point correction of the atmospheric pressure sensor, and temperature fluctuation correction.

[0029] The measurement result S0(t) of the air pressure (difference) without correction is expressed by the following formula: S0(t)={P2(t)-P1(t)}

[0030] When the measurement result is subjected to an initial atmospheric pressure correction, the correction result S1(t) is expressed by the following equation. S1(t)={P2(t)-P1(t)}×K K=Po / P1(0)

[0031] When the measurement result is subjected to zero point correction of the atmospheric pressure sensor, the correction result S2(t) is expressed by the following equation. S2(t)={P2(t)-P1(t)}-{P2(0)-P1(0)} Here, ΔP(t) = P2(t) - P1(t), and the initial output difference ΔP(0) = P2(0) - P1(0).

[0032] When temperature fluctuation correction is performed on the measurement result, the correction result S3(t) is expressed by the following equation. S3(t)={P2(t)-P1(t)}-{T2(t)-T2(0)} / T2(0)×P2(0)×C Here, ΔP(T2) = {T2(t) - T2(0)} / T2(0) × P2(0) × C.

[0033] When these three corrections are made, the calculation unit 55 acquires the measured raw signals P1(t), P2(t), and T2(t), and calculates the pulse diagnosis signal S(t) when the three corrections are made by performing calculations using an arithmetic formula that aligns the three corrections. S(t)=[{P2(t)-P1(t)}-{P2(0)-P1(0)}-{T2(t)-T2(0)} / T2(0)×P2(0)×C]×Po / P1(0)

[0034] Calculation unit 55 acquires a pulse wave signal (for example, a corrected pulse wave signal) based on the signal detected by detection unit W1. Calculation unit 55 stores the calculated pulse wave signal S(t) in a hard disk (HDD) of a computer (for example, a PC) or in a recording medium of a microcomputer, for example, at a sampling rate of 400 Hz or higher. Furthermore, calculation unit 55 has the function of displaying the calculated pulse wave signal on a monitor screen in real time.

[0035] In this embodiment, the case where the calculation unit 55 is provided in the sensing head 11 is shown, but the calculation unit 55 may be provided in another location. Furthermore, in this embodiment, calculation unit 55 performs calculations in real time while pulse wave measurement is being performed, but as another example, data resulting from pulse wave measurement may be temporarily stored in a memory unit, and then calculations may be performed by calculation unit 55 based on the data stored in the memory unit. In this other example, for example, the memory unit may be included in the components shown in Fig. 1, and the functions of calculation unit 55 may be provided in a computer separate from the components shown in Fig. 1.

[0036] In this way, pulse wave detection system 1 according to this embodiment can dynamically detect atmospheric pressure P1(t), internal pressure P2(t) of the sealed space of the detection unit, and temperature T2(t) of the sealed space of the detection unit during pulse wave measurement. Based on the input data P1(t), P2(t), and T2(t), pulse wave detection system 1 can obtain pulse wave signal S(t) as a corrected result that reduces variations in the pulse wave signal due to changes in external disturbance factors. The pulse wave signal S(t) is a function of the input data P1(t), P2(t), and T2(t). In pulse wave detection system 1, noise caused by disturbance factors can be reduced using a predetermined correction formula. In pulse wave detection system 1, such correction can also be performed in real time.

[0037] <Swinging section (Example 1)> The oscillating portion 61 will be described with reference to FIGS. FIG. 3 is a side view showing an example of the configuration of the oscillating portion 61 according to the first embodiment. For convenience of explanation, FIG. 3 shows an XYZ Cartesian coordinate system similar to that shown in FIG.

[0038] The oscillating portion 61 is configured by integrating a rotor 61a, which is a spherical rotor arranged on the upper side, and a shaft portion 61b arranged on the lower side. The oscillating portion 61 (rotor 61a and shaft portion 61b) has a shape that is rotationally symmetrical with respect to a central axis 61c that is parallel to the vertical direction. The rotor 61a has a smooth spherical surface on the upper side, the radius of curvature of which is, for example, 12.25 mm, but is not limited to this value. In rotor 61a, the width L1 (width in the direction parallel to the Y-axis) of the portion supporting the spherical surface is, for example, 8.6 mm, but is not limited to this value.

[0039] The oscillating section 61 can rotate up to, for example, θ=15 degrees (solid angle ω=0.2), but is not limited to this value. The material of the oscillating portion 61 is, for example, SUS304, but is not limited to this material. The swinging portion 61 has a frame 62, a diaphragm 63, and the like connected to the lower side thereof, which constitute the pulse wave sensor.

[0040] Here, the solid angle is defined. FIG. 4 is a diagram illustrating the definition of a solid angle according to the first embodiment. FIG. 4 shows the radius of curvature r and the angle θ of a sphere. The solid angle ω is defined as ω = 2π(1 - cosθ).

[0041] The position of the radial artery (approximately 3 mm in diameter) varies between individuals, meaning that the tip of the pulse wave sensor may not be in close contact with the skin surface even when pressed against the arm (see FIG. 9 for Comparative Example 1). In contrast, in the configuration using the oscillating unit 61 according to Example 1, even if the wrist angle changes within θ=15 degrees (solid angle ω~0.2), the surface of the diaphragm and the skin surface can always be kept parallel to each other. Generally, it is not easy to visually recognize an angle deviation of θ=10 degrees or less, so in Example 1, the oscillating section 61 is made capable of compensating for an angle deviation of θ=15 degrees or less.

[0042] FIG. 5 is a diagram showing a table T1 showing the evaluation results of the oscillating parts according to Example 1 and Comparative Example 1. As shown in FIG. Table T1 shows the correspondence between the angle of the oscillating part and the signal amplitude (arbitrary unit (au)) for each of Example 1 shown in FIGS. 7 and 8 and Comparative Example 1 shown in FIG.

[0043] FIG. 6 is a diagram showing the relationship between the axial angle deviation and the signal amplitude according to Example 1 and Comparative Example 1. In FIG. In the graph shown in FIG. 6, the horizontal axis represents the axis angle deviation, and the vertical axis represents the signal amplitude [%]. The graph shows the result G1 of Example 1 and the result G2 of Comparative Example 1.

[0044] In Example 1, the tight contact between the sensing surface and the skin was ensured, and the fluctuation range of the actually measured pulse wave signal was within 2.1%. On the other hand, in Comparative Example 1 (measurement without a swing mechanism and using a fixed head), the measured signal strength dropped significantly when the wrist rotation angle was changed from zero (0) to 15 degrees. Specifically, in Comparative Example 1, the contact between the sensing surface and the skin was not secured, and a decrease in pulse wave strength of up to 50% was observed.

