Ultraviolet light irradiation device

Abstract

To provide an ultraviolet light irradiation device that can effectively emit ultraviolet light and check whether ultraviolet light is emitted from the ultraviolet light irradiation device.SOLUTION: The ultraviolet light irradiation device includes a substrate having a solid-state light source that is arranged on a main surface and emits ultraviolet light including light belonging to a first wavelength band with a wavelength of 190 nm or more and less than 240 nm and light belonging to a second wavelength band with a wavelength of 240 nm or more and 280 nm or less, an enclosure that accommodates the solid-state light source and has a light extraction portion that extracts the ultraviolet light to the outside, a fluorescent body that is arranged in a position where the return light of the ultraviolet light enters and emits visible light when the return light enters, and an optical filter that does not transmit light belonging to the second wavelength band of the ultraviolet light and transmits light belonging to the first wavelength band and the visible light.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ultraviolet light irradiation device.

Background Art

[0002] Conventionally, an ultraviolet light irradiation device that irradiates ultraviolet light for the purpose of sterilization is known. Since ultraviolet light cannot be recognized by the naked eye, it is difficult to confirm whether ultraviolet light is being irradiated from the ultraviolet light irradiation device. Therefore, in Patent Document 1, a phosphor that emits visible light when ultraviolet light is incident is disposed in a partial region of a cover that does not transmit ultraviolet light and constitutes a part of the housing of the ultraviolet light irradiation device, or in a partial region on the substrate where there is no light-emitting element. Thus, a method of confirming that ultraviolet light is being irradiated from the ultraviolet light irradiation device with visible light is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the ultraviolet light irradiation device of Patent Document 1, a part of the ultraviolet light that should originally be irradiated toward the outside of the housing for sterilization must be irradiated toward the position where the phosphor is disposed, resulting in a decrease in the utilization efficiency of the ultraviolet light. Therefore, an object of the present invention is to provide an ultraviolet light irradiation device that can confirm whether ultraviolet light is being irradiated from the device and has high utilization efficiency of ultraviolet light.

Means for Solving the Problems

[0005] The ultraviolet light irradiation device of the present invention includes a solid light source that emits ultraviolet light including light belonging to a first wavelength band having a wavelength of 190 nm or more and less than 240 nm, and light belonging to a second wavelength band having a wavelength of 240 nm or more and 280 nm or less, disposed on a substrate on a main surface, A housing that houses the solid-state light source and has a light extraction part for extracting the ultraviolet light to the outside; A phosphor that is disposed at a position where the return light of the ultraviolet light is incident and emits visible light when the return light is incident; An optical filter that does not transmit the light belonging to the second wavelength band among the ultraviolet light and transmits the light belonging to the first wavelength band and the visible light.

[0006] First, the ultraviolet light emitted by the solid-state light source includes "light belonging to the first wavelength band having a wavelength of 190 nm or more and less than 240 nm, and light belonging to the second wavelength band having a wavelength of 240 nm or more and 280 nm or less". The "light belonging to the first wavelength band having a wavelength of 190 nm or more and less than 240 nm" has the effect of sterilizing the irradiated object (including inactivating viruses; the same applies hereinafter) and has a property of extremely low harmfulness to the human body. On the other hand, the "light belonging to the second wavelength band having a wavelength of 240 nm or more and 280 nm or less" is ultraviolet light for which there is concern about harmfulness to the human body.

[0007] In this specification, the expression "light belonging to a wavelength band" means that this light only needs to emit light at at least some of the wavelengths included in the wavelength band, and does not need to have an emission spectrum over the entire wavelength band. In this specification, the light belonging to the first wavelength band may be referred to as "beneficial light". Hereinafter, the light belonging to the second wavelength band may be referred to as "harmful light".

[0008] The ultraviolet light irradiation device is provided with an optical filter that does not transmit the light belonging to the second wavelength band and transmits the light belonging to the first wavelength band. Thereby, the beneficial light emitted by the solid-state light source reaches the occupied space, and the harmful light emitted by the solid-state light source is reflected by the optical filter so that the harmful light does not reach the occupied space.

[0009] In this specification, the term "occupied space" means a space where people can enter, regardless of whether there are actually people present. Occupied spaces include, for example, spaces inside buildings such as houses, offices, schools, hospitals, or theaters, or spaces inside vehicles such as cars, buses, trains, or airplanes. The occupied space can also be outdoors.

