Optical sterilization device

Abstract

To provide an optical sterilization device that prevents a decrease in the efficiency of light-based sterilization at a distance from the light source. [Solution] According to the embodiment, the optical sterilization device comprises a first reflector having a mirror surface, a light source positioned opposite the mirror surface of the first reflector, a housing having a fluid intake and outlet and having the first reflector and light source positioned inside, and a heat sink thermally connected to the light source and extending along the direction of fluid flow from the intake to the outlet. The light rays from the light source include wavelengths that inactivate microorganisms in the fluid.

Description

Technical Field

[0001] Embodiments of the present invention relate to an optical sterilization device.

Background Art

[0002] In various fluids such as air and water, it is important to sterilize microorganisms (microorganisms such as filamentous fungi, bacteria, and viruses having pathogenicity or harmfulness) present therein. For example, an optical sterilization device that illuminates ultraviolet light into a fluid using an ultraviolet (UV) light source to sterilize the fluid is known. Generally, the sterilization efficiency increases as the intensity of the ultraviolet light irradiated onto the fluid increases. However, the light from the light source immediately diverges, and the intensity decreases as the distance from the light source increases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

[0005] The problem that this invention aims to solve is to provide an optical sterilization device that prevents a decrease in the sterilization efficiency of light at a position far from the light source. [Means for solving the problem]

[0006] According to one embodiment, the optical sterilization device comprises a first reflector having a mirror surface, a light source positioned opposite the mirror surface of the first reflector, a housing having a fluid intake and outlet and containing the first reflector and light source, and a heat sink thermally connected to the light source and extending along the direction of fluid flow from the intake to the outlet. The light rays from the light source include wavelengths that inactivate microorganisms in the fluid. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic cross-sectional view showing an optical sterilization device according to the first embodiment. [Figure 2] A schematic cross-sectional view showing a part of an optical sterilization device according to Modification 1 of the First Embodiment. [Figure 3] A schematic cross-sectional view showing an optical sterilization device according to a modified example 2 of the first embodiment. [Figure 4] A schematic cross-sectional view showing an optical sterilization device according to the second embodiment. [Figure 5] A schematic cross-sectional view showing an optical sterilization device according to the third embodiment. [Modes for carrying out the invention]

[0008] The embodiments of the present invention will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes of the parts, etc., are not necessarily the same as those of reality. Furthermore, even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In this specification and each drawing, the same reference numerals are used for elements that are the same as those described above with respect to previously shown drawings, and detailed explanations are omitted as appropriate.

[0009] In this specification, light is defined as a type of electromagnetic wave, and includes X-rays, ultraviolet light, visible light, infrared light, microwaves, and the like. In this embodiment, light is defined as ultraviolet light, and for example, its central wavelength is 280 nm. However, light is not limited to this.

[0010] Here, "disinfection" means inactivating (sometimes also called deactivating) viruses and bacteria present in a fluid, and it is also possible to use terms such as "sterilization," "disinfection," and "sterilization" instead of "disinfection." In this embodiment, the term "disinfection" is used, but it can be replaced with "sterilization," "disinfection," and "sterilization."

[0011] (First Embodiment) The optical sterilization device 10 according to the first embodiment will be described below with reference to Figure 1.

[0012] Figure 1 shows a schematic cross-sectional view of the optical sterilization device 10 according to this embodiment. The cross-sectional view shown in Figure 1 is assumed to be on the xz plane, and the z axis coincides with the central axis. The x axis is perpendicular to the z axis and follows the plane of the paper in Figure 1.

[0013] The optical sterilization device 10 according to this embodiment comprises a device body (optical sterilization device body) 12 and a controller 14.

[0014] In this embodiment, the device body 12 comprises a first reflector 22 having a mirror surface 22a, a light source 24, a heat sink 26, and a housing 28 having a fluid intake port (opening) 28a and an exhaust port (opening) 28b.

[0015] The first reflector 22 has a surface 22a that reflects light from the light source 24. The surface 22a of the first reflector 22 may be anything as long as it reduces the divergence angle of the light from the light source 24. The first reflector 22 may be a concave mirror. For example, in FIG. 1, the first reflector 22 is schematically depicted as a single concave mirror, but it may also be configured in combination with a plurality of lenses. Representative examples of the concave mirror 22 include a parabolic mirror, an elliptical mirror, an off-axis parabolic mirror, an off-axis elliptical mirror, etc. In the present embodiment, the first reflector 22 is a parabolic mirror. The parabolic mirror 22 has a focal point f. By disposing the light source 24 near this focal point f and opposing the parabolic mirror 22 and the light source 24, the light from the light source 24 can be converted into parallel light by reflection by the parabolic mirror 22. The light from the light source 24 approaches parallel light by reflection by the mirror surface 22a of the first reflector 22. Therefore, the divergence angle of the light from the light source 24 is reduced.

