Blood sugar level measuring apparatus

Abstract

To provide a blood sugar level measuring apparatus capable of measuring a blood sugar level using a green light source.SOLUTION: A blood sugar level measuring apparatus includes: a light output part including a green light source outputting incident light L1; a light detection part detecting transmitted light L2 transmitting a living organism; and an operation part calculating the blood sugar level of the living organism. In the spectrum of the incident light L1, the center wavelength is located within a range from 430 nm to 580 nm, the intensity in 600 nm to 615 nm is 0.01% or more of the intensity in the center wavelength, and the intensity within a range from 480 nm to 515 nm is 1% or more of the intensity in the center wavelength. The light detection part has: a first light detector having a first detected wavelength range from 460 nm to 535 nm and a second light detector having a second detected wavelength range of 580 nm or larger. The operation part calculates the blood sugar level of a living body on the basis of the intensity of the transmitted light L2 detected by the first light detector and the intensity of the transmitted light L2 detected by the second light detector.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a blood glucose measurement device.

Background Art

[0002] As a device for non-invasively measuring biological information, for example, the device described in Patent Document 1 is known. The device described in Patent Document 1 has a function of measuring the pulse of a living body by outputting light to the living body, for example.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described device, measurement of blood glucose level may be required. However, a green light source may be used for measuring the pulse of a living body. For example, if a new light source for measuring blood glucose level is added, there is a concern about an increase in the size of the device or an increase in power consumption.

[0005] An object of the present invention is to provide a blood glucose measurement device capable of realizing measurement of blood glucose level using a green light source.

Means for Solving the Problems

[0006] The blood glucose measuring device of the present invention is "[1] A blood glucose measuring device for measuring the blood glucose level of a living body, comprising a light output unit including a green light source that outputs incident light to the living body, a light detection unit that detects transmitted light that has passed through the living body, and an arithmetic unit that calculates the blood glucose level of the living body based on the detection result of the light detection unit, wherein in the spectrum of the incident light, the central wavelength is located in a first wavelength range of 430 nm to 580 nm, the intensity in a second wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and the intensity in a third wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength, the light detection unit has a first photodetector having a first detection wavelength range of 460 nm to 535 nm and a second photodetector having a second detection wavelength range of 580 nm or more, and the arithmetic unit calculates the blood glucose level of the living body based on the intensity of the transmitted light detected by the first photodetector and the intensity of the transmitted light detected by the second photodetector."

[0007] In the blood glucose measuring device described in the above [1], in the spectrum of the incident light output to the living body, the central wavelength is located in a first wavelength range of 430 nm to 580 nm, the intensity in a second wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and the intensity in a third wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength. When such incident light is incident on the living body, transmitted light having a spectrum in which the central wavelength is located in each of a wavelength range of 460 nm to 535 nm and a wavelength range of 580 nm or more is emitted from the living body. The arithmetic unit calculates the blood glucose level of the living body based on the intensity of the transmitted light detected in the first detection wavelength range of 460 nm to 535 nm and the intensity of the transmitted light detected in the second detection wavelength range of 580 nm or more. Therefore, according to this blood glucose measuring device, it is possible to realize the measurement of blood glucose using a green light source.

[0008] The blood glucose measurement device of the present invention may be "[2] In the spectrum of the incident light, the central wavelength is located in the fourth wavelength range of 470 nm to 540 nm, the intensity in the fifth wavelength range of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in the sixth wavelength range of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength. The blood glucose measurement device according to [1] above." Thereby, since transmitted light suitable for calculating the blood glucose level can be obtained, the blood glucose level of the living body can be calculated with higher accuracy.

[0009] The blood glucose measurement device of the present invention may be "[3] The first photodetector includes a first light detection region and a first optical filter provided on the first light detection region and having a first transmission wavelength range of 460 nm to 535 nm. The second photodetector includes a second light detection region and a second optical filter provided on the second light detection region and having a second transmission wavelength range of 580 nm or more. The calculation unit calculates the blood glucose level of the living body based on the intensity of the transmitted light that passes through the first optical filter and is detected by the first light detection region, and the intensity of the transmitted light that passes through the second optical filter and is detected by the second light detection region. The blood glucose measurement device according to [1] or [2] above." Thereby, since the transmitted light is selectively transmitted by each of the first optical filter and the second optical filter, it is possible to achieve commonality in the configuration of the first light detection region and the second light detection region.

