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

Smart Rings and Smart Ring Systems

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

[0002] Photoplethysmography is a method for detecting changes in the volume of blood in capillaries caused by perfusion using a 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 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 (see, for example, 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, which use two wavelength light sources, 630-690 nm and 810-990 nm, 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 the 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 reflective diffuse method is more susceptible to external disturbances than the transmissive method. The reflective diffuse 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 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 transmissive 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.

[0010] U.S. Patent No. 10,893,833 (U.S. Patent Application Publication No. 2018 / 0103902)

[0011] For example, in the device described in Patent Literature 1, an appropriate light-emitting element or light-receiving element is selected 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.

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

[0014] Furthermore, it is preferable that a 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] The device may further include 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 being arranged to surround the second photodetector, a second angle formed by the position where the first light source is arranged, the center point, and the position where the second photodetector is arranged is greater than 60° and less than 105°, and the signal obtained from the photodetector with the highest received light intensity may be selected to acquire 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 may be an LED array light source composed of a plurality of LEDs having different peak wavelengths, and the first and second photodetectors may have wavelength ranges within which they have light sensitivity that include the different peak wavelengths.

[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] The finger may further include a second light source that illuminates the finger via a fourth optical element, wherein a fourth central angle formed by the base point, the center point, and a position where the second light source is disposed is greater than a first angle obtained by adding a fifth central angle formed by the first light source, the center point, and a position where the first photodetector is disposed to the second central angle, and is greater 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 a position where the second photodetector is disposed 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.

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

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

[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 Figures 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 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. The smart ring 10 acquires a volume pulse wave acquired from a PD with a high light receiving intensity among photodetectors (PDs) 40, 41. The smart ring 10 then accurately calculates the user's heart rate, blood oxygen concentration, body surface temperature, and other information from the acquired volume pulse wave. Since the 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, and so on, 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 Figures 1A, 1B, and 2, the smart ring 10 has optical elements 50 and 51, which are arranged to surround the light source 30 and PDs 40 and 41, respectively, protruding 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 curved surfaces) on the side where the user's finger 200 is inserted in a typical ring that does not have the light source 30, PDs 40 and 41, or 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 Figure 2 as not protruding for clarity. In addition, 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] (Configuration of smart ring 10) Externally, smart ring 10 has 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 made of metal, such as titanium, and is a ring with a roughly U-shaped cross section. It is integrated with the inner housing 22 to form the exterior 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 positioned in their respective 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 part may be recessed or flat, or there may be a mixture of protruding and non-protruding parts.

[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 disposed at a position that is point-symmetric with respect to a base point BP at the end of the +y direction inside the housing 20 and an end of the −y direction inside the housing 20, with the center point C of the ring hole 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 ends of the light-incident or light-exiting parabolic focusing surfaces 54 of the optical elements 50 and 51 coincide with the starting points 55 of the parabolic curves of the mirrors. 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 focus the light emitted by the light source 30, 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 include a main body 52, an attachment portion 53, a focusing surface 54, and a starting point 55. A hole penetrates the center of the main body 52, and a mounting portion 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 portion 53. The light-collecting surface 54 is formed by a parabolic surface function x ２ 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 in the XY plane and the ZY plane passes as close as possible to light-emitting unit 35 of light source 30, thereby keeping the Y-direction dimensions of optical elements 50 and 51 small.

[0036] The substrate 60 is disposed across both ends of the substantially U-shaped portion of the outer housing 21. 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 during which the light receiving intensity of the PD is measured, a signal collection period during which measured values ​​are acquired 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 uses the light source 30 as a light source and photodetectors 40 and 41 as light-receiving elements to detect the user's volume pulse wave. The gyro sensor 142 measures tilt and the user's exercise amount. The acceleration sensor 143 is used, for example, to calculate the pace while running. The temperature sensor 144 measures the user's body temperature, outside temperature, etc. 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, etc. 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, via 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 functions 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 and 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 (PD 40 in the second embodiment). １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ When the smart ring 10 is inserted on the user's finger 200, the PD control unit 112 controls the ON / OFF of the PDs 40 and 41 (PD 40 in the second embodiment). １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ ) is driven. The PD control unit 112 drives either one of the light sources 30 and 31 (PD 40 in the second embodiment). １ , 40 ２ , …, 40 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 host device 300 can view, analyze, and the like 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), a router, or the like.

