Sensing devices and device sets

Abstract

The present invention improves the S / N ratio of a sensing device that measures bioinformation from a finger.　A sensing device (10) comprises a non-flexible housing (11) that can be mounted on a finger (80) and a biosensor that measures bioinformation for a user from the finger (80). The housing (11) has an inner circumferential surface (12) that faces the belly (81), the back (82), an outside surface (83), and an inside surface (84) of the finger (80). When the housing (11) has been mounted on the finger (80), the biosensor is arranged at the inner circumferential surface (12) so as to face the belly (81) of the finger (80). In a cross-section of the inner circumferential surface (12), a first distance (D1) that is between the portion (15) of the inner circumferential surface (12) that faces the belly (81) of the finger (80) and the portion (16) of the inner circumferential surface (12) that faces the back (82) of the finger (80) is shorter than a second distance (D2) that is between the portion (17) of the inner circumferential surface (12) that faces the outside surface (83) of the finger (80) and the portion (18) of the inner circumferential surface (12) that faces the inside surface (84) of the finger (80).

Description

[Technical Field]

[0001] The present invention relates to a sensing device and a device set. [Background technology]

[0002] A pulse wave signal is a waveform representing changes in blood vessel volume that occur as the heart pumps blood through the blood vessels. A sensor that detects these volume changes is called a pulse wave sensor. Photoplethysmography sensors that measure pulse wave signals have been put to practical use. A photoplethysmography sensor includes a light-emitting element that irradiates light of a specific wavelength onto the user's body surface and a light-receiving element that receives light reflected or transmitted within the user's body. Known sensing devices that measure pulse wave signals from a user's finger include those that incorporate a photoplethysmography sensor in a ring-shaped attachment portion that can be worn on the user's finger. Known sensing devices of this type include those with a ring-shaped attachment portion that has a circular cross-section and is made of a non-flexible material, and those with a non-circular cross-section and is made of a flexible material. Patent Document 1 (Patent Document 1) describes an example of a sensing device with a ring-shaped attachment portion that has a non-circular cross-section and is made of a flexible material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 068465 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the thickness of a human finger (the distance between the pad and dorsum of the finger) is shorter than the width of the finger (the distance between the outer and inner surfaces of the finger), if the cross section of the ring-shaped attachment part worn on the user's finger is circular and the attachment part is made of a non-flexible material, a gap will form between the attachment part and the finger. If such a gap occurs, the photoplethysmographic sensor cannot fit tightly against the finger, which causes a decrease in the signal-to-noise ratio.

[0005] On the other hand, if the ring-shaped attachment part worn on the user's finger is made of a flexible material, the degree of deformation of the attachment part when worn on the finger will vary depending on the thickness of the user's finger, and therefore the distance between the light-emitting element and light-receiving element of the photoplethysmographic sensor will also vary depending on the thickness of the user's finger.It is desirable to maintain the distance between the light-emitting element and light-receiving element of the photoplethysmographic sensor at an optimal distance depending on the wavelength, regardless of the thickness of the user's finger.

[0006] Therefore, an object of the present invention is to solve the above-mentioned problems and improve the signal-to-noise ratio of a sensing device. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention The device set is a device set including a plurality of sensing devices, each of which is a non-flexible housing configured to be wearable on a user's finger, the housing having an inner circumferential surface that faces the pad, dorsum, outer surface, and inner surface of the finger when the housing is worn on the finger, and a biosensor that measures biometric information of the user from the finger, the biosensor being arranged on the inner circumferential surface so that the biosensor faces the pad of the finger when the housing is worn on the finger, and a cross section of the inner circumferential surface having a portion of the inner circumferential surface that faces the pad of the finger and a portion of the inner circumferential surface that faces the dorsum of the finger. a first distance between a portion of the inner circumferential surface facing the outer surface of the finger and a portion of the inner circumferential surface facing the inner surface of the finger is shorter than a second distance between a portion of the inner circumferential surface facing the inner surface of the finger, the first distance and the second distance of the inner circumferential surface of one sensing device among the plurality of sensing devices are different from the first distance and the second distance of the inner circumferential surface of another sensing device among the plurality of sensing devices, the biosensor includes a pulse wave sensor including a light-emitting element and a light-receiving element, and the distance between the light-emitting element and the light-receiving element of each sensing device is the same. [Effects of the Invention]

[0008] According to the sensing device of the present invention, by making the first distance shorter than the second distance, it is possible to increase the adhesion between the pad of the finger and the biosensor and improve the signal-to-noise ratio of the biosensor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram illustrating a hardware configuration of a sensing device according to an embodiment of the present invention. [Figure 2] 1 is an explanatory diagram illustrating an external configuration of a sensing device according to an embodiment of the present invention. [Figure 3]1 is an explanatory diagram illustrating an external configuration of a sensing device according to an embodiment of the present invention. [Figure 4] 1 is an explanatory diagram illustrating an external configuration of a sensing device according to an embodiment of the present invention. [Figure 5] FIG. 2 is an explanatory diagram showing a cross-sectional structure of a housing of a sensing device according to an embodiment of the present invention. [Figure 6] FIG. 2 is a partial exploded view of a sensing device according to an embodiment of the present invention. [Figure 7] FIG. 2 is a partially enlarged cross-sectional view of a housing of a sensing device according to an embodiment of the present invention. [Figure 8] 10 is a graph showing measurement results of the SN ratio versus the distance between the light emitting element and the light receiving element according to an embodiment of the present invention. [Figure 9] FIG. 1 is an explanatory diagram illustrating a configuration of a device set according to an embodiment of the present invention. [Figure 10] FIG. 2 is an explanatory diagram showing a cross-sectional structure of a housing of a sensing device according to an embodiment of the present invention. [Figure 11] FIG. 2 is an explanatory diagram showing a cross-sectional structure of a housing of a sensing device according to an embodiment of the present invention. [Figure 12] FIG. 2 is an explanatory diagram showing a cross-sectional structure of a housing of a sensing device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, the same reference numerals denote the same components, and redundant description will be omitted.

