Electrostatic atomization device

Abstract

The purpose of the present invention is to improve the production efficiency of a functional substance. This electrostatic atomization device (10) is provided with a voltage application circuit (2). The voltage application circuit (2) applies an output voltage (Vo) to a load (4), thereby causing the liquid (50) held by the discharge electrode (41) to discharge. The voltage application circuit (2) performs an operation in which a plurality of modes including first to third modes are executed in a predetermined order as one cycle, and performs an operation in one cycle a plurality of times. The first mode is a mode in which the output voltage (Vo) increases over time. The second mode is a mode in which the output voltage (Vo) is maintained at a voltage equal to or greater than a predetermined value. The third mode is a mode in which the output voltage (Vo) is reduced over time. The predetermined size is 3 kV or more. The time from the start of the second mode to the end of the second mode is 40% or more of the length of one cycle.

Description

Technical Field

[0001] The present disclosure relates to an electrostatic atomization device. Background Art

[0002] The voltage application device (i.e., electrostatic atomization device) described in Patent Document 1 includes a voltage application circuit. The voltage application circuit applies a voltage to a load including a discharge electrode that holds liquid, thereby causing the liquid held by the discharge electrode to discharge. This discharge in the liquid held by the discharge electrode generates active ingredients such as free radicals.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-046635 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the voltage application device described in Patent Document 1, the liquid contracts relatively significantly when the voltage applied to the load is reduced. Therefore, when the voltage is subsequently increased, the liquid cannot sufficiently expand. As a result, the production efficiency of the functional substance may be reduced.

[0008] An object of the present disclosure is to provide an electrostatic atomization device capable of improving the generation efficiency of functional substances (eg, free radicals).

[0009] Solutions for solving problems

[0010] An electrostatic atomizer device according to one embodiment of the present disclosure includes a voltage application circuit. The voltage application circuit applies an output voltage to a load including a discharge electrode that holds the liquid, thereby causing the liquid held on the discharge electrode to discharge. The voltage application circuit sets a plurality of modes in a prescribed order as one cycle of action, and performs the one cycle of action multiple times. The plurality of modes include a first mode, a second mode following the first mode, and a third mode following the second mode. The first mode is a mode in which the output voltage increases over time. The second mode is a mode in which the output voltage is maintained at a voltage greater than a prescribed value. The third mode is a mode in which the output voltage decreases over time. The prescribed value of the output voltage is greater than 3 kV. The time from the start of the second mode to the end of the second mode is greater than 40% of the length of the one cycle.

[0011] Effects of the Invention

[0012] The present disclosure has the advantage of being able to improve the generation efficiency of functional substances such as free radicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a block diagram of the electrostatic atomization device involved in the embodiment.

[0014] Figure 2A Schematic diagram showing a state in which liquid held on a discharge electrode is extended in the electrostatic atomizer according to the embodiment.

[0015] Figure 2B This is a schematic diagram showing a state in which liquid held in a discharge electrode shrinks in the electrostatic atomizer according to the embodiment.

[0016] Figure 3A It is a perspective view showing a specific example of a discharge electrode and a counter electrode in the electrostatic atomizer device according to the embodiment.

[0017] Figure 3B yes Figure 3A X1-X1 line cross-sectional view.

[0018] Figure 4 It is a side view showing the shape of the tip of the discharge electrode according to the embodiment.

[0019] Figure 5 This is a circuit diagram showing an example of the electrostatic atomization device according to the embodiment.

[0020] Figure 6 It is a graph and a schematic diagram that schematically show the change in output voltage of the electrostatic atomization device involved in the embodiment and the expansion and contraction of the liquid.

[0021] Figure 7 It is a graph and a schematic diagram schematically showing the change in output voltage and expansion and contraction of the liquid of the electrostatic atomization device involved in the comparative example. DETAILED DESCRIPTION

[0022] (Implementation Method)

[0023] The electrostatic atomization device 10 involved in the embodiment is described below using the accompanying drawings. However, the embodiment described below is only one of the various embodiments disclosed herein. As long as the purpose of the present disclosure can be achieved, the embodiment described below can be modified in various ways according to the design, etc. In addition, the figures described in the following embodiments are schematic diagrams, and the size and thickness ratios of the components in the figures do not necessarily reflect the actual size ratios.

[0024] (1) Summary

[0025] First, refer to Figure 1 The outline of the electrostatic atomizer 10 according to this embodiment will be described. Figure 1 It is a block diagram of the electrostatic atomization device 10 according to the embodiment.

[0026] like Figure 1 As shown, the electrostatic atomizer 10 according to the present embodiment includes a voltage applying device 1 , a load 4 , and a liquid supply unit 5 .

[0027] The voltage applying device 1 applies a voltage Vo for generating discharge to a load 4 and includes a voltage applying circuit 2 and a detection circuit 3. That is, the electrostatic atomizing device 10 includes the voltage applying circuit 2. Hereinafter, the voltage Vo will be referred to as an output voltage Vo.

[0028] The load 4 includes a discharge electrode 41 and a counter electrode 42. The counter electrode 42 is disposed opposite the discharge electrode 41 with a gap therebetween. In other words, the discharge electrode 41 and the counter electrode 42 are disposed opposite each other. By applying an output voltage Vo between the discharge electrode 41 and the counter electrode 42, a discharge is generated between the discharge electrode 41 and the counter electrode 42.

[0029] The liquid supply unit 5 supplies the liquid 50 to the discharge electrode 41 .

[0030] Thus, the components of the electrostatic atomization device 10 involved in this embodiment include the voltage application circuit 2, the detection circuit 3, the liquid supply unit 5, the discharge electrode 41, and the counter electrode 42. However, the electrostatic atomization device 10 only needs to include the voltage application circuit 2 as a minimum component, and each of the detection circuit 3, the liquid supply unit 5, the discharge electrode 41, and the counter electrode 42 may not be included in the components of the electrostatic atomization device 10.

[0031] In the electrostatic atomization device 10 according to this embodiment, when the discharge electrode 41 holds the liquid 50, the voltage application circuit 2 applies an output voltage Vo between the discharge electrode 41 and the counter electrode 42. The state in which the discharge electrode 41 holds the liquid 50 is, for example, a state in which the liquid 50 adheres to the surface of the discharge electrode 41. That is, the voltage application circuit 2 applies the output voltage Vo to the load 4 including the discharge electrode 41 holding the liquid 50. As a result, the voltage application circuit 2 causes the liquid 50 held by the discharge electrode 41 to discharge. That is, the voltage application circuit 2 causes the load 4 including the discharge electrode 41 (more specifically, between the discharge electrode 41 and the counter electrode 42) to discharge. Consequently, the liquid 50 held by the discharge electrode 41 discharges, and the liquid 50 is electrostatically atomized. In this embodiment, the liquid 50 held by the discharge electrode 41, that is, the liquid 50 to be electrostatically atomized, is also simply referred to as "liquid 50."

[0032] The voltage application circuit 2 is electrically connected to the discharge electrode 41 and the counter electrode 42. Specifically, the counter electrode 42 is electrically connected to the positive terminal (e.g., +) of the voltage application circuit 2, and the discharge electrode 41 is electrically connected to the negative terminal (e.g., ground) of the voltage application circuit 2. The voltage application circuit 2 applies an output voltage Vo between the discharge electrode 41 and the counter electrode 42.

