Plasma processing apparatus

Abstract

To provide a plasma treatment device capable of continuously and uniformly treating an object by not only plasma but also ultraviolet rays.SOLUTION: A plasma generating unit including a plurality of electrodes 114 and 116 and a dielectric layer 118 between the electrodes 114 and 116, the plasma generating unit being configured to generate plasma in the dielectric layer 118 by applying volts alternating current to the electrodes 114 and 116, a protective dielectric layer 104 disposed on at least one outer side of the plasma generating unit, a mass transfer layer 106 configured to transfer an object to an outer side of the protective dielectric layer 104, and a power supply unit configured to apply volts alternating current to the electrodes 114 and 116, wherein the protective dielectric layer 104 is formed of an ultraviolet-transmitting member that transmits ultraviolet light; The plasma treatment device 100 treats an object in the mass transfer layer 106 by plasma and ultraviolet rays generated in the plasma generation part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a plasma processing apparatus for processing an object with plasma and ultraviolet rays. [Background technology]

[0002] In recent years, a technique called dielectric barrier discharge (DBD) has been developed in plasma processing technology, making it possible to generate low-temperature plasma at atmospheric pressure. As a result, the range of applications of plasma processing has expanded, and it is increasingly being used in a variety of applications. The purposes of plasma processing include sterilization, deodorization, surface modification, and decomposition of chemical substances. Furthermore, the substances that can be subjected to plasma processing can be solid, liquid, or gaseous.

[0003] It is already known that ultraviolet rays can be generated by exciting molecules or atoms with plasma, as described, for example, in Patent Document 1. Ultraviolet rays are high-energy electromagnetic waves with wavelengths of 10 to 400 nm, and are already widely used for various purposes, such as sterilization in water treatment and disinfection of medical instruments. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Republished Patent No. 2009 / 123258 Summary of the Invention [Problem to be solved by the invention]

[0005] When a dielectric barrier discharge occurs, not only is plasma generated, but ultraviolet and violet visible light may also be generated. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a plasma processing apparatus that can continuously and uniformly process objects using not only plasma but also ultraviolet light. [Means for solving the problem]

[0006] The inventors discovered that by utilizing plasma leaking from a plasma generating section composed of an electrode layer and a dielectric layer, it is possible to continuously and uniformly treat objects moving within a mass transfer layer with plasma. They also discovered that by constructing a protective dielectric layer from an ultraviolet-transparent material that transmits ultraviolet rays, it is possible to continuously and uniformly treat objects with not only plasma but also ultraviolet rays, leading to the present invention.

[0007] That is, the present invention has the following configuration. (1) A plasma processing apparatus comprising: a plurality of electrode layers; a plasma generation unit having a dielectric layer between the electrode layers and generating plasma in the dielectric layer by applying an AC voltage to the electrode layers; a protective dielectric layer on the outside of at least one of the plasma generation units; a mass transfer layer that moves an object to the outside of the protective dielectric layer; and a power supply unit that applies an AC voltage to the electrode layers, wherein the protective dielectric layer is made of an ultraviolet-transparent material that transmits ultraviolet light; and wherein the object in the mass transfer layer is processed by the plasma and ultraviolet light generated in the plasma generation unit. (2) The plasma processing apparatus according to (1) above, wherein the ultraviolet-transmitting member is made of quartz glass or a synthetic resin that transmits ultraviolet light. (3) The plasma processing apparatus according to (1) above, wherein the outer edge of the electrode layer is sealed with an insulating member. (4) The plasma processing apparatus according to (1), wherein at least one of the electrode layers has a plurality of through holes, and the through holes are sealed with an insulating member. [Effects of the Invention]

[0008] The plasma processing apparatus of the present invention can process objects continuously and uniformly not only with plasma but also with ultraviolet light. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view for explaining a plasma generating unit. [Figure 2] FIG. 2 is a perspective view for explaining a plasma generating unit. [Figure 3] FIG. 2 is a cross-sectional view illustrating a plasma generating unit. [Figure 4] FIG. 10 is a perspective view for explaining a plasma generating unit according to a first modified example. [Figure 5] FIG. 10 is a perspective view for explaining a plasma generating unit according to a second modified example. [Figure 6] FIG. 10 is a cross-sectional view illustrating a plasma generating unit according to a third modified example. [Figure 7] 1 is a side view showing the configuration of a plasma processing apparatus according to a first embodiment of the present invention; [Figure 8] 8 is a partially enlarged view illustrating the plasma generation principle using part A shown in FIG. 7. FIG. [Figure 9] FIG. 2 is a schematic diagram showing a first transfer mechanism that transfers an object along a mass transfer layer. [Figure 10] FIG. 2 is a schematic diagram showing a second transfer mechanism that transfers an object along a mass transfer layer. [Figure 11] FIG. 10 is a schematic diagram showing a third transfer mechanism that transfers an object along a mass transfer layer. [Figure 12] FIG. 2 is a schematic diagram illustrating a mixing mechanism for mixing objects. [Figure 13] 13 is a side view of the plasma electrode structure incorporated into the rotor shown in FIG. 12. FIG. [Figure 14] FIG. 14 is a side configuration view showing a first modified example of the plasma electrode structure shown in FIG. [Figure 15] FIG. 14 is a side view showing a second modified example of the plasma electrode structure shown in FIG. [Figure 16] FIG. 10 is a perspective view showing the configuration of a plasma processing apparatus according to a second embodiment of the present invention. [Figure 17] FIG. 17 is a side view of the plasma processing apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the embodiments of the present invention are not limited to the embodiments described below. Each embodiment and modified example can be applied in appropriate combination. Furthermore, directions such as "upper" and "lower" in the description are used for convenience of explanation and do not limit the directions of the present invention.

