Detection and measurement devices

Abstract

To provide a detection device and a measurement device that allow device configuration to be downsized.SOLUTION: A detection device includes: a first light emission part for emitting a first light having a green wavelength band; a second light emission part for emitting a second light having a wavelength band longer than the green wavelength band; and a light reception part for receiving the first light and the second light respectively emitted from the first light emission part and the second light emission part, and emitted from a living body. The light reception part includes a first light reception area for receiving the first light, a second light reception area disposed at a position farther from the first light emission part than the first light reception area for receiving the second light, and a first filter disposed either in the first light reception area or in the second light reception area for causing the light of a corresponding wavelength band to be selectively transmitted.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to detection and measurement devices. [Background technology]

[0002] Various measurement techniques have been proposed for non-invasively measuring biological information such as pulse waves. For example, Patent Document 1 below discloses a detection device that includes a light-emitting unit that emits light into a living body and a light-receiving unit that receives the light that is emitted from the light-emitting unit and reflected by the living body, and that improves the light utilization efficiency of the light-emitting unit and takes measures against stray light in the light-receiving unit by installing a light-shielding member between the light-emitting unit and the light-receiving unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-061675 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned detection device requires a plurality of light receiving units for receiving light reflected by the living body, which poses a problem that the device configuration cannot be made compact. [Means for solving the problem]

[0005] According to one aspect of the present invention, a first light emitting unit that emits first light having a green wavelength band, and a second light emitting unit that emits light having a wavelength lower than the green wavelength band, longProvided is a detection device comprising: a second light-emitting unit that emits second light having a wavelength band; and a light-receiving unit that receives the first light and the second light emitted from the first light-emitting unit and the second light-emitting unit and emitted from a living body, respectively; the light-receiving unit having a first light-receiving region that receives the first light; a second light-receiving region that is located farther from the first light-emitting unit than the first light-receiving region and receives the second light; and a first filter that is located in either the first light-receiving region or the second light-receiving region and selectively transmits light of the corresponding wavelength band.

[0006] According to one aspect of the present invention, there is provided a measurement device including the detection device of the above aspect and an information analysis unit that identifies biological information from a detection signal that indicates a detection result by the detection device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a side view of the measurement device according to the first embodiment. [Figure 2] FIG. 1 is a configuration diagram focusing on the functions of a measurement device. [Figure 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. [Figure 5] 1 is a graph showing the transmission spectrum of skin. [Figure 6] 10 is a graph showing the relationship between a red light emitting unit and a light receiving unit. [Figure 7] 10A and 10B are diagrams for explaining the operation of the detection device. [Figure 8] FIG. 10 is a cross-sectional view of a detection device according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a detection device according to a third embodiment. [Figure 10] FIG. 11 is a cross-sectional view of a detection device according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to the drawings. Note that in the following drawings, the scale and angle of each component are different from the actual scale and angle in order to make each component large enough to be recognizable.

[0009] (First embodiment) FIG. 1 is a side view of a measurement device 100 according to a first embodiment. The measurement device 100 shown in FIG. 1 is a biometric device that noninvasively measures biometric information of a subject (e.g., a human), which is an example of a living organism. The measurement device 100 is attached to a measurement target part M of the subject's body (hereinafter referred to as the "measurement part"). The measurement device 100 according to this embodiment is a wristwatch-type portable device that includes a housing 1 and a strap 2. The measurement device 100 can be attached to the subject's wrist, which is an example of the measurement part (living organism) M, by wrapping the strap 2 around the subject's wrist. In this embodiment, the subject's pulse wave (e.g., pulse interval PPI) and oxygen saturation (SpO2) are exemplified as biometric information. The pulse wave refers to the time change in intravascular volume linked to the heartbeat. The oxygen saturation refers to the percentage (%) of hemoglobin in the subject's blood that is bound to oxygen, and is an index for evaluating the subject's respiratory function.

[0010] Fig. 2 is a configuration diagram focusing on the functions of the measuring device 100. As shown in Fig. 2, the measuring device 100 of this embodiment includes a control device 5, a storage device 6, a display device 4, and a detection device 3. The control device 5 and the storage device 6 are installed inside the housing unit 1. As shown in Fig. 1, the display device 4 is installed on the surface of the housing unit 1 opposite to the measurement site M, and displays various images including measurement results under the control of the control device 5. The display device 4 is, for example, a liquid crystal display panel.

[0011] The detection device 3 is an optical sensor module that generates a detection signal S corresponding to the state of the measurement site M. As shown in FIG. 1, the detection device 3 is installed, for example, on a surface (hereinafter referred to as the detection surface) 16 of the housing 1 that faces the measurement site M. The detection surface 16 is the surface that comes into contact with the measurement site M. As shown in FIG. 2, the detection device 3 of this embodiment includes a light-emitting unit 11, a light-receiving unit 12, a drive circuit 13, and an output circuit 14. Note that it is also possible to install one or both of the drive circuit 13 and the output circuit 14 as external circuits of the detection device 3. In other words, the drive circuit 13 and the output circuit 14 can be omitted from the detection device 3.

[0012] Fig. 3 is a plan view of the detection device 3. Fig. 4 is a cross-sectional view taken along the line IV-IV in Fig. 3. As shown in Figs. 3 and 4, the detection device 3 of this embodiment further includes a case 40, a light-shielding wall 41, and a sealing layer 42 in addition to the light-emitting unit 11 and the light-receiving unit 12. Note that the drive circuit 13 and the output circuit 14 are not shown in Figs. 3 and 4.

[0013] The configuration of the detection device 3 will be described below using an XYZ coordinate system. The X axis corresponds to the axis along the long side (one side) of the case 40, which has a rectangular outer shape, the Y axis corresponds to the axis perpendicular to the X axis and along the short side (the other side) of the case 40, and the Z axis corresponds to the axis perpendicular to the X axis and Y axis, respectively, and along the normal to the detection surface 16 that comes into contact with the measurement site M.

[0014] As shown in FIGS. 3 and 4, the case 40 is a member that houses the elements (light-emitting unit 11 and light-receiving unit 12) that make up the detection device 3. The case 40 has a box shape that includes a rectangular, flat bottom surface 40a and rectangular frame-shaped side plate portions 40b that protrude from the periphery of the bottom surface 40a toward the +Z side. The case 40 is made of, for example, aluminum. The inner peripheral surface 40b1 of the side plate portion 40b is colored black to provide light blocking properties. This reduces reflection on the inner peripheral surface 40b1 of the side plate portion 40b.

