Inactivation device, optical filter

Abstract

To provide an inactivation device that, while maintaining or improving intensity of UV-rays in a wavelength band small in influence on a human body among emitted UV-rays, suppresses more than ever intensity of UV-rays of a wavelength band influencing on a human body.SOLUTION: An inactivation device comprises an ultraviolet light source emitting ultraviolet light in which at least part of a main emission wavelength band is contained in the range of 200 nm or more and 230 nm or less, and an optical filter that is formed by a dielectric multilayer film and has, relating ultraviolet light incident at an incident angle of 0 degree, a band that transmits ultraviolet light in a range of a wavelength of 190 nm or more and 235 nm or less, and a wavelength λ5 showing 5% of transmittance is 236 nm or more and less than 245 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bacterial or viral inactivation device, particularly to a bacterial or viral inactivation device that uses ultraviolet light, and also to an optical filter employed in a bacterial or viral inactivation device that uses ultraviolet light. [Background technology]

[0002] Conventionally, a technique for inactivating bacteria and viruses by irradiating them with ultraviolet light has been known, and because DNA exhibits the highest absorption characteristics around a wavelength of 260 nm, ultraviolet light with a wavelength of around 254 nm, emitted from a light source such as a low-pressure mercury lamp, is often used. The method of inactivating bacteria and viruses with ultraviolet light has the advantage that sterilization can be performed simply by irradiating the target space or object with ultraviolet light, without the need to spray chemicals or other substances.

[0003] It is known that ultraviolet light exists in wavelength bands that pose a high risk of affecting the human body and wavelength bands that pose a low risk of affecting the human body. Therefore, in recent years, methods and devices have been developed for inactivating bacteria and viruses present in space using ultraviolet light in wavelength bands that pose a low risk of affecting the human body. For example, Patent Document 1 listed below describes a sterilization device (inactivation device) that uses ultraviolet light with a wavelength of 190 nm to 230 nm, which has an extremely low risk of affecting the human body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6025756 [Non-patent literature]

[0005] [Non-Patent Document 1] Sachiko Kaidzu et al. “Re-Evaluation of Rat Corneal Damage by Short-Wavelength UV Revealed Extremely Less Hazardous Property of Far-UV-C†” Photochemistry and Photobiology, 2021, 97: 505-516 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide an improved inactivation device by increasing the intensity of ultraviolet light in wavelength bands that have little effect on the human body, while suppressing an increase in the intensity of ultraviolet light in wavelength bands that have an effect on the human body. [Means for solving the problem]

[0007] The inactivation device of the present invention comprises: an ultraviolet light source that emits ultraviolet light having at least a portion of a main emission wavelength band within the range of 200 nm to 230 nm; and an optical filter formed of a dielectric multilayer film, which has a band that transmits ultraviolet light having a wavelength in the range of 190 nm or more and 235 nm or less with respect to ultraviolet light that is incident on the main surface of the light-transmitting window at an incident angle of 0 degrees, and which has a wavelength λ5 at which it shows a transmittance of 5% that is 236 nm or more and less than 245 nm.

[0008] In this specification, "inactivation" refers to a comprehensive concept of killing or eliminating the infectivity and toxicity of bacteria or viruses, and "microorganisms" refers to microorganisms such as bacteria and fungi (mold). Hereinafter, "microorganisms or viruses" may be collectively referred to as "microorganisms, etc."

[0009] In this specification, the term "main emission wavelength band" refers to a wavelength band that exhibits a light intensity of 10% or more of the peak intensity in the intensity spectrum of light emitted from the light source. Note that the peak wavelength of the ultraviolet light source is preferably in the range of 190 nm to 235 nm, and more preferably in the range of 210 nm to 235 nm.

[0010] In recent years, research and verification into the effects of ultraviolet light on the human body have progressed, and it has been confirmed that ultraviolet light is easily absorbed by the surface layer of the skin and the corneal epithelium, and that the shorter the wavelength, the greater the safety. In particular, it has been confirmed that ultraviolet light with a wavelength of less than 240 nm poses little risk of affecting the human body. It has also been confirmed that ultraviolet light with a wavelength of 230 nm or less poses an extremely low risk of affecting the human body. For example, the above-mentioned Non-Patent Document 1 reports the results of an investigation into the generation of CPD (Cyclobutane Pyrimidine Dimers), which is DNA damage induced by ultraviolet light irradiation and is a cause of cancer.

[0011] According to the above-mentioned non-patent document 1, when ultraviolet light with wavelengths of 207 nm and 222 nm is irradiated onto the cornea of ​​an organism, it penetrates only up to the top layer of the corneal epithelium, and therefore generates CPD only in the top layer of the corneal epithelium. However, the CPD generated in the top layer of the corneal epithelium usually peels off from the cornea within 24 hours as part of the physiological turnover cycle, and therefore hardly remains on the cornea.

[0012] Many reports have been published in recent years on the effects of ultraviolet light (particularly ultraviolet light with wavelengths of 200 nm to 230 nm) on the human body. Inactivation devices that use ultraviolet light in wavelengths that have little effect on the human body have recently been attracting particular attention due to the recent outbreak of coronavirus infections.

[0013] Furthermore, the inactivation device described above uses ultraviolet light in a wavelength band that has an extremely small effect on the human body, and is expected to be effective in suppressing contact infection through the surface of an object and infection through aerosols present in the air. Therefore, it is being considered for installation in spaces where people frequently pass through or where people work for long periods of time.

[0014] However, although ultraviolet light with a wavelength of 190 nm to 230 nm has an extremely small effect on the human body compared to ultraviolet light emitted from a low-pressure mercury lamp, a regulatory limit has been set for the cumulative dose of irradiation to the human body for safety reasons. At the time of filing the present application, it is recommended that the cumulative dose of ultraviolet light irradiated to the human body be within the regulatory limit (allowable limit) set by the American Conference of Governmental Industrial Hygienists (ACGIH). For example, for ultraviolet light with a wavelength of 222 nm, the allowable limit for the cumulative dose of irradiation per day (8 hours) is 22 mJ / cm. 2 It should be noted that the numerical values ​​of the permissible limit values ​​in this specification are current numerical values ​​and may be subject to change in the future. Furthermore, in addition to the above, it is desirable to set a predetermined upper limit for the cumulative irradiation amount of ultraviolet light irradiated onto the human body in order to ensure safe operation.

[0015] Therefore, inactivation devices that are expected to irradiate ultraviolet light into spaces where people pass through are required to be able to efficiently inactivate the target space and objects while complying with the above-mentioned regulatory values ​​for the cumulative irradiation amount of ultraviolet light.

[0016] The above-mentioned Non-Patent Document 1 reports the results of verification of the cumulative irradiation dose threshold at which corneal damage occurs due to ultraviolet light with a wavelength of 207 nm and ultraviolet light with a wavelength of 222 nm. The above-mentioned Non-Patent Document 1 also reports that the cumulative irradiation dose threshold at which corneal damage due to ultraviolet light irradiation was confirmed was 10,000 mJ / cm for ultraviolet light with a wavelength of 207 nm. 2 ~15,000mJ / cm 2 , and 3,500 mJ / cm for ultraviolet light with a wavelength of 222 nm. 2~5,000mJ / cm 2 The results reported that the cumulative exposure dose of ultraviolet light in specific wavelength bands is significantly higher than the current regulatory limits set by the ACGIH. As numerous verification results like this have been published, it is anticipated that the regulatory limits for the cumulative exposure dose of ultraviolet light in specific wavelength bands will be revised.

