WO2022050368A1

WO2022050368A1 - Pulse wave signal acquisition device

Info

Publication number: WO2022050368A1
Application number: PCT/JP2021/032377
Authority: WO
Inventors: 央大加藤; 仁大久保
Original assignee: 興和株式会社
Priority date: 2020-09-04
Filing date: 2021-09-03
Publication date: 2022-03-10
Also published as: JPWO2022050368A1

Abstract

The present invention provides a technology for enabling shortening of the time required to acquire a pulse wave signal that is suitable for measuring the concentration of a blood component. This pulse wave signal acquisition device comprises: at least one light-emitting element which irradiates a measurement site of a living body with light; a light-receiving element which receives the light that has passed through the measurement site; an amplification unit which includes at least one amplifier having a fixed amplification factor and which generates a plurality of amplified signals having different amplification factors by amplifying an output signal from the light-receiving element at the fixed amplification factors of the respective amplifiers; and a determination unit which determines one of the amplified signals as a pulse wave signal.

Description

Pulse wave signal acquisition device

The present invention relates to a pulse wave signal acquisition device.

There is known a technique of irradiating a measurement site of a living body with light, acquiring a pulse wave signal based on the light received from the measurement site, and measuring the concentration of a blood component from the pulse wave signal. Patent Document 1 describes that a living body is irradiated with light from a light emitting element, a transmitted light amount measurement value is detected by measuring the light transmitted through the living body with a photodetection element, and a pulse wave component is extracted from the transmitted light amount measurement value. Discloses a blood component measuring device that detects a pulse wave measurement value. This blood component measuring device measures the blood oxygen saturation concentration of arterial blood using the pulse wave measurement value. Further, Patent Document 2 discloses a biological information measuring device that irradiates a finger with light, receives the reflected light, and detects a signal corresponding to the light receiving level as a pulse wave signal. This biological information measuring device applies arithmetic processing to the pulse wave signal to measure biological information such as oxygen saturation concentration in blood.

Japanese Patent No. 3858678 Japanese Unexamined Patent Publication No. 2006-06173

Since the amplitude of the pulse wave signal is very small, it is preferable to amplify the pulse wave signal when analyzing the pulse wave signal to measure the concentration of blood components. For example, the blood component measuring device disclosed in Patent Document 1 amplifies the pulse wave measurement value by a variable amplifier circuit and uses it for calculating the oxygen saturation concentration in blood. Further, the biometric information measuring device disclosed in Patent Document 2 adjusts the amplification factor of the amplifier circuit based on the sampling data from which noise is excluded, and performs arithmetic processing on the pulse wave signal amplified by the amplifier circuit. However, when amplifying the pulse wave signal using a variable amplifier, adjustment processing for determining the optimum amplification factor is required prior to this measurement, and a pulse wave signal suitable for measuring the concentration of blood components is acquired. There is a problem that it becomes complicated and a long adjustment time is required.

In view of the above circumstances, the present disclosure aims to provide a technique capable of shortening the time for acquiring a pulse wave signal suitable for measuring the concentration of blood components.

The pulse wave signal acquisition device disclosed in the present disclosure includes at least one light emitting element that irradiates a measurement site of a living body with light, a light receiving element that receives light that has passed through the measurement site, and an amplifier having a fixed amplification factor. An amplification unit that includes one and generates a plurality of amplification signals having different amplification factors by amplifying an output signal from the light receiving element at each fixed amplification factor of each amplifier, and amplification of one of the plurality of amplification signals. It has a determination unit that determines a signal as a pulse wave signal. Since the pulse wave signal acquisition device disclosed in the present disclosure determines one of a plurality of amplified signals generated almost simultaneously by the amplification unit as a pulse wave signal, it takes time to acquire a pulse wave signal suitable for measuring the concentration of blood components. Can be shortened.

Further, the pulse wave signal acquisition device includes a plurality of the light emitting elements, the plurality of the light emitting elements emit light having different wavelengths, and irradiate the light in a predetermined order. The one amplification signal may be determined for each output signal from the light receiving element based on the irradiation of light from each light emitting element.

Further, in the pulse wave signal acquisition device, the determination unit detects the signal strength of the amplified signal of one of the plurality of amplified signals, and the signal strength of the other amplified signal is used from the signal strength of the one amplified signal. May be estimated.

Further, in the pulse wave signal acquisition device, the determination unit may detect each signal strength of the plurality of amplified signals.

Further, in the pulse wave signal acquisition device, the determination unit preferentially detects the signal strength of one amplified signal designated in advance among the plurality of amplified signals, and the signal strength of the one amplified signal is determined. If it is within a predetermined allowable range, the one amplified signal may be determined as a pulse wave signal.

Further, the pulse wave signal acquisition device further has an adjusting unit for adjusting the light emitting amount of the light emitting element, and the determining unit selects one combination from the combination of the light emitting amount and the amplification factor. , The amplified signal at the amplification factor in the one combination may be determined as the pulse wave signal.

According to the technology disclosed in the present case, it is possible to shorten the time for acquiring a pulse wave signal suitable for measuring the concentration of blood components.

It is a figure which shows an example of the structure of the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a figure which shows typically the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a figure which shows a part of the pulse wave signal acquisition apparatus which concerns on one Embodiment schematically. It is a figure which shows a part of the pulse wave signal acquisition apparatus which concerns on one Embodiment schematically. It is a circuit diagram of the irradiation part side of the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a circuit diagram of the light receiving part side of the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a graph explaining the signal strength which can be acquired by the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a flowchart about blood component measurement processing using the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a flowchart regarding the measurement preparation process executed by the pulse wave signal acquisition apparatus which concerns on one Embodiment. It is a flowchart regarding the measurement preparation process executed by the pulse wave signal acquisition apparatus which concerns on the modification of one Embodiment (the 1). It is a flowchart regarding the measurement preparation process executed by the pulse wave signal acquisition apparatus which concerns on the modification of one Embodiment (the 2).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configurations of the following embodiments are examples, and the present invention is not limited to the configurations of these embodiments.