[0015] The case 40 may be made of any material and manufactured by any method. For example, the case 40 may be formed by injection molding of a resin material. Alternatively, the case 40 may be formed integrally with the housing 1.

[0016] The light-emitting unit 11 and the light-receiving unit 12 are mounted on a wiring board (not shown) and placed on the bottom surface 40a of the case 40. The light-shielding wall 41 is disposed between the light-emitting unit 11 and the light-receiving unit 12 in the direction along the X-axis. The light-shielding wall 41 is a plate-shaped member that protrudes from the bottom surface 40a to the +Z side and extends in the Y-axis direction, and separates the storage space inside the case 40 into two in the X-axis direction. In other words, the light-shielding wall 41 is a member that separates the spaces that store the light-emitting unit 11 and the light-receiving unit 12 in the direction along the X-axis. The light-shielding wall 41 is a member that has light-shielding properties to block light emitted from the light-emitting unit 11 from directly entering the light-receiving unit 12.

[0017] In this embodiment, the light-shielding wall 41 is provided in the direction along the X-axis between the light-emitting unit 11 including the first light-emitting section 50 and the second light-emitting section 60 and the light-receiving section 12. In other words, the light-shielding wall 41 is a member that blocks part of the green light LG, the red light LR, and the near-infrared light LI.

[0018] The sealing layer 42 is a light-transmitting resin material that fills the gap between the side plate 40b and the light-emitting unit 11 and the light-receiving unit 12 housed in the case 40. The sealing layer 42 seals (molds) the light-emitting unit 11 and the light-receiving unit 12 within the case 40. The surface of the sealing layer 42 functions as the detection surface 16. Instead of the sealing structure using the sealing layer 42, a structure in which the upper surface of the side plate portion 40b of the case 40 is covered with a light-transmitting substrate may be employed. In this case, the upper surface of the light-transmitting substrate functions as the detection surface 16.

[0019] The light-emitting unit 11 has a first light-emitting section 50, a second light-emitting section 60, and a third light-emitting section 70. The first light-emitting section 50, the second light-emitting section 60, and the third light-emitting section 70 are light sources that emit light of different wavelengths toward the measurement site M.

[0020] The first light-emitting unit 50 emits green light (first light) LG having a green wavelength band of 520 nm to 550 nm toward the measurement site M. The green light LG in this embodiment is, for example, light with a peak wavelength of 520 nm. The second light emitting unit 60 emits red light (second light) LR having a red wavelength band of, for example, 600 nm to 800 nm toward the measurement site M. The red light LR in this embodiment is light having a peak wavelength of, for example, 660 nm. The third light emitter 70 emits near-infrared light (third light) LI having a near-infrared wavelength band of, for example, 800 nm to 1300 nm toward the measurement site M. The near-infrared light LI in this embodiment is light having a peak wavelength of, for example, 905 nm.

[0021] As the light-emitting elements constituting the first light-emitting unit 50, the second light-emitting unit 60, and the third light-emitting unit 70, for example, bare chip type or bullet type LEDs (Light Emitting Diodes) are suitably used. Note that the wavelength of the light emitted by each light-emitting unit is not limited to the above-mentioned numerical range. Hereinafter, when the first light-emitting unit 50, the second light-emitting unit 60, and the third light-emitting unit 70 are not particularly distinguished from each other, they will be collectively referred to as the light-emitting units 50, 60, and 70.

[0022] The light emitting units 50, 60, and 70 are installed in the case 40 so that the light emitting surface thereof is parallel to the XY plane. That is, the light emitting units 50, 60, and 70 emit light toward the +Z side.

[0023] Each of the light-emitting units 50, 60, 70 emits light in response to a supply of a drive current from the drive circuit 13 shown in Fig. 2. In this embodiment, the drive circuit 13 causes each of the light-emitting units 50, 60, 70 to emit light independently and in a time-sequential manner. Hereinafter, the mode in which each of the light-emitting units 50, 60, 70 emits light independently and in a time-sequential manner will be referred to as the light-emitting units 50, 60, 70 emitting light in a time-sequential manner.

[0024] The light emitted from each of the light-emitting units 50, 60, 70 enters the measurement site M and propagates while repeatedly being reflected and scattered inside the measurement site M, before being emitted toward the housing 1 and reaching the light-receiving unit 12. In other words, the detection device 3 of this embodiment is a reflective optical sensor in which the light-emitting unit 11 and the light-receiving unit 12 are located on one side of the measurement site M.

[0025] 3, the light-emitting units 50, 60, and 70 are arranged side by side in a direction (first direction) along the Y axis at intervals from one another. Specifically, the second light-emitting unit 60 is arranged on the +Y side of the first light-emitting unit 50, and the third light-emitting unit 70 is arranged on the -Y side of the first light-emitting unit 50. In other words, the first light-emitting unit 50 is arranged between the second light-emitting unit 60 and the third light-emitting unit 70 in the direction along the Y axis. In other words, the first light-emitting unit 50 is located between the second light-emitting unit 60 and the third light-emitting unit 70.

[0026] Incidentally, in the past, when a detection device used in a measurement device acquires both the pulse rate interval (PPI) and oxygen saturation (SpO2) as biological information of a subject, a light receiving unit for green light (hereinafter referred to as the green light receiving unit) for identifying the pulse wave and a light receiving unit for red light and near-infrared light (hereinafter referred to as the red and near-infrared light receiving unit) for identifying the oxygen saturation were provided. This resulted in an increase in the size of the detection device, making it difficult to miniaturize the measurement device.

[0027] In recent years, there has been a demand for further miniaturization of measuring devices. In light of this background, the present inventors have conducted extensive research into a small-sized detection device that can acquire both pulse intervals and oxygen saturation.

[0028] First, the inventors focused on the fact that the transmittance of skin differs for each wavelength band of light. Figure 5 is a graph showing the transmission spectrum of skin. In Figure 5, the horizontal axis represents the wavelength of light, and the vertical axis represents the transmittance (unit: %). Figure 5 shows the transmission spectrum when the skin thickness is 0.43 mm as an example.

