Ultraviolet irradiation system

Abstract

To provide a UV irradiation system that can suitably vary a UV irradiance according to a density of people in an irradiation area.SOLUTION: According to an embodiment, a UV irradiation system has an irradiation unit and a control unit. The irradiation unit can irradiate an irradiation area with UV rays. Based on an estimation of the density of people in the irradiation area, the control unit controls the irradiation unit to be in an irradiation state where a planned UV irradiance from the irradiation unit becomes below an upper limit. The control unit also chronological regulates so that UV irradiation from the irradiation unit becomes a UV intensity corresponding to the estimation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to an ultraviolet illumination system. [Background technology]

[0002] In the ultraviolet irradiation system, an ultraviolet irradiation unit irradiates a predetermined area with ultraviolet light. A control unit determines whether or not a person is present in the ultraviolet light irradiation area. If no person is present in the ultraviolet light irradiation area, the control unit controls the irradiation unit to irradiate the irradiation area with ultraviolet light. In such an ultraviolet light irradiation system, it is required to appropriately change the amount of ultraviolet light irradiation depending on the density of people in the irradiation area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-536492 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an ultraviolet irradiation system that can appropriately change the amount of ultraviolet irradiation depending on the density of people in the irradiation area. [Means for solving the problem]

[0005] According to an embodiment, the ultraviolet irradiation system includes an irradiation unit and a control unit. 222nm It can emit ultraviolet light. The irradiation unit irradiates ultraviolet rays so that a person in the irradiation area is exposed to ultraviolet rays. The control unit controls the irradiation unit in an irradiation state in which the ultraviolet irradiation amount in the planned irradiation of the irradiation unit is less than the upper limit value based on the predicted result of the crowding of people in the irradiation area. The control unit also adjusts the irradiation of ultraviolet rays from the irradiation unit over time to a state in which the ultraviolet illuminance corresponds to the predicted result. Effect of the Invention

[0006] According to the present invention, it is possible to provide an ultraviolet irradiation system that can appropriately change the amount of ultraviolet irradiation depending on the density of people in an irradiation area. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram illustrating an example of an ultraviolet irradiation system according to an embodiment. [Diagram 2] FIG. 2 is a graph showing an example of a change over time in the density of people in an irradiation area on a certain day, which is used in the calculation unit of the ultraviolet irradiation system according to the embodiment. [Diagram 3] Figure 3 is a graph showing an example of the change over time in ultraviolet illuminance of ultraviolet rays irradiated from the irradiation unit, determined by a calculation unit of the ultraviolet irradiation system of the embodiment based on the change over time in the density of people shown in Figure 2. [Figure 4] FIG. 4 is a flowchart showing an example of a process executed in the control of the ultraviolet irradiation system according to the embodiment. [Diagram 5] FIG. 5 is a graph showing an example of the change over time in the crowding density in the irradiation area on the day shown in FIG. 2, predicted by a prediction unit of an ultraviolet irradiation system according to an embodiment based at least on the most recent actual crowding density. [Figure 6] Figure 6 is a graph showing an example of the change over time in ultraviolet illuminance of ultraviolet rays irradiated from the irradiation unit, determined by the calculation unit of the ultraviolet irradiation system of the embodiment based on the change over time in the density of people shown in Figure 5. [Figure 7] FIG. 7 is a flowchart showing an example of a process different from that shown in FIG. 4, which is executed in the control of the ultraviolet ray irradiation system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the ultraviolet irradiation system of the present embodiment, ultraviolet light is irradiated to an irradiation target (for example, a contaminated location to which at least one bacteria, virus, etc. is attached, or a location expected to be contaminated to which at least one bacteria, virus, etc. may be attached) to sterilize, disinfect, or sterilize the irradiation target. In the following embodiment, sterilization is used as an example. However, the term "sterilization" can be replaced with "sterilization" or "disinfection". The expected contaminated location is, for example, a location where a person has passed through or a location where a person has stayed. When at least one of the time taken for a person to pass through a certain area and the time spent by a person in a certain area exceeds a predetermined specified value, the area may be determined as an expected contaminated location. The predetermined specified value is determined, for example, based on the number of people who have passed through a certain area. In one example, when three people pass through a certain area, the control unit 12 (described later) cooperates with the prediction unit 16 to determine whether the area is expected to be contaminated or not based on the result of comparing the total time taken for the three people to pass through with a predetermined specified value.

[0009] The ultraviolet irradiation system (10) of the embodiment includes an irradiation unit (11) and a control unit (12). The irradiation unit (11) can irradiate an irradiation area with ultraviolet rays. The control unit (12) controls the irradiation unit (11) in an irradiation state in which the ultraviolet irradiation amount in the planned irradiation of the irradiation unit (11) is less than an upper limit value based on a prediction result of the density of people in the irradiation area. In addition, the control unit (12) adjusts the irradiation of ultraviolet rays from the irradiation unit (11) over time to a state in which the ultraviolet illuminance corresponds to the prediction result. In this way, the ultraviolet irradiation system 10 can appropriately change the irradiation amount of ultraviolet rays according to the density of people in the irradiation area.

