JP7659732B2 - Sterilization and purification equipment - Google Patents

Description

An embodiment of the present invention relates to a sterilization and purification device.

Reflecting growing health consciousness, there is an increasing demand for gas purification (e.g., air purification) and sterilization and inactivation of bacteria and viruses in so-called closed spaces such as the inside of trains and automobiles, refrigerators, and living spaces. For example, there is a growing demand for the removal of ammonia and ethylene generated from food, the removal and deodorization of VOCs (Volatile Organic Compounds) such as acetaldehyde contained in cigarette smoke, and the sterilization and inactivation of bacteria and viruses contained in gas.

For this reason, a photocatalyst device has been proposed that includes a light source having a plurality of light-emitting diodes and a photocatalyst filter carrying a photocatalyst.
In addition, foreign matter such as dust contained in the atmosphere in which the sterilization and purification device is installed may be sucked into the sterilization and purification device together with the gas to be treated. If the foreign matter sucked into the sterilization and purification device adheres to the photocatalytic filter or the light-emitting diode, the function of the sterilization and purification device may be reduced. Therefore, a filter (also called a pre-filter) that captures foreign matter in the gas flow direction may be provided upstream of the photocatalytic filter.

Generally, photocatalytic filters carry a so-called ultraviolet light responsive photocatalyst. For this reason, a light emitting diode that irradiates ultraviolet light is used as the light source. Since ultraviolet light has a bactericidal effect, a photocatalytic device equipped with a light emitting diode that irradiates ultraviolet light can purify gases using active oxygen species generated by photocatalytic action, and bacteria and viruses can be sterilized or inactivated to a certain extent by the generated active oxygen species and ultraviolet light.

In this case, even if ultraviolet light is irradiated onto the filter installed upstream of the photocatalytic filter, no photocatalytic action is exhibited. Therefore, in general, in order to increase the efficiency of using the ultraviolet light irradiated from the light-emitting diode, the amount of ultraviolet light that passes through the photocatalytic filter is reduced. As a result, in general, very little of the ultraviolet light irradiated from the light-emitting diode reaches the filter installed upstream of the photocatalytic filter.

When gas is sucked into the sterilization and purification device, bacteria and viruses contained in the gas may adhere to the filter. Because the ultraviolet light emitted from the light-emitting diode hardly reaches the filter, it is not possible to sterilize or inactivate the bacteria or viruses using ultraviolet light. As a result, the infectiousness of the bacteria and viruses that adhere to the filter is maintained for a certain period of time, so if an operator touches the filter during maintenance, etc., the operator may become infected with bacteria or viruses.

In this case, it is possible to further provide a light source for irradiating the filter with ultraviolet light, but this would result in an increase in size, cost, and installation space of the sterilization and purification device.
Furthermore, when a photocatalytic filter and a light-emitting diode that irradiates ultraviolet light are provided, the photocatalytic effect may decrease over time.
Therefore, there was a need for the development of a sterilization and purification device that could sterilize and inactivate bacteria and viruses attached to a filter with a simple configuration and that could suppress the deterioration of the photocatalytic action over time .

JP 2011-218073 A

The problem that the present invention aims to solve is to provide a sterilization and purification device that can sterilize and inactivate bacteria and viruses attached to a filter with a simple configuration and can suppress the deterioration of photocatalytic action over time .

The sterilization and purification device according to the embodiment includes a photocatalytic filter having a sheet and a photocatalyst supported on the sheet; a light source facing the photocatalytic filter and having a first light-emitting element and a second light-emitting element; and a filter facing the photocatalytic filter and provided on the opposite side of the photocatalytic filter from the light source side. The first light-emitting element irradiates the photocatalytic filter with a first light. The second light-emitting element irradiates the photocatalytic filter with a second light, which is ultraviolet light having a shorter peak wavelength than the first light. A part of the second light irradiated to the photocatalytic filter passes through the photocatalytic filter and is irradiated to the filter . When the light source irradiates light, a gas is released from the light source. The gas to be treated flows from the filter side toward the light source side, and the released gas is prevented from reaching the photocatalytic filter by the flow of the gas to be treated.

According to an embodiment of the present invention, a sterilization and purification device can be provided that has a simple configuration and can sterilize and inactivate bacteria and viruses attached to a filter, and can suppress the deterioration of photocatalytic activity over time .

FIG. 2 is a schematic exploded view illustrating the sterilization and purification device according to the present embodiment. 2 is a schematic cross-sectional view of the sterilization and purification device in FIG. 1 taken along line AA. FIG. 11 is a schematic cross-sectional view illustrating a sterilization and purification device according to a comparative example.

Hereinafter, an embodiment will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.
FIG. 1 is a schematic exploded view illustrating a sterilization and purification device 1 according to the present embodiment.
FIG. 2 is a schematic cross-sectional view of the sterilization and purification device 1 in FIG. 1 taken along line AA.
As shown in FIGS. 1 and 2 , a sterilization and purification device 1 includes, for example, a frame 2 , a lid 3 , a light source 4 , a photocatalytic filter 5 , and a filter 6 .

