JP7486098B2 - Plasma sterilization equipment - Google Patents

Description

The present invention relates to a plasma sterilization device that uses plasma to sterilize objects, and in particular to a plasma sterilization device that can reliably sterilize small objects such as granules or powders, objects with complex shapes such as flat, confetti, and spindle shapes, as well as objects of various sizes, in addition to simple spherical shapes.

Plasma sterilization, which uses plasma to sterilize objects, has a wide range of uses and its fields of application are constantly expanding. One promising field of application is the sterilization of agricultural products.

Agricultural produce is often transported long distances, during which microbial proliferation becomes an issue. This is because various bacteria, fungi, etc. that originate from the soil and growing environment are attached to the produce, and these have a major impact on the deterioration of the produce.

Seeds are one such agricultural product. Seeds come in a variety of shapes, including not only simple spherical shapes, but also flat seeds like those of carrots and tomatoes, as well as many other complex shapes. If bacteria, fungi, viruses, and the like are attached to the surface of such seeds when they are sown, they will multiply after sowing and adversely affect the growth of the plants, causing them to stagnate and wither. In addition to seeds, granular or powdered agricultural products such as grains used as food ingredients can also have contaminating microorganisms attached to them that become mixed into the product during food processing, causing the product to deteriorate.

To date, the main techniques used to deal with these problems are hot water sterilization, dry heat sterilization, and chemical sterilization, all of which are aimed at sterilizing microorganisms that are attached to seeds.

For example, in hot water sterilization, seeds are immersed in hot water at about 50-60°C for several tens of minutes to disinfect them. In dry heat sterilization, seeds are placed in a dry air atmosphere at about 70-80°C for several days to disinfect them. In chemical sterilization, a chemical that is compatible with fungi present on the surface of the object is added and sprayed to sterilize the object.

However, in the above-mentioned hot water sterilization method, the seeds are soaked in hot water for several tens of minutes, which may cause the seeds to deteriorate and reduce their germination rate due to high temperature and moisture.

In addition, in the above-mentioned dry heat sterilization, the seeds are exposed to a high-temperature, dry air atmosphere for several days. As with hot water sterilization, exposure to a high-temperature environment for a long period of time can cause the seeds to deteriorate, leading to a risk of a decrease in germination rate.

Although sterilization using the above-mentioned chemicals avoids deterioration due to high temperatures, it is necessary to select chemicals that are suitable for the fungi to be sterilized. In addition, if the same chemical is used for a long period of time, chemical-resistant bacteria may develop, and if these bacteria contaminate the seeds, the chemicals may no longer be effective in disinfecting the seeds.

For granular and powdered agricultural products other than seeds, heat sterilization and steam sterilization are mainly used, just as for seeds. However, sterilization has the disadvantage that deterioration of the color, taste, texture, etc. of the agricultural products due to temperature and moisture is unavoidable. Furthermore, since many agricultural products do not like moisture, the sterilization techniques that can be used are limited. Furthermore, when such agricultural products are sterilized using chemicals, in addition to the deterioration of the color, taste, texture, etc. due to the chemicals, there is also the problem of chemical residues in the agricultural products. Furthermore, the types of chemicals that can be used are limited to those approved as food additives.

In this situation, there is a demand for a sterilization method that uses plasma and can be both safe and effective for granular and powdered agricultural products, without directly wetting the target object with water or using chemicals.

Conventional plasma sterilization devices capable of sterilizing such granular and powdered agricultural products include, for example, a device that sterilizes or modifies low-moisture powder or granular material circulating inside a cyclone at low temperatures using atmospheric plasma (i.e., the raw material gas for this purpose generally can be air in the atmosphere as is, and generally also includes oxygen gas, argon gas, nitrogen gas, etc. (see paragraph [0032] of the specification of Patent Document 3 described below)) (see Patent Document 1).
Furthermore, although the purpose is different from sterilizing agricultural products, there is a particle processing method for modifying the surface of particles (fine powder). For example, there is a particle processing method including the steps of supplying gas to a plasma processing device, supplying particles to a supply path of the gas to the plasma processing device and supplying the particles into the plasma processing device along with the gas flow, and generating plasma between a pair of electrodes arranged opposite an outlet of the supply path inside the plasma processing device so as to surround the outlet (see Patent Document 2).

There is also a plasma sterilization device that includes opposing electrodes consisting of an upper electrode and a lower electrode that face each other with a gap in the vertical direction, a supply means that supplies the object from the center of the upper or lower electrode toward the gap, and a discharge means that discharges the object from the center of the lower electrode along the outer periphery to the outside (see Patent Document 3).