[0017] Once the regulatory limits on cumulative irradiation dose are relaxed, it is expected that inactivation devices that use ultraviolet light will be used in ways such as irradiating ultraviolet light at higher intensities or being constantly turned on in spaces where people are passing through in order to more efficiently inactivate target spaces or objects.

[0018] However, if the light output of the ultraviolet light source is simply increased in order to increase the irradiance of ultraviolet light, the intensity of ultraviolet light in wavelength bands that affect the human body will increase, raising concerns about a greater risk of health damage when the ultraviolet light is irradiated onto the human body. In other words, as mentioned above, in order to respond to future relaxation of the regulatory value for the cumulative irradiation amount, an inactivation device using ultraviolet light will be required to be able to increase only the intensity of ultraviolet light in wavelength bands that have little effect on the human body, without increasing the intensity of ultraviolet light in wavelength bands that affect the human body.

[0019] Furthermore, if the inactivation device is left on at all times in a space where people pass through, the ultraviolet light emitted from the device may be irradiated onto people for a longer period of time, which may increase the cumulative exposure to ultraviolet light in wavelength bands that have a significant effect on the human body, raising concerns about the risk of health damage.

[0020] Based on the above, it is predicted that in the future, there will be a need to improve the intensity of ultraviolet light in wavelength bands that have little effect on the human body among the ultraviolet light emitted from inactivation devices, more than at present, and to suppress the increase in the intensity of ultraviolet light in wavelength bands that have an effect on the human body.

[0021] Next, even if the peak wavelength of ultraviolet light emitted from an ultraviolet light source belongs to a wavelength band that has little effect on the human body, the emission spectrum has a tail, and therefore the light may inevitably contain components in wavelength bands that have an effect on the human body. For this reason, inactivation devices that use ultraviolet light, such as the sterilization device (inactivation device) described in Patent Document 1, are usually equipped with an optical filter to block ultraviolet light in wavelength bands that have an effect on the human body.

[0022] In view of conventional design concepts, optical filters are designed to have a sufficiently high transmittance for the wavelength band that is desired to be transmitted, and a sufficiently low transmittance for the wavelength band that is desired to be blocked.

[0023] Incidentally, in a wavelength band near the boundary between a wavelength band to be transmitted and a wavelength band to be blocked, the wavelength at which the transmittance is 5% is sometimes referred to as the "wavelength λ5" or simply "λ5" (hereinafter referred to as "wavelength λ5"). The "wavelength λ5" or "λ5" is sometimes used as an index when considering the characteristic parameters of a light-transmitting member such as glass, or an optical filter that blocks light in a predetermined wavelength band. In this specification, unless otherwise specified, the term "wavelength λ5" corresponds to a wavelength determined based on the spectrum of ultraviolet light incident at an angle of incidence of 0 degrees on the main surface of a light-transmitting window on which the optical filter is formed.

[0024] As an optical filter that transmits ultraviolet light in a predetermined wavelength band, for example, an optical filter made of a dielectric multilayer film is known. An optical filter formed of a dielectric multilayer film has the characteristic that the wavelength band of ultraviolet light that is blocked (conversely, the wavelength band of ultraviolet light that is transmitted) can be adjusted by changing the film thickness of each layer.

[0025] Furthermore, optical filters formed by dielectric multilayer films have angle dependency, and therefore have the characteristic that the peak value of transmittance and the transmitted wavelength band vary depending on the incident angle of ultraviolet light, as will be described later with reference to Figs. 6 and 8.

[0026] Therefore, the present inventors decided to reconsider the configuration of the inactivation device using ultraviolet light, taking into consideration the incident angle characteristics of the optical filter.

[0027] First, the inventors conducted a verification to confirm how the incident angle characteristics of the optical filter contribute to the ratio (defined as the "harmful light ratio") between the integrated value of the intensity of ultraviolet light in the wavelength band of 200 nm or more and 230 nm or less, which has very little effect on the human body, and the integrated value of the intensity of ultraviolet light in the wavelength band of 235 nm or more and 320 nm or less, which includes the wavelength band that may have an effect on the human body, under specified conditions. Details of this verification will be described later in the section "Mode for carrying out the invention."

[0028] According to the results of the above verification, the ultraviolet light emitted by the inactivation device equipped with an optical filter designed to set the wavelength λ5 to 240 nm has a lower harmful light ratio than the ultraviolet light emitted by the inactivation device equipped with an optical filter designed to set the wavelength λ5 to 235 nm. This is presumably because the angular components of the radiant flux of ultraviolet light generated in the ultraviolet light source and incident on the optical filter are mainly angular components greater than 0 degrees.

[0029] Furthermore, based on the above verification results, the inventors have considered the harmful light ratio for each incident angle. The harmful light ratio for each incident angle using an optical filter designed to have a wavelength λ5 of 240 nm is 5% or less within the incident angle range of 0 degrees to 50 degrees. In other words, it has been confirmed that an optical filter designed to have a wavelength λ5 of 240 nm is particularly effective in suppressing the harmful light ratio for light with an incident angle within this angle range.

[0030] An optical filter designed to have a wavelength λ5 of 236 nm or more and less than 245 nm has a coefficient of reflection of 30% or less within the incident angle range of 0 to 50 degrees. The characteristics of the optical filters described here will be described later in the section "Mode for Carrying Out the Invention" with reference to FIG. 10.

[0031] In other words, from the viewpoint of easily transmitting safe ultraviolet light without worsening the harmful light ratio of ultraviolet light, it is preferable to use an optical filter formed of a dielectric multilayer film so that the wavelength λ5 is 236 nm or more and less than 245 nm, as described above. Furthermore, it is preferable that the light intensity of the radiant flux in the relative intensity distribution of the incident ultraviolet light is such that the intensity of ultraviolet light outside the range of incident angles of 10 degrees or more and 50 degrees or less is lower than the intensity of ultraviolet light within this range of incident angles. In other words, it is preferable that the intensity peak in the relative intensity distribution is included in the range of incident angles of 10 degrees or more and 50 degrees or less.

[0032] Therefore, in the inactivation device, In the relative intensity distribution for each angular component of the radiant flux of ultraviolet light generated in the ultraviolet light source and incident on the optical filter, it is preferable that the angle showing the peak value be within a range of 10 degrees or more and 50 degrees or less.

[0033] 10, the optical filter made of a dielectric multilayer film suppresses the harmful light ratio to 5% or less within the incident angle range of 10 degrees to 45 degrees, and suppresses the harmful light ratio to 3% or less within the incident angle range of 20 degrees to 40 degrees. Therefore, the incident angle at which the relative intensity distribution shows a peak is more preferably within the range of 10 degrees to 45 degrees, and particularly preferably within the range of 20 degrees to 40 degrees.