[0029] As shown in Figure 5, when the wavelength band of green light LG (e.g., 520 nm) enters the skin, the transmittance is about 30%, when the wavelength band of red light LR (e.g., 660 nm) enters the skin, the transmittance is about 50% to 60%, and when the wavelength band of near-infrared light LI (e.g., 905 nm) enters the skin, the transmittance is about 60%.

[0030] The graph shown in Figure 5 shows that the distance that light can propagate within a living body varies depending on the wavelength of light. That is, the graph in Figure 5 shows that green light LG can propagate only a shorter distance within a living body than red light LR or near-infrared light LI. In other words, red light LR and near-infrared light LI can propagate farther within a living body than green light LG. Note that Figure 5 uses an example where the skin thickness is 0.43 mm, but even when the skin thickness is different, red light LR and near-infrared light LI can similarly propagate farther within a living body than green light LG. The present inventors have found that, as shown in the graph of FIG. 5, green light LG is more easily attenuated when passing through a living body than red light LR and near-infrared light LI.

[0031] The inventors also performed a simulation of the state of incidence of green light passing through a living body onto a light receiving unit, using a conventionally used light receiving unit of a typical size as a simulation condition.

[0032] The results of this simulation showed that green light LG was effectively incident on the area of the light-receiving section closer to the light-emitting section, but that green light LG was not efficiently incident on the area of the light-receiving section farther from the light-emitting section. This is because the green light was attenuated before it reached the area farther from the light-emitting section. The present inventors have found that since the green light LG that passes through the inside of a living body is easily attenuated, the light receiving region that receives the green light LG should be disposed near the light emitting portion.

[0033] The inventors also noticed that the noise components contained in the red light LR or near-infrared light LI that propagate through the living body and enter the light-receiving unit change depending on the distance from the light-emitting unit to the light-receiving unit. In the following, red light LR will be used as an example for explanation, but the same can be said for near-infrared light LI.

[0034] Figure 6 is a graph showing the relationship between the distance from the red light emitter to the light receiver, the noise component of the red light, and the current consumption of the red light emitter. In Figure 6, the horizontal axis represents the distance from the red light emitter to the light receiver, the vertical axis on the left represents the noise component of the red light LR, and the vertical axis on the right represents the current consumption of the light emitter.

[0035] As shown in Figure 6, the closer the distance between the light-receiving unit and the light-emitting unit, the greater the noise component of the red light LR received by the light-receiving unit. In other words, the farther the light-receiving unit is located from the light-emitting unit, the lower the noise component of the red light LR, thereby improving the detection accuracy of the red light LR. This is because, when the light-receiving unit is located close to the light-emitting unit, red light components that do not pass through blood are reflected by the surface of the living body and are incident on the light-receiving unit. This red light LR that does not pass through blood becomes a noise component when the light-receiving unit determines the blood oxygen concentration.

[0036] Therefore, by arranging the light-receiving unit farther from the light-emitting unit, it is possible to reduce the noise components contained in the red light LR and improve the detection accuracy of the red light LR. On the other hand, if the light-receiving unit is arranged farther from the light-emitting unit, the distance of propagation within the living body increases, so it is necessary to increase the current input to the light-emitting unit to increase the brightness of the red light. In this case, the current consumption of the light-emitting unit increases, so it is desirable to determine the distance between the light-emitting unit and the light-receiving unit in consideration of the balance between the noise components and the current consumption. For example, in this embodiment, the distance between the light-receiving unit and the red light-emitting unit is set to the distance where the curve representing the noise components and the curve representing the current consumption intersect.

[0037] As with the red light LR, the detection accuracy of the near-infrared light LI can also be improved by arranging the near-infrared light emitter that emits the near-infrared light LI and the light receiver at a distance from each other. It is also desirable to determine the distance between the near-infrared light emitter and the light receiver in consideration of the balance between noise components and current consumption.

[0038] The present inventors have found that the detection accuracy of the light receiving section can be improved by arranging the light receiving region that receives red light LR or near-infrared light LI as far away as possible from the light emitting section.

[0039] Based on the above findings, the inventors have completed the detection device 3 and measurement device 100 of this embodiment. In the detection device 3 of this embodiment, the light receiving region of the light receiving unit 12 of a conventionally used, general size is divided into two, and one region closer to the light emitting unit is used as the light receiving region for green light, and the other region farther from the light emitting unit is used as the light receiving region for red and near-infrared light.

[0040] The configuration of the light receiving section 12 of this embodiment will be described below. The light receiving section 12 receives light arriving from the measurement site M due to the emission of light by the light emitting unit section 11. The light receiving section 12 of this embodiment has a first light receiving area 51 and a second light receiving area 61. The light receiving section 12 generates detection signals according to the intensities of the light received in the first light receiving area 51 and the second light receiving area 61. Hereinafter, when there is no need to particularly distinguish between the first light receiving area 51 and the second light receiving area 61, they will be collectively referred to as the "light receiving areas 51, 61."

[0041] The light receiving unit 12 is installed in the case 40 so that the light receiving surfaces of the light receiving regions 51 and 61 are parallel to the XY plane. That is, the light receiving regions 51 and 61 receive light incident from the Z direction.

[0042] 3, the light receiving regions 51, 61 are spaced apart from each other and arranged side by side in a direction (second direction) along the X-axis that intersects (is perpendicular to) the Y-axis. Specifically, the first light receiving region 51 is located on the +X side of the light emitting unit 11, and the second light receiving region 61 is located on the +X side of the first light receiving region 51. The second light receiving region 61 is arranged on the opposite side of the light emitting unit 11 with the first light receiving region 51 in between. In this embodiment, the second light receiving region 61 is located farther from the first light emitting unit 50 than the first light receiving region 51. Specifically, the first light receiving region 51 is located closer to the first light emitting unit 50 than the second light receiving region 61 in the direction along the X-axis.