[0045] The situation of the first embodiment will be described with reference to FIGS. 7 and 8, the pulse wave sensor tip 66 is shown in a simplified form. FIG. 7 is a diagram showing an initial state before the tip portion 66 of the pulse wave sensor according to the first embodiment comes into contact with the skin 111. As shown in FIG. FIG. 8 is a diagram showing a state after the distal end portion 66 of the pulse wave sensor according to the first embodiment has been brought into close contact with the skin 111. As shown in FIG. 7 and 8 show an XYZ Cartesian coordinate system similar to that shown in FIG. 2 for the sake of convenience of explanation.

[0046] As experimental conditions, in Example 1, a silicone rubber diaphragm with a diameter of 10 mm, a thickness of 0.3 mm, and a hardness of 30 degrees was used as the diaphragm of the pulse wave sensor, and the step between the frame and the silicone rubber was set to 0 mm. In Example 1, the pulse wave sensor tip 66 was placed directly above the radial artery 112, and a human pulse wave was measured under the condition that a pressure of 200 g (pressure in direction P1) was applied. The pulse wave measurement time was approximately 20 seconds, and the average value of five measurement results was taken.

[0047] As shown in FIG. 7, in the initial state before pulse wave sensor tip 66 comes into contact with skin 111, the surface of skin 111 is inclined at angle B1 with respect to surface A1, which is the surface of the diaphragm of the pulse wave sensor. As shown in Figure 8, after the pulse wave sensor tip 66 has come into close contact with the skin 111, the oscillating portion 61 is tilted by an angle B2, so that the surface A1 of the diaphragm of the pulse wave sensor comes into close contact with the surface of the skin 111.

[0048] Thus, in Example 1, pulse wave sensor tip 66 is mounted on oscillating unit 61, which allows pulse wave sensor tip 66 to rotate freely up to 15 degrees. As a result, when oscillating unit 61 rotates under load, the fulcrum of the rotation of oscillating unit 61 moves horizontally and stops at a position where balance can be achieved naturally. 5 shows the results of measurements taken when the initial angle (angle B1) at which pulse wave sensor tip 66 contacts the surface of skin 111 is 0 degrees, 1 degree, 3 degrees, 6 degrees, 9 degrees, 12 degrees, and 15 degrees. The results shown in Table T1 are the average of the five measurements taken five times, each measuring the pulse wave for 20 seconds after applying a pressure of 200 g to oscillating section 61.

[0049] The situation in Comparative Example 1 will be described with reference to FIG. FIG. 9 is a diagram showing a state in which the tip portion 2011 of the pulse wave sensor according to Comparative Example 1 is in contact with the skin 111a. In FIG. 9, the pulse wave sensor tip 2011 is shown in a simplified form. For convenience of explanation, FIG. 9 shows an XYZ Cartesian coordinate system similar to that shown in FIGS.

[0050] In Comparative Example 1, the pulse wave of a human was measured by placing the pulse wave sensor tip 2011 directly above the radial artery 112a and applying a pressure of 200 g. The pulse wave measurement time was about 20 seconds, and the average value of five measurement results was taken. As shown in FIG. 9, in Comparative Example 1, when pulse wave sensor tip portion 2011 is in contact with skin 111a, the surface of skin 111a is inclined at angle B11 with respect to surface A11, which is the surface of the diaphragm of the pulse wave sensor.

[0051] In Comparative Example 1, the oscillation mechanism was not used, and measurements were taken with the pulse wave sensor tip 2011 fixed to the sensing head. 5 shows the results of measurements taken when the initial angle (angle B11) at which pulse wave sensor tip 2011 contacts the surface of skin 111a is 0 degrees, 5 degrees, 10 degrees, and 15 degrees. The results shown in Table T1 are the average of the five measurements taken five times, with a pressure of 200 g applied to the head and the pulse wave measured for 20 seconds.

[0052] As described above, the angle error that can be visually observed is approximately 10 degrees, but in Example 1, by using the oscillating unit 61, the axis of the internal air pressure sensor 82 can always be kept perpendicular to the skin surface, and adhesion between the surface of the diaphragm of the internal air pressure sensor 82 and the skin surface can be maintained. As a result, in Example 1, the measurement is less susceptible to the influence of wrist rotation, and even if the wrist rotates within 15 degrees (solid angle 0.2), the influence (fluctuation range) on the measured pulse wave signal can be reduced (for example, to within 3%).

[0053] <Head structure with steps (Example 2)> The head structure having a step will be described with reference to FIGS. In the second embodiment, in order to prevent the influence of the pressure F(t) on the pulse wave signal S(t), measurements are performed with the frame and diaphragm in fixed vertical positions. In Example 2, the step between the frame and the diaphragm was set to 0 to 0.2 mm so that the diaphragm would not be exposed from the frame.

[0054] In Example 2, when the step was set to -0.1 mm, the change in internal pressure of the sealed space {P2(t)-P1(t)} was only within 10 Pa even when a load of 0 to 350 g was applied. The variation in the measurement signal due to the pressing force was evaluated by noise / full span. In the case of Example 2, the variation was low at about 0.2%.

[0055] On the other hand, if the step is 0.3 mm or more, the measurement sensitivity will be degraded. In Comparative Example 2, measurements were taken with the diaphragm protruding 0.2 mm from the frame of the sensing head (frame of the attachment). In this case, when a load of 300 g was applied, the internal pressure rose by about 2400 P. In Comparative Example 2, although it depends on the magnitude of the pressure, when 350 g was applied, the variation in the measurement signal was large, about 41%.

[0056] FIG. 10 is a diagram showing a table T2 showing the evaluation results of the step influence according to Example 2 and Comparative Example 2. In FIG. Table T2 shows the relationship between the pressure (g) and the evaluation results of the variation (%) for each of Example 2 and Comparative Example 2.

[0057] Fig. 11 is a diagram showing the influence of noise due to pressure in Example 2 and Comparative Example 2. In the graph shown in Fig. 11, the horizontal axis represents pressure (g) and the vertical axis represents variation (%). The graph shows the results G11 of Example 2 and G12 of Comparative Example 2.

[0058] Here, as the experimental conditions, in Example 2 and Comparative Example 2, a silicone rubber diaphragm with a diameter of 8 mm, a thickness of 0.3 mm and a hardness of 30 degrees was used. The diaphragm of the pulse wave sensor to be evaluated was then placed on a flat metal surface, and a blank pressing experiment was conducted. Specifically, a pressure of 0 to 350 g was applied to the back surface of the tip of the pulse wave sensor to be evaluated, and signal changes resulting from pulse wave measurement were obtained. In Example 2 and Comparative Example 2, the measurement results of two types of samples with different levels between the frame and the silicone rubber were compared.

