Reflective optical sensor

Abstract

Provided is a reflective optical sensor 10 comprising: a base material 11; a light emitting element 12 and a light receiving element 13 provided on the base material 11; and a light shielding wall 14 provided between the light emitting element 12 and the light receiving element 13. The relationship between a distance de of the light emitting element 12 and the light shielding wall 14, a distance dr between the light receiving element 13 and the light shielding wall 14, and a thickness t of the light shielding wall 14 satisfies the expression de + dr < t, and the shortest distance between a region which does not belong to any of a region where the light emission from the light emitting element 12 does not reach an object to be measured and a region where reflected light of the light emission from the object to be measured or scattered light from the object to be measured is not input to the light receiving element 13, and a sensor surface where the reflective optical sensor 10 and the object to be measured are in contact with each other is 0.2 mm or more and 0.3 mm or less.

Description

Reflective Optical Sensor

[0001] The present invention relates to a reflective optical sensor.

[0002] Known examples of devices that use reflective optical sensors to optically and non-invasively detect biological information include pulse oximeters that measure blood oxygen saturation and blood glucose meters that measure blood glucose levels. In such reflective optical sensors, a light-emitting element such as a light-emitting diode (LED) irradiates a fingertip or the like with light, and a light-receiving element such as a photodiode receives the reflected light from the biological subject (specifically, blood in the blood vessels), thereby detecting the biological information as a change in the amount of received light.

[0003] To date, Patent Document 1 has reported a photoreflector having two light-emitting elements and one light-receiving element in the same package, which includes a photo sensor having a light-emitting element (12) and a light-receiving element (13) mounted on a substrate (11), a light-transmitting resin (15) that seals each of these elements, and a photoreflector having a light-shielding resin (2), as shown in FIG. 8, in which a light-shielding wall (2a) is formed by the light-shielding resin (2) between the light-emitting element (12) and the light-receiving element (13), and an eave (2b) that is connected to the light-shielding wall (2a) and narrows the light-emitting surface above the light-emitting element (12).

[0004] International Publication No. 2017 / 094089

[0005] However, in the conventional photoreflector described in Patent Document 1, the angle of light emitted from the light-emitting element is limited by a canopy, thereby effectively irradiating the blood flowing through the blood vessels in the living body being measured. However, the angle of light incident on the light-receiving element is not limited, so signals from the surface of the living body are also detected, which poses the problem of these signals becoming noise.

[0006] The present invention aims to solve the above-mentioned conventional problems and achieve the following object: That is, the present invention aims to provide a reflective optical sensor having a simple structure in which noise due to light from the surface of the measurement object is reduced.

[0007] The means for solving the above problems are as follows: <1> A reflective optical sensor having a substrate, a light emitting element and a light receiving element provided on the substrate, and a light shielding wall provided between the light emitting element and the light receiving element, wherein a distance d between the light emitting element and the light shielding wall is ｅ and the distance d between the light receiving element and the light shielding wall ｒ The relationship between the thickness t of the light-shielding wall and the thickness t of the light-shielding wall is expressed by the following equation: ｅ +d ｒ <t> is satisfied, and the shortest distance between the reflective optical sensor and the sensor surface with which the measurement object is in contact and a region that does not belong to either a region where light emitted from the light-emitting element does not reach the measurement object or a region where reflected light of the light emitted from the measurement object or scattered light from the measurement object is not input to the light-receiving element is 0.2 mm or more and 0.3 mm or less. <2> The reflective optical sensor according to <1>, wherein the light-emitting element is two or more light-emitting elements arranged adjacent to each other, and the emission wavelengths of the two or more light-emitting elements are different from each other. <3> The reflective optical sensor according to <1> or <2>, wherein the base material has a light-shielding frame that, together with the light-shielding wall, partitions the light-emitting element and the light-receiving element, and the shape of the inside of the partition formed by the light-shielding wall and the light-shielding frame is a chamfered quadrangular pillar. <4> The reflective optical sensor according to <3>, wherein the thickness of the light-shielding frame is smaller than the thickness of the light-shielding wall. <5> The reflective optical sensor according to any one of <1> to <4>, wherein the base material is a glass epoxy substrate having a light transmittance of 1% or less through the thickness of the base material, the light-shielding wall is a glass epoxy substrate having a light transmittance of 1% or less through the thickness of the light-shielding wall, and the light-shielding wall is provided on the base material via a light-shielding adhesive.

