Method for adjusting pulse wave measurement device, pulse wave measurement system, and pulse wave measurement device

Abstract

The present invention is a method for adjusting a pulse wave measurement device which can be worn on a wrist of a user, the pulse wave measurement device comprising: a pulse wave sensor which has a strain gauge and acquires a pulse wave by measuring a pulse of a radial artery; a pressing member that presses the pulse wave sensor toward a radial artery; and an output unit that outputs a measurement value of the pulse wave sensor as a digital signal, the adjustment method comprising the steps of: when the pulse wave measurement device is worn on a wrist of a user, acquiring a pulse wave by the pulse wave sensor and outputting the acquired measurement value as a digital signal; a comparison unit that compares a voltage level of the digital signal with a range preset with respect to a maximum output level of the output unit; and adjusting or instructing a pressing force applied to the pulse wave sensor when the voltage level of the digital signal is outside the preset range.

Description

Technical Field

[0001] The invention relates to an adjustment method of a pulse wave measuring device, a pulse wave measuring system and a pulse wave measuring device. Background Art

[0002] In recent years, it has been known to acquire information on biological signal waves such as pulse waves, including blood flow due to expansion / contraction of blood vessels and reflected waves due to blood vessel resistance, by a vital sensor worn on the wrist.

[0003] However, in such a vital sensor, an error occurs in a signal due to a difference in the pressing force of the sensor against the skin.

[0004] Therefore, Patent Document 1 discloses calculating the difference between the maximum and minimum values ​​of each blood pressure wave of the pulse wave signal, continuously adjusting to increase the pressure of the pulse holding device until the difference no longer increases, and sensing the blood pressure wave according to the most appropriate pressure value.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-6291 Summary of the invention

[0006] [Problems to be Solved by the Invention]

[0007] However, in Patent Document 1, since it is necessary to continue increasing the pressure until the change between the maximum value and the minimum value disappears, the time for pressure adjustment varies, and the time until the main measurement is uncertain, which is time-consuming.

[0008] Therefore, in view of the above situation, an object of the present invention is to provide an adjustment method in a pulse wave measurement device, which can shorten the time required for adjustment and adjust to an appropriate pressing force, thereby reducing the error.

[0009] [Methods used to solve the problem]

[0010] In order to solve the above problem, in one aspect of the present invention, a method for adjusting a pulse wave measurement device is provided, wherein the pulse wave measurement device can be worn on a user's wrist, wherein:

[0011] The pulse wave measuring device comprises:

[0012] a pulse wave sensor having a strain gauge for acquiring a pulse wave by measuring the pulse of the radial artery; a pressing member for pressing the pulse wave sensor toward the radial artery; and

[0013] an output unit that outputs the measurement value of the pulse wave sensor as a digital signal,

[0014] The adjustment method comprises the following steps:

[0015] When the pulse wave measuring device is worn on the wrist of a user, the pulse wave is acquired through the pulse wave sensor, and the acquired measurement value is output as a digital signal;

[0016] comparing the voltage level of the digital signal with a predetermined range relative to the maximum output level of the output unit; and

[0017] When the voltage level of the digital signal is outside the preset range, the pressing force applied to the pulse wave sensor is adjusted or instructed.

[0018] [Effects of the Invention]

[0019] According to one aspect, the adjustment method in the pulse wave measurement device can shorten the time required for adjustment and adjust to an appropriate pressing force, thereby reducing errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an overall diagram of the pulse wave measurement system according to the first embodiment of the present invention.

[0021] Figure 2 This is a side view illustrating the pulse wave measurement device according to the first embodiment.

[0022] Figure 3 yes Figure 1 An exploded view of a pulse wave measurement device included in a pulse wave measurement system.

[0023] Figure 4 This is a control block diagram of the pulse wave measurement system according to the first embodiment.

[0024] Figure 5 This is a diagram showing the average value of the output voltage of the pulse wave when the belt length is changed.

[0025] Figure 6 is a graph showing an example of a measured pulse wave and an accelerated pulse wave calculated from the pulse wave.

[0026] Figure 7 This is a diagram for explaining the inflection point of a general acceleration pulse wave.

[0027] Figure 8 is a graph showing changes in the acceleration pulse wave caused by changes in pressure applied to the pulse wave sensor.

[0028] Fig. 9 This is a diagram for explaining the average value of the output level of the pulse wave.

[0029] Fig.10 1 is a diagram showing the inflection point of the acceleration pulse wave corresponding to the voltage value of the average output level.

[0030] Fig.11 This graph summarizes the signal deviation caused by changes in pressing force within the pulse wave measurement range.

[0031] Fig.12 This is a detailed flow chart of pressure adjustment for pulse wave measurement.

[0032] Fig.13 This is the overall flow chart of pulse wave measurement.

[0033] Fig.14 This is a front view of the pressure detection surface side of the pulse wave sensor included in the pulse wave measurement device.

[0034] Fig.15 yes Fig.14 A cross-sectional view of a pulse wave sensor.

[0035] Fig.16 is an example Fig.14 A top view of a strain gauge included in a pulse wave sensor.

[0036] Fig.17 yes Fig.16 Cross-sectional view of the strain gauge.

[0037] Fig.18 This is a cross-sectional view of the head portion of the pulse wave measurement device according to the second embodiment.

[0038] Fig.19 This is an overall block diagram of the pulse wave measurement device according to the third embodiment.

[0039] Fig. 20 This is an overall block diagram of the pulse wave measurement device according to the fourth embodiment. DETAILED DESCRIPTION

[0040] Hereinafter, the mode for implementing the present invention will be described with reference to the drawings. In each figure, the same components are sometimes given the same reference numerals, and repeated descriptions are omitted.

[0041] [Implementation Method 1]

[0042] First, use Figure 1 , Figure 2 , Figure 3 The pulse wave measurement system 1000 according to the first embodiment will be described. Figure 1 This is an overall diagram of pulse wave measurement system 1000 according to Embodiment 1 of the present invention. Figure 2 This is a side view illustrating the pulse wave measurement device 1 according to the first embodiment. Figure 3 yes Figure 1 1 is an exploded view of the pulse wave measurement device 1 included in the pulse wave measurement system 1000.

[0043] like Figure 1 As shown, the pulse wave measurement system 1000 according to Embodiment 1 includes a pulse wave measurement device 1 and an information processing device 5 capable of communicating with the pulse wave measurement device 1 .

[0044] The pulse wave measurement device 1 is a vital sign that is worn on the wrist of the subject, for example, with the pulse wave sensor 10 disposed near the radial artery of the subject. The pulse wave captures changes in blood vessel volume as the heart pumps blood as a waveform, and the pulse wave measurement device 1 can monitor changes in blood vessel volume.

[0045] (Configuration of Pulse Wave Measurement Device According to Embodiment 1)

[0046] Reference Figure 1 , Figure 2 and Figure 3 The pulse wave measuring device 1 is a watch-type wearable device that can be worn on a subject, and mainly includes a pulse wave sensor 10, a sensor fixing part 20 and a belt part 80. It should be noted that, Figure 2 The arrow N in FIG. 1 represents the detection surface of the pulse wave sensor 10 ( Figure 2 The normal direction of the lower surface in the figure.

[0047] The pulse wave sensor 10 is a strain sensor, and is fixed to one side (the subject side) of the sensor fixing part 20. Specifically, for example, a plurality of threaded holes 10y are provided on the back side of the pulse wave sensor 10. For example, in the sensor fixing part 20, a plurality of insertion holes 20y for screw insertion are provided in a manner that penetrates the sensor fixing part 20. For example, two screws 90 are respectively inserted into each insertion hole 20y, and the front end portions protrude from each insertion hole 20y and engage with each threaded hole 10y, thereby fixing the pulse wave sensor 10 to one side of the sensor fixing part 20. On one side of the sensor fixing part 20, a cylindrical positioning hole or the like for positioning the pulse wave sensor 10 may be provided.

[0048] A through hole 10x may be provided on the side of the pulse wave sensor 10 for passing a cable for extracting an electrical signal from the inside of the pulse wave sensor 10. By passing the cable through the through hole 10x, the signal detected by the pulse wave sensor 10 can be connected to an external circuit by wire. For example, a notch 20x is provided in the sensor fixing portion 20, and the through hole 10x is exposed in the notch 20x.

[0049] The belt 80 is an adjustment part and is a belt-shaped body for wearing the pulse wave sensor 10 and the sensor fixing part 20 on the wrist of the subject, etc., and is configured to be wrapped around the wrist of the subject from the outside. The belt 80 is formed of, for example, resin, rubber, cloth, etc., and has flexibility.

