JP7517307B2 - Bacteria or virus inactivation device - Google Patents

Description

The present invention relates to a device for inactivating bacteria or viruses.

Germs (bacteria, fungi, etc.) and viruses present in air or on the surface of objects can cause infectious diseases in humans and non-human animals, and there is concern that the spread of infectious diseases will threaten people's lives. In particular, infectious diseases are likely to spread in facilities where people frequently gather, such as medical facilities, schools, and government offices, and in vehicles such as cars, trains, buses, airplanes, and ships, so there is a need for effective means of inactivating bacteria and viruses.

Conventionally, ultraviolet light irradiation has been known as a method for inactivating bacteria and viruses (hereinafter collectively referred to as "bacteria, etc."). DNA exhibits the highest absorption characteristics at a wavelength of around 260 nm. Low-pressure mercury lamps exhibit a high emission spectrum at a wavelength of around 254 nm. For this reason, sterilization technology using low-pressure mercury lamps is widely used.

However, it is known that irradiating the human body with ultraviolet light of this wavelength range poses a risk of adverse effects on the human body. The skin is divided into three parts, starting from the surface: the epidermis, dermis, and the subcutaneous tissue deeper below. The epidermis is further divided into four layers, starting from the surface: the stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. When ultraviolet light with a wavelength of 254 nm is irradiated onto the human body, it penetrates the stratum corneum, reaches the stratum granulosum, stratum spinosum, and in some cases the stratum basale, and is absorbed by the DNA of cells present within these layers. This results in a risk of skin cancer. Therefore, it is difficult to actively use ultraviolet light of this wavelength range in places where people may be present.

The following Patent Document 1 describes that ultraviolet light with a wavelength of 240 nm or more (UVC light) is harmful to the human body, and that ultraviolet light with a wavelength of less than 240 nm has a lesser effect on the human body than ultraviolet light with a wavelength of 240 nm or more. It also describes the results of irradiation experiments with wavelengths of 207 nm and 222 nm in particular.

In addition, the following Patent Document 2 discloses that after detecting that no one is present in a toilet, which is a space to be decontaminated, ultraviolet light (UVC light) is irradiated.

Patent No. 6025756 Special Publication No. 2017-528258

The present invention aims to provide a bacteria or virus inactivation device that can efficiently inactivate bacteria or viruses in a space where humans may be present, while taking into consideration the effects on the human body.

The bacteria or virus inactivation device according to the present invention comprises:
A light source that emits ultraviolet light having a light output in a specific wavelength range that falls within a range of 190 nm to 235 nm;
A control unit that controls the lighting of the light source;
a detection unit configured to detect whether or not a human is present within a detection target area, which is a part of an area irradiated with ultraviolet light or an area adjacent to the irradiation area;
The control unit controls the light source to be turned on regardless of the detection result of the detection unit, and when the detection unit detects the absence of a human being, controls the light source to increase the accumulated amount of ultraviolet light irradiation within a unit time.

In this specification, "inactivation" refers to the comprehensive concept of killing bacteria or viruses or eliminating their infectivity and toxicity, and "microbes" refers to microorganisms such as bacteria and fungi (molds). Hereinafter, "microbes or viruses" may be collectively referred to as "microbes, etc."

As of the filing date of this application, threshold limit values (TLV: Threshold Limit Values) for each wavelength have been established for the amount of UV radiation that can be irradiated to the human body per day (8 hours) by ACGIH (American Conference of Governmental Industrial Hygienists) and JIS Z 8812 (Method of measurement of harmful UV radiation). In other words, when UV radiation is used in an environment where humans are present, it is recommended that the illuminance and exposure time of UV radiation be determined so that the cumulative exposure amount of UV radiation irradiated within a given time period is within the standard value of the TLV.

On the other hand, if there are no people present in the area where ultraviolet light is irradiated (irradiation area), there is no need to take the TLV standard value into consideration even if the illuminance of ultraviolet light is increased or the irradiation time is extended. Furthermore, the higher the cumulative amount of ultraviolet light irradiation within a certain standard time period, the greater the inactivation effect within that space.

According to the description in the above-mentioned Patent Document 1, ultraviolet rays with wavelengths shorter than 240 nm are used to suppress the impact on the human body. The inactivation device of the present invention inactivates bacteria or viruses while suppressing the impact on the human body by using ultraviolet rays that show a light output in a specific wavelength range within the range of 190 to 235 nm.

Patent Document 2 only mentions UVC light, and the details of its wavelength are unknown. However, as mentioned above, in the past, the wavelength band most commonly used to inactivate bacteria and the like is around 254 nm, and the document only mentions UVC light without any specific mention of the wavelength, and the document controls the irradiation of ultraviolet light after confirming that no people are present, so it is natural to assume that the wavelength of the ultraviolet light used in Patent Document 1 is around 254 nm.

