discharge device

Abstract

The discharge device disclosed herein comprises a discharge electrode, an opposing electrode, a voltage application circuit, and a liquid supply unit. The discharge electrode is a columnar electrode. The opposing electrode faces the discharge electrode. The voltage application circuit applies an external voltage between the discharge electrode and the opposing electrode. The liquid supply unit supplies liquid to the discharge electrode. The liquid expands and contracts along the central axis of the discharge electrode due to discharge. The opposing electrode comprises a peripheral electrode portion and a protruding electrode portion. In the direction along the central axis of the discharge electrode, the top end of the liquid in the expanded state is located at the same position as the outer peripheral edge of the peripheral electrode portion or closer to the discharge electrode than the outer peripheral edge.

Description

[0001] This application is a divisional application of an application filed on July 16, 2020, with application number 202080065151.9 (international application number PCT / JP2020 / 027609), and invention name “Discharge device and electrode device”. Technical Field

[0002] The present disclosure generally relates to a discharge device and an electrode device, and more particularly to a discharge device including a discharge electrode and a counter electrode, and an electrode device used in the discharge device. Background Art

[0003] Patent Document 1 describes a discharge device comprising a discharge electrode and a counter electrode. A voltage is applied between the discharge electrode and the counter electrode to generate a discharge that develops from a corona discharge. The discharge generated by this device is intermittent, with insulation breakdown forming a discharge path extending from the discharge electrode to the surrounding area. The discharge device described in Patent Document 1 generates high-energy discharge, which can increase the production of active ingredients compared to corona discharge.

[0004] Patent Document 1 also describes that a counter electrode includes a needle-shaped electrode portion facing a discharge electrode. Thus, the discharge device stably generates discharge with a discontinuous discharge path between the discharge electrode and the needle-shaped electrode portion.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-22574 Summary of the Invention

[0008] An object of the present disclosure is to provide a discharge device and an electrode device capable of further improving the efficiency of generating effective components.

[0009] A discharge device according to a technical solution of the present disclosure includes a discharge electrode, an opposing electrode, a voltage application circuit, and a liquid supply unit. The discharge electrode is a columnar electrode. The opposing electrode is opposed to the discharge electrode. The voltage application circuit generates discharge by applying an external voltage between the discharge electrode and the opposing electrode. The liquid supply unit supplies liquid to the discharge electrode. The liquid expands and contracts along the central axis of the discharge electrode due to the discharge. The opposing electrode includes a peripheral electrode portion and a protruding electrode portion. The peripheral electrode portion protrudes toward the side opposite to the discharge electrode and has an opening formed at the top surface. The protruding electrode portion protrudes from the peripheral electrode portion into the opening. In the direction along the central axis of the discharge electrode, the top end of the liquid in the expanded state is located at the same position as the outer peripheral edge of the peripheral electrode portion or at a position closer to the discharge electrode than the outer peripheral edge.

[0010] An electrode device according to one aspect of the present disclosure is an electrode device used in the discharge device, includes the discharge electrode and the counter electrode, and is applied with the external voltage from the voltage application circuit.

[0011] A discharge device according to one technical solution of the present disclosure includes a discharge electrode, an opposing electrode, and a voltage application circuit. The discharge electrode is a columnar electrode. The opposing electrode is opposed to the discharge electrode. The voltage application circuit generates a discharge by applying an external voltage between the discharge electrode and the opposing electrode. The opposing electrode includes a peripheral electrode portion and a protruding electrode portion. The peripheral electrode portion protrudes toward a side opposite to the discharge electrode and has an opening formed on its top surface. The protruding electrode portion protrudes from the peripheral electrode portion into the opening. In a direction along the central axis of the discharge electrode, the top end of the discharge electrode is located closer to the discharge electrode than the outer peripheral edge of the peripheral electrode portion.

[0012] According to the present disclosure, there is an advantage that the production efficiency of the active ingredient can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A This is a partially cutaway perspective view schematically showing a main portion of the electrode device of the discharge device according to the first embodiment.

[0014] Figure 1B This is a cross-sectional view schematically showing the main parts of the electrode device according to the first embodiment.

[0015] Figure 2 This is a block diagram of the discharge device according to the first embodiment.

[0016] Figure 3 This is a schematic perspective view showing the main parts of the discharge device according to the first embodiment.

[0017] Figure 4 It is a schematic plan view showing the main parts of the discharge device according to the first embodiment.

[0018] Figure 5 The main part of the discharge device of the first embodiment is shown. Figure 4 A1-A1 line cross-sectional view.

[0019] Figure 6A This is a plan view of the counter electrode of the discharge device according to Embodiment 1.

[0020] Figure 6B This is a bottom view of the counter electrode in Embodiment 1.

[0021] Figure 7A This is a plan view showing a main portion of a counter electrode of the electrode device according to the first embodiment.

[0022] Figure 7B yes Figure 7A A1-A1 line cross-sectional view.

[0023] Figure 7C yes Figure 7A B1-B1 line cross-sectional view.

[0024] Figure 8A The main part of the electrode device according to the first embodiment is schematically shown in a cross-sectional view showing a state where liquid is expanded.

[0025] Figure 8B The main part of the electrode device according to the first embodiment is schematically shown in a cross-sectional view showing a state where liquid is contracted.

[0026] Figure 9A This is a schematic diagram showing the discharge form of corona discharge.

[0027] Figure 9B It is a schematic diagram showing the discharge form of full-circuit breakdown discharge.

[0028] Figure 9C This is a schematic diagram showing the discharge form of partial breakdown discharge.

[0029] Figure 10A This is a schematic plan view showing a counter electrode of the electrode device according to the second embodiment.

[0030] Figure 10B This is a schematic plan view showing a counter electrode of the electrode device according to the second embodiment.

[0031] Figure 10C This is a schematic plan view showing a counter electrode of the electrode device according to the second embodiment.

[0032] Figure 10D This is a schematic plan view showing a counter electrode of the electrode device according to the second embodiment. DETAILED DESCRIPTION

[0033] (Implementation 1)

[0034] (1) Summary

[0035] Below, refer to Figure 1A 、 Figure 1B as well as Figure 2 The outline of the discharge device 10 and the electrode device 3 according to this embodiment will be described.

[0036] like Figure 1A and Figure 1B As shown, the electrode device 3 of this embodiment includes a discharge electrode 1 and a counter electrode 2. The electrode device 3 is configured such that an external voltage V1 (see Figure 2 ) is applied between the discharge electrode 1 and the counter electrode 2, thereby generating discharge.

[0037] In addition, if Figure 2 As shown, the electrode device 3, the voltage application circuit 4, and the liquid supply unit 5 together constitute the discharge device 10. In other words, the discharge device 10 of this embodiment includes the electrode device 3, the voltage application circuit 4, and the liquid supply unit 5. The voltage application circuit 4 applies an external voltage V1 between the discharge electrode 1 and the counter electrode 2, thereby generating a discharge. The liquid supply unit 5 supplies a liquid 50 (see Figure 8A The discharge device 10 generates an electric discharge at the electrode device 3, thereby generating an effective component. The "effective component" referred to in this disclosure refers to a component generated by the discharge at the electrode device 3, and includes, for example, a charged particulate liquid containing OH radicals, OH radicals, O2 radicals, negative ions, positive ions, ozone, or nitrate ions. These effective components are not limited to sterilization, deodorization, moisturizing, preservation, or virus inactivation, but can also have useful effects in various situations.

[0038] In this discharge device 10, liquid 50 is electrostatically atomized using the discharge generated in the discharge device 10. Specifically, in the discharge device 10, for example, when liquid 50 supplied from the liquid supply unit 5 adheres to the surface of the discharge electrode 1, thereby retaining the liquid 50 on the discharge electrode 1, a voltage is applied between the discharge electrode 1 and the opposing electrode 2 from the voltage application circuit 4. Consequently, when a discharge is generated between the discharge electrode 1 and the opposing electrode 2, the liquid 50 retained on the discharge electrode 1 is electrostatically atomized due to the discharge. Thus, the discharge device 10 of this embodiment constitutes an electrostatic atomization device (effective ingredient generation system) that electrostatically atomizes the liquid 50 using discharge and generates a charged microparticle liquid as an effective ingredient. In this disclosure, the liquid 50 retained on the discharge electrode 1, i.e., the liquid 50 to be electrostatically atomized, is also referred to simply as "liquid 50."

[0039] In particular, in this embodiment, voltage application circuit 4 intermittently generates discharge by periodically varying the magnitude of applied voltage V1. This periodic variation in applied voltage V1 mechanically vibrates liquid 50. The term "applied voltage" as used herein refers to the voltage applied by voltage application circuit 4 between discharge electrode 1 and counter electrode 2 to generate discharge.

[0040] By applying a voltage (applied voltage V1) between the discharge electrode 1 and the counter electrode 2, the liquid 50 held by the discharge electrode 1 is subjected to a force generated by the electric field and forms a conical shape called a Taylor cone (see Figure 8A ), as described below. The electric field then concentrates at the top (apex) of the Taylor cone, causing discharge. The more pointed the Taylor cone tip, that is, the smaller (more acute) the cone's apex angle, the lower the electric field strength required for insulation breakdown, making discharge more likely to occur.

[0041] The liquid 50 held in the discharge electrode 1 is moved along the central axis P1 (see FIG. Figure 8B ) stretches and contracts, thereby deforming alternately into the first shape and the second shape. The first shape is a state in which the liquid 50 is stretched along the central axis P1 of the discharge electrode 1, that is, the shape of a Taylor cone (refer to Figure 8A The second shape is a state where the liquid 50 is contracted, that is, the top end of the Taylor cone is flattened (see Figure 8B As a result, since the Taylor cone as described above is periodically formed, discharge is intermittently generated in conjunction with the formation timing of the Taylor cone.

[0042] Furthermore, the discharge device 10 of this embodiment includes the discharge electrode 1, the counter electrode 2, the voltage application circuit 4, and the liquid supply unit 5 as described above. Figure 1A and Figure 1BAs shown, the discharge electrode 1 is a columnar electrode. The counter electrode 2 is opposite to the discharge electrode 1. The voltage application circuit 4 generates discharge by applying an external voltage V1 between the discharge electrode 1 and the counter electrode 2. The liquid supply portion 5 supplies liquid 50 to the discharge electrode 1. The liquid 50 expands and contracts along the central axis P1 of the discharge electrode 1 due to the discharge. The counter electrode 2 has a peripheral electrode portion 21 and a protruding electrode portion 22. The peripheral electrode portion 21 protrudes to the side opposite to the discharge electrode 1. The peripheral electrode portion 21 has an opening 23 formed on the top surface. The protruding electrode portion 22 protrudes from the peripheral electrode portion 21 into the opening 23. In the direction along the central axis P1 of the discharge electrode 1, the top end of the liquid 50 in the stretched state is located at the same position as the outer peripheral edge 210 of the peripheral electrode portion 21 or at a position closer to the discharge electrode 1 side than the outer peripheral edge 210 (refer to Figure 8A ).

[0043] According to the above-mentioned structure, when a voltage (applied voltage V1) is applied between the discharge electrode 1 and the opposing electrode 2, the electric field can be concentrated on the peripheral electrode portion 21 and the protruding electrode portion 22 in the opposing electrode 2 opposite to the discharge electrode 1. However, since the protruding electrode portion 22 protrudes from the peripheral electrode portion 21 into the opening 23, the degree of electric field concentration at the protruding electrode portion 22 is higher than that at the peripheral electrode portion 21. Therefore, when the liquid 50 held by the discharge electrode 1 is subjected to the force generated by the electric field to form a Taylor cone, the electric field tends to be concentrated, for example, between the top end (apex) of the Taylor cone and the protruding electrode portion 22. Therefore, a high-energy discharge is generated between the liquid 50 and the protruding electrode portion 22, and the corona discharge generated in the liquid 50 held by the discharge electrode 1 can be further developed into a high-energy discharge. As a result, a discharge path L1 (see FIG. 1 ) that is at least partially dielectrically broken is easily formed intermittently between the discharge electrode 1 and the opposing electrode 2. Figure 9B ), the generation efficiency of the effective ingredients is not easily reduced.

