JP2012148256A - Surface acoustic wave atomizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave atomizing device in which a surface of a substrate is easily supplied with liquid, and which stably keeps balance between liquid supply quantity and atomizing quantity and stably generates a large quantity of fine particles with smaller powder consumption without requiring an increase in the size of the device.SOLUTION: The surface acoustic wave atomizing device 1 includes a substrate 2 comprising a piezoelectric material and a pair of comb-shaped electrodes 3 for generating surface acoustic wave W and a groove 4 reaching a propagation region of the surface acoustic wave W, the comb-shaped electrodes 3 and the groove 4 being formed on the surface S of the substrate 2. The surface acoustic wave atomizing device 1 is configured to supply liquid 5 charged to one end side of the groove 4 to the propagation region of the surface acoustic wave W by capillary phenomenon, hold the liquid in the groove 4 and atomize the liquid by the surface acoustic wave W propagated on the bottom surface of the groove 4. The liquid 5 of necessary and sufficient quantity is stably supplied to the propagation region of the surface acoustic wave W by the groove 4 and capillary phenomenon and the liquid in the groove is kept at the constant thickness of a liquid layer. The groove 4 is smoothly formed so as to have a tilted surface 4a on the edge of the groove in contact with the substrate surface S and suppresses the reflection of the surface acoustic wave W.

Description

  The present invention relates to a surface acoustic wave atomization device that atomizes a liquid with surface acoustic waves.

  Conventionally, when a liquid is supplied to the surface of a substrate made of a piezoelectric material or the like through which surface acoustic waves are propagating, the liquid receives the surface acoustic wave energy and flows and vibrates, resulting in the phenomenon of flying as fine particles. Various devices for atomizing a liquid using this phenomenon have been proposed. In such a surface acoustic wave atomizer, in order to efficiently perform stable atomization with low power, the liquid is thinly spread on the surface of the substrate, and the balance between the liquid supply amount and the atomization amount is kept good. There is a need. Therefore, a rough surface region having a surface roughness larger than that of the other part is formed on a part of the substrate surface where the surface acoustic wave propagates, the liquid is held in the rough surface region, and the surface of the liquid is caused by the surface acoustic wave in the region. 2. Description of the Related Art A surface acoustic wave atomizer that atomizes while promoting spreading is known (see, for example, Patent Document 1). This will be described with reference to FIG. This surface acoustic wave atomizing device includes a substrate 91 made of a piezoelectric material, and has a comb-shaped electrode 92 that generates surface acoustic waves W on the surface S of the substrate 91. A rough surface region 93 is formed in the conversion region. When the liquid 94 is supplied to the rough surface region 93, the liquid 94 is held in the region, and the surface of the peripheral portion of the liquid 94 facing the comb-shaped electrode 92 becomes minute particles M by the surface acoustic wave W. It becomes.

  In addition, a liquid film forming member disposed opposite the substrate surface to form a gap with the substrate surface is provided, and the liquid supplied to the gap is held in the gap and exits from the gap toward the surface acoustic wave source. Such a surface acoustic wave atomizer is known (see, for example, Patent Document 2). This will be described with reference to FIG. This surface acoustic wave atomizing apparatus includes a liquid film forming member 95 that forms a gap with the substrate surface in place of the rough surface region 93 in FIG. The width of the liquid film forming member 95 (the length in the propagation direction of the surface acoustic wave W) is set to a width that maintains a balance between the liquid supply amount and the atomization amount.

JP 2009-154058 A JP 2008-104974 A

  However, in the surface acoustic wave atomization apparatus as shown in Patent Documents 1 and 2 described above, a large amount of liquid that is not involved in atomization may still exist on the propagation surface of the surface acoustic wave. Therefore, there is a problem that the energy of the surface acoustic wave is consumed. Further, in the surface acoustic wave atomization apparatus as described above, the substantial atomization region is limited to the portion facing the comb-shaped electrode that is the generation source of the surface acoustic wave. There is a problem that it is necessary to increase the size of the apparatus for the increase.

  The present invention solves the above-described problems, can easily supply liquid, can stably maintain a balance between the supply amount and the atomization amount, and requires less power without increasing the size of the substrate constituting the apparatus. It is an object of the present invention to provide a surface acoustic wave atomizer capable of stably generating a large amount of fine particles.

  In order to achieve the above object, a surface acoustic wave atomization apparatus according to the present invention includes a substrate made of a piezoelectric material on which a pair of comb electrodes are formed, and elastically applies to the surface of the substrate by applying a high frequency voltage to the comb electrodes. In the surface acoustic wave atomization device that generates surface waves and atomizes the liquid supplied to the surface of the substrate by the surface acoustic waves, a groove is formed on the surface of the substrate, and the groove is formed on one end of the groove. The liquid is supplied to the surface acoustic wave propagation region by capillary action and atomized by the surface acoustic wave propagating on the bottom surface of the groove.

