JP2008161095A - Apparatus for ultraviolet ray sterilization, and method for ultraviolet ray sterilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for ultraviolet ray sterilization with which viruses are inactivated through concentration of near-ultraviolet ray so as to sterilize colored liquid, and sterilization effect on the viruses or the colored liquid is improved even in use having difficulty in uniform irradiation of ultraviolet ray. <P>SOLUTION: The apparatus for ultraviolet ray sterilization of viruses or colored liquid is provided with an LED for radiating ultraviolet ray. The LED is provided with a photogenesis chip having a peak of main emission in a wavelength region of 360-380 nm, and a light-focus lens focusing the light emission of the photogenesis chip so that the LED focuses the light emission of the photogenesis chip with the light-focus lens and emits the focused light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus and method for inactivating a virus or sterilizing a colored liquid with ultraviolet light from an LED, and more particularly, an ultraviolet sterilization apparatus using an LED that emits light at the boundary between the near ultraviolet region and visible light. The present invention relates to a sterilization method.

  Sterilization is indispensable not only in our daily life but also in industry. In general, chemical sterilization with chlorine, heat sterilization, ultraviolet sterilization, ozone sterilization, etc. are known as sterilization methods. There is a need for a higher quality sterilization technique from the viewpoint of lack of environmental protection and environmental friendliness. From such a background, a sterilization method using ultraviolet rays (UV), that is, ultraviolet sterilization has been widely used.

  Virus inactivation by UV is excellent in safety because there is no residue like a drug. In addition, ultraviolet rays are said to destroy viral DNA or RNA, and have the advantage of not producing resistant bacteria unlike drug sterilization. The sterilization mechanism by UV is generally explained as follows. Nucleic acids (DNA or RNA) that control genetic information exist in the cells of organisms, including bacteria, and when irradiated with ultraviolet light, the nucleic acids absorb the light, causing damage to some nucleic acids and transcription from the genes. Control is delayed and the metabolism is disturbed and inactivated.

  FIG. 1 shows the wavelength characteristics of the ultraviolet germicidal action that is currently recognized as a standard internationally (see non-patent literature). As is clear from FIG. 1, the wavelength showing the maximum value of the bactericidal action is around 260 nm, and a lamp that efficiently radiates 253.7 nm of UV (referred to as bactericidal radiation or bactericidal radiation) close to this wavelength is a germicidal lamp ( Or a sterilizing lamp). However, the germicidal lamp is made of a special glass tube that allows the germicidal wire to pass therethrough, and it is difficult to reduce the size and weight, and there is a problem that the shape is limited and the power consumption is larger than that of the LED. . In addition, argon gas and mercury, which is an environmental pollutant, are enclosed in the tube, and there are special restrictions at the time of disposal and there are problems such as complexity.

  In recent years, an ultraviolet sterilizer using LEDs has been proposed in place of the problematic germicidal lamps (see Patent Documents 1 to 5). Patent Documents 1 to 4 are intended to activate a photocatalyst made of titanium oxide with ultraviolet rays of an LED to generate a bactericidal action. For effective sterilization, it is necessary to directly contact the photocatalyst. Because there is a restriction on the usage state, and because a photocatalyst is essential, extra processing is required to fix the material cost and the photocatalyst, and because it depends on the dispersion and deterioration of the performance of the photocatalyst, There are problems such as unstable bactericidal effect.

  Furthermore, patent document 5 describes the purification apparatus of LED. The purification device includes a purification chamber and an LED that generates ultraviolet light. The LED is arranged to illuminate the interior of the purification chamber. This patent document describes that the optimal range of bactericidal effects by UV irradiation is UV irradiation between 245 nm and 285 nm and that the virus is sensitive to wavelengths above 254 nm of mercury emission. Short wavelength ultraviolet rays having a wavelength region of 254 nm are not only invisible, but also have a bad influence on the human body. For this reason, even if the virus can be effectively sterilized, there is a drawback that it cannot be used safely.

  On the other hand, in the sterilization using only ultraviolet rays without using a photocatalyst, as shown in FIG. 1, when the wavelength is 300 nm or more, the sterilization action is rapidly reduced to 1/100 or less and the sterilization effect is not expected. Are excluded as unnecessary.

  Furthermore, ultraviolet rays having a wavelength of about 260 nm have an excellent sterilizing effect. However, in order to realize an excellent sterilizing action, it is necessary to irradiate ultraviolet rays to the portion to be sterilized. The sterilizing effect due to ultraviolet rays is significantly reduced in shaded areas where ultraviolet rays are not directly irradiated or in areas where the irradiation intensity of ultraviolet rays is significantly weakened.

  Furthermore, an apparatus for sterilizing a colored liquid such as milk by irradiating it with ultraviolet rays has been developed (see Patent Document 6). However, the colored liquid has a poor transmittance of ultraviolet rays, and the whole cannot be sterilized by irradiating the inside with ultraviolet rays. In particular, ultraviolet rays having a wavelength of 254 nm emitted from an ultraviolet lamp have poor permeability for colored liquids. For this reason, as described in Patent Document 6, it is necessary to irradiate ultraviolet rays by flowing milk or the like through a thin film, which has a drawback in that the structure becomes complicated.