[0043] Here, the distance from the first light-emitting unit 50 to the first light-receiving region 51 is defined as D1, the distance from the second light-emitting unit 60 to the second light-receiving region 61 is defined as D2, and the distance from the third light-emitting unit 70 to the second light-receiving region 61 is defined as D3. The distance D1 corresponds to the distance between the centers of the first light-emitting unit 50 and the first light-receiving region 51 when viewed in a plane from the Z-axis direction. The distance D2 corresponds to the distance between the centers of the second light-emitting unit 60 and the second light-receiving region 61 when viewed in a plane from the Z-axis direction. The distance D3 corresponds to the distance between the centers of the third light-emitting unit 70 and the second light-receiving region 61 when viewed in a plane from the Z-axis direction.

[0044] In the detection device 3 of this embodiment, the distance D1 from the first light-emitting unit 50 to the first light-receiving region 51 is shorter than the distance D2 from the second light-emitting unit 60 to the second light-receiving region 61. In addition, the distance D1 from the first light-emitting unit 50 to the first light-receiving region 51 is shorter than the distance D3 from the third light-emitting unit 70 to the second light-receiving region 61. Note that the distances D2 and D3 are equal. As described above, the detecting device 3 of this embodiment employs a configuration in which the first light receiving region 51 for receiving the green light LG is disposed in the position closest to the first light emitting section 50 that emits the green light LG.

[0045] In this embodiment, the first light-receiving region 51 and the second light-receiving region 61 are formed by dividing the light entrance region of the light-receiving unit 12 into two regions. The first light-receiving region 51 and the second light-receiving region 61 have the same area. The first light-receiving region 51 has a planar area capable of receiving approximately 80% of the amount of green light LG that has passed through the living body. The light-receiving unit 12 of this embodiment ensures that a sufficient amount of green light LG that has passed through the living body is incident on the first light-receiving region 51. Therefore, the detection device 3 of this embodiment does not need to increase the current consumption of the first light-emitting unit 50 to increase the amount of green light LG emitted, thereby enabling low power consumption of the light-emitting unit 11.

[0046] As shown in FIG. 4, the light receiving section 12 includes a light receiving element 120, an angle limiting filter 121, and a band pass filter (first filter) 122. The light receiving element 120 is configured by, for example, a photodiode (PD). The angle limiting filter 121 is provided so as to cover the entire light receiving surface 120a of the light receiving element 120. The angle limiting filter 121 is formed, for example, by embedding a plug 1212 made of a light-shielding material such as tungsten in a silicon oxide layer 1211 having optical transparency.

[0047] The silicon oxide layer 1211 forms an optical path that guides light to the light-receiving surface 120a of the light-receiving element 120. The plug 1212 embedded in the silicon oxide layer 1211 limits the angle of incidence of light passing through the optical path (silicon oxide layer 1211). That is, when light entering the silicon oxide layer 1211 is tilted at an angle greater than a predetermined angle with respect to the optical path, the incident light hits the plug 1212, and part of the light is absorbed by the plug 1212, while the rest is reflected. Then, the intensity of the reflected light weakens as it is repeatedly reflected before passing through the optical path, so the light that can ultimately pass through the angle limiting filter 121 is essentially limited to light whose tilt with respect to the optical path is within a predetermined limiting angle.

[0048] The angle limiting filter 121 has the property of transmitting light incident at angles smaller than a predetermined angle of incidence and cutting off light incident at angles larger than the predetermined angle of incidence without transmitting it. This makes it possible for the angle limiting filter 121 to limit the angle of incidence of light incident on the light receiving element 120. Specifically, the angle limiting filter 121 transmits light incident at a predetermined angle of incidence (hereinafter referred to as the allowable angle of incidence) by propagating inside the living body, and cuts off light incident at an angle larger than the allowable angle of incidence, such as external light such as sunlight and light that has not entered the living body.

[0049] The bandpass filter 122 is provided in a region of the light-receiving surface 120a of the light-receiving element 120 that corresponds to the first light-receiving region 51. The bandpass filter 122 has the property of selectively transmitting the wavelength band of green light LG and absorbing and cutting off light in other wavelength bands, that is, red light LR and near-infrared light LI. The bandpass filter 122 is formed, for example, by alternately laminating multiple low-refractive index layers, such as silicon oxide, and high-refractive index layers, such as titanium oxide, on the angle limiting filter 121. The bandpass filter 122 is formed in the region that corresponds to the first light-receiving region 51 using a conventionally known photolithography process.

[0050] On the other hand, in the light receiving unit 12, the second light receiving region 61 is not provided with a bandpass filter that selectively transmits the red light LR or the near-infrared light LI, but is provided with only an angle limiting filter 121. Therefore, the light receiving unit 12 can limit the angle of incidence of the red light LR or the near-infrared light LI that reaches the light receiving element 120 in the second light receiving region 61. The angle limiting filter 121 transmits, for example, the red light LR or the near-infrared light LI that has propagated inside the living body and is incident at an allowable incident angle, and cuts out light that is incident at an angle larger than the allowable incident angle, such as external light such as sunlight, or the red light LR or near-infrared light LI that has not passed through the living body.

[0051] As shown in FIG. 2, in this embodiment, the light receiving section 12 receives each light in synchronization with the light emission timing of the light emitting sections 50, 60, and 70 that are driven in a time-division manner, and generates a detection signal corresponding to each light. The light receiving unit 12 transmits the detection signals generated in the light receiving regions 51 and 61 to the output circuit 14. The output circuit 14 is configured to include, for example, an A / D converter that converts the detection signals generated by the light receiving regions 51 and 61 from analog to digital, and an amplifier circuit that amplifies the converted detection signals (both not shown), and generates a plurality of detection signals S (S1, S2, S3) corresponding to different wavelengths.

[0052] Here, the detection signal S1 is a signal representing the light receiving intensity of the first light receiving region 51 when receiving green light LG emitted from the first light-emitting unit 50. The detection signal S2 is a signal representing the light receiving intensity of the second light-receiving region 61 when receiving red light LR emitted from the second light-emitting unit 60, and the detection signal S3 is a signal representing the light receiving intensity of the second light-receiving region 61 when receiving near-infrared light LI emitted from the third light-emitting unit 70.

[0053] Generally, the amount of light absorbed by blood differs when blood vessels are dilated and when they are contracted, so each detection signal S becomes a pulse wave signal that includes a periodic fluctuation component corresponding to the pulsation component (volume pulse wave) of the artery inside the measurement site M.

