Discharge device

Abstract

To increase the production amount of an active ingredient.SOLUTION: The discharge device includes discharge electrode 41, counter electrode 42, and a voltage application circuit. Discharge electrode 41 includes tip end 411. Counter electrode 42 is disposed to face tip portion 411 of discharge electrode 41. The voltage application circuit applies a voltage between discharge electrode 41 and counter electrode 42. The discharge device forms a first dielectric breakdown region extending from discharge electrode 41 toward counter electrode 42, and a second dielectric breakdown region extending from counter electrode 42 toward discharge electrode 41. A base end of the first dielectric breakdown region is tip end 411 of discharge electrode 41. The base end portion of the second dielectric breakdown region is an annular portion provided in counter electrode 42.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates generally to a discharge device, and more particularly to a discharge device including a discharge electrode and a counter electrode. [Background technology]

[0002] Patent Document 1 describes a discharge device that includes a discharge electrode, a counter electrode, and a voltage application unit. The counter electrode is positioned opposite the discharge electrode. The voltage application unit applies a voltage to the discharge electrode, causing a discharge in the discharge electrode that is more energetic than a corona discharge. The high-energy discharge in the discharge device described in Patent Document 1 is a discharge that intermittently generates a discharge path that causes insulation breakdown between the discharge electrode and the counter electrode so as to connect the two.

[0003] In the discharge device described in Patent Document 1, a liquid is supplied to a discharge electrode by a liquid supply unit, and the liquid is electrostatically atomized by discharge, generating nanometer-sized charged minute water particles containing radicals.

[0004] The discharge mode of the discharge device described in Patent Document 1 generates active ingredients (radicals or charged minute particle liquid containing radicals) with greater energy than corona discharge, so a larger amount of active ingredients is generated compared to corona discharge. Furthermore, the amount of ozone generated is suppressed to the same level as in corona discharge. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-22574 Summary of the Invention [Problem to be solved by the invention]

[0006] In the discharge device described in Patent Document 1, it is desired to further increase the amount of active ingredients produced by discharge.

[0007] The present disclosure has been made in view of the above-mentioned circumstances, and aims to provide a discharge device that can increase the amount of active ingredients produced. [Means for solving the problem]

[0008] A discharge device according to one aspect of the present disclosure includes a discharge electrode, a counter electrode, and a voltage application circuit. The discharge electrode has a tip. The counter electrode is arranged to face the tip of the discharge electrode. The voltage application circuit applies a voltage between the discharge electrode and the counter electrode. The discharge device forms a first breakdown region extending from the discharge electrode toward the counter electrode and a second breakdown region extending from the counter electrode toward the discharge electrode. The base end of the first breakdown region is the tip of the discharge electrode. The base end of the second breakdown region is an annular portion provided on the counter electrode. A discharge device according to one aspect of the present disclosure includes a discharge electrode, a counter electrode, and a voltage application circuit. The discharge electrode has a tip. The counter electrode is arranged to face the tip of the discharge electrode. The voltage application circuit applies a voltage between the discharge electrode and the counter electrode. The discharge device forms a breakdown region connecting the discharge electrode and the counter electrode. The breakdown region is formed to connect the tip of the discharge electrode and an annular portion provided on the counter electrode. [Effects of the Invention]

[0009] According to the discharge device according to the above aspect of the present disclosure, it is possible to increase the amount of active ingredients produced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a discharge device according to an embodiment. [Figure 2]2A and 2B are schematic diagrams showing the state in which the liquid held in the discharge electrode of the discharge device is expanded and contracted, respectively. [Figure 3] Fig. 3A is a top view showing a load in the discharge device of Fig. 3. Fig. 3B is a cross-sectional view taken along line X1-X1 of Fig. 3A. [Figure 4] 4A is a partially cutaway schematic view of a main part of the load, FIG. 4B is a cross-sectional view of a main part of the load, and FIG. 4C is a front view of a discharge electrode of the load. [Figure 5] Fig. 5A is a schematic diagram showing the discharge form of a partial breakdown discharge, Fig. 5B is a schematic diagram showing the discharge form of a corona discharge, and Fig. 5C is a schematic diagram showing the discharge form of a total breakdown discharge. [Figure 6] Fig. 6A is a cross-sectional view of a main part of a load in a discharge device according to a first modified example, and Fig. 6B is a cross-sectional view of a main part of a load in a discharge device according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the embodiments described below, common elements are designated by the same reference numerals, and redundant descriptions of the common elements may be omitted. The following embodiment is merely one of various embodiments of the present disclosure. Various modifications to the embodiment are possible depending on the design, etc., as long as the object of the present disclosure is achieved. The figures described in this disclosure are schematic diagrams, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios. The arrows indicating each direction in the figures are merely examples and are not intended to define the orientation of the discharge device 10 during use. The arrows indicating each direction in the figures are merely shown for explanatory purposes and do not have any physical substance.

[0012] (1) Overview First, an outline of a discharge device 10 according to this embodiment will be described with reference to FIGS. 1 to 4A.

[0013] As shown in FIG. 1, the discharge device 10 according to this embodiment includes a voltage application device 1, a load 4 (electrode device), and a liquid supply unit 5.

[0014] As shown in Fig. 3B, the load 4 has a discharge electrode 41 and a counter electrode 42. The load 4 is a device that generates a discharge by applying a voltage between the discharge electrode 41 and the counter electrode 42. In the following description, the direction in which the discharge electrode 41 and the counter electrode 42 face each other is defined as the up-down direction. The direction from the discharge electrode 41 side to the counter electrode 42 side is defined as the up-down direction, and the direction from the counter electrode 42 side to the discharge electrode 41 side is defined as the down-down direction.

[0015] The discharge electrode 41 protrudes (upward) toward the counter electrode 42. The discharge electrode 41 has a tip 411 (see FIG. 2A). The tip 411 is formed at the tip (upper end) of the discharge electrode 41 in the direction in which the discharge electrode 41 protrudes. The tip 411 holds the liquid 50 (see FIG. 2A). In the following description, the direction in which the discharge electrode 41 protrudes (upward) may be referred to as the "protruding direction of the discharge electrode 41."

[0016] The counter electrode 42 is disposed so as to face the tip 411 of the discharge electrode 41 across a gap. The counter electrode 42 has a discharge part 420 where a discharge occurs between the counter electrode 42 and the tip 411 of the discharge electrode 41. The discharge part 420 extends linearly along the circumference of a circle centered on the tip 411 of the discharge electrode 41.

[0017] The liquid supply unit 5 supplies the liquid 50 to the tip 411 of the discharge electrode 41 .

[0018] The voltage application device 1 is a device that applies a voltage between the discharge electrode 41 and the counter electrode 42 to generate a discharge between the discharge electrode 41 and the counter electrode 42. In other words, by applying a voltage between the discharge electrode 41 and the counter electrode 42, the voltage application device 1 forms a discharge path L1 (see FIG. 4A ) with partial dielectric breakdown between the tip 411 of the discharge electrode 41 and the counter electrode 42. In this disclosure, "dielectric breakdown" refers to the breakdown of the electrical insulation of an insulator (including gas) separating conductors, causing the insulation state to be lost. Dielectric breakdown of gas occurs, for example, when ionized molecules are accelerated by an electric field and collide with and ionize other gas molecules, causing a sudden increase in ion concentration and causing a gas discharge.

[0019] Furthermore, in the voltage application device 1 of this embodiment, when the liquid 50 is held in the discharge electrode 41, a voltage is applied from the voltage application circuit 2 to the load 4 including the discharge electrode 41. This causes a discharge to occur at least in the discharge electrode 41, and the liquid 50 held in the discharge electrode 41 is electrostatically atomized by the discharge.

[0020] The discharge device 10 generates radicals by generating a discharge between the discharge electrode 41 and the counter electrode 42 of the load 4, and electrostatically atomizes the liquid 50 held by the discharge electrode 41. In other words, the discharge device 10 generates nanometer-sized charged minute particle liquid particles containing radicals in the fine droplets of the electrostatically atomized liquid 50. In other words, the discharge device 10 functions as a charged minute particle liquid generator (electrostatic atomizer). The radicals are the basis for providing useful effects in various situations, including sterilization, deodorization, moisturizing, freshness preservation, and virus inactivation. Hereinafter, radicals and charged minute particle liquid particles may be collectively referred to as active ingredients. The active ingredients also include air ions.

