Sterilization device using blue light

Abstract

The present invention relates to a sterilization device using blue light. The sterilization device, according to one embodiment of the present invention, performs a sterilizing action using blue light and comprises: a light-emitting unit for generating blue light; and a control unit for controlling the operation of the light-emitting unit, wherein the control unit controls a pulsing operation for the blue light so that an on-time in which the blue light is generated and an off-time in which the blue light is not generated are alternately repeated.

Description

Sterilization device using blue light

[0001] The present invention relates to a sterilization technology, and more particularly, to a technology for performing a sterilization action using light.

[0002] Interest in sterilization devices has been growing recently due to outbreaks like COVID-19. Accordingly, various devices that utilize light to perform sterilization are being developed.

[0003] In particular, conventional sterilization devices utilizing ultraviolet rays, such as UV-C (i.e., short-wavelength ultraviolet rays) (hereinafter referred to as "first prior art"), kill bacteria by having the ultraviolet rays directly attack and destroy the cell walls or DNA of bacteria. However, the ultraviolet rays used in this first prior art can cause harm, such as accelerating skin aging, when they come into contact with human skin.

[0004] Accordingly, when sterilizing open spaces, the first conventional technology must be implemented to operate only when no one is present, utilizing sensors. In other words, since the first conventional technology requires sensor-based control, it suffers from the problem of complex configuration and increased costs (hereinafter referred to as "the first problem").

[0005] To improve this first problem, a sterilizing device (hereinafter referred to as "the second conventional technology") that utilizes blue light, which does not cause skin aging or other harmful effects even when in contact with human skin, is being developed. For example, the second conventional technology can perform a sterilizing effect based on a blue light LED (Light Emitting Diode) with a wavelength of 405 nm. However, the second conventional technology does not kill bacteria by having the blue light directly attack and destroy the bacterial cell wall or DNA, but rather kills bacteria by increasing the amount of active oxygen within the bacteria exposed to the blue light.

[0006] Accordingly, the second conventional technology must generate light with a higher energy content than the first conventional technology that utilizes ultraviolet rays. That is, since the blue light of the second conventional technology can only have a sterilizing effect when irradiated with a higher energy content than the ultraviolet rays of the first conventional technology, the second conventional technology must either increase the light irradiation time or increase the light output.

[0007] At this time, increasing the light exposure time makes it difficult to perceive the sterilizing effect in everyday life. Furthermore, considering physical time and other factors, there are limits to extending the light exposure time beyond a certain point. Therefore, increasing light output may be a more reasonable approach. However, increasing light output can lead to the following problems (hereinafter referred to as "the second problem").

[0008] First, one of the secondary issues is that it can increase manufacturing costs. Specifically, products with higher light output require a greater number of LEDs, which increases manufacturing costs. Furthermore, the higher light output also increases the cost of other components (especially power supply components), further increasing manufacturing costs.

[0009] Another potential problem is the increased risk of malfunction or burns due to heat generation. LEDs are semiconductor devices that convert electrical energy into light. The conversion rate of electrical energy into light energy is not 100%; it's typically around 30% to 40%. Most of the remaining energy is converted into heat. Consequently, the higher the light output, the more intense the product's heat generation. This heat generation can degrade product performance, cause malfunctions, shorten its lifespan, and even cause burns to users who touch the product.

[0010] Another potential problem is the potential for reduced product portability. High-power products contain a greater number of components, which increases their weight. Furthermore, their high power consumption makes them difficult to operate on battery power, making them virtually impossible to carry.

[0011] However, the above-described content merely provides background information on the present invention and does not correspond to previously disclosed technology.

[0012] In order to solve the problems of the above-described prior art, the purpose of the present invention is to provide a technology that performs a sterilizing action using blue light that is harmless to the human body, but has high sterilizing performance while using less energy.

[0013] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0014] A sterilizing device according to one embodiment of the present invention for solving the above-described problem is a sterilizing device that performs a sterilizing action using blue light, and includes: a light-emitting unit that generates the blue light; and a control unit that controls the operation of the light-emitting unit.