[0011] 1 is an explanatory diagram showing the hardware configuration of a sensing device 10 according to an embodiment of the present invention. The sensing device 10 includes a biosensor 21 that measures biometric information from a user's finger, a control circuit 22 that controls the operation of the biosensor 21, a communication module 23 that transmits the measurement results of the biosensor 21 to an external computer via a wireless line or a wired circuit, and a battery 24 that supplies power to the control circuit 22 and the communication module 23. The biosensor 21, the control circuit 22, and the communication module 23 are mounted on a circuit chip 20.

[0012] The biosensor 21 may include, for example, one or more of a pulse wave sensor (a photoplethysmographic sensor or a piezoelectric pulse wave sensor), an oxygen saturation sensor, and a temperature sensor. For example, a reflective photoplethysmographic sensor irradiates the user's body surface with infrared light, red light, or green wavelength light, and measures the light reflected from the user's body surface using a photodiode or phototransistor. Oxygenated hemoglobin is present in arterial blood, and has the property of absorbing incident light. Therefore, a pulse wave signal can be measured by sensing the blood flow rate (changes in blood vessel volume) that changes with the heartbeat over time.

[0013] For example, pulse wave feature values ​​can be calculated from a pulse wave signal measured by a pulse wave sensor, and blood pressure, blood glucose level, vascular resistance, blood flow, or arteriosclerosis level can be estimated based on the pulse wave feature values. Furthermore, the heart rate (pulse rate) can be estimated by determining the period of fluctuation from the pulse wave signal. Furthermore, an index value of autonomic nervous function can be estimated by performing power spectrum analysis on the frequency components of the periodic fluctuation of the heart rate. The arterial blood oxygen saturation level can be estimated by determining the pulsation (amount of change) from the pulse wave signal measured by an oxygen saturation sensor. The user's body temperature can be estimated from the measurement value of a temperature sensor.

[0014] By using a pulse wave sensor, an oxygen saturation sensor, or a temperature sensor as the biosensor 21, it is possible to estimate bioinformation such as blood pressure, blood glucose level, vascular resistance, blood flow rate, arteriosclerosis level, heart rate, autonomic nervous function, arterial blood oxygen saturation level, or body temperature from the measurement results of the biosensor 21.

[0015] The control circuit 22 includes a processor, a memory, and an input / output interface. The control circuit 22 transmits the measurement results of the biosensor 21 to an external computer (for example, a mobile terminal such as a multi-function mobile phone or a tablet, or a cloud server) via the communication module 23. The external computer receives the measurement results of the biosensor 21 and performs processing to estimate bioinformation from the received measurement results. The control circuit 22 may also perform processing to estimate bioinformation from the measurement results of the biosensor 21 without transmitting the measurement results of the biosensor 21 to the external computer.

[0016] 2 to 4 are explanatory diagrams showing the external configuration of a sensing device 10 according to an embodiment of the present invention. The sensing device 10 includes a ring-shaped housing 11 that can be worn on a user's finger.

[0017] For example, in the example shown in Fig. 2, the housing 11 has a hollow cylindrical shape. In the example shown in Fig. 3, a slit is formed on the side of the housing 11 parallel to the direction in which the finger is inserted and removed, but the slit may not be present. In the example shown in Fig. 4, the housing 11 has a cylindrical shape (for example, the shape of a fingerstall) that fits over the user's finger. The bottom of the cylinder (the part that the fingertip comes into contact with) may or may not be present.

[0018] The housing 11 is made of a non-flexible material (for example, metal, ceramic, glass, or hard resin). Non-flexibility refers to the property of not easily bending or deforming even when subjected to an external force and maintaining its original shape. Specifically, for example, this means that when the housing is worn on a user's finger, the housing does not deform due to an external force applied as the finger deforms. Furthermore, by using a non-flexible material for the housing 11, it is possible to improve the design and durability compared to flexible materials such as rubber or sponge. This allows the user to easily wear the sensing device 10 at all times in their daily lives.

[0019] 5 is an explanatory diagram showing the cross-sectional structure of the housing 11 of the sensing device 10 according to an embodiment of the present invention. Here, the X and Y directions in the figure are orthogonal to the insertion / removal direction of the user's finger 80, and the Z direction is parallel to the insertion / removal direction of the user's finger 80. The cross section of the housing 11 in the figure is a cross section obtained by cutting the housing 11 along a plane parallel to the X and Y directions and perpendicular to the Z direction (the same applies to FIGS. 6, 7, 9, and 10). FIG. 6 shows a partial exploded view of the housing 11.

[0020] As shown in FIG. 5, the housing 11 has a hollow, annular inner surface 12 and an outer surface 13. Of the two surfaces constituting the inner surface 12, the surface facing the finger 80 is referred to as the front surface, and the reverse side of the front surface is referred to as the back surface. The surface of the inner surface 12 has portions 15, 16, 17, and 18 that face the pad 81, back 82, outer surface 83, and inner surface 84 of the finger 80, respectively, when the housing 11 is worn on the finger 80. As shown in FIG. 6, the portion 15 facing the pad 81 of the finger 80 has an opening (hole) 14 that penetrates the front and back of the inner surface 12, and the circuit chip 20 is fitted into the opening 14 from the back side of the inner surface 12. After being fitted into the opening 14, the circuit chip 20 is fixed to the inner surface 12 with an adhesive or adhesive tape. By fitting the circuit chip 20 into the opening 14 and then fixing it, it is possible to prevent the circuit chip 20 from shifting position when an external force acts on the circuit chip 20. The battery 24 is mounted on the back side of the inner circumferential surface 12. Reference numeral 25 denotes a wiring cable that connects the battery 24 and the circuit chip 20. The wiring cable 25 is also mounted on the back side of the inner circumferential surface 12 (the wiring cable 25 is not shown in FIG. 5). The biosensor 21 mounted on the circuit chip 20 is disposed on the inner circumferential surface 12 so as to face the pad 81 of the finger 80.