[0008] According to the present invention, it is possible to solve the above-mentioned problems in the prior art, achieve the above-mentioned object, and provide a reflective optical sensor having a simple structure in which noise caused by light from the surface of the object to be measured is reduced.

[0009] FIG. 1 is a schematic cross-sectional view showing an example of a reflective optical sensor of this embodiment. FIG. 2 is a schematic top view showing an example of a reflective optical sensor of this embodiment. FIG. 3 is a schematic cross-sectional view showing a non-sensing distance of the reflective optical sensor of this embodiment. FIG. 4 is a schematic cross-sectional view showing a non-sensing distance of a reflective optical sensor of the prior art. FIG. 5 is a schematic top view showing another example of the reflective optical sensor of this embodiment. FIG. 6 is a schematic top view showing another example of the reflective optical sensor of this embodiment. FIG. 7 is a schematic top view showing another example of the reflective optical sensor of this embodiment. FIG. 8 is a schematic view showing an example of a reflective optical sensor of the prior art. FIG. 9 is a schematic view showing another example of a reflective optical sensor of the prior art.

[0010] (Reflection-type optical sensor) The reflection-type optical sensor of the present invention is a reflection-type optical sensor having a base material, a light-emitting element and a light-receiving element provided on the base material, and a light-shielding wall provided between the light-emitting element and the light-receiving element, wherein the distance d between the light-emitting element and the light-shielding wall is ｅ and the distance d between the light receiving element and the light shielding wall ｒ The relationship between the thickness t of the light-shielding wall and the thickness t of the light-shielding wall is expressed by the following equation: ｅ +d ｒ <t, and the shortest distance between an area that does not belong to either an area where the light emitted from the light-emitting element does not reach the object to be measured or an area where the reflected light of the light emitted from the object to be measured or the scattered light from the object to be measured is not input to the light-receiving element and the reflective optical sensor and the sensor surface with which the object to be measured comes into contact is 0.2 mm or more and 0.3 mm or less.

[0011] Here, an example of a reflective optical sensor of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a reflective optical sensor of this embodiment, and FIG. 2 is a schematic top view of FIG. 1. As shown in FIGS. 1 and 2, a reflective optical sensor 10 has a substrate 11, a light-emitting element 12 and a light-receiving element 13 provided on the substrate 11, and a light-shielding wall 14 provided between the light-emitting element 12 and the light-receiving element 13. In this embodiment, an aspect having one light-emitting element 12 is shown, but as shown in FIG. 5 and the like described below, two or more light-emitting elements may be provided.

[0012] The reflective optical sensor 10 has a conductive wire 22a and a conductive portion 23a for supplying electric power from the outside to the electrode 12e of the light-emitting element 12, and a conductive wire 22b and a conductive portion 23b for outputting a photocurrent from the electrode 13e of the light-receiving element 13 to the outside. The light-emitting element 12 and the light-receiving element 13 are electrically connected to the conductive wire 22 and the conductive portion 23 so as to be able to supply electric power and output a photocurrent. The light-emitting element 12 and the light-receiving element 13 are provided adjacent to the light-shielding wall 14, while the conductive portions 23a and 23b to which the conductive wires 22a and 22b are connected are disposed and connected distally to the light-shielding wall 14.