[0015] The above control unit can control the pulse operation for the blue light so that the on time (On Time) during which the blue light is generated and the off time (Off Tiem) during which the blue light is not generated are alternately repeated.

[0016] The above control unit can control the on time to be 10 μs to 1 ms and the off time to be 100 μs to 9 ms.

[0017] The above control unit can control the frequency of the pulse of the blue light to be 100 Hz to 9 kHz.

[0018] The above control unit can control the ratio of the off time to the on time to be 1:1 to 1:10.

[0019] The blue light may have a wavelength of 360 nm to 470 nm.

[0020] The principle of killing bacteria by active oxygen, a by-product of the porphyrin reaction of bacteria caused by the blue light, can be utilized.

[0021] The On Time may be operated to operate in the first process in which the porphyrin in the bacteria exposed to the blue light is excited and then stabilized, thereby generating the active oxygen, and the Off Time may be operated to operate in the second process in which the cell wall or DNA of the bacteria is damaged by the active oxygen after the first process.

[0022] The present invention, configured as described above, can perform a sterilizing action using blue light that is harmless to the human body, and has the advantage of being able to increase sterilizing performance while using less energy.

[0023] In particular, the present invention enables sterilization using blue light even with low energy consumption, so there is no need to increase the light output beyond a certain level for the sterilization effect, thereby reducing manufacturing costs, reducing heat generation and the risk of burns, and increasing portability because it can be implemented with a small number of parts. In other words, the present invention has the advantage of solving the second problem described above.

[0024] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention belongs from the description below.

[0025] Figure 1 shows a schematic block diagram of a sterilizing device (10) according to one embodiment of the present invention.

[0026] Figure 2 shows an example of pulse-shaped blue light generated according to the present sterilizing device (10).

[0027] The above-described objects, means, and resulting effects of the present invention will become more apparent through the following detailed description, taken in conjunction with the accompanying drawings. Accordingly, those skilled in the art will be able to readily implement the technical concepts of the present invention. Furthermore, in describing the present invention, if a detailed description of known technology related to the present invention is deemed to unnecessarily obscure the gist of the invention, such detailed description will be omitted.

[0028] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms, unless specifically stated otherwise. In this specification, terms such as "include," "provide," "provide," or "have" do not exclude the presence or addition of one or more other components other than the mentioned components.

[0029] In this specification, terms such as "or", "at least one", etc. may refer to one of the words listed together, or to a combination of two or more. For example, "A or B", "at least one of A and B" may include only one of A or B, or may include both A and B.

[0030] In this specification, descriptions using the phrase "for example" or the like should not be construed as limiting the embodiments of the invention in terms of the effects of variations such as tolerances, measurement errors, limitations of measurement accuracy, and other commonly known factors, including the information presented, such as cited characteristics, variables, or values, may not be exact matches.

[0031] In this specification, when a component is described as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components in between. Conversely, when a component is described as being "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0032] In this specification, when a component is described as being "on" or "in contact with" another component, it should be understood that it may be directly on or connected to the other component, but there may be another component in between. Conversely, when a component is described as being "directly on" or "in direct contact with" another component, it should be understood that there is no other component in between. Other expressions that describe the relationship between components, such as "between" and "directly between", can be interpreted similarly.

[0033] In this specification, terms such as "first" and "second" may be used to describe various components, but the components should not be limited by these terms. Furthermore, these terms should not be construed to limit the order of each component, but rather may be used to distinguish one component from another. For example, a "first component" may be referred to as a "second component," and similarly, a "second component" may also be referred to as a "first component."

[0034] Unless otherwise defined, all terms used herein may be used in their common sense by those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0035] Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings.

[0036] Figure 1 shows a schematic block diagram of a sterilizing device (10) according to one embodiment of the present invention.