[0010] Providing an ultraviolet light irradiation device corresponds to Goal 3 of the Sustainable Development Goals (SDGs) led by the United Nations, "Ensure healthy lives and promote well-being for all at all ages," and also greatly contributes to Target 3.3, "By 2030, end the epidemics of AIDS, tuberculosis, malaria, and neglected tropical diseases, and combat hepatitis, water-borne diseases, and other infectious diseases."

[0011] In the ultraviolet light irradiation device, there is return light of ultraviolet light that is not extracted from the light extraction part. As a result of intensive research, the inventor conceived of using the return light to cause the phosphor to emit light. The return light is made to enter the phosphor to obtain visible light, and it is confirmed whether the solid light source emits light by this visible light. In this specification, "visible light" is light belonging to the wavelength band of 380 to 780 nm that can be visually recognized by humans.

[0012] Although details will be described later, the "return light" is light that is reflected by the optical filter and returns when the light traveling from the light emission position of the solid light source toward the outside of the housing, or light that is reflected and returns by the incident surface or reflection surface of the transmission optical system for reducing the incident angle of the ultraviolet light and the visible light on the optical filter. Therefore, even if the return light is used to cause the phosphor to emit light, it is difficult to affect the utilization efficiency of the ultraviolet light.

[0013] The optical filter may be disposed at the light extraction part, and a transmission optical system for reducing the incident angle of the ultraviolet light and the visible light on the optical filter may be disposed between the solid light source and the optical filter. Light belonging to the first wavelength band is more likely to pass through the optical filter, and the ultraviolet light irradiation efficiency is improved.

[0014] A plurality of the solid light sources are arranged on the main surface, The transmission optical system includes a lens array in which a plurality of small lenses are arranged, and each of the small lenses may be arranged to face one of the plurality of solid light sources one-to-one.

[0015] The phosphor may be continuously arranged in a region on the main surface excluding the plurality of solid light sources.

[0016] The phosphor may be arranged so as to be in contact with the outer edge of the solid light source.

[0017] Each of the phosphors may have a frame shape surrounding each of the plurality of solid light sources. Thereby, since the outer edge of the region irradiated with ultraviolet light can be strongly illuminated, the visibility of the outer edge can be enhanced. In particular, when the frame shape is such that it is in contact with the outer edge of the solid light source, it becomes easier to determine the individual lighting states of the solid light sources.

[0018] The phosphor may be dispersedly arranged on the main surface so as to face each of the small lenses. Thereby, not only can it be confirmed whether ultraviolet light is irradiated, but also the position where the ultraviolet light is irradiated can be visually recognized with visible light.

[0019] Each of the phosphors may be arranged such that the plurality of solid light sources and the plurality of phosphors are mixed. Thereby, since the entire region irradiated with ultraviolet light can be illuminated with visible light, the visibility of the irradiation region can be enhanced.

[0020] When the plurality of solid light sources and the plurality of phosphors are mixed and arranged, a region composed of a plurality of phosphors may surround a region composed of the plurality of solid light sources. Alternatively, the phosphor and the solid light source may be alternately arranged.

[0021] The phosphor may have an excitation spectrum in which the minimum intensity of the excitation light in the second wavelength band is higher than the minimum intensity of the excitation light in the first wavelength band. The light in the second wavelength band can be effectively used to increase the intensity of the excitation light.

[0022] The phosphor may be a LaPO4:Ce,Tb-based phosphor.

[0023] The phosphor may be composed of two or more kinds of phosphors.

[0024] The solid light source may be an LED.

Advantages of the Invention

[0025] An ultraviolet light irradiation device can be provided that effectively emits ultraviolet light and can confirm whether ultraviolet light is being irradiated from the ultraviolet light irradiation device.

Brief Description of the Drawings

[0026]

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Embodiments for Carrying Out the Invention

[0027] Embodiments of the ultraviolet light irradiation device will be described with reference to the drawings. Note that each drawing except for the graphs is schematically illustrated, the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios do not necessarily match between the drawings.

[0028] In the following, a part of the drawings will be described with reference to the XYZ coordinate system. In this specification, when expressing a direction while distinguishing between positive and negative directions, for example, it is described with positive and negative signs such as “+X direction” and “-X direction”. When expressing a direction without distinguishing between positive and negative directions, for example, it is described without positive and negative signs such as “X direction”. That is, in this specification, when simply described as “X direction”, both “+X direction” and “-X direction” are included. The same applies to the Y direction and the Z direction. In the embodiments described below, the direction in which the light ray on the optical axis of the light emitted from the ultraviolet light irradiation device travels is represented as the “+Z direction”.