[0033] Moreover, the voltage applying circuit 2 generates a discharge between the discharge electrode 41 and the counter electrode 42 by applying the output voltage Vo to the load 4 (more specifically, between the discharge electrode 41 and the counter electrode 42). In particular, in the present embodiment, the voltage applying circuit 2 intermittently generates a discharge by periodically varying the magnitude of the output voltage Vo. That is, the output voltage Vo alternately repeats a period in which the output voltage Vo increases and becomes a high voltage and a period in which the output voltage Vo decreases and becomes a low voltage. Since the magnitude of the output voltage Vo varies periodically, the liquid 50 generates mechanical vibrations. In addition, the "high voltage" mentioned here is a voltage set to cause the discharge electrode 41 to generate a discharge, and as an example, it is a voltage with a peak value of about 7.0 kV. However, the voltage value of the output voltage Vo is not limited to about 7.0 kV, and may be determined, for example, according to the shape of the discharge electrode 41 and the counter electrode 42, or the distance W1 between the discharge electrode 41 and the counter electrode 42 (see below). Figure 3B ) etc. The voltage value of the output voltage Vo is appropriately set. Furthermore, the "low voltage" may be a voltage set to prevent discharge electrode 41 from generating a discharge. It may be a voltage lower than the "high voltage" described above, and may be either a voltage greater than 0V or 0V. Hereinafter, "periodically fluctuating the magnitude of the output voltage Vo" may be referred to as "periodically fluctuating the output voltage Vo."

[0034] Specifically, when the output voltage Vo is applied to the load 4, the liquid 50 held on the discharge electrode 41 is as follows: Figure 2A As shown, it extends due to the force generated by the electric field. Figure 2A : is a schematic diagram showing the state in which the liquid 50 held on the discharge electrode 41 in the electrostatic atomization device 10 involved in the embodiment is extended. As a result, the liquid 50 forms a conical shape called a Taylor cone. Moreover, discharge occurs because the electric field is concentrated at the top end (i.e., the vertex) of the Taylor cone. At this time, the sharper the top end of the Taylor cone, that is, the smaller the apex angle of the cone (i.e., the more acute the angle), the smaller the electric field intensity required for insulation breakdown, and the easier it is to generate discharge. In addition, during the period when the output voltage Vo is low voltage, the liquid 50 held on the discharge electrode 41 is as follows: Figure 2B As shown, the force generated by the electric field is reduced, and thus the circuit contracts compared to the period when the output voltage Vo is low. Figure 2BThis is a schematic diagram showing a state in which the liquid 50 held on the discharge electrode 41 in the electrostatic atomizer 10 according to the embodiment is contracted. As a result, the liquid 50 assumes a substantially spherical shape. Furthermore, by periodically varying the output voltage Vo, the liquid 50 held on the discharge electrode 41 is alternately deformed into various shapes in response to mechanical vibration. Figure 2A The shape and Figure 2B That is, the liquid 50 expands and contracts. As a result, the Taylor cone as described above is periodically formed, and thus the Taylor cone as described above is formed. Figure 2A The timing of the Taylor cone shown in FIG. 1 generates discharges intermittently. Figure 2A and Figure 2B In the figure, in order to easily distinguish the discharge electrode 41 and the liquid 50, dotted shadows are applied to the liquid 50.

[0035] Moreover, the electrostatic atomization device 10 generates free radicals by generating a discharge between the discharge electrode 41 and the counter electrode 42 of the load 4, and electrostatically atomizes the liquid 50 held on the discharge electrode 41. Moreover, the electrostatic atomization device 10 generates nano-sized charged microparticle liquid (for example, charged microparticle water) containing free radicals in the fine droplets of the liquid 50 after being electrostatically atomized. That is, the electrostatic atomization device 10 functions as a charged microparticle liquid generating device. In addition, the charged microparticle liquid can also be a liquid other than water. Hereinafter, free radicals and charged microparticle liquids are sometimes collectively referred to as functional substances or effective ingredients. In addition to having the effects of sterilization, deodorization, moisturizing the skin, preserving food (i.e., maintaining freshness), or inactivating viruses, functional substances also play a useful role in various scenarios.

[0036] Free radicals are also called free radicals. Free radicals are atoms or molecules that have unpaired electrons.

[0037] The electrostatic atomizer 10 generates a charged microparticle liquid containing free radicals, thereby achieving a longer lifespan of the free radicals compared to when the free radicals are released into the air as monomers. Furthermore, the charged microparticle liquid is, for example, nano-sized, thereby enabling the charged microparticle liquid to be suspended over a relatively wide range.

[0038] Furthermore, in the electrostatic atomizer 10 according to the present embodiment, the voltage applying circuit 2 performs a plurality of modes (i.e., a plurality of operation modes) in a predetermined order as one cycle of operation, and performs one cycle of operation multiple times (see the following description). Figure 6 ). The multiple modes include a first mode, a second mode following the first mode, and a third mode following the second mode.

[0039] Figure 6It is a graph and a schematic diagram schematically showing the change of the output voltage Vo of the electrostatic atomizer 10 and the expansion and contraction of the liquid 50 involved in the embodiment. Figure 6 In the example, the period T1 is the time from the start to the end of the first mode, the period T2 is the time from the start to the end of the second mode, and the period T3 is the time from the start to the end of the third mode.

[0040] The first mode increases the output voltage Vo over time. The second mode maintains the output voltage Vo at a predetermined level Vo2 or higher. The third mode decreases the output voltage Vo over time. The predetermined level Vo2 of the output voltage Vo is 3 kV or higher. The time from the start of the second mode to its end is at least 40% of the length of the aforementioned one cycle.

[0041] With the above configuration, the voltage application circuit 2 operates in the second mode, extending the time during which the output voltage Vo, which is a predetermined value greater than Vo2, is applied to the load 4 compared to when the circuit immediately transitions to the third mode after the first mode. This uniformizes the vibration of the liquid 50, allowing the liquid 50 to discharge while being uniformly stretched. This uniform discharge voltage allows discharge to be performed with a minimum applied voltage, improving the efficiency of generating the functional substance.

[0042] (2) Details

[0043] Next, refer to Figures 1 to 7 The electrostatic atomizer 10 according to this embodiment will be described in detail.

[0044] (2.1) Overall structure

[0045] like Figure 1 As shown, the electrostatic atomizer 10 according to this embodiment includes a voltage applying device 1, a load 4, and a liquid supply unit 5. The voltage applying device 1 includes a voltage applying circuit 2 and a detection circuit 3. The load 4 includes a discharge electrode 41, a counter electrode 42, and a housing 40 (see below). Figure 3A The liquid supply unit 5 supplies the liquid 50 to the discharge electrode 41 .

[0046] (2.1.1) Electrodes

[0047] Figure 3A It is a perspective view showing a specific example of the discharge electrode 41 and the counter electrode 42 in the electrostatic atomizer 10 according to the embodiment. Figure 3B yes Figure 3A The X1-X1 line cross-sectional view. Figure 3A and Figure 3BAs shown, the discharge electrode 41 and the counter electrode 42 are each held by a housing 40. The housing 40 has electrical insulation properties and is made of, for example, synthetic resin.

