Ultrasonic atomization device and ultrasonic atomization method

Abstract

To provide an ultrasonic atomization device which can prevent failure of an ultrasonic vibrator by removing foams on a vibration surface of the ultrasonic vibrator.SOLUTION: An ultrasonic atomization device 10 comprises an atomization tank 11, an ultrasonic vibrator 20, a thickness vibration oscillation circuit and a control part. The atomization tank 11 is a tank for entry of liquid A1, and the ultrasonic vibrator 20 is installed on a bottom 12 of the atomization tank 11. The thickness vibration oscillation circuit outputs high-frequency power for generating thickness direction vibration in the ultrasonic vibrator 20. Further, a first operation mode in which the thickness vibration oscillation circuit outputs high-frequency power with first electric energy, and a second mode, in which the same outputs high-frequency power with second electric energy greater than the first electric energy, are set to the ultrasonic atomization device 10. The control part usually drives the thickness vibration oscillation circuit in the first operation mode, temporarily switches to the second operation mode every time a prescribed period of time passes and drives the thickness vibration oscillation circuit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ultrasonic atomization device and an ultrasonic atomization method for atomizing a liquid by ultrasonic waves. [Background technology]

[0002] Conventionally, ultrasonic atomization devices that atomize liquid by outputting ultrasonic waves from an ultrasonic vibrator are known (see, for example, Patent Document 1). Ultrasonic atomization devices generally have a structure in which an ultrasonic vibrator is installed at the bottom of an atomization tank containing liquid. When ultrasonic waves are output from the ultrasonic vibrator toward the liquid surface, the liquid is atomized. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-214664 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an ultrasonic atomizer, bubbles are generated around the ultrasonic vibrator when the ultrasonic vibrator is driven. The generated bubbles adhere to the vibration surface of the ultrasonic vibrator that is in contact with the liquid, which reduces the contact area between the vibration surface and the liquid, and this may result in poor vibration efficiency of the ultrasonic waves generated by the ultrasonic vibrator. Furthermore, if the vibration surface is covered with a large amount of generated bubbles, the vibration will occur without the liquid in contact with the vibration surface, causing the ultrasonic vibrator to run dry, which may result in the ultrasonic vibrator breaking down.

[0005] The present invention has been made in consideration of the above problems, and its object is to provide an ultrasonic atomization device and an ultrasonic atomization method that can prevent failure of the ultrasonic vibrator by removing bubbles on the vibrating surface of the ultrasonic vibrator. [Means for solving the problem]

[0006] In order to solve the above problem, the invention described in claim 1 is an ultrasonic atomization device comprising: an atomization tank for containing a liquid to be atomized; an ultrasonic vibrator installed at the bottom of the atomization tank; a thickness vibration oscillator circuit connected to the ultrasonic vibrator and outputting high-frequency power that generates thickness-directional vibration in the ultrasonic vibrator; and a control unit for driving the thickness vibration oscillator circuit, wherein a first operating mode in which the thickness vibration oscillator circuit outputs the high-frequency power with a first amount of power and a second operating mode in which the thickness vibration oscillator circuit outputs the high-frequency power with a second amount of power greater than the first amount of power are preset, and the control unit always drives the thickness vibration oscillator circuit in the first operating mode and temporarily switches to the second operating mode every time a predetermined period elapses to drive the thickness vibration oscillator circuit.

[0007] Therefore, according to the invention described in claim 1, the thickness vibration oscillation circuit is driven by switching to the second operation mode in which the second amount of power is larger than the first amount of power at predetermined intervals, thereby generating thickness direction vibration in the ultrasonic transducer. This removes bubbles on the vibration surface of the ultrasonic transducer, so that the liquid can be reliably brought into contact with the vibration surface, improving the vibration efficiency of the ultrasonic waves generated by the ultrasonic transducer. Furthermore, by oscillating with the liquid reliably in contact with the vibration surface, the ultrasonic transducer is prevented from running dry, so that the ultrasonic transducer can be prevented from breaking down. Moreover, the amount of power is not always increased to remove bubbles, but is temporarily increased to remove bubbles, so that the risk of the ultrasonic transducer breaking down can be reduced.

[0008] The invention described in claim 2 is based on claim 1, and its gist is that in the second operation mode, the high-frequency power is output at a current value set to be greater than the current value in the first operation mode.