[0050] One end of the belt portion 80 is connected to one end side of the sensor fixing portion 20 in a uniaxially swingable manner, and the other end of the belt portion 80 is connected to the other end side of the sensor fixing portion 20 in a uniaxially swingable manner. Specifically, one end of the belt portion 80 is inserted into a groove provided on the belt fixing portion 30 and fixed to the belt fixing portion 30. At the end of the belt fixing portion 30 on the sensor fixing portion 20 side, a protrusion 30a protruding on both sides in the width direction of the belt portion 80 is provided. The protrusion 30a is inserted into the through hole of the mounting portion 20a provided on the sensor fixing portion 20 as the axis UA1.

[0051] Therefore, if Figure 2 As shown, the sensor fixing part 20 is connected to the belt fixing part 30 fixing one end of the belt part 80 so as to be swingable along the arrow direction with UA1 as the axis. The belt fixing part 30 moves integrally with the belt part 80. That is, the axis UA1 becomes the axis when one end side of the belt part 80 swings.

[0052] The other end of the belt portion 80 is inserted into a through hole provided in the belt portion insertion portion 40. At the end of the belt portion insertion portion 40 on the sensor fixing portion 20 side, there are provided protrusions 40a protruding on both sides in the width direction of the belt portion 80. The protrusions 40a are inserted into the through hole of the mounting portion 20b provided in the sensor fixing portion 20 as the axis UA2. That is, the other end of the belt portion 80 is connected to the other end side of the sensor fixing portion 20 via the belt portion insertion portion 40 by the axis UA2 so as to be swingable.

[0053] Thus, the sensor fixing part 20 and the belt insertion part 40 into which the other end of the belt 80 is inserted are connected so as to be swingable in a single axis in the direction of the arrow about the axis UA2. The belt insertion part 40 and the belt 80 move integrally. That is, the axis UA2 becomes the axis when the other end side of the belt 80 swings. Figure 2 The arrow direction is a direction in which the strength of the fastening belt portion 80 is increased or decreased.

[0054] The other end of the belt portion 80 inserted into the through hole of the belt portion insertion portion 40 passes through the through hole of the belt portion insertion portion 40, and is detachably connected to the outer peripheral surface of the portion of the belt portion 80 that is not inserted into the belt portion insertion portion 40 by, for example, a surface fastener. By changing the position of the other end of the belt portion 80 in the longitudinal direction of the belt portion 80, the fastening strength when the pulse wave measurement device 1 is worn on the subject can be changed.

[0055] When the pulse wave measurement device 1 is worn on the subject, the sensor fixing portion 20 and the belt portion 80 swing around the axis UA1 and the axis UA2, so that the entire pulse wave measurement device 1 can follow the shape of the subject's wrist, etc. At this time, by changing the fastening strength of the belt portion 80, the pulse wave sensor 10 can be pressed in the N direction, so that the closeness between the subject and the pulse wave sensor 10 can be adjusted. As a result, the strain body 12 side of the pulse wave sensor 10 can be brought into close contact with the radial artery of the subject. In this embodiment, the sensor fixing portion 20 becomes a pressing member that presses against the wrist of the pulse wave sensor 10 due to the fastening of the belt portion 80.

[0056] In addition, Figure 2 In the embodiment, the lower surface of the pulse wave sensor 10 becomes the detection surface for detecting the pulse wave, and the axis UA1 and the axis UA2 are located above the detection surface of the pulse wave sensor 10, that is, on the side opposite to the subject with respect to the detection surface of the pulse wave sensor 10. It should be noted that the detection surface of the pulse wave sensor 10 refers to the surface of the pulse wave sensor 10 that contacts the subject, specifically, the surface of the strain body 12 described later on the subject's side.

[0057] By positioning the axis UA1 and the axis UA2 on the side opposite to the subject with respect to the detection surface of the pulse wave sensor 10, the fastening strength of the belt portion 80 is changed, so that the detection surface of the pulse wave sensor 10 can be easily pressed against the wrist of the subject. In particular, it is preferred that the lower surface of the pulse wave sensor 10 protrudes toward the subject from the sensor fixing portion 20. Thus, by changing the fastening strength of the belt portion 80, the detection surface of the pulse wave sensor 10 can be more easily pressed against the wrist of the subject.

[0058] The axis UA1 and the axis UA2 are preferably aligned with the belt portion 80. Figure 2 When the belt portion 80 extends in the left-right direction, the direction perpendicular to the length direction ( Figure 2 The depth direction of the

[0059] In addition, Figure 2 In the middle, that is, when viewed from the side, the straight line connecting the center of the axis UA1 and the center of the axis UA2 is preferably parallel to the detection surface of the pulse wave sensor 10. In this case, the distance between the straight line connecting the center of the axis UA1 and the center of the axis UA2 and the detection surface of the pulse wave sensor 10 is, for example, not less than 2 mm and not more than 8 mm. It should be noted that the parallelism here includes the case where the angle formed by the two straight lines is within ±5 degrees. By making the straight line connecting the center of the axis UA1 and the center of the axis UA2 parallel to the detection surface of the pulse wave sensor 10, when the belt portion 80 is tightened, the detection surface of the pulse wave sensor 10 can be uniformly pressed against the subject.

[0060] Note that, when the detection surface of the pulse wave sensor 10 is a curved surface protruding toward the subject, the tangent line at the end of the detection surface of the pulse wave sensor 10 closest to the subject is replaced with the detection surface of the pulse wave sensor 10 described above.

[0061] In addition, Figure 2 In the side view of the embodiment, the straight line connecting the midpoint of the straight line connecting the center of the axis UA1 and the center of the axis UA2 and the straight line connecting the midpoint of the detection surface of the pulse wave sensor 10 is preferably perpendicular to the straight line connecting the center of the axis UA1 and the center of the axis UA2. It should be noted that the perpendicularity here includes the case where the angle formed by the two straight lines is within 90±5 degrees. By making the midpoint of the straight line connecting the center of the axis UA1 and the center of the axis UA2 and the straight line connecting the midpoint of the detection surface of the pulse wave sensor 10 perpendicular to the straight line connecting the center of the axis UA1 and the center of the axis UA2, the detection surface of the pulse wave sensor 10 can be uniformly pressed against the subject when the belt portion 80 is tightened.

[0062] It should be noted that a force-applying mechanism for applying force to the pulse wave sensor 10 toward the subject may be provided between the sensor fixing portion 20 and the pulse wave sensor 10. The force-applying mechanism may be composed of, for example, only a spring, or may be a structure including a spring and an adjustment portion for adjusting the force of the spring, or may be other structures. By providing a force-applying mechanism for applying force to the pulse wave sensor 10 toward the subject, the detection surface of the pulse wave sensor 10 can be stably pressed against the wrist of the subject. Regarding the structure having a spring capable of adjusting the force, Fig.18 This will be described in detail in the embodiment 2 shown.

[0063] (Control box)

[0064] Reference Figure 4 The pulse wave measurement device 1 includes a pulse wave sensor 10 as a control structure, a control substrate 17, a sensor fixing part (pressing member) 20, and a belt part (adjusting part) 80. In addition, a position detection unit 90 for detecting the position of the pulse wave sensor 10 relative to the tibial artery may be included.

[0065] The pulse wave sensor 10 includes a strain body 12 and four strain gauges in a housing 100 . The control substrate 17 includes an analog front end unit 13 , a control unit 14 , a communication unit 15 , and a battery 16 .

[0066] The strain gauges 11a, 11b, 11c, and 11d have resistors, and when the load portion 123 (see FIG. 124 ) of the pulse wave sensor is energized according to the pulse wave of the subject, Fig.14 ) When a load is applied to cause the bridge arm portion 122 to elastically deform, the resistance value changes.

[0067] The analog front end unit (AFE) 13 includes, for example, a bridge circuit 131, an amplifier circuit 132, an analog-to-digital conversion circuit (A / D conversion circuit) 133, and an interface 134. The AFE 13 may also include a temperature compensation circuit. In the AFE 13, the amplifier circuit 132, the A / D conversion circuit 133, and the interface 134 function as an output unit α.

[0068] The electrodes 114 and 115 (see Fig.16 ) is connected to the bridge circuit 131 of the AFE 13 to form a full bridge. Thus, the bridge circuit 131 can output a voltage (analog signal) corresponding to the change in the resistance value of each resistor of the four strain gauges 11a, 11b, 11c, and 11d.

[0069] When the resistance values ​​of the plurality of strain gauges 11a, 11b, 11c, and 11d having such a structure change, the positional relationship of the strain gauges 11a, 11b, 11c, and 11d changes, so that the pulse wave information can be detected from the radial artery of the subject in close contact, that is, the pulse wave can be measured. In the present embodiment, an example in which the pulse wave sensor 10 has four strain gauges is shown. However, the number of strain gauges that the pulse wave sensor 10 has is not particularly limited as long as the number is one or more. It should be noted that, when the pulse wave sensor 10 has one strain gauge, the "resistance value of the pulse wave sensor 10" and the "resistance value of the strain gauge" are roughly synonymous.