[0010] The ultraviolet irradiation system (10) of the embodiment further includes a detection unit (15). The detection unit (15) can detect the density of people in the irradiation area. The prediction result is a result predicted based at least on the density of people detected by the detection unit (15). This allows the ultraviolet irradiation system 10 to use the appropriately predicted density of people in the irradiation area as the prediction result.

[0011] The ultraviolet irradiation system (10) of the embodiment further includes a prediction unit (16). The prediction unit (16) predicts the future crowding density of the irradiation area as a prediction result based on at least the crowding density of the irradiation area. This allows the ultraviolet irradiation system 10 to predict the future crowding density of the irradiation area based on the crowding density of the irradiation area.

[0012] In the ultraviolet irradiation system (10) of the embodiment, the prediction result is a result predicted based at least on the density of people in the irradiation area up to the previous day, so that the ultraviolet irradiation system 10 can use the more appropriately predicted density of people in the irradiation area as the prediction result.

[0013] In the ultraviolet irradiation system (10) of the embodiment, the prediction result is a result predicted based on the latest human density in the irradiation area, so that the ultraviolet irradiation system 10 can use a more appropriately predicted human density in the irradiation area as the prediction result.

[0014] In the ultraviolet irradiation system (10) of the embodiment, the detection unit (15) can detect the distance between the irradiation unit (11) and a person in the irradiation area. The control unit (12) controls the irradiation unit (11) in an irradiation state where the ultraviolet irradiation amount is less than an upper limit value, based at least on the distance between the irradiation unit (11) and the person detected by the detection unit (15). This allows the ultraviolet irradiation system (10) to irradiate ultraviolet rays in a state where the ultraviolet irradiation amount satisfies the upper limit value.

[0015] Hereinafter, embodiments will be described with reference to the drawings.

[0016] (Embodiment) The ultraviolet irradiation system 10 of the present embodiment sterilizes a contaminated site by irradiating the contaminated site with ultraviolet rays. The degree of sterilization by irradiating a contaminated site with ultraviolet rays is generally determined by the ultraviolet irradiation amount (mJ / cm 2 ) is defined by the amount of ultraviolet light exposure (mJ / cm 2 ) is the UV irradiance (mW / cm 2) and the ultraviolet irradiation time (s). The ultraviolet irradiation amount is the ultraviolet illuminance multiplied by the ultraviolet irradiation time (ultraviolet illuminance x ultraviolet irradiation time). In other words, the ultraviolet irradiation amount is proportional to the ultraviolet illuminance and to the ultraviolet irradiation time. Note that a contaminated area may be an area where one or more bacteria, viruses, etc. are attached, or an area where a specified number or more of bacteria, viruses, etc. are attached per unit area may be defined as a contaminated area.

[0017] The location where the ultraviolet irradiation system 10 is used is an indoor space where people enter and leave from outside for a predetermined period of time, such as a restaurant, cafe, etc. In such a location, customers enter the location from outside when business hours begin. The customers use the location in a predetermined manner, and therefore stay in the location for a certain period of time. After completing the predetermined manner of use, the customers leave the location. Then, when business hours end, people stop entering and leaving the location.

[0018] In the above-mentioned locations, for example, if a location that may be touched by a user is contaminated, it is required that appropriate treatment be carried out promptly. However, when appropriately treating the location using, for example, ultraviolet light, it is required from a safety standpoint to meet certain requirements in order to carry out treatment during a certain period of time when users are present. These certain requirements are, for example, set out by the American Conference of Governmental Industrial Hygienists (ACGIH) and the Japanese Industrial Standards (JIS Z 8812) as the threshold limit value (TLV) of ultraviolet light that a person may be exposed to in a day. For example, in the case of 222 nm ultraviolet light, the threshold limit value of ultraviolet light exposure (within 8 hours per day) is 22 mJ / cm2. 2 This threshold limit value (TLV) corresponds to the upper limit of the ultraviolet light irradiated by the ultraviolet light irradiation system. The ultraviolet light irradiation system 10 of the present embodiment can sterilize the contaminated area quickly and appropriately while satisfying such predetermined requirements.

[0019] 1 shows a block diagram of an ultraviolet irradiation system 10 according to an embodiment. The ultraviolet irradiation system 10 includes an irradiation unit 11, a control unit 12, a calculation unit 13, a storage unit 14, a detection unit 15, and a prediction unit 16. The control unit 12 includes the calculation unit 13.

