JP7627845B2 - Liquid atomization system, mist generating system, and liquid atomization method - Google Patents

Description

The present disclosure relates generally to a liquid atomization system, a mist generating system, and a liquid atomization method, and more specifically to a liquid atomization system that atomizes a liquid, a mist generating system including the liquid atomization system, and a liquid atomization method.

Patent Document 1 describes a liquid atomization device that includes a SAW device and atomizes liquid supplied to the surface of the SAW device using surface acoustic waves. The SAW device in the liquid atomization device disclosed in Patent Document 1 has a set of comb-shaped electrodes formed on the surface of a substrate made of a piezoelectric ceramic material.

In the liquid atomization device disclosed in Patent Document 1, in the vicinity of a pair of comb electrodes of a SAW device, in the propagation region of the surface acoustic wave, within the range of the overlap width (crossing width) of the pair of comb electrodes, a number of liquid supply holes (through holes) penetrating the front and back surfaces are arranged in a row across the propagation direction of the surface acoustic wave.

In the liquid atomization device disclosed in Patent Document 1, a part of the surface acoustic wave propagates between two adjacent liquid supply holes, so energy loss of the surface acoustic wave is likely to occur. In addition, in the liquid atomization device disclosed in Patent Document 1, the liquid supply hole is circular, so the surface acoustic wave is likely to be reflected toward the outside of the propagation area, so energy loss of the surface acoustic wave is likely to occur. In addition, in the liquid atomization device disclosed in Patent Document 1, the liquid film thickness of the liquid supplied to the surface of the SAW device becomes unstable, making it difficult to stably generate droplet particles with nanometer-sized particle diameters. Here, "nanometer size" is 1 nm to 999 nm.

JP 2012-24646 A

The object of the present disclosure is to provide a liquid atomization system, a mist generating system, and a liquid atomization method that are capable of more stably generating droplet particles having nanometer-sized particle sizes.

A liquid atomization system according to one aspect of the present disclosure includes a SAW device, and atomizes a liquid supplied to the SAW device by surface acoustic waves. The SAW device includes a substrate, an IDT electrode, and a reflector. The substrate has a front surface and a back surface, and is piezoelectric. The IDT electrode has a pair of comb electrodes provided on the front surface of the substrate. The IDT electrode generates the surface acoustic wave in the substrate. The reflector is provided on the front surface of the substrate. The substrate has a through hole. The through hole penetrates the substrate in a thickness direction. The liquid is supplied to the through hole. When viewed from the thickness direction, the through hole is aligned with an intersection region of the pair of comb electrodes in the propagation direction of the surface acoustic wave. When viewed from the thickness direction, the through hole is formed at least between both ends of the intersection region in a direction perpendicular to the propagation direction of the surface acoustic wave. The substrate has a periphery of the through hole on the surface, which is located between the through hole and the intersection region of the IDT electrode in the propagation direction, as viewed from the thickness direction. The liquid atomization system atomizes at least an overflowing portion of the liquid by the surface acoustic wave. The overflowing portion is a portion of the liquid that overflows from the through hole beyond the periphery onto the propagation region of the surface acoustic wave on the substrate. As viewed from the thickness direction, the reflector, the IDT electrode, the propagation region, and the through hole are arranged in the order of the reflector, the IDT electrode, the propagation region, and the through hole. The reflector reflects the surface acoustic wave generated by the IDT electrode and propagating to the opposite side to the propagation region. The periphery has a first end and a second end, which are both ends in a direction perpendicular to the propagation direction. The inclination angle of the peripheral edge with respect to a virtual line that is orthogonal to the propagation direction and passes through at least one of the first end and the second end is −90 degrees or more and 45 degrees or less, when the IDT electrode side is taken as plus and the opposite side to the IDT electrode side is taken as minus with respect to the virtual line.

A mist generating system according to one aspect of the present disclosure includes the liquid atomization system and a liquid supply unit. The liquid supply unit supplies the liquid to the through hole from the back side of the substrate of the SAW device.

In one aspect of the liquid atomization method according to the present disclosure, liquid is atomized using the liquid atomization system.

FIG. 1 is a plan view of a liquid atomization system according to a first embodiment. FIG. 2 shows the liquid atomization system, taken along line AA of FIG. FIG. 3 is an explanatory diagram of the operation of the liquid atomization system. FIG. 4 is a partially cutaway plan view of a liquid nebulization system according to a first modified example of the first embodiment. FIG. 5 is a partially cutaway plan view of a liquid nebulization system according to a second modified example of the first embodiment. FIG. 6 is a partially cutaway plan view of a liquid nebulization system according to a third modified example of the first embodiment. FIG. 7 is a partially cutaway plan view of a liquid nebulization system according to a fourth modified example of the first embodiment. FIG. 8 shows the liquid atomization system of the above, and is a cross-sectional view taken along line AA of FIG. FIG. 9 is an explanatory diagram of the operation of the liquid atomization system. FIG. 10 is a partially cutaway plan view of a liquid nebulization system according to a fifth modified example of the first embodiment. FIG. 11 is a partially cutaway plan view of a liquid nebulization system according to a sixth modified example of the first embodiment. FIG. 12 is a cross-sectional view of a modified example of a mist generating system including the liquid atomization system of the first embodiment. FIG. 13 is a plan view of a mist generating system including a liquid atomization system according to the second embodiment. FIG. 14 is a plan view of a mist generating system according to the third embodiment.

Figures 1 to 14 described in the following embodiments 1 to 3 are schematic diagrams, and the ratios of sizes and thicknesses of each component in the figures do not necessarily reflect the actual dimensional ratios.

(Embodiment 1)
Hereinafter, a liquid atomization system 1 according to a first embodiment will be described with reference to FIGS.

(1) Overview The liquid atomization system 1 according to the first embodiment includes a SAW (Surface Acoustic Wave) device 5, and applies the energy of surface acoustic waves generated by the SAW device 5 to a liquid 100 (see FIG. 3) to atomize the liquid 100. In the liquid atomization system 1, droplet particles 103 (see FIG. 3) are generated by atomizing the liquid 100. Here, the SAW device 5 includes a substrate 2 and an IDT (Interdigital Transducer) electrode 3. The substrate 2 has piezoelectricity. The IDT electrode 3 generates surface acoustic waves in the substrate 2. In the liquid atomization system 1, the liquid 100 (see FIGS. 2 and 3) is supplied to a through hole 25 of the substrate 2. The liquid 100 is, for example, an aroma oil, but is not limited thereto, and may be water, a cosmetic liquid, a medical liquid, or the like. The liquid atomization system 1 can be applied to, for example, a mist diffuser.

(2) Details of the Liquid Atomization System As shown in FIGS. 1 to 3, the liquid atomization system 1 includes a substrate 2 and an IDT electrode 3.