[0070] In the pulse wave measurement device 1, the pulse wave sensor 10 including the strain gauges 11a to 11d and the strain body 12 and the control substrate 17 may be arranged in the same housing 100 (see Fig.15 ) and may not be configured in the same shell.

[0071] The bridge circuit 131 of the AFE 13 outputs a voltage (analog signal) corresponding to the resistance value of the resistor of the strain gauges 11a to 11d. The voltage output from the bridge circuit 131 is amplified by the amplifier circuit 132, converted into a digital signal by the A / D conversion circuit (A / D conversion unit) 133, and transmitted to the control unit 14. When the AFE 13 includes a temperature compensation circuit, the temperature-compensated digital signal is transmitted to the control unit 14.

[0072] The control unit 14 outputs the digital signal sent from the AFE 13 to the information processing device 5 via the communication unit 15. The control unit 14 may be configured to include a ROM (read-only memory), a RAM (random access memory), a main memory, etc. in addition to a computing unit such as a microprocessor, a CPU (central processing unit), an FPGA (field programmable gate array), and an ASIC (application-specific integrated circuit). For example, the control unit 14 is programmed to instruct the strain gauges 11a to 11d to obtain a resistance value, or to instruct and transmit the resistance value output from the strain gauges 11a to 11d via the AFE 13, etc., in response to an instruction from the information processing device 5. The various functions of the control unit 14 can be realized by reading the program recorded in the ROM, etc. to the main memory and executing it by a computing unit such as a CPU. However, part or all of the control unit 14 may be realized only by hardware. In addition, the control unit 14 may be composed of a plurality of physical devices, etc.

[0073] The communication unit 15 performs communication between the pulse wave measurement device 1 and the information processing device 5. Specifically, the communication unit 15 sends a digital signal converted by the AFE 13 based on the resistance value output by the strain gauges 11a to 11d to the information processing device 5. In addition, when the pulse wave measurement device 1 operates according to the instruction of the information processing device 5, the communication unit 15 receives a control instruction for the pulse wave sensor 10 from the information processing device 5.

[0074] The communication method of the communication unit 15 is not particularly limited. For example, the communication unit 15 can use a communication method such as a wireless or wired LAN such as Wifi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), etc.

[0075] The battery 16 is a power source that supplies power to the pulse wave sensor 10 and the control substrate 17. Note that the pulse wave sensor 10 may be supplied with power from an external power source without including the battery 16.

[0076] In addition, refer to Figure 4 The information processing device 5 at least includes a communication unit 51, a control unit 52 and a storage unit 53. In addition, the information processing device 5 may include a display unit 54 and / or a sound output unit 55, and a timing unit 56.

[0077] The communication unit 51 obtains a digital signal obtained by A / D conversion from the resistance value from the communication unit 15 of the pulse wave measurement device 1. When the information processing device 5 issues an operation instruction such as drive / stop to the pulse wave measurement device 1, the communication unit 51 sends a control instruction to the pulse wave measurement device 1.

[0078] The display unit 54 displays text and images related to the processing content and / or processing results of the control unit 52. The display method is not particularly limited. In addition, the information processing device 5 may include the display unit 54, or the sound output unit 55 instead of the display unit 54. In addition, the sound output unit 55 can output sounds related to the processing content and / or processing results of the control unit 52. The display unit 54 and the sound output unit 55 function as a notification unit β and an adjustment instruction unit.

[0079] The timekeeping unit 56 measures time and notifies the control unit 52 of the pulse wave measurement timing (for example, 0 minute of each hour, a predetermined time (for example, 12 hours) has passed since the last measurement) as needed.

[0080] The storage unit 53 stores information necessary for the operation of the information processing device 5. The storage unit 53 stores, for example, critical point data 531. The critical point data 531 is data indicating a threshold value of an output voltage that is compared in the control unit 52 to determine whether pressure adjustment is necessary in the preliminary adjustment.

[0081] The control unit 52 has a predetermined period average value calculation unit 521, a comparison unit 522, a zero point adjustment unit 523, an acceleration pulse wave calculation unit 524, a measurement timing notification unit 525, and an acceleration pulse wave analysis unit 526. In addition, a blood sugar level analysis unit 527 may be included.

[0082] The predetermined period average value calculation unit 521 and the comparison unit 522 correspond to the operation means for adjusting the pressure during the pulse wave measurement of the present invention. Specifically, the predetermined period average value calculation unit 521 calculates the average value of the voltage level of the digital signal after A / D conversion of the pulse wave measured by the subject immediately after wearing the pulse wave measurement device 1 within the predetermined period.

[0083] The comparison unit 522 compares the average value of the digital signal with a critical point as a threshold value, and when the average value is smaller than the critical point, the display unit 54 and the sound output unit 55 notify that the pressure is increased.

[0084] The zero-point adjustment unit 523 performs zero-point adjustment when used for the first time.

[0085] The acceleration pulse wave calculation unit 524 performs second-order differentiation on the digital signal to calculate the acceleration pulse wave.

[0086] When the measurement timing arrives, the measurement timing notification unit 525 notifies through the display unit 54 and the sound output unit 55 to urge the measurement.

[0087] The acceleration pulse wave analysis unit 526 analyzes the health status of the subject based on the acceleration pulse wave measured this time and the acceleration pulse wave measured in the past.

[0088] The blood sugar level analyzing unit 527 analyzes the blood sugar level of the subject based on the currently measured accelerated pulse wave and the previously measured accelerated pulse wave as necessary. It should be noted that the blood sugar level analyzing unit 527 may not be provided.

[0089] In addition, the control unit 52 controls the information processing device 5 as a whole. The control unit 22 can be implemented by, for example, a CPU, an FPGA, an ASIC, etc. In addition, the control unit 52 may include a memory. The various functions of the control unit 52 can be implemented by reading out a program recorded in a ROM, etc. to a main memory and executing it by the CPU. However, a part or all of the control unit 52 may be implemented only by hardware. In addition, the control unit 52 may be composed of a plurality of physical devices, etc. The control unit 52 compares the digital signal received from the pulse wave measurement device 1 with the critical point to determine whether pressure adjustment is required, and calculates the acceleration pulse wave in the main measurement. In the following, reference will be made to Figures 5 to 13 The processing contents of the control unit 52 will be described in detail.

[0090] (Output voltage and belt length)

[0091] here, Figure 5 FIG. 4 is a graph showing the average value of the output voltage of the pulse wave when the length of the belt portion is changed. Figure 5 As shown, as the length of the belt portion increases, the pressing force of the pulse wave sensor 10 on the skin decreases, and the signal level of the digital signal of the measured pulse wave decreases.

[0092] However, since the thickness and flatness of the wrist vary from person to person, the length of the belt portion at which the output voltage decreases varies from person to person.

[0093] Therefore, in the present invention, the voltage level of the digital signal output as the measured pulse wave is compared with a predetermined range relative to the maximum voltage level of the output unit α, and when the voltage level of the digital signal is smaller than the range, the pressing force on the pulse wave sensor 10 is adjusted, or an adjustment instruction is issued.

[0094] Thus, the pressure applied to the pulse wave sensor 10 can be appropriately adjusted according to the characteristics of the wearer's wrist. Figure 5In the example, when 10mV is the maximum and the critical point is 4mV, for subject C, even when the belt length is 165mm, since the voltage level of the digital signal is above the critical point, subject C does not need to adjust the pressure. On the other hand, for subject D, when the belt length is 155mm, since the voltage level of the digital signal does not reach the critical point, the pressure adjustment instruction is received when the belt length does not reach 155mm.

[0095] As described above, the pressure applied to the pulse wave sensor 10 can be confirmed by the output signal level itself output from the pulse wave sensor 10, so that a pressure gauge or the like is not required, and the pressure can be adjusted based on the output signal level so that the output signal level is within an appropriate range. Thus, it is possible to suppress the pressure difference caused by the different arm thicknesses of each subject and the signal error caused by the change in pressure due to repeated measurements of the same subject.

[0096] here, Figure 6 A graph showing an example of a pulse wave measured by a pulse wave measuring device and an acceleration pulse wave calculated from the pulse wave. Figure 6 In FIG. 1 , (a) shows a digital output waveform obtained by performing A / D conversion on a pulse wave, and (b) shows a waveform of an accelerated pulse wave.

[0097] The acceleration pulse wave calculation unit 524 of the information processing device 5 performs denoising, smoothing and normalization processing on the digital signal obtained by A / D conversion of the pulse wave, and performs second-order differentiation to calculate the acceleration pulse wave. It should be noted that the digital pulse wave measured by the pulse wave measurement device 1 and obtained by A / D conversion is equivalent to the fingertip volume pulse wave in the heartbeat, so the acceleration pulse wave is equivalent to the waveform obtained by differentiating the fingertip volume pulse wave as the original waveform twice. Generally, the state of the pulse can be analyzed in the state of the acceleration pulse wave.