[0016] Note that the mirror surface 22a of the first reflector 22 is formed concave in the +z-axis direction in FIG. 1. Let the axis passing through the center of the first reflector 22 be the central axis C. Assume that the z-axis coincides with the central axis C.

[0017] The reflector 22 may also be an optical element having imaging performance. This is called an imaging optical element. The imaging optical element 22 has a function of collecting a group of light rays emitted from a single point to a conjugate single point. This is also referred to as imaging or being transferred to a conjugate point. The set surface of the conjugate points to which a group of light rays emitted from a sufficiently distant point is transferred by the imaging optical element 22 is called the focal surface of the imaging optical element 22. Also, the line perpendicular to the focal surface and passing through the center of the imaging optical element 22 is taken as the optical axis C. At this time, the conjugate image point of the object point transferred by this light ray becomes the focal point. The reflector 22 may also be an optical element having no imaging performance. This is called a non-imaging optical element.

[0018] Suppose the reflectivity of the mirror surface 22a of the reflector 22 is, for example, 90% or more. In this embodiment, the reflector 22 is a parabolic mirror, and its reflectivity is assumed to be 90% or more.

[0019] The light-emitting surface of the light source 24 is arranged to face the mirror surface 22a of the first reflector 22. Suppose the light source 24 emits light containing a wavelength that inactivates microorganisms in the fluid toward the mirror surface 22a of the first reflector 22. Here, the light source 24 is assumed to emit ultraviolet light as the light containing a wavelength that inactivates microorganisms in the fluid. Among ultraviolet rays, the UV-C wavelength region is said to have a high effect on inactivating microorganisms. Therefore, in this embodiment, the light source 24 is an LED that emits UV-C. However, it is not limited to this, and any light emitted from the light source 24 may be used as long as it contains a wavelength that inactivates microorganisms in the fluid. The light-emitting area of the light-emitting surface of the LED 24 is, for example, 5 mm × 5 mm.

[0020] The light source 24 emits a group of light rays with a divergence angle. For example, suppose two light rays from the light source 24 include the first light ray B1 and the second light ray B2. At this time, the angle formed by these light rays B1 and B2 is defined as the divergence angle of the two light rays. The divergence angle of the entire group of light rays is the largest among the divergence angles of the two light rays B1 and B2.

[0021] When a point light source is arranged as the light source 24 at the focus f of the parabolic mirror 22, the group of light rays emitted from the point light source 24 is reflected by the parabolic mirror 22 and becomes a group of parallel light rays. At this time, the one that is parallel to this group of parallel light rays and passes through the focus f is defined as the optical axis. Hereinafter, when the light from the light source 24 is reflected by the reflector 22 to form a group of parallel light rays, the one that is parallel to this group of parallel light rays and passes through the center C of the reflector 22 is defined as the optical axis. In this embodiment, the central axis C of the reflector 22 and the optical axis coincide.

[0022] The heat sink 26 is thermally connected to the light source 24. The heat sink 26 is connected, for example, to the region of the light source 24 opposite to the light-emitting surface. The heat sink 26 extends along the flow direction F of the fluid flowing from the intake port 28a to the outlet port 28b of the housing 28. In this embodiment, the heat sink 26 is assumed to be, for example, a solid cylinder of aluminum. However, it is not limited to this, and the heat sink 26 may be a triangular prism, a square prism, or a polygonal prism of any other shape. The heat sink 26 may be made of a material with high thermal conductivity, such as metal, and may have any shape. Alternatively, the heat sink 26 may be a heat pipe with a coolant inside a hollow metal cavity. However, when comparing the maximum dimension of the heat sink 26 along the central axis C with the maximum dimension in a cross-section perpendicular to the central axis C, the maximum dimension along the central axis C is assumed to be larger. In other words, when comparing the maximum dimensions of the heat sink 26 along the fluid flow direction F with the maximum dimensions in a cross-section perpendicular to the fluid flow direction F, the maximum dimension along the fluid flow direction F, i.e., along the central axis C, is assumed to be larger. The heat sink 26 is assumed to be a rotationally symmetric body with a rotational symmetry axis. The rotational symmetry axis of the heat sink 26 is perpendicular to the light-emitting surface of the light source 24.

[0023] In this embodiment, the fluid is air. However, it is not limited to air; any fluid, such as water or a noble gas, may be used. When the device body 12 according to this embodiment is placed in a space where the fluid is not stagnant, that is, in a space where the fluid is moving, the fluid passes through the housing 28 of this embodiment. The fluid enters through the intake port 28a, flows along the fluid flow direction F indicated by the symbol F, and exits through the outlet port 28b. However, the intake port 28a and outlet port 28b of the housing 28 may be reversed. In this case, naturally, the fluid flow direction indicated by the symbol F will also be the opposite direction to that shown in Figure 1. In Figure 1, the position indicated by the symbol 28a is the fluid intake port and the position indicated by the symbol 28b is the fluid outlet port. However, the intake port 28a may be placed closer to the position where the reflector 22 and light source 24 are placed, and the outlet port 28b may be placed further away from the position where the reflector 22 and light source 24 are placed.