The substrate 2 has a front surface 21 and a back surface 22. The front surface 21 and the back surface 22 are separated in the thickness direction D0 of the substrate 2 and intersect with the thickness direction D0 of the substrate 2. The front surface 21 and the back surface 22 of the substrate 2 are, for example, perpendicular to the thickness direction D0 of the substrate 2. When viewed from the thickness direction D0 of the substrate 2, the peripheral shape of the substrate 2 is, for example, rectangular.

The substrate 2 has piezoelectricity as described above. The substrate 2 is a piezoelectric substrate, and is, for example, a 128° Y-cut LiNbO3 _single crystal substrate. The material of the substrate 2 is not limited to _LiNbO3 , and may be, for example, _LiTaO3 , etc. The cut angle of the substrate 2 is not limited to 128°, and may be a cut angle other than 128°. The thickness of the substrate 2 is, for example, 0.5 mm, but is not limited thereto.

The IDT electrode 3 is provided on the surface 21 of the substrate 2 and generates a surface acoustic wave on the substrate 2. Here, the IDT electrode 3 is provided directly on the surface 21 of the substrate 2.

The IDT electrode 3 has a pair of comb-shaped electrodes, a first comb-shaped electrode 31 and a second comb-shaped electrode 32. Each of the first comb-shaped electrode 31 and the second comb-shaped electrode 32 is comb-shaped when viewed from the thickness direction D0 of the substrate 2. The first comb-shaped electrode 31 includes a plurality of first electrode fingers 311. The first comb-shaped electrode 31 further includes a first conductive portion 312 to which the plurality of first electrode fingers 311 are connected. The second comb-shaped electrode 32 includes a plurality of second electrode fingers 321. The second comb-shaped electrode 32 further includes a second conductive portion 322 to which the plurality of second electrode fingers 321 are connected.

The material of the IDT electrode 3 is, for example, aluminum, but is not limited to this and may be other metals or alloys, etc. In addition, the IDT electrode 3 is not limited to a single-layer structure and may have a multilayer structure.

In the following, for ease of explanation, the thickness direction D0 of the substrate 2 is sometimes referred to as the first direction D1, the direction in which the first electrode fingers 311 of the first comb electrode 31 are arranged is sometimes referred to as the second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 is sometimes referred to as the third direction D3.

In the IDT electrode 3, a plurality of first electrode fingers 311 and a plurality of second electrode fingers 321 are arranged alternately one by one in the second direction D2. Adjacent first electrode fingers 311 and second electrode fingers 321 in the second direction D2 are spaced apart from each other. In the illustrated examples, Figures 1 to 3 are merely schematic diagrams, and the number of first electrode fingers 311 and second electrode fingers 321 in the IDT electrode 3 is drawn to be less than the actual number.

In the IDT electrode 3, the first conductive portion 312 and the second conductive portion 322 face each other in the third direction D3. The first electrode fingers 311 are connected to the first conductive portion 312 and extend toward the second conductive portion 322. In the third direction D3, the lengths of the first electrode fingers 311 are the same. Here, "same" is not limited to being strictly the same, but may be approximately the same (for example, within a range of ±5% of the average value of the lengths of the first electrode fingers 311). The tips of the first electrode fingers 311 are separated from the second conductive portion 322 in the third direction D3. In the third direction D3, the lengths of the second electrode fingers 321 are the same. Here, "same" is not limited to being strictly the same, but may be approximately the same (for example, within a range of ±5% of the average value of the lengths of the second electrode fingers 321). The tips of the multiple second electrode fingers 321 are spaced apart from the first conductive portion 312 in the third direction D3.

The IDT electrode 3 has an intersection region 33 determined by a plurality of first electrode fingers 311 and a plurality of second electrode fingers 321. The intersection region 33 is a region between a first envelope of the tips of the plurality of first electrode fingers 311 and a second envelope of the tips of the plurality of second electrode fingers 321. The outer periphery of the intersection region 33 includes a first envelope and a second envelope. In other words, the intersection region 33 is a region where the plurality of first electrode fingers 311 and the plurality of second electrode fingers 321 overlap when viewed from the second direction D2. In addition, in FIG. 1, in order to make the intersection region 33 easier to see, the outer periphery of the intersection region 33 is slightly separated from the tips of the plurality of first electrode fingers 311 and the tips of the plurality of second electrode fingers 321. Similarly, in FIG. 1, in order to make the intersection region 33 easier to see, the outer periphery of the intersection region 33 is slightly separated from the first electrode finger 311 at the left end and the second electrode finger 321 at the right end in FIG. 1.

The SAW device 5, which includes the substrate 2 and the IDT electrode 3, generates a surface acoustic wave by the IDT electrode 3. More specifically, the SAW device 5 generates a surface acoustic wave by applying a high-frequency voltage between the first comb electrode 31 and the second comb electrode 32, for example, from a high-frequency power source. The frequency of the high-frequency voltage is, for example, several MHz to several hundred MHz, and is 40 MHz as an example, but is not limited to this. From the viewpoint of reducing the particle size of the droplet particles 103, a high frequency of the high-frequency voltage is preferable.

In the SAW device 5, the IDT electrode 3 excites a surface acoustic wave in the substrate 2 at the intersection region 33. The surface acoustic wave propagates through at least the propagation region 23 in the substrate 2. Here, the propagation region 23 is a region that overlaps in the thickness direction D0 of the substrate 2 with an extension region obtained by extending the intersection region 33 in the second direction D2.

The width L1 of the propagation region 23 (hereinafter also referred to as the propagation width L1) is the same as the width of the intersection region 33 in the third direction D3 (hereinafter also referred to as the intersection width L0). The propagation width L1 is, for example, 0.5 mm to 10 mm.

The SAW device 5 further includes a reflector 4. The reflector 4 is provided on the surface 21 of the substrate 2. The reflector 4 is aligned with the IDT electrode 3 in the second direction D2. In the SAW device 5, the reflector 4, the IDT electrode 3, the propagation region 23, and the through hole 25 are aligned in the following order: reflector 4, IDT electrode 3, propagation region 23, and through hole 25. Therefore, when viewed from the thickness direction D0 of the substrate 2, the propagation region 23 is on the opposite side to the reflector 4 side with respect to the IDT electrode 3. The reflector 4 reflects the surface acoustic wave generated by the IDT electrode 3 and propagating in the second direction D2 to the opposite side to the propagation region 23 side.

The reflector 4 has a first electrode 41 and a second electrode 42. Each of the first electrode 41 and the second electrode 42 has a comb shape as with the IDT electrode 3 when viewed from the thickness direction D0 of the substrate 2. The material of the reflector 4 is, for example, aluminum, but is not limited to this and may be other metals or alloys.