JP 2014-68 A JP 2006-68589 A International Publication WO2016/190436

However, in conventional plasma sterilization devices, for example in Patent Document 1, the target powder or granular material is irradiated with plasma while it randomly rotates inside the cyclone. This means that, probabilistically, some targets are actually irradiated with plasma and some are not, resulting in bias in the degree of plasma irradiation and making it impossible to stably sterilize all targets uniformly and sufficiently.

For example, in Patent Document 2, although the purpose is different from sterilizing agricultural products, plasma is generated between a pair of electrodes arranged opposite the outlet of the plasma treatment device in the supply path, surrounding the outlet, to modify the surface of the fine particles (fine powder). In other words, plasma is generated locally only at both ends of the outlet between the pair of electrodes to modify the surface of the fine particles (fine powder). Therefore, even if agricultural products are used as the fine particles, some agricultural products will be sterilized and some will not be sterilized due to this localized plasma, resulting in uneven sterilization of the agricultural products, resulting in uneven and insufficient sterilization.

For example, Patent Document 3 aims to sterilize small agricultural products such as seeds, but there is a problem that, particularly with flat seeds, the movement of the seeds becomes irregular, so some agricultural products are sterilized by the plasma and some are not, resulting in uneven sterilization of the agricultural products, and resulting in uneven and insufficient sterilization.

Among the agricultural products that can be sterilized, seeds in particular come in a wide variety of sizes and shapes, including not only simple spherical shapes but also complex shapes such as flat, confetti, and spindle shapes. However, there is currently no known technology that can uniformly sterilize all of these seeds, particularly those with complex shapes such as flat, confetti, and spindle shapes, and seeds of various sizes.

The present invention has been made to solve the above problems, and aims to provide a plasma sterilization device that can perform plasma sterilization continuously and stably under mild conditions without degrading the quality of small objects such as granular or powdered agricultural products, and objects of various sizes and complex shapes such as flat, confetti, and spindle shapes, as well as simple spherical shapes.

The plasma sterilization device disclosed in this application is a plasma sterilization device that sterilizes objects using plasma generated by applying a voltage between electrodes in a raw material gas atmosphere, and is equipped with: opposing electrodes consisting of plate-shaped upper and lower electrodes facing each other across a gap in the vertical direction; a storage section whose bottom surface is formed of a plate-shaped insulating material or the lower electrode and which is provided with a partition body around its outer periphery; a storage means that is disposed between the opposing electrodes and is supported by a shaft while the object is stored in the storage section; a supply means that supplies the object toward the gap; and a control means that controls the retention and discharge of the object in the storage means by changing the shaft center that supports the storage means.

In this way, the plasma sterilization device disclosed in the present application comprises a counter electrode consisting of a plate-shaped upper electrode and a plate-shaped lower electrode facing each other with a gap in the vertical direction, a storage section whose bottom surface is formed of a plate-shaped insulating material or the lower electrode and which is provided with a partition around its outer periphery, the storage section being disposed between the counter electrodes and which is supported by a shaft while the object is stored in the storage section, a supply means for supplying the object toward the gap, and a control means for changing the shaft center supporting the storage means to control the retention and discharge of the object in the storage means. Therefore, the control means maintains a certain retention time of the object in the storage means, and promotes discharge to the outside after the object has been sufficiently sterilized by plasma sterilization. Therefore, even if the object is fine, such as a powder, and even if the object has a simple spherical shape, but also complex shapes such as flat, confetti, and spindle shapes, and objects of various sizes, plasma sterilization can be performed continuously and stably under relaxed conditions without deterioration of quality.

In the plasma sterilization device disclosed in the present application, if necessary, the storage means is provided with guide fins arranged radially as the partition body, and the storage means oscillates relative to the opposing electrode, and the control means changes the axis to control the direction of the oscillation. In this way, the storage means is provided with guide fins arranged radially as the partition, and the storage means oscillates relative to the counter electrode, and the control means changes the axis to control the direction of the oscillation. By controlling the direction of the oscillation by the control means, in one direction of oscillation, the guide fins function as a barrier, causing the object to remain without being discharged from the storage means, and in the other direction of oscillation, the guide fins function as an opening, causing the object to be discharged from the storage means. This simple configuration allows continuous and stable plasma sterilization of all objects under relaxed conditions without deterioration of quality, even if the object is fine, such as a powder, and even if the object has not only a simple spherical shape but also a complex shape such as a flat or cubic shape.

