Smart Ring and Smart Ring System

Abstract

This smart ring (10) has: a first light source (30) which irradiates a finger (200) through a first optical element (50); a first photo detector (40) which receives light emitted from the first light source (30) or another light source through a second optical element (51) and acquires a volume pulse wave; and a housing (20) through which the finger (200) is inserted. The first and second optical elements (50, 51) are disposed so as to respectively surround the first light source (30) and the first photo detector (40) and protrude toward the finger (200) from a main surface on the side of the housing (20) where the finger (200) is inserted.

Description

[Technical Field]

[0001] The present invention relates to smart rings and smart ring systems. [Background technology]

[0002] Photoplethysmography is a method for detecting changes in the volume of blood in capillaries caused by perfusion using a volume pulse wave sensor consisting of an LED light source and a photodetector. The light source is an LED that emits light in the visible to near-infrared range. It is possible to detect volume pulse waves from changes in absorbance that accompany changes in the amount of hemoglobin in the blood vessels. Light from the LED light source is irradiated onto the skin, and the diffuse reflected light or transmitted light is measured.

[0003] By analyzing the volume pulse waves detected by photoplethysmography, pulse rate and blood oxygen saturation can be estimated. In addition, recent research has shown that it can also estimate blood pressure and blood sugar levels.

[0004] Pulse wave sensors are composed of inexpensive elements and are non-invasive. For this reason, they are used in many consumer products, such as smartphones, smartwatches, and wearable devices (e.g., Patent Document 1). Many of these devices calculate the pulse rate from the pulse wave detected using a light source with a wavelength of 500 nm to 600 nm.

[0005] Pulse wave sensors are also used in medical devices such as blood oxygen concentration meters (pulse oximeters), which use two wavelength light sources, 630-690nm and 810-990nm, to calculate the blood oxygen saturation level from the ratio of absorbance at each wavelength between oxygenated hemoglobin and deoxygenated hemoglobin.

[0006] A method for detecting blood glycated hemoglobin concentration using a volume sensor has also been proposed. Using a light source with three or four wavelengths in the wavelength range of 600 nm to 990 nm, the blood glycated hemoglobin concentration is calculated from the absorbance ratio of oxygenated hemoglobin, deoxygenated hemoglobin, and glycated hemoglobin.

[0007] Photoplethysmography can be broadly divided into two methods: the reflective diffuse method and the transmissive method. In the reflective diffuse method, light from an LED light source is irradiated onto the skin, and the diffused light reflected from the skin is detected by a photodetector. Therefore, the reflective diffuse method allows the volume pulse wave sensor to be applied anywhere on the body, such as the wrist or forehead. In the transmissive method, light is emitted from an LED light source, and the light that passes through biological tissue is detected by a photodetector on the skin surface on the back side of the light source. Therefore, it is used in places where the tissue is relatively thin, such as the fingertips. Attempts to use it on the earlobe have also been made.

[0008] The diffuse reflection method is more susceptible to external disturbances than the through-beam method. The diffuse reflection method detects the absorbance of hemoglobin in blood from terminal arterioles with a diameter of 17 to 26 microns that exist in the papillary dermis, and from arterioles with a diameter of 150 to 242 microns that exist at the junction between the dermis and subcutaneous tissue. The blood flow velocity and shear rate in these terminal arterioles are relatively easily reduced by external pressure, so the volume pulse waveform shape changes with external pressure. On the other hand, the through-beam method measures the absorbance of hemoglobin in blood from relatively large arterioles with a diameter of around 1 mm that are located deep in the subcutaneous tissue, so the effect of external pressure is small.

[0009] Based on the above fundamental background, in order to measure the volume pulse wave more accurately using photoplethysmography, a transmission method that can access large arterioles is desirable.In recent years, in addition to medical devices that measure the fingertip, there are also consumer products equipped with volume pulse wave sensors that target the base of the finger or the earlobe. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 10,893,833 (U.S. Patent Application Publication No. 2018 / 0103902) Summary of the Invention [Problem to be solved by the invention]

[0011] For example, the device described in Patent Document 1 selects an appropriate light-emitting element or light-receiving element depending on the distance between the sensor module and the part of the body worn by the user. However, after the light-emitting element or light-receiving element is selected, the distance between the device and the part of the body worn by the user may change due to the user's movement or the like, and the selected light-emitting element or light-receiving element may no longer be appropriate.

[0012] Therefore, an object of the present invention is to provide a smart ring and a smart ring system that can measure volume pulse waves with high accuracy. [Means for solving the problem]

[0013] In order to achieve the above object, a smart ring according to a first aspect of the present invention comprises: a first light source that irradiates a finger via a first optical element; a first photodetector that receives light emitted from the first light source or another light source via a second optical element and acquires a volume pulse wave; and a housing through which the finger is inserted; The first and second optical elements are arranged to surround the first light source and the first photodetector, respectively, and protrude from a main surface of the housing on the side where the finger is inserted, toward the finger.

[0014] Furthermore, it is preferable that the first angle formed by the position where the first light source is disposed, the center point of the ring hole, and the position where the first photodetector is disposed is greater than 60° and less than 105°.

[0015] a second photodetector that receives the light emitted from the first light source or another light source via a third optical element; the third optical element is disposed to surround the second photodetector; a second angle formed by a position where the first light source is disposed, the center point, and a position where the second photodetector is disposed is greater than 60° and less than 105°; It is advisable to select the signal obtained from the photodetector with the highest received light intensity to obtain the volume pulse wave.

[0016] The first, second and third optical elements may comprise aspherical mirrors that focus the light.

[0017] Preferably, the first, second, and third optical elements further include at least one of a lens, a filter, and a prism that condenses the light.

[0018] The first central angle formed by a predetermined base point on the inner surface of the smart ring, the center point, and the position where the first light source is located is preferably larger than the second central angle formed by the base point, the center point, and the position where the first photodetector is located, and smaller than the third central angle formed by the base point, the center point, and the position where the second photodetector is located.

[0019] the first light source is an LED array light source composed of a plurality of LEDs having different peak wavelengths; The first and second photodetectors preferably have wavelength ranges in which they are sensitive to light, the different peak wavelengths being included in the wavelength ranges.

