Optical system device, ppg sensor including same, blood oxygen concentration measurement device, and blood glucose level measurement device

Abstract

The purpose of the present invention is to provide an optical system device that is more compact than existing optical system devices.　An optical system device 100 comprises a light irradiation means 1 capable of emitting light, and a first light detection means 2 for detecting information regarding the light received on a light receiving surface 21. The light receiving surface 21 is located on the optical axis of the light emitted by the light irradiation means 1 and is disposed so that the light from the light irradiation means 1 does not directly irradiate the light receiving surface 21. The light irradiation means 1 may be disposed on the back surface side of the first light detection means 2. The optical system device 100 may also comprise a transmission path 3 having an entry portion 31 for allowing entry of the light from the light irradiation means 1 and an output portion 32 for outputting the light.

Description

Optical system device, PPG sensor including the same, blood oxygen concentration measurement device, and blood glucose level measurement device

[0008] ,

[0001] The present invention relates to an optical system device, a PPG sensor including the same, a blood oxygen concentration measurement device, and a blood glucose level measurement device.

[0002] There are various methods for measuring pulse, and the method of measuring with the wrist, arm, finger, etc. is common. As such pulse measurement, there is an optical type that irradiates irradiation light on the surface of the wrist, arm, finger, etc., receives the reflected reflected light, and specifies the pulse by analyzing the change in the light amount of the irradiation light and the reflected light (for example, Patent Document 1).

[0003] In recent years, due to the increasing interest in health, wristwatches and smartwatch-type health management devices equipped with a function of being wearable on the body and simply measuring pulse continuously for 24 hours have attracted attention. These pulse sensors are very useful in fitness and health management, and their accuracy and functions are improving day by day due to technological progress.

[0004] Japanese Patent Application Laid-Open No. 2-213325

[0005] Here, an optical system device such as a pulse sensor is mounted on a wristwatch or a smartwatch, etc., so there is a demand for miniaturization, and miniaturization of a light emitting element, a lens, a sensor, etc. used in the optical system device has been carried out. In addition, their integration has also been promoted. However, there has been a demand for further miniaturization.

[0006] Therefore, an object of the present invention is to provide an optical system device that is further miniaturized than existing optical system devices, a PPG sensor including the same, a blood oxygen concentration measurement device, and a blood glucose level measurement device.

[0007] In order to achieve the above object, the optical system device of the present invention includes a light irradiation means capable of irradiating light, and a first light detection means for detecting information of light received on a light receiving surface, wherein the light receiving surface is located on the optical axis of the light irradiated by the light irradiation means and is arranged so that the light of the light irradiation means is not directly irradiated on the light receiving surface.

[0008] The light irradiation means can be arranged on the back side of the first light detection means. In this case, it is preferable that the light irradiation means comprises a transmission path that causes light to be incident at an incident part and emitted at an exit part. Furthermore, it is preferable that the exit part of the transmission path be located in a part that is not on the optical axis of the light irradiated by the light irradiation means. Also, the transmission path may irradiate light from the exit part in a direction such that the elevation angle with respect to the light receiving surface is less than 90 degrees. The back side of the light irradiation means and the back side of the first light detection means may also be arranged facing each other. Furthermore, it is preferable that the transmission path is a waveguide.

[0009] Furthermore, the light irradiation means may be arranged on the light-receiving surface side of the first light detection means. In this case, the transmission path may be provided such that the reflected light from the light irradiation means is incident at an incident part, and the reflected light is emitted at an output part formed to irradiate the light-receiving surface of the first light detection means. Furthermore, it is preferable that the incident part of the transmission path is located in a part that is not on the optical axis of the light irradiated by the light irradiation means. Furthermore, it is preferable that the transmission path is a waveguide.

[0010] Furthermore, the optical system of the present invention may include an optical element that controls the light from the light irradiation means to perform an optical function. In this case, the optical element may be arranged on the output side of the transmission line. The optical element may also function as a diffuser that diffuses the light from the light irradiation means. The optical element may also create a dot pattern from the light. The optical element may also focus the light to a predetermined position.

[0011] Furthermore, the light irradiation means may be capable of selectively irradiating light of different wavelengths.

[0012] Furthermore, the optical system of the present invention may further include a second light detection means for detecting light information from the light irradiation means.