The frame 2 has a box shape. When viewed from the inflow side of the gas G, the outline of the frame 2 can be approximately rectangular. The outline of the frame 2 can also be, for example, approximately polygonal or approximately circular. However, taking into consideration the attachment and detachment of the light source 4, photocatalytic filter 5, and filter 6 described below and space efficiency, it is preferable that the outline of the frame 2 be approximately rectangular.

One end 2a of the frame 2 is open. The end 2b of the frame 2 opposite the end 2a is closed. One side 2c of the frame 2 has a hole 2c1. One side 2d of the frame 2 opposite the side 2c has a hole 2d1.

The hole 2c1 on the side surface 2c and the hole 2d1 on the side surface 2d serve as an inlet or outlet for the gas G to be treated. In this case, as shown in FIG. 2, for example, the hole 2c1 on the side surface 2c can serve as an inlet for the gas G, and the hole 2d1 on the side surface 2d can serve as an outlet for the gas G. When the hole 2d1 serves as an outlet, a fan 7 can be provided on the side surface 2d.

The fan 7 is provided on the opposite side of the light source 4 from the photocatalytic filter 5 side. The fan 7 exhausts the gas G inside the frame 2. The fan 7 forms a flow of gas G that flows from the filter 6 side toward the light source 4 side. The fan 7 is not necessarily required and can be omitted. For example, if the sterilization and purification device 1 is provided in the flow of gas G, the fan 7 can be omitted.

The hole 2c1 on the side surface 2c may be an outlet for gas G, and the hole 2d1 on the side surface 2d may be an inlet for gas G. In other words, it is sufficient that gas G flows from the filter 6 side toward the light source 4 side.

The gas G may be, for example, a gas containing air as a main component and containing the substance to be treated, bacteria, viruses, etc. The substance to be treated may be anything that can be purified by photocatalysis. The substance to be treated may be, for example, ammonia, ethylene, VOCs such as acetaldehyde, etc.

Furthermore, a lattice or the like can be provided on at least one of side 2c and side 2d of frame 2. Providing a lattice can prevent fingers or foreign objects from entering the inside of frame 2.

A plurality of grooves 2e1 are provided on side surface 2e of frame 2, which intersects with side surface 2c. A plurality of grooves 2f1 are provided on side surface 2f of frame 2, which faces side surface 2e. The plurality of grooves 2e1 and the plurality of grooves 2f1 open to the inside of frame 2. The plurality of grooves 2e1 and the plurality of grooves 2f1 are arranged side by side between side surface 2c and side surface 2d of frame 2. The plurality of grooves 2e1 and the plurality of grooves 2f1 extend between end portions 2a and 2b of frame 2.

The groove 2e1 is provided approximately parallel to the opposing groove 2f1. Multiple pairs of opposing grooves 2e1, 2f1 are provided. The multiple pairs of grooves 2e1, 2f1 serve as slots into which the light source 4, photocatalytic filter 5, and filter 6 are inserted. In this case, the filter 6, photocatalytic filter 5, and light source 4 can be arranged in order from the upstream side of the flow of gas G. The dimensions of the pair of grooves 2e1, 2f1 can be changed as appropriate depending on the dimensions of the light source 4, photocatalytic filter 5, and filter 6 to be inserted.

The light source 4, photocatalytic filter 5, and filter 6 inserted into the pair of grooves 2e1, 2f1 are approximately parallel to each other. When the photocatalytic filter 5 and the light source 4 are approximately parallel, the ultraviolet light irradiated from the light source 4 can be efficiently incident on the photocatalytic filter 5. Therefore, the photocatalytic filter 5 can efficiently purify the gas G, and can efficiently sterilize and inactivate bacteria and viruses attached to the photocatalytic filter 5.

If a pair of grooves 2e1, 2f1 into which the light source 4, photocatalytic filter 5, and filter 6 are inserted are provided, the light source 4, photocatalytic filter 5, and filter 6 can be freely inserted and removed inside the frame 2. This improves maintainability. In addition, it becomes easy to change the specifications of the light source 4 and photocatalytic filter 5 according to the flow rate of the gas G, the amount of substances contained in the gas G, the light intensity (light amount) of the ultraviolet light irradiated from the light source 4, etc., and to change the specifications of the filter 6 according to the amount and type of foreign matter contained in the gas G.

There are no particular limitations on the material of the frame 2. However, if the material of the frame 2 is a thermoplastic resin, the frame 2 can be formed using an injection molding method. This can reduce manufacturing costs.

For example, the material of the frame 2 can be ABS resin (acrylonitrile-butadiene-styrene copolymer synthetic resin). If the material of the frame 2 is ABS resin, it is possible to improve moldability and reduce costs. In this case, if the material of the frame 2 is reinforced ABS resin, it is possible to improve the strength of the frame 2. Note that reinforced ABS resin is ABS resin mixed with glass fiber, etc.

