Ultraviolet irradiation device

Abstract

To improve the decrease in uniformity of UV illuminance depending on the position of an object to be irradiated.SOLUTION: An ultraviolet irradiation device is equipped with an ultraviolet light source device that utilizes gas discharge, in which a plurality of discharge tubes, each having an ultraviolet-emitting phosphor layer inside, are arranged in parallel along an ultraviolet irradiation surface, and a common electrode pair is arranged facing the back side of the ultraviolet irradiation surface and extending in the longitudinal direction of each discharge tube, separating them by a discharge gap, and the plurality of discharge tubes are arranged such that the spacing between adjacent tubes is narrower at both ends than at the center.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] The present invention relates to an ultraviolet irradiation device that utilizes a surface light source consisting of an array of ultraviolet light-emitting gas discharge tubes. Hereinafter, in this specification, deep ultraviolet radiation (UVC) means ultraviolet radiation with a wavelength of 200 nm to 300 nm. Among deep ultraviolet radiation, deep ultraviolet radiation with a peak wavelength around 228 nm is called UVC1, and deep ultraviolet radiation with a peak wavelength around 260 nm is called UVC2. Vacuum ultraviolet radiation (VUV) means ultraviolet radiation with a wavelength of 200 nm or less that is generated by rare gas discharge. [Background technology]

[0002] Traditionally, ultraviolet light has been widely used in the fields of industry, medicine, sterilization, and the like, but the reality is that there are no practical light source devices other than high-pressure mercury lamps and excimer discharge lamps. In addition, deep ultraviolet light (UVC) is harmful to the human body, so there are limits on the amount of irradiation (irradiation intensity x time) that can be applied to the human body. In particular, deep ultraviolet light in the UVC2 region is highly harmful, so there has been little progress in the application of ultraviolet irradiation devices to sterilize the human body.

[0003] Recently, some of the inventors of the present application have developed a new light source using deep ultraviolet light in the UVC1 region, as shown in Patent Document 1. UVC1, which has a peak wavelength around 228 nm, is significantly less harmful than UVC2, which has a peak wavelength around 260 nm, and is therefore expected to be used for sterilization involving ultraviolet irradiation of the human body.

[0004] It is known that there is a risk of bacteria and viruses spreading through human hands and objects touched by hands in facilities such as hospitals, nursing homes, and restaurant kitchens. In the human body, it is particularly important to sterilize hands, including fingers. Objects touched by hands also need to be sterilized at the same time. Since it is assumed that workers will be working with gloves on in these facilities, it is considered effective in preventing infection to sterilize hands in a short period of time while wearing gloves, and to repeat sterilization when moving or touching objects. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022 / 113943 Summary of the Invention [Problem to be solved by the invention]

[0006] Even though UVC1 is less harmful to the human body than UVC2, there is a limit to the allowable amount of exposure to the human body. Therefore, it is necessary to perform effective and stable sterilization with the minimum amount of exposure. In the application of ultraviolet irradiation to the human body, the sterilization effect decreases due to the positional or temporal variation in the amount of ultraviolet exposure. For example, if there is a part where the irradiation intensity is too strong, it is necessary to ensure that the amount of exposure to the human body in that part does not exceed the allowable limit. Therefore, a problem occurs in that the amount of exposure required for sterilization is insufficient in other parts. In conventional sterilization devices using existing deep ultraviolet (UVC) light emitting sources, the uniformity of the irradiation intensity is generally increased by increasing the distance from the light source to the object to be sterilized. However, with this method, if the object to be irradiated (the object to be irradiated) is three-dimensional, a shadow is likely to be created, and if a shadow is created, the difference in the amount of exposure becomes large. On the other hand, in an ultraviolet irradiation device using a surface light source as disclosed in Patent Document 1, ultraviolet rays are irradiated close to the object to be irradiated from a light emitting surface with an area equal to or larger than the size of the object to be irradiated. In an ultraviolet irradiation device using a surface light source, light is emitted from various positions on the light source surface, so that light reaches the surface of the irradiation target from various directions. Irradiation with diffused light can suppress the occurrence of shadows, allowing for uniform and stable ultraviolet irradiation of the irradiation target.

[0007] However, even in the ultraviolet irradiation device using the above-mentioned surface light source, there is a problem that the uniformity of the ultraviolet illuminance decreases depending on the position of the irradiation object. The cause of this is a decrease in the peripheral light amount. In other words, when an irradiation object is located at a position corresponding to both ends of the surface light source, the direction of the light irradiated to the irradiation object is limited and the light amount decreases. A technology to improve this is needed.

[0008] Therefore, the present invention provides an ultraviolet irradiation device which solves the above-mentioned problems, has a broad bactericidal effect against many viruses and bacteria, and has little effect on the human body, and is safe and has a high bactericidal effect. The present invention also provides a technique for suppressing changes in the light emission intensity of a light source over time and fluctuations in the amount of irradiation due to the environment, etc. [Means for solving the problem]

[0009] In order to solve the above problems, the ultraviolet irradiation apparatus of the present invention comprises an ultraviolet light source device that utilizes gas discharge, in which a plurality of discharge tubes, each having an ultraviolet-emitting phosphor layer inside, are arranged in parallel along an ultraviolet irradiation surface, and a common electrode pair is arranged facing the back side of the ultraviolet irradiation surface and extending in the longitudinal direction of each discharge tube, separating them by a discharge gap, and the plurality of discharge tubes are arranged so that the spacing between adjacent tubes is narrower at both ends than at the center.

[0010] The ultraviolet irradiation device of the present invention is preferably based on an ultraviolet irradiation device of a surface light source having a wide emission spectrum (UVC1) in a wavelength range of at least 210 to 250 nm as disclosed in the above-mentioned Patent Document 1, and is characterized in that the ultraviolet light-emitting gas discharge tubes constituting the ultraviolet irradiation device are arranged such that the interval (pitch) between adjacent tubes is narrower at both ends than at the center. Also, auxiliary electrodes are provided at positions corresponding to the vicinity of both ends in the longitudinal direction of each ultraviolet light-emitting gas discharge tube.