[0013] Furthermore, the optical system may have multiple such optical systems, and at least the light-receiving surface of each optical system may be positioned to receive light irradiated from the light-irradiating means of other optical systems. In this case, it is preferable that at least one set of the optical systems be arranged so that their light-receiving surfaces face each other.

[0014] Furthermore, the PPG sensor of the present invention is a PPG sensor for measuring heart rate or pulse rate, and is characterized by comprising the optical system of the present invention described above. Furthermore, the blood oxygen concentration measuring device of the present invention is for measuring the oxygen concentration in the blood, and is characterized by comprising the optical system of the present invention described above. Furthermore, the blood glucose level measuring device of the present invention is for measuring blood glucose levels, and is characterized by comprising the optical system of the present invention described above.

[0015] The optical system of the present invention can reduce its footprint (area occupied) because the light irradiation means and the first light detection means are stacked on top of each other.

[0016] This is a schematic cross-sectional view showing the optical system of the present invention. This is a schematic cross-sectional view showing a transmission line related to the optical system of the present invention. This is a schematic cross-sectional view showing another transmission line related to the optical system of the present invention. This is a schematic cross-sectional view showing an example of the output section of a transmission line related to the optical system of the present invention. This is a schematic cross-sectional view showing another optical system of the present invention. This is a schematic cross-sectional view showing an optical element related to the optical system of the present invention. This is a schematic cross-sectional view showing another optical element related to the optical system of the present invention. This is a schematic cross-sectional view showing an example of a light irradiation means related to the optical system of the present invention. This is a schematic cross-sectional view showing a second light detection means related to the optical system of the present invention. This is a schematic plan view showing the optical system of the present invention. This is a schematic cross-sectional view showing the optical system of the present invention arranged on a ring. This is a schematic cross-sectional view showing a method for manufacturing the optical system of the present invention.

[0017] The optical system 100 of the present invention will be described below. As shown in Figure 1, the optical system 100 of the present invention mainly consists of a light irradiation means 1 capable of irradiating light and a first light detection means 2 that detects information of the light received by a light receiving surface 21. The light receiving surface 21 is located on the optical axis of the light irradiated by the light irradiation means 1 (a perpendicular line including the optical axis), and is positioned so that the light from the light irradiation means 1 does not directly irradiate the light receiving surface 21. The position of the light receiving surface 21 on the optical axis of the light irradiation means 1 means that, in a plan view from the direction of the optical axis, the light-emitting surface of the light irradiation means 1 and the light-receiving surface 21 of the first light detection means 2 overlap in at least a part. Furthermore, in this plan view, the footprint (occupied area) can be reduced by the amount by which the light irradiation means 1 and the first light detection means 2 overlap.

[0018] The light irradiation means 1 is for irradiating light. Any means capable of irradiating the light necessary for the measurement purpose is acceptable. Specific examples of the light irradiation means 1 include LEDs and VCSELs (Vertical Cavity Surface Emitting Lasers) that can provide high output with low power consumption. VCSELs include single-emitter VCSELs, which have one light source 10 that can irradiate light perpendicular to the light-emitting surface, and multi-emitter VCSELs, which have multiple light sources 10. The light irradiation means 1 may also consist of multiple LEDs or VCSELs.

[0019] The wavelength of the light emitted by the light irradiation means 1 can be appropriately determined depending on the object and purpose of measurement. For example, when measuring blood flow, the light emitted by the light irradiation means 1 should be green light (electromagnetic waves with a wavelength of 500 nm to 565 nm), which is easily absorbed by red blood. This allows the amount of blood flow and pulse rate to be detected by the intensity of the green light detected by the first light detection means 2. Also, when measuring the oxygen concentration in the blood, the light emitted by the light irradiation means 1 should be red light (electromagnetic waves with a wavelength of 625 nm to 780 nm, preferably 660 nm), which is easily absorbed by hemoglobin that is not bound to oxygen, or infrared light (electromagnetic waves with a wavelength of 800 nm to 1000 nm, preferably 940 nm), which is easily absorbed by hemoglobin that is bound to oxygen. This allows the oxygen concentration in the blood to be detected by the intensity of the red light or infrared light detected by the first light detection means 2. Furthermore, if blood glucose levels are to be measured, the light emitted by the light irradiation means 1 should be mid-infrared light (electromagnetic waves with a wavelength of 2.5 μm to 4 μm) which can measure the concentration of glucose in the blood.