[0037] A sterilizing device (10) according to one embodiment of the present invention (hereinafter referred to as "the sterilizing device") is a device that performs a sterilizing action using blue light, and as illustrated in FIG. 1, may include a light emitter (100), a pulse driver (200), and a controller (300). That is, the sterilizing device (10) is a technology related to the second conventional technology described above, and can kill bacteria by irradiating blue light in a pulse form with a preset duty ratio and frequency according to pulse driving.

[0038] The light-emitting unit (100) is configured to generate blue light. That is, the light-emitting unit (100) may include a blue light LED (Light Emitting Diode). In this case, the blue light generated from the light-emitting unit (100) may include a wavelength band of 360 nm to 470 nm. This blue light has the advantage of not causing any harm, such as skin aging, even if it comes into contact with human skin.

[0039] For example, the blue light generated from the light emitting unit (100) may include a wavelength band of 405 nm, and in particular, it may be preferable that the wavelength band with the greatest intensity be 405 nm, but is not limited thereto.

[0040] The pulse driving unit (200) is a component that drives the light emitting unit (100), and supplies a direct current for pulse driving to the light emitting unit (100). That is, the pulse driving unit (200) can supply a direct current to the light emitting unit (100) that causes the light emitting unit (100) to generate blue light in a pulse form. At this time, the pulse driving unit (200) can supply a direct current for pulse driving to the light emitting unit (100) by switching the direct current supplied from the power supply unit (not shown) of the sterilizing device (10).

[0041] For example, the power supply unit may supply DC power using commercial power (such as 220 V or 110 V) or may supply DC power using a rechargeable battery included in the sterilizing device (10). Of course, the pulse driving unit (200) may supply a pulse driving DC current corresponding to a preset duty ratio and frequency to the light emitting unit (100) under the control of the control unit (300).

[0042] For example, the pulse driving unit (200) may include at least one switching element (e.g., FET, etc.) whose on / off is controlled according to a control signal of the control unit (300). Such a switching element may be turned on / off according to the control signal and supply a pulse driving direct current corresponding to a preset duty ratio and frequency to the light emitting unit (100).

[0043] The control unit (300) may include a processor and a memory. The memory may store instructions regarding the control algorithm of the light emitting unit (100) and the pulse driving unit (200) and related data such as frequency, duty ratio, and wavelength, and the processor may use the data stored in the memory and execute at least one instruction to control the light emitting unit (100) and the pulse driving unit (200).

[0044] The control unit (300) can control the operation of the sterilizing device (10). Accordingly, the control unit (300) can control the operation of the light emitting unit (100) and the pulse driving unit (200). In particular, the control unit (300) can control the pulse driving of the pulse driving unit (200). That is, the control unit (300) can control the pulse driving unit (200) to switch the direct current at a preset pulse duty ratio and switching frequency.

[0045] Accordingly, the control unit (300) can control the light emitting unit (100) to generate blue light in the form of pulses with preset duty ratios and frequencies. Of course, the duty ratio and frequency of the pulses can be set to specific specifications as default, and can also be implemented so that the user can set or change the duty ratio and frequency of the pulses through an input unit (not shown) as needed.

[0046] Meanwhile, blue light such as the 405 nm wavelength band used in the present sterilizing device (10) is useful for sterilizing bacteria. In particular, when blue light is irradiated to bacteria, the blue light is absorbed by the porphyrin of the bacteria. At this time, porphyrin is a pigment protein present in bacteria and exists in most living organisms including bacteria. Such porphyrin recognizes stimuli in bacteria and plays a role in decomposing harmful substances, and is activated by specific light such as blue light in the 405 nm wavelength band, and the activated porphyrin is also expressed as porphyrin*.

[0047] Porphyrins activated by specific light react with surrounding oxygen to stabilize themselves, primarily reducing oxygen molecules to generate reactive oxygen species. This porphyrin reaction can be simply formulated as follows:

[0048] ① Blue light of wavelength 405 nm, etc. + porphyrin -> porphyrin*

[0049] ② Porphyrin* + oxygen molecule -> porphyrin + active oxygen

[0050] That is, when bacteria are irradiated with blue light, the porphyrin of the bacteria that has absorbed the blue light is excited by the blue light and then stabilized, generating reactive oxygen species such as singlet oxygen and triplet oxygen. For reference, the excited porphyrin is denoted as porphyrin* in ②.