[0020] The irradiation unit 11 can irradiate ultraviolet light (light with a wavelength in the ultraviolet region). The irradiation unit 11 includes a light source unit and a power supply unit, which are not shown. The light source of the light source unit may be a non-LED (Light Emitting Device) lamp (for example, a mercury lamp, a metal halide lamp, a fluorescent ultraviolet lamp, an excimer lamp, etc.), or may be an LED lamp. The light source of the light source unit is, for example, a light-emitting substrate using a UV-LED. The ultraviolet light irradiated by the light source unit has a wavelength of at least 380 nm. The light source unit may irradiate only ultraviolet light. In addition to the ultraviolet light, the irradiation unit 11 may irradiate visible light with a wavelength longer than 380 nm. Then, the light source of the light source unit is turned on, so that the irradiation unit 11 can illuminate (light) the target location. When an LED is used as the light source of the light source unit, the power supply unit (lighting circuit) can be simplified. In addition, the power supply unit may include an inverter. Note that the location where the irradiation unit 11 is attached is not particularly limited as long as the irradiation unit 11 can irradiate the target with ultraviolet light.

[0021] The control unit 12 controls the ultraviolet irradiation system 10. In this case, in the ultraviolet irradiation system 10, a certain processing device includes a processor and a storage medium, the processor executes the processing of the control unit 12, and the storage medium becomes the storage unit 14. The processing device is, for example, a computer, a smart device, etc. The processor includes any of a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), an ASIC (Application Specific Integrated Circuit), a microcomputer, an FPGA (Field Programmable Gate Array), and a DSP (Digital Signal Processor), etc. The storage medium may include an auxiliary storage device in addition to a main storage device such as a memory. The storage medium is a magnetic disk, an optical disk (CD-ROM, CD-R, DVD, etc.), a magneto-optical disk (MO, etc.), and a semiconductor memory (USB memory, SSD, etc.), etc.

[0022] In a certain processing device, only one processor and one storage medium may be provided, or multiple processors and storage media may be provided. The processor executes the processing of the control unit 12 by executing a program stored in a storage medium or the like. The program executed by the processor may be stored in a processing device connected via a network. The network may be, for example, a wired LAN (Local Area Network), a wireless LAN, a mobile communication network, Bluetooth (registered trademark), or the like. The processing device connected via the network may be a computer, a server, a server in a cloud environment, or the like. In this case, the processor downloads the program via the network.

[0023] A certain processing device may be a cloud server constructed in a cloud environment. In this case, the infrastructure of the cloud environment is configured by a virtual processor such as a virtual CPU and a cloud memory. The virtual processor executes the processing of the control unit 12 including the calculation unit 13. And the cloud memory functions as the storage unit 14. Note that the storage unit 14 may be provided in, for example, a processing device other than the control unit 12. In one example, the other processing device is a computer or the like other than the control unit 12. In this case, the control unit 12 is connected to the computer in which the storage unit 14 or the like is provided via a network.

[0024] The ultraviolet irradiation system 10 may be provided with a user interface. In the user interface, various operations are input by the user, and information to be notified to the user is notified by display or the like. The user interface may be a display unit such as a display, or an input unit such as a touch panel or a keyboard. The user interface may be provided separately from the control unit 12, for example.

[0025] Control unit 12 writes (inputs) information regarding changes over time in the density of people in the ultraviolet ray irradiation area to storage unit 14. The information regarding changes over time in the density of people in the ultraviolet ray irradiation area may be information regarding changes over time that are correlated with the density of people obtained from outside via a network, or may be information regarding changes over time related to the density of people detected by detection unit 15 described below. When control unit 12 uses information regarding changes over time in the density of people, it receives the information from storage unit 14 or detection unit 15.

[0026] FIG. 2 is a graph showing the change in the density of people over time on a certain day in an ultraviolet irradiation area. The graph shown in FIG. 2 itself and the values ​​constituting the graph shown in FIG. 2 are an example of information on the change in the density of people over time in an ultraviolet irradiation area. The horizontal axis indicates time. The vertical axis indicates density. The curve α0 indicates the change in the density of people over time. The curve α0 is, for example, a predicted curve (prediction result) of the density of people at each time of a certain day predicted from the change in the density of people over time up to the day before in an ultraviolet irradiation area. As shown in FIG. 2, the ultraviolet irradiation system 10 of this embodiment continuously irradiates ultraviolet rays during the ultraviolet irradiation period from time t1 to time t2. In addition, ultraviolet rays are irradiated in a state where there is no person in the place where the ultraviolet irradiation system 10 is used until time t1. Similarly, ultraviolet rays are irradiated from time t2 in a state where there is no person in the place where the ultraviolet irradiation system 10 is used. Time t1, which is the start time of ultraviolet irradiation, and time t2, which is the end time of ultraviolet irradiation, can be appropriately set by a user of the ultraviolet irradiation system 10. In one example, when the place where the ultraviolet irradiation system 10 is used is a store, Fig. 2 shows the change in the density of people in the store on a certain day, where time t1 is the opening time of the store and time t2 is the closing time of the store.