[0044] Furthermore, the peripheral electrode portion 21 protrudes toward the side opposite the discharge electrode 1, and an opening 23 is formed at the tip of the peripheral electrode portion 21. Therefore, the electric field exerts a force on the liquid 50 held by the discharge electrode 1, drawing the liquid 50 toward the peripheral electrode portion 21. Furthermore, in the direction along the central axis P1 of the discharge electrode 1, the tip of the liquid 50, when stretched, is located at the same position as the outer peripheral edge 210 of the peripheral electrode portion 21, or closer to the discharge electrode 1 than the outer peripheral edge 210. Consequently, when the liquid 50 held by the discharge electrode 1 is mechanically vibrated, for example, a force continuously acts on the liquid 50, drawing it toward the peripheral electrode portion 21. This allows the amplitude of the vibration of the liquid 50 to be suppressed to a minimum. That is, even when the liquid 50 is contracted, the liquid 50 is biased in the direction of being attracted toward the peripheral electrode portion 21. Therefore, the liquid 50 does not become completely flattened, and the amount of deformation of the liquid 50 caused by the mechanical vibration of the liquid 50 can be suppressed to a minimum. As a result, the vibration frequency of the liquid 50 can be increased, and the production efficiency of the active ingredient can be improved.

[0045] (2) Details

[0046] Below, refer to Figures 1A to 9C The details of the discharge device 10 and the electrode device 3 according to this embodiment will be described.

[0047] As an example, the following describes three mutually orthogonal axes: the X-axis, the Y-axis, and the Z-axis. Specifically, the axis along the central axis P1 of the discharge electrode 1 is referred to as the "Z-axis." Furthermore, the positive direction of the Z-axis is defined as the direction toward the opposing electrode 2 when viewed from the discharge electrode 1. The X-axis, Y-axis, and Z-axis are all imaginary axes. The arrows indicating "X," "Y," and "Z" in the figures are merely for illustrative purposes and do not represent physical entities. The aforementioned directions are not intended to limit the orientation of the electrode assembly 3 during use.

[0048] (2.1) Overall structure

[0049] As described above, the discharge device 10 of this embodiment is as follows Figure 2 As shown in FIG. 1 , the discharge device 10 includes an electrode device 3 , a voltage applying circuit 4 , and a liquid supply unit 5 .

[0050] The electrode device 3 includes a discharge electrode 1 and a counter electrode 2. Figure 2 , the shapes of the discharge electrode 1 and the counter electrode 2 are schematically shown. As described above, the electrode device 3 generates discharge by applying a voltage between the discharge electrode 1 and the counter electrode 2.

[0051] like Figure 1A and Figure 1B As shown, the discharge electrode 1 is a columnar electrode extending along the Z axis. The discharge electrode 1 has a discharge portion 11 at one end (top end) in the longitudinal direction (Z axis direction) and a base end 12 at the other end (the end opposite to the top end) in the longitudinal direction (see FIG. Figure 5 The discharge electrode 1 is a needle-shaped electrode in which at least the discharge portion 11 is formed into a tapered shape. The "tapered shape" mentioned here is not limited to a shape with a sharp tip, such as Figure 1A As shown in FIG. 1 , shapes with rounded tops are also included.

[0052] The counter electrode 2 is arranged to face the discharge portion 11 of the discharge electrode 1. As described above, the counter electrode 2 includes the peripheral electrode portion 21 and the protruding electrode portion 22. The peripheral electrode portion 21 is arranged to surround the central axis P1 of the discharge electrode 1 when viewed from one side of the central axis P1. The protruding electrode portion 22 protrudes from a portion of the circumference of the peripheral electrode portion 21 toward the central axis P1 of the discharge electrode 1 when viewed from one side of the central axis P1 of the discharge electrode 1 (the positive side of the Z axis).

[0053] In this embodiment, if Figures 3 to 5 As shown in FIG. 1 , the counter electrode 2 has a plate-shaped flat portion 24 that is long in the X-axis direction. Figure 5 As shown in FIG. 1 , the discharge electrode 1 is spaced apart from the counter electrode 2 in the direction along the central axis P1 of the discharge electrode 1 (Z-axis direction). Figure 5 As shown, the discharge electrode 1 and the counter electrode 2 are positioned apart from each other in the direction along the central axis P1 of the discharge electrode 1 (Z-axis direction).

[0054] Here, an opening 23 is formed partially in the flat plate portion 24, penetrating the flat plate portion 24 in the thickness direction (Z-axis direction) of the flat plate portion 24. The portion of the counter electrode 2 located around the opening 23 serves as the peripheral electrode portion 21. Furthermore, the portion protruding from the peripheral electrode portion 21 into the opening 23 serves as the protruding electrode portion 22.

[0055] The discharge electrode 1 and the counter electrode 2 are held in a housing 6 made of an electrically insulating synthetic resin. As an example, the flat plate portion 24 is formed by a plurality of (here, four) caulking protrusions 61 (see FIG. Figure 3 ) is caulkingly bonded to the housing 6 by heat caulking or the like. Thus, the counter electrode 2 is held in the housing 6.

[0056] Here, the positional relationship between the opposing electrode 2 and the discharge electrode 1 is determined so that the thickness direction of the opposing electrode 2 (the direction through which the opening 23 extends) coincides with the longitudinal direction (Z-axis direction) of the discharge electrode 1, and the discharge portion 11 of the discharge electrode 1 is located near the center of the opening 23 of the opposing electrode 2. In other words, when viewed from one side of the central axis P1 of the discharge electrode 1 (the positive side of the Z-axis), the center of the opening 23 is located on the central axis P1 of the discharge electrode 1. In other words, a gap (space) is ensured between the opposing electrode 2 and the discharge electrode 1, at least by the opening 23 of the opposing electrode 2. In other words, the opposing electrode 2 is positioned opposite the discharge electrode 1 across the gap and is electrically insulated from the discharge electrode 1.

[0057] The more detailed shapes of the discharge electrode 1 and the counter electrode 2 of the electrode assembly 3 will be described in the section “(2.3) Electrode Assembly”.

[0058] The liquid supply unit 5 supplies the liquid 50 for electrostatic atomization to the discharge electrode 1. As an example, the liquid supply unit 5 is realized by using a cooling device 51 that cools the discharge electrode 1 to generate condensed water on the discharge electrode 1. Specifically, as an example, Figure 5 As shown, the cooling device 51 includes a heat sink 512 and multiple (two in the illustrated example) Peltier elements 511. The multiple Peltier elements 511 are mechanically and electrically connected to the heat sink 512, for example, by soldering, and are retained by the heat sink 512. Each of the multiple Peltier elements 511 has one end (on the heat sink 512 side) as a heat dissipation end and the other end (on the side opposite the heat sink 512) as a heat absorption end.

[0059] Furthermore, multiple Peltier elements 511 are mechanically connected to the discharge electrode 1. Here, the discharge electrode 1 is mechanically connected to the cooling device 51 at its base end 12, and the multiple Peltier elements 511 are mechanically connected to the discharge electrode 1 at their heat-absorbing ends. In other words, the discharge electrode 1 and the cooling device 51 (the multiple Peltier elements 511) are thermally coupled.

[0060] The cooling device 51 cools the discharge electrode 1, which is thermally coupled to the Peltier elements 511, by energizing the plurality of Peltier elements 511. In this case, the cooling device 51 cools the entire discharge electrode 1 via the base end 12. This causes moisture in the air to condense and adhere to the surface of the discharge electrode 1 as condensed water. Specifically, the liquid supply unit 5 is configured to cool the discharge electrode 1 and generate condensed water as liquid 50 on the surface of the discharge electrode 1. With this configuration, the liquid supply unit 5 can utilize moisture in the air to supply the liquid 50 (condensed water) to the discharge electrode 1, eliminating the need to supply and replenish liquid to the discharge device 10.

[0061] The voltage application circuit 4 , the electrode device 3 , and the liquid supply unit 5 together constitute the discharge device 10 , which generates discharge by applying the applied voltage V1 between the discharge electrode 1 and the counter electrode 2 as described above.

[0062] like Figure 2 As shown, the voltage application circuit 4 has a voltage generating circuit 41, a drive circuit 42 and a control circuit 43. In addition, the voltage application circuit 4 also has a limiting resistor R1. The voltage generation circuit 41 is a circuit that receives power from a power supply and generates a voltage (applied voltage V1) to be applied to the electrode device 3. The "power supply" mentioned here is a power supply that supplies power for operation to the voltage generation circuit 41, etc., and as an example, it is a power supply circuit that generates a DC voltage of several V to more than ten V. The drive circuit 42 is a circuit that drives the voltage generation circuit 41. The control circuit 43 controls the drive circuit 42, for example, based on a monitoring object. The "monitoring object" mentioned here includes at least one of the output current and the output voltage of the voltage application circuit 4.

[0063] The voltage generating circuit 41 is, for example, a DC / DC converter, which boosts the input voltage from the power supply and outputs the boosted voltage as the applied voltage V1. The output voltage of the voltage generating circuit 41 is applied to the electrode device 3 (discharge electrode 1 and counter electrode 2) as the applied voltage V1.

[0064] The voltage generating circuit 41 is electrically connected to the electrode assembly 3 (discharge electrode 1 and opposing electrode 2). The voltage generating circuit 41 applies a high voltage to the electrode assembly 3. Here, the voltage generating circuit 41 is configured to apply a high voltage between the discharge electrode 1 and the opposing electrode 2, with the discharge electrode 1 serving as the negative electrode (grounded) and the opposing electrode 2 serving as the positive electrode (positive). In other words, when the high voltage is applied to the electrode assembly 3 from the voltage applying circuit 4, a potential difference is generated between the discharge electrode 1 and the opposing electrode 2, with the discharge electrode 1 side at a low potential and the opposing electrode 2 side at a high potential. The "high voltage" referred to here can be any voltage set to cause full-circuit breakdown discharge or localized breakdown discharge, described later, in the electrode assembly 3. As an example, it is a voltage with a peak value of approximately 6.0 kV. Full-circuit breakdown discharge and localized breakdown discharge are described in detail in the "(2.4) Discharge Method" section. The high voltage applied from the voltage applying circuit 4 to the electrode device 3 is not limited to approximately 6.0 kV, and can be appropriately set according to, for example, the shapes of the discharge electrode 1 and the counter electrode 2 or the distance therebetween.

[0065] Furthermore, a limiting resistor R1 is inserted between the voltage generating circuit 41 and the electrode assembly 3. In other words, the voltage application circuit 4 includes the voltage generating circuit 41 that generates the applied voltage V1, and the limiting resistor R1 inserted between one output terminal of the voltage generating circuit 41 and the electrode assembly 3. The limiting resistor R1 is a resistor used to limit the peak value of the discharge current flowing after insulation breakdown. Specifically, the limiting resistor R1 protects the electrode assembly 3 and the voltage application circuit 4 from overcurrent by limiting the current flowing into the electrode assembly 3 during discharge.

[0066] In this embodiment, limiting resistor R1 is inserted between voltage generating circuit 41 and counter electrode 2. As described above, counter electrode 2 is positive, so limiting resistor R1 is inserted between the high potential side output terminal of voltage generating circuit 41 and electrode device 3.

[0067] Here, the operation mode of the voltage application circuit 4 includes two modes: the first mode and the second mode. The first mode is a mode for causing the applied voltage V1 to rise over time, and for causing the corona discharge to develop and form a discharge path L1 between the discharge electrode 1 and the counter electrode 2, which is at least partially dielectrically broken down, thereby generating a discharge current. The second mode is a mode for putting the electrode device 3 in an overcurrent state and cutting off the discharge current using a control circuit 43 or the like. The "discharge current" referred to in this disclosure refers to a relatively large current flowing through the discharge path L1, and does not include a small current of several μA generated during the corona discharge before the discharge path L1 is formed. The "overcurrent state" referred to in this disclosure refers to a state in which the load is reduced due to discharge and a current exceeding the assumed value flows to the electrode device 3.