[0048] (Discharge electrode)

[0049] The discharge electrode 41 is a rod-shaped electrode. The discharge electrode 41 includes a shaft portion 41a and a base portion 41b. The shaft portion 41a is formed in a rod-like shape with a circular cross-section. The shaft portion 41a has a front end portion 411 at the first end in the longitudinal direction thereof. The base end portion 41b is continuously formed integrally at the second end in the longitudinal direction of the shaft portion 41a (the end on the opposite side to the front end portion 411). The shape of the base end portion 41b is a flat plate. The front end portion 411 is a tapered shape in which the cross-sectional area becomes smaller as it approaches the front end of the shaft portion 41a. That is, the discharge electrode 41 is a needle electrode in which the front end portion 411 is formed in a tapered shape. The "tapered shape" mentioned here is not limited to a shape with a sharp front end, such as Figure 2A and Figure 2B As shown, the shape includes a rounded front end.

[0050] Reference Figure 4 The shape of the front end portion 411 of the discharge electrode 41 will be described. Figure 4 : is a side view showing the shape of the tip of the discharge electrode 41 according to the embodiment. Figure 4 In order to easily distinguish the front end portion 411 and the liquid 50, dotted shadows are applied to the liquid 50.

[0051] The shape of the tip portion 411 of the discharge electrode 41 is, for example, a shape including a conical portion. Here, the conical portion is a conical shape. The shape of the portion of the tip portion 411 facing the counter electrode 42 (here, the shape of the tip of the conical portion) is, for example, an R shape. That is, the tip portion 411 is opposite to the base portion 41b side (see Figure 3B ) is an R-shape. The "R-shape" mentioned in this disclosure may include a case where the surface of a component has rounded corners (i.e., has rounded corners). The front end surface of the front end portion 411 of this embodiment includes a curved surface with convex rounded corners. The cross-sectional shape of the front end surface of the discharge electrode 41 of this embodiment, including the central axis of the discharge electrode 41, is continuously connected from the side surface of the front end portion 411. The cross-sectional shape of the front end surface of the discharge electrode 41, including the central axis of the discharge electrode 41, is formed into an arc shape and does not include any corners. In other words, the front end surface of the discharge electrode 41 is a curved surface (e.g., a curved surface) as a whole. For example, the shape of the front end portion 411 is hemispherical or approximately hemispherical.

[0052] The tip portion 411 includes a first portion 4111 and a second portion 4112. The first portion 4111 is disposed between the second portion 4112 and the base portion 41b. The first portion 4111 is cylindrical and flattened in the axial direction of the discharge electrode 41. The second portion 4112 is a portion of the tip portion 4111 that is farther from the base portion 41b than the first portion 4111. The second portion 4112 is conical. In short, the tip portion 411 includes the cylindrical first portion 4111 and the second portion 4112, which corresponds to the conical portion described above.

[0053] In addition, by applying a voltage between the discharge electrode 41 and the counter electrode 42, the liquid 50 held at the discharge electrode 41 is Figure 4 As shown in the figure, it takes on a conical shape called a Taylor cone due to the force generated by the electric field. Figure 4 As shown, the Taylor cone is conical along the conical portion (second portion 4112) of the tip portion 411 of the discharge electrode 41. The second portion 4112 of the tip portion 411 of the discharge electrode 41 is covered by the Taylor cone-shaped liquid 50. That is, in the electrostatic atomizer 10 according to this embodiment, the second portion 4112 constitutes a portion of the tip portion 411 covered by the Taylor cone-shaped liquid 50.

[0054] (Counter Electrode)

[0055] like Figure 3A and Figure 3B As shown, the counter electrode 42 is arranged so as to face the front end portion 411 of the discharge electrode 41. The counter electrode 42 includes, for example, a flat support portion 422, with a first recess 421 provided approximately in the center of the support portion 422. The first recess 421 is formed into a truncated cone shape by recessing the support portion 422 approximately in the center toward the discharge electrode 41. A boss 423 is integrally formed in the center of the bottom wall 4211 of the first recess 421. The boss 423 is formed into a truncated cone shape (e.g., a dome shape) by protruding a portion of the bottom wall 4211 of the first recess 421 toward the side opposite to the discharge electrode 41. In other words, by recessing the center of the bottom wall 4211 toward the side opposite to the discharge electrode 41, a truncated cone-shaped second recess 424 is formed in the bottom wall 4211.

[0056] The first recessed portion 421 is recessed in a direction opposite to the direction in which the boss portion 423 protrudes (i.e., the direction in which the second recessed portion 424 is recessed). A circular opening 4232 is formed in the center of the top wall 4231 of the boss portion 423 (more specifically, the bottom wall of the second recessed portion 424). The opening 4232 extends through the top wall 4231 along its thickness.

[0057] In this way, the counter electrode 42 includes: a first conical concave portion 421 that is concave toward the discharge electrode 41; a conical boss portion 423 that protrudes from the bottom wall 4211 of the first concave portion 421 in a direction away from the discharge electrode 41; and an opening portion 4232 formed on the top wall 4231 of the boss portion 423.

[0058] Here, the thickness direction of the counter electrode 42 (i.e., the direction through which the opening 4232 extends) coincides with the longitudinal direction of the discharge electrode 41. Furthermore, when viewed from above (i.e., viewed along the thickness direction of the counter electrode 42), the tip 411 of the discharge electrode 41 is located near the center of the opening 4232 of the counter electrode 42. Furthermore, when viewed perpendicular to the thickness direction of the counter electrode 42, the tip 411 of the discharge electrode 41 is located outside the second recess 424 of the counter electrode 42 and between the bottom wall 4211 of the first recess 421 and the base 41b of the discharge electrode 41. In other words, a gap (i.e., space) is ensured between the counter electrode 42 and the discharge electrode 41, at least by the opening 4241 of the second recess 424 of the counter electrode 42. In other words, the counter electrode 42 is positioned facing the discharge electrode 41 across a gap, and is spatially separated from the discharge electrode 41.

[0059] The boss portion 423 of the counter electrode 42 faces the discharge electrode 41 and is formed to be axially symmetrical with respect to the shaft portion 41a of the discharge electrode 41 when viewed from above. The periphery of the opening 4241 of the second recess 424 is an annular edge 425 that constitutes the boundary between the bottom wall 4211 and the boss portion 423. When viewed from above, the front end 411 of the discharge electrode 41 is located at the center of the annular edge 425. That is, the distance W1 between the annular edge 425 and the front end 411 (see FIG. 1 ) is 1 / 2. Figure 3B ) is equal around the entire circumference of the edge 425.