[0021] The pad 81 of the finger 80 is relatively softer than the back 82 and has more blood vessels. Because the above-mentioned biometric information is information measured from blood or blood vessels, the signal-to-noise ratio of the biosensor 21 can be increased by arranging the biosensor 21 on the inner circumferential surface 12 so that the biosensor 21 faces (is in close contact with) the pad 81 of the finger 80. In particular, when calculating pulse wave feature amounts from a pulse wave signal and estimating blood pressure, blood glucose level, vascular resistance, blood flow rate, or degree of arteriosclerosis based on the pulse wave feature amounts, a high signal-to-noise ratio is required of the biosensor 21. Therefore, by arranging the biosensor 21 so that the biosensor 21 faces (is in close contact with) the pad 81 of the finger 80, such a requirement can be met.

[0022] The cross section of the inner circumferential surface 12 is a cross section of the inner circumferential surface 12 between a portion 15 of the inner circumferential surface 12 facing the pad 81 of the finger 80 and a portion 8 2 is shorter than a second distance D2 between a portion 17 of the inner circumferential surface 12 facing the outer surface 83 of the finger 80 and a portion 18 of the inner circumferential surface 12 facing the inner surface 84 of the finger 80. The cross-sectional shape of the inner circumferential surface 12 is, for example, a substantially elliptical shape.

[0023] If the distance between the pad 81 and the dorsum 82 of the finger 80 is defined as the thickness of the finger 80, and the distance between the outer surface 83 and the inner surface 84 of the finger 80 is defined as the width of the finger 80, the statistical average of the ratio of the thickness to the width of the finger 80 is approximately 0.93 for both men and women. If the first distance D1 and the second distance D2 were set to the same value, a gap would be created between the pad 81 of the finger 80 and the biosensor 21, reducing the signal-to-noise ratio of the biosensor 21. Therefore, by making the length of the first distance D1 shorter than the length of the second distance D2 (for example, by setting the ratio of the first distance D1 to the second distance D2 equal to the statistical average of the ratio of the thickness to the width of the finger 80), the contact between the pad 81 of the finger 80 and the biosensor 21 can be improved. This can improve the signal-to-noise ratio of the biosensor 21. The ratio of the first distance D1 to the second distance D2 is preferably in the range of 0.85 to 0.95, for example.

[0024] Since the Y direction is parallel to the thickness direction of the inner diameter of the inner circumferential surface 12, the first distance D1 is the maximum value in the thickness direction of the inner diameter of the inner circumferential surface 12. Since the X direction is parallel to the width direction of the inner diameter of the inner circumferential surface 12, the second distance D2 is the maximum value in the width direction of the inner diameter of the inner circumferential surface 12.

[0025] A protrusion that comes into contact with the finger 80 may be formed on or near any of the portions 15, 16, 17, and 18 of the inner circumferential surface 12 that face the pad 81, dorsal surface 82, outer surface 83, and inner surface 84 of the finger 80, respectively. In this case, the first distance D1 means the distance between the portion 15 of the inner circumferential surface 12 that faces the pad 81 of the finger 80 and the portion 16 of the inner circumferential surface 12 that faces the dorsal surface 82 of the finger 80, when the protrusion is removed. The second distance D2 means the distance between the portion 17 of the inner circumferential surface 12 that faces the outer surface 83 of the finger 80 and the portion 18 of the inner circumferential surface 12 that faces the inner surface 84 of the finger 80, when the protrusion is removed.

[0026] If the length of the first distance D1 is made shorter than the length of the second distance D2, slight gaps are created between the outer surface 83 of the finger 80 and the portion 17 of the inner circumferential surface 12 facing it, and between the inner surface 84 of the finger 80 and the portion 18 of the inner circumferential surface 12 facing it, but the flesh of the finger 80 that is pushed out when the finger 80 is bent escapes into the gaps on the sides, thereby alleviating the feeling of pressure on the finger 80.

[0027] 7 is a partially enlarged cross-sectional view of the housing 11 of the sensing device 10 according to the embodiment of the present invention. Here, an example will be described in which a reflective photoplethysmographic sensor 40 and a temperature sensor 50 are used as the biosensor 21.

[0028] The photoplethysmographic sensor 40 includes a light-emitting element 41 and a light-receiving element 42. The light-emitting element 41 may be, for example, a semiconductor laser such as a vertical-cavity surface-emitting laser (VCSEL) or a light-emitting diode. The light-receiving element 42 may be, for example, a photodiode or a phototransistor. When the cross-sectional shape of the inner circumferential surface 12 is, for example, a substantially elliptical shape, the minor axis of the ellipse is a line segment connecting a portion 15 of the inner circumferential surface 12 facing the pad 81 of the finger 80 and a portion 16 of the inner circumferential surface 12 facing the dorsum 82 of the finger 80. The light-emitting element 41 and the light-receiving element 42 may be disposed symmetrically with respect to the minor axis of the substantially ellipse. When the wavelength of light emitted by the light-emitting element 41 is, for example, in the near-infrared wavelength region, the distance between the light-emitting element 41 and the light-receiving element 42 is preferably, for example, 10 mm, which may be approximately the same as the width of the finger. By arranging the light emitting element 41 and the light receiving element 42 symmetrically with respect to the minor axis of the approximately ellipse, it becomes possible to measure the pulse wave on the pad side of the finger even for people with thin fingers.