[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, the smart ring 10 has a light source 30 disposed on the inner housing 22 opposite the base point BP, passing through the ring hole center point C from the base point BP on the inner housing 22 side of the decorative portion 23, which is the circumferential center of the smart ring 10. Here, the angle formed by the line segment connecting the base point BP, the ring hole center point C, and the PD40 (front view, clockwise; the same applies to subsequent angles) is θ1, the angle formed by the line segment connecting the base point BP, the ring hole center point C, and the light source 30 is θ2 (= 180°), and the angle formed by the line segment connecting the base point BP, the ring hole center point C, and the PD41 is θ3. The PD40 is positioned so that the angle θ2 - θ1 formed by the line segment connecting the light source 30, the ring hole center point C, and the PD40 is a predetermined value in the range of 60° < θ2 - θ1 < 105°. The PD41 is positioned so that the angle θ3-θ2 formed by the line segment connecting the light source 30, the ring hole center point C, and the 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] (Method for Acquiring Volume Pulse Wave by 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 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 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 / 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 true (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. If the user removes the smart ring 10 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, terminate the signal acquisition process 1 (step S7; Yes); if not (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, preventing the smart ring 10 from rotating circumferentially around 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. This allows accurate measurement of the volume pulse wave even when the smart ring 10 rotates circumferentially around the user's finger 200 while working, doing housework, exercising, etc.

[0061] Second Embodiment As shown in FIGS. 8A and 8B, in the second embodiment, the smart ring 11 has N PDs 40 instead of the two PDs 41 and 42 in the first embodiment. １ , 40 ２ , …, 40 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 has a different peak wavelength λ １ , λ ２ , …, λ ｎ The optical fiber has a plurality of LEDs with a peak wavelength of at least between 500-550 nm, between 600-800 nm, and between 900-1000 nm.

[0063] PD40 １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ The angle formed by the base point BP, the ring hole center point C, and each PD is θ １ , θ ２ , …, θ Ｎ－１ , θ ＮThe angle formed by the base point BP, the center point C of the ring hole, and the light source 31 is θ Ｌ Also, θ １ <θ ２ <…<θ Ｌ <…<…<θ Ｎ－１ , <θ Ｎ In the smart ring 11, θ Ｌ -θ １ , θ Ｌ -θ ２ , θ Ｌ -θ ２ , …, θ Ｌ -θ Ｎ－１ , θ Ｌ -θ Ｎ , and the absolute values ​​thereof are greater than 60° and less than 105°, respectively (note that in FIGS. 8A and 8B, the light source 31 and the PD are also arranged at positions less than 60° and greater than 105° for ease of viewing the figures). The other configurations are the same as those of the first embodiment.

[0064] As shown in Figure 9, signal acquisition process 2, which is performed 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] (Method of Acquiring Volume Pulse Wave by Smart Ring 11) 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 outputs light having a predetermined wavelength, in this embodiment, at least one of different peak wavelengths λ 1 having a peak wavelength between 500-550 nm, 600-800 nm, and 900-1000 nm. １ , λ ２ , …, λ ｎ (Step S11).

[0067] In accordance with the driving of the light source 31, the PD control unit 112 controls the PD 40 １ , 40 ２ , …, 40 Ｎ－１ , 40 ＮThe light emitted from the light source 31 is transmitted through the soft tissue of the user's finger 200 and diffusely reflected by the PD 40. １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ The measurement unit 113 receives the light at the PD40 １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ Received light intensity T １ , T ２ , ..., T Ｎ－１ , T Ｎ is measured during the received light intensity measurement period (step S12).

[0068] The selection and collection unit 114 １ , T ２ , ..., T Ｎ－１ , T Ｎ The PD that shows the maximum received light intensity compared with ＭＡＸ (step S13), and during the signal acquisition period, PD ＭＡＸ and transmits the signals to the host device 300. Also, the PDs other than the PD that showed the maximum received light intensity during the received light intensity measurement period are stopped (step S14).