[0060] (2.1.2) Liquid supply unit

[0061] The liquid supply unit 5 supplies the liquid 50 for electrostatic atomization to the discharge electrode 41. As an example, the liquid supply unit 5 uses Figure 3B This is achieved by the cooling device 51 shown. Specifically, the liquid supply unit 5 includes the cooling device 51. The cooling device 51 cools the discharge electrode 41, causing condensed water to form as the liquid 50. Specifically, the cooling device 51 includes a pair of Peltier elements 511 and a pair of heat sinks 512. The pair of Peltier elements 511 are held by the pair of heat sinks 512. The cooling device 51 cools the discharge electrode 41 by applying power to the pair of Peltier elements 511. The pair of heat sinks 512 are held in the housing 40 by partially embedding each of the pair of heat sinks 512. At least the portion of the pair of heat sinks 512 that holds the Peltier elements 511 is exposed from the housing 40.

[0062] The pair of Peltier elements 511 are mechanically and electrically connected to the base end 41b of the discharge electrode 41, for example, by soldering. Furthermore, the pair of Peltier elements 511 are mechanically and electrically connected to the pair of heat sinks 512, for example, by soldering. Current is supplied to the pair of Peltier elements 511 via the discharge electrode 41 and the pair of heat sinks 512. The cooling device 51 constituting the liquid supply unit 5 cools the entire discharge electrode 41 via the base end 41b. As a result, moisture in the air condenses and adheres to the surface of the discharge electrode 41 as condensed water. This condensed water is retained on the discharge electrode 41 as liquid 50. In other words, the liquid supply unit 5 is configured to cool the discharge electrode 41 and generate condensed water as liquid 50 on the surface of the discharge electrode 41. With this configuration, the liquid supply unit 5 can utilize moisture in the air to supply liquid 50 (e.g., condensed water) to the discharge electrode 41, eliminating the need to supply (particularly actively supply) or replenish liquid to the electrostatic atomization device 10.

[0063] (2.1.3) Voltage application circuit and detection circuit

[0064] like Figure 1 As shown, the voltage application circuit 2 has a drive circuit 21 and a voltage generating circuit 22. The drive circuit 21 is a circuit that drives the voltage generating circuit 22. The voltage generating circuit 22 is a circuit that receives power from the power supply unit 6 and generates a voltage applied to the load 4, that is, an output voltage Vo. The power supply unit 6 is, for example, a power supply circuit that generates a DC voltage of several V to about ten V. In this embodiment, the power supply unit 6 is not included in the components of the voltage application device 1 for explanation, but the power supply unit 6 may also be included in the components of the voltage application device 1. The voltage application circuit 2 generates the output voltage Vo by periodically boosting the input voltage Vin from the power supply unit 6, and applies the output voltage Vo to the load 4.

[0065] The voltage application circuit 2 is electrically connected to the load 4. The voltage application circuit 2 applies a periodically varying output voltage Vo to the load 4. More specifically, the voltage application circuit 2 sets the discharge electrode 41 to a negative electrode (e.g., ground) and the counter electrode 42 to a positive electrode (e.g., +), and applies the output voltage Vo between the discharge electrode 41 and the counter electrode 42. When the voltage application circuit 2 applies the output voltage Vo to the load 4, a potential difference is generated between the discharge electrode 41 and the counter electrode 42, with the counter electrode 42 side at a high potential and the discharge electrode 41 side at a low potential.

[0066] As described above, the multiple modes of the voltage application circuit 2 include a first mode, a second mode following the first mode, and a third mode following the second mode. In addition, the multiple modes also include a fourth mode following the third mode. The fourth mode is a mode in which the output voltage Vo is maintained below a predetermined lower limit voltage. Figure 6 In the example, period T4 is the time from the start of the fourth mode to the end of the fourth mode. The voltage application circuit 2 sequentially executes the first mode, the second mode, the third mode, and the fourth mode as one cycle, and performs this cycle multiple times. That is, after the fourth mode, the first mode continues.

[0067] The first mode is a mode in which the output voltage Vo is increased over time. The second mode is a mode in which the output voltage Vo is maintained at a predetermined value Vo2 (see Figure 6 ) or above. In the second mode, insulation breakdown occurs between the discharge electrode 41 and the counter electrode 42, and discharge begins, generating an output current Io (i.e., discharge current). The third mode is a mode in which the output voltage Vo decreases over time. The third and fourth modes are modes for causing the output voltage Vo to become a voltage lower than the voltage at which discharge occurs, thereby interrupting the discharge. In other words, the third and fourth modes are modes for cutting off the output current Io. After the fourth mode, the voltage application circuit 2 increases the output voltage Vo again in the first mode, and generates discharge again in the second mode.

[0068] In the second mode, if Figure 6 As shown in the schematic diagram of , the liquid 50 maintains the extended state. In addition, in the second mode, discharge is generated at the tip portion 411 of the discharge electrode 41. As a result, the liquid 50 held at the tip portion 411 is electrostatically atomized.

[0069] By repeating the first to fourth modes, the output voltage Vo fluctuates periodically. Consequently, the electric field acting on the liquid 50 held by the discharge electrode 41 fluctuates periodically. As a result, the liquid 50 held by the discharge electrode 41 mechanically vibrates in accordance with the fluctuations in the output voltage Vo.

[0070] In this embodiment, the voltage application circuit 2 operates based on the monitoring object of the detection circuit 3. More specifically, the voltage application circuit 2 controls the output voltage Vo based on the monitoring object of the detection circuit 3. The "monitoring objects" here refer to the output current Io and output voltage Vo of the voltage application circuit 2. In other words, the detection circuit 3 detects the magnitude of the output voltage Vo and the output current Io.

[0071] like Figure 1As shown, the detection circuit 3 has a voltage detection circuit 31 and a current detection circuit 32. The voltage detection circuit 31 monitors the output voltage Vo of the voltage application circuit 2 to detect the magnitude of the output voltage Vo (i.e., the voltage value). Then, the voltage detection circuit 31 outputs a voltage detection signal Si1 containing data on the magnitude of the output voltage Vo to the drive circuit 21 of the voltage application circuit 2. The current detection circuit 32 monitors the output current Io of the voltage application circuit 2 to detect the magnitude of the output current Io (i.e., the current value). Then, the current detection circuit 32 outputs a current detection signal Si2 containing data on the magnitude of the output current Io to the drive circuit 21 of the voltage application circuit 2. The drive circuit 21 drives the voltage generating circuit 22 based on the voltage detection signal Si1 and the current detection signal Si2, and controls the output voltage Vo. In the control of the output voltage Vo, control can also be performed by controlling the value of the target voltage VoX maintained in the second mode.

[0072] In addition, since the output voltage Vo of the voltage applying circuit 2 (more specifically, Figure 5 Because there is a correlation between the voltage applied circuit 2's secondary-side voltage (more specifically, the isolation transformer 220's primary-side voltage) and the input voltage Vin of the voltage application circuit 2 (more specifically, the isolation transformer 220's primary-side voltage), the voltage detection circuit 31 can also indirectly detect the output voltage Vo based on the input voltage Vin. Similarly, because there is a correlation between the output current Io of the voltage application circuit 2 (more specifically, the isolation transformer 220's secondary-side current) and the input current of the voltage application circuit 2 (more specifically, the isolation transformer 220's primary-side current), the current detection circuit 32 can also indirectly detect the output current Io based on the input current.