[0011] If necessary, an optical filter that substantially blocks transmission of ultraviolet light in the wavelength range of 240 nm or more in the phosphor emission spectrum is arranged opposite the light emitting surface (arrangement surface consisting of the light emitting surfaces of the arranged gas discharge tubes). Furthermore, an ultraviolet irradiation device is provided in which the thickness of the glass tube constituting the gas discharge tube envelope is adjusted to limit the radiation of the short wavelength side of the ultraviolet light generated inside, while the optical filter arranged opposite the light emitting surface limits the radiation of the long wavelength side. With this configuration, it becomes possible to design a device that covers a wide wavelength range of 200 nm to 250 nm, which is expected to be most effective for sterilization, and prevents the radiation of ultraviolet light in the vacuum ultraviolet range and ultraviolet light in the deep ultraviolet range with a wavelength of 240 nm or more, which are harmful to the human body. Effect of the Invention

[0012] According to the ultraviolet irradiation device of the present invention, a surface light source with a larger area can be obtained by improving the reduction in the peripheral light amount. Also, by improving the reduction in the peripheral light amount of the surface light source, uniform and stable ultraviolet irradiation can be performed. Therefore, it is possible to obtain a sterilization effect that is safe and has a high sterilization effect with little effect on the human body. [Brief description of the drawings]

[0013] [Figure 1A] 1 is a cross-sectional view showing a cross section of a gas discharge tube, which is a constituent unit of a gas discharge array, and a cross section of an electrode structure in a surface-emitting ultraviolet light source device, which is an example of a light source of an ultraviolet irradiation apparatus according to the present invention. [Figure 1B] 1B is a perspective view showing an example of a surface-emitting ultraviolet light source device in which a plurality of gas discharge tubes shown in FIG. 1A are arranged in parallel on an electrode structure. [Figure 1C] 1C is an explanatory diagram showing the electrode arrangement and driving principle of the electrode structure in the surface-emitting ultraviolet light source device shown in FIG. 1B. [Figure 1D] 1B is a cross-sectional view showing a configuration example of an electrode structure different from that in FIG. 1A. [Diagram 2] FIG. 2 is a diagram showing the emission spectrum of a phosphor formed in an ultraviolet light-emitting gas discharge tube. [Figure 3A] FIG. 1 is a plan view showing an example of a surface-emitting ultraviolet light source device having an array of conventional ultraviolet light-emitting gas discharge tubes as a comparative example. [Figure 3B] 3B is a side view of the surface-emitting ultraviolet light source device shown in FIG. 3A as viewed from an extension line in the longitudinal direction of a gas discharge tube. [Figure 3C] 3C is an explanatory diagram showing the distribution of irradiation intensity from a gas discharge tube on the irradiation surface of the surface-emitting ultraviolet light source device shown in FIGS. 3A and 3B. FIG. [Figure 3D] FIG. 3D is an explanatory diagram showing the overall distribution of the irradiation intensity shown in FIG. 3C. [Figure 3E] 3B is a side view of the surface-emitting ultraviolet light source device shown in FIG. 3A, viewed from a direction perpendicular to the longitudinal direction of the gas discharge tube. [Figure 4A]3B is a plan view corresponding to FIG. 3A of the surface-emitting ultraviolet light source device according to the first embodiment. FIG. [Figure 4B] 3B is a side view of the surface-emitting ultraviolet light source device according to the first embodiment, the side view corresponding to FIG. 3B. [Figure 4C] 3D is an explanatory diagram of an illuminance distribution of the surface-emitting ultraviolet light source device according to the first embodiment, corresponding to FIG. 3C. [Figure 4D] 3D of the surface-emitting ultraviolet light source device according to the first embodiment. FIG. [Diagram 5] 11A and 11B are explanatory diagrams showing the configuration of a surface-emitting ultraviolet light source device according to a second embodiment and a discharge model thereof. [Figure 6] 10 is a schematic diagram showing a configuration of a surface-emitting ultraviolet light source device according to a third embodiment. FIG. [Figure 7] FIG. 11 is a schematic diagram showing a modified example of the third embodiment. [Figure 8A] 7 is a cross-sectional view of the gas discharge tube and a cross-sectional view of the electrode structure shown in FIG. 6. [Figure 8B] 8 is a cross-sectional view of the gas discharge tube and a cross-sectional view of an electrode structure shown in FIG. 7. [Figure 9] 1 is a block diagram showing a configuration of an inverter circuit for driving a surface-emitting ultraviolet light source device according to an embodiment of the present invention. [Figure 10] 10 is a diagram showing an example in which the emission luminance of the surface-emitting ultraviolet light source device is changed by adjusting the duty ratio of the inverter circuit shown in FIG. [Figure 11] 10 is a time chart illustrating the inverter circuit shown in FIG. 9 and drive voltage waveform control by an external control signal. [Figure 12] 5 is a time chart showing lighting control of an inverter circuit in response to a decrease in the light emission output of a surface-emitting ultraviolet light source device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in more detail below with reference to the drawings. Note that the following description is illustrative in all respects and should not be construed as limiting the present invention. Note that, in order to simplify the description, the same components are given the same reference numerals. First, the technology underlying the present invention will be described. [Basic structure and driving principle of surface-emitting ultraviolet light source device] The ultraviolet irradiation device described below as one embodiment of the present invention is one in which a gas discharge array type surface-emitting ultraviolet light source device is applied as a light source. Figs. 1A to 1D are schematic diagrams showing a surface-emitting ultraviolet light source device relating to the ultraviolet irradiation device of this embodiment. The surface-emitting ultraviolet light source device 10 shown in Figs. 1A to 1D has a structure in which a plurality of gas discharge tubes 1 are arranged on an electrode structure 15 having an insulating substrate 13, an electrode pair 14, and an insulating layer 11. Except for the auxiliary electrodes provided near both ends of each gas discharge tube 1, the configuration is basically the same as that disclosed in the above Patent Document 1.

[0015] (Gas Discharge Tube) FIG. 1A is a cross-sectional view of a gas discharge tube 1 as an ultraviolet light-emitting element that is a constituent unit of a gas discharge array. The gas discharge tube 1 is mainly composed of a glass tube 2 having a flat elliptical cross section with a major axis of about 2 mm and a minor axis of about 1 mm, and a deep ultraviolet ultraviolet phosphor layer 3 is provided on the inner wall surface of the tube. The deep ultraviolet phosphor layer 3 extends along the major axis direction of the inner wall having an elliptical cross section, and is formed on one of two opposing surfaces. The side on which the deep ultraviolet phosphor layer 3 is formed is called the rear side or back side of the gas discharge tube 1, and the opposite side is called the irradiation side or front side of the gas discharge tube 1. The gas discharge tube 1 has a structure in which a discharge gas 4 containing a rare gas such as a mixed gas of neon (Ne) and xenon (Xe), helium (He) and xenon (Xe), or argon (Ar) and xenon (Xe), which emits vacuum ultraviolet light, is sealed inside the glass tube 2, and both ends are sealed.

[0016] As the material of the glass tube 2, if the objective is to generate only deep ultraviolet rays (UVC) as a light source device of ultraviolet light, it is preferable to use borosilicate glass with an improved ultraviolet transmittance by adding a small amount of fluorine or the like, if the objective is to generate vacuum ultraviolet rays (VUV) and UVC simultaneously. Specifically, ultraviolet-transmitting glass having a borosilicate composition is preferable. Of course, quartz glass, which is expensive but has excellent ultraviolet transmittance, may be used. By thinning the wall thickness by drawing (redrawing) the borosilicate glass tube to a wall thickness of 200 μm or less, preferably to about 100 μm, a glass tube 2 that transmits with a transmittance of 80% or more from the vacuum ultraviolet region of about 140 nm to the deep ultraviolet region of about 280 nm can be obtained. However, if the wall thickness is 50 μm or less, it is not preferable because the strength is insufficient and there is a risk of breakage.