[0069] Proceed to step S15. If the user removes the smart ring 11 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, terminate the signal acquisition process 2 (step S15; Yes); if not (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 PD 40 １ , 40 ２ , …, 40 Ｎ－１ , 40 Ｎ Since the angle formed by the light source 31 and the PD 40 is greater than 60° and less than 105°, the AC / DC ratio can be improved. １ , 40 ２ , …, 40 Ｎ－１ , 40 ＮThe optical elements 50, 51, which are arranged to surround the finger 200, protrude so as to press against the user's finger 200, thereby preventing the smart ring 11 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 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 when the smart ring 11 rotates in the circumferential direction of the ring 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 preventing the smart ring 11's rechargeable battery 162 from being depleted.

[0071] 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 having different peak wavelengths λ １ , λ ２ , …, λ ｎ The light sources 31 and 32 have a plurality of LEDs each having a peak wavelength of at least 500-550 nm, two LEDs each having a peak wavelength of 600-800 nm, and one LED each having a peak wavelength of 900-1000 nm. As shown in FIG. 12, the light sources 31 and 32 are pulse-driven and controlled so that their pulse-on and pulse-off times are reversed, and they emit light alternately.

[0072] As shown in FIGS. 11A and 11B, in the sensor unit 15, the angle Φ formed by the base point BP, the ring hole center point C, and the PD 40 is １ The angle Φ formed by the light source 31, the center point C of the ring hole, and the PD 40 Ｌ１ The angle formed by the base point BP, the center point C of the ring hole, and the light source 32 is ２ is less than Φ 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 of 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] (Method of Acquiring Volume Pulse Wave by Smart Ring 12) 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 λ 1 , λ 2 , λ 3 , λ 4 , λ 5 , λ 6 , λ 7 , λ 8 , λ 9 , λ 10 , λ 20 , λ 31 , λ 40 , λ 51 , λ 62 , λ 73 , λ 84 , λ 95 , λ 106 , λ 110 , λ 120 , λ 130 , λ 140 , λ 150 , λ 160 , λ 170 , λ 180 , λ 190 , λ 210 , λ 220 , λ 230 , λ 240 , λ 250 , λ 260 , λ 270 , λ 280 , λ 290 , λ 310 , λ 320 , λ 330 , λ 340 , λ 350 , λ 360 , λ 370 , λ 380 , λ 390 , λ 410 , λ 420 , λ 430 , λ 440 , λ 450 , λ 460 , λ 470 , λ 480 , λ 490 , λ 510 , λ 520 , λ 530 , λ １ , λ ２ , …, λ ｎ (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 having the larger received light intensity is stopped. Ｈ (step S24) and transmits the signals to the host device 300.

[0078] Proceed to step S25. If the user removes the smart ring 12 from the finger 200 or the remaining charge of the rechargeable battery 162 is insufficient, terminate the signal acquisition process 3 (step S25; Yes); if not (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°, improving the AC / DC ratio. Furthermore, the optical elements 50 and 51, which are arranged to surround the light sources 31 and 32 and the PDs 40 and 41, protrude so as to press against the user's finger 200, preventing the smart ring 12 from rotating in the circumferential direction of the ring 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 rotated at regular intervals. 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. Furthermore, 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] [Modifications] In the above embodiments, the 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. The 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 composed 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 combinations 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 is a lithium polymer battery, but it may be 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), or LoRaWAN (registered trademark), or it may perform wireless communication based on other standards.

[0088] In each of the above embodiments, the sensor unit 140 has 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, 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 center point C of the ring hole 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 in 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.

[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 arranged to surround the light source and the PD, are described below.

[0093] Optical simulation was used to optimize the structure of the smart ring according to each of the above embodiments. The simulation used Trace Pro (registered trademark), an optical simulation tool manufactured by Lambda Research Corporation in the United States. 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) V. v. Tuchin, “Light scattering study of tissues”, Phys. -Usp. 40(5), 495-515 (1997).