[0059] FIG. 12 is a cross-sectional view showing an example of a head structure having a step according to the second embodiment. For convenience of explanation, FIG. 12 shows an XYZ Cartesian coordinate system similar to that shown in FIG. In the second embodiment, the end surface A21 of the silicone rubber 211 is disposed above the end surface A22 of the frame 62 in the vertical direction. In the second embodiment, the distance between the end face A22 of the frame 62 and the end face A21 of the silicone rubber 211 is 0.1 mm. In the second embodiment, pressures are applied to the frame 62 in downward and upward directions P11 and P12. In this way, in Example 2, the step between the end face A22 of the frame 62 and the end face A21 of the silicone rubber 211 was set to −0.1 mm so that the silicone rubber surface (end face A21) of the diaphragm would not be exposed from the frame 62. In Example 2, even when a load of 0 to 350 g was applied, the change in internal pressure of the sealed space {P2(t) - P1(t)} was only within 10 Pa. As a result, in Example 2, the measurement error was kept within 0.2%.

[0060] FIG. 13 is a cross-sectional view showing an example of a head structure according to Comparative Example 2 that does not have the required step. For convenience of explanation, FIG. 13 shows an XYZ orthogonal coordinate system similar to that shown in FIG. In Comparative Example 2, the end face A32 of the silicone rubber 2032 is disposed below the end face A31 of the frame 2031 in the vertical direction. In Comparative Example 2, the distance between the end face A31 of the frame 2031 and the end face A32 of the silicone rubber 2032 is 0.2 mm. In Comparative Example 2, pressure is applied to the silicone rubber 2032 from bottom to top in directions P21 to P24. In this way, in Comparative Example 2, the silicone rubber surface (end surface A32) of the diaphragm was exposed from frame 2031, and the step between frame 2031 and the diaphragm was set to +0.2 mm. In Comparative Example 2, when a load of 350 g was applied, an increase in internal pressure of approximately 2400 P occurred, resulting in a maximum variation of 41%.

[0061] As described above, in the second embodiment, the external load is received by the frame 62, so that the diaphragm does not deform and it is possible to prevent the generation of false signals in the pulse wave signal due to changes in the internal pressure of the air chamber.

[0062] <Diaphragm Rigidity Center (Example 3)> The rigid center of the diaphragm will be described with reference to FIGS. In Example 3, the center of the diaphragm was made harder than the periphery to reduce variations due to deviations in the measurement center position. This allowed the top and bottom of the center of the diaphragm to be precisely aligned during sensing. In Example 3, a 5 mm diameter, 0.2 mm thick stainless steel plate was attached to the silicone rubber at the center of the diaphragm. The peripheral portion of the diaphragm was made of silicone rubber with a hardness of 30 degrees and a thickness of 0.3 mm.

[0063] In Example 3, a load was applied to the center of the diaphragm using a 0.5 mm diameter push rod. Even when the position of the load was shifted ±2 mm from the center of the diaphragm, the rate of change in the intensity of the pulse wave signal was controlled to within ±1%. According to the ISO standard, for example, the diameter of the center (SUS plate) should be Φ4 or more and Φ10 or less.

[0064] On the other hand, in Comparative Example 3, the same measurements as in Example 3 were carried out in a state where only the SUS plate in the center of the diaphragm was removed compared to Example 3. In Comparative Example 3, the center of the diaphragm was too soft, making it easier for the center to detect pulsation signals, and the intensity of the pulse wave signal decreased by up to 20% due to eccentricity.

[0065] FIG. 14 is a diagram showing a table T3 showing the evaluation results of the rigidity center portions according to Example 3 and Comparative Example 3. As shown in FIG. Table T3 shows the relationship between the positional deviation (mm) of the center of the diaphragm and the change in strength for each of Example 3 and Comparative Example 3.

[0066] FIG. 15 is a diagram showing the relationship between the positional deviation and the change in intensity according to Example 3 and Comparative Example 3. In FIG. In the graph shown in FIG. 15, the horizontal axis represents the positional deviation (mm) and the vertical axis represents the intensity conversion (%). The graph shows the results G21 of Example 3 and G22 of Comparative Example 3.

[0067] Here, as the experimental conditions, in Example 3, the decentering characteristics were evaluated under the conditions (7.16) defined in ISO19614. FIG. 16 is a diagram illustrating an example of the manner in which eccentricity is evaluated according to the third embodiment. FIG. 16 shows an evaluation target sensor 231, a push rod 232, a horizontal movement direction C1, and a circle 233. In Example 3, the horizontal movement is ±2 mm, and the pushing amount of the push rod 232 is 300 μm.

[0068] FIG. 17 is a cross-sectional view showing an example of the structure of a diaphragm having a rigid center according to the third embodiment. In FIG. 17, the shape of the tip of the pulse wave sensor is shown in a simplified form. For convenience of explanation, FIG. 17 shows an XYZ Cartesian coordinate system similar to that shown in FIG. In the structure of Example 3, a SUS plate 251 having a thickness of 0.5 mm and a diameter of 5 mm is embedded in the center of the diaphragm in silicone rubber 252 that covers the sides and bottom of air chamber D1 (sealed space). The silicone rubber around the diaphragm has a hardness of 30 degrees and a thickness of 0.3 mm.

[0069] As shown in FIG. 16, in Example 3, a push rod 232 (Φ1 mm) was used to press the push rod 232 to a depth of 300 μm against the center position of the diaphragm of the pulse wave sensor to be measured (sensor 231 to be evaluated). Here, the amount of pushing of the push rod 232 was measured with a meter with an accuracy of 1 μm, and the accuracy of the horizontal movement was set to 0.1 mm. The position of the push rod 232 was changed in 0.5 mm increments from its center position to obtain a signal representing the result of pulse wave measurement. At this time, the signal was measured after the push rod 232 was pressed in and held there for 30 seconds. This was repeated three times to obtain measurement values, and the average value of these three measurement values ​​was recorded. In this way, the eccentricity was evaluated in the X and Y directions from the center position, and the maximum variation measured in both directions was evaluated.

[0070] FIG. 18 is a cross-sectional view showing an example of the structure of a diaphragm having uniform hardness and thickness according to Comparative Example 3. As shown in FIG. In FIG. 18, the shape of the tip of the pulse wave sensor is shown in a simplified form. In Comparative Example 3, only silicone rubber 2051 having a thickness of 0.3 mm and a hardness of 30 degrees was used as a diaphragm for the air chamber D11 (sealed space). Other measurement conditions in Comparative Example 3 were the same as those in Example 3.