[0021] The discharge device 10 generates charged minute water particles containing radicals, thereby extending the life of the radicals compared to when the radicals are released into the air alone. Furthermore, since the charged minute water particles are nanometer-sized, the charged minute water particles can be suspended over a relatively wide area.

[0022] As described above, the counter electrode 42 of the discharge device 10 of this embodiment has a discharge portion 420. The discharge portion 420 is a portion that generates a discharge between itself and the tip 411 of the discharge electrode 41. As described above, the discharge portion 420 extends linearly along the circumference of a circle centered on the tip 411 of the discharge electrode 41, and therefore the discharge path L1, with its apex at the tip 411 of the discharge electrode 41, is wider than in a conventional load (counter electrode) that has a needle-shaped discharge portion. The wider discharge path L1 makes it possible to increase the amount of active ingredients (including radicals, etc.) produced by the discharge.

[0023] (2) Details The discharge device 10 according to this embodiment will be described below with reference to FIGS. 1 to 5C.

[0024] (2.1) Configuration of the discharge device As shown in FIG. 1, a discharge device 10 according to this embodiment includes a voltage application device 1, a load 4, and a liquid supply unit 5.

[0025] (2.2) Configuration of the liquid supply unit The liquid supply unit 5 supplies the liquid 50 for electrostatic atomization to the discharge electrode 41. The liquid supply unit 5 is realized, for example, by using a cooling device 51 shown in FIG. 3B. The cooling device 51 cools the discharge electrode 41 and generates condensed water on the discharge electrode 41 as the liquid 50 (see FIG. 2A). Specifically, the cooling device 51 includes a pair of Peltier elements 511 and a pair of heat sinks 512. The pair of Peltier elements 511 are held by the pair of heat sinks 512. The cooling device 51 cools the discharge electrode 41 by applying current to the pair of Peltier elements 511. The pair of heat sinks 512 are held by the housing 40 of the load 4, with a portion of each of the pair of heat sinks 512 being embedded in the housing 40 (described later). At least the portion of the pair of heat sinks 512 that holds the Peltier elements 511 is exposed from the housing 40.

[0026] The pair of Peltier elements 511 are mechanically and electrically connected to a base end 41b (described later) of the discharge electrode 41, for example, by soldering. The pair of Peltier elements 511 are also mechanically and electrically connected to a pair of heat sinks 512, for example, by soldering. Current is passed through the pair of Peltier elements 511 via the pair of heat sinks 512 and the discharge electrode 41. Therefore, the cooling device 51 constituting the liquid supply unit 5 cools the entire discharge electrode 41 through the base end 41b. As a result, moisture in the air condenses and adheres to the surface of the discharge electrode 41 as condensed water. This condensed water is retained in the discharge electrode 41 as liquid 50. That is, the liquid supply unit 5 is configured to cool the discharge electrode 41 and generate condensed water as liquid 50 on the surface of the discharge electrode 41. With this configuration, the liquid supply unit 5 can supply the liquid 50 (condensed water) to the discharge electrode 41 by utilizing moisture in the air, eliminating the need to supply and replenish liquid to the discharge device 10.

[0027] (2.3) Configuration of voltage application device As shown in FIG. 1, the voltage application device 1 of this embodiment includes a voltage application circuit 2 and a control circuit 3.

[0028] The voltage application circuit 2 has a drive circuit 21 and a voltage generation circuit 22. The drive circuit 21 is a circuit that drives the voltage generation circuit 22. The voltage generation circuit 22 is a circuit that receives power supply from a power supply unit 6 (input unit) and generates an application voltage V1 (see FIG. 5A) to be applied to the load 4. In this disclosure, the "application voltage" refers to the voltage that the voltage application circuit 2 applies to the load 4 to cause discharge. The power supply unit 6 is a power supply circuit that generates a DC voltage of about several volts to several tens of volts. In this embodiment, the power supply unit 6 is described as not being included in the components of the voltage application device 1, but the power supply unit 6 may be included in the components of the voltage application device 1.

[0029] The voltage application circuit 2 is, for example, an insulating DC / DC converter that boosts the input voltage (for example, 13.8 V) from the power supply unit 6 and outputs the boosted voltage as the applied voltage V1. The applied voltage V1 of the voltage application circuit 2 is applied to the load 4 (the discharge electrode 41 and the counter electrode 42).

[0030] The voltage application circuit 2 is electrically connected to the load 4. The voltage application circuit 2 applies a high voltage to the load 4. Here, the voltage application circuit 2 is configured to apply a high voltage between the discharge electrode 41 and the counter electrode 42, with the discharge electrode 41 being the negative electrode (ground) and the counter electrode 42 being the positive electrode (plus). In other words, when a high voltage is applied from the voltage application circuit 2 to the load 4, a potential difference is generated between the discharge electrode 41 and the counter electrode 42, with the counter electrode 42 side at a high potential and the discharge electrode 41 side at a low potential. The "high voltage" referred to here may be any voltage that is set to cause a discharge between the discharge electrode 41 and the counter electrode 42.

[0031] In the present disclosure, "discharge between the discharge electrode 41 and the counter electrode 42" includes discharge in which a discharge path L1 caused by partial dielectric breakdown is formed between the discharge electrode 41 and the counter electrode 42, as shown in FIG. 5A. Such a discharge in which a discharge path L1 caused by partial dielectric breakdown is formed will be referred to as "partial breakdown discharge" below. In other words, partial breakdown discharge forms a discharge path L1 caused by partial dielectric breakdown between the discharge electrode 41 and the counter electrode 42 (between the pair of electrodes). Partial breakdown discharge will be described in detail in the section "(3) Discharge form."

[0032] Furthermore, the "discharge between the discharge electrode 41 and the counter electrode 42" referred to in this disclosure includes a discharge in which a breakdown region R4 is formed between the discharge electrode 41 and the counter electrode 42, as shown in FIG. 5C. Such a discharge in which a breakdown region R4 is formed in which breakdown is caused across the entire discharge electrode 41 is referred to as a "total breakdown discharge" below. In other words, a total breakdown discharge forms a discharge path in which continuous breakdown has occurred (a discharge path in which breakdown is continuous from one electrode to the other electrode) between the discharge electrode 41 and the counter electrode 42 (between a pair of electrodes). The total breakdown discharge will be described in detail in the section "(3) Discharge Mode."

[0033] The voltage application circuit 2 of this embodiment generates intermittent discharge by periodically varying the magnitude of the applied voltage V1. The applied voltage V1 alternates between periods in which the applied voltage V1 increases to a high voltage and periods in which the applied voltage V1 decreases to a low voltage. As shown in FIGS. 2A and 2B , the periodic variation of the applied voltage V1 causes vibrations in the liquid 50. Note that the “high voltage” referred to here is any voltage set to generate a discharge in the discharge electrode 41, e.g., a voltage with a peak of approximately 7.0 kV. However, the value of the applied voltage V1 is not limited to approximately 7.0 kV and may be appropriately set depending on, for example, the shapes of the discharge electrode 41 and the counter electrode 42, the distance between the discharge electrode 41 and the counter electrode 42, etc. Furthermore, the “low voltage” is any voltage set to prevent a discharge from occurring in the discharge electrode 41, and is a voltage lower than the “high voltage” described above. Note that, hereinafter, “the magnitude of the applied voltage V1 periodically varies” may also be referred to as “the applied voltage V1 periodically varies.”

[0034] Specifically, when the applied voltage V1 is applied to the load 4, during the period when the applied voltage V1 is high, the liquid 50 held in the discharge electrode 41 is subjected to a force from the electric field and forms a conical shape known as a Taylor cone, as shown in FIG. 2A. At least a portion of the tip 411 of the discharge electrode 41 is embedded in the Taylor cone-shaped liquid 50. A discharge occurs when the electric field is concentrated at the tip (apex) of the Taylor cone. At this time, the sharper the tip of the Taylor cone, i.e., the smaller (acute) the apex angle of the cone, the smaller the electric field strength required for dielectric breakdown, making it easier for a discharge to occur.

[0035] Furthermore, during the period when the applied voltage V1 is low, the liquid 50 held by the discharge electrode 41 assumes a substantially spherical shape due to the reduced force of the electric field, as shown in FIG. 2B.