First, the pulse wave signal acquisition device according to this embodiment will be described. The pulse wave signal acquisition device 1 according to the present embodiment irradiates a measurement site, which is a part of the body of a living body including blood, with near-infrared light by a Light-Emitting Diode (LED) to collect blood in the measurement site. The passed near-infrared light is received by a Photodiode (PD) to acquire the received light data. Since the living body is not transparent with the exception of the eyeball, almost no light is transmitted. However, for example, the light that has penetrated into the inside of a human finger is scattered by tissues, blood, etc., and a small part of the penetrated light reaches the PD and is detected. Of the detected light intensities, the component that fluctuates periodically is the pulse wave signal detected by the received data of the light that has passed through the blood.

Here, a human being can be mentioned as a living body to be measured by the pulse wave signal acquisition device 1. When the measurement target is a human, the measurement site may be a site where pulsation can be easily detected by near-infrared light, and the finger, palm, wrist, inside of elbow, back of knee, sole of foot, and foot. Fingers, ear flaps, anterior sides of the ears, lips, grooves, neck, etc. are preferable, and thumbs, index fingers, and middle fingers that can clearly detect pulsation are more preferable. In the following, the organism to be measured will be referred to as a human, and the measurement site will be referred to as a thumb. The organism to be measured and the measurement site are not limited to these.

FIG. 1 is a diagram showing a schematic configuration of a pulse wave signal acquisition device 1 according to the present embodiment. As shown in FIG. 1, the pulse wave signal acquisition device 1 includes a control unit 10, a storage unit 20, an irradiation unit 30, a light receiving unit 40, an amplification unit 50, and a communication unit 60.

The control unit 10 includes a Central Processing Unit (CPU) and controls each unit in the pulse wave signal acquisition device 1. The storage unit 20 includes a non-volatile memory such as a flash memory and an electrically Erasable Programmable Read-Only Memory (EEPROM), and a Random Access Memory (RAM). The storage unit 20 stores the control program in the pulse wave signal acquisition device 1 and the data obtained when various processes are executed. In the control unit 10, each functional unit of the determination unit 11 and the adjustment unit 12 is realized by the CPU executing the program stored in the storage unit 20. The determination unit 11 determines the amplification signal of one of the plurality of amplification signals as a pulse wave signal. The adjusting unit 12 adjusts the amount of light emitted from each LED of the irradiation unit 30.

The irradiation unit 30 irradiates the measurement site of the living body with near-infrared light. In the present embodiment, the blood TG value and the HbA1c value are measured by irradiating the thumb of a human being to be measured with near-infrared light by the irradiation unit 30.

The intensity of light that has passed through blood in the blood vessels of human fingers fluctuates periodically due to the pulsation of blood. In the present embodiment, blood is measured by non-invasively measuring the absorbance of blood at a plurality of wavelengths by using a pulse wave signal which is a time-dependent change in light intensity passing through blood in a blood vessel of a human thumb. The value of Triglyceride in blood (hereinafter referred to as "blood TG value") and the ratio of glycated hemoglobin to the total hemoglobin concentration contained in blood as a percentage (hereinafter referred to as "HbA1c value"). To measure).

When the concentration of blood TG value increases and the turbidity of blood increases, the absorbance in near-infrared light near the wavelength of 1050 nm increases. In this embodiment, the blood TG value is measured using the absorbance of blood at a wavelength of 1050 nm, the absorbance of blood at a wavelength of 1300 nm, and the absorbance of blood at a wavelength of 1200 nm.

Further, it has been found by the inventors of the present invention that the absorbance in the vicinity of a wavelength of 1450 nm to 1600 nm changes significantly as compared with other wavelengths, depending on the HbA1c value. Further, since the absorbance in the vicinity of the wavelength of 900 nm to 1300 nm changes depending on the total hemoglobin concentration in the blood, in the present embodiment, the absorbance of the blood at the wavelength of 1450 nm, the absorbance of the blood at the wavelength of 1600 nm, and the absorbance of the blood at the wavelength of 1050 nm. The HbA1c value is measured using.

The irradiation unit 30 of the pulse wave signal acquisition device 1 according to the present embodiment irradiates a human finger with near-infrared light of the above wavelength in order to non-invasively measure the blood TG value and the HbA1c value. It has a light emitting element. Specifically, the irradiation unit 30 includes an LED having a peak wavelength of 1050 nm, an LED having a peak wavelength of 1200 nm, an LED having a peak wavelength of 1300 nm, an LED having a peak wavelength of 1450 nm, and an LED having a peak wavelength of 1600 nm. Have. The details of these LEDs and the details of the method for measuring the blood TG value and the HbA1c value will be described later.

The light receiving unit 40 receives light that has passed through blood at the measurement site. The near-infrared light irradiated by the irradiation unit 30 passes through the blood contained in the measurement site of the living body and is received by the light receiving unit 40. The light receiving unit 40 has a PD (photodiode), detects light that has passed through blood by the PD, and outputs the intensity as a voltage signal. Further, the pulse wave signal acquisition device 1 has an AD (Analog Digital) converter (not shown), and after AD conversion of the output signal as the received light data from the PD of the light receiving unit 40, the control unit 10 is used. Output. The control unit 10 stores the received light data in the storage unit 20. The positional relationship between the irradiation unit 30 and the light receiving unit 40 will be described later.

The amplification unit 50 includes a plurality of amplifiers having a fixed amplification factor, amplifies the output signal of the PD at each fixed amplification factor, and generates a plurality of amplification signals having different amplification factors. The details of the amplification unit 50 will be described later.

The communication unit 60 wirelessly communicates with the terminal device 100 owned by the user by known short-range wireless communication such as Bluetooth (registered trademark), Bluetooth Low Energy (BLE), Wi-Fi, etc., and transmits various data to the terminal device 100. can do.

Examples of the terminal device 100 include smartphones, feature phones, tablet-type personal computers, notebook-type personal computers, desktop-type personal computers, and various other electronic devices. The terminal device 100 is composed of a liquid crystal display device, an organic EL display device, and the like, and includes a display unit 100A that displays a blood TG value and an HbA1c value as measured values. Further, the terminal device 100 stores a blood component measurement program and various data for executing various processes (see FIGS. 8 to 11) in the blood component measurement described below. In the present embodiment, the terminal device 100 calculates the blood TG value and the HbA1c value based on the pulse wave signal obtained by the pulse wave signal acquisition device 1.