The reflector 4 is not limited to a shape having a first electrode 41 and a second electrode 42, and may be, for example, a short-circuit grating or an open grating.

In order to obtain droplet particles 103 of nanometer size, it is preferable that the liquid film thickness of the liquid 100 on the surface 21 of the substrate 2 is thin. Here, "nanometer size" means 1 nm to 999 nm.

The through hole 25 penetrates the substrate 2 in the thickness direction D0 of the substrate 2. The through hole 25 is a hole for supplying the liquid 100 from the rear surface 22 side to the front surface 21 side of the substrate 2. When viewed from the thickness direction D0 of the substrate 2, the through hole 25 is aligned with the IDT electrode 3 in the propagation direction D4 of the surface acoustic wave. The propagation direction D4 of the surface acoustic wave referred to here is not the propagation direction of all surface acoustic waves, but a direction along the second direction D2 (a direction parallel to the second direction D2). Here, the through hole 25 and the IDT electrode 3 are aligned in the second direction D2. The through hole 25 and the IDT electrode 3 are separated from each other in the second direction D2.

When viewed from the thickness direction D0 of the substrate 2, the through hole 25 is a slit-shaped shape with a direction perpendicular to the propagation direction D4 as its longitudinal direction. In other words, when viewed from the thickness direction D0 of the substrate 2, the through hole 25 is a slit-shaped shape with a direction perpendicular to the second direction D2 as its longitudinal direction. In this specification, the "direction perpendicular to the propagation direction D4 as viewed from the thickness direction D0 of the substrate 2" and the "direction perpendicular to the second direction D2 as viewed from the thickness direction D0 of the substrate 2" are the same direction. Here, when viewed from the thickness direction D0 of the substrate 2, the opening shape of the through hole 25 is, for example, rectangular. When viewed from the thickness direction D0 of the substrate 2, the through hole 25 is formed so that the longitudinal direction of the through hole 25 is aligned with the third direction D3 and the short direction of the through hole 25 is aligned with the second direction D2. The width H3 of the through hole 25 in the third direction D3 is longer than the propagation width L1 of the propagation region 23 in the third direction D3. The width H3 of the through hole 25 in the third direction D3 is longer than the width H2 of the through hole 25 in the second direction D2. As viewed from the thickness direction D0 of the substrate 2, the propagation region 23 is located inside both ends of the through hole 25 in the third direction D3. As viewed from the thickness direction D0 of the substrate 2, the through hole 25 is preferably line-symmetric with respect to the center line of the propagation region 23, but does not necessarily have to be line-symmetric. The width H3 of the through hole 25 in the third direction D3 is not limited to being longer than the propagation width L1 of the propagation region 23 in the third direction D3, but may be equal to or larger than the propagation width L1 of the propagation region 23 in the third direction D3. In other words, as viewed from the thickness direction D0 of the substrate 2, the propagation region 23 may have the same range as the through hole 25 in the third direction D3.

When viewed from the thickness direction D0, the through hole 25 is formed at least across both ends of the intersection region 33 in a direction perpendicular to the propagation direction D4 of the surface acoustic wave. Here, in the liquid atomization system 1 according to embodiment 1, when viewed from the thickness direction D0, the through hole 25 is formed with a width larger than the intersection width L0 of the intersection region 33. In one embodiment, when the intersection width L0 is 2 mm, the width H3 of the through hole 25 is 3 mm and the width H2 is 1 mm. These numerical values are merely examples and are not limited to these numerical values. In addition, when viewed from the thickness direction D0, the through hole 25 is not limited to only being formed with a width larger than the intersection width L0 of the intersection region 33, but may be any width equal to or greater than the intersection width L0.

In the liquid atomization system 1, the substrate 2 has a periphery (edge) 251 of the through hole 25 on the surface 21 located between the through hole 25 and the intersection region 33 of the IDT electrode 3 in the propagation direction D4 as viewed from the thickness direction D0. In the liquid atomization system 1, droplet particles 103 are generated by atomization of at least the protruding portion 102 (see FIG. 3) of the liquid 100 as viewed from the thickness direction D0 of the substrate 2. The protruding portion 102 is a portion of the liquid 100 that protrudes beyond the periphery 251 of the through hole 25 onto the surface 21 of the substrate 2 on the IDT electrode 3 side. In the liquid atomization system 1, droplet particles 103 are also generated by atomization by surface acoustic waves of the portion of the liquid 100 that covers the periphery 251 of the through hole 25. When viewed from the thickness direction D0, the periphery 251 of the through hole 25 has a first end 2511 and a second end 2512, which are both ends in a direction perpendicular to the propagation direction D4. In the liquid atomization system 1 according to the first embodiment, the periphery 251 is a straight line along a virtual straight line VL1 that is perpendicular to the propagation direction D4 and passes through at least one of the first end 2511 and the second end 2512. In the liquid atomization system 1 according to the first embodiment, the virtual straight line VL1 passes through both the first end 2511 and the second end 2512 of the periphery 251. In this specification, the inclination angle of the periphery 251 with respect to the virtual straight line VL is set to a plus on the IDT electrode 3 side and a minus on the opposite side to the IDT electrode 3 side with respect to the virtual straight line VL1. In the liquid atomization system 1 according to the first embodiment, the inclination angle is 0 degrees.

The liquid atomization system 1 according to the first embodiment atomizes at least the protruding portion 102 of the liquid 100 by surface acoustic waves. From the viewpoint of generating nanometer-sized droplet particles 103, it is preferable that the liquid film thickness of the protruding portion 102 is thin when atomizing the liquid 100. This allows the particle size of the droplet particles 103 formed by atomizing the liquid 100 to be nanometer-sized. In the liquid atomization system 1 according to the first embodiment, the particle size of the droplet particles 103 is nanometer-sized. In the liquid atomization system 1, for example, when the liquid 100 is an aroma oil, the liquid level 101 of the liquid 100 in the through hole 25 is lower than the surface 21 of the substrate 2 when the liquid 100 is atomized.

The particle size of the droplet particles 103 formed by atomizing the liquid 100 is a value measured by, for example, a laser diffraction method. More specifically, the particle size of the droplet particles 103 is a value measured by using a laser diffraction type particle size distribution measuring device. The laser diffraction type particle size distribution measuring device is, for example, Spraytec (product name) by Malvern Panalytical. Spraytec is, for example, a device that can measure the particle size distribution from the pattern of light scattered when laser light passes through a spray, and then analyze the scattering pattern to calculate the droplet size. The particle size of the droplet particles 103 formed by atomizing the liquid 100 is the median diameter (d ₅₀ ).

