Patent Grant
12128150
The present invention relates to an ultraviolet irradiation device.
It is conventionally known that DNA exhibits the highest absorption characteristic near a wavelength of 260 nm. A low-pressure mercury lamp shows a high emission spectrum near a wavelength of 254 nm. Therefore, conventionally, a technology of sterilizing by irradiating ultraviolet light from the low-pressure mercury lamp is widely used (refer to, for example, Patent Document 1).
However, light in the vicinity of the wavelength of 254 nm might adversely affect a human body when being irradiated to the human body. Following Patent Document 2 discloses a technology of performing sterilization while avoiding a risk to the human body by using ultraviolet light of a wavelength of 207-220 nm in a medical site.
However, Patent Document 2 mentioned above only refers that the ultraviolet light of the wavelength of 207-220 nm may be used for the sterilization in the medical site, and it is not assumed that general consumers generally perform the sterilization treatment in a non-medical site. For example, when the general consumers perform the sterilization in places in the home where bacteria are considered to be relatively easily grow such as toilet, kitchen, bathroom, and in shoes, conditions are imposed such as a size easy to carry and a minimal adverse effect on the human body.
However, at present, actually, no ultraviolet irradiation device suitable for sterilization applications that satisfies the above-described conditions has been proposed.
In view of the above-described problems, an object of the present invention is to provide a compact ultraviolet irradiation device in which a degree of an adverse effect on the human body is suppressed.
An ultraviolet irradiation device according to the present invention is provided with:
In this specification, the “main emission wavelength” indicates a wavelength λi in a wavelength range Z(λi) showing integrated intensity of 40% or larger with respect to the total integrated intensity in an emission spectrum in a case where a wavelength range Z(λ) of ±10 nm with respect to a certain wavelength λ, is defined on the emission spectrum. For example, in a light source having an extremely narrow half-value width and showing light intensity only at a specific wavelength such as an excimer lamp in which a luminescent gas containing KrCl, KrBr, and ArF is sealed, a wavelength having the highest relative intensity (main peak wavelength) may be usually made the main emission wavelength.
In this specification, the description that the optical filter “substantially transmits the ultraviolet light” is intended to mean that intensity of the ultraviolet light transmitted through the optical filter is 60% or larger of the intensity of the ultraviolet light incident on the optical filter. In this specification, the description “not substantially transmit the ultraviolet light” is intended to mean that the intensity of the ultraviolet light transmitted through the optical filter is less than 20% of the intensity of the ultraviolet light incident on the optical filter.
Note that the optical filter may substantially reflect the ultraviolet light of the wavelength of 240-300 nm. Here, in this specification, the description “substantially reflects the ultraviolet light” is intended to mean that the intensity of the ultraviolet light reflected by the optical filter is 80% or more of the intensity of the ultraviolet light incident on the optical filter.
Transmittance and reflectance of the ultraviolet light of the optical filter actually change depending on an incident angle of the ultraviolet light incident on the optical filter. Note that, the incident angle is the angle between the normal of the incident surface of the optical filter and the ultraviolet light incident on the incident surface of the optical filter. Here, the ultraviolet light emitted from the excimer lamp travels with a certain divergence angle; among all the traveling light rays, intensity of the light ray traveling at an incident angle in the vicinity of 0° with respect to a light emission surface is the strongest, and the intensity decreases as the divergence angle is farther from 0°. Therefore, the optical filter having the transmittance of 60% or larger with respect to the intensity of the ultraviolet light incident on the optical filter at the incident angle of 20° or smaller may be treated as the filter that substantially transmits the ultraviolet light. Similarly, the optical filter exhibiting the transmittance of less than 20% with respect to the intensity of the ultraviolet light incident on the optical filter at the incident angle of 20° or smaller may be treated as the filter that does not substantially transmit the ultraviolet light. Similarly, the optical filter exhibiting the reflectance of 90% or larger with respect to the intensity of the ultraviolet light incident on the optical filter at the incident angle of 20° or smaller may be treated as the filter that substantially reflects the ultraviolet light.