[0009] Therefore, according to the invention described in claim 2, in the second operating mode, the amount of power is increased by increasing the current value rather than the voltage value, thereby further reducing the risk of failure of the ultrasonic transducer.

[0010] The invention described in claim 3 is based on claim 1, and its gist is that in the second operation mode, the high-frequency power is output at a current value set to be 1.9 times or more and 2.8 times or less the current value in the first operation mode.

[0011] Therefore, according to the invention described in claim 3, in the second operation mode, the current value is set to 1.9 times or more the current value in the first operation mode, so that many bubbles adhering to the vibration surface can be removed. Also, in the second operation mode, the current value is set to 2.8 times or less the current value in the first operation mode, so that the ultrasonic transducer can be prevented from being damaged due to application of a large current.

[0012] The invention described in claim 4 is characterized in that, in any one of claims 1 to 3, the control unit temporarily switches to the second operating mode every time a period of 5 minutes or more and 20 minutes or less has elapsed, and drives the thickness vibration oscillation circuit for 0.5 seconds or more and 10 seconds or less.

[0013] Therefore, in the invention described in claim 4, the switching to the second operation mode, which increases the amount of power applied to the thickness vibration oscillation circuit, is performed when a period of 5 minutes or more has elapsed, so that frequent application of power to the thickness vibration oscillation circuit can be suppressed. Therefore, it is possible to prevent a failure of the thickness vibration oscillation circuit caused by the application of power. In addition, bubbles on the vibration surface grow over time, but since the operation mode is switched to the second operation mode and the amount of power is increased every time a period of 20 minutes or less has elapsed, bubbles that remain small in size can be reliably removed from the vibration surface. If a period longer than 20 minutes has elapsed and the bubbles on the vibration surface become too large, there is a possibility that the bubbles cannot be removed even if the operation mode is switched to the second operation mode and the amount of power is increased. Furthermore, since the control unit drives the thickness vibration oscillation circuit for a period of 10 seconds or less, it is possible to prevent a failure of the thickness vibration oscillation circuit caused by the application of power.

[0014] The invention described in claim 5 is a method for atomizing a liquid by applying high-frequency power to an ultrasonic vibrator installed at the bottom of an atomization tank for containing the liquid to be atomized, and vibrating the ultrasonic vibrator in a thickness direction, wherein a first operating mode in which the high-frequency power of a first amount of power is applied to the ultrasonic vibrator, and a second operating mode in which the high-frequency power of a second amount of power greater than the first amount of power is applied to the ultrasonic vibrator are preset, and the liquid is atomized by always vibrating the ultrasonic vibrator in the thickness direction in the first operating mode, and bubbles are removed from the vibration surface of the ultrasonic vibrator by temporarily switching to the second operating mode every time a predetermined period of time has elapsed.

[0015] Therefore, according to the invention described in claim 5, every time a predetermined period of time has elapsed, the ultrasonic transducer is temporarily switched to a second operation mode in which the second amount of power is greater than the first amount of power, and vibrated in the thickness direction. This removes bubbles on the vibration surface of the ultrasonic transducer, so that the liquid can be reliably brought into contact with the vibration surface, and the vibration efficiency of the ultrasonic waves generated by the ultrasonic transducer is improved. Furthermore, by oscillating with the liquid reliably in contact with the vibration surface, the ultrasonic transducer is prevented from running dry, and therefore failure of the ultrasonic transducer can be prevented. Moreover, since the amount of power is not always increased to remove bubbles, but is temporarily increased to remove bubbles, the risk of failure of the ultrasonic transducer can be reduced. Effect of the Invention