[0024] The housing 28 is formed of, for example, a metal material. The housing 28 is formed in a cylindrical shape, having an intake port 28a and an exhaust port 28b for drawing in fluid. Preferably, the housing 28 is formed as a straight pipe. Figure 1 shows an example in which the first reflector 22, the light source 24, and the heat sink 26 are arranged in the space between the intake port 28a and the exhaust port 28b of the housing 28. For example, the first reflector 22 may be positioned outside the space between the intake port 28a and the exhaust port 28b of the housing 28. The light source 24 may also be positioned outside the space between the intake port 28a and the exhaust port 28b of the housing 28, together with the first reflector 22.

[0025] Assume the fluid flows through the housing 28 along the central axis C. The reflectivity of the inner wall of the housing 28 can be anything, but here we assume it is 60%. In other words, the reflectivity of the inner wall of the housing 28 is lower than that of the mirror surface 22a of the reflector 22. Generally, the housing 28 has a larger surface area of ​​its inner wall compared to the mirror surface 22a of the reflector 22, so improving the reflectivity of the housing 28 is costly. Also, the inner wall of the housing 28 often has a large curvature. Therefore, it is difficult to make the reflectivity of the housing 28 higher than that of the mirror surface 22a of the reflector 22. Here, we assume that the shape of the inner wall of the housing 28 is rotationally symmetric with respect to the central axis C. However, it is not limited to this, and the shape of the inner wall of the housing 28 can be anything. For example, the shape of the inner wall of the housing 28 may be translationally symmetric in the direction perpendicular to the plane of the paper in Figure 1.

[0026] When the housing 28 is cylindrical and the reflector 22 is a parabolic mirror, the outer diameter of the reflector 22 is formed to be smaller than the inner diameter of the housing 28. A gap for fluid to pass through is formed between the outer edge of the reflector 22 and the inner wall of the housing 28.

[0027] The controller 14 is electrically connected to the light source 24, for example. The controller 14 supplies power to the light source 24 and is used as a power source to switch the light emission of the light source 24 ON / OFF. The controller 14 can adjust the intensity of the light emitted from the light source 24. The wiring connecting the controller 14 and the light source 24 is provided, for example, along the central axis C. In this case, it is preferable for the wiring to pass through the hollow part (cavity) of the heat sink 26.

[0028] Based on the above configuration, the operation of the optical sterilization device 10 according to this embodiment will be described.

[0029] Microorganisms present in fluids may include pathogenic or harmful filamentous fungi, bacteria, and viruses. These are known to be sterilized by irradiation with ultraviolet (UV) light. Furthermore, the sterilization effect of UV light on fluids increases with higher UV intensity (brightness or illuminance) and longer irradiation times. In other words, higher UV intensity leads to a higher sterilization rate in fluids, and longer irradiation times also lead to a higher sterilization rate in fluids.

[0030] First, consider a general optical sterilization device that does not use a reflector 22 and a heat sink 26, but instead reflects divergent light (ultraviolet light) from a light source (for example, the same as the light source 24 described in this embodiment) multiple times off the inner wall of a housing (for example, the same as the housing 28 described in this embodiment). For example, the light source 24 is placed near the central axis C of the intake port 28a, and light is emitted from the light-emitting surface of the light source 24 along the fluid flow direction F. In this case, since the light emitted from the light source 24 is divergent light, many of the light rays reach the inner wall of the housing 28 once and are reflected. Then, while repeatedly reflecting off the inner wall of the housing 28, the light travels along the central axis C and reaches the vicinity of the outlet 28b of the housing 28. Due to such reflections, the intensity of the light rays is gradually reduced by a power of the reflectance. In other words, near the outlet 28b of the housing 28, the intensity of ultraviolet light is the intensity obtained by raising the reflectance of the inner wall of the housing 28 to the power of the number of reflections. As a result, the intensity of many of the light rays emitted from the light source 24 is greatly attenuated before they are emitted from the exhaust port 28b of the housing 28. However, some of the light from the light source 24 is emitted from the exhaust port 28b of the housing 28 without being reflected by the housing 28.

[0031] On the other hand, when a reflector 22 is provided, as in the main body 12 of the optical sterilization device 10 according to this embodiment, the light from the light source 24 approaches parallel light due to reflection by the mirror surface 22a of the first reflector 22. Therefore, the main body 12 of the optical sterilization device 10 according to this embodiment can reduce the divergence angle of the diverging light from the light source 24. As a result, the number of times each light ray B1, B2 is reflected by the inner wall of the housing 28 can be reduced compared to the case without the reflector 22. In other words, for example, when comparing the light intensity near the light source 24 with the light intensity at the fluid intake port 28a, for example, using a reflector 22 as in the main body 12 of the optical sterilization device 10 according to this embodiment can suppress the attenuation of the light rays B1, B2 compared to the case without the reflector 22. As described above, the sterilization effect of using ultraviolet light on fluids is greater the greater the intensity (luminance or illuminance) of the ultraviolet light. This means that by incorporating a reflector 22 and reflecting the light from the light source 24 off the mirror surface 22a of the reflector 22 to make it closer to parallel light, it is possible to increase the sterilization rate of the fluid flowing inside the housing 28 even at a distance from the light source 24.