[0068] In this embodiment, the control circuit 43 controls the voltage application circuit 4 by controlling the drive circuit 42. The control circuit 43 controls the drive circuit 42 so that the voltage application circuit 4 alternates between the first mode and the second mode during the drive period in which the voltage application circuit 4 is driven. Here, the control circuit 43 switches between the first mode and the second mode at the drive frequency so that the magnitude of the applied voltage V1 applied from the voltage application circuit 4 to the electrode device 3 periodically varies at the drive frequency. The "drive period" referred to in this disclosure is the period in which the voltage application circuit 4 is driven to cause the electrode device 3 to discharge.

[0069] That is, the voltage application circuit 4 does not maintain the magnitude of the voltage applied to the electrode device 3 including the discharge electrode 1 at a constant value, but instead causes the magnitude of the voltage to fluctuate periodically at a driving frequency within a predetermined range. The voltage application circuit 4 intermittently generates discharges by periodically varying the magnitude of the applied voltage V1. In other words, the discharge path L1 is periodically formed in conjunction with the fluctuation period of the applied voltage V1, and discharges occur periodically. Hereinafter, the period in which discharges (full-path breakdown discharges or local breakdown discharges) occur will also be referred to as a "discharge period." As a result, the magnitude of the electrical energy acting on the liquid 50 held by the discharge electrode 1 fluctuates periodically at the driving frequency, resulting in the liquid 50 held by the discharge electrode 1 mechanically vibrating at the driving frequency.

[0070] To increase the deformation of the liquid 50, the frequency of the applied voltage V1, or the driving frequency, is preferably set within a predetermined range that includes the resonant frequency (natural frequency) of the liquid 50 held by the discharge electrode 1. In other words, it is set to a value near the resonant frequency of the liquid 50. The "predetermined range" referred to in this disclosure refers to the range of frequencies that amplify the mechanical vibration of the liquid 50 when the force (energy) applied to the liquid 50 is vibrated at a frequency within this predetermined range. This range has lower and upper limits defined based on the resonant frequency of the liquid 50. In other words, the driving frequency is set to a value near the resonant frequency of the liquid 50. In this case, the amplitude of the mechanical vibration of the liquid 50 caused by fluctuations in the magnitude of the applied voltage V1 becomes relatively large, resulting in an increase in the deformation of the liquid 50 caused by the mechanical vibration. The resonant frequency of the liquid 50 depends on, for example, the volume (amount), surface tension, and viscosity of the liquid 50.

[0071] Specifically, in the discharge device 10 of this embodiment, the liquid 50 mechanically vibrates at a drive frequency near its resonant frequency, resulting in a relatively large amplitude. Consequently, the tip (apex) of the Taylor cone formed by the liquid 50 when an electric field acts on it forms a more pointed (acute) shape. Consequently, compared to when the liquid 50 mechanically vibrates at a frequency that deviates from its resonant frequency, the electric field strength required for dielectric breakdown is reduced when the Taylor cone is formed, facilitating discharge. This allows for stable discharge despite variations in the voltage (applied voltage V1) applied to the electrode assembly 3 by the voltage application circuit 4, variations in the shape of the discharge electrode 1, or variations in the amount (volume) of the liquid 50 supplied to the discharge electrode 1. Furthermore, the voltage application circuit 4 can suppress the voltage applied to the electrode assembly 3, including the discharge electrode 1, to a relatively low level. This simplifies the insulation structure around the electrode assembly 3 and reduces the withstand voltage of components such as the voltage application circuit 4.

[0072] However, in this embodiment, even when the liquid 50 is contracting, the liquid 50 is biased toward the peripheral electrode portion 21, thereby minimizing the deformation of the liquid 50 caused by the mechanical vibration of the liquid 50. Consequently, the discharge device 10 of this embodiment can increase the vibration frequency of the liquid 50, thereby improving the efficiency of generating the active ingredient. For a detailed explanation of the principle of increasing the vibration frequency of the liquid 50, see "(2.5) Vibration Frequency of the Liquid."

[0073] (2.2) Action

[0074] The discharge device 10 having the above-described configuration causes discharge to occur in the electrode device 3 (the discharge electrode 1 and the counter electrode 2 ) by operating the voltage application circuit 4 as follows.

[0075] Specifically, before discharge path L1 is formed, control circuit 43 monitors the output voltage of voltage application circuit 4. When the monitored output voltage (output voltage) exceeds a maximum value α, control circuit 43 reduces the energy output from voltage generation circuit 41. After discharge path L1 is formed, control circuit 43 monitors the output current of voltage application circuit 4. When the monitored output current exceeds a threshold value, control circuit 43 reduces the energy output from voltage generation circuit 41. Consequently, voltage application circuit 4 reduces the voltage applied to electrode device 3 and operates in the second mode, which causes electrode device 3 to enter an overcurrent state and thereby cuts off the discharge current. In other words, the operating mode of voltage application circuit 4 switches from the first mode to the second mode.

[0076] At this point, the output voltage and output current of the voltage application circuit 4 decrease, so the control circuit 43 restarts the drive circuit 42. As a result, the voltage applied to the electrode device 3 increases over time, causing corona discharge to develop, forming a discharge path L1 between the discharge electrode 1 and the counter electrode 2, which is at least partially dielectrically broken.

[0077] During the driving period, the control circuit 43 repeatedly performs the above-described operation, causing the voltage application circuit 4 to operate alternately between the first mode and the second mode. As a result, the amount of electrical energy acting on the liquid 50 held by the discharge electrode 1 periodically fluctuates at the driving frequency, causing the liquid 50 to mechanically vibrate at the driving frequency.

[0078] In short, by applying a voltage to the electrode device 3 including the discharge electrode 1 through the self-voltage application circuit 4, the force generated by the electric field acts on the liquid 50 held by the discharge electrode 1, causing the liquid 50 to deform. At this time, the force F1 acting on the liquid 50 held by the discharge electrode 1 is represented by the product of the charge q1 contained in the liquid 50 and the electric field E1 (F1 = q1 × E1). In particular, in this embodiment, since a voltage is applied between the counter electrode 2 opposite to the discharge portion 11 of the discharge electrode 1 and the discharge electrode 1, the liquid 50 is acted upon by a force in the direction of being pulled toward the counter electrode 2 under the action of the electric field. As a result, as Figure 8A As shown in FIG. 1 , the liquid 50 held in the discharge portion 11 of the discharge electrode 1 is subjected to the force generated by the electric field, and stretches along the central axis P1 of the discharge electrode 1 (i.e., along the Z-axis direction) toward the counter electrode 2, forming a conical shape called a Taylor cone. Figure 8A As the state shown decreases, the force acting on the liquid 50 also decreases due to the influence of the electric field, so that the liquid 50 deforms. Figure 8B As shown, the liquid 50 held in the discharge portion 11 of the discharge electrode 1 shrinks.

[0079] Furthermore, by periodically changing the magnitude of the voltage applied to the electrode device 3 at the driving frequency, the liquid 50 held by the discharge electrode 1 is alternately deformed into Figure 8A The shape and Figure 8B The shape shown. That is, in this embodiment, the discharge electrode 1 holds the liquid 50 in such a way that the discharge portion 11 is covered by the liquid 50. The liquid 50 expands and contracts along the central axis P1 of the discharge electrode 1 (i.e., along the Z-axis direction) due to discharge. Since the electric field is concentrated at the top end (apex) of the Taylor cone, discharge occurs, so Figure 8A As shown, dielectric breakdown occurs when the tip of the Taylor cone is sharp, and thus discharge (full-circuit breakdown discharge or local breakdown discharge) occurs intermittently in accordance with the driving frequency.

[0080] Liquid 50 held by discharge electrode 1 is thus electrostatically atomized by the discharge. Consequently, an active ingredient consisting of nanometer-sized charged microparticles containing free radicals is generated in discharge device 10. The generated active ingredient (charged microparticles) is released into the surrounding area of ​​discharge device 10, for example, through opening 23 of counter electrode 2.

[0081] (2.3) Electrode device

[0082] Next, refer to Figure 1A 、 Figure 1B as well as Figures 6A to 8B The shape of the electrode assembly 3 (discharge electrode 1 and counter electrode 2) used in the discharge device 10 of this embodiment will be described in more detail. Figure 1A、 Figure 1B 、 Figure 8A as well as Figure 8B , main parts of the discharge electrode 1 and the counter electrode 2 constituting the electrode device 3 are schematically shown, and the configuration other than the discharge electrode 1 and the counter electrode 2 is omitted as appropriate. Figure 1A It is along Figure 4 A schematic three-dimensional diagram after cutting along the B1-B1 line, Figure 1B It is along Figure 4 Schematic cross-sectional view taken along line B1-B1. Figures 6A to 7C This figure shows only the counter electrode 2 .

[0083] That is, in this embodiment, as described above, the counter electrode 2 includes the peripheral electrode portion 21 and the protruding electrode portion 22. The peripheral electrode portion 21 is arranged so as to surround the central axis P1 of the discharge electrode 1 (see FIG. 1 ) when viewed from the central axis P1 of the discharge electrode 1 (i.e., when viewed from the Z-axis side). Figure 7A When viewed from the side of the central axis P1 of the discharge electrode 1 (i.e., when viewed from the side of the Z axis), the protruding electrode portion 22 protrudes from a part of the circumference of the peripheral electrode portion 21 toward the central axis P1 of the discharge electrode 1 (see Figure 7A ).

[0084] As an example, the discharge electrode 1 is formed of a conductive metal material such as titanium alloy (Ti alloy). Figure 1A and Figure 1B As shown, the discharge electrode 1 is a cylindrical electrode extending along the Z-axis. The discharge electrode 1 has a discharge portion 11 at one end (top end) in the longitudinal direction (Z-axis direction).

[0085] In this embodiment, the top end portion (discharge portion 11) of the discharge electrode 1 is formed as a whole into a substantially hemispherical shape. In other words, the top end surface of the discharge electrode 1, i.e., the surface facing the counter electrode 2 in the Z-axis direction, includes a curved surface. In this embodiment, the surface of the discharge electrode 1 facing the counter electrode 2 in the Z-axis direction (positive direction of the Z-axis) is defined as the discharge portion 11. When the liquid 50 is supplied to the discharge electrode 1 by the liquid supply portion 5, the liquid 50 is retained on the discharge electrode 1 so as to cover at least the discharge portion 11 (see FIG. 1 ). Figure 8A and Figure 8B ).

[0086] On the other hand, as an example, the counter electrode 2 is formed of a conductive metal material such as titanium alloy (Ti alloy). In this embodiment, the counter electrode 2 has a plate-shaped flat portion 24 as described above. Figures 6A to 7CAs shown, an opening 23 is formed in a portion of the flat plate portion 24, penetrating the flat plate portion 24 in the thickness direction (Z-axis direction) of the flat plate portion 24. The portion of the counter electrode 2 located around the opening 23 serves as the peripheral electrode portion 21. Furthermore, the portion protruding from the peripheral electrode portion 21 into the opening 23 serves as the protruding electrode portion 22.

[0087] Furthermore, the counter electrode 2 is provided with an extension portion 25 extending outward from the peripheral electrode portion 21 . That is, in the discharge device 10 of this embodiment, the counter electrode 2 has the extension portion 25 in addition to the peripheral electrode portion 21 , the protruding electrode portion 22 , and the flat plate portion 24 .

[0088] More specifically, a dome-shaped peripheral electrode portion 21 is formed in a portion of the flat plate portion 24, protruding in a direction away from the discharge electrode 1 (positive direction of the Z axis) along the central axis P1 of the discharge electrode 1. In other words, the peripheral electrode portion 21 protrudes toward the side opposite to the discharge electrode 1 (positive direction of the Z axis). As an example, the peripheral electrode portion 21 is formed into a hemispherical shell shape (dome shape) flattened in the Z axis direction by drawing a portion of the flat plate portion 24. Figure 7B and Figure 7C As shown, the peripheral electrode portion 21 has an inner surface 212 that is recessed toward the side opposite to the discharge electrode 1. The inner surface 212 is a sloped surface that is inclined relative to the central axis P1 of the discharge electrode 1 so that the inner diameter of the edge on the discharge electrode 1 side in the Z-axis direction is larger than the inner diameter of the edge on the side opposite to the discharge electrode 1.