[0016] As described above in detail, according to the inventions recited in claims 1 to 5, it is possible to provide an ultrasonic atomization device and an ultrasonic atomization method that can prevent breakdown of the ultrasonic vibrator by removing bubbles on the vibrating surface of the ultrasonic vibrator. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view showing an ultrasonic atomization device according to an embodiment of the present invention. [Diagram 2]1 is a photograph showing the vibration surface of an ultrasonic transducer in an initial state. [Diagram 3] FIG. 2 is a block diagram showing the electrical configuration of the ultrasonic atomization device. [Figure 4] A photograph showing the vibration surface of an ultrasonic transducer when the current value is adjusted to 0.8A. [Diagram 5] A photograph showing the vibration surface of an ultrasonic transducer when the current value is adjusted to 1.0 A. [Figure 6] A photograph showing the vibration surface of an ultrasonic transducer when the current value is adjusted to 1.1A. [Figure 7] A photograph showing the vibration surface of an ultrasonic transducer when the current value is adjusted to 1.3A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic atomization device according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] As shown in FIG. 1, the ultrasonic atomization device 10 includes an atomization tank 11 for containing the liquid A1 to be atomized. The ultrasonic atomization device 10 is a device that atomizes the liquid A1 by irradiating the liquid A1 in the atomization tank 11 with ultrasonic waves S1. The atomization tank 11 is substantially rectangular and has a bottom 12 and a pair of side walls 13 and 14 facing each other. In this embodiment, hypochlorous acid water is used as the liquid A1. For this reason, the atomization tank 11, which is a member that comes into contact with the liquid A1, is made of a material that is resistant to hypochlorous acid water, such as a resin material such as ABS resin (acrylonitrile butadiene styrene resin), PP resin (polypropylene resin), or PE resin (polyethylene resin).

[0020] As shown in Fig. 1 and Fig. 2, the ultrasonic atomization device 10 includes an ultrasonic vibrator 20. More specifically, a recess 16 that opens into the internal space 15 of the atomization tank 11 is formed in the center of the bottom 12 of the atomization tank 11. The recess 16 is circular in plan view, and the ultrasonic vibrator 20 is installed on the bottom surface. The ultrasonic vibrator 20 of this embodiment emits (outputs) ultrasonic waves S1 with a frequency of 2.4 MHz from a vibration surface 21. The ultrasonic vibrator 20 is disc-shaped with a bonding surface that is bonded to the bottom surface of the recess 16 and a non-bonding surface (vibration surface 21) located on the opposite side of the bonding surface, and is made of a piezoelectric ceramic material or the like.

[0021] Next, the electrical configuration of the ultrasonic atomization device 10 will be described.

[0022] 3, the ultrasonic atomization device 10 is provided with an oscillation substrate (not shown), and an electric circuit 30 is formed on the oscillation substrate. The electric circuit 30 includes a thickness vibration oscillation circuit 31, a drive circuit 32, and an output circuit 33.

[0023] The thickness vibration oscillator circuit 31 is electrically connected to the ultrasonic vibrator 20 via the drive circuit 32 and the output circuit 33. The thickness vibration oscillator circuit 31 outputs high-frequency power from the output circuit 33 to the ultrasonic vibrator 20 to generate thickness direction vibration. As a result, the ultrasonic vibrator 20 irradiates the liquid A1 in the atomization tank 11 with ultrasonic waves S1. The drive circuit 32 also has a function of guiding the high-frequency power output from the thickness vibration oscillator circuit 31 to the output circuit 33.

[0024] 3, the ultrasonic atomization device 10 of this embodiment includes a control device 41 (control unit). The control device 41 is configured by a known computer including a CPU, a ROM, a RAM, etc. The control device 41 is electrically connected to the thickness vibration oscillation circuit 31 and drives the thickness vibration oscillation circuit 31.

[0025] In this embodiment, a first operation mode and a second operation mode are set in advance as operation modes for generating thickness direction vibration in the ultrasonic transducer 20. In the first operation mode, the current value is set to 0.45 A or more and 0.55 A or less, and the thickness vibration oscillation circuit 31 outputs high-frequency power at a first power amount (about 10 W in this embodiment). This generates thickness direction vibration in the ultrasonic transducer 20, and the liquid A1 is atomized. In the second operation mode, the current value is set to a value (1.1 A in this embodiment) larger than the current value in the first operation mode, and the thickness vibration oscillation circuit 31 outputs high-frequency power at a second power amount (about 18 W in this embodiment) larger than the first power amount. This generates thickness direction vibration in the ultrasonic transducer 20, and the bubbles 22 on the vibration surface 21 of the ultrasonic transducer 20 are removed.

[0026] The control device 41 drives the thickness vibration oscillation circuit 31 in the first operation mode during normal atomization of the liquid A1. Then, the control device 41 switches to the second operation mode for temporarily removing the bubbles 22 every time a predetermined period of time elapses, and drives the thickness vibration oscillation circuit 31. In the second operation mode, the high-frequency power is outputted by setting a current value larger than the current value in the first operation mode. As a result, the second amount of power used in the second operation mode becomes larger than the first amount of power used in the first operation mode.