[0010] The blood glucose measurement device of the present invention may be "[4] The light detection unit further includes a third photodetector having a third detection wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse of the living body based on the intensity of the transmitted light detected by the third photodetector. The blood glucose measurement device according to any one of [1] to [3] above." Thereby, it is possible to realize the measurement of both blood glucose level and pulse using a green light source, and suppress the increase in the size of the device and the power consumption.

[0011] The blood glucose measuring device of the present invention may be "[5] The third photodetector further includes a third light detection region and a third optical filter provided on the third light detection region and having a third transmission wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse of the living body based on the intensity of the transmitted light that passes through the third optical filter and is detected by the third light detection region, according to the blood glucose measuring device described in [4] above." Thus, since the transmitted light is selectively transmitted by each of the first optical filter, the second optical filter, and the third optical filter, it is possible to make the configurations of the first light detection region, the second light detection region, and the third light detection region common.

[0012] The blood glucose measuring device of the present invention may be "[6] Each of the first photodetectors is one of a plurality of first photodetectors, each of the second photodetectors is one of a plurality of second photodetectors, and each of the plurality of first photodetectors and each of the plurality of second photodetectors are alternately arranged so as to surround the light output unit, according to the blood glucose measuring device described in any one of [1] to [5] above." Thus, the loss of the incident light output from the light output unit is reduced.

[0013] The blood glucose measuring device of the present invention may be "[7] Each of the green light sources is one of a plurality of green light sources, and each of the plurality of green light sources is arranged so as to surround the light detection unit, according to the blood glucose measuring device described in any one of [1] to [5] above." Thus, since the plurality of green light sources surround the light detection unit, the intensity of the transmitted light incident on the light detection unit is ensured.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a blood glucose measuring device capable of realizing the measurement of blood glucose values using a green light source.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0017] FIG. 1 is a cross-sectional view of the blood glucose measuring device and the living body of the present embodiment. FIG. 1 is a conceptual diagram for explaining the function of the blood glucose measuring device 1, and does not necessarily show the actual cross-section of the blood glucose measuring device 1.

[0018] The blood glucose measuring device 1 shown in FIG. 1 is, for example, a wearable device, a smartphone, a pulse oximeter, or the like. Examples of wearable devices include smartwatches and smart rings. In the present embodiment, the blood glucose measuring device 1 is a smartwatch having a function of measuring the blood glucose level of the living body 6. The living body 6 has a surface layer tissue 61 and an internal tissue 62 located inside the living body 6 rather than the surface layer tissue 61. The surface 61a of the surface layer tissue 61 is the surface of the skin of the living body 6. The living body 6 is, for example, a human body.

[0019] The blood glucose measuring device 1 includes a main body unit 2, a light output unit 3, a light detection unit 4, and an ECU [Electronic Control Unit] 5. The main body unit 2 has a front surface 2a and a back surface 2b facing the side opposite to the front surface 2a. The front surface 2a functions as a display screen (display) for displaying various information of the blood glucose measuring device 1. The blood glucose measuring device 1 is attached to the living body 6 so that the back surface 2b contacts the skin of the living body 6.

[0020] The light output unit 3 is provided in the main body unit 2. The light output surface of the light output unit 3 is exposed from the back surface 2b of the main body unit 2. The light output unit 3 outputs the measurement light L. The measurement light L is emitted from the back surface 2b. The measurement light L emitted from the light output unit 3 propagates inside the living body 6 and then is emitted from the living body 6 again. The light output unit 3 is controlled by the ECU 5.

[0021] The light detection unit 4 is provided in the main body unit 2. The light detection unit 4 is separated from the light output unit 3. The light detection surface of the light detection unit 4 is exposed from the back surface 2b of the main body unit 2. The light detection unit 4 detects the measurement light L (transmitted light) that has passed through the living body 6. The light detection unit 4 transmits a signal regarding the intensity of the measurement light L to the ECU 5.

[0022] The ECU 5 is provided in the main body unit 2. The ECU 5 is an electronic control unit having a CPU [Central Processing Unit] and a storage unit such as a ROM [Read Only Memory] or a RAM [Random Access Memory]. In the ECU 5, for example, a program stored in the storage unit is executed by the CPU. The ECU 5 functions as an arithmetic unit that calculates the biological information of the living body 6. The ECU 5 calculates the blood glucose level of the living body 6, the pulse of the living body 6, the oxygen saturation concentration of the living body 6, etc. based on the signal transmitted from the light detection unit 4 (the detection result of the light detection unit 4).