JP-A-9-940 Japanese Patent Laid-Open No. 9-8361 JP 9-38190 A JP 2004-663 A JP-T-2004-508162 JP-A-8-57476 [Applications of Genetical, Erythemal and Infrared Energy 1st. ed. 1946], 111 pages, author [Matthew Luckies], publisher [D. Van Nostrand Company, Inc. ] TOSHIBA REVIEW (Vol.11, No.9) 1951 Paper title "Sterilization and its application", page 1020

  The present invention uses ultraviolet light in a specific wavelength region, which is ultraviolet light at the boundary between near ultraviolet light and visible light, and is expected to have almost no bactericidal effect based on common sense from conventional ultraviolet light sterilization. Rather than uniformly radiating ultraviolet rays of a specific wavelength range emitted from the light, it is focused by a condensing lens to produce extremely strong ultraviolet intensity locally, which inactivates viruses due to ultraviolet rays and excels in colored liquids In addition to the sterilizing effect, particularly in the region where the ultraviolet intensity is focused and the ultraviolet intensity is extremely increased, the practical sterilizing effect has been achieved even in an extremely weak ultraviolet intensity area. In other words, using conventional ultraviolet light in a specific wavelength region where the sterilizing effect can hardly be expected from the common sense of conventional ultraviolet sterilization, and in contrast to the normal technical idea of uniformly irradiating with ultraviolet light, By focusing the light with a condensing lens and emitting extremely strong ultraviolet rays to specific areas, it is impossible to imagine from conventional ultraviolet sterilization not only in areas with extremely high ultraviolet intensity but also in areas with extremely low ultraviolet intensity. It realizes an excellent feature that can not be imagined from the conventional technology of realizing excellent virus inactivation and sterilizing effect of colored liquid, and the first important object of the present invention is the conventional common sense In applications where it is difficult to inactivate the virus by condensing near ultraviolet rays that are not expected to have a bactericidal effect to sterilize colored liquids and to irradiate ultraviolet rays uniformly, Also in the portion outside line it is not sufficiently illuminated to provide an ultraviolet sterilizer that can dramatically improve the bactericidal effects of liquids viruses and colored.

  Another important object of the present invention is that it is small, lightweight and has a degree of freedom in designing the shape, which is impossible in the past, and is energy-saving, highly safe, portable viruses and colored liquids. It is to provide an ultraviolet sterilizer that is not affected by the material surface, which is a drawback of an ultraviolet LED using a photocatalyst, and that is low in cost.

  The ultraviolet sterilizer which inactivates a virus with the ultraviolet-ray described in Claim 1 of this invention is equipped with LED which radiates | emits an ultraviolet-ray. The LED includes a light-emitting chip having a main light emission peak in a wavelength range of 360 to 380 nm and a condensing lens that focuses light emitted from the light-emitting chip, and the LED focuses and emits light emitted from the light-emitting chip by the condensing lens. .

  According to a second aspect of the present invention, an ultraviolet sterilization apparatus for sterilizing a colored liquid by irradiating ultraviolet light includes an LED that emits ultraviolet light. This LED includes a light-emitting chip having a main light emission peak in a wavelength range of 360 to 380 nm and a condensing lens that focuses light emitted from the light-emitting chip, and the LED focuses and emits light emitted from the light-emitting chip by the condensing lens. To do.

  In the ultraviolet sterilization apparatus of the present invention, with the LED condensing lens, the angle at which the directional characteristic of the light emission output focused and emitted becomes 50% of the radiation intensity on the center line is within 60 degrees from the center line. be able to. Furthermore, the directivity characteristic of the light emission output focused and radiated by the LED condensing lens can be such that the angle of 75% of the radiation intensity on the center line is within 35 degrees from the center line.

  In the ultraviolet sterilizer of the present invention, the LED condensing lens can radiate 80% or more of the luminescence energy radiated from the light emitting chip in a range of 60 degrees from the center line.

In the ultraviolet sterilizer of the present invention, the radiation intensity on the center line 1 cm away from the LED can be 300 mW / cm ² or more, preferably 500 mW / cm ² or more.

  In the ultraviolet sterilizer of the present invention, the main light emission peak of the LED can be in the wavelength range of 365 to 370 nm.

  The ultraviolet sterilization apparatus of this invention can make the half value width of the emission spectrum in the main light emission peak wavelength of LED into 5 nm or more and 15 nm or less.

  The ultraviolet sterilizer of the present invention can use an LED made of a gallium nitride compound semiconductor light emitting element.

  The ultraviolet sterilizer of the present invention can directly irradiate an object to be sterilized as a light source in which all or part of the light emitted from the LED has a sterilizing action, regardless of the presence or absence of a photocatalyst or a wavelength conversion material in the vicinity of the LED.