[0029] <First Embodiment> [Ultraviolet Light Irradiation Device] Referring to FIG. 1, a first embodiment of an ultraviolet light irradiation device will be described. FIG. 1 is a cross-sectional view taken along the XZ plane of the ultraviolet light irradiation device 10. The ultraviolet light irradiation device 10 includes a substrate 2 on which at least one solid light source 1 is disposed, a frame 3 surrounding the substrate 2, a phosphor 5, and an optical filter 7 that transmits the beneficial light emitted by the solid light source 1 and blocks the transmission of the harmful light emitted by the solid light source 1.

[0030] In this embodiment, the emission surface of the solid light source 1 and the main surface of the substrate 2 on which the solid light source 1 is disposed are arranged parallel to the XY plane. And the substrate 2, together with the frame 3, constitutes a housing 4 that houses the solid light source 1. That is, the substrate 2 functions as a part of the housing 4. As a modification, the ultraviolet light irradiation device may separately include a substrate 2 that does not function as the housing 4.

[0031] The light extraction unit 6 that extracts the light emitted by the solid light source 1 to the outside of the housing 4 is a region where the housing 4 opens to the outside. The optical filter 7 is disposed in the light extraction unit 6. The light flux F1 (a collection of light rays having a radiation intensity of 1 / 2 or more of the radiation intensity of the light ray showing the maximum radiation intensity among the light rays emitted from each solid light source 1) that passes through the optical filter 7 is emitted in the D1 direction along the +Z direction to sterilize the manned space.

[0032] The statement that "the optical filter 7 is disposed in the light extraction unit 6" means that the optical filter 7 is disposed so as to block the light extraction unit 6 (the region where the housing 4 opens) so that the light extracted from the light extraction unit 6 passes through the optical filter 7. In this specification, the interior surrounded by the housing 4 composed of the substrate 2 and the frame 3 and the optical filter 7 may be referred to as the interior of the housing 4. Note that the arrangement location of the optical filter 7 is not limited to the above-described position. For example, the optical filter 7 may be arranged so as to be incorporated into the solid light source 1, or the optical filter 7 may be arranged so as to be in contact with the solid light source 1.

[0033] The optical filter 7 has a function of not transmitting but reflecting (or absorbing part of) the light belonging to the second wavelength band with a wavelength of 240 nm or more and 280 nm or less. The optical filter 7 may not transmit the entire second wavelength band and reflect (or absorb part of it).

[0034] The optical filter 7 is composed of a dielectric multilayer film in which dielectric films with different refractive indices are alternately laminated on a substrate serving as a base material. The light belonging to a specific wavelength band does not penetrate the dielectric multilayer film and is reflected by the dielectric multilayer film. As the dielectric multilayer film, for example, there are those in which HfO2 layers and SiO2 layers are alternately laminated, and those in which SiO2 layers and Al2O3 layers are alternately laminated. The dielectric multilayer film layer in which HfO2 layers and SiO2 layers are alternately laminated can have fewer layers to obtain the same wavelength selection characteristics than the dielectric multilayer film layer in which SiO2 layers and Al2O3 layers are alternately laminated. Therefore, the transmittance of the selected ultraviolet light can be increased. The base material is preferably a material that is transparent to ultraviolet light and visible light, such as quartz glass.

[0035] FIG. 2 is a diagram showing the substrate 2 with the solid light sources 1 arranged on the main surface. As shown in FIG. 2, a plurality of solid light sources 1 are arranged at regular intervals in the X direction and the Y direction on the main surface on the +Z side of the substrate 2. Although FIG. 2 shows 9 solid light sources 1, the solid light source 1 may have 10 or more solid light sources 1, may have less than 9, and preferably has at least one. The solid light source 1 emits light in the +Z direction.

[0036] The solid light source 1 emits light belonging to the first wavelength band with a wavelength of 190 nm or more and less than 240 nm and light belonging to the second wavelength band with a wavelength of 240 nm or more and 280 nm or less. The solid light source 1 may be, for example, an LED having an emission wavelength spectrum with a maximum intensity emission wavelength of 235 nm, or an LED having another emission wavelength spectrum. Also, instead of an LED, other solid light sources, such as an LD or an organic EL, may be used. In this specification, the term "solid light source" includes LEDs, LDs, and organic ELs and does not include incandescent bulbs and lamps (for example, mercury lamps or excimer lamps).