[0027] Next, a method for atomizing the liquid A1 using the ultrasonic atomization device 10 will be described.

[0028] First, the liquid A1 is placed in the atomization tank 11, and then the power supply (not shown) of the ultrasonic atomization device 10 is turned on. Next, the control device 41 controls the thickness vibration oscillation circuit 31 to output high-frequency power for generating thickness direction vibration in the ultrasonic vibrator 20. More specifically, the high-frequency power output from the thickness vibration oscillation circuit 31 is input to the output circuit 33 via the drive circuit 32.

[0029] The high-frequency power is then applied to the ultrasonic transducer 20, causing it to vibrate in the thickness direction. As a result, ultrasonic waves S1 are irradiated into the liquid A1 from the vibration surface 21 of the ultrasonic transducer 20. The ultrasonic waves S1 irradiated from the ultrasonic transducer 20 propagate through the liquid A1 and reach the liquid surface A2. At this time, ultrasonic energy is concentrated at a position above the ultrasonic transducer 20 on the liquid surface A2, causing the liquid A1 to rise. Then, at the tip of the raised liquid A1, a part of the liquid A1 is atomized and scattered as mist (droplets). As a result, the humidity of the space in which the ultrasonic atomization device 10 is installed is controlled.

[0030] During normal atomization of the liquid A1 as described above, the control device 41 vibrates the ultrasonic transducer 20 in the thickness direction in a first operation mode in which the thickness vibration oscillation circuit 31 outputs high-frequency power with a first power amount (approximately 10 W in this embodiment). However, while the ultrasonic transducer 20 is in operation, bubbles 22 continue to adhere to the vibration surface 21 of the ultrasonic transducer 20. These bubbles 22 prevent the liquid A1 from contacting the vibration surface 21, which can cause the ultrasonic transducer 20 to run dry, and therefore the bubbles 22 must be removed.

[0031] Therefore, the control device 41 temporarily switches to a second operation mode in which the thickness vibration oscillation circuit 31 outputs high-frequency power at a second power amount (about 18 W in this embodiment) larger than the first power amount every time a predetermined period (about 10 minutes in this embodiment) elapses, and vibrates the ultrasonic transducer 20 in the thickness direction. In the second operation mode, the high-frequency power is output by setting a current value (1.1 A in this embodiment) larger than the current value in the first operation mode (0.45 A or more and 0.55 A or less in this embodiment). As a result, in the second operation mode, the current value is 2 times or more and 2.5 times or less than the current value in the first operation mode. In addition, the second power amount is about 180% of the first power amount. Then, the control device 41 drives the thickness vibration oscillation circuit 31 in the second operation mode. In this embodiment, when the operation mode is switched to the second operation mode, the power amount changes abruptly from the first power amount to the second power amount. Furthermore, when switching to the second operation mode, high-frequency power with a larger amount of power than the second amount of power is instantaneously output, and the bubbles 22 attached to the vibration surface 21 of the ultrasonic transducer 20 are removed in the greatest amount. Therefore, the control device 41 only needs to drive the thickness vibration oscillator circuit 31 for a short period of time (1 second in this embodiment) in the second operation mode. Furthermore, if the thickness vibration oscillator circuit 31 is initially driven for a short period of time, most of the bubbles 22 are removed, so even if the thickness vibration oscillator circuit 31 is driven for a long period of time, only the few remaining bubbles 22 can be removed.

[0032] Next, the evaluation method and results of the ultrasonic atomization device will be described.

[0033] First, an ultrasonic atomization device similar to the ultrasonic atomization device 10 of this embodiment was prepared, and liquid was placed in the atomization tank of the ultrasonic atomization device. Next, the ultrasonic vibrator 20 provided in the ultrasonic atomization device was vibrated in the thickness direction, and bubbles 22 were attached to the vibration surface 21 of the ultrasonic vibrator 20. At this point, the ultrasonic vibrator 20 was in the initial state (see FIG. 2) before the bubbles 22 were removed. The current value applied to the ultrasonic vibrator 20 when it was in the initial state was set to 0.45 A or more and 0.55 A or less.

[0034] Next, the current value applied to the ultrasonic transducer 20 was gradually increased to verify the extent to which bubbles 22 could be removed when the current value was increased. Fig. 4 shows the ultrasonic transducer 20 when the current value was 0.8 A, Fig. 5 shows the ultrasonic transducer 20 when the current value was 1.0 A, Fig. 6 shows the ultrasonic transducer 20 when the current value was 1.1 A, and Fig. 7 shows the ultrasonic transducer 20 when the current value was 1.3 A.