  The ultraviolet sterilizer according to the present invention is configured such that LEDs are mounted side by side on the front and / or back surface of a mounting member having a rod shape, a cylindrical shape, a box shape, a planar shape, a spherical shape, or an arbitrary shape, and the light emission of the LED is changed to the shape of the mounting member. Can be diverged around.

  The ultraviolet sterilization apparatus of the present invention has a sealing property and water resistance against water, and can incorporate an LED in a transparent container or capsule that transmits ultraviolet rays.

  The ultraviolet sterilization method according to claim 14 of the present invention is an ultraviolet sterilization method for radiating ultraviolet rays to a colored liquid, wherein riboflavin is added to the colored liquid, and the colored liquid to which riboflavin is added is 360 to Irradiate ultraviolet rays emitted from an LED having a main emission peak in a wavelength region of 380 nm.

  In the ultraviolet sterilization method of the present invention, a colored liquid can be used as milk. In the ultraviolet sterilization method of the present invention, the amount of riboflavin added can be preferably 0.5% by weight or more.

The ultraviolet sterilizer for viruses and colored liquids according to the present invention uses 360 to 380 nm ultraviolet light in a wavelength region where the sterilizing effect is considered to be extremely low, and further, in the part where the irradiation intensity of the ultraviolet light becomes extremely weak. However, the bactericidal effect of viruses and colored liquids can be dramatically improved. By the way, the main emission peak is 365 nm, the full width at half maximum is 10 nm, and an LED having a directivity characteristic in which the angle at which the radiant intensity is 50% is 50 degrees with respect to the center line is used. FIG. 6 shows the inactivation rate of the influenza virus and herpes virus in the directly irradiated part where the ultraviolet intensity is 250 mW / cm ² . As is clear from FIG. 6, the inactivation rate of the directly irradiated portion of influenza virus was about 85%, 100%, 100%, 100 in order after 5 minutes, 10 minutes, 20 minutes, and 30 minutes. %, And after only 10 minutes, an extremely excellent sterilizing effect is realized with an inactivation rate of 100%. Moreover, the inactivation rate of the directly irradiated part of herpesvirus is about 30%, 65%, and 90% in order after 10 minutes, 20 minutes, and 30 minutes, respectively, and an extremely excellent bactericidal effect is realized.

  Moreover, the inactivation rate of influenza virus will be in an excellent state not only in the direct irradiation part but also in the indirect irradiation part. The indirect irradiation portion is a portion that is in the direction of 80 degrees with respect to the center line of the LED and is 5 cm away from the direct irradiation portion, and the ultraviolet intensity is 1/100 or less of the direct irradiation portion. The inactivation rate of the influenza virus after 10 minutes of the indirect irradiation portion is about 70%, indicating an excellent inactivation rate. This means that the influenza virus is inactivated in the same way as the directly irradiated portion even in the indirectly irradiated portion where the ultraviolet irradiation intensity is almost 1/100 or less. The indirect irradiation portion uses the ultraviolet ray in the wavelength region that is extremely weak from the sterilizing power due to the characteristics showing the bactericidal effect in FIG. 1, and further directly reduces the ultraviolet intensity to 1/100 or less of the direct irradiation portion. The bactericidal effect comparable to is realized.

  Incidentally, from the sterilization characteristics shown in FIG. 1, the sterilization effect of 365 nm ultraviolet light is significantly reduced to 1/5000 compared to 260 nm ultraviolet light. Furthermore, the ultraviolet intensity of the indirectly irradiated portion is reduced to 1/100 or less of the directly irradiated portion. From this, theoretically, the sterilizing effect of the indirectly irradiated portion can hardly be expected. Nevertheless, the ultraviolet sterilization apparatus of the present invention has the effect of sufficiently inactivating the influenza virus even when irradiating 365 nm ultraviolet light with little sterilizing effect and further reducing the ultraviolet intensity to 1/100 or less. . For this reason, the apparatus that focuses and irradiates the 365 nm ultraviolet rays with the condenser lens can effectively inactivate the virus even in the indirect irradiation portion where the sterilization dose is extremely weak. That is, the ultraviolet sterilization apparatus of the present invention is expected to greatly improve the inactivation of the virus even in the portion where the ultraviolet rays are not directly irradiated. In this way, the extremely sterilizing effect is realized in the portion not irradiated with ultraviolet rays because the ultraviolet sterilizing device of the present invention focuses the ultraviolet rays having a main emission peak of 360 to 380 nm emitted from the LED, and localizes them. This is because, by irradiating with an extremely strong ultraviolet ray, the air becomes an environment inactivating the virus, and the air flows to inactivate the virus even in a portion not irradiated with the ultraviolet ray. That is, by locally irradiating the focused and strengthened ultraviolet light, the air is changed to a state in which the virus is inactivated, and this air inactivates the virus that is not directly irradiated with the ultraviolet light. For this reason, the ultraviolet sterilization apparatus of this invention implement | achieves the very outstanding characteristic which cannot be implement | achieved by the conventional apparatus that a virus can be inactivated effectively also in the part which does not irradiate an ultraviolet-ray. This is an extremely important characteristic for a virus ultraviolet sterilizer. This is because the ultraviolet sterilization apparatus has many applications in which it is practically impossible to uniformly irradiate the entire surface to be sterilized with ultraviolet rays.