[0032] The LED light source 24 generally has a heat resistance temperature of around 100 to 150°C. Therefore, a relatively large heat sink 26 is required to continuously emit light of appropriate intensity from the light-emitting surface of the light source 24. In the main body 12 of the optical sterilization device 10 according to this embodiment, a heat sink 26 thermally connected to the light source 24 is arranged near the light source 24. Generally, the larger the surface area of ​​the heat sink 26 that comes into contact with the fluid, the greater the heat transfer to the fluid. In other words, the larger the surface area of ​​the heat sink 26, the higher its heat dissipation performance. However, if the light source (LED) 24 is placed at or near the focal point f of the reflector 22, and the heat sink thermally connected to the light source 24 is formed to be large in the radial direction perpendicular to the central axis C, although the heat dissipation performance is improved, the heat sink blocks the light reflected back from the light source 24 by the reflector 22. As a result, the sterilization efficiency of microorganisms in the fluid is reduced.

[0033] In this embodiment, the heat sink 26 extends along the fluid flowing from the intake port 28a to the exhaust port 28b of the housing 28. Therefore, the surface of the heat sink 26 is always in contact with the fluid even at a distance from the point connected to the light source 24, and the longer the heat sink 26 is extended, the larger its surface area becomes, resulting in improved heat dissipation performance.

[0034] In the device body 12 according to this embodiment, the longer the housing 28 is extended and the longer the heat sink 26 is extended along the central axis C, the longer the first parallel light ray B1 and the second parallel light ray B2 formed by the reflector 22 will propagate through the fluid inside the housing 28. In other words, the exposure time of light (ultraviolet light) to microorganisms in the fluid inside the housing 28 can be increased. Therefore, the inactivation of microorganisms in the fluid inside the housing 28 can be promoted. In other words, by using the optical sterilization device 10 according to this embodiment, the sterilization efficiency of microorganisms in the fluid inside the housing 28 can be improved. When using the optical sterilization device 10 according to this embodiment, the first light ray B1 and the second light ray B2 are parallel light rays parallel to the central axis C, which has the effect of preventing the light from being attenuated when it reaches the housing 28.

[0035] From the above, the longer the housing 28 is made, the further the heat sink 26 can be extended along the central axis C, improving heat dissipation performance. At the same time, the exposure time of microorganisms in the fluid to light of an appropriate intensity, with attenuation due to reflection from the inner wall of the housing 28 suppressed, can be extended, thereby improving the sterilization efficiency of microorganisms in the fluid.

[0036] On the other hand, if the heat sink is extended in a direction perpendicular to the central axis C, the heat dissipation performance will improve, but the heat sink will block the light rays reflected by the reflector 22. As a result, the efficiency of sterilization of microorganisms in the fluid will be reduced. Furthermore, if the heat sink is extended in a direction perpendicular to the central axis C, the heat sink will easily obstruct the fluid flow. As a result, the heat dissipation performance will be inferior compared to the heat sink 26 which is further extended along the central axis C, as in this embodiment. On the other hand, if the heat sink 26 is further extended along the central axis C while maintaining an appropriate outer diameter of the heat sink 26, as in the heat sink 26 of this embodiment, the heat dissipation performance will be improved because the fluid flow will not be obstructed and the rectification effect of the fluid will be promoted.

[0037] When comparing the maximum dimensions of the heatsink 26 along the central axis C with the maximum dimensions in a cross-section perpendicular to the central axis C, the maximum dimensions along the central axis C are larger. This prevents the reflected light from the reflector 22 from being blocked, and allows for heat dissipation performance to be equal to or better than, compared to the case where the maximum dimensions along the central axis C are smaller than the maximum dimensions in a cross-section perpendicular to the central axis C, when comparing heatsinks 26 with the same surface area. In other words, when comparing the maximum dimensions of the heatsink 26 along the flowing fluid with the maximum dimensions in a cross-section perpendicular to it, the maximum dimensions along the central axis C are larger, thus preventing the reflected light from the reflector 22 from being blocked, and allowing for heat dissipation performance to be equal to or better than,

[0038] Furthermore, the heat sink 26, which is thermally connected to the light source 24, can continuously dissipate the heat generated by the light source 24. As a result, the controller 14 can continuously emit light of appropriate intensity from the light-emitting surface of the light source 24 with appropriate power. Therefore, by using the heat sink 26 according to this embodiment, which is thermally connected to the light source 24 and extends along the fluid flow direction F, it is possible to continuously emit light of appropriate intensity from the light-emitting surface of the light source 24, and to continue to exhibit appropriate sterilization performance even at a distance from the light source 24.