  In this surface acoustic wave atomizer, the groove is preferably formed smoothly with an inclined surface at an edge in contact with the substrate surface.

  In this surface acoustic wave atomizer, it is preferable that a plurality of grooves are formed.

  In this surface acoustic wave atomization device, the plurality of grooves may be arranged so that the surface acoustic waves pass repeatedly.

  According to the surface acoustic wave atomization apparatus of the present invention, the liquid injected into the groove on the substrate surface can be stably and necessaryly supplied to the surface acoustic wave propagation region by capillary action, and the liquid in the groove is kept constant. Thickness can be maintained. Thereby, the liquid can be efficiently atomized into a large amount of fine particles without increasing the size of the substrate.

(A) is a perspective view about the surface acoustic wave atomization apparatus which concerns on one Embodiment of this invention, (b) is sectional drawing of the groove direction of the groove part of the apparatus, (c) is the groove cross direction of the apparatus. Sectional drawing. (A) is a perspective view about the surface acoustic wave atomization apparatus which concerns on other embodiment, (b) is sectional drawing of the groove cross direction of the apparatus. (A) is a top view about the surface acoustic wave atomization apparatus which concerns on other embodiment, (b) is sectional drawing of the groove cross direction of the apparatus. (A) is sectional drawing which shows the modification of the apparatus, (b) is sectional drawing which shows the other modification of the apparatus. (A) is a top view which shows the further another modification of the apparatus, (b) is a top view which shows the other modification of the apparatus. The perspective view about the surface acoustic wave atomization apparatus which concerns on other embodiment. (A) is sectional drawing of the conventional surface acoustic wave atomization apparatus, (b) is sectional drawing of the other conventional surface acoustic wave atomization apparatus.

  Hereinafter, a surface acoustic wave atomization apparatus according to an embodiment of the present invention will be described with reference to the drawings. Further, the orthogonal coordinate axis XY in the drawing is referred to as appropriate. Fig.1 (a) (b) (c) shows the surface acoustic wave atomization apparatus 1 which concerns on one Embodiment. As shown in FIG. 1A, the surface acoustic wave atomization apparatus 1 includes a substrate 2, and a pair of comb electrodes 3 for generating a surface acoustic wave W is formed on the surface S of the substrate 2. Further, the substrate 2 is formed with a groove 4 reaching the propagation region of the surface acoustic wave W. The surface acoustic wave atomization apparatus 1 supplies the liquid 5 thrown into one end side of the groove 4 to the propagation region of the surface acoustic wave W by capillary action, holds it in the groove 4, and propagates the bottom surface of the groove 4. Atomization is caused by the surface acoustic wave W. Hereinafter, each part will be described in detail.

The substrate 2 is composed of a piezoelectric material itself, such as a piezoelectric material such as LiNbO ₃ (lithium niobate). Further, the substrate 2 may be a substrate having a piezoelectric material only on the surface portion where the surface acoustic wave W exists. For example, the substrate 2 may be one in which a piezoelectric thin film, for example, a PZT thin film (lead, zirconium, titanium alloy thin film) is formed on the surface of a non-piezoelectric substrate. A surface acoustic wave W is generated and propagated on the surface portion of the piezoelectric thin film of the substrate 2.

  The comb-shaped electrode 3 is an electrode (IDT: Inter Digital Transducer) formed by engaging two comb-shaped electrodes on the surface of a piezoelectric material. The width of the comb electrode 3 in the Y direction (the direction orthogonal to the propagation direction X of the surface acoustic wave W) is preferably about 20 times the wavelength λ or more in order to generate a stable surface acoustic wave W. Good. The comb teeth adjacent to each other of the pair of comb-shaped electrodes 3 belong to different electrodes, and are arranged along the X direction at a pitch that is half the wavelength λ of the generated surface acoustic wave W. By applying a high-frequency (for example, MHz band) voltage from the electric circuit 10 for applying a high-frequency voltage to the comb-shaped electrode 3, the electrical energy is converted into wave mechanical energy by the comb-shaped electrode 3, and the surface S of the substrate 2. A surface acoustic wave W is generated. The amplitude of the surface acoustic wave W is determined by the magnitude of the voltage applied to the comb electrode 3. The surface acoustic wave W becomes a wave having a width corresponding to the width at which the teeth of the comb-shaped electrode 3 intersect, and propagates in a direction perpendicular to the teeth of the comb. Since the comb-shaped electrode 3 generates surface acoustic waves propagating in opposite directions on both sides, the so-called unidirectional electrode having a reflector on the substrate surface and generating a surface acoustic wave W propagating only in the X direction. You may comprise as.

