Optical system device

Abstract

The purpose of the present invention is to provide an optical system device that is more compact than existing optical system devices.　This optical system device 100 comprises: a light radiation means 1 that is capable of radiating light; and a first light detection means 2 that detects information regarding light received by a light receiving surface 21, wherein the light radiation means 1 and the first light detection means 2 are arranged along the optical axis of the light radiated by the light radiation means 1 such that the light from the light radiation means 1 is not directly radiated onto the light receiving surface 21. The light radiation means 1 may be arranged at the rear surface side of the first light detection means 2. Furthermore, there may be a waveguide 3 which causes the light from the light radiation means 1 to be incident on an incidence part 31 and to be emitted from an emission part 32.

Description

Optical system device

[0001] The present invention relates to an optical system device.

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

[0003] In recent years, due to the increasing health consciousness, wristwatches and smartwatch-type health management devices equipped with a function of being wearable on the body and simply measuring the 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 with the progress of technology.

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

[0005] Here, since an optical system device such as a pulse sensor is mounted on a wristwatch or a smartwatch, 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.

[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, and the light irradiation means and the first light detection means are arranged on the optical axis of the light irradiated by the light irradiation means so that the light of the light irradiation means is not directly irradiated on the light receiving surface. The first light detection means is arranged on the optical axis of the light irradiated by the light irradiation means and in a direction in which the light receiving surface does not face the light irradiation means. An optical system device characterized by this.

[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 waveguide that causes light to be incident at the incident part and emitted at the exit part. The waveguide may also 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 sides of the light irradiation means and the back sides of the first light detection means can also be arranged facing each other.

[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 waveguide may be configured such that reflected light from the light irradiation means is incident at an incident section, and the reflected light is emitted at an output section formed to irradiate the light-receiving surface of the first light detection means.

[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 waveguide. 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.

[0014] In this case, it is preferable that at least one set of the optical system devices be arranged so that their light-receiving surfaces face each other.

[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 waveguide related to the optical system of the present invention. This is a schematic cross-sectional view showing another waveguide 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 waveguide 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 arranged on a ring.

[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 on the light receiving surface 21. The light irradiation means 1 and the first light detection means 2 are arranged on the optical axis (perpendicular line) of the light irradiated by the light irradiation means 1, so that the light from the light irradiation means 1 does not directly irradiate the light receiving surface 21. Arrangement of the light irradiation means 1 and the first light detection means 2 on the optical axis means that in a plan view taken from the direction of the optical axis, at least a part of the light irradiation means 1 and the first light detection means 2 overlap. In addition, 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 in the plan view.

[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 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 blood glucose levels, the light emitted by the light irradiation means 1 should be mid-infrared light (electromagnetic waves with a wavelength of 2.5 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 positioned 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 waveguide 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 waveguide 3 becomes important when the light irradiation means 1 is smaller than the first light detection means 2. Here, the waveguide 3 is a light transmission path made using a material with optical properties. The waveguide 3 is 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. Furthermore, when the waveguide 3 is present, 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] Waveguide 3 can be any known type, provided it is formed to allow light emitted by the light irradiation means 1 to propagate through total internal reflection. Waveguide 3 is transparent to light emitted by the light irradiation means 1 and is formed from a material with a higher refractive index than the surrounding material.

[0024] Furthermore, the waveguide 3 has an inlet 31 for injecting light into the waveguide and an outlet 31 for emitting light from within the waveguide. The inlet 31 can be anything as long as it can inject light from the light irradiation means 1 into the waveguide 3, but for example, it is formed in contact with the surface of the light-emitting part of the light irradiation means 1. The inlet 31 can be anything as long as it can inject light into the waveguide 3, but for example, a grating pattern for injecting light into the waveguide 3 can be formed on the surface of the waveguide 3. The grating pattern can be formed directly on the material of the waveguide 3, or a resin formed as a grating pattern may be placed on the surface of the material of the waveguide 3. The grating pattern can be any shape as long as it can inject light into the waveguide 3, 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 incident from the outside into the waveguide 3.