[0071] In the third embodiment, the SUS plate 251 is used as the center of the diaphragm, but instead of the SUS plate 251, a plate made of other metals such as aluminum, or a resin may be used. As another example, the center and peripheral portions of the diaphragm may be made of silicone rubber, but the thickness of the silicone rubber in the center may be made greater than the thickness of the silicone rubber in the periphery, making the center harder than the periphery. In this way, it is sufficient that the center of the diaphragm is harder than the surrounding silicone rubber.

[0072] As described above, in Example 3, even if the load application position deviates from the center of the diaphragm by a predetermined amount (e.g., ±2 mm), the rate of change in the intensity of the measured pulse wave signal can be controlled to be small (e.g., within ±1%).

[0073] <Hysteresis (Example 4)> The hysteresis will be described with reference to FIGS. In Example 4, hysteresis was evaluated using silicone rubbers with hardnesses of 30 degrees, 40 degrees, and 50 degrees and thicknesses of 0.3 mm, 0.4 mm, and 0.5 mm. As a result, the softer and thinner the silicone rubber, the better the hysteresis. For example, when the silicone rubber has a hardness of 30 degrees and a thickness of around 0.3 mm, it meets the 1% hysteresis standard specified by ISO. Operation was also confirmed when the silicone rubber was 100 μm thick, but if it was too thin, air could penetrate the diaphragm. The material of the squeezable peripheral portion of the diaphragm is a soft material that is difficult for gas to permeate, such as silicone rubber or fluororesin.

[0074] FIG. 19 is a diagram showing a table T4 representing the evaluation results of the hysteresis according to the fourth embodiment. Table T4 shows the evaluation results (%) of hysteresis for each combination of silicone rubber hardness and thickness. FIG. 20 is a diagram showing the evaluation results of hysteresis according to Example 4. As shown in FIG. FIG. 20 shows three-dimensionally the hysteresis of a plurality of patterns E1 to E9 for the combinations of hardness and thickness shown in FIG.

[0075] FIG. 21 is a diagram for explaining a method for evaluating hysteresis according to the fourth embodiment. As the experimental conditions, in Example 4, hysteresis was evaluated under the conditions (7.10) defined in ISO19614. A periodic vibration was generated using a standard machine. The diaphragm was pushed in by 300 μm. 21, oscillator 312, which vibrates in a predetermined direction C11, was brought into contact with sensor 311 (diaphragm) to be evaluated, so that vibrations generated by the reference device were transmitted to the diaphragm of the pulse wave sensor to be evaluated. Then, when subjected to vibrations of the same amplitude, the difference between the average value of three measurements when the amplitude increased and the average value of three measurements when the amplitude decreased was measured. Figure 21 shows an example of signal 1011 when the amplitude increased (going 1021) and an example of signal 1011 when the amplitude decreased (return 1022).

[0076] In Example 4, the hysteresis was determined as the maximum value / full span of the difference between the amplitude increase and the amplitude decrease evaluated within the entire range. A silicone rubber diaphragm (Φ10) was used in this evaluation. The hardness of the silicone rubber is the evaluation value (unitless) of a durometer (Type A, standard JIS K 6301). The standard for rubber hardness is defined in the international standard, International Rubber Hardness Degree (IRHD). The experimental conditions were the same except for the thickness and hardness of the silicone rubber.

[0077] As described above, in Example 4, it is possible to reduce the linearity and hysteresis (for example, to within 1%) by adjusting the hardness and thickness of the silicone rubber.

[0078] <Temperature Control (Example 5)> The temperature control will be described with reference to FIGS. The temperature T2(t) of the sealed sensing space depends on the body temperature of the subject and the room temperature. In most cases, the arm surface temperature is approximately 34 to 40°C, and the room temperature is 10 to 30°C. Because there is a difference between the body surface temperature and the room temperature, when the diaphragm is attached to the skin, the temperature of the sealed space is likely to rise by several to 20 degrees Celsius.

[0079] In Example 5, to eliminate the effect of such a temperature rise in the sealed space, a heater was used to heat the sealed space to a temperature close to body temperature, thereby ensuring that the difference ΔT between the temperature of the pulse wave sensor (temperature T2 in this embodiment) and the body surface temperature was less than 0.5°C. In Example 5, under temperature control, a fluctuation range Δp of the measured pulse wave signal was ensured to be less than 60 Pa. An error in the pulse wave signal of 1% was ensured.

[0080] In Comparative Example 5, the above-described heating and temperature control were not performed. At this time, the temperature of the pulse wave sensor (temperature T2 in this embodiment) rose from room temperature to body surface temperature by approximately 15°C. This caused a variation of approximately 10% in the pulse wave signal. For example, when the room temperature is 10°C and the pulse wave signal of a patient with a body temperature of 40°C is measured, it is estimated that the variation in the pulse wave signal may increase to approximately 20%.

[0081] As the experimental conditions, in Example 5, a silicone rubber diaphragm with a diameter of 8 mm, a thickness of 0.3 mm and a hardness of 30 degrees was used. Three heaters were attached to the outside of the aluminum cell that constituted the sealed space. The target heating temperature was set to 34°C, which was the actual body surface temperature of the test subject. The tip of the pulse wave sensor was attached to the surface of the arm where there was no pulsation, avoiding the location of the radial artery. A pressure of 200g was then applied to the tip of the pulse wave sensor.

[0082] FIG. 22 is a diagram showing a table T5 representing the evaluation results of the temperature control according to the fifth example and the fifth comparative example. Table T5 shows the temperature fluctuation range, internal pressure fluctuation range, and pulse wave signal variation for Example 5 (with heating) and Comparative Example 5 (without heating).

[0083] FIG. 23 is a diagram showing the fluctuations in temperature and internal pressure inside the sealed space measured when the temperature of the sealed space according to Example 5 is controlled to a body surface temperature of 34°C. In the graph shown in Figure 23, the horizontal axis represents time (sec), the left vertical axis represents temperature (T2), and the right vertical axis represents internal pressure (differential pressure P2-P1). Figure 23 shows the temperature measurement result G31 and the pressure (differential pressure) measurement result G32.

[0084] FIG. 24 is a diagram showing fluctuations in temperature and internal pressure inside the sealed space in Comparative Example 5 when the body surface temperature is 34° C. and the sealed space is not heated or temperature controlled. The horizontal axis shown in FIG. 24 represents time (sec), the vertical axis on the left represents internal pressure (ΔP, which is the differential pressure), and the vertical axis on the right represents temperature. FIG. 24 shows a heater-off period Q1 and a heater-on period Q2. FIG. 24 also shows the results of pressure (differential pressure) measurement G41 and the results of temperature measurement G42.