[0020] The plurality of LEDs preferably includes one or more LEDs having a peak wavelength in the range of 500-550 nm, two or more LEDs having a peak wavelength in the range of 600-800 nm, and one or more LEDs having a peak wavelength in the range of 900-1000 nm.

[0021] It is preferable that the signal obtained from the photodetector with the highest received light intensity is selected every time a predetermined time elapses, and the volume pulse wave is acquired.

[0022] The aspherical mirror may be a parabolic mirror in which the end of the parabolic curved surface on the side where the light enters or exits coincides with the starting point of the parabolic curved surface of the mirror.

[0023] a second light source that illuminates the finger through a fourth optical element; The fourth central angle formed by the base point, the center point, and the position where the second light source is located is greater than a first angle obtained by adding a fifth central angle formed by the first light source, the center point, and the position where the first photodetector is located to the second central angle, and is also greater than a second angle obtained by adding a sixth central angle formed by the position where the second light source is located, the center point, and the position where the second photodetector is located to the second central angle.

[0024] The first and second light sources may have pulse-on times and pulse-off times that are opposite to each other.

[0025] A smart ring system according to a second aspect of the present invention comprises: the smart ring; and an electronic device that receives the volume pulse wave from the smart ring via wireless communication. [Effects of the Invention]

[0026] According to the present invention, the volume pulse wave can be measured with high accuracy. [Brief explanation of the drawings]

[0027] [Figure 1A] FIG. 1 is a perspective view of a smart ring according to an embodiment of the present invention. [Figure 1B] FIG. 2 is a side cross-sectional view of a smart ring according to an embodiment of the present invention. [Figure 2] 1 is a front cross-sectional view of a smart ring according to an embodiment of the present invention, with the inner housing omitted when worn on a finger. FIG. [Figure 3] 1 is a block diagram of a smart ring system according to an embodiment of the present invention. [Figure 4A] 1 is a perspective view of an optical element according to an embodiment of the present invention. [Figure 4B] 1 is a longitudinal sectional view of an optical element according to an embodiment of the present invention. [Figure 5A] 1 is a cross-sectional view of an optical element according to an embodiment of the present invention, cut along the XY plane, with the right half indicated by a dashed dotted line. [Figure 5B] 1 is a cross-sectional view of an optical element according to an embodiment of the present invention, cut along the ZY plane, with the right half indicated by a dashed dotted line. [Figure 6A] 1 is a front cross-sectional view of the smart ring according to the first embodiment, omitting the optical element. FIG. [Figure 6B] FIG. 2 is a side view of the smart ring according to the first embodiment, omitting the optical element. [Figure 7] 1 is a flowchart of a signal acquisition process 1 performed in the smart ring according to the first embodiment. [Figure 8A] FIG. 10 is a front cross-sectional view of a smart ring according to a second embodiment, omitting the optical element. [Figure 8B] FIG. 10 is a side view of the smart ring according to the second embodiment, omitting the optical element. [Figure 9] 10A and 10B are diagrams illustrating the drive timing of the PD and the light source of the smart ring according to the second embodiment. [Figure 10] 10 is a flowchart of a signal acquisition process 2 performed in a smart ring according to a second embodiment. [Figure 11A] FIG. 11 is a front cross-sectional view of a smart ring according to a third embodiment, omitting the optical element. [Figure 11B] FIG. 11 is a side view of the smart ring according to the third embodiment, omitting the optical element. [Figure 12] 10A and 10B are diagrams illustrating the drive timing of the PD and the light source of the smart ring according to the third embodiment. [Figure 13] 10 is a flowchart of a signal acquisition process 3 performed in a smart ring according to the third embodiment. [Figure 14] FIG. 10 is a cross-sectional side view of a smart ring according to a modified example of the present invention. [Figure 15] FIG. 10 is a cross-sectional side view of a smart ring according to another modified example of the present invention. [Figure 16A] FIG. 10 is a diagram showing the radiation distribution of a light source of a smart ring when no optical element is attached to the light source. [Figure 16B] 10A and 10B are diagrams showing the radiation distribution of a light source when an optical element is attached to the light source of a smart ring. [Figure 17] 10 is a diagram showing the intensity of light received by a PD depending on the positional relationship between the PD and a light source. FIG. [Figure 18] 10 is a diagram showing the AC / DC ratio of light received by a PD depending on the positional relationship between the PD and a light source. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] A smart ring system according to an embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the x, y, and z directions in the description follow the arrows in each drawing. Also, the same or equivalent parts are given the same reference numerals.

[0029] As shown in Figures 1A, 1B, 2, etc., the smart ring system 1 according to an embodiment of the present invention non-invasively measures the user's heart rate, blood oxygen concentration, body surface temperature, etc. using a smart ring 10 inserted on the user's finger 200.

[0030] [First embodiment] As shown in FIGS. 2 and 3 , a smart ring system 1 according to a first embodiment of the present invention includes a smart ring 10 inserted on a user's finger 200 and a host device 300 that wirelessly receives data related to the user's volume pulse wave acquired by the smart ring 10. The smart ring 10 acquires a volume pulse wave acquired from one of photodetectors (hereinafter referred to as PDs (Photo Detectors)) 40, 41 that receives light from a light source 30 that emits light of multiple wavelengths toward the user's finger 200 inserted in the smart ring 10, and calculates the user's heart rate, blood oxygen concentration, body surface temperature, etc. with high accuracy from the acquired volume pulse wave. Since a user wears the smart ring 10 during daily activities, the smart ring 10 may rotate around the finger 200 as the user works, does housework, exercises, etc., causing the light source 30 and the PDs 40, 41 to move to positions that are not suitable for measuring the volume pulse wave. To prevent this, as shown in FIGS. 1A, 1B, and 2, the optical elements 50 and 51 of the smart ring 10, which are arranged to surround the light source 30 and the PDs 40 and 41, respectively, protrude from the main surface 24 of the inner housing 22 on the side where the user's finger 200 is inserted toward the user's finger 200. Here, the main surface 24 refers to the portion or surface (including a curved surface) on the side where the user's finger 200 is inserted, in a typical ring that does not have the light source 30, the PDs 40 and 41, or the optical elements 50 and 51. Because the optical elements 50 and 51 protrude from the main surface 24, pressing the user's finger 200 allows them to adhere closely to the user's finger 200, maintaining the smart ring 10 fixed in a predetermined position on the user's finger 200 and preventing the smart ring 10 from slipping off. Although the optical element 51 actually protrudes from the main surface 24, it is depicted in FIG. 2 as not protruding for clarity. Furthermore, in the cross-sectional views of the smart ring 10 (or 11, 12) from FIG. 6A onwards, the optical elements 50, 51 themselves are omitted for ease of understanding and to make the drawings easier to see.