Next, a configuration example of the pulse wave signal acquisition device 1 according to the present embodiment will be described in more detail with reference to FIG. FIG. 2 is an external perspective view of the pulse wave signal acquisition device 1. The pulse wave signal acquisition device 1 includes a housing 61 and an upper cover 62 that covers the upper part of the housing 61. Further, in the pulse wave signal acquisition device 1, an opening 63 for inserting the finger of the subject to be measured is provided between the housing 61 and the upper cover 62. When the subject inserts a finger into the opening 63, the irradiation unit 30 and the light receiving unit 40 are provided on the contact surface 61a that comes into contact with the finger in the housing 61.

FIG. 3 is a diagram schematically showing a state in which the subject inserts the thumb 101 into the opening 63 in the pulse wave signal acquisition device 1 shown in FIG. In the pulse wave signal acquisition device 1 according to the present embodiment, the irradiation unit 30 irradiates the ventral side of the thumb 101 with light, and the light that has passed through the blood is received by the light receiving unit 40 arranged on the ventral side of the finger. A reflected light method that receives light is adopted.

FIG. 4 is a plan view showing a contact surface 61a in which the irradiation unit 30 and the light receiving unit 40 are arranged in the pulse wave signal acquisition device 1. The irradiation unit 30 has a first LED 31, a second LED 32, a third LED 33, a fourth LED 34, and a fifth LED 35. The first LED 31 irradiates light having a peak wavelength at a wavelength of 1050 nm. The second LED 32 irradiates light having a peak wavelength at a wavelength of 1200 nm. The third LED 33 irradiates light having a peak wavelength at a wavelength of 1300 nm. The fourth LED 34 irradiates light having a peak wavelength at a wavelength of 1450 nm. The fifth LED 35 irradiates light having a peak wavelength at a wavelength of 1600 nm.

Further, the light receiving unit 40 has a PD 41 (an example of a "light receiving element"). The PD 41 receives light that is irradiated from the irradiation unit 30 to the finger and has passed through the blood. The PD 41 receives light and outputs a voltage signal as light receiving data. Hereinafter, the voltage signal output by the PD 41 may be referred to as an “output signal”.

FIG. 5 is a circuit diagram of the irradiation unit 30 side of the pulse wave signal acquisition device 1 according to the present embodiment. The pulse wave signal acquisition device 1 includes a microcomputer 70 that constitutes a control unit 10 and a storage unit 20. The microcomputer 70 is operated by being supplied with electric power by a power source (for example, a secondary battery) (not shown) included in the pulse wave signal acquisition device 1.

As shown in FIG. 5, each anode terminal of the first LED 31, the second LED 32, the third LED 33, the fourth LED 34, and the fifth LED 35 (hereinafter, may be abbreviated as "the first LED 31 to the fifth LED 35") has a DC voltage of 3.3 V. It is connected to a power supply circuit (not shown) to be applied, and their cathode terminals are connected to each collector terminal of transistors 71 to 75 (NPN type) via a resistor (50 to 150Ω). Each emitter terminal of the transistors 71 to 75 is connected to the ground. Further, any base terminal of the transistors 71 to 75 is connected to the microcomputer 70 via a resistor. When the microcomputer 70 applies a voltage to each base terminal of the transistors 71 to 75 according to the light irradiation timing by the first LED 31 to the fifth LED 35, a DC voltage of 3.3 V is applied to each LED. As a result, the pulse wave signal acquisition device 1 can execute light irradiation by the first LED 31, the second LED 32, the third LED 33, the fourth LED 34, and the fifth LED 35 at a predetermined timing. The control program for executing this control is stored in the storage unit (storage unit 20 shown in FIG. 1) of the microcomputer 70.

The pulse wave signal acquisition device 1 according to the present embodiment has one cycle by irradiating light having different wavelengths in the order of the fifth LED35, the fourth LED34, the third LED33, the second LED32, and the first LED31 within a predetermined time (100 milliseconds). Acquires the received light data for the minute.

FIG. 6 is a circuit diagram of the light receiving unit 40 side of the pulse wave signal acquisition device 1 according to the present embodiment. As shown in FIG. 6, one end side (output terminal) of the PD 41 of the light receiving unit 40 is connected to the amplification unit 50, and the other end side of the PD 41 is connected (grounded) to the ground. Further, the output terminal of the PD 41 is connected to the collector terminal of the transistor 76 (NPN type). The emitter terminal of the transistor 76 is connected to the ground, and the base terminal thereof is connected to the microcomputer 70. The transistor 76 is an example of a switching element that switches between a connected state in which the output terminal of the PD 41 is connected to the ground and a non-connected state in which the output terminal of the PD 41 is disconnected from the ground. The transistor 76 connects the output terminal of the PD 41 to the ground after the light irradiation by the first LED 31 in a certain cycle, and disconnects the output terminal of the PD 41 from the ground before the light irradiation by the fifth LED 35 in the next cycle of the certain cycle. The switching control of the transistor 76 is executed by the microcomputer 70. The control program for executing this control is stored in the storage unit (storage unit 20 shown in FIG. 1) of the microcomputer 70. Unlike the present embodiment, the pulse wave signal acquisition device 1 may not be provided with the transistor 76, and may not be provided with a circuit that allows the output terminal of the PD 41 to be grounded via the transistor 76.

Further, the output terminal of the PD 41 is connected to the current-voltage conversion unit 45. The current-voltage conversion unit 45 includes an operational amplifier 45A, a resistor 45B, and a capacitor 45C. The inverting input terminal of the operational amplifier 45A is connected to the output terminal of the PD 41. Further, a resistor 45B and a capacitor 45C (R = 680 kΩ, C = 3nF) are connected in parallel to the inverting input terminal and the output terminal of the operational amplifier 45A. The non-inverting input terminal of the operational amplifier 45A is connected (grounded) to the ground. The current-voltage conversion unit 45 forms an inverting amplifier circuit with an operational amplifier 45A and a resistor 45B. Further, the current-voltage conversion unit 45 has a fixed amplification factor. The resistor 45B is a feedback resistor, and the amplification factor of the current-voltage conversion unit 45 is determined by the resistance value of the resistor 45B. Further, a low-pass filter circuit is formed by connecting the resistor 45B and the capacitor 45C in parallel. The current-voltage conversion unit 45 converts the current input from the output terminal of the PD 41 into a voltage and outputs it as an output signal of the PD 41.