[0073] (2.2) Circuit structure

[0074] Next, refer to the following Figure 5 The specific circuit configuration of the voltage applying device 1 will be described. Figure 5 1 is a circuit diagram schematically showing an example of the circuit structure of the electrostatic atomization device 10. Figure 5 In the figure, the power supply unit 6 is omitted.

[0075] As described above, the voltage applying circuit 2 includes the driving circuit 21 and the voltage generating circuit 22. Figure 5In the example shown, the voltage application circuit 2 is an isolated DC / DC converter and includes a boost circuit B1. The boost circuit B1 boosts the DC input voltage Vin (e.g., 13.8V) from the power supply unit 6 and outputs it as an output voltage Vo. Here, the voltage generating circuit 22 functions as the boost circuit B1. The output voltage Vo is applied to the load 4 (more specifically, the discharge electrode 41 and the counter electrode 42). That is, the voltage application circuit 2 applies the periodically fluctuating output voltage Vo to the load 4, causing the discharge electrode 41 to periodically discharge.

[0076] The voltage generating circuit 22 (for example, the booster circuit B1) includes an isolation transformer 220. The isolation transformer 220 includes a primary winding 221, a secondary winding 222, and an auxiliary winding 223. The primary winding 221 and the auxiliary winding 223 are electrically insulated from and magnetically coupled to the secondary winding 222. A counter electrode 42 is electrically connected to a first end of the secondary winding 222. Specifically, the booster circuit B1 includes the isolation transformer 220, which boosts the input voltage Vin input to the primary side (i.e., the primary winding 221 side) and outputs the output voltage Vo from the secondary side (i.e., the secondary winding 222 side), which is electrically connected to the load 4.

[0077] The drive circuit 21 includes a transistor Q1 and is configured to supply power to the primary winding 221 of the isolation transformer 220 through the switching operation of the transistor Q1. In addition to the transistor Q1, the drive circuit 21 also includes a microcontroller MC1 that drives the transistor Q1. As an example, the transistor Q1 is configured as an npn bipolar transistor.

[0078] The collector of transistor Q1 is connected to primary winding 221, and the emitter of transistor Q1 is connected to ground. Input voltage Vin is applied to the series circuit of primary winding 221 and transistor Q1 from power supply 6. The base of transistor Q1 is connected to the output port of microcontroller MC1 via resistor R1.

[0079] The drive circuit 21 is connected to a control power supply. The control power supply generates a control voltage Vcc (eg, 5V) and applies the control voltage Vcc to the microcontroller MC1.

[0080] With the above configuration, voltage application circuit 2 forms a separately excited converter. Specifically, microcontroller MC1 repeatedly turns transistor Q1 on and off, generating a pulsed voltage in primary winding 221. This induces a high voltage in secondary winding 222 of isolation transformer 220, which is then applied to load 4. Through these operations, voltage application circuit 2 generates output voltage Vo, a step-up from input voltage Vin, and applies this output voltage Vo to load 4.

[0081] Detection circuit 3 has Figure 5 The voltage detection circuit 31 and the current detection circuit 32 are shown.

[0082] Voltage detection circuit 31 includes diode D11, resistors R11-R13, and capacitor C11. The anode of diode D11 is connected to the first end of auxiliary winding 223. The second end of auxiliary winding 223 is connected to ground. The cathode of diode D11 is connected to the first end of capacitor C11 via resistor R11. The second end of capacitor C11 is connected to ground. Furthermore, the first end of capacitor C11 is connected to an input port of microcontroller MC1 via resistor R12 and to ground via the series circuit of resistors R12 and R13.

[0083] With the above configuration, the voltage detection circuit 31 indirectly monitors the output voltage Vo of the voltage application circuit 2 (i.e., the induced voltage of the secondary winding 222), which is the monitored target, by monitoring the induced voltage of the auxiliary winding 223. Specifically, the capacitor C11 is charged by the induced voltage of the auxiliary winding 223 via the diode D11 and the resistor R11. The voltage of the capacitor C11, divided by resistors R12 and R13, is input as the voltage detection signal Si1 to the input port of the microcontroller MC1. As the output voltage Vo increases, the voltage detection signal Si1 (for example, voltage) increases, and as the output voltage Vo decreases, the voltage detection signal Si1 decreases.

[0084] The current detection circuit 32 includes resistors R21 and R22 and capacitors C21 and C22. A control voltage Vcc is applied to the first end of resistor R21, and the second end of resistor R21 is connected to the first end of capacitor C21. The second end of capacitor C21 is connected to ground. The connection point between resistor R21 and capacitor C21 is connected to the second end of the secondary winding 222 of the isolation transformer 220. The second end of the secondary winding 222 is the end opposite the first end of the secondary winding 222. The first end of the secondary winding 222 is connected to the counter electrode 42. In other words, the control voltage Vcc is applied to the counter electrode 42 via the resistor R21 and the secondary winding 222. Furthermore, the second end of the secondary winding 222 is connected to ground via the series circuit of resistor R22 and capacitor C22. Furthermore, the voltage across capacitor C22 is input as a current detection signal Si2 to an input port of the microcontroller MC1. If the output current Io increases, the current detection signal Si2 increases; if the output current Io decreases, the current detection signal Si2 decreases.

[0085] The microcontroller MC1 monitors the output voltage Vo based on the voltage detection signal Si1 and the output current Io based on the current detection signal Si2 . The microcontroller MC1 then drives the transistor Q1 on and off based on the output voltage Vo and the output current Io.

[0086] (2.3) Discharge control

[0087] Figure 6 FIG. 2 shows the control of the output voltage Vo by the voltage applying circuit 2 and the expansion and contraction of the liquid 50 (for example, water) accompanying this control. Figure 6 In FIG, the horizontal axis represents time, the vertical axis represents voltage for the output voltage Vo, and the vertical axis represents the length of the liquid 50 (i.e., the length in the direction in which the discharge electrode 41 and the counter electrode 42 face each other) for the expansion and contraction of the liquid 50. Figure 6 A schematic diagram of the expansion and contraction of the liquid 50 is also shown.

[0088] By periodically changing the output voltage Vo by the voltage applying circuit 2, a discharge is periodically generated between the discharge electrode 41 and the counter electrode 42. In the load 4, a discharge is generated between the discharge electrode 41 and the counter electrode 42 due to the potential difference between the discharge electrode 41 and the counter electrode 42. Then, free radicals are generated by the discharge generated between the discharge electrode 41 and the counter electrode 42 of the load 4, and the liquid 50 held in the discharge electrode 41 is electrostatically atomized. Then, the electrostatic atomization device 10 generates a nano-sized charged microparticle liquid containing free radicals in the fine droplets of the electrostatically atomized liquid 50. The generated charged microparticle liquid is released to the surroundings of the electrostatic atomization device 10, for example, through the opening 4232 of the counter electrode 42.

