Ultraviolet light emitting element and ultraviolet light irradiation device

Abstract

The present invention provides a safe ultraviolet light irradiation device which uses ultraviolet light that is safe to the human body, and which has a wide range of microorganism elimination and sterilization effects. Disclosed is an ultraviolet light emitting element provided with: an electrode substrate that has a pair of electrodes; at least one cylindrical or flattened cylindrical glass tube that is disposed on the electrode substrate so as to face both of the electrodes, the glass tube having both end parts sealed; a discharge gas which is sealed inside the glass tube and contains a xenon gas that generates a discharge due to a voltage applied to the electrodes; and a phosphor layer which is formed on the inner surface of the glass tube and emits light when excited by the discharge. The glass tube is formed of borosilicate glass or quartz glass. The phosphor layer is formed of a phosphoric acid-based fluorescent material, and has an emission spectrum which has a peak half-value width within the wavelength range of 50 nm or less, with the peak being at a wavelength of 230 ± 10 inm on an illuminance basis.

Description

Ultraviolet light emitting element and ultraviolet irradiation device

[0001] The present invention relates to an ultraviolet light-emitting element and an ultraviolet irradiation device, and in particular to an ultraviolet light-emitting element and an ultraviolet irradiation device that can realize a sterilization device using ultraviolet light that is safe for the human body, without using expensive, high-performance filters, for the purpose of eliminating (including disinfecting and sterilizing) viruses and various bacteria and deodorizing.

[0002] In this specification, among ultraviolet rays (UV), deep ultraviolet rays (DUV) refer to radiation in the ultraviolet range with a wavelength of 200 nm to 300 nm, and vacuum ultraviolet rays (VUV) refer to ultraviolet rays with a wavelength of 200 nm or less generated by rare gas discharge. Furthermore, LAFi (Luminous Array Film) refers to a surface light source structure in which a gas discharge tube (a glass capillary) is filled with a discharge gas containing a mixture of phosphor, neon, and xenon, both ends of the glass tube are sealed, and a plurality of the glass capillaries are arranged on an electrode substrate to emit light.

[0003] In this specification, when the wavelength of ultraviolet light is based on "photon amount (photon number)" (here referred to as photon wavelength (unit: pnm)) and when "illuminance" is used as the standard (here referred to as illuminance wavelength (unit: inm)), there is a difference of about 10 nm, especially on the short wavelength side. In other words, the characteristics based on "photon amount (photon number)" are shifted to the long wavelength side by about 10 nm compared to the characteristics based on "illuminance". The reason for this is that illuminance (mW / cm 2) = n × h × C / wavelength. Here, n is the number of photons per unit, h is the Planck multiplier, and C is the speed of light. That is, there is a relationship of illuminance ∝ photon number / wavelength. Therefore, even with the same photon number, illuminance is higher at shorter wavelengths, so the illuminance spectrum shifts toward shorter wavelengths compared to the photon number spectrum. General-purpose measuring instruments with illuminance standards below 200 in. are difficult to obtain, and measurements below 200 in. are generally made based on the photon quantity standard. Factors that can cause the wavelength shift include the transmittance of the glass capillary and the non-uniform sensitivity of the light-receiving sensor in the illuminometer across wavelengths. Since glass transmittance and light-receiving sensor sensitivity tend to decrease as wavelengths become shorter, the peak wavelength of the emission spectrum shifts toward longer wavelengths in broadband light sources.

[0004] The sterilizing and deodorizing effects of ultraviolet light have long been well known, and various sterilizing or disinfecting devices that use ultraviolet light irradiation are known (see, for example, Patent Documents 1 to 4). Patent Document 1 proposes that wavelengths of 200 to 230 inm are optimal for ultraviolet light that is beneficial for virus inactivation and does not affect human cells. The device disclosed in Patent Document 1 cites an excimer lamp with a narrow peak wavelength at 222 inm as a representative example of a light source that emits deep ultraviolet light in this wavelength range.

[0005] Patent Literature 2014-508612 International Publication No. 2016 / 125708 Japanese Patent Laid-Open Publication No. 2015-193521 International Publication No. 2018 / 235723 International Publication No. 2022 / 113943

[0006] However, excimer lamps emitting deep ultraviolet radiation with a wavelength of 222 in. use highly toxic krypton chloride (KrCl) gas as the discharge gas, which inevitably poses environmental problems in the event of breakage. Furthermore, excimer lamp manufacturing sites require special facilities for poison prevention. Furthermore, the narrow emission wavelength range of KrCl excimer lamps makes it difficult to effectively sterilize many types of bacteria and viruses. That is, although more efficient inactivation of bacteria and viruses can be expected in wavelengths shorter than 222 in., the emission wavelengths of these excimer lamps are concentrated almost entirely around 222 in. Therefore, excimer lamps cannot be expected to have inactivation capabilities in wavelengths shorter than 222 in.

[0007] Furthermore, in the conventional surface-emitting ultraviolet light source device for sterilization disclosed in Patent Document 2, limitations on the glass material (old material) constituting the gas discharge tube and the phosphor material limited commercialization to a light source device with a peak wavelength around 260 in. When using such a light source device, deep ultraviolet light with wavelengths shorter than around 240 in. is absorbed by the glass material constituting the tube envelope. Therefore, there has been a demand for the development of a phosphor that emits shorter-wavelength ultraviolet light that is expected to have a high sterilizing effect against viruses and bacteria, and a new glass material that efficiently transmits deep ultraviolet light. Furthermore, there has also been a need for the development of a new technology for forming a phosphor within a glass tube so that the new phosphor can emit shorter-wavelength deep ultraviolet light with appropriate luminous efficiency.

[0008] Therefore, the present inventors have solved the above-mentioned problems and provided a deep ultraviolet irradiation device disclosed in Patent Document 5, which is a safe sterilization device that has a wide range of sterilization and disinfection effects against many viruses and bacteria and has little effect on the human body. This deep ultraviolet irradiation device is equipped with a broadband light source that emits ultraviolet light with a peak wavelength around 228 inm (hereinafter, this light source will be referred to as 228B).

[0009] The deep ultraviolet irradiation device of Patent Document 5 differs from conventional methods that use excimer lamps to emit wavelengths around 222 in., which are considered effective for bacterial inactivation, by using a gas discharge tube array-type surface-emitting light source device that utilizes deep ultraviolet phosphors as a deep ultraviolet light source. The deep ultraviolet irradiation device of Patent Document 5 also utilizes a deep ultraviolet phosphor layer that is excited by the discharge of xenon (Xe) gas and has a broad emission spectrum ranging from at least 210 to 250 in., with a peak wavelength around 228 in. The deep ultraviolet irradiation device of Patent Document 5 further includes an optical filter, if necessary, disposed opposite the light-emitting surface (the arrangement surface consisting of the light-emitting surfaces of the arranged gas discharge tubes) to reduce ultraviolet light in the wavelength range of 240 in. or more of the emission spectrum of the phosphor layer, i.e., to suppress transmission of ultraviolet light. This optical filter has a dielectric multilayer film filter structure formed on the surface of a UV-transmitting substrate made of quartz, and is positioned so that the UV-transmitting substrate faces the light-emitting surface of the surface-emitting UV light source device. The ultraviolet light transmitting substrate functions to adjust the angle of incidence of the light emitted from the light emitting surface onto the dielectric multilayer filter.

[0010] As described above, the conventional deep ultraviolet irradiation device disclosed in Patent Document 5 uses an optical filter to reduce the effective irradiance, which is an indicator of safety, thereby providing a device with higher safety. However, optical filters are expensive. Furthermore, with a diffuse broadband waveform such as 228B, the optical filter has a viewing angle dependency, making it difficult to efficiently remove ultraviolet light in the wavelength range of 240 inm or more, which is less safe. Therefore, the structure of the optical filter and irradiation device needed to be devised, resulting in the need for more expensive optical filters and complex structures.

[0011] The present invention provides a safe ultraviolet irradiation device that has a wide range of sterilizing and disinfecting effects against many viruses and bacteria, and also reduces ultraviolet rays in wavelength ranges that have adverse effects on the human body, i.e., does not basically use an optical filter that suppresses the transmission of ultraviolet rays, and has little effect on the human body.

[0012] The present invention provides an ultraviolet light-emitting element comprising: an electrode substrate having a pair of electrodes; at least one cylindrical or flat tubular glass tube placed on the electrode substrate so as to face either of the electrodes and having both ends sealed; a discharge gas containing xenon gas sealed inside the glass tube that generates a discharge when a voltage is applied to the electrodes; and a phosphor layer formed on the inner surface of the glass tube that is excited by the discharge and emits light, wherein the glass tube is borosilicate glass or quartz glass, and the phosphor layer is a phosphate-based fluorescent material, and the element exhibits an emission spectrum in a wavelength range with a half-width of 50 nm or less, with a peak at a wavelength of 203±10 inm based on illuminance.

[0013] The ultraviolet irradiation device of the present invention is based on the use of a new broadband light source (hereinafter referred to as 203B) as described below to effectively sterilize and minimize its effects on the human body. In the ultraviolet irradiation device of the present invention, the spectrum, expressed in terms of wavelength and illuminance, has a peak wavelength of 203±10 inm, preferably around 203 inm (200 inm to 208 inm). The ultraviolet irradiation device of the present invention emits continuous ultraviolet light that generates a wavelength range with a peak half-width of 50 nm, preferably a wavelength range of 40 nm. Light source 203B is a gas discharge tube array-type surface-emitting light source device that uses phosphors, similar to 228B proposed in Patent Document 5. However, compared to 228B, 203B is a light source that significantly reduces ultraviolet light in the wavelength range of 240 inm or more, which has adverse effects on the human body. Furthermore, the light emitted from the 203B phosphor (i.e., a broadband wavelength centered at 203 nm (approximately 210 pnm)) is excited by vacuum ultraviolet light emitted from Xe and emits light. This light is close to the broadband light centered around 180 pnm emitted from Xe through the glass tube. Therefore, in order to effectively extract the light from 203B, the light at 180 pnm must also be extracted.