Further, the pulse wave signal acquisition device 1 according to the present embodiment includes an amplification unit 50 connected to the output side of the current-voltage conversion unit 45. The amplification unit 50 includes a first amplifier 51, a second amplifier 52, and a third amplifier 53 (hereinafter, may be abbreviated as “first amplifier 51 to third amplifier 53”). The first amplifier 51, the second amplifier 52, and the third amplifier 53 are composed of a non-inverting amplifier circuit composed of an operational amplifier, an input resistance resistor, and a feedback resistance resistor. In FIG. 6, among the non-inverting amplifier circuits constituting the first amplifier 51, the second amplifier 52, and the third amplifier 53, the input resistance and feedback resistance resistors are not shown, and only the operational amplifier is shown. Each of the first amplifier 51, the second amplifier 52, and the third amplifier 53 has a fixed amplification factor. Each fixed amplification factor of these amplifiers is determined by the constant ratio of the resistance values of the input resistance and the feedback resistance.

The first amplifier 51 to the third amplifier 53 are connected in series. The microcomputer 70 amplifies the output signal of the PD 41 output from the current-voltage conversion unit 45 and the output signal obtained by amplifying the output signal of the PD 41 by the first amplifier 51 to the third amplifier 53 of the amplification unit 50. It is input as a signal. In the present specification, the term "amplified signal" is amplified not only by the three signals obtained by amplifying the output signal of the PD 41 by the first amplifier 51 to the third amplifier 53, but also by the first amplifier 51. The output signal itself of the previous PD41 is also included. That is, the output signal of the PD 41 output from the current-voltage conversion unit 45 is also an example of an amplified signal having an amplification factor of 1.0 times. The output side of the current-voltage conversion unit 45 is connected to the input side of the first amplifier 51 and the signal acquisition pin A3 of the microcomputer 70. An amplified signal having an amplification factor of 1.0 times converted into a voltage by the current-voltage conversion unit 45 is input to the signal acquisition pin A3. The output side of the first amplifier 51 is connected to the signal acquisition pin A2 of the microcomputer 70 and the input side of the second amplifier 52. The amplified signal amplified by the first amplifier 51 is input to the signal acquisition pin A2. The output side of the second amplifier 52 is connected to the signal acquisition pin A1 of the microcomputer 70 and the input side of the third amplifier 53. The amplified signal amplified by the first amplifier 51 and the second amplifier 52 is input to the signal acquisition pin A1. The output side of the third amplifier 53 is connected to the signal acquisition pin A0 of the microcomputer 70. The amplified signal amplified by the first amplifier 51 to the third amplifier 53 is input to the signal acquisition pin A0. As described above, the amplification unit 50 includes the first amplifier 51 to the third amplifier 53, and generates four amplification signals having different amplification factors from the output signal of the PD 41. Each of these four amplified signals is input to the signal acquisition pins A3 to A0 of the microcomputer 70. In the present embodiment, the first amplifier 51 has a fixed amplification factor of 1.2 times, the second amplifier 52 has a fixed amplification factor of 5.0 times, and the third amplifier 53 has a fixed amplification factor of 3.0 times. Has a fixed amplification factor of. Therefore, an amplified signal amplified 1.2 times is input to the signal acquisition pin A2, an amplified signal amplified 6.0 times is input to the signal acquisition pin A1, and 18 is input to the signal acquisition pin A0. Amplified signal amplified by 0.0 times is input.

The pulse wave signal acquisition device 1 according to the present embodiment can change the acquireable signal intensity by adjusting the amount of light emitted from the first LED 31 to the fifth LED 35 by PWM control (pulse width modulation). FIG. 7 is a graph illustrating the signal strength that can be acquired by the pulse wave signal acquisition device 1. The horizontal axis of FIG. 7 represents the set value of the amplification factor of the amplification unit 50, the vertical axis of FIG. 7 represents the strength of the signal strength to be acquired (arbitrary unit), and the line L is acquired with respect to the set value of the amplification factor. It represents the signal strength that can be achieved. The point P1 in the line L represents a point where the amplification factor input to the signal acquisition pin A3 is 1.0 times. By adjusting the amount of light emitted from the first LED 31 to the fifth LED 35 by PWM control, the signal strength in the range R1 can be obtained from the amplified signal having an amplification factor of 1.0 times. Further, the point P2 in the line L represents a point where the amplification factor input to the signal acquisition pin A2 is 1.2 times. By adjusting the amount of light emitted from the first LED 31 to the fifth LED 35 by PWM control, the signal strength in the range R2 can be obtained from the amplified signal having an amplification factor of 1.2 times. The point P3 in the line L represents a point where the amplification factor input to the signal acquisition pin A1 is 6.0 times. By adjusting the amount of light emitted from the first LED 31 to the fifth LED 35 by PWM control, the signal strength in the range R3 can be obtained from the amplified signal having an amplification factor of 6.0 times. The point P4 in the line L represents a point where the amplification factor input to the signal acquisition pin A0 is 18.0 times. By adjusting the amount of light emitted from the first LED 31 to the fifth LED 35 by PWM control, the signal strength in the range R4 can be obtained from the amplified signal having an amplification factor of 18.0 times. As described above, the pulse wave signal acquisition device 1 can be acquired by combining the first amplifier 51 to the third amplifier 53 having fixed amplification factors and the adjustment of the light emission amount of the first LED 31 to the fifth LED 35 by PWM control. The signal strength can be changed linearly, and signals of any strength can be obtained.

Next, the blood component measurement process executed by the pulse wave signal acquisition device 1 and the terminal device 100 according to the present embodiment will be described. Prior to the measurement process, the subject presses his / her fingertip against a predetermined position of the pulse wave signal acquisition device 1. FIG. 8 is a flowchart relating to the blood component measurement process.