[0029] The circuit chip 20 includes two rigid substrates 31, 32, a flexible substrate 33 connecting the two rigid substrates 31, 32, and a resin layer 70 sealing the rigid substrates 31, 32 and the flexible substrate 33. The rigid substrate 31 is mounted with a light-emitting element 41 and a temperature sensor 50. The rigid substrate 32 is mounted with a light-receiving element 42. The control circuit 22 and the communication module 23 may be mounted on the rigid substrates 31, 32, or may be mounted on another substrate.

[0030] In order to increase the S / N ratio of photoplethysmographic sensor 40, it is desirable to bring photoplethysmographic sensor 40 into close contact with finger 80 when measuring the pulse wave signal. The reason why the S / N ratio of photoplethysmographic sensor 40 decreases when a gap is formed between photoplethysmographic sensor 40 and finger 80 is explained below.

[0031] The material of the resin layer 70 is, for example, epoxy resin, silicone resin, acrylic resin, polycarbonate resin, or polyethylene terephthalate resin, and its refractive index is approximately 1.4 to 1.6. For convenience of explanation, the refractive index of the resin layer 70 is set to 1.5, the refractive index of the skin of the finger 80 is set to 1.3, and the refractive index of air is set to 1. Here, if the refractive index of the medium on the incident side is set to n1 and the refractive index of the medium on the transmission side is set to n2, the reflectance R of light that is perpendicularly incident on the interface between these two media is given by R=(n2-n1) 2 / (n2+n1) 2 This becomes:

[0032] When there is no gap between the photoplethysmographic sensor 40 and the finger 80, the reflectance of the interface between the resin layer 70 and the finger 80 is 0.005 (transmittance 0.995). When there is a gap between the photoplethysmographic sensor 40 and the finger 80, the reflectance of the interface between the resin layer 70 and the air is 0.040 (transmittance 0.960), and the reflectance of the interface between the air and the finger 80 is 0.017 (transmittance 0.983). As a result, when there is a gap between the photoplethysmographic sensor 40 and the finger 80, the transmittance of the two interfaces is 0.960 × 0.983 ≈ 0.944, which is 94.9% of the transmittance when there is no gap between the photoplethysmographic sensor 40 and the finger 80.

[0033] When there is a gap between the photoplethysmographic sensor 40 and the finger 80, the transmittance of the light emitted from the light-emitting element 41 and the transmittance of the light received by the light-receiving element 42 are 94.9% of the transmittance of the light emitted from the light-emitting element 41 and the transmittance of the light received by the light-receiving element 42 when there is no gap between the photoplethysmographic sensor 40 and the finger 80. Therefore, when there is a gap between the photoplethysmographic sensor 40 and the finger 80, the amount of light received by the photoplethysmographic sensor 40 will be reduced to approximately 90% of the amount of light received by the photoplethysmographic sensor 40 when there is no gap between the photoplethysmographic sensor 40 and the finger 80.

[0034] Furthermore, since the reflectance and transmittance of light also depend on the angle of incidence of light with respect to the interface and the thickness of the gap, if a gap occurs between the photoplethysmographic sensor 40 and the finger 80, the amount of light received by the photoplethysmographic sensor 40 will fluctuate significantly, and the signal-to-noise ratio will decrease.

[0035] According to an embodiment of the present invention, by making the length of the first distance D1 shorter than the length of the second distance D2, even if the housing 11 is made of a non-flexible material, the adhesion between the pad 81 of the finger 80 and the biosensor 21 can be increased, and the signal-to-noise ratio of the biosensor 21 can be improved.

[0036] The distance between the light-emitting element 41 and the light-receiving element 42 is preferably set within an optimal distance range depending on the wavelength of light emitted from the light-emitting element 41. For example, to measure biological information from deep within the skin of the finger 80, a wavelength near near-infrared light (e.g., 940 nm) is suitable. FIG. 8 is a graph showing measurement results of the SN ratio as a function of the distance between the light-emitting element emitting near-infrared light and the light-receiving element receiving near-infrared light. The signal strength of the photoplethysmographic signal is the pulse wave amplitude, which varies depending on breathing and environmental temperature even for the same subject. Therefore, although there may be some variation in measurements, it can be seen that the SN ratio is maximized when the distance between the light-emitting element and the light-receiving element is approximately 10 mm. In the wavelength region near near-infrared light, the optimal distance between the light-emitting element and the light-receiving element is considered to be approximately 10 mm. If the distance between the light-emitting element and the light-receiving element deviates from the optimal distance, the SN ratio decreases.

[0037] On the other hand, when using a wavelength range of green light, which is much more strongly absorbed by living bodies than near-infrared light or red light, the optimum distance between the light-emitting element and the light-receiving element is thought to be approximately 2 to 3 mm.

[0038] The oxygen saturation sensor includes a light-emitting element that emits near-infrared light, a light-emitting element that emits red light, and a light-receiving element that receives the near-infrared light and the red light. The ratio of the AC component to the DC component of the red photoplethysmographic signal is defined as (AC / DC). Red The ratio of AC to DC components of the near-infrared photoplethysmographic signal is (AC / DC). IRThen, the oxygen saturation is [(AC / DC) Red ] / [(AC / DC) IR If the distance between the light-emitting element and the light-receiving element changes, the ratio of the AC component to the DC component of the photoplethysmographic signal changes, so it is desirable to set the distance between the light-emitting element that emits near-infrared light and the light-receiving element to the same distance as the distance between the light-emitting element that emits red light and the light-receiving element.

