Ultraviolet irradiation device

Abstract

The present invention provides a deep ultraviolet irradiation device which is safe and has good sterilization effect. The ultraviolet irradiation device is provided with an optical filter which prevents the transmission of ultraviolet light above 240nm emitted by the phosphor in a direction opposite to the light-emitting surface of a gas discharge tube array type surface light-emitting ultraviolet light source device having a phosphor layer with a peak wavelength of 228nm and a wide light-emitting spectrum of at least 210nm-250nm. The radiated light from the light source device changes the incident angle on the transparent substrate of the optical filter and is incident on the optical filter film. An ozone generating space can be formed between the surface light-emitting ultraviolet light source device and the optical filter.

Description

Technical Field

[0001] The present invention relates to an ultraviolet irradiation device, and in particular to a deep ultraviolet irradiation device for sterilizing (including disinfection and sterilization) and deodorizing viruses and various bacteria. In addition, in the present invention, deep ultraviolet refers to radiation in the ultraviolet region with a wavelength in the range of 200nm-300nm, wherein deep ultraviolet with a peak wavelength near 228nm is referred to as UVC1, and deep ultraviolet with a peak wavelength near 260nm is referred to as UVC2. In addition, vacuum ultraviolet (VUV) means ultraviolet with a wavelength below 200nm generated by rare gas discharge. Background Art

[0002] The sterilization and deodorization effects of ultraviolet rays are well known, and various sterilization or disinfection devices using ultraviolet rays are also well known (see Patent Documents 1-4). In addition, in the following Patent Document 1, it is proposed that ultraviolet rays with a wavelength of 200-230nm are the most suitable as they are conducive to virus inactivation and have no effect on human cells. Moreover, in the device disclosed in Patent Document 1, as a light source for radiating deep ultraviolet light in the above wavelength range, an excimer lamp with a narrow peak wavelength at a wavelength of 222nm is cited as a representative example.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2014-58612

[0006] Patent Document 2: International Publication No. 2016 / 125708

[0007] Patent Document 3: Japanese Patent Publication No. 2015-193521

[0008] Patent Document 4: International Publication No. 2018 / 235723 Summary of the invention

[0009] Problems to be solved by the present invention

[0010] However, the excimer lamp emitting deep ultraviolet light with a wavelength of 222nm uses highly toxic krypton chloride (KrCl) as the discharge gas, and environmental problems cannot be avoided when it is damaged. In addition, the KrCl excimer has the problem of narrow wavelength width of luminescence and limited bacteria or viruses that can be inactivated. That is, since the wavelength of the luminescence of the excimer lamp is concentrated at about 222nm, although more effective inactivation ability can be expected in a wavelength region shorter than that, it cannot be used.

[0011] In addition, in the conventional surface-emitting ultraviolet light source device for sterilization disclosed in patent document 2, due to the limitation of the glass material (old material) constituting the gas discharge tube and the limitation of the phosphor material, only the UVC2 light source device with a peak wavelength near 260nm becomes the limit of productization. In the glass material used in the UVC2 light source device, since the glass material constituting the tube shell absorbs the short-wavelength light near 240nm, it is more necessary to develop a new glass material capable of transmitting a shorter wavelength of deep ultraviolet light than to develop a new glass material having a better sterilization effect on viruses and bacteria. In addition, it is also necessary to develop a new process for emitting a shorter wavelength of deep ultraviolet light from a new phosphor with appropriate luminous efficiency.

[0012] Therefore, in order to solve the above-mentioned problems, the present invention provides a deep ultraviolet irradiation device which has a wide range of sterilization effects on various viruses and bacteria and has little effect on the human body and is safe.

[0013] Means of solving the problem

[0014] The ultraviolet irradiation device of the present invention for solving the above-mentioned problems is different from the conventional method of radiating a wavelength near 222nm which is beneficial for inactivating bacteria from an excimer lamp, and basically uses a surface luminescent light source device of a gas discharge tube array type using a deep ultraviolet phosphor as a deep ultraviolet light source. The conventional surface luminescent deep ultraviolet light source device of the gas discharge tube array type itself is known in the above-mentioned patent document 2, etc. However, in the present invention, it is characterized in that a deep ultraviolet phosphor layer is used which is excited by the discharge of xenon gas (Xe), has a wavelength near 228nm as a peak, and has a wide luminescent spectrum (UVC1) with a wavelength range of at least 210-250nm, and an optical filter is arranged opposite to the luminescent surface (the arrangement surface composed of the luminescent surfaces of the arranged gas discharge tubes) as needed to substantially prevent the transmission of ultraviolet rays in the wavelength region above 240nm in the luminescent spectrum of the phosphor.

[0015] The optical filter combined in the present invention has a structure of a dielectric multilayer film filter formed on the surface of an ultraviolet light-transmitting substrate, and the ultraviolet light-transmitting substrate is arranged in a direction relative to the light-emitting surface of a surface light-emitting ultraviolet light source device. The ultraviolet light-transmitting substrate is used to adjust the incident angle of the radiated light emitted from the light-emitting surface to the dielectric multilayer film filter.

[0016] Another aspect of the present invention is to utilize a surface luminescent ultraviolet light source device composed of a gas discharge tube array, and by selecting a new type of ultraviolet transmission glass that can obtain vacuum ultraviolet rays from the outside as the glass material constituting the outer shell of the gas discharge tube, it can effectively radiate vacuum ultraviolet rays VUV emitted by 172nm Xe, and can also effectively radiate UVC1. Therefore, another aspect of the present invention is characterized by the structure of the ultraviolet irradiation device, wherein an ozone generation space is formed between the light emitting surface of the surface luminescent light source device that radiates VUV and UVC1 at the same time and the optical filter, and the ozone generated in the space is released into the ambient space.