[0089] If the period in which the voltage application circuit 2 changes the output voltage Vo is set as a discharge period, then in each discharge period, the voltage application circuit 2 first operates in the first mode to increase the output voltage Vo from the minimum value Vo1 to the prescribed size Vo2. Then, when the output voltage Vo reaches the prescribed size Vo2, the voltage application circuit 2 transfers to the second mode. The second mode is a mode in which the output voltage Vo is maintained at a target voltage VoX greater than the prescribed size Vo2. More specifically, in the second mode, the voltage application circuit 2 maintains the output voltage Vo at a voltage within a range below an upper limit voltage Vo3 greater than the target voltage VoX and greater than a prescribed size Vo2. The upper limit voltage is a prescribed multiple (for example, 1.2 times) of the target voltage VoX. The prescribed size Vo2 is a prescribed multiple (for example, 0.8 times) of the target voltage VoX. In other words, the upper limit voltage Vo3 is, for example, 1.5 times the prescribed size Vo2.

[0090] The difference between the target voltage VoX and the predetermined magnitude Vo2 is smaller than the difference between the predetermined magnitude Vo2 and the minimum value Vo1. In addition, the difference between the predetermined magnitude Vo2 and the upper limit voltage Vo3 is smaller than the difference between the predetermined magnitude Vo2 and the minimum value Vo1.

[0091] To generate a discharge, the predetermined magnitude Vo2 is 3 kV or greater. For example, the predetermined magnitude Vo2 is preferably 3 kV. In other words, the second mode is preferably a mode that maintains the output voltage Vo at a voltage of 3 kV or greater. The predetermined magnitude Vo2 is more preferably 3.5 kV. The predetermined magnitude Vo2 is more preferably 4 kV.

[0092] The voltage application circuit 2 controls the on / off ratio (ie, duty ratio) of the transistor Q1 to increase the output voltage Vo in the first mode and maintain the output voltage Vo in the second mode.

[0093] In the second mode, if Figure 6 As shown in the schematic diagram of , the liquid 50 is maintained in an extended state. During at least a portion of the time from the start of the second mode to the end of the second mode (ie, period T2), discharge occurs between the discharge electrode 41 and the counter electrode 42, and the liquid 50 is electrostatically atomized.

[0094] The voltage applying circuit 2 continues the second mode for a certain period of time. To this end, the microcontroller MC1 of the voltage applying circuit 2 includes a timer, and the timer is used to measure the time. Alternatively, a feedback circuit may be provided instead of the timer to measure the time based on the feedback cycle.

[0095] When the end time of the second mode arrives, the voltage application circuit 2 begins the third mode. The third mode is a mode in which the output voltage Vo decreases over time. In the third mode, the voltage application circuit 2 maintains the transistor Q1 in the off state, thereby decreasing the output voltage Vo over time. As a result, in the third mode, the output voltage Vo decreases to a voltage that prevents discharge.

[0096] The voltage applying circuit 2 executes the fourth mode following the third mode. Figure 6 The period T4 is the time from the start of the fourth mode to the end of the fourth mode. The fourth mode is a mode in which the output voltage Vo is maintained below a predetermined lower limit voltage. Figure 6 As shown, in the fourth mode, the voltage application circuit 2 maintains the output voltage Vo at a minimum value Vo1. In this embodiment, the minimum value Vo1 is 0V. In other words, in this embodiment, the fourth mode maintains the output voltage Vo at 0V. In other words, in the fourth mode, the voltage application circuit 2 does not apply the output voltage Vo to the load 4. The voltage application circuit 2 maintains the output voltage Vo at 0V by keeping the transistor Q1 off.

[0097] The minimum value Vo1 may be greater than 0 V. The voltage application circuit 2 may maintain the output voltage Vo below a lower limit voltage greater than 0 V in the fourth mode by controlling the on / off ratio (ie, duty cycle) of the transistor Q1 .

[0098] In the fourth mode, if Figure 6 As shown in the schematic diagram of FIG, the liquid 50 contracts.

[0099] The voltage applying circuit 2 continues the fourth mode for a certain period of time. To this end, the microcontroller MC1 of the voltage applying circuit 2 includes a timer, and the timer performs timing. Alternatively, a feedback circuit may be provided instead of the timer to perform timing based on the feedback cycle.

[0100] As a comparative example for this embodiment, Figure 7 2 shows the control of the output voltage Vo and the expansion and contraction of the liquid 50 (for example, water) accompanying this control when the voltage applying circuit 2 does not execute the second mode and the fourth mode, and a schematic diagram thereof. Figure 7 The graph and schematic diagram schematically show the change of the output voltage Vo of the electrostatic atomizer according to the comparative example and the expansion and contraction of the liquid 50. Figure 7 In the process, the control of increasing the output voltage Vo from the minimum value Vo4 to the maximum value Vo5 in the period T5 and the control of decreasing the output voltage Vo from the maximum value Vo5 to the minimum value Vo4 in the period T6 are repeated alternately. Figure 7 In the embodiment, the first mode and the third mode are repeated alternately.

[0101] On the other hand, the voltage application circuit 2 of this embodiment operates in the first to fourth modes. By operating the voltage application circuit 2 in the second mode, the time during which the output voltage Vo, which is greater than the predetermined value Vo2, is applied to the load 4 is prolonged compared to when the first mode is immediately followed by the third mode. Consequently, compared to the case where the first and third modes are alternately repeated as in the comparative example, discharge can be performed while the liquid 50 is uniformly extended, thereby improving the efficiency of generating the functional substance.

[0102] For example, the generation efficiency of the functional substance can be evaluated based on the amount of functional substance generated relative to the amount of ozone generated. It can be said that the greater the amount of functional substance generated relative to the amount of ozone generated, the higher the generation efficiency of the functional substance. By discharging while the liquid 50 is uniformly extended each time, the functional substance can be generated while suppressing the amount of ozone generated. In addition, the discharge energy between the discharge electrode 41 and the counter electrode 42 can be reduced, thereby suppressing not only the amount of ozone generated, but also the amount of NOx (for example, NO2, an environmental benchmark substance in the Basic Environmental Law) generated.

[0103] Furthermore, in the present embodiment, the generation efficiency of the functional material is improved compared to the comparative example, and therefore the discharge current (ie, the output current Io) can be suppressed.

[0104] Furthermore, the time from the start of the second mode to the end of the second mode can be sufficiently ensured as the time required for the liquid 50 to expand. In other words, the liquid 50 expands sufficiently. Therefore, discharge can be generated at a relatively low output voltage Vo.

[0105] In addition, as described above, since the magnitude of the output voltage Vo fluctuates periodically, mechanical vibrations are generated in the liquid 50. In the voltage application circuit 2 of this embodiment, the second mode is inserted between the first mode and the third mode to suppress the vibration (e.g., expansion and contraction) of the liquid 50, thereby suppressing the sound (e.g., discharge sound) generated by the vibration. Specifically, compared with the comparative example (refer to Figure 7 ), in this embodiment, as Figure 6 As shown, the expansion and contraction of the liquid 50 is suppressed.

[0106] In addition, the third mode is a mode for interrupting the discharge of the load 4. However, sometimes the period T3 of the third mode alone does not reach a period sufficient to interrupt the discharge. Therefore, by executing the fourth mode by the voltage application circuit 2, the discharge of the load 4 can be interrupted more reliably. If the discharge is not interrupted and continues for a long time, the front end shape of the liquid 50 may become rounded. In other words, if the discharge continues for a long time, the liquid 50 may not be able to maintain the Taylor cone shape. Therefore, it is difficult to generate functional substances even if the second mode is continued. In response to this, by interrupting the discharge in the fourth mode, the front end shape of the liquid 50 is reset (that is, the liquid 50 shrinks). As a result, the Taylor cone is reformed in the second mode of the next discharge cycle, making it easier to generate functional substances. In other words, the generation efficiency of functional substances is improved.