  As shown in FIGS. 1A, 1 </ b> B, and 1 </ b> C, the groove 4 propagates from the end portion on the side of the propagation direction X of the surface acoustic wave W in the substrate 2 to a position where it enters the propagation region of the surface acoustic wave W. It is formed parallel to the direction X. In other words, the groove 4 is a step structure with a long minute gap provided on the surface S of the substrate 2. An inclined surface 4 a is formed at the edge of the groove 4 at the edge in contact with the substrate surface, and the surface S of the substrate 2 and the bottom surface of the groove 4 are smoothly connected. Therefore, the surface acoustic wave W generated by the comb-shaped electrode 3 and directed toward the groove 4 reaches the inside of the groove 4 and propagates along the groove 4 along the bottom surface of the groove 4. When the liquid 5 is poured into one end side of the groove 4 by an appropriate liquid supply means 5a, the liquid 5 enters the tip of the groove 4 on the center side of the substrate 2 along the groove 4 by capillary action. The liquid that has entered the groove 4 is held in the groove 4 with a predetermined uniform thickness. The liquid 5 spreading along the groove 4 can be used for atomization. That is, since the surface acoustic wave W propagating along the groove 4 exists on the bottom surface of the groove 4, the liquid 5 distributed in the groove 4 with a uniform thickness over a long distance is dispersed in the fine particles M. Can be atomized efficiently. The liquid supply means 5a may be constituted by a pump that sends a minute amount of the liquid 5, or may be constituted by a method using a capillary phenomenon. The structure of the inclined surface 4a can be set based on the depth of the groove 4, the wavelength of the surface acoustic wave W, and the like. The width and depth of the groove 4 are determined based on the physical properties such as the surface tension of the liquid 5 to be atomized and the amplitude (energy) of the surface acoustic wave W to be injected. The dimensions can be maintained.

  According to the present embodiment, since the liquid 5 is supplied into the groove 4 by capillary action, a necessary and sufficient amount of the liquid 5 can be stably supplied into the groove 4 and is held in the groove 4 and has a uniform thickness. The liquid 5 spreading along can be effectively used for atomization. That is, the height of the liquid level of the liquid 5 supplied to the substrate surface can be made constant, and the atomization efficiency is improved. Further, the distance at which the surface acoustic wave W interacts with the liquid 5 can be increased by setting the structure (length) of the groove 4 and the arrangement thereof. That is, the bottom surface of the groove 4, that is, the effective area used for atomization can be increased by increasing the length, and the substrate 2 can be atomized more efficiently without increasing the size.

  In this embodiment, in the conventional apparatus, when the liquid is directly disposed on the substrate surface and the liquid is spread on the substrate surface, an appropriate thickness cannot be maintained over a wide range due to the influence of the surface tension of the liquid. This solves the problem that it is difficult to transfer energy in a liquid layer that is too thick. In other words, since the presence of a large amount of liquid in the conventional apparatus is excluded in the groove 4, energy loss of the surface acoustic wave W is avoided. Further, by supplying the liquid 5 by capillary action, the balance between the liquid supply amount and the atomization amount can be maintained in a self-regulating manner, and the presence of the liquid 5 not involved in the atomization can be suppressed. A large amount of fine particles can be stably sprayed with less power consumption. When the liquid held by the surface tension is consumed by atomization, the liquid is automatically replenished by the surface tension. In addition, liquid is supplied by utilizing capillary action, and the liquid 5 is held in the groove 4 by surface tension. Therefore, by appropriately setting the cross section of the groove 4, the liquid 5 maintained at an optimum thickness can be obtained. A thin layer can be formed effectively. Further, since the step at the tip of the groove 4 has an inclined surface 4 a and is formed smoothly, reflection of the surface acoustic wave W at this step portion is suppressed and the surface acoustic wave W is efficiently transferred to the bottom surface of the groove 4. Can lead to.

  The surface acoustic wave atomizer 1 is used as, for example, a medical atomizer that is driven by a low-power dry battery. In this case, the liquid 5 to be atomized is water or a chemical solution in which a chemical is dissolved in water. Moreover, when driving the surface acoustic wave atomizer 1 with comparatively high electric power, it is used as a humidity adjusting device for preventing drying, for example.

  Next, a surface acoustic wave atomization apparatus 1 according to another embodiment will be described with reference to FIGS. This surface acoustic wave atomizing device 1 is provided with three grooves 4 in parallel in the surface acoustic wave atomizing device 1 shown in FIG. According to the present embodiment, by increasing the number of grooves 4, it is possible to atomize in a larger amount according to the increase in the number of devices without increasing the size of the apparatus.