[0031] (Smart Ring 10 configuration) Externally, the smart ring 10 comprises a housing 20 that houses a light source 30 and PDs 40 and 41, a light source 30 that emits light having multiple peak wavelengths, PDs 40 and 41 that receive the light emitted by the light source 30, optical elements 50 and 51 that collect the light emitted by the light source 30, and a substrate 60 on which various electronic components are mounted.

[0032] The housing 20 includes an outer housing 21 that forms the exterior of the smart ring 10 and an inner housing 22 that forms the interior of the smart ring 10. The outer housing 21 is a metal ring, such as titanium, with a substantially U-shaped cross section, and is integrated with the inner housing 22 to form the outer shape of the smart ring 10. A decorative portion 23 is formed on a portion of the exterior of the outer housing 21. When the user inserts the smart ring 10 onto the finger 200, the decorative portion 23 is located on the back of the hand, enhancing the decorativeness of the smart ring 10 and making it easier for the user to position the smart ring 10 in a position suitable for measuring the volume pulse wave. The inner housing 22 is made of a transparent resin with high transmittance for light with wavelengths of 400-1000 nm. The inner housing 22 is formed inside the outer housing 21 with the light source 30, light-receiving elements 40, 41, optical elements 50, 51, and substrate 60 arranged in their predetermined positions within the outer housing 21. The inner housing 22 protrudes toward the center point C of the ring hole so as to cover the optical elements 50, 51, but the center of the protruding portion may be recessed or flat, or there may be a mixture of protruding and non-protruding portions.

[0033] The light source 30 is an LED (Light Emitting Device) and is surface-mounted on the substrate 60. The light source 30 has a peak wavelength between 400 and 1000 nm. The light source 30 is also one of the components of a multi-wavelength PPG (Photoplethysmography) sensor 141, which will be described later. The light source 30 is arranged at a position that is point-symmetric with respect to a base point BP at the +y-direction end inside the housing 20 and the -y-direction end inside the housing 20, with the ring hole center point C as the reference point.

[0034] The photodetectors 40 and 41 are light-receiving elements that receive light emitted from the light source 30 and transmitted and diffusely reflected by the soft tissue of the user's finger 200. In this embodiment, the photodetectors 40 and 41 are PIN-type photodiodes. The photodetectors 40 and 41 have light-receiving sensitivity in a wavelength range that includes the peak wavelength of the light emitted by the light source 30. The photodetectors 40 and 41 are one of the components of a multi-wavelength PPG sensor 141, which will be described later, and are mounted on the substrate 60.

[0035] The optical elements 50 and 51 are parabolic mirrors, a type of aspherical mirror, arranged on the substrate 60 to surround the light source 30 and the PDs 40 and 41. The optical elements 50 and 51 have a parabolic light-collecting surface 54, which is a parabolic curved surface, at an end on the light-incident or light-exiting side that coincides with a starting point 55 of the mirror's parabolic curve. When the light source 30 and the PDs 40 and 41 are in a predetermined positional relationship described below, the optical elements 50 and 51 collect the light emitted by the light source 30, thereby improving the accuracy of volume pulse wave acquisition. In this embodiment, the optical element 50 protrudes more toward the user's finger 200 inserted through the ring hole than the optical element 51. As shown in FIGS. 4A and 4B , the optical elements 50 and 51 have a main body 52, an attachment portion 53, a light-collecting surface 54, and a starting point 55. A hole penetrates the center of the main body 52, and a mounting part 53 is formed on one side of the hole, and a light-collecting surface 54 is formed on the other side of the hole. Either the light source 30 or the PD 40 or 41 is mounted on the mounting part 53. The light-collecting surface 54 is formed by a parabolic surface function x 2 =4·0.4·(y-0.4) is translated in the respective axial directions, resulting in a focal length f=0.4 mm. As shown in Figures 5A and 5B, focusing surface 54 is formed by setting starting point 55 on main body 52 so that the parabolic curved surface obtained by extending focusing surface 54 passes as close as possible to light-emitting unit 35 of light source 30 in both the XY and ZY planes, thereby keeping the Y-direction dimensions of optical elements 50 and 51 small.

[0036] The substrate 60 is disposed across the outer housing 21 so as to connect both ends of the substantially U-shaped portion. The light source 30, PDs 40 and 41, optical elements 50 and 51, and a charging IC (Integrated Circuit) 61 (described later) are disposed on the inner housing 22 side of the substrate 60. An MCU (Micro Computer Unit) 100 (described later), various sensor ICs, various sensor elements, and a power management IC 62 are mounted inside the recess of the substantially U-shaped portion of the substrate 60.

[0037] 3, in addition to the above configuration, the smart ring 10 includes a sensor unit 140, a notification unit 150, and a power supply unit 160. The MCU 100 also includes a control unit 110, a storage unit 120, and a communication unit .

[0038] The MCU 100 is a microprocessor-based controller IC. The MCU 100 is equipped with a microprocessor, inputs and outputs required for controlling the smart ring 10, and memory for storing programs and data.

[0039] The control unit 110 is composed of a CPU (Central Processing Unit) and the like, and by executing a program stored in the memory unit 120, realizes the functions of each unit (light source control unit 111, PD control unit 112, measurement unit 113, selection / collection unit 114) described below.

[0040] The storage unit 120 is composed of a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and includes a setting storage unit 121 and a measurement result storage unit 122. The ROM stores programs executed by the CPU of the control unit 110 and data required in advance for executing the programs. The RAM stores data that is created or changed during program execution.

[0041] The setting storage unit 121 stores various settings (for example, a light receiving intensity measurement period for measuring the light receiving intensity of the PD, a signal collection period for acquiring measured values ​​from the selected PD, etc.) which will be described later.