[0037] [Phosphor Arrangement] The phosphor 5 (the hatched area in Fig. 2) is a kind of wavelength conversion element that is excited by ultraviolet light emitted from the solid light source 1 and emits visible light. The specific material of the phosphor 5 will be described later. The phosphor 5 is continuously arranged in the area of the main surface of the substrate 2 where the solid light source 1 is arranged, excluding the solid light source 1. The continuously arranged state means a state in which a plurality of phosphors 5 are connected to each other to form one phosphor. In addition, the state in which the phosphor 5 is dispersed, as shown in other embodiments described later, means a state in which a plurality of phosphors 5 are not connected to each other. Further, in the embodiments shown in Figs. 1 and 2, the phosphor 5 is arranged so as to be in contact with the outer edge of the solid light source 1 on the main surface of the substrate 2 where the solid light source 1 is arranged, but the phosphor 5 may be arranged so as to be away from the outer edge of the solid light source 1.

[0038] In this embodiment, the phosphor 5 is laminated in a thin film form over the entire area excluding the solid light source 1. Such a thin film phosphor 5 may be formed, for example, by screen printing a paste containing the phosphor 5 on the substrate 2, or by applying and firing a slurry containing the phosphor 5.

[0039] The light emitted from the solid light source 1 is in the +Z direction. The phosphor 5 is arranged in the area of the substrate 2 excluding the solid light source 1, and is arranged at a position where the light emitted from the solid light source 1 is not easily directly incident on the phosphor 5. There may be a gap between the solid light source 1 and the phosphor 5, or a light shielding member may be arranged between the solid light source 1 and the phosphor 5. The fact that the light from the solid light source 1 is not directly incident on the phosphor 5 means that the light emitted from the solid light source 1 can be irradiated toward the occupied space without being consumed by the phosphor 5. Therefore, the utilization efficiency of ultraviolet light is not easily reduced.

[0040] Figure 3 is an enlarged view of the E1 region in Figure 1. With reference to Figure 3, the return light of the light emitted by the solid-state light source 1 will be described. The light ray L0 represents an example of the light ray of the harmful light belonging to the second wavelength band emitted by the solid-state light source 1. The light ray L0 is reflected by the optical filter 7 and becomes the return light heading towards the phosphor 5. Although details will be described later, the harmful light is reflected by the optical filter 7 and becomes the return light heading towards the phosphor 5 regardless of the incident angle with respect to the optical filter 7.

[0041] Both the light ray L1 and the light ray L2 represent an example of the light ray of the beneficial light belonging to the first wavelength band emitted by the solid-state light source 1. The incident angles (θ1, θ2) are represented by the angles formed between the light rays (L1, L2) incident on the optical filter and the normal line 7N to the incident surface of the optical filter 7. The light ray L1 is a low-angle light ray with a small incident angle with respect to the optical filter 7, while the light ray L2 is a high-angle light ray with a large incident angle with respect to the optical filter 7. That is, the incident angle θ2 is larger than the incident angle θ1. The transmittance of the beneficial light passing through the optical filter 7 depends on the angle of the incident angle. In Figure 3, the light ray L1, which is a low-angle light ray, passes through the optical filter 7, while the light ray L2, which is a high-angle light ray, is reflected without passing through the optical filter 7 and becomes the return light heading towards the phosphor 5.

[0042] Figure 4 is a graph showing an example of the transmittance spectrum of the optical filter 7 for each incident angle when ultraviolet light is incident on the optical filter 7. From the transmittance below 240 nm in Figure 4, it can be seen that even for light rays of the same wavelength, the transmittance decreases as the incident angle θ (deg) increases.

[0043] In summary, in this embodiment, the harmful light belonging to the second wavelength band and the beneficial light of the high-angle component with a large incident angle θ with respect to the optical filter 7 belonging to the first wavelength band become the return light from the optical filter 7 towards the phosphor 5. When the return light is incident on the phosphor 5, the phosphor 5 is excited and emits visible light. Note that the optical filter 7 has a high transmittance for visible light, and even when the incident angle of the visible light ray with respect to the optical filter 7 increases, it is less likely to become the return light. Therefore, the optical filter 7 is less likely to limit the visible light emitted from the phosphor 5.