[0014] When a phosphor is irradiated with 147 pnm and / or 172 pnm vacuum ultraviolet light generated by discharge in the glass tube to emit light, the ultraviolet light inherent to the phosphor within the glass tube is designated as ultraviolet light 1. The ultraviolet light extracted from ultraviolet light 1 through the wall of the gas discharge tube (glass capillary tube) is designated as ultraviolet light 2. Because ultraviolet light 1 and ultraviolet light 2 have wavelength ranges that are absorbed depending on the transmission characteristics of the glass when passing through the glass, they have different spectral characteristics. In other words, ultraviolet light 2 exhibits spectral characteristics that are completely different from ultraviolet light 1, depending on the material and thickness of the glass capillary tube, and the spectrum is only apparent once the device is fabricated. In the present invention, ultraviolet light 203B, which will be described later, refers to ultraviolet light 2.

[0015] As will be described in detail later, the inventors, through extensive research and experiments, have confirmed for the first time that the 203B of the present invention exhibits sterilization and disinfection capabilities equivalent to or superior to those of conventional 228B. Furthermore, the inventors evaluated the effective irradiance used in safety standards and found that in the ultraviolet wavelength range of 240 inm or more, 203B without an optical filter can ensure safety equivalent to or superior to that of conventional 228B that uses an optical filter to reduce ultraviolet light, i.e., suppress ultraviolet light transmission. This led the inventors to discover that the above-mentioned problems can be solved and to develop the present invention.

[0016] In another aspect of the present invention, the ultraviolet irradiation device according to the present invention is basically an apparatus that does not require an optical filter. However, if even higher safety is required, it is preferable to provide an optical filter or a timer to control the operating time of the surface-emitting ultraviolet light source device. The optical filter combined in the present invention can be similar to that proposed in Patent Document 5. That is, this optical filter has a dielectric multilayer filter structure formed on the surface of an ultraviolet-transmitting substrate such as quartz, and the ultraviolet-transmitting substrate is positioned so that it faces the light-emitting surface of the surface-emitting ultraviolet light source device. The ultraviolet-transmitting substrate functions to adjust the angle of incidence of the light emitted from the light-emitting surface to the dielectric multilayer filter.

[0017] In another aspect of the present invention, the glass material constituting the envelope of the gas discharge tube is borosilicate glass or quartz glass, which has high transmittance in the deep ultraviolet region. Borosilicate glass has the property of absorbing ultraviolet rays in the wavelength range of 175 to 200 pnm, thereby suppressing the emission of ultraviolet rays in the vacuum ultraviolet region with wavelengths of 190 pnm or less, which generate ozone harmful to humans. This allows for the emission of vacuum ultraviolet rays (VUV: second peak) centered at 180 pnm, which are emitted from the xenon (Xe) gas sealed as the discharge gas and extracted to the outside of the glass tube. Furthermore, quartz glass transmits vacuum ultraviolet rays better than borosilicate glass, allowing for the emission of vacuum ultraviolet rays (VUV: second peak) centered around 173 pnm. Furthermore, the present invention can utilize a surface-emitting ultraviolet light source device consisting of a gas discharge tube array that can efficiently emit deep ultraviolet rays included in 203B, particularly deep ultraviolet rays in the wavelength range of 200 inm to 250 inm, which are expected to be most effective for sterilization and disinfection, from a phosphor layer.

[0018] In yet another aspect of the present invention, by using 203B as a broadband light source for emitting ultraviolet rays, ultraviolet rays in the wavelength range of 240 inm or more, which are harmful to the human body, are significantly reduced. Furthermore, the present invention provides an ultraviolet irradiation device that limits the radiation of short-wavelength ultraviolet rays generated inside by adjusting the thickness (film thickness) of the glass tube that constitutes the envelope of the gas discharge tube. That is, 203B emits ultraviolet rays in the deep ultraviolet range over a wide wavelength range from 200 inm to 250 inm, which are expected to be most effective for sterilization and disinfection, while significantly suppressing the radiation of ultraviolet rays with wavelengths of 240 inm or more, which are harmful to the human body. Furthermore, ultraviolet rays in the vacuum ultraviolet range of wavelengths of 190 pnm or less, which generate ozone harmful to the human body, can be suppressed by adjusting the film thickness of the glass tube depending on the glass material. For example, in the case of a glass tube made of borosilicate glass, by setting the film thickness in the range of approximately 60 to 300 μm, it is possible to effectively suppress the radiation from the glass tube of ultraviolet rays in the vacuum ultraviolet range with wavelengths of 200 μm or less, particularly ultraviolet rays in the vacuum ultraviolet range with wavelengths of 190 μm or less that generate ozone that is harmful to the human body.

[0019] As another aspect of the present invention, the inventors, through extensive research and experimentation, have discovered that while the 203B broadband light source used in the ultraviolet irradiation device of the present invention has many advantages as described above, it also has a problem of "high temperature dependency." Therefore, the ultraviolet irradiation device of the present invention is preferably characterized by including a heat dissipation mechanism or cooling device that suppresses or controls temperature rise in the light source device. The heat dissipation mechanism or cooling device may be any of those that incorporate a specially designed substrate or device structure, or those that incorporate a device or element that actively promotes cooling. Specifically, for example, a slit substrate with a through-hole such as a slit may be used as the electrode substrate constituting the light source device. A ceramic or aluminum heat sink, a Peltier device, or a vapor chamber may be attached to the back of the electrode substrate. Alternatively, a cooling fan may be installed on the back of the light source device. While the heat dissipation mechanism or cooling device is not limited to these, greater effectiveness can be achieved by combining multiple such specific configurations. Furthermore, when using a heat sink with high conductivity, such as made of aluminum, it is necessary to attach the heat sink to the back side of the electrode substrate at dispersed positions corresponding to each electrode pair in order to prevent electrical short circuits.

[0020] Another aspect of the present invention is characterized in that a quartz glass or borosilicate glass is placed at a distance of 1 mm or more from the surface of the light source device, and the surrounding area is sealed by sealing in the atmosphere. While ozone (molecular formula: O3) generation is effective when ozone is actively used, high concentrations of ozone are harmful, so suppressing its generation is necessary when not using ozone. This structure allows ozone to be contained within the sealed space, preventing its diffusion to the outside. Furthermore, since vacuum ultraviolet light is absorbed by oxygen in the gap between the surface of the light source device and the quartz glass or borosilicate glass to generate ozone, short-wavelength ultraviolet light is blocked by this gap. As a further variation, two sheets of quartz glass or UV-transmitting glass can be placed in close contact with the surface of the light source device with a gap of approximately 1 mm to 5 mm between them, and a sealed panel can be used to block short-wavelength ultraviolet light.

[0021] According to the present invention, it is possible to realize a deep ultraviolet irradiation device that has a wide range of sterilization and disinfection effects using ultraviolet light that is highly safe for the human body, without using expensive, high-performance optical filters. Furthermore, even when the ultraviolet irradiation device is used by people who are unfamiliar with handling ultraviolet light, or when the ultraviolet irradiation device is used in an environment that is not designed and controlled to prevent the leakage of ultraviolet light in wavelength ranges that are harmful to the human body, the ultraviolet irradiation device can be operated safely. The ultraviolet irradiation device of the present invention covers a wide wavelength range of 200 inm to 250 inm, which is expected to be most effective for sterilization and disinfection, but the radiation of ultraviolet light in the deep ultraviolet range of wavelengths above 240 inm, which is harmful to the human body, is significantly reduced.

[0022] FIG. 1 is a schematic diagram showing the configuration of a gas discharge tube array type surface-emitting ultraviolet light source device in a first embodiment of an ultraviolet irradiation device according to the present invention. FIG. 2 is a schematic diagram showing the configuration of a gas discharge tube array type surface-emitting ultraviolet light source device in a first embodiment of an ultraviolet irradiation device according to the present invention. FIG. 3 is a schematic diagram showing the configuration of a gas discharge tube array type surface-emitting ultraviolet light source device in a first embodiment of an ultraviolet irradiation device according to the present invention. FIG. 4 is a perspective view showing a heat sink as a heat dissipation mechanism. FIG. 5 is a perspective view showing another heat sink as a heat dissipation mechanism. FIG. 6 is a perspective view showing a Peltier element as a cooling device. FIG. 7 is a perspective view showing a combination of a heat dissipation mechanism and a cooling device. FIG. 8 is a diagram showing the light transmission characteristics of borosilicate glass based on photons. FIG. 9 is a diagram showing the emission spectrum of each ultraviolet light source. FIG. 10 is a diagram showing an action function with respect to wavelength. FIG. 11 is a diagram showing the inactivation rate of each ultraviolet light source. FIG. 12 is a diagram showing the variation in illuminance depending on the lighting time of each ultraviolet light source. FIG. 13 is a diagram showing the variation in illuminance depending on the lighting time of each ultraviolet light source. FIG. 14 is a diagram showing the variation in illuminance depending on the temperature change in a 203B light source. FIG. 15 is a cross-sectional diagram showing a second embodiment of an ultraviolet irradiation device. FIG. 16 is a comparison table showing the effective irradiation illuminance in each method. FIG. 17 is a schematic diagram showing a UV irradiation device according to a third embodiment. FIG. 18 is a schematic diagram showing a UV irradiation device according to a third embodiment. 15A is a schematic diagram showing a fourth embodiment of the ultraviolet irradiation device according to the present invention; FIG. 15B is a diagram showing the emission spectrum characteristics of the 203B light source according to the present invention; FIG. 15C is a schematic diagram showing a fifth embodiment of the ultraviolet irradiation device according to the present invention; FIG. 15D is a table showing the increase in the surface temperature of 203B under various conditions; and FIG. 15E is a graph of FIG.

