An ultrasonic wave nebulizer

Abstract: An ultrasonic wave nebulizer for converting water or liquid to mist has a disc-shaped piezoelectric vibrator (1) which has a pair of surfaces one of which is defined as an operation surface. A mesh (3) is located close to said operation surface so that a gap (G) or a thin water or liquid film is defined between the mesh and the operation surface. The gap spacing is smaller than the diameter of water drop which is composed by surface tension of water when no mesh were located. Upon excitation of the vibrator with high frequency, the water film is converted to mist. Fresh water is supplied in said gap spacing through capillarity. The exciting frequency is almost the same as the resonant frequency of the vibrator. The present nebulizer is useful for a small atomizer which operates with small power consumption.

Description: BACKGROUND OF THE INVENTION The present invention relates to an ultrasonic wave nebulizer which atomizes water or liquid with small power consumption. Conventionally, an ultrasonic wave nebulizer for atomizing water to adjust room humidity has been known. In that atomizer, an ultrasonic wave vibrator which vibrates in thickness direction is mounted at a bottom of a water tank. Fig. 1A shows a prior art atomizer in which a tank 102 which has an ultrasonic wave vibrator 103 at the bottom of the same contains water 101. When the piezoelectric vibrator 103 vibrates, water column 104 is generated on the surface of the water 101, and the water column 104 generates fine mist. Fig. 1B shows the relations between water depth (H) and the amount of generated mist (vertical axis). When the vibration frequency is 1.7 MHz, and the diameter of the vibrator is 20 mm, the maximum generation of mist is obtained when the water depth is from H=30 mm to H=40 mm. However, the prior atomizer has the disadvantage that the size of the device is rather large, since the vibrator must be mounted at the bottom of the water tank with a depth of 30-40 mm. Further, the prior atomizer has the disadvantage that the power consumption is rather large as shown in Fig. 1C in which the horizontal axis shows the power consumption, and the vertical axis shows the amount of mist. The minimum power consumption W₀ in a prior art nebulizer is around 6 watts. As an atomizer for converting 400 cc/hour of water to mist consumes about 40 watts, that power consumption is too high to a battery operated atomizer or a portable atomizer. Another prior atomizer is shown in JP-Y-6338950 as shown in Figs. 2A and 2B, in which the numeral 111 is a cone shaped horn having a resonator plate 112 on the end having the smaller diameter, and a piezoelectric vibrator 113 on the other end having the larger diameter. The numeral 114 is a capillary tube for supplying water to the resonator plate 112. The length of the horn 111 or the length between the plate 112 and the vibrator 113 is designed to be half wavelength. As the vibration of the vibrator 113 is amplified according to the ratio of the area of the plate 112 and the area of the vibrator 113, the amplitude of the plate 112 is very large, and water drops on the plate 112 are atomized. However, the atomizer of Fig. 2 has the disadvantages that (1) only water drops close to the outlet of the tube 114 are atomized, and so, the essential operation area of the plate 112 is small, (2) as the vibration is mechanically amplified the horn must be manufactured very precisely, and malfunction can occur due to the difference between the thermal expansion of the vibrator and the horn, and (3) the size of mist droplets is rather large (for instance 20 µm), as the operation frequency must be rather low (100-150 kHz for instance) because of the mechanical amplification. If the plate 112 is covered with a mesh in order to provide fine mist, the conversion efficiency from water to mist is decreased because of the presence of a mesh. A nebulizer corresponding to the preamble of claim 1 is disclosed in Review of Scientific Instruments, 58, July 1987, N° 7, New York, USA, P. 1292. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages and limitations of a prior nebulizer by providing a new and improved nebulizer . It is also an object of the present invention to provide a nebulizer which atomizes water or liquid to mist with small power consumption. It is also an object of the present invention to provide a nebulizer which is small in size. Another object of the present invention is to provide a nebulizer which generates fine mist. The above and other objects are attained by an ultrasonic wave nebulizer according to claim 1. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and attendant advantages of the present invention will be appreciated as the same become better understood by means of the following description and accompanying drawings wherein; Fig.1 shows the explanatory figure of a prior art ultrasonic wave nebulizer , Fig.2 shows the structure of another prior art ultrasonic wave nebulizer , Fig.3 is a cross section of the ultrasonic wave nebulizer according to the present invention, Fig.4 is a partially enlarged view of Fig.1 Fig.5 is a circuit diagram of an oscillator which is used for exciting a vibrator, Fig.6 is a modification of a vibrator, Fig.7 is another modification of a vibrator, Fig.8 is another embodiment of a nebulizer , Fig.9 is still another modification of a vibrator, Fig.10 is still another embodiment of a nebulizer , Fig.11 is still another embodiment of a nebulizer , and Fig.12 is still another embodiment of a nebulizer. DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs. 3 and 4 show the first embodiment of the ultrasonic wave nebulizer