[0013] The reflective optical sensor 10 further includes a light-shielding frame 21 on the base material 11, which, together with the light-shielding wall 14, partitions the light-emitting element 12 and the light-receiving element 13. The light-shielding wall 14 and the light-shielding frame 21 are attached to the base material 11 via a light-shielding adhesive layer 24. The compartment housing the light-emitting element 12 and the compartment housing the light-receiving element 13 are each filled with a transparent resin 25. The transparent resin 25 is a transparent resin that is transparent to the light emitted by the light-emitting element 12 and the light reflected or scattered from the measurement object, such as an epoxy resin. The transparent resin 25 seals the light-emitting element 12 and the light-receiving element 13 to protect them from impact, moisture, and the like. The surface (top surface) of the transparent resin 25 is formed flat and at the same height as the light-shielding wall 14 and the light-shielding frame 21, forming a sensor surface that comes into contact with the measurement object. The light-emitting element 12 and the light-receiving element 13 are attached to the base material 11 via an optional adhesive layer 26.

[0014] As shown in FIGS. 1 and 2, the reflective optical sensor 10 is configured such that the distance d between the light emitting element 12 and the light blocking wall 14 is ｅ and the distance d between the light receiving element 13 and the light blocking wall 14 ｒ and the thickness of the light-shielding wall 14 is t, the relationship between these is expressed by the following equation: ｅ +d ｒ <t. In other words, the light emitting element 12 and the light receiving element 13 satisfy d ｅ +d ｒ The light emitting element 12 and the light receiving element 13 are adjacent to each other via the light blocking wall 14 so as to satisfy the relationship d<t. ｅ and distance d ｒThis means that a light-shielding wall 14 having a thickness t that is relatively large compared to the light-emitting element 12 and the light-receiving element 13 is provided between the light-emitting element 12 and the light-receiving element 13 .

[0015] Fig. 3 is a schematic cross-sectional view showing the non-sensing distance of the reflective optical sensor of this embodiment, and Fig. 4 is a schematic cross-sectional view showing the non-sensing distance of a reflective optical sensor of the prior art. As shown in Fig. 3, area A1 where light emitted from the light-emitting element 12 does not reach the measurement object, and area A2 where reflected light of the light emitted from the measurement object or scattered light from the measurement object is not input to the light-receiving element 13 can be referred to as areas not sensed by the reflective optical sensor (non-sensing area). An area (referred to as area A3) that does not belong to either non-sensing area A1 or A2, and the shortest distance (also referred to as non-sensing distance) d between the reflective optical sensor 10 and the sensor surface where the measurement object comes into contact, is 0.2 mm or more and 0.3 mm or less. Here, the shortest distance d between the area A3 and the sensor surface is the length (shortest distance) between the parts where the area A3 and the sensor surface are closest to each other, and in Figure 3, it is the distance indicated by d between the sensor surface of the reflective optical sensor and the intersection of the boundary line of area A1, which forms an angle θ2 with the side surface of the light-shielding wall 14, and the boundary line of area A2, which forms an angle θ4 with the side surface of the light-shielding wall 14.

[0016] As shown in FIG. 3, the reflective optical sensor 10 ｅ +d ｒ <t, the d shown in FIG. ｅ +d ｒ Compared to conventional reflective optical sensors that do not satisfy <t, the overlap of the non-sensing areas represented by areas A1 and A2 can be made wider, and therefore the non-sensing distance d can be set in the range of 0.2 mm or more and 0.3 mm or less.

[0017] For example, when using the reflective optical sensor 10 to detect biological information in blood, such as blood oxygen saturation or blood glucose concentration, the sensor surface of the reflective optical sensor 10 comes into contact with the living body being measured. The skin of a living body is structured into three layers: the epidermis, dermis, and subcutaneous tissue, starting from the surface. The epidermis, which is approximately 0.2 mm thick, has few blood vessels. The dermis and subcutaneous tissue, which are approximately 2 mm thick together, are rich in blood vessels. Detection of reflected or scattered light from the skin surface, such as the epidermis, leads to noise. The reflective optical sensor of this embodiment, with a non-detectable distance d set to 0.2 mm or greater, does not detect noise caused by light from the surface of the measurement object. Furthermore, with a non-detectable distance d set to 0.3 mm or less, can efficiently detect signals from the target measurement site (blood in the blood vessels).