[0051] These reactive oxygen species can be absorbed into bacterial DNA, forming pyramidal dimers that alter its structure. They can also react with cell wall lipids, damaging the cell wall. Reactive oxygen species are highly reactive, and when absorbed into bacterial cell walls or DNA, they destroy its molecular structure. Consequently, excessive amounts of reactive oxygen species can kill bacteria.

[0052] The method of killing bacteria using blue light according to the present sterilizing device (10) is not a method in which the blue light directly attacks and destroys the cell wall or DNA of bacteria as in the first conventional technology described above, but a method in which the blue light generates porphyrin reaction and active oxygen, a by-product of the porphyrin reaction, and utilizes this. However, in order for this method to work properly, a large amount of energy is required. That is, in order to kill bacteria according to the present sterilizing device (10), a sufficient amount of active oxygen must be generated, and for this purpose, a greater amount of energy may be required than in the first conventional technology described above.

[0053] Accordingly, a method is needed to kill bacteria more effectively using blue light while reducing the amount of energy, and this will be explained below.

[0054] The sterilization method of this sterilization device (10) corresponds to a method of killing bacteria by damaging the cell membrane or DNA of bacteria by active oxygen (i.e., singlet oxygen and triplet oxygen) generated when the porphyrin of bacteria that absorbs the blue light generated from the light-emitting unit (100) is excited and then stabilized. The process of this sterilization method can be broadly divided into the first and second processes.

[0055] First, the first process is the process in which the bacterial porphyrin pigment protein is excited by blue light, which corresponds to process ① described above. That is, when blue light is irradiated on bacteria, the bacterial porphyrin pigment protein enters an excited state. Next, the second process is the process in which the excited porphyrin pigment protein is stabilized, generating singlet oxygen, and triplet oxygen is generated by the singlet oxygen. In other words, the second process corresponds to process ② described above.

[0056] In particular, blue light is only directly involved in the first process and not in the second process. In other words, blue light is only necessary for the occurrence of the first process, and if the first process occurs due to blue light, the second process will occur naturally over time even without blue light. If blue light is irradiated during the time of the second process, which is not involved in blue light, the blue light in question is merely a loss.

[0057] Accordingly, when blue light is irradiated only for the first process that requires blue light and blue light is not irradiated for the second process that does not require blue light, the amount of energy can be saved compared to when blue light is always on as the blue light illumination time is reduced.

[0058] Figure 2 shows an example of pulse-shaped blue light generated according to the present sterilizing device (10).

[0059] The present sterilizing device (10) performs a sterilizing action using this principle, and accordingly, the control unit (300) can control the pulse driving unit (200) so that pulse-shaped blue light is generated from the light-emitting unit (100), as illustrated in FIG. 2. That is, the pulse-shaped blue light includes an On state region where blue light is generated and an Off state region where blue light is not generated, and these are alternately included. At this time, the degree of alternation of the On / Off states occurs periodically according to a preset duty ratio and frequency, and this is controlled by the control unit (300). At this time, the duty ratio means the ratio of the On time, which is the time of the On state, in the pulse-shaped blue light having a periodicity.

[0060] That is, if the on time (On Time) is t1 and the off time (Off Time), which is the time in the off state, is t2, the duty ratio D can be expressed as in the following [Mathematical Formula 1]. At this time, the unit of D is %.

[0061] [Mathematical Formula 1]

[0062]

[0063] The sterilizing device (10) performs a first operation of generating blue light from the light emitting unit (100) for the first process, and then performs a second operation of not generating blue light from the light emitting unit (100) during the second process. At this time, the control unit (300) controls the first and second operations to be alternately and repeatedly performed according to a preset duty ratio and frequency, and accordingly, blue light is generated in the form of pulses from the light emitting unit (100) according to the corresponding duty ratio and frequency. That is, the control unit (300) can control the second operation to be performed during the second process after the first operation is performed for the first process, and these first and second operations to be alternately and repeatedly performed according to the preset duty ratio and frequency. Accordingly, the sterilizing device (10) does not generate blue light during the second process in which blue light is unnecessary, thereby reducing the lighting time of the blue light, which has the advantage of saving energy.