[0107] The voltage application circuit 2 performs the same control in each cycle (i.e., discharge cycle). Specifically, the voltage application circuit 2 sequentially operates in the first mode, the second mode, the third mode, and the fourth mode during each cycle. The length of one cycle is the sum of the lengths of the first mode, the second mode, the third mode, and the fourth mode (i.e., the sum of the lengths of periods T1, T2, T3, and T4).

[0108] The time from the start of the second mode to the end of the second mode (i.e., the length of period T2) is 40% or more of the length of one cycle. More specifically, the time from the start of the second mode to the end of the second mode is preferably 40% or more and 60% or less of the length of one cycle.

[0109] The time from the start of the fourth mode to the end of the fourth mode (i.e., the length of period T4) is preferably 5% or more and 40% or less of the length of one cycle. More specifically, the time from the start of the fourth mode to the end of the fourth mode is more preferably 20% or more and 40% or less of the length of one cycle.

[0110] The time from the start to the end of the first mode (that is, the length of the period T1 ) is preferably 5% to 15% of the length of one cycle.

[0111] The time from the start of the third mode to the end of the third mode (i.e., the length of period T3) is preferably 5% to 15% of the length of one cycle. Furthermore, the time from the start of the third mode to the end of the third mode is more preferably 10% or less of the length of one cycle.

[0112] The lengths of the periods T1 and T3 are determined, for example, depending on the characteristics of the isolation transformer 220. In addition, the periods T2 and T4 are completed under the control of the microcontroller MC1.

[0113] The length of one cycle is preferably within a predetermined range including the resonance period of the liquid 50. That is, the length of one cycle is preferably set to be close to the resonance period of the liquid 50.

[0114] Furthermore, the length of one cycle is preferably not less than 1 / 3000 second and not more than 1 / 100 second. In other words, the reciprocal of the length of one cycle is preferably not less than 100 Hz and not more than 3 kHz.

[0115] The resonance period of the liquid 50 is the period at which the amplitude of the vibration of the liquid 50 generated by fluctuations in the output voltage Vo reaches its maximum. The resonance period of the liquid 50 depends on the volume (i.e., amount) of the liquid 50 and is expressed as [1 / a·V - 0.5]. "V" is the volume of the liquid 50 held by the discharge electrode 41. "a" is a proportionality factor that depends on the surface tension and viscosity of the liquid 50 held by the discharge electrode 41.

[0116] For example, if the volume of the Taylor cone is 0.0917 mm 3 The volume of the second portion 4112 of the front end portion 411 is 0.0650 mm 3 , the volume of the liquid 50 forming the Taylor cone is 0.076 μL, and the resonance period of the liquid 50 is 0.33 msec. In this embodiment, the volume of the liquid 50 forming the Taylor cone is set to 0.46 μL, and the resonance period of the liquid 50 is set to 2 ms.

[0117] Specifically, the length of one cycle is preferably less than a first value and greater than a second value, the first value being the value obtained by adding half the resonance period to the resonance period, and the second value being the value obtained by subtracting half the resonance period from the resonance period. For example, if the resonance period is 2 msec, half the resonance period is 1 msec. In this case, the first value is 3 msec (= 2 msec + 1 msec) and the second value is 1 msec (= 2 msec - 1 msec). That is, the length of one cycle is selected from a range of greater than 1 msec and less than 3 msec. As a result, the generation efficiency of the functional substance can be further improved.

[0118] (3) Modification

[0119] The following are modified examples of the embodiment, which can be implemented by combining them as appropriate.

[0120] The counter electrode 42 is not limited to the shape of the above embodiment, and may be any shape as long as it generates discharge between the counter electrode 41. For example, the counter electrode 42 may include a needle-shaped protrusion and generate a dielectric breakdown region between the needle-shaped protrusion and the discharge electrode 41.

[0121] The liquid supply unit 5 is not limited to a configuration that cools the discharge electrode 41 to generate condensed water as in the above-described embodiment. The liquid supply unit 5 may also be configured to supply the liquid 50 from a tank to the discharge electrode 41 using a supply mechanism such as capillary action or a pump. Furthermore, the liquid 50 is not limited to water (including condensed water) and may be a liquid other than water.

[0122] The voltage application circuit 2 can also be configured such that the discharge electrode 41 is set to the positive electrode (e.g., +), the counter electrode 42 is set to the negative electrode (e.g., ground), and the output voltage Vo is applied between the discharge electrode 41 and the counter electrode 42. Furthermore, as long as a potential difference (e.g., voltage) is generated between the discharge electrode 41 and the counter electrode 42, the voltage application circuit 2 can also apply a negative voltage to the load 4 by setting the electrode on the higher potential side (e.g., the positive electrode) to ground and the electrode on the lower potential side (e.g., the negative electrode) to a negative potential. In other words, the voltage application circuit 2 can either set the discharge electrode 41 to ground and the counter electrode 42 to a negative potential, or set the discharge electrode 41 to a negative potential and the counter electrode 42 to ground.

[0123] The specific circuit structure of the voltage applying device 1 can be modified as appropriate. For example, the voltage applying circuit 2 is not limited to a separately excited converter and may also be a self-excited converter. Furthermore, the voltage generating circuit 22 may be implemented by a transformer having a piezoelectric element (e.g., a piezoelectric transformer).

[0124] The counter electrode 42 may be omitted in the electrostatic atomizer 10. In this case, discharge occurs between the discharge electrode 41 and a member (eg, a housing) existing around the discharge electrode 41.

[0125] The same functions as those of the voltage applying device 1 described above can also be specifically implemented by a control method, a computer program, or a recording medium having the computer program recorded thereon, for the voltage applying circuit 2. In other words, the functions of the voltage applying circuit 2 can also be specifically implemented by a control method, a computer program, or a recording medium having the computer program recorded thereon, for the voltage applying circuit 2.

[0126] The electrostatic atomization device 10 can also generate ions as functional substances.

[0127] The “monitoring object” of the detection circuit 3 may be at least one of the output current Io and the output voltage Vo of the voltage application circuit 2 .

[0128] The voltage application circuit 2 only needs to execute at least the first mode, the second mode, and the third mode, and does not necessarily need to execute the fourth mode.

[0129] The microcontroller MC1 of the above embodiment is used as a switch control device for driving the transistor Q1 as a switch. The switch control device is not limited to the microcontroller MC1 and may be composed of a plurality of discrete components.

[0130] (4) Summary

[0131] Based on the above-described embodiments and the like, the following aspects are disclosed.