[0023] FIG. 2 is a rear view of the blood glucose level measuring device 1. FIG. 2 shows the light output unit 3 and the light detection unit 4 when viewed from the back surface 2b of the main body unit 2. As shown in FIG. 2, the light output unit 3 has a first light source 31, a second light source 32, and a third light source 33. The first light source 31, the second light source 32, and the third light source 33 are arranged in a row. The first light source 31 is disposed between the second light source 32 and the third light source 33.

[0024] The first light source 31 is a green light source. The first light source 31 outputs green light as the measurement light L. The green light is, for example, a probe light with a central wavelength of about 515 nm. The green light is different from white light. When observed by the human eye, the green light appears green or greenish blue. The color of the green light corresponds to, for example, 5G, 10G, 5BG, or 10BG in the Munsell color system. The first light source 31 outputs green light at a predetermined pulse interval in response to the control signal transmitted from the ECU 5. That is, the green light output from the first light source 31 blinks at a predetermined pulse interval. The first light source 31 continues to output green light. That is, the green light output from the first light source 31 is constantly blinking. The first light source 31 is, for example, a light-emitting diode (LED), a laser diode (LD), or a superluminescent diode (SLD), etc.

[0025] The second light source 32 is a red light source. The second light source 32 outputs red light as the measurement light L. The red light is, for example, a probe light with a central wavelength of about 660 nm. The second light source 32 outputs red light at a predetermined pulse interval in response to the control signal transmitted from the ECU 5. That is, the red light output from the first light source 31 blinks at a predetermined pulse interval. The second light source 32 outputs red light intermittently. That is, the red light output from the second light source 32 blinks intermittently. The second light source 32 operates at predetermined intervals. During the period when the second light source 32 is operating, both the green light and the red light blink. During the period when the second light source 32 is stopped, the green light blinks and the red light is turned off. The second light source 32 is, for example, a light-emitting diode (LED), a laser diode (LD), or a superluminescent diode (SLD), etc.

[0026] The third light source 33 is an infrared light source. The third light source 33 outputs infrared light as the measurement light L. The infrared light is, for example, probe light with a central wavelength of about 880 nm or about 910 nm. The third light source 33 outputs infrared light at a predetermined pulse interval in response to a control signal transmitted from the ECU 5. That is, the infrared light output from the third light source 33 blinks at a predetermined pulse interval. The third light source 33 outputs infrared light intermittently. That is, the infrared light output from the third light source 33 blinks intermittently. The third light source 33 operates at predetermined intervals. During the period when the third light source 33 is operating, both the green light and the infrared light blink. During the period when the third light source 33 is stopped, the green light blinks and the infrared light is turned off. The third light source 33 is, for example, a light emitting diode (LED), a laser diode (LD), or a superluminescent diode (SLD).

[0027] The light detection unit 4 includes a plurality of first photodetectors 401, a plurality of second photodetectors 402, and a plurality of third photodetectors 403. The plurality of first photodetectors 401, the plurality of second photodetectors 402, and the plurality of third photodetectors 403 are arranged in an annular shape so as to surround the light output unit 3. Each first photodetector 401, each second photodetector 402, and each third photodetector 403 are alternately arranged so as to surround the light output unit 3. In the present embodiment, the light detection unit 4 includes two first photodetectors 401, two second photodetectors 402, and three third photodetectors 403. In the circumferential direction of the light detection unit 4, one first photodetector 401, one second photodetector 402, one third photodetector 403, one first photodetector 401, one third photodetector 403, one second photodetector 402, and one third photodetector 403 are arranged in order.

[0028] The first photodetector 401 has a first detection wavelength range S1 (see FIG. 4). That is, the first photodetector 401 detects light having wavelengths included in the first detection wavelength range S1. The first detection wavelength range S1 is 460 nm to 535 nm. The second photodetector 402 has a second detection wavelength range S2 (see FIG. 4). That is, the second photodetector 402 detects light having wavelengths included in the second detection wavelength range S2. The second detection wavelength range S2 is 580 nm or more. The third photodetector 403 has a third detection wavelength range S3 (see FIG. 4). That is, the third photodetector 403 detects light having wavelengths included in the third detection wavelength range S3. The third detection wavelength range S3 is 500 nm to 600 nm.