[0064] Meanwhile, more effective bacterial killing is possible when pulsed blue light is irradiated at a specific duty ratio and frequency. This is because, at the specific duty ratio and frequency, the probability that blue light will be generated as the first action in the first process and not generated as the second action in the second process can be greatly increased.

[0065] <First consideration for determining specific duty cycle and frequency>

[0066] That is, the ratio of the on time and off time of the blue light in pulse form is very important, and in order to determine the specific duty ratio and frequency accordingly, it is necessary to consider the times of the first and second processes. At this time, the time required for the reaction according to the first process to occur varies according to the following conditions.

[0067] 1) Wavelength of light

[0068] The absorption rate of blue light varies depending on its wavelength, resulting in differences in porphyrin activation. Porphyrin absorbs blue light most strongly at 405 nm, while absorption is very low at wavelengths above 450 nm. Consequently, the time required for porphyrin activation varies depending on the wavelength of blue light.

[0069] 2) Conditions of the surrounding environment

[0070] The reaction rate of porphyrin activation also varies depending on whether the surrounding environment is acidic, neutral, or basic. Of course, the reaction rate also varies depending on the surrounding temperature.

[0071] Under optimal conditions, the time required for porphyrin activation is approximately 10 μs. However, under unfavorable conditions such as the wavelength of blue light and the surrounding environment, porphyrin activation may require longer time, up to 1 ms or more. However, a time required for porphyrin activation exceeding 1 ms is considered unusual. Therefore, considering the time of the first process, it may be desirable for the on time of the pulsed blue light to be 10 μs or more and 1 ms or less. In this case, the on time corresponds to the time for one pulse in the on state.

[0072] Additionally, the time required for the second process and for the porphyrin to become completely stabilized after the second process to enable the next reaction (i.e., the subsequent reaction according to the first process) varies depending on the distribution concentration of oxygen molecules in the surroundings and the pH concentration, and the time can be approximately 100 μs to 1 ms. In other words, the time required for the activated porphyrin to become stabilized again and to enable the next reaction varies depending on environmental conditions and the type of bacteria.

[0073] To summarize the above, the minimum On Time required for the activation reaction of porphyrin is 10 μs, and the minimum Off Time required thereafter is 100 μs. In this case, the approximate frequency is 9 kHz, and the On Time / Off Time ratio is 1:11 (i.e., the duty ratio is approximately 8.3%). In addition, based on the condition of the slowest activation reaction of porphyrin, the maximum On Time is 1 ms, and the maximum Off Time required thereafter is 1 ms. In this case, the frequency is 500 Hz, and the On Time / Off Time ratio is 1:1 (i.e., the duty ratio is 50%).

[0074] Therefore, considering the reaction time of porphyrin, the frequency at which pulsed blue light has a sterilizing effect is 500 Hz to 9 KHz, and the on time / off time ratio is 1:1 to 1:11 (i.e., the duty ratio is 8.3% to 50%).

[0075] <Second Consideration for Determining Specific Duty Ratio and Frequency>

[0076] Meanwhile, since LEDs have a very fast response speed, instantaneous on / off control is possible. Generally, when adjusting the brightness of an LED through current control, the current applied to the LED is checked momentarily through a sensor, and the brightness is controlled by changing the lighting cycle by feeding back this. This driving is referred to as "PWM (Pulse Width Modulation) brightness control." Of course, in the present sterilizing device (10), the control unit (300) can perform such PWM brightness control.