[0020] The first light detection means 2 is for detecting information about the light received on the light-receiving surface. The light information to be detected can be anything that can achieve the measurement purpose, such as light intensity, light quantity, or wavelength (color). Preferably, the first light detection means 2 converts the light information into digital data and outputs it. The first light detection means 2 can be anything that can detect light that has been irradiated by the light irradiation means 1 and reflected by the object on the light-receiving surface 21. For example, a photodiode (PD) that can convert the detected light into digital data can be used as the first light detection means 2. Alternatively, an existing image sensor such as a CMOS or CCD can be used as the first light detection means 2.

[0021] Furthermore, the light irradiation means 1 may be positioned on the back surface 22 side of the first light detection means 2, as shown in Figure 1(a), or on the light receiving surface 21 side of the first light detection means 2, as shown in Figure 1(b). In other words, the first light detection means 2 may be positioned on the light irradiation side of the light irradiation means 1, as shown in Figure 1(a), or on the back surface 12 side of the light irradiation means 1, as shown in Figure 1(b).

[0022] Furthermore, when the light irradiation means 1 is located on the back surface 22 side of the first light detection means 2, it is preferable that the optical system 100 of the present invention has a transmission path 3 that causes the light from the light irradiation means 1 to be incident at the incident section 31 and emitted at the exit section 32, as shown in Figure 2. In particular, the transmission path 3 becomes important when the light irradiation means 1 is smaller than the first light detection means 2. Here, the transmission path 3 is a light transmission path made using a material with optical properties. The transmission path 3 can be formed, for example, to reflect and propagate the light irradiated by the light irradiation means 1 internally. The transmission path 3 is also formed to guide the light irradiated on the back surface 22 side opposite to the light receiving surface 21 of the first light detection means 2 to the outside side facing the light receiving surface 21. This allows the light from the light irradiation means 1 to be irradiated onto the target object without waste. Specifically, the transmission path 3 is formed to bypass the outside of the first light detection means 2 from the front side of the light irradiation means 1 (the back surface 22 side of the first light detection means 2). Furthermore, the position (height) of the emission section 32 in the optical axis direction is arbitrary, but for example, it can be formed flat by aligning the position of the light-receiving surface 21 of the first light detection means 2 with the position of the emission section 32 of the transmission path 3. In the case of a transmission path 3, it is also possible to arrange the light irradiation means 1 and the first light detection means 2 so that their back surfaces face each other, as shown in Figure 2(b).

[0023] Furthermore, the transmission path 3 may be a waveguide. A waveguide is a structure that uses total internal reflection to confine light and transmit it in a certain direction while suppressing loss. Any known waveguide can be used as the waveguide, for example, as long as it can be formed to propagate the light emitted by the light irradiation means 1 by causing total internal reflection. For example, the waveguide is made of a material that is transparent to the light emitted by the light irradiation means 1 and has a higher refractive index than the surrounding materials.

[0024] Furthermore, the transmission line 3 has an inlet section 31 for injecting light into the transmission line 3 and an outlet section for emitting light from within the transmission line. The inlet section 31 can be anything as long as it can inject light from the light irradiation means 1 into the transmission line 3, but for example, it is formed by contacting the surface of the light-emitting part of the light irradiation means 1. The inlet section 31 can be anything as long as it can inject light into the transmission line 3, but for example, a grating pattern for injecting light into the transmission line 3 can be formed on the surface of the transmission line 3. The grating pattern can be formed directly on the material of the transmission line 3, or a resin formed as a grating pattern may be placed on the surface of the material of the transmission line 3. The grating pattern can be any shape as long as it can inject light into the transmission line 3, but for example, it can be a line-and-space pattern with periodically arranged inclined convex portions that can diffract light so that it is incident from the outside into the transmission line 3.