[0029] The first photodetector 401 has a first light detection region 41 and a first optical filter 44. The second photodetector 402 has a second light detection region 42 and a second optical filter 45. The third photodetector 403 has a third light detection region 43 and a third optical filter 46. Each of the light detection regions 41, 42, 43 detects the transmitted light that has passed through the living body 6. Each of the light detection regions 41, 42, 43 has a light detection element and a preamplifier. The light detection element is, for example, a photodiode (PD) or the like. The preamplifier amplifies the photocurrent output from the light detection element. In the present embodiment, the configurations of the light detection regions 41, 42, 43 are the same as each other.

[0030] The first optical filter 44 is provided on the first light detection region 41. The first optical filter 44 is provided on the light detection surface of the first light detection region 41. The outer edge of the first optical filter 44 is located outside the outer edge of the first light detection region 41. The outer edge of the first optical filter 44 may substantially coincide with the outer edge of the first light detection region 41. The first optical filter 44 is, for example, in the form of a film. The first optical filter 44 has a first transmission wavelength range T1 (see FIG. 4). The transmittance of light having a wavelength included in the first transmission wavelength range T1 passing through the first optical filter 44 is greater than the transmittance of light having a wavelength not included in the first transmission wavelength range T1 passing through the first optical filter 44. The first optical filter 44 transmits light in the first transmission wavelength range T1 and does not transmit light outside the first transmission wavelength range T1. The first transmission wavelength range T1 is 460 nm to 535 nm.

[0031] The second optical filter 45 is provided on the second light detection region 42. The second optical filter 45 is provided on the light detection surface of the second light detection region 42. The outer edge of the second optical filter 45 is located outside the outer edge of the second light detection region 42. The outer edge of the second optical filter 45 may substantially coincide with the outer edge of the second light detection region 42. The second optical filter 45 is, for example, in the form of a film. The second optical filter 45 has a second transmission wavelength range T2 (see FIG. 4). The transmittance of light having a wavelength included in the second transmission wavelength range T2 passing through the second optical filter 45 is greater than the transmittance of light having a wavelength not included in the second transmission wavelength range T2 passing through the second optical filter 45. The second optical filter 45 transmits light in the second transmission wavelength range T2 and does not transmit light outside the second transmission wavelength range T2. The second transmission wavelength range T2 is 580 nm or more, preferably 610 nm or more.

[0032] The third optical filter 46 is provided on the third light detection region 43. The third optical filter 46 is provided on the light detection surface of the third light detection region 43. The outer edge of the third optical filter 46 is located outside the outer edge of the third light detection region 43. The outer edge of the third optical filter 46 may substantially coincide with the outer edge of the third light detection region 43. The third optical filter 46 is, for example, in a film shape. The third optical filter 46 has a third transmission wavelength range T3 (see FIG. 4). The transmittance of light having a wavelength included in the third transmission wavelength range T3 passing through the third optical filter 46 is greater than the transmittance of light having a wavelength not included in the third transmission wavelength range T3 passing through the third optical filter 46. The third optical filter 46 transmits light in the third transmission wavelength range T3 and does not transmit light outside the third transmission wavelength range T3. The third transmission wavelength range T3 is 500 nm to 600 nm.

[0033] Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 is, for example, a dielectric multilayer film filter or the like. Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 may be, for example, a color filter for an image sensor formed by a color resist, or a color filter in which a dye is mixed into gelatin or triacetate. Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 may be the same as each other or different from each other.

[0034] Next, the measurement of the blood glucose level using the green light output from the first light source 31 will be described in detail. FIG. 3 is a diagram showing the spectra of the incident light L1 (broken line) output from the first light source 31 and the transmitted light L2 (solid line) transmitted through the living body 6. In FIG. 3, the wavelength is on the horizontal axis and the light intensity is on the vertical axis. In FIG. 3, the vertical axis is expressed as a logarithmic scale.

[0035] As shown in FIG. 3, the first light source 31 of the light output unit 3 outputs incident light L1 to the living body 6, and the light detection unit 4 detects transmitted light L2 that has passed through the living body 6. The incident light L1 is the green light described above. In the spectrum of the incident light L1, the central wavelength is located in the first wavelength range R1. That is, the incident light L1 has a peak value in the first wavelength range R1. The central wavelength of the incident light L1 is an arbitrary value within the first wavelength range R1. The first wavelength range R1 is 430 nm to 580 nm.