[0085] As described above, in Example 5, the temperature of the sensing head 11 can be stabilized at a temperature close to the body surface temperature (for example, stabilized to a difference of about plus or minus 0.5 degrees), and therefore, even when there is a difference between the ambient temperature and the body surface temperature, the influence (fluctuation range) on the measured pulse wave signal can be reduced (for example, within 10 Pa).

[0086] <Frame cut (Example 6)> The cut edges of the frame will be described with reference to FIGS. FIG. 25 is a diagram showing the configuration of a frame 331 having cutouts 351 to 354 according to the sixth embodiment. For convenience of explanation, FIG. 25 shows an XYZ Cartesian coordinate system similar to that shown in FIG.

[0087] In FIG. 25, the frame 331 and the membrane 332 of the diaphragm are shown. In the example of FIG. 25, a case is shown in which a frame having a circular surface (a surface parallel to the XY plane) is used as the frame 331. The frame 331 has four cutouts 351 to 354 on the circular surface. These four cutouts 351 to 354 are provided at equal angular intervals of 90 degrees on the circular surface.

[0088] In the sixth embodiment, the frame 331 of the sensing head 11 is provided with four cuts 351 to 354 of 0.3 mm each. This allows the surface of the diaphragm to be constantly in communication with the atmosphere, so that when the diaphragm is attached to the skin, gas does not accumulate between the diaphragm and the skin, and when atmospheric pressure fluctuates momentarily, the amount of the air pressure fluctuation can be correctly removed from the differential pressure {P2(t)-P1(t)}.

[0089] In Example 6, an air flow was created in the measurement environment by opening and closing a window in a negative indoor pressure environment, resulting in a momentary atmospheric pressure fluctuation of up to approximately 80 Pa. At this time, the fluctuation range of the measured pressure difference {P2(t) - P1(t)} was ±5 Pa, and the atmospheric pressure fluctuation was appropriately canceled. To ensure such an effect, the size of the cuts 351 to 354 is set to 0.1 mm or more. In the example of FIG. 25, four cuts 351 to 354 are provided, but it is sufficient that at least one cut is provided in the frame 331.

[0090] On the other hand, as Comparative Example 6, measurements were made using a frame with no cuts. In Comparative Example 6, with the surface of the diaphragm in close contact with the skin, air was caused to flow in the measurement environment by opening and closing a window in a negative pressure room, resulting in an instantaneous atmospheric pressure fluctuation of up to approximately 80 Pa. In Comparative Example 6, there were some irregularities such as grooves on the surface of the skin, and communication between the diaphragm and the atmosphere was not completely ensured, resulting in a false signal being generated in {P2(t)-P1(t)}. In Comparative Example 6, although it depends on the severity of the sudden change in atmospheric pressure, cases were observed in which a false signal of up to 50 Pa occurred in {P2(t)-P1(t)}. The effect of canceling atmospheric pressure fluctuations when there are cuts in the frame is more than 10 times greater than when there are no cuts in the frame.

[0091] Here, as the experimental conditions, in Example 6 and Comparative Example 6, a silicone rubber diaphragm with a diameter of 8 mm, a thickness of 0.3 mm and a hardness of 30 degrees was used. In Example 6 and Comparative Example 6, three heaters were attached to the outside of the aluminum cell that constituted the sealed space, and the target heating temperature was set to 34°C to match the actual body surface temperature (34°C) of the test subject. In Example 6 and Comparative Example 6, the diaphragm of the pulse wave sensor was attached to a part of the arm surface where there was no pulsation, avoiding the position of the radial artery. In Example 6 and Comparative Example 6, the zero point correction of the two pressure sensors (the atmospheric pressure sensor 81 and the internal pressure sensor 82 shown in FIG. 2) has already been performed. In Example 6 and Comparative Example 6, the ambient air pressure of the indoor negative pressure was 99250 Pa to 99390 Pa. In Example 6 and Comparative Example 6, a pressure of 200 g was applied to the tip of the pulse wave sensor.

[0092] Figure 26 is a diagram showing the atmospheric pressure fluctuation cancellation effect of a frame with a cutout according to Example 6. In the graph shown in Figure 26, the horizontal axis represents time (sec), the left vertical axis represents pressure (P1, P2), and the right vertical axis represents the pressure difference (P2 - P1). Figure 26 shows the result of measuring the internal pressure G51, the result of measuring the atmospheric pressure G52, and the result G53 of subtracting the atmospheric pressure from the internal pressure.

[0093] FIG. 27 is a diagram showing the atmospheric pressure fluctuation canceling effect of a frame having no cut edge according to Comparative Example 6. In FIG. In the graph shown in Figure 27, the horizontal axis represents time (sec), the left vertical axis represents pressure (P1, P2), and the right vertical axis represents the pressure difference (P2 - P1). Figure 27 shows the result of measuring atmospheric pressure G61, the result of measuring internal pressure G62, and the result of subtracting atmospheric pressure from internal pressure G63.

[0094] As described above, in the sixth embodiment, atmospheric pressure fluctuation ΔP, which is noise caused by momentary changes in airflow, can be correctly canceled from the pressure difference (P2-P1) between atmospheric pressure sensor 81 and internal pressure sensor 82. For example, even if the atmospheric pressure fluctuation during measurement is several tens of Pa, the effect (fluctuation range) on the measured pulse wave signal can be made small (for example, within 10 Pa). In this way, in the sixth embodiment, erroneous detection of the pulse wave signal can be prevented.

[0095] <Laser pointer (Example 7)> The laser pointer will be described with reference to FIGS. FIG. 28 is a diagram showing an example of the installation of two laser pointers (a first laser pointer 421 and a second laser pointer 422) according to the seventh embodiment. For convenience of explanation, FIG. 28 shows an XYZ Cartesian coordinate system similar to that shown in FIG.

[0096] The first laser pointer 421 and the second laser pointer 422 are included in the laser pointer unit 54 shown in FIG. 28, pulse wave sensor housing 411 (head housing 51 in the example of FIG. 2) has a circular surface, and the center of the circle is intended measurement position 412. First laser pointer 421 and second laser pointer 422 are placed at positions near the circumference that are rotated 90 degrees from the center of the circle.

[0097] Fig. 29 is a diagram showing an example of a cross mark of a laser pointer according to Example 7. For convenience of explanation, Fig. 29 shows an XYZ Cartesian coordinate system similar to that shown in Fig. 2. In the example of FIG. 29, a cross mark of a laser pointer is formed on the cradle portion 431. A first laser beam 451 from the first laser pointer 421 around the pulse wave sensor housing 411 and a second laser beam 452 from the second laser pointer 422 around the pulse wave sensor housing 411 form a cross mark on the cradle 431. The intersection 453 of the cross marks is the measurement target position (planned measurement position). In other words, the two linear laser beams emitted from the two laser pointers form a cross mark indicating the target location for detecting the pulse wave.