[0011] In this embodiment, the target object refers to gas, liquid, solid, or a mixture thereof. It may be gas only, liquid only, solid only, a mixture of gas and liquid, a mixture of liquid and solid, a mixture of gas and solid, or a mixture of gas, liquid, and solid. In the case of a solid, there are no limitations on size or shape. The solid material may be natural or artificial, and is not limited. Specifically, substances or powders such as metals, gems, sand, stones, seeds, flour, rice, corn, and buckwheat can be used.

[0012] In this embodiment, the target object is not moved between a pair of electrodes to which an AC voltage is applied, but is moved in the space outside the pair of electrodes to which an AC voltage is applied (outside the plasma generating section). Therefore, even if the target object is a conductive material such as a metal, electricity does not flow through the conductive material, so plasma processing can be performed safely.

[0013] The plasma processing apparatus of this embodiment includes a power supply unit for applying an AC voltage to a plasma generation unit, a protective dielectric layer, a mass transfer layer, and an electrode layer. The plasma generation unit includes a plurality of electrode layers and a dielectric layer between the electrode layers. The plasma generation unit may further include a mask layer. In dielectric barrier discharge, by applying an AC voltage between a pair of adjacent electrode layers, plasma and ultraviolet rays can be generated within the dielectric layer sandwiched between the electrode layers. First, the plasma generation unit will be described.

[0014] <Basic structure of the plasma generation unit> As shown in FIGS. 1 and 2, the plasma generating unit 10 includes a dielectric layer 11, an upper electrode layer 12, a lower electrode layer 13, an upper mask layer 14, and a lower mask layer 15. The plasma generating unit 10 may be made of a thin film member made of a flexible material. For convenience, the dielectric layer 11 is depicted as a single dielectric layer, but it may also have a multilayer structure in which multiple dielectric layers, including one or more air layers, are stacked. The mask layer is intended to protect the electrode layer and improve assembly of the electrode layer, and may be omitted. Furthermore, by appropriately selecting the thickness and position of the mask layer, excessive electric field concentration on the electrode layer can be prevented, thereby extending the life of the electrode layer.

[0015] As shown in FIGS. 1 to 3, the dielectric layer 11 is a layered member disposed between the upper electrode layer 12 and the lower electrode layer 13. The material of the dielectric layer 11 is an insulating material with a large breakdown voltage so that discharge does not easily occur between the upper electrode layer 12 and the lower electrode layer 13. Furthermore, since the material of the dielectric layer 11 will be exposed to the generated plasma, it is preferable that the material be durable against active substances generated in the plasma. The material of the dielectric layer 11 is preferably a material selected mainly from glass, ceramics, and synthetic resins. The term "mainly" means that the component composition is 50% by mass or more (the same applies hereinafter).

[0016] Examples of glass include soda-lime glass (soda glass), borosilicate glass, quartz glass, lead glass, oxide glass, etc. Examples of ceramics include alumina, silica, titanium oxide, zinc oxide, etc.

[0017] Synthetic resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include general-purpose resins such as polyolefin, polystyrene, polyvinyl acetate, polyurethane, polylactic acid, ABS resin, AS resin, acrylic resin, polyvinyl chloride, and polyvinylidene chloride; engineering plastics such as polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester, and cyclic polyolefin; and super-engineering plastics such as polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, liquid crystal polymer, polyetheretherketone, polyimide, polyamideimide, polyetherimide, fluorine-based resin, and silicone-based resin. Examples of thermosetting resins include phenolic resin, melamine resin, urea resin, alkyd resin, epoxy resin, unsaturated polyester resin, and polyurethane resin. Among these synthetic resins, silicone-based resins, polyimide-based resins, and Teflon®-based resins, which are highly durable, are particularly preferred. The thickness of the dielectric layer 11 is not particularly limited, but is preferably 0.1 mm to 5.0 mm, more preferably 0.1 mm to 3.0 mm, and even more preferably 0.1 mm to 1.0 mm, in order to achieve light weight and compactness.

[0018] As shown in FIGS. 1 to 3, the upper electrode layer (electrode layer) 12 and the lower electrode layer (electrode layer) 13 are layered members disposed on the front and back of the dielectric layer 11. The outer edges (peripheries) of the electrode layers 12 and 13 are preferably sealed with an insulating member. The insulating member serves to insulate the electrode layers 12 and 13, which are exposed to high temperatures and active substances when an AC voltage is applied, from the outside world and to protect them from deterioration over time. The insulating member also serves to prevent short-circuiting between the electrode layers 12 and 13, to which an AC voltage is applied, via the surrounding end faces or surfaces of components.

[0019] At least one of the electrode layers 12, 13 preferably has a plurality of through holes 16. The upper electrode layer 12 and the lower electrode layer 13 shown in FIGS. 1 to 3 are each provided with through holes 16 penetrating in the thickness direction. In this embodiment, the through holes 16 are oval in plan view, and five through holes 16 are formed, but the shape and number are not limited. When through holes 16 are formed in the electrode layer, acute-angled edges are present near the cross-section of the electrode layer within the through holes 16, which makes it easier to generate plasma and ultraviolet rays in the surrounding area, which is preferable. Therefore, by forming many through holes 16, more plasma and ultraviolet rays can be generated.