[0054] The drive circuit 13 and the output circuit 14 are mounted in the form of IC chips on a wiring board together with the light-emitting unit 11 and the light-receiving unit 12. As described above, the drive circuit 13 and the output circuit 14 can also be installed outside the detection device 3.

[0055] The control device 5 is an arithmetic processing device such as a CPU (Central Processing Unit) or FPGA (Field-Programmable Gate Array), and controls the entire measuring device 100. The storage device 6 is composed of, for example, a nonvolatile semiconductor memory, and stores programs executed by the control device 5 and various data used by the control device 5. Note that a configuration in which the functions of the control device 5 are distributed across multiple integrated circuits, or a configuration in which some or all of the functions of the control device 5 are implemented by dedicated electronic circuits, may also be adopted. Note that, although FIG. 2 illustrates the control device 5 and the storage device 6 as separate elements, the control device 5 incorporating the storage device 6 may also be implemented by, for example, an ASIC (Application Specific Integrated Circuit) or the like.

[0056] The control device 5 of this embodiment executes a program stored in the storage device 6 to identify biological information of the subject from the plurality of detection signals S (S1, S2, S3) generated by the detection device 3.

[0057] Specifically, the control device (information analysis unit) 5 identifies the subject's pulse wave from the detection signal S1 that represents the intensity of green light LG received by the first light-receiving region 51. The control device 5 can identify the subject's pulse rate interval (PPI), for example, based on the detection signal S1. The control device 5 can also identify the subject's oxygen saturation (SpO2) by analyzing the detection signal S2 that represents the intensity of red light LR received by the second light-receiving region 61 and the detection signal S3 that represents the intensity of near-infrared light LI received by the second light-receiving region 61.

[0058] As described above, in the measuring device 100, the control device 5 functions as an information analysis unit that identifies biological information from the detection signal S that indicates the detection result by the detection device 3. The control device 5 causes the display device 4 to display the biological information identified from the detection signal S. It is also possible to notify the user of the measurement results by audio output. It is also preferable to configure the device to issue a warning (of possible physical dysfunction) to the user if the pulse rate or oxygen saturation level fluctuates to a value outside a predetermined range.

[0059] FIG. 7 is a diagram for explaining the operation of the detection device 3. As shown in FIG. 7, in the detection device 3 of this embodiment, a portion of the green light LG emitted from the first light emitter 50 may be reflected by the surface of the living body (measurement site M), for example, and may directly enter the first light receiving region 51 without passing through the living body. Also, external light such as sunlight may directly enter the first light receiving region 51 through a gap between the living body and the detection surface 16. Hereinafter, the green light LG that heads toward the first light receiving region 51 without passing through the living body will be referred to as the "first stray light component SL1," and the external light that heads directly toward the first light receiving region 51 will be referred to as the "second stray light component SL2."

[0060] The first stray light component SL1 has a green wavelength band, and therefore passes through the bandpass filter 122 and is incident on the angle limiting filter 121 provided below the bandpass filter 122. As described above, the angle limiting filter 121 has the property of transmitting light incident at an angle smaller than the allowable incident angle and cutting light incident at an angle larger than the allowable incident angle.

[0061] Because the first stray light component SL1 enters the first light receiving region 51 without passing through the living body, the angle of incidence of the green light LG with respect to the first light receiving region 51 becomes larger than the allowable angle of incidence of the angle limiting filter 121. In other words, the first stray light component SL1 is cut by the angle limiting filter 121. As a result, the first light receiving region 51 can suppress the incidence of the first stray light component SL1 on the light receiving surface 120a of the light receiving element 120 by the angle limiting filter 121.

[0062] The second stray light component SL2 is mostly cut by the bandpass filter 122, but the component having a green wavelength band included in the second stray light component SL2 passes through the bandpass filter 122. Here, as described above, the second stray light component SL2 enters through the gap between the living body and the detection surface 16, and therefore the angle of incidence of the second stray light component SL2 with respect to the first light receiving region 51 becomes larger than the allowable angle of incidence of the angle limiting filter 121. Therefore, a portion of the second stray light component SL2 (the component having a green wavelength band) that has passed through the bandpass filter 122 is cut by the angle limiting filter 121. As a result, the first light receiving region 51 can suppress the incidence of the second stray light component SL2 on the light receiving surface 120a of the light receiving element 120 by the angle limiting filter 121.

[0063] In this way, the detection device 3 of this embodiment can efficiently cause the green light LG that is emitted from the light-emitting unit 11 and passes through the living body to be incident on the light-receiving surface 120a of the light-receiving element 120. Furthermore, the detection device 3 of this embodiment can make it difficult for the first stray light component SL1 and the second stray light component SL2 to be incident on the light-receiving surface 120a of the light-receiving element 120.

[0064] Therefore, the first light-receiving region 51 can obtain a high S / N ratio by suppressing the incidence of the first stray light component SL1 and the second stray light component SL2, which become noise components. Therefore, the detection device 3 of this embodiment can receive the green light LG with high accuracy in the first light-receiving region 51, and therefore can suppress the power consumption of the light-emitting unit 11 by suppressing the amount of green light LG emitted by the first light-emitting section 50.

[0065] Furthermore, a portion of the red light LR emitted from the second light-emitting unit 60 or a portion of the near-infrared light LI emitted from the third light-emitting unit 70 may directly enter the second light-receiving region 61 without passing through the living body. Additionally, external light such as sunlight may directly enter the second light-receiving region 61 through a gap between the living body and the detection surface 16. Hereinafter, the red light LR or near-infrared light LI that goes directly toward the second light-receiving region 61 without passing through the living body will be collectively referred to as the "third stray light component SL3," and the external light that goes directly toward the second light-receiving region 61 will be referred to as the "fourth stray light component SL4."

[0066] The third stray light component SL3 is incident on the angle limiting filter 121 without passing through the living body, and therefore the angle of incidence of the third stray light component SL3 with respect to the second light receiving region 61 becomes larger than the allowable angle of incidence of the angle limiting filter 121. In addition, the fourth stray light component SL4 is incident from the gap between the living body and the detection surface 16, and therefore the angle of incidence of the fourth stray light component SL4 with respect to the second light receiving region 61 becomes larger than the allowable angle of incidence of the angle limiting filter 121.