[0039] Furthermore, the optical sterilization device 10 according to this embodiment directs light from the light source 24 near the discharge port 28b to the intake port 28a, for example, by aligning it with the reflector 22 to suppress attenuation within the housing 28. Therefore, by using the optical sterilization device 10 according to this embodiment, appropriate sterilization performance can be maintained even at a distance from the light source 24.

[0040] Furthermore, the method of supplying power to the light source 24 is not limited to using the controller 14 described above. For example, a battery may be placed along the heat sink 26.

[0041] Furthermore, in this embodiment, when the housing 28 is cylindrical, the outer diameter of the reflector 22 is formed to be smaller than the inner diameter of the housing 28, and a gap for fluid to pass through is formed between the outer edge of the reflector 22 and the inner wall of the housing 28. For example, if a plurality of through holes are formed in the mirror surface 22a of the reflector 22, for example along the central axis C, the outer edge of the reflector 22 may be formed to fit into the inner wall of the housing 28. In this case, a gap for fluid to pass through is not required between the outer edge of the reflector 22 and the inner wall of the housing 28.

[0042] Furthermore, multiple sets of reflectors 22, light sources 24, and heat sinks 26 may be arranged in a single housing 28.

[0043] According to this embodiment, an optical sterilization device 10 can be provided that prevents a decrease in the sterilization efficiency of light at a position far from the light source 24.

[0044] (Variation 1) An optical sterilization device 10 according to Modification 1 of the First Embodiment will be described with reference to Figure 2.

[0045] Figure 2 is a schematic cross-sectional view of the heat sink 26 and housing 28 of the optical sterilization device 10 shown in Figure 1, taken by cutting along an xy cross-section perpendicular to the z-axis (central axis C), and looking at the intake port 28a side of the housing 28.

[0046] As shown in Figure 2, the main body 12 of the optical sterilization device 10 is equipped with fins 26a that are thermally connected to the heat sink 26 and the inner wall of the housing 28. The fins 26a are made of a metal such as aluminum. This has the effect of further enhancing heat dissipation performance by conducting heat from the heat sink 26 to the surface of the housing 28 via the fins 26a. For example, it is preferable to use a material with high thermal conductivity, such as aluminum, for the housing 28. The fins 26a may be integrally molded with the heat sink 26.

[0047] Furthermore, if the fins 26a are formed as connecting members that connect the heat sink 26 and the inner wall of the housing 28, the fins 26a can also be expected to have the effect of firmly fixing the heat sink 26 to the inner wall of the housing 28.

[0048] Furthermore, the fins 26a do not necessarily have to be thermally connected to the heatsink 26 and the inner wall of the housing 28. If the fins 26a extend from the heatsink 26 toward the inner wall of the housing 28, heat is conducted from the heatsink 26 to the fins 26a, which has the effect of improving heat dissipation performance compared to when the fins 26a are not present.

[0049] (Modification 2) An optical sterilization device 10 according to a modified example 2 of the first embodiment will be described with reference to Figure 3.

[0050] As the light source 24 shown in Figure 3, one or more LEDs are used that emit light including the UV-A wavelength region in addition to the UV-C wavelength region from the light-emitting surface toward the mirror surface 22a of the first reflector 22.

[0051] A photocatalytic filter 30 is placed in the intake port 28a of the housing 28, for example, by supporting a photocatalytic material on a substrate made of a porous material. The substrate can be, for example, a porous ceramic body. The photocatalytic material can be, for example, titanium dioxide, zinc oxide, tungsten oxide, etc.

[0052] In this case, the light from the light source 24 approaches parallel light due to reflection by the mirror surface 22a of the first reflector 22. Then, UV-C, which suppresses attenuation due to reflection by the inner wall of the housing 28, can be irradiated onto the fluid in the space between the first reflector 22 and the photocatalytic filter 30. Similarly, UV-A, which suppresses attenuation due to reflection by the inner wall of the housing 28, can be irradiated onto the fluid in the space between the first reflector 22 and the photocatalytic filter 30. As a result, reactive oxygen species and OH radicals are generated from the photocatalyst, and organic matter such as microorganisms in the fluid is decomposed into water and carbon dioxide. Note that the light emitted from the light source 24 only needs to include wavelengths that cause chemical reactions such as oxidation-reduction reactions with the substance in contact with the photocatalyst of the photocatalytic filter 30.

[0053] Therefore, even if the distance between the first reflector 22 and the photocatalytic filter 30 is appropriately large, by using UV-A, which suppresses attenuation due to reflection off the inner wall of the housing 28, UV-A can be more reliably irradiated onto the photocatalytic filter 30, and the reaction that decomposes organic matter such as microorganisms in the fluid passing through the photocatalytic filter 30 into water and carbon dioxide can be facilitated. In addition, a large volume (space) for inactivating microorganisms with UV-C can be allocated in the flow direction F along the central axis C. As a result, both the photocatalytic reaction by UV-A irradiation and the inactivation of microorganisms in the fluid by UV-C irradiation can be carried out more efficiently. In other words, without considering the reflection of ultraviolet light from the first reflector 22 to the intake port 28a off the inner wall of the housing 28, an appropriate sterilization rate can be achieved with an appropriately low ultraviolet intensity. As a result, optical sterilization treatment can be performed while suppressing power consumption by the light source 24.