[0036] As the applied voltage V1 varies periodically, the liquid 50 held by the discharge electrode 41 is deformed alternately between the shape shown in Fig. 2A and the shape shown in Fig. 2B. As a result, the Taylor cone as described above is formed periodically, and discharge occurs intermittently in accordance with the timing at which the Taylor cone as shown in Fig. 2A is formed. Note that in Figs. 2A and 2B, the liquid 50 is indicated by dot hatching to make it easier to distinguish between the tip 411 and the liquid 50.

[0037] In the present disclosure, the discharge that occurs intermittently (discontinuously) between the discharge electrode 41 and the counter electrode 42 in response to the periodic fluctuations of the applied voltage V1 may be referred to as a "leader discharge." The leader discharge intermittently forms a discharge path (between a pair of electrodes) between the discharge electrode 41 and the counter electrode 42, and intermittently and repeatedly generates a discharge current (output current). In other words, the "leader discharge" includes a partial breakdown discharge and a full breakdown discharge that occur intermittently (discontinuously) between the discharge electrode 41 and the counter electrode 42 in response to the periodic fluctuations of the applied voltage V1. The leader discharge differs from a spark discharge that occurs instantaneously (single) between the discharge electrode 41 and the counter electrode 42, and from a glow discharge and an arc discharge that occur continuously between the discharge electrode 41 and the counter electrode 42.

[0038] The control circuit 3 controls the voltage application circuit 2. The control circuit 3 controls the magnitude of the applied voltage V1 to vary periodically during a driving period in which the voltage application device 1 is driven. The "driving period" referred to in this disclosure is a period in which the voltage application device 1 is driven to generate a discharge in the discharge electrode 41.

[0039] The control circuit 3 of this embodiment controls the voltage application circuit 2 based on the object to be monitored. The "object to be monitored" here consists of at least one of the output current and output voltage of the voltage application circuit 2. The control circuit 3 of this embodiment has a voltage control circuit 31 and a current control circuit 32.

[0040] The voltage control circuit 31 controls the drive circuit 21 of the voltage application circuit 2 based on the monitored output voltage of the voltage application circuit 2. The voltage control circuit 31 outputs a control signal Si1 to the drive circuit 21, and controls the drive circuit 21 by the control signal Si1.

[0041] The current control circuit 32 controls the drive circuit 21 of the voltage application circuit 2 based on the monitored object which is the output current of the voltage application circuit 2. The current control circuit 32 outputs a control signal Si2 to the drive circuit 21, and controls the drive circuit 21 by the control signal Si2.

[0042] Note that since there is a correlation between the output voltage (secondary side voltage) of the voltage application circuit 2 and the primary side voltage of the voltage application circuit 2, the voltage control circuit 31 may indirectly detect the output voltage of the voltage application circuit 2 from the primary side voltage of the voltage application circuit 2. Similarly, since there is a correlation between the output current (secondary side current) of the voltage application circuit 2 and the input current (primary side current) of the voltage application circuit 2, the current control circuit 32 may indirectly detect the output current of the voltage application circuit 2 from the input current of the voltage application circuit 2.

[0043] (2.4) Load configuration As shown in FIG. 3B, the load 4 of this embodiment includes a housing 40, a discharge electrode 41, and a counter electrode .

[0044] (2.4.1) Housing Configuration As shown in Fig. 3B, the housing 40 is formed in the shape of a rectangular box with an opening on the top surface (the surface holding the counter electrode 42). The housing 40 is made of an electrically insulating material such as synthetic resin. The housing 40 holds the discharge electrode 41 and the counter electrode 42. More specifically, the housing 40 holds the discharge electrode 41 and the counter electrode 42 so that the discharge electrode 41 and the counter electrode 42 face each other across a gap in the vertical direction.

[0045] (2.4.2) Discharge electrode configuration 3B, the discharge electrode 41 is a rod-shaped electrode. In this embodiment, the discharge electrode 41 is disposed on the lower side (lower surface) of the internal space of the housing 40 and protrudes upward. In other words, the longitudinal direction of the discharge electrode 41 in this embodiment is along the up-down direction.

[0046] The discharge electrode 41 has a shaft portion 41a and a base end portion 41b. The shaft portion 41a is formed in a rod shape with a circular cross section. The shaft portion 41a has the above-mentioned tip portion 411. A flat plate-shaped base end portion 41b is formed integrally and continuously with the first end in the longitudinal direction of the shaft portion 41a (the end portion opposite the tip portion 411 or the lower end).

[0047] The tip portion 411 is formed at a second end (upper end or tip) in the longitudinal direction of the shaft portion 41a. The tip portion 411 has a tapered shape in which the cross-sectional area decreases toward the tip of the shaft portion 41a. In other words, the discharge electrode 41 is a needle electrode in which the tip portion 411 is formed in a tapered shape. The term "tapered shape" as used here is not limited to a shape with a sharply pointed tip, but also includes a shape with a rounded tip as shown in FIGS. 2A and 2B.

[0048] The shape of the tip portion 411 of the discharge electrode 41 is, for example, a shape that includes a conical portion. The shape of the portion of the tip portion 411 that faces the counter electrode 42 (here, the shape of the tip or upper end of the conical portion) is, for example, an R-shape (rounded shape). In the present disclosure, the term "R-shape" may include a surface of a certain member that is rounded (has a rounded shape). The tip surface of the tip portion 411 of this embodiment includes a curved surface that is convex upward. The tip surface of the discharge electrode 41 of this embodiment has a cross-sectional shape that includes the central axis of the discharge electrode 41 and is formed into an arc that continues continuously from the side surface of the tip portion 411, and does not include any corners. In other words, the tip surface of the discharge electrode 41 is a curved surface as a whole.

[0049] As an example, the radius of curvature r2 (see FIG. 4C) of the tip surface of the discharge electrode 41 is preferably 0.2 mm or more. In this way, by having the tip 411 of the discharge electrode 41 have an R-shape, it is possible to reduce excessive concentration of the electric field at the tip 411 of the discharge electrode 41 compared to when the tip 411 of the discharge electrode 41 is sharp, and partial breakdown discharge is more likely to occur.

[0050] (2.4.3) Counter electrode configuration 3B, the counter electrode 42 is disposed on the upper side (upper surface) of the internal space of the housing 40. The counter electrode 42 is disposed so as to face the tip portion 411 of the discharge electrode 41 with a gap therebetween in the vertical direction. In other words, the counter electrode 42 is spatially separated from the discharge electrode 41, and is electrically insulated from the discharge electrode 41. The counter electrode 42 has a discharge portion 420, a support portion 422, a recessed portion 421, a bottom portion 4211, and a cylindrical portion 423.

[0051] 3A, the recess 421, the bottom 4211, and the cylindrical portion 423 are formed in a circular ring shape with the tip portion 411 of the discharge electrode 41 as the center when the load 4 is viewed from above (top view). That is, the recess 421, the bottom 4211, and the cylindrical portion 423 are formed in a concentric circular ring shape when the load 4 is viewed from above. When the load 4 is viewed from above, the cylindrical portion 423, the bottom 4211, the recess 421, and the support portion 422 are arranged in this order from the inside with the tip portion 411 of the discharge electrode 41 as the center.

[0052] Support portion 422 is held by housing 40. As shown in Fig. 3B, support portion 422 is formed in the shape of a flat plate whose thickness direction is aligned with the up-down direction.

[0053] The recess 421 is recessed from the support portion 422 toward the discharge electrode 41. That is, the recess 421 is formed so as to be recessed downward from the support portion 422. In other words, the recess 421 protrudes downward from the support portion 422. As shown in FIG. 3A, the recess 421 has a circular shape when viewed from above the load 4. The recess 421 is also cylindrical in shape, with a diameter that decreases as it recesses downward (goes downward).

[0054] In a top view of the load 4, the bottom 4211 protrudes from the lower end of the recess 421 toward the tip 411 of the discharge electrode 41. The bottom 4211 is formed in a flat, annular shape with its thickness extending in the vertical direction.