[0020] 1 to 3, through holes 16 formed in the upper electrode layer 12 and the lower electrode layer 13 and through holes 17 formed in the upper mask layer 14 and the lower mask layer 15 (described later) are formed in the same position and with the same shape, and are continuous. As a result, the inside of the through holes 16 is exposed to the outside. At this time, plasma and ultraviolet rays generated near the cross section of the electrode layer in the through holes 16 leak out to the outside through the through holes 16, 17, and are effective in plasma treatment and ultraviolet treatment of objects moving outside the plasma generation unit 10.

[0021] On the other hand, there is an embodiment in which through holes are formed in the upper electrode layer 12 and the lower electrode layer 13, but no through holes are formed in the upper mask layer 14 and the lower mask layer 15 described below (see FIG. 16 ). In this case, the through holes 16 formed in the electrode layers 12 and 13 are preferably sealed with an insulating member. Forming the through holes 16 in the electrode layers 12 and 13 has the advantage of facilitating the generation of plasma and ultraviolet rays near the cross-sections of the electrode layers within the through holes 16. On the other hand, if the formed through holes 16 are sealed with an insulating member, there is no cavity (space) where the through holes 16 are formed. This makes it possible to suppress the occurrence of a discharge phenomenon between the electrode layers through the cavity (space), and thus to suppress a decrease in the durability of the plasma generation unit 10.

[0022] The shape, number, and orientation of the through holes 16, 17 relative to the moving direction of the object can be selected appropriately depending on the purpose of the plasma processing, the effect of the plasma processing, etc. Furthermore, the shapes of the through holes may be different on the front and back sides of the plasma generating unit 10. Furthermore, the through holes may be provided on the front side of the plasma generating unit 10, and no through holes may be provided on the back side. Furthermore, the ratio of the area of ​​the through holes 16, 17 to the area of ​​the conductor (electrode) is not particularly specified, but the same effect can be obtained with a structure in which the hole dimensions of the through holes 16, 17 are large, for example, a mesh-like structure.

[0023] The upper electrode layer 12 and the lower electrode layer 13 are formed of a conductive material, and may be a metal plate (including metal foil), a conductive paint, a conductive polymer, a conductive film, etc. The thickness of the upper electrode layer 12 and the lower electrode layer 13 is not particularly limited, but is preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm, respectively, in order to provide a flexible, lightweight, and compact processing device.

[0024] The dielectric layer 11, the upper electrode layer 12, and the lower electrode layer 13 may be laminated without using an adhesive, or may be bonded with an adhesive. The adhesive is preferably a material that is durable against active substances generated in plasma. Examples of adhesives include epoxy, acrylic, urethane, phenol, urea, silicone, cyanoacrylate, rubber, and vinyl acetate adhesives. Among these, silicone adhesives and UV-curable epoxy adhesives are preferred from the viewpoint of durability, with polyamide adhesives, polyimide adhesives, and silicone adhesives being more preferred. The thickness of the adhesive is preferably 0.01 to 0.2 mm, and more preferably 0.01 to 0.1 mm.

[0025] As shown in FIGS. 1 to 3 , the upper mask layer 14 and the lower mask layer 15 are members disposed on the outer sides of the upper electrode layer 12 and the lower electrode layer 13, respectively. More specifically, the upper mask layer 14 is disposed on the upper surface of the upper electrode layer 12. The lower mask layer 15 is disposed on the lower surface of the lower electrode layer 13. The upper mask layer 14 and the lower mask layer 15 are each provided with through holes 17. In this embodiment, the through holes 17 are oval in shape, and five through holes 17 are formed, but the shape and number are not limited thereto. The through holes 17 may be omitted. Furthermore, for ease of manufacture, the through holes 17 are preferably the same as the through holes 16, but are not limited thereto.

[0026] In the structures shown in FIGS. 2 and 3 , the through holes 17 are illustrated as having the same shape as the through holes 16, but this is not limited thereto. The through holes 16, 17 expose the dielectric layer 11 to the outside. In other words, the surface of the dielectric layer 11 is exposed to the outside at multiple locations where the through holes 16, 17 are formed. The hole walls (cross-sectional portions) 16a, 17a of the through holes 16, 17 are also exposed to the outside, respectively. The through holes 16, 17 may be formed on only one side. Furthermore, when the mask layer is formed using a liquid resin or the like, the mask layer penetrates into areas without electrodes and directly covers the dielectric layer 11. However, in such cases, in areas where the dielectric layer 11 is exposed, the material constituting the mask layer functions as part of the dielectric layer 11. At the same time, the mask layer can also be used to protect the dielectric layer 11.

[0027] The upper mask layer 14 and the lower mask layer 15 are formed of an insulating material. Similar to the dielectric layer 11, the insulating material is preferably a material selected from glass, ceramics, and synthetic resins. Furthermore, the hardness of the upper mask layer 14 and the lower mask layer 15 is preferably equal to or less than that of the upper electrode layer 12 and the lower electrode layer 13. While the plasma generation unit 10 can be difficult to handle if it is manufactured using a thin material, providing the upper mask layer 14 and the lower mask layer 15 improves ease of handling. Furthermore, the upper mask layer 14 and the lower mask layer 15 can protect the thin conductor from mechanical and physical shocks during manufacture and use, as well as deterioration caused by the surrounding environment. Furthermore, they can provide mechanical protection against scratches that may occur during manufacture. On the other hand, when considering that the plasma generating unit 10 will be installed on an object to be mounted, it is preferable that the upper mask layer 14 and the lower mask layer 15 have a hardness that allows them to be easily installed along the object to be mounted and also improves handling. Furthermore, by dividing the dielectric layer 11 into two, the upper and lower structures of the plasma generating unit 10 can be made symmetrical. Manufacturing can be easily achieved by assembling the upper and lower structures and bonding them together in the center. In this case, the dielectric layer 11 is divided into three layers: the upper layer, the lower layer, and the adhesive layer, but can be considered electrically as a single dielectric.