  Next, with reference to FIG. 3 (a) (b), the surface acoustic wave atomization apparatus 1 which concerns on other embodiment is demonstrated. In the surface acoustic wave atomization apparatus 1, the groove 4 is formed so as to cross the surface S of the substrate 2 so as to be orthogonal to the direction X instead of being parallel to the propagation direction X of the surface acoustic wave W. 2 is different from the surface acoustic wave atomizer 1 shown in FIG. The liquid 5 is introduced from the end side of each groove 4 and supplied to the center side of the substrate 2 by capillary action. In this embodiment, the plurality of grooves 4 are arranged so that the surface acoustic wave W passes repeatedly. That is, the surface acoustic wave W propagates alternately on the surface S of the substrate 2 and the bottom surface of the groove 4 while going up and down the step of the groove 4, and when propagating on the bottom surface of the groove 4, Atomize the liquid 5. That is, the surface acoustic wave W is used a plurality of times due to the presence of the plurality of grooves 4. The surface acoustic wave atomization apparatus 1 having such a configuration does not need to include the liquid film forming member 95 as shown in FIG. 7B, and can be configured more simply and more efficiently. A large amount can be atomized. In this arrangement of the grooves 4, as shown in FIGS. 4A and 4B, in order to suppress the reflection of the surface acoustic waves W, each groove 4 has its both sides, that is, the propagation of the surface acoustic waves W. It is preferable to provide the inclined surface 4b at the edge in contact with the substrate surface positioned in the direction.

  Next, a surface acoustic wave atomization apparatus 1 according to another embodiment will be described with reference to FIGS. In the surface acoustic wave atomization device 1 shown in FIG. 5A, the three grooves 4 in FIG. 3A described above are formed obliquely with respect to the direction X. That is, even if the groove 4 has a configuration not orthogonal to the direction X, the same effect as described above can be obtained. Moreover, the surface acoustic wave atomization apparatus 1 shown in FIG.5 (b) is what the one end side of the three groove | channels 4 in above-mentioned FIG.3 (a) is connected by the common recessed part 4c. In this surface acoustic wave atomization apparatus 1, the liquid 5 can be supplied to the grooves 4 by introducing the liquid 5 into the recesses 4 c.

  Next, a surface acoustic wave atomization apparatus 1 according to still another embodiment will be described with reference to FIG. This surface acoustic wave atomization apparatus 1 uses the surface acoustic wave atomization apparatus 1 shown in FIG. 2 in a vertical type, uses a liquid container as the liquid supply means 5a, and has an end portion of the substrate 2. The liquid 5 is raised along the groove 4 by utilizing capillary action. According to the present embodiment, liquid can be easily charged and the balance between the liquid supply amount and the atomization amount can be kept more stable. The arrangement of the substrate 2 is not limited to being vertical, but can be inclined.

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the configurations of the above-described embodiments can be combined with each other. For example, you may make it provide the groove | channel which combined the groove | channel 4 shown in FIG. 2, and the groove | channel 4 shown in FIG. The number of grooves 4 can be two or four or more. The groove 4 in FIGS. 3 and 5 can be a groove whose one end is opened and whose other ends are closed, instead of the structure crossing the surface S of the substrate 2. Moreover, it can replace with the rectangular cross-sectional shape of the groove | channel 4 shown in FIG.1 (c), and can be made into grooves, such as a trapezoidal cross section, a reverse trapezoid cross section, and an elliptical arc-shaped cross section. Further, the shape of the groove 4 in the length direction is not limited to a linear shape, and may be a bent shape or a smooth curved shape.

DESCRIPTION OF SYMBOLS 1 Surface acoustic wave atomizer 2 Substrate 3 Comb electrode 4 Groove 4a, 4b Inclined surface 5 Liquid S Surface of substrate W Surface acoustic wave X Propagation direction

Claims (4)

A substrate made of a piezoelectric material on which a pair of comb-shaped electrodes are formed, and a surface acoustic wave is generated on the surface of the substrate by applying a high-frequency voltage to the comb-shaped electrode, and is supplied to the surface of the substrate by the surface acoustic wave. In the surface acoustic wave atomization device for atomizing the liquid to be
Grooves are formed on the surface of the substrate,
A surface acoustic wave atomization device characterized in that a liquid charged into one end of the groove is supplied to a surface acoustic wave propagation region by capillary action and atomized by a surface acoustic wave propagating on the bottom surface of the groove. .   The surface acoustic wave atomization device according to claim 1, wherein the groove has an inclined surface at an edge in contact with the substrate surface and is smoothly formed.   The surface acoustic wave atomizer according to claim 1 or 2, wherein a plurality of the grooves are formed.   The surface acoustic wave atomization device according to claim 3, wherein the plurality of grooves are arranged so that surface acoustic waves pass repeatedly.

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