The light source of the inactivation device is preferably configured to emit ultraviolet light in the wavelength range of 200 to 230 nm, from the viewpoint of achieving an inactivation effect while ensuring safety to the human body. It is believed that ultraviolet light in this wavelength range has almost no effect on the human body even when irradiated for a relatively long period of time.

The inactivation device of the present invention emits ultraviolet light that has a light output in the wavelength range of 190 to 235 nm, so the amount of ultraviolet light that is tolerable to the human body is significantly higher than that of ultraviolet light that has a light output in the wavelength range of 240 nm or more. As a result, by controlling the irradiation dose within a range that does not exceed the TLV, it is possible to increase the inactivation effect while suppressing the effects on the human body.

Furthermore, with the above configuration, the cumulative amount of ultraviolet light irradiation is controlled to increase during times when no people are present, making it possible to increase the inactivation effect of bacteria, etc. while suppressing the effects on the human body.

In this specification, the term "integrated UV irradiation amount within a unit time" refers to the following time. When the light source is cyclically controlled by the control unit and the lighting cycle is adjusted to be different between the time zone where humans are present and the time zone where humans are not present, it refers to the value obtained by dividing the integrated irradiation amount within each lighting cycle (one cycle) by the lighting cycle. Taking FIG. 8 described later in the "Form for carrying out the invention" as an example, in the time zone where humans are present, one cycle is the sum of time Tn1 and time Tf1 (herein referred to as cycle τa for convenience), while in the time zone where humans are not present, one cycle is the sum of time Tn1 and time Tf2 (herein referred to as cycle τb for convenience). In this case, in the time zone where humans are present, the integrated irradiation amount per unit time is the value obtained by dividing the integrated irradiation amount over the cycle τa by this cycle τa. On the other hand, in the time zone where humans are not present, the integrated irradiation amount per unit time is the value obtained by dividing the integrated irradiation amount over the cycle τb by this cycle τb. In other words, the "cumulative amount of UV radiation irradiated per unit time" corresponds to the average value of the cumulative amount of radiation irradiated during each lighting cycle.

When the light source is controlled to be cyclically turned on by the control unit only during the time period when people are present, more specifically, in the case of an embodiment such as that shown in FIG. 15 described later in the "Form for carrying out the invention", the "accumulated amount of ultraviolet irradiation per unit time" is set by dividing the accumulated amount of ultraviolet irradiation within the time corresponding to this one cycle by the time corresponding to the cycle. Conversely, when the light source is controlled to be cyclically turned on by the control unit only during the time period when people are not present, more specifically, in the case of an embodiment such as that shown in FIG. 16 described later in the "Form for carrying out the invention", the "accumulated amount of ultraviolet irradiation per unit time" is similarly set by dividing the accumulated amount of ultraviolet irradiation within the time corresponding to one cycle by the time corresponding to the cycle.

Even if the light source is not periodically controlled by the control unit, if the light source is configured to be periodically controlled, the "unit time" may be set in a manner similar to that described above.

Furthermore, if the light source is not periodically controlled by the control unit and is configured in such a way that periodic lighting control is not possible, in other words, if only continuous lighting control is performed when the light source is turned on, the "accumulated amount of ultraviolet light irradiation per unit time" is set by dividing the cumulative amount of ultraviolet light irradiation within an arbitrarily set time (e.g., 5 minutes, 10 minutes, etc.) by the set time (in the above example, 5 minutes, 10 minutes, etc.). In this case, the "accumulated amount of ultraviolet light irradiation per unit time" corresponds to the average value of the cumulative amount of irradiation during continuous lighting operation.

the control unit is configured to be capable of executing a specific operation mode in which a first control in which the light source is turned on at a relatively high emission intensity and a second control in which the light source is turned on at a relatively lower emission intensity than when the first control is executed or is turned off are repeated;
The control unit may be configured to continue executing the specific operation mode with an increased cumulative amount of ultraviolet radiation irradiation per unit time when the detection unit detects the absence of a human being while the specific operation mode is being executed.

When ultraviolet light is continuously irradiated at high illuminance, the power supply unit that supplies power to the light source generates significant heat, requiring a large cooling system. For this reason, from the perspective of reducing the size of the device, it is preferable to have a configuration that can execute an operating mode (hereinafter referred to as a "specific operating mode") that switches between high and low ultraviolet illuminance, or switches between irradiation and non-irradiation of ultraviolet light, even when no humans are present.

Incidentally, some bacteria, etc., after being inactivated by irradiation with ultraviolet light of a wavelength of 254 nm, act to repair DNA damage when irradiated with light in the wavelength range of 300 nm to 500 nm. This is due to the action of photolyase enzymes (e.g., FAD (flavin adenine dinucleotide)) possessed by the bacteria, and this phenomenon is referred to as "photoreactivation of bacteria" below. The wavelength range of 300 nm to 500 nm includes visible light such as sunlight and white light, and it is known that photoreactivation of bacteria progresses in bright environments. Due to the existence of such circumstances, when bacteria, etc. are inactivated by irradiation with ultraviolet light in a lit environment, it is easy to make it difficult to maintain this inactivated state. From this perspective, for example, when inactivating bacteria, etc. using a conventional low-pressure mercury lamp, it is required, in principle, to keep it on continuously.