The material of the frame 2 may be, for example, polypropylene resin or acrylic resin (polymethyl methacrylate resin). In this case, if the material of the frame 2 is acrylic resin, it will have improved resistance to the ultraviolet light irradiated from the light source 4 and to the VOCs contained in the gas G. Furthermore, if the degree of polymerization of the acrylic resin is about 10,000 to 15,000, odor generation can be suppressed.

The frame 2 can also be made of a metal. If the frame 2 is made of a metal, the rigidity of the sterilization and purification device 1 can be increased. The metal can be, for example, iron, stainless steel, or an aluminum alloy.

The lid 3 is provided at the end 2a of the frame 2. The lid 3 covers the opening at the end 2a. The lid 3 can prevent the light source 4, photocatalytic filter 5, and filter 6 provided inside the frame 2 from coming off. It can also prevent foreign matter from entering the inside of the frame 2. The lid 3 can be attached to the frame 2 using a screw or the like. Also, a hook or the like may be provided on the lid 3, and the hook may be held by a recess or protrusion provided on the frame 2. If the lid 3 is provided on the frame 2 so that it can be easily attached and detached, it is possible to improve maintainability. There is no particular limitation on the material of the lid 3. For example, the material of the lid 3 can be the same as the material of the frame 2.

At least one light source 4 can be provided. The light source 4 is provided inside the frame 2. The light source 4 faces the photocatalytic filter 5. In the flow direction of the gas G, the light source 4 is preferably provided downstream of the photocatalytic filter 5.
The effect of the arrangement of the light source 4 and the photocatalytic filter 5 in the flow direction of the gas G will be described later.

The light source 4 includes, for example, a substrate 4a, a light emitting element 4b (corresponding to an example of a first light emitting element), and a light emitting element 4c (corresponding to an example of a second light emitting element).
The substrate 4a has a plate shape. The substrate 4a is provided in the flow path of the gas G. Therefore, if the substrate 4a is provided, there is a risk that the flow of the gas G may be hindered. In this case, a plurality of holes penetrating in the thickness direction may be provided in the substrate 4a. However, if the size of the holes is small, the pressure loss increases, and the flow of the gas G is hindered. If the size of the holes is large, restrictions arise in the arrangement and number of the light emitting elements 4b and 4c and the wiring patterns.

1, the width W1 of the substrate 4a is made smaller than the width W2 of the photocatalytic filter 5. The width is the dimension in the direction in which the pair of grooves 2e1, 2f1 extend. In this way, it is possible to ensure an appropriate flow of gas G and to prevent restrictions on the arrangement and number of the light-emitting elements 4b, 4c and the wiring patterns.
According to the findings of the present inventors, if "W1 (mm)/W2 (mm)" is smaller than 0.5, it is easy to ensure an appropriate flow of gas G.

There are no particular limitations on the material or structure of the substrate 4a. For example, the substrate 4a can be made of inorganic materials (ceramics) such as aluminum oxide or aluminum nitride, or organic materials such as paper phenol or glass epoxy. The substrate 4a may also be a metal core substrate in which the surface of a metal plate is covered with an insulating material.

When the light emitting elements 4b and 4c generate a large amount of heat, it is preferable to form the substrate 4a using a material with high thermal conductivity from the viewpoint of heat dissipation. It is also preferable to form the substrate 4a using a material with high resistance to ultraviolet light irradiated from the light emitting elements 4b and 4c. For example, it is preferable to form the substrate 4a from ceramics such as aluminum oxide or aluminum nitride, a metal core substrate, or the like.
Furthermore, the substrate 4a may have a single-layer structure or a multi-layer structure.

The light-emitting element 4b can be provided on the surface of the substrate 4a facing the photocatalytic filter 5. The light-emitting element 4b is, for example, electrically connected to a wiring pattern provided on the surface of the substrate 4a. There are no particular limitations on the type of the light-emitting element 4b. The light-emitting element 4b can be, for example, a surface-mount type light-emitting element such as a PLCC (Plastic Leaded Chip Carrier) type. The light-emitting element 4b can also be, for example, a light-emitting element having leads such as a bullet type.

The light-emitting element 4b may also be mounted by COB (Chip On Board). When the light-emitting element 4b is mounted by COB, a chip-shaped light-emitting element, wiring that electrically connects the light-emitting element to the wiring pattern, and a sealing part that covers the chip-shaped light-emitting element and the wiring can be provided on the substrate 4a.

At least one light-emitting element 4b can be provided. However, if multiple light-emitting elements 4b are provided, ultraviolet light can be irradiated over a wide area of the photocatalytic filter 5. The multiple light-emitting elements 4b can be connected in series. There are no particular limitations on the arrangement of the multiple light-emitting elements 4b, but it is preferable to provide them approximately evenly on the surface of the substrate 4a. If multiple light-emitting elements 4b are provided approximately evenly on the surface of the substrate 4a, it becomes easier to irradiate the surface of the photocatalytic filter 5 (sheet 5a) with ultraviolet light evenly.