[0025] The emission section 32 is the part that emits light that has passed through the transmission line 3. The emission section 32 is positioned in a location that is not on the optical axis of the light irradiated by the light irradiation means 1. Furthermore, it is preferable that the emission section 32 is formed so that the emitted light does not directly irradiate the first light detection means 2. The emission section 32 can be anything as long as it can emit light from within the transmission line 3, but for example, a grating pattern can be formed on the surface of the transmission line 3 to emit light from within the transmission line 3. This grating pattern may be formed directly on the material of the transmission line 3, or a resin formed as a grating pattern may be placed on the surface of the material of the transmission line 3. The grating pattern can be any shape as long as it can emit light from the transmission line 3, but for example, it can be a line-and-space pattern with periodically arranged inclined convex portions that can diffract light so that it is emitted from within the transmission line 3 to the outside. The light-emitting section 32 can emit light in any direction as long as it can irradiate the object with light; for example, it may be formed to emit light in a direction perpendicular to the light-receiving surface 21.

[0026] The transmission line 3 may be formed by a first transmission line 36 and a second transmission line 37, for example, as shown in Figure 2(a). The first transmission line 36 is formed between the light-emitting side of the light irradiation means 1 and the back side of the first light detection means 2, with at least a portion extending along the back surface to the peripheral part outside the back surface of the first light detection means 2. The second transmission line 37 is formed to extend from the end of the first transmission line 36 in a vertical direction (in the direction of the optical axis of the light irradiated by the light irradiation means 1) to the light-receiving surface side of the first light detection means 2. The incident portion 31 is formed between the first transmission line 36 and the light-emitting side of the light irradiation means 1. The outgoing portion is formed at the end of the second transmission line 37 on the light-receiving surface side. The connection portion 38 between the first transmission line 36 and the second transmission line 37 may be vertical, as shown in Figure 2(a), but may also be connected diagonally, as shown in Figure 3(a), or curved, as shown in Figure 3(b). By configuring it in this way, light can be propagated more efficiently.

[0027] Furthermore, as shown in Figure 4, when using the first light detection means 2 with an object such as a finger placed on the light-receiving surface 21, the emission unit 32 may be formed so that the emitted light is directed toward the object on the light-receiving surface 21. Specifically, the emission unit 32 should be formed so that the elevation angle of the emitted light with respect to the light-receiving surface 21 is less than 90 degrees, preferably 45 degrees or less, and more preferably 0 degrees. This allows the light emitted from the emission unit 32 to be efficiently irradiated onto the object on the light-receiving surface 21.

[0028] The transmission line 3 can be made of any material as long as it can receive light from the light irradiation means 1 at the incident part 31 and emit the light at the exit part formed in a position where the light does not directly irradiate the first light detection means 2. However, a material with a transmittance of at least 90% of the light irradiated by the light irradiation means 1 is preferred. Examples of such materials include resins such as polydimethylsiloxane (PDMS), polyimide resin, acrylic resin, and photoresist resin, as well as glass. The transmission line 3 may also be a gas such as air. Furthermore, the transmission line 3 can be manufactured in any way, for example, by conventionally known methods such as imprinting or injection molding.

[0029] In the above description, the transmission path was described as one in which the light emitted by the light irradiation means 1 is propagated by reflection or total internal reflection due to the difference in refractive index between the inside and outside. However, it is not limited to this, and for example, specular reflection using metal or the like can also be used.

[0030] Furthermore, when the light irradiation means 1 is arranged on the light-receiving surface 21 side of the first light detection means 2, it is preferable that the optical system 100 of the present invention has a transmission path 4, as shown in Figure 5, which is formed to cause reflected light from the light irradiation means 1 to be incident at an incident section 41 and to emit the reflected light at an output section 42 that is formed so as to irradiate the light-receiving surface 21 of the first light detection means 2. In particular, the transmission path 4 becomes important when the first light detection means 2 is smaller than the light irradiation means 1. Here, the transmission path 4 is a light transmission path made using a material with optical properties. The transmission path 4 can be formed, for example, to propagate reflected light that is reflected when the light irradiated by the light irradiation means 1 strikes an object. The transmission path 4 is also formed to guide the reflected light that is reflected when the light irradiated by the light irradiation means 1 strikes an object to the light-receiving surface 21 of the first light detection means 2, which is arranged on the back surface 12 side of the light irradiation means 1. Specifically, the transmission path 4 is formed to bypass the light irradiation means 1 by passing along its side and reaching the light-receiving surface 21 of the first light detection means 2. The position (height) of the incident portion 41 in the optical axis direction is arbitrary, but for example, the position of the incident portion 41 of the transmission path 3 can be aligned with the position of the light-emitting surface of the light irradiation means 1 to form a flat surface. When the transmission path 4 is present, it is also possible to arrange the light irradiation means 1 so that its back surface 12 and the back surface 22 of the first light detection means 2 face each other, as shown in Figure 5(b).