[0018] In Figure 3, n1 represents the refractive index of the transparent resin 25, and n2 represents the refractive index of the object to be measured. θ1 and θ2 are angles that determine the non-sensing area A1, representing the maximum incident angle θ1 on the light-emitting side and the maximum exit angle θ2 on the light-emitting side, respectively. θ3 and θ4 are angles that determine the non-sensing area A2, representing the maximum incident angle θ4 on the light-receiving side and the maximum receiving angle θ3 on the light-receiving side. θ1 and θ3 are determined by the dimensions of the light-emitting element and the light-receiving element, the shapes of the light-emitting and light-receiving areas, the height of the light-shielding wall, and the distance between each element and the light-shielding wall, while θ2 and θ4 are determined from θ1 or θ3 and n1 and n2. The non-sensing distance d is determined by θ2 and θ4 and the thickness t of the light-shielding wall.

[0019] The materials for the substrate 11, the light-shielding wall 14, and the light-shielding frame 21 are not particularly limited and can be selected appropriately depending on the purpose, but it is preferable that at least one of the members is glass epoxy, and it is more preferable that all of the members are glass epoxy. By using glass epoxy, processing by cutting becomes possible in the manufacture of the reflective optical sensor. Since there is no need to use a mold for resin molding, this is advantageous in terms of manufacturing, processing, and cost, especially in small-lot production.

[0020] The substrate 11 is preferably a glass epoxy substrate having a light transmittance of 1% or less across the thickness of the substrate 11. The light-shielding wall 14 is also preferably a glass epoxy substrate having a light transmittance of 1% or less across the thickness of the light-shielding wall 14. In particular, a light transmittance of 1% or less across the thickness of the light-shielding wall 14 can prevent light from passing through the light-shielding wall 14 from the light-emitting element 12 to the light-receiving element 13, thereby reducing detection noise. Here, "light transmittance across the thickness of the substrate" refers to the light transmittance across the thickness of a substrate having a specific thickness. "Light transmittance across the thickness of the light-shielding wall" refers to the light transmittance across the thickness of a light-shielding wall having a specific thickness, the thickness of the light-shielding wall being perpendicular to the thickness of the substrate. The light-shielding frame is similarly defined as a light-shielding frame having a specific thickness.

[0021] Glass epoxy substrates have different optical properties in the thickness direction (stacking direction) and in-plane direction, and general glass epoxy substrates may have low light-blocking properties in the in-plane direction. An example of a glass epoxy substrate with high light-blocking properties and low light transmittance in the thickness direction and in-plane direction is the light-blocking black printed wiring board material CS-3667B (manufactured by Risho Kogyo Co., Ltd.). The light transmittance can be appropriately selected as long as it is 1% or less at the wavelengths of emitted and received light to be measured. However, it is preferable that the light transmittance be 1% or less at wavelengths of 650 nm to 1,310 nm, and it is more preferable that the light transmittance be 1% or less at wavelengths of 250 nm to 2,000 nm.

[0022] The light-shielding wall 14 and the light-shielding frame 21 are preferably provided via an adhesive layer 24 formed on the base material 11 using a light-shielding adhesive. The light-shielding adhesive is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include adhesive sheet AD-7006B (manufactured by Risho Kogyo Co., Ltd., average thickness: 0.05 mm).

[0023] As shown in Fig. 2, the reflective optical sensor may have one light-emitting element. As another embodiment, as shown in Fig. 5, the reflective optical sensor may have two or more light-emitting elements arranged adjacent to each other. Either of these embodiments can be suitably implemented. For example, there are an increasing number of applications in which multiple light-emitting elements are used for detection depending on the object to be detected, such as pulse oximeters, and reflective optical sensors in which multiple light-emitting elements and light-receiving elements are mounted in the same package to achieve miniaturization are known.