[0098] In this way, in the seventh embodiment, a cross mark is formed around the periphery of the pulse wave sensor housing 411 using two linear laser pointers. These two lines, for example, intersect at right angles. For example, the focal shape is a line with a width of 1 mm or less. To ensure the safety of the living body, the laser power is set to 1 mW or less. The subject's arm was placed on the support 431, and the position of the strongest pulsation was confirmed with a finger.

[0099] For example, before measuring the pulse wave, the intended contact position of the tip of the pulse wave sensor is indicated with a cross mark on the laser pointer, and this allows fine adjustment of the position of the tip of the pulse wave sensor or cradle 431. Then, when the tip of the pulse wave sensor is lowered onto the skin, the position of the strongest pulse can be secured, improving the efficiency of measurement. The configuration of the cradle portion 431 is not limited to the example shown in FIG.

[0100] As described above, in the seventh embodiment, the measurement position can be clearly displayed before the tip of the pulse wave sensor comes into contact with the skin, and deviation of the measurement position can be prevented.

[0101] <Correction of the initial atmospheric pressure value (Example 8)> Correction of the initial atmospheric pressure value will be described with reference to FIGS. The local pressure P1(t) depends heavily on the altitude of the measurement site. For example, the pressure at an altitude of 4000 m is about 40% lower than the pressure at sea level. In addition, sea levels rise and fall depending on the season and time of day, and atmospheric pressure is constantly changing. For example, the fluctuation range of atmospheric pressure over a 24-hour period is approximately 300 Pa.

[0102] In pulse diagnosis, the strength of the measured waveform is compared, and a weak pulse wave is classified as a weak pulse, and a strong pulse wave is classified as a strong pulse. In the eighth embodiment, a correction formula (calculation formula S1(t)) is used to convert the output of the measurement signal (pulse wave signal) into a standard pressure of 101325 Pa in order to ensure the same measurement output at any location and any time.

[0103] S1(t)={P2(t)-P1(t)}× K K=Po / P1(0) Po=101325Pa (atmospheric pressure reference value)

[0104] This means that the output pulse wave signal does not depend on the initial atmospheric pressure at the time of measurement, meaning that the same measurement results can be obtained at any location and at any time.

[0105] On the other hand, when the initial atmospheric pressure was not corrected, evaluations were performed at different altitudes (initial atmospheric pressures). Pulse wave intensity decreased by up to 40%. For example, when the initial pressure is lower than 1 atmosphere and becomes 0.64 atmospheres (altitude 4000M), ΔP decreases by approximately 2600 Pa for the same ΔZ = 300 μm.

[0106] FIG. 30 is a diagram showing a table T6 representing the correction effect of the initial atmospheric pressure value according to Example 8 and Comparative Example 8. In FIG. Table T6 shows the relationship between the displacement ΔZ and the signal intensity (%) for Example 8, in which the initial atmospheric pressure value is corrected, and two Comparative Examples 8, in which the initial atmospheric pressure value is not corrected. Here, in Example 8, Po=0.6 to 1.1 atmospheres. In one of the two Comparative Examples 8, Po=0.6 atmospheres, and in the other, Po=0.8 atmospheres.

[0107] Fig. 31 is a diagram showing the correction effect of the initial atmospheric pressure value according to Example 8 and Comparative Example 8. In the graph shown in Fig. 31, the horizontal axis represents the displacement ΔZ, and the vertical axis represents the signal intensity (%). Figure 31 shows measurement results G71 for Example 8, measurement results G72 for one side of Comparative Example 8 (Po = 0.6 atmospheres), and measurement results G73 for the other side of Comparative Example 8 (Po = 0.8 atmospheres).

[0108] As described above, in Example 8, regardless of the altitude or time of the measurement area, signals of the same pulse wave intensity can be correctly measured for the same pulsation when the atmospheric pressure at the start of measurement is within a predetermined range (for example, within a range of 0.6 to 1.1 atmospheres). In the eighth embodiment, the amplitude of the pulse wave signal can be guaranteed to be correct by correcting the initial value of atmospheric pressure.

[0109] <Zero Point Correction of Barometric Pressure Sensor (Example 9)> Referring to FIG. 32, the zero point correction of the atmospheric pressure sensor will be described. There may be initial variations among different sensors due to manufacturing variations. The same electronic circuitry was implemented as 16 MEMS sensors on different flexible substrates and tested. The absolute value of the pressure output from the MEMS pressure sensor ICP-10100 has a variation of approximately ±100 Pa. Variations in capacitors and resistors and circuit mounting accuracy further increase lot-to-lot variations.

[0110] 32 is a diagram showing Table T7 showing the correction effect of the zero point correction according to Example 9. Table T7 shows the variation in the measurement results of the air pressure sensor for the numbers (sample numbers) of 16 flexible substrate samples, both with and without the zero point correction according to Example 9 (Comparative Example 9). The results of measuring atmospheric pressure showed a maximum difference of ±500 Pa. By using the zero point correction formula (calculation formula ΔP(0)), the variation was reduced to ±2 Pa.

[0111] ΔP(0)={P2(0)-P1(0)}

[0112] When zero point correction was performed as in Example 9, the zero point deviation could be eliminated from the pulse wave signal even if there was variation in the manufacturing lot. On the other hand, when no zero point correction was performed, as in Comparative Example 9, the pulse wave signal S0(t)={P2(t)-P1(t)}, with a maximum variation of ±8.5%.

[0113] The experimental conditions used here were a silicone rubber diaphragm with a diameter of 8 mm, a thickness of 0.3 mm, and a hardness of 30 degrees. The same MEMS pressure sensor, ICP-10100, was also used and implemented using the same electronic circuit. The atmospheric pressure in the same environment was measured within 30 minutes using 16 pressure sensors. The ambient pressure measured by the reference pressure sensor during the 30-minute period was 101512±2 Pa.

[0114] As described above, in Example 9, the difference in initial output between the adopted atmospheric pressure sensor 81 and the internal air pressure sensor 82 (which is variation between manufacturing lots, and in the example results of a specified evaluation, is up to ±500 Pa) can be eliminated, and a more accurate pulse wave signal can be detected.

[0115] <Temperature Fluctuation Correction (Example 10)> Temperature fluctuation correction will be described with reference to FIG. Because body surface temperature varies from person to person, there can be a difference of up to approximately 2°C between the heater's set temperature and the actual body surface temperature. Furthermore, even during temperature control, there is a temperature fluctuation of approximately 0.5°C.

[0116] Using the temperature fluctuation correction formula (calculation formula ΔP(T2)), the variation due to temperature fluctuation can be reduced.