[0028] The thicknesses of the upper mask layer 14 and the lower mask layer 15 are not particularly limited, but in order to provide a flexible, lightweight, and compact processing device, they are preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm. The thicknesses of the upper mask layer 14 and the lower mask layer 15 may be set appropriately, but in this embodiment they are formed to be thicker than the thicknesses of the upper electrode layer 12 and the lower electrode layer 13.

[0029] The plasma generating unit 10 can be made very thin and flexible, which can lead to problems such as difficulty in handling during assembly. Furthermore, the plasma generating unit 10 is installed to conform to the shape of the target object. However, if the upper and lower mask layers 14 and 15 are not provided and only the upper and lower electrode layers 12 and 13 are used, problems arise in that the metal constituting the electrodes may wrinkle or gaps may form between the dielectric layer 11 and the upper and lower electrode layers 12 and 13, respectively, if the electrodes are made of thin metal. Gaps between the upper and lower electrode layers 12 and 13 and the dielectric layer 11 can cause abnormal or partial discharges.

[0030] In this regard, according to the present embodiment, the upper mask layer 14 and the lower mask layer 15 can protect the upper electrode layer 12 and the lower electrode layer 13, making the plasma generation unit 10 easier to handle and improving workability and assembly. Furthermore, the provision of the upper mask layer 14 and the lower mask layer 15 allows the plasma generation unit 10 to be installed on an object without forming wrinkles or gaps. Furthermore, when multiple pairs of electrodes are provided in a multi-stage configuration, the upper mask layer 14 and the lower mask layer 15 also serve as part of the dielectric constituting the barrier discharge, making it less likely that abnormal discharge will occur even if gaps are formed during installation. However, the upper mask layer 14 and the lower mask layer 15 are not particularly necessary for applications in which mechanical strength, electrode life, etc. are not a consideration. Furthermore, as long as the dielectric layer 11 sufficiently protrudes from the ends of the upper electrode layer 12 and the lower electrode layer 13, the upper mask layer 14 and the lower mask layer 15 are not necessarily required. Furthermore, an insulating layer (not shown) may be provided on the outside of the upper mask layer 14 and the lower mask layer 15 . The plasma generating unit 10 may have a configuration in which a plurality of electrode layers and dielectric layers 11 are alternately stacked as needed. Also, it may have a configuration in which a plurality of the layer configurations shown in Figs. 1 to 6 are stacked. In this case, in addition to the electrode layers and dielectric layers 11, mask layers, insulating layers, etc. may be appropriately combined.

[0031] <First Modification of Plasma Generation Unit> 4 is a perspective view for explaining a plasma generating unit according to a first modified example. The plasma generating unit 10A according to the first modified example differs from the basic structure described above in that it does not have an upper mask layer 14. As in the plasma generating unit according to the first modified example, the mask electrode (mask electrode layer) may be provided only on one side of the plasma generating unit 10A.

[0032] <Second Modification of Plasma Generation Unit> FIG. 5 is a perspective view illustrating a plasma generating unit according to a second modified example. The plasma generating unit 10B according to the second modified example differs from the basic structure described above in that it does not include the upper mask layer 14 and the lower mask layer 15. As with the plasma generating unit 10B according to the second modified example, the upper mask layer 14 and the lower mask layer 15 may be omitted. By configuring the plasma generating unit 10B with a dielectric layer 11, an upper electrode layer 12, and a lower electrode layer 13, it is possible to further reduce the size of the unit, reduce the number of electrode manufacturing steps, and reduce the number of parts. Furthermore, by thinning the dielectric layer 11, the upper electrode layer 12, and the lower electrode layer 13, the electrode layers themselves can be made flexible, allowing them to be manufactured to conform to curved surfaces.

[0033] Furthermore, as in the first and second modified examples, by omitting both or one of the upper mask layer 14 and the lower mask layer 15, the upper electrode layer 12 and the lower electrode layer 13 can be brought into direct contact with gas, and the plasma or ultraviolet light can be brought into contact with the object at the edge of the electrode layer, thereby enabling plasma treatment or ultraviolet light treatment.

[0034] <Third Modification of Plasma Generation Unit> FIG. 6 is a cross-sectional view illustrating a plasma generation unit according to a third modified example. The plasma generation unit 10C according to the third modified example differs from the basic structure described above in that it does not include an upper mask layer 14 and a lower mask layer 15. Furthermore, the plasma generation unit 10C according to the third modified example does not have a monolithic dielectric layer. Instead, it is composed of an upper dielectric layer 18 and a lower dielectric layer 19, which are separated vertically and arranged facing each other. However, since air is also considered a type of dielectric, if the upper dielectric layer 18, air layer 20, and lower dielectric layer 19 are combined into a single dielectric layer 11, the structure is the same as that of the plasma generation unit 10B shown in FIG. 5. An upper electrode layer 12 is provided on the upper surface of the upper dielectric layer 18, and a lower electrode layer 13 is provided on the lower surface of the lower dielectric layer 19. An air layer 20 is provided between the upper dielectric layer 18 and the lower dielectric layer 19. In the third modified example, plasma and ultraviolet rays can be generated even in the air layer 20.