[0017] Another aspect of the present invention is to provide an ultraviolet irradiation device, which limits the radiation of the short wavelength side of the ultraviolet rays generated inside by adjusting the thickness of the glass tube constituting the outer shell of the gas discharge tube, and limits the radiation of the long wavelength side by arranging an optical filter opposite to the light-emitting surface. According to such a configuration, the following device design can be realized, that is, a device that widely covers the wavelength range of 200nm to 250nm that can be expected to be most effective for sterilization and disinfection, and prevents the radiation of ultraviolet rays in the vacuum ultraviolet region that are harmful to the human body or ultraviolet rays in the deep ultraviolet region with a wavelength of 240nm or more.

[0018] Next, the design concept of the glass shell for the gas discharge tube, which is the basis of the present invention, is described. In the past, the present inventors put into practical use a surface light source device of UVC2 having a peak near 260nm. However, when applying a new deep ultraviolet phosphor having a peak near 228nm to a capillary tube of an old borosilicate glass (BS1) used for the shell of a UVC2 light-emitting tube to trial-produce an ultraviolet light source device, as shown in FIG. Fig. 9 As will be described later, the transmittance of the old glass BS1 decreases sharply in a wavelength region below 250 nm, and therefore only weak light emission intensity can be obtained.

[0019] On the other hand, when using the new borosilicate glass (BS2) produced based on various experimental results, the ultraviolet transmittance in the short wavelength region is greatly improved. Fig. 9 As shown in the curve G of , a luminous spectrum can be obtained in which ultraviolet rays below 250nm are also transmitted with sufficient intensity. However, when the transmittance of ultraviolet rays is excessively increased, vacuum ultraviolet rays generated by gas discharge inside the tube transmit through the glass shell and emit ultraviolet rays with a wavelength of about 180nm. The radiation in the vacuum ultraviolet region generated by gas discharge will decompose the ambient air and contribute to the generation of ozone. The air purification effect brought by the generated ozone can be expected, but on the other hand, the generation of toxic ozone may not be preferred depending on the use environment.

[0020] Therefore, in order to obtain the best sterilization effect, it is necessary to realize a glass tube shell that can fully transmit ultraviolet rays below 250nm and can block the radiation of vacuum ultraviolet rays associated with the generation of ozone. Therefore, the present inventors conducted various experiments on the relationship between the material, thickness and transmittance of ultraviolet-transmitting glass constituting the shell of the gas discharge tube. As a result, they obtained a commercially available glass tube with a wall thickness of 0.6mm, which is borosilicate-based ultraviolet-transmitting glass that allows ultraviolet rays to pass more easily than old glass, and analyzed its transmittance. Fig. 9 The transmittance of the original tube of the new borosilicate glass (BS2) shown by the middle dotted line F is as low as about 70% near 228nm, and as the wavelength is further shortened, the transmittance sharply deteriorates, and at 210nm, the transmittance is less than 50%. In contrast, the conditions for making a capillary tube are adjusted, and a gas discharge tube with a glass tube shell as thin as about 90μm is made using the same glass as the original tube. As a result, it was found that only extremely limited vacuum ultraviolet radiation to the outside of the tube could be observed, and more than 90% of ultraviolet transmission could be achieved at 228nm. That is, it was confirmed that by using a new borosilicate glass as a new glass shell material and controlling the thickness of the tube, the transmittance on the short wavelength side of the emitted ultraviolet light can be selected.

[0021] Effects of the Invention

[0022] According to the present invention, as a light source for generating deep ultraviolet rays of wavelength (222nm) that is beneficial for virus inactivation, a surface-emitting ultraviolet light source device of a gas discharge tube array type characterized by not using highly toxic KrCl gas or mercury with environmental problems can be used, so that an ultraviolet irradiation device that is safe to operate as a whole can be obtained. In addition, the light emission of the deep ultraviolet phosphor used also has a wide light emission spectrum in the wavelength region below 240nm that is highly sensitive not only to a single virus but also to a variety of bacteria, so a more efficient and extensive sterilization and disinfection effect can be obtained.

[0023] In addition, the surface luminous ultraviolet light source device used in the present invention can radiate vacuum ultraviolet (VUV) while radiating deep ultraviolet 1 (UVC1). Therefore, an ozone generating space is formed between the luminous surface and the optical filter, and the vacuum ultraviolet VUV is used to decompose the air flowing therebetween to generate ozone, and the sterilization and deodorization effects of the ozone can be used at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram showing the structure of a gas discharge tube array type surface-emitting ultraviolet light source device.

[0025] Figure 2 This is a graph showing the emission spectrum of the phosphor formed on the gas discharge tube.

[0026] Figure 3 This is a graph showing the sensitivity of viruses and bacteria to ultraviolet wavelengths.

[0027] Figure 4 It is a cross-sectional structural view showing a first embodiment of the ultraviolet irradiation device of the present invention.

[0028] Figure 5 It is a graph showing the transmission characteristics and incident angle dependence of an optical filter.

[0029] Figure 6 It is a schematic diagram showing the assembly structure of the ultraviolet irradiation device according to the first embodiment.

[0030] Figure 7 It is a schematic structural diagram showing a second embodiment of the ultraviolet irradiation device of the present invention.

[0031] Figure 8 Graphs showing emission spectra of VUV and UVC of the surface-emitting ultraviolet light source device according to the second embodiment.

[0032] Fig. 9 It is a graph showing the relationship between the light emission characteristics of the gas discharge tube and the ultraviolet transmission characteristics of the glass tube.