[0098] here, Figure 7 This is a diagram for explaining the inflection point of a normal acceleration pulse wave.

[0099] Inflection point a (a wave) is the first inflection point in the cycle, known as the initial positive wave of contraction, indicating the maximum point of change in the rate of blood vessel expansion. Inflection point b (b wave) is the second inflection point in the cycle, known as the initial negative wave of contraction, and becomes shallower (the absolute value becomes smaller) if the artery has poor elasticity. A wave and b wave are the forward components of the contraction period, reflecting the driving pressure wave generated by the blood ejection.

[0100] Inflection point c is the third inflection point in the cycle, called the mid-systolic rising wave, which is the reflected wave generated by vascular resistance. Inflection point d is the fourth inflection point in the cycle, called the late systolic falling wave, which is the end point of the reflected wave generated by vascular resistance. The higher the vascular resistance, the deeper it is (the larger the absolute value).

[0101] It should be noted that the inflection point e is the fifth inflection point in the cycle, also known as the early diastolic positive wave (e wave). The inflection point f is the sixth inflection point in the cycle, also known as the early diastolic negative wave (f wave).

[0102] The c-wave and d-wave are the systolic backward components, and the systolic backward component reflects the reflected pressure wave that is reflected back from the propagation of the driving pressure wave to the extremities. Here, it is known that the reflected wave usually increases due to aging, arteriosclerosis, hypertension, etc., and the systolic backward component (c-wave, d-wave) increases relative to the systolic forward component (a-wave, b-wave). In particular, as the age of blood vessels increases, the depth of the d-wave deepens relative to the depth of the b-wave. Therefore, by analyzing the inflection point in the acceleration pulse wave, the age of blood vessels and the state of arteries can be understood.

[0103] In this way, in order to calculate and analyze the accelerated pulse wave, it is necessary to measure the pulse wave, which is the original waveform of the accelerated pulse wave, under appropriate conditions as a prerequisite.

[0104] here, Figure 8 1 shows a graph showing changes in the acceleration pulse wave caused by changes in the pressure applied to the pulse wave sensor 10. Specifically, Figure 8 Graph showing the accelerated pulse wave when the pulse wave of the same male subject in his 50s is measured by changing the belt pressure.

[0105] Thus, in the pulse wave measurement device of the first embodiment, by changing the length of the belt portion, the pressing force on the wrist of the subject on the detection surface of the pulse wave sensor changes. Figure 5 As shown in FIG. 1 , if the waveform of the pulse wave digital signal changes depending on the belt pressure, then even in the case of Figure 8 In the acceleration pulse wave calculated from the digital signal shown, the amplitude direction position and time of the c wave, d wave, and e wave as waveform indexes also change.

[0106] exist Figure 8 In the example, particularly when the belt length is 165 mm, the magnitude relationship between the b wave and the d wave is reversed compared to the cases with other belt lengths. Therefore, it can be considered that in the case of 165 mm, the pressure is too low and is not suitable for pulse wave measurement.

[0107] In contrast, when tightening, no particular adverse effect is apparent. Therefore, in the pulse wave measurement of the present invention, pressure adjustment is performed in a manner that excludes situations where the critical point is not reached and the numerical value is significantly erroneous.

[0108] Specifically, in the control of the present invention, the pulse wave is measured, and the average value of the voltage level of the digital signal after A / D conversion is compared with a pre-set specified range (critical point). When it is lower than the specified range, the measurement is considered inappropriate and pressure adjustment is indicated to increase the pressing force on the pulse wave sensor.

[0109] As an example, Fig. 9 An explanatory diagram showing the average value of the output level of the pulse wave. The average value of the voltage level of the digital signal is, for example, the average value of a predetermined number of heart beats (e.g., 10 beats (10 cycles)) or the average value of a predetermined period (e.g., 5 seconds, 10 seconds, etc.). This example shows an example in which the average value of the output level is 2.41 mV when 10 beats of the heart beat are the predetermined period.

[0110] Here, a predetermined threshold value (critical point) of the voltage level to be compared when judging whether the pressure is appropriate is set relative to the maximum output level of the A / D conversion circuit 133 included in the output unit α. For example, the critical point as a predetermined range is 35% or more relative to the maximum output level of the output unit α, and more preferably 40% or more. It should be noted that the maximum output level as the upper limit of the output unit α varies depending on the size of the strain body, etc., but is known in advance.

[0111] For example, when the maximum output level of output unit α is 5mV, Fig. 9 The average value of the output level is 2.41mV which corresponds to 48%, so the pressure is in the appropriate range.

[0112] On the other hand, for example, when the maximum output level of the output section α is 10mV, Fig. 9 The average value of the output level in 2.41 mV corresponds to 24%, so the voltage level is less than the preset range. Therefore, the pressure applied to the pulse wave sensor is insufficient, so the pulse wave sensor 10 issues a command to increase the pressure, that is, to tighten the belt 80 strongly.

[0113] here, Fig.10 1 is a diagram showing the inflection point of the acceleration pulse wave according to the voltage value of the average output level. In this example, the maximum output level is 10 mV and the critical point of the preset range is 4 mV.

[0114] In the above Figure 8 In the experiment, the length of the belt is changed for one subject, and Fig.10In FIG. 1 , the pulse waves acquired by the pulse wave measurement device 1 when the belt length of two subjects was changed five times were subjected to second-order differentiation to obtain the accelerated pulse waves, and each inflection point was plotted.

[0115] Then, if Fig.10 As shown in (a), the values ​​of the c-wave, d-wave, e-wave, and f-wave of the normalized signal with the calculated maximum value of the acceleration pulse wave set to 1 (the value of the a-wave) and the minimum value set to 0 (the value of the b-wave) are plotted on the horizontal axis as the signal level of the pressure pulse wave. Specifically, Fig.10 (a) shows the sampling frequency = 1kHz obtained Figure 8 The pulse wave of the normalized average acceleration pulse wave is resampled at 50 Hz at the time (moment) when each peak value (c, e) and valley value (b, d, f) of the normalized average acceleration pulse wave appears. Fig.10 The 0 second point (origin) in (a) is equivalent to 33.3 msec to the left of point a.

[0116] from Fig.10 As can be seen from (a), in the normalized signal value, the wave height value of the d wave is below 4.0 mV, which is a critical value, and fluctuates upward (eg, takes a larger value) than other values.

[0117] also, Figure 8 The time when the inflection points c, d, e and f respectively appear (hereinafter sometimes referred to as the peak / valley time) is Fig.10 is shown in (b).

[0118] from Fig.10 As can be seen from (b), the peak / valley time fluctuates downward below 4.0 mV, which is a critical value, that is, the time decreases and a time shift occurs.

[0119] Fig.11 Graph summarizing signal deviations caused by changes in pressing force within the pulse wave measurement range. Specifically, it shows signal deviations caused by changes in pressing force within the pulse wave measurement range, and the error bars on both the vertical and horizontal axes are σ.

[0120] like Fig.11 As shown, without adjustment, the deviation of each waveform index (inflection point) of the accelerated pulse wave calculated from the biosignal (ie, the pulse wave obtained from a general pulse wave measuring device (vital sensor)) is about 10%.

[0121] Therefore, as described above, if the average value of the voltage of the pulse wave signal itself within a predetermined period is compared with the critical point, only Fig.10The error can be reduced to a few percentage points only when the main measurement of the next process is performed when the value is above the critical point shown on the right side of the graphs (a) and (b). Therefore, in the acceleration pulse wave calculated from the digital signal and used for analysis, the a wave, b wave, c wave, d wave, e wave, and f wave, which are inflection points, appear within the appropriate intensity range.

[0122] Thus, when the pulse wave measurement device 1 is worn, the output signal level of the sensor is controlled as pressure adjustment, and the blood flow and reflected wave velocity can be measured under the same conditions each time. Thus, since the deviation of the measured value caused by the pressure difference is suppressed, the analysis accuracy of the signal detection for health management and disease using the acceleration pulse wave calculated from the pulse wave can be improved.

[0123] (Pressure adjustment and main measurement for pulse wave measurement)

[0124] Here, we will refer to Fig.12 and Fig.13 The pre-pressure adjustment for pulse wave measurement according to the present invention will be described. Fig.12 This is a detailed flow chart of the pressure adjustment method for pulse wave measurement.

[0125] In step S101 , when the user wears the pulse wave measurement device 1 on the wrist and is about to start measurement, pressure adjustment is started before that.

[0126] In step S102 , the pulse wave measurement device 1 measures the pulse wave and transmits a digital signal as an output to the information processing device 5 .

[0127] In step S103, the information processing device 5 calculates the average value of the output level of the pulse wave digital signal in an arbitrary period. The arbitrary period used for calculating the average value is a preset period, such as 10 heart beats, 5 seconds, etc.