[0089] In addition, an opening 23 is formed in the center of the peripheral electrode portion 21. The opening 23 is formed on the top surface of the peripheral electrode portion 21 that protrudes toward the side opposite to the discharge electrode 1 (the positive side of the Z axis). The opening 23 is a circular opening that penetrates the opposing electrode 2 in the thickness direction (Z axis direction) of the opposing electrode 2. In other words, the peripheral electrode portion 21 has the opening 23 that is a circular opening. Figure 7A In FIG, the inner periphery 231 (that is, the periphery of the opening 23) and the outer periphery 210 of the peripheral electrode portion 21 are represented by imaginary lines (two-dot chain lines). Figure 7A In FIG, a region between two concentric imaginary lines (two-dot chain lines) is the peripheral electrode portion 21. The center of the opening 23 is located on the central axis P1 of the discharge electrode 1.

[0090] Furthermore, the protruding electrode portion 22 protrudes from the peripheral electrode portion 21 into the opening 23. Here, the protruding electrode portion 22 protrudes from the inner peripheral edge 231 of the peripheral electrode portion 21 (i.e., the peripheral edge of the opening 23) toward the center of the opening 23. In this embodiment, a plurality of protruding electrode portions 22 are provided. That is, in this embodiment, the counter electrode 2 has a plurality of protruding electrode portions 22.

[0091] The counter electrode 2 preferably has three or more protruding electrode portions 22. In this embodiment, as an example, the counter electrode 2 has four protruding electrode portions 22. Having three or more protruding electrode portions 22 in this manner can alleviate electric field concentration at the protruding electrode portions 22, compared to a case where there are two or fewer protruding electrode portions 22. The plurality of protruding electrode portions 22 protrude from a portion of the circumference of the peripheral electrode portion 21 toward the central axis P1 of the discharge electrode 1.

[0092] Here, a plurality of (here, 4) protruding electrode portions 22 are arranged at equal intervals in the circumferential direction of the peripheral electrode portion 21. That is, a plurality of protruding electrode portions 22 are arranged at equal intervals in the circumferential direction of the opening portion 23. In this embodiment, the opposing electrode 2 has 4 protruding electrode portions 22, and therefore, the 4 protruding electrode portions 22 are arranged at positions that are rotationally symmetrical by 90 degrees in the circumferential direction of the peripheral electrode portion 21 (the circumferential direction of the opening portion 23). That is, a plurality of protruding electrode portions 22 are arranged at point-symmetrical positions with the center of the opening portion 23 as the symmetry point (center of symmetry). In Figure 7A In the embodiment, when the positive direction of the X-axis (rightward) is defined as "0 degrees" and the positive direction of the Y-axis (upward) is defined as "90 degrees", the four protruding electrode portions 22 are respectively provided at positions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees. As an example, the above-described opening 23 and the plurality of protruding electrode portions 22 are formed by punching.

[0093] Furthermore, the multiple (here, four) protruding electrode portions 22 have a common shape. In other words, the multiple protruding electrode portions 22 have shapes that are rotationally symmetrical at 90 degrees with respect to the central axis P1 of the discharge electrode 1. Therefore, the distance from the discharge portion 11 located on the central axis P1 of the discharge electrode 1 to the protruding electrode portion 22 is substantially uniform across the multiple protruding electrode portions 22.

[0094] Furthermore, the electrode assembly 3 of this embodiment is configured to intermittently form a discharge path L1, at least partially dielectrically broken, between the discharge portion 11 of the discharge electrode 1 and the protruding electrode portion 22 of the counter electrode 2, in order to increase the amount of active ingredient generated. In this case, it is preferable to concentrate the electric field at the tip of the protruding electrode portion 22 to reduce ozone generation.

[0095] So, for example, Figure 7AAs shown, the protruding electrode portion 22 is preferably in an arc shape as a whole when viewed from above. In other words, it is preferred that the outer periphery of the protruding electrode portion 22 is in an arc shape as a whole when viewed from one side of the central axis P1 of the discharge electrode 1 (i.e., when viewed from one side of the Z axis). The "arc shape" mentioned in the present disclosure is not limited to the shape of a part of a perfect circle, but also includes the shape of an R surface (curved surface) with a substantially uniform curvature radius at the top. That is, the top surface 221 of the protruding electrode portion 22 is as shown in FIG. Figure 7A As shown, it has an arc shape when viewed from above. With this shape, the electric field does not act uniformly across the entire top surface 221 of the protruding electrode portion 22 when viewed from above. Instead, the electric field tends to concentrate at the vertex of the top surface 221 of the protruding electrode portion 22, where the distance to the discharge electrode 1 (particularly the discharge portion 11) is shortest when viewed from above. This has the advantage of stabilizing the discharge between the discharge portion 11 and the protruding electrode portion 22.

[0096] Furthermore, if the top surface 221 (apex) of the protruding electrode portion 22 is sharp when viewed from above, this portion is susceptible to electrolytic corrosion due to electric field concentration, potentially causing the discharge state to vary over time. Therefore, to prevent the discharge state from varying over time, the top surface 221 of the protruding electrode portion 22 when viewed from above preferably includes a curved surface.

[0097] Furthermore, the degree of electric field concentration at the opposing electrode 2 varies depending on the shape of the surface of the opposing electrode 2 facing the discharge electrode 1 (particularly the discharge portion 11). In this embodiment, the electric field concentration at the opposing electrode 2 is slightly alleviated by setting the surface of the opposing electrode 2 facing the discharge electrode 1 (particularly the discharge portion 11) to be an R-surface (curved surface). Specifically, at least one of the following four locations of the opposing electrode 2 includes an R-surface. The first location is as follows: Figure 7A The top surface 221 of the protruding electrode portion 22 is shown as viewed from the side of the central axis P1 of the discharge electrode 1. Figure 7C The imaginary plane VP1 including the central axis P1 of the discharge electrode 1 and the top of the protruding electrode portion 22 (see Figure 8A ) in the corner 222 of the protruding electrode portion 22 on the discharge electrode 1 side. The third portion is as follows Figure 7C The fourth portion is the corner 211 of the peripheral electrode portion 21 on the discharge electrode 1 side within the virtual plane VP1 shown. Figure 7C The inner surface 212 of the peripheral electrode portion 21 is shown within the virtual plane VP1. Figure 8A and Figure 8B It is a cross-sectional view taken along a virtual plane VP1 including the central axis P1 of the discharge electrode 1 and the tip of the protruding electrode portion 22 .

[0098] In this embodiment, all four of these locations have curved shapes. Specifically, the top surface 221 of the protruding electrode portion 22, as well as the corner 222, corner 211, and inner surface 212 within the imaginary plane VP1, all have curved shapes when viewed from above. Furthermore, in this embodiment, in addition to these four locations, the inner peripheral edge 231 of the peripheral electrode portion 21 (the peripheral edge of the opening 23) when viewed from the side of the central axis P1 of the discharge electrode 1 (in a plan view) also has a curved shape.

[0099] The corner 211 of the peripheral electrode portion 21 is formed by the corner portion of the peripheral electrode portion 21 located closest to the discharge portion 11. In this embodiment, the corner 211 is the edge of the dome-shaped inner surface 212 of the peripheral electrode portion 21 on the discharge electrode 1 side in the Z-axis direction. In other words, the corner 211 is the corner between the surface of the peripheral electrode portion 21 facing the central axis P1 of the discharge electrode 1 (the inner surface 212) and the surface facing the negative direction of the Z-axis. The corner 211 is formed throughout the entire circumference of the peripheral electrode portion 21. Therefore, when viewed from the side of the central axis P1 of the discharge electrode 1, the corner 211 is formed in a circular shape centered on the central axis P1. As a result, the distance from the discharge portion 11 located on the central axis P1 of the discharge electrode 1 to the corner 211 is approximately uniform throughout the entire circumference of the corner 211.

[0100] The corner 222 of the protruding electrode portion 22 is formed by the corner portion of the protruding electrode portion 22 located closest to the discharge portion 11. In this embodiment, the corner 222 is the edge of the vertex of the protruding electrode portion 22, which is formed in an arc shape when viewed from above, on the discharge electrode 1 side in the Z-axis direction. In other words, the corner 222 is the angle between the surface of the protruding electrode portion 22 facing the central axis P1 of the discharge electrode 1 and the surface facing the negative direction of the Z-axis. Here, the distance from the discharge portion 11 located on the central axis P1 of the discharge electrode 1 to the corner 222 is approximately equal for the multiple (here, four) protruding electrode portions 22.

[0101] More specifically, the five locations are each formed into an arc shape. Furthermore, of the five locations, the inner surface 212 of the peripheral electrode portion 21 and the inner peripheral edge 231 of the peripheral electrode portion 21 are arc-shaped, convex toward the side opposite the discharge portion 11, i.e., concave toward the discharge portion 11 side. Meanwhile, the top surface 221 of the protruding electrode portion 22, the corner 211 of the peripheral electrode portion 21, and the corner 222 of the protruding electrode portion 22 are arc-shaped, convex toward the discharge portion 11 side. Furthermore, the curvature radii of the curved shapes of the five locations preferably satisfy the following relationship. That is, the five locations, starting from the side with the larger curvature radius, are, in order: the inner surface 212 of the peripheral electrode portion 21, the inner peripheral edge 231 of the peripheral electrode portion 21, the top surface 221 of the protruding electrode portion 22, the corner 211 of the peripheral electrode portion 21, and the corner 222 of the protruding electrode portion 22.

[0102] In short, the radius of curvature of the inner surface 212 of the peripheral electrode portion 21 is the largest. Furthermore, the radius of curvature of the curved shape of the top surface 221 of the protruding electrode portion 22 is larger than the radius of curvature of the curved shape of the corner portion 222 of the protruding electrode portion 22 on the discharge electrode 1 side. That is, the radius of curvature of the corner portion 222 of the protruding electrode portion 22 on the discharge electrode 1 side within virtual plane VP1 is smaller than that of the top surface 221 of the protruding electrode portion 22 when viewed from above. Furthermore, the radius of curvature of the curved shape of the top surface 221 of the protruding electrode portion 22 is smaller than the radius of curvature of the curved shape of the inner surface 212 of the peripheral electrode portion 21. That is, the radius of curvature of the inner surface 212 of the peripheral electrode portion 21 within virtual plane VP1 is larger than that of the top surface 221 of the protruding electrode portion 22 when viewed from above. As an example, the radius of curvature of the inner circumferential edge 231 of the peripheral electrode portion 21 is preferably greater than 2.0 mm and less than 5.0 mm. More specifically, the curvature radius of the inner peripheral edge 231 of the peripheral electrode portion 21 is preferably 3.5 mm or less.

[0103] The extension portion 25 is a portion extending outward from the peripheral electrode portion 21. Figure 7B and Figure 7CAs shown, the extension portion 25 is formed so that the further away from the peripheral electrode portion 21, the further away from the discharge electrode 1 it is in the direction along the central axis P1 of the discharge electrode 1. In this embodiment, the extension portion 25 is located around the peripheral electrode portion 21, connecting the flat plate portion 24 and the peripheral electrode portion 21. Specifically, when viewed from one side of the central axis P1 of the discharge electrode 1 (in a plan view), the peripheral electrode portion 21 and the extension portion 25 are formed concentrically with the central axis P1 as the center. Furthermore, within the extension portion 25, the outer peripheral portion connected to the flat plate portion 24 is located on the side opposite to the discharge electrode 1 in the direction along the central axis P1 of the discharge electrode 1, i.e., on the positive side of the Z axis, relative to the inner peripheral portion connected to the peripheral electrode portion 21. In other words, the extension portion 25 is tilted relative to the central axis P1 of the discharge electrode 1 such that the inner diameter of the end edge on the discharge electrode 1 side in the Z axis direction is smaller than the inner diameter of the end edge on the side opposite to the discharge electrode 1 (the flat plate portion 24 side).