[0036] In the spectrum of the incident light L1, the intensity in the second wavelength range R2 is 0.01% or more of the intensity at the central wavelength (the peak intensity of the incident light L1). In the spectrum of the incident light L1, the intensity in the second wavelength range R2 is 10% or less of the intensity at the central wavelength, preferably 5% or less of the intensity at the central wavelength. The "intensity in the wavelength range" refers to the intensity corresponding to the value of any wavelength within the wavelength range. The second wavelength range R2 is 600 nm to 615 nm. At least a part of the inner region of the spectrum of the incident light L1 (the region between L1 and the horizontal axis in FIG. 3) overlaps with the region D1. The region D1 is, in FIG. 3, a region having an intensity of 0.01% or more at the central wavelength and being within the second wavelength range R2.

[0037] In the spectrum of the incident light L1, the intensity in the third wavelength range R3 is 1% or more of the intensity at the central wavelength, preferably 50% or more of the intensity at the central wavelength. In the spectrum of the incident light L1, the intensity in the third wavelength range R3 is 100% or less of the intensity at the central wavelength. The third wavelength range R3 is 480 nm to 515 nm. At least a part of the inner region of the spectrum of the incident light L1 overlaps with the region D2. The region D2 is, in FIG. 3, a region having an intensity of 1% or more at the central wavelength and being within the third wavelength range R3.

[0038] In the spectrum of the incident light L1, the central wavelength is preferably located in the fourth wavelength range R4. The fourth wavelength range R4 is included in the first wavelength range R1. That is, the minimum value of the fourth wavelength range R4 is equal to or greater than the minimum value of the first wavelength range R1, and the maximum value of the fourth wavelength range R4 is equal to or less than the maximum value of the first wavelength range R1. The fourth wavelength range R4 is, for example, 470 nm to 540 nm.

[0039] In the spectrum of the incident light L1, preferably, the intensity in the fifth wavelength range R5 is 0.1% or more of the intensity at the central wavelength. The fifth wavelength range R5 is included in the second wavelength range R2. That is, the minimum value of the fifth wavelength range R5 is equal to or greater than the minimum value of the second wavelength range R2, and the maximum value of the fifth wavelength range R5 is equal to or less than the maximum value of the second wavelength range R2. The fifth wavelength range R5 is, for example, 605 nm to 615 nm. At least a part of the inner region of the spectrum of the incident light L1 preferably overlaps with the region D3. The region D3 is, in FIG. 3, a region having an intensity of 0.1% or more at the central wavelength and being within the fifth wavelength range R5.

[0040] In the spectrum of the incident light L1, preferably, the intensity in the sixth wavelength range R6 is 40% or more of the intensity at the central wavelength. The sixth wavelength range R6 is included in the third wavelength range R3. That is, the minimum value of the sixth wavelength range R6 is equal to or greater than the minimum value of the third wavelength range R3, and the maximum value of the sixth wavelength range R6 is equal to or less than the maximum value of the third wavelength range R3. The sixth wavelength range R6 is, for example, 490 nm to 515 nm. At least a part of the inner region of the spectrum of the incident light L1 overlaps with the region D4. The region D4 is, in FIG. 3, a region having an intensity of 40% or more at the central wavelength and being within the sixth wavelength range R6.

[0041] The transmitted light L2 is the light that has passed through the living body 6 among the incident light L1. FIG. 4 is a diagram showing the spectrum of the transmitted light L2 shown in FIG. 3. In FIG. 4, the wavelength is on the horizontal axis and the light intensity is on the vertical axis. In FIG. 4, the vertical axis is represented as a linear scale.

[0042] As shown in FIGS. 3 and 4, in the spectrum of the transmitted light L2, the central wavelengths are located in the first transmission wavelength range T1 (first detection wavelength range S1), the second transmission wavelength range T2 (second detection wavelength range S2), and the third transmission wavelength range T3 (third detection wavelength range S3), respectively. The transmitted light L2 has a first peak P1 in the first transmission wavelength range T1, a second peak P2 in the second transmission wavelength range T2, and a third peak P3 in the third transmission wavelength range T3.

[0043] The transmitted light L2 having the first peak P1, the second peak P2, and the third peak P3 is incident on the first optical filter 44, the second optical filter 45, and the third optical filter 46, respectively. The transmitted light L2 (first peak P1) in the first transmission wavelength range T1 passes through the first optical filter 44 and is detected by the first light detection region 41. The transmitted light L2 (second peak P2) in the second transmission wavelength range T2 passes through the second optical filter 45 and is detected by the second light detection region 42. The transmitted light L2 (third peak P3) in the third transmission wavelength range T3 passes through the third optical filter 46 and is detected by the third light detection region 43.