[0128] In step S104, the information processing device 5 compares whether the average value of the pulse wave output level in any period is equal to or higher than the critical point.

[0129] When “NO” in S104 , that is, when the average value of the output levels is smaller than the critical point, in step S105 , the information processing device 5 instructs pressure adjustment via the display unit 54 or the sound output unit 55 .

[0130] Then, in step S106, in this embodiment, the pressure is adjusted by manually adjusting the tightening force of the belt portion 80. After the adjustment is completed, this process ends and enters the main measurement process ( Fig.13 S204).

[0131] On the other hand, in step S104, when the average value of the output level of the pulse wave in any period is above the critical point, the process proceeds to step S107, and a notification is given through the display unit 54 or the sound output unit 55 that no pressure adjustment is required, and this process ends, and the process proceeds to the main measurement process ( Fig.13 S204).

[0132] In this control, the critical point is pre-set according to the maximum voltage of the output unit α, so there is no need to adjust the pressure applied to the sensor in stages while observing the situation, which can shorten the time required for adjustment and adjust to an appropriate pressing force. Therefore, the error can be reduced.

[0133] Next, we will refer to Fig.13 The overall flow of pulse wave measurement including pressure adjustment is described. Fig.13 This is the overall flow chart of pulse wave measurement.

[0134] If the pulse wave measurement device 1 is to be used for the first time after purchase (step S201), the process proceeds to step S202 to perform zero-point calibration of the pulse wave measurement device 1. In the zero-point calibration, in order to adjust the initial error caused by the solid difference of the strain gauges 11a to 11d themselves, before wearing, the detection surface of the pulse wave sensor 10 is suspended in the air, and the signal is adjusted to point to 0. It should be noted that when the pulse wave measurement device 1 of the present invention is lent to a hospital, a gym, etc., since the manager has already completed the zero-point adjustment process in advance, the measurer starts the process from step S203.

[0135] When the 0-point correction is completed, the process proceeds to step S203, and the process proceeds to step S204. Fig.12 The pressure adjustment process for pulse wave measurement is shown.

[0136] On the other hand, when this wearing is not the first time ("No" in S201), when the subject wears it again from a never-worn state, in step S203, the pulse wave is measured and the digital signal as output is transmitted to the information processing device 5.

[0137] In step S203, the above Fig.12 After the pre-pressure adjustment (S102 to S107) shown in FIG. 1, the process proceeds to step S204, where the pulse wave is measured during a prescribed period using the pulse wave measurement device 1 and sent to the information processing device 5. It should be noted that step S204 is the main measurement, so it can be adjusted more than the measurement period ( Fig.12 S102) in, or may have a period of the same degree.

[0138] In step S205, the information processing device 5 performs signal processing such as second-order differentiation of the pulse wave as a digital signal to calculate the acceleration pulse wave.

[0139] In step S206 , the information processing device 5 stores the acceleration pulse wave calculated in step S205 in advance.

[0140] When the measurement is intentionally repeated in step S207 , the measurer does not remove the belt portion 80 but keeps the pulse wave measurement device 1 worn.

[0141] When the next trigger event is reached in step S208, the process proceeds to step S209, and the pulse wave measurement device 1 measures the pulse wave again during the specified period and sends it to the information processing device 5. It should be noted that the next measurement trigger event corresponds to, for example, reaching a timing suitable for the next measurement after a meal, after a specified time (for example, every hour, after 12 hours), after exercise, etc. Alternatively, the next trigger event may include a situation where the measurement is desired according to the intention of the measurer.

[0142] Next, in step S210 , the information processing device 5 performs signal processing such as second-order differentiation of the pulse wave as a digital signal to calculate the acceleration pulse wave.

[0143] In step S211 , the information processing device 5 compares the acceleration pulse wave calculated in step S205 with the acceleration pulse wave calculated in step S210 to detect a change.

[0144] In step S212, the blood sugar level is estimated based on the change of the accelerated pulse wave as needed. As an example, it is known that the size and timing of the inflection point in the accelerated pulse wave are related to the blood sugar level, so the blood sugar level is estimated based on the correlation between the waveform of the accelerated pulse wave and the blood sugar level stored as needed.

[0145] Then, in step S213, the information processing device 5 displays the analysis and evaluation of the change of the pulse wave based on the acceleration, or the analysis and evaluation of the blood sugar level state.

[0146] By such control, in the present invention, after the pressure adjustment is performed using the output level, the pulse wave measurement is performed as the main measurement. That is, in the pre-pressure adjustment process, since the main measurement is not performed when the output level is out of range, the average value of the signal level (digital signal) of the pulse wave in the main measurement will not be as large as that in the pre-pressure adjustment process. Figure 5Furthermore, since the actual measurement starts after the average value of the output level in the predetermined period reaches or exceeds the critical point, the case where the critical point is not reached, which is prone to errors, is not taken as the measurement object, and the pulse wave measured by the main measurement is within the appropriate range, which can greatly reduce the error.

[0147] Thus, when the pulse wave measurement device 1 is worn, the output signal level of the sensor is controlled to be above the critical point as pressure adjustment, so that the pulse wave can be measured under the same conditions each time. Thus, the deviation of the measured value caused by the pressure difference can be suppressed, and the analysis accuracy of the acceleration pulse wave and the blood sugar level can be improved.

[0148] <Pulse wave sensor structure>

[0149] Next, use Fig.14 and Fig.15 The detailed structure of the pulse wave sensor 10 will be described. Fig.14 is a front view of the pressure detection surface side of the pulse wave sensor 10, Fig.15 is a cross-sectional view of the pulse wave sensor 10. Fig.14 and Fig.15 The pulse wave sensor 10 includes a housing 100 , a strain body 12 , and strain gauges 11 a to 11 d .

[0150] The strain body 12 includes a base 121, a bridge arm 122, a load portion 123, and an extension portion 124. The strain body 12 is flat, and each component is integrally formed by, for example, a stamping method. The strain body 12 has, for example, a four-fold symmetrical shape when viewed from above. The thickness t of the strain body 12 other than the load portion 123 is constant. The appropriate range of the thickness t will be described later.

[0151] It should be noted that for the sake of convenience, Figure 2 In an upside-down state Fig.15 In the embodiment, the side of the strain body 12 in the pulse wave sensor 10 where the load part 123 is provided is set as the upper side or one side, and the side where the load part 23 is not provided is set as the lower side or the other side. In addition, the surface of the side where the load part 23 is provided in each part is set as one surface or the upper surface, and the surface of the side where the load part 123 is not provided is set as the other surface or the lower surface. However, the pulse wave sensor 10 can be used in an upside-down state or can be configured at any angle. In addition, the top view refers to observing the object from the normal direction of the upper surface of the strain body 12, and the top view shape refers to the shape of the object observed from the normal direction of the upper surface of the strain body 12.

[0152] In the pulse wave sensor 10, the housing 100 is a part that holds the strain body 12. The housing 100 is a hollow cylindrical shape, one side of which is blocked, and the other side (the surface on the detection side) is open. The housing 100 can be formed of, for example, metal, resin, etc. The roughly disk-shaped strain body 12 is fixed with an adhesive or the like to close the opening on the upper surface side of the housing 100.

[0153] In the strain body 12, the base 121 is Fig.14 The circular frame-shaped (ring-shaped) area on the outside of the circular dotted line shown. It should be noted that the area inside the circular dotted line is sometimes called a circular opening. That is, the base 121 of the strain body 12 has a circular opening. The width w1 of the base 121 is, for example, not less than 1 mm and not more than 5 mm. The preferred range of the inner diameter d of the base 121 (i.e., the diameter of the circular opening) will be described later.

[0154] The bridge arm portion 122 is provided to bridge the inner side of the base portion 121. The bridge arm portion 122 has, for example, two bridge arms that cross each other in a cross shape when viewed from above, and the intersection area of ​​the two bridge arms includes the center of the circular opening. Fig.14 In the example, one bridge arm constituting the cross has the X direction as its length direction, and the other bridge arm constituting the cross has the Y direction as its length direction, and the two are orthogonal. Preferably, each of the two orthogonal bridge arms is located on the inner side of the inner diameter d (the diameter of the circular opening) of the base 121 and is as long as possible. That is, it is preferred that the length of each bridge arm is approximately equal to the diameter of the circular opening. In each bridge arm constituting the bridge arm portion 122, the width w2 outside the intersection area is constant, for example, the width w2 is greater than 1 mm and less than 5 mm. Although it is not necessary for the width w2 to be constant, it is preferred that the strain can be detected linearly by making the width w2 constant.

[0155] The load portion 123 is provided in the bridge arm portion 122. The load portion 123 is provided, for example, in a region where two bridge arms constituting the bridge arm portion 122 intersect. The load portion 123 protrudes from the upper surface of the bridge arm portion 122. The protrusion amount of the load portion 123 relative to the upper surface of the bridge arm portion 122 is, for example, approximately 0.1 mm. The bridge arm portion 122 has flexibility, and elastic deformation occurs when a load is applied to the load portion 123.