Here, the reaction speed of the photocatalyst 5b provided in the photocatalyst filter 5 varies depending on the absorption wavelength region of the photocatalyst 5b and the intensity (amount of light) of the ultraviolet light. Therefore, the arrangement and number of the multiple light-emitting elements 4b can be determined based on the amount of ultraviolet light emitted by one light-emitting element 4b, the surface area of the photocatalyst filter 5 (sheet 5a), and the distance between the light-emitting surface of the light-emitting element 4b and the photocatalyst filter 5 (sheet 5a).

The light-emitting element 4b irradiates ultraviolet light having a predetermined wavelength (corresponding to an example of the first ultraviolet light) toward the photocatalytic filter 5. In this case, if the material or composition of the photocatalyst 5b changes, the absorption wavelength range of the photocatalyst 5b changes. Therefore, a light-emitting element 4b that irradiates ultraviolet light of an appropriate wavelength is selected according to the absorption wavelength range of the photocatalyst 5b.

For example, if the absorption wavelength range of the photocatalyst 5b is 365 nm or more and 405 nm or less, the light-emitting element 4b can be a light-emitting diode or a laser diode that irradiates ultraviolet light with a peak wavelength of 365 nm or more and 405 nm or less. For example, the light-emitting element 4b can be a light-emitting diode with a peak wavelength of 400 nm and an intensity (amount of light) of ultraviolet light of 700 mW.

The light-emitting element 4c can be provided on the surface of the substrate 4a on which the light-emitting element 4b is provided. As with the light-emitting element 4b described above, the light-emitting element 4c can be any of a surface-mount type light-emitting element such as a PLCC type, a light-emitting element having leads such as a bullet type, and a chip-shaped light-emitting element mounted by COB.

At least one light-emitting element 4c can be provided. However, if multiple light-emitting elements 4c are provided, ultraviolet light can be irradiated onto a wide area of the photocatalytic filter 5. In addition, the intensity (amount of light) of the ultraviolet light that passes through the photocatalytic filter 5 and reaches the filter 6 can be increased, and ultraviolet light can be made to enter a wide area of the filter 6.

The light-emitting element 4c is electrically connected to, for example, a wiring pattern provided on the surface of the substrate 4a. In this case, for example, the light-emitting element 4c and the light-emitting element 4b can be connected in series, or the light-emitting element 4c and the light-emitting element 4b can be connected in parallel. Also, for example, multiple light-emitting elements 4c and multiple light-emitting elements 4b can be connected in series, or multiple light-emitting elements 4c and multiple light-emitting elements 4b can be connected in parallel.

Although there is no particular limitation on the arrangement of the multiple light-emitting elements 4c, it is preferable to arrange them approximately evenly on the surface of the substrate 4a. If the multiple light-emitting elements 4c are arranged approximately evenly on the surface of the substrate 4a, it becomes easier to irradiate the surface of the filter 6 with ultraviolet light evenly. For example, the light-emitting elements 4c and the light-emitting elements 4b can be arranged alternately, or a row of multiple light-emitting elements 4c and a row of multiple light-emitting elements 4b can be arranged in the width direction of the surface of the substrate 4a. In the case of the light source 4 illustrated in FIG. 1, one light-emitting element 4c is arranged approximately in the center of the substrate 4a, and two light-emitting elements 4b are arranged on either side of the light-emitting element 4c.

The number of light-emitting elements 4c can be the same as the number of light-emitting elements 4b, or can be different.

When the gas G flows inside the frame 2, bacteria and viruses contained in the gas G may adhere to the surface of the photocatalytic filter 5 (sheet 5a). Since ultraviolet light has a sterilizing effect, if the light-emitting element 4b irradiates ultraviolet light with a peak wavelength of, for example, 365 nm or more and 405 nm or less, bacteria and viruses can be sterilized or inactivated to a certain extent.

However, in recent years, in addition to purifying the gas G in a closed space, there is a demand for effective sterilization and inactivation of bacteria, viruses, etc. In this case, the shorter the peak wavelength of the ultraviolet light, the stronger the sterilizing effect.
Therefore, the light-emitting element 4c is configured to irradiate the photocatalytic filter 5 with ultraviolet light (corresponding to an example of the second ultraviolet light) having a shorter peak wavelength than the ultraviolet light irradiated from the light-emitting element 4b. In this case, if only the light-emitting element 4c is provided in the light source 4, it is possible to purify the gas G and effectively sterilize and inactivate bacteria and viruses. However, the light-emitting element 4c that irradiates ultraviolet light with a short peak wavelength is more expensive than the light-emitting element 4b. Therefore, if only the light-emitting element 4c is provided in the light source 4, the manufacturing cost of the sterilization and purification device 1 will be high. The number of light-emitting elements 4c can be appropriately determined in consideration of the effect of sterilization and inactivation of bacteria and viruses and the manufacturing cost.