[0025] The emission section 32 is the part that emits light that has passed through the waveguide 3. Preferably, 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 inside the waveguide 3, but for example, a grating pattern can be formed on the surface of the waveguide 3 to emit light from inside the waveguide 3. The grating pattern can be formed directly on the material of the waveguide 3, or a resin formed as a grating pattern can be placed on the surface of the material of the waveguide 3. The grating pattern can be any shape as long as it can emit light from the waveguide 3, but for example, it can be a line-and-space pattern with periodically arranged inclined protrusions that can diffract light so that it is emitted from inside the waveguide 3 to the outside. The emission section 32 can emit light in any direction as long as it can irradiate the object with light, for example, it can be formed to emit light in a direction perpendicular to the light-receiving surface 21.

[0026] Waveguide 3 may be formed, for example, by a first waveguide 36 and a second waveguide 37, as shown in Figure 2(a). The first waveguide 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 waveguide 37 is formed to extend from the end of the first waveguide 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 waveguide 36 and the light-emitting side of the light irradiation means 1. The exit portion is formed at the end of the second waveguide 37 on the light-receiving surface side. Furthermore, the connection point 38 between the first waveguide 36 and the second waveguide 37 may be vertical, as shown in Figure 2(a), but it 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] Waveguide 3 can be made of any material as long as it can receive light from the light irradiation means 1 at the incident section 31 and emit the light at the exit section formed in a position where the light is not directly irradiated to the first light detection means 2. For example, resins such as polydimethylsiloxane (PDMS) or glass can be used. Waveguide 3 can be manufactured in any way, for example, by conventionally known methods such as imprint printing or injection molding.

[0029] In the above description, we explained a waveguide in which the light emitted by the light irradiation means 1 is propagated by total internal reflection. However, the invention is not limited to this, and it is also possible to use specular reflection using, for example, metal.

[0030] Furthermore, when the light irradiation means 1 is positioned on the light-receiving surface 21 side of the first light detection means 2, the optical system 100 of the present invention preferably has a waveguide 4, as shown in Figure 5, which causes the reflected light from the light irradiation means 1 to be incident at an incident section 41 and to be emitted at an output section 42 that is formed so as to irradiate the light-receiving surface 21 of the first light detection means 2. The waveguide 4 is particularly important when the first light detection means 2 is smaller than the light irradiation means 1. Here, the waveguide 4 is a light transmission path made using a material with optical properties. The waveguide 4 is formed to guide the reflected light, which is reflected when the light from the light irradiation means 1 strikes an object, to the light-receiving surface 21 of the first light detection means 2, which is positioned on the back surface 12 side of the light irradiation means 1. Note that when the waveguide 4 is present, it is also possible to arrange the devices so that the back surface 12 of the light irradiation means 1 and the back surface 22 of the first light detection means 2 face each other, as shown in Figure 5(b).

[0031] Waveguide 4 can be any known type, provided it is formed to allow the reflected light from the light irradiation means 1 to propagate through total internal reflection. Waveguide 4 is transparent to the reflected light from the light irradiation means 1 and is formed of a material with a higher refractive index than the surrounding material.

[0032] Furthermore, the waveguide 4 has an inlet section 41 for injecting light into the waveguide and an outlet section 42 for emitting light from within the waveguide. The inlet section 41 can be anything as long as it can inject reflected light from the light irradiation means 1 into the waveguide 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 anything as long as it can inject light into the waveguide 4, but for example, a grating pattern for injecting light into the waveguide 4 can be formed on the surface of the waveguide 4. The grating pattern may be formed directly on the material of the waveguide 4, or a resin formed as a grating pattern may be arranged on the surface of the material of the waveguide 4. The grating pattern can be any shape as long as it can inject light into the waveguide 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 incident from the outside into the waveguide 4.