[0027] In Figure 2, the human density starts at zero and increases as time passes and approaches time t1. After time t1, the human density increases rapidly (monotonically increases), and reaches its maximum between time t1 and time t2. After reaching its maximum, the human density decreases (monotonically decreases) as time passes. Even after time t2, the human density continues to decrease, and at a certain point in time the human density becomes zero.

[0028] The calculation unit 13 determines the change in ultraviolet illuminance over time based on the curve α0 shown in Figure 2. When the calculation unit 13 calculates the change in ultraviolet illuminance over time, the control unit 12 reads (obtains) information related to the change in human density over time from the memory unit 14 in advance. Figure 3 shows the change in ultraviolet illuminance determined by the calculation unit based on the change in human density over time shown in Figure 2. The horizontal axis indicates time. The vertical axis indicates human density or ultraviolet illuminance. The curve α0 represents the change in human density over time shown in Figure 2. The line β0 represents the change in ultraviolet illuminance irradiated from the irradiation unit 11 over time. S represents the area surrounded by the line β0 and the horizontal axis of the graph.

[0029] 3, the area S corresponds to the amount of ultraviolet irradiation. The upper limit of the area S can be appropriately set depending on the usage form of the ultraviolet irradiation system 10 of this embodiment. In one example, when the time from time t1 to time t2 is 8 hours and the irradiation unit irradiates ultraviolet rays of 222 nm, the upper limit of the area S is 22 mJ / cm. 2 In this case, the calculation unit sets the upper limit of the area S to 22 mJ / cm 2 With this as a condition, a change in ultraviolet irradiance over time (irradiation schedule) is determined based on a curve α0 of the change in human density over time. The irradiation schedule includes one or more pairs of ultraviolet irradiance and irradiation time for irradiation at that ultraviolet irradiance. The change in ultraviolet irradiance over time can be determined based on a model created using, for example, machine learning, artificial intelligence (AI), or the like.

[0030] It should be noted that it may be the irradiation unit 11 or the irradiation target that satisfies the upper limit value. When the irradiation unit 11 satisfies the upper limit value, the change over time of the ultraviolet illuminance (projected irradiation) is determined so that the ultraviolet irradiance irradiated from the irradiation unit 11 is equal to or less than the upper limit value. When the irradiation target satisfies the upper limit value, the change over time of the ultraviolet illuminance (projected irradiation) is determined so that the ultraviolet irradiance received by the irradiation target is equal to or less than the upper limit value. In this case, there is a risk that the ultraviolet irradiance irradiated from the irradiation unit 11 will exceed the upper limit value. In this case, the ultraviolet irradiance irradiated from the irradiation unit 11 may be determined according to the distance between the irradiation unit 11 and the irradiation target.

[0031] In the example of FIG. 3, the ultraviolet illuminance increases stepwise after time t1 in response to the increase in the density of people over time. Between time t1 and time t2, the ultraviolet illuminance reaches its maximum, with the time when the density of people is at its maximum sandwiched in between. Thereafter, the ultraviolet illuminance decreases stepwise from its maximum state in response to the decrease in the density of people over time. In this example, the ultraviolet irradiation ends at time t2, so the ultraviolet illuminance becomes zero at time t2. Note that, although the example of FIG. 3 shows the ultraviolet illuminance increasing and decreasing stepwise, the change in the ultraviolet illuminance over time is not limited to this. The change in the ultraviolet illuminance over time can be appropriately set according to the type of light source of the irradiation unit 11 used in the ultraviolet irradiation system 10.

[0032] Fig. 4 is a flowchart showing an example of control executed by the ultraviolet irradiation system 10. When the ultraviolet irradiation system 10 is in use, the process of Fig. 4 is performed, for example, once a day. The control of the irradiation unit 11 by the process of Fig. 4 is performed in a state in which the irradiation unit 11 can illuminate the place where the ultraviolet irradiation system 10 is used.

[0033] As described above, the ultraviolet irradiation system 10 obtains a prediction result of the change over time of the crowding degree in the ultraviolet irradiation area (S401). Based on the obtained prediction result, the calculation unit determines the change over time of the ultraviolet illuminance to be irradiated from the irradiation unit 11 as described above (S402). When it is time to start irradiating ultraviolet rays from the irradiation unit 11, the control unit 12 controls the irradiation unit 11 to start irradiating ultraviolet rays (S403). The control unit 12 obtains the illuminance of the ultraviolet rays to be irradiated and the irradiation time for irradiating ultraviolet rays at the ultraviolet illuminance determined by the calculation unit (S404). If the set irradiation time has not elapsed (S405-No), the control unit 12 continues irradiating ultraviolet rays at the set ultraviolet illuminance. If the irradiation time has elapsed (S405-Yes), the control unit 12 determines whether or not all of the ultraviolet irradiation schedules determined by the calculation unit have been completed (S406). If the ultraviolet irradiation schedule has not been completed (S406-No), the process returns to S403, and the control unit 12 executes the processes from S403 onward. If the ultraviolet irradiation schedule has been completed (S406-Yes), the control unit 12 ends the irradiation of ultraviolet rays from the irradiation unit 11 (S407). This allows viruses and the like to be sterilized quickly and appropriately in the ultraviolet irradiation area while limiting the amount of ultraviolet irradiation received by the human body in the irradiation area to a predetermined upper limit value.