[0054] According to this modified example, an optical sterilization device 10 can be provided that prevents a decrease in the sterilization efficiency of light at a position away from the light source 24.

[0055] (Second Embodiment) The optical sterilization device 10 according to this embodiment will be described below with reference to Figure 4.

[0056] Figure 4 shows a schematic cross-sectional view of the main body 12 of the optical sterilization device 10 according to this embodiment. In this embodiment, the main body 12 comprises a first reflector 22, a light source 24, a heat sink 26, a housing 28, a second reflector 32, and a first fan 34.

[0057] The first reflector 22 in this embodiment is, for example, a parabolic mirror and is formed in the same manner as the first reflector 22 described in the first embodiment. The first reflector 22 has an optical axis C. The optical axis C coincides with the central axis of the first reflector 22.

[0058] The second reflector 32 is provided with, for example, a planar mirror surface 32a facing the mirror surface 22a of the first reflector 22. The planar mirror 32 may be, for example, a metal mirror made of aluminum. Alternatively, the planar mirror 32 may be a heat-conductive dielectric multilayer film or a thin thermally conductive substrate with a reflective coating. The planar mirror 32 is preferably perpendicular to the central axis C.

[0059] The flat mirror 32 of the second reflector 32 is fixed to, for example, the end of the heat sink 26 that is furthest from the light source 24. The flat mirror 32 can be of any shape, but it can be formed from, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0060] The first fan 34 forces the fluid to flow from the intake port 28a to the outlet port 28b. The fan 34 can be anything that moves (flows) the fluid, but here it is assumed to be an axial flow fan with a rotating shaft.

[0061] Based on the above configuration, the operation of the optical sterilization device 10 according to this embodiment will be described.

[0062] The controller 14 drives the first fan 34, forcing the fluid to move from the intake port 28a to the exhaust port 28b of the housing 28. This has the effect of drawing fluid from outside the housing 28 into the housing 28 and disinfecting it. In addition, the controller 14 can adjust the fluid flow rate by electrically controlling the rotation speed of the first fan 34 and the intensity of light by electrically controlling the light source 24, thereby adjusting the disinfection efficiency of microorganisms outside the housing 28.

[0063] The parallel rays of light from the light source 24, reflected by the mirror surface 22a of the first reflector 22, are reflected again by the planar mirror surface 32a of the second reflector 32, and travel at least once back and forth along the same path along the central axis C. This increases the exposure time of microorganisms in the fluid taken into the housing 28 by the first fan 34 compared to the case of light traveling only once. In other words, it has the effect of improving sterilization efficiency.

[0064] Furthermore, the heatsink 26 can be forcibly cooled by the fluid supplied from the first fan 34.

[0065] Therefore, according to this embodiment, it is possible to provide an optical sterilization device 10 that prevents a decrease in the sterilization efficiency of light at a position away from the light source 24.

[0066] (Third embodiment) The optical sterilization device 10 according to this embodiment will be described below with reference to Figure 5.

[0067] Figure 5 shows a schematic cross-sectional view of the optical sterilization device 10 according to this embodiment. The cross-sectional view shown in Figure 5 is assumed to be on the xz plane.

[0068] The main body 12 of the optical sterilization device 10 according to this embodiment includes a first mirror (reflector) 22, a light source 24, a heat sink 26, a housing 28, a second mirror (reflector) 32, a first fan (blower) 34, and a second fan (blower) 36.

[0069] Let the axis passing through the center of the first mirror 22 be the optical axis C. Assume that this cross-sectional view is on the xz plane, and that the z axis coincides with the optical axis C. In this embodiment, assume that the optical axis of the second mirror 32 and the optical axis of the first mirror 22 coincide. However, this is not limited to this, and the optical axes of the two mirrors may be misaligned.

[0070] In this embodiment, the second fan 36 draws in fluid, and the first fan 34 discharges fluid. In other words, unlike the first fan 34 described in the second embodiment, the first fan 34 may discharge fluid, and the second fan 36 may draw in fluid. The first fan 34 and the second fan 36 are, for example, axial flow fans, and their swivel sections are axially symmetric, with their respective axes of symmetry coinciding with the optical axis C. However, this is not limited to this, and the optical axis C may be misaligned with the axes of symmetry of the first fan 34 and the second fan 36. Furthermore, the fans 34 and 36 are not necessarily limited to axial flow fans; any fan that advects fluid, such as a centrifugal fan, may be used.

[0071] The heat sink 26 is positioned to pass through the second mirror 32. That is, the second mirror 32 has a through hole 32b in its center. The second mirror 32 may be a metal mirror made of aluminum, for example. Alternatively, the second mirror 32 may be a heat-conductive dielectric multilayer film or a thin thermally conductive substrate with a reflective coating.