[0044] [Luminescence confirmation using a phosphor] FIG. 5 is a diagram showing the light distribution curves of ultraviolet light (useful light) and visible light emitted from the ultraviolet light irradiation device 10. In FIG. 5, the light distribution curve of the ultraviolet light is labeled UV, and the light distribution curve of the visible light is labeled VIS. The line connecting 0 degrees and 180 degrees is a line parallel to the emission surface of the optical filter 7 in the ultraviolet light irradiation device 10. The line extending in the 90-degree direction from the ultraviolet light irradiation device 10 overlaps with the normal line to the emission surface of the optical filter 7 and is a line along the optical axis of the emitted light. The ultraviolet light (useful light) has a higher ratio of light components with a small incident angle. Therefore, the light distribution of the ultraviolet light emitted from the optical filter 7, UV, has a small light distribution angle and becomes light having directivity in the optical axis direction.

[0045] The visible light VIS has a small incident angle dependence of the transmittance in the optical filter 7. Therefore, the visible light VIS has a light distribution close to a circle following Lambert's cosine law, and the directivity of the visible light VIS is small.

[0046] From this, the light distribution curve VIS of the visible light becomes wider than the light distribution curve UV of the ultraviolet light. As shown in FIG. 5, specifically, the light distribution angle at which the radiation intensity becomes half the peak intensity is around 53 degrees for the light distribution curve VIS of the visible light, while it is around 17 degrees for the light distribution curve UV of the ultraviolet light. The light distribution curve VIS of the visible light has a wider light distribution angle than the light distribution curve UV of the ultraviolet light. Then, by recognizing whether visible light is emitted without entering the irradiated area of the ultraviolet light, it is possible to know whether ultraviolet light is emitted. Thereby, the operation confirmation of the ultraviolet light irradiation device can be easily performed. In addition, the visible light emitted from the phosphor 5 can be used as normal illumination light.

[0047] [Phosphor material] In this embodiment, as the phosphor 5, a LaPO4:Ce,Tb-based (LAP) phosphor is used. When ultraviolet light is incident on LAP, green light is emitted.

[0048] FIG. 6 shows the excitation spectrum of the phosphor 5 of this embodiment. The higher the relative intensity, the more light at that wavelength is absorbed and converted into visible light. Looking at FIG. 6, it can be seen that the minimum value P1 of the relative intensity of the excitation light in the second wavelength band WB2 with a wavelength of 240 nm or more and 280 nm or less is higher than the minimum value P2 of the relative intensity of the excitation light in the first wavelength band WB1 with a wavelength of 190 nm or more and less than 240 nm. This is one of the indicators showing that the phosphor is one in which the luminous efficiency by harmful light is higher than the luminous efficiency of beneficial light. Since the return light from the optical filter 7 contains a lot of harmful light, if the phosphor 5 that easily emits light with respect to harmful light is used, more visible light can be emitted from the return light. Note that the excitation spectrum shown in FIG. 6 is an example of LAP, and the excitation spectrum varies depending on the component ratio of Ce or Tb constituting the phosphor 5, etc.

[0049] The phosphor 5 is not limited to LAP. Phosphors of other colors (for example, blue phosphors of BaMgAl 10 O 17 :Eu or red phosphors of (Y,Gd)BO3:Eu) may be used, or two or more kinds of phosphors may be used. For example, a phosphor for PDP that mixes three wavelengths of green, red, and blue may be used, or a phosphor used for a white fluorescent lamp for illumination such as calcium halophosphate may be used.

[0050] [Modification Example] A modification example of the first embodiment will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view along the XZ plane of the ultraviolet light irradiation device 20. Note that, except for the matters described below, the description will focus on the parts different from the above-described ultraviolet light irradiation device 10, and the matters not described are the same as the configuration of the above-described ultraviolet light irradiation device 10. Similarly, for other embodiments and their modification examples described later, the description will focus on the different parts.

[0051] In the ultraviolet light irradiation device 20, the phosphor 5 is provided not only on the substrate 2 but also on the inner wall surface of the frame body 3 and the inner side surface of the optical filter 7. The inner wall surface of the frame body 3 and the inner side surface of the optical filter 7 where the phosphor 5 is disposed are located outside the light beam F2. The light beam F2 represents a collection of light rays having a radiation intensity of 1 / 2 or more of the light ray showing the maximum radiation intensity among the light rays emitted from each solid light source 1. The light emitted from the solid light source 1 hardly directly enters the phosphor 5 located outside the light beam F2. However, the return light reflected by the optical filter 7 enters the phosphor 5 disposed on the inner wall surface of the frame body 3 and the inner side surface of the optical filter 7. By increasing the formation region of the phosphor 5 in this way, stronger visible light can be emitted from the phosphor 5.