The ultraviolet irradiation device is provided with the first electrode and the second electrode in contact with the outer surface of the luminous tube of the excimer lamp. These electrodes are in contact with the outer surface of the luminous tube of the excimer lamp in positions separated from each other in a tube axis direction of the excimer lamp. Therefore, the excimer lamp may discharge by a simple straight tube type structure, so that it is not necessary to adopt a structure in which double tube bodies are concentrically provided and a luminescent gas is sealed between an inner tube and an outer tube, a so called “double tube structure” generally used as a conventional excimer lamp.
As an example, a size of the luminous tube of the excimer lamp provided on the ultraviolet irradiation device is such that a length in the tube axis direction (second direction) is 15-200 mm, and an outer diameter is 2-16 mm.
In the excimer lamp that emits the ultraviolet light, the main emission wavelength of which belongs to the first wavelength band, also, ultraviolet light in a wavelength band (wavelength of 240-300 nm) that may affect the human body may be emitted although intensity thereof is extremely small.
With reference to
As described above, in the ultraviolet irradiation device according to the present invention, the optical filter that substantially transmits the ultraviolet light in the first wavelength band and substantially reflects the ultraviolet light of the wavelength of 240-300 nm is arranged on a light extraction surface side. Therefore, components of a wavelength of 240-300 nm contained in the ultraviolet light emitted from the excimer lamp are substantially reflected by the optical filter, so that the amount of the light extracted out of the ultraviolet irradiation device decreases. That is, by providing such optical filter, an amount of light extracted to the outside further decreases (although they are originally the components of the wavelength band of a small light output), so that the effect on the human body is further suppressed.
By the way, as described above, transmittance and reflectance of the ultraviolet light of the optical filter change depending on the incident angle of the ultraviolet light incident on the optical filter. Even in the ultraviolet light of the first wavelength band, which are supposed to be extracted from the ultraviolet irradiation device, when the incident angle on the optical filter becomes extremely large, the transmittance decreases and the reflectance increases. Therefore, out of the ultraviolet light in the first wavelength band emitted from the excimer lamp, a part of the ultraviolet light incident on the optical filter at a relatively large incident angle (for example, 30° or larger) is reflected by the optical filter to be returned to the excimer lamp side. As a result, this is not extracted out of the ultraviolet irradiation device, and light extraction efficiency is lowered to a certain extent as compared with a case where the optical filter is not provided.
A part of the reflected light may be irradiated to a housing (casing) of the lamp house, and the lamp house may deteriorate.
In contrast, the ultraviolet irradiation device according to the present invention is provided with a reflecting surface exhibiting reflectivity with respect to ultraviolet light, the reflecting surface located outside a luminous tube and inclined with respect to the light extraction surface as seen in the second direction, that is, in the tube axis direction of the luminous tube of the excimer lamp. The ultraviolet light emitted from the excimer lamp travels toward the optical filter with a predetermined divergence angle. Here, when ultraviolet light traveling with a large divergence angle is incident on the reflecting surface, this is reflected by the reflecting surface to change the travel direction. Since the reflecting surface is formed of the surface inclined with respect to the light extraction surface, the incident angle at the time of incidence on the optical filter after reflection by the reflecting surface decreases.
As a result, a proportion of the ultraviolet light transmitted through the optical filter increases, an output of the ultraviolet light in the first wavelength band extracted from the ultraviolet irradiation device increases, and an effect of suppressing the degree of deterioration of the lamp house is obtained.
Note that, the description “the optical filter is arranged on the light extraction surface” includes a case where the optical filter is arranged in a position separated from the light extraction surface at a minute distance (for example, a few millimeters to dozen millimeters) in the first direction in addition to a case where the optical filter is arranged so as to be completely integral with the light extraction surface.
The first electrode may be a first electrode block in the shape of a block and a the second electrode may be a second electrode block in the shape of a block, and at least one of the first electrode block and the second electrode block may include a tapered surface forming the reflecting surface in a position away from the excimer lamp in a third direction orthogonal to the first direction and the second direction.
That is, the tapered surface forming the reflecting surface may be a part of the first electrode block or the second electrode block. In this case, both the first electrode block and the second electrode block are preferably made of a material exhibiting reflectivity with respect to the ultraviolet light in the first wavelength band (Al, Al alloy, stainless steel and the like). Furthermore, it is more preferable that both the first electrode block and the second electrode block include the tapered surface.