[0072] The first mirror 22 and the second mirror 32 are equipped with reflective surfaces (mirror surfaces) 22a and 32a that reflect ultraviolet light. Both reflective surfaces 22a and 32a have curved surfaces. The curved surfaces may have, for example, a radius of curvature larger than the distance between the two mirrors 22 and 32. By using such a radius of curvature, the light rays B1 and B2 can be made to move back and forth many times between the two mirrors 22 and 32. However, in the main body 12 of the optical sterilization device 10 according to this embodiment, at least two light rays (or beams) B1 and B2 are made to move back and forth simultaneously. This makes it possible to increase the irradiance of the light rays in the xy cross-section within the fluid compared to moving back and forth with only one light ray (or beam).

[0073] On the other hand, a method is known in which the concentration of an absorbent medium in a fluid is determined by moving a single ray (or beam) back and forth and calculating the attenuation rate from the ratio of the light rays' intensity before and after the round trip. In this case, if multiple rays are moved back and forth simultaneously, it becomes difficult to distinguish between the rays, so it is necessary to limit the number of rays (or beams) to one.

[0074] The first mirror 22 is positioned near the axis of symmetry of the rotating part of the second fan 34. However, the positions of the first fan 34 and the second fan 36 may be swapped.

[0075] The inner wall of the housing 28 has a constricted structure 29 near the center between the first fan 34 and the second fan 36. The inner wall of the housing 28 is assumed to be a rotationally symmetric body with a rotational symmetry axis. The rotational symmetry axis of the housing 28 is perpendicular to the light-emitting surface of the light source 24.

[0076] Furthermore, the outer diameter of the first mirror 22 and the outer diameter of the second mirror 32 are formed to be the same as or smaller than the inner diameter of the constricted structure 29 within the housing 28.

[0077] Based on the above configuration, the operation of the optical sterilization device 10 according to this embodiment will be described.

[0078] Let's consider the case where there is no second mirror 32. In this case, light irradiated from the light source 24, reflected by the first mirror 22 and traveling along the optical axis C cannot return to the first mirror 22 side. On the other hand, by providing a curved second mirror 32 as in this embodiment, light reflected by the first mirror 22 and traveling along the optical axis C can be reflected by the reflective surface 32a of the second mirror 32 and travel back to the reflective surface 22a on the first mirror 22 side. Also, light is generally much faster than the speed of fluid. In other words, the fluid can be considered to be almost stationary while the light is traveling inside the housing 28. As a result, the light can pass through the same fluid at least twice: an outward path where it is reflected by the reflective surface 22a and heads towards the reflective surface 32a, and a return path where it is reflected by the reflective surface 32a and heads towards the reflective surface 22a. The reflective surfaces 22a and 32a in this embodiment allow the light rays B1 and B2 to travel back and forth many times between the two mirrors 22 and 32. In other words, the residence time of the light in the same fluid can be increased. In other words, the light irradiation time can be extended. This has the effect of increasing the sterilization efficiency of the optical sterilization device 10 according to this embodiment.

[0079] The first mirror 22 is positioned near the pivot axis of the second fan 36, and the second mirror 32 is positioned near the pivot axis of the first fan 34. When objects are placed in the vicinity of the pivot axes of fans 34 and 36, the closer the distance between the objects and the fans 34 and 36, the less likely it is that the objects will obstruct the advection of fluid by the fans 34 and 36. In other words, it is possible to prevent an increase in pressure loss due to the objects. For example, by positioning the first mirror 22 in the vicinity of the pivot axis of the second fan 36, pressure loss can be prevented. Similarly, by positioning the second mirror 32 in the vicinity of the pivot axis of the first fan 34, pressure loss can be prevented.

[0080] The reflective surfaces 22a and 32a of the first mirror 22 and the second mirror 32 both have curvature. These curvatures have a radius of curvature larger than the distance between the two mirrors 22 and 32. As a result, it is known that light rays that reach the reflective surface 22a of the first mirror 22 from the light source 24 can travel back and forth between the reflective surface 22a of the first mirror 22 and the reflective surface 32a of the second mirror 32 multiple times. In this embodiment, at least two light rays from the light source 24 (the first light ray B1 and the second light ray B2) are simultaneously made to travel back and forth between the first mirror 22 and the second mirror 32 multiple times. This has the effect of increasing the illuminance of the fluid cross-section due to the light emitted from the light source 24 compared to when a single light ray is irradiated in one direction or when it is made to travel back and forth once.

[0081] In this embodiment, fans 34 and 36 are axial flow fans. It is generally known that the flow efficiency of axial flow fans 34 and 36 improves as the diameter of the fan increases. When the flow velocity is kept constant, a larger flow rate means a larger amount of sterilization can be performed per unit time. Therefore, as the diameter of the axial flow fans 34 and 36 increases, a synergistic effect can be expected in which both the flow efficiency and sterilization capacity improve.