First, the pulse wave signal acquisition device 1 executes the measurement preparation process (OP101). Here, the measurement preparation process executed by the pulse wave signal acquisition device 1 according to the present embodiment will be described. FIG. 9 is a flowchart relating to the measurement preparation process executed by the pulse wave signal acquisition device 1. In the measurement preparation process, the pulse wave signal acquisition device 1 sequentially executes the processes of OP301 to OP308 for the five LEDs of the first LED31 to the fifth LED35, and determines the amplification factor and the amount of light emitted from the LEDs to obtain an appropriate pulse wave signal. It is determined for each LED, and the amplified signal at the amplification factor is determined as a pulse wave signal.

First, in OP301, the control unit 10 of the pulse wave signal acquisition device 1 causes the five LEDs of the first LED 31 to the fifth LED 35 to emit light in order within 100 milliseconds. Specifically, the control unit 10 causes the five LEDs to emit light in the order of the fifth LED35, the fourth LED34, the third LED33, the second LED32, and the first LED31. The light emission time of each LED may be different from each other or may be the same. At this time, the control unit 10 controls each LED to emit light at a duty ratio of a predetermined applied voltage.

In the next OP 302, the control unit 10 acquires the amplified signal of the PD 41 from one of the signal acquisition pins A3 to A0. Which signal acquisition pin the signal is acquired from is specified in advance for each of the LEDs of the first LED 31 to the fifth LED 35.

In the next OP 303, the control unit 10 continues to calculate (update) the average value of the amplified signal acquired by the OP 302 while the first LED 31 to the fifth LED 35 irradiate the light, and the average value for 5 seconds is accumulated. At that point, the process shifts to OP304 processing. In OP303, the average value of the calculated amplified signal is not limited to the signal for 5 seconds, and may be a signal for less than 5 seconds or a signal longer than 5 seconds.

Next, in OP304, the determination unit 11 of the control unit 10 determines whether or not the signal strength (average value for 5 seconds) of one acquired amplified signal is within a predetermined allowable range. The predetermined allowable range is set in which the signal strength is 40% or more and 80% or less (40% to 80%) of the signal acquisition range. The signal acquisition range is determined, for example, based on the saturation signal amount and the noise signal amount. An amplified signal within a predetermined allowable range can be said to be a pulse wave signal suitable for measuring the concentration of blood components.

When the determination unit 11 of the control unit 10 determines that the signal strength of the amplified signal acquired in the OP 303 is within a predetermined allowable range (Yes in the OP 304), the processing of the OP 305 is executed. In OP305, the determination unit 11 of the control unit 10 determines the amplification factor and the light emission amount of the LED for obtaining an appropriate pulse wave signal used for measuring the concentration of blood components for each LED, and the amplification signal at the amplification factor is pulse wave. Determined as a signal.

On the other hand, when the control unit 10 determines that the signal strength acquired in OP 303 is not within a predetermined allowable range (No in OP 304), the processing of OP 306 is executed. In OP306, the determination unit 11 of the control unit 10 estimates the signal strengths of the remaining three amplified signals from the signal strength of one acquired amplified signal. Since each of the first amplifier 51 to the third amplifier 53 of the amplification unit 50 has a fixed amplification factor, the determination unit 11 of the control unit 10 changes the signal strength of one amplification signal to the signal of the remaining three amplification signals. The strength can be estimated.

In the next OP307, the determination unit 11 of the control unit 10 detects an amplified signal within a predetermined allowable range among the signal intensities of the three estimated amplified signals. When the determination unit 11 of the control unit 10 determines that at least one of the three amplification signals is within a predetermined allowable range (Yes in OP307), the processing of OP305 is executed. In OP305, the determination unit 11 of the control unit 10 determines the amplification factor and the light emission amount of the LED for obtaining an appropriate pulse wave signal used for measuring the concentration of blood components for each LED, and pulses the amplification signal at the amplification factor. Determined as a wave signal.

On the other hand, when the determination unit 11 of the control unit 10 determines that the signal strength of the amplified signal estimated in OP306 is not within a predetermined allowable range (No in OP307), the processing of OP308 is executed. In OP308, the adjusting unit 12 of the control unit 10 adjusts the amount of light emitted from the first LED 31 to the fifth LED 35. The signal strength of the output signal of the PD 41 changes according to the amount of light emitted from each of the first LED 31 to the fifth LED 35. Therefore, when the signal intensities of the three amplified signals estimated in OP306 are less than 40% of the signal acquisition range, the adjusting unit 12 emits light from the LED because the signal intensities of all the amplified signals are weak as pulse wave signals. Make adjustments to increase the amount. Further, when the signal intensities of the three amplified signals estimated in OP306 are larger than 80% of the signal acquisition range, the adjusting unit 12 determines the amount of light emitted from the LED because each amplified signal has a strong signal intensity as a pulse wave signal. Make adjustments to weaken. The amount of light emitted from the LED is adjusted by PWM control. More specifically, the amount of light emitted from the LED is adjusted by changing the duty ratio of the applied voltage in the light emission control of each LED. The adjusting unit 12 can adjust the duty ratio of the applied voltage with 255 gradations.

The processing of OP302 is executed again after the processing of OP308. As described above, in the present embodiment, the combination of the amplification factor and the light emission amount of the LED to obtain an appropriate amplified signal by repeatedly executing the processes of OP302 to OP308 until the amplified signal falls within a predetermined allowable range in OP304. Is determined. Then, the determination unit 11 of the control unit 10 selects one combination for each LED from the combination of the light emission amount of the LED and the amplification factor of the amplified signal by the amplification unit 50 for the first LED 31 to the fifth LED 35. The amplification signal at the amplification factor in the combination of is determined as an appropriate pulse wave signal of each LED. As a result, the pulse wave signal acquisition device 1 according to the present embodiment can shorten the time for acquiring a pulse wave signal suitable for measuring the concentration of blood components.

Next, returning to FIG. 8, the blood component measurement process will be further described. When the measurement preparation process (OP101) is completed, the pulse wave signal acquisition device 1 shifts to the process of OP102.