[0017] For example, a phosphor made of lutetium and scandium phosphate having an emission spectrum peak at a wavelength of about 228 nm can be used as the deep ultraviolet phosphor layer 3 that generates deep ultraviolet rays. The emission spectrum of this phosphor has a continuous wide wavelength range from 200 nm to 260 nm with a peak at 228 nm, and emits effective deep ultraviolet light at least in the range of 210 nm to 250 nm.

[0018] [Surface-emitting ultraviolet light source device] As shown in FIG. 1B, a gas discharge array type surface-emitting ultraviolet light source device 10 has a plurality of gas discharge tubes 1 as ultraviolet light emitting elements arranged in parallel on an electrode structure 15 having electrode pairs 14 (pairs of electrodes 14X and 14Y). The electrode structure 15 has a flexible insulating substrate 13 made of, for example, polyimide resin as a base, and has electrode pairs 14 on the lower surface of the insulating substrate 13. A heat-resistant insulating layer 11 is provided further below the electrode pairs 14. The electrode structure 15 supports the arrangement of the gas discharge tubes 1 via an adhesive layer 12 on its upper surface. The side on which the gas discharge tubes 1 are arranged via the adhesive layer 12 is also called the front surface of the insulating substrate 13 and the electrode structure 15 including it, and the opposite side is also called the back surface. As another configuration of the electrode structure 15, for example, as shown in FIG. 1D, the above-mentioned electrode pair 14 may be formed on the upper surface (front surface) of a flexible insulating substrate 13 made of polyimide resin, and a heat-resistant thin film-like insulating layer 11 (thickness: about 0.6 mm to 0.8 mm) may be provided thereon. Furthermore, an adhesive layer 12 (thickness: about several tens of μm) made of an adhesive with good thermal conductivity such as silicone resin may be provided thereon to support an array of a plurality of gas discharge tubes in a detachable adhesive contact state. Note that the adhesive layer 12 on the electrode structure 15 does not need to be provided on the entire upper surface side of the insulating layer 11, but may be provided in spots at positions that support the gas discharge tubes 1 in both the width direction and the length direction of the gas discharge tubes 1. The electrode pair 14 faces the back side of each gas discharge tube 1 and is composed of a pair of electrodes, namely, electrodes 14X and 14Y, which extend on both sides of an electrode slit G (electrode gap) as shown in FIG. 1C.

[0019] If a flexible insulating film made of polyimide resin is used as the insulating substrate 13 that is the base of the electrode structure 15, and the gas discharge tubes 1 are arranged with a gap between adjacent ones, a flexible surface-emitting ultraviolet light source device 10 that can be bent in the arrangement direction of the gas discharge tubes 1 can be obtained. In addition, the electrode structure 15 may be formed with an air hole or an air slit that penetrates at least the insulating substrate 13 and the electrode pair 14. If a part of the back side of each gas discharge tube 1 is directly exposed to the formed air hole or air slit, or if a part of the back side of each gas discharge tube 1 is indirectly exposed to the formed air hole or air slit through the insulating layer 11 shown in FIG. 1D or the adhesive layer 12 shown in FIG. 1A and FIG. 1D, it is convenient for the heat dissipation of each gas discharge tube 1. That is, the heat generated in each gas discharge tube 1 can be efficiently dissipated.

[0020] The electrodes 14X and 14Y may be directly formed on the insulating substrate 13 by printing a conductive ink such as silver paste, or may be formed by gluing or bonding a pre-shaped metal conductor foil such as copper or aluminum. In FIG. 1D, when the insulating layer 11 supporting each gas discharge tube 1 is made of an insulating film made of a fluorine-based transparent resin such as Teflon (registered trademark), it is preferable to use a material with high light reflectance for the electrodes 14X and 14Y, and in this sense, it is particularly effective to use aluminum foil. When a material with high light reflectance is used for the electrodes 14X and 14Y, the electrode slit G may become a window opening on the back side, and ultraviolet light may escape from the window to the back side. Therefore, it is preferable to cover the electrode slit G with an insulating material with a light reflectance equivalent to that of the electrode material, for example, a light reflective tape.

[0021] [Drive principle] 1C is an explanatory diagram showing the electrode arrangement and driving principle of the electrode structure in the surface-emitting ultraviolet light source device shown in FIG. 1B. An inverter circuit 17 for driving the surface-emitting ultraviolet light source device applies a sine-wave alternating driving voltage having a peak-to-peak voltage (PP voltage) of 1000 to 2000 V and a frequency of 30 to 40 KHz to the electrodes 14X and 14Y constituting the electrode pair 14, for example. In the process of increasing the alternating driving voltage applied between the electrodes 14X and 14Y by the inverter circuit 17, an initial discharge occurs in the discharge gap in the gas discharge tube 1 at a position approximately corresponding to the electrode slit G between the electrodes 14X and 14Y. As the alternating driving voltage increases, the discharge expands from the initial discharge in the discharge gap to a position in the longitudinal direction corresponding to the electrodes 14X and 14Y of the gas discharge tube 1.

[0022] By applying an alternating drive voltage to the electrodes 14X and 14Y, such discharges are generated in the region inside the gas discharge tube 1, alternating and repeating while alternating polarity. The gas to be filled in the gas discharge tube may be a mixture of neon (Ne) and xenon (Xe), or a mixture of other rare gases, such as helium (He) and xenon (Xe), or argon (Ar) and xenon (Xe). In the case of a mixture of neon (Ne) and xenon (Xe), a discharge accompanied by the emission of vacuum ultraviolet rays (VUV) of 143 nm and 172 nm occurs at a lower discharge voltage than the other mixtures of neon (Ne) and xenon (Xe). The excitation of this VUV causes the deep ultraviolet phosphor layer 3 to emit deep ultraviolet rays (UVC1) with a central wavelength of 228 nm. In order to stabilize the composition of the deep ultraviolet phosphor layer 3, nitrogen (N) may be further added to each of the mixtures.

[0023] In this way, the gas discharge tubes 1 are completed and function as discharge tubes only when they are arranged on the electrode structure 15 and electrically connected to the electrode pairs 14. For this reason, the gas discharge tubes 1 must be arranged on the electrode structure 15 in a state of contact so that the electrical characteristics of each gas discharge tube 1 with respect to the electrode pairs 14 are uniform in the longitudinal direction. In addition, since the gas discharge tubes 1 are supported on the electrode structure 15 via the adhesive layer 12 in an adhesive state that allows them to be detached from the insulating substrate 13, even if any of the gas discharge tubes 1 develops a crack, flaw, or break, the gas discharge tubes 1 can be easily replaced in units of the gas discharge tubes 1. In the surface-emitting ultraviolet light source device 10 that functions as a discharge tube only when the gas discharge tubes 1 are well arranged on the electrode structure 15, this configuration in which the gas discharge tubes 1 are supported on the electrode structure 15 via the adhesive layer 12 is extremely effective in terms of improving yield.