[0035] First Embodiment Next, a plasma processing apparatus according to a first embodiment of the present invention will be described. FIG. 7 is a side view showing the configuration of the plasma processing apparatus according to the first embodiment of the present invention, and FIG. 8 is a partially enlarged view illustrating the principle of plasma generation using part A shown in FIG. 7. The plasma processing apparatus 100 according to the first embodiment of the present invention comprises a plasma generation unit, a protective dielectric layer, a mass transfer layer, and a power supply unit (not shown). Of these, the structure forming the multilayer structure including the plasma generation unit, the protective dielectric layer, and the mass transfer layer will be referred to as a plasma electrode structure 102.

[0036] The plasma generating section is composed of a first electrode layer 114 , a second electrode layer 116 , a dielectric layer 118 , a first mask layer 112 , and a second mask layer 120 . The plasma electrode structure 102 is composed of a plasma generation unit, a first protective dielectric layer 104 that prevents the entry of objects, a mass transfer layer 106 sandwiched between two first protective dielectric layers 104, a second protective dielectric layer 110, and a lower protective conductor 108. In Figures 7 and 8, the outline arrows indicate the direction in which the objects move.

[0037] The first mask layer 112 and the second mask layer 120 are members corresponding to the upper mask layer 14 and the lower mask layer 15 (see FIGS. 1 and 2) of the plasma generating unit 10 described above, and have the same functions and effects. The dielectric layer 118 is a member corresponding to the dielectric layer 11 of the plasma generating unit 10 described above, and has the same functions and effects.

[0038] Furthermore, the first electrode layer 114 and the second electrode layer 116 of the plasma generating unit are formed with a plurality of through-holes (not shown) penetrating through the layer in the thickness direction. The optimal size of the through-holes depends on the power supply frequency of the AC power supply and the characteristics of the dielectric layer 118, but is preferably approximately 0.1 mm to 20 mm. In this embodiment, the through-holes in the first electrode layer 114 and the second electrode layer 116 may have the same symmetrical shape, but this is not a limitation. Although FIGS. 7 and 8 show the first electrode layer 114 and the second electrode layer 116 as having the same size (width), this is not a limitation. The lower protective conductor 108 is provided to enhance safety by grounding the first electrode layer 114 and the second electrode layer 116 to prevent the electric field leaking from them from adversely affecting the outside.

[0039] The pair of protective dielectric layers 104 is composed of an upper protective dielectric layer 104a, which is disposed on the upper side with the mass transfer layer 106 sandwiched therebetween, and a lower protective dielectric layer 104b, which is disposed on the lower side with the mass transfer layer 106 sandwiched therebetween. The lower protective dielectric layer 104b prevents intrusion of objects into the first electrode layer 114 and the second electrode layer 116 and prevents corrosion, oxidation, deterioration, and mechanical damage to the electrode layers. Furthermore, using a material with a smooth surface improves the cleanability of the mass transfer layer 106. Furthermore, when handling medical or food-grade objects, using a material that complies with these standards allows for the handling of such objects. The upper protective dielectric layer 104a and the lower protective dielectric layer 104b are both referred to as the "protective dielectric layer 104." The second protective dielectric layer 110 has the same function as the first protective dielectric layer 104 but is provided as a backup.

[0040] Like the mask layer, the protective dielectric layer 104 is made of an insulating material. As with the dielectric layer 11, the insulating material is preferably a material selected from the group consisting of glass, ceramics, and synthetic resins.

[0041] 7 and 8, the plasma electrode structure 102 is configured in a linear shape (flat, layered), but if the plasma electrode structure 102 is configured from a thin, flexible material, it can be bent within a range that does not damage the material. As a result, even if the plasma electrode structure 102 becomes large and bending occurs in the lower protective dielectric layer 104b, or if an object is moved to the mass transfer layer 106 and its center expands due to pressure, the first electrode layer 114 and the second electrode layer 116 can be configured to bend accordingly and absorb mechanical strain.

[0042] Here, the protective dielectric layer 104 is made of an ultraviolet-transmitting material that transmits ultraviolet rays. The plasma generating unit generates not only plasma but also ultraviolet rays. As the plasma is generated, ultraviolet rays are emitted when molecules and atoms excited by the plasma return to their ground state. If the protective dielectric layer 104 is made of an ultraviolet-transmitting material, ultraviolet rays generated between the pair of electrode layers of the plasma generating unit pass through the protective dielectric layer 104 and are irradiated onto the target M in the mass transfer layer 106 (dotted line UV1 in Figure 8). At this time, if the second electrode layer 116 is a thin layer, ultraviolet rays can easily pass to the outside. Similarly to the protective dielectric layer 104, the second mask layer 120 is preferably made of an ultraviolet-transmitting material or is a sufficiently thin layer that easily transmits ultraviolet rays. In addition, plasma that leaks outside the pair of electrode layers of the plasma generation section and penetrates the second mask layer 120 and the protective dielectric layer 104 may generate ultraviolet light within the mass transfer layer 106, which may then be irradiated onto the object M within the mass transfer layer 106 (dotted line UV2 in Figure 8).