[0033] Fig.10 It is a graph showing the relationship between the emission wavelength characteristics of the ultraviolet light source device according to the present invention and the inactivation curve and relative harmful effect characteristics of ultraviolet rays on bacteria. DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be further described in detail by means of the accompanying drawings. It should be understood that the following description is illustrative in all aspects and does not limit the present invention.

[0035] [Basic structure and driving principle of surface luminescent ultraviolet light source device]

[0036] In the present invention, the gas discharge tube array used as the surface-emitting ultraviolet light source device has basically the same structure as that disclosed in the above-mentioned Patent Document 2 except for the materials of the phosphor and the glass tube used.

[0037] (Gas Discharge Tube)

[0038] Figure 1(a) is a cross-sectional view of a gas discharge tube as a deep ultraviolet light emitting element. The gas discharge tube 1, as an example, is mainly composed of a glass capillary 2 having a flat elliptical cross section with a major diameter of 2 mm and a minor diameter of about 1 mm, and has a deep ultraviolet phosphor layer 3 on the inner surface of the back side. At the same time, it has a structure in which a discharge gas 4 is sealed inside and both ends are sealed. The discharge gas 4 contains a mixed gas of neon (Ne) and xenon (Xe) that radiates vacuum ultraviolet rays, or rare gases such as He and Xe, or Ar and Xe.

[0039] As the material of the glass capillary 2, when only UVC is generated, inexpensive borosilicate glass is used, and when VUV and UVC are generated simultaneously, borosilicate glass to which a trace amount of fluorine or the like is added to improve the ultraviolet transmittance is used. Specifically, ultraviolet-transmitting glass having a borosilicate composition as disclosed in Patent Document 3 is preferred. Of course, quartz glass, which is expensive but has excellent ultraviolet transmittance, can also be used. By drawing (re-drawing) the borosilicate glass tube to a wall thickness of less than 200 μm, preferably about 100 μm to make the wall thickness thinner, a glass capillary 2 that transmits at a transmittance of more than 80% from the vacuum ultraviolet region of about 140 nm in wavelength to the deep ultraviolet region of about 280 nm in wavelength can be obtained. However, when the wall thickness is less than 50 μm, the strength is insufficient and there is a risk of breakage, so it is not preferred.

[0040] In addition, as the deep ultraviolet phosphor layer 3 newly adopted in the present invention, a phosphor composed of lutetium and scandium phosphate having a peak of the emission spectrum near the wavelength of 228nm, as disclosed in the above-mentioned Patent Document 4, is used. The emission spectrum of the phosphor used in the present invention is as follows: Figure 2 As shown, it has a continuous wide wavelength width of 200nm-260nm with a peak at 228nm, and radiates effective deep ultraviolet light at least in the range of 210nm-250nm.

[0041] [Surface emitting ultraviolet light source device]

[0042] like Figure 1As shown in (b), a plurality of gas discharge tubes 1 as ultraviolet light emitting elements are arranged in parallel on an electrode substrate 11 having an electrode pair 12 (electrode pair of electrode 12X and electrode 12Y), so as to manufacture a gas discharge array type surface light emitting ultraviolet light source device 10. The electrode substrate 11 is based on, for example, a polyimide-based insulating substrate 13, on which the arrangement of the gas discharge tubes 1 is supported by an adhesive layer, and on the lower side opposite to the electrode substrate 11, there is an electrode pair 12. As another structure, the electrode pair 12 can be formed on the upper surface of the insulating substrate 13, and the arrangement of the gas discharge tubes can be supported by an adhesive layer that also acts as an insulating layer on the electrode pair 12. The electrode pair 12 is composed of an electrode 12X and an electrode 12Y that are opposite to the bottom back of each gas discharge tube 1 and have a pattern extending to both sides with a common electrode slit (electrode gap G) sandwiched therebetween.

[0043] If the insulating substrate 13 as the base of the electrode substrate 11 is composed of an insulating film of a polyimide resin, and the gas discharge tubes are arranged with gaps between each other, a surface-emitting ultraviolet light source device 10 that is bendable and flexible in the tube arrangement direction as a whole can be formed. In addition, if ventilation holes or ventilation slits that penetrate the front and back surfaces are formed on the electrode substrate 11 so that the bottom surface of each gas discharge tube is partially exposed, it is beneficial to the heat dissipation of each gas discharge tube.

[0044] [Driving principle]

[0045] Figure 1 (c) is a schematic diagram for explaining the driving principle. The inverter circuit 15 applies an alternating drive voltage with a peak-to-peak voltage (PP voltage) of 1000-2000V and a frequency of 30-40KHz to the electrode X and the electrode 12Y constituting the electrode pair 12. During the rising process of the alternating drive voltage applied by the inverter circuit 15, an initial discharge occurs in the discharge gap in the gas discharge tube 1 corresponding to the electrode gap G between the electrode 12X and the electrode 12Y. Then, as the alternating drive wave voltage rises, the discharge expands in the length direction of the gas discharge tube 1.

[0046] By applying an alternating driving voltage, discharges are generated alternately and repeatedly in the area of ​​the gas discharge tube 1 corresponding to the electrodes 12X and 12Y while the polarity of the charges is alternately accumulated. When the gas sealed in the gas discharge tube is a mixed gas of neon (Ne) and xenon (Xe), a discharge accompanied by vacuum ultraviolet (VUV) radiation including 143nm and 172nm is generated at a discharge voltage lower than that of other gases. Through the excitation of the VUV, deep ultraviolet (UVC1) with a central wavelength of 228nm is radiated from the fluorescent layer 3. The driving principle and the specific driving circuit are described in detail in the above-mentioned patent document 2.