[0156] The four extensions 124 are fan-shaped portions extending from the inner side of the base 121 toward the bridge arm 122 in a plan view. A gap of about 1 mm is provided between each extension 124 and the bridge arm 122. The extensions 124 do not contribute to the sensing of the pulse wave sensor 10 and therefore may not be provided.

[0157] In addition, if Fig.15 As shown in FIG. 1 , a control substrate 17 is provided inside the pulse wave sensor 10. The control substrate 17 is, for example, a flexible substrate on which a Figure 4 The AFE 13, control unit 14, communication unit 15, battery 16, etc. are shown. In addition, the control board 17 is connected to the strain gauges 11a to 11d by a cable (not shown) for inputting and outputting electrical signals. The cable is a wire such as a shielded cable. In addition, the control board 17 only needs to be set in the pulse wave measurement device 1, so the control board 17 can also be set outside the housing 100.

[0158] The strain gauges 11a to 11d are provided on the strain body 12. The strain gauges 11a to 11d can be provided, for example, on the lower surface side of the bridge arm portion 122. Since the bridge arm portion 122 is in the shape of a flat plate, the strain gauge can be easily attached. It is sufficient to provide at least one strain gauge 11a to 11d. In the present embodiment, four strain gauges 11a to 11d are provided. By providing four strain gauges 11a to 11d, strain can be detected by a full bridge.

[0159] Two of the four strain gauges 11b and 11d are arranged on the side of the bridge arm whose length direction is the X direction, close to the load portion 123 (the center side of the circular opening), so as to face each other across the load portion 23 in a plan view. The other two of the four strain gauges 11a and 11c are arranged on the side of the bridge arm whose length direction is the Y direction, close to the base 121, so as to face each other across the load portion 23 in a plan view. By arranging in this way, the compressive force and the tensile force can be effectively detected, and a large output can be obtained by a full-bridge.

[0160] The pulse wave sensor 10 is fixed to the arm of the subject in such a manner that the load portion 123 is pressed against the radial artery of the subject. When a load is applied to the load portion 123 in accordance with the pulse wave of the subject and the bridge arm portion 122 is elastically deformed, the resistance value of the resistor of the strain gauges 11a to 11d changes. The pulse wave sensor 10 can detect the pulse wave based on the change in the resistance value of the resistor of the strain gauges 11a to 11d caused by the deformation of the bridge arm portion 122. The pulse wave is output as a periodic voltage change from, for example, the measurement circuit AFE13 connected to the electrodes of the strain gauges 11a to 11d.

[0161] [Structure of strain gauge]

[0162] Here, refer to Fig.16 , Fig.17 Describe the structure of a strain gauge. Fig.16 1 is a top view illustrating a strain gauge 11 a according to one embodiment of the present invention. Fig.17 is a cross-sectional view illustrating a strain gauge 11a according to one embodiment, showing a cross-sectional view of a strain gauge 11a along Fig.16It should be noted that, below, the structure is described using the strain gauge 11a as an example, but the strain gauges 11b, 11c, and 11d also have the same structure.

[0163] Reference Fig.16 and Fig.17 The strain gauge 11a includes a substrate 110, a resistor 111, wirings 112 and 113, electrodes 114 and 115, and a cover layer 116. It should be noted that: Fig.16 In the figure, for convenience, only the outer edge of the cover layer 116 is shown by a dotted line. It should be noted that the cover layer 116 can be provided as required.

[0164] exist Fig.16 In the strain gauge 11a shown, the side of the substrate 110 without components is attached to Fig.14 The bridge arm portion 122 extending in the X direction is shown. At this time, the side of the substrate 110 without components is attached to the lower surface (back surface) of the bridge arm portion 122 using an adhesive or the like. In addition, Fig.16 The plan view refers to observing the object along the normal direction from the upper side to the lower side with respect to the upper surface 110U of the substrate 110. The plan view shape refers to the shape of the object when the object is observed in the normal direction.

[0165] The substrate 110 is a component used as a base layer for forming a resistor 111 and the like. The substrate 110 is flexible. The thickness of the substrate 110 is not particularly limited, and may be, for example, about 5 μm to 500 μm. It should be noted that from the perspective of the transmission of strain from the outer surface of the strain body 12 to the sensing portion, and the dimensional stability to environmental changes, the thickness of the substrate 110 is preferably in the range of 5 μm to 200 μm. In addition, from the perspective of insulation, the thickness of the substrate 110 is preferably greater than 10 μm.

[0166] The substrate 110 is formed of an insulating resin film such as PI (polyimide) resin, epoxy resin, PEEK (polyetheretherketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, LCP (liquid crystal polymer) resin, polyolefin resin, etc. It should be noted that the film refers to a member having a thickness of about 500 μm or less and having flexibility.

[0167] When the base material 110 is formed of an insulating resin film, the insulating resin film may contain fillers, impurities, etc. For example, the base material 110 may be formed of an insulating resin film containing a filler such as silica or alumina.

[0168] Examples of materials other than resin for the substrate 110 include SiO 2、Crystalline materials such as ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, and perovskite ceramics (CaTiO3, BaTiO3). In addition to the above-mentioned crystalline materials, amorphous glass and the like can also be used as the material of the substrate 110. In addition, as the material of the substrate 110, metals such as aluminum, aluminum alloy (duralumin), and titanium can also be used. When a metal is used, an insulating film is provided on the metal substrate 110.

[0169] The resistor 111 is a thin film formed on the upper side of the substrate 110 in a predetermined pattern. In the strain gauge 11a, the resistor 111 is a sensing part that generates a change in resistance when it is strained. The resistor 111 can be formed directly on the upper surface 110U of the substrate 110 or through other layers ( Fig.17 The functional layer 117 shown in FIG. 1 is formed on the upper surface 110U of the substrate 110. Fig.16 In the figure, for convenience, the resistor 111 is represented by a dark pear-skin pattern.

[0170] The resistor 111 is configured such that a plurality of elongated portions extend in the same direction ( Fig.16 The ends of the adjacent elongated portions are connected alternately, and the whole is folded back into a sawtooth shape. The length direction of the plurality of elongated portions is the grid direction, and the direction perpendicular to the grid direction is the grid width direction (in the example of Fig.16 vertically in the example above).

[0171] In the resistor 111, Fig.16 The left end of the uppermost elongated portion is bent upward to reach one end 122e1 in the grid width direction of the resistor 111. Fig.16 In the embodiment, the left end of the elongated portion located at the lowest side is bent downward to reach the other end 122e2 in the grid direction of the resistor 111. The ends 122e1 and 122e2 are electrically connected to the electrodes 114 and 115 via the wirings 112 and 113, respectively. In other words, the wirings 112 and 113 electrically connect the ends 122e1 and 122e2 in the grid width direction of the resistor 111 to the electrodes 114 and 115, respectively.

[0172] The resistor 111 can be formed of a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 111 can be formed of a material containing at least one of Cr and Ni. As a material containing Cr, for example, a Cr mixed phase film can be cited. As a material containing Ni, for example, Cu-Ni (copper nickel) can be cited. As a material containing both Cr and Ni, for example, Ni-Cr (nickel chromium) can be cited.

[0173] Here, the Cr mixed phase film is a film formed by a mixed phase of Cr, CrN, Cr2N, etc. The Cr mixed phase film may contain inevitable impurities such as chromium oxide.

[0174] The thickness of the resistor 111 is not particularly limited, and may be, for example, approximately 0.05 μm to 2 μm. In particular, when the thickness of the resistor 111 is 0.1 μm or more, the crystallinity of the crystals constituting the resistor 111 (for example, the crystallinity of α-Cr) is improved. In addition, when the thickness of the resistor 111 is 1 μm or less, (i) cracks in the film and (ii) warping of the film from the substrate 110 caused by the internal stress of the film constituting the resistor 111 are reduced.

[0175] Considering the difficulty in generating lateral sensitivity and the countermeasure for disconnection, the width of the resistor 111 is preferably 10 μm to 100 μm. More preferably, the width of the resistor 111 is preferably 10 μm to 70 μm, and more preferably 10 μm to 50 μm.