However, the light source of the inactivation device according to the present invention is configured to emit ultraviolet light that has a light output in a specific wavelength range that falls within the range of 190 nm to 235 nm. With such ultraviolet light, even if the above-mentioned visible light is irradiated after the target area for inactivation is irradiated, "photoreactivation of bacteria" is unlikely to occur, in other words, it has an inhibitory effect on "photoreactivation of bacteria". There are several possible reasons for this, but one of them is that ultraviolet light in this wavelength range acts on photoreactivating enzymes and inhibits the photoreactivation function. For this reason, even if the illuminance of ultraviolet light is temporarily reduced or ultraviolet light is irradiated intermittently during the inactivation process, bacteria do not easily grow during times when the illuminance is low or when no irradiation is performed. Therefore, it is possible to achieve a high inactivation effect while reducing the size of the device.

And, according to the above configuration, if the absence of a person is detected during such a period in which ultraviolet irradiation is performed intermittently, or during a period in which ultraviolet irradiation is performed while switching between high and low illuminance (i.e., during execution of a specific operation mode), the specific operation mode continues to be executed with the cumulative irradiation amount increased. This realizes a device that is small and has a high inactivation effect while taking into consideration the impact on the human body.

In order to further enhance the effect of inhibiting the photoreactivation function, it is more preferable that the wavelength range in which the ultraviolet light emitted from the light source exhibits light output is within the range of 200 nm to 235 nm, and particularly preferably within the range of 215 nm to 230 nm.

the specific operation mode is a mode in which an operation of executing the first control for a first predetermined time and then executing the second control for a second predetermined time is repeated,
The control unit may be configured to at least one of increase the first predetermined time period and decrease the second predetermined time period when the detection unit detects the absence of a human being.

With the above configuration, when the absence of a human is detected, ultraviolet light can be intermittently irradiated while increasing the cumulative amount of ultraviolet light irradiated per unit time.

The control unit may be configured to perform control to increase the light output of the light source when the first control is executed when the detection unit detects the absence of a human. More specifically, the "light output" referred to here may be luminance.

Even with this configuration, if the absence of a human is detected, the cumulative amount of UV radiation irradiated per unit time can be increased.

The ultraviolet light may have a peak wavelength in the range of 200 nm to 230 nm.

More specifically, the light source can be an excimer lamp filled with a light-emitting gas containing Kr and Cl, or an excimer lamp filled with a light-emitting gas containing Kr and Br. In the former case, the peak wavelength of the ultraviolet light is approximately 222 nm, and in the latter case, the peak wavelength of the ultraviolet light is approximately 207 nm. As another example, the light source can be a solid-state light source such as an LED or LD.

The present invention provides a device for inactivating bacteria or viruses that can efficiently inactivate bacteria or viruses in a space where humans may be present, while taking into consideration the effects on the human body.

1 is a diagram showing a schematic diagram of an example of a situation in which the bacteria or virus inactivation device according to the present invention is used. 1 is a diagram showing a schematic configuration of an inactivation device. FIG. 2 is a functional block diagram for explaining the configuration of the inactivation device. FIG. 2 is a perspective view illustrating an example of the appearance of a light source. FIG. 2 is a schematic exploded perspective view of a lamp house of a light source. FIG. 2 is a plan view showing a schematic positional relationship between an excimer lamp and electrodes. 1 is a diagram showing an example of a spectrum of ultraviolet light emitted from a light source. 5 is a timing chart showing an example of control of the light source by the control unit. 10 is a timing chart illustrating another example of the control of the light source by the control unit. 10 is a timing chart showing another example of the control of the light source by the control unit. 1 is a graph comparing the inactivation effect on Staphylococcus aureus when ultraviolet light having a wavelength of 254 nm is irradiated continuously and intermittently. 1 is a graph comparing the inactivation effect on Staphylococcus aureus when ultraviolet light having a wavelength of 222 nm is irradiated continuously and when it is irradiated intermittently. 1 is a diagram showing a schematic diagram of another example of a situation in which the bacteria or virus inactivation device according to the present invention is used. 1 is a diagram showing a schematic diagram of yet another example of a situation in which the bacteria or virus inactivation device according to the present invention is used. 1 is a diagram showing a schematic diagram of yet another example of a situation in which the bacteria or virus inactivation device according to the present invention is used. 10 is a timing chart showing another example of the control of the light source by the control unit. 10 is a timing chart showing another example of the control of the light source by the control unit.

Embodiments of the bacteria or virus inactivation device according to the present invention will be described with reference to the drawings as appropriate. Note that hereinafter, the "bacteria or virus inactivation device" may be abbreviated to simply "inactivation device."