[0023] The present invention will be described in more detail below with reference to the accompanying drawings. Note that the following description is given by way of example only in all respects and should not be construed as limiting the present invention.

[0024] [First Embodiment] [Basic Configuration and Driving Principle of Surface-Emitting Ultraviolet Light Source Device] Except for the phosphor material and glass capillaries used, the gas discharge tube array used as a surface-emitting ultraviolet light source device in the present invention is basically the same as the configuration disclosed in the aforementioned Patent Document 5. The present invention utilizes a gas discharge tube array-type surface-emitting ultraviolet light source device, which is characterized by not using highly toxic KrCl gas or environmentally unfriendly mercury, as a light source for generating deep ultraviolet rays in the wavelength range (185 pnm to 240 pnm) that is beneficial for virus inactivation.

[0025] 1A to 1C are schematic diagrams showing the configuration of a gas discharge tube array-type surface-emitting ultraviolet light source device in a first embodiment of an ultraviolet irradiation apparatus according to the present invention. FIG. 1A is a cross-sectional view of a gas discharge tube serving as a deep ultraviolet light-emitting element. The gas discharge tube 1 is, for example, primarily comprised of a glass capillary tube 2 having an oblate elliptical cross section with a major axis of approximately 2 mm and a minor axis of approximately 1 mm, and a length of 8 cm. A deep ultraviolet phosphor layer 3 is provided on the inner surface of the rear side opposite the ultraviolet radiation side. Furthermore, the gas discharge tube 1 is configured such that a discharge gas 4 containing a rare gas, such as a mixture of neon (neon, element symbol: Ne) and xenon (Xe), or a mixture of helium (helium, element symbol: He) and xenon (Xe), or a mixture of argon (argon, element symbol: Ar) and xenon (Xe), or krypton, which emits vacuum ultraviolet light, is sealed inside the glass capillary tube 2, and both ends are sealed.

[0026] When generating only DUV radiation, inexpensive borosilicate glass or soft glass with high UV transmittance is used as the material for the glass capillary tube 2. When simultaneously generating VUV and DUV radiation, UV-transmitting borosilicate glass or quartz glass, which have a borosilicate composition with improved UV transmittance due to the addition of trace amounts of fluorine or other additives, are suitable. Examples of such UV-transmitting borosilicate glass include glass known as BU-41 manufactured by Nippon Electric Glass Co., Ltd. and SCHOTT 8337B manufactured by SCHOTT. Figure 2 shows the photon-based light transmittance characteristics of borosilicate glass (the transmittance of a UV-transmitting glass tube). In Figure 2, the horizontal axis represents wavelength (pnm) and the vertical axis represents transmittance. Because borosilicate glass has the ability to absorb UV radiation in the wavelength range of 175 to 200 pnm, controlling the glass thickness can also suppress UV radiation in the vacuum UV range of 190 pnm or less, which generates ozone harmful to humans. Lines A and B in Figure 2 show the light transmittance of UV-transmitting glass tubes made using Nippon Electric Glass Co., Ltd.'s product names BU-41-2 and BU-41-3. Of course, quartz glass, which is more expensive but has excellent UV transmittance, may also be used. When manufacturing the glass capillary tube, the UV-transmitting borosilicate glass tube is redrawn to a wall thickness (film thickness) of 200 μm or less, preferably about 100 μm, to obtain a glass capillary tube 2 that transmits light from the vacuum ultraviolet region of about 170 nm to the deep ultraviolet region of about 280 nm with a transmittance of 80% or more. This glass capillary tube 2 is made of borosilicate glass that transmits 80% or more of light at a wavelength of 200 pnm and 45% or less at a wavelength of 180 pnm, based on the photon quantity. However, a wall thickness of 50 μm or less is not preferred because it lacks strength and is prone to breakage.

[0027] The deep ultraviolet phosphor layer 3 newly adopted in the present invention is made of scandium (Sc, element symbol: Sc) phosphate ScPO 4, which has an emission spectrum peak at a wavelength of about 203 nm when excited by vacuum ultraviolet light, for example. ４ Phosphate-based fluorescent materials such as

[0028] The excitation source of the vacuum ultraviolet rays in the phosphor layer 3 may be any light source capable of emitting vacuum ultraviolet rays with an excitation wavelength of 200 nm or less. For example, such an excitation source may be krypton (Kr) gas (wavelength 147 nm), xenon (Xe) gas (wavelength 173 nm), neon (Ne) (wavelength 143 nm), or a mixture of these gases.

[0029] FIG. 3 shows the emission spectra of each ultraviolet light source. The emission spectrum of the surface-emitting ultraviolet light source used in the ultraviolet irradiation device according to the present invention, due to the phosphor and glass capillary tube described above, has a peak wavelength of 203±10 inm, preferably around 203 inm (200 to 208 inm), as shown as an example in FIG. 3, designated 203B. Furthermore, the ultraviolet irradiation device according to the present invention emits ultraviolet light that generates a wavelength range with a peak half-width of 50 inm, preferably a wavelength spread of about 40 inm. While such 203B has a peak around 203 inm and limitations in measurement in the low wavelength range, it emits effective vacuum ultraviolet light and deep ultraviolet light in at least the range of 180 pnm to 235 inm, with a continuous broad wavelength range spanning approximately 170 pnm to 260 inm.

[0030] Figure 3 shows the emission spectra of two light sources, 228B (a light source according to the present invention) and 275 inm (a broadband light source emitting ultraviolet light with a peak wavelength around 228 inm) for comparison (hereinafter, referred to as 275B). In Figure 3, wavelength is plotted on the horizontal axis (unit: inm), and the illuminance of each wavelength is plotted on the vertical axis as a ratio to the illuminance of the peak wavelength. The basic structure of 228B and 275B is the same as that of 203B. Figure 4 shows the action function, i.e., the adverse effect (degree of inhibition) of ultraviolet light of each wavelength (horizontal axis: unit: inm) on the human body, expressed as a coefficient. The action function has a coefficient value of "1" as the maximum, and the lower the coefficient value, the less adverse effect there is, i.e., the greater the safety. The action function based on Figure 4 is maximum at around 270 inm, i.e., the coefficient value is "1", and is approximately 30% (coefficient value 0.3) at around 300 inm on the long wavelength side and around 240 inm on the short wavelength side. Furthermore, the action function rapidly decreases on the short wavelength side from around 240 inm.

[0031] The emission spectrum in Figure 3 was measured under the following conditions. The measuring instrument was a Maya 2000 Pro manufactured by Ocean Photonics. Within this spectrum, the wavelength range of 200 inm or more was measured in illuminance mode. Since the wavelength range of 203B below 200 inm is the measurement limit of this measuring instrument in illuminance mode, it was measured in photon mode (see Figure 13), and the spectrum was calculated from the correlation of the waveforms in the wavelength range of 200 inm or more between illuminance mode and photon mode. 203B was positioned approximately 1 mm from the measuring head of the measuring instrument, and the measuring head and 203B were placed in a container capable of sealing nitrogen. The illuminance mode measurement was performed in an air atmosphere, and the photon mode measurement was performed in a nitrogen atmosphere.

[0032] Returning to Figure 3 and comparing the illuminance spectra, 203B has a broadband emission spectrum with a peak near 203-204 in. For 203B, the emission spectrum near 240 in. is less than 20% (approximately 1 / 10) of the peak, and the emission spectrum near 250 in. is less than 10% (approximately 1 / 20) of the peak. The emission spectrum becomes even smaller as the wavelength increases. In contrast, for 228B, the emission spectrum near 240 in. is approximately 60% of the peak, resulting in significantly greater adverse effects (degree of inhibition) on the human body compared to 203B. Furthermore, for 275B, the illuminance of the emission spectrum is also highest in the wavelength range near 270 in., where the action function is highest.

[0033] As described above, the inventors of the present invention have clarified for the first time that the ultraviolet light source 203B used in the deep ultraviolet irradiation device according to the present invention has a significantly improved safety compared to conventional ultraviolet light sources. Furthermore, when the inventors compared the sterilization performance of the light source 203B according to the present invention with that of the conventional 228B, they confirmed for the first time that 203B exhibits sterilization and disinfection capabilities equivalent to those of 228B.

[0034] Fig. 5 is a diagram comparing the sterilization ability of each light source as an inactivation rate to demonstrate the above, and shows the results of inactivating natto bacteria by irradiating them with ultraviolet light using the three types of light sources, 203B, 228B, and 275B, shown in Fig. 3. In Fig. 5, the inactivation rate on the vertical axis represents the value obtained by dividing the "residual number of bacteria" after ultraviolet irradiation under each condition (the three types of light source) by the "number of bacteria before ultraviolet irradiation." The horizontal axis of Fig. 5 represents the irradiation dose (mJ / cm 2 ) is shown.