For example, the light-emitting element 4c can be a light-emitting diode or a laser diode that emits ultraviolet light with a peak wavelength of 265 nm or more and 280 nm or less. For example, the light-emitting element 4c can be a light-emitting diode with a peak wavelength of 280 nm and an intensity (amount of light) of ultraviolet light of 40 mW.

If light-emitting element 4c is provided, ultraviolet light having a stronger bactericidal effect than the ultraviolet light emitted from light-emitting element 4b can be irradiated onto the surface of photocatalytic filter 5 (sheet 5a), thereby enabling effective sterilization and inactivation of bacteria, viruses, etc. attached to photocatalytic filter 5 (sheet 5a). It also enables effective sterilization and inactivation of bacteria, viruses, etc. contained in gas G flowing inside frame 2.

For example, when only light-emitting element 4b was provided, the removal rate of airborne bacteria 30 minutes after the start of power supply was about 45%, but when light-emitting elements 4b and 4c were provided, the removal rate of airborne bacteria 30 minutes after the start of power supply was 99% or more. Furthermore, when light-emitting elements 4b and 4c were provided, the time required for the removal rate of airborne bacteria to reach 99% could be shortened to about 1/5 compared to when only light-emitting element 4b was provided.

The photocatalytic filter 5 includes, for example, a sheet 5a and a plurality of photocatalysts 5b.
The sheet 5a may be, for example, a woven fabric including a plurality of linear bodies.
Generally, a sheet carrying a photocatalyst is formed using a plurality of glass fibers. Since a sheet formed from a plurality of glass fibers has low rigidity, a frame-shaped member for holding the periphery of the sheet is required.

In addition, in recent years, there has been a demand for improved processing capacity, and the flow rate and flow speed of the gas G that permeates the sheet tend to increase. For this reason, bars or the like may be provided on the frame-shaped member to suppress deformation in the central region of the sheet. If a frame-shaped member or bars or the like is provided, there will be areas where the ultraviolet light irradiated from the light-emitting elements 4b and 4c cannot enter, or areas where the gas G cannot flow, making it impossible to improve processing capacity.

Therefore, the sheet 5a according to the present embodiment is formed of a plurality of linear bodies including a metal, such as stainless steel, nickel, Monel, phosphor bronze, titanium, copper, a copper alloy, silver, or a silver alloy.
The wire diameter (thickness) of the linear body can be, for example, not less than 0.016 mm and not more than 2.0 mm.

By forming the sheet 5a using such linear bodies, the rigidity of the sheet 5a can be increased, and the flow rate and flow velocity of the gas G passing through the sheet 5a can be increased. In addition, there is no need to provide frame-shaped members or bars for reinforcement. This allows the processing capacity of the sterilization and purification device 1 to be improved.

Here, if the linear body contains metal, the infectivity of bacteria, viruses, etc. attached to the surface of the linear body will be maintained for a certain period of time. However, as described above, the ultraviolet light emitted from the light-emitting element 4c has a high bactericidal effect, so that the bacteria and viruses attached to the surface of the linear body can be easily disinfected or inactivated.
Furthermore, if the material of the linear body is a metal that generates copper ions, such as copper or a copper alloy, the copper ions can be used to disinfect or inactivate bacteria or viruses attached to the surface of the linear body. If the material of the linear body is a metal that generates silver ions, such as silver or a silver alloy, the silver ions can be used to disinfect or inactivate bacteria or viruses attached to the surface of the linear body.

When a plurality of linear bodies are woven, gaps are generated in the regions defined by the linear bodies. That is, a plurality of gaps penetrating the sheet 5a in the thickness direction are provided. If a plurality of gaps penetrating the sheet 5a in the thickness direction are provided, the plurality of gaps become flow paths for the gas G.
There is no particular limitation on the weaving method of the multiple linear bodies, and the weaving method of the multiple linear bodies can be, for example, plain weave, twill weave, plain tatami weave, twill tatami weave, etc.

Here, if the number of gaps per inch (25.4 mm), i.e., the number of meshes, increases, the gaps will have a smaller cross-sectional area. If the cross-sectional area of the gap decreases, the pressure loss of the gas G passing through the gap increases. In this case, if the pressure loss exceeds 50 Pa, the flow rate of the gas G passing through the sheet 5a will decrease, and there is a risk that the desired processing capacity will not be obtained. According to the knowledge gained by the inventors, if the number of meshes is set to 500 or less, the pressure loss can be reduced to 50 Pa or less.

The multiple photocatalysts 5b are supported on the sheet 5a. The multiple photocatalysts 5b are, for example, granular bodies. The ultraviolet light irradiated from the light-emitting element 4b is incident on the photocatalysts 5b. Therefore, the photocatalysts 5b can be ultraviolet light-responsive photocatalysts. The ultraviolet light-responsive photocatalysts contain, for example, titanium oxide.