Figure 1 is a diagram showing a schematic example of a situation in which the bacteria or virus inactivation device according to the present invention is used. In the example shown in Figure 1, an inactivation device 1 is installed in a room 50 such as a conference room. This inactivation device 1 is installed on a desk 51, chair 52, wallpaper 53, and the space within the room 50 for the purpose of inactivating bacteria, etc.

The inactivation device 1 is configured to emit ultraviolet light L1, which will be described later, and the inactivation process is carried out on the objects or space to be inactivated by irradiating them with this ultraviolet light L1.

Figure 2 is a diagram showing a schematic configuration of the inactivation device 1. Figure 3 is a functional block diagram for explaining the configuration of the inactivation device 1.

The inactivation device 1 includes a light source 2 that emits ultraviolet light L1, a detection unit 20 for detecting whether or not a human is present within a detection target area 40, and a control unit 9 that controls the lighting of the light source 2. The detection target area 40 here is an area in which the detection unit 20 detects whether or not a human is present, and is an area to which at least a portion can be irradiated with ultraviolet light L1. However, this detection target area 40 does not have to completely coincide with the area irradiated with ultraviolet light L1. In other words, the detection target area 40 is a part of the irradiation area of ultraviolet light L1, or an area adjacent to the irradiation area.

In this embodiment, the detection unit 20 is configured as a human sensor using infrared rays L2. When the detection unit 20 detects that no human is present within the detection target area 40, the control unit 9 changes the lighting control content for the light source 2. This control content will be described later.

Figure 4 is a perspective view showing an example of the appearance of the light source 2. Figure 5 is a perspective view showing the main casing part 12a and the lid part 12b of the lamp house 12 of the light source 2 disassembled from Figure 4.

In the following Figures 4 to 6, the explanation will be given with reference to the X-Y-Z coordinate system, in which the direction in which ultraviolet light L1 is extracted is the X direction, and the plane perpendicular to the X direction is the YZ plane. More specifically, as will be described later with reference to Figures 5 and 6, the tube axis direction of the excimer lamp 3 arranged in the lamp house 12 is the Y direction, and the direction perpendicular to the X and Y directions is the Z direction.

As shown in Figures 4 and 5, the light source 2 has a lamp house 12 with a light extraction surface 10 formed on one side. The lamp house 12 has a main casing part 12a and a lid part 12b, and the main casing part 12a houses an excimer lamp 3 and electrodes (5, 6). Figure 5 shows, as an example, a case in which four excimer lamps 3 are housed in the lamp house 12. The electrodes (5, 6) are electrically connected to a power supply line 18 and form electrodes for supplying power to each excimer lamp 3. Figure 6 is a plan view that shows a schematic positional relationship between the excimer lamp 3 and the electrodes (5, 6).

As shown in Figures 4 to 6, the light source 2 in this embodiment has two electrodes (5, 6) arranged so as to contact the outer surface of the arc tube of each excimer lamp 3. The electrodes (5, 6) are arranged at positions spaced apart in the Y direction. The electrodes (5, 6) are made of a conductive material, and preferably a material that is reflective to the ultraviolet light L1 emitted from the excimer lamp 3. As an example, the electrodes (5, 6) are both made of Al, Al alloy, stainless steel, or the like. The electrodes (5, 6) are both arranged so as to straddle each excimer lamp 3 in the Z direction while contacting the outer surface of the arc tube of each excimer lamp 3.

The excimer lamp 3 has an arc tube with its axis in the Y direction, and the outer surface of the arc tube of the excimer lamp 3 is in contact with each electrode (5, 6) at positions spaced apart in the Y direction. The arc tube of the excimer lamp 3 is filled with a light emitting gas 3G. When a high-frequency AC voltage of, for example, several kHz to 5 MHz is applied between the electrodes (5, 6) through a power supply line 18 (see FIG. 4) based on control from the control unit 9 (see FIG. 3), the voltage is applied to the light emitting gas 3G through the arc tube of the excimer lamp 3. At this time, a discharge plasma is generated in the discharge space in which the light emitting gas 3G is filled, and the atoms of the light emitting gas 3G are excited to an excimer state, and excimer light emission occurs when these atoms transition to the ground state.

The light emitting gas 3G is made of a material that emits ultraviolet light L1 that exhibits a light output in a specific wavelength range within the range of 190 nm to 235 nm during excimer emission. As an example, the light emitting gas 3G includes KrCl, KrBr, and ArF.

For example, when the light emitting gas 3G contains KrCl, the excimer lamp 3 emits ultraviolet light L1 with a main peak wavelength of about 222 nm. When the light emitting gas 3G contains KrBr, the excimer lamp 3 emits ultraviolet light L1 with a main peak wavelength of about 207 nm. When the light emitting gas 3G contains ArF, the excimer lamp 3 emits ultraviolet light L1 with a main peak wavelength of about 193 nm. Note that a fluorescent material may be applied to the tube wall of the light emitting tube of the excimer lamp 3 to emit ultraviolet light L1 with a longer wavelength than the wavelength of the excimer light. Figure 7 is a diagram showing an example of the spectrum of ultraviolet light L1 emitted from an excimer lamp 3 containing KrCl in the light emitting gas 3G.