[0052] <Second Embodiment> Referring to FIG. 8, a second embodiment of the ultraviolet light irradiation device will be described. FIG. 8 is a cross-sectional view taken along the XZ plane of the ultraviolet light irradiation device 30. In the ultraviolet light irradiation device 30, an optical filter 7 is disposed in the light extraction portion 6, and a transmission optical system for reducing the incident angle of ultraviolet light and visible light on the optical filter 7 is disposed between the solid light source 1 and the optical filter 7. The transmission optical system is composed of at least one optical lens. In the present embodiment, as the transmission optical system, one lens array 15 in which a plurality of small lenses are arranged is used, but it may not be a lens array, and a plurality of lenses may be used.

[0053] Each of the plurality of small lenses constituting the lens array 15 is disposed opposite to each of the plurality of solid light sources 1 one-to-one. Each small lens can reduce the incident angle of the light rays incident on the optical filter 7 by deflecting the light beam F2 from each solid light source 1 so as to approach parallel light. As a result, useful light easily passes through the optical filter 7, and the ultraviolet light irradiation efficiency is improved. Further, in the present embodiment, a part of the ultraviolet light emitted from the solid light source 1 is reflected not only by the optical filter 7 but also by the incident surface or the exit surface of the lens array 15. Therefore, the ultraviolet light reflected by the incident surface or the exit surface of the lens array 15 becomes return light for causing the phosphor 5 to emit light.

[0054] <Third Embodiment> Referring to FIG. 9, a third embodiment of the ultraviolet light irradiation device will be described. FIG. 9 is a cross-sectional view of the ultraviolet light irradiation device 40 along the XZ plane. In the ultraviolet light irradiation device 40, an optical filter 7 is disposed in the light extraction unit 6, and between the solid light source 1 and the optical filter 7, similar to the second embodiment, an array of a plurality of small lenses, that is, one lens array 15 is disposed.

[0055] FIG. 10 is a diagram showing a substrate 22 having the solid light source 1 disposed on the main surface and used in the ultraviolet light irradiation device 40. A plurality of solid light sources 1 are arranged in the X direction and the Y direction on the main surface on the +Z side of the substrate 22. The phosphors 5 (hatched areas in FIG. 10) are dispersedly arranged, and each of the dispersedly arranged phosphors 5 has a frame shape surrounding each solid light source 1. The visible light emitted by the phosphor 5 having the frame shape is refracted by each small lens constituting the lens array 15 and is made to approach parallel light, similar to the ultraviolet light emitted from each solid light source 1.

[0056] In particular, in FIGS. 9 and 10, the phosphor 5 is arranged so as to be in contact with the outer edge of the solid light source 1 on the main surface of the substrate 2 where the solid light source 1 is disposed. Thereby, it becomes easy to discriminate the individual lighting states of the respective solid light sources.

[0057] Referring to FIG. 11, the effects of the ultraviolet light irradiation device 40 having the substrate 22 will be described. FIG. 11 is a diagram showing the relative light intensity distribution of the ultraviolet light (useful light) UV and the visible light VIS of the ultraviolet light irradiation device on an irradiated surface 200 mm away from the optical filter 7 in the +Z direction. The horizontal axis represents the distance from the optical axis position (position 0 mm) of the emitted light. The vertical axis is the relative value of the light intensity when the maximum light intensity is 1. This relative light intensity distribution is obtained by simulation.

[0058] Looking at FIG. 11, the relative intensity of the ultraviolet light UV decreases as it goes from +20 mm to +50 mm, and also decreases as it goes from -20 mm to -50 mm. The irradiated region of the ultraviolet light UV where the relative light intensity becomes 0.5 or more is -35 mm to +35 mm.