[0055] As shown in FIG. 3B , the tubular portion 423 protrudes upward from the inner circumferential end of the bottom portion 4211. That is, the tubular portion 423 extends in the protruding direction of the discharge electrode 41. The tubular portion 423 of this embodiment has a cylindrical shape whose diameter decreases as it extends upward. In other words, the tubular portion 423 protrudes in a direction away from the discharge electrode 41, and the outer shape of the tubular portion 423 is a truncated cone. The tubular portion 423 is formed in a dome shape above the discharge electrode 41 so as to cover the discharge electrode 41. The tubular portion 423 has a first opening 4231 and a second opening 4232.

[0056] The first opening 4231 and the second opening 4232 are aligned in the vertical direction. In other words, the first opening 4231 and the second opening 4232 are aligned in the protruding direction (upward) of the discharge electrode 41. The first opening 4231 is disposed below the second opening 4232. That is, the first opening 4231 is disposed closer to the discharge electrode 41 than the second opening 4232. The first opening 4231 and the second opening 4232 are circular openings centered on the tip end 411 of the discharge electrode 41 when viewed from above the load 4. As shown in FIG. 4B , in this embodiment, the opening diameter D3 of the second opening 4232 is smaller than the opening diameter D4 of the first opening 4231.

[0057] As shown in FIG. 4A , the cylindrical portion 423 of this embodiment further includes an edge portion 424. The edge portion 424 is an edge portion of the first opening 4231 and is continuous with the bottom portion 4211. The edge portion 424 includes a line L2 along which the distance between the tip portion 411 of the discharge electrode 41 and the counter electrode 42 is shortest. That is, the edge portion 424 is a portion where electric field concentration is likely to occur. Note that the line L2 in this embodiment is an imaginary line. In a top view of the load 4, the line L2 is an annular line centered on the tip portion 411 of the discharge electrode 41, and the edge portion 424 is an annular line including the line L2. A distance D1 between the annular line L2 and the tip portion 411 of the discharge electrode 41 is constant along the entire circumference of the line L2. The line L2 in this embodiment forms an imaginary right circular cone with the tip portion 411 of the discharge electrode 41 as its apex and a generatrix length equal to the distance D1. The distance D1 between the line L2 and the tip 411 of the discharge electrode 41 is smaller than the distance D2 between the edge of the second opening 4232 and the tip 411 of the discharge electrode 41.

[0058] The edge portion 424 of this embodiment has a curved surface. In other words, the edge portion 424 has a rounded shape that convexly extends toward the tip portion 411 of the discharge electrode 41, as shown in Fig. 4B. More specifically, the cross section of the edge portion 424 is formed in a semicircular arc shape that continues continuously from the bottom portion 4211 and does not include any corners. In other words, the entire surface of the edge portion 424 of the cylindrical portion 423 is a curved surface.

[0059] The radius of curvature r1 of the edge portion 424 is preferably equal to or greater than half the radius of curvature r2 (see FIG. 4C ) of the tip portion 411 of the discharge electrode 41. In other words, it is preferable to satisfy the relational expression "r1≧r2×½". As an example, if the radius of curvature r2 of the tip portion 411 of the discharge electrode 41 is 0.6 mm, it is preferable that the radius of curvature r1 of the edge portion 424 is 0.3 mm or greater. The "radius of curvature" here refers to the minimum value, that is, the radius of curvature of the portion where the curvature is maximum, for both the edge portion 424 and the tip portion 411 of the discharge electrode 41. However, because the scales are different between FIG. 4B and FIG. 4C , "r1" in FIG. 4B and "r2" in FIG. 4C do not necessarily represent the ratio between "r1" and "r2".

[0060] Furthermore, it is more preferable that the radius of curvature r1 of the edge 424 is larger than the radius of curvature r2 of the tip 411 of the discharge electrode 41. In this embodiment, the radius of curvature r1 of the edge 424 is larger than the radius of curvature r2 of the tip 411 of the discharge electrode 41.

[0061] 4A is a portion where discharge occurs between the discharge portion 420 and the tip portion 411 of the discharge electrode 41. The discharge portion 420 extends linearly along the circumference of a circle centered on the tip portion 411 of the discharge electrode 41. The discharge portion 420 of this embodiment is formed on the edge portion 424. In other words, the discharge portion 420 is formed on the edge of the first opening 4231.

[0062] The discharge part 420 of this embodiment is a part (strip-shaped surface) including the line L2 where the distance between the tip 411 of the discharge electrode 41 and the counter electrode 42 is the shortest. Since the discharge part 420 is a part including the line L2, discharge is more likely to occur between the discharge part 420 and the tip 411 of the discharge electrode 41, and the amount of active ingredient produced can be further increased.

[0063] Furthermore, the discharge unit 420 of this embodiment is formed in a circular ring shape along the circumference of a circle centered on the tip 411 of the discharge electrode 41. More specifically, the discharge unit 420 of this embodiment is formed in a circular ring shape including the line L2. The dotted lines in FIGS. 4A and 4B indicate the discharge path L1 between the discharge unit 420 and the tip 411 of the discharge electrode 41. The discharge path L1 of this embodiment is formed along the generatrix of an imaginary right circular cone formed by the tip 411 of the discharge electrode 41 and the discharge unit 420. In other words, the discharge path L1 is formed along the side surface of the cone formed by the tip 411 of the discharge electrode 41 and the discharge unit 420. In the present disclosure, a discharge occurring in the shape of a cone side surface with the tip 411 of the discharge electrode 41 as its apex is referred to as a "round discharge." In other words, the round discharge forms a discharge path that spreads out in the shape of a cone side surface connecting the discharge electrode 41 and the counter electrode 42 (between the pair of electrodes).

[0064] Furthermore, since the discharge portion 420 of this embodiment is formed on the edge portion 424, the discharge portion 420 has a curved surface. The curved surface of the discharge portion 420 can prevent excessive concentration of the electric field. By preventing excessive concentration of the electric field, it is possible to prevent the discharge form from progressing and the amount of active ingredient produced from decreasing.

[0065] Furthermore, the radius of curvature r1 of the discharge part 420 of this embodiment is larger than the radius of curvature r2 of the tip 411 of the discharge electrode 41. In other words, the radius of curvature r1 of the curved surface of the discharge part 420 is larger than the radius of curvature r2 of the tip 411 of the discharge electrode 41. By making the radius of curvature r1 of the discharge part 420 larger than the radius of curvature r2 of the tip 411 of the discharge electrode 41, it is possible to further prevent the electric field from concentrating excessively, making it easier to generate partial breakdown discharges.

[0066] Furthermore, the active ingredient generated around the edge (edge ​​424) of first opening 4231 by the discharge passes through the internal space of tubular portion 423 and is released from second opening 4232. That is, tubular portion 423 of this embodiment serves as a release path for the active ingredient. By using tubular portion 423 as a release path for the active ingredient, the active ingredient can be released efficiently.

[0067] Furthermore, in this embodiment, opening diameter D3 of second opening 4232 is smaller than opening diameter D4 of first opening 4231. Since opening diameter D3 is smaller than opening diameter D4, tubular portion 423 functions as a nozzle that releases the active ingredient. Therefore, the flow rate of the active ingredient released from second opening 4232 through the internal space of tubular portion 423 increases, and the active ingredient can be released more efficiently.

[0068] (3) Discharge form The following describes in detail the form of discharge that occurs when an applied voltage V1 is applied between the discharge electrode 41 and the counter electrode 42, with reference to FIGS. 5A to 5C. FIGS. 5A to 5C are conceptual diagrams for explaining the form of discharge, and each diagram schematically illustrates the discharge electrode 41 and the counter electrode 42. In addition, in the discharge device 10 according to this embodiment, a liquid 50 is actually held in the discharge electrode 41, and a discharge occurs between this liquid 50 and the counter electrode 42; however, the liquid 50 is not shown in FIGS. 5A to 5C. In addition, the following description will be given assuming that there is no liquid 50 at the tip 411 of the discharge electrode 41. However, if the liquid 50 is present, the "tip 411 of the discharge electrode 41" may be replaced with the "liquid 50 held in the discharge electrode 41" when describing the location where the discharge occurs.

[0069] First, the partial breakdown discharge employed in the discharge device 10 according to this embodiment will be described with reference to FIG. 5A. The discharge device 10 first generates a localized corona discharge at the tip 411 of the discharge electrode 41. In this embodiment, the discharge electrode 41 is on the negative (ground) side, so the corona discharge generated at the tip 411 of the discharge electrode 41 is a negative corona. The discharge device 10 develops the corona discharge generated at the tip 411 of the discharge electrode 41 into a high-energy discharge. This high-energy discharge forms a discharge path L1 with partial dielectric breakdown between the discharge electrode 41 and the counter electrode 42.