[0035] As is clear from Figure 5, the inactivation rate at the same irradiation dose was lowest when 203B was irradiated, and it can be seen that 203B has an inactivation power equal to or greater than that of 228B and 275B. In comparing the three types of light sources, 203B, 228B, and 275B, the inventors of the present invention discovered for the first time through this experiment the order shown in Figure 5, that is, that 203B has an inactivation power almost equal to that of 228B but greater than that of 275B. In addition, in this experiment, the irradiation dose required for 99.9% inactivation was approximately 8 mJ / cm for 203B and 228B, respectively. 2 , 21.5 mJ / cm for 275B 2 is.

[0036] The sterilization experiment shown in Figure 5 was carried out as follows. The bacteria used were Bacillus subtilis natto. Approximately 6 million Bacillus subtilis natto were dispersed in an aqueous solution and applied to 10 culture beds (Sanispec Stamps). One culture bed was left unexposed to ultraviolet light, and the other culture beds were assigned three each to 203B, 228B, and 275B ultraviolet light. 203B was assigned to 4.5, 9, and 12 mJ / cm, respectively. 2 The three types are 4.3, 8.6, and 12.9 mJ / cm for 228B, respectively. 2 The three types of 275B are 9.2, 23, and 32 mJ / cm 2 Three types of UV irradiation were performed. Ten culture beds, including one that was not irradiated with UV light, were then left in a 30°C incubator for 20 hours to cultivate the bacteria. Afterwards, photographs of each culture bed were taken and the number of remaining bacteria was examined. The inactivation rate for each condition was calculated by dividing the number of bacteria under each condition by the number of bacteria in the culture bed that was not irradiated with UV light. The sterilization effect of UV light tends to be similar for bacteria and viruses, and the effect can be represented by bacteria.

[0037] As described above, 203B, the light source used in the deep ultraviolet irradiation device according to the present invention, is safer than the previously proposed 228B and 275B, has equal or greater inactivation power, and is the most efficient light source. This fact was first revealed through research and experiments by the inventors of the present invention. While 203B has many advantages as described above, it was found that its irradiance varies greatly depending on the lighting time. Figure 6 is a diagram showing the variation in irradiance depending on the lighting time of each ultraviolet light source, and shows the relationship between lighting time and irradiance for each of the light sources 203B, 228B, and 275B. In Figure 6, the horizontal axis represents lighting time (seconds), and the left vertical axis represents irradiance (mW / cm 2 ) and the right vertical axis represents the coefficient of variation (rate of variation). In Figure 6, the graphs represent, from top to bottom, the illuminance of 228B, the rate of variation of 228B, the rate of variation of 275B, the rate of variation of 203B, the illuminance of 275B, and the change in illuminance of 203B. As is clear from the graph, the illuminance of 203B drops more rapidly in a short period of time than 228B and 275B, and the rate of variation is also greater.

[0038] The measurements shown in Figure 6 were performed as follows. 203B, 228B, and 275B were each driven by a homemade inverter using a light source with an illumination surface measuring 8 cm x 6 cm. A voltage of 12 V was applied to the inverter, and a current of 1.4 A was applied. The illuminance was measured non-contact with a handheld simple illuminometer placed 5 mm away from the light source surface. This handheld simple illuminometer cannot capture the full wavelength range of each light source, so the measured values ​​are relative, but this does not hinder the measurement of the relative value of illuminance fluctuations due to lighting time.

[0039] Figure 7 shows the time variation of illuminance and temperature depending on the lighting time. In Figure 7, the horizontal axis shows the lighting time (seconds), and the left vertical axis shows the illuminance (mW / cm 2) and the right vertical axis represents temperature (°C). The graphs, from top to bottom, show the temperature of 203B, the illuminance of 228B, the temperature of 228B, and the change in illuminance of 203B. All graphs show the cases where light source devices 203B and 228B are cooled by blowing air on them. As is clear from FIG. 7 , the temperature of both 203B and 228B increases and the illuminance decreases as the UV light source is turned on for a longer period of time. Thus, the decrease in illuminance depends on the temperature increase over time, and the temperature increase and illuminance decrease for 203B are greater than those for 228B. Furthermore, as shown in FIG. 7 , when cooling is performed by blowing air on the device, the temperature increase and illuminance decrease are smaller than those for the case of FIG. 6 where no cooling is performed.

[0040] The measurements shown in Figure 7 were performed as follows. For 203B and 228B, a light source with an irradiation surface of 8 cm x 6 cm was used, as in Figure 6. Temperature and illuminance were measured at the same time. Illuminance was measured as described above, but temperature was measured non-contact using an infrared thermometer for a specified irradiation time.

[0041] 8 is a diagram showing the change in illuminance with respect to the temperature change in the 203B light source. In FIG. 8, the horizontal axis represents temperature (°C), and the left vertical axis represents illuminance (mW / cm 2) and the right vertical axis represents the room temperature ratio of illuminance. In the graph of Figure 8, graphs D and C use a 203B light source with an 8 x 6 cm irradiation area using a slit substrate. Figure 8 compares the temperature and illuminance measured when two 203B light sources were placed on a desk and driven, with the temperature increased without cooling (graph D), and the temperature and illuminance measured when the light sources were raised 1.5 cm above the desk to facilitate cooling by wind (approximately 4 m / s) (graph C). Since graph D is not cooled, the temperature rises to 62°C, while graph C, with a fan applied, only rises to 42°C. In both cases, the illuminance decreases as the temperature rises. Graphs A and B represent the temperature-illuminance relationships of graphs D and C, respectively, normalized by the illuminance at 25°C. The fact that graphs A and B follow nearly identical curves up to 42°C with respect to the temperature increase indicates that illuminance is a function of temperature. From this curve, it can be seen that by limiting the temperature rise to within 10 degrees, the illuminance fluctuation can be limited to 10%.

[0042] As is clear from FIG. 8 , suppressing temperature rise is essential for stable operation of the 203B light source according to the present invention. Therefore, the 203B light source must be cooled to suppress temperature rise by, for example, using a slit substrate, air cooling with a fan, using a heat sink, water cooling, or installing a Peltier element. For example, a heat dissipation mechanism such as a heat sink or a cooling device such as a Peltier element or vapor chamber, either alone or in combination, may be installed on the back of the 203B light source to dissipate heat or cool it. In this way, by suppressing temperature rise to approximately 35°C or less, fluctuations in illuminance can be suppressed to within 90% of the initial value, thereby achieving stabilization of the irradiation amount. This will be described in detail later with reference to FIGS. 15A and 15B.

[0043] [Surface-emitting ultraviolet light source device] We will now return to Figures 1A to 1C to continue the explanation. As shown in Figures 1A and 1B, a gas discharge array-type surface-emitting ultraviolet light source device 10 is fabricated by arranging a plurality of gas discharge tubes 1 as ultraviolet light-emitting elements in parallel on an electrode substrate 11 equipped with electrode pairs 12 (pairs of electrodes 12X and 12Y). The electrode substrate 11 is based on an insulating substrate 13, such as a polyimide substrate, and has an adhesive layer 14 on its upper surface to support the array of gas discharge tubes 1, and an electrode pair 12 on the opposing lower surface. The electrode pair 12 is further covered with an electrode covering layer (insulating layer) 15. The electrode substrate 11 includes the electrode pair 12, the insulating substrate 13, the adhesive layer 14, and the electrode covering layer 15.

[0044] To enhance the heat dissipation or cooling effect of the surface-emitting ultraviolet light source device 10, a heat dissipation mechanism or cooling device 16 is selectively provided as needed on the lower surface side of the electrode pair 12 constituting the surface-emitting ultraviolet light source device 10 (the back surface side of the electrode covering layer (insulating layer) 15 of the electrode substrate 11). As the heat dissipation mechanism 16, for example, a heat sink 17 as shown in FIGS. 1D and 1E is used. The heat sink 17 is preferably made of ceramic or aluminum, but is not limited thereto. When a metal heat sink such as aluminum is used as the heat sink 17, it is necessary to attach it in multiple pieces (at least two pieces as shown in FIG. 1E) to the exposed back surface of the electrode covering layer 15 (see FIG. 1A) and corresponding to the electrodes 12X and 12Y (see FIG. 1B) to prevent electrical shorts.

[0045] Furthermore, to further enhance the heat dissipation or cooling effect of the surface-emitting ultraviolet light source device 10, a Peltier device 18, for example, as shown in FIG. 1F may be selectively used as the cooling device 16, as needed. In this case, the Peltier device 18 is provided so that its heat absorption plate 182 contacts the back surface of the electrode coating layer 15 constituting the electrode substrate 11. In the Peltier device 18, metal electrodes connected to a power supply line 185, and N-type semiconductors 183 and P-type semiconductors 184 are alternately connected between the heat sinks 181 and 182 arranged above and below. When current is applied from the power supply line 185, the heat absorbed by the heat absorption plate 182 moves to the heat sink 181 due to the Peltier effect and is then released from the heat sink 181. As a result, heat generated in the surface-emitting ultraviolet light source device 10 is effectively released into the atmosphere via the heat sink 182 and the heat sink 181. The cooling device 16 is not limited to a Peltier element; for example, a vapor chamber may be used instead of the Peltier element. Furthermore, as shown in FIG. 1G , by attaching a heat sink 17 to the heat sink 181 side of the Peltier element 18 and combining the two as a composite, heat from the heat sink 181 side of the Peltier element 18 can be efficiently removed, maximizing the functionality of the Peltier element 18. This further enhances the heat dissipation or cooling effect of the surface-emitting ultraviolet light source device 10. Alternatively, a vapor chamber may be attached to the heat sink 181 side of the Peltier element 18 instead of the heat sink 17, and the vapor chamber may be used as a means for effectively removing heat from the heat sink 181 side of the Peltier element 18. Hereinafter, when the heat sink 17 and / or the Peltier element 18 are used, the surface-emitting ultraviolet light source device 10 will be referred to as including the heat sink 17 and / or the Peltier element 18.