[0039] The distance between the light-emitting element 41 and the light-receiving element 42 is desirably shorter than the distance between the outer surface 83 and the inner surface 84 of the finger 80 (i.e., the width of the finger 80). If the distance between the light-emitting element 41 and the light-receiving element 42 is longer than the width of the finger 80, the length of the optical path of light passing through the inside of the finger 80 will change depending on the thickness of the finger 80, which may cause fluctuations in performance such as the S / N ratio. By making the distance between the light-emitting element 41 and the light-receiving element 42 shorter than the width of the finger 80, the length of the optical path of light passing through the inside of the finger 80 becomes constant, stabilizing performance such as the S / N ratio.

[0040] 9 is an explanatory diagram showing the configuration of a device set 100 according to an embodiment of the present invention. The device set 100 includes a plurality of sensing devices 10-1 and 10-2. To distinguish between the sensing devices 10-1 and 10-2, different reference numerals are assigned to the sensing devices 10-1 and 10-2, but the basic configuration of each of the sensing devices 10-1 and 10-2 is the same as the configuration of the sensing device 10.

[0041] The sensing device 10-1 is designed for users with thick fingers 80 (for example, men), and the first distance D1-1 and the second distance D2-1 of its inner circumferential surface 12 are both set to be longer. On the other hand, the sensing device 10-2 is designed for users with thin fingers 80 (for example, women), and the first distance D1-2 and the second distance D2-2 of its inner circumferential surface 12 are both set to be shorter. In this way, by designing the first distance D1-1 and the second distance D2-1 of the inner circumferential surface 12 of the sensing device 10-1 to be different from the first distance D1-2 and the second distance D2-2 of the inner circumferential surface 12 of the sensing device 10-2 in accordance with the thickness of the user's finger, it is possible to improve the adhesion between the finger 80 and the biosensor 21.

[0042] However, it is desirable to set the distance between the light-emitting element 41 and the light-receiving element 42 that constitute the biosensor 21 of the sensing device 10-1 to be the same as the distance between the light-emitting element 41 and the light-receiving element 42 that constitute the biosensor 21 of the sensing device 10-2. In this way, by setting the distance between the light-emitting element 41 and the light-receiving element 42 to a constant value (i.e., within an optimal distance range according to the wavelength), regardless of the thickness of the user's finger that is expected to use the device, the performance of the biosensor 21 can be made the same across the multiple sensing devices 10-1 and 10-2.

[0043] 9 shows an example in which the number of sensing devices constituting the device set 100 is two, but the number of sensing devices constituting the device set 100 may be three or more. In this case, the first distance and the second distance on the inner circumferential surface of one of the plurality of sensing devices may be different from the first distance and the second distance on the inner circumferential surface of another of the plurality of sensing devices. However, the distance between the light-emitting element 41 and the light-receiving element 42 constituting the biosensor 21 of each sensing device is the same.

[0044] Returning now to the explanation of FIG. 7 , as described above, in the wavelength region near near-infrared light, the optimal distance between the light-emitting element 41 and the light-receiving element 42 is considered to be approximately 10 mm. Meanwhile, the minimum width of the finger 80 for Japanese women is approximately 14.1 mm. Considering the curvature of the skin surface of the finger 80, if the light-emitting element 41 and the light-receiving element 42 are arranged on a flat surface with a distance of approximately 10 mm between them, the adhesion between the pulse wave sensor 40 and the finger 80 will be reduced. In consideration of this circumstance, the light-emitting element 41 and the light-receiving element 42 are arranged in a bent position on the inner circumferential surface 12 so as to face the bent portion of the pad 81 of the finger 80. For example, in the example shown in FIG. 7 , the flexible substrate 33 connecting the rigid substrates 31 and 32 is bent (valley fold), so that the light-emitting element 41 and the light-receiving element 42 can be arranged on the inner circumferential surface 12 so as to face the bent portion of the pad 81 of the finger 80. The shape of the bent arrangement may be, for example, a V-shape or a U-shape. When the distance between the light emitting element 41 and the light receiving element 42 is set to about 10 mm, the depth of the valley of the V-shape is preferably about 1 to 2.5 mm.

[0045] By arranging the light emitting element 41 and the light receiving element 42 on the inner circumferential surface 12 so that the light emitting element 41 and the light receiving element 42 face the bent portion of the pad 81 of the finger 80, the maximum radiation direction 61 of the light emitting element 41 and the maximum light receiving direction 63 of the light receiving element 42 can be positioned perpendicular to the surface of the pad 81 of the finger 80. By arranging the light emitting element 41 so that the maximum radiation direction 61 of the light emitting element 41 is perpendicular to the surface of the pad 81 of the finger 80, it is possible to increase the proportion of light that reaches the blood vessels in the dermis of the finger 80. Similarly, by arranging the light receiving element 42 so that the maximum light receiving direction 63 of the light receiving element 42 is perpendicular to the surface of the pad 81 of the finger 80, it is possible to increase the proportion of light that is reflected from the blood vessels in the dermis of the finger 80 and reaches the light receiving element 42. Depending on the thickness of the finger 80, the maximum radiation direction 61 of the light-emitting element 41 may deviate from the perpendicular direction to the surface of the pad 81 of the finger 80, and the maximum light-receiving direction 63 of the light-receiving element 42 may deviate from the perpendicular direction to the surface of the pad 81 of the finger 80. However, by arranging the light-emitting element 41 and the light-receiving element 42 in a bent position as described above, the deviation can be reduced.