[0070] Furthermore, partial breakdown discharge is a type of leader discharge. That is, partial breakdown discharge involves partial breakdown between a pair of electrodes (the discharge electrode 41 and the counter electrode 42). However, the breakdown does not occur continuously, but rather occurs intermittently. Therefore, the discharge current occurring between the pair of electrodes also occurs intermittently. That is, if the power supply (voltage application circuit 2) does not have the current capacity necessary to maintain the discharge path L1, the voltage applied between the pair of electrodes decreases as soon as the corona discharge progresses to partial breakdown discharge, the discharge path L1 is interrupted, and the discharge stops. The "current capacity" here refers to the capacity of the current that can be discharged per unit time. The discharge current flows intermittently as a result of this repeated occurrence and stop of discharge. In this way, partial breakdown discharge differs from spark discharge, in that it alternates between high and low discharge energy states, which causes instantaneous (single) breakdown. Furthermore, partial breakdown discharge differs from glow discharge and arc discharge in that breakdown occurs continuously (that is, discharge current occurs continuously) in that a state of high discharge energy and a state of low discharge energy are alternately repeated.

[0071] More specifically, the voltage application device 1 applies an applied voltage V1 between a discharge electrode 41 and a counter electrode 42, which are arranged to face each other with a gap between them, thereby generating a discharge between the discharge electrode 41 and the counter electrode 42. When a discharge occurs, a discharge path L1 is formed between the discharge electrode 41 and the counter electrode 42, where a partial breakdown occurs. As shown in FIG. 5A , the discharge path L1 formed at this time includes a first breakdown region R1 generated around the discharge electrode 41 and a second breakdown region R2 generated around the counter electrode 42.

[0072] That is, a discharge path L1 in which insulation breakdown occurs partially (locally) rather than entirely between the discharge electrode 41 and the counter electrode 42. In this way, in a partial breakdown discharge, the discharge path L1 formed between the discharge electrode 41 and the counter electrode 42 does not result in a total breakdown, but is a path in which insulation breakdown occurs partially.

[0073] As described above, by appropriately setting the shape (R-shape) of the tip 411 of the discharge electrode 41 and the edge 424 of the tubular portion 423 so as to moderately reduce the concentration of the electric field, partial breakdown discharge can be easily achieved. In other words, by appropriately setting the shape of the tip 411 and the curvature radius r1 of the edge 424, along with other factors such as the length of the discharge electrode 41 and the applied voltage V1, so as to reduce the concentration of the electric field, the concentration of the electric field can be moderately reduced. As a result, when a voltage is applied between the discharge electrode 41 and the counter electrode 42, a complete breakdown like a complete breakdown discharge does not occur, and only a partial breakdown occurs. As a result, partial breakdown discharge can be achieved.

[0074] Here, the discharge path L1 includes a first breakdown region R1 generated around the discharge electrode 41 and a second breakdown region R2 generated around the counter electrode 42. In other words, the first breakdown region R1 is a region of breakdown around the discharge electrode 41, and the second breakdown region R2 is a region of breakdown around the counter electrode 42. Here, when a liquid 50 is held in the discharge electrode 41 and an applied voltage V1 is applied between the liquid 50 and the counter electrode 42, the first breakdown region R1 is generated around the discharge electrode 41, particularly around the liquid 50.

[0075] The first breakdown region R1 and the second breakdown region R2 are spaced apart so as not to come into contact with each other. In other words, the discharge path L1 includes a region (insulating region) where no breakdown has occurred at least between the first breakdown region R1 and the second breakdown region R2. Therefore, in a partial breakdown discharge, a discharge current flows through the discharge path L1 in the space between the discharge electrode 41 and the counter electrode 42, with only partial breakdown occurring rather than a complete breakdown. In other words, even in the discharge path L1 where partial breakdown has occurred, in other words, even in the discharge path L1 where no breakdown has occurred in any part, a discharge current flows through the discharge path L1 between the discharge electrode 41 and the counter electrode 42, and a discharge occurs.

[0076] Here, the second breakdown region R2 basically occurs around a portion of the counter electrode 42 where the distance (spatial distance) to the discharge electrode 41 is shortest. In this embodiment, the counter electrode 42 has a curved edge 424 (discharge portion 420) formed on the cylindrical portion 423 where the distance D1 (see FIG. 4A) to the discharge electrode 41 is shortest, and therefore the second breakdown region R2 is generated around the edge 424. In other words, the counter electrode 42 shown in FIG. 5A actually corresponds to the edge 424 of the cylindrical portion 423.

[0077] 4A, the discharge portion 420 is a portion that includes an annular line L2 along which the distance between the tip 411 of the discharge electrode 41 and the counter electrode 42 is shortest. Therefore, the second breakdown region R2 is generated around this annular line L2. Here, the region of the discharge portion 420 where the second breakdown region R2 is generated is not limited to a specific region, but is determined randomly with the annular line L2 as the center.

[0078] In a partial breakdown discharge, as shown in FIG. 5A, a first breakdown region R1 around the discharge electrode 41 extends from the discharge electrode 41 toward the opposing counter electrode 42. A second breakdown region R2 around the opposing electrode 42 extends from the opposing counter electrode 42 toward the opposing discharge electrode 41. In other words, the first breakdown region R1 and the second breakdown region R2 extend from the discharge electrode 41 and the opposing electrode 42, respectively, in directions approaching each other. Therefore, each of the first breakdown region R1 and the second breakdown region R2 has a length along the discharge path L1. In this way, in a partial breakdown discharge, the regions where insulation has partially broken down (each of the first breakdown region R1 and the second breakdown region R2) have a shape that extends elongated in a specific direction.

[0079] In partial breakdown discharge, radicals are generated with greater energy than in corona discharge (see Figure 5B), and the amount of radicals generated is about 2 to 10 times greater than in corona discharge. The radicals generated in this way are the basis for a variety of useful effects, including sterilization, deodorization, moisturizing, freshness preservation, and virus inactivation. When radicals are generated by partial breakdown discharge, ozone is also generated. However, while partial breakdown discharge generates about 2 to 10 times more radicals than corona discharge, the amount of ozone generated is kept at the same level as corona discharge.

[0080] Next, corona discharge will be described with reference to FIG. 5B.

[0081] Generally, when energy is applied between a pair of electrodes to generate a discharge, the discharge form progresses from corona discharge to spark discharge, glow discharge, and arc discharge depending on the amount of energy applied.

[0082] Spark discharge, glow discharge, and arc discharge are discharges that involve dielectric breakdown between a pair of electrodes. Spark discharge is a discharge in which a discharge path is formed instantaneously (single-shot). In glow discharge and arc discharge, the discharge path formed by dielectric breakdown is maintained while energy is being input between the pair of electrodes, and a discharge current is continuously generated between the pair of electrodes. In contrast, corona discharge, as shown in FIG. 5B , is a discharge that occurs locally at one electrode (the discharge electrode 41) and does not involve dielectric breakdown between the pair of electrodes (the discharge electrode 41 and the counter electrode 42). In other words, when a voltage V1 is applied between the discharge electrode 41 and the counter electrode 42, a localized corona discharge occurs at the tip 411 of the discharge electrode 41. Here, because the discharge electrode 41 is the negative (ground) electrode, the corona discharge generated at the tip 411 of the discharge electrode 41 is a negative corona. At this time, a dielectric breakdown region R3, where dielectric breakdown has occurred locally, may occur around the tip 411 of the discharge electrode 41. This breakdown region R3 does not have a shape that extends long in a specific direction like the first breakdown region R1 and the second breakdown region R2 in partial breakdown discharge, but has a point-like (or spherical) shape.

[0083] Here, if the current capacity that can be discharged per unit time from the power supply (voltage application circuit 2) between the pair of electrodes is sufficiently large, the discharge path once formed will be maintained without interruption, and as described above, the discharge will progress from corona discharge and spark discharge to glow discharge and arc discharge.

[0084] Next, a complete breakdown discharge will be described with reference to FIG. 5C.