[0046] 1B has a structure in which an electrode pair 12 is formed on the lower surface of an insulating substrate 13, and an adhesive layer 14, which also serves as an insulating layer, supports the array of gas discharge tubes 1 on the upper surface of the insulating substrate 13. The electrode pair 12 is arranged on the bottom rear surface of each gas discharge tube 1, and is composed of electrodes 12X and 12Y in a pattern that extends on both sides of a common electrode slit (electrode gap G) between them.

[0047] If the insulating substrate 13, which forms the base of the electrode substrate 11, is made of an insulating film of polyimide resin and the gas discharge tubes 1 are arranged with gaps between them, it is possible to construct a flexible surface-emitting ultraviolet light source device 10 that can be bent in the direction of the tube arrangement as a whole. Furthermore, if ventilation slits are formed in the electrode substrate 11 so that the bottom surfaces of the gas discharge tubes 1 are partially exposed to the outside, this is convenient for heat dissipation and / or cooling to suppress or control the temperature rise of the gas discharge tubes 1.

[0048] When providing ventilation slits in the electrode substrate 11 facing the gas discharge tubes 1 so that the bottom surfaces of the gas discharge tubes 1 are partially exposed to the outside, V-shaped or approximately U-shaped groove-shaped slits (non-penetrating type) or slits (vent holes) penetrating the electrode substrate 11 are provided in a direction perpendicular to the arrangement direction of the discharge tubes 1. Providing ventilation slits perpendicular to the arrangement direction of the tubes allows heat generated from each gas discharge tube 1 to be dissipated to the outside almost evenly and allows air to be blown almost evenly to each gas discharge tube 1. This enhances the heat dissipation and / or cooling effect of the surface-emitting ultraviolet light source device 10, efficiently suppressing or controlling temperature rise. As a result, the reduction in illuminance of the surface-emitting ultraviolet light source device 10 can be suppressed, and the amount of irradiation can be stabilized. Note that, in the configuration shown in FIGS. 1A and 1B in which the electrode pairs 12 are formed on the underside of the insulating substrate 13, if a heat dissipation mechanism or cooling device 16 is provided, it may be located on the underside of the insulating substrate 13, i.e., on the bottommost side of the electrode substrate 11. In either case, this configuration is not limited to this. In the following, when a heat dissipation mechanism or cooling device 16 (heat sink 17 and / or Peltier element 18, etc.) is used, the heat dissipation mechanism or cooling device 16 (heat sink 17 and / or Peltier element 18, etc.) will be referred to as the electrode substrate 11 or the surface-emitting ultraviolet light source device 10.

[0049] [Driving Principle] Figure 1C is a schematic diagram illustrating the driving principle of the surface-emitting ultraviolet light source device 10. To the electrodes 12X and 12Y that make up the electrode pair 12, the inverter circuit 19 applies an alternating driving voltage with a peak-to-peak voltage (P-P voltage) of 1000 to 2000 V and a frequency of 30 to 40 kHz. As the alternating driving voltage applied by the inverter circuit 19 increases, an initial discharge occurs in the discharge gap in the gas discharge tube 1 that corresponds to the electrode gap G between the electrodes 12X and 12Y. Subsequently, as the alternating driving voltage increases, the discharge expands in the longitudinal direction of the gas discharge tube 1.

[0050] By applying an alternating drive voltage, such discharges occur repeatedly in the regions of the gas discharge tube 1 corresponding to electrodes 12X and 12Y, alternating the polarity of the accumulated charge. When the gas filled in the gas discharge tube 1 is a mixture of neon (Ne) and xenon (Xe), a discharge accompanied by the emission of vacuum ultraviolet (VUV) rays at 143 pnm and 172 pnm occurs at a lower discharge voltage than with other gases. This VUV excitation causes ultraviolet rays to be emitted from the phosphor layer 3, which then pass through the glass tube and emit ultraviolet rays with a center wavelength of 203 pnm. This drive principle and specific drive circuit are described in detail in the aforementioned Patent Document 2.

[0051] Second Embodiment A second embodiment of the present invention will be described below in detail with reference to the drawings. As described above, the ultraviolet irradiation device according to the present invention is a device that does not basically require an optical filter. However, to further enhance safety, an optical filter may be provided, and further, a timer may be provided to control the operating time of the surface-emitting ultraviolet light source device.

[0052] Fig. 9 is a cross-sectional view showing a second embodiment of an ultraviolet irradiation device. More specifically, Fig. 9 is a cross-sectional view showing the configuration of an ultraviolet irradiation device in which an optical filter 20 is combined with a surface-emitting ultraviolet light source device 10 according to the present invention having the structure shown as the first embodiment in Figs. 1A to 1G and an emission spectrum as shown by 203B in Fig. 3.

[0053] The optical filter 20 to be combined here may be similar to that proposed in Patent Document 5, but it is desirable that it has filter characteristics that transmit shorter wavelengths. That is, the optical filter 20 is an ultraviolet-transmitting substrate, preferably a synthetic quartz substrate 21 having a thickness of about 1 mm, on which an oxide film (for example, hafnium oxide (molecular formula: HfO ２ ) / silicon dioxide (SiO ２ The optical filter 20 has a dielectric multilayer filter 22 with a thickness of about 1 to 2 μm, which includes an oxide film such as a fluorine-containing oxide film (fluorine-containing oxide film) or the like. This optical filter 20 has the property of mainly transmitting deep ultraviolet light of 190 to 230 inm and blocking ultraviolet light of 240 inm or more, which is likely to have an adverse effect on human tissue, i.e., effectively blocking the transmission of ultraviolet light.

[0054] Incidentally, the deep ultraviolet light emitted from the surface-emitting ultraviolet light source device 10 (sometimes referred to as the gas discharge tube array 10) used as the light source in the present invention has a wide radiation angle. On the other hand, the dielectric multilayer film filter 22 combined with the surface-emitting ultraviolet light source device 10 has incidence angle dependency. Therefore, in a configuration in which the light emitted from the surface-emitting ultraviolet light source device 10 is directly incident on the dielectric multilayer film filter 22, the peripheral light of the ultraviolet light emitted at a wide angle cannot be sufficiently transmitted through the optical filter 20. This point is explained in Patent Document 5.

[0055] When combining the optical filter 20 with the surface-emitting ultraviolet light source device 10, the following can be done to maximize its effect. That is, in the present invention as well, the quartz substrate 21 is positioned on the incident surface side of the optical filter 20 so that the deep-ultraviolet radiation from the surface-emitting ultraviolet light source device 10 passes through the dielectric multilayer filter 22 as efficiently as possible. In this arrangement, the quartz substrate 21 functions, in front of the dielectric multilayer filter 22, as an optical element that converts the incident angle of the light at the optical filter 20 for the portion of the light with a large radiation angle among the deep-ultraviolet light radiated at a wide angle from each gas discharge tube 1.

[0056] 9, the refraction of the emitted light from the emission surface of the gas discharge tube 1 to the dielectric multilayer filter 22 is indicated by arrows 23. The light emitted from the emission surface of the gas discharge tube 1 constituting the surface-emitting ultraviolet light source device 10 is incident on the dielectric multilayer filter 22 with its emission angle narrowed due to the difference between the refractive index of the space between the gas discharge tube 1 and the quartz substrate 21 (air n≈1) and the refractive index of the quartz substrate 21 (n=1.5). As a result, attenuation of the radiation intensity of deep ultraviolet light centered at 203 inm that is emitted after passing through the optical filter 20 can be suppressed.

[0057] In order to reduce the incidence loss of deep ultraviolet radiation 23 emitted at a wide angle from the surface-emitting ultraviolet light source device 10 onto the dielectric multilayer filter 22, stripe or grid-patterned ribs functioning as a diffraction grating may be further provided on the incident surface side of the quartz substrate 21 constituting the optical filter 20. The stripe ribs corresponding to the arrangement pitch of the gas discharge tubes 1 can narrow the angle of incidence onto the dielectric multilayer filter 22 of the deep ultraviolet radiation emitted at a wide angle from each gas discharge tube 1 of the surface-emitting ultraviolet light source device 10.

[0058] Furthermore, each of the glass capillaries of the multiple gas discharge tubes 1 may further have a reflective layer formed on the outer surface of the back side facing the electrode substrate 11 or the side side facing the adjacent glass capillary, which reflects ultraviolet light from inside the glass capillary. Furthermore, by providing a metal film such as aluminum on the adhesive layer 14 located between the gas discharge tubes 1, 1 in the surface-emitting ultraviolet light source device 10, light radiated at a wide angle may be reflected forward, reducing the angle of incidence on the filter and allowing the light to be radiated effectively forward. This method also allows ultraviolet light to be radiated effectively forward even when a filter is not used.