[0042] The measurement result storage unit 122 stores the measurement results measured using the various sensors included in the sensor unit 140. The stored measurement results are transmitted to the host device 300 via the communication unit 130 by wireless communication.

[0043] The communication unit 130 is a module for wireless communication with the host device 300. The communication unit 131 performs wireless communication with the host device 300 based on, for example, Bluetooth (registered trademark).

[0044] The sensor unit 140 includes a multi-wavelength PPG sensor 141, a gyro sensor 142, an acceleration sensor 143, a temperature sensor 144, a millimeter-wave sensor 145, a microwave sensor 146, and an optical sensor 147. The multi-wavelength PPG sensor 141 detects the user's volume pulse wave using the light source 30 as a light source and the photodetectors 40 and 41 as light-receiving elements. The gyro sensor 142 measures the tilt and the amount of exercise of the user. The acceleration sensor 143 is used, for example, to calculate the pace while running. The temperature sensor 144 measures the user's body temperature, the outside temperature, and the like. The millimeter-wave sensor 145 is used for motion detection and distance measurement functions. The microwave sensor 146 is used to measure the user's breathing, heart rate, body movement, and the like. The optical sensor 147 is used for (long-distance) distance measurement functions.

[0045] The notification unit 150 is used to notify the user when the remaining charge of the rechargeable battery 162 of the smart ring 10 falls below a predetermined level. The notification device 151 issues an alarm sound to notify the user when the remaining charge of the rechargeable battery 162 falls below a predetermined level.

[0046] The power supply unit 160 includes a power supply monitoring unit 161, a rechargeable battery 162, and a charge receiver 163. The power supply unit 160 charges the smart ring 10 from the charging device 400, for example, by NFC (Near Field Communication) wireless charging. The rechargeable battery 162 is a lithium polymer battery located inside a recess in the approximately U-shaped portion of the outer housing 21. The rechargeable battery 162 is wirelessly powered from the charge transmitter 401 of the charging device 400 via the power supply monitoring unit 161 and the charge receiver 163.

[0047] Next, a description will be given of the function of the control unit 110. The control unit 110 includes a light source control unit 111, a PD control unit 112, a measurement unit 113, and a selection / collection unit 114, and executes signal acquisition processes 1-3 and the like, which will be described later.

[0048] The light source control unit 111 controls the ON / OFF of the light sources 30 and 31 (the light source 31 will be described in the third embodiment). When the smart ring 10 (11, 12) is inserted on the user's finger 200, the light source control unit 111 causes the light source 30 (31) to emit light. The light source control unit 111 also stops one of the light sources 30 and 31 for a certain period of time.

[0049] The PD control unit 112 controls the PDs 40 and 41 (PDs 401, 402, . . . , 40 in the second embodiment). N-1 ,40 N When the smart ring 10 is put on the user's finger 200, the PD control unit 112 controls the ON / OFF of the PDs 40 and 41 (PDs 401, 402, ..., 40 in the second embodiment). N-1 ,40 N ), and the PD control unit 112 drives either one of the light sources 30 and 31 (PDs 401, 402, ..., 40 in the second embodiment). N-1 ,40 N (excluding the PD that received the maximum amount of light) is stopped for a certain period of time.

[0050] The measurement unit 113 measures the user's volume pulse wave, blood oxygen saturation, blood glycated hemoglobin concentration, etc. using various sensors of the sensor unit 140 , and stores the measurement results in the measurement result storage unit 122 .

[0051] The selection and collection unit 114 selects which PD to use for measurement based on the measurement results stored in the measurement result storage unit 122, and collects the measurement results from the selected PD.

[0052] (Other configurations) In this embodiment, the host device 300 is a smartphone. By downloading a dedicated app or the like, the user can view and analyze the volume pulse wave data received from the smart ring 10. The host device may also be an electronic device such as a tablet, a PC (Personal Computer), or a router.

[0053] The charging device 400 is a device for wirelessly charging the smart ring 10. The smart ring 10 can be charged by bringing the charging receiver 163 into contact with the charging transmitter 401.

[0054] (Structure of Smart Ring 10) As shown in Figures 6A and 6B, smart ring 10 has light source 30 disposed on the inner housing 22 opposite base point BP, passing through ring hole center point C from base point BP, which is the circumferential center of decorative portion 23 of smart ring 10. Here, the angle formed by the line segment connecting base point BP, ring hole center point C, and PD40 (front view, clockwise; the same applies to subsequent angles) is θ1, the angle formed by the line segment connecting base point BP, ring hole center point C, and light source 30 is θ2 (= 180°), and the angle formed by the line segment connecting base point BP, ring hole center point C, and PD41 is θ3. PD40 is disposed so that the angle θ2 - θ1 formed by the line segment connecting light source 30, ring hole center point C, and PD40 is a predetermined value in the range of 60° < θ2 - θ1 < 105°. PD41 is positioned so that the angle θ3-θ2 formed by the line segment connecting light source 30, ring hole center point C, and PD41 is a predetermined value in the range of 60°<θ3-θ2<105°. θ2-θ1=θ3-θ2. The basis for 60°<θ2-θ1<105° and 60°<θ3-θ2<105° will be explained in the examples below.

[0055] (How to obtain volume pulse waves using the Smart Ring 10) Signal acquisition process 1, which is executed by the smart ring 10 of the smart ring system 1 to acquire the volume pulse wave of the user with high accuracy, will be described with reference to FIG.

[0056] The smart ring 10 is inserted onto the user's finger 200, and the light source control unit 111 causes the light source 30 to emit light having a predetermined wavelength, in this embodiment, a peak wavelength between 400-1000 nm (step S1).

[0057] In synchronization with the driving of light source 30, PD control unit 112 drives PDs 40 and 41. Light emitted from light source 30 is transmitted and diffusely reflected by the soft tissue of user's finger 200 and is received by PDs 40 and 41. Measurement unit 113 measures the received light intensity T1 at PD 40 during a received light intensity measurement period (step S2), and also measures the received light intensity T2 at PD 41 during the same received light intensity measurement period (step S3).

[0058] The selection and collection unit 114 determines whether the received light intensity T1 is greater than the received light intensity T2 (step S4), and if T1>T2 (step S4; Yes), collects the signal of PD40 during the signal collection period (step S5) and transmits it to the host device 300, and if T1>T2 is not (step S4; No), collects the signal of PD41 during the signal collection period (step S6) and transmits it to the host device 300.