In addition, in the plasma sterilization device disclosed in the present application, if necessary, the storage means includes a frame portion arranged at the outer end of the insulating material as the partition body, and an open-shaped exhaust outlet in a part of the frame portion, and the control means changes the axis to control the inclination angle of the storage means. In this way, the storage means includes a frame portion disposed at the outer end of the insulating material as the partition, and an open discharge port in part of the frame portion. The control means changes the axis to control the tilt angle of the storage means. When the control means changes the axis, for example, when the storage means is maintained without tilting horizontally, the object acts to remain in the frame portion, and when the control means changes the axis, for example, when the storage means is tilted from the horizontal direction, the object acts to be discharged from the discharge port. This simple configuration allows continuous and stable plasma sterilization of all objects under relaxed conditions without deteriorating their quality, even if the object is fine, such as a powder, and even if the object has a simple spherical shape, but also a complex shape such as a flat or cubic shape.

In addition, in the plasma sterilization device disclosed in this application, the supply means supplies the raw material gas together with the object as necessary. In this way, the concentration of the raw material gas supplied by the supply means is increased between the upper and lower electrodes where the object is present, so that all objects pass through the high-concentration plasma generation region, and even if the object is fine, such as a powder, and even if it has not only a simple spherical shape but also a complex shape such as a flat or cubic shape, it is possible to reliably sterilize all objects with a simple configuration.

The plasma sterilization device disclosed in this application is also provided with a discharge position control section formed by sealing a liquid dielectric between the opposing electrodes as necessary. In this way, the dielectric constant is reduced at the position where plasma is generated between the opposing electrodes due to the action of the liquid dielectric, and the discharge is controlled so that the next plasma generation position shifts sequentially to another adjacent position with a higher dielectric constant. This suppresses the generation of arc discharge, and a stable and gentle discharge is continuously generated between the opposing electrodes, making it possible to maintain plasma sterilization in a gentle discharge state that does not damage the target object.

1 shows a configuration diagram of a plasma sterilization device according to a first embodiment of the present invention. 1 shows a configuration diagram of a plasma sterilization device according to a first embodiment of the present invention. 1A to 1C are explanatory diagrams showing the rocking operation of the plasma sterilization device according to the first embodiment of the present invention. 1 shows a configuration diagram of a plasma sterilization device according to a first embodiment of the present invention. FIG. 1 shows a configuration diagram including a mesh electrode of a plasma sterilization device according to a first embodiment of the present invention. FIG. 1 shows a configuration diagram including a mesh electrode of a plasma sterilization device according to a first embodiment of the present invention. FIG. 11 shows a configuration diagram of a storage means of a plasma sterilization device according to a second embodiment of the present invention. 6A to 6C are explanatory diagrams of the oscillation operation of a plasma sterilization device according to a second embodiment of the present invention. 6A to 6C are explanatory diagrams of the oscillation operation of a plasma sterilization device according to a second embodiment of the present invention. FIG. 11 shows a configuration diagram of a stacked type plasma sterilization device according to a second embodiment of the present invention. FIG. 13 shows a configuration diagram of a plasma sterilization device according to a third embodiment of the present invention.

First Embodiment
Hereinafter, a plasma sterilization device according to a first embodiment will be described with reference to FIGS. 1 to 6. FIG.

As shown in FIG. 1, the plasma sterilization device according to this embodiment is a plasma sterilization device that sterilizes an object 100 by plasma generated by applying a voltage between electrodes in a raw material gas atmosphere, and is configured to include an opposing electrode 1 consisting of a plate-shaped upper electrode 11 and a lower electrode 12 that face each other across a gap A in the vertical direction, a storage section 23 having a bottom surface 21 formed of a plate-shaped insulating material or the lower electrode 12 and a partition body 22 on its outer periphery, the storage section 23 being disposed between the opposing electrodes 1, a storage means 2 that is axially supported while the object 100 is stored in the storage section 23, a supply means 3 that supplies the object 100 toward the gap A, and a control means 4 that changes the axis 41 that axially supports the storage means 2 to control the retention and discharge of the object 100 in the storage means 2. The device also includes an AC power source 200 as a means for applying an AC voltage to the opposing electrode 1, and a collection section 300 that accumulates and collects the object 100 discharged from the storage means 2 below the lower electrode 12.

The shapes of the upper electrode 11 and the lower electrode 12 that constitute this counter electrode 1 are not particularly limited as long as they are plate-like, and can be, for example, a disk shape or a polygonal shape. The material of this counter electrode 1 is not particularly limited as long as it is a commonly used metal electrode, and for example, an aluminum electrode can be used.

The AC power source 200 that supplies power to the opposing electrode 1 is not particularly limited as long as the applied voltage is AC, and a low-frequency power source or a high-frequency power source (RF) can be used. For example, an AC power source with a frequency band of several tens of Hz to several hundreds of MHz and a voltage of 1 to 10 kV can be used. In addition, a receptacle such as a plastic tray made of resin can be used as the recovery unit 300, allowing the target objects 100 such as seeds to be stored and recovered without being damaged.