[0059] On the other hand, the visible light VIS emitted by the phosphor 5 having a frame shape surrounding the solid light source 1 has a high light intensity of the visible light VIS between +30 mm and +50 mm, and between -30 mm and -50 mm, which is near the outer edge of the irradiated region of the ultraviolet light UV. Then, the visible light VIS is irradiated onto the irradiated surface so as to form the outer edge of the irradiated region of the ultraviolet light UV. Thereby, the irradiated position of the ultraviolet light can be visually recognized using the visible light VIS. That is, in the present embodiment, by using visible light, not only can it be confirmed whether ultraviolet light is emitted, but also the irradiated position of ultraviolet light that cannot be visually recognized by the naked eye can be visually recognized. In particular, since the vicinity of the outer edge of the irradiated region, which is the boundary between the region irradiated with ultraviolet light and the region not irradiated, is strongly illuminated, the visibility of the outer edge of the irradiated region is high.

[0060] [Modification Example] A modification example of the third embodiment will be described. In this modification example, the substrate 32 (see FIG. 12) is used. The configuration of the ultraviolet light irradiation device 40 excluding the substrate 32 is the same as that of the third embodiment.

[0061] As shown in FIG. 12, on the substrate 32, the phosphors 5 (hatched regions in FIG. 12) are dispersedly arranged. The phosphor 5 has a shape and size similar to those of the solid light source 1. Then, a plurality of solid light sources 1 and a plurality of phosphors 5 are mixed and arranged on the substrate 32. A region 5a composed of a plurality of phosphors 5 surrounds a region 1a composed of a plurality of solid light sources 1.

[0062] FIG. 13 is a diagram showing the relative light intensity distribution of ultraviolet light (useful light) UV and visible light VIS of the ultraviolet light irradiation device 40 using the substrate 32 on the irradiated surface 200 mm away from the optical filter 7 in the +Z direction. The horizontal axis represents the distance from the optical axis position (position 0 mm) of the emitted light. The vertical axis is the relative value of the light intensity when the maximum light intensity is 1. This relative light intensity distribution is obtained by simulation.

[0063] In FIG. 13, the irradiated area of visible light VIS substantially coincides with the irradiated area of ultraviolet light UV. That is, when the substrate 32 is used, the area where visible light VIS can be visually recognized can be said to be the irradiated area of ultraviolet light UV. That is, also in this modified example, by using visible light, not only can it be confirmed whether ultraviolet light is emitted, but also the irradiated position of ultraviolet light that cannot be visually recognized with the naked eye can be visually recognized with visible light. Since the irradiation area of visible light substantially overlaps with the irradiation area of ultraviolet light, a person can intuitively understand the irradiation area of ultraviolet light.

[0064] The relative light intensity distribution in FIG. 13 is not only obtained with the substrate 32 shown in FIG. 12, but can also be obtained, for example, by using a substrate 42 in which the phosphors 5 and the solid light sources 1 are alternately arranged as shown in FIG. 14.

[0065] The above described each embodiment and its modified example of the ultraviolet light irradiation device have been explained. The present invention is not limited to the above described embodiments at all, and within the scope not departing from the gist of the present invention, the above described embodiments or modified examples can be combined, or various changes or improvements can be made to the above described embodiments. For example, the lens array 15 (transmission optical system) may be removed from the ultraviolet light irradiation device 40 of the third embodiment or the modified example of the third embodiment.

[0066] In addition, although an example using a solid light source has been described as the ultraviolet light irradiation device, a phosphor may also be arranged in an ultraviolet light irradiation device using a light source that is not a solid light source (for example, a mercury lamp or an excimer lamp). That is, for an ultraviolet light irradiation device in which the light source is not specified, a light source that emits ultraviolet light including light belonging to a first wavelength band of 190 nm or more and less than 240 nm and light belonging to a second wavelength band of 240 nm or more and 280 nm or less, a housing that houses the light source and has a light extraction portion for extracting the ultraviolet light to the outside, a phosphor that is arranged at a position where the return light of the ultraviolet light is incident and emits visible light when the return light is incident, and an optical filter that does not transmit the light belonging to the second wavelength band among the ultraviolet light and transmits the light belonging to the first wavelength band and the visible light, may be provided.

[0067] In the configuration of the ultraviolet light irradiation device of the previous paragraph, it is desirable that the phosphor be disposed at a position where the ultraviolet light emitted from the light source does not directly enter and the return light enters. As described above, the "return light" is the light that is reflected by the optical filter and returns when the light traveling from the light emitting position of the light source toward the outside of the housing, or the light that is reflected and returns by the incident surface or the reflection surface of the transmission optical system for reducing the incident angle on the optical filter. In particular, it is desirable to dispose the phosphor at a position where the harmful light reflected by the optical filter enters as the "return light". Further, the configuration of the ultraviolet light irradiation device using the solid light source described above can also be applied to an ultraviolet light irradiation device using a light source that is not a solid light source.