Figure 8 is a timing chart showing an example of the control of the light source 2 by the control unit 9. More specifically, Figure 8 shows a schematic diagram of the change in the optical output of the ultraviolet light L1 emitted from the light source 2 according to the control result by the control unit 9. This method of illustration is also common to Figures 9, 10, and 15, which will be described later.

In this embodiment, the control unit 9 controls the light source 2 so that times when the light source 2 is energized (ON times) and times when the light source 2 is not energized (OFF times) occur alternately. In other words, the control unit 9 is configured to be able to execute an operation mode (corresponding to a "specific operation mode") in which the light source 2 is repeatedly turned on and off. In this case, the turning on operation corresponds to a "first control" and the turning off operation corresponds to a "second control." Using this terminology, the specific operation mode is a mode in which an operation in which the first control is executed for a certain time and then the second control is executed for a certain time is repeated.

As an example, electricity is applied to the light source 2 for a time Tn1 (corresponding to the "first specified time"), and ultraviolet light L1 is emitted from the light source 2 for this time. Thereafter, electricity is stopped from being applied to the light source 2 for a time Tf1 (corresponding to the "second specified time"), and the emission of ultraviolet light L1 is stopped. As an example, the time Tn1 is 15 seconds, and the time Tf1 is 250 seconds. These times can be changed as appropriate by the control unit 9.

In FIG. 8, the change in the light output from the light source 2, i.e., the irradiation/non-irradiation of ultraviolet light L1, is shown extremely linearly, but this is merely a schematic drawing for the convenience of explanation. If the time axis is analyzed in detail, the light output may be considered to decrease/increase smoothly. The speed (response) at which the light output from the light source 2 changes in response to a change in the control signal from the control unit 9 depends on the configuration of the light source 2. FIG. 8 merely shows the ON/OFF control of the light source 2 based on the control signal from the control unit 9, and does not suggest that the light source 2 has extremely high responsiveness. In other words, in the present invention, the speed at which the light output from the light source 2 changes based on the control signal from the control unit 9 is not limited. This point is also common to FIG. 9, FIG. 10, and FIG. 15 described later.

Here, assume that at time Ta, the detection unit 20 detects the absence of a human being within the detection target area 40. When the control unit 9 receives a signal from the detection unit 20 indicating that the absence of a human being has been detected, it changes the control content for the light source 2 so as to increase the cumulative irradiation amount of ultraviolet light L1 over a predetermined unit time.

As a specific example, the control unit 9 performs control to reduce the OFF time of the light source 2 after time Ta (see FIG. 8). That is, before time Ta, the OFF time is set to Tf1, but after time Ta, the OFF time is set to Tf2, which is shorter than Tf1. As a result, the ratio of the continuous lighting time of the light source 2 to the time required from when the light source 2 is turned on until it is turned on again (ON duty ratio) increases.

Since it is detected that no human is present within the detection target area 40, even if the cumulative dose of ultraviolet light L1 per unit time is increased, there is no risk of the cumulative dose of ultraviolet light L1 irradiated to humans increasing. Therefore, it is possible to increase the inactivation effect of bacteria, etc., within the room 50 (see FIG. 1) without exceeding the standard values set by ACGIH, JIS Z 8812, etc.

Although not shown in FIG. 8, if the detection unit 20 subsequently detects the presence of a human at a certain time Tb, the OFF time of the light source 2 is again set to Tf1. This makes it possible to suppress the cumulative irradiation amount of ultraviolet light L1 on a human to within a reference value while still achieving the inactivation effect of bacteria, etc.

In particular, the light source 2 is configured to emit ultraviolet light L1 that has a light output in a specific wavelength range that falls within the range of 190 nm to 235 nm, and in the case of ultraviolet light L1 in this wavelength band, a high inactivation effect can be achieved without continuous irradiation of ultraviolet light, compared to ultraviolet light with a wavelength of 254 nm, such as that emitted by low-pressure mercury lamps that are generally used widely for sterilization, etc. This point will be described later.

Figure 9 is a timing chart showing an example of another control performed by the control unit 9. As shown in Figure 9, when it is detected that no human is present within the detection target area 40 at time Ta, control may be performed to increase the light output of the light source 2 (excimer lamp 3). As a result, the luminance of the light source 2 increases, and the integrated irradiation amount of ultraviolet light L1 per unit time can be increased compared to before time Ta. Methods for increasing the light output of the light source 2 include, for example, increasing the peak value of the pulse voltage applied to the light source 2, or increasing the frequency of the pulse voltage.