The storage means 2 may be the same size as the counter electrode 1, or may be a different size. That is, the surface area may be smaller or larger than that of the counter electrode 1. The placement position of the storage means 2 is not particularly limited, but it may be placed on the lower electrode 12 as shown in FIG. 1(a). Alternatively, it may be placed between the upper electrode 11 and the lower electrode 12 without contacting either of them as shown in FIG. 1(b).

The bottom surface 21 of the storage section 23 constituting the storage means 2 can be formed from a plate-shaped insulating material. The shape of this plate-shaped insulating material is not particularly limited, but a mesh sheet can be used. By using this mesh sheet, plasma irradiation from the upper electrode 11 and the lower electrode 12 can be efficiently applied through the gaps arranged in the mesh fabric, even to objects 100 of various sizes and objects with complex shapes such as flat, confetti, and spindle shapes, which are particularly difficult to irradiate uniformly with plasma.

The bottom surface 21 of the storage section 23 constituting the storage means 2 can be formed from a plate-shaped insulating material as shown in FIG. 1, or it can be formed as the upper surface of the lower electrode 12 without using this plate-shaped insulating material as shown in FIG. 2(a), allowing for a simpler configuration depending on the application.

The supply means 3 supplies the object 100 toward the gap A. The supply method is not particularly limited, but the object 100 can be supplied toward the gap A by, for example, using various types of injectors or pressurization by a pump.

In addition, the supply means 3 can supply the object 100 from the gaps in the mesh of the upper electrode 11 toward the gap A by configuring the upper electrode 11 to have a mesh structure. Also, the supply means 3 can supply the object 100 from the gap in the center of the upper electrode 11 toward the gap A by configuring the upper electrode 11 to have a tapered shape with a recess in the center and providing a gap in the center.

The control means 4 changes the axis 41 that supports the storage means 2 to control the retention and discharge of the object 100 in the storage means 2. The manner in which the axis 41 is changed is not particularly limited, but for example, the storage means 2 can oscillate relative to the counter electrode 11 and the direction of the oscillation can be controlled by changing the axis 41.

For example, as shown in FIG. 2(b), the storage means 2 has guide fins 22a arranged radially as the partition body 22, and the storage means 2 swings relative to the counter electrode 11, while the control means 4 changes the axis 41 to control the forward and reverse directions of the swing.

The storage means 2 oscillating relative to the counter electrode 11 is not particularly limited, but includes the storage means 2 oscillating in a different movement or direction than the counter electrode 11, or oscillating in the same movement or direction as the counter electrode 11.

As shown in FIG. 3(a), the guide fins 22a are placed radially as the partition 22, and the material used for them is preferably a resin or the like that will not cause damage when the target object 100, i.e., the agricultural seed, collides with them.

The center B' of the storage means 2 (or the center of the circle if it is circular) is configured to be eccentric to the center B of the lower electrode 12 (or upper electrode 11) (or the center of the circle if it is circular).

The storage means 2 performs a rocking motion relative to the opposing electrode 1 by vibrating in two directions on a plane (xy direction, vertical and horizontal direction), and the control means 4 controls the phase of the vibration in these two directions. The vibration in these two directions may be a vibration motion that is not rotational, or may be a vibration motion that is rotational, and is not particularly limited as long as vibration occurs in two directions on the plane. For example, as shown in FIG. 3(a), the storage means 2 can rotate around the center B of the lower electrode 12 (upper electrode 11) as the center of rotation. In other words, the trajectory of the center B' of the storage means 2 is formed along a concentric circle centered on the center B of the lower electrode 12 (upper electrode 11).

In addition, when the storage means 2 rotates, the control means 4 can change the direction of rotation to either the forward or reverse direction using the axis 41, thereby controlling the direction of the oscillation.

For example, as shown in FIG. 3(b), the control means 4 controls the rotation of the storage means 2 in the forward direction R, so that the guide fins 22a are at an elevation angle relative to the direction of rotation, and the gaps in the guide fins 22a are not visible from inside the storage means 2. This shields the outer periphery of the storage means 2, inhibits the objects 100 from being discharged, and acts to propel the objects 100 into the storage means 2. The objects 100 are scraped together inside the storage means 2, and uniform sterilization can be achieved with sufficient plasma irradiation time.

Furthermore, as shown in FIG. 3(c), the control means 4 controls the storage means 2 to rotate in the reverse direction L, so that the guide fins 22a are at a depressed angle with respect to the direction of rotation, and the gaps in the guide fins 22a are visible from inside the storage means 2, opening up the outer periphery of the storage means 2 and promoting the discharge of the object 100, which acts to discharge the object 100 to the outside of the storage means 2. As described above, the object 100 can be discharged to the outside after being uniformly sterilized inside the storage means 2 for a sufficient plasma irradiation time.