According to such a configuration, since the ultraviolet light in the first wavelength band traveling from the excimer lamp with a large divergence angle is reflected by both the electrode blocks, an amount of light with a reduced incident angle on the optical filter increases. As a result, the light extraction efficiency may be further improved, and the effect of suppressing the degree of deterioration of the lamp house is enhanced.
The ultraviolet irradiation device may be provided with the plurality of excimer lamps arranged separated from each other in the third direction, in which
the first electrode block and the second electrode block may be arranged so as to straddle the plurality of excimer lamps while being in contact with the outer surface of the luminous tube of each of the plurality of excimer lamps, and the tapered surface may be at least formed in a position interposed between the plurality of excimer lamps adjacent to each other in the third direction as seen in the second direction.
A part of the tapered surface may be located closer to the light extraction surface than the excimer lamp in the first direction. According to such configuration, it is possible to reflect the ultraviolet light that would have been incident on the optical filter at an incident angle with a low proportion of transmission (transmittance) through the optical filter if there is no tapered surface, thereby further improving the amount of light that may be incident on the optical filter at an incident angle with a high proportion of transmission through the optical filter.
The tapered surface preferably has an angle of 10°-50° and more preferably has an angle of 20°-40° from the first direction as seen in the second direction.
According to the present invention, a compact ultraviolet irradiation device in which the degree of the adverse effect on the human body is suppressed is achieved.
An embodiment of an ultraviolet irradiation device according to the present invention is described with reference to the drawings as appropriate. Note that the following drawings are schematically illustrated, and a dimensional ratio on the drawing and an actual dimensional ratio do not always match. Furthermore, the dimensional ratios do not always the same between the drawings.
In each of following drawings, it is illustrated with reference to an X-Y-Z coordinate system in which an extraction direction of ultraviolet light L1 is an X direction, and a plane orthogonal to the X direction is a YZ plane. In further detail, as described later with reference to
In the following description, in a case where positive and negative directions are distinguished from each other when expressing the direction, they are represented with positive and negative signs such as a “+X direction” and a “−X direction”. In a case of expressing the direction without distinguishing between positive and negative directions, this is simply represented as the “X direction”. That is, in this specification, in a case where it is simply represented as the “X direction”, both the “+X direction” and “−X direction” are included. The same applies to the Y direction and the Z direction.
As illustrated in
In this embodiment, as illustrated in
As illustrated in
The first electrode block 11 and the second electrode block 12 are arranged in positions separated from each other in the Y direction. As illustrated in
Note that the first electrode block 11 and the second electrode block 12 are made of conductive materials, preferably materials exhibiting reflectivity with respect to the ultraviolet light L1 in a first wavelength band. As an example, both the first electrode block 11 and the second electrode block 12 are formed of Al, Al alloy, stainless steel and the like.
The excimer lamp 3 includes the luminous tube a tube axis direction of which is the Y direction, and the outer surface of the luminous tube of the excimer lamp 3 is in contact with each of the electrode blocks (11, 12) in positions separated from each other in the Y direction. A luminescent gas 3G is sealed in the luminous tube of the excimer lamp 3. When a high-frequency AC voltage of, for example, about 10 kHz to 5 MHz is applied between the electrode blocks (11, 12), the voltage is applied to the luminescent gas 3G via the luminous tube of the excimer lamp 3. At that time, discharge plasma is generated in a discharge space in which the luminescent gas 3G is sealed, an atom of the luminescent gas 3G is excited to enter an excimer state, and excimer light emission is generated when this atom shifts to a ground state.
The luminescent gas 3G is made of a material that emits the ultraviolet light L1, a main emission wavelength of which belongs to the first wavelength band of 190-225 nm at the time of excimer light emission. As an example, the luminescent gas 3G contains KrCl, KrBr, and ArF. Note that, in addition to the above-described gas types, an inert gas such as argon (Ar) or neon (Ne) may also be mixed.