[0047] [Implementation Method 1]

[0048] Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

[0049] Figure 2 It is a graph showing the luminous spectrum of the deep ultraviolet phosphor layer 3 from the above-mentioned gas discharge tube array type surface luminous ultraviolet light source device 10. The vertical axis is the number of luminous photons (photon count) as the luminous intensity, and the horizontal axis represents the wavelength. From the luminous spectrum, it can be seen that within the continuous wavelength range of 215-245nm, a luminous intensity of more than 70% of the peak wavelength of 228nm can be obtained.

[0050] on the other hand, Figure 3 This is a graph of wavelength sensitivity of various viruses and E. coli disclosed in Newsletter No. 4 issued by the Japan Ultraviolet Water Treatment Technology Association in January 2011. From this graph, it can be seen that the ultraviolet sensitivity of various viruses and bacteria increases on the short wavelength side of wavelengths below 230nm. That is, by irradiating the wide range of deep ultraviolet rays from the ultraviolet phosphor layer 3, a better sterilization effect can be obtained for more types of bacteria and viruses compared with irradiation with a single wavelength of 222nm from a KrCl excimer lamp.

[0051] Figure 4 is a diagram showing a basic cross-sectional structure of an ultraviolet irradiation device according to the present invention, wherein an optical filter 20 and a Figure 2 The optical filter 20 has a surface emitting ultraviolet light source device 10 with such an emission spectrum. The optical filter 20 has a HfO layer formed on an ultraviolet-transmitting substrate, preferably a synthetic quartz substrate 21 with a thickness of about 1 mm. 2 / SiO 2 The structure of the dielectric multilayer filter 22 is composed of Figure 5 The solid line A shows the transmission characteristics. That is, it has the characteristics of being able to transmit deep ultraviolet rays of 230 nm or less including the peak wavelength of 228 nm of the phosphor layer 3, and preventing the transmission of ultraviolet rays of 240 nm or more that are likely to have adverse effects on human tissues.

[0052] However, the deep ultraviolet light from 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 filter 22 combined with the surface emitting ultraviolet light source device 10 has a Figure 5 The incidence angle dependence is shown. Figure 5In the figure, the incidence from the direction perpendicular to the surface of the dielectric multilayer film filter 22 is the reference of the angle. Compared with the transmission characteristic of the incident angle 0 (zero) degree shown by the solid line A, for the radiation with an incident angle of 10 degrees, it becomes the transmission characteristic shown by the dotted line B. In addition, for the radiated light with an incident angle of 20 degrees, as shown by the dotted line C, there is a tendency that the transmission curve shifts to the short wavelength side as the incident angle increases. That is, in the structure in which the radiated light from the surface luminous ultraviolet light source device 10 directly enters the dielectric multilayer film filter 22, the light of the surrounding part of the ultraviolet light radiated at a wide angle cannot fully transmit the filter.

[0053] In the present invention, in order to allow the deep ultraviolet radiation from the surface-emitting ultraviolet light source device 10 to pass through the dielectric multilayer film filter 22 as efficiently as possible, the two are combined and configured with the quartz substrate 21 being located on the incident surface side of the filter. That is, in this configuration structure, the quartz substrate 21 acts as an optical element in front of the dielectric multilayer film filter 22 to transform the incident angle light of the optical filter 20 of the portion of the deep ultraviolet light radiated at a wide angle from each gas discharge tube 1, which has a large radiation angle. Figure 4 In FIG. 1 , the arrow line 23 indicates the refraction of the radiated light reaching the dielectric multilayer film filter 22 from the radiating surface of the gas discharge tube 1. The radiated light from the radiating surface of the gas discharge tube 1 constituting the surface luminescent ultraviolet light source device 10 enters the dielectric multilayer film filter 22 after its radiation angle is corrected to a direction in which the incident angle is narrowed due to the difference between the refractive index of the space between the quartz substrate 21 and the quartz substrate (n≈1 for air) and the refractive index of the quartz substrate (n=1.5). As a result, it was found that the attenuation of the radiation intensity of the deep ultraviolet light centered at 228nm radiated through the optical filter can be suppressed.

[0054] In addition, in order to further reduce the incident loss of the deep ultraviolet radiation light 23 radiated at a wide angle from the surface luminescent ultraviolet light source device 10 to the dielectric multilayer film filter 22, ribs with stripes or a lattice pattern that function as a diffraction grating may be provided on the incident surface side of the quartz substrate 21 constituting the optical filter 20. By using the strip ribs corresponding to the arrangement pitch of the gas discharge tubes 1, the incident angle of the deep ultraviolet radiation radiated at a wide angle from each gas discharge tube of the surface luminescent ultraviolet light source device 10 to the dielectric multilayer film filter 22 can be narrowed.

[0055] Figure 6(a) is a three-dimensional schematic diagram showing the assembly structure of the ultraviolet irradiation device as the first embodiment. The driving circuit board 40 is arranged on the base substrate 30 having an air inlet hole (not shown), and the air blower 50, the surface light-emitting ultraviolet light source device 60 and the optical filter 20 are assembled and supported above the driving circuit board 40 by four pillars 31. In addition, the whole is housed in a box shown in the dotted line with an ultraviolet irradiation window (opening) on ​​the top. Figure 6 In the figure, for convenience, the light emitting surface of the surface light emitting ultraviolet light source device 60 is configured to be in a substantially horizontal direction, and the irradiation direction of ultraviolet rays is configured to be in an upward direction, but the irradiation direction may be arbitrarily selected.