[0034] As a result, by adopting the above configuration, an inactivation device is realized that improves the intensity of ultraviolet light in wavelength bands that have little effect on the human body, while suppressing the increase in the intensity of ultraviolet light in wavelength bands that have an effect on the human body more than before.

[0035] The target product of the inactivation device of this invention does not cause erythema or keratitis on the skin or eyes of humans or animals, and can provide the sterilization and virus inactivation capabilities inherent to ultraviolet light. In particular, unlike conventional low-pressure mercury lamps, it can be used in manned environments, and by installing it in manned environments indoors or outdoors, it can irradiate the entire environment, suppressing and sterilizing viruses in the air and on the surfaces of materials installed in the environment.

[0036] This corresponds to Goal 3 of the United Nations Sustainable Development Goals (SDGs), "Ensure healthy lives and promote well-being for all at all ages," and will significantly contribute 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 communicable diseases."

[0037] The inactivation device comprises: The optical filter may be provided on a main surface of the light-transmitting window. The optical filter may be provided on the main surface of the light-transmitting window.

[0038] In addition, in the inactivation device, The optical filter may be configured so that the wavelength λ5 is within the range of 238 nm or more and less than 243 nm.

[0039] In addition, in the inactivation device, The optical filter may be made of a material that absorbs ultraviolet light with a wavelength of 200 nm or less.

[0040] In addition, in the inactivation device, The ultraviolet light source may be an excimer lamp in which a gas containing krypton (Kr) and chlorine (Cl) is sealed in a light emitting tube as a light emitting gas.

[0041] An excimer lamp, in which a gas containing krypton (Kr) and chlorine (Cl) is sealed inside the arc tube as the light-emitting gas, is a light source that emits ultraviolet light with a peak wavelength of 222 nm and a main emission wavelength band falling within the range of 200 nm to 230 nm (see Figure 6 described below).

[0042] The optical filter of the present invention comprises: an optical filter made of a dielectric multilayer film formed on the light-transmitting window of the inactivation device, The optical element is characterized in that it has a band that transmits ultraviolet light having a wavelength in the range of 190 nm or more and 235 nm or less, with respect to ultraviolet light that is incident on the main surface of the light-transmitting window at an incident angle of 0 degrees, and the wavelength λ5 at which it shows a transmittance of 5% is 236 nm or more and less than 245 nm. [Effects of the Invention]

[0043] According to the present invention, an improved inactivation device is realized by increasing the intensity of ultraviolet light in a wavelength band that has little effect on the human body, while suppressing the increase in the intensity of ultraviolet light in a wavelength band that has an effect on the human body. [Brief explanation of the drawings]

[0044] [Figure 1] 1 is a diagram schematically illustrating the appearance of an embodiment of an inactivation device. [Figure 2] 2 is a view of the inactivation device of FIG. 1 as seen from the +Z side. [Figure 3] 1 is a graph showing an example of the spectrum of ultraviolet light generated by an ultraviolet light source. [Figure 4] FIG. 2 is a cross-sectional view of the inactivation device of FIG. 1 as viewed in the X direction. [Figure 5] FIG. 5 is an enlarged view of the periphery of the ultraviolet light source in FIG. [Figure 6] 10 is a graph showing transmittance characteristics of an optical filter according to an embodiment for each angle θ of incidence of ultraviolet light with respect to a light-transmitting window. [Figure 7A] 10 is a diagram schematically showing a method for acquiring the relative intensity distribution of ultraviolet light incident on an optical filter formed on a plane. [Figure 7B] 7B is a diagram of the ultraviolet light source shown in FIG. 7A as viewed from the light emission direction. [Figure 7C] 10 is a diagram schematically illustrating a method for acquiring the relative intensity distribution of ultraviolet light incident on an optical filter formed on a curved surface. [Figure 7D] 10 is a graph showing the relative intensity distribution over the entire range from 0 degrees to 90 degrees with respect to the radiant flux Vθi for each angle θi of the ultraviolet light source, taking into account the solid angle. [Figure 8] 1 is a graph showing the transmittance characteristics of the optical filter included in the inactivation device of Comparative Example 1 for each incident angle θ of ultraviolet light with respect to the main surface of the light-transmitting window. [Figure 9] This graph is obtained by adding up the ultraviolet light emitted from the light-transmitting windows of the inactivation devices of Example 1 and Comparative Example 1, taking into account the solid angle of the emitted ultraviolet light, based on the relative intensity distribution of the radiant flux incident on the optical filter, and taking into account the integrated amount for each angle component. [Figure 10] 10 is a graph showing a harmful light ratio for each incident angle θ in an optical filter. [Figure 11] 1 is a diagram illustrating the travel of light emitted from a point light source in the form of a uniform luminous flux in all directions. [Figure 12] FIG. 10 is an enlarged view of the periphery of an ultraviolet light source in another embodiment of the inactivation device. [Figure 13] 10 is a diagram schematically illustrating an example of an implementation of another embodiment of an inactivation device. [Figure 14] FIG. 14 is an enlarged view of the inactivation device of FIG. 13. [Figure 15] 10 is a diagram schematically illustrating the configuration of an ultraviolet light source in another embodiment of the inactivation device. DETAILED DESCRIPTION OF THE INVENTION

[0045] Fig. 1 is a diagram schematically illustrating the appearance of one embodiment of an inactivation device 1, and Fig. 2 is a diagram illustrating the inactivation device 1 of Fig. 1 as viewed from the +Z side. As shown in Fig. 2, the inactivation device 1 of this embodiment includes a housing 10 and an ultraviolet light source 30 housed inside the housing 10.

[0046] In the following description, as shown in FIG. 2, the direction in which a plurality of arc tubes 30a (described later) provided in the ultraviolet light source 30 are arranged is referred to as the X direction, the direction in which the arc tubes 30a extend is referred to as the Y direction, and the direction perpendicular to the X direction and the Y direction is referred to as the Z direction.

[0047] Furthermore, when expressing a direction, if a distinction is made between positive and negative directions, the direction is written with a positive or negative sign, such as "+Z direction" or "-Z direction," and when a direction is expressed without distinguishing between positive and negative directions, it is simply written as "Z direction." In the inactivation device 1 shown in Figures 1 and 2, the direction from which ultraviolet light is extracted corresponds to the "+Z direction."

[0048] As shown in FIGS. 1 and 2, the housing 10 includes a light-transmitting window 20 for extracting the ultraviolet light emitted from the ultraviolet light source 30 to the outside of the housing 10.

[0049] The ultraviolet light source 30 of this embodiment is an excimer lamp including a plurality of arc tubes 30a and a pair of electrodes 30b, as shown in Fig. 2. The plurality of arc tubes 30a are placed on the pair of electrodes 30b, as shown in Fig. 4, which will be described later.

[0050] Fig. 3 is a graph showing an example of the spectrum of ultraviolet light Lx generated by ultraviolet light source 30. In the ultraviolet light source 30 of this embodiment, krypton (Kr) and chlorine (Cl) are sealed in the arc tube 30a as a light emitting gas G1, and when a voltage is applied between the electrodes (30b, 30b), ultraviolet light Lx having a peak wavelength of 222 nm is emitted as shown in Fig. 3. Furthermore, as shown in Fig. 3, the ultraviolet light emitted from the ultraviolet light source 30 exhibits a spectrum with a main emission wavelength band of 216 nm or more and 223 nm or less.