[0024] [Embodiment 1 of the surface-emitting ultraviolet light source device] A first embodiment of the present invention will be described in detail below with reference to the drawings. 2 is a diagram showing an emission spectrum from the deep ultraviolet phosphor layer 3 of the gas discharge tube array type surface-emitting ultraviolet light source device 10 shown in FIGS. 1A to 1D. The vertical axis indicates the number of emitted photons (photocount) as emission intensity, and the horizontal axis indicates wavelength. As is clear from this emission spectrum, it is found that an emission intensity of 70% or more of the peak wavelength of 228 nm can be obtained in the continuous wavelength range of 215 to 245 nm. The diagram showing the emission spectrum in FIG. 2 is the same as that in Patent Document 1 mentioned above.

[0025] 3A to 3D are diagrams for explaining the relationship between the arrangement of the gas discharge tubes 1 at equal intervals in the prior art and the irradiation intensity as a comparative example. As shown in FIG. 3A, the gas discharge tubes 1 constituting the surface-emitting ultraviolet light source device 10 are evenly arranged at equal intervals of 12.5 mm on the electrode structure 15. The configuration of the surface-emitting ultraviolet light source device 10, including the configuration of the electrode structure 15, is the same as that shown in FIG. 1A to 1D. FIG. 3B is a side view of the surface-emitting ultraviolet light source device shown in FIG. 3A as seen from an extension line in the longitudinal direction of the gas discharge tubes. FIG. 3C shows the distribution of the irradiation intensity of the light source device 10 arranged as shown in FIG. 3B on an irradiation surface at a distance of 25 mm from the bottom surface of each gas discharge tube 1. The distribution of the irradiation intensity of each gas discharge tube 1 shown in FIG. 3C is obtained by measuring while moving an illuminometer along the arrangement direction of the irradiation surface with only one gas discharge tube 1 emitting light and the other gas discharge tubes 1 turned off. Moreover, Fig. 3D shows the overall combined illuminance intensity of the surface-emitting ultraviolet light source device 10, which is a combination of the illuminance distributions from each gas discharge tube 1 shown in Fig. 3C. Note that the characteristics on the right end side of the surface-emitting ultraviolet light source device 10 are the same as those in Fig. 3, and therefore are omitted in Figs. 3C and 3D.

[0026] As is clear from Fig. 3D, at both ends of the arrangement direction perpendicular to the longitudinal direction of each gas discharge tube in Fig. 3A and along the irradiation surface, i.e., at both ends of the arrangement direction of the use area used as an ultraviolet irradiation device, the amount of light combined is reduced, and the combined illuminance is reduced. Such a reduction in combined illuminance occurs similarly at both ends of the longitudinal direction (tube length direction) of each gas discharge tube, as shown in Fig. 3E. In this way, the uniformity of the illuminance of the ultraviolet irradiation device is reduced at both ends in both directions, both in the arrangement width direction and the tube length direction of each gas discharge tube 1. This causes a problem that the irradiation target cannot be uniformly and stably irradiated with ultraviolet rays.

[0027] As shown in Figures 3A and 3B, if the irradiation position is at a distance of 25 mm, which is twice the arrangement pitch of the gas discharge tubes 1 of 12.5 mm, the peaks of the illuminance distribution of each gas discharge tube 1 overlap as shown in Figure 3C. When the illuminance distributions are combined as shown in Figure 3D, the peaks of the illuminance distribution of each gas discharge tube 1 become invisible, resulting in a smooth illuminance distribution. On the other hand, at a distance of 250 mm, which is 20 times the arrangement pitch of 12.5 mm, the peaks of the illuminance distribution of each gas discharge tube 1 become lower and the base becomes wider, and the spread of the illuminance distribution reaches ±500 mm. Considering a surface-emitting ultraviolet light source device 10 with 21 gas discharge tubes 1 arranged at an arrangement pitch of 12.5 mm and an arrangement width of 250 mm (12.5 mm x 20), if the irradiation position is at a distance of 20 times the arrangement pitch (250 mm), the irradiation range will exceed 1 m, and if it becomes larger than this, it cannot be said to be an ultraviolet light source device for a specific object to be irradiated. Therefore, in the surface-emitting ultraviolet light source device 10 of this embodiment, which is intended to irradiate a specific object with deep ultraviolet light, it is desirable to set the irradiation distance of each gas discharge tube 1 relative to the adjacent pitch in the range of 2 to 20 times so as to achieve both uniformity of irradiation and irradiation range.

[0028] When inactivating viruses and various bacteria in a fluid such as water or air in a short time or in one pass, it is preferable that the arrangement pitch of the gas discharge tubes 1 is relatively narrow, about a few mm, for example, 2.5 mm. In such a case, for example, 10 mW / cm 2 When irradiated for 2 seconds at an emission intensity of 1.0 mJ, the amount of irradiation is 20 mJ. On the other hand, in the case of sterilization of the human body such as hands and fingers, in order to ensure sufficient safety, the pitch of the gas discharge tubes 1 can be widened to reduce the emission intensity per unit area of ​​the light source and widen the irradiation area without increasing the cost of the surface-emitting ultraviolet light source device. In such a case, for example, the arrangement pitch of the gas discharge tubes 1 can be widened five-fold to 12.5 mm, and the amount of irradiation can be increased to 2.0 mW / cm. 2 Irradiation for 10 seconds at an emission intensity of 10 mJ results in an irradiation dose of 20 mJ.

[0029] 4A to 4D are schematic diagrams showing a first aspect (first embodiment) of the ultraviolet irradiation device according to this embodiment. FIG. 4A is a plan view of the surface-emitting ultraviolet light source device 100, FIG. 4B is a side view, FIG. 4C is a diagram showing the illuminance distribution in the arrangement direction of the gas discharge tubes 1, and FIG. 4D shows the composite illuminance. The ultraviolet irradiation device shown in FIG. 4 has the arrangement (pitch) of the gas discharge tubes 1 changed from that in FIG. 3A to FIG. 3D, and other detailed configurations are the same as those in FIG. 3A to FIG. 3D. That is, in the ultraviolet irradiation device having the surface-emitting ultraviolet light source device shown in FIG. 4A to FIG. 4D, the gas discharge tubes 1 are arranged on the electrode structure 150 such that the intervals (D1 to D4) between the adjacent gas discharge tubes 1 at both ends in the arrangement direction of the gas discharge tubes 1 become successively narrower (D3, D2, D1) from the interval (D4) at the center toward both ends. As in FIG. 3B, the right end side of the surface-emitting ultraviolet light source device 100 is not shown in FIG. 4B because it is formed by folding back the left end side.