[0082] The axial fans 34 and 36 are known to generate swirling flow. This swirling flow increases the time the fluid stays inside the housing 28. As a result, the exposure time to ultraviolet light inside the housing 28 is extended, which improves the sterilization capacity.

[0083] To efficiently generate swirling flow, it is best to align the rotational axis of the axial fans 34 and 36 with the rotational symmetry axis of the heatsink 26. Because the heatsink 26 is rotationally symmetric, it is easier to generate swirling flow compared to a non-symmetrical configuration.

[0084] The inner wall of the housing 28 has a constricted structure 29 near the center between the first fan 34 and the second fan 36. As a result, the fluid passes through the inside of the most constricted structure 29. This has the effect of ensuring that the fluid passes through the beam of light by irradiating it near the inside of the most constricted structure 29 or the inner wall portion of the constricted structure 29. In other words, the amount of fluid that passes through the housing 28 without being irradiated by light can be reduced, and the fluid contained within the housing 28 can be reliably processed by light.

[0085] By arranging the first fan 34 and the second fan 36 at, for example, both ends of the housing 28 and using them for fluid advection, it is possible to flow a large volume of fluid even when the pressure loss within the housing 28 is high.

[0086] The heatsink 26 is positioned near the first fan 34. This allows the first fan 34 to forcibly expel the fluid from inside the housing 28 through the opening indicated by reference numeral 28a, thereby promoting heat dissipation from the heatsink 26 by the fluid advecting from inside to outside the housing 28. This allows for an increase in the power input from the controller 14 to the light source 24, which increases the light intensity and enhances the sterilization capacity of the fluid.

[0087] Therefore, according to this embodiment, it is possible to provide an optical sterilization device 10 that prevents a decrease in the sterilization efficiency of light at a position away from the light source 24.

[0088] (modified version) The propeller surface of the rotating section of the first fan 34 or the second fan 36 may be coated with a reflective coating that reflects ultraviolet light. Alternatively, the propeller of the rotating section of the first fan 34 or the second fan 36 may be made of a material that reflects ultraviolet light. This allows the light that reaches the propeller of the first fan 34 or the second fan 36 to be reflected into the housing 28 and circulate back and forth within the fluid, thereby increasing the residence time of the light within the fluid and enhancing the sterilization ability.

[0089] According to the optical sterilization device 10 of at least one embodiment described above, it is possible to prevent a decrease in the sterilization efficiency of light at a position away from the light source 24.

[0090] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0091] 10...Optical sterilization device, 12...Device body, 14...Controller, 22...Reflector (mirror), 22a...Reflective surface (mirror surface), 24...Light source, 26...Heat sink, 26a...Fin, 28...Housing, 28a...Opening (intake), 28b...Opening (exhaust), 29...Constricted structure, 30...Photocatalytic filter, 32...Reflector (mirror), 32a...Reflective surface (flat mirror surface), 32b...Through hole, 34...First fan, 36...Second fan.

Claims

1. A first reflector having a mirror surface, A light source is positioned so as to face the mirror surface of the first reflector, A housing having a fluid intake port and an exhaust port, with the first reflector and the light source arranged inside, A heat sink is thermally connected to the light source and extends along the flow direction of the fluid flowing from the intake port to the exhaust port. As a preparation, The light rays from the light source include wavelengths that inactivate microorganisms in the fluid. Optical sterilization device.

2. The light source is positioned at or near the focal point of the mirror surface of the first reflector. The optical sterilization device according to claim 1.

3. When comparing the maximum dimension of the heat sink along the fluid flow direction with the maximum dimension in a cross-section perpendicular to the flow direction, the maximum dimension along the flow direction is larger. The optical sterilization device according to claim 1 or claim 2.

4. The housing is provided with a fan located at either the intake port or the exhaust port, or both, which moves the fluid along the direction of fluid flow. The optical sterilization device according to claim 1 or claim 2.

5. The aforementioned light source emits ultraviolet light, The optical sterilization device according to claim 1 or claim 2.

6. The heat sink is assumed to have a rotationally symmetric axis, The rotational symmetry axis of the heat sink is perpendicular to the light-emitting surface of the light source. The optical sterilization device according to claim 1 or claim 2.

7. The housing is equipped with a fan located at either the intake port or the exhaust port, or both, which moves the fluid along the direction of fluid flow. Assuming the aforementioned fan is an axial flow fan, The pivot axis of the axial flow fan coincides with the rotational symmetry axis of the heat sink. The optical sterilization device according to claim 6.

8. A second reflector is provided at a position spaced apart from the first reflector and facing the mirror surface of the first reflector. The light source is positioned between the first reflector and the second reflector. The optical sterilization device according to claim 1 or claim 2.

9. The housing is equipped with a photocatalytic filter located at the intake port, The light source emits light of a wavelength that causes a chemical reaction with the substance in contact with the photocatalyst in the photocatalyst filter. The optical sterilization device according to claim 1 or claim 2.

Images