[0059] Proceed to step S7, and if the user removes the smart ring 10 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, end the signal acquisition process 1 (step S7; Yes), otherwise (step S7; No), return to step S1.

[0060] As described above, in the smart ring 10 used in the smart ring system 1, the angle formed by the light source 30, the ring hole center point C, and each of the PDs 40 and 41 is greater than 60° and less than 105°, thereby improving the AC (Alternate Current) / DC (Direct Current) ratio. Furthermore, the optical elements 50 and 51, which are arranged to surround the light source 30 and the PDs 40 and 41, protrude so as to press against the user's finger 200. This prevents the smart ring 10 from rotating in the circumferential direction of the ring even when the user is working, doing housework, exercising, etc. Furthermore, the smart ring system 1 periodically collects the signal of the PD that receives the higher intensity of light from the light source 30. Therefore, even if the smart ring 10 rotates in the circumferential direction of the ring around the user's finger 200 while working, doing housework, exercising, etc., the volume pulse wave can be measured accurately.

[0061] [Second embodiment] As shown in FIGS. 8A and 8B, in the second embodiment, the smart ring 11 has N PDs 401, 402, ..., 40 instead of the two PDs 41 and 42 in the first embodiment. N-1 ,40 N All the PDs are driven simultaneously to receive light. Another difference from the first embodiment is that the light source 31 is an LED array light source.

[0062] The light source 31 emits light having different peak wavelengths λ1, λ2, . . . , λ n The optical fiber cable includes a plurality of LEDs having a peak wavelength of at least between 500-550 nm, between 600-800 nm, and between 900-1000 nm.

[0063] PD401,402,…,40 N-1 ,40 N The angles formed by the base point BP, the ring hole center point C, and each PD are θ1, θ2, ..., θ N-1 , θ N In addition, the angle formed by the base point BP, the center point C of the ring hole, and the light source 31 is θ L Also, θ1<θ2<…<θ L <…<…<θ N-1 , <θ N In the smart ring 11, θ L -θ1, θ L -θ2, θ L -θ2, …, θ L -θ N-1 , θ L -θ N The absolute values ​​of , , and are greater than 60° and less than 105°, respectively (note that in Figs. 8A and 8B, for ease of viewing, light sources 31 and PDs are also placed at positions less than 60° and greater than 105°). The other configurations are the same as those of the first embodiment.

[0064] As shown in Figure 9, signal acquisition process 2 executed by smart ring 11 differs from the first embodiment in that, during the signal collection period, PDs other than the PD that showed the maximum light receiving intensity during the light receiving intensity measurement period are stopped.

[0065] (How to obtain volume pulse waves using the Smart Ring 11) The signal acquisition process 2 executed by the smart ring 11 of the smart ring system 1 will be described with reference to FIG.

[0066] The smart ring 11 is inserted on the user's finger 200, and the light source control unit 111 controls the light source 31 to emit light having predetermined wavelengths, in this embodiment, different peak wavelengths λ1, λ2, ..., λ having peak wavelengths at least between 500-550 nm, 600-800 nm, and 900-1000 nm. n The light having the above formula is emitted (step S11).

[0067] In accordance with the driving of the light source 31, the PD control unit 112 controls the PDs 401, 402, . . . , 40 N-1 ,40 N The light emitted from the light source 31 is transmitted and diffusely reflected by the soft tissue of the user's finger 200, and is applied to the PDs 401, 402, ..., 403. N-1 ,40 N The measurement unit 113 receives the light from the PDs 401, 402, ..., 40 N-1 ,40 N Received light intensity at T1, T2, ..., T N-1 , T N is measured during the received light intensity measurement period (step S12).

[0068] The selection and collection unit 114 selects T1, T2, ..., T N-1 , T N The PD that shows the maximum received light intensity compared to the MAX (step S13), and during the signal acquisition period, PD MAX The signals are collected and transmitted to the host device 300. In addition, the PDs other than the PD that exhibited the maximum received light intensity during the received light intensity measurement period are stopped (step S14).

[0069] Proceed to step S15, and if the user removes the smart ring 11 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, end the signal acquisition process 2 (step S15; Yes), otherwise (step S15; No), return to step S11.

[0070] As described above, in the smart ring system 1 of the second embodiment, the light source 31, the ring hole center point C, and the PDs 401, 402, . . . , 40 N-1 ,40 NThe angle formed by the light source 31 and the PDs 401, 402, ..., 40 is greater than 60° and less than 105°, so that the AC / DC ratio can be improved. N-1 ,40 N The optical elements 50, 51, which are arranged to surround the smart ring 11, protrude so as to press against the user's finger 200, so that the smart ring 11 can be prevented from rotating in the ring circumferential direction even when the user is working, doing housework, exercising, etc. Furthermore, the smart ring system 1 periodically collects signals from the PD with the highest light reception intensity from the light source 31 among N PDs. This allows for more accurate measurement of the volume pulse wave even if the smart ring 11 rotates in the ring circumferential direction on the user's finger 200 while the user is working, doing housework, exercising, etc. Furthermore, during the signal collection period, PDs other than the PD with the highest light reception intensity during the light reception intensity measurement period are stopped, thereby saving power consumption and suppressing the wear on the rechargeable battery 162 of the smart ring 11.

[0071] [Third embodiment] 11A and 11B, in the third embodiment, the smart ring 12 includes a sensor unit 15 including a light source 31 and a PD 40, and a sensor unit 16 including a light source 32 and a PD 41. The light sources 31 and 32 are LED array light sources, and emit light with different peak wavelengths λ1, λ2, ..., λ n The light sources 31 and 32 have multiple LEDs with peak wavelengths of at least 500-550 nm, two LEDs with peak wavelengths of 600-800 nm, and one LED with peak wavelengths of 900-1000 nm. As shown in Figure 12, the light sources 31 and 32 are pulse-driven and controlled so that their pulse-on and pulse-off times are reversed, causing them to emit light alternately.