[0034] In the ultraviolet irradiation system 10 of the present embodiment, it is preferable to predict the density of people in the ultraviolet irradiation area based on the past change in the density of people in the ultraviolet irradiation area over time. In this case, in the ultraviolet irradiation system 10, the detection unit 15 shown in Fig. 1 detects the density of people in the ultraviolet irradiation area, and the prediction unit 16 predicts the density of people in the ultraviolet irradiation area.

[0035] The detection unit 15 detects the density of people in the ultraviolet irradiation area. The configuration of the detection unit 15 is not particularly limited as long as it can detect the density of people. The detection unit 15 is, for example, a camera or a CO2 sensor. When a camera is used as the detection unit 15, the detection unit 15 takes an image and / or a video of the illumination area of ​​the irradiation unit 11. When a CO2 sensor is used as the detection unit 15, the detection unit 15 measures the change in the CO2 concentration in the illumination area of ​​the irradiation unit 11 over time. In either configuration, the detection unit 15 writes the detected density of people in the ultraviolet irradiation area and the change in the density of people over time to the memory unit 14.

[0036] The prediction unit 16 predicts the density of people in the ultraviolet irradiation area based on the past density of people in the ultraviolet irradiation area detected by the detection unit 15. The prediction unit 16 predicts a change over time in the density of people in the ultraviolet irradiation area on a date (prediction date) set as a prediction date according to a predetermined prediction model created by machine learning or artificial intelligence (AI) based on the past density of people. The prediction unit 16 may also predict the density of people in the ultraviolet irradiation area based on the latest density of people in the ultraviolet irradiation area in addition to the past density of people in the ultraviolet irradiation area detected by the detection unit 15. In this case, the prediction unit 16 reads out the latest density of people in the ultraviolet irradiation area from the storage unit 14. Then, the prediction unit 16 predicts a change over time in the density of people in the ultraviolet irradiation area on the prediction date based on the latest density of people in the ultraviolet irradiation area. When the predicted date is the current day, the latest human density in the ultraviolet ray irradiation area is the human density in the ultraviolet ray irradiation area obtained by the detection unit 15 up until immediately before the prediction unit 16 starts the prediction.

[0037] FIG. 5 shows a graph of the crowding level when the prediction unit 16 predicts the crowding level using the most recent crowding level in the ultraviolet irradiation area when ultraviolet rays are continuously irradiated on the day shown in FIG. 2. The horizontal axis indicates time. The vertical axis indicates crowding level or ultraviolet illuminance. As in FIG. 2, the ultraviolet irradiation system 10 of this embodiment continuously irradiates ultraviolet rays from time t1 to time t2 as the ultraviolet irradiation period. Time tc is the current time.

[0038] The predicted curve α0 represents the change over time in the human density shown in FIG. 2. The line β0 represents the change over time in the ultraviolet illuminance shown in FIG. 3. S represents the area enclosed by the line β0 and the horizontal axis of the graph. The curve γ0 (shown by a solid line) represents the change over time in the actual human density on the day shown in FIG. 2. The point γc represents the actual human density at the current time. The curve γ1 (shown by a dashed line) represents the change over time in the human density after the point γc, predicted by the prediction unit 16 using the human density up to the point γc in the ultraviolet ray irradiation area.

[0039] As described in FIG. 2 and FIG. 3, the calculation unit 13 determines the change over time (line β0) of the ultraviolet illuminance by the irradiation unit 11 based on the prediction curve α0. In addition, the area S is the ultraviolet illuminance, and satisfies the upper limit condition of the area S. In FIG. 5, the irradiation unit 11 starts continuous irradiation of ultraviolet rays from time t1. After time t1, the predicted value of the human density shown by the prediction curve α0 increases over time, and the actual value of the human density shown by the curve γ0 increases over time. Immediately after time t1, the difference between the predicted value of the human density shown by the prediction curve α0 and the actual value of the human density shown by the curve γ0 is small. In this case, the ultraviolet irradiation system 10 can irradiate ultraviolet rays appropriately according to the human density in the irradiation area by changing the ultraviolet illuminance over time according to the line β0 determined based on the curve α0.