[0046] The light-emitting element 41 and the light-receiving element 42 are bent and arranged on the inner surface 12 so as to face the bent portion of the pad 81 of the finger 80, and therefore the maximum radiation direction 61 of the light-emitting element 41 and the maximum light-receiving direction 63 of the light-receiving element 42 are non-parallel to each other.

[0047] The resin layer 70 is bent to match the bending shape of the flexible substrate 33 so that its surface is perpendicular to each of the maximum emission direction 61 of the light emitting element 41 and the maximum light receiving direction 63 of the light receiving element 42. By bending the resin layer 70 so that the surface of the resin layer 70 is perpendicular to the maximum emission direction 61 of the light emitting element 41, it is possible to suppress refraction of light emitted from the light emitting element 41 at the surface of the resin layer 70 and to suppress a decrease in the transmittance of the emitted light. Similarly, by bending the resin layer 70 so that the surface of the resin layer 70 is perpendicular to the maximum light receiving direction 63 of the light receiving element 42, it is possible to suppress refraction of light received by the light receiving element 42 at the surface of the resin layer 70 and to suppress a decrease in the transmittance of the received light.

[0048] 7, the light emitting element 41 and the light receiving element 42 may be mounted on a flexible substrate, and the flexible substrate may be bent between the light emitting element 41 and the light receiving element 42. Also, instead of the flexible substrate 33, a flexible cable may be used.

[0049] The resin layer 70 is preferably formed by integral molding using a mold so as to integrally seal the rigid substrates 31, 32 and the flexible substrate 33. By integrally molding the resin layer 70 so as to integrally seal the rigid substrates 31, 32 and the flexible substrate 33, it is possible to suppress deviation in the relative positional relationship (such as the distance and angle between them) between the light-emitting element 41 and the light-receiving element 42, thereby maintaining an optimal signal-to-noise ratio for the photoplethysmographic sensor 40.

[0050] It is desirable to design the electrode terminals of the light emitting element 41, the light receiving element 42, and other circuit elements so that they are not exposed from the resin layer 70. This allows the sensing device 10 to achieve waterproof functionality for everyday use.

[0051] It is desirable to surround the light-emitting element 41 with a reflector 90. By surrounding the light-emitting element 41 with the reflector 90, it is possible to prevent light emitted from the light-emitting element 41 from being incident directly on the light-receiving element 42 without being incident on the finger 80, thereby improving the signal-to-noise ratio of the photoplethysmographic sensor 40. In addition to surrounding the light-emitting element 41 with the reflector 90, the light-receiving element 42 may also be surrounded by a reflector.

[0052] The resin layer 70 is preferably formed so that the ends and corners of the resin layer 70 are located outside the range of the directivity angle 62 of the light-emitting element 41, and the ends and corners of the resin layer 70 are located outside the range of the directivity angle 64 of the light-receiving element 42. This prevents the light emitted from the light-emitting element 41 from entering the finger 80 and being scattered or reflected at the ends or corners of the resin layer 70, thereby preventing the light from directly entering the light-receiving element 42.

[0053] Furthermore, it is desirable to arrange the light emitting element 41 on the inner circumferential surface 12 so that when the housing 11 is worn on the finger 80, the pad 81 of the finger 80 is positioned within the range of the directivity angle 62 of the light emitting element 41. This makes it possible to prevent the light emitted from the light emitting element 41 from being reflected by the housing 11 without being incident on the finger 80 and being directly incident on the light receiving element 42.

[0054] Furthermore, it is desirable to arrange the light receiving element 42 on the inner circumferential surface 12 so that when the housing 11 is worn on the finger 80, the pad 81 of the finger 80 is positioned within the range of the directivity angle 64 of the light receiving element 42. This makes it possible to prevent light that is reflected by the housing 11 without being incident on the finger 80 from being directly incident on the light receiving element 42.

[0055] In addition to the above-mentioned structure, a structure for suppressing stray light may also be used, for example, in which the resin layer that seals the light-emitting element 41 and the resin layer that seals the light-receiving element 42 are separate bodies, and the two resin layers are separated by a black resin.

[0056] The temperature sensor 50 can be, for example, a thermistor. Because air has low thermal conductivity, it is desirable to have no gap between the finger 80 and the temperature sensor 50 in order to accurately measure the temperature (peripheral temperature) of the finger 80. Furthermore, it is desirable to have a small thermal resistance between the temperature sensor 50 and the finger 80, and a large thermal resistance between the temperature sensor 50 and the outside air. In view of these circumstances, it is desirable to seal the temperature sensor 50 with a resin layer 70. The thermal conductivity of the resin layer 70 is three orders of magnitude lower than that of metal but one order of magnitude higher than that of air. The thermal resistance between the temperature sensor 50 and the finger 80 can be reduced by adjusting the thickness of the resin layer 70 between the temperature sensor 50 and the finger 80 to, for example, less than 1 mm. Furthermore, the thermal resistance between the temperature sensor 50 and the outside air can be increased by appropriately adjusting the shape and thickness of the housing 11.

[0057] In the above description, the photoplethysmographic sensor 40 includes a light-emitting element 41 and a light-receiving element 42. However, the photoplethysmographic sensor 40 may include a plurality of light-emitting elements and light-receiving elements that emit light of different wavelengths. The plurality of light-emitting elements may include, for example, a light-emitting element that emits light in the red to near-infrared wavelength band and a light-emitting element that emits light in the blue to yellow-green wavelength band. The red to near-infrared wavelength band is suitable for measuring biological information from deep regions of the skin of the finger 80. On the other hand, the blue to yellow-green wavelength band is suitable for measuring biological information from shallow regions of the skin of the finger 80. By using a light-emitting element that emits light in the red to near-infrared wavelength band and a light-emitting element that emits light in the blue to yellow-green wavelength band in combination, biological information can be measured from both deep and shallow regions of the skin of the finger 80.