[0095] (Reference document 2) A. N. Bashkatov, D. M. Zhestkov, E. A. Genina, and V. V. Tuchin, “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, V. S. 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 is therefore deformed to conform to the inner housing 22, and that a recess D is formed in the part that is pressed against the optical element 50 in particular.

[0098] Light with a near-infrared wavelength was emitted from the light source 30, and the intensity of the light that reached the PD 40 after multiple scattering within the tissue of the finger 200 was analyzed. The positional relationship between the light source 30 and the PD 40 was expressed by the angle θ formed by connecting the light source 30, the ring hole center point C, and the PD 40, using the ring hole center point C, which is the center of the circle when the ring hole of the smart ring 10 is considered as 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. For each of these two cases, the PD 40 was analyzed with and without the optical element 51 (four cases in total). To simplify the model, the analysis was performed assuming that the optical element 50 and the optical element 51 had the same shape. The PD 41 was also omitted for the sake of simplicity. 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] Here, 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] The following three points can be seen from FIGS.

[0104] 1. When θ is small (region similar to a reflection photoplethysmogram) The smaller θ, the closer the shape is to a reflection photoplethysmogram. Simulation results show that in this case, the intensity of the light reaching the PD 40 is high, but the amount of light reaching the PD 40 via the deep finger tissue where the artery 206 is located is extremely low. Therefore, this shape 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 (region similar to a transmission-type photoplethysmogram) The larger θ is, 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 need for high light emission intensity may make this unsuitable for smart rings, which require compact size, from the perspective of securing power. It is also estimated that the benefits of optical elements are limited in this region.

[0107] 3. When θ is intermediate between cases 1 and 2 (quasi-transmissive photoplethysmography region) A form that is neither the reflective type in case 1 nor the transmissive type in case 2 is called a quasi-transmissive type. The 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. In the region where 60°<θ<105°, it can be confirmed that the AC / DC ratio is significantly improved when an optical element is present. In a quasi-transmissive photoplethysmography 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.

[0109] REFERENCE SIGNS LIST 1 Smart ring system 10, 11, 12 Smart ring 15, 16 Sensor unit 20 Housing 21 Outer housing 22 Inner housing 23 Decorative part 24 Main surface 25 Recess 30, 31, 32 Light source 35 Light-emitting part 40, 40 １ , 40 ２ , …, 40 Ｎ, 41 Photodetector 50, 51 Optical element 52 Main body 53 Mounting portion 54 Light collecting surface 55 Starting point 60 Substrate 61 Charging IC 62 Power supply management IC 65 Hole 100 MCU 110 Control portion 111 Light source control portion 112 PD control portion 113 Measurement portion 114 Selection and collection portion 120 Memory portion 121 Setting memory portion 122 Measurement result memory portion 130 Communication portion 131 Communication device 140 Sensor portion 141 Multi-wavelength PPG sensor 142 Gyro sensor 143 Acceleration sensor 144 Temperature sensor 145 Millimeter wave sensor 146 Microwave sensor 147 Optical sensor 150 Notification portion 151 Notification device 160 Power supply portion 161 Power supply monitoring unit 162 Rechargeable battery 163 Charge receiver 200 Finger 201 Epidermis 202 Dermis 203 Subcutaneous fat 204 Proximal phalanx 205 Flexor tendon 206 Artery 207 Nerve 300 Host device 400 Charging device 401 Charge transmitter BP Base point C Ring hole center point

Claims

1. The finger-type hand-held device has a first light source that irradiates a finger through a first optical element, a first photodetector that receives light emitted from the first light source or another light source through 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, protrude from a main surface of the housing on the 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 relative to the finger. Smart ring.

2. a first angle formed by a position where the first light source is disposed, a center point of the ring hole, and a position where the first photodetector is disposed 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 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°; 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. the first, second and third optical elements each include an aspheric mirror that focuses the light; The smart ring of claim 3.

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 according to claim 4.

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 according to claim 4.

11. a second light source that illuminates the finger through a fourth optical element; 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; 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.