[0031] Furthermore, the transmission path 4 may be a waveguide. A waveguide is a structure that uses total internal reflection to confine light and transmit it in a certain direction while suppressing loss. Any known waveguide can be used as long as it is formed so that the reflected light from the light irradiation means 1 is totally reflected inside and propagated. For example, the waveguide is made of a material that is transparent to the reflected light from the light irradiation means 1 and has a higher refractive index than the surrounding materials.

[0032] Furthermore, the transmission line 4 has an inlet section 41 for injecting light into the transmission line and an outlet section 42 for emitting light from the transmission line. The inlet section 41 is positioned in a part that is not on the optical axis of the light irradiated by the light irradiation means 1. The inlet section 41 can be any shape as long as it can allow reflected light from the light irradiation means 1 to be injected into the transmission line 4, but for example, it is formed on the same plane as the surface of the light-emitting part of the light irradiation means 1. The inlet section 41 can be any shape as long as it can allow light to be injected into the transmission line 4, but for example, a grating pattern for injecting light into the transmission line 4 can be formed on the surface of the transmission line 4. The grating pattern can be formed directly on the material of the transmission line 4, or a resin formed as a grating pattern may be placed on the surface of the material of the transmission line 4. The grating pattern can be any shape as long as it can allow light to be injected into the transmission line 4, but for example, it can be a line-and-space pattern with periodically arranged inclined convex parts that can diffract light so that it is injected into the transmission line 4 from the outside.

[0033] The emission section 42 is the part that emits light that has passed through the transmission line 4. Preferably, the emission section 42 is formed so that the emitted light is directly irradiated onto the light-receiving surface 21 of the first light detection means 2. The emission section 42 can be anything as long as it can emit light from within the transmission line 4, but for example, a grating pattern can be formed on the surface of the transmission line 4 to emit light from within the transmission line 4. The grating pattern can be formed directly on the material of the transmission line 41, or a resin formed as a grating pattern can be placed on the surface of the material of the transmission line 41. The grating pattern can be any shape as long as it can emit light from the transmission line 4, but for example, it can be a line-and-space pattern with periodically arranged inclined convex portions that can diffract light so that it is emitted from within the transmission line 4 to the outside. The emission section 42 can emit light in any direction as long as it can emit reflected light to the light-receiving surface, for example, it can be formed to emit light in a direction perpendicular to the light-receiving surface 21.

[0034] Furthermore, the optical system 100 of the present invention may include an optical element 5 that controls the light emitted by the light irradiation means 1 to perform an optical function, as shown in Figures 6 and 7. The optical element 5 may directly or indirectly control the light emitted by the light irradiation means 1. For example, Figure 6 is an example of an optical system 100 that directly controls the light emitted by the light irradiation means 1. Figure 7 is an example of an optical system 100 in which the optical element 5 is arranged on the output side of the transmission line and indirectly controls the light emitted by the light irradiation means 1. Although not shown, it is also possible to arrange multiple optical elements 5 of the same or different types. For example, it is possible to arrange the optical element 5 both directly in front of the light irradiation means 1 and on the output side of the transmission line 3. Furthermore, the optical element 5 may be formed integrally with the light irradiation means 1, as shown in Figures 6(a) and (b), or it may be formed separately from the light irradiation means 1, as shown in Figure 6(c). Furthermore, the optical element 5 may be formed integrally with the output portion 32 of the transmission line 3, as shown in Figure 7(a), or it may be formed separately from the output portion 32 of the transmission line 3, as shown in Figure 7(b).

[0035] The optical element 5 consists of, for example, a first surface on which light from the light irradiation means 1 is incident, and a second surface on which controlled light is emitted. The optical element 5 has a functional surface on at least one or both of the first and second surfaces that performs an optical function. The functional surface can be any type that controls the light from the light irradiation means 1 to perform an optical function. For example, the functional surface may control transmitted light to create diffused light or a dot pattern. The shape of the functional surface may be, for example, an uneven shape such as a microlens array. The optical element 5 can be, for example, a diffuser that diffuses light. When the optical element 5 is placed between the light irradiation means 1 and the incident part 31 of the transmission line 3, as shown in Figure 6(a), the light from the light irradiation means 1 can be efficiently incident into the transmission line. The optical element 5 may also be one that creates a dot pattern from the light emitted from the exit part 32 of the transmission line 3. Furthermore, the optical element 5 may be used to focus the light emitted from the emission section 32 of the transmission line 3 to a predetermined position.