[0030] In the first embodiment, the interval D4 is set to 12.5 mm at the pitch of the central portion as a reference, as in FIG. 3. From there, the intervals are gradually reduced at intervals of 1.5 mm to 2 mm toward the end (the left end in FIG. 4A) until the interval D1=7.5 mm. In the first embodiment, the interval D2 is set to 9 mm, and the interval D3 is set to 11 mm. Note that each pitch in the central portion to the right of the interval D4 in FIG. 4A is set to 12.5 mm. In FIG. 4D, the solid line indicates the composite illuminance of each gas discharge tube 1 according to the configuration of the first embodiment shown in FIGS. 4A to 4C, and the dashed line indicates the composite illuminance similar to that in FIG. 3D according to the configuration of the comparative example shown in FIGS. 3A to 3C.

[0031] According to this embodiment, the combined illuminance of the comparative example shown by the dashed line is 30% lower at the use end (left use end) compared to that of the center, whereas the combined illuminance of the first embodiment shown by the solid line is suppressed to a drop of 10% at the same position. As is clear from Fig. 4D, according to the first embodiment, the amount of combined light is reinforced toward the end of the use area in the arrangement direction of the gas discharge tubes 1 compared to the comparative example, and the drop in illuminance is suppressed. Therefore, it is possible to perform more uniform and stable ultraviolet irradiation on irradiation objects including human bodies such as hands than in the comparative example.

[0032] In the surface-emitting ultraviolet light source device 10 shown in Figs. 4A to 4D, the intervals between the gas discharge tubes 1 at the ends in the arrangement direction were determined as follows. Although this is a surface-emitting ultraviolet light source device in which the gas discharge tubes 1 are arranged at an equal pitch as in Figs. 3A and 3B, the number of gas discharge tubes 1 was 22, the arrangement pitch was 10 mm, and the distance to the irradiation surface (irradiation distance) was 50 mm. Based on actual measurements, the composite illuminance at the ends and center of the use area in the arrangement direction was obtained under the conditions. According to the results obtained, the composite illuminance at the ends of the use area was reduced to about 60% to 70% of the composite illuminance at the center. For this reason, in the example of the surface-emitting ultraviolet light source device 10 shown in Figs. 4A and 4B, the interval D1 at the very end of the use area in the arrangement width direction was set to 60% of the reference pitch at the center, that is, 12.5 mm x 0.6 (60%) = 7.5 mm. For the intervals D2, D3, and D4 following the interval D1, the intervals were gradually increased (increased in intervals of 1.5 mm to 2 mm) until the interval D4 reached 12.5 mm, at which point the interval in the center was set to a constant pitch (reference pitch).

[0033] The pitch arrangements shown in Figures 4A to 4D, including the method of determining the pitch arrangements, the minimum interval between the ends, the reference pitch, and the values ​​of the irradiation distance, are examples and are not limited to these. The number of gas discharge tubes 1 may be determined appropriately depending on the size and use of the ultraviolet irradiation device required. In addition, whether or not the same pitch is repeated multiple times in the process of changing from the minimum pitch to the reference pitch may be determined appropriately depending on the size and use of the ultraviolet irradiation device. The number of gas discharge tubes 1 used may be set to provide the greatest effect.

[0034] In applications for sterilizing the surfaces of objects, etc., if a wider irradiation area is desired, the arrangement pitch of the gas discharge tubes 1 can be widened and the irradiation time can be extended by the amount of the lowered emission intensity. As described above, the typical arrangement pitch applied to inactivating viruses and various bacteria using fluids such as water and air as the irradiated object is 2.5 mm to 3 mm. In contrast, in the first embodiment, the arrangement pitch is set to 12.5 mm, which is five times larger, as the reference pitch, and the irradiation area in the arrangement direction is also expanded five times. In sterilization and disinfection, for example, an ultraviolet (UV) irradiation dose of about 10 mJ is required for bacteria and viruses when the ultraviolet wavelength is 260 nm. 2 mW / cm 2 The emission intensity per area of ​​the surface-emitting ultraviolet light source device 10 with an array pitch of 2.5 mm is 10 mW / cm. 2 Therefore, if the pitch is expanded five times, the luminous intensity per area will be 2 mW / cm 2 It becomes about that.

[0035] [Embodiment 2 of surface-emitting ultraviolet light source device] Next, a second embodiment of the present invention will be described. FIG. 5 shows the configuration of a surface-emitting ultraviolet light source device according to the second embodiment, and is an explanatory diagram for explaining a discharge model in the second embodiment. As shown in FIG. 5, the surface-emitting ultraviolet light source device 101 in the ultraviolet irradiation device of the second embodiment is a light source device 10 shown in FIG. 3E, in which a pair of auxiliary electrodes 18X, 18Y having a thickness of about 10 μm are provided on an electrode structure 151 corresponding to both ends in the tube length direction of the gas discharge tube 1. The configuration of the electrode structure 15 is the same as that of FIG. 1D. Note that FIG. 5 is shown upside down compared to FIG. 3E. When the object to be irradiated is irradiated from above as shown in FIG. 3E, the surface-emitting ultraviolet light source device 101 is arranged upside down compared to FIG. 5. As with the electrodes 14X and FIG. 14Y, an alternating drive voltage is applied to the pair of auxiliary electrodes 18X, 18Y by an inverter circuit 17. The other points are the same as those of the light source device 10 shown in Fig. 3E and the electrode structure 15 shown in Fig. 1D, and the same components are denoted with the same reference numerals. Note that the adhesive layer 12 (see Fig. 1D) that supports the gas discharge tube 1 on the electrode structure 15 is not shown in Fig. 5.

[0036] With one electrode 14X and auxiliary electrode 18X grounded, inverter circuit 17 applies an alternating drive voltage to the other electrode 14Y and auxiliary electrode 18Y. When the voltage in the rising process of the alternating drive voltage exceeds the discharge start voltage between electrodes 14X and 14Y at timing t1 shown in Fig. 5, a discharge (trigger discharge) occurs in the discharge space inside gas discharge tube 1.

[0037] This trigger discharge supplies a large amount of space charge to the nearby gas space, causing a so-called pilot effect, and as the AC driving voltage rises, the discharge expands from the center of the gas discharge tube 1 corresponding to the electrode slit G toward both ends, transitioning to a so-called long-distance discharge. At the same time, charges of the opposite polarity to the applied voltage (electrons (-) and cations (+)) accumulate as wall charges on the inner wall surface of the gas discharge tube 1 corresponding to the position where the initial trigger discharge occurred. The electric field caused by this wall charge cancels out the electric field of the applied voltage, and the discharge in the trigger discharge area stops.

[0038] Timings t1 to t4 in Fig. 5 show the discharge and wall charge accumulation state corresponding to each timing with the rise of the alternating drive voltage. From Fig. 5, it can be seen that the discharge generated in the center of each gas discharge tube 1 at timing t1 expands toward both ends of each gas discharge tube 1 while accumulating wall charge as the applied voltage rises to timings t2, t3, and t4.