[0033] The emission section 42 is the part that emits light that has passed through the waveguide 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 inside the waveguide 4, but for example, a grating pattern can be formed on the surface of the waveguide 4 to emit light from inside the waveguide 4. The grating pattern can be formed directly on the material of the waveguide 41, or a resin formed as a grating pattern can be placed on the surface of the material of the waveguide 41. The grating pattern can be any shape as long as it can emit light from the waveguide 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 emitted from inside the waveguide 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 waveguide 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 waveguide 32. Furthermore, the optical element 5 may be formed integrally with the light irradiation means 1, as shown in Figures 6(a) and (b), or as a separate component 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 waveguide 3, as shown in Figure 7(a), or it may be formed separately from the output portion 32 of the waveguide 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 its first and second surfaces that performs an optical function. The functional surface can be any type of surface 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 waveguide 3, as shown in Figure 6(a), the light from the light irradiation means 1 can be efficiently incident into the waveguide. The optical element 5 may also be a surface that creates a dot pattern from the light emitted from the exit part 32 of the waveguide 3. Furthermore, the optical element 5 may be used to focus the light emitted from the emission section 32 of the waveguide 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, LEDs or the like that can selectively irradiate light of different wavelengths can be used. Here, the light sources 10A to 10C can be arranged in parallel along the waveguide 3, as shown in Figure 8(a). Also, the light sources 10A to 10C can be arranged in multiple stages across the waveguide 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 waveguide 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 waveguide 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 waveguide 3. In this case, for example, an emission section 33 can be formed in a part of the first waveguide 36 of the waveguide 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 waveguide 37 of the waveguide 3 and to place the second light detection means 7 on the side of the second waveguide 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] 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.

[0042] The optical systems 100 can be arranged in any way; for example, as shown in Figure 10(b), three optical systems 100a to 100c can be arranged at 120-degree intervals. However, it is preferable that at least one pair of optical systems 100 be arranged so that their light-receiving surfaces face each other. For example, Figure 10(a) shows an example where two pairs of optical systems 100a and 100b are arranged facing each other on the ring 9. Also, Figure 10(c) shows an example where two pairs of optical systems 100a and 100c, and optical systems 100b and 100d are arranged facing each other on the ring 9. Such a ring 9 can be used to measure objects such as blood flow and blood glucose levels by inserting a human finger or arm into the hole 91 in the center of the ring.

[0043] 1 Light irradiation means 2 First light detection means 3 Waveguide 4 Waveguide 5 Optical element 7 Second light detection means 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 waveguide 37 Second waveguide 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 irradiation means and the first light detection means are arranged on the optical axis of the light irradiated by the light irradiation means, 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 waveguide 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 waveguide irradiates light from the emission section in a direction such that the elevation angle with respect to the light-receiving surface is less than 90 degrees.

5. 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.

6. 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.

7. The optical system according to claim 6, further comprising a waveguide that causes reflected light from the light irradiation means to be incident at an incident section and the reflected light to be emitted at an output section formed to irradiate the light-receiving surface of the first light detection means.

8. The optical system according to any one of claims 1 to 7, further comprising an optical element that controls the light from the light irradiation means to perform an optical function.

9. The optical system according to claim 8, characterized in that the optical element is arranged on the emission side of the waveguide.

10. The optical system according to claim 8, characterized in that the optical element is a diffuser that diffuses light.

11. The optical system according to claim 8, characterized in that the optical element is one that transforms light into a dot pattern.

12. The optical system according to claim 8, characterized in that the optical element focuses light to a predetermined position.

13. The optical system according to any one of claims 1 to 7, characterized in that the light irradiation means is capable of selectively irradiating light of different wavelengths.

14. The optical system according to any one of claims 1 to 7, further comprising a second light detection means for detecting light information from the light irradiation means.

15. An optical system comprising a plurality of optical systems according to any one of claims 1 to 7, wherein at least the light-receiving surface of each optical system is positioned to receive light irradiated from the light-irradiating means of the other optical systems.

16. The optical system according to claim 16, characterized in that at least one set of the optical system according to any one of claims 1 to 7 is arranged so that its light-receiving surfaces face each other.

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