[0036] The optical element 5 can be made of any material that can control the light from the light irradiation means 1 to exhibit optical functions, such as resins like polydimethylsiloxane (PDMS) or glass. The optical element 5 can also be manufactured in any way, such as using conventionally known methods like imprint printing or injection molding.

[0037] The light irradiation means 1 may be capable of selectively irradiating light of different wavelengths. For example, the light irradiation means 1 may be configured to have multiple light sources, each of which can irradiate light of different wavelengths. Specifically, for example, as shown in Figure 8, the light irradiation means 1 may include one or more light sources 10A that irradiate infrared light, one or more light sources 10B that irradiate red light, and one or more light sources 10C that irradiate green light. As such a light irradiation means 1, an LED or the like capable of selectively irradiating light of different wavelengths can be used. Here, the light sources 10A to 10C can be arranged in parallel along the transmission line 3, as shown in Figure 8(a). Also, the light sources 10A to 10C can be arranged in multiple stages across the transmission line 3, as shown in Figure 8(b).

[0038] Furthermore, the characteristics of the light emitted by the light irradiation means 1 may change due to environmental factors such as temperature, or deterioration due to lifespan or damage. Therefore, the optical system 100 of the present invention may further include a second light detection means 7 for detecting information about the light emitted by the light irradiation means 1, as shown in Figure 9. The light information detected by the second light detection means 7 can be anything that can achieve the measurement purpose, but examples include light intensity, light quantity, wavelength (color), etc. It is preferable that the second light detection means 7 converts the light information into digital data and outputs it. The second light detection means 7 can be anything that can at least detect the light irradiated by the light irradiation means 1. For example, a photodiode (PD) that can convert the detected light into digital data can be used as the second light detection means 7. Alternatively, an existing image sensor such as a CMOS or CCD can be used as the second light detection means 7.

[0039] The second light detection means 7 can be positioned anywhere as long as it can detect information about the light emitted by the light irradiation means 1 before it is irradiated onto an object or the like. For example, in order to detect information about the light emitted from the emission section 32, the second light detection means 7 can be positioned in contact with a part of the transmission line 3 on the emission section 32 side, as shown in Figure 9(a). Although not shown, it is also possible to position the second light detection means 7 at a distance from a part of the transmission line 3. Furthermore, in order to detect information about the light emitted from the light irradiation means 1, the second light detection means 7 can be positioned on a part of the optical axis of the light irradiation means 1, as shown in Figure 9(b). Also, as shown in Figure 9(c), the second light detection means 7 may be positioned in the middle of the transmission line 3. In this case, for example, an emission section 33 can be formed in a part of the first transmission line 36 of the transmission line 3, and the second light detection means 7 can be positioned in parallel with the light irradiation means 1, so that the information about the light emitted from the emission section 33 is detected by the second light detection means 7. Although not shown in the diagram, it is also possible to form an emission section in a part of the second transmission line 37 of the transmission line 3 and to place the second light detection means 7 on the side of the second transmission line 37, so that the light information emitted from the emission section 33 is detected by the second light detection means 7.

[0040] By configuring the second light detection means 7 in this way, it is possible to monitor the lifespan and deterioration of the light irradiation means 1 due to damage, and to use it for eye safety in the event of damage to the optical system 100. Furthermore, by detecting the light information from the light irradiation means 1 with the second light detection means 7, and detecting the light information after irradiation of the object with the first light detection means 2, it is possible to monitor and compare the light information before and after irradiation of the object, thereby enabling more accurate measurements.