[0104] Therefore, the counter electrode 2 is as Figure 7B and Figure 7C As shown, the shape is formed to extend from the opening 23 toward the outer periphery (flat plate portion 24 side) in the negative direction of the Z axis and further extend from its tip in the positive direction of the Z axis. Thus, a recessed portion (groove) having a substantially V-shaped cross-section is formed around the opening 23, extending across the entire circumference of the opening 23 and concave in the negative direction of the Z axis. As an example, the extension portion 25 is formed together with the peripheral electrode portion 21 by partially recessing the flat plate portion 24 through deep drawing.

[0105] By including such an extension portion 25 in the counter electrode 2, portions of the counter electrode 2 other than the peripheral electrode portion 21 and the protruding electrode portion 22 can be positioned away from the discharge electrode 1 (particularly the discharge portion 11). In short, by positioning portions of the counter electrode 2 outside the outer periphery 210 of the peripheral electrode portion 21 away from the discharge electrode 1 in the Z-axis direction, the generation of an unnecessary electric field between the extension portion 25 or the flat plate portion 24 and the discharge electrode 1 can be suppressed. As a result, an electric field can be efficiently generated between the peripheral electrode portion 21 and the protruding electrode portion 22 of the counter electrode 2 and the discharge electrode 1.

[0106] In addition, if Figure 1A and Figure 1B As shown, the distance D1 from the peripheral electrode portion 21 to the discharge electrode 1 is greater than the distance D2 from the protruding electrode portion 22 to the discharge electrode 1 (D1 ≥ D2). Preferably, the distance D1 from the peripheral electrode portion 21 to the discharge electrode 1 is greater than the distance D2 from the protruding electrode portion 22 to the discharge electrode 1.

[0107] The term "distance D1" as used herein refers to the shortest distance from the peripheral electrode portion 21 to the discharge electrode 1. In this embodiment, it is the length of a line segment connecting a point at the corner 211 of the peripheral electrode portion 21 and a point at the discharge portion 11. Furthermore, the term "distance D2" as used herein refers to the shortest distance from the protruding electrode portion 22 to the discharge electrode 1. In this embodiment, it is the length of a line segment connecting a point at the corner 222 of the protruding electrode portion 22 and a point at the discharge portion 11. Specifically, the distance D1 from the peripheral electrode portion 21 to the discharge portion 11 is the distance from the corner 211 to the discharge portion 11. The distance D2 from the protruding electrode portion 22 to the discharge portion 11 is the distance from the corner 222 to the discharge portion 11.

[0108] In addition, in this embodiment, as described above, the liquid 50 is held on the discharge electrode 1 so as to cover the discharge portion 11, and the liquid 50 expands and contracts along the central axis P1 of the discharge electrode 1 (i.e., along the Z-axis direction) due to discharge. Here, when the liquid 50 is expanded along the central axis P1 of the discharge electrode 1, as shown in FIG. Figure 8A As shown in FIG, the liquid 50 becomes a Taylor cone shape (first shape). On the other hand, when the liquid 50 contracts, as shown in FIG. Figure 8B As shown, the liquid 50 has a shape in which the tip of the Taylor cone is flattened (second shape).

[0109] Moreover, if Figure 8A As shown in FIG. 1 , when the liquid 50 is in the extended state (first shape), it is preferable to define the distance from the peripheral electrode portion 21 and the protruding electrode portion 22 based on the liquid 50 instead of the discharge portion 11 as follows. Figure 8A As shown, in the state where the liquid 50 is extended, the distance D3 from the liquid 50 to the peripheral electrode portion 21 is greater than the distance D4 from the liquid 50 to the protruding electrode portion 22 (D3≥D4).

[0110] The "distance D3" referred to in this disclosure refers to the shortest distance from the liquid 50 in the extended state to the peripheral electrode portion 21. In this embodiment, it is the length of a line segment connecting a point at the corner 211 of the peripheral electrode portion 21 and the vertex of the first shape of the liquid 50. In addition, the "distance D4" referred to in this disclosure refers to the shortest distance from the liquid 50 in the extended state to the protruding electrode portion 22. In this embodiment, it is the length of a line segment connecting a point at the corner 222 of the protruding electrode portion 22 and the vertex of the first shape of the liquid 50. That is, the distance D3 from the liquid 50 to the peripheral electrode portion 21 is the distance from the corner 211 to the liquid 50 in the first shape (Taylor cone). The distance D4 from the liquid 50 to the protruding electrode portion 22 is the distance from the corner 222 to the liquid 50 in the first shape (Taylor cone).

[0111] Here, within the imaginary plane VP1 including the central axis P1 of the discharge electrode 1 and the top end of the protruding electrode portion 22, the inclination angle θ1 of the imaginary line connecting the liquid 50 and the top end of the protruding electrode portion 22 with respect to the central axis P1 of the discharge electrode 1 is 67 degrees or less. The "imaginary line connecting the liquid 50 and the top end of the protruding electrode portion 22" referred to here is the shortest distance from the liquid 50 in the extended state to the protruding electrode portion 22, and is a line segment connecting a point at the corner 222 of the protruding electrode portion 22 and the vertex of the liquid 50 in the first shape ( Figure 8A The arrow in FIG. 4 indicates the distance D4).

[0112] And, as Figure 8B As shown in FIG. 1 , when the liquid 50 is in a contracted state (second shape), it is preferable to define the distance from the peripheral electrode portion 21 and the protruding electrode portion 22 based on the liquid 50 instead of the discharge portion 11 as follows. Figure 8B As shown, in the state where the liquid 50 is contracted, the distance D5 from the liquid 50 to the peripheral electrode portion 21 is greater than the distance D6 from the liquid 50 to the protruding electrode portion 22 (D5≥D6).

[0113] The "distance D5" referred to in this disclosure refers to the shortest distance from the contracted liquid 50 to the peripheral electrode portion 21. In this embodiment, it is the length of a line segment connecting a point at the corner 211 of the peripheral electrode portion 21 and the vertex of the second shape of the liquid 50. Furthermore, the "distance D6" referred to in this disclosure refers to the shortest distance from the contracted liquid 50 to the protruding electrode portion 22. In this embodiment, it is the length of a line segment connecting a point at the corner 222 of the protruding electrode portion 22 and the vertex of the second shape of the liquid 50. Specifically, the distance D5 from the liquid 50 to the peripheral electrode portion 21 is the distance from the corner 211 to the second shape of the liquid 50 (the shape of the Taylor cone with the top portion flattened). The distance D6 from the liquid 50 to the protruding electrode portion 22 is the distance from the corner 222 to the second shape of the liquid 50 (the shape of the Taylor cone with the top portion flattened).

[0114] Here, within the imaginary plane VP1 including the central axis P1 of the discharge electrode 1 and the top end of the protruding electrode portion 22, the inclination angle θ2 of the imaginary line connecting the liquid 50 and the top end of the protruding electrode portion 22 with respect to the central axis P1 of the discharge electrode 1 is 67 degrees or less. The "imaginary line connecting the liquid 50 and the top end of the protruding electrode portion 22" referred to here is the shortest distance from the liquid 50 in the contracted state to the protruding electrode portion 22, and is a line segment connecting a point at the corner 222 of the protruding electrode portion 22 and the vertex of the second shape of the liquid 50 ( Figure 8B The arrow in FIG. 5 indicates the distance D6).

[0115] Thus, in this embodiment, the distance from the liquid 50 to the protruding electrode portion 22 (D4 or D6) is less than the distance from the liquid 50 to the peripheral electrode portion 21 (D3 or D5). Furthermore, in this embodiment, the distance from the liquid 50 to the protruding electrode portion 22 is shorter than the distance from the liquid 50 to the peripheral electrode portion 21 (D4 < D3 or D6 < D5). More specifically, the distance from the liquid 50 to the protruding electrode portion 22 (D4 or D6) is preferably less than or equal to 9 / 10 of the distance from the liquid 50 to the peripheral electrode portion 21 (D3 or D5).

[0116] Furthermore, within an imaginary plane VP1 including the central axis P1 of the discharge electrode 1 and the tip of the protruding electrode portion 22, the inclination angles θ1 and θ2 of the imaginary line connecting the liquid 50 and the tip of the protruding electrode portion 22 relative to the central axis P1 of the discharge electrode 1 are 67 degrees or less. The inclination angles θ1 and θ2 of the imaginary line relative to the central axis P1 of the discharge electrode 1 are more preferably 65 degrees or less, and even more preferably 62 degrees or less.

[0117] Here, the above-mentioned distances D3 to D6 and the inclination angles θ1 and θ2 are preferably Figure 8A The liquid 50 is shown in an extended state (first shape) and Figure 8B This holds true in the illustrated state where the liquid 50 is contracted (second shape).

[0118] The electrode assembly 3 of this embodiment, by adopting the aforementioned relationship between distances D1 to D6, offers the following advantages. Specifically, because the distance D1 from the peripheral electrode portion 21 to the discharge portion 11 is greater than the distance D2 from the protruding electrode portion 22 to the discharge portion 11, when a voltage is applied between the discharge electrode 1 and the counter electrode 2, the electric field acting between the protruding electrode portion 22 and the discharge portion 11 becomes dominant. This facilitates the generation of corona discharge. Consequently, glow discharge or arc discharge, which can cause dielectric breakdown, is less likely to occur, and the resulting decrease in the production efficiency of the active ingredient due to glow discharge or arc discharge is less likely to occur.

[0119] Furthermore, when the liquid 50 held by the discharge electrode 1 is subjected to the force generated by the electric field, forming a Taylor cone, the distance D3 from the (extended) liquid 50 to the peripheral electrode portion 21 is longer than the distance D4 from the liquid 50 to the protruding electrode portion 22. Consequently, the electric field tends to concentrate between the tip (apex) of the Taylor cone and the protruding electrode portion 22. Consequently, a relatively high-energy discharge occurs between the liquid 50 and the protruding electrode portion 22, further developing the corona discharge generated in the liquid 50 held by the discharge electrode 1 to a higher-energy discharge. Consequently, a discharge path L1, at least partially experiencing dielectric breakdown, is formed between the discharge electrode 1 and the counter electrode 2.

[0120] However, in Figure 8A and Figure 8B In this embodiment, the liquid 50 in the discharge device 10 is maintained in a stable state. As used herein, "stable state" means that the amount of liquid 50 held by the discharge electrode 1 is maintained at a substantially constant level. Specifically, the amount of liquid 50 supplied from the liquid supply unit 5 to the discharge electrode 1 is substantially balanced by the amount of liquid 50 released from the discharge device 10 by electrostatic atomization, resulting in a substantially constant, stable level of liquid 50. The aforementioned distances D3 to D6 are defined based on the liquid 50 in this stable state.

[0121] In addition, in the present embodiment, as described above, the top end of the liquid 50 in the extended state is located at the same position as the outer peripheral edge 210 of the peripheral electrode portion 21 or at a position closer to the discharge electrode 1 than the outer peripheral edge 210 in the direction along the central axis P1 of the discharge electrode 1 (see FIG. Figure 8A ). That is, Figure 8A As shown, the apex (top) of the liquid 50 in the extended state (first shape) is located in the Z-axis direction at the same position as the outer peripheral edge 210 of the peripheral electrode portion 21 or closer to the discharge electrode 1 side (the negative side of the Z-axis) than the outer peripheral edge 210. That is, when a plane perpendicular to the Z-axis and including the outer peripheral edge 210 of the peripheral electrode portion 21 is assumed, the apex (top) of the liquid 50 in the first shape is located within the plane or closer to the negative side of the Z-axis than the plane.

[0122] With this configuration, the electric field constantly exerts a force on the liquid 50 held by the discharge electrode 1, attracting it toward the peripheral electrode portion 21. In short, the peripheral electrode portion 21 and the protruding electrode portion 22 of the counter electrode 2, through which the electric field acts on the liquid 50, are always located on the positive side of the Z axis when viewed from the liquid 50. This constantly exerts a force attracting the liquid 50 in the positive direction of the Z axis. Therefore, when the liquid 50 held by the discharge electrode 1 mechanically vibrates, for example, a force constantly acts on the liquid 50, attracting it toward the peripheral electrode portion 21. This allows the amplitude of the liquid 50 to be suppressed. In other words, even when the liquid 50 contracts, it is biased toward the peripheral electrode portion 21, preventing it from becoming completely flattened. The deformation of the liquid 50 caused by the mechanical vibration of the liquid 50 can be minimized. As a result, the vibration frequency of the liquid 50 can be increased, thereby improving the efficiency of generating effective ingredients.