[0068] In Fig. 15, an ultraviolet light irradiation device 50 using an excimer lamp 11 is shown. The ultraviolet light irradiation device 50 includes a cylindrical excimer lamp 11 extending in the Y direction (for example, a KrCl excimer lamp having a main emission peak wavelength of 222 nm), a housing 4, an electrode block 19, a phosphor 5, an optical filter 7, and a diffusion plate 13 for diffusing ultraviolet light. The electrode block 19 functions not only as an electrode of the excimer lamp 11 but also as a mirror that reflects a part of the ultraviolet light emitted from the excimer lamp 11. The phosphor 5 is disposed on the surface of a position where the electrode block 19 is not used as a mirror (that is, a position where the light from the excimer lamp 11 does not directly enter). Return light from the optical filter 7 enters the phosphor 5. Note that a transmission optical system may be disposed in the ultraviolet light irradiation device 50. In that case, for example, a small lens can be used as the transmission optical system, and a cylindrical type lens array can be used.

Explanation of Reference Numerals

[0069] 1: Solid light source 2, 22, 32, 42: Substrate 3: Frame 4: Housing 5: Phosphor 6: Light extraction part 7: Optical filter 10, 20, 30, 40, 50: Ultraviolet light irradiation device 11: Excimer lamp 13: Diffusion plate 15: Lens array 19: Electrode block

Claims

1. A solid-state light source that emits ultraviolet light including light belonging to a first wavelength band with a wavelength of 190 nm or more and less than 240 nm, and light belonging to a second wavelength band with a wavelength of 240 nm or more and 280 nm or less, a substrate disposed on a main surface, a housing that houses the solid-state light source and has a light extraction unit that extracts the ultraviolet light to the outside, a phosphor disposed at a position where the return light of the ultraviolet light is incident and emits visible light when the return light is incident, an optical filter that does not transmit light belonging to the second wavelength band among the ultraviolet light and transmits light belonging to the first wavelength band and the visible light, characterized in that it comprises an ultraviolet light irradiation device.

2. The optical filter is disposed in the light extraction unit, and a transmission optical system that reduces an incident angle at which the ultraviolet light and the visible light are incident on the optical filter is disposed between the solid-state light source and the optical filter. The ultraviolet light irradiation device according to claim 1, characterized by the above.

3. A plurality of the solid-state light sources are arranged on the main surface, The transmission optical system includes a lens array in which a plurality of small lenses are arranged, and each of the small lenses is disposed opposite to each of the plurality of solid-state light sources one-to-one. The ultraviolet light irradiation device according to claim 2, characterized by the above.

4. The phosphor is continuously disposed in a region on the main surface excluding the plurality of solid-state light sources. The ultraviolet light irradiation device according to claim 3, characterized by the above.

5. The phosphor is disposed on an outer edge of the solid-state light source. The ultraviolet light irradiation device according to claim 1, characterized by the above.

6. Each of the phosphors has a frame shape surrounding each of the plurality of solid-state light sources. The ultraviolet light irradiation device according to claim 5, characterized by the above.

7. The phosphor is dispersedly disposed on the main surface so as to face each of the small lenses. The ultraviolet light irradiation device according to claim 3, characterized by the above.

8. Each of the phosphors is arranged such that the plurality of solid-state light sources and the plurality of phosphors are mixed. The ultraviolet light irradiation device according to claim 7, characterized by the above.

9. A region composed of a plurality of phosphors surrounds a region composed of the plurality of solid-state light sources. The ultraviolet light irradiation device according to claim 8, characterized by the above.

10. The phosphor and the solid-state light source are alternately arranged. The ultraviolet light irradiation device according to claim 8, characterized by the above.

11. The ultraviolet light irradiation device according to any one of claims 1 to 10, wherein the phosphor has an excitation spectrum in which the minimum intensity of the excitation light in the second wavelength band is higher than the minimum intensity of the excitation light in the first wavelength band.

12. The phosphor is a LaPO ４ :Ce, Tb-based phosphor, and the ultraviolet light irradiation device according to any one of claims 1 to 10, characterized in that it is such a phosphor.

13. The ultraviolet light irradiation device according to any one of claims 1 to 10, wherein the phosphor is composed of two or more kinds of phosphors.

14. The ultraviolet light irradiation device according to any one of claims 1 to 10, wherein the solid light source is an LED.

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