[0041] The optical system 100 of the present invention may consist of one light irradiation means 1 and one first light detection means 2, or it may consist of multiple units of either the light irradiation means 1 or the first light detection means 2, or both. The optical system 100 of the present invention may also have a housing 8 that encloses the light irradiation means 1, the first light detection means 2, the transmission line 3, the transmission line 4, the optical element 5, the second light detection means 7, etc. Furthermore, the external shape of the light irradiation means 1, the first light detection means 2, the transmission line 3, the transmission line 4, the housing 8, and the optical system 100 comprising these may be formed in any way. For example, the external shape of the optical system 100 of the present invention can be (a) a rectangle, (b) a circle, (c) a regular hexagon, etc., as shown in Figure 10, when viewed in a plan view from the optical axis direction of the light irradiation means 1. By making the external shape of the optical system 100 a rectangle, the handling of the optical system 100 can be improved, and the degree of freedom in placement when mounting the optical system 100 on other devices can be increased. Furthermore, by making the outer shape of the optical system 100 circular, the shape of the light-inlet and outlet windows in the device on which the optical system 100 is mounted can also be made circular, which is advantageous in terms of design, processability, and maintainability. In addition, by making the outer shape of the optical system 100 hexagonal, the arrangement density can be increased when many optical system 100s are mounted on other devices.

[0042] Furthermore, the optical system of the present invention may have a plurality of the above-described optical system 100, and at least the light-receiving surface of each optical system 100 may be positioned to receive light irradiated from the light irradiation means of other optical system 100. With this configuration, the first light detection means can not only detect information about the light reflected by the object from the light irradiation means, but also information about the light reflected or transmitted by the object from the light irradiation means 1 of other optical system 100. Therefore, information about the object to be measured can be detected more accurately.

[0043] The arrangement of the optical system devices 100 may be in any manner. For example, as shown in FIG. 11(b), three optical system devices 100a to 100c can be arranged at intervals of 120 degrees. However, more preferably, at least one set or more of the optical system devices 100 are arranged such that their light receiving surfaces face each other. For example, FIG. 11(a) shows an example in which a set of two optical system devices 100a and 100b are arranged on the ring 9 so as to face each other. Also, FIG. 11(c) shows an example in which two sets are arranged on the ring 9 such that a set of two optical system devices 100a and 100c face each other, and a set of two optical system devices 100b and 100d face each other. Such a ring 9 can be used, for example, to insert a human finger, arm, etc. into the hole 91 in the center of the ring to measure objects such as blood flow and blood glucose level.

[0044] Next, application examples of the optical system device 100 of the present invention will be given. For example, in a PPG sensor for measuring a heartbeat or a pulse, the optical system device 100 of the present invention can be used in a measurement unit that measures the heartbeat or the pulse. In this case, as the light irradiated by the light irradiation means 1 of the optical system device 100, for example, green light (an electromagnetic wave having a wavelength of 500 nm or more and 565 nm or less) can be used. Also, in a blood oxygen concentration measuring device for measuring the blood oxygen concentration, the optical system device 100 of the present invention can be used in a measurement unit that measures the blood oxygen concentration. In this case, as the light irradiated by the light irradiation means 1 of the optical system device 100, for example, red light (an electromagnetic wave having a wavelength of 625 nm or more and 780 nm or less, preferably 660 nm) or infrared light (an electromagnetic wave having a wavelength of 800 nm or more and 1000 nm or less, preferably 940 nm) can be used. Also, in a blood glucose level measuring device for measuring the blood glucose level, the optical system device 100 of the present invention can be used in a measurement unit that measures the blood oxygen concentration. In this case, as the light irradiated by the light irradiation means 1 of the optical system device 100, for example, mid-infrared light (an electromagnetic wave having a wavelength of 2.5 μm or more and 4 μm or less) can be used.

[0045] Next, an example of a method for manufacturing the optical system 100 of the present invention will be described with reference to Figure 12. First, as shown in Figure 12(a), the first light detection means 2 is placed on a temporary substrate 110. At this time, the first light detection means 2 is positioned so that the light-receiving surface 21 faces the temporary substrate 110. Here, if multiple optical system devices 100 are to be manufactured, multiple first light detection means 2 may be placed on the temporary substrate 110. Next, as shown in Figure 12(b), the back surface of the first light detection means 2 is molded with a resin for the light transmission path so that it is filled. The resin used is a material that can transmit light from the light irradiation means 1. After molding, as shown in Figure 12(c), the light irradiation means 1 is placed on the resin for the transmission path. At this time, the light irradiation means 1 is positioned so that the light-receiving surface 21 is located on the optical axis of the light irradiated by the light irradiation means 1, and the light from the light irradiation means 1 faces the first light detection means 2. When manufacturing multiple optical system devices 100, a light irradiation means 1 can be placed for each corresponding first light detection means 2. Next, as shown in Figure 12(d), the first light detection means 2 and the light irradiation means 1 are cut together as a pair using a dicer or the like. After that, the temporary substrate 110 is peeled off or removed to create individual chips. Next, as shown in Figure 12(e), the individual chips are placed on the temporary substrate 120, and as shown in Figure 12(f), they are molded with a sealing material such as resin. After molding with the sealing material, through holes are opened in the electrode parts of the light irradiation means 1 and the first light detection means 2 using machining or the like. After opening, as shown in Figure 12(g), the electrode parts and wiring 130 are connected to the openings using lithography, vacuum deposition, plating, or the like, and the optical system device 100 is completed. The temporary substrate 120 can be peeled off or removed after the completion of the optical system device 100, as shown in Figure 12(h).