  In the colored liquid, about 40% of Escherichia coli is killed by 30 minutes of ultraviolet irradiation in the directly irradiated portion of ultraviolet light, and about 30% of Escherichia coli is killed in 30 minutes of irradiation in the indirect irradiated portion. E. coli is not killed in milk irradiated with UVC ultraviolet rays under the same conditions by shortening the wavelength of the ultraviolet rays. Furthermore, when riboflavin is added to milk, the death rate of E. coli is remarkably increased to about 80% after 30 minutes of UV irradiation. Riboflavin is vitamin B2, so it can be added to milk and eaten together.

  In addition, since the ultraviolet sterilizer of the present invention is a small, light and energy-saving sterilizer, it can be installed in a narrow place where it is difficult to install with a conventional germicidal lamp, a place where it is difficult to supply a large amount of power, and it is usually a human being. Can be used conveniently. Further, since a photocatalyst is not essential, it is economical, there is no fear of a decrease in catalyst performance, and the bactericidal effect can be maintained for a long time.

  Furthermore, since the ultraviolet sterilizer of the present invention inactivates the virus using an ultraviolet LED having a main emission peak wavelength of 360 nm to 380 nm, the emission of the LED can be seen with a light purple color. This is because the shortest wavelength of visible light visible to the human eye is 380 nm. For this reason, the ultraviolet sterilizer of this invention has the characteristics which can confirm visually which part is irradiated and sterilized. It is also possible to easily determine whether or not it is sterilized with ultraviolet rays. For this reason, there is a feature that even in any use state, the required portions can be sterilized more effectively or evenly.

  Furthermore, since it uses ultraviolet light having a main light emission peak of 360 to 380 nm and has been known to have no bactericidal effect in the past, it emits light in a wavelength region close to visible light. The ideal feature is that it can be effectively sterilized while preventing adverse effects. Although the conventional germicidal lamp uses invisible ultraviolet rays, it is necessary to turn off the ultraviolet irradiation and stop the ultraviolet irradiation when a person is in the area. While checking the sterilization state, it is not necessary to turn on / off even when a person is present, and the sterilization effect can be exhibited by continuously lighting for 24 hours. Moreover, it can be installed without providing a special shielding material even in a place such as a wall that is visible to the human eye.

  Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify the ultraviolet sterilization apparatus and the sterilization method for embodying the technical idea of the present invention, and the present invention does not specify the ultraviolet sterilization apparatus and the sterilization method as follows. . Further, this specification does not limit the members shown in the claims to the members of the embodiments.

  The ultraviolet sterilizer which sterilizes a virus and a colored liquid shown in FIG. 2 includes an LED 1 as a light source that exhibits a sterilizing action. The LED 1 includes a light emitting chip that emits ultraviolet light having a main light emission peak in a wavelength range of 360 to 380 nm. More preferably, the main emission peak of ultraviolet rays emitted from the light emitting chip is in a narrower wavelength range of 365 to 370 nm. The LED 1 having the main emission peak in these wavelength regions is realized by a gallium nitride compound semiconductor light emitting element. The present invention includes an LED 1 whose main emission peak has a very limited wavelength region. The LED 1 uses the wavelength region of the main emission peak as a boundary region between visible light and near ultraviolet light. This is because visible light is in a wavelength region of 380 nm or more and near ultraviolet light is in a wavelength region of 300 nm or more. Further, the LED 1 preferably has a half width of the emission spectrum of 5 nm or more and 15 nm or less. The full width at half maximum specifies the emission spectrum of the LED 1.

  An LED having a half-value width of 15 nm or more cannot radiate ultraviolet rays only in a narrow wavelength region and is dispersed in a wavelength region having a small sterilizing effect. On the other hand, an LED whose half width is narrower than 5 nm cannot see the ultraviolet rays emitted with the intensity of visible light being reduced. Therefore, the half-value width of the LED is specified in the aforementioned range so that the ultraviolet rays emitted from the LED can be effectively sterilized while visually checking.

  The LED 1 also includes a condenser lens that focuses the light emitted from the light emitting chip. The LED 1 converges the light emitted from the light emitting chip with a condenser lens and radiates the light to the outside. Therefore, the light emitted from the LED 1 to the outside is locally focused and the radiation intensity is significantly increased. In particular, the LED 1 that focuses the light emitted by the condenser lens has a strong radiant intensity at the center line, and the radiant intensity decreases as it deviates from the center line.