[0059] Figure 10 is a table comparing the effective irradiance of each method. The table in Figure 10 shows the relationship between various light sources and effective irradiance (an index of the degree of inhibition: unit: mJ / cm 2) are compared. The various light sources include 228B, a combination of 228B and an optical filter, and 203B, a combination of 203B and an optical filter. Figure 10 shows the effective irradiance of ultraviolet light with wavelengths of 180 to 240 inm (vacuum ultraviolet region), the effective irradiance of ultraviolet light with wavelengths of 200 to 240 inm (a region considered less harmful in the UVC region), the effective irradiance of ultraviolet light with wavelengths of 240 to 300 inm, and the effective irradiance of ultraviolet light with wavelengths of 180 to 300 inm for the four light sources. The optical filter used is the optical filter 20 described above, which effectively blocks ultraviolet light with wavelengths of 240 inm or longer (i.e., substantially blocks the transmission of ultraviolet light), as shown in Figure 9. A lower effective irradiance indicates higher safety. The effective irradiance values ​​in Figure 10 are integrated values ​​obtained by performing a product-sum calculation for each wavelength using the emission spectrum in Figure 3 and the action function in Figure 4. The action functions in Figure 4 are unitless relative values. The spectra in Figure 3 are shown as unitless relative values ​​for comparison of waveforms, but the spectrum with the vertical axis representing irradiance is shown in mW / cm. 2 or μW / cm 2 The irradiation power per unit area is expressed as μW / cm in Figure 10. 2 The calculated values ​​are listed.

[0060] As is clear from Figure 10, the ultraviolet irradiation device using the above-mentioned 203B light source alone according to the present invention has a lower effective irradiation illuminance at wavelengths of 180 to 300 inm and is therefore safer than the conventional ultraviolet irradiation device using only a 228B light source and the ultraviolet irradiation device combining a 228B light source and an optical filter, even without an optical filter. In other words, the total effective irradiation illuminance at wavelengths of 180 to 300 inm is 50.3 μW / cm when the 203B light source is used alone. 2 and when using a 228B light source alone, it is 257.9 μW / cm 2Therefore, it can be seen that using the 203B light source alone is safer. Furthermore, the comparison table in FIG. 10 also reveals that using the 203B light source in combination with the optical filter 20 shown in FIG. 9 can further improve safety. Thus, the 203B light source according to the present invention can provide a highly safe ultraviolet irradiation device even without the use of an optical filter. Furthermore, in environments requiring safer ultraviolet irradiation, such as special cases requiring high safety or use by people with little knowledge or experience in handling ultraviolet light, an extremely safe ultraviolet irradiation device can be provided by using the 203B light source in combination with the optical filter 20 shown in FIG. 9. As shown in FIG. 10, when the 203B light source and optical filter are combined, the illuminance of ultraviolet light at wavelengths of 240 in. or longer is zero, making it the safest of the light sources compared.

[0061] The effective irradiance E in Fig. 10 eff is a safety indicator set out in the guidelines published by the Global Lighting Association (GLA). eff The smaller the value, the higher the safety. The emission spectrum φ(λ) is calculated based on the illuminance standard, and the effective irradiance E is calculated by multiplying the emission spectrum φ(λ) by the action function S(λ) shown in Figure 4. eff That is, the effective irradiance E(λ) of wavelength λ = emission spectrum φ(λ) × action function S(λ). Therefore, the effective irradiance of the target spectrum can be calculated by integrating the total spectrum wavelength for each wavelength. That is, the total effective irradiance E eff = ∫Emission spectrum φ(λ) × Action function S(λ) dλ, where λ is the wavelength (measured based on illuminance in units of in-m)

[0062] [Third Embodiment] Fig. 11A is a perspective schematic diagram showing an ultraviolet irradiation device according to a third embodiment of the present invention, illustrating the assembly configuration of the ultraviolet irradiation device. The ultraviolet irradiation device shown in Fig. 11A includes a base substrate 30 having an air inlet hole (not shown), a drive circuit board 40 mounted on the base substrate 30, and a blower fan 50 mounted above the drive circuit board 40. This ultraviolet irradiation device further includes a surface-emitting ultraviolet light source device 60 mounted above the blower fan 50, and an optical filter 20 mounted above the surface-emitting ultraviolet light source device 60 as needed. These components (the surface-emitting ultraviolet light source device 60 and the optical filter 20) are assembled and supported by four supports 31 in order from bottom to top. The surface-emitting ultraviolet light source device 60 is the same as the surface-emitting ultraviolet light source device 10 shown in Figs. 1A to 1G or 9, and the optical filter 20 may be selectively installed depending on the environment in which the ultraviolet irradiation device is used, the user, etc. The entire structure of the ultraviolet irradiation device is housed in a housing 70 shown by a dotted line and having an ultraviolet irradiation window (opening) at the top. For convenience, in Fig. 11A, the ultraviolet irradiation device is illustrated so that the light-emitting surface of the surface-emitting ultraviolet light source device 60 is approximately horizontal and the ultraviolet irradiation direction is upward, but the irradiation direction can be determined arbitrarily.

[0063] Here, the surface-emitting ultraviolet light source device 60 uses an electrode substrate 61 with slits as shown in FIG. 11B . Similar to the electrode substrate 11 described above with reference to FIG. 1B , the electrode substrate 61 shown in FIG. 11B has a plurality of through slits 64 formed through the electrode substrate 61, including the electrodes 12X and 12Y, approximately parallel to the discharge gap G. In such an electrode substrate 61 with slits, the bottom surfaces (back surfaces) of the arranged gas discharge tubes 1 are partially exposed downward to the outside, and vent holes are formed at the intersections of the through slits 64 and the gaps between adjacent gas discharge tubes. Therefore, the surface-emitting ultraviolet light source device 60 can be effectively cooled by the flow of cooling air from the blower fan 50 through the vent holes. The vent holes formed in the electrode substrate 61 are not limited to the slit shape described above, and may be a number of small holes distributed so that the back surfaces of the discharge tubes are partially exposed to the outside.

[0064] [Fourth Embodiment] Fig. 12 is a schematic diagram showing the configuration of an ultraviolet irradiation device that generates ozone as a fourth embodiment of the present invention. The ultraviolet irradiation device shown in Fig. 12 includes a base substrate 30 having ventilation holes (not shown), a gas discharge tube array-type surface-emitting ultraviolet light source device 10 provided above the base substrate 30, an optical filter 20 provided on the front side (light-emitting surface side) of the surface-emitting ultraviolet light source device 10, a drive circuit board 40 provided on the back side of the surface-emitting ultraviolet light source device 10, and a housing 70 (shown by a dotted line) that houses these components (the base substrate 30, the surface-emitting ultraviolet light source device 10, the optical filter 20, and the drive circuit board 40). The housing 70 has a window for emitting ultraviolet light in the wall facing the optical filter 20. The optical filter 20 may be disposed arbitrarily and may be omitted. A space that functions as an ozone generation space 51 is formed on the front side, which is the ultraviolet irradiation side, of the surface-emitting ultraviolet light source device 10 (or between the light source device 10 and the optical filter 20 if an optical filter 20 is disposed). In addition, a space that functions as a heat dissipation path 52 is formed between the surface-emitting ultraviolet light source device 10 and the drive circuit board 40. A blower fan 50 is provided inside the housing 70, facing one end face of the ozone generation space 51 and the heat dissipation path 52. The housing 70 has an exhaust port in a wall portion facing the other end faces of the ozone generation space 51 and the heat dissipation path 52. When driven, air is blown from the blower fan 50, and ozone in the ozone generation space 51 is exhausted to the outside through the exhaust port, and heat generated by the gas discharge tube array 10 and the drive circuit board 40 is released to the outside through the exhaust port via the heat dissipation path 52. 12 illustrates an example in which the blower fan 50 is disposed on the side (one end side) of the surface-emitting ultraviolet light source device 10, but it may also be disposed on the back side of the light source device 10, and is not limited to the example illustrated here. In the fourth embodiment, the surface-emitting ultraviolet light source device 10 is the same as the surface-emitting ultraviolet light source device 10 described in FIGS. 1A to 1G or 9, and the optical filter 20 may be selectively provided depending on the environment in which the ultraviolet irradiation device is used, the user, etc.

[0065] In the fourth embodiment, as described with reference to FIG. 1A , each gas discharge tube 1 constituting a surface-emitting ultraviolet light source device 10 has a thin glass capillary tube 2 made of quartz glass or thin borosilicate glass with high ultraviolet transmittance. The shorter wavelengths of vacuum ultraviolet radiation, with a peak wavelength of 172 pnm, generated by the discharge of xenon (Xe) gas within the tube 1 are absorbed by the glass of the glass capillary tube 2. Vacuum ultraviolet radiation with a peak wavelength of approximately 180 pnm is then emitted into the space within the tube 1. Therefore, the deep ultraviolet (DUV) emission spectrum of the phosphor layer 3, with a wavelength width of at least 180 to 230 pnm and a peak wavelength (first peak) of approximately 210 pnm (203 pnm) (210±10 pnm), and vacuum ultraviolet (VUV) with a peak wavelength (second peak) of approximately 180 pnm (180±10 pnm) are simultaneously emitted into the space within the tube 1. FIG. 13 shows the emission spectrum characteristics of a 203B light source according to the present invention. In Fig. 13, the horizontal axis represents wavelength (pnm) and the vertical axis represents the number of photons. Fig. 13 also shows the radiation spectra of VUV (light A) and DUV (light B) from the gas discharge tube array type surface-emitting ultraviolet light source device of the 203B light source shown in Fig. 12. In this embodiment, the phosphor layer 3 exhibits an emission spectrum in which the wavelength of a first peak, at which the illuminance relative to the wavelength is maximum, is in the range of 203±10 innm (preferably 200 to 208 innm) based on illuminance, and the half-width of the first peak is in a wavelength range of 50 nm (see Fig. 3), and the second peak, at which the illuminance is lower than the first peak, has a wavelength of 180±10 pnm based on photon quantity, and the spectral width at 70% of the peak value of the second peak is in a wavelength range of 20 nm (see Fig. 13). Alternatively, in this embodiment, the phosphor layer 3 exhibits an emission spectrum in which the wavelength of a first peak, at which the illuminance relative to the wavelength is maximum, is in the range of 203±10 inm (preferably 200 to 208 inm) based on the illuminance, and the half-width of the first peak is in a wavelength range of 50 nm (see FIG. 3 ), and the second peak has an illuminance lower than the first peak, the wavelength of the second peak is in the range of 173±5 pnm based on the photon amount, and the half-width of the second peak is in a wavelength range of 20 nm (see FIG. 13 ).Although not clearly shown in Figure 13 , the wavelength transmittance characteristics of glass and air absorb the shorter wavelengths of the emitted light. This is based on the idea that, as these wavelength transmittance characteristics become more uniform (i.e., transmittance does not decrease even on the shorter wavelength side), the 180 pnm peak shifts to 173 pnm. For example, if the transmittance of the glass is significantly reduced below 200 pnm on the shorter wavelength side, or if there is light absorption on the shorter wavelength side by oxygen in the air, the second peak at 180 pnm, as shown by light B in Figure 13 , does not appear. However, as the decrease in transmittance on the shorter wavelength side is gradually alleviated, the second peak at 180 pnm begins to appear, as shown by light A. Furthermore, as the transmittance on the shorter wavelength side is increased, the second peak at 180 pnm shifts toward 173 pnm. In principle, when there is no influence of glass transmittance or light absorption by oxygen, the second peak at 180 pnm coincides with the molecular beam emission peak of Xe gas.