[0067] Therefore, the third stray light component SL3 and the fourth stray light component SL4 are effectively cut by the angle limiting filter 121. As a result, the second light receiving region 61 can suppress the incidence of the third stray light component SL3 and the fourth stray light component SL4 on the light receiving surface 120a of the light receiving element 120 by the angle limiting filter 121.

[0068] In this way, the detection device 3 of this embodiment can efficiently allow the red light LR or near-infrared light LI emitted from the light-emitting unit 11 and passing through the living body to be incident on the light-receiving surface 120a of the light-receiving element 120. Furthermore, the detection device 3 of this embodiment can make it difficult for the third stray light component SL3 and the fourth stray light component SL4 to be incident on the light-receiving surface 120a of the light-receiving element 120.

[0069] Therefore, the second light receiving region 61 can obtain a high S / N ratio by suppressing the incidence of the third stray light component SL3 and the fourth stray light component SL4, which become noise components. According to the detection device 3 of this embodiment, the red light LR and the near-infrared light LI are efficiently received in the second light receiving region 61, so that the amount of light emitted by the second light-emitting section 60 and the third light-emitting section 70 can be reduced, thereby suppressing the power consumption of the light-emitting unit 11.

[0070] Furthermore, in the detection device 3 of this embodiment, the distance (distance D2 or distance D3) between the second light-emitting unit 60 and the third light-emitting unit 70 and the second light-receiving region 61 is greater than the distance D1 between the first light-emitting unit 50 and the first light-receiving region 51. In other words, the distance that the red light LR and the near-infrared light LI travel within the living body before entering the second light-receiving region 61 is greater than the distance that the green light LG travels within the living body before entering the first light-receiving region 51.

[0071] As shown in Figure 4, the longer the propagation distance of red light LR or near-infrared light LI within a living body, the more components that are reflected by the surface of the body and do not pass through the blood, i.e., the fewer noise components are present when determining the blood oxygen concentration. Therefore, the second light-receiving region 61 can achieve a high S / N ratio by suppressing the incidence of noise components. Therefore, the detection device 3 of this embodiment can receive red light LR or near-infrared light LI with high accuracy in the second light-receiving region 61.

[0072] On the other hand, if the propagation distance of the red light LR or near-infrared light LI within the living body becomes too long, it becomes necessary to increase the light emission intensity of the second light-emitting unit 60 or the third light-emitting unit 70. In the present embodiment, the second light-receiving region 61 is formed together with the first light-receiving region 51 on the light-receiving surface 120a of one light-receiving element 120, so that the second light-receiving region 61, the second light-emitting unit 60, and the third light-emitting unit 70 are arranged as close as possible to each other. This makes it possible to reduce the power consumption of the light-emitting unit 11 by reducing the power consumption of the second light-emitting unit 60 or the third light-emitting unit 70 while ensuring the light-receiving accuracy of the red light LR and near-infrared light LI.

[0073] Furthermore, in the present embodiment, only red light LR and near-infrared light LI are incident on the second light receiving region 61, and therefore, a bandpass filter that selectively transmits the red light LR and near-infrared light LI and blocks the green light LG is not provided in the second light receiving region 61. That is, the detection device 3 of this embodiment can employ a configuration in which only the first light receiving region 51 includes the bandpass filter 122, and the second light receiving region 61 does not include a bandpass filter. Therefore, the detection device 3 of this embodiment can achieve cost reduction by omitting the bandpass filter in the second light receiving region 61.

[0074] As described above, according to the detection device 3 of this embodiment, even when the light-emitting amount of the first light-emitting parts 50, 60, and 70 is reduced to reduce power consumption of the light-emitting unit part 11, the light-receiving part 12 can receive light that has passed through the living body with high accuracy. Furthermore, in the detection device 3 of this embodiment, the bandpass filter in the second light-receiving region 61 can be omitted, thereby reducing costs.

[0075] When the light receiving unit 12 receives the green light LG emitted from the first light emitting unit 50 and propagating inside the measurement site M in the first light receiving region 51, it generates a detection signal according to the intensity of the received light. Note that although a portion of the green light LG enters the second light receiving region 61, the green light LG that enters the second light receiving region 61 is cut by the angle limiting filter 121.

[0076] Furthermore, when the light receiving unit 12 receives, in the second light receiving region 61, the red light LR emitted from the second light emitter 60 and propagating inside the measurement site M, or the near-infrared light LI emitted from the third light emitter 70 and propagating inside the measurement site M, it generates a detection signal according to the intensity of the received light. Note that although a portion of the red light LR and near-infrared light LI enters the first light receiving region 51, the red light LR and near-infrared light LI that enters the first light receiving region 51 are cut by the bandpass filter 122.

[0077] As described above, the detection device 3 of this embodiment includes a first light-emitting unit 50 that emits green light LG, a second light-emitting unit 60 that emits red light LR having a wavelength band higher than that of the green light LG, and a light-receiving unit 12 that receives the green light LG and red light LR emitted from the first light-emitting unit 50 and the second light-emitting unit 60 and emitted from the measurement site M. The light-receiving unit 12 includes a first light-receiving region 51 that receives the green light LG, a second light-receiving region 61 that is located farther from the first light-emitting unit 50 than the first light-receiving region 51 and receives the red light LR, and a bandpass filter 122 that is located in the first light-receiving region 51 and selectively transmits the green light LG.

[0078] In this embodiment, the bandpass filter 122 is a bandpass filter that selectively transmits green light LG. The detection device 3 of this embodiment further includes a third light-emitting unit 70 that emits near-infrared light LI, and the first light-emitting unit 50, the second light-emitting unit 60, and the third light-emitting unit 70 each emit light independently in time sequence.

[0079] According to the detection device 3 of this embodiment, the green light LG, the red light LR, and the near-infrared light LI can each be received using one light receiving unit 12, so the device configuration can be reduced in size, for example to about half the size of a conventional configuration using two light receiving units. Therefore, a compact detection device 3 can be provided that can acquire both the pulse interval and oxygen saturation. Furthermore, using only one light receiving unit 12 can reduce the cost of the detection device 3.