In OP102, the pulse wave signal acquisition device 1 irradiates the thumb of the subject with light in the order of the fifth LED35, the fourth LED34, the third LED33, the second LED32, and the first LED31, and emits the light that has passed through the blood in the finger. Receive light with PD41 and acquire light reception data. More specifically, the pulse wave signal acquisition device 1 emits light from each LED with the emission intensity determined for each LED in the above-mentioned measurement preparation process, and amplifies the amplification factor determined for each LED in the above-mentioned measurement preparation process. The signal is acquired as pulse wave signal data. The pulse wave signal acquisition device 1 acquires, for example, pulse wave signal data for 20 seconds (200 cycles). Further, in OP 102, the pulse wave signal acquisition device 1 transmits the pulse wave signal data to the terminal device 100.

In OP201, the terminal device 100 receives the pulse wave signal data from the pulse wave signal acquisition device 1. In the present embodiment, the pulse wave signal acquisition device 1 acquires the pulse wave signal data, and the terminal device 100 analyzes the pulse wave data signal to calculate the blood TG value and the HbA1c value. Therefore, the pulse wave signal acquisition device 1 Transmits the pulse wave signal data acquired to the terminal device 100, and the terminal device 100 receives the pulse wave signal data from the pulse wave signal acquisition device 1.

In the next OP202, the terminal device 100 calculates the absorbance corresponding to each wavelength from the pulse wave signal data. For example, the change width of the pulsating signal corresponding to each wavelength can be appropriately converted into absorbance. The terminal device 100 determines the absorbance of blood corresponding to light irradiation at a wavelength of 1050 nm (hereinafter referred to as “first absorbance”) and light irradiation at a wavelength of 1200 nm from the change width of the pulse wave signal corresponding to the irradiation at each wavelength. Corresponds to the absorbance of the corresponding blood (hereinafter referred to as "second absorbance"), the absorbance of blood corresponding to light irradiation having a wavelength of 1300 nm (hereinafter referred to as "third absorbance"), and the light irradiation having a wavelength of 1450 nm. The absorbance of blood (hereinafter referred to as "fourth absorbance") and the absorbance of blood corresponding to light irradiation having a wavelength of 1600 nm (hereinafter referred to as "fifth absorbance") are calculated. According to the present embodiment, since a pulse wave signal suitable for measuring the concentration of blood components can be obtained by the measurement preparation process, the first to fifth absorbances corresponding to each wavelength are used for measuring the concentration of blood components. Can be done.

In the next OP203, the terminal device 100 calculates the blood TG value using the first absorbance, the second absorbance, and the third absorbance. Specifically, the terminal device 100 first normalizes the first absorbance by subtracting the third absorbance from the first absorbance, and then subtracts the third absorbance from the second absorbance to normalize the second absorbance. Then, the terminal device 100 calculates the ratio of the normalized first absorbance and the second absorbance, and converts the ratio into a blood TG value using a predetermined conversion table (for example, a calibration curve). As a result, the blood TG value is calculated. In addition, unlike the present embodiment, the terminal device 100 calculates, for example, a difference value by subtracting the second absorbance from the first absorbance, and converts the difference value into a blood TG value using a predetermined conversion table. You may. Alternatively, the terminal device 100 may, for example, subtract the third absorbance from the first absorbance to calculate the difference value, and convert the difference value into the blood TG value using a predetermined conversion table.

In the next OP204, the terminal device 100 calculates the HbA1c value using the first absorbance, the fourth absorbance, and the fifth absorbance. Specifically, the terminal device 100 first subtracts the first absorbance from the fourth absorbance to normalize the fourth absorbance, and then subtracts the first absorbance from the fifth absorbance to normalize the fifth absorbance. Then, the terminal device 100 calculates the ratio of the normalized fourth absorbance and the fifth absorbance, and converts the ratio into the HbA1c value using a predetermined conversion table. As a result, the HbA1c value is calculated. In addition, unlike the present embodiment, the terminal device 100 calculates the ratio of the fourth absorbance and the fifth absorbance without standardizing the fourth absorbance and the fifth absorbance, and calculates a predetermined conversion table (for example, a calibration curve). ) May be used to convert the ratio into an HbA1c value.

In the next OP205, the terminal device 100 displays the blood TG value and the HbA1c value as measured values on the display unit 100A. This allows the subject to know the blood TG value and the HbA1c value. According to the present embodiment, since a pulse wave signal suitable for measuring the concentration of the blood component can be acquired, the accuracy of measuring the concentration of the blood component can be improved.

The above is the description of the present embodiment, but the configuration of the pulse wave signal acquisition device 1, the calculation process of the blood TG value and the HbA1c value, etc. are not limited to the above embodiment, and the present invention is not limited to the above embodiment. Various changes can be made within the range that does not lose its identity with the technical idea. For example, in the above embodiment, the blood TG value is calculated first, and then the HbA1c value is calculated, but the present invention is not limited to this, and the HbA1c value is calculated first, and then the blood TG value is calculated. You may.

Further, in the above embodiment, the terminal device 100 calculates and displays the blood TG value and the HbA1c value based on the pulse wave signal data obtained by the pulse wave signal acquisition device 1, but the present invention is not limited to this. For example, the pulse wave signal acquisition device 1 calculates the blood TG value and the HbA1c value based on the pulse wave signal data, and the display unit included in the pulse wave signal acquisition device 1 displays the blood TG value and the HbA1c value. May be good. Further, the pulse wave signal acquisition device 1 may calculate the blood TG value and the HbA1c value based on the pulse wave signal data, and the terminal device 100 may display the blood TG value and the HbA1c value. In this case, the pulse wave signal acquisition device 1 has a blood component measurement program stored in the storage unit 20, and the control unit 10 expands and executes the blood component measurement program in the RAM in the storage unit 20. The various processes shown in 8 (for example, the processes of OP202 to OP205) are executed.