  FIG. 3 and FIG. 4 show the directivity characteristics of the LED that converges and emits the light from the light emitting chip with the condenser lens. The LED of FIG. 3 irradiates ultraviolet rays within a range of about 8 degrees with respect to the center line. The radiant intensity emitted in the direction of 8 degrees with respect to the center line is 50% on the center line. The LED of FIG. 4 emits ultraviolet rays within a range of about 47 degrees with respect to the center line. The intensity of radiation emitted in the direction of 47 degrees with respect to the center line is 50% on the center line. The LED can sharpen the directivity characteristic of irradiating ultraviolet rays more strongly in the direction of the center line, in other words, sharpen the directivity characteristics, and focus the ultraviolet rays in a narrower region, thereby increasing the ultraviolet intensity of the irradiation part. Therefore, the LED used in the ultraviolet sterilizer of the present invention preferably has an angle that is 50% of the radiation intensity on the center line within 60 degrees from the center line. In addition, the LED preferably has an angle of dropping to 75% of the radiation intensity on the center line within 35 degrees from the center line. Further, the LED preferably emits 80% or more of the emission energy emitted from the light emitting chip while being focused in a range of 60 degrees from the center line.

Furthermore, the output and directivity characteristics of the LED focus strong ultraviolet rays so that the radiation intensity on the center line 1 cm away from the tip of the LED is, for example, 300 mW / cm ² or more, preferably 500 mW / cm ² or more. To change the air into a strong sterilizing effect.

  Further, the LED irradiates the sterilization target indirectly by reflecting it without irradiating the sterilizing ultraviolet light directly irradiating the sterilization target virus or colored liquid such as milk. You can also. Further, the photocatalyst can be irradiated with a part of the ultraviolet rays emitted from the LED, and sterilized by a synergistic effect with the photocatalyst. Furthermore, a wavelength conversion material such as a phosphor can be irradiated with a part of the ultraviolet rays, and the wavelength of the ultraviolet rays can be converted with the wavelength conversion material. The ultraviolet sterilization apparatus of the present invention has a strong effect of activating a photocatalyst with ultraviolet rays emitted from LEDs, and when a photocatalyst is used in combination, a synergistic effect of ultraviolet rays and active oxygen can be used. However, when a photocatalyst is used in combination, the dispersion and deterioration of the catalyst performance, as well as material costs and processing costs increase. Therefore, effective sterilization can be realized by irradiating a virus or colored liquid with ultraviolet rays having a specific wavelength emitted from the LED as efficiently as possible without using a photocatalyst or a wavelength conversion material.

  Furthermore, the ultraviolet sterilizer arranges a plurality of LEDs side by side on the surface and / or the back surface of a planar, rod-shaped, cylindrical, box-shaped, spherical or arbitrary-shaped mounting member, thereby radiating ultraviolet rays emitted from the LEDs. Depending on the shape of the mounting member, it can be emitted to the surroundings to irradiate a virus or colored liquid with a specific irradiation pattern.

  Moreover, the ultraviolet sterilizer has a hermeticity and waterproofness against water, and can incorporate the LED in a transparent container or capsule that transmits ultraviolet rays emitted from the LED. This ultraviolet sterilizer can be conveniently used for applications where water droplets adhere or moisture in the air is condensed. The ultraviolet sterilization apparatus having this structure can be used more conveniently by incorporating a power supply device such as a battery together with an LED in a watertight container. In addition, the ultraviolet sterilizer has a structure in which a plurality of LEDs are gathered and assembled with the light emitting surface of the light emitting element on the outside and the substrate side facing inward to radiate ultraviolet rays emitted from the LEDs in all directions. It is small and can realize a bactericidal effect over a wide range.

(Production of UV sterilizer)
As shown in FIG. 5, the ultraviolet sterilizer disposes two rows of LEDs 1 at a distance of 10 cm on a planar substrate 2. The LED 1 is fixed to the lower surface of the base 2 in a posture facing downward. LED1 (manufactured by Nichia Corporation) has a main emission peak wavelength of 365 nm, an emission spectrum half width of 10 nm, an optical output of 100 mW, and directivity shown in FIG. Two LEDs 1 are connected in series and connected to a power source 3 (PAS40-9 manufactured by Kikusui Electronics Corporation). The power source 3 is a DC stabilized power source that stabilizes the output. This power supply 3 is used in a constant current mode in which a current of 500 mA is applied at a rated current where the light output of the LED 1 is 100 mW. As shown in the figure, the sterilization object 4 is arranged in a direct irradiation part directly under 2 cm from the lower end of the LED 1 and an indirect irradiation part in the middle of the two LEDs 1. The ultraviolet radiation intensity at the directly irradiated portion is 250 mW / cm ² . The radiant intensity of the ultraviolet rays in the indirect irradiation portion is arranged in a direction in which almost no ultraviolet rays are radiated from the directivity characteristics of the LED shown in FIG.

It is confirmed by the following test that the above ultraviolet sterilizer has excellent effects on virus inactivation and colored liquid sterilization.
(Indicator virus of this experiment)
Influenza virus and herpes virus are used as target viruses.
(How to make virus solution)
Herpes virus is infected with Vero cells and influenza virus is infected with MDCK cells, amplified, and amplified from the cell culture supernatant, and the sample virus solution is placed in a 96-well plate.