[0077] Because LEDs light up instantaneously, they can use higher currents than when they are turned on continuously. This varies depending on the type and structure of the LED, as well as the instantaneous lighting cycle and rate, but it is generally recommended to use currents up to 10 times higher. The current used is roughly proportional to the inverse of the lighting rate (i.e., duty ratio). If the current exceeds 10 times, the LED chip may be damaged, the LED lifespan may be drastically reduced, or the likelihood of LED failure may increase.

[0078] That is, if the ratio of On Time / Off Time exceeds 1:10 (i.e., the duty ratio is less than about 9%), it is not desirable considering the characteristics of the LED that it is difficult to apply more than 10 times the maximum output. Accordingly, it may be desirable that the ratio of On Time / Off Time be 1:10 or less (i.e., the duty ratio is about 9% or more).

[0079] At this time, if the ratio of On Time / Off Time is set to 1:10 or less (i.e., the duty ratio is approximately 9% or more), not only can the manufacturing cost be minimized while optimizing the sterilization performance, but also the energy consumption can be saved. In particular, if the On Time is set to 1 ms and the Off Time is set to 9 ms, the instantaneous maximum output can be applied up to 10 times higher than in the case of continuous operation, so the instantaneous output can be increased to increase the average light output, and as a result, the sterilization performance can be improved while minimizing energy consumption. In this case, since the On Time is 1 ms and the Off Time is 9 ms, the frequency is 100 Hz.

[0080] The first and second considerations described above can be summarized as follows. That is, according to the first consideration, the On Time for irradiating blue light during the activation reaction time of porphyrin (i.e., during the first process) is preferably 10 μs to 1 ms, considering the surrounding environment and bacterial strains. In addition, according to the first and second considerations, considering that the activated porphyrin generates active oxygen and prepares for the next reaction while at the same time increasing the maximum output of the LED, the Off Time is preferably 100 μs to 9 ms. Depending on the range of the On Time and Off Time, the frequency may be preferably 100 Hz to 9 kHz and the On Time / Off Time ratio may be preferably 1:1 to 1:10 (i.e., the duty ratio may be approximately 9% to 50%).

[0081] To confirm the sterilizing effect at the frequency and duty ratio according to the first and second considerations, the first and second experiments were conducted, which are described below.

[0082] Experiment 1

[0083] First, the first experiment was conducted by driving blue light of the 405 nm wavelength band in the form of pulses with a constant frequency and various duty ratios. That is, E. coli was irradiated with blue light of 405 nm in the form of pulses with a constant frequency, but the duty ratios of the pulse shapes were set differently.

[0084] At this time, in experimental group 1, pulsed blue light with a frequency of 1000 Hz and an On Time / Off Time ratio of 1:9 (i.e., a duty ratio of 10%) was used. In experimental group 2, pulsed blue light with a frequency of 1000 Hz and an On Time / Off Time ratio of 1:4 (i.e., a duty ratio of 20%) was used. In experimental group 3, pulsed blue light with a frequency of 1000 Hz and an On Time / Off Time ratio of 1:1 (i.e., a duty ratio of 50%) was used. In experimental group 4, pulsed blue light with a frequency of 1000 Hz and an On Time / Off Time ratio of 1:0.5 (i.e., a duty ratio of 66%) was used. In experimental group 5, pulsed blue light was not used, but continuous blue light without an off time was used.

[0085] In Experimental Groups 1, 2, and 3, the light output per second was 170 mJ / cm2 ± 5 mJ / cm2, which was equivalent to the light output. In other words, Experimental Group 1 had a peak power four times higher than that of Experimental Group 3, and Experimental Group 2 had a peak power twice as high as that of Experimental Group 3.

[0086] In each experimental group, a blue light LED module was fixed to the top of the medium inoculated with E. coli, and the blue light was irradiated to the E. coli. The density of E. coli in the experimental medium for each experimental group was checked after 30 minutes and 1 hour. Meanwhile, in Control Group 1, the medium inoculated with E. coli was placed in a dark room (i.e., an area without light), and the density of E. coli was checked after 30 minutes and 1 hour. The results of this density check are shown in Table 1 below.