[0051] The ultraviolet light source 30 can be a light source that emits ultraviolet light in a wavelength band that has little effect on the human body and is effective in inactivation treatment, so it is preferable that the peak wavelength of the emitted ultraviolet light be within the range of 210 nm or more and 235 nm or less, and more preferably within the range of 215 nm or more and 230 nm or less.

[0052] Fig. 4 is a cross-sectional view of the inactivation device 1 of Fig. 1 when viewed in the X direction, and Fig. 5 is an enlarged view of the periphery of the ultraviolet light source 30 in Fig. 4. The light-transmitting window 20 is a light exit window for extracting the ultraviolet light emitted from the ultraviolet light source 30 to the outside of the housing 10. The light-transmitting window 20 of this embodiment has an optical filter 20b made of a dielectric multilayer film formed on a main surface 20a.

[0053] In the inactivation device 1, ultraviolet light exhibiting a spectrum as shown in Fig. 3 passes through an optical filter 20b, which will be described later with reference to Figs. 4 and 5, and is then extracted to the outside through the light-transmitting window 20. In Fig. 4, the ultraviolet light generated by the ultraviolet light source 30 is represented as "ultraviolet light Lx," and the ultraviolet light that passes through the light-transmitting window 20 and is extracted to the outside of the inactivation device 1 is represented as "ultraviolet light L1," thereby distinguishing between the two. Similar expressions will be used hereinafter as appropriate.

[0054] The light-transmitting window 20 is made of a material that can transmit ultraviolet light in the wavelength band of 190 nm or more and 235 nm or less. Specific materials that can be used for the light-transmitting window 20 include, for example, ceramic materials such as quartz glass, borosilicate glass, sapphire, magnesium fluoride, calcium fluoride, lithium fluoride, and barium fluoride, and resin materials such as silicone resin and fluororesin.

[0055] Furthermore, although the optical filter 20b of this embodiment is formed on the main surface 20a of the light-transmitting window 20 as shown in FIG. 5, it may also be formed on the main surface 20c of the light-transmitting window 20 opposite to the main surface 20a.

[0056] In this embodiment, the length of the light emitting tube 30a of the ultraviolet light source 30 in the tube axis direction (Y direction) is 70 mm, the distance between the ultraviolet light source 30 and the optical filter 20b is 8 mm, and the size of the optical filter 20b is (X, Y) = (60 mm, 45 mm). Note that each size configuration described here is merely an example, and each size can be arbitrary as long as it is configured so that the relative intensity distribution of the ultraviolet light Lx incident on the optical filter 20b shows an intensity peak at an incident angle θ of 10 degrees or more and 50 degrees or less.

[0057] 6 is a graph showing the transmittance characteristics of the optical filter 20b in this embodiment for each angle of incidence θ of ultraviolet light with respect to the main surface 20a of the light-transmitting window 20. The optical filter 20b in this embodiment is formed of a dielectric multilayer film, and is configured to have a band that transmits ultraviolet light Lx having a wavelength in the range of 190 nm to 235 nm, as shown in FIG.

[0058] The graph in Fig. 6 was obtained by measuring the spectrum of light transmitted through optical filter 20b using a spectrophotometer. Specifically, Fig. 6 is a graph obtained by changing the exit angle corresponding to the incident angle θ with respect to optical filter 20b in 10-degree increments within the range of 0 to 60 degrees, and measuring the transmittance for wavelengths from 200 nm to 320 nm at each incident angle θ.

[0059] The graph shown in FIG. 6 is created by superimposing the waveforms of the transmittance for each incident angle θ obtained by the measurement.

[0060] Furthermore, as shown in FIG. 6, the optical filter 20b in this embodiment is configured so that the wavelength λ5 at which the transmittance is 5% for ultraviolet light incident on the main surface 20a of the light-transmitting window 20 at an incident angle θ of 0 degrees (this wavelength λ5 is, in short, the wavelength on the long wavelength side at which the transmittance is 5%) is 240 nm.

[0061] The optical filter 20b made of a dielectric multilayer film can adjust the wavelength λ5 by finely adjusting the film thickness of each film that makes up the dielectric multilayer film.

[0062] As the incident angle θ of the ultraviolet light Lx incident on the light-transmitting window 20 increases, the band through which the ultraviolet light Lx passes gradually shifts toward the shorter wavelength side, and the peak value of the transmittance of the optical filter 20b gradually decreases. However, as shown in Fig. 6, the optical filter 20b of this embodiment maintains a transmittance of 50% or more for ultraviolet light in the wavelength band of 200 nm or more and 230 nm or less, even when the incident angle θ of the ultraviolet light Lx exceeds 40 degrees.

[0063] Here, the "relative intensity distribution" in this specification will be explained with reference to the drawings. Fig. 7A is a diagram schematically showing a method for acquiring the relative intensity distribution of ultraviolet light incident on optical filter 20b formed on a flat surface, and Fig. 7B is a diagram showing ultraviolet light source 30 shown in Fig. 7A as viewed from the light emission direction. Fig. 7C is a diagram schematically showing a method for acquiring the relative intensity distribution of ultraviolet light incident on optical filter 20b formed on a curved surface. For convenience of illustration, the housing 10 that houses ultraviolet light source 30 shown in Figs. 7A to 7C is shown with a different configuration from the housings 10 shown in other drawings.

[0064] First, we will explain how to acquire the relative intensity distribution when light is incident on the main surface 20a of the light-transmitting window 20, i.e., the optical filter 20b formed on a flat surface. In the inactivation device 1 configured as shown in Figures 7A and 7B, with the optical filter 20b removed, the angle θi is changed by 5 degrees in a first direction (in this embodiment, the circumferential direction with the central axis being a straight line passing through the center Q1 and parallel to the tube axis direction of the arc tube 30a) using a position at which the ultraviolet light emitted from the ultraviolet light source 30 can be detected as a reference, which is located in the direction of the normal N1 from the center Q1 of the ultraviolet light source 30 to the plane on which the optical filter is formed, to measure the intensity of the ultraviolet light in an emission angle range of 0 to ±90 degrees.

[0065] Here, angle θi is defined as the inclination angle of the light ray with respect to the normal N1 of the light-transmitting window 20, and the light intensity is measured at a position that is a predetermined distance away from the ultraviolet light source 30. As shown in Fig. 7A, when the ultraviolet light source 30 is configured to include multiple arc tubes 30a, measurement is performed assuming that light is emitted from the center Q1 of the region 30c in which the arc tubes 30a are arranged.

[0066] When performing measurements, it is desirable that the distance from the ultraviolet light source be at least 10 times the size of the light source. For example, in this embodiment, the distance is desirably 50 cm or more. Ensuring a sufficient distance makes it easy to treat the light source as a substantial point light source, but if the distance is short, calculation errors are likely to occur.