[0176] For example, in the case where the resistor 111 is a Cr mixed phase film, by using α-Cr (α chromium) of a stable crystalline phase as the main component, the stability of the strain characteristics can be improved. For another example, in the case where the resistor 111 is a Cr mixed phase film, by making the resistor 111 with α-Cr as the main component, the strain rate of the strain gauge 11a can be set to 10 or more, and the strain rate temperature coefficient TCS and the resistance temperature coefficient TCR can be set within the range of -1000ppm / ℃ to +1000ppm / ℃. Here, "main component" means a component that accounts for more than 50% by weight of all the materials constituting the resistor. If it is considered from the perspective of improving the strain characteristics, the resistor 111 preferably contains more than 80% by weight of α-Cr. Further, if it is considered from the same point of view, the resistor 111 more preferably contains more than 90% by weight of α-Cr. It should be noted that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0177] When the resistor 111 is a Cr mixed phase film, the CrN and Cr2N contained in the Cr mixed phase film are preferably 20 wt % or less. By setting the CrN and Cr2N contained in the Cr mixed phase film to 20 wt % or less, the strain rate of the strain gauge 11a can be suppressed from decreasing.

[0178] In addition, the ratio of CrN to Cr2N in the Cr mixed phase film is preferably 80 weight % or more and less than 90 weight % of the ratio of Cr2N to the total weight of CrN and Cr2N. Further, the ratio is more preferably 90 weight % or more and less than 95 weight % of the ratio of Cr2N to the total weight of CrN and Cr2N. Cr2N has semiconductor properties. Therefore, by making the above-mentioned Cr2N ratio 90 weight % or more and less than 95 weight %, the reduction of TCR (negative TCR) is more obvious. Furthermore, by making the above-mentioned Cr2N ratio 90 weight % or more and less than 95 weight %, the ceramicization of the resistor 111 can be reduced. Therefore, the brittle fracture of the resistor 111 can be made less likely to occur.

[0179] On the other hand, CrN also has the advantage of chemical stability. By including more CrN in the Cr mixed phase film, the possibility of generating unstable N can be reduced, so a stable strain gauge can be obtained. Here, "unstable N" refers to a trace amount of N2 or atomic N that may exist in the film of the Cr mixed phase film. Depending on the external environment (such as a high temperature environment), these unstable N may escape from the film. When unstable N escapes from the film, the film stress of the Cr mixed phase film may change.

[0180] The wirings 112 and 113 are provided on the substrate 110. The wirings 112 and 113 are electrically connected to the resistor 111 and the electrodes 114 and 115. The wirings 112 and 113 are not limited to being linear, but may have any pattern. In addition, the wirings 112 and 113 may have any width and any length. Fig.16 In the figure, for convenience, the wirings 112 and 113 are represented by a pear-skin pattern that is lighter than the resistor 111.

[0181] The electrodes 114 and 115 are provided on the substrate 110. The electrodes 114 and 115 are electrically connected to the resistor 111 via the wirings 112 and 113. When viewed from above, the electrodes 114 and 115 are wider than the wirings 112 and 113 and are formed into a roughly rectangular shape. The electrodes 114 and 115 are a pair of electrodes for outputting the change in the resistance value of the resistor 111 caused by strain to the outside. The electrodes 114 and 115 are, for example, joined to a lead wire (not shown) for external connection. A metal layer with low resistance such as copper, or a metal layer with good weldability such as gold, may also be stacked on the upper surface of the electrodes 114 and 115. Although different reference numerals are used for the resistor 111, wirings 112 and 113, and electrodes 114 and 115 for convenience, they may be integrally formed from the same material in the same process. It should be noted that in Fig.16 In FIG. 1 , for convenience, the electrodes 114 and 115 are represented by the same pear-skin pattern as the wirings 112 and 113 .

[0182] The covering layer 116 is provided on the substrate 110 as required. The covering layer 116 is provided on the upper surface 110U of the substrate 110 in such a manner as to cover the resistor 111 and the wirings 112 and 113 and expose the electrodes 114 and 115. As the material of the covering layer 116, for example, insulating resins such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, and composite resins (for example, silicone resin, polyolefin resin) can be cited. It should be noted that the covering layer 116 may also contain fillers and pigments. The thickness of the covering layer 116 may be, for example, about 2 μm to 30 μm. By providing the covering layer 116, mechanical damage to the resistor 111 can be suppressed. In addition, by providing the covering layer 116, the resistor 111 can be protected from moisture and the like.

[0183] In the strain gauge 11a, when the Cr mixed phase film is used as the material of the resistor 111, high sensitivity and miniaturization can be achieved. For example, the output of the conventional strain gauge is about 0.04mV / 2V, but when the Cr mixed phase film is used as the material of the resistor 111, an output of more than 0.3mV / 2V can be obtained. In addition, the size (strain length × strain width) of the conventional strain gauge is about 3mm × 3mm, but when the Cr mixed phase film is used as the material of the resistor 111, the size (strain length × strain width) can be miniaturized to about 0.3mm × 0.3mm.

[0184] Therefore, the strain gauge 11a using the Cr mixed phase film as the material of the resistor 111 can be installed later even in a narrow space of the strain body 12, so it can be suitably used in the pulse wave sensor 10 in the pulse wave measurement device 1 as a wearable device. In addition, the resistance of the strain gauge 11a using the Cr mixed phase film as the material of the resistor 111 is higher than that of the conventional strain gauge. Therefore, when the strain gauge 11a is driven by a battery as the storage battery 16, since low power consumption can be achieved, the battery life can be extended, and the pulse wave of the measured person can be measured for a longer period of time or repeatedly.

[0185] The top view shape of the functional layer 117 can be patterned to be substantially the same as the top view shape of the resistor 111, wirings 112, 113, and electrodes 114, 115, for example. Fig.17 In the structure, by providing the functional layer 117 under the metal layer on which the wiring and other components are formed, the crystal growth of the metal layer can be promoted, so that the metal layer composed of a stable crystal phase can be produced. As a result, the stability of the strain characteristic of the strain gauge 11a is improved. Alternatively, since the material constituting the functional layer diffuses into the metal layer, the measurement characteristic of the strain gauge 11a is improved.

[0186] (Other stacked structures of strain gauges)

[0187] It should be noted that although Fig.17 The cross-sectional shape is shown when the functional layer 117 is provided as a base layer for the resistor 111 , the wirings 112 , 113 , and the electrodes 114 , 115 , but the functional layer 117 may not be provided.

[0188] <Implementation method 2>

[0189] In the above-described structure, the pulse wave measurement device adjusts the pressing force of the pulse wave sensor on the skin by adjusting the length of the belt portion 80 , but the pressing force may be adjusted by other structures.

[0190] use Fig.18 A modified example of the pulse wave measurement device will be described. Fig.18 1A is a cross-sectional view of the head H of the pulse wave measurement device according to the second embodiment.

[0191] like Fig.18 As shown, the head H of the pulse wave measurement device 1A according to this modification includes, for example, a pulse wave sensor 10, a box-shaped sensor fixing portion 201, belt fixing portions 301 and 302, and a force adjustment mechanism 60. The pulse wave sensor 10 has the same configuration as that of the first embodiment.

[0192] The sensor fixing portion 201 serves as a pressing member that fixes the side surface and the upper surface of the pulse wave sensor 10 and receives the pressing force from the force adjustment mechanism 60 to press the pulse wave sensor 10 to the wrist side of the user.

[0193] The force adjustment mechanism 60 is an adjustment part, and includes an upper surface lifting plate 61, a toroidal cylindrical support plate 62, and a spring 63. The spring 63 is, for example, a coil spring, and is fixed to the upper surface of the sensor fixing part 201. By lifting and lowering the upper surface lifting plate 61 relative to the support plate 62, the force adjustment mechanism 60 can adjust the force of the spring 63 that pushes the pulse wave sensor 10 in the N direction via the sensor fixing part 201.

[0194] As an example of the force adjustment mechanism 60, the support plate 62 is provided with a sawtooth-shaped engaging protrusion extending in the up-down direction, and the upper surface lifting plate 61 is lowered by the amount of pressing as the subject pushes in, and stops at this position. Therefore, the force of the spring 63 on the sensor fixing part 201 changes according to the amount of pushing in. Alternatively, the upper surface lifting plate 61 is threadedly engaged with the support plate 62, and the subject can change the force by rotating the upper surface lifting plate 61 relative to the support plate 62 to lower the upper surface lifting plate 61 by the amount of rotation, and stop at this position.

[0195] Thus, in this embodiment, the pressure applied by the spring 63 to the subject side can be changed by changing the height of the upper surface lifting plate 61. Therefore, an appropriate pressure can be applied to the radial artery of the subject. As a result, the pulse wave measurement device 1A allows the subject and the pulse wave sensor 10 to have good adhesion, and can improve the measurement accuracy of the pulse wave.

[0196] In this embodiment, when the pulse wave measurement device 1A is worn, the output signal level of the notification sensor reaches a critical point or more, and the pressure is controlled by the force adjustment mechanism 60, so that the pulse wave can be measured under the same conditions each time. In this way, the deviation of the measured value caused by the pressure difference is suppressed, and the analysis accuracy of the acceleration pulse wave and the blood sugar level can be improved.

[0197] <Implementation method 3>

[0198] Fig.19 This is an overall block diagram of a pulse wave measurement device 1B according to the third embodiment.