[0056] Here, as the surface emitting ultraviolet light source device 60, a Figure 6 (b) shows an electrode substrate 61 with slits. Figure 1 (b) The electrode substrate 11 described is different, Figure 6 The electrode substrate 61 shown in (b) is formed with a plurality of through slits 64 penetrating the electrode substrate 61 in a manner substantially parallel to the gap G for the discharge gap. On such an electrode substrate 61 with slits, a portion of the bottom surface (back surface) of the arranged gas discharge tubes 1 is exposed downward, and a vent hole is formed at the intersection of the gap between adjacent gas discharge tubes and the through slit 64. Therefore, the cooling air flow from the blower fan 50 through the vent hole can effectively cool the surface light-emitting ultraviolet light source device 60. In addition, the vent hole provided on the electrode substrate is not limited to the slit shape as described above, and may also be a shape in which a plurality of small holes are dispersedly arranged to expose a portion of the back surface of the discharge tube.

[0057] [Implementation Method 2]

[0058] Figure 7 1 is a schematic diagram showing the structure of an ultraviolet irradiation device accompanied by ozone generation as a second embodiment of the present invention. A component is supported on a base substrate 30 having a vent (not shown), in which an optical filter 20 and a driving circuit substrate 40 are arranged to sandwich a surface-emitting ultraviolet light source device 10 of a gas discharge tube array type from the left and right sides. A space that functions as an ozone generating space 51 is formed between the surface-emitting ultraviolet light source device 10 and the optical filter 20. 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 driving circuit substrate 40. A blower fan 50 is provided opposite to the end faces of the ozone generating space 51 and the heat dissipation path 52, and ozone is discharged from the ozone generating space 51 by the blower fan 50, and at the same time, the heat generated by the gas discharge tube array 10 and the driving circuit substrate 40 is released from the heat dissipation path 52.

[0059] In such a structure, each gas discharge tube 1 constituting the surface luminescent ultraviolet light source device 10 is as described above with reference to Figure 1 As described, when the glass capillary 2 is quartz glass or thin borosilicate glass with high ultraviolet transmittance, it radiates a deep ultraviolet emission spectrum (UVC1) having a wavelength width of at least 210nm-250nm with a peak wavelength near 228nm of the phosphor layer 3, and at the same time radiates vacuum ultraviolet light (VUV) of 172nm. Figure 8 The emission spectra of UVC and VUV from the gas discharge tube array type surface light emitting ultraviolet light source device used in the above embodiment are shown.

[0060] The driving circuit substrate 40 is equipped with a driving circuit including an inverter circuit 15 for providing an alternating driving voltage to the surface luminescent ultraviolet light source device, and is also equipped with a timer for controlling the irradiation time and a control circuit for controlling the entire device. When the surface luminescent ultraviolet light source device 10 is driven by the driving circuit, deep ultraviolet rays below 240nm with a peak wavelength of about 228nm are irradiated through the optical filter 20 to sterilize and disinfect the air and objects in the irradiation space.

[0061] On the other hand, among the vacuum ultraviolet rays generated in the gas discharge tube 1, the vacuum ultraviolet rays with a wavelength of 172nm from the xenon gas, which are reflected by the fluorescent layer 3 having the ultraviolet reflection function and radiated from the light-emitting surface, decompose the air in the ozone generation space 51 between the light-emitting surface of each gas discharge tube 1 constituting the surface light-emitting ultraviolet light source device 10 and the optical filter 20 to generate ozone. The generated ozone is discharged to the top together with the air from the blower fan 50, and plays a sterilizing role on the ambient air. Of course, ozone itself has a strong oxidizing effect and toxicity, so it is extremely effective for sterilization and disinfection in an unmanned closed space regardless of its concentration, but on the contrary, excessive emission into a manned environment space must be limited. That is, low-concentration ozone is harmless to the human body and is extremely beneficial for space sterilization.

[0062] Therefore, it is necessary to control the ozone released into the manned space so that the ozone concentration does not exceed the determined reference value of 0.1ppm. Incidentally, in a surface luminous ultraviolet light source device 10 with a light-emitting area of ​​8×3cm and 12 gas discharge tubes with a length of 8cm are arranged, 20mg of ozone can be generated per hour. By intermittently applying an alternating drive voltage and changing the duty cycle of the alternating drive voltage, the ozone generation amount using the surface luminous ultraviolet light source device can be appropriately controlled, and the on / off drive can be controlled by feeding back the monitored value of the ozone concentration in the ambient space.

[0063] [Implementation Method 3]

[0064] In the above-mentioned second embodiment, a device structure is described in which ozone is generated by emitting vacuum ultraviolet rays simultaneously with the radiation in the deep ultraviolet region, and both ozone and UVC1 are utilized. However, depending on the use environment, there are also cases where ozone generation is not desired. The inventors of the present invention have confirmed that the emission of vacuum ultraviolet rays generated by the discharge of xenon (Xe) gas to the outside can be controlled by the glass thickness of the tube shell. That is, in the case of a glass tube composed of synthetic quartz, although the ultraviolet transmittance cannot be adjusted by the thickness of the glass, in a tube using borosilicate-based ultraviolet-transmitting glass, if the thickness is reduced, the transmittance of ultraviolet rays is increased for the same wavelength, and at the same time, it is shifted to the short wavelength side.

[0065] Fig. 9 This is a graph showing the relationship between the ultraviolet transmittance and the ultraviolet emission spectrum of borosilicate ultraviolet-transmitting glass tubes available on the market. Curve D is the ultraviolet transmittance characteristic of an old borosilicate glass (BS1) tube that previously emitted 260nm ultraviolet rays. When a device is manufactured using a 228nm phosphor using this glass, the luminous waveform of curve E is obtained. Thus, sufficient ultraviolet luminescence cannot be obtained in the range of 210-250nm. On the other hand, curve F is the transmittance curve of a glass mother tube with a diameter of 15.7mm and a thickness of 0.6mm purchased on the market as a borosilicate ultraviolet-transmitting glass tube (BS2). At a wavelength of 220nm, the transmittance is about 70%, and the transmittance of ultraviolet rays decreases as it moves to the short wavelength side, and the cut-off wavelength is about 205nm. When the mother tube is drawn (re-drawn) into a tube with a flat elliptical cross-section having a long diameter of 2.5mm, a short diameter of 1mm and a thickness of 90μm, the transmittance characteristic of curve G is obtained.