[0080] In this embodiment, the light receiving section 12 receives the green light LG, the red light LR, and the near-infrared light LI in synchronization with the emission timing of each of the lights. This configuration allows the green light LG, red light LR, and near-infrared light LI signals to be acquired separately in time. This prevents the lights from becoming noise. This allows the use of a single light-receiving unit 12 to achieve a configuration that can detect both the pulse interval and oxygen saturation while miniaturizing the device configuration.

[0081] (Second embodiment) Next, a detection device according to a second embodiment will be described. In the first embodiment, the bandpass filter 122 is provided in the first light receiving region 51, but the detection device according to this embodiment differs from the first embodiment in that the first filter is provided only in the second light receiving region 61.

[0082] Fig. 8 is a cross-sectional view of the detection device of this embodiment. Fig. 8 shows a configuration corresponding to Fig. 4 of the first embodiment. Note that the same reference numerals are used to designate the same configurations and members as those of the first embodiment, and detailed descriptions thereof will be omitted.

[0083] As shown in FIG. 8 , the detection device 103 of this embodiment has a bandpass filter (first filter) 222 provided in the second light-receiving region 61 of the light-receiving unit 112. The bandpass filter 222 is provided in a region of the light-receiving surface 120a of the light-receiving element 120 corresponding to the second light-receiving region 61. The bandpass filter 222 has the property of selectively transmitting red light LR and near-infrared light LI and absorbing and cutting light in other wavelength bands. The bandpass filter 222 is formed, for example, by alternately stacking multiple low-refractive index layers, such as silicon oxide, and high-refractive index layers, such as titanium oxide, on the angle-limiting filter 121. The bandpass filter 222 is formed in the region corresponding to the second light-receiving region 61 using a conventionally known photolithography process.

[0084] The second light receiving region 61 of the light receiving unit 112 is disposed closer to the side plate portion 40b of the case 40 than the first light receiving region 51. Therefore, the fourth stray light component SL4 is likely to enter the second light receiving region 61 through the gap between the living body and the detection surface 16. According to the detection device 103 of this embodiment, the bandpass filter 222, which is a bandpass filter provided in the second light receiving region 61, makes it difficult for the fourth stray light component SL4 incident on the second light receiving region 61 to reach the light receiving surface 120a.

[0085] For example, if the distance between the side plate portion 40b and the second light receiving region 61 is reduced to reduce the size of the case 40, the detection device 103 becomes more susceptible to the influence of the fourth stray light component SL4. In the case of the detection device 103 of this embodiment, the influence of the fourth stray light component SL4 is suppressed by the bandpass filter 222 provided in the second light receiving region 61. Therefore, the detection device 103 of this embodiment can achieve a more compact device configuration by reducing the size of the case 40 while suppressing the influence of the noise component due to the fourth stray light component SL4.

[0086] (Third embodiment) Next, a detection device according to a third embodiment will be described. In the first embodiment, the bandpass filter 122 is provided in the first light receiving region 51. However, the detection device according to this embodiment differs from the first embodiment in that a bandpass filter is provided in each of the first light receiving region 51 and the second light receiving region 61.

[0087] Fig. 9 is a cross-sectional view of the detection device of this embodiment. Fig. 9 shows a configuration corresponding to Fig. 4 of the first embodiment. Note that the same reference numerals are used to designate the same configurations and members as those of the first embodiment, and detailed descriptions thereof will be omitted.

[0088] 9, the detection device 203 of this embodiment has a bandpass filter (first filter) 122 provided in the first light-receiving region 51 of the light-receiving unit 212, and a bandpass filter (second filter) 322 provided in the second light-receiving region 61 of the light-receiving unit 212. The bandpass filter 122 has the property of selectively transmitting the wavelength band of green light LG and absorbing and cutting light in other wavelength bands. The bandpass filter 322 has the property of selectively transmitting red light LR and near-infrared light LI and absorbing and cutting light in other wavelength bands. The bandpass filter 122 and the bandpass filter 322 are formed in regions of the light receiving surface 120a of the light receiving element 120 that correspond to the first light receiving region 51 and the second light receiving region 61, respectively, by using a conventionally known photolithography process.

[0089] According to the detection device 203 of this embodiment, the first light-receiving region 51 and the second light-receiving region 61 are provided with band-pass filters 122 and 322, respectively, and therefore it is possible to reduce the influence of noise components in each of the light-receiving regions 51 and 61. Therefore, it is possible to provide a detection device that can detect both the pulse interval and oxygen saturation with high accuracy while miniaturizing the device configuration.

[0090] FIG. 10 is a cross-sectional view of a detection device according to a modified example of this embodiment. 10 , in the detection device 303 of this modified example, the width H2 of the bandpass filter 322 provided in the second light-receiving region 61 in the direction along the X-axis (second direction) is larger than the width H1 of the bandpass filter 122 provided in the first light-receiving region 51 in the direction along the X-axis. That is, in this modified example, unlike the above embodiment, the width of the second light-receiving region 61 is larger than the width of the first light-receiving region 51 in the direction along the X-axis. Note that the light emission amount of each of the light-emitting units 50, 60, 70 may be adjusted depending on the widths of the second light-receiving region 61 and the first light-receiving region 51.

[0091] As described above, the green light LG is more likely to attenuate the longer the distance it propagates within the living body, and therefore the amount of green light LG incident on the region closer to the +X side (the second light receiving region 61 side) of the first light receiving region 51 is smaller. In the case of this modification, by using the +X side of the first light receiving region 51 as the second light receiving region 61, the degree of increase in the received amounts of red light LR and near-infrared light LI due to the expansion of the second light receiving region 61 is greater than the degree of decrease in the received amount of green light LG. Therefore, with the configuration of this modification, the detection accuracy of red light LR and near-infrared light LI can be relatively improved without changing the size of the light receiving unit 12.

[0092] The present invention has been described above based on the above-mentioned embodiment, but the present invention is not limited to the above-mentioned embodiment and can be implemented in various aspects without departing from the spirit of the present invention. For example, in the above embodiment, a human being is used as an example of a living body, but the present invention can also be applied to measuring biological information (for example, pulse rate) of other animals.

[0093] Furthermore, in the measuring device 100 of the above embodiment, the detection device 3 is provided inside the housing part 1 as an example, but the installation location of the detection device 3 is not limited to this, and it may be embedded in the belt 2, for example.