[0117] ΔP(T2)={T2(t)-T2(0)} / T2(0)×P2(0)×C

[0118] The pulse wave signal S4(t) after temperature fluctuation correction and zero point correction is obtained by the following equation:

[0119] S4(t)={P2(t)-P1(t)}-ΔP(0)-ΔP(T2)

[0120] As in Example 10, the influence of air expansion in the sealed space can be accurately compensated for by temperature fluctuation correction. Even with a temperature fluctuation of 2°C, the change in internal pressure was kept within 20 Pa, and the variation was kept to 0.3%. As an empirical value, C varies depending on the material, shape, and tension of the diaphragm. Specifically, for a rectangular head, C = 20-25%, and for a circular head, C = 15-20%. If this temperature compensation is not performed, a 2°C temperature difference will result in a false signal of approximately 170 Pa in the internal pressure change. Furthermore, if this temperature compensation is not performed, an error of approximately 3% will occur.

[0121] FIG. 33 is a diagram illustrating the correction effect of the temperature fluctuation correction according to the tenth embodiment. In the graph shown in Fig. 33, the horizontal axis represents time (sec), the left vertical axis represents air pressure (differential pressure ΔP), and the right vertical axis represents temperature (Temp). Fig. 33 shows the result G81 when only zero point correction was performed, the result G82 when both zero point correction and temperature correction were performed, and the result G83 of measuring temperature T2.

[0122] Here, the experimental conditions used were a silicone rubber diaphragm with a diameter of 8 mm, a thickness of 0.3 mm, and a hardness of 30 degrees. In Example 10, the initial atmospheric pressure value correction and the zero point correction of the atmospheric pressure sensor were performed. The test was conducted in a room temperature environment of 23°C. A heater was attached to the outside of the sealed space to control the temperature at 34°C. The temperature rose by approximately 2°C within 30 seconds of starting heating.

[0123] As described above, in Example 10, in the pulse wave detection system 1, even when there are individual differences in body surface temperature or temperature fluctuations during measurement, the internal pressure change ΔP(t) due to temperature changes in the pulse wave detection unit can be eliminated, thereby eliminating noise due to expansion or contraction of the sealed space.

[0124] (Regarding the above embodiments) As described above, the pulse wave detection system 1 according to this embodiment can improve the accuracy of data used in pulse diagnosis. In the pulse wave detection system 1 according to this embodiment, for example, variations in pulse wave signals due to changes in disturbance factors can be significantly reduced. Therefore, the pulse wave detection system 1 according to this embodiment can measure, for example, a pulse waveform with minimal distortion and accurate pulse wave intensity. Furthermore, the pulse wave detection system 1 according to this embodiment can acquire a pulse wave signal that has been dynamically corrected in a predetermined manner.

[0125] A program for implementing the functions of any of the components (e.g., the calculation unit 55) in any of the above-described devices may be recorded on a computer-readable recording medium and loaded into a computer system for execution. The term "computer system" as used herein includes hardware such as an operating system or peripheral devices. The term "computer-readable recording medium" also refers to portable media such as flexible disks, optical magnetic disks, ROMs, and compact discs (CDs) or read-only memories (ROMs), as well as storage devices such as hard disks built into computer systems. The term "computer-readable recording medium" also includes devices that retain a program for a certain period of time, such as volatile memory within a computer system that acts as a server or client when a program is transmitted over a network such as the Internet or a communication line such as a telephone line. Such volatile memory may be, for example, random access memory (RAM). The recording medium may also be, for example, a non-transitory recording medium.

[0126] The above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by transmission waves in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. The above program may also be one that realizes part of the above-mentioned functions. Furthermore, the above program may be a so-called differential file that can realize the above-mentioned functions in combination with a program already recorded in a computer system. A differential file may also be called a differential program.

[0127] Furthermore, the functions of any of the components (e.g., the calculation unit 55) in any of the above-described devices may be implemented by a processor. For example, each process in the embodiments may be implemented by a processor that operates based on information such as a program and a computer-readable recording medium that stores information such as the program. Here, the functions of each unit of the processor may be implemented by, for example, individual hardware, or may be implemented by integrated hardware. For example, the processor may include hardware, and the hardware may include at least one of a circuit for processing digital signals and a circuit for processing analog signals. For example, the processor may be configured using one or more circuit devices mounted on a circuit board, or one or both of one or more circuit elements. An integrated circuit (IC) or the like may be used as the circuit device, and a resistor or a capacitor may be used as the circuit element.

[0128] Here, the processor may be, for example, a CPU. However, the processor is not limited to a CPU, and various types of processors such as a GPU (Graphics Processing Unit) or a DSP (Digital Signal Processor) may be used. The processor may also be, for example, a hardware circuit such as an ASIC (Application Specific Integrated Circuit). The processor may also be, for example, composed of multiple CPUs, or may be, for example, composed of a hardware circuit such as a multiple ASIC. The processor may also be, for example, composed of a combination of multiple CPUs and a hardware circuit such as a multiple ASIC. The processor may also include, for example, one or more of an amplifier circuit or a filter circuit that processes analog signals.

[0129] The embodiments of this disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs within the scope that do not deviate from the gist of this disclosure. In the above embodiment, a number of characteristic configuration examples have been shown for the pulse wave detection system 1, but these characteristic configuration examples may, for example, all be combined and applied, or each characteristic configuration example may be applied alone, or any two or more characteristic configuration examples may be combined and applied.

[0130] [Note] Below, (Configuration Example 1) to (Configuration Example 12) are shown. The following (Configuration Example 1) to (Configuration Example 12) are merely examples, and other configurations may also be used.

[0131] (Configuration example 1) a detection unit that is brought into contact with the arm that is the subject of pulse wave detection; a swinging unit provided with the detection unit and capable of swinging the detection unit; a calculation unit that acquires a pulse wave signal based on the signal detected by the detection unit; 、 the detection unit includes a diaphragm and a frame; The diaphragm is not exposed from the frame, The step between the diaphragm and the frame is 0 to 0.2 mm. Pulse wave detection system.

[0132] (Configuration example 2) The oscillating unit has a spherical rotor and can rotate within a solid angle of 0.2. The pulse wave detection system according to (Configuration Example 1).

[0134] (Configuration example 3 ) The center of the diaphragm is harder than the peripheral portion of the diaphragm. (Configuration example 1 ) Or (Configuration Example 2) The pulse wave detection system according to claim 1.

[0135] (Configuration example 4 ) The peripheral portion of the diaphragm is made of a flexible resin, has a hardness of 20 to 50 degrees, and has a thickness of 0.1 to 0.5 mm. (Configuration example 3 ) A pulse wave detection system according to the present invention.