[0035] As a result, it was confirmed that the bubbles 22 attached to the vibrating surface 21 could not be removed when the current value was increased to 0.8 A (see FIG. 4). Moreover, even when the current value was increased to 1.0 A, it was confirmed that the bubbles 22 attached to the vibrating surface 21 could not be removed, and only two bubbles 22 attached to the outer periphery of the vibrating surface 21 disappeared (see FIG. 5).

[0036] On the other hand, when the current value was increased to 1.1 A, it was confirmed that many of the bubbles 22 in the center of the vibration surface 21 could be removed (see FIG. 6) compared to the initial state (see FIG. 2). It is considered that more of the bubbles 22 were removed from the center because the ultrasonic transducer 20 oscillates more in the center than in the peripheral portion of the vibration surface 21 when vibrating in the thickness direction. It was also confirmed that when the current value was increased to 1.3 A, some of the bubbles 22 that could not be removed when the current value was 1.1 A could be removed (see FIG. 7). Furthermore, an attempt was made to increase the current value beyond 1.3 A, but the liquid A1 could not be atomized and the components on the oscillation board became too hot, so the operation of increasing the current value was stopped.

[0037] Therefore, according to this embodiment, the following effects can be obtained.

[0038] (1) In the ultrasonic atomization device 10 of the present embodiment, the thickness vibration oscillation circuit 31 is driven by switching to the second operation mode in which the second amount of power is larger than the first amount of power at predetermined intervals, thereby generating thickness direction vibration in the ultrasonic oscillator 20. This removes bubbles 22 on the vibration surface 21 of the ultrasonic oscillator 20, so that the liquid A1 can be reliably brought into contact with the vibration surface 21, improving the vibration efficiency of the ultrasonic waves S1 generated by the ultrasonic oscillator 20. In addition, by oscillating with the liquid A1 reliably in contact with the vibration surface 21, the ultrasonic oscillator 20 is prevented from running dry, and therefore failure of the ultrasonic oscillator 20 can be prevented.

[0039] (2) In this embodiment, the amount of power is not always increased to remove the bubbles 22, but the amount of power is temporarily increased to remove the bubbles 22 attached to the vibration surface 21. Moreover, in this embodiment, when the operation mode is switched to a mode for removing the bubbles 22 (second operation mode), high-frequency power with a large amount of power is output instantaneously, so that the bubbles 22 attached to the vibration surface 21 are removed most at the time of switching the mode. This allows the control device 41 to drive the thickness vibration oscillation circuit 31 only for a short time (1 second in this embodiment) in the second operation mode. As a result, the temperature rise of the ultrasonic transducer 20 is minimized, so that the risk of failure of the ultrasonic transducer 20 due to heat can be reduced, and thus the risk of failure of the circuits (thickness vibration oscillation circuit 31, drive circuit 32, and output circuit 33) that drive the ultrasonic transducer 20 can be reduced. In addition, the time during which the thickness vibration oscillation circuit 31 is driven by high-frequency power with a large amount of power is shortened, so that power consumption can be reduced.

[0040] (3) Japanese Patent No. 4961607 discloses a technology in which an ultrasonic vibrator is vibrated in the thickness direction during normal operation to atomize a liquid, and the ultrasonic vibrator is vibrated in the radial direction every time a predetermined period of time elapses to remove bubbles attached to the ultrasonic vibrator. However, in this case, two circuits are required: a thickness vibration oscillator circuit that generates thickness vibration in the ultrasonic vibrator, and a radial vibration oscillator circuit that generates radial vibration in the ultrasonic vibrator. In addition, the ultrasonic vibrator has different vibration conditions (such as vibration frequency) when vibrating in the thickness direction and when vibrating in the radial direction, so the efficiency of the ultrasonic vibrator may decrease. On the other hand, in this embodiment, only one oscillator circuit (thickness vibration oscillator circuit 31) can perform both the atomization of the liquid A1 and the removal of bubbles 22, so the manufacturing cost of the ultrasonic atomization device 10 can be reduced. In addition, in this embodiment, the frequency of vibration is constant, so the efficiency of the ultrasonic vibrator 20 is maintained constant.