At least one photocatalytic filter 5 can be provided. When multiple photocatalytic filters 5 are provided, the multiple photocatalytic filters 5 can be arranged side by side in the flow direction of the gas G. For example, the multiple photocatalytic filters 5 can be arranged side by side between side 2c and side 2d of the frame 2.

In this case, increasing the number of photocatalytic filters 5 makes it easier to purify the gas G and to sterilize and inactivate bacteria and viruses using active oxygen species. However, increasing the number of photocatalytic filters 5 increases pressure loss. Therefore, the number of photocatalytic filters 5 can be changed as appropriate depending on the flow rate of the gas G, the required purification capacity (e.g., the amount of substances contained in the gas G), the number of meshes of the sheet 5a, etc.

The photocatalytic filter 5 can be formed, for example, as follows.
First, a plurality of linear bodies are woven together to form a sheet 5a.
Next, an emulsion solution is produced.
For example, phosphoric acid or the like is added to pure water to produce an aqueous solution whose pH (hydrogen ion concentration) is adjusted to 2-7.
Next, a plurality of photocatalysts 5b are added to the aqueous solution. For example, the average particle size of the photocatalysts 5b may be about 200 nm.
In this manner, an emulsion solution can be produced.

Next, the sheet 5a is immersed in the emulsion solution for about 10 minutes.
Next, the sheet 5a is pulled out of the emulsion solution and dried. The drying can be performed by heating. For example, the heating temperature can be about 100° C. and the heating time can be about 2 hours.
In this manner, the photocatalytic filter 5 can be formed.

The filter 6 faces the photocatalytic filter 5 and is provided on the side of the photocatalytic filter 5 opposite the light source 4. The filter 6 is, for example, sheet-like and includes a plurality of linear bodies. The filter 6 can be, for example, a woven fabric including a plurality of linear bodies, or can be a stack of a plurality of linear bodies. There are no particular limitations on the material of the linear bodies as long as it is resistant to ultraviolet light. The material of the linear bodies can be, for example, glass fiber or metal.

In this case, if the filter 6 is formed from a linear body containing metal, the rigidity of the filter 6 can be increased. Therefore, the flow rate and flow speed of the gas G passing through the filter 6 can be increased. In addition, there is no need to provide a frame-shaped member or a crosspiece for reinforcement. The linear body containing metal can be, for example, the same as the linear body used in the sheet 5a. The dimensions of the filter 6 can be, for example, the same as the dimensions of the photocatalytic filter 5 (sheet 5a). For example, the width dimension of the filter 6 can be W2.

When the filter 6 is a woven fabric containing multiple linear bodies, there is no particular limit to the way in which the multiple linear bodies are woven. The way in which the multiple linear bodies are woven can be, for example, plain weave, twill weave, plain tatami weave, twill tatami weave, etc. In this case, if the number of meshes is increased, the size of the foreign matter that can be captured can be reduced, but the pressure loss of the gas G passing through the filter 6 increases. Therefore, if the number of meshes is made too large, the flow rate of the gas G passing through the filter 6 will be reduced, and there is a risk that the desired processing capacity will not be obtained. For example, the number of meshes of the filter 6 can be about 100.

Next, the effects of the sterilization and purification device 1 according to this embodiment will be described.
For example, when the sterilization and purification device 1 is operated for a long time, maintenance such as replacement and cleaning of elements may be required. For example, when the light-emitting elements 4b and 4c break down or the function of the light-emitting elements 4b and 4c deteriorates over time, replacement and cleaning of the light source 4 is required. For example, when the photocatalyst 5b becomes dirty or the function of the photocatalyst 5b deteriorates over time, replacement and cleaning of the photocatalyst filter 5 is required. For example, when the filter 6 is damaged or dirty, replacement and cleaning of the filter 6 is required.

In such a case, the worker will remove the light source 4, photocatalytic filter 5, and filter 6 from the frame 2. In this case, the ultraviolet light irradiated from the light emitting element 4c is directly incident on the light source 4 and photocatalytic filter 5, so bacteria and viruses adhering to the light source 4 and photocatalytic filter 5 are sterilized and inactivated. Therefore, even if the worker touches the light source 4 or photocatalytic filter 5, there is a low risk of the worker becoming infected with bacteria or viruses.

On the other hand, even if the filter 6 is irradiated with ultraviolet light, the photocatalytic action does not occur. Therefore, in general, in order to increase the efficiency of use of the ultraviolet light irradiated from the light-emitting element, the photocatalytic filter is configured so that the amount of ultraviolet light passing through the photocatalytic filter is reduced. As a result, in general, the ultraviolet light irradiated from the light-emitting element hardly reaches the filter 6 provided upstream of the photocatalytic filter. In other words, in general, the ultraviolet light irradiated from the light-emitting element does not sterilize or inactivate bacteria or viruses attached to the filter 6. If bacteria or viruses are not sterilized or inactivated, the infectiousness of the bacteria or viruses will be maintained for a certain period of time, so if a worker touches the filter 6, the worker may become infected with bacteria or viruses.