As shown in Figure 3, the mist generating system 200 including the liquid atomization system 1 includes the liquid atomization system 1 and a liquid supply unit 201. The liquid supply unit 201 supplies liquid 100 to the through-hole 25 in the liquid atomization system 1. The mist generating system 200 generates mist M1 including nanometer-sized droplet particles 103. In Figure 3, the liquid 100 is hatched with dots. Also, in Figure 3, surface acoustic waves are shown diagrammatically by wavy arrows.

The liquid supply section 201 has, for example, a supply pipe 2012 for supplying liquid 100 to the through hole 25, a jig 2014 for connecting the supply pipe 2012 to the SAW device 5, and a pump 2013 for sending the liquid 100 in the supply pipe 2012 to the through hole 25.

In the liquid atomization system 1 of embodiment 1, the widths H2, H3 of the through holes 25 can be appropriately determined depending on various parameters such as the intersection width L0, the frequency of the driving voltage of the IDT electrode 3, the input power to the IDT electrode 3, and the type of liquid 100.

(3) Effects In the liquid atomization system 1 according to the first embodiment, the through hole 25 is formed at least over both ends of the intersection region 33 in a direction perpendicular to the propagation direction D4 of the surface acoustic wave, as viewed from the thickness direction D0 of the substrate 2. The substrate 2 has a periphery 251 of the through hole 25 on the surface 21, which is located between the through hole 25 and the intersection region 33 of the IDT electrode 3 in the propagation direction D4, as viewed from the thickness direction D0. The liquid atomization system 1 atomizes at least the protruding portion 102 of the liquid 100 by surface acoustic waves. The protruding portion 102 is a portion of the liquid 100 that protrudes from the through hole 25 beyond the periphery 251 onto the propagation region 23 of the surface acoustic wave in the substrate 2. The periphery 251 has a first end 2511 and a second end 2512, which are both ends in a direction perpendicular to the propagation direction D4. The inclination angle of the peripheral edge 251 with respect to a virtual straight line VL1 that is perpendicular to the propagation direction D4 and passes through at least one of the first end 2511 and the second end 2512 is 0 degrees.

In the liquid atomization system 1 of embodiment 1, it becomes possible to more stably generate droplet particles 103 having nanometer-sized particle sizes.

(4) Modifications (4.1) Modification 1
In the following, a liquid atomization system 1a according to a first modified example of the first embodiment will be described with reference to Fig. 4. In the liquid atomization system 1a according to the first modified example, the same components as those in the liquid atomization system 1 according to the first embodiment will be denoted by the same reference numerals and will not be described.

The liquid nebulization system 1a of variant example 1 differs from the liquid nebulization system 1 of embodiment 1 in that the periphery 251 of the through hole 25 is curved.

In the liquid atomization system 1a according to the first modification, the peripheral edge 251 is a concave curve that is concave in the direction away from the IDT electrode 3 (see FIG. 1) when viewed from the thickness direction D0 (see FIG. 2) of the substrate 2. Here, the peripheral edge 251 is a concave curve having a radius of curvature larger than half the overlap width L0 (see FIG. 1).

In the liquid atomization system 1a according to the first modification, the peripheral edge 251 has, for example, inclination angles θ1 and θ2 of -10 degrees with respect to the virtual straight line VL1. Here, the inclination angles θ1 and θ2 are positive on the IDT electrode 3 side and negative on the opposite side to the IDT electrode 3 side with respect to the virtual straight line VL1. In the liquid atomization system 1 according to the first embodiment, the inclination angles θ1 and θ2 are both 0 degrees.

In the liquid atomization system 1a according to the first modification, as in the liquid atomization system 1 according to the first embodiment, a slit-shaped through hole 25 is provided, and the through hole 25 is formed at least across both ends of the intersection region 33 in a direction perpendicular to the propagation direction D4 (see FIG. 1) of the surface acoustic wave as viewed from the thickness direction D0 of the substrate 2. Here, in the liquid atomization system 1a according to the first modification, the through hole 25 is formed with a width greater than the intersection width L0 in a direction perpendicular to the propagation direction D4 of the surface acoustic wave as viewed from the thickness direction D0 of the substrate 2. In addition, the peripheral edge 251 has an inclination angle of -10 degrees with respect to the virtual straight line VL1 that is perpendicular to the propagation direction D4 and passes through at least one of the first end 2511 and the second end 2512. The liquid atomization system 1a atomizes at least the protruding portion 102 of the liquid 100 by surface acoustic waves. The protruding portion 102 is a portion of the liquid 100 that protrudes from the through hole 25 beyond the periphery 251 onto the propagation region 23 of the surface acoustic wave on the substrate 2. In the liquid atomization system 1a according to the first modification, similarly to the liquid atomization system 1 according to the first embodiment, it is possible to more stably generate droplet particles 103 (see FIG. 3) having a particle size on the nanometer size.

(4.2) Modification 2
In the following, a liquid atomization system 1b according to a modified example 2 of the embodiment 1 will be described with reference to Fig. 5. In the liquid atomization system 1b according to the modified example 2, the same components as those in the liquid atomization system 1 according to the embodiment 1 are denoted by the same reference numerals and will not be described.

In the liquid atomization system 1b relating to variant example 2, the peripheral edge 251 is a concave curve having a radius of curvature that is half the intersection width L0.

In the liquid atomization system 1b according to the second modification, the peripheral edge 251 has inclination angles θ1 and θ2 of -90 degrees with respect to the virtual straight line VL1. Here, as in the liquid atomization system 1a according to the first modification, the inclination angles θ1 and θ2 are positive on the IDT electrode 3 side and negative on the opposite side to the IDT electrode 3 side with respect to the virtual straight line VL1.

In the liquid atomization system 1b according to the second modification, as in the liquid atomization system 1 according to the first embodiment, a slit-shaped through hole 25 is provided, and the through hole 25 is formed at least across both ends of the intersection region 33 (see FIG. 1) in a direction perpendicular to the propagation direction D4 (see FIG. 1) of the surface acoustic wave, as viewed from the thickness direction D0 of the substrate 2 (see FIG. 2). Here, in the liquid atomization system 1b according to the second modification, the through hole 25 is formed with a width equal to or greater than the intersection width L0 (see FIG. 1) in a direction perpendicular to the propagation direction D4 of the surface acoustic wave, as viewed from the thickness direction D0 of the substrate 2. In addition, the peripheral edge 251 has an inclination angle of -90 degrees toward the IDT electrode 3 with respect to the virtual straight line VL1 that is perpendicular to the propagation direction D4 and passes through at least one of the first end 2511 and the second end 2512. The liquid atomization system 1a atomizes at least the protruding portion 102 of the liquid 100 by surface acoustic waves. The protruding portion 102 is a portion of the liquid 100 that protrudes from the through hole 25 beyond the periphery 251 onto the propagation region 23 of the surface acoustic wave on the substrate 2. In the liquid atomization system 1b according to the second modification, similarly to the liquid atomization system 1 according to the first embodiment, it is possible to more stably generate droplet particles 103 (see FIG. 3) having a particle size of nanometer size.