Figure 10 is a timing chart showing an example of yet another control performed by the control unit 9. As shown in Figure 10, when it is detected that no human is present within the detection target area 40 at time Ta, control may be performed to increase the ON time of the light source 2. That is, before time Ta, the ON time is set to Tn1, but after time Ta, the ON time is set to Tn3, which is longer than Tn1. As a result, the ratio of the continuous lighting time of the light source 2 to the time required for the light source 2 to be turned on again after it is turned on (ON duty ratio) increases.

In the example of FIG. 10, the OFF time is also set to Tf3, which is shorter than Tf1. However, the OFF time may be controlled to remain at Tf1.

The control contents shown in Figures 8 to 10 may be combined as appropriate.

Figures 11A and 11B are graphs to explain that the inactivation effect on bacteria, etc. differs depending on the wavelength of the irradiated ultraviolet light when the ultraviolet light is irradiated continuously and when it is irradiated intermittently. Both graphs are the results of the following experiment.

1 mL of Staphylococcus aureus with a concentration of about 10 ⁶ CFU/mL was placed in a φ35 mm petri dish, and ultraviolet light from a low pressure mercury lamp (comparative example) and ultraviolet light from a KrCl excimer lamp (example) were irradiated from above the petri dish. CFU stands for colony forming unit. After that, the solution in the petri dish after irradiation was diluted to a predetermined ratio with physiological saline, and 0.1 mL of the diluted solution was seeded on a standard agar medium. Then, the mixture was cultured for 48 hours in a culture environment at a temperature of 37°C and a humidity of 70%, and the number of colonies was counted.

In both the comparative example and the working example, experiments were conducted both in the case of continuous UV irradiation and in the case of intermittent UV irradiation. Intermittent UV irradiation was conducted by repeating a control in which UV irradiation was performed for 50 seconds, followed by no irradiation for 59 minutes and 10 seconds. This experiment was also conducted in a normal room without a blackout curtain or the like.

Figures 11A and 11B are graphs of the above experimental results, with the horizontal axis representing the amount of UV irradiation and the vertical axis representing the survival rate of S. aureus. The vertical axis represents the logarithmic value of the ratio of the number of S. aureus colonies after UV irradiation to the number of S. aureus colonies before UV irradiation.

Figure 11A shows that, when ultraviolet light with a wavelength of 254 nm is used, the survival rate of Staphylococcus aureus is clearly higher when it is irradiated intermittently compared to continuous irradiation. In contrast, when ultraviolet light with a wavelength of 222 nm is used, even with intermittent irradiation, the survival rate of Staphylococcus aureus is almost equivalent to that of continuous irradiation. In particular, in this experiment, the irradiation mode was set to irradiate for 50 seconds, followed by no irradiation for 59 minutes and 10 seconds, and although the irradiation time within the unit time of 60 minutes was only 1.3%, it can be seen that an inactivation effect almost equivalent to that of continuous ultraviolet irradiation was obtained.

This is presumably because after the bacteria are inactivated by irradiation with 254 nm UV light, the bacteria are exposed to illumination light or natural light during the time when UV light is not being irradiated, and the DNA damage is repaired by the photolyase enzyme contained in the bacteria. On the other hand, it is presumed that the 222 nm UV light also acts on this photolyase enzyme, resulting in a state in which the photolyase function remains inhibited even during the time when UV light is not being irradiated. This function is achieved by UV light L1, which shows a light output in a specific wavelength range within the range of 190 nm to 235 nm, and the effect is particularly strong with a wavelength of 200 nm to 235 nm, and is even more pronounced with a wavelength of 215 nm to 230 nm.

In other words, according to the inactivation device 1 of this embodiment, during the time period when the detection unit 20 detects the presence of a human in the detection target area 40, the ON duty of the light source 2 is lowered or the light output (brightness) is lowered to reduce the cumulative irradiation amount per unit time. This sets the cumulative irradiation amount of ultraviolet light to humans not to exceed the reference value. Even during this time period, the ultraviolet light L1 is intermittently irradiated, ensuring the inactivation effect of bacteria, etc. On the other hand, during the time period when the detection unit 20 detects that no human is present in the detection target area 40, the ON duty of the light source 2 is increased or the light output (brightness) is increased to increase the cumulative irradiation amount per unit time. This further enhances the inactivation effect of bacteria, etc., without the cumulative irradiation amount of ultraviolet light to humans exceeding the reference value.

Figures 12 to 14 are diagrams that show another example of a situation in which the inactivation device 1 is used.

Figure 12 shows a situation in which an inactivation device 1 is installed in a passageway 60 inside a building or vehicle. Inactivation device 1a does not detect the presence of a human 61 in the detection unit 20, so the ON duty is increased and ultraviolet light L1 is irradiated within area 62. On the other hand, inactivation device 1b detects the presence of a human 61 in the detection unit 20, so the ON duty is decreased and ultraviolet light L1 is not irradiated to area 63 during the time period shown in Figure 12.