[0072] As shown in FIGS. 11A and 11B, in the sensor unit 15, the angle Φ1 formed by the base point BP, the ring hole center point C, and the PD 40 is smaller than the angle Φ L1 is less than the angle Φ2 formed by the base point BP, the ring hole center point C, and the light source 32.L2 is the angle formed by the light source 32, the center point C of the ring hole, and the PD 41. L1 =Φ L2 <105°. The other configurations are the same as those in the first embodiment.

[0073] In the signal acquisition process 3 executed by the smart ring 12, as shown in FIG. 12, during the signal collection period, the PD with the larger received light intensity during the received light intensity measurement period is used. H The other PD L and shutting off the light source.

[0074] (How to obtain volume pulse waves using the Smart Ring 12) The signal acquisition process 3 executed by the smart ring 12 of the smart ring system 1 will be described with reference to FIG.

[0075] The smart ring 12 is inserted on the user's finger 200, and the light source control unit 111 interleaves pulse trains for the light source 31 of the sensor unit 15 and the light source 32 of the sensor unit 16 to generate light having different peak wavelengths λ1, λ2, ..., λ3 having peak wavelengths at least between 500-550 nm, 600-800 nm, and 900-1000 nm in this embodiment. n The light having the above formula is emitted (step S21).

[0076] In synchronization with the driving of light sources 31 and 32, PD control unit 112 drives PDs 40 and 41. Light emitted from light sources 31 and 32 is transmitted through and diffusely reflected by the soft tissue of user's finger 200, and is received by PDs 40 and 41. Measurement unit 113 measures received light intensities T3 and T4 at PDs 40 and 41 during a received light intensity measurement period (step S22).

[0077] The selection and collection unit 114 compares T3 and T4 and selects the PD with the greater received light intensity. H (step S23), and during the signal acquisition period, the other PD L The sensor unit with the larger received light intensity is stopped. HThe signals are collected (step S24) and transmitted to the host device 300.

[0078] Proceed to step S25, and if the user removes the smart ring 12 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, end the signal acquisition process 3 (step S25; Yes), otherwise (step S25; No), return to step S21.

[0079] As described above, in the smart ring system 1 of the third embodiment, the angle Φ formed by the light source 31, the ring hole center point C, and the PD 40 is L1 , and the angle Φ formed by the light source 31, the center point C of the ring hole, and the PD 40 L2 is greater than 60° and less than 105°, the AC / DC ratio can be improved. In addition, the optical elements 50, 51 arranged to surround the light sources 31, 32 and the PDs 40, 41 protrude so as to press against the user's finger 200, so that the smart ring 12 can be prevented from rotating in the ring circumferential direction even when the user is working, doing housework, exercising, etc. Furthermore, in the smart ring system 1, the PD with the greater light receiving intensity from the light source 31 or the light source 32 is periodically H Since the signal is collected, even if the smart ring 12 rotates around the circumference of the ring on the user's finger 200 while the user is working, doing housework, exercising, etc., the volume pulse wave can be measured with high accuracy. Also, during the signal collection period, the PD other than the PD with the larger received light intensity during the received light intensity measurement period is collected. L Since the sensor unit having the sensor is stopped, power consumption can be reduced and the consumption of the rechargeable battery 162 of the smart ring 12 can be suppressed.

[0080] [Variations] In each of the above embodiments, outer housing 21 is made of titanium, but it may be made of other metals such as surgical stainless steel, or may be made of ceramic, resin, wood, etc. Inner housing 22 is made of resin, but it may be made of metal or ceramic.

[0081] In each of the above embodiments, the light source 30 is an LED having multiple peak wavelengths, but it may also be an LED array light source consisting of multiple LEDs having different peak wavelengths, or any other light source that can emit light having different peak wavelengths.

[0082] In the above embodiments, the photodetectors 40 and 41 are PIN photodiodes, but they may be PN photodiodes or avalanche photodiodes, or may be photoconductive elements such as CdS or PbS.

[0083] In the above embodiments, the optical elements 50 and 51 are parabolic mirrors, but they may also be aspherical mirrors with parabolic, hyperbolic or ellipsoidal surfaces. They may also be lenses, filters, prisms, or a combination of these.

[0084] In each of the above embodiments, the optical element 50 arranged to surround the light source 30 protrudes more toward the user's finger 200 inserted into the ring hole than the optical element 51 arranged to surround the PDs 40, 41, but the protrusion amounts of all optical elements may be the same, or the optical element arranged to surround the PD may protrude more.

[0085] In the above embodiments, the power supply unit 160 performs NFC wireless charging, and the charging device 400 uses a lithium polymer battery, but it may use a lithium ion battery or other rechargeable battery. Alternatively, a non-rechargeable small battery may be used.

[0086] In each of the above embodiments, the MCU 100 has a control unit 110, a memory unit 120, and a communication unit 130, but the configuration of the MCU may be different from this, or a control unit, a memory unit, and a communication unit may be provided without using an MCU.

[0087] Furthermore, in each of the above embodiments, the communication device 131 performs wireless communication based on Bluetooth, but it may also perform wireless communication based on Wi-Fi (registered trademark), LoRaWAN (registered trademark), or other standards.

[0088] In each of the above embodiments, the sensor unit 140 has the multi-wavelength PPG sensor 141, the gyro sensor 142, the acceleration sensor 143, the temperature sensor 144, the millimeter wave sensor 145, the microwave sensor 146, and the optical sensor 147, but it may also have other sensors, or may not have some sensors other than the multi-wavelength PPG sensor 141.

[0089] In the first embodiment described above, the angle formed by the light source 30, PDs 41 and 42, and the ring hole center point C was θ2-θ1=θ3-θ2, but θ2-θ1 and θ3-θ2 may be different as long as the angles are greater than 60° and less than 105°.

[0090] In the above embodiments, the optical elements 50, 51 protrude from the main surface 24 of the inner housing 22. However, as shown in Fig. 14, the optical elements 50, 51 may be disposed in a recess 25 formed in the inner housing 22 so as to protrude from the recess 25, and a sealant 56 made of a transparent resin similar to that of the inner housing 22 may be filled in to cover the optical elements 50, 51. Alternatively, as shown in Fig. 15, the optical elements 50, 51 may be disposed in a hole 65 in the substrate 60 and a recess in the outer housing 21. A lens, a prism, or the like may be used instead of the sealant 56.