(4.3) Modification 3
In the following, a liquid atomization system 1c according to a third modification of the first embodiment will be described with reference to Fig. 6. In the liquid atomization system 1c according to the third modification, the same components as those in the liquid atomization system 1 according to the first embodiment will be denoted by the same reference numerals and will not be described.

When viewed from the thickness direction D0 (see FIG. 2) of the substrate 2, the peripheral edge 251 is curved and is a convex curve that becomes convex in the direction approaching the IDT electrode 3 (see FIG. 1). Here, the peripheral edge 251 is a convex curve having a radius of curvature larger than half the overlap width L0.

In the liquid atomization system 1c according to the modified example 3, as in the liquid atomization system 1 according to the embodiment 1, the liquid atomization system 1c has a slit-shaped through hole 25, and when viewed from the thickness direction D0 of the substrate 2, the through hole 25 is formed at least over both ends of the intersection region 33 in a direction perpendicular to the propagation direction D4 of the surface acoustic wave (see FIG. 2). In the liquid atomization system 1c according to the modified example 3, the through hole 25 is formed with a width larger than the intersection width L0 (see FIG. 1) in a direction perpendicular to the propagation direction D4 of the surface acoustic wave. In the liquid atomization system 1c according to the modified example 3, the peripheral edge 251 has, for example, inclination angles θ1 and θ2 of 10 degrees with respect to the virtual straight line VL1. Here, the peripheral edge 251 may have inclination angles θ1 and θ2 of 45 degrees or less with respect to the virtual straight line VL1. As a result, in the liquid atomization system 1c, the surface acoustic wave is less likely to be reflected toward the outside of the propagation region 23, and the energy loss of the surface acoustic wave is less likely to occur, compared to when the inclination angles θ1 and θ2 are greater than 45 degrees. As a result, in the liquid atomization system 1c according to the third modification, as in the liquid atomization system 1 according to the first embodiment, the liquid film thickness of the protruding portion 102 (see FIG. 3) can be stabilized, and the liquid droplet particles 103 (see FIG. 3) having a nanometer-sized particle size can be more stably generated.

(4.4) Modification 4
In the following, a liquid atomization system 1d according to a fourth modification of the first embodiment will be described with reference to Figures 7 to 9. In the liquid atomization system 1d according to the fourth modification, the same components as those in the liquid atomization system 1 according to the first embodiment will be denoted by the same reference numerals and will not be described.

In the liquid atomization system 1d according to the modified example 4, the inner surface 253 of the through hole 25 adjacent to the peripheral edge 251 in the substrate 2 includes a tapered surface. Here, in the liquid atomization system 1d according to the modified example 4, the width H2 of the through hole 25 in the second direction D2 (see FIG. 1) is different between the front surface 21 and the back surface 22 of the substrate 2. As a result, the opening area of the through hole 25 on the front surface 21 of the substrate 2 is larger than the opening area of the back surface 22 of the substrate 2. The opening shape of the through hole 25 on the back surface 22 of the substrate 2 is a rectangle whose short side length is shorter than the opening shape on the front surface 21 of the substrate 2.

In the liquid atomization system 1d according to the modified example 4, as in the liquid atomization system 1 according to the embodiment 1, the inclination angle of the periphery 251 with respect to the virtual straight line VL1 that is perpendicular to the propagation direction D4 (see FIG. 1) and passes through at least one of the first end 2511 and the second end 2512 is 0 degrees. The liquid atomization system 1d atomizes at least the protruding portion 102 (see FIG. 9) of the liquid 100 by surface acoustic waves. The protruding portion 102 is a portion of the liquid 100 that protrudes from the through hole 25 beyond the periphery 251 onto the propagation region 23 of the surface acoustic wave in the substrate 2. In the liquid atomization system 1d according to the modified example 4, it is possible to more stably generate droplet particles 103 having a particle size of nanometer size.

In addition, in the liquid atomization system 1d according to the fourth modification, if the liquid 100 has high wettability with respect to the substrate 2, the liquid 100 may be able to creep up along the inner surface 253 of the through-hole 25 by capillary action, as shown in Fig. 9. In this case, in the liquid atomization system 1d, it is possible to thin the liquid film thickness of the liquid 100 on the inner surface 253 of the through-hole 25, and it is possible to stably generate droplet particles 103 having a nanometer-sized particle size from the portion of the liquid 100 on the inner surface 253 of the through-hole 25.

(4.5) Modification 5
Hereinafter, a liquid atomization system 1e according to a modified example 5 of the embodiment 1 will be described with reference to Fig. 10. Regarding the liquid atomization system 1e according to the modified example 5, the same components as those in the liquid atomization system 1d according to the modified example 4 are denoted by the same reference numerals, and the description thereof will be omitted.

The liquid atomization system 1e according to variant example 5 differs from the liquid atomization system 1d according to variant example 4 in that the inner surface 253 of the through hole 25 is curved rather than flat, and the opening shape of the through hole 25 on the rear surface 22 of the substrate 2 is not rectangular.

In the liquid nebulization system 1e of variant example 5, like the liquid nebulization system 1d of variant example 4, it is possible to more stably generate droplet particles 103 having a nanometer-sized particle size.

(4.6) Modification 6
In the following, a liquid atomization system 1f according to a sixth modified example of the first embodiment will be described with reference to Fig. 11. In the liquid atomization system 1f according to the sixth modified example, the same components as those in the liquid atomization system 1 according to the first embodiment will be denoted by the same reference numerals and will not be described.

The liquid atomization system 1f according to the modified example 6 differs from the liquid atomization system 1 according to the embodiment 1 in that the opening shape of the through hole 25 is not rectangular, but has a radius on both ends in the third direction D3. However, the periphery 251 of the through hole 25 is linear.

In the liquid atomization system 1f of variant example 6, similar to the liquid atomization system 1 of embodiment 1, it is possible to more stably generate droplet particles 103 having nanometer-sized particle sizes.

(4.7) Modification of Mist Generation System A mist generation system 200a according to a modification of the mist generation system 200 including the liquid atomization system 1 according to the first embodiment will be described below with reference to FIG.

The mist generating system 200a according to the modified example includes a liquid atomization system 1 and a liquid supply unit 201. The liquid supply unit 201 supplies liquid 100 to the through hole 25 in the liquid atomization system 1. The mist generating system 200a generates a mist M1 (see FIG. 3) containing nanometer-sized droplet particles 103 (see FIG. 3).