[0132] The electrostatic atomization device (10) involved in the first embodiment includes a voltage application circuit (2). The voltage application circuit (2) applies an output voltage (Vo) to a load (4) including a discharge electrode (41) holding a liquid (50), thereby causing the liquid (50) held on the discharge electrode (41) to discharge. The voltage application circuit (2) performs a plurality of modes in a prescribed order as one cycle of action, and performs one cycle of action multiple times. The plurality of modes include a first mode, a second mode following the first mode, and a third mode following the second mode. The first mode is a mode in which the output voltage (Vo) increases over time. The second mode is a mode in which the output voltage (Vo) is maintained at a voltage greater than a prescribed magnitude (Vo2). The third mode is a mode in which the output voltage (Vo) decreases over time. The prescribed magnitude (Vo2) of the output voltage (Vo) is greater than 3 kV. The time from the start of the second mode to the end of the second mode is greater than 40% of the length of one cycle.

[0133] According to the above structure, by executing the second mode operation by the voltage application circuit (2), the time for applying the output voltage (Vo) greater than the predetermined magnitude (Vo2) to the load (4) is prolonged compared to the case where the operation is immediately transferred to the third mode after the first mode. As a result, the liquid (50) is discharged in a state where it is uniformly extended in each cycle, thereby improving the efficiency of generating the functional substance.

[0134] Furthermore, regarding the electrostatic atomizer (10) according to the second embodiment, in the first embodiment, the plurality of modes further includes a fourth mode following the third mode. The fourth mode is a mode for maintaining the output voltage (Vo) below a predetermined lower limit voltage.

[0135] According to the above structure, the discharge of the liquid (50) can be interrupted by the voltage applying circuit (2) performing the fourth mode operation. If the discharge is not interrupted, the shape of the front end of the liquid (50) becomes rounded, and thus, it is difficult to generate the functional substance even if the second mode is continued. In contrast, by interrupting the discharge, the shape of the front end of the liquid (50) is reset (that is, the liquid (50) shrinks), and the functional substance is easily generated in the second mode of the next cycle.

[0136] In addition, regarding the electrostatic atomizer (10) involved in the third embodiment, in the second embodiment, the fourth mode is a mode in which the output voltage (Vo) is maintained at 0V.

[0137] According to the above structure, the discharge of the liquid (50) can be interrupted more reliably.

[0138] In addition, regarding the electrostatic atomizer (10) involved in the fourth aspect, in the second aspect or the third aspect, the time from the start of the fourth mode to the end of the fourth mode is not less than 5% and not more than 40% of the length of one cycle.

[0139] According to the above structure, since the fourth mode lasts for a relatively long time, the discharge of the liquid (50) can be interrupted more reliably. In addition, compared with the case where the time from the start of the fourth mode to the end of the fourth mode exceeds 40% of the length of one cycle, the possibility of excessive contraction of the liquid (50) and a reduction in the production efficiency of the functional substance can be reduced.

[0140] Furthermore, regarding the electrostatic atomizer (10) according to the fifth aspect, in any one of the second to fourth aspects, the time from the start of the third mode to the end of the third mode is less than 10% of the length of one cycle.

[0141] According to the above structure, it is possible to adopt a structure in which the time from the start of the third mode to the end of the third mode is relatively short. Figure 5In the structure, this time is determined by the characteristics of the insulation transformer (220). Therefore, when a structure that can shorten this time is adopted, the degree of freedom in selecting the insulation transformer (220) is improved. Moreover, even if this time is relatively short, the time during which the output voltage (Vo) is low is lengthened by the voltage application circuit (2) performing the fourth mode operation. As a result, the discharge of the liquid (50) can be interrupted.

[0142] Furthermore, regarding the electrostatic atomization device (10) according to the sixth aspect, in any one of the first to fifth aspects, the length of one cycle is within a predetermined range including the resonance period of the liquid (50).

[0143] According to the above-mentioned structure, the production efficiency of the functional substance is improved.

[0144] Furthermore, regarding the electrostatic atomization device (10) according to the seventh aspect, in any one of the first to sixth aspects, the length of one cycle is not less than 1 / 3000 second and not more than 1 / 100 second.

[0145] According to the above-mentioned structure, the production efficiency of the functional substance is improved.

[0146] Regarding the structures other than the first embodiment, they are not necessary for the electrostatic atomization device (10) and can be appropriately omitted.

[0147] Description of Reference Numerals

[0148] 1: Voltage applying device; 2: Voltage applying circuit; 21: Drive circuit; 22: Voltage generating circuit; 220: Insulation transformer; 221: Primary winding; 222: Secondary winding; 223: Auxiliary winding; 3: Detection circuit; 31: Voltage detection circuit; 32: Current detection circuit; 4: Load; 40: Housing; 41: Discharge electrode; 41a: Shaft; 41b: Base end; 411: Front end; 4111: First portion; 4112: Second portion; 42: Counter electrode; 421: First recess; 4211: Bottom wall; 422: Support portion; 423: Boss portion; 4231: Top wall; 4232: Opening; 424: Second recess; 425: Edge; 10: Electrostatic atomization device; 50 : liquid; 51: cooling device; 511: Peltier element; 512: heat sink; 6: power supply unit; B1: boost circuit; C11: capacitor; C21: capacitor; C22: capacitor; D11: diode; Io: output current; MC1: microcontroller; Q1: transistor; R1: resistor; R11: resistor; R12: resistor; R13: resistor; R21: resistor; R22: resistor; Si1: voltage detection signal; Si2: current detection signal; Vcc: control voltage; Vin: input voltage; Vo: output voltage; Vo1: minimum value; Vo2: specified size; Vo3: upper limit voltage; Vo4: minimum value; Vo5: maximum value; VoX: target voltage; W1: distance.

Claims

1. An electrostatic atomizer comprising a voltage application circuit configured to apply an output voltage to a load including a discharge electrode for holding liquid, thereby causing the liquid held on the discharge electrode to discharge. The voltage application circuit performs a plurality of modes in a predetermined order as one cycle of operation, and performs the one cycle of operation multiple times. The plurality of modes include a first mode, a second mode subsequent to the first mode, and a third mode subsequent to the second mode, The first mode is a mode in which the output voltage increases with time. The second mode is a mode for maintaining the output voltage at a voltage greater than a predetermined level. The third mode is a mode in which the output voltage is reduced over time. The output voltage is set to be greater than 3 kV. The time from the start of the second mode to the end of the second mode is equal to or greater than 40% of the length of the one cycle.

2. The electrostatic atomization device according to claim 1, wherein: The plurality of modes further includes a fourth mode subsequent to the third mode, The fourth mode is a mode for maintaining the output voltage at or below a predetermined lower limit voltage.

3. The electrostatic atomization device according to claim 2, wherein: The fourth mode is a mode for maintaining the output voltage at 0V.

4. The electrostatic atomization device according to claim 2, wherein: The time from the start of the fourth mode to the end of the fourth mode is equal to or greater than 5% and equal to or less than 40% of the length of the one cycle.

5. The electrostatic atomization device according to claim 2, wherein: The time from the start of the third mode to the end of the third mode is less than or equal to 10% of the length of the one cycle.

6. The electrostatic atomization device according to claim 1, wherein: The length of one period is within a prescribed range including the resonance period of the liquid.

7. The electrostatic atomization device according to claim 1, wherein: The length of one cycle is greater than or equal to 1 / 3000 second and less than or equal to 1 / 100 second.

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