Figure 13 shows a situation where the inactivation device 1 is installed in a room 70. The inactivation device 1c is installed, for example, for the purpose of inactivating bacteria and the like within the space and on the floor of the room 70. The inactivation device 1d is installed for the purpose of inactivating bacteria and the like on an operation unit 71 such as a remote control for controlling the air conditioning and lighting of the room 70. In the example shown in Figure 13, when the inactivation device 1 (1c, 1d) detects the absence of a human (not shown), the cumulative irradiation amount of ultraviolet light L1 per unit time is increased, thereby increasing the inactivation effect of bacteria and the like on the floor and space of the room 70 and on the operation unit 71 without the cumulative irradiation amount of ultraviolet light on the human exceeding the reference value.

Figure 14 shows a situation where the inactivation device 1 is installed in a vending machine 80. The inactivation device 1e is installed, for example, in the operation unit 81, change outlet 82, and product outlet 83 of the vending machine 80 for the purpose of inactivating bacteria, etc. In the example shown in Figure 14, when the inactivation device 1 (1e) detects the absence of a human (not shown), the cumulative irradiation amount of ultraviolet light L1 per unit time is increased, thereby increasing the inactivation effect of bacteria, etc. in the operation unit 81 and outlets (82, 83) without the cumulative irradiation amount of ultraviolet light on the human exceeding a reference value.

[Another embodiment]
Another embodiment will be described below.

<1> In the above embodiment, the inactivation device 1 has a built-in human sensor as the detection unit 20 for detecting the presence/absence of a human being. However, if a separate detection means such as a human sensor is provided in advance at the location where the inactivation device 1 is installed, the inactivation device 1 may configure the detection unit 20 with a receiving unit that receives a signal from the detection means.

The detection unit 20 may be capable of directly or indirectly determining the presence/absence of a human being. For example, the detection unit 20 may be capable of determining the presence/absence of a human being using a contact sensor, weight sensor, door sensor, etc., either alone or in combination, and may perform the determination based on whether or not a lighting fixture installed in the space to be inactivated is turned on, whether the door in the room is opened or closed, etc.

<2> As shown in FIG. 15, when the detection unit 20 detects the absence of a human being at time Ta, the control unit 9 may control the light source 2 to be continuously lit. However, if the light source 2 is continuously lit, there is a risk that the power supply circuit (inverter, etc.) provided to supply power to the light source 2 may heat up. In addition, if the detection unit 20 were to fail, there is a risk that ultraviolet light L1 would continue to be emitted from the light source 2 even when a human being is present. From this perspective, it is preferable that the control unit 9 be preset so that ultraviolet light L1 is intermittently emitted even when no human is present.

However, the present invention does not exclude a configuration in which the control unit 9 can be appropriately switched between a continuous illumination mode and an intermittent illumination mode during times when no humans are present within the detection target area 40.

〈3〉 As shown in FIG. 16, the control unit 9 may control the light source 2 to be continuously turned on at a low output during the time period when a human is present within the detection target area 40, and may control the light source 2 to be turned on periodically with an increased output when it detects that no human is present within the detection target area 40 (time Ta).

In this case, as in the above-described embodiment, the cumulative irradiation amount of ultraviolet light L1 per unit time is increased by detecting the absence of a human being within the detection target area 40, and there is no risk of an increase in the cumulative irradiation amount of ultraviolet light L1 irradiated to a human being. Therefore, it is possible to increase the inactivation effect of bacteria, etc., within the room 50 (see FIG. 1) without exceeding the standard values set by ACGIH, JIS Z 8812, etc.

On the other hand, if the room 50 is a conference room or the like, the amount of time that people will be continuously present in the room 50 can be predicted to a certain extent, and it is unlikely that people will stay there for long periods of time, such as 18 hours or more. For this reason, the control unit 9 controls the output of the light source 2 so that the ultraviolet light L1 is irradiated at an extremely low illuminance within a range that does not exceed the standard values set by ACGIH, JIS Z 8812, etc., thereby achieving the inactivation effect without affecting the human body even if there is a person present in the room 50.

In this case, it is preferable that the control unit 9 controls the cumulative irradiation amount of ultraviolet light L1 per unit time to be higher the longer the time from when the presence of a human in the detection target area 40 is detected immediately before to when the presence of a human is detected no longer in the detection target area 40, in other words, the longer the continuous presence time of a human in the detection target area 40. More specifically, the longer the continuous presence time of a human in the detection target area 40, the higher the light output of the light source 2 or the higher the ON duty ratio may be set during the immediately following time period when no human is present.

〈4〉 In the above embodiment, the light source 2 is an excimer lamp 3. However, the light source 2 is not limited to a specific form as long as it emits ultraviolet light L1 that has a light output in a specific wavelength range between 190 nm and 235 nm. For example, the light source 2 may be a solid-state light source such as an LED or laser diode.