[0039] According to the second embodiment, by providing a pair of auxiliary electrodes 18X, 18Y at both ends of each gas discharge tube 1, the electric field caused by the applied alternating drive voltage is stronger in the discharge space at the positions corresponding to the auxiliary electrodes 18X, 18Y than at other positions. Accordingly, the discharge is stronger at the positions corresponding to the auxiliary electrodes 18X, 18Y, and the amount of light emitted from the gas discharge tube 1 also increases at the same positions. This makes it possible to reduce the decrease in illuminance at both ends in the tube length direction as shown in Fig. 3E of the comparative example, and makes it possible to perform more uniform and stable ultraviolet irradiation on the irradiation target.

[0040] [Embodiment 3 of the surface-emitting ultraviolet light source device] A third embodiment of the present invention will be described. Fig. 6 is a schematic diagram showing an ultraviolet irradiation device according to the third embodiment. The third embodiment combines the configuration of the interval (pitch) between adjacent gas discharge tubes in the first embodiment and the configuration of providing an auxiliary electrode in the second embodiment. Furthermore, the surface-emitting ultraviolet light source device 102 in the third embodiment preferably uses an electrode structure 152 with a through slit. The same components as those in the first and second embodiments are denoted by the same reference numerals.

[0041] 6, the auxiliary electrodes 18X, 18Y are formed at both ends in the tube length direction of the gas discharge tube 1, and have the same length as the electrodes 14X, 14Y in the arrangement direction of the gas discharge tube 1. The length of the auxiliary electrodes 18X, 18Y in the tube length direction of the gas discharge tube 1 is provided to an extent necessary to improve the reduction in illuminance at both ends in the tube length direction.

[0042] Moreover, in the electrode structure 152 provided in the surface-emitting ultraviolet light source device 102, a plurality of through slits 61 penetrating the insulating substrate 13 and the electrodes 14X, 14Y are formed at substantially equal intervals and substantially parallel to the electrode slits G for the discharge gap. In such an electrode structure 152 with through slits, the rear surfaces (the surface opposite to the ultraviolet radiation direction in FIG. 1A: the rear surface) of the arranged gas discharge tubes 1 are partially exposed to the rear surface side of the electrode structure 152 through the through slits 61, and ventilation holes are formed by the through slits 61 in the regions between the adjacent gas discharge tubes 1. Therefore, for example, by creating an air flow through the ventilation holes using a blower fan not shown in FIG. 6, the gas discharge tubes 1 constituting the surface-emitting ultraviolet light source device 102 can be effectively cooled from their outer circumferential surfaces.

[0043] The through slit 61 provided in the electrode structure 152 is not limited to the through slit having a rectangular shape in plan view shown in FIG. 6, but may be, for example, a configuration in which a large number of small holes (through holes) are distributed. In such an embodiment in which a large number of through holes are provided, similar to the through slit 61 described above, an air hole is formed in the region between the adjacent gas discharge tubes 1, and the surface-emitting ultraviolet light source device 102 can be effectively cooled from the outer circumferential surface of the gas discharge tube. Furthermore, instead of the through slit 61 shown in FIG. 6, a plurality of grooves may be formed on the front surface of the electrode structure 152. Each groove extends in a direction transverse to the gas discharge tube 1 and has, for example, a V-shaped cross section. The adhesive layer 12 is provided in a portion other than the plurality of grooves formed in the electrode structure 152. The plurality of grooves do not penetrate the insulating substrate 13, but provide a space through which cooling air passes between the back side of the gas discharge tube 1 and the electrode structure 152. This allows the surface-emitting ultraviolet light source device 102 to be effectively cooled from the outer circumferential surface of the gas discharge tube.

[0044] According to the third embodiment, the effects of the first embodiment and the second embodiment are both achieved. That is, according to the third embodiment, the gas discharge tubes 1 are arranged such that the intervals (D1 to D4) between adjacent tubes are narrower at both ends (D1) than at the center (D4). Therefore, compared to the comparative example, the combined illuminance is reinforced toward the ends in the arrangement direction of the gas discharge tubes 1, and the decrease in illuminance at both ends in the arrangement direction is suppressed. Therefore, uniform and stable ultraviolet irradiation can be performed on the irradiation object including the human body such as the hand. In addition, the discharge in the gas discharge tube 1 becomes stronger at the positions corresponding to the auxiliary electrodes 18X and 18Y (both ends in the longitudinal direction of the gas discharge tube 1), and the amount of light emitted from the gas discharge tube 1 also increases at the same positions. This can reduce the problem of the decrease in illuminance that occurred at both ends in the longitudinal direction of the tube in the past, and it is possible to perform more uniform ultraviolet irradiation on the irradiation object compared to the comparative example. Furthermore, if the electrode structure 152 is provided with the through slits 61, the surface-emitting ultraviolet light source device 102 can be effectively cooled.

[0045] In Fig. 6, an electrode structure 152 with a plurality of through slits 61 penetrating the insulating substrate 13 and the electrodes 14X and 14Y is used as the surface-emitting ultraviolet light source device 102, but the through slits 61 do not necessarily have to be provided. The surface-emitting ultraviolet light source device 102 in this case is shown in Fig. 7. The only difference between Fig. 7 and Fig. 6 is the presence or absence of the through slits 61, and the same components in both drawings are given the same reference numerals. For example, when the surface-emitting ultraviolet light source device 102 is used in an open space with good ventilation with respect to an irradiation target, or in other cases where the surface-emitting ultraviolet light source device 102 is used in an environment where heat generation from the surface-emitting ultraviolet light source device 102 is not a problem, the through slits 61 do not necessarily have to be provided.

[0046] 8A is a ZZ cross-sectional view of FIG. 6 or FIG. 7, and the same components as those of FIG. 6 or FIG. 7 are given the same reference numerals. In the electrode structure 152 in FIG. 8A, an electrode 14Y is formed on an insulating substrate 13, and an auxiliary electrode 18Y is further provided via an insulating layer 11. A gas discharge tube 1 is disposed on the auxiliary electrode 18Y via an adhesive layer 12 that also serves as an insulator. In FIG. 8B, an electrode 14Y is formed on the back side (opposite the gas discharge tube 1) of the insulating substrate 13, and an auxiliary electrode 18Y is provided on the front side (the gas discharge tube 1 side) of the insulating substrate 13. As in FIG. 8A, a gas discharge tube 1 is disposed on the auxiliary electrode 18Y via an adhesive layer 12 that also serves as an insulator.

[0047] [Light source driving inverter circuit] An inverter circuit for driving the surface-emitting ultraviolet light source device in this embodiment is shown in Fig. 9. As shown in Fig. 9, the inverter circuit 17 has the configuration of an inverter power supply that is connected to the surface-emitting ultraviolet light source device 102 and applies an alternating drive voltage to the electrodes 14X and 14Y. The surface-emitting ultraviolet light source device 102 is connected to a secondary winding L2 of a step-up transformer 20 of the inverter circuit 17, and its primary winding L1 is connected to switching transistors Tr1 and Tr2 that convert a DC voltage V1 from a DC power supply input into an AC voltage. In addition, like a general inverter circuit, capacitors C, C1, C2, and a resistor R1 are appropriately connected as shown in the figure.