[0043] Examples of the ultraviolet-transmitting member include quartz glass and synthetic resins that transmit ultraviolet light, such as polyethylene, polypropylene, polyvinyl chloride, polyamide, and polyvinyl alcohol.

[0044] <Action and effect> In the plasma electrode structure 102, an AC voltage is applied between the first electrode layer 114 and the second electrode layer 116 by a power supply unit. As a result, plasma is generated between the first electrode layer 114 and the second electrode layer 116. Most of the plasma and ultraviolet rays are generated in the dielectric layer 118 that exists between the first electrode layer 114 and the second electrode layer 116. Some of the plasma and ultraviolet rays leak out to the back side of the second electrode layer 116 through through-holes or the like, pass through the lower protective dielectric layer 104b, and reach the mass transfer layer 106 (white arrows in Figure 8). The object M moving within the mass transfer layer 106 is treated by contacting the plasma and ultraviolet rays that have leaked into the mass transfer layer 106.

[0045] The amount of plasma and ultraviolet rays leaking into the mass transfer layer 106 on the upper surface of the lower protective dielectric layer 104b can be controlled by appropriately selecting the number and pattern of through holes formed in the second electrode layer 116, the thickness, dielectric constant, and dielectric strength of the lower protective dielectric layer 104b, etc. Therefore, the amount of plasma and ultraviolet light in mass transfer layer 106 is hardly affected by object M moving through mass transfer layer 106. As a result, object M moving through mass transfer layer 106 can be stably treated with a constant amount of plasma and ultraviolet light.

[0046] Furthermore, in this embodiment, processing can be performed using plasma and ultraviolet light without applying a high voltage to the object M passing through the mass transfer layer 106, so processing can be performed stably even on conductive objects, which was difficult to do with conventional methods, or in situations where the conditions in the space change from moment to moment.

[0047] Furthermore, in this embodiment, even if the properties of the object (e.g., dielectric constant, conductivity, saturation rate, etc.) change, the impedance between the electrode layers does not change, so larger electrodes can be used, and therefore the plasma and ultraviolet rays can come into contact with the object over a larger area, thereby enabling the generation of large amounts of plasma and ultraviolet rays in this embodiment.

[0048] The power supply unit is not particularly limited as long as it can apply an AC voltage of a predetermined voltage at a predetermined frequency to each electrode of the plasma generating unit, and any known power supply device can be used. The frequency of the AC voltage is preferably 50 Hz to 30 MHz, and more preferably 50 Hz to 100 kHz. The AC voltage is preferably 0.1 to 50 kV, and more preferably 0.2 to 10 kV.

[0049] Next, the transfer mechanism for transferring the object along the mass transfer layer 106 will be described in detail. Here, several specific examples of transfer mechanisms for transferring the object through the mass transfer layer when the object is a solid will be described. Here, a solid refers to a mixture containing a solid, and may be a mixture of a solid and a liquid, a mixture of a solid and a gas, or a mixture of a solid, a liquid, and a gas. There are no limitations on the size or shape of the solid. The solid material may be either natural or artificial, and is not limited. Specifically, solids or powders such as metals, gems, sand, stones, seeds, flour, rice, corn, and buckwheat can be used.

[0050] <1st movement mechanism> As shown in FIG. 9 , the first transfer mechanism 200 uses gravity to cause the target to roll or slide within the mass transfer layer 106 provided on the plasma electrode structure 102. In the following figures, "M" indicates the target moving along the mass transfer layer 106. The first transfer mechanism 200 creates a vertical elevation difference between the inlet side 202 and the outlet side 204 of the mass transfer layer 106, allowing the target to move or slide along the mass transfer layer 106 due to its own weight. In this case, the inlet side 202 of the mass transfer layer 106 is elevated and the outlet side 204 is lowered, forming an inclined surface 206 due to the elevation difference. Because no high voltage is applied between the target and the first transfer mechanism 200, the plasma discharge is not significantly affected even if a conductor such as a metal is supplied to the mass transfer layer 106. If the protective dielectric layer 104 is made of an ultraviolet-transmitting material, the object M is processed not only by plasma but also by ultraviolet light. The same applies to the second movement mechanism, the third movement mechanism, and the substance mixing mechanism described below.

[0051] In conventional methods, a plasma discharge is generated between electrodes and an object is moved through the plasma discharge. When an electrically conductive object, such as a metal or conductive object, is moved, the plasma discharge is significantly affected, making it difficult to maintain a steady plasma. Furthermore, even if the object is not conductive, if it is a dielectric, the impedance of each part varies depending on the density of the material. When using a conventional power supply, the plasma tends to concentrate in areas with low impedance, making it difficult to obtain a uniform plasma. Furthermore, in conventional methods, a high-frequency current flows through the object, which can heat the object and change its properties.

[0052] In the first transfer mechanism 200, the plasma generated between the plasma electrodes is maintained in a substantially constant state, regardless of the dielectric constant, conductivity, or density of the object moving within the mass transfer layer 106. Furthermore, in this embodiment, a high voltage is not applied to the object itself, and no current flows through the object, so the object does not heat up due to Joule heat or the like generated by the current flow, and the properties of the object do not change.

[0053] The first movement mechanism 200 can, for example, sterilize bacteria adhering to the surfaces of seeds, grains, etc., or reduce the activity of mold. The first movement mechanism 200 is ideal for objects that are round and easy to roll, such as soybeans and adzuki beans. If necessary, it is preferable to provide a guide groove or the like on the upper surface of the lower protective dielectric layer 104b to make it easier for the object to roll in the correct direction.