(I radiate ultraviolet rays from an ultraviolet sterilizer)
150 μL of the virus solution is placed in a sterilized well plate (Becton Dickinson Labware), placed in the direct irradiation portion and the indirect irradiation portion, and irradiated with ultraviolet rays for 5, 10, 20, and 30 minutes. Ultraviolet rays are irradiated through a polystyrene lid. In order to show a statistically significant difference, experiments are performed three times at different conditions for each condition.

(Measurement of virus activity after UV irradiation with UV sterilizer)
The measurement of herpes virus activity after ultraviolet irradiation is according to the following steps.
(1) Vero cells cultured for 3 days are prepared in a 6-well plate.
(2) To the Vero cells of this 6-well plate, the virus solution that has been subjected to LED irradiation is added at 200 μl / well. On the other hand, a virus solution not irradiated with ultraviolet rays is similarly added to Vero cells in a 6-well plate at 200 μl / well, and this is used as a control.
(3) Leave at 37 ° C. for 1 hour. At this time, tilt the virus solution evenly every 15 minutes.
(4) After removing the virus solution, 2 ml of a medium for stratification (0.5% methylcellulose, 2 mM glutamine, 2.2 g / L stratification, 1% FBS, 1 μg / ml fungizone, 2 × MEM) was added to each well. Leave at ℃ for 3 days.
(5) After adding 0.5 ml of crystal violet solution (10% formalin, 0.5% crystal violet) to each well and allowing to stand at room temperature for 30 minutes, the solution was removed and the number of plaques was measured to determine the infectivity titer (PFU / ml).

The inactivation rate is expressed as an infectivity titer rate relative to a control (a sample not irradiated with ultraviolet rays). For example, if the number of plaques in the control is 1 × 10 ⁸ PFU / ml and the infectivity titer after irradiation with ultraviolet rays is 0.5 × 10 ⁸ PFU / ml, the virus inactivation rate is 50%. .

The measurement of influenza virus activity after ultraviolet irradiation is based on the following steps.
(1) Prepare MDCK cells cultured in a 6-well plate for 3 days.
(2) MDCK cells are washed with 10% TPB-MEM (10% TPB, 2 mM glutamine, 2.2 g / L overlay, 1 μg / ml fungizone, 0.1 mg / ml streptomycin, 2 × MEM).
(3) The virus solution that has been subjected to LED irradiation is added to the MDCK cells of this 6-well plate at 200 μl / well. On the other hand, a virus solution not irradiated with ultraviolet rays is similarly added to MDCK cells of a 6-well plate at 200 μl / well, and this is used as a control.
(3) Leave at 37 ° C. for 1 hour. At this time, tilt the virus solution evenly every 15 minutes.
(4) After removing the virus solution, the cells were washed again with 10% TPB-MEM, and then the medium for stratification containing trypsin (0.5% methylcellulose, 2 mM glutamine, 2.2 g / L stratification, 10% TPB, 1 μg / ml) 2 ml of fungizone, 2 × MEM, 1 μg / ml trypsin) is added to each well and left at 37 ° C. for 3 days.
(5) After adding 0.5 ml of crystal violet solution (10% formalin, 0.5% crystal violet) to each well and allowing to stand at room temperature for 30 minutes, the solution was removed and the number of plaques was measured to determine the infectivity titer (PFU / ml).

The inactivation rate is expressed as an infectivity value rate relative to the control. For example, if the control plaque is 1 × 10 ⁸ PFU / ml and the infectivity after irradiation with ultraviolet rays is 0.8 × 10 ⁸ PFU / ml, the inactivation rate is 80%.

  The inactivation rate of herpes virus and influenza virus by ultraviolet rays by the above method is as shown in FIG. From this figure, the inactivation rate of influenza virus can be made 100% with only 10 minutes of UV irradiation. In addition, herpes virus can be inactivated very effectively at 65% by irradiation for 20 minutes and 90% by irradiation for 30 minutes.

The sterilization rate of milk, which is a colored liquid, is measured by the following process.
(Creation method of culture solution)
LB medium is used for culture of bacteria used as a sterilization target. A method for preparing a liquid medium and an agar medium (LB plate) will be described below.
-Composition of LB medium;
trytone …………………… 1% (10 g / l)
yeast extract …… 0.5% (5 g / l)
NaCl ……………………………… 1% (10 g / l)
In the case of an agar medium, agar is added to this so that it may become 1.5% (W / V).

  The LB medium is dissolved in deionized water and then sterilized by autoclaving (121 ° C., 20 minutes). For the agar medium, add a stirrer bar, stir uniformly with a stirrer after autoclaving, and cool to about 65 ° C. Dispense an appropriate amount into a 10 cm disposable plastic petri dish (Eiken Equipment Co., Ltd.) Set to solidify.