In this case, it is possible to further provide a light source for irradiating the filter 6 with ultraviolet light, but this would result in an increase in size of the sterilization and purification device 1, higher costs, and an increase in the installation space.
In the sterilization and purification device 1 according to the present embodiment, a part of the ultraviolet light irradiated from the light-emitting element 4c to the photocatalytic filter 5 is transmitted through the photocatalytic filter 5 and irradiated to the filter 6. If a part of the ultraviolet light irradiated from the light-emitting element 4c is irradiated to the filter 6, bacteria and viruses attached to the filter 6 can be sterilized and inactivated. Therefore, even if an operator touches the filter 6, the operator can be prevented from being infected with bacteria or viruses. In addition, since there is no need to further provide a light source for irradiating the filter 6 with ultraviolet light, the sterilization and purification device 1 can be made smaller, less expensive, and requires less installation space. That is, the sterilization and purification device 1 according to the present embodiment can sterilize and inactivate bacteria and viruses attached to the filter 6 with a simple configuration.

In addition, a portion of the ultraviolet light irradiated from the light-emitting element 4b also passes through the photocatalytic filter 5 and is irradiated to the filter 6. Therefore, the ultraviolet light irradiated from the light-emitting element 4b can also sterilize and inactivate bacteria and viruses attached to the filter 6. However, as described above, the peak wavelength of the ultraviolet light irradiated from the light-emitting element 4c is shorter than the peak wavelength of the ultraviolet light irradiated from the light-emitting element 4b, so the bactericidal effect of the ultraviolet light irradiated from the light-emitting element 4c is greater than that of the ultraviolet light irradiated from the light-emitting element 4b. Therefore, the effect of sterilization and inactivation of bacteria and viruses attached to the filter 6 can be evaluated by the illuminance of the ultraviolet light irradiated from the light-emitting element 4c.

Here, a portion of the ultraviolet light irradiated from the light-emitting element 4b also passes through the photocatalytic filter 5, so if the amount of ultraviolet light passing through the photocatalytic filter 5 is too large, the photocatalytic action of the photocatalytic filter 5 may be insufficient. If the amount of ultraviolet light passing through the photocatalytic filter 5 is too small, the sterilization and inactivation of bacteria and viruses attached to the filter 6 may be insufficient.

According to the knowledge obtained by the present inventors, when the illuminance of the ultraviolet light irradiated from the light-emitting element 4c to the photocatalytic filter 5 is L1 (mW/cm ² ), and the illuminance of the ultraviolet light irradiated from the light-emitting element 4c to the filter 6 via the photocatalytic filter 5 is L2 (mW/cm ² ), it is preferable to make the relationship "0.2≦L2/L1≦0.3". In this way, it is possible to suppress the deterioration of the photocatalytic action of the photocatalytic filter 5, and it is possible to effectively sterilize and inactivate bacteria and viruses attached to the filter 6.

In this case, L2/L1 can be adjusted by the number of meshes of the sheet 5a provided on the photocatalytic filter 5. For example, if the number of meshes is set to 300, the above-mentioned illuminance L1 can be set to 42.4 (mW/cm ² ), and the above-mentioned illuminance L2 can be set to 10.8 (mW/cm ² ). In this case, L2/L1 is 0.25. The above-mentioned illuminance L1 and the above-mentioned illuminance L2 can be measured using an ultraviolet integrating light meter (for example, UIT-250 (Ushio Electric)).
According to the knowledge obtained by the present inventors, it is preferable that the mesh number of the sheet 5a is 50 or more and 400 or less.

As described above, the light source 4, photocatalytic filter 5, and filter 6 inserted into the pair of grooves 2e1, 2f1 are approximately parallel to each other. This makes it easier for the ultraviolet light irradiated from the light source 4 to pass through the photocatalytic filter 5, and allows the ultraviolet light that has passed through the photocatalytic filter 5 to be efficiently incident on the filter 6. As a result, it becomes even easier to disinfect and inactivate bacteria and viruses attached to the filter 6.

Next, the effect of the arrangement of the light source 4 and the photocatalytic filter 5 in the flow direction of the gas G will be described.
FIG. 3 is a schematic cross-sectional view illustrating a sterilization and purification device 100 according to a comparative example.
3, the sterilization and purification device 100 has a frame 2, a lid 3, a light source 4, a photocatalytic filter 5, and a filter 6. In addition, like the sterilization and purification device 1 described above, a fan 7 may be further provided.