[0054] <Second movement mechanism> The second moving mechanism 210, which is less likely to roll than the first moving mechanism 200, uses protrusions 212, such as blades, brushes, and spatulas, arranged on the opposite side of the plasma electrode to press and move the object. As shown in FIG. 10 , the second moving mechanism 210 includes an endless track belt 216 that circulates around multiple rollers 214, and multiple protrusions (e.g., blades, brushes, spatulas, etc.) 212 are attached to the endless track belt 216. The rotation of the multiple protrusions 212 integrally with the endless track belt 216 allows solids and powdery solids to move along the mass transfer layer 106 provided on the plasma electrode structure 102. Note that, for convenience, side covers and walls are not shown in FIG. 10 . These side covers and walls support the plasma electrode structure 102 and prevent the object from escaping from the sides of the mass transfer layer 106.

[0055] <Third movement mechanism> The third transfer mechanism 220 is preferably used primarily for powdery solids. As shown in Fig. 11, the third transfer mechanism 220 has a plurality of air nozzles 222 attached to the upper protective dielectric layer 104a, which are spaced apart at a predetermined interval along the direction of object movement, and which are inclined downward from an inlet side 224 to an outlet side 226. By supplying air from an air supply source (not shown) to each air nozzle 222, the object can be moved along the mass transfer layer 106 by the pressure (air flow) of the air ejected from the air nozzles 222.

[0056] <Matter mixing mechanism> The substance mixing mechanism 230 is primarily suitable for mixing solid, liquid, and powdered substances. As shown in FIG. 12 , the substance mixing mechanism 230 includes a container 232 having an opening on its top surface and containing the target substance therein; a rotation mechanism 234 including, for example, a motor, a pulley, a handle, etc.; a rotation shaft 236 rotatably connected to the rotation mechanism 234; a rotating plate 238 that rotates a predetermined rotation around the rotation shaft 236 by the rotation mechanism 234; and a rotating body 240 whose end portion extending in the vertical direction is connected to the underside of the rotating plate 238 and rotates integrally with the rotating plate 238. The rotating body 240 is composed of a blade or spatula incorporating a plasma electrode (described below), and is configured of one or more rotating bodies 240. The target substance contained in the container 232 is smoothly mixed by the rotation of the blade or spatula incorporating the plasma electrode under the rotational driving action of the rotation mechanism 234. Here, vessel 232 constitutes the mass transfer bed.

[0057] Fig. 13 is a side view of the plasma electrode structure incorporated inside the rotor 240 shown in Fig. 12. This plasma electrode structure 250 is composed of a pair of first and second electrode layers 252 and 254, an electrode support dielectric layer 256 interposed between the first and second electrode layers 252 and 254 to support the electrode layers, a pair of first and second mask layers 258 and 259 respectively arranged on the outer sides of the first and second electrode layers 252 and 254, and a pair of first and second protective dielectric layers 260 and 262 respectively arranged on the outer sides of the first and second mask layers 258 and 259 to protect the electrodes. The first and second electrode layers 252 and 254 of the pair of electrode layers are electrically connected to a power supply (not shown).

[0058] Fig. 14 is a side view of the plasma electrode structure according to the first modification. In the plasma electrode structure 250 shown in Fig. 13, the first electrode 252 connected to the high-voltage AC power supply is not sufficiently protected, so that leakage from the plasma electrode can be further prevented by configuring as follows.

[0059] In the plasma electrode structure 270 according to the first modification, the other second electrode 254 and the outermost protected electrode 272 are grounded (earthed), so that the high-voltage portion of one first electrode 252 connected to the high-voltage AC power supply can be covered. This makes it possible to prevent electric leakage to the worker even if the worker inadvertently touches the plasma electrode structure 270. Note that the protrusion 274, which protrudes upward compared to the other parts, is an attachment part for the rotating plate 238. A protective dielectric (rice scoop, spatula, blade body) 276 is interposed between the first mask layer 258 and the protected electrode 272.

[0060] 15 is a side view of a plasma electrode structure according to a second modification. In a plasma electrode structure 280 according to the second modification, a second electrode 284 and a third electrode 286 are arranged on the outer side of a central first electrode 282, and the second electrode 284 and the third electrode 286 surrounding the high-voltage first electrode 282 that generates plasma are respectively grounded (earthed), thereby making it possible to further prevent electric leakage to an operator even if the operator inadvertently touches the plasma electrode structure 280.

[0061] In the second modified example, a first electrode supporting dielectric 288 is interposed between the first electrode 282 and the second electrode 284, and a second electrode supporting dielectric 290 is interposed between the first electrode 282 and the third electrode 286. In addition, a third mask layer 292 is disposed on the outer side of the third electrode 286.

[0062] Second Embodiment Next, a plasma processing apparatus 300 according to a second embodiment of the present invention will be described. The same components as those in the plasma processing apparatus 100 according to the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted. The plasma processing apparatus 100 according to the first embodiment employs a one-sided electrode structure in which plasma electrodes (first electrode layer 114, second electrode layer 116) are arranged only on the lower side, whereas this embodiment differs in that a two-sided electrode structure in which plasma electrodes are arranged on both the upper and lower sides is employed.