[0066] exist Fig. 9 In the figure, curve H is the front Figure 8 The emission spectra of vacuum ultraviolet rays and deep ultraviolet rays from the phosphor layer shown in FIG. 1 can be obtained by a gas discharge device composed of a quartz glass tube or a tube in which the thickness of the borosilicate glass tube (BS2) that easily transmits vacuum ultraviolet rays is reduced to less than 70 μm as described above. On the other hand, curve I represents the luminous characteristics of a gas discharge tube having the same deep ultraviolet phosphor layer, which is composed of a borosilicate glass tube (BS2) with a thickness of 90 μm and has the transmittance characteristics of the above curve G. It can be seen that in the light source device having such a configuration, the radiation in the vacuum ultraviolet region with a peak near 178 nm is cut off, and broadband ultraviolet luminescence in the range of 200 nm to 260 nm is obtained.

[0067] Fig.10 It indicates that the deep ultraviolet phosphor layer with a peak wavelength of 228nm Figure 2 The broadband luminescence characteristic curve shown has the same characteristics (same as Fig. 9 The inactivation curve J for bacteria and the curve K for relative spectroscopic harmful characteristics are overlapped on the basis of the curve I of FIG. Figure 3 The graphs showing the wavelength sensitivity of Escherichia coli and the like are from the same source, and the relative spectroscopic harmful characteristic K is a well-known characteristic specified in the Japanese Industrial Standard JIS (Z8812-1987). It can be seen from the graph that the inactivation effect on bacteria increases from a wavelength of about 240nm to the short wavelength side, while on the other hand, the harmful effect on the human body tends to decrease from a wavelength of 270nm to the short wavelength side. Based on this relationship, it can be well understood that deep ultraviolet rays with a wide wavelength width in the range of 200nm-240nm suppress harmful effects to a low level and widely exert a bactericidal effect. In addition, the curve L represents the 222nm single wavelength characteristic of the excimer lamp of KrCl gas disclosed in Patent Document 1 for comparison, and its bacterial inactivation effect is limited.

[0068] [Other Modifications]

[0069] The above is a representative structural example of the present invention, but various other deformations can also be made. For example, the surface-emitting ultraviolet light source device of the gas discharge tube array type is characterized in that, in addition to being mercury-free, the electrode substrate is a flexible structure, and the electrode substrate can be bent in the arrangement direction of the tube. Therefore, by bending the light-emitting surface of the surface-emitting ultraviolet light source device 10 into a concave structure, and at the same time, the optical filter 20 also becomes a structure with a concave surface on the incident surface side, it is possible to converge the irradiation light to the irradiated object and increase the irradiation intensity. Alternatively, it is also possible to configure an optical element such as a convex lens made of ultraviolet transmissive material instead of the above-mentioned optical filter before the light source device bent into a concave shape, so as to further converge the irradiation light.

[0070] In addition, as in the second embodiment, when ozone is generated while irradiating deep ultraviolet rays and the air is sterilized by ozone, the plurality of gas discharge tubes constituting the surface light-emitting ultraviolet light source device 10 do not necessarily need to have the same emission spectrum. Instead of the phosphor layer 3, a hybrid array may be formed in which magnesium oxide (MgO) or aluminum oxide (Al2O3) is mixed and arranged between the gas discharge tubes for deep ultraviolet radiation. 2 O 3) or other ultraviolet reflection layers. Alternatively, as the material of the deep ultraviolet phosphor layer 3, in addition to the gas discharge tube using the broadband luminescent phosphor with a peak wavelength at 228nm, if the gas discharge tube using a phosphor with a peak wavelength at 191nm or 209nm disclosed in Patent Document 4 is regularly mixed and arranged, it is possible to form a gas discharge tube array type light source device with ultra-wideband and stable luminous intensity. By combining the device with an optical filter that cuts off wavelengths above 240nm, it is possible to obtain an ultraviolet irradiation device with low harmful effects and a wide range of inactivation effects on viruses or bacteria.

[0071] In the case of using a broadband deep ultraviolet phosphor material having a central wavelength at 228nm and substantially having no luminous spectrum components above 240nm as the phosphor layer 3, or in the case of constituting an irradiation device for use in an unmanned environment even if the luminous wavelength spectrum exceeds 240nm, the optical filter 20 can be omitted. Alternatively, a simple protective plate of ultraviolet-transmitting material can be configured to replace the dielectric multilayer filter 22 to form an ozone generating space between it and the surface-emitting ultraviolet light source device 10.

[0072] As a further development system of the present invention, a surface-emitting ultraviolet light source device that simultaneously generates VUV light and UVC light generated by a fluorescent body as described above can be used to form an air sterilization device. Figure 6 (a) or Figure 7 The structure of the present invention is the same as that of the present invention. By configuring a driving circuit substrate 40, a blower fan 50, and a VUV+UVC surface luminescent light source device 60 in a sterilization box having an inlet opening for introducing air to be sterilized from the surrounding environment and an outlet opening for the sterilized air, an air sterilization device can be obtained. In this case, the deep ultraviolet light from the phosphor is not emitted to the outside, but plays a role in sterilizing and deodorizing the air introduced into the sterilization box together with the ozone generated by the VUV and the active oxygen generated by the reaction of ozone and UVC during the generation period, and the clean air and the remaining ozone are released from the sterilization box to the environment. The phosphor layer can appropriately use a phosphor that emits light in the deep ultraviolet region with an ultraviolet reflection function on the coating surface, but a UVC2 luminescent phosphor with a peak at 260nm is preferred. The optical filter 20 is not required and can be omitted, or a cover with an air outlet hole can be configured instead.