[0041] The above embodiment may be modified as follows.

[0042] In the above embodiment, hypochlorous acid water is used as the liquid A1 put into the atomization tank 11, but the liquid is not limited to this, and pure water, tap water, or the like may also be used.

[0043] Although the atomization tank 11 in the above embodiment is formed in a substantially rectangular parallelepiped shape, it may be formed in other shapes, such as a substantially cubic shape or a substantially cylindrical shape.

[0044] In the second operation mode of the above embodiment, the amount of electric power (the second amount of electric power) is increased by setting a current value larger than the current value in the first operation mode. However, the amount of electric power may be increased by setting a voltage value larger than the voltage value in the first operation mode as long as the voltage value is large enough to prevent failure of the ultrasonic transducer 20.

[0045] In the above embodiment, the recess 16 is formed in the bottom 12 of the atomization tank 11, and the ultrasonic vibrator 20 is installed on the bottom surface of the recess 16. However, the installation manner of the ultrasonic vibrator 20 may be changed. For example, the ultrasonic vibrator 20 may constitute the bottom of the recess 16. Also, the recess 16 may be omitted, and the ultrasonic vibrator 20 may be installed on the bottom 12 of the atomization tank 11. Note that, although the recess 16 in the above embodiment is formed in the center of the bottom 12, it may be formed on the outer periphery of the bottom 12.

[0046] Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-mentioned embodiments will be listed below.

[0047] (1) The ultrasonic atomization device according to any one of claims 1 to 4, wherein the second amount of electric power is equal to or greater than 150% of the first amount of electric power.

[0048] (2) The ultrasonic atomization device according to claim 4, wherein the control unit drives the thickness vibration oscillation circuit for 0.5 seconds or more and 1 second or less in the second operation mode. [Explanation of symbols]

[0049] 10...Ultrasonic atomization device 11...Atomization tank 12...Bottom of atomization tank 20...Ultrasonic transducer 21...Vibration surface of ultrasonic transducer 22…foam 31…Thickness vibration oscillator circuit 41...Control device as a control unit A1…liquid

Claims

1. an atomization tank for containing a liquid to be atomized; An ultrasonic vibrator installed at the bottom of the atomization tank; a thickness vibration oscillation circuit connected to the ultrasonic transducer and outputting high-frequency power for generating a thickness direction vibration in the ultrasonic transducer; A control unit that drives the thickness vibration oscillation circuit; Equipped with A first operation mode in which the thickness vibration oscillation circuit outputs the high frequency power with a first power amount, and a second operation mode in which the thickness vibration oscillation circuit outputs the high frequency power with a second power amount larger than the first power amount are set in advance, The control unit always drives the thickness vibration oscillation circuit in the first operation mode, and temporarily switches the operation mode to the second operation mode every time a predetermined period elapses to drive the thickness vibration oscillation circuit.

1. An ultrasonic atomization device comprising:

2. 2 . The ultrasonic atomization device according to claim 1 , wherein in the second operation mode, the high-frequency power is outputted at a current value set to be larger than a current value in the first operation mode.

3. 2. The ultrasonic atomization device according to claim 1, wherein in the second operation mode, the high-frequency power is outputted at a current value set to be 1.9 times or more and 2.8 times or less than the current value in the first operation mode.

4. 4. The ultrasonic atomization device according to claim 1, wherein the control unit temporarily switches to the second operating mode every time a period of 5 minutes or more and 20 minutes or less has elapsed, and drives the thickness vibration oscillator circuit for a period of 0.5 seconds or more and 10 seconds or less.

5. A method for atomizing a liquid by applying high-frequency power to an ultrasonic vibrator installed at the bottom of an atomization tank for containing the liquid to be atomized, and vibrating the ultrasonic vibrator in a thickness direction, comprising: A first operation mode in which the high frequency power of a first power amount is applied to the ultrasonic transducer, and a second operation mode in which the high frequency power of a second power amount larger than the first power amount is applied to the ultrasonic transducer are set in advance, The ultrasonic vibrator is normally vibrated in the thickness direction in the first operation mode to atomize the liquid, and every time a predetermined period of time elapses, the operation mode is temporarily switched to the second operation mode to vibrate the ultrasonic vibrator in the thickness direction, thereby removing bubbles on the vibration surface of the ultrasonic vibrator.

1. An ultrasonic atomization method comprising:

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