[0024] As shown in FIG. 5, when the reflective optical sensor has two or more light-emitting elements 12a and 12b, each light-emitting element has a ｅ +d ｒ <t and non-sensing distance d are satisfied. In other words, each of the light-emitting elements 12a, 12b is disposed close to the light-shielding wall 14, and each of the light-emitting elements 12a, 12b is disposed side by side with respect to the light-shielding wall 14, with no other components disposed between them. By satisfying the above configuration, it is possible to reduce the location dependency of the light irradiation characteristics and light reception characteristics of each light-emitting element, and to increase the uniformity of the location-dependent characteristics of light irradiation and light reception on the measurement object between two or more light-emitting elements.

[0025] In a conventional photoreflector having two or more light-emitting elements, for example, the two light-emitting elements (12) are provided in different sections on both sides of the photodiode, resulting in significant differences in the irradiation conditions of light emitted from one light-emitting element and the irradiation conditions of light emitted from the other light-emitting element. This creates a problem of differences in the location-dependent characteristics of light irradiation and light-receiving characteristics of the measurement target between the two light-emitting elements. In other words, depending on the location where the two or more light-emitting elements are arranged on the substrate, the optical characteristics of each light-emitting element relative to the light-receiving element may differ, resulting in sensing different regions of the measurement target (e.g., regions with different blood densities), resulting in poor measurement uniformity between the light-emitting elements.

[0026] Japanese Patent Application Laid-Open Publication No. 2009-038322 also reports a reflective photosensor having two light-emitting elements in the same section. As shown in FIG. 9 , in this reflective photosensor, the light-emitting and light-receiving surfaces of the light-emitting elements (18a, 18b) and the light-receiving element (20) are arranged in a direction perpendicular to the direction of movement (H) of the object to be detected, which moves parallel to the light-emitting and light-receiving surfaces. The light-receiving element (20) receives light reflected from the object to be detected based on the light output from the light-emitting elements (18a, 18b). The light-emitting elements (18a, 18b) are provided with light-emitting regions in which the amount of light emitted is higher at both ends than at the center in the direction of movement (H) of the object to be detected, so that the detection output of the light-receiving element (20) changes linearly depending on the amount of movement of the object to be detected.

[0027] In the reflective photosensor, although two light-emitting elements are provided in one section, they are arranged on either side of a bonding pattern (17c), with the two light-emitting elements spaced apart from each other. Therefore, as with the photoreflector described in Patent Document 1, the direction of light irradiation from one light-emitting element and light reception by the light-receiving element differs from the direction of light irradiation from the other light-emitting element and light reception by the light-receiving element, resulting in a problem of different locations of light irradiation characteristics and light reception characteristics with respect to the measurement object among the multiple light-emitting elements. On the other hand, the reflective photosensor of this embodiment, which has two or more adjacent light-emitting elements, can solve the conventional problem and improve the uniformity of the locations of light irradiation characteristics and light reception characteristics with respect to the measurement object among the two or more light-emitting elements.

[0028] It is preferable that the emission wavelengths of the two or more light-emitting elements are different from each other, thereby making it possible to detect reflected light of two or more wavelengths, for example, two or more wavelengths that are significantly different from each other, and to detect a plurality of pieces of information, detect information based on the difference between the reflected light of different wavelengths, and correct the information.

[0029] The wavelength can be appropriately selected depending on the information to be measured. Specifically, in a pulse oximeter for measuring blood oxygen saturation, red light (for example, wavelength 660 nm) and infrared light (for example, 940 nm) are alternately pulsed, and oxygenated hemoglobin (HbO) is calculated from the difference between the reflected light. ２In addition, the blood glucose meter can measure the blood glucose concentration by correcting the reflected light at the absorption wavelength of glucose (peak absorption wavelength 1,600 nm) with the reflected light at the absorption wavelength of water (1,450 nm).