[0044] The ECU 5 measures the blood glucose level of the living body 6 based on the intensity of the transmitted light L2 detected by the first photodetector 401 and the intensity of the transmitted light L2 detected by the second photodetector 402. The ECU 5 calculates the blood glucose level of the living body 6 based on the intensity of the transmitted light L2 (first peak P1) that passes through the first optical filter 44 and is detected by the first light detection region 41, and the intensity of the transmitted light L2 (second peak P2) that passes through the second optical filter 45 and is detected by the second light detection region 42.

[0045] Specifically, the ECU 5 calculates the difference between the intensity of the first peak P1 at the first time and the intensity of the first peak P1 at the second time (the amount of change in the intensity of the first peak P1 over time), the difference between the intensity of the second peak P2 at the first time and the intensity of the second peak P2 at the second time (the amount of change in the intensity of the second peak P2 over time), and the ratio of oxygenated hemoglobin to the first peak P1 (O 2The absorption coefficients of oxyhemoglobin (Hb) and deoxyhemoglobin (HHb), and O for the second peak P2 2 Based on the absorption coefficients of Hb and HHb respectively, O 2 The relative change in Hb over time (ΔO 2 Hb) and the relative change in HHb over time (ΔHHb) are calculated. The ECU 5 continuously calculates each of ΔO 2 Hb and ΔHHb at a predetermined time interval (for example, about 16 milliseconds). The ECU 5 2 Based on the time difference between the characteristic points (for example, peak points) of ΔO 2 Hb and the characteristic points (for example, peak points) of ΔHHb, the blood glucose level of the living body 6 is calculated. Note that the ECU 5 may calculate the derivative value (first derivative value) of ΔO

[0046] The ECU 5 calculates the pulse of the living body 6 based on the intensity of the transmitted light L2 detected by the third photodetector 403. The ECU 5 calculates the pulse of the living body 6 based on the intensity of the transmitted light (third peak P3) that passes through the third optical filter 46 and is detected by the third light detection region 43. The ECU 5 calculates the pulse of the living body 6 based on the time interval between adjacent third peaks P3. For example, when the time interval between adjacent third peaks P3 is 0.8 seconds (for example, the average value), the ECU 5 calculates the value obtained by dividing 60 seconds by 0.8 seconds (75 BPM [Beat Per Minute]) as the pulse of the living body 6.

[0047] The red light output from the second light source 32 and the infrared light output from the third light source 33 are each detected by the third photodetector 403. The red light output from the second light source 32 and the infrared light output from the third light source 33 each pass through the third optical filter 46 and are detected by the third light detection region 43. The ECU 5 calculates the blood oxygen saturation concentration of the living body 6 based on the intensities of the red light and the infrared light (the transmitted light of each of the red light and the infrared light) that pass through the third optical filter 46 and are detected by the third light detection region 43. In the present embodiment, a known method is used as the method for calculating the blood oxygen saturation concentration. The ECU 5 may calculate the blood glucose level of the living body 6 by the same method as the method using the green light described above based on the intensities of the red light and the infrared light detected by the third light detection region 43.

[0048] As described above, in the blood glucose level measuring device 1, in the spectrum of the incident light L1 output to the living body 6, the central wavelength is located in the first wavelength range R1 of 430 nm to 580 nm, the intensity in the second wavelength range R2 of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and the intensity in the third wavelength range R3 of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength. When such incident light L1 is incident on the living body 6, transmitted light L2 having a spectrum (a spectrum having the first peak P1 and the second peak P2) in which the central wavelength is located in each of the wavelength ranges of 460 nm to 535 nm and 580 nm or more is emitted from the living body 6. The ECU 5 calculates the blood glucose level of the living body 6 based on the intensity of the transmitted light L2 (the intensity of the first peak P1) detected in the first detection wavelength range S1 of 460 nm to 535 nm and the intensity of the transmitted light L2 (the intensity of the second peak P2) detected in the second detection wavelength range S2 of 580 nm or more. Therefore, according to the blood glucose level measuring device 1, it is possible to realize the measurement of the blood glucose level using a green light source.

[0049] In order to miniaturize the device and save power, the inventors of the present application came up with the idea of using a green light source for measuring blood glucose levels. As a result of intensive research based on this idea, the inventors of the present application found that when using green light having a spectrum in which the central wavelength is located in the wavelength range of 430 nm to 580 nm, the intensity in the wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and the intensity in the wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength, biospectroscopy is possible. That is, the inventors of the present application found that when green light having such a spectrum is incident on a living body, transmitted light having a spectrum in which the central wavelength is located in each of the wavelength ranges of 460 nm to 535 nm and 580 nm or more, and the intensity at each central wavelength is at the same level, is obtained. The inventors of the present application succeeded in measuring blood glucose levels using this transmitted light.