[0067] Next, with the optical filter 20b removed, the angle θi is changed in increments of 5 degrees in a second circumferential direction (in this embodiment, the circumferential direction centered on a straight line that passes through the center Q1 and is parallel to the arrangement direction of the arc tubes 30a) and the intensity of the ultraviolet light is measured in an emission angle range of 0 to ±90 degrees. Note that the first and second directions are defined such that, when viewed from the direction of the normal N1, the movement lines of the measuring instrument C1 are perpendicular to each other when the measuring instrument C1 is moved to align its position with each measurement point, as shown in FIG.

[0068] By the above-described method, the light intensity distribution is measured at 5-degree intervals in the first direction and the second direction with the optical filter 20b removed.

[0069] Next, the light intensity obtained by the above-mentioned method is calculated by integrating the radiant flux for each component of the angle θi (for convenience of notation, the explanation is given in radians [rad] here) when viewed from the total luminous flux of ultraviolet light. For ultraviolet light incident on the optical filter 20b, the radiant flux for each component of the angle θi is calculated as V θi Then, the radiant flux V θi is calculated according to the value of angle θi using the following formulas 1 to 3.

[0070]

number

[0071] The above formula 1 is applied when the angle θi is θi=0.

[0072]

number

[0073] The above formula 2 is applied when the angle θi is in the range of 0<θi<π.

[0074]

number

[0075] The above formula 3 is applied when the angle θi is θi=π.

[0076] Here, "I Aθi " is the light intensity of the ultraviolet light at the angle θi in the first direction, and "I Bθi " is the light intensity of the ultraviolet light at the angle θi in the second direction. Also, "Δθ" is the measurement angle interval in each of the first direction and the second direction. The measurement angle interval Δθ is π / 36 (= 5 degrees).

[0077] For example, the radiant flux V of the angular component where the angle θi is π / 12 (= 15 degrees) θi When calculating the light intensity I when the angle θi of the ultraviolet light in the first direction is 15 degrees, Aθi and the light intensity IBθi of the ultraviolet light in the second direction when the angle θi is 15 degrees. The measurement angle interval Δθ is set to π / 36 (=5 degrees). Then, using the above formula 2 that applies when the angle θi is π / 12 (=15 degrees), the radiant flux V θi is calculated.

[0078] By the above procedure, the radiant flux V for each angle θi (hereinafter, the explanation will be given again in degrees) θiBy calculating and graphing the angle θi at which the integrated intensity peaks, it is possible to determine the angle θi at which the integrated intensity peaks. Figure 7D shows the radiant flux V for each angle θi in the measurement system shown in Figures 7A and 7B. θi 7A and 7B, the ultraviolet light source 30 shown in FIG. 7A and FIG. 7B has a radiant flux V within the angle θi range of 20 degrees or more and 50 degrees or less, as shown in FIG. 7D. θi A peak of light intensity of .gtoreq.1000 is formed.

[0079] When the optical filter 20b is formed on a curved surface rather than a flat surface, the light intensity for each angle θi is measured based on a normal N1 to the tangent surface T1, as shown in Fig. 7A. The normal N1 is a perpendicular line drawn from the center Q1 to the tangent surface T1.

[0080] However, due to the curvature of the optical filter 20b, as shown in Fig. 7C, there are portions where the angle between the traveling direction of the light ray to be measured and the normal N1 differs from the angle between the traveling direction of the light ray to be measured and the normal N2 of the tangent surface T2 at the position where the light ray actually passes through. Therefore, when the optical filter 20b is formed on a curved surface, the light intensity of the radiant flux of ultraviolet light obtained for each angle θi is corrected for the angle θi. The correction is as follows.

[0081] For ease of explanation, the following description will be given on the assumption that the optical filter 20b is curved only in the first direction, as shown in Fig. 7C. If the optical filter 20b is curved in the first direction, a correction angle θic with respect to the normal N2 perpendicular to the tangent surface T2 of the optical filter 20b is calculated from the angle θi with respect to the normal N1 of the light emitted from the center Q1 of the ultraviolet light source 30.

[0082] When the optical filter 20b is formed on a curved surface, the radiant flux V of ultraviolet light calculated by the above-mentioned method is θi is corrected by regarding it as the light intensity of the radiant flux at the correction angle θic. Aθi " is the radiant flux of ultraviolet light based on the angle θi of the first direction, and "V Bθi" is the radiant flux of ultraviolet light based on the angle θi in the second direction, but the angle θi in the first direction at which the optical filter is curved is considered to be the radiant flux of the correction angle θic, and "V Aθi " is treated as the radiant flux of ultraviolet light based on the correction angle θic.

[0083] In this case, the radiant flux per corrected angular component in the first direction, V Aθi ” and the relative intensity distribution of the radiant flux “V Bθi By adding the relative intensity distribution of " and ", the corrected total radiant flux "V θi If the optical filter 20b is curved in the second direction as well, the above-described correction is performed in the second direction as well.

[0084] Next, a test was conducted to confirm the relationship between the wavelength λ5 of the optical filter 20b and the harmful light ratio for ultraviolet light transmitted through the optical filter 20b and emitted from the housing 10, and this test will be described.

[0085] As described above, the "harmful light ratio" here is defined as the ratio of the integrated intensity of ultraviolet light with a wavelength of 235 nm or more and 320 nm or less to the integrated intensity of ultraviolet light with a wavelength of 200 nm or more and 230 nm or less, for ultraviolet light emitted from the inactivation device.

[0086] As mentioned above, the cumulative dose of ultraviolet light irradiated onto the human body has a specified standard value for each wavelength. Therefore, for each inactivation device to be verified, the maximum light intensity is standardized to "1" so that the intensity at the peak wavelength (222 nm in this verification) of the ultraviolet light L1 emitted from the light-transmitting window 20 is the same, and the harmful light ratios are compared.

[0087] Example 1 In Example 1, the inactivation device 1 described above was used.

[0088] (Comparative Example 1) In Comparative Example 1, the inactivation device had the same configuration as in Example 1, except that the wavelength λ5 was adjusted to 235 nm by adjusting the thickness of each of the dielectric multilayer films constituting the optical filter 20b. FIG. 8 is a graph showing the transmittance characteristics of the optical filter provided in the inactivation device of Comparative Example 1 for each angle of incidence θ of ultraviolet light with respect to the light-transmitting window 20. The graph in FIG. 8 was created in the same manner as in the case of FIG. 6 described above. Compared to the characteristics of the optical filter 20b shown in FIG. 6, it can be seen that the optical filter of Comparative Example 1 has a lower total amount of transmitted ultraviolet light in the wavelength band of 200 nm or more and 230 nm or less.

[0089] (result) Figure 9 is a graph obtained by adding up the UV light emitted from the light-transmitting windows of the inactivation devices of Example 1 and Comparative Example 1, taking into account the solid angle of the emitted UV light and the integrated amount for each angular component based on the relative intensity distribution incident on the optical filter. This corresponds to the spectrum obtained when the differences in spectrum and relative intensity for each angular component are homogenized for the entire luminous flux of UV light transmitted through the optical filter. The graph shown in Figure 9 shows the relative intensity on a logarithmic scale, with the vertical axis representing the light intensity at a wavelength of 222 nm as 1. Note that the graph shown in Figure 9 also approximates the spectrum obtained when the light emitted from the optical filter is completely diffused.