The liquid supply unit 201 includes a tank 2011 containing the liquid 100, and a capillary tube section 2015 that supplies the liquid 100 in the tank 2011 into the through-hole 25 of the substrate 2 by capillary action. The liquid supply unit 201 supplies the liquid 100 to the through-hole 25 so as to generate, for example, an overflow portion 102 of the liquid 100 that overflows onto the surface 21 of the substrate 2 of the liquid atomization system 1. The capillary tube section 2015 may include a porous body. The material of the porous body may be any material that is corrosion-resistant to the liquid 100. The material of the porous body may be, for example, glass, ceramic, polymer, fiber, etc.

The mist generating system 200a of the modified example is capable of more stably generating droplet particles 103 having nanometer-sized particle sizes, similar to the mist generating system 200.

(Embodiment 2)
Hereinafter, a liquid atomization system 1g according to a second embodiment and a mist generating system 200b including the liquid atomization system 1g will be described with reference to Fig. 13. In the liquid atomization system 1g according to the second embodiment, components similar to those in the liquid atomization system 1 according to the first embodiment are designated by the same reference numerals and will not be described.

The mist generating system 200b includes the liquid atomization system 1g and a liquid supply unit 201. The liquid supply unit 201 supplies liquid 100 to the through-hole 25 of the substrate 2 in the liquid atomization system 1g. Here, in the liquid atomization system 1g, the SAW device 5 includes the substrate 2 and the IDT electrode 3, similar to the liquid atomization system 1 according to the first embodiment.

The liquid supply section 201 includes a tank 2011 containing liquid 100 and a supply pipe 2012 connecting the tank 2011 to the peripheral portion of the through hole 25 on the rear surface 22 of the substrate 2.

The mist generating system 200b has multiple (e.g., two) sets of an IDT electrode 3, a through hole 25, and a liquid supply section 201.

In the liquid atomization system 1g, in the SAW device 5, two IDT electrodes 3 are provided on the surface 21 of one substrate 2. In addition, in the liquid atomization system 1g, in the SAW device 5, two through holes 25 are formed in one substrate 2 so as to correspond one-to-one to each of the two IDT electrodes 3. In other words, one substrate 2 has two through holes 25.

In each of the multiple sets, liquid containing different components as liquid 100 is supplied from liquid supply unit 201 to through-hole 25. Mist generating system 200b may further include mixer 202. Mixer 202 mixes mist M1 containing droplet particles 103 (see FIG. 3) emitted from protruding portion 102 (see FIG. 3) on surface 21 of substrate 2 at least near periphery 25 of through-hole 25 of each of the multiple sets. Mixer 202 has an outlet from which the mixed mist is ejected.

The mist generating system 200b is equipped with a liquid atomization system 1g and a liquid supply unit 201, and is therefore capable of generating a mist containing droplet particles 103 having nanometer-sized particle sizes, similar to the mist generating system 200.

In the liquid atomization system 1g, the SAW device 5 has two IDT electrodes 3 provided on the surface 21 of one substrate 2, but this is not limited to this. For example, the liquid atomization system 1g may include a plurality of SAW devices 5, each having one IDT electrode 3 provided on the surface 21 of one substrate 2.

(Embodiment 3)
A mist generating system 200c according to the third embodiment will be described below with reference to FIG.

The mist generating system 200c includes the liquid atomization system 1 of embodiment 1 and a liquid supply unit 201. Here, the liquid atomization system 1 includes a SAW device 5 including a substrate 2 and an IDT electrode 3 as described in embodiment 1. The substrate 2 also has a through hole 25. The liquid supply unit 201 supplies liquid 100 (see FIG. 2) to the through hole 25 in the liquid atomization system 1.

Therefore, the mist generating system 200c is capable of stably emitting droplet particles 103 (see Figure 3) having nanometer-sized particle sizes.

The mist generating system 200c according to the third embodiment further includes a blending unit 203 that blends liquid 100 from multiple types of liquid. The liquid supply unit 201 supplies the liquid 100 blended in the blending unit 203 to the through hole 25.

In the mist generating system 200c according to the third embodiment, the mixing section 203 and the liquid supply section 201 are formed, for example, in a microchannel forming substrate 206. The microchannel forming substrate 206 is formed, for example, using two silicon substrates. More specifically, the microchannel forming substrate 206 is formed by providing a first recess, a second recess, and multiple (three) third recesses in at least one of the two silicon substrates and bonding the two silicon substrates. The first recess is a recess for forming the liquid supply section 201. The second recess is a recess for forming the mixing section 203. The multiple (three) third recesses are recesses for forming multiple (three) microchannels 205 that supply different liquids to the mixing section 203. The microchannel forming substrate 206 also has multiple liquid injection holes 204 that are connected one-to-one to the multiple microchannels 205.

In the mist generating system 200c of embodiment 3, it is possible to generate a mist containing droplet particles 103 (see Figure 3) having a nanometer-sized particle size by atomizing the liquid 100 prepared in the preparation section 203.

The above-mentioned embodiments 1 to 3 are merely examples of the various embodiments of the present disclosure. The above-mentioned embodiments 1 to 3 can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

For example, the liquid atomization systems 1 to 1g may be provided with a liquid-repellent portion having liquid repellency to the liquid 100 in areas of the surface 21 of the substrate 2 on both sides of the propagation region 23 in the third direction D3 when viewed from the thickness direction D0 of the substrate 2.

When viewed from the thickness direction D0 of the substrate 2, the through hole 25 needs to be formed at least across both ends of the intersection region 33 in a direction perpendicular to the propagation direction D4 of the surface acoustic wave, and may be formed with a width equal to the intersection width L0 of the intersection region 33, not limited to a width greater than the intersection width L0 of the intersection region 33.

The periphery 251 of the through hole 25 is not limited to a straight line, a concave curve, or a convex curve, and may be a free curve. In any case, from the viewpoint of making it difficult for the surface acoustic wave to be reflected outside the propagation region 23, it is preferable that the inclination angle of the periphery 251 with respect to a straight line parallel to the virtual straight line VL1 is greater than or equal to -90 degrees and less than or equal to 45 degrees in all parts of the periphery 251 of the through hole 25.

In addition, in the liquid atomization system 1, when the liquid 100 is atomized, the liquid level 101 of the liquid 100 in the through hole 25 is not limited to being at a position lower than the surface 21 of the substrate 2, but may be at the same height as the surface 21 of the substrate 2 or at a position higher than the surface 21 of the substrate 2.

In addition, in the liquid atomization systems 1d and 1e, the entire inner surface 253 of the through hole 25 adjacent to the peripheral edge 251 of the substrate 2 is a tapered surface, but this is not limited to this and it is sufficient if it includes a tapered surface.