[0050] In the spectrum of the incident light L1, preferably, the central wavelength is located in the fourth wavelength range R4 of 470 nm to 540 nm, the intensity in the fifth wavelength range R5 of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in the sixth wavelength range R6 of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength. Thereby, since the transmitted light L2 suitable for calculating the blood glucose level can be obtained, the blood glucose level of the living body 6 can be calculated more accurately.

[0051] The first photodetector 401 includes a first light detection region 41 and a first optical filter 44 provided on the first light detection region 41 and having a first transmission wavelength range T1 of 460 nm to 535 nm. The second photodetector 402 includes a second light detection region 42 and a second optical filter 45 provided on the second light detection region 42 and having a second transmission wavelength range T2 of 580 nm or more. The ECU 5 calculates the blood glucose level of the living body 6 based on the intensity of the transmitted light L2 (intensity of the first peak P1) that passes through the first optical filter 44 and is detected by the first light detection region 41, and the intensity of the transmitted light L2 (intensity of the second peak P2) that passes through the second optical filter 45 and is detected by the second light detection region 42. Thus, since the transmitted light L2 is selectively transmitted by each of the first optical filter 44 and the second optical filter 45, it is possible to make the configurations of the first light detection region 41 and the second light detection region 42 common.

[0052] The light detection unit 4 has a third photodetector 403 having a third detection wavelength range S3 of 500 nm to 600 nm. The ECU 5 calculates the pulse of the living body 6 based on the intensity of the transmitted light L2 detected by the third photodetector 403. Thus, it is possible to realize the measurement of both the blood glucose level and the pulse using a green light source, and suppress the increase in the size of the device and the power consumption.

[0053] The third photodetector 403 has a third light detection region 43 and a third optical filter 46 provided on the third light detection region 43 and having a third transmission wavelength range T3 of 500 nm to 600 nm. The ECU 5 calculates the pulse of the living body 6 based on the intensity of the transmitted light L2 (third peak P3) that passes through the third optical filter 46 and is detected by the third light detection region 43. Thus, since the transmitted light L2 is selectively transmitted by each of the first optical filter 44, the second optical filter 45, and the third optical filter 46, it is possible to make the configurations of the first light detection region 41, the second light detection region 42, and the third light detection region 43 common.

[0054] Each first photodetector 401, each second photodetector 402, and each third photodetector 403 are alternately arranged so as to surround the light output unit 3. Thereby, the loss of the measurement light L emitted from the light output unit 3 is reduced.

[0055] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment.

[0056] FIG. 5 is a rear view of a blood glucose measurement device according to a modified example. As shown in FIG. 5, in the blood glucose measurement device 1 according to the modified example, the light output unit 3 includes a plurality of first light sources 31, a plurality of second light sources 32, and a plurality of third light sources 33. The plurality of first light sources 31, the plurality of second light sources 32, and the plurality of third light sources 33 are arranged in an annular shape so as to surround the light detection unit 4. Each first light source 31, each second light source 32, and each third light source 33 are alternately arranged so as to surround the light detection unit 4. The light output unit 3 has, for example, three first light sources 31, two second light sources 32, and two third light sources 33. In the circumferential direction of the light output unit 3, one first light source 31, one third light source 33, one second light source 32, one first light source 31, one third light source 33, one first light source 31, and one second light source 32 are arranged in order. In this case, each photodetector of the light detection unit 4 may be alternately arranged in a matrix. Further, each photodetector of the light detection unit 4 may have a CCD image sensor, a CMOS image sensor, or the like instead of a PD. According to such a configuration, since the plurality of first light sources 31, the plurality of second light sources 32, and the plurality of third light sources 33 surround the light detection unit 4, the intensity of the transmitted light L2 incident on the light detection unit 4 is ensured. In the blood glucose measurement device 1 according to the modified example, the light output unit 3 may have a first light source 31 instead of each of the second light source 32 and the third light source 33. The light output unit 3 may be constituted by a plurality of first light sources 31 that surround the light detection unit 4. In this case, the second transmission wavelength range T2 may be 580 nm to 635 nm, and preferably may be 610 nm to 635 nm.