[0063] FIG. 16 is a perspective view showing the configuration of a plasma processing apparatus according to a second embodiment of the present invention, and FIG. 17 is a side view showing the configuration of the plasma processing apparatus shown in FIG. The plasma processing apparatus 300 according to the second embodiment of the present invention comprises an upper electrode structure 302, which is one of the plasma generating sections, a lower electrode structure 304, which is the other of the plasma generating sections, and a space section provided between the upper electrode structure 302 and the lower electrode structure 304, and a mass transfer layer 106 through which the target material supplied from a target material supply source (not shown) moves.

[0064] The upper electrode structure 302 and the lower electrode structure 304 are arranged symmetrically to each other. The upper electrode structure 302 and the lower electrode structure 304 may have a symmetrical structure or different structures. In consideration of manufacturing costs, a symmetrical structure is preferable.

[0065] The upper electrode structure 302 is composed of an upper protective conductor layer 308 disposed at the top, an upper protective dielectric layer 310 laminated on the lower surface of the upper protective conductor layer 308, a first upper mask layer 312 laminated on the lower surface of the upper protective dielectric layer 310, a first upper electrode layer 314 and a second upper electrode layer 316 disposed below the first upper mask layer 312, an upper dielectric layer 318 interposed between the first upper electrode layer 314 and the second upper electrode layer 316, and a second upper mask layer 320 laminated on the lower surface of the upper dielectric layer 318. The first upper mask layer 312 and the second upper mask layer 320 correspond to the upper mask layers 14 and 15 (see FIGS. 1 and 2) of the plasma generation unit 10 and have the same functions and effects. The upper dielectric layer 318 corresponds to the dielectric layer 11 of the plasma generation unit 10 and has the same functions and effects. Furthermore, an upper protective dielectric layer 104a is provided below the upper electrode structure 302, and a mass transfer layer 106 consisting of a space is provided between the upper protective dielectric layer 104a and a lower protective dielectric layer 104b spaced apart in the vertical direction.

[0066] Furthermore, the first upper electrode layer 314 and the second upper electrode layer 316 are formed with a plurality of through-holes (not shown) penetrating through the thickness direction. The upper electrode structure 302 does not necessarily need to have the plurality of through-holes. The through-holes may also have an extremely large structure, such as a mesh-like structure. The optimal size of the through-holes depends on the power frequency of the AC power supply and the characteristics of the upper dielectric layer 318, but is preferably approximately 0.1 mm to 20 mm. In this embodiment, the through-holes may have a symmetrical structure with the same shape as the first upper electrode layer 314 and the second upper electrode layer 316, but this is not a limitation. Although FIGS. 16 and 17 show the first upper electrode layer 314 and the second upper electrode layer 316 as having the same size (area), this is not a limitation.

[0067] The lower electrode structure 304 is configured in the same manner as the plasma electrode structure 102 of the first embodiment. Also, like the first embodiment, the pair of protective dielectric layers 104 is configured from an upper protective dielectric layer 104a disposed on the upper side with the mass transfer layer 106 sandwiched therebetween, and a lower protective dielectric layer 104b disposed on the lower side with the mass transfer layer 106 sandwiched therebetween. The upper protective dielectric layer 104a prevents intrusion of objects into the first upper electrode layer 314 and the second upper electrode layer 316, and prevents corrosion, oxidation, deterioration, mechanical damage, etc. of the electrodes. Here, the upper protective dielectric layer 104a and the lower protective dielectric layer 104b are each configured from an ultraviolet-transmitting material that transmits ultraviolet light.

[0068] In this embodiment, since upper electrode structure 302 and lower electrode structure 304 each have an electrode layer for generating plasma, it is possible to perform treatment with a large amount of plasma and ultraviolet light on the object moving through mass transfer layer 106. In addition, by applying the first to third transfer mechanisms 200, 210, and 220 described above to this embodiment, it is possible to smoothly move the object along mass transfer layer 106. In this embodiment, substances moving along the mass transfer layer 106 from both the upper and lower sides are treated with plasma and ultraviolet light, thereby efficiently sterilizing and inactivating viruses, mold, bacteria, etc. present on the surface of the object.

[0069] Although the embodiments of the present invention have been described above, appropriate design changes are possible within the scope of the present invention. [Explanation of symbols]

[0070] 100, 300 Plasma treatment device 102 Plasma electrode structure 104 Protective dielectric layer 104a Upper protective dielectric layer 104b Lower protective dielectric layer 106 Mass transfer layer 114 First electrode layer (electrode layer) 116 Second electrode layer (electrode layer) 118 Dielectric Layer 200, 210, 220 movement mechanism 302 Upper electrode structure 304 Lower electrode structure

Claims

1. a plasma generating unit having a plurality of electrode layers and a dielectric layer between the electrode layers, and generating plasma in the dielectric layer by applying an AC voltage to the electrode layers; a protective dielectric layer on at least one outer surface of the plasma generating unit; a mass transfer layer for transferring an object to the outside of the protective dielectric layer; a power supply unit that applies an AC voltage to the electrode layer, the protective dielectric layer is made of an ultraviolet-transmitting member that transmits ultraviolet rays; A plasma processing apparatus characterized in that an object in the mass transfer layer is processed by the plasma generated in the plasma generating section and ultraviolet rays.

2. 2. The plasma processing apparatus according to claim 1, wherein the ultraviolet-transmitting member is made of quartz glass or a synthetic resin that transmits ultraviolet light.

3. 2. The plasma processing apparatus according to claim 1, wherein an outer edge of the electrode layer is sealed with an insulating member.

4. 2. The plasma processing apparatus according to claim 1, wherein at least one of the electrode layers has a plurality of through holes, and the through holes are sealed with an insulating member.

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