[0058] Each of the plurality of light-emitting elements may be disposed at a different distance from the light-receiving element depending on the wavelength. For example, a light-emitting element emitting light in the red to near-infrared wavelength band may be disposed at a distance of approximately 10 mm from the light-receiving element, and a light-emitting element emitting light in the blue to yellow-green wavelength band may be disposed at a distance of approximately 2 to 3 mm from the light-receiving element. By disposing each of the plurality of light-emitting elements at a different distance from the light-receiving element depending on the wavelength, it is possible to measure biological information with a stable signal-to-noise ratio.

[0059] Photoplethysmographic sensor 40 may include multiple light-emitting elements that emit light of different wavelengths and multiple light-receiving elements that receive light of different wavelengths. For example, photoplethysmographic sensor 40 may include a first pair including a first light-emitting element that emits light in the red to near-infrared wavelength band and a first light-receiving element that receives the light from the first light-emitting element, and a second pair including a second light-emitting element that emits light in the blue to yellow-green wavelength band and a second light-receiving element that receives the light from the second light-emitting element. In this case, the first light-emitting element may be located approximately 10 mm away from the first light-receiving element, and the second light-emitting element may be located approximately 2 to 3 mm away from the second light-receiving element.

[0060] FIG. 10 is an explanatory diagram showing an example of the cross-sectional structure of the housing 11 of the sensing device 10 according to an embodiment of the present invention. In this example, the radius of curvature of a first curve C1 passing through a portion 17 of the inner circumferential surface 12 facing the outer surface 83 of a finger 80, a portion 15 of the inner circumferential surface 12 facing the pad 81 of the finger 80, and a portion 18 of the inner circumferential surface 12 facing the inner surface 84 of the finger 80 is defined as a first radius of curvature. The radius of curvature of a second curve C2 passing through a portion 17 of the inner circumferential surface 12 facing the outer surface 83 of the finger 80, a portion 16 of the inner circumferential surface 12 facing the dorsum 82 of the finger 80, and a portion 18 of the inner circumferential surface 12 facing the inner surface 84 of the finger 80 is defined as a second radius of curvature. The first curve C1 and the second curve C2 define the cross-sectional shape of the inner circumferential surface 12. In this example, the first radius of curvature is greater than the second radius of curvature.

[0061] With this configuration, an appropriate gap is created between the first curved line C1 of the inner circumferential surface 12 and the finger 80, and when bending the finger 80 with the finger 80 inserted in the hollow portion of the inner circumferential surface 12, the flesh of the finger 80 can escape into this gap, making it easier to bend the finger 80. If the second radius of curvature were larger than the first radius of curvature, the upper part of the second joint of the finger 80 would get caught on the inner circumferential surface 12, making it difficult to remove the finger 80 from the inner circumferential surface 12. Furthermore, since there is almost no gap between the first curved line C1 of the inner circumferential surface 12 and the finger 80, when bending the finger 80 with the finger 80 inserted in the hollow portion of the inner circumferential surface 12, the flesh of the finger 80 cannot escape sufficiently into this gap, making it difficult to bend the finger 80.

[0062] The first curve C1 may be a portion of a circle having a first curvature, and the second curve C2 may be a portion of a circle having a second curvature. Here, the first curvature is smaller than the second curvature. That is, the cross-sectional shape of the inner circumferential surface 12 may be a combination of portions of multiple circles having different curvatures. The cross-sectional shape of the inner circumferential surface 12 is not limited to a circle, an ellipse, or a combination thereof, and the radius of curvature of the curve defining the cross-sectional shape of the inner circumferential surface 12 may change continuously.

[0063] In the example shown in Figure 10, if the straight line that defines the maximum width of the inner circumferential surface 12 is L, the distance D3 between the straight line L and portion 15 of the inner circumferential surface 12 is shorter than the distance D4 between the straight line L and portion 16 of the inner circumferential surface 12.

[0064] FIG. 11 is an explanatory diagram showing an example of the cross-sectional structure of the housing 11 of the sensing device 10 according to an embodiment of the present invention. In the figure, the direction of the line segment connecting the portion 17 of the inner circumferential surface 12 facing the outer surface 83 of the finger 80 and the portion 18 of the inner circumferential surface 12 facing the inner surface 84 of the finger 80 is the X direction, the direction of the line segment connecting the portion 15 of the inner circumferential surface 12 facing the pad 81 of the finger 80 and the portion 16 of the inner circumferential surface 12 facing the dorsum 82 of the finger 80 is the Y direction, and the insertion / removal direction of the finger 80 (the longitudinal direction of the finger 80) is the Z direction. In this case, the cross-sectional shape of the portion 16 of the inner circumferential surface 12 facing the dorsum 82 of the finger 80 in a plane parallel to the YZ plane and perpendicular to the X direction protrudes convexly toward the hollow portion. In the example shown in the figure, the cross-sectional shape of the portion 16 of the inner circumferential surface 12 in a plane parallel to the YZ plane and perpendicular to the X direction is gently curved convexly toward the hollow portion. With this structure, the contact area between the back 82 of the finger 80 and the portion 16 of the inner surface 12 can be reduced, improving the sliding properties between the back 82 of the finger 80 and the portion 16 of the inner surface 12 when inserting or removing the sensing device 10, making it easier to insert or remove the sensing device 10.