[0085] As shown in Fig. 5C, a total breakdown discharge is a discharge form in which a phenomenon in which a corona discharge progresses to a total breakdown between a pair of electrodes is repeated intermittently. That is, in a total breakdown discharge, a discharge path in which dielectric breakdown occurs entirely between the discharge electrode 41 and the counter electrode 42 is generated between the discharge electrode 41 and the counter electrode 42. At this time, a breakdown region R4 in which dielectric breakdown occurs entirely may be generated between the tip 411 of the discharge electrode 41 and the counter electrode 42 (discharge portion 420). Unlike the first breakdown region R1 and the second breakdown region R2 in a partial breakdown discharge, this breakdown region R4 does not occur partially, but rather occurs so as to continuously connect the tip 411 of the discharge electrode 41 and the counter electrode 42.

[0086] Furthermore, a total-breakdown discharge is a type of leader discharge. That is, a total-breakdown discharge involves dielectric breakdown (total breakdown) between a pair of electrodes (the discharge electrode 41 and the counter electrode 42). However, the dielectric breakdown does not occur continuously, but rather occurs intermittently. Therefore, the discharge current generated between the pair of electrodes (the discharge electrode 41 and the counter electrode 42) also occurs intermittently. That is, as described above, in cases such as when the power supply (the voltage application circuit 2) does not have the current capacity necessary to maintain the discharge path L1, the voltage applied between the pair of electrodes decreases as soon as the corona discharge progresses to total breakdown, the discharge path L1 is interrupted, and the discharge stops. Such repeated occurrences and stops of discharge result in an intermittent flow of the discharge current. Thus, a total-breakdown discharge differs from a spark discharge, in that it alternates between a state of high discharge energy and a state of low discharge energy, in that it occurs instantaneously (single). Furthermore, a complete breakdown discharge differs from a glow discharge and an arc discharge in that breakdown occurs continuously (that is, discharge current occurs continuously) in that a state of high discharge energy and a state of low discharge energy are repeated.

[0087] In a complete breakdown discharge, radicals are generated with greater energy than in a partial breakdown discharge, as in a corona discharge, and a quantity of radicals is generated that is about 2 to 10 times greater than in a corona discharge. However, the energy of a complete breakdown discharge is even greater than that of a partial breakdown discharge. Therefore, even if a large amount of radicals is generated due to the disappearance of ozone and an increase in radicals when the energy level is "medium," some of the radicals may disappear when the energy level becomes "high" in the subsequent reaction pathway. In other words, in a complete breakdown discharge, the energy involved in the discharge is too high, so some of the active components such as generated radicals (air ions, radicals, charged minute particle liquid containing these, etc.) may disappear, leading to a decrease in the production efficiency of the active components.

[0088] Here, the partial breakdown discharge (see FIG. 5A) generated by the discharge device 10 of this embodiment can suppress the loss of radicals due to excessive energy, even compared to the full-path breakdown discharge (see FIG. 5C), and can improve the radical generation efficiency compared to the full-path breakdown discharge. That is, in the full-path breakdown discharge, the energy involved in the discharge is too high, so some of the generated radicals may disappear, leading to a decrease in the generation efficiency of the active ingredient. In contrast, the energy involved in the partial breakdown discharge is kept low compared to the full-path breakdown discharge, so the amount of radical loss due to exposure to excessive energy is reduced, and the radical generation efficiency can be improved. As a result, the discharge device 10 of this embodiment, which employs partial breakdown discharge, can improve the generation efficiency of active ingredients (air ions, radicals, charged minute particle liquid containing these, etc.) compared to corona discharge and full-path breakdown discharge.

[0089] Furthermore, in a partial breakdown discharge, the concentration of the electric field is relaxed compared to a complete breakdown discharge. Therefore, in a complete breakdown discharge, a large discharge current flows instantaneously between the discharge electrode 41 and the counter electrode 42 through the discharge path where complete breakdown has occurred, and the electrical resistance at that time is very small. In contrast, in a partial breakdown discharge, the concentration of the electric field is relaxed, so that when a discharge path L1 where partial breakdown has occurred is formed, the maximum value of the current that flows instantaneously between the discharge electrode 41 and the counter electrode 42 is kept smaller than in a complete breakdown discharge. As a result, in a partial breakdown discharge, the generation of nitride oxides (NOx) is suppressed compared to a complete breakdown discharge, and electrical noise is also kept small.

[0090] The discharge generated by the discharge device 10 of this embodiment is a round discharge, in which the discharge path L1 is formed along the side of a cone formed by the tip 411 of the discharge electrode 41 and the discharge portion 420. By making the discharge portion 420 annular, the discharge portion 420 can be maximized in length along the circumference, thereby widening the discharge path L1 between the discharge electrode 41 and the discharge portion 420, with the tip 411 of the discharge electrode 41 as its apex. In other words, the space in which the discharge occurs is expanded. The wider discharge path L1 further increases the amount of active ingredients produced. The discharge generated by the discharge device 10 of this embodiment is a "round leader discharge," which is both a leader discharge and a round discharge. The round leader discharge intermittently forms a discharge path that extends along the side of a cone connecting the discharge electrode 41 and the counter electrode 42 (between the pair of electrodes), and intermittently generates a discharge current (output current). The round leader discharge has the advantages of both leader discharge and round discharge. In the round leader discharge, the discharge path L1 is widened to a conical side, which prevents the electric field concentration from growing rapidly and progressing to a complete breakdown discharge, and it is possible to spatially expand the partial breakdown discharge. In other words, the round leader discharge can further increase the amount of active ingredients produced compared to the conventional leader discharge.

[0091] (4) Variations The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above embodiment are listed below. The modifications described below can be applied in appropriate combinations.

[0092] (4.1) First Modification As shown in FIG. 6A, the shape of the counter electrode 42 of the load 4 of the first modified example differs from that of the above embodiment. FIG. 6A is a cross-sectional view of a main portion of the load 4, including the counter electrode 42. In addition, in the load 4, a liquid 50 is actually held in the discharge electrode 41, and a discharge occurs between this liquid 50 and the counter electrode 42, but FIG. 6A does not illustrate the liquid 50. In the following description, it is assumed that there is no liquid 50 at the tip 411 of the discharge electrode 41. However, if there is liquid 50, the "tip 411 of the discharge electrode 41" may be replaced with "liquid 50 held in the discharge electrode 41" when referring to the location where the discharge occurs, etc.

[0093] The counter electrode 42 of the first modified example has a cylindrical portion 423a instead of the cylindrical portion 423 of the above embodiment. The cylindrical portion 423a has a step portion 4233. In other words, the cylindrical portion 423a has at least one step portion 4233. The step portion 4233 is formed on the inner periphery of the cylindrical portion 423a between the first opening 4231 and the second opening 4232. The step portion 4233 has an annular shape. More specifically, the step portion 4233 has an annular shape centered on the tip portion 411 of the discharge electrode 41 when the load 4 is viewed from above.

[0094] An inner diameter D5 of the step portion 4233 is smaller than the opening diameter D4 of the first opening 4231 (see FIG. 4B) and larger than the opening diameter D3 of the second opening 4232 (see FIG. 4B). That is, the step portion 4233 is a portion where the inner diameter of the tubular portion 423a becomes smaller in a plan view (bottom view) of the load 4 seen from below. The inner diameter of the tubular portion 423a from the first opening 4231 to the step portion 4233 is equal to the opening diameter D4 of the first opening 4231. The inner diameter of the tubular portion 423a from the step portion 4233 to the lower end of the second opening 4232 is equal to the inner diameter D5 of the step portion 4233.

[0095] The step portion 4233 of this modified example has a curved surface. In other words, the step portion 4233 has a rounded shape that convexly extends toward the tip portion 411 of the discharge electrode 41. The radius of curvature r3 of the step portion 4233 is preferably equal to or greater than half the radius of curvature r2 (see FIG. 4C ) of the tip portion 411 of the discharge electrode 41. The radius of curvature r3 of the step portion 4233 of this modified example is greater than the radius of curvature r2 of the tip portion 411 of the discharge electrode 41.