[0087] E. coli density after 30 minutes E. coli density after 1 hour Experimental group 1 (1:9, duty ratio 10%) 3.3 x10 4 5.3x10 3Experimental group 2 (1:4, duty ratio 20%) 7.6x10 4 1.9x10 4 Experimental group 3 (1:1, duty ratio 50%) 1.5x10 5 3.4x10 4 Experimental group 4 (1:0.5, duty ratio 66%) 4.7 x10 5 7.8 x10 4 Experimental group 5 (continuous) 5.3x10 5 9.2x10 4 Control group 1 (dark room) 3.8x10 6 4.2x10 6

[0088] A rough look at the results of the first experiment shows that, based on the same amount of energy irradiated, in the case of a 10% duty ratio (i.e., experimental group 1), bacteria were reduced by more than 10 times compared to continuous irradiation, in the case of a 20% duty ratio (i.e., experimental group 2), bacteria were reduced by more than 5 times compared to continuous irradiation, and in the case of a 50% duty ratio (i.e., experimental group 3), bacteria were reduced by more than 2.5 times compared to continuous irradiation. In addition, in the case of a 66% duty ratio (i.e., experimental group 4), there was no significant difference, approximately 1.2 times compared to continuous irradiation. <Experiment 2> Next, a second experiment was additionally conducted on the cycle of the on time (On Time) / off time (Off Time) of blue light. At this time, blue light with a wavelength of 405 nm was driven in the form of pulses with a constant duty ratio and various frequencies. That is, E. coli was irradiated with 405 nm blue light in the form of pulses with a constant duty ratio, but the frequency of the pulse forms was set differently.

[0089] At this time, in experimental group 6, pulsed blue light with a frequency of 10 Hz and an On Time / Off Time ratio of 1:1 (i.e., a duty ratio of 50%) was used. In experimental group 7, pulsed blue light with a frequency of 100 Hz and a duty ratio of 1:1 (i.e., a duty ratio of 50%) was used. In experimental group 8, pulsed blue light with a frequency of 1000 Hz and an On Time / Off Time ratio of 1:1 (i.e., a duty ratio of 50%) was used. In experimental group 9, pulsed blue light with a frequency of 10,000 Hz and an On Time / Off Time ratio of 1:1 (i.e., a duty ratio of 50%) was used. In experimental group 10, blue light that was continuously lit without an Off Time was used instead of pulsed blue light.

[0090] In each experimental group, a blue light LED module was fixed to the top of the medium inoculated with E. coli, and the blue light was irradiated to the E. coli. The density of E. coli in the experimental medium for each experimental group was checked after 30 minutes and 1 hour. Meanwhile, for Control Group 2, the medium inoculated with E. coli was placed in a dark room and left, and the density of E. coli was checked after 30 minutes and 1 hour. The results of this density check are shown in Table 2 below.

[0091] E. coli density after 30 minutes E. coli density after 1 hour Experimental group 6 (10 Hz) 3.9 x 10 5 6.7x10 4 Experimental group 7 (100Hz) 2.4x10 5 8.2x10 4 Experimental group 8 (1000Hz) 1.2x10 5 3.8x10 4 Experimental group 9 (10,000 Hz) 1.6x10 5 5.1x10 4 Experimental group 10 (continuous) 4.8x10 5 9.5x10 4 Control group 2 (dark room) 4.1x10 6 4.6x10 6