[0066] Figure 13 shows that vacuum ultraviolet light is absorbed by the air layer. In other words, in Figure 13, light A and light B represent the spectra measured when the light-emitting element 203B was measured in a nitrogen atmosphere and an air atmosphere, respectively. Because there is no absorption of vacuum ultraviolet light in a nitrogen atmosphere, light up to the 170 pnm wavelength range reaches and is detected by a photodetector approximately 5 mm away (light A). On the other hand, in an air atmosphere, light in the wavelength range below 190 pnm is absorbed by oxygen between the light source and the photodetector, generating ozone, and is not detected. That is, light in the wavelength range below 190 pnm is cut off (light B). The distance between the surface of 203B shown in Figure 12 and the measurement head of the photodetector (not shown) was set to 5 mm. In 203B, the voltage applied to the inverter was 12 V, and the current was 1.4 A. Because there is no absorption of vacuum ultraviolet light in a nitrogen atmosphere, light up to the 170 pnm wavelength range reaches the photodetector approximately 5 mm away, resulting in the spectrum of light A. On the other hand, in the atmosphere, light below 190 pnm is absorbed by oxygen before it reaches the photodetector, generating ozone, meaning that light below 190 pnm is cut off and not detected, resulting in the detection of the spectrum of light B. Incidentally, each of the hump-shaped peaks below 190 pnm occurs when light reacts with ozone and is absorbed. The difference between light A and light B contributes to the generation of ozone.

[0067] The drive circuit board 40 is equipped with a drive circuit including an inverter circuit 19 (see FIG. 1C ) that supplies an alternating drive voltage to the surface-emitting ultraviolet light source device 10, a timer that controls the irradiation time, a control circuit that controls the entire ultraviolet irradiation apparatus, etc. When the surface-emitting ultraviolet light source device 10 is driven by the drive circuit, deep ultraviolet light of 240 inm or less with a peak wavelength around 203 inm is transmitted through the optical filter 20 and irradiated, thereby sterilizing and disinfecting the air in the irradiation space and the target object.

[0068] Meanwhile, vacuum ultraviolet rays generated within the gas discharge tube 1 are reflected by the phosphor layer 3, which also has a UV-reflecting function, and vacuum ultraviolet rays with wavelengths around 180 pnm are emitted from the light-emitting surface. Of this vacuum ultraviolet light, light of 190 pnm or less decomposes the air present in the ozone generation space 51 between the light-emitting surface of each gas discharge tube 1 and the optical filter 20, generating ozone. The principle of ozone generation using ultraviolet light is known. Briefly, vacuum ultraviolet rays (VUV: light A) generated within the gas discharge tube 1 are radiated into the air in the ozone generation space 51 outside the tube 1, where they chemically react with oxygen in the air to generate ozone. More specifically, when oxygen molecules absorb photons, which are ultraviolet particles, they dissociate into oxygen atoms, and the oxygen atoms combine with the oxygen molecules to generate ozone.

[0069] The ozone generated within the housing 70 is exhausted to the outside through the exhaust port along with the air from the blower fan 50, thereby sterilizing the ambient air. Ozone itself, of course, has strong oxidizing and toxic properties, making it extremely effective for sterilization, disinfection, and deodorization in unmanned, enclosed spaces regardless of concentration. However, excessive release into occupied spaces must be limited. Low concentrations of ozone are harmless to humans and are extremely beneficial for space sterilization. Therefore, ozone released into occupied spaces must be controlled so that the ozone concentration does not exceed the prescribed standard value of 0.1 ppm. Incidentally, a surface-emitting ultraviolet light source device 10 with an 8 x 3 cm light-emitting area and an array of 12 8 cm long gas discharge tubes can generate 20 mg of ozone per hour. The amount of ozone generated using such a surface-emitting ultraviolet light source device can be appropriately controlled by intermittently applying a driving AC voltage and changing its duty ratio. It can also be controlled by turning the drive on and off using feedback of the monitored ozone concentration in the ambient space.

[0070] Fifth Embodiment FIG. 14 is a schematic diagram showing an ultraviolet irradiation device according to a fifth embodiment of the present invention. When ozone is actively utilized, generating ozone as in the fourth embodiment is effective. However, because ozone is harmful, suppressing its generation is necessary when ozone is not utilized. In FIG. 14, the light source 10 is the same as the surface-emitting ultraviolet light source device 10 (see FIGS. 1B and 9) used in the above-described embodiments. As shown in FIG. 14, in this ultraviolet irradiation device, an optical filter 20 or a quartz plate 73 is disposed on the front side of the light source 11, i.e., on the ultraviolet radiation side, with a gap of approximately 5 mm. A sealing member 72 is disposed or applied around the periphery between the light source 10 and the quartz plate 73, thereby forming an airtight space 71 between the light source 10 and the quartz plate 73. The quartz plate 73 may or may not have a filtering function.

[0071] The effect of the fifth embodiment will be described with reference to FIG. 13. As shown in FIG. 13, light A is emitted from an ultraviolet light source using nitrogen (N ２) atmosphere. The emission spectrum of light A has two peak wavelengths near 180 pnm and 210 pnm, which are vacuum ultraviolet. On the other hand, light B is the emission spectrum measured when the same light source is placed in air. The emission spectrum of light B rapidly attenuates at wavelengths shorter than 190 pnm. This is because photons are absorbed by oxygen molecules, generating ozone. That is, according to the ultraviolet irradiation device of the fifth embodiment shown in FIG. 14, the air is sealed in the sealed space 71, and by sealing the area between the light source 10 and the optical filter 20 (see FIG. 9) or the quartz plate 73, the ozone generated in the sealed space 71 is also contained. At the same time, the ozone layer within the sealed space 71 absorbs light of 190 pnm or less (vacuum ultraviolet). Therefore, the generated ozone does not leak out of the sealed space 71, and light of 190 pnm or less does not leave the quartz plate 73, so ozone is not generated outside the quartz plate 73. Therefore, according to the fifth embodiment, when ozone is not actively used, it is possible to suppress or prevent the release of harmful ozone to the outside. In the case of the embodiment shown in Fig. 14, since it is necessary to create an enclosed space 71, it is not possible to provide slits (through holes) for heat dissipation in the substrate of the light source 10. However, slits can be provided in the substrate of the light source 10 as follows. In this case, a similar effect (the effect of suppressing the release of ozone to the outside) can be obtained by preparing two substrates that transmit ultraviolet light, sealing the space between the two substrates with air and sealing the periphery, and placing this panel on the front side (light-emitting surface side) of the light source 10.

[0072] [Summary of Measures to Prevent Temperature Increase in the 203B Light Source] Figure 15A is a table showing the increase in the surface temperature of the 203B under various conditions. In the table in Figure 15A, the irradiation time (seconds) is shown on the left side, and the temperature (°C) change over time under conditions (1) to (7) is shown. In Figure 15A, (1) is the condition of a slitted substrate, tabletop installation, and no fan. (2) is the condition of a slitted substrate suspended 1.5 cm and blowing air from the side. (3) is the condition of a fan blowing air from the back of the slitted substrate. (4) is the condition of a ceramic heat sink attached to the back of the slitted substrate. (5) is the condition of an aluminum heat sink attached to the back of the slitted substrate. (6) is the condition of an aluminum heat sink attached to the back of the non-slitted substrate. (7) is the condition of a fan blowing air from the back of the non-slitted substrate. FIG. 15B is a graph of the values ​​in FIG. 15A, with the horizontal axis representing irradiation time (seconds) and the vertical axis representing temperature (°C). The data in FIGS. 15A and 15B were obtained by using the surface-emitting ultraviolet light source device 10 of FIG. 1B and employing various heat dissipation or cooling methods to examine the effect of the heat dissipation or cooling method on suppressing temperature rise. As shown in (1) to (7) of FIG. 15A, the heat dissipation or cooling methods include providing slits in the electrode substrate, blowing air using a fan, and providing a ceramic or aluminum heat sink, either alone or in combination. Note that methods (1) to (7) did not use the Peltier element shown in FIGS. 1F and 1G.