(Indicator bacteria in this experiment)
A non-pathogenic Escherichia coli DH5α strain is used as an indicator bacterium for sterilization. In order to examine the bactericidal effect of the sterilizer produced in the experiment on Escherichia coli, the Escherichia coli is cultured for 16 hours in a 37 ° C. shaking incubator using 5 ml of LB medium.

(Method for adjusting the number of bacteria)
In the experiment, a plate culture method is used to measure the number of bacteria. This is to count the number of colonies produced by smearing and culturing a certain amount of bacterial solution on an agar medium. A colony is a group of the same bacteria, and one cell cannot be seen with the naked eye, but the colony can be confirmed with the naked eye. To adjust the number of bacteria, first measure the approximate number of bacteria with a spectrophotometer, and then perform serial dilution.

Spectrophotometer Assume that the intensity of light having a certain wavelength changes from I0 (incident light intensity) to I (transmitted light intensity) while passing through a solution layer of a substance. At this time, the ratio of I to I0 (I / I0) is referred to as transmittance (t; transmittance), and the transmittance expressed as a percentage is referred to as transmittance (T; percent transmittance). Optical density (OD) is the common logarithm of the inverse of transmission.

T = (I / I0) × 100, A = −logt = log (I / I0) = O. D.
In order to measure the number of E. coli, measurement is performed using light having a wavelength of 600 nm. The result is written as OD ₆₀₀ .
In the experiment, OD ₆₀₀ is measured using a bacterial solution as a sample and PBS [phosphate-buffeved saline (hereinafter referred to as PBS)] as a control. A dilute solution (PBS) is mixed with the bacterial solution, and the OD ₆₀₀ value is adjusted to 1.0. The bacterial solution adjusted to OD ₆₀₀ = 1.0 is used as a stock solution, and this is serially diluted to 10 ⁶ times with milk (no component adjustment). 100 μl of the sample stock solution is mixed with 900 μl of milk to make a 10-fold diluted solution, and further 100 μl of 10-fold diluted solution is mixed with milk to make a 100-fold diluted solution. In the same manner, dilution was carried out sequentially to adjust up to 6 levels.

(Measurement of the number of bacteria before the UV sterilizer irradiates UV rays)
As a result of preliminary experiments, the bacterial solution diluted 10 ⁵ times and 10 ⁶ times is suitable for the measurement of the number of bacteria before UV irradiation, so 100 μl of each was dropped onto the LB plate and smeared evenly with a congeal rod, 37 ° C. Incubate for 16 hours. Thereafter, the number of colonies appearing on the LB agar medium is measured. To count the number of colonies, count all colonies with the naked eye from the back of the petri dish. The number of bacteria is obtained by multiplying the number of colonies in each dilution factor by the dilution factor and averaging.

(I radiate ultraviolet rays from an ultraviolet sterilizer)
150 μl of the bacterial solution prepared by the above-described adjustment method is placed in a sterilized well plate (Becton Dickinson Labware), placed in a direct irradiation part and an indirect irradiation part, and irradiated with ultraviolet rays for 30 minutes. Ultraviolet rays are irradiated through a polystyrene lid. In order to show a statistically significant difference, experiments are performed three times at different conditions for each condition.

(Measurement of the number of bacteria after irradiating ultraviolet rays with an ultraviolet sterilizer)
For the measurement of the number of bacteria after ultraviolet irradiation, the bacterial solution after ultraviolet irradiation is taken out and diluted 10-fold or 100-fold with PBS. Then, 100 μl each of the undiluted (stock solution), 10-fold diluted, and 100-fold diluted bacterial solutions is dropped onto the LB plate and smeared evenly with a large stick. After culturing this at 37 ° C. for 16 hours, the number of colonies appearing on the LB agar medium is measured, and the number of remaining bacteria after ultraviolet irradiation under each condition is calculated.

In order to evaluate the bactericidal effect of ultraviolet irradiation by LED1, the number of bacteria after ultraviolet irradiation is divided by the number of bacteria before ultraviolet irradiation, and the survival rate P of bacteria and the lethality rate Q (bactericidal rate) of bacteria are calculated by the following formulas: To do.
P = (N / N0) × 100, Q = 100−P
P: Bacterial survival rate, Q: Bacterial lethality rate,
N0: Number of bacteria before UV irradiation, N: Number of surviving bacteria after UV irradiation

(Relationship between UV irradiation time and sterilization rate)
When the ultraviolet irradiation time is 30 minutes, as shown in FIG. 7, the sterilization rate of the directly irradiated portion of E. coli is about 40%, and the sterilization rate of the indirect irradiated portion is about 30%.

  The number of bacteria before ultraviolet irradiation is about 4000 (SD + -800). The temperature of the heat radiation plate of the ultraviolet irradiator after the experiment is about 36 ° C., and the temperature of the bacterial solution at the end of the experiment is about 35 ° C. By irradiating with ultraviolet rays for 30 minutes, the sterilization rate is 30 to 40% in both the direct irradiation portion and the indirect irradiation portion.