In addition, two IDT electrodes 3 may be provided on the substrate 2 so that the propagation regions 23 are aligned in a straight line, and two through holes 25 may be located between the two IDT electrodes 3 as viewed from the thickness direction D0 of the substrate 2. In this case, the two through holes 25 may correspond one-to-one to the two IDT electrodes 3 as viewed from the thickness direction D0 of the substrate 2, and may be formed over at least both ends of the intersection region 33 of the corresponding IDT electrodes 3. In this case, the liquid atomization system may also include two reflectors 4 that correspond one-to-one to the two IDT electrodes 3. Here, each of the two reflectors 4 may be located on the opposite side of the through hole 25 side as viewed from the corresponding IDT electrode 3 of the two IDT electrodes 3.

In addition, by providing an IDT electrode 3 on the center of the substrate 2 and eliminating the reflector 4, propagation regions 23 can be provided on both sides of the IDT electrode 3, and two through holes 25 can be provided in one-to-one correspondence with the two propagation regions 23.

Furthermore, the substrate 2 need only have piezoelectric properties and is not limited to a piezoelectric substrate. For example, the substrate 2 may have a structure in which a piezoelectric layer (LiNbO ₃ single crystal substrate) is provided on a support substrate.

In addition, in the liquid atomization systems 1 to 1f, the supply amount of the liquid 100 supplied to the through-hole 25 of the substrate 2 is preferably controlled by a control unit that controls the supply amount of the liquid 100. The control unit is, for example, a micropump, a microvalve, a capillary tube, etc., but is not limited to these.

(Aspects)
From the above-described embodiments, the present specification discloses the following aspects.

A liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) according to a first aspect includes a SAW device (5) and atomizes a liquid (100) supplied to the SAW device (5) by surface acoustic waves. The SAW device (5) includes a substrate (2) and an IDT electrode (3). The substrate (2) has a front surface (21) and a back surface (22) and has piezoelectricity. The IDT electrode (3) has a pair of comb electrodes (first comb electrode 31, second comb electrode 32) provided on the front surface (21) of the substrate (2). The IDT electrode (3) generates a surface acoustic wave in the substrate (2). The substrate (2) has a through hole (25). The through hole (25) penetrates the substrate (2) in the thickness direction (D0). The liquid (100) is supplied to the through hole (25). When viewed from the thickness direction (D0), the through holes (25) are arranged in the crossing region (33) of a pair of comb electrodes (first comb electrode 31, second comb electrode 32) in the propagation direction (D4) of the surface acoustic wave. When viewed from the thickness direction (D0), the through holes (25) are formed across at least both ends of the crossing region (33) in a direction perpendicular to the propagation direction (D4) of the surface acoustic wave. When viewed from the thickness direction (D0), the substrate (2) has a periphery (251) of the through hole (25) on the surface (21) located between the through hole (25) and the crossing region (33) of the IDT electrode (3) in the propagation direction (D4). The liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) atomizes at least the protruding portion (102) of the liquid (100) by surface acoustic waves. The protruding portion (102) is a portion of the liquid (100) that protrudes from the through hole (25) beyond the periphery (251) onto the propagation region (23) of the surface acoustic wave in the substrate (2). The periphery (251) has a first end (2511) and a second end (2512) that are both ends in a direction perpendicular to the propagation direction (D4). The inclination angle (θ1, θ2) of the periphery (251) with respect to a virtual straight line (VL1) that is perpendicular to the propagation direction (D4) and passes through at least one of the first end (2511) and the second end (2512) is -90 degrees or more and 45 degrees or less, when the IDT electrode (3) side is positive and the opposite side to the IDT electrode (3) side is negative, based on the virtual straight line (VL1).

The liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) relating to the first aspect makes it possible to more stably generate droplet particles (103) having a nanometer-sized particle size.

In the liquid atomization system (1; 1d; 1e; 1f; 1g) relating to the second aspect, in the first aspect, when viewed from the thickness direction (D0), the peripheral edge (251) is a straight line along the imaginary straight line (VL1).

The liquid atomization system (1; 1d; 1e; 1f; 1g) relating to the second aspect makes it possible to more stably generate droplet particles (103) having nanometer-sized particle sizes.

In the liquid atomization system (1a; 1b; 1c) relating to the third aspect, in the first aspect, the peripheral edge (251) is curved when viewed from the thickness direction (D0).

In the liquid atomization system (1b; 1c) relating to the fourth aspect, in the third aspect, when viewed from the thickness direction (D0), the peripheral edge (251) is a concave curve that is concave in the direction away from the IDT electrode (3).

The liquid atomization system (1c) of the fifth aspect is the third aspect, in which, when viewed from the thickness direction (D0), the peripheral edge (251) is a convex curve that is convex in the direction approaching the IDT electrode (3).

The liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) of the sixth aspect is any one of the first to fifth aspects, in which, when the liquid (100) is atomized, the liquid level (101) of the liquid (100) in the through hole (25) is at a position lower than the surface (21) of the substrate (2).

In the liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) relating to the sixth aspect, droplet particles (103) having a nanometer-sized particle size are easily formed from a liquid (100) that has a higher wettability than water with respect to a substrate (2).

In the liquid atomization system (1d; 1e) relating to the seventh aspect, in any one of the first to sixth aspects, the inner surface (253) of the through hole (25) adjacent to the periphery (251) in the substrate (2) includes a tapered surface.

In the liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) relating to the eighth aspect, in any one of the first to seventh aspects, the through hole (25) is slit-shaped and the width (H3) in the direction along the imaginary straight line (VL1) is greater than the width (H2) in the propagation direction (D4).

In the liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) according to the eighth aspect, the opening area of the through hole (25) in the surface (21) of the substrate (2) can be prevented from becoming too large. As a result, in the liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) according to the eighth aspect, the energy loss of the surface acoustic wave can be suppressed, and the droplet particles (103) having a nanometer-sized particle size can be more stably formed.

A mist generating system (200; 200a; 200b; 200c) according to a ninth aspect includes a liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) according to any one of the first to eighth aspects, and a liquid supply unit (201). The liquid supply unit (201) supplies liquid (100) from the back surface (22) side of the substrate (2) of the SAW device (5) to the through hole (25).

The mist generating system (200; 200a; 200b; 200c) of the ninth aspect makes it possible to more stably generate droplet particles (103) having nanometer-sized particle sizes.

In the mist generating system (200a) relating to the tenth aspect, in the ninth aspect, the liquid supply section (201) supplies the liquid (100) to the through hole (25) by capillary action.

In the mist generating system (200c) according to the eleventh aspect, in the ninth or tenth aspect, the liquid supply unit (201) further includes a blending unit (203) that blends the liquid (100). The liquid supply unit (201) supplies the liquid (100) blended in the blending unit (203) to the through hole (25).

The liquid atomization method of the 12th aspect comprises atomizing a liquid (100) using a liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) of any one of the first to eighth aspects.