[0090] The harmful light ratio calculated based on the graph shown in Figure 9 was 0.69% for Example 1 and 0.72% for Comparative Example 1. In other words, it was confirmed that the ultraviolet light L1 emitted from the inactivation device 1 of Example 1 had a lower ratio of the intensity of harmful light to the intensity of ultraviolet light used in the inactivation process than the ultraviolet light emitted from the inactivation device of Comparative Example 1.

[0091] As shown in Fig. 6, the optical filter 20b of Example 1 has a high transmittance from a wavelength of approximately 300 nm when the incident angle θ is 60 degrees, and a high transmittance from a wavelength of approximately 310 nm when the incident angle θ is 50 degrees. In contrast, as shown in Fig. 8, the optical filter of Comparative Example 1 has a high transmittance from a wavelength of approximately 290 nm when the incident angle θ is 60 degrees, a high transmittance from a wavelength of approximately 300 nm when the incident angle θ is 50 degrees, and a high transmittance from a wavelength of approximately 310 nm when the incident angle θ is 40 degrees.

[0092] In an optical filter made of a dielectric multilayer film, when the wavelength λ5 is changed by adjusting the film thickness of each layer, the transmittance characteristics change in accordance with the change in wavelength λ5. Specifically, as shown in Figures 6 and 8, as the wavelength λ5 is shifted to the short wavelength side, the band where the transmittance increases near a wavelength of 300 nm shifts to the short wavelength side.

[0093] For this reason, as shown in the graph of FIG. 9, the relative intensity of the ultraviolet light with wavelengths of 240 nm to 320 nm in Comparative Example 1 is higher than the intensity of the ultraviolet light L1 in Example 1.

[0094] Furthermore, as shown in Figures 6 and 8, in all optical filters, the transmittance is 10% or less in the wavelength band of 200 nm to 210 nm, and the transmittance increases as the wavelength moves from 210 nm toward longer wavelengths. This characteristic remains almost unchanged with changes in wavelength λ5. This is because the blocking wavelength range for longer wavelength ultraviolet light varies depending on the film design of the optical filter, but the optical filter itself absorbs shorter wavelength ultraviolet light.

[0095] As described above, the integrated light amount of the ultraviolet light L1 emitted from the light-transmitting window 20 at the peak wavelength (wavelength 222 nm in this verification) is set to a predetermined standard value (22 mJ / cm in this verification). 29 ), the light intensity of the ultraviolet light Lx generated by the ultraviolet light source 30 is adjusted. In this case, the ultraviolet light source 30 in Example 1 is more likely to maintain a high level of transmittance at the peak wavelength compared to the ultraviolet light source 30 in Comparative Example 1. Therefore, compared to the ultraviolet light source 30 in Comparative Example 1, the ultraviolet light source 30 in Example 1 does not deteriorate the harmful light ratio when irradiating ultraviolet light until the integrated light amount at the peak wavelength reaches a predetermined standard value, and it can be seen from FIG. 9 that the harmful light ratio is lower.

[0096] Therefore, compared to the inactivation device of Comparative Example 1, the inactivation device 1 of Example 1 shows less fluctuation in the integrated value of light intensity in the wavelength band of 200 nm or more and 230 nm or less, and the integrated value of light intensity in the wavelength band of 235 nm or more and 320 nm or less fluctuates more.

[0097] Fig. 10 is a graph showing the harmful light ratio for optical filter 20b for each incident angle θ, with the vertical axis representing the harmful light ratio and the horizontal axis representing the incident angle θ. As shown in Fig. 10, in an optical filter designed to have a wavelength λ5 of 236 nm, the harmful light ratio is 30% or less when the incident angle θ is in the range of 0 to 50 degrees, and becomes higher than 30% when the incident angle θ is 50 degrees or more.

[0098] In addition, an optical filter designed to have a wavelength λ5 of 244 nm has a harmful light ratio of over 5.0% when the incident angle θ is 0 degrees, but as the incident angle θ increases, the harmful light ratio gradually decreases, and when the incident angle θ is in the range of 10 degrees to 50 degrees, the harmful light ratio is 5% or less. When the incident angle θ is greater than 60 degrees, the harmful light ratio exceeds 30%.

[0099] From the above, it can be seen that the peak value of the radiant flux for each angular component of ultraviolet light incident on the optical filter is located within a range that suppresses the harmful light ratio to at least 30% and therefore the incident angle θ at which the peak appears in the relative intensity distribution is preferably within the range of 10 degrees to 50 degrees. Furthermore, in order to further reduce the harmful light ratio, it is more preferable that the incident angle θ at which the peak appears in the relative intensity distribution be within the range of 10 degrees to 45 degrees, and particularly preferably within the range of 20 degrees to 40 degrees.

[0100] Finally, it will be explained that the relative intensity distribution of ultraviolet light Lx incident on the optical filter 20b in this embodiment shows an intensity peak when the incident angle θ is in the range of 20 degrees or more and 50 degrees or less. Fig. 11 is a diagram explaining the progression of light emitted from a point light source A1 as a uniform luminous flux in all directions. As shown in Fig. 11, it is assumed that light is emitted from the point light source A1 as a uniform luminous flux in all directions, and a portion of the light is irradiated onto a plane Px.

[0101] 11, the region on the plane Px where the light beam emitted from the point light source A1 is incident at an incident angle θ of 0 degrees is defined as P0, and the region on the plane Px where the light beam is incident at an incident angle θ of 30 degrees is defined as P30. Then, as can be seen from FIG. 11, on the plane Px, the region P0 is only one point, whereas the region P30 is a circular region centered on the region P0.

[0102] Furthermore, as described above, if point light source A1 emits light with a uniform luminous flux in all directions, the total luminous flux of light incident on the entire annular region at position P30 is greater than the luminous flux of light incident on only one point at position P0. In other words, assuming that the light source is a point light source, the total amount of luminous flux of light incident on a given surface increases as the angle of incidence θ increases from 0 degrees. This means that the relative intensity of each angular component of the radiant flux is greater at position P30 than at position P0.

[0103] The ultraviolet light source 30 mounted in the inactivation device 1 of this embodiment can be considered equivalent to point light sources arranged in the axial direction of the light-emitting tube 30a. If we consider each of the arranged point light sources, the luminous flux incident on the optical filter 20b will be minimum when the incident angle θ is 0 degrees, and the total amount of luminous flux will gradually increase as the angle of incidence θ increases from 0 degrees.

[0104] The intensity of the ultraviolet light Lx incident on the optical filter 20b is proportional to the amount of light flux. The amount of light flux incident on the optical filter 20b increases as the incident angle θ increases from 0 degrees. When the incident angle θ reaches a certain large range, the amount of light flux that cannot enter the optical filter 20b increases, and the amount of light flux of the ultraviolet light Lx decreases. The incident angle θ at which the amount of incident light flux begins to decrease is adjusted by the distance between the ultraviolet light source 30 and the optical filter 20b, the size of the light-emitting tube 30a of the ultraviolet light source 30, the area where the optical filter 20b is formed, and the like. The specific sizes of the ultraviolet light source 30 and the optical filter 20b are as described above.