[0040] At the current time tc, the point γc on the curve γ0 is the actual value of the human density in the ultraviolet irradiation area. At this time, the difference between the predicted value of the human density shown by the prediction curve α0 and the value of the point γc is larger than that before the current time tc. That is, the human density in the irradiation area is significantly different from the predicted value of the human density shown by the prediction curve α0. Then, using the value (detection result) of the actual human density up to the latest detection time, the prediction unit 16 predicts the future (future) change in human density over time in the ultraviolet irradiation area, and as a result, the change in human density over time shown by the prediction curve γ1 is obtained. That is, the human density after the current time tc is larger than the human density shown by the prediction curve α0. In this case, even if the ultraviolet irradiation system 10 changes the ultraviolet illuminance over time according to the curve β0, it may not be possible to irradiate ultraviolet light in accordance with the human density in the irradiation area. For example, there is a possibility that the irradiation unit 11 irradiates the irradiation area with ultraviolet light at an ultraviolet light irradiance that is less than the ultraviolet light irradiance required when the human density is at its maximum. In this way, when the prediction unit 16 predicts future changes in human density over time using the value of the actual human density up to the most recent detection time point, and the result deviates from the prediction curve α0 by a predetermined amount or more, the calculation unit 13 re-determines the change in ultraviolet light irradiance (scheduled irradiation) based on the prediction curve γ1.

[0041] FIG. 6 shows the change over time of the ultraviolet irradiance determined by the calculation unit 13 based on the prediction curve γ1 shown in FIG. 5. The horizontal axis indicates time. The vertical axis indicates the crowding degree or ultraviolet irradiance. The line β1 represents the change over time of the ultraviolet irradiance determined based on the prediction curve γ1. The prediction curve α0, the line β0, the curve γ0, the prediction curve γ1, the point γc, and the times t1, t2, and tc are the same as those in FIG. 5. The area S represents the area of ​​the part surrounded by the line β1 and the horizontal axis of the graph, and corresponds to the ultraviolet irradiance. The calculation unit 13 again determines the change over time of the ultraviolet irradiance based on the prediction curve γ1 in the same manner as in FIG. 3, in which the change over time of the ultraviolet irradiance was determined based on the prediction curve α0. Also, in FIG. 6, the area (ultraviolet irradiance) of the part surrounded by the line β1 and the horizontal axis is S, which is the same as in FIG. 2. That is, the calculation unit 13 determines the change over time in the ultraviolet illuminance represented by the line β1 while maintaining the ultraviolet irradiance constant. Note that in order to keep the ultraviolet irradiance below the upper limit, the ultraviolet irradiance may be adjusted not to exceed the upper limit by providing a period during the time period between times t1 and t2 during which the ultraviolet irradiance is suppressed (reduced) or turned off.

[0042] In this way, when the curve γ0, which represents the change over time in the actual human density, deviates from the predicted curve α0, the ultraviolet irradiation system 10 determines a new line β1 based on the predicted curve γ1 predicted using the actual human density up to the most recent detection point. Then, the ultraviolet irradiation system 10 changes the ultraviolet illuminance over time according to the line β1, thereby enabling the ultraviolet irradiation system 10 to appropriately irradiate ultraviolet rays in accordance with the human density in the irradiation area.

[0043] Fig. 7 is a flowchart showing an example of control executed by the ultraviolet irradiation system 10 in the cases shown in Fig. 5 and Fig. 6. As in Fig. 4, when the ultraviolet irradiation system 10 is in use, the ultraviolet irradiation system 10 performs the process of Fig. 7, for example, once a day. The control of the irradiation unit 11 by the process of Fig. 7 is performed in a state in which the irradiation unit 11 can illuminate the place where the ultraviolet irradiation system 10 is used. In the ultraviolet irradiation system 10, the control unit 12 performs the same processes as S401 to S405 in Fig. 4 in S701 to S705.

[0044] When the irradiation time has elapsed (S705-Yes), the control unit 12 acquires the actual human density in the irradiation area acquired by the detection unit 15 (S706). As described above, the control unit 12 causes the prediction unit 16 to predict the future human density in the irradiation area based on the actual human density acquired in S706 (S707). If the newly predicted future human density in the irradiation area is higher than the previous prediction result (S708-Yes), the control unit 12 causes the calculation unit 13 to change the irradiation schedule based on the newly predicted future human density in the irradiation area (S709). If the newly predicted future human density in the irradiation area is almost the same as or lower than the previous prediction result (S708-No), the control unit 12 proceeds with the process without executing the process of S709.

[0045] The control unit 12 determines whether or not all ultraviolet irradiation schedules determined by the calculation unit 13 have been completed (S710). If the ultraviolet irradiation schedule has not been completed (S710-No), the process returns to S704, and the control unit 12 executes the processes from S704 onward. If the ultraviolet irradiation schedule has been completed (S710-Yes), the control unit 12 ends the irradiation of ultraviolet rays from the irradiation unit 11 (S711). This allows viruses and the like to be sterilized in the ultraviolet irradiation area quickly and appropriately while limiting the amount of ultraviolet irradiation to which the human body is exposed in the irradiation area to a predetermined upper limit value.