[0073] In addition, by arranging a plurality of long gas discharge tubes on an electrode substrate, the electrode substrate is provided with a plurality of electrode pairs, in which the discharge electrode gap is sandwiched between the electrode pairs in a direction intersecting the longitudinal direction of the gas discharge tubes, an ultraviolet irradiation device having a large irradiation surface can be constructed. The size of the irradiation surface can be determined by the length and number of arrangement of the gas discharge tubes and the arrangement pattern of the divided electrode pairs. In addition, an irradiation device having a large irradiation surface can be constructed by tiling a plurality of small-sized surface-emitting ultraviolet light source devices.

[0074] In addition, the surface luminescent ultraviolet light source device can also be composed of a deep ultraviolet phosphor layer and an ultraviolet or electron beam excitation source that excites the phosphor layer to generate deep ultraviolet light in a flat glass envelope having ultraviolet transmissivity. As the electron beam excitation source, a structure that emits electrons based on the field emission principle can be used.

[0075] [Summarize]

[0076] In conclusion, according to the present invention, it is possible to obtain a safe ultraviolet irradiation device which minimizes the adverse effects of ultraviolet rays on the human body and has the effect of sterilizing and disinfecting viruses and bacteria.

[0077] The aspects of the present invention include any combination of the above-mentioned plural aspects.

[0078] In addition to the above embodiments, the present invention may also have various modifications. These modifications should not be interpreted as not belonging to the scope of the present invention. The present invention should include the meaning equivalent to the claims and all modifications within the scope.

[0079] Explanation of symbols

[0080] 1: gas discharge tube, 2: glass capillary, 3: phosphor layer, 4: discharge gas, G: electrode gap, 10, 60: surface luminescent ultraviolet light source device, gas discharge tube array, 11, 61: electrode substrate, 12: electrode pair, 12X, 12Y: electrode, 13: insulating substrate, 15: 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 substrate, 50: air supply fan, 51: ozone generating space, 52: heat dissipation path, 64: through slit.

Claims

1. An ultraviolet irradiation device, characterized in that: A plurality of gas discharge tubes for ultraviolet light emission are arranged in parallel on a common pair of electrodes, and an optical filter is arranged in front of a light emitting surface of a light source device for generating ultraviolet light in a deep ultraviolet region with a wavelength range of at least 210-250nm to substantially prevent the transmission of ultraviolet light above 240nm in the ultraviolet light. The front side of the glass envelope constituting the gas discharge tube has a thickness selected to limit the emission of the short-wavelength side of the ultraviolet rays. The glass tube constituting the gas discharge tube has a thin tube structure with a front side thickness of 70 μm or more made of an ultraviolet-transmitting glass matrix material, wherein the ultraviolet-transmitting glass matrix material has a characteristic that the ultraviolet transmittance at a wavelength of 220 nm is 70±15% when the wall thickness is 0.6 mm, and the cut-off wavelength of the ultraviolet rays is 205±5 nm; Alternatively, the glass tube constituting the gas discharge tube has a thin tube structure with a front side wall thickness of 70 μm or more made of ultraviolet-transmitting glass, wherein the ultraviolet-transmitting glass has an ultraviolet transmittance of 90±10% at a wavelength of 220 nm when the wall thickness is 0.07 mm, and a cut-off wavelength of ultraviolet rays of 200±10 nm.

2. The ultraviolet irradiation device according to claim 1, characterized in that The light source device comprises: a gas discharge tube, which is mainly composed of a glass shell having a front side serving as a light-emitting surface and an opposite back side and is made of ultraviolet-transmitting glass, a phosphor layer emitting ultraviolet rays in a deep ultraviolet region with a wavelength range of at least 210-250nm is arranged on the inner surface of the back side of the glass shell, and a discharge gas emitting vacuum ultraviolet rays is sealed inside; and an electrode pair, which is opposite to the back side of the gas discharge tube and is arranged to extend to both sides with a gap constituting a discharge gap sandwiched therebetween.

3. The ultraviolet irradiation device according to claim 2, characterized in that: The phosphor layer has a broadband emission spectrum with a peak wavelength near 228 nm.

4. The ultraviolet irradiation device according to any one of claims 1 to 3, characterized in that: The optical filter has a structure of a dielectric multilayer film filter formed on the surface of an ultraviolet-transmitting substrate, wherein the ultraviolet-transmitting substrate is arranged opposite to the light-emitting surface of each gas discharge tube constituting the light source device, and the incident angle of the radiated light from the light-emitting surface to the dielectric multilayer film filter is adjusted by utilizing the difference between the refractive index of the space between the light-emitting surface and the ultraviolet-transmitting substrate and the refractive index of the ultraviolet-transmitting substrate.

5. The ultraviolet irradiation device according to any one of claims 1 to 3, characterized in that: The optical filter includes: a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate; and a diffraction grating provided on the ultraviolet incident surface side of the quartz substrate.

6. The ultraviolet irradiation device according to any one of claims 1 to 3, characterized in that: The optical filter comprises: a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate; and striped pattern ribs arranged on the ultraviolet incident surface side of the quartz substrate to narrow the incident angle of the radiated light from the gas discharge tube to the dielectric multilayer film filter.

7. The ultraviolet irradiation device according to any one of claims 1 to 3, characterized in that: The optical filter comprises: a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate; and grating pattern ribs arranged on the ultraviolet incident surface side of the quartz substrate to narrow the incident angle of the radiated light from the gas discharge tube to the dielectric multilayer film filter.