In this way, the control means 4 controls the storage means 2 to rotate in the forward direction R through the above-mentioned series of control operations, thereby gathering the objects 100 around the center B between the upper electrode 11 and the lower electrode 12, and performing uniform, intensive sterilization for a sufficient plasma irradiation time, and then controls the storage means 2 to rotate in the reverse direction L, allowing the uniformly sterilized objects 100 to be discharged to the outside.

The control performed by the control means 4 is not limited to the control directions related to the forward direction R and reverse direction L described above, and the control direction can be freely designed according to the shape and size of the target object 100. For example, when the target object 100 is a spherical seed or when it is flat, it is possible to individually set whether to rotate first in the forward direction R or first in the reverse direction L according to the type of target object 100.

By controlling the control means 4, the guide fins 22a have the dual function of temporarily storing the object 100 in the storage means 2 and discharging it from the storage means 2 to the outside, making it possible to easily sterilize every corner of each object 100, regardless of its shape, including small objects 100 such as granules or powder, objects with complex shapes such as not only simple spherical shapes but also flat, confetti-like, and spindle-like shapes, and objects of various sizes.

By controlling the direction of the oscillation of the storage means 2 by the control means 4, in one direction of movement (forward direction R), the guide fins 22a function as a barrier, causing the object 100 to remain in the storage means 2 without being expelled, and during the retention period, the object 100 is sufficiently irradiated with plasma and uniformly sterilized, while in the other direction of movement (reverse direction L), the guide fins 22a function as an opening, causing the object 100 to be expelled from the storage means 2. With this simple configuration, plasma sterilization can be performed continuously and stably under relaxed conditions without deteriorating the quality of all objects 100, even if the object 100 is fine, such as a powder, and even if it is not only a simple spherical shape but also a complex shape such as a flat shape, a confetti shape, or a spindle shape, or a variety of sizes.

Furthermore, as shown in FIG. 4, it is possible to arrange the above-mentioned counter electrodes 1 in multiple stages and connect them to one axis 41 (a stacked type), arranging multiple counter electrodes 1 in series. With this stacked type configuration, the object 100 is sequentially supplied from the uppermost counter electrode 1 and moves continuously through each stage of the counter electrodes 1 and the storage means 2, ensuring a substantial sterilization processing time and enabling rapid and efficient sterilization.

Also, as shown in FIG. 5(a), an upper mesh electrode 11a facing the upper electrode 11 can be disposed between the upper electrode 11 and the lower electrode 12, and an upper AC power source 200a can be disposed to apply a voltage between the upper electrode 11 and the upper mesh electrode 11a.

Similarly, as shown in FIG. 5(a), a lower mesh electrode 12a facing the lower electrode 12 can be disposed between the upper electrode 11 and the lower electrode 12, and a lower AC power source 200b can be disposed to apply a voltage between the lower electrode 12 and the lower mesh electrode 12a.

There is no particular limitation as to whether the upper mesh electrode 11a and the lower mesh electrode 12a are grounded, but either or both of them may be grounded.

As shown in FIG. 5(a), the storage means 2 is disposed between the upper mesh electrode 11a and the lower mesh electrode 12a. In this configuration, it is preferable that the bottom surface 21 of the storage means 2 is a mesh sheet formed of the plate-shaped insulating material described above.

By applying a voltage to the upper AC power supply 200a, a discharge occurs between the upper electrode 11 and the upper mesh electrode 11a, generating plasma P. Also, by applying a voltage to the lower AC power supply 200b, a discharge occurs between the lower electrode 12 and the lower mesh electrode 12a, generating plasma P.

As shown in FIG. 5(b), the plasma P generated near the upper electrode 11 leaks through the gaps in the mesh of the upper mesh electrode 11a and flows toward the top of the bottom surface 21 of the storage means 2. Also, as shown in FIG. 5(b), the plasma P generated near the lower electrode 12 leaks through the gaps in the mesh of the lower mesh electrode 12a and flows toward the bottom surface of the storage means 2, and further, because the bottom surface 21 of the storage means 2 is made of a mesh sheet formed of a plate-shaped insulating material, the plasma P also leaks through the gaps in the mesh of the bottom surface 21 of the storage means 2 and rises.

In this way, the plasma P generated near each of the upper and lower electrodes 11 and 12 leaks out and passes through the gaps in the mesh of the upper mesh electrode 11a and the lower mesh electrode 12a, and flows from above and below toward the upper surface of the bottom surface 21 of the storage means 2. As a result, as shown in FIG. 5(c), the plasma P reliably irradiates the object 100 rolling into the inside of the storage means 2 from above and below, and the object 100 can be uniformly sterilized inside the storage means 2 for a sufficient plasma irradiation time before being discharged to the outside.