[0046] As described above, in this embodiment, the control unit 12 of the ultraviolet irradiation system 10 controls the irradiation unit 11 in a state where the ultraviolet irradiation amount in the planned irradiation of the irradiation unit 11 is less than the upper limit value based on the prediction result of the crowding of people in the ultraviolet irradiation area. In addition, the control unit 12 adjusts the ultraviolet irradiation from the irradiation unit 11 over time to a state where the ultraviolet illuminance corresponds to the prediction result. In this way, the ultraviolet irradiation system 10 can appropriately change the ultraviolet irradiation amount according to the crowding of people in the irradiation area. Therefore, the ultraviolet irradiation system 10 can comply with a predetermined value determined as the ultraviolet irradiation amount for one day, for example, and can appropriately sterilize the irradiation area that has become a high infection risk.

[0047] In this embodiment, the ultraviolet irradiation system 10 preferably further includes a detection unit 15. The detection unit 15 can detect the density of people in the irradiation area. The prediction result of the density of people is a result predicted at least based on the density of people detected by the detection unit 15. This allows the ultraviolet irradiation system 10 to use the appropriately predicted density of people in the irradiation area as the prediction result. Therefore, the ultraviolet irradiation system 10 can more appropriately change the irradiation amount of ultraviolet rays according to the density of people in the irradiation area.

[0048] In this embodiment, the ultraviolet irradiation system 10 preferably further includes a prediction unit 16. The prediction unit 16 predicts the future crowding of people in the irradiation area as a prediction result based on at least the crowding of people in the irradiation area. This allows the ultraviolet irradiation system 10 to predict the future crowding of people in the irradiation area based on the crowding of people in the irradiation area. Therefore, the ultraviolet irradiation system 10 can more appropriately change the irradiation amount of ultraviolet rays according to the crowding of people in the irradiation area.

[0049] In this embodiment, the prediction result used by the ultraviolet irradiation system 10 is preferably a result predicted based at least on the density of people in the irradiation area up to the previous day. This allows the ultraviolet irradiation system 10 to use a more appropriately predicted density of people in the irradiation area as the prediction result. Therefore, the ultraviolet irradiation system 10 can more appropriately change the irradiation amount of ultraviolet rays according to the density of people in the irradiation area.

[0050] In the present embodiment, the prediction result used by the ultraviolet irradiation system 10 is preferably a result predicted based at least on the latest human density in the irradiation area. This allows the ultraviolet irradiation system 10 to use a more appropriately predicted human density in the irradiation area as the prediction result. Therefore, the ultraviolet irradiation system 10 can more appropriately change the irradiation amount of ultraviolet light according to the human density in the irradiation area.

[0051] (Modification) In a modified example, the detection unit 15 can detect (measure) the distance between a person in the ultraviolet irradiation area and the irradiation unit 11. In this case, the configuration of the detection unit 15 is not particularly limited as long as the distance between a person in the ultraviolet irradiation area and the irradiation unit 11 can be measured. The calculation unit 13 determines an irradiation schedule in which the ultraviolet irradiation amount is less than the upper limit value described above, based at least on the distance between the person in the irradiation area and the irradiation unit 11. As described above, the ultraviolet irradiation amount is inversely proportional to the square of the distance between the contaminated location and the light source. Therefore, when determining an irradiation schedule in which the ultraviolet irradiation amount is less than the upper limit value, the calculation unit 13 determines the irradiation schedule based at least on the distance to the person closest to the irradiation unit 11. For example, the irradiation schedule is determined so that the ultraviolet irradiation amount is less than the upper limit value even for the person closest to the irradiation unit 11. Then, the control unit 12 controls the irradiation unit 11 according to the irradiation schedule determined by the calculation unit 13. As a result, the ultraviolet irradiation system 10 can perform ultraviolet irradiation in a state in which the upper limit value of the ultraviolet irradiation amount is satisfied.

[0052] In the ultraviolet irradiation system 10, multiple periods during which ultraviolet rays are continuously irradiated may be set per day, and between the multiple periods, periods during which ultraviolet rays are not irradiated from the irradiation unit 11 may be set. In addition, when there is a possibility that the ultraviolet irradiance may exceed the upper limit of the ultraviolet irradiance amount due to a change over time, the irradiation of ultraviolet rays from the irradiation unit 11 may be stopped before the upper limit of the ultraviolet irradiance amount is reached.