[0030] As another embodiment, as shown in FIG. 6 , a light-shielding frame 21 is provided on the substrate 11, which, together with the light-shielding wall 14, defines the light-emitting element 12 and the light-receiving element 13, and the interior shape of the compartment defined by the light-shielding wall 14 and the light-shielding frame 21 is a chamfered rectangular column. When the interior shape of the compartment is a chamfered rectangular column, the opening can be made smaller. A smaller opening reduces stray light components of the emitted and received light, thereby reducing noise. Furthermore, when a substrate such as a glass epoxy substrate is used for the light-shielding wall 14 and the light-shielding frame 21, cutting is easy, which is preferable in terms of processing and cost.

[0031] As shown in FIG. 7, the thickness t １ However, it is also possible to suitably implement an embodiment in which the thickness is smaller than the thickness t of the light-shielding wall 14. The embodiment can be easily manufactured by processing such as cutting with a thick dicing blade when separating elements. １ This allows the thickness to be reduced, thereby reducing the package size of the reflective optical sensor 10.

[0032] Example 1 As an example of a reflective optical sensor having two light-emitting elements as shown in FIG. 5 , a pulse oximeter for measuring blood oxygen saturation was fabricated. Specifically, a red LED chip (PR7A, manufactured by Dowa Holdings Co., Ltd.) and an infrared LED chip (FP6E, manufactured by Dowa Holdings Co., Ltd.) were used as the two light-emitting elements emitting red light (wavelength 660 nm) and infrared light (940 nm), and a large-area photodiode (KPD31S, manufactured by Kyoto Semiconductor Co., Ltd.) with a detection wavelength of 400 nm to 1,100 nm was used as the light-receiving element, but with a reduced size and light-receiving area. Furthermore, the pulse oximeter of Example 1 was fabricated using a glass epoxy substrate (black printed wiring board material, CS-3667B, manufactured by Risho Kogyo Co., Ltd.) with a light transmittance of 1% or less as the light-shielding wall and light-shielding frame, and a light-shielding adhesive sheet (AD-7006B, manufactured by Risho Kogyo Co., Ltd.) as the light-shielding adhesive.

[0033] The light-emitting element had dimensions of 0.24 mm x 0.24 mm to 0.28 mm x 0.28 mm and a thickness of 0.15 mm. The light-receiving element had dimensions of 2.0 mm x 0.7 mm, a thickness of 0.3 mm, and a light-receiving area of ​​1.8 mm x 0.5 mm. The light-shielding wall had a thickness t = 0.8 mm and a height of 0.8 mm. The distance d between the light-shielding wall and each element ｅ = d ｒ = 0.2 mm, and d ｅ +d ｒ < t is satisfied. When calculated with a refractive index of 1.5 for the transparent resin and a refractive index of 1.4 for the human body as the measurement target, the non-detectable distance d was approximately 0.24 mm.

[0034] In the pulse oximeter of Example 1, two light-emitting elements are alternately irradiated with pulses, and oxygenated hemoglobin (HbO ２ ) can be detected.

[0035] Example 2 A blood glucose meter for measuring blood glucose concentrations was fabricated as an example of a reflective optical sensor having two light-emitting elements as shown in Figure 5. Specifically, an infrared LED chip used in an infrared LED (KEDE1652H, manufactured by Kyoto Semiconductor Co., Ltd., peak emission wavelength 1,650 nm) was used as one light-emitting element that emits light at the absorption wavelength of glucose (peak absorption wavelength 1,600 nm), an infrared LED chip used in an infrared LED (KEDE1452H, manufactured by Kyoto Semiconductor Co., Ltd., peak emission wavelength 1,450 nm) was used as the other light-emitting element that emits light at the absorption wavelength of water (1,450 nm), and a chip used in a photodiode (KPDE300 InGaAs photodiode, manufactured by Kyoto Semiconductor Co., Ltd.) capable of detecting 80% or more of light in the wavelength range of 1,200 nm to 1,700 nm was used as the light-receiving element. The blood glucose meter of Example 2 was fabricated using a glass epoxy substrate (black printed wiring board material, CS-3667B, manufactured by Risho Kogyo Co., Ltd.) with a light transmittance of 1% or less as the light-shielding wall and light-shielding frame, and a light-shielding adhesive sheet (AD-7006B, manufactured by Risho Kogyo Co., Ltd.) as the light-shielding adhesive.