In particular, when the size of the object 100 is large, the gap A between the upper electrode 11 and the lower electrode 12 is set long to ensure space to accommodate the object 100, and the discharge distance between the upper electrode 11 and the lower electrode 12 is long. Even if this long distance results in a long discharge, the upper mesh electrode 11a and the lower mesh electrode 12a can stably generate plasma P near the upper electrode 11 and the lower electrode 12. Even if the gap A between the upper electrode 11 and the lower electrode 12 is long, the object can be uniformly sterilized for a sufficient plasma irradiation time inside the storage means 2 and then discharged to the outside.

Furthermore, it is also possible to apply a voltage between the upper mesh electrode 11a and the lower mesh electrode 12a described above.

For example, as shown in FIG. 6(a), a middle power source 200c can be provided to apply a voltage between the upper mesh electrode 11a and the lower mesh electrode 12a. The middle power source 200c is a power source that applies a voltage of DC, AC, or a voltage obtained by superimposing both. For convenience of explanation, FIG. 6 illustrates the middle power source 200c as an AC power source as an example. The voltage applied to the middle power source 200c is not particularly limited, but it is desirable to set it to a voltage lower than the voltages applied to the upper AC power source 200a and the lower AC power source 200b, so that no discharge occurs. This can further reduce damage to the object 100 during the sterilization process, and perform higher quality sterilization.

With this configuration, as shown in FIG. 6(a), applying a voltage to the upper AC power supply 200a causes a discharge between the upper electrode 11 and the upper mesh electrode 11a, generating plasma P. Also, applying a voltage to the lower AC power supply 200b causes a discharge between the lower electrode 12 and the lower mesh electrode 12a, generating plasma P.

Furthermore, as shown in FIG. 6(b), the plasma P generated near each of the upper and lower electrodes 11 and 12 is encouraged to leak through the gaps in the mesh of the upper mesh electrode 11a and the lower mesh electrode 12a by applying a voltage to the middle power source 200c, and flows in high density from above and below toward the top surface of the bottom surface 21 of the storage means 2.

As a result, as shown in FIG. 6(c), the object 100 that rolls into the inside of the storage means 2 is irradiated with plasma P from above and below at high density, and the object 100 is sterilized uniformly and at high density for a sufficient plasma irradiation time inside the storage means 2, and then it can be discharged to the outside.

The object 100 to be sterilized by the plasma sterilization device according to the first embodiment is not limited to a particular type, and can be not only a simple spherical shape, but also complex shapes such as flat, confetti, and spindle shapes, and objects of various sizes. Further examples of such complex shapes include a bell shape, a boat shape, an arm shape, a curved ball shape, a cylinder shape, an ellipse shape, a human heart shape, a convex lens shape, a line shape, a club shape, a crystal shape, a sphere shape, a low cone shape, a nipple shape, a small platelet shape, a small thorn shape, a straight prickle shape, a peeling shape, a wart shape/low hill shape, an ovoid shape, a kidney shape, a round kidney shape, a spiral shape, a square shape, a distorted sphere shape (a shape in which the diameter is almost the same everywhere but has irregularities), etc.

From the above configurations, the plasma sterilization device of the first embodiment uses the control means 4 to maintain a fixed residence time of the object 100 within the storage means 2, and promotes discharge to the outside after it has been sufficiently sterilized by plasma irradiation. This allows continuous and stable plasma sterilization under gentle conditions without deterioration of quality for all objects 100, even if the object is fine, such as a powder, and even if the object is not only simple spherical, but also has complex shapes such as flat, confetti, and spindle shapes, and is of various sizes.

In addition, in this plasma sterilization device, the supply means 3 can supply raw material gas along with the supply of the object 100. In this case, the concentration of raw material gas supplied by the supply means 3 is filled between the upper electrode 11 and the lower electrode 12 where the object 100 is present, so all objects 100 pass through the plasma generation area with a higher concentration more reliably, and even if the object 100 is fine, such as a powder, and even if it is not only a simple spherical shape but also a complex shape such as a flat shape, a confetti shape, or a spindle shape, or a variety of sizes, all objects 100 can be sterilized reliably with a simple configuration.

In other words, the concentration of the raw material gas supplied by this supply means 2 is locally increased between the center of each of the upper electrode 11 and the lower electrode 12, so that all objects 100 pass through the high-concentration plasma generation area, and all objects 100 can be reliably sterilized regardless of the shape of the objects 100, even if they are fine objects such as powder.

The supply means 3 can also supply cold air or fine ice along with the supply of the object 100. In this case, the thermal stress that the object 100 receives from the plasma discharge during sterilization can be minimized, making it possible to obtain an object 100 of even higher quality after sterilization.