[0105] The above results confirm that the optical filter 20b, which has a wavelength λ5 set to be equal to or greater than 236 nm and less than 245 nm, is relatively effective in reducing the harmful light ratio for ultraviolet light Lx having an incident angle θ in the range of 10 to 50 degrees. Therefore, it is preferable that the relative intensity distribution of the ultraviolet light Lx incident on the optical filter 20b has a lower light intensity when the incident angle θ is outside the range of 10 to 50 degrees than when the incident angle θ is within the range of 10 to 50 degrees. In other words, it is preferable that the intensity peak in the relative intensity distribution of the ultraviolet light Lx incident on the optical filter 20b is included in the range of the incident angle θ of 10 to 50 degrees.

[0106] For the above reasons, the ultraviolet light L1 emitted from the inactivation device 1 of Example 1 has a lower harmful light ratio than the ultraviolet light emitted from the inactivation device of Comparative Example 1.

[0107] Therefore, with the above configuration, the inactivation device 1 can reduce the proportion of ultraviolet light that has an effect on the human body contained in the emitted ultraviolet light L1. In other words, an inactivation device 1 is realized in which the intensity of ultraviolet light in a wavelength band that has little effect on the human body is improved, while the intensity of ultraviolet light in a wavelength band that has an effect on the human body is the same as or lower than conventional inactivation devices.

[0108] 9, Example 1 has a relatively higher amount of ultraviolet light in the wavelength range of 235 nm to 240 nm and a relatively lower amount of ultraviolet light in the wavelength range of 240 nm to 320 nm than Comparative Example 1. In other words, the amount of ultraviolet light in the wavelength range of 240 nm to 280 nm, which is considered to have a greater impact on the human body, is reduced, while the amount of ultraviolet light in the wavelength range of 235 nm to 240 nm, which is considered to be safer than the wavelength range of 240 nm to 280 nm, is increased. Therefore, in Example 1, wavelength components that have a greater impact on the human body are reduced in the wavelength range of 235 nm to 320 nm, which includes wavelengths that may have an impact on the human body, and it is considered that safety is further improved.

[0109] As described above, in order to reduce the harmful light ratio, it is desirable to suppress the decrease in the integrated value of light intensity in the wavelength band of 200 nm or more and 230 nm or less, while reducing the integrated value of light intensity in the wavelength band of 235 nm or more and 320 nm or less.

[0110] Therefore, the optical filter may be a low-pass filter that limits the transmission of at least some ultraviolet light in the wavelength band of 235 nm or more and 320 nm or less, thereby making it difficult for the integrated value of light intensity in the wavelength band of 200 nm or more and 230 nm or less to decrease.

[0111] Alternatively, the optical filter may be a bandpass filter that transmits ultraviolet light with wavelengths of 200 nm to 230 nm and restricts the transmission of at least a portion of ultraviolet light in the wavelength band of 235 nm to 320 nm. In this case, the optical filter is preferably made of a material that absorbs ultraviolet light with wavelengths of 200 nm or less. Even if the absorption edge of the optical filter varies depending on the film design, the optical filter itself absorbs ultraviolet light with wavelengths of 200 nm or less, thereby stably restricting the transmission of ultraviolet light with wavelengths of 200 nm or less, and stabilizing the light intensity in the wavelength band of 200 nm to 230 nm. Examples of materials that absorb ultraviolet light with wavelengths of 200 nm or less include HfO2 and YO3.

[0112] As described above, the optical filter 20b contributes to reducing the harmful light ratio by being an optical filter with a wavelength λ5 of 236 nm or more and less than 245 nm, at which the transmittance is 5%. Furthermore, by making the optical filter a low-pass filter with a wavelength λ5 of 236 nm or more and less than 245 nm that transmits ultraviolet light with wavelengths of 200 nm to 230 nm, it is easy to prevent deterioration in the transmittance of ultraviolet light with wavelengths of 230 nm or less due to differences in the optical filter's film design. Furthermore, by using a band-pass filter made of a material that absorbs ultraviolet light with wavelengths of 200 nm or less, the transmission of ultraviolet light with wavelengths of 200 nm or less is stably limited, and the light intensity of ultraviolet light with wavelengths of 200 nm or more and 230 nm or less is easily stabilized.

[0113] In this embodiment, the optical filter 20b is configured to have a wavelength λ5 of 240 nm. However, from the viewpoint of suppressing the amount of ultraviolet light in a wavelength band that affects the human body extracted from the housing 10, the above-described verification results indicate that the wavelength λ5 of the optical filter 20b is preferably 236 nm or greater but less than 245 nm. Furthermore, to further suppress the amount of ultraviolet light in a wavelength band that affects the human body extracted from the housing 10, the upper limit of the wavelength λ5 of the optical filter 20b is preferably 243 nm or less, and more preferably 242 nm or less. Furthermore, to further increase the intensity of ultraviolet light in a wavelength band that has little effect on the human body, the lower limit of the wavelength λ5 of the optical filter 20b is preferably 237 nm or greater, preferably 238 nm or greater, and more preferably 239 nm or greater. Based on the above, for example, the wavelength λ5 of the optical filter is preferably 238 nm or greater but less than 243 nm.

[0114] The ultraviolet light source 30 in this embodiment may be any light source that generates ultraviolet light Lx, at least a portion of whose main emission wavelength band is within the range of 200 nm to 230 nm. The ultraviolet light source 30 may be, for example, an excimer lamp in which krypton (Kr) gas and bromine (Br) gas are sealed in the arc tube 30a as the light-emitting gas G1, and that emits ultraviolet light Lx with a peak wavelength of 207 nm. Alternatively, an ultraviolet light source using an LED, LD, or wavelength conversion member, whose peak wavelength is within the range of 200 nm to 235 nm, may be used.

[0115] [Another embodiment] Another embodiment will be described below.

[0116] <1> Fig. 12 is an enlarged view of the periphery of the ultraviolet light source 30 in another embodiment of the inactivation device 1. As shown in Fig. 12, the inactivation device 1 may further include a diffusion member 20d, located downstream of the optical filter 20b, that diffuses the ultraviolet light L1 emitted from the optical filter 20b.

[0117] The diffusing member 20d diffuses the ultraviolet light L1 that has passed through the optical filter 20b, homogenizing the light intensity, spectrum, and the like, which differ for each angular component of the ultraviolet light L1 emitted from the optical filter 20b. As a result, the ultraviolet light L1 emitted from the inactivation device 1 becomes a light beam with characteristics that are approximately the same as the spectrum shown in Fig. 9. Therefore, with the above configuration, the inactivation device 1 can improve the intensity of ultraviolet light in a wavelength band that has little effect on the human body and irradiate a wider area with ultraviolet light L1 with the proportion of harmful light maintained or reduced, thereby performing inactivation processing efficiently and safely over a wide area.