[0048] A drive voltage detection signal VDs and a drive current detection signal IDs are input to the voltage / current detection / determination circuit 21 from the output side of the step-up transformer 20, and the voltage / current detection / determination circuit 21 determines whether or not there is an abnormality in the drive voltage detection signal VDs or the drive current detection signal IDs, and outputs a voltage / current abnormality determination signal to the control circuit 22. Based on the voltage / current abnormality determination signal and the external lighting control signal PON, the control circuit 22 outputs inverter control signals S1 and S2 that control the lighting period (burst period), burst length, and pulse duty (also called duty ratio) to the switch control circuit 23. The on / off control of the switching transistors Tr1 and Tr2 that determine the driving frequency is performed by the inverter control signals S1 and S2 provided from the control circuit 22 to the switch control circuit 23.

[0049] The control circuit 22 as a control unit is realized by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and a flash memory as a storage unit, and a microcomputer and various circuits having input / output ports, etc. The ROM in the control circuit 22 stores, as a data table, the emission intensity vs. lighting time characteristics of the surface-emitting ultraviolet light source device 102, i.e., data (time-dependent change data) that is a numerical value obtained by actually measuring in advance the decrease in the emission output of the light source device 102 over the lighting time.

[0050] The configuration and operation of the light source driving inverter circuit shown in FIG. 9 are described in detail in Japanese Patent Application No. 2017-553745 (Patent No. 6670508) previously filed by the present inventors. Therefore, detailed description of this point will be omitted here. The main difference between the present invention and the prior application is that a lighting time cumulative timer 221 and a light emission intensity vs. lighting time characteristic table 222 are newly provided in the control circuit 22. This point will be described in detail below.

[0051] The lighting time accumulation timer 221 measures the lighting time of the surface-emitting ultraviolet light source device 102 and stores the accumulated time. The light emission intensity vs. lighting time characteristic table 222 stores the time-varying data of the surface-emitting ultraviolet light source device 102 described above. This data indicates the characteristics of the light emission intensity (emission output) versus the lighting time. The control circuit 22 controls the amount of ultraviolet radiation of the surface-emitting ultraviolet light source device 102 based on the time-varying data so that it is within a predetermined range. The control circuit 22 controls the light emission intensity (amount of ultraviolet radiation) of the surface-emitting ultraviolet light source device 102 to be within a predetermined range by changing the lighting period and pulse duty of the surface-emitting ultraviolet light source device 102 based on the lighting time by the lighting time accumulation timer 221 and the time-varying data stored in the light emission intensity vs. lighting time characteristic table 222.

[0052] 10 is a diagram showing an example of changing the light emission intensity of the surface-emitting ultraviolet light source device 102 by adjusting the duty ratio for driving the surface-emitting ultraviolet light source device 102. For example, the light emission luminance changes in the range of 10 nit to 100 nit by adjusting the duty ratio from 10% to 100%. In other words, by changing the drive duty ratio of the surface-emitting ultraviolet light source device 102, it is possible to increase or decrease the light emission luminance of the light source device 102. Note that nit is a unit of luminance, and is expressed as cd / m 2 (candela per square meter).

[0053] FIG. 11 is a time chart for explaining the drive voltage waveform control by the inverter circuit 17 of FIG. 9 and the external lighting control signal PON. The magnitude of the duty ratio is proportional to the number of lighting pulses (the number of inverter control signals S1, S2) in the burst period Tbc. The control unit 22 changes the duty ratio in the burst period Tbc, that is, changes the number of inverter control signals S1, S2 according to the lighting time, to control the light emission intensity of the surface-emitting ultraviolet light source device 102. The control for changing the number of inverter control signals S1, S2 is performed by changing the length of the on period (the ratio of the on / off period) in one period of the burst control signal BO with respect to the burst period Tbc. Changing the ratio of the on / off period of the burst control signal BO changes the number of inverter control signals S1, S2 generated in one period, and changes the number of on / off of the switching transistors Tr1, Tr2.

[0054] By turning on / off the transistors Tr1 and Tr2, a sinusoidal current flows through the winding (coil) L1 on the primary side of the step-up transformer 20. Accordingly, a stepped-up sinusoidal signal (alternating drive voltage waveform Vout) is generated on the secondary side. During the period when the transistors Tr1 and Tr2 are turned on / off, i.e., the inverter control signals S1 and S2 are stopped, the alternating drive voltage waveform on the secondary side also stops. Therefore, when the burst period Tbc is constant and the burst length becomes shorter (Tb1-1>Tb1-2), the output period of the alternating drive voltage waveform also becomes shorter, and the average luminance of the light source device 102 during the burst period Tbc decreases. In other words, the light emission output of the light source device 102 decreases.

[0055] FIG. 12 is a time chart showing the state in which the light emission output of the surface-emitting ultraviolet light source device 102 decreases with time, and the lighting control according to the change with time. In FIG. 12, the light emission output expected value represents the characteristic of the light emission output of the surface-emitting ultraviolet light source device 102 decreasing with respect to the cumulative lighting time. This light emission output expected value is stored in the light emission intensity vs. lighting time characteristics table 222 as described above. The light emission output expected value is quantified by actually measuring the time-dependent decrease in the light emission output of a plurality of light source devices 102 in advance, predicting (linear prediction or nonlinear prediction) the value until the replacement time Te of the light source device 102 from the average value. Of course, the change in the light emission output from the initial value of the surface-emitting ultraviolet light source device 102 to the replacement time Te may be actually measured, and the actual measurement value may be stored in the light emission intensity vs. lighting time characteristics table 222.

[0056] The control circuit 22 obtains the current light output expected value by referring to the light intensity vs. lighting time characteristic table 222 according to the cumulative lighting time of the surface-emitting ultraviolet light source device 102 measured and stored by the lighting time cumulative timer 221. Based on the thus obtained light output expected value, the length of the on period of the on / off period of the burst control signal BO, that is, the duty ratio, is controlled. In this embodiment, the duty ratio is changed by dividing into three periods in order to simplify the control. The inverter control signals S1 and S2 are generated by applying 60% as the duty ratio R0 of the zeroth period in which the cumulative lighting time is the smallest. Then, when the cumulative lighting time reaches the next stage (first period), 70% is applied as the duty ratio R1 of the first period. When the cumulative lighting time further increases to the next stage (second period), 90% is applied as the duty ratio R2 of the second period to generate the inverter control signals S1 and S2. In this way, the light emission intensity of the light source device 102 is controlled according to the stage of the cumulative lighting time.