Second Embodiment
A plasma sterilization device according to the second embodiment will be described below with reference to FIGS.

In the second embodiment, as in the first embodiment described above, the counter electrode 1, the storage means 2, the supply means 3, and the control means 4 are provided, and further, as shown in FIG. 7, the storage means 2 includes a frame portion 22b disposed at the outer end of the insulating material as the partition body 22, and an open-shaped discharge port 22c in a part of the frame portion 22b, and the control means 4 changes the axis 41 to control the inclination angle of the storage means 2.

There are no particular limitations on how the axis 41 can be changed, so long as it tilts the storage means 2. For example, the axis 41 can be simply tilted, or the axis 41 can be vibrated or expanded or contracted.

As shown in FIG. 7, the storage means 2 includes a frame portion 22b disposed at the outer end of the insulating material. The shape of the frame portion 22b is not particularly limited as long as it is disposed at the outer end of the storage means 2. For example, as shown in FIG. 7, when the bottom portion 21 of the storage means 2 is formed in a rectangle or square, the frame portion 22b is disposed on the outer edge of the rectangle or square at the outer end of the storage means 2. In addition, as shown in FIG. 8(a), when the bottom portion 21 of the storage means 2 is formed in a circle or ellipse, the frame portion 22b is disposed on the outer periphery of the circle or ellipse at the outer end of the storage means 2.

The location of the outlet 22c is not particularly limited as long as it is disposed in a part of the frame portion 22b. As shown in FIG. 8(a), the bottom 21 of the storage means 2 can be formed in a circular, rectangular or square shape, and the upper electrode 11 can be configured to have a mesh structure, and the supply means 3 can supply the object 100 between the electrodes of the upper electrode 11 and the lower electrode 12 through the gaps in the mesh of the upper electrode 11.

The control means 4 rocks the storage means 2, thereby performing plasma sterilization on the object 100 for a certain period of time. This rocking may be a vibration motion in the vertical and horizontal directions, or a rotational motion. After performing plasma sterilization for a certain period of time, the control means 4 controls the axis 41 to tilt as shown in FIG. 8(b), and discharges the object 100 to the outside through the discharge port 22c.

In this way, the storage means 2 is provided with a frame body portion 22c disposed at the outer end of the insulating material as the partition body 22, and an open-shaped discharge port 22c in part of the frame body portion 22c, and the control means changes the axis to control the tilt angle of the storage means 2. Therefore, when the control means changes the axis, for example, when the storage means 2 is maintained without tilting horizontally, the object 100 acts to remain in the frame body portion 22c, and when the control means changes the axis, for example, when the storage means 2 is tilted from the horizontal direction, the object 100 acts to be discharged from the discharge port 22c. Even if the object 100 is fine, such as a powder, and even if it is not only a simple spherical shape but also a complex shape such as a flat shape, a confetti shape, or a spindle shape, or a variety of sizes, plasma sterilization can be performed continuously and stably under relaxed conditions without deteriorating the quality of all the objects 100 with a simple configuration.

In the above configuration, the supply means 3 supplies the object 100 between the upper electrode 11 and the lower electrode 12 through the gaps in the mesh of the upper electrode 11, but this is not limited to this. For example, as shown in FIG. 9, the supply means 3 can supply the object 100 directly between the electrodes, without passing through the gaps in the mesh of the upper electrode 11, as in the first embodiment.

As shown in FIG. 9(b), the control means 4 controls the tilt direction (forward direction R and reverse direction L) so that plasma sterilization is concentrated in the horizontal position fixed by the reverse direction L, and the sterilized object 100 is discharged in the position tilted by the forward direction R.

As shown in FIG. 10, it is also possible to arrange the above-mentioned counter electrodes 1 in multiple stages, and to connect multiple electrodes to one axis 41 (a stacked type), so that multiple counter electrodes 1 are arranged in series. As shown in FIG. 10, it is also possible to house the entire plasma sterilization device according to this embodiment in a cylindrical container, and the supply means 3 can be disposed on the outer periphery of each stage.

In this way, the plasma sterilization device of this embodiment has a multi-stage stacked configuration, so that the object 100 is sequentially supplied from the topmost counter electrode 1, and the object 100 sterilized on the upper stage moves to the successive lower stage counter electrode 11, where the sterilization and discharge are repeated in the same manner, and the object 100 moves continuously between each stage of the counter electrode 1 and storage means 2, ensuring a substantial sterilization processing time while easily performing rapid and efficient sterilization.

Third Embodiment
Hereinafter, a plasma sterilization device according to a third embodiment will be described with reference to FIG.