For example, in a case where the luminescent gas 3G contains KrCl, the excimer lamp 3 emits the ultraviolet light L1 the main peak wavelength of which is in the vicinity of 222 nm. In a case where the luminescent gas 3G contains KrBr, the excimer lamp 3 emits the ultraviolet light L1 the main peak wavelength of which is in the vicinity of 207 nm. In a case where the luminescent gas 3G contains ArF, the excimer lamp 3 emits the ultraviolet light L1 the main peak wavelength of which is in the vicinity of 193 nm. A spectrum of the ultraviolet light L1 emitted from the excimer lamp 3 in which the luminescent gas 3G contains KrCl is as described above with reference to
As illustrated in
The optical filter 21 having a characteristic illustrated in
According to the optical filter 21 illustrated in
As described above, the optical filter 21 showing different transmittance depending on the wavelength of the incident ultraviolet light L1 is realized by a multilayer film composed of a plurality of materials having different refractive indices. In contrast, in a case where the optical filter 21 is formed of the plurality of dielectric multilayer films having different refractive indices, the transmittance inevitably changes depending on the incident angle θ of the ultraviolet light L1 with respect to the optical filter 21. As a result, as illustrated in
Note that, out of the ultraviolet light L1, a part of the ultraviolet light L1 not transmitted through the optical filter 21 is reflected by the optical filter 21.
According to the optical filter 21 illustrated in
Next, an effect of including the tapered surfaces (11b, 12b) of the electrode blocks (11, 12), respectively is described with reference to the drawings.
The ultraviolet light L1 emitted from each excimer lamp 3 travels toward the optical filter 21 with a predetermined divergence angle. Therefore, out of the ultraviolet light L1, as for ultraviolet lights (L1b, L1c) having a relatively small incident angle with respect to the optical filter 21, components in the vicinity of the main peak wavelength are substantially transmitted through the optical filter 21. However, as for ultraviolet light L1a having a relatively large incident angle with respect to the optical filter 21, a certain proportion of the ultraviolet light L1a is reflected by the optical filter 21 even in a case of the components in the vicinity of the main peak wavelength. Therefore, a phenomenon occurs that out of the ultraviolet light L1 emitted from each excimer lamp 3, a part of the components in the vicinity of the main peak wavelength being the wavelength band that is expected to be extracted cannot be extracted to the outside.
In contrast, as in this embodiment, since the first electrode block 11 is provided with the tapered surface 11b, as illustrated in
Note that, although the first electrode block 11 is described as an example in
An effect of taper angles of tapered surfaces (11a, 11b) of electrode blocks (11, 12), respectively, on illuminance of ultraviolet light L1 extracted from an ultraviolet irradiation device 1 was examined.
(Common Condition)
Four excimer lamps 3 were prepared in which a mixed gas of Kr, Cl2, Ar, and Ne was sealed as a luminescent gas 3G in a tube body having a length of 70 mm in a tube axis direction (Y direction) and an outer diameter of φ6 mm. Then, these four excimer lamps 3 were brought into contact with the electrode blocks (11, 12) made of Al arranged so as to be separated from each other by 7 mm in the Y direction. Note that a separation distance between the excimer lamps 3 in a Z direction was set to 14 mm.
Under the above-described conditions, an AC voltage of a peak-to-peak value of about 4 kV and a frequency of 70 kHz was applied between the electrode blocks (11, 12) to generate dielectric barrier discharge for each excimer lamp 3, and illuminance in the center position of the four excimer lamps 3 away from a light extraction surface 10 by 20 mm in a +X direction was measured with an illuminometer. Note that an optical filter 21 having a transmission spectrum illustrated in
As the electrode blocks (11, 12), a plurality of types having different taper angles φ illustrated in
Note that, for comparison, illuminance of a case where the electrode blocks having a taper angle φ of 0°, that is, the electrode blocks not provided with the tapered surfaces (11b, 12b) as is the case with an electrode block 111 illustrated in
The results are illustrated in Table 1 and
According to Table 1 and
Especially, in a case where the taper angle φ is 10°-50°, illuminance increase of 3% or more is realized as compared with a case of using the electrode blocks not provided with the tapered surfaces (11b, 12b). Furthermore, in a case where the taper angle φ is 20°-40°, illuminance of 10% or more is realized as compared with a case where the electrode blocks not provided with the tapered surfaces (11b, 12b) are used.