[0094] Furthermore, although a wristwatch-type configuration has been given as an example of the measuring device 100 in the above embodiment, the present invention can also be applied to other configurations, such as a necklace-type configuration worn around the subject's neck, a sticker-type configuration worn by sticking it to the subject's body, or a head-mounted display-type configuration worn on the subject's head.

[0095] Furthermore, in the above embodiment, an example has been given in which the angle limiting filter 121 is shared between the first light receiving region 51 and the second light receiving region 61, but angle limiting filters may be provided separately for the first light receiving region 51 and the second light receiving region 61. In this case, the allowable incident angles for the first light receiving region 51 and the second light receiving region 61 may be made different.

[0096] The detection device according to one aspect of the present invention may have the following configuration. A detection device according to one embodiment of the present invention comprises a first light-emitting unit that emits first light having a green wavelength band, a second light-emitting unit that emits second light having a wavelength band higher than the green wavelength band, and a light-receiving unit that receives the first light and second light emitted from the first light-emitting unit and the second light-emitting unit and emitted from a living body, respectively. The light-receiving unit has a first light-receiving region that receives the first light, a second light-receiving region that is located farther from the first light-emitting unit than the first light-receiving region and receives the second light, and a first filter that is located in either the first light-receiving region or the second light-receiving region and selectively transmits light in the corresponding wavelength band.

[0097] In the detection device according to one aspect of the present invention, a first filter may be provided in the first light receiving region, and the first filter may be a bandpass filter that selectively transmits the first light.

[0098] In the detection device according to one aspect of the present invention, a first filter may be provided in the second light receiving region, and the first filter may be a bandpass filter that selectively transmits the second light.

[0099] In one embodiment of the detection device of the present invention, the detection device may further include a third light-emitting unit that emits third light, wherein the second light-emitting unit emits light in one of the red wavelength band and the near-infrared wavelength band as the second light, and the third light-emitting unit emits light in the other of the red wavelength band and the near-infrared wavelength band as the third light, and the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit may each emit light independently in time sequence.

[0100] In the detection device according to one aspect of the present invention, the light receiving section may be configured to receive each of the first light, the second light, and the third light in synchronization with the emission timing of each of the first light, the second light, and the third light.

[0101] In one embodiment of the detection device of the present invention, the first light-emitting element and the second light-emitting element may be arranged side by side in a first direction, the first light-receiving region and the second light-receiving region may be arranged side by side in a second direction that intersects the first direction, and the first light-receiving region may be positioned closer to the first light-emitting element than the second light-receiving region in the second direction.

[0102] In one embodiment of the detection device of the present invention, the light receiving section may further include a second filter provided in the other of the first light receiving region and the second light receiving region, which selectively transmits light in the corresponding wavelength band.

[0103] In one embodiment of the detection device of the present invention, the width in the second direction of one of the first and second filters provided in the second light receiving region may be larger than the width in the second direction of the other filter provided in the first light receiving region.

[0104] The measurement device according to one aspect of the present invention may have the following configuration. A measurement device according to one aspect of the present invention includes the detection device according to the above aspect, and an information analysis unit that identifies biological information from a detection signal that indicates a detection result by the detection device. [Explanation of symbols]

[0105] 3,103,203,303...detection device, 5...control device (information analysis unit), 12...light receiving unit, 50...first light emitting unit, 51...first light receiving area, 60...second light emitting unit, 61...second light receiving area, 70...third light emitting unit, 100...measuring device, 122,222...band pass filter (first filter), 322...band pass filter (second filter), H1,H2...width, LG...green light (first light), LR...red light (second light), LI...near infrared light (third light), M...measurement site (living body).

Claims

1. a first light emitting unit that emits first light having a green wavelength band; a second light emitting unit that emits second light having a wavelength band longer than the green wavelength band; a light receiving unit configured to receive fourth light in the same wavelength band as the first light emitted from the first light emitting unit, incident on a living body, reflected and scattered inside the living body, and emitted, and fifth light in the same wavelength band as the second light emitted from the second light emitting unit, incident on the living body, reflected and scattered inside the living body, and emitted, The light receiving unit a first light receiving region that receives the fourth light and a second light receiving region that receives the fifth light, both of which are provided on a light receiving surface of one light receiving element; a first bandpass filter provided in the first light receiving region and selectively transmitting the fourth light; an angle limiting filter provided in the first light receiving region and the second light receiving region so as to cover the light receiving surface, and limiting the angle of incidence of light incident on the light receiving surface to a predetermined angle; a transmittance of the first light through the living body is lower than a transmittance of the second light through the living body; the first light-emitting unit and the second light-emitting unit are arranged side by side in a first direction, the first light receiving region and the second light receiving region are arranged side by side in a second direction intersecting the first direction, and in the second direction, the first light receiving region is located closer to the first light emitting unit than the second light receiving region; At least the first light-emitting unit and the second light-emitting unit each emit light independently in a time-sequential manner; The light receiving unit receives the fourth light and the fifth light in synchronization with at least the light emission timing of the first light emitting unit and the second light emitting unit, and generates a detection signal in response to the received light.

2. The detection device according to claim 1 , wherein in the light receiving section, the width of the first light receiving region in the second direction is smaller than the width of the second light receiving region in the second direction.

3. further comprising a third light emitting unit that emits third light; the third light emitting unit is arranged alongside the first light emitting unit and the second light emitting unit in the first direction, The second light receiving region of the light receiving unit receives sixth light having the same wavelength band as the third light emitted from the third light emitting unit, incident on the living body, reflected and scattered inside the living body, and emitted; the second light-emitting unit emits light in one of a red wavelength band and a near-infrared wavelength band as the second light, the third light-emitting unit emits light in the other wavelength band of a red wavelength band or a near-infrared wavelength band as the third light, 3. The detection device according to claim 1, wherein the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit each emit light independently in time sequence.

4. 4. The detection device according to claim 3, wherein the light receiving unit receives the fourth light, the fifth light, and the sixth light in synchronization with light emission timings of the first light emitter, the second light emitter, and the third light emitter, respectively, and generates a detection signal in response to the received light.

5. A detection device according to any one of claims 1 to 4; and an information analysis unit that identifies biological information from a detection signal that indicates a detection result by the detection device.

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