The third embodiment, like the first embodiment described above, comprises the counter electrode 1, the storage means 2, the supply means 3, and the control means 4, and further comprises a discharge position control unit 5 formed by sealing a liquid dielectric C between the counter electrodes 1 consisting of the upper electrode 11 and the lower electrode 12, in a dielectric case formed of a dielectric material (e.g., glass, etc.), as shown in FIG. 11.

The liquid constituting this liquid dielectric C is not particularly limited, but it is preferable to use a polarizable liquid such as water, nitrobenzene, methyl alcohol, or acetone, because the temperature dependence of the solvent dielectric constant is good, and it is particularly preferable to use water, because it is easy to handle.

In addition, it is preferable to fill the dielectric case with the liquid dielectric C without leaving any gaps in order to more efficiently obtain the effect of suppressing the occurrence of arc discharge described below.

In this way, due to the action of the discharge position control unit 5, the dielectric constant at the position where plasma is generated between the opposing electrodes 1 decreases, and the next plasma generation position shifts sequentially to other adjacent positions with higher dielectric constants, suppressing the occurrence of arc discharge and allowing a stable and gentle discharge to be continuously generated between the opposing electrodes 1 (between the upper electrode 11 and the lower electrode 12), making it possible to maintain plasma sterilization in a gentle discharge state that does not damage the target object 100.

In other words, by using this configuration with the discharge position control unit 5, it is possible to uniformly and stabilize plasma generation even in a situation where the electric field distribution is uneven, such as when an object 100 that is treated as a foreign object from the perspective of the discharge is present between the electrodes.

The discharge position control unit 5 configured in this embodiment can also be applied to the plasma sterilization devices according to the first and second embodiments.

REFERENCE SIGNS LIST 1 Counter electrode 11 Upper electrode 11a Upper mesh electrode 12 Lower electrode 12a Lower mesh electrode 2 Storage means 21 Bottom surface 22 Partition body 22a Guide fin 22b Frame body portion 22c Discharge port 23 Storage portion 3 Supply means 4 Control means 41 Axis center 5 Discharge position control portion 100 Target object 200 AC power source 200a Upper AC power source 200b Lower AC power source 200c Middle power source 300 Recovery portion

Claims (5)

A plasma sterilization device for sterilizing an object using atmospheric plasma generated by applying a voltage between electrodes in an atmosphere of a gas made from atmospheric air,
an opposing electrode including a plate-shaped upper electrode and a plate-shaped lower electrode facing each other with a gap therebetween in the vertical direction;
a storage unit that is provided as a plane having an xy direction, a bottom surface of which is formed of a plate-shaped insulating material or the lower electrode, and that is provided with a partition body composed of guide fins radially placed on an outer periphery, the storage unit being disposed between the opposing electrodes, the central portion of the plane being configured eccentrically from the central position of the upper electrode and/or the lower electrode, the storage unit eccentrically swinging by rotation about the central position , and the storage unit that stores an object in the storage unit;
A supply means for supplying the object toward the gap;
a control means for controlling the storage means to change the rotation direction to cause the object to remain in a central portion of the storage means and to discharge the object that has moved to the outer periphery through gaps between the guide fins;
The present invention is characterized by comprising
Plasma sterilization device. The plasma sterilization device according to claim 1,
The plasma sterilization device, characterized in that the control means changes the rotation direction of the storage means between forward and reverse directions, and controls the retention and discharge of the object within the storage means according to the rotation direction. A plasma sterilization device for sterilizing an object using atmospheric plasma generated by applying a voltage between electrodes in an atmosphere of a gas made from atmospheric air,
an opposing electrode including a plate-shaped upper electrode and a plate-shaped lower electrode facing each other with a gap therebetween in the vertical direction;
a storage unit that is provided as a plane having an xy direction, a bottom surface of which is formed of a plate-like insulating material or the lower electrode, a partition wall body that has an open outlet on an outer periphery and is composed of a frame body that is disposed on an outer end of the insulating material, the storage unit being disposed between the opposing electrodes, the central part of the plane being supported by a shaft center, the storage unit being swung so as to tilt while rotating the shaft center, and the storage unit being supported by a shaft center while the object is stored in the storage unit;
A supply means for supplying the object toward the gap;
a control means for controlling retention and discharge of the object in the storage means by changing the axis of the storage means in terms of a rotation direction and a tilt angle;
A plasma sterilization device comprising: In the plasma sterilization device according to any one of claims 1 to 3,
The plasma sterilization device, wherein the supply means supplies the raw material gas together with the object. In the plasma sterilization device according to any one of claims 1 to 3,
The plasma sterilization device further comprises a discharge position control section formed by sealing a liquid dielectric between the opposing electrodes.

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