[0092] A rough look at the results of the second experiment shows that, based on the same amount of energy irradiated, in the case of 1000 Hz frequency / 50% duty ratio operation (i.e., experimental group 8), bacteria were reduced by more than 3 times compared to continuous irradiation, in the case of 10,000 Hz frequency / 50% duty ratio operation (i.e., experimental group 9), bacteria were reduced by more than 2.5 times compared to continuous irradiation, and in the case of 100 Hz frequency / 50% duty ratio operation (i.e., experimental group 7), bacteria were reduced by more than 2 times compared to continuous irradiation. In addition, in the case of 10 Hz frequency / 50% duty ratio operation (i.e., experimental group 6), it was confirmed that there was no significant difference of approximately 1.2 times compared to the case of continuous irradiation. That is, when using pulsed blue light with a specific duty ratio and frequency, the blue light is appropriately irradiated only until the porphyrin of the bacteria is activated, and then an appropriate rest period in which the blue light is not irradiated occurs. At this time, since the blue light is not irradiated during the time when the porphyrin activated by the blue light generates active oxygen, energy waste can be prevented, and ultimately, a higher sterilization effect is possible with less energy. In particular, it is confirmed through the first and second experiments that this effect is effective at the frequency and duty ratio according to the first and second considerations. That is, the frequency according to the first and second considerations may correspond to 100 Hz to 9 kHz, and the On Time / Off Time ratio according to the first and second considerations may correspond to 1:1 to 1:10 (i.e., the duty ratio may correspond to about 9% to 50%).

[0093] Accordingly, in order to enable a high sterilization effect while consuming a small amount of energy, it may be desirable for the control unit (300) to control the light emitting unit (100) to output pulse-shaped blue light at the above-described specific duty ratio and frequency. At this time, it may be desirable for the specific duty ratio to fall within the range of 1:1 to 1:10 in the ratio of on time (On Time) to off time (Off Time), and it may be desirable for the specific frequency to fall within the range of 100 Hz to 9 kHz. In the case of a duty ratio and frequency outside the above range, the bacterial killing efficiency may decrease, the energy saving effect may decrease, or the light emitting unit (100) including the LED may be overloaded.

[0094] For example, in Experimental Group 2, the On Time consumes only 20% of the power of the constant lighting. Therefore, if the output of the constant lighting is adjusted to the same level as in Experimental Group 2 and a sterilization experiment is conducted, the time required to sterilize 99.9% of E. coli can be reduced by up to 50% compared to the constant lighting.

[0095] The sterilizing device (10) configured as described above can perform a sterilizing action using blue light that is harmless to the human body, and has the advantage of being able to increase sterilizing performance while using less energy in particular. Accordingly, since the sterilizing device (10) can perform a sterilizing action using blue light even with less energy, unlike the second conventional technology, there is no need to increase the light output above a certain level for the sterilizing action. As a result, the sterilizing device (10) can reduce the manufacturing cost compared to the second conventional technology, reduce the risk of heat generation and burns, and can be implemented with a small number of parts, so it has the advantage of being able to increase portability. In other words, the sterilizing device (10) has the advantage of being able to solve the second problem described above.

[0096] While the detailed description of the present invention has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention is not limited to the described embodiments, but should be determined by the claims and their equivalents.

Claims

1. A sterilizing device that performs sterilizing action using blue light, A light-emitting part that generates the blue light; and It includes a control unit that controls the operation of the above light-emitting unit; A sterilizing device in which the control unit controls the pulse operation for the blue light so that the on time (On Time) during which the blue light is generated and the off time (Off Tiem) during which the blue light is not generated are alternately repeated.

2. In paragraph 1, A sterilizing device in which the control unit controls the on time to be 10 μs to 1 ms and the off time to be 100 μs to 9 ms.

3. In paragraph 1, A sterilizing device in which the control unit controls the frequency of the pulse of the blue light to be 100 Hz to 9 kHz.

4. In paragraph 1, A sterilizing device in which the control unit controls the ratio of the off time to the on time to be 1:1 to 1:

10.

5. In paragraph 1, A sterilizing device wherein the blue light has a wavelength of 360 nm to 470 nm.

6. In paragraph 1, A sterilizing device that utilizes the principle that bacteria are killed by active oxygen, a by-product of the porphyrin reaction of bacteria caused by the blue light.

7. In paragraph 6, A sterilizing device that operates so that the On Time operates in a first process in which the porphyrin in the bacteria exposed to the blue light is excited and stabilized, thereby generating the active oxygen, and operates so that the Off Time operates in a second process in which the cell wall or DNA of the bacteria is damaged by the active oxygen after the first process.

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