[0096] 6A indicates the range where the distance between the tip 411 of the discharge electrode 41 and the counter electrode 42 is shortest. In this modified example, the distance D1a between the step portion 4233 and the tip 411 of the discharge electrode 41 is equal to the distance D1 between the line L2 of the edge portion 424 (see FIG. 4A) and the tip 411 of the discharge electrode 41. In other words, the distance D1a between the step portion 4233 and the tip 411 of the discharge electrode 41 is the shortest distance between the discharge electrode 41 and the counter electrode 42.

[0097] The counter electrode 42 of this modified example has a plurality of (two in the example of FIG. 6A ) discharge portions 420. One of the two discharge portions 420 is formed on the edge portion 424 of the first opening 4231, as in the above embodiment. That is, the discharge portion 420 formed on the edge portion 424 is one of the plurality of discharge portions 420. The other of the two discharge portions 420 is formed on the step portion 4233.

[0098] The discharge portion 420 formed in the step portion 4233 also generates a round leader discharge, similar to the discharge portion 420 formed in the edge portion 424. By having a plurality of discharge portions 420 on the counter electrode 42, it is possible to prevent the electric field concentration in each discharge portion 420 from becoming excessively high.

[0099] As will be described later in a second modified example, the cylindrical portion 423a may have two or more (plural) step portions, and the discharge portion 420 is formed on each of the two or more step portions.

[0100] (4.2) Second Modification As shown in Fig. 6B, the counter electrode 42 of the second modified example has a cylindrical portion 423b instead of the cylindrical portion 423a of the above embodiment. The cylindrical portion 423b has a plurality of (two in the example of Fig. 6B) step portions 4234, 4235. The step portion 4234 is disposed below the step portion 4235. In other words, the step portion 4234 is disposed closer to the first opening 4231 than the step portion 4235.

[0101] The inner diameters of the multiple step portions 4234, 4235 are smaller than the opening diameter D4 of the first opening 4231 (see FIG. 4B) and larger than the opening diameter D3 of the second opening 4232 (see FIG. 4B). The inner diameter of the step portion 4234 is larger than the inner diameter of the step portion 4235 arranged above the step portion 4234. That is, among the multiple step portions arranged in the vertical direction, the inner diameter of the step portion arranged on the lower side is larger than the inner diameter of the step portion arranged on the upper side. The two step portions 4234, 4235 are portions where the inner diameter of the tubular portion 423b becomes smaller when viewed from the bottom of the load 4. The other shapes of the two step portions 4234, 4235 are similar to those of the step portion 4233 described in the first modified example.

[0102] 6B indicates the range where the distance between the tip 411 of the discharge electrode 41 and the counter electrode 42 is shortest. In this modified example, the distance D1b between the step portion 4234 and the tip 411 of the discharge electrode 41 is equal to the distance D1 between the line L2 of the edge portion 424 (see FIG. 4A) and the tip 411 of the discharge electrode 41. In this modified example, the distance D1c between the step portion 4235 and the tip 411 of the discharge electrode 41 is equal to the distance D1 between the line L2 of the edge portion 424 and the tip 411 of the discharge electrode 41. In other words, the distance D1b between the step portion 4234 and the tip 411 of the discharge electrode 41 and the distance D1c between the step portion 4235 and the tip 411 of the discharge electrode 41 are the shortest distances between the discharge electrode 41 and the counter electrode 42.

[0103] The counter electrode 42 of this modified example has a plurality of (three in the example of FIG. 6B) discharge portions 420. One of the three discharge portions 420 is formed on the edge portion 424 of the first opening 4231, as in the above embodiment. One of the three discharge portions 420 is formed on the step portion 4234. One of the three discharge portions 420 is formed on the step portion 4235.

[0104] The discharge portions 420 formed on the two step portions 4234, 4235 also generate round leader discharges, similar to the discharge portion 420 formed on the edge portion 424. By having a plurality of discharge portions 420 on the counter electrode 42, it is possible to prevent the electric field concentration in each discharge portion 420 from becoming excessively high.

[0105] 6A and 6B, the shapes of the counter electrode 42 and the discharge electrode 41 can be changed as appropriate. For example, the cylindrical portion 423b may have three or more step portions. Furthermore, it is not essential that the distance from the tip 411 of the discharge electrode 41 to the step portions be the shortest distance (distance D1). The distance from the tip 411 of the discharge electrode 41 to the step portions may be set as appropriate depending on the radius of curvature r1 of the edge portion 424 and the radius of curvature of each of the multiple step portions, as well as the form of discharge generated near the edge portion 424 and the step portions.

[0106] (4.3) Other Modifications The discharge device 10 may be configured without the liquid supply unit 5 for generating charged minute particle liquid. In this case, the discharge device 10 generates air ions by partial breakdown discharge occurring between the discharge electrode 41 and the counter electrode 42. That is, the discharge device 10 may be an ion generating device or the like in addition to an electrostatic atomizing device.

[0107] Furthermore, the liquid supply unit 5 is not limited to a configuration that cools the discharge electrode 41 to generate condensed water on the discharge electrode 41 as in the above embodiment. The liquid supply unit 5 may be configured to supply the liquid 50 from a tank to the discharge electrode 41 using, for example, capillary action or a supply mechanism such as a pump. Furthermore, the liquid 50 is not limited to water (including condensed water) and may be a liquid other than water.

[0108] Furthermore, the voltage application circuit 2 may be configured to apply a high voltage between the discharge electrode 41 and the counter electrode 42, with the discharge electrode 41 as the positive electrode (plus) and the counter electrode 42 as the negative electrode (ground). Furthermore, since it is sufficient to generate a potential difference (voltage) between the discharge electrode 41 and the counter electrode 42, the voltage application circuit 2 may apply a negative voltage to the load 4 by grounding the electrode on the higher potential side (positive electrode) and setting the electrode on the lower potential side (negative electrode) to a negative potential. In other words, the voltage application circuit 2 may ground the discharge electrode 41 and set the counter electrode 42 to a negative potential, or alternatively, may set the discharge electrode 41 to a negative potential and set the counter electrode 42 to the ground.

[0109] The voltage application device 1 may also include a limiting resistor between the voltage application circuit 2 and the discharge electrode 41 or the counter electrode 42 of the load 4. The limiting resistor is a resistor for limiting the peak value of the discharge current that flows after dielectric breakdown in a partial breakdown discharge. The limiting resistor is electrically connected, for example, between the voltage application circuit 2 and the discharge electrode 41 or between the voltage application circuit 2 and the counter electrode 42.

[0110] The voltage application circuit 2 may be a self-excited converter or a separately excited converter. The voltage generation circuit 22 may be realized by a transformer having a piezoelectric element (piezoelectric transformer).

[0111] Furthermore, the discharge mode employed by the discharge device 10 is not limited to the mode described in the above embodiment. For example, the discharge device 10 may employ, as one mode of round discharge, a discharge mode in which a phenomenon in which a corona discharge progresses to a dielectric breakdown between a pair of electrodes is intermittently repeated, i.e., a "total breakdown discharge." In this case, in the discharge device 10, when a corona discharge progresses to a dielectric breakdown between the pair of electrodes, a relatively large discharge current flows instantaneously, and immediately thereafter, the applied voltage drops, cutting off the discharge current, and then the applied voltage rises again, leading to dielectric breakdown. This phenomenon is repeated.

[0112] Furthermore, each of the leader discharge, the round discharge, and the round leader discharge may be either a partial breakdown discharge or a full breakdown discharge.

[0113] The discharge device 10 may also employ spark discharge, arc discharge, or glow discharge, which are developed from corona discharge, as a form of round discharge. As with round leader discharge, the widening of the discharge path increases the amount of effective ingredients produced by the discharge.

[0114] Furthermore, the shape of counter electrode 42 is not limited to the uneven shape shown in Fig. 3B. That is, counter electrode 42 does not have to have recessed portion 421, cylindrical portion 423, etc. For example, counter electrode 42 may be formed in a flat plate shape with its thickness direction aligned with the vertical direction. Counter electrode 42 is only required to have at least discharge portion 420.

[0115] Furthermore, the shape of the discharge part 420 is not limited to a circular ring shape. The shape of the discharge part 420 may be any shape that extends linearly along the circumference of a circle centered on the tip part 411 of the discharge electrode 41. For example, the shape of the discharge part 420 may be a circular ring with at least a portion missing.