  About 40% of Escherichia coli is killed in the directly irradiated portion with an ultraviolet irradiation time of 30 minutes, and about 30% of Escherichia coli is killed in the indirectly irradiated portion. E. coli was not killed by milk irradiated with UVC ultraviolet rays under the same conditions while shortening the wavelength of the ultraviolet rays.

  Similar experiments, except that 1% by weight riboflavin is added to milk, the kill rate of E. coli increases from 40% to 80%. When the amount of riboflavin added is less than 0.3% by weight, the effect of addition is not expected. Moreover, even if the addition amount of riboflavin is more than 2% by weight, the effect of addition is reduced. Therefore, the amount of riboflavin added is preferably 0.1 to 2% by weight, more preferably 0.3 to 1% by weight.

It is a graph which shows the wavelength characteristic of an ultraviolet sterilization effect | action. It is a schematic block diagram of the ultraviolet sterilizer concerning one Example of this invention. It is a figure which shows an example of the directional characteristic of LED. It is a figure which shows another example of the directional characteristic of LED. It is a schematic block diagram of the ultraviolet sterilizer used for the Example of this invention. It is a graph which shows the inactivation rate of the direct irradiation part of the influenza virus and herpes virus in the Example of this invention. It is a graph which shows the disinfection rate of the milk in the Example of this invention.

Explanation of symbols

1 ... LED
2 ... Base 3 ... Power supply 4 ... Sterilization target

Claims (16)

  An ultraviolet sterilizer for viruses that inactivates viruses with ultraviolet rays, comprising an LED that emits ultraviolet rays, the LED having a light emitting chip having a main light emission peak in a wavelength range of 360 to 380 nm, and the ultraviolet light of the light emitting chip. And a condensing lens for focusing the emitted light, and the LED sterilizes the light emitted from the light emitting chip by the condensing lens and emits it.   An ultraviolet sterilization apparatus for colored liquids that sterilizes by irradiating colored liquid with ultraviolet rays, and includes an LED that emits ultraviolet rays, and the LED has a light emitting chip having a main light emission peak in a wavelength range of 360 to 380 nm; An ultraviolet sterilizer comprising a condensing lens for converging the light emitted from the light emitting chip, and the LED condensing the light emitted from the light emitting chip by the condensing lens for emission.   The directional characteristic of the light emission output focused and radiated by the condensing lens of the LED is such that an angle at which 50% of the radiation intensity on the center line is within 60 degrees from the center line. UV sterilizer.   The directional characteristic of the light emission output focused and radiated by the condensing lens of the LED is an angle at which 75% of the radiation intensity on the center line is within 35 degrees from the center line. UV sterilizer.   The ultraviolet sterilizer according to claim 1 or 2, wherein the condensing lens of the LED focuses and emits 80% or more of the emission energy emitted from the light emitting chip in a range of 60 degrees from the center line. The ultraviolet sterilizer according to claim 1 or 2, wherein the radiation intensity on the center line 1 cm away from the LED is 300 mW / cm ² or more. The ultraviolet sterilizer according to claim 1 or 2, wherein the radiation intensity on the center line 1 cm away from the LED is 500 mW / cm ² or more.   The ultraviolet sterilizer according to claim 1 or 2, wherein the main light emission peak of the LED is in a wavelength range of 365 to 370 nm.   The ultraviolet sterilizer according to any one of claims 1 to 4, wherein the full width at half maximum of the emission spectrum at the main emission peak wavelength of the LED is 5 nm or more and 15 nm or less.   9. The ultraviolet sterilizer according to claim 1, wherein the LED comprises a gallium nitride compound semiconductor light emitting element.   11. The sterilization target is directly irradiated regardless of the presence or absence of a photocatalyst or a wavelength conversion material in the vicinity of the LED as a light source in which all or part of the light emission of the LED exerts a sterilizing action. The ultraviolet sterilizer described in any one.   When LEDs are mounted side by side on the front and / or back of a mounting member having a rod shape, tube shape, box shape, flat shape, spherical shape or any shape, the light emission of the LED is emitted to the surroundings according to the shape of the mounting member. The ultraviolet sterilizer according to any one of claims 1 to 11, wherein the ultraviolet sterilizer is configured as described above.   13. The ultraviolet sterilizer according to claim 1, wherein the LED is incorporated in a transparent container or capsule that has water-tightness and waterproofness and transmits ultraviolet rays. An ultraviolet sterilization method for sterilizing a colored liquid by irradiating with ultraviolet rays,
An ultraviolet ray of a colored liquid, characterized in that riboflavin is added to a colored liquid, and the colored liquid to which riboflavin is added is irradiated with ultraviolet rays emitted from an LED having a main emission peak in a wavelength range of 360 to 380 nm. Sterilization method.   The ultraviolet sterilization method according to claim 14, wherein the colored liquid is milk.   The method for ultraviolet sterilization of a colored liquid according to claim 14, wherein 0.5% by weight or more of riboflavin is added to the colored liquid.

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