<5> In the above embodiment, the "specific operation mode" is an operation mode in which a first control in which a lighting operation is performed and a second control in which a turning off operation is performed are repeated. However, the "specific operation mode" may be an operation mode in which a first control in which a lighting operation is performed with a relatively high light emission intensity and a second control in which a lighting operation is performed with a light emission intensity relatively lower than that when the first control is performed are repeated.

As an example, when the first control is performed, the control unit 9 adjusts the luminance of the light source 2 so that the illuminance of the ultraviolet ray L1 on the light extraction surface 10 is higher than 0.3 mW/cm ² , and when the second control is performed, the illuminance of the ultraviolet ray L1 on the light extraction surface 10 is less than 0.3 mW/cm ^2. The illuminance division value (illuminance reference value) here may be set arbitrarily within the range of 0.1 mW/cm ² to 3 mW/cm ² . For example, the illuminance reference value of ultraviolet light L1 on the light extraction surface 10 may be set to ^one value selected from a group of set values consisting of 3 mW/ ^cm2 , 2.5 mW/ ^cm2 , 2 mW/ ^cm2 , 1.5 mW/ ^cm2 , 1 mW/cm2, 0.5 mW/ ^cm2 , and 0.1 mW/ ^cm2 , and when a first control is executed, the illuminance may be controlled to be higher than the illuminance reference value, and when a second control is executed, the illuminance may be controlled to be less than the illuminance reference value.

The illuminance of the ultraviolet light L1 when the second control is executed is preferably less than 50% of the illuminance of the ultraviolet light L1 when the first control is executed, more preferably less than 30%, and particularly preferably less than 15%. If the illuminance of the ultraviolet light L1 when the second control is executed is less than 1% of the illuminance of the ultraviolet light L1 when the first control is executed, the second control may be regarded as a substantial "lights off" operation.

<6> In the above embodiment, the detection unit 20 detects whether or not a human is present in the detection target area 40, and the control unit 9 controls the light source 2 according to the detection result of the detection unit 20. However, the detection unit 20 may detect the absence of animals other than humans. In this case, the inactivation device 1 according to the present invention includes a light source 2 that emits ultraviolet light L1 that shows a light output in a specific wavelength range that falls within the range of 190 nm to 235 nm, a control unit 9 that controls the lighting of the light source 2, and a detection unit 20 that detects whether or not an "animal" is present in the detection target area 40, which is a part of the irradiation area of the ultraviolet light L1 or an area adjacent to the irradiation area. Then, the control unit 9 may control the light source 2 to increase the cumulative irradiation amount of the ultraviolet light L1 within a unit time when the detection unit 20 detects the absence of an "animal".

In this case, the animals to be detected may be pets such as dogs, cats, rabbits, etc., or livestock such as cows, pigs, chickens, horses, etc., or animals kept in zoos or protected animals.

1 (1a, 1b, 1c, 1d, 1e): inactivation device 2: light source 3: excimer lamp 3G: luminous gas 9: control unit 10: light extraction surface 12: lamp house 12a: main body casing 12b: lid 18: power supply line 20: detection unit 40: detection target area 50: room 51: desk 52: chair 53: wallpaper 60: passage 61: people 62, 63: area 70: room 71: operation unit 80: vending machine 81: operation unit 82: outlet 83: outlet L1: ultraviolet light L2: infrared light

Claims (5)

A light source that emits ultraviolet light having a light output in a specific wavelength range that falls within a range of 190 nm to 235 nm;
A control unit that controls the lighting of the light source;
a detection unit configured to detect whether or not a human is present within a detection target area, which is a part of an area irradiated with ultraviolet light or an area adjacent to the irradiation area;
The control unit controls the light source to be turned on regardless of the detection result of the detection unit, and when the detection unit detects the absence of a human being, controls the light source to increase the cumulative amount of ultraviolet light irradiation within a unit time. the control unit is configured to be capable of executing a specific operation mode in which a first control in which the light source is turned on at a relatively high emission intensity and a second control in which the light source is turned on at a relatively lower emission intensity than when the first control is executed or is turned off are repeated;
The bacteria or virus inactivation device according to claim 1 , wherein the control unit executes the specific operation mode when the detection unit detects the absence of a human being. The bacteria or virus inactivation device according to claim 1 or 2, characterized in that the control unit performs control to reduce the light output of the light source during a time period when the detection unit detects the presence of a human being compared to a time period when the detection unit detects the absence of a human being. The bacteria or virus inactivation device according to claim 3, characterized in that the control unit controls the light source to be continuously lit during the time period when the detection unit detects the presence of a human being. A light source that emits ultraviolet light having a light output in a specific wavelength range that falls within a range of 190 nm to 235 nm;
A control unit that controls the lighting of the light source;
a detection unit that detects whether or not an animal is present within a detection target area that is a part of the ultraviolet ray irradiation area or an area adjacent to the ultraviolet ray irradiation area;
The control unit controls the light source to be turned on regardless of the detection result of the detection unit, and when the detection unit detects the absence of an animal, controls the light source to increase the cumulative amount of ultraviolet light irradiation within a unit time.

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