[0199] In the first embodiment, the information processing device performs the calculation function such as comparison, but the pulse wave measurement device 1B may perform the calculation and instruct the adjustment. In this case, the pulse wave measurement device can perform the calculation function internally, so it is not necessary to communicate with the information processing device.

[0200] In this example, the control unit 14B of the pulse wave measurement device 1B can execute the average value calculation unit 141 within a predetermined period, the comparison unit 142, the zero point adjustment unit 143, the acceleration pulse wave calculation unit 144, the measurement timing notification unit 145, the acceleration pulse wave analysis unit 146, etc. In addition, the control substrate 17B is provided with a storage unit 18 and a notification unit 19. The notification unit 19 is composed of, for example, a sound output unit, a display unit, or a light emitting component, and also serves as an adjustment instruction unit for instructing pressure adjustment.

[0201] In the present embodiment, the voltage level of the digital signal outputted as the measured pulse wave inside the pulse wave measurement device 1B is compared with a preset range with respect to the maximum voltage level of the output section, and when the voltage level of the digital signal is lower than the range, the notification section 19 instructs to adjust the pressing force applied to the pulse wave sensor 10. Then, the user adjusts the length of the belt section 80 or the position of the upper surface lifting plate 61 of the force adjustment mechanism 60.

[0202] Therefore, even if there is a difference in pressing pressure due to the different arm thicknesses of each subject, the time required for adjustment can be shortened and the pressing pressure can be adjusted to an appropriate level, thereby reducing errors.

[0203] It should be noted that although Fig.19 The structure in which all the operation functions are arranged on the pulse wave measurement device 1B side and are completed by the pulse wave measurement device 1B alone is shown, but this structure may be a structure capable of communicating with an information processing device and may be arranged on the information processing device side. Fig.19 Some functions of the control unit 14B in the apparatus, such as the functions of the acceleration pulse wave calculation unit 144 and the acceleration pulse wave analysis unit 146 having a large processing amount.

[0204] <Implementation method 4>

[0205] Fig. 20 1C is an overall block diagram of a pulse wave measurement device 1C according to Embodiment 4. In this embodiment, the pulse wave measurement device 1C has an automatic adjustment unit 29 and has an automatic adjustment function. Therefore, calculations are performed and adjustments are made inside the control unit 14C of the pulse wave measurement device 1C. This embodiment is based on automatic adjustment, so it is preferable to be able to use Fig.18 The force adjustment mechanism 60 shown is a structure for adjusting pressure.

[0206] In the present embodiment, the voltage level of the digital signal output as the measured pulse wave in the pulse wave measurement device 1C is compared with a preset range with respect to the maximum voltage level of the output unit α, and when the voltage level of the digital signal is smaller than the range, the pressing force applied to the pulse wave sensor 10 is automatically adjusted. For example, as the automatic adjustment, the upper surface lifting plate 61 is automatically raised and lowered to automatically adjust the pressure.

[0207] Therefore, even if there is a difference in pressing pressure due to the different arm thicknesses of each subject, the time required for adjustment can be shortened and the pressing pressure can be adjusted to an appropriate level, thereby reducing errors.

[0208] As mentioned above, although the preferred embodiments and the like have been described in detail, the present invention is not limited to the above-mentioned embodiments and the like, and various modifications and substitutions can be made to the above-mentioned embodiments and the like without departing from the scope described in the claims.

[0209] This international application claims priority based on Japanese Patent Application No. 2022-106687 filed on June 30, 2022, and all the contents of No. 2022-106687 are incorporated into this international application.

[0210] Description of Reference Numerals

[0211] 1, 1A, 1B, 1C pulse wave measuring device; 5 information processing device; 10 pulse wave sensor; 11a, 11b, 11c, 11d strain gauge; 12 strain body; 13 AFE; 20, 201 sensor fixing part (pressing part); 60 force adjustment mechanism (adjustment part); 80 belt part (adjustment part); 131 bridge circuit; 132 amplifier circuit; 133 A / D conversion circuit (A / D conversion unit); 1000 pulse wave measurement system; α output unit.

Claims

1. A method for adjusting a pulse wave measuring device, wherein the pulse wave measuring device can be worn on a user's wrist, wherein: The pulse wave measuring device comprises: A pulse wave sensor having a strain gauge for acquiring a pulse wave by measuring a pulse of a radial artery; a pressing member that presses the pulse wave sensor toward the radial artery; and an output unit that outputs the measurement value of the pulse wave sensor as a digital signal, The adjustment method comprises the following steps: When the pulse wave measuring device is worn on the wrist of a user, the pulse wave is acquired through the pulse wave sensor, and the acquired measurement value is output as a digital signal; comparing the voltage level of the digital signal with a predetermined range relative to the maximum output level of the output unit; and When the voltage level of the digital signal is outside the preset range, the pressing force applied to the pulse wave sensor is adjusted or instructed.

2. The method for adjusting the pulse wave measurement device according to claim 1, wherein: The predetermined range of the voltage levels compared in the comparing step is equal to or greater than 35% of a maximum output level of the output unit.

3. The method for adjusting the pulse wave measurement device according to claim 1, wherein: The voltage level of the digital signal compared in the comparing step is an average voltage of an arbitrary period of the digital signal.

4. The method for adjusting the pulse wave measurement device according to claim 1, wherein: The adjustment method comprises the following steps: When the pulse wave measurement device is worn on the wrist of the user for the first time, before the step of comparing, as a first adjustment, a zero-point correction is performed on the digital signal acquired by the pulse wave sensor.

5. A pulse wave measurement system comprising a pulse wave measurement device that can be worn on a user's wrist and an information processing device that can communicate with the pulse wave measurement device, wherein: The pulse wave measuring device comprises: a pulse wave sensor having a strain gauge for acquiring a pulse wave of a radial artery when the pulse wave measuring device is worn on a wrist of a user; an output unit that outputs the measurement value of the pulse wave sensor as a digital signal; a pressing member that presses the pulse wave sensor toward the radial artery; and an adjustment unit that adjusts the pressing force applied to the pulse wave sensor, The information processing device comprises: a comparing unit that compares the voltage level of the digital signal with a preset range relative to a maximum output level of the output unit; and The adjustment instruction unit instructs adjustment of the pressing force applied to the pulse wave sensor when the voltage level of the digital signal is outside the preset range.

6. The pulse wave measurement system according to claim 5, wherein: The pulse wave measuring device has a belt portion for wearing, which is used to be worn on the wrist of the user and is wrapped around the outer side of the pulse wave sensor. The pulse wave sensor includes a strain body that contacts a wrist of a user, and the strain gauge is disposed on the strain body. The pressing member is a sensor fixing portion that holds the pulse wave sensor from a side opposite to the strain body. The adjustment portion is the belt portion, and the biasing force of the pressing member can be adjusted by adjusting the belt length of the belt portion.

7. The pulse wave measurement system according to claim 5, wherein: The pulse wave sensor includes a strain body that contacts a wrist of a user, and the strain gauge is disposed on the strain body. The pressing member is a sensor fixing portion that holds the pulse wave sensor from a side of the pulse wave sensor opposite to the strain body. The adjustment part is a force adjustment mechanism that contacts the sensor fixing part from a side of the sensor fixing part opposite to the pulse wave sensor and applies force to the sensor fixing part toward a wrist side of the user.

8. The pulse wave measurement system according to claim 5, wherein: The pulse wave sensor of the pulse wave measuring device outputs an analog signal, The output section has an amplifier circuit and an A / D conversion unit.

9. The pulse wave measurement system according to claim 5, wherein: The information processing device performs second-order differentiation on the digital signal as the measured value of the pulse wave after the pressing force is adjusted, thereby calculating an accelerated pulse wave.

10. The pulse wave measurement system according to claim 5, wherein: The pulse wave sensor includes a strain body on which the strain gauge is mounted. The pulse wave is detected based on a change in the resistance value of the strain gauge caused by the deformation of the strain body.

11. The pulse wave measurement system according to claim 10, wherein: The strain gauge includes a strain gauge having a resistor body formed of a film containing Cr, CrN, and Cr2N.

12. The pulse wave measurement system according to claim 5, wherein: The pulse wave measurement device further includes a position detection unit that detects a position of the pulse wave sensor relative to the tibial artery.

13. A pulse wave measuring device, which can be worn on a user's wrist and comprises: a pulse wave sensor having a strain gauge, which acquires the pulse wave of the radial artery when the pulse wave measuring device is worn on the wrist of the user; an output unit that outputs the measurement value of the pulse wave sensor as a digital signal; a comparing unit that compares the voltage level of the digital signal with a preset range relative to the maximum output level of the output unit; A pressing component that presses the pulse wave sensor toward the radial artery; as well as An adjustment unit adjusts the pressing force applied to the pulse wave sensor when the voltage level of the digital signal is outside the preset range.

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