[0065] In the example shown in Figure 11, the cross-sectional shape of portion 16 of inner surface 12 in a plane parallel to the YZ plane and perpendicular to the X direction is convexly curved toward the hollow portion with rounded corners, but as shown in Figure 12, the cross-sectional shape of portion 16 of inner surface 12 in a plane parallel to the YZ plane and perpendicular to the X direction may be rectangular and protrude toward the hollow portion without rounded corners.

[0066] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. The present invention may be modified or improved without departing from its spirit, and equivalents are also included within the scope of the present invention. In other words, even designs modified appropriately by a person skilled in the art are encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention. Furthermore, the elements of the embodiments can be combined to the extent technically possible, and such combinations are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention. [Explanation of symbols]

[0067] 10...Sensing device 11...Housing 12...Inner peripheral surface 13...Outer peripheral surface 14...Opening 20...Circuit chip 21...Biometric sensor 22...Control circuit 23...Communication module 50...Temperature sensor 80...Finger 81...Belly 82...Dorsal 83...Outer surface 84...Inner surface

Claims

1. a non-flexible housing configured to be wearable on a user's finger, the housing having an inner circumferential surface that faces the pad, back, outer surface, and inner surface of the finger when the housing is worn on the finger; a biosensor that measures biometric information of the user from the finger, the biosensor being arranged on the inner circumferential surface such that the biosensor faces the pad of the finger when the housing is worn on the finger; a cross section of the inner circumferential surface is configured such that a first distance between a portion of the inner circumferential surface facing the pad of the finger and a portion of the inner circumferential surface facing the dorsum of the finger is shorter than a second distance between a portion of the inner circumferential surface facing the outer surface of the finger and a portion of the inner circumferential surface facing the inner surface of the finger, a first radius of curvature is a radius of curvature of a curve that passes through a portion of the inner circumferential surface facing an outer surface of the finger, a portion of the inner circumferential surface facing a pad of the finger, and a portion of the inner circumferential surface facing an inner surface of the finger; When the radius of curvature of a curve passing through a portion of the inner circumferential surface facing the outer surface of the finger, a portion of the inner circumferential surface facing the back of the finger, and a portion of the inner circumferential surface facing the inner surface of the finger is defined as a second radius of curvature, The sensing device, wherein the first radius of curvature is greater than the second radius of curvature.

2. A device set comprising a plurality of sensing devices, Each sensing device is a sensing device according to claim 1, the first distance and the second distance of the inner circumferential surface of one sensing device among the plurality of sensing devices are different from the first distance and the second distance of the inner circumferential surface of another sensing device among the plurality of sensing devices, the biosensor includes a pulse wave sensor including a light-emitting element and a light-receiving element; A device set, wherein the distance between the light-emitting element and the light-receiving element of each sensing device is the same.

3. 3. The device set according to claim 2, the biosensor includes a pulse wave sensor including a light-emitting element and a light-receiving element; A device set, wherein the distance between the light emitting element and the light receiving element is shorter than the distance between the outer surface of the finger and the inner surface of the finger.

4. 3. The device set according to claim 2, the biosensor includes a pulse wave sensor including a light-emitting element and a light-receiving element; The device set, wherein the light emitting element and the light receiving element are bent and arranged on the inner circumferential surface so as to face the pad of the finger.

5. 5. The device set according to claim 4, A device set, wherein the distance between the light-emitting element and the light-receiving element is 10 mm.

6. 6. The device set according to claim 5, The light-emitting element emits light in the red to near-infrared wavelength range.

7. 5. The device set according to claim 4, A device set, wherein the maximum emission direction of the light-emitting element and the maximum light-receiving direction of the light-receiving element are non-parallel to each other.

8. 3. The device set according to claim 2, The biosensor is a device set including a pulse wave sensor including a light-emitting element, a light-receiving element, and a resin layer that seals the light-emitting element and the light-receiving element.

9. 9. The device set of claim 8, the resin layer is formed such that an end and a corner of the resin layer are located outside a range of a directivity angle of the light-emitting element, or such that an end and a corner of the resin layer are located outside a range of a directivity angle of the light-receiving element, the light-emitting element is disposed on the inner circumferential surface such that, when the housing is worn on the finger, the pad of the finger is positioned within a range of a directivity angle of the light-emitting element, The light receiving element is arranged on the inner circumferential surface so that the pad of the finger is positioned within the range of the directivity angle of the light receiving element when the housing is worn on the finger.

10. 10. The device set of claim 9, The light emitting element and the light receiving element are fitted into openings in the inner circumferential surface.

11. 3. The device set according to claim 2, The device set, wherein the biological sensor includes a temperature sensor.

12. 3. The device set according to claim 2, The biosensor includes a pulse wave sensor including a plurality of light-emitting elements and a light-receiving element that emit light of different wavelengths, and each of the plurality of light-emitting elements is positioned at a different distance from the light-receiving element depending on the wavelength.

13. 13. A device set according to claim 12, The device set, wherein the plurality of light-emitting elements include a second light-emitting element that emits light in a wavelength band from blue to yellow-green.

14. 14. A device set according to claim 13, A device set, wherein the distance between the second light-emitting element and the light-receiving element is 2 to 3 mm.

15. 3. The device set according to claim 2, The inner circumferential surface has a hollow shape having a hollow portion, a direction of a line segment connecting a portion of the inner circumferential surface facing an outer surface of the finger with a portion of the inner circumferential surface facing an inner surface of the finger is defined as an X direction; a direction of a line segment connecting a portion of the inner circumferential surface facing the pad of the finger and a portion of the inner circumferential surface facing the back of the finger is defined as a Y direction; When the insertion and removal direction of the finger is the Z direction, A device set, wherein the cross-sectional shape of the portion of the inner surface facing the back of the finger in a plane parallel to the YZ plane and perpendicular to the X direction protrudes convexly toward the hollow portion.

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