8. The ultraviolet irradiation device according to any one of claims 1 to 3, characterized in that: The optical filter comprises: a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate; and a plurality of ribs having a stripe pattern or a lattice pattern, which are arranged on the ultraviolet incident surface side of the quartz substrate corresponding to the arrangement of the gas discharge tubes so as to narrow the incident angle of the radiated light from the gas discharge tubes to the dielectric multilayer film filter.

9. An ultraviolet irradiation device, characterized in that: The ultraviolet light source device is mainly composed of: a glass shell having a front side serving as a light-emitting surface and an opposite back side, a phosphor layer radiating ultraviolet rays in a deep ultraviolet region inside, a discharge gas for generating vacuum ultraviolet rays for exciting the phosphor layer sealed therein; and an electrode pair arranged opposite to the back side of the glass shell and having a pattern extending to both sides with a gap constituting a discharge gap sandwiched therebetween, An optical filter is arranged in front of the light emitting surface of the ultraviolet light source device to limit the emission wavelength on the long wavelength side in the light emission spectrum of the phosphor layer. Furthermore, the glass shell is made of borosilicate ultraviolet-transmitting glass having a thickness of 70 μm or more on the front side, and the radiation on the short-wavelength side including vacuum ultraviolet rays generated in the ultraviolet light source device is selectively controlled by the thickness of the front side. Furthermore, the glass shell has a thin tube structure with a front side thickness of 70 μm or more made of a borosilicate ultraviolet-transmitting glass matrix material, and the borosilicate ultraviolet-transmitting glass matrix material has a characteristic that the ultraviolet transmittance at a wavelength of 220 nm is 70±15% when the wall thickness is 0.6 mm, and the cut-off wavelength of ultraviolet rays is 205±5 nm; Alternatively, the glass shell has a thin tube structure with a front side wall thickness of more than 70 μm made of borosilicate ultraviolet-transmitting glass, and the borosilicate ultraviolet-transmitting glass has an ultraviolet transmittance of 90±10% at a wavelength of 220 nm when the wall thickness is 0.07 mm, and a cut-off wavelength of ultraviolet rays of 200±10 nm.

10. The ultraviolet irradiation device according to claim 9, characterized in that The phosphor layer has a broadband emission spectrum with a peak wavelength near 228 nm.

11. The ultraviolet irradiation device according to claim 9, characterized in that An optical filter for blocking radiation of ultraviolet rays having a wavelength of 240 nm or more is arranged in front of the light emitting surface of the ultraviolet light source device.

12. The ultraviolet irradiation device according to any one of claims 9 to 11, characterized in that: The optical filter is constructed as follows: a dielectric multilayer film filter structure is formed on the surface of a quartz substrate having a refractive index greater than that of air, the quartz substrate is arranged opposite to the light-emitting surface of each gas discharge tube constituting the ultraviolet light source device, and the incident angle of ultraviolet radiation to the dielectric multilayer film filter is adjusted by utilizing the difference between the refractive index of the quartz substrate and the refractive index of the space between the light-emitting surface and the quartz substrate.

13. An ultraviolet irradiation device, characterized in that: It comprises: a gas discharge tube array, which is mainly composed of glass tubes having a front side serving as a light-emitting surface and an opposite back side, a deep ultraviolet phosphor layer being provided on the inner surface of the back side of the glass tubes, and a plurality of gas discharge tubes formed by sealing discharge gas inside being arranged in parallel; an electrode pair, which is opposite to the back side of the gas discharge tube array and extends to both sides with electrode slits constituting a common discharge gap on each gas discharge tube, and an optical filter is arranged in front of the front side arrangement surface of each gas discharge tube in order to substantially prevent the transmission of ultraviolet rays above 240 nm in the light emission spectrum of the phosphor layer, the optical filter having a diffraction grating on the incident surface side, and the glass tubes are formed of glass having a wall thickness of 70 μm or more. Furthermore, the glass capillary tube has a capillary structure with a front side thickness of 70 μm or more made of an ultraviolet-transmitting glass matrix, and the ultraviolet-transmitting glass matrix has a characteristic that the ultraviolet transmittance at a wavelength of 220 nm is 70±15% when the wall thickness is 0.6 mm, and the cut-off wavelength of the ultraviolet rays is 205±5 nm; Alternatively, the glass capillary tube has a capillary tube structure with a front side wall thickness of 70 μm or more formed of ultraviolet-transmitting glass, wherein the ultraviolet-transmitting glass has an ultraviolet transmittance of 90±10% at a wavelength of 220 nm when the wall thickness is 0.07 mm and a cutoff wavelength of ultraviolet rays of 200±10 nm.

14. The ultraviolet irradiation device according to claim 13, characterized in that: The phosphor layer has a broadband emission spectrum with a peak wavelength near 228 nm.

15. The ultraviolet irradiation device according to claim 13 or 14, characterized in that: The optical filter including the diffraction grating is composed of a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate, and a diffraction grating provided on the ultraviolet incident surface side of the quartz substrate, the diffraction grating being a rib with a stripe pattern.

16. The ultraviolet irradiation device according to claim 13 or 14, characterized in that: The optical filter including the diffraction grating is composed of a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate, and a diffraction grating provided on the ultraviolet incident surface side of the quartz substrate, the diffraction grating being a rib of a lattice pattern.

17. The ultraviolet irradiation device according to claim 13 or 14, characterized in that: The optical filter having the diffraction grating is composed of a dielectric multilayer film filter structure formed on the ultraviolet emitting surface side of a quartz substrate, and a diffraction grating arranged on the ultraviolet incident surface side of the quartz substrate, wherein the diffraction grating is a plurality of ribs of a stripe pattern or a grid pattern corresponding to the arrangement pitch of the gas discharge tube.

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