[0091] Furthermore, in the third embodiment, the smart ring 12 is equipped with two sensor units, but it may be equipped with three or more sensor units. [Example]

[0092] The experimental results for the PD's received light intensity versus the angle formed by the light source, the center point C of the ring hole, and the PD are described below. The results of four simulation patterns, with and without optical elements positioned to surround the light source and PD, are described below.

[0093] The structure of the smart ring according to each of the above embodiments was optimized by optical simulation. The simulation was performed using Trace Pro (registered trademark), an optical simulation tool manufactured by Lambda Research Corporation, USA. As shown in FIG. 2, the optical simulation assumed a state in which the smart ring 10 was inserted around the proximal phalanx 204 of a user's finger 200. The model included an outer housing 21, an inner housing 22, a light source 30 die (light-emitting area: 0.28 mm × 0.28 mm), a PD 40 die (light-receiving area: 1.5 mm × 1.5 mm), an epidermis 201, a dermis 202, subcutaneous fat 203, a proximal phalanx 204, a flexor tendon 205, an artery 206, and a nerve 207. The absorbance, scattering coefficient, and refractive index were defined for each model component, and the simulation was performed as a multiple scattering system. The respective optical constants were determined by referring to the following references.

[0094] (Reference 1) VvTuchin, “Light scattering study of tissues”, Phys.-Usp.40(5), 495-515(1997).

[0095] (Reference 2) ANBashkatov, DMZhestkov, EAGenina, and VVTuchin, “Immersion clearing of human blood in the visible and near-infrared spectral regions”, Opt. Spectrosc.98(4), 638-646 (2005).

[0096] (Reference 3) O. Zhernovava, VS Tuchin, and A. Douplik, “The refractive index of human hemoglobin in the visible range”, Phys. Med. Biol. 56(13), 4013-4021 (2011).

[0097] Here, it is assumed that the tissue of the finger 200 is compressed by the inner housing 22 of the smart ring 10 and therefore deforms to conform to the inner housing 22, and in particular, a recess D is formed in the part pressed against the optical element 50.

[0098] Light of near-infrared wavelength was emitted from light source 30, and the intensity of the light that reached PD40 after multiple scattering within the tissue of finger 200 was analyzed. The positional relationship between light source 30 and PD40 was expressed as the angle θ formed by connecting light source 30, ring hole center point C, and PD40, using ring hole center point C, which is the center of the circle when the ring hole of smart ring 10 is considered to be the circumference. Simulations were performed by changing θ from 45° to 105° in 15° increments.

[0099] The light source 30 was analyzed in two cases, with and without the optical element 50, and each of these two cases was analyzed with and without the optical element 51 in the PD 40 (four cases in total). To simplify the model, the analysis was performed assuming that the optical element 50 and the optical element 51 have the same shape. Also, to simplify the model, the PD 41 was omitted. For reference, the light radiation distribution when the light source 30 does not have the optical element 50 is shown in FIG. 16A, and the distribution when the light source 30 has the optical element 50 is shown in FIG. 16B. It can be seen that the light emitted by the light source 30 is focused toward 0° by the optical element 50.

[0100] The results of the optical simulation are shown in Figures 17 and 18. The horizontal axis of Figure 17 represents the angle θ formed between the light source 30, the center point C of the ring hole, and the PD 40, and the vertical axis represents the intensity of light received by the PD. The solid line represents the case where neither the light source 30 nor the PD 40 has an optical element, while the dotted line represents the case where only the PD 40 has an optical element. The dashed-dotted line represents the case where only the light source 30 has an optical element, and the broken line represents the case where both the light source 30 and the PD 40 have optical elements. In all four cases, it can be seen that the received light intensity decreases as θ increases. This is thought to be due to absorption by the skin tissue and subcutaneous tissue of the finger.

[0101] 18, the horizontal axis represents the angle θ formed between the light source 30, the center point C of the ring hole, and the PD 40, and the vertical axis represents the AC / DC ratio. The AC / DC ratio is defined as follows. AC / DC=I artery / I all

[0102] where I artery is the total intensity of the light emitted from the light source 30, passing through the artery, and reaching the PD 40, and I all is the sum of the intensities of all the light rays emitted from the light source 30 and reaching the PD 40.

[0103] Figures 17 and 18 reveal the following three points.

[0104] 1. When θ is small (area close to the reflective photoplethysmogram) The smaller θ, the closer the form is to a reflection photoplethysmogram. Simulation results show that, in this case, the intensity of the light reaching PD40 is high, but the amount of light reaching PD40 via the deep finger tissue where arteries 206 are present is extremely low. Therefore, this form is not suitable for measuring blood oxygen saturation. It is also clear that the effect of the optical element in this region is low.

[0105] 2. When θ is large (area close to the transmission photoplethysmogram) The larger the θ, the closer the form is to a transmission type photoplethysmogram.

[0106] The simulation results show that in this case, a large proportion of light rays reach the PD 40 via the deep tissue of the finger where the artery 206 is located, making it suitable for measuring blood oxygen saturation. However, the emission intensity must be increased, and from the perspective of securing power, this may not be suitable for a smart ring, which requires compact size. It is also estimated that the benefit of optical elements is small in this region.

[0107] 3. When θ is between cases 1 and 2 (quasi-transmission photoplethysmography region) A configuration that is neither reflective (1.) nor transmissive (2.) is called a quasi-transmissive type. Simulation results show that there is a trade-off between the received light intensity and the AC / DC ratio, so it is important to optimize θ according to the application. It can be confirmed that in the region where 60°<θ<105°, the AC / DC ratio is significantly improved when an optical element is present. In a quasi-transmissive photoplethysmographic sensor, the AC / DC ratio can be improved by adding an optical element to the light source and PD.