[0053] In a modified example, the irradiation unit 11 may be attached to an aircraft. The aircraft may be, for example, a drone or a balloon. In this case, the aircraft moves to a location where the density of people is predicted. The irradiation unit 11 irradiates the location where the density of people is predicted as an irradiation area with ultraviolet light. Also, the control unit 12 cooperates with the prediction unit 16 to analyze the movement of people based on the detection result of the detection unit 15. The control unit 12 may cause the irradiation unit 11 to irradiate ultraviolet light based on the analysis result. In this modified example, the irradiation unit 11 may irradiate ultraviolet light to a location where the number of movement lines per unit area is large (the number of times one or more people come and go is large) as a predicted contaminated location. Also, the irradiation unit 11 may irradiate ultraviolet light to a location where people stay for a long time as a contaminated location or a predicted contaminated location. In this case, the control unit 12 cooperates with the prediction unit 16 to determine whether the number of movement lines and the stay time are long or not based on a predetermined criterion. The predetermined criterion may be a relative criterion based on information on the entire detection range of the detection unit 15, or may be a criterion determined in advance. In this modification, the irradiation unit 11 is attached to the flying object, and the control unit 12 cooperates with the prediction unit 16 to predict the density of people and analyze the movement of people. This allows the ultraviolet irradiation system of this modification to change the amount of ultraviolet irradiation more appropriately. Note that the irradiation of ultraviolet rays based on the above-mentioned analysis of the movement of people may be performed independently of the prediction of the density of people.

[0054] According to at least one of these embodiments, the ultraviolet irradiation system includes an irradiation unit and a control unit. The irradiation unit can irradiate an irradiation area with ultraviolet light. The control unit controls the irradiation unit in an irradiation state in which the ultraviolet light irradiation amount during the irradiation period of the irradiation unit is less than an upper limit value based on a prediction result of the density of people in the irradiation area. In addition, the control unit adjusts the irradiation of ultraviolet light from the irradiation unit over time to a state in which the ultraviolet light illuminance corresponds to the prediction result. This allows the ultraviolet irradiation system to appropriately change the ultraviolet light irradiation amount according to the density of people in the irradiation area.

[0055] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. The following are additional notes. [1] An irradiation unit capable of irradiating an irradiation area with ultraviolet light; a control unit that adjusts over time the irradiation of ultraviolet light from the irradiation unit to an ultraviolet light illuminance corresponding to a prediction result based on a prediction result of a density of people in the irradiation area, while the ultraviolet light irradiation amount in the planned irradiation of the irradiation unit is less than an upper limit value; An ultraviolet irradiation system comprising: [2] Further comprising a detection unit capable of detecting the density of people in the irradiation area; The prediction result is a result predicted based at least on the density of people detected by the detection unit. 2. The ultraviolet irradiation system according to claim 1. [3] Further comprising a prediction unit that predicts a future crowding rate in the projection area as the prediction result based on at least the crowding rate in the projection area. 3. The ultraviolet irradiation system according to claim 1 or 2. [4] The predicted result is a result predicted based at least on the density of people in the irradiation area up to the previous day. 4. The ultraviolet irradiation system according to claim 1. [5] The predicted result is a result predicted based at least on the latest human density of the illumination area. 5. The ultraviolet irradiation system according to claim 1. [6] The detection unit can detect a distance between the irradiation unit and a person in the irradiation area, The control unit controls the irradiation unit so that the ultraviolet ray irradiation amount is less than the upper limit value based on at least the distance between the irradiation unit and the person detected by the detection unit. 3. The ultraviolet irradiation system according to claim 2. [Explanation of symbols]

[0056] 10: ultraviolet irradiation system, 11: irradiation unit, 12: control unit, 13: calculation unit, 14: memory unit, 15: detection unit, 16: prediction unit.

Claims

1. An irradiation unit capable of irradiating an irradiation area with 222 nm ultraviolet light; a control unit that adjusts over time the irradiation of ultraviolet rays from the irradiation unit to an ultraviolet illuminance corresponding to a prediction result based on a prediction result of a density of people in the irradiation area, while the ultraviolet irradiance in the planned irradiation of the irradiation unit is less than an upper limit value; wherein the irradiation unit irradiates the ultraviolet light so that a person in the irradiation area is exposed to the ultraviolet light.

2. A detection unit capable of detecting a density of people in the irradiation area is further provided, The prediction result is a result predicted based at least on the density of people detected by the detection unit. The ultraviolet irradiation system according to claim 1 .

3. A prediction unit that predicts a future crowding rate in the projection area as the prediction result based on at least the crowding rate in the projection area. The ultraviolet irradiation system according to claim 1 or 2.

4. The predicted result is a result predicted based at least on the density of people in the irradiation area up to the previous day. The ultraviolet irradiation system according to any one of claims 1 to 3.

5. The predicted result is a result predicted based at least on the latest human density of the illumination area. The ultraviolet irradiation system according to any one of claims 1 to 4.

6. The detection unit can detect a distance between the irradiation unit and a person in the irradiation area, The control unit controls the irradiation unit so that the ultraviolet ray irradiation amount is less than the upper limit value based on at least the distance between the irradiation unit and the person detected by the detection unit. The ultraviolet irradiation system according to claim 2 .

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