[0116] Furthermore, functions similar to those of the voltage application device 1 according to the above embodiment may be embodied in a control method for the voltage application circuit 2, a computer program, a recording medium on which a computer program is recorded, etc. In other words, functions corresponding to the control circuit 3 may be embodied in a control method for the voltage application circuit 2, a computer program, a recording medium on which a computer program is recorded, etc.

[0117] (summary) As described above, the discharge device (10) according to the first aspect includes a discharge electrode (41) and a counter electrode (42). The discharge electrode (41) has a tip portion (411). The counter electrode (42) is disposed to face the tip portion (411) of the discharge electrode (41) across a gap. The discharge device (10) generates a discharge by applying a voltage between the discharge electrode (41) and the counter electrode (42). The discharge electrode (41) protrudes (upward) toward the counter electrode (42). The counter electrode (42) has a discharge portion (420) at which a discharge occurs between the discharge electrode (41) and the tip portion (411). The discharge portion (420) extends linearly along a circumference (line L2) centered on the tip portion (411) of the discharge electrode (41).

[0118] According to this aspect, the discharge portion (420) extends linearly along the circumference (line L2) of a circle centered on the tip portion (411) of the discharge electrode (41), and therefore the discharge path (L1) having an apex at the tip portion (411) of the discharge electrode (41) is wider than in a conventional discharge device (10) having a needle-shaped discharge portion (420). The wider discharge path (L1) can increase the amount of active ingredients (including radicals) produced by discharge.

[0119] In the discharge device (10) according to the second aspect, in the first aspect, the discharge part (420) is a part including a line (L2) along which the distance (D1) between the tip (411) of the discharge electrode (41) and the counter electrode (42) is shortest.

[0120] According to this aspect, the discharge portion (420) is a portion that includes the line (L2) at which the distance (D1) from the tip end (411) of the discharge electrode (41) is shortest. Therefore, discharge is more likely to occur between the discharge portion (420) and the tip end (411) of the discharge electrode (41), and the amount of the active ingredient produced can be further increased.

[0121] In the discharge device (10) according to the third aspect, in the first or second aspect, the discharge part (420) is formed in an annular shape along the circumference of a circle centered on the tip end (411) of the discharge electrode (41).

[0122] According to this embodiment, the annular shape of the discharge portion (420) maximizes the circumferential length of the discharge portion (420), thereby widening the discharge path (L1) whose apex is the tip end (411) of the discharge electrode (41).The wider discharge path (L1) can further increase the amount of active ingredient produced.

[0123] In the discharge device (10) according to a fourth aspect, in any one of the first to third aspects, the discharge part (420) has a curved surface.

[0124] According to this aspect, the curved surface of the discharge portion (420) can prevent excessive concentration of the electric field. By preventing excessive concentration of the electric field, it is possible to prevent the discharge form from progressing and the amount of the active ingredient produced from decreasing.

[0125] In the discharge device (10) according to the fifth aspect, the radius of curvature (r1) of the curved surface of the discharge part (420) in the fourth aspect is larger than the radius of curvature (r2) of the tip (411) of the discharge electrode (41).

[0126] According to this embodiment, by making the radius of curvature (r1) of the discharge part (420) larger than the radius of curvature (r2) of the tip (411) of the discharge electrode (41), excessive concentration of the electric field can be further prevented.

[0127] In a discharge device (10) according to a sixth aspect, in any one of the first to fifth aspects, the counter electrode (42) further includes a cylindrical portion (423). The cylindrical portion (423) extends in the direction in which the discharge electrode (41) protrudes (upward). The cylindrical portion (423) includes a first opening (4231) and a second opening (4232). The first opening (4231) and the second opening (4232) are aligned in the protruding direction. The first opening (4231) is formed closer to the discharge electrode (41) than the second opening (4232). The discharge portion (420) is formed on the edge (edge ​​portion 424) of the first opening (4231).

[0128] According to this embodiment, the cylindrical portion (423) serves as a release path for the active ingredient, thereby enabling the active ingredient to be released efficiently.

[0129] A discharge device (10) according to a seventh aspect is the same as that of the sixth aspect, except that the cylindrical portion (423) further includes at least one stepped portion (4233; 4234; 4235). The stepped portion (4233; 4234; 4235) is formed between the first opening (4231) and the second opening (4232) on the inner periphery of the cylindrical portion (423). The stepped portion (4233; 4234; 4235) is formed in an annular shape. The discharge portion (420) is one of a plurality of discharge portions (420). At least one discharge portion (420) of the plurality of discharge portions (420) is formed in at least one stepped portion (4233; 4234; 4235).

[0130] According to this aspect, by providing a plurality of discharge parts (420), it is possible to prevent the electric field concentration in each discharge part (420) from becoming excessively high.

[0131] In the discharge device (10) according to the eighth aspect, in the sixth or seventh aspect, the edge (edge ​​portion 424) of the first opening (4231) is a portion including a line (L2) along which the distance (D1) between the tip end (411) of the discharge electrode (41) and the counter electrode (42) is shortest. The opening diameter (D3) of the second opening (4232) is smaller than the opening diameter (D4) of the first opening (4231).

[0132] According to this aspect, the discharge portion (420) is formed on the edge portion (424) including the line (L2) at which the distance (D1) from the tip portion (411) of the discharge electrode (41) is shortest, which makes it easier for a discharge to occur between the tip portion (411) of the discharge electrode (41) and the discharge portion (420), thereby further increasing the amount of active ingredient produced. Furthermore, the opening diameter (D3) of the second opening (4232) is smaller than the opening diameter (D4) of the first opening (4231), which makes it easier for the active ingredient to be released from the second opening (4232) more efficiently.

[0133] In the discharge device (10) according to a ninth aspect of the present invention, in any one of the first to eighth aspects, the tip (411) of the discharge electrode (41) holds the liquid (50). The liquid (50) is electrostatically atomized by discharge.

[0134] According to this aspect, the charged minute particle liquid containing radicals is generated. Therefore, the life of the radicals can be extended compared to when the radicals are released into the air alone. Furthermore, since the charged minute particle liquid is, for example, nanometer-sized, the charged minute particle liquid can be suspended over a relatively wide area.

[0135] The discharge device (10) according to a tenth aspect is the same as the ninth aspect, and further includes a liquid supply section (5). The liquid supply section (5) supplies a liquid (50) to the discharge electrode (41).

[0136] According to this embodiment, the liquid (50) is automatically supplied to the discharge electrode (41) by the liquid supply part (5), and therefore, the work of supplying the liquid (50) to the discharge electrode (41) is not required.

[0137] The components other than those of the first aspect are not essential components of the discharge device (10) and can be omitted as appropriate. [Explanation of symbols]

[0138] 10 Discharge device 41 Discharge electrode 411 Tip 42 Counter electrode 420 Discharge section 423 Cylinder part 4231 First opening 4232 Second Opening 4233, 4234, 4235 Step 424 Edge (edge ​​of first opening) 5 Liquid supply section 50 liquid D1 Distance D3 opening diameter D4 opening diameter L1 discharge path L2 line r1 radius of curvature r2 radius of curvature

Claims

1. a discharge electrode having a tip; a counter electrode disposed opposite the tip of the discharge electrode; a voltage application circuit that applies a voltage between the discharge electrode and the counter electrode, A discharge device that forms a first breakdown region extending from the discharge electrode toward the counter electrode and a second breakdown region extending from the counter electrode toward the discharge electrode, the base end of the first breakdown region is the tip end of the discharge electrode, the base end of the second breakdown region is an annular portion provided on the counter electrode; Discharge device.

2. a discharge electrode having a tip; a counter electrode disposed opposite the tip of the discharge electrode; a voltage application circuit that applies a voltage between the discharge electrode and the counter electrode, A discharge device that forms a dielectric breakdown region that connects the discharge electrode and the counter electrode, the dielectric breakdown region is formed so as to connect the tip of the discharge electrode and the annular portion provided on the counter electrode. Discharge device.

3. the counter electrode has an opening; The annular portion is a peripheral portion of the opening.

3. The discharge device according to claim 1 or 2.

4. The annular portion is annular. The discharge device according to any one of claims 1 to 3.

5. The annular portion has a curved surface. The discharge device according to any one of claims 1 to 4.

6. The tip of the discharge electrode has a curved surface, The radius of curvature of the curved surface of the annular portion is greater than the radius of curvature of the curved surface of the tip portion. The discharge device according to claim 5 .

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