[0123] In addition, if Figure 1A and Figure 1BAs shown, in the absence of liquid 50, the structure of the discharge device 10 of this embodiment is as follows. Specifically, the discharge device 10 of this embodiment includes a discharge electrode 1, an opposing electrode 2, and a voltage application circuit 4. The discharge electrode 1 is a columnar electrode. The opposing electrode 2 faces the discharge electrode 1. The voltage application circuit 4 generates a discharge by applying an applied voltage V1 between the discharge electrode 1 and the opposing electrode 2. The opposing electrode 2 includes a peripheral electrode portion 21 and a protruding electrode portion 22. The peripheral electrode portion 21 protrudes toward the side opposite to the discharge electrode 1. An opening 23 is formed at the top surface of the peripheral electrode portion 21. The protruding electrode portion 22 protrudes from the peripheral electrode portion 21 into the opening 23. In the direction along the central axis P1 of the discharge electrode 1, the top end of the discharge electrode 1 is located closer to the discharge electrode 1 than the outer edge 210 of the peripheral electrode portion 21.

[0124] In this manner, even when the tip of the discharge electrode 1 is located closer to the discharge electrode 1 than the outer edge 210 of the peripheral electrode portion 21 along the central axis P1 of the discharge electrode 1, the same effects as described above can be expected. Specifically, the electric field can constantly exert a force on the liquid 50 held by the discharge electrode 1, drawing the liquid 50 toward the peripheral electrode portion 21. As a result, the vibration frequency of the liquid 50 can be increased, thereby improving the efficiency of generating the active ingredient.

[0125] (2.4) Discharge method

[0126] Below, refer to Figures 9A to 9C The following describes in detail the form of discharge that occurs when the applied voltage V1 is applied between the discharge electrode 1 and the counter electrode 2 . Figures 9A to 9C This is a conceptual diagram used to illustrate the discharge form. Figures 9A to 9C The discharge electrode 1 and the counter electrode 2 are schematically shown in FIG. In addition, in the discharge device 10 of this embodiment, the liquid 50 is actually held in the discharge electrode 1, and discharge is generated between the liquid 50 and the counter electrode 2. Figures 9A to 9C The liquid 50 is omitted from the illustration. The following description assumes that the liquid 50 does not exist in the discharge portion 11 of the discharge electrode 1. However, if the liquid 50 exists, the "discharge portion 11 of the discharge electrode 1" may be replaced with "the liquid 50 held in the discharge electrode 1" with respect to the location where the discharge occurs.

[0127] Here, first refer to Figure 9A Explain corona discharge.

[0128] Generally, when energy is input between a pair of electrodes to generate discharge, the discharge form develops from corona discharge to glow discharge or arc discharge depending on the amount of energy input.

[0129] Glow discharge and arc discharge are discharges accompanied by insulation breakdown between a pair of electrodes. In the case of glow discharge and arc discharge, the discharge path formed by insulation breakdown is maintained while energy is input between the pair of electrodes, thereby continuously generating a discharge current between the pair of electrodes. Figure 9A As shown, corona discharge is a discharge that occurs locally at one electrode (discharge electrode 1) and is not accompanied by dielectric breakdown between a pair of electrodes (discharge electrode 1 and opposing electrode 2). In short, by applying an external voltage V1 between the discharge electrode 1 and the opposing electrode 2, a localized corona discharge occurs at the discharge portion 11 of the discharge electrode 1. Here, the discharge electrode 1 is located on the negative (grounded) side, so the corona discharge generated at the discharge portion 11 of the discharge electrode 1 is a negative polarity corona. At this time, a region A1 where dielectric breakdown occurs may occur locally around the discharge portion 11 of the discharge electrode 1. This region A1 is not a long-extending shape in a specific direction like the first dielectric breakdown region A3 and the second dielectric breakdown region A4 described later in the case of localized dielectric breakdown discharge, but is instead point-shaped (or spherical).

[0130] Here, if the current capacity that can be discharged per unit time between the pair of electrodes from the power supply (voltage applying circuit 4) is sufficiently large, the discharge path once formed is maintained uninterrupted, and the corona discharge progresses to the glow discharge or arc discharge as described above.

[0131] Next, refer to Figure 9B This indicates that the entire circuit is undergoing breakdown discharge.

[0132] like Figure 9B As shown, full-path breakdown discharge is a discharge form in which corona discharge intermittently and repeatedly develops and reaches full-path breakdown between a pair of electrodes (discharge electrode 1 and opposing electrode 2). In other words, for full-path breakdown discharge, a discharge path L1 is generated between the discharge electrode 1 and the opposing electrode 2, in which the entire insulation between the discharge electrode 1 and the opposing electrode 2 is broken down. At this time, a region A2 of overall insulation breakdown is generated between the discharge portion 11 of the discharge electrode 1 and the opposing electrode 2 (the corner 222 of any protruding electrode portion 22). This region A2 is not generated locally, as in the first insulation breakdown region A3 and the second insulation breakdown region A4 described later in the case of localized breakdown discharge, but is generated in a manner that connects the discharge portion 11 of the discharge electrode 1 and the opposing electrode 2.

[0133] "Insulation breakdown," as used herein, refers to the breakdown of the insulating properties of the insulator (including gas) separating the conductors. For example, ionized molecules are accelerated by an electric field, collide with other gas molecules, ionizing them. This sudden increase in ion concentration causes gas discharge, leading to insulation breakdown.

[0134] In addition, although full-path breakdown discharge is accompanied by insulation breakdown (full-path breakdown) between a pair of electrodes (discharge electrode 1 and opposing electrode 2), the insulation breakdown does not occur continuously but intermittently. Therefore, the discharge current generated between the pair of electrodes (discharge electrode 1 and opposing electrode 2) is also generated intermittently. That is, in cases such as when the power supply (voltage application circuit 4) does not have the current capacity required to maintain the discharge path L1 as described above, as soon as the corona discharge develops into full-path breakdown, the voltage applied between the pair of electrodes drops, thereby interrupting the discharge path L1 and stopping the discharge. The "current capacity" mentioned here refers to the capacity of the current that can be discharged per unit time. By repeatedly generating and stopping the discharge as described above, the discharge current flows intermittently. In this way, full-path breakdown discharge differs from glow discharge and arc discharge in which insulation breakdown occurs continuously (that is, the discharge current is continuously generated) in that it repeats the state of high discharge energy and the state of low discharge energy.

[0135] Next, refer to Figure 9C This shows local breakdown discharge.

[0136] During a localized breakdown discharge, the discharge device 10 first generates a localized corona discharge in the discharge portion 11 of the discharge electrode 1. In this embodiment, the discharge electrode 1 is located on the negative (grounded) side, so the corona discharge generated in the discharge portion 11 of the discharge electrode 1 is negative-polarity corona. The discharge device 10 further develops the corona discharge generated in the discharge portion 11 of the discharge electrode 1 into a high-energy discharge. This high-energy discharge forms a discharge path L1 between the discharge electrode 1 and the counter electrode 2, which partially breaks down the insulation.

[0137] In addition, although the local breakdown discharge is accompanied by partial insulation breakdown between a pair of electrodes (discharge electrode 1 and opposing electrode 2), the insulation breakdown does not occur continuously but intermittently. Therefore, the discharge current generated between the pair of electrodes (discharge electrode 1 and opposing electrode 2) is also generated intermittently. That is, in cases such as when the power supply (voltage application circuit 4) does not have the current capacity required to maintain the discharge path L1, as soon as the corona discharge develops into a local breakdown discharge, the voltage applied between the pair of electrodes drops, thereby interrupting the discharge path L1 and stopping the discharge. By repeatedly generating and stopping the discharge as described above, the discharge current flows intermittently. In this way, the local breakdown discharge is different from the glow discharge and arc discharge in which insulation breakdown occurs continuously (that is, the discharge current is continuously generated) in that the discharge energy is high and the discharge energy is low.

[0138] More specifically, the discharge device 10 applies an external voltage V1 between the discharge electrode 1 and the counter electrode 2, which are arranged to face each other with a gap therebetween, thereby generating a discharge between the discharge electrode 1 and the counter electrode 2. Furthermore, when the discharge occurs, a discharge path L1 is formed between the discharge electrode 1 and the counter electrode 2, which is partially dielectrically broken. Figure 9C As shown, the discharge path L1 formed at this time includes a first dielectric breakdown region A3 formed around the discharge electrode 1 and a second dielectric breakdown region A4 formed around the counter electrode 2 .

[0139] That is, a discharge path L1 is formed between the discharge electrode 1 and the counter electrode 2, which is not a path of complete insulation breakdown, but rather a path of partial (local) insulation breakdown. Thus, in terms of localized breakdown discharge, the discharge path L1 formed between the discharge electrode 1 and the counter electrode 2 is a path of partial insulation breakdown, not a path of complete insulation breakdown.

[0140] Here, the first insulation breakdown region A3 and the second insulation breakdown region A4 exist separately and do not contact each other. In other words, the discharge path L1 includes an area (insulated area) that has not undergone insulation breakdown, at least between the first insulation breakdown region A3 and the second insulation breakdown region A4. Therefore, with respect to partial breakdown discharge, in the space between the discharge electrode 1 and the opposing electrode 2, a discharge current flows through the discharge path L1, even when the space has not undergone full insulation breakdown but has undergone partial insulation breakdown. In short, even if the discharge path L1 has undergone partial insulation breakdown, in other words, even if the discharge path L1 has not undergone partial insulation breakdown, a discharge current still flows between the discharge electrode 1 and the opposing electrode 2 through the discharge path L1, causing discharge.

[0141] Here, the second insulation breakdown region A4 is basically generated around the portion of the counter electrode 2 where the distance (spatial distance) to the discharge portion 11 is the shortest. In this embodiment, at the corner 222 of the protruding electrode portion 22, the distance D2 (see Figure 1B ) is shortest, so a second insulation breakdown region A4 is generated around the corner 222. In other words, Figure 9C The protruding electrode portion 22 shown actually corresponds to the corner portion 222 .

[0142] Furthermore, for full circuit breakdown discharge (refer to Figure 9B ) or partial breakdown discharge (refer to Figure 9C ) compared to corona discharge (reference Figure 9A) generates free radicals with greater energy, generating approximately 2 to 20 times as many free radicals as corona discharge. The free radicals generated in this way are not limited to sterilization, deodorization, moisturizing, preservation, and virus inactivation, but also have useful effects in a variety of situations. Here, when free radicals are generated by full-circuit breakdown discharge or partial-circuit breakdown discharge, ozone is also produced. However, while full-circuit breakdown discharge or partial-circuit breakdown discharge generates approximately 2 to 20 times more free radicals than corona discharge, the amount of ozone produced is suppressed to the same level as with corona discharge.

[0143] In addition, for partial breakdown discharge (see Figure 9C ) is different from the full circuit breakdown discharge (refer to Figure 9B Compared to full-path breakdown discharge, partial breakdown discharge can suppress the disappearance of free radicals caused by excessive energy, thereby improving the efficiency of free radical generation compared to full-path breakdown discharge. Specifically, full-path breakdown discharge has excessively high discharge energy, causing some of the generated free radicals to disappear, potentially reducing the efficiency of generating effective components. In contrast, partial breakdown discharge has a lower discharge energy than full-path breakdown discharge, thus reducing the amount of free radicals that disappear due to exposure to excessive energy and improving the efficiency of free radical generation.

[0144] Furthermore, compared to full-circuit breakdown discharge, the concentration of the electric field is alleviated for partial breakdown discharge. Therefore, for full-circuit breakdown discharge, a large discharge current instantly flows between the discharge electrode 1 and the opposing electrode 2 through the discharge path that has been completely broken down, and the resistance at that time becomes very small. In contrast, for partial breakdown discharge, the concentration of the electric field is alleviated, so that when the discharge path L1, which has been partially broken down by insulation, is formed, the maximum value of the current instantly flowing between the discharge electrode 1 and the opposing electrode 2 is suppressed to a value smaller than that of full-circuit breakdown discharge. Therefore, compared to full-circuit breakdown discharge, partial breakdown discharge can suppress the generation of nitrogen oxides (NOx), further minimizing electrical noise.