[0118] In this embodiment, as shown in Figure 12, a configuration is shown in which the diffusion member 20d is directly stacked on top of the optical filter 20b of the light-transmitting window 20, but the configuration of the diffusion member 20d is not limited to this configuration.For example, the diffusion member 20d may be configured to be fixed to the housing 10 by screws as a separate member, or may be configured to be positioned at a distance from the optical filter 20b.

[0119] <2> Figure 13 is a diagram schematically illustrating an example of another embodiment of the inactivation device 1. Figure 14 is an enlarged view of the inactivation device 1 of Figure 13. As shown in Figure 14, the inactivation device 1 may not include the housing 10, but may simply include a plate 20p on which an optical filter 20b is formed around a portion of the periphery of the ultraviolet light source 30.

[0120] The material of the plate 20p may be the same as that of the light-transmitting window 20. As shown in Fig. 14, the plate 20p is formed to be curved, but it may also be formed to be flat.

[0121] In this embodiment, the plate 20p is formed to be curved, and therefore the optical filter 20b is also formed on a curved surface rather than a flat surface, as shown in Fig. 14. In such a case, the relative intensity distribution for each angular component of the radiant flux of the ultraviolet light Lx incident on the optical filter 20b is determined by measuring for each inclination angle (incident angle θ) with respect to the normal line N1 at a predetermined location using the measurement method described above with reference to Figs. 7A and 7B, as shown in Fig. 14.

[0122] With the above configuration, for example, as shown in Figure 13, the lower space of room 2 where people come and go is irradiated with ultraviolet light L1 with a reduced proportion of harmful light. The upper space of room 2, which is higher than a person's height, is irradiated with ultraviolet light Lx without being attenuated by plate 20p or optical filter 20b. Aerosols and the like that are to be inactivation-treated and present in room 2 circulate between the lower and upper spaces within room 2 by natural convection. Therefore, by irradiating the upper space of room 2 with high-intensity ultraviolet light Lx, the inactivation treatment within room 2 progresses by natural convection.

[0123] Therefore, the inactivation device 1 of this embodiment can achieve both safety for people and highly efficient inactivation treatment.

[0124] <3> Figure 15 is a diagram schematically illustrating the configuration of an ultraviolet light source 30 in another embodiment of the inactivation device 1. As shown in Figure 14, the inactivation device 1 may have the optical filter 20b on the wall surface of the arc tube 30a that constitutes the ultraviolet light source 30, as long as the relative intensity distribution of the ultraviolet light Lx incident on the optical filter 20b has an intensity peak in the range of 20 degrees or more and 50 degrees or less. Note that the location where the optical filter 20b is formed may be either the inner wall surface 30a1 or the outer wall surface 30a2 of the arc tube 30a.

[0125] 15 is an excimer lamp having a rectangular cross section taken along a tube axis 30x, which is also called a flattened tube shape, and when a voltage is applied between a pair of electrodes (30b, 30b) disposed opposite each other across a light emitting tube 30a in which a light emitting gas G1 is sealed, ultraviolet light Lx is generated within the light emitting tube 30a. At this time, the ultraviolet light Lx is generated most in the vicinity of a plane 30p which is parallel to the electrodes (30b, 30b) and includes the tube axis 30x.

[0126] Here, an example of estimating the relative intensity distribution of ultraviolet light Lx incident on the optical filter 20b in this embodiment is shown. First, assume that multiple point light sources that emit the same luminous flux in all directions are densely arranged on the plane 30p. In this case, when viewed from the optical filter 20b, the light emitted from each point light source has the smallest luminous flux incident at 0 degrees, and as the angle increases, the luminous flux increases. Light above a certain incident angle does not enter the optical filter 20b.

[0127] In other words, in a flat tube-shaped excimer lamp, the ultraviolet light Lx incident on the optical filter 20b has a relative intensity distribution that includes a peak intensity when the incident angle θ is between 20 degrees and 50 degrees, by adjusting the distance between the electrodes (30b, 30b) and the width of the arc tube 30a (the distance between the opposing wall surfaces in a direction perpendicular to both the direction of the tube axis 30x and the opposing direction of the electrodes (30b, 30b)), etc.

[0128] An example of specific dimensions of the ultraviolet light source 30, which is a flattened tube-shaped excimer lamp that can be used in the inactivation device 1, is as follows: the distance between the electrodes (30b, 30b) is 8 mm, the width of the arc tube 30a is 20 mm, and the length of the arc tube 30a in the tube axis 30x direction is 100 mm. The optical filter 20b is formed over the entire flat area of ​​the inner wall surface 30a1 or 30a2.

[0129] The above-described configuration is merely one example, and as long as the relative intensity distribution is configured to satisfy predetermined conditions, the ultraviolet light source 30 may be an excimer lamp having a shape other than a flat tube shape. For example, an excimer lamp having a double tube shape, or an LED, laser, or the like may be used as a light source other than an excimer lamp.

[0130] <4> The configuration of the inactivation device 1 described above is merely an example, and the present invention is not limited to the illustrated configurations. [Explanation of symbols]

[0131] 1 : Inactivation device 2: Room 10: Housing 20: Translucent window 20a: Main surface 20b: Optical filter 20c: Main surface 20d: Diffusion element 20p: Plate 30 : Ultraviolet light source 30a: Arc tube 30a1: Inner wall surface 30a2: External wall surface 30b: Electrode 30p: Plane 30x: tube axis 70: Light intensity measuring instrument A1 : Point light source C1: Measuring Instruments G1: Luminous gas L1,Lx: Ultraviolet light N1,N2: normals P0,P30: Area Px: Plane Q1: Center T1,T2: Contact surface θ: angle of incidence

Claims

1. an ultraviolet light source that emits ultraviolet light having at least a portion of a main emission wavelength band within a range of 200 nm to 230 nm; an optical filter on which ultraviolet light generated by the ultraviolet light source is incident, the optical filter being formed of a dielectric multilayer film, and having a band that transmits ultraviolet light having a wavelength in the range of 190 nm or more and 235 nm or less for ultraviolet light incident at an incident angle of 0 degrees, and a wavelength λ5 at which the filter shows a transmittance of 5% being 236 nm or more and less than 245 nm; An inactivation device characterized in that the angle showing the peak value in the relative intensity distribution for each angular component of the radiant flux of ultraviolet light generated in the ultraviolet light source and incident on the optical filter is within the range of 10 degrees or more and 50 degrees or less.

2. 2. The inactivation device according to claim 1, further comprising: a housing that houses the ultraviolet light source; and a light-transmitting window for extracting the ultraviolet light to the outside of the housing, wherein the optical filter is provided on a main surface of the light-transmitting window.

3. 2. The inactivation device according to claim 1, wherein the wavelength λ5 of the optical filter is equal to or greater than 238 nm and less than 243 nm.

4. 2. The inactivation device according to claim 1, wherein the optical filter is made of a material that absorbs ultraviolet light having a wavelength of 200 nm or less.

5. 2. The inactivation device according to claim 1, wherein the ultraviolet light source emits ultraviolet light having a peak wavelength within the range of 210 nm to 235 nm.

6. 2. The inactivation device according to claim 1, wherein the ultraviolet light source is an excimer lamp in which a gas containing krypton (Kr) and chlorine (Cl) is sealed as a light emitting gas in a light emitting tube.

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