As shown in FIG. 3, the arrangement of the light source 4 and the photocatalytic filter 5 is different between the sterilization and purification device 1 and the sterilization and purification device 100. That is, in the case of the sterilization and purification device 1, as shown in FIG. 2, the filter 6, the photocatalytic filter 5, and the light source 4 are arranged in order from the upstream side of the flow of the gas G. In contrast, in the case of the sterilization and purification device 100, as shown in FIG. 3, the filter 6, the light source 4, and the photocatalytic filter 5 are arranged in order from the upstream side of the flow of the gas G.

Here, silicone resin is used as a sealant for the light-emitting elements 4b and 4c. Although silicone resin has high resistance to ultraviolet light, a part of the silicone resin may decompose when the light-emitting elements 4b and 4c are irradiated with ultraviolet light. In this case, the shorter the peak wavelength of the irradiated ultraviolet light, the easier it is for the silicone resin to decompose. Therefore, the silicone resin used for the light-emitting element 4c is even more likely to decompose.
Furthermore, when the light emitting elements 4b and 4c irradiate the ultraviolet light, heat is generated. If the silicone resin is heated by the generated heat, the silicone resin becomes more likely to decompose.

When the silicone resin is decomposed, gas containing silicone resin components is released from the light-emitting elements 4b and 4c. The gas released from the light-emitting elements 4b and 4c is carried by the flow of gas G flowing inside the frame 2 and is discharged to the outside of the frame 2.

In this case, as shown in FIG. 3, if the light source 4 (light-emitting elements 4b, 4c) is provided upstream of the flow of gas G flowing inside the frame 2 and the photocatalytic filter 5 is provided downstream of the light source 4, the silicone resin component contained in the gas G is likely to adhere to the photocatalyst 5b of the photocatalytic filter 5. If the silicone resin component adheres to the photocatalyst 5b, it becomes difficult for ultraviolet light to enter the photocatalyst 5b, or for the gas G to come into contact with the photocatalyst 5b. As a result, the functions of the sterilization and purification device 100 (gas purification, sterilization and inactivation of bacteria and viruses, etc.) decrease over time. For example, the deodorizing performance maintenance rate after 1600 hours from the start of operation may be about 19%.

In contrast, in the sterilization and purification device 1 according to this embodiment, as shown in FIG. 2, a photocatalytic filter 5 is provided upstream of the flow of gas G flowing inside the frame 2, and a light source 4 (light-emitting elements 4b, 4c) is provided downstream of the photocatalytic filter 5. Therefore, even if gas containing silicone resin components is released from the light-emitting elements 4b and 4c, the flow of gas G prevents the released gas from reaching the photocatalytic filter 5. As a result, it is possible to suppress the deterioration over time of the functions of the sterilization and purification device 1 (gas purification, sterilization and inactivation of bacteria and viruses, etc.). For example, the deodorizing performance maintenance rate after 1600 hours from the start of operation was about 84%.

Although several embodiments of the present invention have been illustrated above, 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, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their variations are included within the scope and gist of the invention, as well as within the scope of the invention and its equivalents described in the claims. Furthermore, the above-mentioned embodiments can be implemented in combination with each other.

1 sterilization and purification device, 2 frame, 4 light source, 4a substrate, 4b light emitting element, 4c light emitting element, 5 photocatalytic filter, 5a sheet, 5b photocatalytic element, 6 filter, 7 fan, G gas

Claims (6)

A photocatalytic filter having a sheet and a photocatalyst supported on the sheet;
a light source facing the photocatalytic filter and having a first light-emitting element and a second light-emitting element;
a filter disposed opposite the photocatalytic filter and on the opposite side of the photocatalytic filter from the light source;
Equipped with
The first light emitting element irradiates a first light toward the photocatalytic filter,
The second light emitting element irradiates the second light, which is ultraviolet light having a shorter peak wavelength than the first light, toward the photocatalytic filter;
A part of the second light irradiated to the photocatalytic filter is transmitted through the photocatalytic filter and irradiated to the filter ,
When the light source irradiates light, gas is released from the light source,
A sterilization and purification device in which the gas to be treated flows from the filter side toward the light source side, and the flow of the gas to be treated prevents the released gas from reaching the photocatalyst filter . The sterilization and purification device according to claim 1, which satisfies the following formula when the illuminance of the second light irradiated to the photocatalytic filter is L1 (mW/ ^cm2 ) and the illuminance of the second light irradiated to the filter is L2 (mW/ ^cm2 ).
0.2≦L2/L1≦0.3 The sheet is a woven fabric including a plurality of linear bodies,
the plurality of linear bodies includes a metal,
3. The sterilization and purification device according to claim 1, wherein the sheet has a mesh number of 50 or more and 400 or less. The sterilization and purification device according to any one of claims 1 to 3, wherein the peak wavelength of the second light is 265 nm or more and 280 nm or less. The sterilization and purification device according to any one of claims 1 to 4, wherein the peak wavelength of the first light is 365 nm or more and 405 nm or less. The sterilization and purification device according to any one of claims 1 to 5 , further comprising a fan that forms a flow of the gas from the filter side toward the light source side.

Images