Further, in the measurement preparation process shown in FIG. 9, the pulse wave signal acquisition device 1 may select one LED from the first LEDs 31 to the fifth LED 35, make the LED emit light, and execute the processes of OP302 to OP308. good. In this case, the pulse wave signal acquisition device 1 sequentially executes the processes of OP302 to OP308 for each LED, determines the amplification factor at which an appropriate pulse wave signal can be obtained and the light emission amount of the LED for each LED, and the amplification factor. The amplified signal in is determined as a pulse wave signal.

Further, since the light emission amount of each LED of the first LED 31 to the fifth LED 35 and the signal intensity acquired via the PD 41 have a linear relationship as shown in FIG. 7, the pulse wave signal acquisition device 1 is shown in FIG. In OP306 of the measurement preparation process shown in 9, not only the signal strength of the remaining amplified signal is estimated by using the fixed amplification factor of another amplifier, but also each amplification when the duty ratio is increased or decreased by a predetermined amount. The signal strength of the signal may also be estimated.

Further, the pulse wave signal acquisition device 1 sets the duty ratio by a predetermined amount in OP306 of the measurement preparation process shown in FIG. 9 without estimating the signal strength of the remaining amplified signal by using the fixed amplification factor of another amplifier. Only the signal strength of each amplified signal when increased or decreased may be estimated.

(Modification example)
Next, a modified example of the measurement preparation process executed by the pulse wave signal acquisition device 1 will be described with reference to FIGS. 10 and 11. FIG. 10 is a flowchart relating to the measurement preparation process of the modified example.

First, in OP401, the control unit 10 of the pulse wave signal acquisition device 1 causes the five LEDs of the first LED 31 to the fifth LED 35 to emit light in order within 100 milliseconds. Specifically, the control unit 10 causes the five LEDs to emit light in the order of the fifth LED35, the fourth LED34, the third LED33, the second LED32, and the first LED31. The light emission time of each LED may be different from each other or may be the same. At this time, the control unit 10 controls each LED to emit light at a duty ratio of a predetermined applied voltage.

In the next OP402, the control unit 10 simultaneously acquires the amplified signal of the PD41 from the four signal acquisition pins A3 to A0.

In the next OP403, the control unit 10 receives the amplification signal acquired by the OP402 while the first LED31 to the fifth LED35 are irradiating light, that is, a plurality of amplification signals of the PD 41 input to the signal acquisition pins A3 to A0, respectively. The calculation (update) of each average value is continued, and when the average value for 5 seconds is accumulated, the process shifts to OP404 processing. In OP403, the calculated average value of the amplified signal is not limited to the signal for 5 seconds, but may be a signal for less than 5 seconds or a signal longer than 5 seconds.

In the next OP404, the determination unit 11 of the control unit 10 determines whether or not the signal strength (average value for 5 seconds) of the four amplified signals simultaneously acquired from the signal acquisition pins A3 to A0 is within a predetermined allowable range. To judge. The predetermined allowable range is the same as the range in OP304 of FIG. 9 (the range in which the signal strength is 40% or more and 80% or less (40% to 80%) of the signal acquisition range).

FIG. 11 is a flowchart showing the processing of OP404 in detail. The determination of OP404 is composed of four determinations of OP4013 to OP4043. OP4013 determines whether or not the signal strength (average value for 5 seconds) of the amplified signal acquired from the signal acquisition pin A3 is within the permissible range. OP4023 determines whether or not the signal strength (average value for 5 seconds) of the amplified signal acquired from the signal acquisition pin A2 is within the allowable range. OP4033 determines whether or not the signal strength (average value for 5 seconds) of the amplified signal acquired from the signal acquisition pin A1 is within the allowable range. OP4043 determines whether or not the signal strength (average value for 5 seconds) of the amplified signal acquired from the signal acquisition pin A0 is within the allowable range. In this way, it is determined step by step whether or not the signal strength (average value for 5 seconds) of the amplified signal acquired from each signal acquisition pin is within the permissible range, but it is acquired by the signal acquisition pins A3 to A0. When the signal strength (average value for 5 seconds) of the amplified signal is within a predetermined allowable range, the processing of OP404 is terminated.

As shown in FIG. 10, the determination unit 11 of the control unit 10 determines that any one of the signal intensities (average value for 5 seconds) of the four amplified signals calculated in OP403 is within a predetermined allowable range. In the case (Yes in OP404), the processing of OP405 is executed. In OP405, the determination unit 11 of the control unit 10 uses a pulse wave signal using any one of the signal acquisition pins A3 to A0 for inputting an amplified signal to obtain an appropriate pulse wave signal for measuring the concentration of blood components. Determined as the signal acquisition pin to be acquired.

On the other hand, when it is determined that all of the signal intensities (average value for 5 seconds) of the four amplified signals acquired by the control unit 10 in OP403 are not within the predetermined allowable range (No in OP404), the processing of OP406 is performed. Is executed. In OP406, the determination unit 11 of the control unit 10 adjusts the amount of light emitted from the first LED 31 to the fifth LED 35. After the processing of OP406, the processing of OP402 is executed again.

As described above, in the measurement preparation process of this modification, the determination unit 11 of the control unit 10 calculates the average value of each signal intensity of the plurality of amplified signals (OP403), and the average value of each amplified signal is within a predetermined allowable range. It is determined in order whether it is within or for each amplified signal, and this determination is terminated when an amplified signal whose average value is within a predetermined allowable range is detected. As a result, the pulse wave signal acquisition device 1 can shorten the time for acquiring a pulse wave signal suitable for measuring the concentration of blood components.

In the flowchart shown in FIG. 11, it is determined whether or not the signal strength of each signal is within a predetermined range in the order of the signal acquisition pin A3, the signal acquisition pin A2, the signal acquisition pin A1, and the signal acquisition pin A0. .. However, the order in which the signal strength is determined is not limited to this order, and may be, for example, the order of the signal acquisition pin A0, the signal acquisition pin A1, the signal acquisition pin A2, and the signal acquisition pin A3. Alternatively, the order may be changed for each LED according to a predetermined priority.

Further, the terminal device 100 transmits the pulse wave signal data obtained by the pulse wave signal acquisition device 1 to an external server via a communication line, and the external server determines the blood TG value and the HbA1c value based on the pulse wave signal data. The calculated information including the blood TG value and the HbA1c value may be transmitted to the terminal device 100 via the communication line, and the terminal device 100 may display the blood TG value and the HbA1c value on the display unit 100A.