[0036] The light-emitting element had a size of 0.35 mm x 0.35 mm and a thickness of 0.33 mm. The light-receiving element had a size of 0.44 mm x 0.44 mm and a thickness of 0.15 mm, with a light-receiving area diameter of 0.3 mm. The light-shielding wall had a thickness t of 0.8 mm and a height of 0.8 mm. The distance d between the light-shielding wall and each element ｅ = d ｒ = 0.3 mm, and d ｅ +d ｒ < t is satisfied. When calculated with a refractive index of 1.5 for the transparent resin and a refractive index of 1.4 for the human body as the measurement target, the non-detectable distance d was approximately 0.27 mm.

[0037] In the blood glucose meter of Example 2, the reflected light at the absorption wavelength of glucose (peak absorption wavelength 1,600 nm) is corrected by the reflected light at the absorption wavelength of water (1,450 nm), so that glucose can be detected with high accuracy without being affected by water, and therefore the blood glucose concentration can be measured.

[0038] The reflective optical sensors of Examples 1 and 2 all have a simple structure and do not require the use of molds for resin molding during manufacturing. The angle between the emission angle of light emitted from the light-emitting element and the incidence angle of light received by the light-receiving element can be reduced, thereby reducing the location dependency of the light emission characteristics and light-receiving characteristics. Furthermore, because the non-detection distance d is set in the range of 0.2 mm to 0.3 mm, noise caused by light from the surface of the living body being measured is reduced, while at the same time, a strong signal caused by light from the blood within the living body can be detected.

[0039] This international application claims priority based on Japanese Patent Application No. 2023-098321, filed on June 15, 2023, the entire contents of which are incorporated herein by reference.

[0040] REFERENCE SIGNS LIST 10 Reflective optical sensor 11 Base material 12 Light-emitting element 13 Light-receiving element 14 Light-shielding wall 21 Light-shielding frame 22a, b Conductive wire 23a, b Conductive portion 24 Adhesive layer 25 Transparent resin 26 Adhesive layer A1 Region 1 A2 Region 2

Claims

1. A reflective optical sensor having a substrate, a light emitting element and a light receiving element provided on the substrate, and a light shielding wall provided between the light emitting element and the light receiving element, ｅ and the distance d between the light receiving element and the light shielding wall ｒ The relationship between the thickness t of the light-shielding wall and the thickness t of the light-shielding wall is expressed by the following formula: ｅ +d ｒ <t, and wherein the shortest distance between an area that does not belong to either an area where the light emitted from the light-emitting element does not reach the object to be measured or an area where the reflected light of the light emitted from the object to be measured or the scattered light from the object to be measured is not input to the light-receiving element and between the reflective optical sensor and a sensor surface with which the object to be measured comes into contact is 0.2 mm or more and 0.3 mm or less.

2. The reflective optical sensor according to claim 1, wherein the light-emitting element is two or more light-emitting elements arranged adjacent to each other, and the emission wavelengths of the two or more light-emitting elements are different from each other.

3. A reflective optical sensor as described in claim 1 or 2, further comprising a light-shielding frame on said base material which, together with said light-shielding wall, partitions said light-emitting element and said light-receiving element, and the inner shape of the partition formed by said light-shielding wall and said light-shielding frame is a chamfered rectangular column.

4. The reflective optical sensor according to claim 3, wherein the thickness of said light-shielding frame is smaller than the thickness of said light-shielding wall.

5. A reflective optical sensor as claimed in any one of claims 1 to 5, wherein the base material is a glass epoxy substrate having a light transmittance of 1% or less through the thickness of the base material, the light-shielding wall is a glass epoxy substrate having a light transmittance of 1% or less through the thickness of the light-shielding wall, and the light-shielding wall is attached to the base material via a light-shielding adhesive.

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