In a case where the taper angle φ of the tapered surface 11b is 50° or larger (tapered surface 11b2), out of the ultraviolet light L1 emitted from the excimer lamp 3, the ultraviolet light L1 reflected by the tapered surfaces (11b, 12b) to change the travel direction is limited to that with an extremely large divergence angle. That is, it is considered that, as a result of a fact that a component the incident angle θ of which is relatively large is still present (ultraviolet light L1a) out of the ultraviolet light L1 that travels straight without being incident on the tapered surfaces (11b, 12b) and is directly incident on the optical filter 21, the ultraviolet light L1a is not transmitted through the optical filter 21 and cannot be extracted, so that the illuminance is not sufficiently made high in a case where the taper angle φ of the tapered surface 11b is 50° or larger as compared with a case where the taper angle φ is smaller than 50°.
With reference to
In contrast, in a case where the taper angle φ of the tapered surface 11b is smaller than 10° (tapered surface 11b3), the ultraviolet light L1b that is incident on the optical filter 21 at a small incident angle such that this is transmitted through the optical filter 21 even when this travels straight without the tapered surface 11b3 might be incident on the tapered surface 11b3. With reference to
Hereinafter, another embodiment is described.
<1> In the above-described embodiment, a case where the first electrode block 11 includes both the tapered surface 11b inclined counterclockwise and the tapered surface 11b inclined clockwise with respect to the XY plane is described (refer to
<2> In a case where the ultraviolet irradiation device 1 is provided with a plurality of excimer lamps 3, arrangement positions of the two or more excimer lamps 3 in the X direction may be displaced.
<3> In the above-described embodiment, it is described that the first electrode block 11 and the second electrode block 12 are arranged so as to be separated from each other in the Y direction. However, the first electrode block 11 and the second electrode block 12 may also be connected via an insulating member.
<4> In the above-described embodiment, it is described that the tapered surfaces (11b, 12b) are a part of the electrode blocks (11, 12), respectively. However, the tapered surfaces (11b, 12b) may also be formed of a reflecting member different from the forming material of the electrode blocks (11, 12) and exhibiting reflectivity with respect to the ultraviolet light L1 belonging to the first wavelength band.
<5> In the above-described embodiment, a case where a part of the tapered surface (11b, 12b) protrudes in the +X direction from the excimer lamp 3 is described. However, even in a case where an end in the +X direction of the tapered surfaces (11b, 12b) are located on the −X side as compared with an end on the +X end of the excimer lamp 3, the light extraction efficiency may be improved as compared with the electrode blocks not including the tapered surfaces (11b, 12b), respectively.
<6> In the above-described embodiment, a case where the tapered surfaces (11b, 12b) forming the reflecting surfaces are a part of the electrode blocks (11, 12) is described. However, as described above with reference to
For example, as illustrated in
Furthermore, in this case, each electrode does not have to have a block shape. That is, as illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-184792 | Oct 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/037737 | 10/5/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2021/070780 | 4/15/2021 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7187138 | Kogure | Mar 2007 | B2 |
| 10910210 | Yagyu et al. | Feb 2021 | B2 |
| 20070149086 | Nakamura | Jun 2007 | A1 |
| 20150246148 | Blechschmidt | Sep 2015 | A1 |
| 20190105415 | Gross | Apr 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| H09-171799 | Jun 1997 | JP |
| 2003-036723 | Feb 2003 | JP |
| 2006-40867 | Feb 2006 | JP |
| 2011-048968 | Mar 2011 | JP |
| 6025756 | Apr 2014 | JP |
| 2017-27912 | Feb 2017 | JP |
| 2018-114197 | Jul 2018 | JP |
| 2018-166091 | Oct 2018 | JP |
| 2012122210 | Sep 2012 | WO |
| Entry |
|---|
| Notification of Transmittal of Translation of the International Preliminary Report on Patentability (Chapter I) and Translation of Written Opinion of the International Searching Authority; PCT/JP2020/0037737; mailed on Apr. 12, 2022. |
| Offfice Action of Jun. 29, 2023 for Corresponding Taiwanese Application 109134046, Citing JP 2017-27912A and Its English Summary of the Office Action. |
| Number | Date | Country | |
|---|---|---|---|
| 20220409755 A1 | Dec 2022 | US |