[0136] (Configuration example 5 ) The frame has one or more cuts. (Configuration example 1 ) to (Configuration Example 4) t The pulse wave detection system according to claim 1.

[0138] (Configuration example 6 ) Let t be the time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space, The calculation unit For the pulse wave signal {P2(t)-P1(t)} The correction formula for correcting the initial value P1(0) of the atmospheric pressure to the reference value Po=101325 Pa is: {P2(t)-P1(t)}×Po / P1(0) Performing operations using Corrects variations in pulse wave signals due to pressure differences , (Configuration Example 1) to (Configuration Example 5 ) A pulse wave detection system according to any one of the above.

[0139] (Configuration example 7 ) Let t be the time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space, The calculation unit For the pulse wave signal {P2(t)-P1(t)} The zero point correction of the atmospheric pressure sensor and the internal air pressure sensor is carried out by using a correction calculation formula that eliminates the initial difference ΔP(0) between the outputs of the atmospheric pressure sensor and the internal air pressure sensor, as follows: ΔP(0)=P2(0)-P1(0) {P2(t)-P1(t)}-ΔP(0) Performing operations using Corrects variations in pulse wave signals due to pressure differences , (Configuration example 1 ) from (Configuration example 6 ) One of The pulse wave detection system according to claim 1.

[0140] (Configuration example 8 ) Let t be the time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space; an internal temperature sensor that measures the internal temperature T2(t) of the sealed space; The calculation unit For the pulse wave signal {P2(t)-P1(t)} A correction calculation formula for eliminating the temperature fluctuation, which is the internal pressure change ΔP(T2) due to the temperature change of the internal temperature sensor, is given by: ΔP(T2)={T2(t)-T2(0)} / T2(0)×P2(0)×C {P2(t)-P1(t)}-ΔP(T2) Performing operations using Corrects variations in pulse wave signals due to temperature differences , (Configuration example 1 ) to (Configuration example 7 ) A pulse wave detection system according to any one of the above.

[0141] (Configuration example 9 ) The detection unit is provided with an analog temperature control unit, The analog temperature control unit has a heater and a temperature control unit that controls the temperature by controlling on / off of the heater. (Configuration Example 1) to (Configuration Example 8 ) A pulse wave detection system according to any one of the above.

[0142] (Configuration example 10 ) Two laser pointers are provided which emit two linear laser beams that form cross marks indicating the target locations for detecting pulse waves. (Configuration Example 1) to (Configuration Example 9 ) A pulse wave detection system according to any one of the above. [Explanation of symbols]

[0143] 1...pulse wave detection system, 11...sensing head, 12...casing, 13...positioner, 13a...first member, 13b...second member, 21...arm, 51...head housing, 52...cavity, 53...support, 54...laser pointer, 61...oscillating portion, 61a...rotor (spherical rotor), 61b...shaft, 61c...central axis, 62, 331...frame, 63...diaphragm, 66...pulse wave sensor tip, 71...analog temperature control unit, 81...atmospheric pressure sensor, 82...internal air pressure sensor, 83...internal temperature sensor, 111...skin, 112...radial artery, 211, 252...Silicone rubber, 231, 311...Sensor to be evaluated, 233...Circle, 251...SUS plate, 312...Vibrator, 332...Membrane, 351 to 354...Cut, 411...Pulse wave sensor housing, 412...Planned measurement position, 421...First laser pointer, 422...Second laser pointer, 431...Receiving base, 451...First laser beam, 452...Second laser beam, A1...Surface, A21, A22...End face, B1, B2...Angle, D1...Air chamber, P1, P11, P12, C1, C11...Direction, T1 to T7...Table, W1...Detecting part

Claims

1. a detection unit that is brought into contact with the arm that is the subject of pulse wave detection; a swinging unit provided with the detection unit and capable of swinging the detection unit; a calculation unit that acquires a pulse wave signal based on the signal detected by the detection unit, the detection unit includes a diaphragm and a frame; The diaphragm is not exposed from the frame, The step between the diaphragm and the frame is 0 to 0.2 mm. Pulse wave detection system.

2. The oscillating unit has a spherical rotor and is rotatable within a solid angle range of 0.

2. The pulse wave detection system according to claim 1 .

3. The center of the diaphragm is harder than the peripheral portion of the diaphragm. The pulse wave detection system according to claim 1 or 2.

4. The peripheral portion of the diaphragm is made of a flexible resin, has a hardness of 20 to 50 degrees, and has a thickness of 0.1 to 0.5 mm. The pulse wave detection system according to claim 3 .

5. The frame has one or more cuts. The pulse wave detection system according to claim 1 or 2.

6. Let t be time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space, The calculation unit calculates a correction formula for correcting the initial value P1(0) of the atmospheric pressure to the reference value Po=101325 Pa for the pulse wave signal {P2(t)-P1(t)}, as follows: {P2(t)-P1(t)}×Po / P1(0) and corrects for variations in the pulse wave signal due to pressure differences. The pulse wave detection system according to claim 1 or 2.

7. Let t be time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space, The calculation unit performs zero point correction of the atmospheric pressure sensor and the internal air pressure sensor with respect to the pulse wave signal {P2(t)-P1(t)}, and uses a correction calculation formula that eliminates an initial output difference ΔP(0) between the atmospheric pressure sensor and the internal air pressure sensor, as follows: ΔP(0)=P2(0)-P1(0) {P2(t)-P1(t)}-ΔP(0) and corrects for variations in the pulse wave signal due to pressure differences. The pulse wave detection system according to claim 1 or 2.

8. Let t be time, an atmospheric pressure sensor that measures atmospheric pressure P1(t); an internal air pressure sensor provided in the detection unit for measuring the internal air pressure P2(t) of the sealed space; an internal temperature sensor that measures an internal temperature T2(t) of the sealed space; The calculation unit calculates a correction formula for eliminating temperature fluctuations, which are the internal pressure change ΔP(T2) due to the temperature change of the internal temperature sensor, from the pulse wave signal {P2(t)-P1(t)}, using C as a predetermined coefficient: ΔP(T2)={T2(t)-T2(0)} / T2(0)×P2(0)×C {P2(t)-P1(t)}-ΔP(T2) and correcting the variation in the pulse wave signal due to the temperature difference. The pulse wave detection system according to claim 1 or 2.

9. The detection unit is provided with an analog temperature control unit, The analog temperature control unit has a heater and a temperature control unit that controls the temperature by controlling on / off of the heater. The pulse wave detection system according to claim 1 or 2.

10. Two laser pointers are provided which emit two linear laser beams that form cross marks indicating targets for detecting pulse waves. The pulse wave detection system according to claim 1 or 2.

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