The liquid atomization method according to the twelfth aspect makes it possible to more stably generate droplet particles (103) having nanometer-sized particle sizes.

A liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) according to a thirteenth aspect includes a SAW device (5) and atomizes a liquid (100) supplied to the SAW device (5) by surface acoustic waves. The SAW device (5) includes a substrate (2) and an IDT electrode (3). The substrate (2) has a front surface (21) and a back surface (22) and has piezoelectricity. The IDT electrode (3) includes a first comb electrode (31) and a second comb electrode (32) provided on the front surface (21) of the substrate (2). The first comb electrode (31) is comb-shaped. The first comb electrode (31) includes a plurality of first electrode fingers (311). The second comb electrode (32) is comb-shaped. The second comb electrode (32) includes a plurality of second electrode fingers (321). The IDT electrode (3) generates a surface acoustic wave in the substrate (2). The substrate (2) has a through hole (25). The through hole (25) penetrates the substrate (2) in a thickness direction (D0). A liquid (100) is supplied to the through hole (25). When viewed from the thickness direction (D0), the through hole (25) is arranged in a predetermined direction (second direction D2) in which the first electrode fingers (311) and the second electrode fingers (321) are arranged, in an intersection region (33) between the first electrode fingers (311) and the second electrode fingers (321) in the IDT electrode (3). When viewed from the thickness direction (D0), the through hole (25) is formed in a direction perpendicular to the predetermined direction (second direction D2) at least across both ends of an extension region (propagation region 23) in the predetermined direction (second direction D2) of the intersection region (33). The substrate (2) has a periphery (251) of the through hole (25) on the surface (21) located between the through hole (25) and the intersection region (33) of the IDT electrode (3) in a predetermined direction (second direction D2) when viewed from the thickness direction (D0). The liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f) atomizes at least the protruding portion (102) of the liquid (100) by surface acoustic waves. The protruding portion (102) is a portion of the liquid (100) that protrudes from the through hole (25) beyond the periphery (251) onto the extension region (propagation region 23) of the substrate (2). The periphery (251) has a first end (2511) and a second end (2512) that are both ends in a direction perpendicular to the predetermined direction (second direction D2). The inclination angle (θ1, θ2) of the peripheral edge (251) with respect to a virtual straight line (VL1) that is perpendicular to a predetermined direction (second direction D2) and passes through at least one of the first end (2511) and the second end (2512) is greater than or equal to -90 degrees and less than or equal to 45 degrees, when the IDT electrode (3) side is taken as positive and the opposite side to the IDT electrode (3) side is taken as negative, with respect to the virtual straight line (VL1).

The liquid atomization system (1; 1a; 1b; 1c; 1d; 1e; 1f; 1g) relating to the thirteenth aspect makes it possible to more stably generate droplet particles (103) having a nanometer-sized particle size.

1, 1a, 1b, 1c, 1d, 1e, 1f, 1g Liquid atomization system 2 Substrate 21 Front surface 22 Back surface 23 Propagation area 25 Through hole 251 Edge 2511 First end 2512 Second end 253 Inner surface 3 IDT electrode 31 First comb electrode 311 First electrode finger 32 Second comb electrode 321 Second electrode finger 33 Intersection area 5 SAW device 100 Liquid 101 Liquid surface 102 Overhanging portion 103 Liquid droplet particle 200, 200a, 200b, 200c Mist generation system 201 Liquid supply section 203 Mixing section D0 Thickness direction D4 Propagation direction H1 Width H2 Width VL1 Virtual straight line θ1, θ2 Tilt angle

Claims (11)

A liquid atomization system including a SAW device, the liquid being supplied to the SAW device being atomized by surface acoustic waves,
The SAW device is
A substrate having a front surface and a back surface and having piezoelectricity;
an IDT electrode having a pair of comb-shaped electrodes provided on the surface of the substrate, the IDT electrode generating the surface acoustic wave on the substrate;
a reflector disposed on the surface of the substrate;
the substrate has a through hole penetrating in a thickness direction of the substrate and through which the liquid is supplied,
When viewed from the thickness direction, the through holes are aligned in an intersection region of the pair of comb electrodes in a propagation direction of the surface acoustic wave,
When viewed from the thickness direction, the through hole is formed across at least both ends of the intersection region in a direction perpendicular to a propagation direction of the surface acoustic wave,
the substrate has a periphery of the through hole on the surface, the periphery being located between the through hole and the intersection region of the IDT electrodes in the propagation direction when viewed from the thickness direction,
Atomizing at least the protruding portion of the liquid by the surface acoustic wave;
the protruding portion is a portion of the liquid that protrudes from the through hole beyond the periphery onto a propagation region of the surface acoustic wave on the substrate,
the reflector, the IDT electrode, the propagation region, and the through hole are arranged in this order as viewed from the thickness direction,
the reflector reflects the surface acoustic wave generated by the IDT electrode and propagating toward an opposite side to the propagation region;
The periphery is
a first end and a second end which are both ends in a direction perpendicular to the propagation direction;
an inclination angle of the periphery with respect to a virtual line that is perpendicular to the propagation direction and passes through at least one of the first end and the second end is greater than or equal to −90 degrees and less than or equal to 45 degrees, when the IDT electrode side is set to be positive and the opposite side to the IDT electrode side is set to be negative with respect to the virtual line;
An inner surface of the through hole adjacent to the periphery of the substrate includes a tapered surface.
Liquid atomization system. When viewed from the thickness direction, the periphery is a straight line along the imaginary straight line.
The liquid atomization system of claim 1 . When viewed in the thickness direction, the periphery is a curved line.
The liquid atomization system of claim 1 . When viewed from the thickness direction, the peripheral edge is a concave curve that is concave in a direction away from the IDT electrode.
The liquid atomization system of claim 3. When viewed from the thickness direction, the peripheral edge is a convex curve that is convex toward the IDT electrode.
The liquid atomization system of claim 3. when the liquid is atomized, a liquid level of the liquid in the through hole is at a position lower than the surface of the substrate;
The liquid atomization system according to any one of claims 1 to 5. The through hole has a slit shape and a width in a direction along the virtual straight line is larger than a width in the propagation direction.
A liquid atomization system according to any one of claims 1 to 6. A liquid atomization system according to any one of claims 1 to 7;
a liquid supply unit that supplies the liquid to the through hole from the back surface side of the substrate of the SAW device,
Mist generating system. The liquid supply unit supplies the liquid to the through hole by capillary action.
9. The mist generating system of claim 8. The liquid supply unit further includes a mixing unit that mixes the liquid,
The liquid supply unit supplies the liquid prepared in the preparation unit to the through hole.
10. A mist generating system according to claim 8 or 9. A liquid is atomized by the liquid atomization system according to any one of claims 1 to 7.
Liquid atomization method.

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