Further, although the reflected light method is adopted for the pulse wave signal acquisition device 1 in the above embodiment, the transmitted light method may be adopted. In the transmitted light type pulse wave signal acquisition device 1, for example, the irradiation unit 30 is arranged on the upper cover 62 so that the irradiation unit 30 and the light receiving unit 40 sandwich the thumb 101 of the subject inserted from the opening 63. The irradiation unit 30 may irradiate light from the dorsal side (nail side) or the ventral side of the thumb 101, and the light receiving unit 40 may receive the light that has passed through the thumb.

The number of LEDs included in the irradiation unit 30, the peak wavelength of the irradiation light of each LED, and the arrangement pattern are not limited to the above embodiment. For example, when measuring only the blood TG value, the irradiation unit 30 may have at least one of the first LED 31 and the second LED 32 and the third LED 33. Further, when measuring only the HbA1c value, the irradiation unit 30 may have at least the 4th LED 34 and the 5th LED 35. Further, when it is sufficient to acquire only the pulse wave signal, the pulse wave signal acquisition device 1 may have at least one of the first LED 31 to the fifth LED 35.

In the present embodiment, the blood TG value is calculated numerically and displayed on the display unit 100A, but the blood TG value may be converted into an index format having 3 to 5 stages and displayed.

Further, the predetermined allowable range of the signal strength of the amplified signal may be set to a plurality of levels. For example, the first allowable range is set to the range of 50 to 70% of the signal acquisition range, and when the signal strength deviates from the first allowable range, the allowable range is set to the second allowable range of 40 to 80% of the signal acquisition range. It may be expanded to judge the quality of the signal strength.

Further, the amplification unit 50 may be configured to connect amplifiers in parallel and connect an adder circuit to the subsequent stage. Further, the number of amplifiers included in the amplification unit 50 is not limited to three, and the amplification unit 50 may have at least one amplifier. The fixed amplification factors of the first amplifier 51 to the third amplifier are not limited to the above-described embodiment.

Further, the PWM control used for adjusting the light emission amount of the first LED 31 to the fifth LED 35 is not limited to 255 gradations, may be 10 gradations, may be 20 gradations, and may be gradations depending on each LED (for each emission wavelength). May be changed. Further, the pulse wave signal acquisition device 1 may not have a function of adjusting the amount of light emitted from the first LED 31 to the fifth LED 35.

The user of the pulse wave signal acquisition device 1 may visually check the measurement result displayed on the terminal device 100 or the like, and manually select the signal and adjust the light emission amount. For example, the user changes the signal acquisition pins A3 to A0 for acquiring the signal on the spot while checking the pulse wave signal of the subject on the display unit 100A of the terminal device 100, and adjusts the light emission amount of each LED. May be performed to confirm that the pulse wave signal is in an appropriate state.

Further, the living body to be measured in the above embodiment was a human, but the living body to be measured is not limited to humans. Mammals and birds are examples of specific living organisms to be measured. Of these, it is more preferable to measure humans who may be diagnosed with a disease due to hyperglycemia (for example, diabetes), and mammals and birds which can be pets and livestock.

Further, in the above embodiment, the blood TG value and the HbA1c value are measured as the blood component concentration, but the concentration of another blood component may be measured. For example, hemoglobin, glucose, cholesterol (total cholesterol, HDL- or LDL-cholesterol, free cholesterol), urea, bilirubin, lipoprotein, phospholipid, ethyl alcohol, etc. in blood may be measured. In this case, the living body is irradiated with light having a wavelength whose absorbance changes depending on the concentration of each blood component, and the concentration of each blood component is calculated from the absorbance.

Further, in the above embodiment, an example in which five LEDs having different emission wavelengths are used has been shown, but by changing or increasing the blood component to be measured, the required number of LEDs and the light emission of the LEDs are shown. The type of wavelength is changed as appropriate. According to the pulse wave signal acquisition device of the present invention, by mounting a large number of LEDs having different wavelengths, it is possible to simulate the spectral measurement of blood components without using a spectroscope, so that the concentrations of various blood components can be measured. It will be possible to do.

1 Pulse wave signal acquisition device 10 Control unit 11 Determination unit 12 Adjustment unit 20 Storage unit 30 Irradiation unit 40 Light receiving unit 50 Amplification unit 60 Communication unit 100 Terminal device

Claims

At least one light emitting element that irradiates the measurement site of the living body with light,
A light receiving element that receives light that has passed through the measurement site, and
An amplification unit that includes at least one amplifier having a fixed amplification factor and generates a plurality of amplification signals having different amplification factors by amplifying an output signal from the light receiving element at each fixed amplification factor of each amplifier.
A determination unit that determines the amplified signal of one of the plurality of amplified signals as a pulse wave signal, and
A pulse wave signal acquisition device having.
It is equipped with a plurality of the light emitting elements.
The plurality of light emitting elements emit light having different wavelengths, and irradiate the light in a predetermined order.
The determination unit determines the one amplification signal for each output signal from the light receiving element based on the irradiation of light from each light emitting element.
The pulse wave signal acquisition device according to claim 1.
The determination unit detects the signal strength of one of the plurality of amplified signals and estimates the signal strength of the other amplified signal from the signal strength of the one amplified signal.
The pulse wave signal acquisition device according to claim 1 or 2.
The determination unit detects each signal strength of the plurality of amplified signals.
The pulse wave signal acquisition device according to claim 1 or 2.
The determination unit preferentially detects the signal strength of one amplified signal specified in advance among the plurality of amplified signals, and when the signal strength of the one amplified signal is within a predetermined allowable range, the determination unit concerned. Determine one amplified signal as a pulse wave signal,
The pulse wave signal acquisition device according to any one of claims 1 to 4.
Further, it has an adjusting unit for adjusting the amount of light emitted from the light emitting element.
The determination unit selects one combination from the combination of the light emission amount and the amplification factor, and determines the amplification signal at the amplification factor in the one combination as the pulse wave signal.
The pulse wave signal acquisition device according to any one of claims 1 to 5.