[0073] As is clear from the results shown in Figures 15A and 15B, it was found that by using each of methods (2) to (6), it was possible to suppress the temperature rise to about 10 to about 15°C even when the LAFi-driven 203B light source shown in Figure 1B was operated continuously for about 4 minutes. By adopting each of methods (2) to (6), it was found that the decrease in illuminance due to a temperature rise of 10°C could be suppressed to about 10%, according to the temperature and illuminance characteristics of Figure 8, and this is not a problem in practice. With this combination of heat dissipation and cooling, it was found that the irradiation amount (illuminance (mW / cm)) required for the ultraviolet irradiation amount of the surface-emitting ultraviolet light source device 10 could be suppressed to about 10 to 15°C. 2In order to obtain the product of the temperature (°C) and the irradiation time (seconds), it is possible to secure the irradiation time even if the illuminance is somewhat reduced, and there is no need to control the irradiation time while managing the temperature, for example.

[0074] [Summary] According to the present invention, a safe ultraviolet irradiation device can be obtained that has a wide range of sterilization and disinfection effects using ultraviolet light that is safe for the human body, without using expensive, high-performance optical filters. Furthermore, according to the present invention, an ultraviolet sterilization device including an ultraviolet irradiation device can be obtained, and an ultraviolet germicidal lighting device including an ultraviolet irradiation device and a lighting device can also be obtained. Aspects of the present invention include combinations of any of the above-mentioned aspects. In addition to the above-described embodiments, various modifications of the present invention are possible. These modifications should not be construed as falling outside the scope of the present invention. The present invention should include all modifications within the scope of the claims and their equivalents.

[0075] 1: Gas discharge tube, 2: Glass thin tube, 3: Phosphor layer, 4: Discharge gas, 10, 60: Surface-emitting ultraviolet light source device, light source device, gas discharge tube array, light source, 11, 61: Electrode substrate, 12: Electrode pair, 12X, 12Y: Electrode, 13: Insulating substrate, 14: Adhesive layer, 15: Electrode coating layer (insulating layer), 16: Heat dissipation mechanism, cooling device, 17: Heat sink, 18: Peltier element, 19: Inverter circuit, 20: Optical filter, 21: Quartz substrate, synthetic quartz substrate, 22: Dielectric multilayer film filter, 23: Radiated light, arrow line, 30: Base substrate, 31: Support, 40: Drive circuit board, 50: Blower fan, 51: Ozone generation space, 52: Heat dissipation path, 64: Through slit, 70: Housing, 71: Sealed space, 72: Sealing member, 73: Quartz plate, 181: Heat dissipation plate, 182: Heat absorption plate, 183: N-type semiconductor, 184: P-type semiconductor, 185: Power supply line, G: Electrode gap

Claims

1. The present invention comprises an electrode substrate having a pair of electrodes, at least one cylindrical or flat tubular glass tube disposed on the electrode substrate so as to face either of the electrodes and having both ends sealed, a discharge gas including xenon gas sealed inside the glass tube and generating a discharge by a voltage applied to the electrodes, and a phosphor layer formed on the inner surface of the glass tube and excited by the discharge to emit light, the glass tube being made of borosilicate glass or quartz glass, and the phosphor layer being made of ScPO as a fluorescent material. ４ and exhibiting an emission spectrum in a wavelength range in which the half-width of the peak is 50 nm or less, with a wavelength of 203±10 inm based on illuminance.

2. The glass tube is made of quartz glass, 2. The ultraviolet light-emitting element according to claim 1, wherein the light emitted from the phosphor layer and extracted to the outside of the glass tube exhibits an emission spectrum in which the peak wavelength at which the illuminance is maximum is in the range of 203±10 inm based on the illuminance, and the half-width of the peak is in a wavelength range of 50 nm.

3. the glass tube is made of borosilicate glass that transmits 80% or more of light emitted inside the glass tube at a wavelength of 200 pnm on a photon basis; 2. The ultraviolet light-emitting element according to claim 1, wherein the phosphor layer exhibits an emission spectrum in which the wavelength of a first peak at which the illuminance relative to the wavelength is maximum is in the range of 203±10 innm on an illuminance basis, the half-width of the first peak is in a wavelength range of 50 nm, and a second peak having an illuminance lower than that of the first peak, the wavelength of the second peak is in the range of 180±10 pnm on a photon quantity basis, and the spectral width of 70% of the peak value of the second peak is in a wavelength range of 20 nm.

4. 3. The ultraviolet emitting element according to claim 2, wherein the peak wavelength is in the range of 200 to 208 inm based on illuminance.

5. 4. The ultraviolet emitting element according to claim 3, wherein the wavelength of the first peak is in the range of 200 to 208 inm based on illuminance.

6. 4. The ultraviolet light emitting element according to claim 3, wherein the emission intensity of light emitted by said phosphor layer at a wavelength of 250 inm based on illuminance is 10% or less of the emission intensity of said peak wavelength.

7. 4. The ultraviolet light emitting element according to claim 3, wherein the emission intensity of light emitted by the phosphor layer at a wavelength of 250 inm based on illuminance is 10% or less of the emission intensity of the first peak wavelength.

8. 3. The ultraviolet light emitting element according to claim 2, wherein the emission intensity of light emitted by said phosphor layer in a wavelength region of 240 innm or more based on illuminance is 20% or less of the emission intensity of said peak wavelength.

9. 4. The ultraviolet light emitting element according to claim 3, wherein the emission intensity of light emitted by said phosphor layer in a wavelength region of 240 innm or more based on illuminance is 20% or less of the emission intensity of said first peak.

10. The ultraviolet light emitting element according to claim 1 , comprising a plurality of the glass tubes; an ultraviolet irradiation device comprising a heat dissipation mechanism or a cooling device disposed on the rear side of the ultraviolet light emitting element to suppress an increase in temperature of each glass tube during light emission;

11. The ultraviolet irradiation device according to claim 10, wherein each of the plurality of glass tubes further has a reflective layer formed on an outer surface of a rear side facing the electrode substrate or a side side facing an adjacent glass tube, for reflecting ultraviolet light from inside each glass tube.

12. The ultraviolet irradiation device according to claim 10 , wherein the heat dissipation mechanism or cooling device includes a slit penetrating the electrode substrate.

13. 11. The ultraviolet irradiation device according to claim 10, wherein the heat dissipation mechanism or cooling device includes a ceramic or aluminum heat sink attached to the rear surface of the electrode substrate.

14. The ultraviolet irradiation device according to claim 10 , wherein the heat dissipation mechanism or cooling device includes a Peltier element or a vapor chamber attached to the rear surface of the electrode substrate.

15. an electrode substrate having a pair of electrodes; at least one cylindrical or flat tubular glass tube, both ends of which are sealed, disposed on the electrode substrate so as to face each of the electrodes; a discharge gas, including xenon gas, sealed inside the glass tube and generating a discharge when a voltage is applied to the electrodes; a phosphor layer formed on the inner surface of the glass tube and excited by the discharge to emit light; the glass tube is made of borosilicate glass that transmits, on a photon quantity basis, 80% or more of light emitted inside the glass tube at a wavelength of 200 pnm and 45% or less at a wavelength of 180 pnm; The phosphor layer is an ultraviolet light-emitting element, and the light emitted from the phosphor layer and extracted to the outside of the glass tube exhibits an emission spectrum in which the peak wavelength at which the illuminance is maximum is in the range of 203±10 inm based on the illuminance, and the half-width of the peak is in a wavelength range of 50 nm.

16. an electrode substrate having a pair of electrodes; at least one cylindrical or flat tubular glass tube, both ends of which are sealed, disposed on the electrode substrate so as to face each of the electrodes; a discharge gas, including xenon gas, sealed inside the glass tube and generating a discharge when a voltage is applied to the electrodes; a phosphor layer formed on the inner surface of the glass tube and excited by the discharge to emit light; The glass tube is made of quartz glass, The phosphor layer is an ultraviolet light-emitting element that exhibits an emission spectrum in which the wavelength of a first peak, at which the illuminance relative to the wavelength is maximum, is in the range of 203±10 innm on an illuminance basis, the half-width of the first peak is in a wavelength range of 50 nm, and a second peak has an illuminance lower than that of the first peak, the wavelength of the second peak is in the range of 173±5 pnm on a photon quantity basis, and the half-width of the second peak is in a wavelength range of 20 nm.

17. 16. The ultraviolet light-emitting element according to claim 15, wherein the phosphor layer exhibits an emission spectrum in which the wavelength of a first peak at which the illuminance relative to the wavelength is maximum is in the range of 203±10 innm on an illuminance basis, the half-width of the first peak is in a wavelength range of 50 nm, and a second peak having an illuminance lower than that of the first peak, the wavelength of the second peak is in the range of 180±10 pnm on a photon quantity basis, and the spectral width of 70% of the peak value of the second peak is in a wavelength range of 20 nm.

18. 17. The ultraviolet light-emitting element according to claim 16, wherein the light emitted from the phosphor layer and extracted to the outside of the glass tube exhibits an emission spectrum in which the peak wavelength at which the illuminance is maximum is in the range of 203±10 inm based on the illuminance, and the half-width of the peak is in a wavelength range of 50 nm.

19. The phosphor layer contains ScPO as a fluorescent material. ４ The ultraviolet emitting device according to claim 15 or 16, comprising:

20. 17. An ultraviolet irradiation device comprising: an ultraviolet light-emitting element according to claim 15 or 16 having a plurality of the glass tubes; and a heat dissipation mechanism or cooling device arranged on the rear side of the ultraviolet light-emitting element to suppress a rise in temperature of each glass tube during light emission.