[0046] 1 Light irradiation means 2 First light detection means 3 Transmission line 4 Transmission line 5 Optical element 7 Second light detection means 8 Housing 9 Ring 10a Light source 10b Light source 10c Light source 12 Back surface 21 Light receiving surface 22 Back surface 31 Incident part 32 Outlet part 33 Outlet part 36 First transmission line 37 Second transmission line 38 Connection part 100 Optical system

Claims

1. An optical system comprising a light irradiation means capable of irradiating light, and a first light detection means for detecting information of light received on a light receiving surface, wherein the light receiving surface is located on the optical axis of the light irradiated by the light irradiation means, and is arranged such that the light from the light irradiation means does not directly irradiate the light receiving surface.

2. The optical system according to claim 1, characterized in that the light irradiation means is arranged on the back side of the first light detection means.

3. The optical system according to claim 2, characterized in that it comprises a transmission path that causes light from the light irradiation means to be incident at an incident section and emitted at an exit section.

4. The optical system according to claim 3, characterized in that the output portion of the transmission line is located in a portion not on the optical axis of the light irradiated by the light irradiation means.

5. The optical system according to claim 3, characterized in that the transmission line irradiates light from the emission unit in a direction such that the elevation angle with respect to the light-receiving surface is less than 90 degrees.

6. The optical system according to claim 2, characterized in that the back surface of the light irradiation means and the back surface of the first light detection means are arranged to face each other.

7. The optical system according to claim 1, characterized in that the light irradiation means is arranged on the light-receiving surface side of the first light detection means.

8. The optical system according to claim 7, further comprising a transmission path that causes reflected light from the light irradiation means to be incident at an incident section and emitted at an output section formed such that the reflected light is irradiated onto the light-receiving surface of the first light detection means.

9. The optical system according to claim 8, characterized in that the incident portion of the transmission line is located in a portion not on the optical axis of the light irradiated by the light irradiation means.

10. The optical system according to claim 3 or 8, characterized in that the transmission line is a waveguide.

11. The optical system according to any one of claims 1 to 9, further comprising an optical element that controls the light from the light irradiation means to perform an optical function.

12. The optical system according to claim 11, characterized in that the optical element is arranged on the output side of the transmission line.

13. The optical system according to claim 11, characterized in that the optical element is a diffuser that diffuses light.

14. The optical system according to claim 11, characterized in that the optical element is one that transforms light into a dot pattern.

15. The optical system according to claim 11, characterized in that the optical element focuses light to a predetermined position.

16. The optical system according to any one of claims 1 to 9, characterized in that the light irradiation means is capable of selectively irradiating light of different wavelengths.

17. The optical system according to any one of claims 1 to 9, further comprising a second light detection means for detecting light information from the light irradiation means.

18. An optical system comprising a plurality of optical system devices according to any one of claims 1 to 9, wherein at least the light-receiving surface of each optical system device is positioned to receive light irradiated from the light-irradiating means of the other optical system devices.

19. The optical system according to claim 18, characterized in that at least one set of the optical system according to any one of claims 1 to 9 is arranged so that its light-receiving surfaces face each other.

20. A PPG sensor for measuring heart rate or pulse rate, characterized by comprising an optical system according to any one of claims 1 to 9.

21. A blood oxygen concentration measuring device for measuring the oxygen concentration in the blood, characterized in that it comprises an optical system according to any one of claims 1 to 9.

22. A blood glucose measuring device for measuring blood glucose levels, characterized by comprising an optical system according to any one of claims 1 to 9.

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