[0108] It should be noted that the present invention is susceptible to various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate examples of the present invention and do not limit the scope of the present invention. The above-described embodiments and modifications can be combined in any manner. Furthermore, excluding some of the constituent elements of an embodiment, if necessary, still falls within the scope of the technical idea of ​​the present invention. [Explanation of symbols]

[0109] 1. Smart Ring System 10,11,12 Smart Ring 15,16 Sensor unit 20 Case 21 Outer housing 22 Inner housing 23 Decoration Department 24 main surfaces 25 recess 30,31,32 light source 35 Light-emitting part 40,401,402,…,40 N ,41 Photodetector 50,51 Optical elements 52 Main body 53 Mounting part 54 Focusing surface 55 Starting point 60 boards 61 Charging IC 62 Power management IC 65 holes 100 MCU 110 control section 111 Light source control unit 112 PD control unit 113 Measuring section 114 Selection and Collection Department 120 Storage section 121 Setting memory section 122 Measurement result storage section 130 Communications Department 131 Communication equipment 140 Sensor unit 141 Multi-wavelength PPG sensor 142 Gyro Sensor 143 Acceleration Sensor 144 Temperature Sensor 145 mmWave sensor 146 Microwave Sensor 147 Optical Sensor 150 Information Department 151 Alarm device 160 Power supply section 161 Power supply monitoring unit 162 Rechargeable battery 163 Charging Receiver 200 fingers 201 Epidermis 202 Dermis 203 Subcutaneous fat 204 Proximal phalanx 205 Flexor Tendon 206 Arteries 207 Nerves 300 host devices 400 Charging device 401 Charging Transmitter BP base point C Ring hole center point

Claims

1. A device comprising: a first light source which illuminates a finger through a first annular optical element; a first photodetector which receives light emitted from the first light source or another light source through a second annular optical element and acquires a volume pulse wave; a housing through which the finger is inserted; and a transparent resin sealing body which fixes the first and second optical elements to the housing; the first light source and the first photodetector are disposed in through holes of the first and second optical elements; the first and second optical elements are arranged to surround the first light source and the first photodetector, respectively, and protrude from a main surface of the housing on a side through which the finger is inserted toward the finger, the finger is pressed against the sealing body covering the first and second optical elements to bring the sealing body into close contact with the finger, and rotation of the housing relative to the finger is suppressed via the sealing body; the first and second optical elements are aspheric mirrors having parabolic curved surfaces formed in the through holes to condense the light; Smart ring.

2. a first angle formed by a position where the first light source is arranged, a center point of a ring hole through which the finger is inserted, which is formed in the housing, and a position where the first photodetector is arranged is greater than 60° and less than 105°; The smart ring of claim 1.

3. a second photodetector that receives the light emitted from the first light source or another light source via an annular third optical element; the third optical element is disposed to surround the second photodetector, a second angle formed by a position where the first light source is disposed, the center point, and a position where the second photodetector is disposed is greater than 60° and less than 105°; A signal obtained from the photodetector with the highest light receiving intensity is selected to obtain a volume pulse wave. The smart ring according to claim 2.

4. A device comprising: a first light source which illuminates a finger through a first annular optical element; a first photodetector which receives light emitted from the first light source or another light source through a second annular optical element and acquires a volume pulse wave; a second photodetector which receives the light emitted from the first light source or another light source through a third annular optical element; and a housing through which the finger is inserted; the first light source and the first photodetector are disposed in through holes of the first and second optical elements, respectively; the first and second optical elements are arranged to surround the first light source and the first photodetector, respectively, protrude from a main surface of the housing on a side through which the finger is inserted toward the finger, press against the finger to come into close contact with the finger, and suppress rotation of the housing with respect to the finger; a first angle formed by a position where the first light source is disposed, a center point of a ring hole through which the finger is inserted, which is formed in the housing, and a position where the first photodetector is disposed is greater than 60° and less than 105°; the second photodetector is disposed in a through hole of the third optical element; the third optical element is disposed to surround the second photodetector, a second angle formed by a position where the first light source is disposed, the center point, and a position where the second photodetector is disposed is greater than 60° and less than 105°; the first, second and third optical elements are parabolic mirrors, each of which has a parabolic curved surface formed in the through hole, the end of which is on the side where the light is incident or the end of which is on the side where the light is emitted, coinciding with a start point of the parabolic curved surface of the mirror; Smart ring.

5. The first, second and third optical elements further include at least one of a lens, a filter and a prism that condenses the light. The smart ring of claim 3.

6. a first central angle formed by a predetermined base point on an inner surface of the smart ring, the center point, and a position where the first light source is disposed is larger than a second central angle formed by the base point, the center point, and a position where the first photodetector is disposed, and is smaller than a third central angle formed by the base point, the center point, and a position where the second photodetector is disposed; The smart ring of claim 5.

7. the first light source is an LED array light source composed of a plurality of LEDs having different peak wavelengths; The first and second photodetectors include the different peak wavelengths in their light sensitivity wavelength ranges. The smart ring of claim 5.

8. The plurality of LEDs include one or more LEDs having a peak wavelength in the range of 500-550 nm, two or more LEDs having a peak wavelength in the range of 600-800 nm, and one or more LEDs having a peak wavelength in the range of 900-1000 nm. The smart ring of claim 7.

9. every time a predetermined time has elapsed, a signal obtained from a photodetector having the highest light receiving intensity is selected to obtain a volume pulse wave; The smart ring of claim 8.

10. The aspheric mirror is a parabolic mirror whose parabolic curved surface has an end on the side where the light is incident or exits, the end coinciding with the start point of the parabolic curved surface of the mirror. The smart ring of claim 1.

11. Further comprising a second light source that illuminates the finger through an annular fourth optical element; the second light source is disposed in a through hole of the fourth optical element; the fourth optical element is disposed to surround the second light source, the fourth optical element is an aspheric mirror having a parabolic curved surface formed in the through hole for collecting the light, a fourth central angle formed by the base point, the center point, and the position where the second light source is disposed is larger than a first angle obtained by adding a fifth central angle formed by the first light source, the center point, and the position where the first photodetector is disposed to the second central angle, and is also larger than a second angle obtained by adding a sixth central angle formed by the position where the second light source is disposed, the center point, and the position where the second photodetector is disposed to the second central angle; A signal obtained from the photodetector having the highest light receiving intensity is selected from the combination of the two light sources and the two photodetectors to obtain a volume pulse wave. The smart ring of claim 6.

12. The first and second light sources have opposite pulse-on and pulse-off times. The smart ring of claim 11.

13. A smart ring according to any one of claims 1 to 12; and an electronic device that receives the volume pulse wave from the smart ring via wireless communication. Smart Ring System.

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