[0057] The above control allows the change in the light emission output of the surface-emitting ultraviolet light source device 102 to be within a predetermined range of the ultraviolet irradiation amount. This also makes it possible to set the external lighting control signal PON that specifies the lighting time Ton of the surface-emitting ultraviolet light source device 102 to the same length in all three periods (Ton0b=Ton1b=Ton2b). Note that the period in which the duty is changed may be divided into more periods rather than the above three periods and controlled more finely. This allows the change in the light emission output of the surface-emitting ultraviolet light source device 102 to be within a smaller range.

[0058] According to this embodiment, it is possible to stably irradiate the irradiation target with ultraviolet light within a predetermined range, regardless of aging deterioration of the surface-emitting ultraviolet light source device 102. Therefore, it is possible to obtain a sterilization effect that is safe and highly effective for the human body, particularly hands and fingers.

[0059] [summary] According to the present invention, it is possible to obtain a safe and stable ultraviolet irradiation device that has a disinfecting and sterilizing effect against viruses and bacteria while minimizing the adverse effects of ultraviolet light on the human body.

[0060] The aspects of the present invention include any combination of the above-mentioned aspects. In addition to the above-mentioned embodiment, various modifications of the present invention are possible. These modifications should not be interpreted as not falling within the scope of the present invention. The present invention should include all modifications within the scope of the claims and the equivalent meanings. [Explanation of symbols]

[0061] 1: Gas discharge tube 2: Glass tube 3: UV phosphor layer, deep UV phosphor layer 10, 100, 101, 102: Surface-emitting ultraviolet light source device 11: Insulating layer 12: Adhesive layer 13: Insulating substrate 14: Electrode pair 14X,14Y: Electrode 15,150,151,152: Electrode structure 17: Inverter circuit 18X,18Y: Auxiliary electrode G: Electrode slit 20: step-up transformer, 21: voltage / current detection / determination circuit, 22: control circuit, 23: switch control circuit, 221: lighting time accumulation timer, 222: light emission intensity vs. lighting time characteristic table, 61: through slit, Tr1, Tr2: switching transistor

Claims

1. a surface-emitting ultraviolet light source device in which a plurality of gas discharge tubes each having an ultraviolet phosphor layer are arranged in parallel along an irradiation surface to be irradiated with ultraviolet light from each gas discharge tube, and a common electrode pair is arranged on the opposite side of each gas discharge tube from the irradiation surface, extending in the longitudinal direction of each gas discharge tube with a discharge gap therebetween, In this ultraviolet irradiation device, the gas discharge tubes are arranged such that the distance between adjacent gas discharge tubes is narrower at both ends than at the center in the arrangement direction.

2. 2. The ultraviolet irradiation device according to claim 1, wherein the intervals between adjacent gas discharge tubes are set symmetrically about a center portion in the arrangement direction.

3. 3. The ultraviolet irradiation device according to claim 1, wherein the shortest distance between the adjacent tubes at both ends in the arrangement direction is set to 60% to 70% of the distance at the center.

4. 2. An ultraviolet irradiation device according to claim 1, further comprising a pair of auxiliary electrodes common to each gas discharge tube, the auxiliary electrodes being provided at both longitudinal ends of each gas discharge tube on the side opposite the irradiation surface of the gas discharge tube and closer to the gas discharge tube than the pair of electrodes.

5. 5. The ultraviolet irradiation device according to claim 4, wherein each gas discharge tube is arranged via an adhesive layer on an electrode structure in which the electrode pair is formed on the front surface of an insulating substrate with an electrode slit therebetween, and the auxiliary electrode is formed on the electrode pair via an insulating layer.

6. 5. The ultraviolet irradiation device according to claim 4, wherein each gas discharge tube is arranged via an adhesive layer on an electrode structure in which the electrode pair is formed on the back surface of an insulating substrate with an electrode slit therebetween and the auxiliary electrode is formed on the front surface of the insulating substrate.

7. An electrode structure; a plurality of gas discharge tubes each having an inner surface provided with a phosphor layer emitting ultraviolet light having a wavelength width of at least 210 nm to 250 nm, and filled with a discharge gas, the gas discharge tubes being arranged in parallel on the electrode structure to form a light emitting surface; The electrode structure has an electrode slit across which each of the gas discharge tubes crosses, and a pair of reflective electrodes extending symmetrically in the longitudinal direction of the gas discharge tube on both sides of the electrode slit, The ultraviolet irradiating device includes a plurality of gas discharge tubes arranged such that the intervals between adjacent gas discharge tubes are narrower at both ends than at the center in the arrangement direction.

8. An electrode structure; a phosphor layer that emits ultraviolet light having a wavelength width of at least 210 nm to 250 nm on an inner surface thereof, a discharge gas is sealed inside, and a plurality of gas discharge tubes that are arranged in parallel on the electrode structure to form a light emitting surface; The electrode structure has an electrode slit across which each of the gas discharge tubes crosses, and a pair of reflective electrodes extending symmetrically in the longitudinal direction of the gas discharge tube on both sides of the electrode slit, an ultraviolet irradiation device, comprising: a pair of auxiliary electrodes across which each of said gas discharge tubes crosses, provided on said electrode structure between both longitudinal ends of said gas discharge tube and positions corresponding to said both longitudinal ends of said pair of reflective electrodes.

9. a surface-emitting ultraviolet light source device in which a plurality of gas discharge tubes, each having an ultraviolet phosphor layer therein, are arranged in parallel along an irradiation surface to be irradiated with ultraviolet light from each gas discharge tube, and a common electrode pair is arranged on each gas discharge tube on the opposite side of the irradiation surface, the electrode pair extending in the longitudinal direction of each gas discharge tube with a discharge gap therebetween; an inverter circuit that applies an alternating drive voltage between each electrode of the electrode pair; a control unit that controls the inverter circuit by referring to a data table that stores data on changes over time in the emission intensity of the surface-emitting ultraviolet light source device; The control unit controls the alternating drive voltage applied by the inverter circuit to the electrode pair based on the time-varying data so that the emission intensity of the surface-emitting ultraviolet light source device falls within a predetermined range over time.

10. An electrode structure; a surface-emitting ultraviolet light source device including: a plurality of gas discharge tubes each having an inner surface provided with a phosphor layer that emits ultraviolet light having a wavelength width of at least 210 nm to 250 nm and filled with a discharge gas, the gas discharge tubes being arranged in parallel on the electrode structure to form a light-emitting surface, the electrode structure having an electrode slit across which each of the gas discharge tubes crosses, and a pair of reflective electrodes extending symmetrically in the longitudinal direction of the gas discharge tubes on both sides of the electrode slit; an inverter circuit that applies an alternating drive voltage between the pair of reflective electrodes; a control unit that controls the inverter circuit by referring to a data table that stores data on changes over time in the emission intensity of the surface-emitting ultraviolet light source device; The control unit controls the alternating drive voltage applied between the electrodes by the inverter circuit based on the time-varying data so that the emission intensity of the surface-emitting ultraviolet light source device falls within a predetermined range over time.

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