[0145] In this embodiment, as described above, the counter electrode 2 includes a plurality of (here, four) protruding electrode portions 22, and the distance D2 (see FIG. 2 ) from each protruding electrode portion 22 to the discharge electrode 1 is Figure 1B ) is uniform for the plurality of protruding electrode portions 22. Therefore, the region A2 undergoing insulation breakdown or the second insulation breakdown region A4 is generated around the corner portion 222 of a certain protruding electrode portion 22 among the plurality of protruding electrode portions 22. Here, the protruding electrode portion 22 where the region A2 undergoing insulation breakdown or the second insulation breakdown region A4 is generated is not limited to a specific protruding electrode portion 22, but is randomly determined among the plurality of protruding electrode portions 22.

[0146] (2.5) Liquid vibration frequency

[0147] Next, the principle of increasing the vibration frequency of the liquid 50 will be described.

[0148] In this embodiment, as described above, the liquid 50 held in the discharge portion 11 of the discharge electrode 1 is subjected to the force generated by the electric field, causing it to expand and contract along the central axis P1 of the discharge electrode 1 (i.e., along the Z-axis). Furthermore, even when the liquid 50 is contracted, it is biased toward the peripheral electrode portion 21, thereby minimizing the deformation of the liquid 50 caused by the mechanical vibration of the liquid 50. Consequently, the discharge device 10 of this embodiment can increase the vibration frequency of the liquid 50, thereby improving the efficiency of generating the active ingredient.

[0149] Specifically, the peripheral electrode portion 21 and the protruding electrode portion 22 of the counter electrode 2, which exert an electric field between themselves and the liquid 50, are always located on the positive side of the Z axis when viewed from the liquid 50. This allows a force to constantly act on the liquid 50, attracting it in the positive direction of the Z axis. Thus, the discharge device 10 can constantly bias the liquid 50 toward the counter electrode 2 in the direction along the central axis P1 of the discharge electrode 1 (i.e., the Z axis). Consequently, the discharge device 10 can minimize the deformation of the liquid 50 caused by mechanical vibrations. Consequently, the vibration frequency of the liquid 50 can be increased, leading to improved production efficiency of the active ingredient.

[0150] Furthermore, in the discharge device 10 of this embodiment, the voltage application circuit 4 varies the applied voltage V1 at a driving frequency corresponding to the natural vibration frequency of the liquid 50. Specifically, as described above, the frequency at which the applied voltage V1 varies, i.e., the driving frequency, is set to a value within a predetermined range that includes the resonant frequency (natural vibration frequency) of the liquid 50 held by the discharge electrode 1, i.e., to a value near the resonant frequency of the liquid 50. This causes the liquid 50 to deform more significantly, resulting in a more pointed (acute-angled) top portion (apex) of the Taylor cone formed by the liquid 50 when an electric field acts on it, thus facilitating discharge in the discharge device 10.

[0151] Furthermore, in this embodiment, the driving frequency is set to a frequency greater than the natural vibration frequency of the liquid 50. In short, the discharge device 10 of this embodiment can minimize the deformation of the liquid 50 caused by the mechanical vibration of the liquid 50, thereby increasing the vibration frequency of the liquid 50. Therefore, by setting the driving frequency, which is the frequency of the fluctuation of the applied voltage V1, to a value greater than the natural vibration frequency of the liquid 50, the vibration frequency of the liquid 50 can be maximized. Specifically, it is preferable to set the driving frequency to a value greater than the center frequency within a predetermined range with a lower and upper limit defined based on the natural vibration frequency (resonance frequency) of the liquid 50. More preferably, the driving frequency is set to near the upper limit of the predetermined range. This biases the liquid 50 in a direction that attracts it toward the peripheral electrode portion 21, thereby minimizing the deformation of the liquid 50 caused by the mechanical vibration of the liquid 50 and, in a complementary manner, increasing the vibration frequency of the liquid 50. As a result, in the discharge device 10 of the present embodiment, the vibration frequency of the liquid 50 can be increased, and the generation efficiency of the effective component can be improved.

[0152] (3) Modification

[0153] Implementation 1 is only one of the various implementations of the present disclosure. Implementation 1 can be modified in various ways, depending on the design, etc., as long as it can achieve the purpose of the present disclosure. In addition, the figures referenced in the present disclosure are schematic diagrams, and the size and thickness ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. The following lists variations of Implementation 1. The variations described below can be appropriately combined and applied.

[0154] The counter electrode 2 may also have an appropriate number of protruding electrode portions 22, not limited to four. For example, the counter electrode 2 may have an odd number of protruding electrode portions 22. The number of protruding electrode portions 22 included in the counter electrode 2 is not limited to four, and may be one, two, three, or five or more. Furthermore, it is not essential that the plurality of protruding electrode portions 22 be arranged at equal intervals in the circumferential direction of the opening 23. The plurality of protruding electrode portions 22 may also be arranged at appropriate intervals in the circumferential direction of the opening 23.

[0155] The liquid supply unit 5 for generating the charged microparticle liquid may be omitted from the discharge device 10. In this case, the discharge device 10 generates air ions by discharge (full-path breakdown discharge or partial breakdown discharge) generated between the discharge electrode 1 and the counter electrode 2.

[0156] The liquid supply unit 5 is not limited to a structure that cools the discharge electrode 1 to generate condensed water on the discharge electrode 1 as in the first embodiment. The liquid supply unit 5 may also be a structure that uses a supply mechanism such as capillary action or a pump to supply the liquid 50 from a tank to the discharge electrode 1. The liquid 50 is not limited to water (including condensed water) and may be a liquid other than water.

[0157] Alternatively, the voltage application circuit 4 may be configured to set the discharge electrode 1 to the positive electrode (positive) and the counter electrode 2 to the negative electrode (ground), thereby applying a high voltage between the discharge electrode 1 and the counter electrode 2. Furthermore, since a potential difference (voltage) is sufficient between the discharge electrode 1 and the counter electrode 2, the voltage application circuit 4 may also set the electrode on the higher potential side (positive electrode) to ground and the electrode on the lower potential side (negative electrode) to a negative potential, thereby applying a negative voltage to the electrode device 3. In other words, the voltage application circuit 4 may set the discharge electrode 1 to ground and the counter electrode 2 to a negative potential, or alternatively, set the discharge electrode 1 to a negative potential and the counter electrode 2 to ground.

[0158] Alternatively, limiting resistor R1 may be inserted between voltage generating circuit 41 and discharge electrode 1. In this case, since discharge electrode 1 is the negative electrode (grounded), limiting resistor R1 is inserted between the low-potential output terminal of voltage generating circuit 41 and electrode assembly 3. Alternatively, if discharge electrode 1 is the positive electrode (positive) and counter electrode 2 is the negative electrode (grounded), limiting resistor R1 may be inserted between the high-potential or low-potential output terminal of voltage generating circuit 41 and electrode assembly 3. Limiting resistor R1 is not a required component and may be omitted as appropriate.

[0159] The discharge electrode 1 and the counter electrode 2 are not limited to titanium alloy (Ti alloy) and may be, for example, a copper alloy such as copper-tungsten alloy (Cu-W alloy). Furthermore, the discharge electrode 1 is not limited to a tapered shape and may have a bulging tip, for example.

[0160] The high voltage applied from the voltage applying circuit 4 to the electrode device 3 is not limited to approximately 6.0 kV, and may be appropriately set according to, for example, the shapes of the discharge electrode 1 and the counter electrode 2 or the distance therebetween.

[0161] Furthermore, the same functions as those of the voltage applying circuit 4 in the first embodiment can also be realized by using a control method, a computer program, or a storage medium storing a computer program for the voltage applying circuit 4. Specifically, the functions corresponding to the control circuit 43 can also be realized by using a control method, a computer program, or a storage medium storing a computer program for the voltage applying circuit 4.

[0162] Furthermore, when comparing two values, the phrase "above" encompasses both the case where the two values ​​are equal and the case where one of the two values ​​exceeds the other. However, the present disclosure is not limited to this, and "above" as used herein may be synonymous with "greater than," which simply encompasses the case where one of the two values ​​exceeds the other. In other words, whether or not the case where the two values ​​are equal can be arbitrarily changed based on settings such as thresholds, so there is no technical difference between "above" and "greater than." Similarly, "less than" may be synonymous with "less than."

[0163] (Implementation Method 2)

[0164] The discharge device 10 of this embodiment is as follows Figures 10A to 10D As shown, the shapes of the counter electrodes 2A to 2D are different from those of the discharge device 10 of Embodiment 1. Hereinafter, the same components as those of Embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Figures 10A to 10D This is a schematic plan view showing counter electrodes 2A to 2D according to the second embodiment.

[0165] Figure 10A The counter electrode 2A shown is configured such that a plurality (two in this case) of protruding electrode portions 22 are arranged in the Y-axis direction. Figure 10A In the example, when viewed from one side of the central axis P1 of the discharge electrode 1, that is, when viewed from above, the protruding electrode portion 22 is triangular in shape. The "triangular shape" mentioned in the present disclosure is not limited to a triangle with three vertices, but also includes Figure 10A As shown in the protruding electrode portion 22, the tip thereof has an R-surface (curved surface) shape.

[0166] Figure 10B The counter electrode 2B shown has four triangular protruding electrode portions 22 in a plan view. Figure 10B In the figure, when the positive direction of the X-axis (right) is defined as "0 degrees" and the positive direction of the Y-axis (upward) is defined as "90 degrees", the four protruding electrode portions 22 are respectively arranged at positions of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

[0167] Figure 10C The counter electrode 2C shown has four triangular protruding electrode portions 22 in a plan view. Figure 10C In the figure, when the positive direction of the X-axis (right) is defined as "0 degrees" and the positive direction of the Y-axis (upward) is defined as "90 degrees", the four protruding electrode portions 22 are respectively arranged at positions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees.

[0168] exist Figure 10DIn the illustrated counter electrode 2D, the peripheral electrode portion 21 and the protruding electrode portion 22 are independent of each other. In this case, the protruding electrode portion 22 also protrudes from a portion of the circumference of the peripheral electrode portion 21 toward the central axis P1 of the discharge electrode 1 when viewed from the side of the central axis P1 of the discharge electrode 1. In this case, the protruding electrode portion 22 is fixed to the peripheral electrode portion 21 using an appropriate joining method (welding, screwing, caulking, etc.).

[0169] In the present embodiment, the extension portion 25 extending outward from the peripheral electrode portion 21 is omitted. However, the present invention is not limited to this structure, and the counter electrodes 2A to 2D may also include the extension portion 25 .

[0170] And, not limited to Figures 10A to 10D For example, the discharge electrode 1 and the counter electrode 2 in the electrode assembly 3 can have any appropriate shape. As an example, the peripheral electrode portion 21 of the counter electrode 2 can have any appropriate shape, such as a circle, an ellipse, a triangle, a quadrilateral, or another polygonal shape, when viewed from above. The outer diameter, inner diameter, and thickness of the peripheral electrode portion 21 can have any values. Similarly, the protruding electrode portion 22 of the counter electrode 2 can have any appropriate shape, such as a needle, a triangle, a quadrilateral, or another polygonal shape, when viewed from above. The protruding amount, width, and thickness of the protruding electrode portion 22 can have any values.

[0171] The various structures (including modified examples) described in the second embodiment can be appropriately combined with the various structures (including modified examples) described in the first embodiment and can be adopted.