[0057] In the embodiment, the light output unit 3 had the second light source (red light source) 32 and the third light source (infrared light source) 33. However, the light output unit 3 may not have the second light source 32 and the third light source 33. The light output unit 3 may be constituted by the first light source 31. In this case, the second transmission wavelength range T2 may be 580 nm to 635 nm, and preferably may be 610 nm to 635 nm.

[0058] In the embodiment, the light detection unit 4 had the third optical filter 46. However, the light detection unit 4 may not have the third optical filter 46.

[0059] In the embodiment, the first photodetector 401 had the first optical filter 44. However, when the first light detection region 41 has selectively sensitivity to the first detection wavelength range S1, the first photodetector 401 may not have the first optical filter 44. In the embodiment, the second photodetector 402 had the second optical filter 45. However, when the second light detection region 42 has selectively sensitivity to the second detection wavelength range S2, the second photodetector 402 may not have the second optical filter 45. In the embodiment, the third photodetector 403 had the third optical filter 46. However, when the third light detection region 43 has selectively sensitivity to the third detection wavelength range S3, the third photodetector 403 may not have the third optical filter 46.

Description of Reference Numerals

[0060] 1... Blood glucose measurement device, 3... Light output unit, 4... Light detection unit, 5... ECU (computation unit), 6... Living body, 31... First light source (green light source), 41... First light detection region, 42... Second light detection region, 43... Third light detection region, 44... First optical filter, 45... Second optical filter, 46... Third optical filter, 401... First photodetector, 402... Second photodetector, 403... Third photodetector, L1... Incident light, L2... Transmitted light, R1... First wavelength range, R2... Second wavelength range, R3... Third wavelength range, R4... Fourth wavelength range, R5... Fifth wavelength range, R6... Sixth wavelength range, S1... First detection wavelength range, S2... Second detection wavelength range, S3... Third detection wavelength range, T1... First transmission wavelength range, T2... Second transmission wavelength range, T3... Third transmission wavelength range.

Claims

1. A blood glucose measurement device for measuring the blood glucose level of a living body, comprising: an optical output unit including a green light source that outputs incident light to the living body; a light detection unit that detects transmitted light that has passed through the living body; a calculation unit that calculates the blood glucose level of the living body based on the detection result of the light detection unit, in the spectrum of the incident light, the central wavelength is located in a first wavelength range of 430 nm to 580 nm, the intensity in a second wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and the intensity in a third wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength; the light detection unit includes a first photodetector having a first detection wavelength range of 460 nm to 535 nm and a second photodetector having a second detection wavelength range of 580 nm or more; the calculation unit calculates the blood glucose level of the living body based on the intensity of the transmitted light detected by the first photodetector and the intensity of the transmitted light detected by the second photodetector.

2. In the spectrum of the incident light, the central wavelength is located in a fourth wavelength range of 470 nm to 540 nm, the intensity in a fifth wavelength range of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in a sixth wavelength range of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength. The blood glucose measurement device according to claim 1.

3. The first photodetector includes a first light detection region and a first optical filter provided on the first light detection region and having a first transmission wavelength range of 460 nm to 535 nm; the second photodetector includes a second light detection region and a second optical filter provided on the second light detection region and having a second transmission wavelength range of 580 nm or more; the calculation unit calculates the blood glucose level of the living body based on the intensity of the transmitted light that has passed through the first optical filter and is detected by the first light detection region and the intensity of the transmitted light that has passed through the second optical filter and is detected by the second light detection region. The blood glucose measurement device according to claim 1.

4. The light detection unit further includes a third photodetector having a third detection wavelength range of 500 nm to 600 nm; the calculation unit calculates the pulse of the living body based on the intensity of the transmitted light detected by the third photodetector. The blood glucose measurement device according to claim 1.

5. The third photodetector includes a third light detection region and a third optical filter provided on the third light detection region and having a third transmission wavelength range of 500 nm to 600 nm. The arithmetic unit calculates the pulse of the living body based on the intensity of the transmitted light that has passed through the third optical filter and has been detected by the third light detection region. The blood glucose measurement device according to claim 4. **Claim 6** The first photodetector is each of a plurality of first photodetectors. The second photodetector is each of a plurality of second photodetectors. Each of the plurality of first photodetectors and each of the plurality of second photodetectors are alternately arranged so as to surround the light output unit. The blood glucose measurement device according to claim 1. **Claim 7** The green light source is each of a plurality of green light sources. Each of the plurality of green light sources is arranged so as to surround the light detection unit. The blood glucose measurement device according to claim 1.

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