[0172] (Summarize)

[0173] As described above, the discharge device (10) of the first embodiment includes a discharge electrode (1), an opposing electrode (2, 2A to 2D), a voltage application circuit (4), and a liquid supply unit (5). The discharge electrode (1) is a columnar electrode. The opposing electrode (2, 2A to 2D) is opposite to the discharge electrode (1). The voltage application circuit (4) generates discharge by applying an external voltage (V1) between the discharge electrode (1) and the opposing electrode (2, 2A to 2D). The liquid supply unit (5) supplies liquid (50) to the discharge electrode (1). The liquid (50) expands and contracts along the central axis (P1) of the discharge electrode (1) due to the discharge. The opposing electrode (2, 2A to 2D) includes a peripheral electrode unit (21) and a protruding electrode unit (22). The peripheral electrode unit (21) protrudes toward the side opposite to the discharge electrode (1), and an opening (23) is formed on the top surface. The protruding electrode portion (22) protrudes from the peripheral electrode portion (21) into the opening portion (23). In the direction along the central axis (P1) of the discharge electrode (1), the top end of the liquid (50) in the extended state is located at the same position as the outer peripheral edge (210) of the peripheral electrode portion (21) or at a position closer to the discharge electrode (1) than the outer peripheral edge (210).

[0174] According to this method, since the peripheral electrode portion (21) protrudes toward the side opposite to the discharge electrode (1) and has an opening (23) formed on its top surface, a force is exerted on the liquid (50) held on the discharge electrode (1) by the electric field, attracting the liquid toward the peripheral electrode portion (21). Furthermore, in the direction along the central axis (P1) of the discharge electrode (1), the top end of the liquid (50) in the extended state is located at the same position as the outer peripheral edge (210) of the peripheral electrode portion (21) or at a position closer to the discharge electrode (1) than the outer peripheral edge (210). Therefore, when the liquid (50) held on the discharge electrode (1) is mechanically vibrated, for example, a force in the direction of attraction toward the peripheral electrode portion (21) is continuously exerted on the liquid (50), thereby suppressing the amplitude of the liquid (50) to be small. That is, the deformation of the liquid (50) caused by the mechanical vibration of the liquid (50) can be suppressed to a small value, and as a result, the vibration frequency of the liquid (50) can be increased, and the generation efficiency of the effective component can be improved.

[0175] According to the first aspect, in the discharge device (10) of the second aspect, the protruding electrode portion (22) is arc-shaped when viewed from one side of the central axis (P1) of the discharge electrode (1).

[0176] According to this method, the concentration of the electric field at the protruding electrode portion (22) can be alleviated.

[0177] According to the first or second aspect, in the discharge device (10) of the third aspect, the counter electrode (2, 2A to 2D) has three or more protruding electrode portions (22).

[0178] According to this method, discharge can be generated in a dispersed manner at three or more protruding electrode portions (22).

[0179] According to any one of the first to third aspects, in the discharge device (10) of the fourth aspect, the distance (D4, D6) from the liquid (50) to the protruding electrode portion (22) is less than the distance (D3, D5) from the liquid (50) to the peripheral electrode portion (21).

[0180] According to this method, the electric field is easily concentrated between the liquid (50) and the protruding electrode portion (22), and discharge is easily generated between the liquid (50) and the opposing electrodes (2, 2A to 2D).

[0181] According to the fourth aspect, in the discharge device (10) of the fifth aspect, the distance (D4, D6) from the liquid (50) to the protruding electrode portion (22) is less than 9 / 10 of the distance (D3, D5) from the liquid (50) to the peripheral electrode portion (21).

[0182] According to this method, the electric field is easily concentrated between the liquid (50) and the protruding electrode portion (22), and discharge is easily generated between the liquid (50) and the opposing electrodes (2, 2A to 2D).

[0183] According to any one of the first to fifth aspects, in the discharge device (10) of the sixth aspect, an inclination angle (θ1, θ2) of an imaginary line connecting the liquid (50) and the tip of the protruding electrode portion (22) relative to the central axis (P1) of the discharge electrode (1) is 67 degrees or less in an imaginary plane (VP1). The imaginary plane (VP1) includes the central axis (P1) of the discharge electrode (1) and the tip of the protruding electrode portion (22).

[0184] According to this method, the electric field is easily concentrated between the liquid (50) and the protruding electrode portion (22), and in particular, the force that attracts the liquid (50) toward the opposing electrode (2, 2A to 2D) is easily applied to the liquid (50) along the central axis (P1) of the discharge electrode (1).

[0185] According to any one of the first to sixth aspects, in a seventh aspect of the discharge device (10), the counter electrode (2, 2A-2D) further includes an extension portion (25) extending outward from the peripheral electrode portion (21). The extension portion (25) is formed so as to become increasingly distant from the discharge electrode (1) in a direction along the central axis (P1) of the discharge electrode (1) as it becomes farther away from the peripheral electrode portion (21).

[0186] According to this method, it is possible to avoid the unnecessary electric field from being concentrated outside the peripheral electrode portion (21), and to easily generate an appropriate electric field that contributes to discharge.

[0187] According to any one of the first to seventh aspects, in the discharge device (10) of the eighth aspect, at least one of the following four portions of the opposing electrode (2, 2A to 2D) includes a curved shape. The first portion is the top surface (221) of the protruding electrode portion (22) when viewed from the side of the central axis (P1) of the discharge electrode (1). The second portion is the corner (222) of the protruding electrode portion (22) on the discharge electrode (1) side within a virtual plane (VP1) including the central axis (P1) of the discharge electrode (1) and the top of the protruding electrode portion (22). The third portion is the corner (211) of the peripheral electrode portion (21) on the discharge electrode (1) side within a virtual plane (VP1) including the central axis (P1) of the discharge electrode (1) and the top of the protruding electrode portion (22). The fourth portion is an inner surface (212) of the peripheral electrode portion (21) within a virtual plane (VP1) including the central axis (P1) of the discharge electrode (1) and the top end of the protruding electrode portion (22).

[0188] According to this aspect, it is possible to avoid excessive electric field concentration and easily generate an appropriate electric field that contributes to discharge.

[0189] According to the eighth aspect, in the discharge device (10) of the ninth aspect, the curvature radius of the curved shape of the top end surface (221) of the protruding electrode portion (22) is larger than the curvature radius of the curved shape of the corner portion (222) of the protruding electrode portion (22) on the discharge electrode (1) side.

[0190] According to this method, it is possible to avoid excessive electric field concentration on the top surface (221) of the protruding electrode portion (22), and it is easy to generate an appropriate electric field that contributes to discharge.

[0191] According to the eighth or ninth aspect, in the discharge device (10) of the tenth aspect, the curvature radius of the curved shape of the top end surface (221) of the protruding electrode portion (22) is smaller than the curvature radius of the curved shape of the inner surface (212) of the peripheral electrode portion (21).

[0192] According to this method, it is possible to avoid excessive electric field concentration on the inner surface (212) of the peripheral electrode portion (21), and to easily generate an appropriate electric field that contributes to discharge.

[0193] According to any one of the first to tenth aspects, in the discharge device (10) of the eleventh aspect, the voltage applying circuit (4) varies the applied voltage (V1) at a driving frequency corresponding to the natural vibration frequency of the liquid (50).

[0194] According to this embodiment, the change of the applied voltage (V1) can easily and efficiently contribute to the mechanical vibration of the liquid (50).

[0195] According to the eleventh aspect, in the discharge device (10) of the twelfth aspect, the driving frequency is a frequency equal to or higher than the natural vibration frequency of the liquid (50).

[0196] According to this embodiment, the vibration frequency of the liquid (50) can be increased, and the generation efficiency of the effective component can be improved.

[0197] The electrode device of the 13th embodiment is an electrode device used in the discharge device (10) of any one of the 1st to 12th embodiments, comprising a discharge electrode (1) and counter electrodes (2, 2A to 2D), and having an external voltage (V1) applied from a voltage application circuit (4).

[0198] According to this aspect, the production efficiency of the active ingredient can be improved.

[0199] The discharge device (10) of the fourteenth embodiment comprises a discharge electrode (1), an opposing electrode (2, 2A to 2D), and a voltage application circuit (4). The discharge electrode (1) is a columnar electrode. The opposing electrode (2, 2A to 2D) is opposite to the discharge electrode (1). The voltage application circuit (4) generates discharge by applying an external voltage (V1) between the discharge electrode (1) and the opposing electrode (2, 2A to 2D). The opposing electrode (2, 2A to 2D) comprises a peripheral electrode portion (21) and a protruding electrode portion (22). The peripheral electrode portion (21) protrudes toward the side opposite to the discharge electrode (1), and an opening portion (23) is formed on the top surface. The protruding electrode portion (22) protrudes from the peripheral electrode portion (21) into the opening portion (23). In a direction along the central axis (P1) of the discharge electrode (1), the tip of the discharge electrode (1) is located closer to the discharge electrode (1) than the outer peripheral edge (210) of the peripheral electrode portion (21).

[0200] According to this aspect, the production efficiency of the active ingredient can be improved.

[0201] The structures of the second to twelfth aspects are not essential structures of the discharge device (10) and can be omitted as appropriate.

[0202] The discharge device and the electrode device can be applied to a variety of uses, including refrigerators, washing machines, hair dryers, air conditioners, fans, air purifiers, humidifiers, facial beautifiers, and automobiles.

[0203] Description of Reference Numerals

[0204] 1. Discharge electrode; 2. 2A to 2D, opposing electrodes; 4. Voltage application circuit; 5. Liquid supply portion; 10. Discharge device; 21. Peripheral electrode portion; 22. Protruding electrode portion; 23. Opening portion; 25. Extension portion; 50. Liquid; 210. Outer periphery; 211. Corner; 212. Inner surface; 221. Top surface; 222. Corner; D3 to D6, distance; V1, applied voltage; VP1, imaginary plane.

Claims

1. A discharge device, wherein: The discharge device has: a discharge electrode, which is columnar; an opposing electrode, which is opposite to the discharge electrode; a voltage applying circuit for applying an external voltage between the discharge electrode and the counter electrode to generate discharge; as well as a liquid supply unit for supplying liquid to the discharge electrode; The liquid expands and contracts along the central axis of the discharge electrode due to discharge. The counter electrode has: a peripheral electrode portion having an opening formed therein; and a protruding electrode portion protruding from the peripheral electrode portion into the opening portion, In an imaginary plane including the central axis of the discharge electrode and the tip of the protruding electrode portion, an inclination angle of an imaginary line connecting the liquid and the tip of the protruding electrode portion with respect to the central axis of the discharge electrode is 67 degrees or less.

2. The discharge device according to claim 1, wherein When viewed from the side of the central axis of the discharge electrode, the outer peripheral edge of the protruding electrode portion is generally arc-shaped.

3. The discharge device according to claim 1 or 2, wherein: The distance from the liquid to the protruding electrode portion is less than or equal to the distance from the liquid to the peripheral electrode portion.

4. The discharge device according to claim 3, wherein: The distance from the liquid to the protruding electrode portion is 9 / 10 or less of the distance from the liquid to the peripheral electrode portion.

5. The discharge device according to claim 1 or 2, wherein: In the counter electrode, at least one of the top end surface of the protruding electrode portion when viewed from the side of the central axis of the discharge electrode, the corner of the protruding electrode portion on the discharge electrode side within an imaginary plane containing the central axis of the discharge electrode and the top end of the protruding electrode portion, the corner of the peripheral electrode portion on the discharge electrode side, and the inner surface of the peripheral electrode portion includes a curved shape.

6. The discharge device according to claim 5, wherein: The curvature radius of the curved shape of the distal end surface of the protruding electrode portion is larger than the curvature radius of the curved shape of the corner portion of the protruding electrode portion on the discharge electrode side.

7. The discharge device according to claim 5 or 6, wherein: The curvature radius of the curved shape of the distal end surface of the protruding electrode portion is smaller than the curvature radius of the curved shape of the inner surface of the peripheral electrode portion.

8. The discharge device according to claim 1 or 2, wherein: The voltage applying circuit varies the applied voltage at a driving frequency corresponding to a natural vibration frequency of the liquid.

9. The discharge device according to claim 8, wherein: The driving frequency is a frequency equal to or higher than the natural vibration frequency of the liquid.

10. The discharge device according to claim 1 or 2, wherein: The counter electrode has: a peripheral electrode portion protruding toward a side opposite to the discharge electrode and having an opening formed on a top surface thereof; as well as a protruding electrode portion protruding from the peripheral electrode portion into the opening portion, In a direction along a central axis of the discharge electrode, a tip of the discharge electrode is located closer to the discharge electrode than an outer peripheral edge of the peripheral electrode portion.

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