for atomizing water and/or liquid according to the present invention. In those figures, the numeral 1 is a piezoelectric vibrator which has a front electrode 2A and a rear electrode 2B. Preferably, it is disc-shaped, having a uniform thickness. Those electrodes 2A and 2B are plated on the surfaces of the vibrator. The vibrator 1, and the electrodes 2A an 2B provide a vibrator element TD. One surface of the vibrator element, the surface of the electrode 2A in the embodiment, is defined as an operation surface which converts water to mist. A mesh 3 which has a large number of holes 6 is placed close to said vibrator element TD. The vibrator element TD and the mesh 3 are kept in a ring shaped groove 5 provided in the inner surface of a cylindrical resilient holder 4. In one embodiment, the vibrator is made of ceramics, which is polarized. The front electrode 2A is partially folded to the rear surface as shown in the figure, and the rear electrode 2B is a little smaller than the diameter of the disc so that the electrodes 2A and 2B are not short-circuited with each other. A pair of lead wires are coupled with the electrodes 2A and 2B, so that they are coupled with an exciting oscillator (as shown in Fig.5) through a terminal 60. The lead wires are coupled with the rear surface of the vibrator, but not with the operation surface. The vibrator 1 is excited by applying alternate power between the electrodes 2A and 2B. The exciting frequency is higher than 1 MHz, and preferably in the range of 1.6 MHz - 2.4 MHz. The higher the exciting frequency, the smaller the generated mist is. So, a high frequency excitation higher than 1 MHz is preferable to generate fine mist less than 10 µm of diameter. It should be appreciated that a small gap G exists between the mesh 3 and the front electrode 2A, or the operation surface so that water or liquid W which is subject to be converted to mist expands between the mesh and the vibrator through capillary action. The gap spacing G is preferably smaller than 100 µm. Therefore, the gap spacing is smaller than the diameter of a water drop under surface tension placed on the vibrator if no mesh were provided. The gap G is provided by supporting the mesh 3 on the vibrator 1 through a thin ring shaped support (not shown). Therefore, it should be appreciated that a very thin water film covers the vibrator, and that film is atomized. Because of the very thin water film, the water is atomized with relatively low power. The mesh 3 is made of for instance stainless steel with a thickness of 10 µm, and a large number of holes each of which has a diameter d of about 5-100 µm. The numeral 7 is a supply tube for supplying water or liquid onto the vibrator element TD. Although the hole 6 in Fig.4 is tapered so that the hole is larger downwardly, an oppositely tapered hole or non-tapered hole of the mesh is of course possible. Converted mist is released into the air through the holes of the mesh. In this case, it should be noted that the size of mist, or diameter of each mist droplet is defined by the exciting frequency of the vibrator, but not by the diameter of the holes of the mesh. Fig. 5 shows a circuit diagram of an oscillator which excites the vibrator 1. In the figure, the symbol Q is a transistor for oscillation, T₁ is a booster transformer, T₂ is a tuning transformer having a primary winding N₁ coupled with the vibrator element TD in series and a secondary winding N₂ coupled with a capacitor C₁ in parallel. The resonance frequency of the tuning circuit of the secondary winding N₂ and the capacitor C₁ is almost the same as the resonance frequency of the vibrator element TD. It should be appreciated that the fact that the tuning frequency of the oscillator circuit is the same as that of the vibrator element is one of the features of the present invention. In the prior art, the vibration element is excited with a frequency higher than the resonance frequency of the element so that the vibration element has inductive characteristics. The symbol C₂ is a capacitor for preventing DC potential to the transformer. The symbol R is a resistor for providing base potential to the transistor, and E is a DC power supply (for instance 6-12 V) which is for instance a battery. Fig. 5 shows the embodiment of a self-oscillation circuit of current feed-back type so that the vibrator element TD is excited in the thickness direction with the frequency close to the resonant frequency f r of the vibrator element. In Fig. 5, when the transistor Q is in ON state, the potential is applied to the vibrator element TD which then vibrates with the frequency close to the resonant frequency of the vibrator, and the resonant signal which is tuned by the tuning transformer T₂ is fed back to the transistor Q. Then, the transistor Q turns ON again. The circuit keeps the oscillation so that the current I t in the vibrator is the maximum, in other words, the oscillation frequency is close to the resonance frequency f r of the vibrator element TD. When the oscillation circuit of Fig. 5 applies the excitation power between the electrodes 2A and 2B of the vibrator element TD of Fig. 3 (for instance the frequency is 2.4 MHz) so that the vibrator element is vibrated in the thickness direction, and the supply capillary 7 supplies liquid or water which is to be turned to mist on the vibrator TD, the liquid or water expands in the thin gap G between the operation surface of the vibrator ceramics 1 and the mesh 3. And, a liquid column is generated at each small hole 6 of the mesh 3. Then, the top portion of those liquid columns are converted to mist by the vibration of the vibrator, and the mist is spread into the air. It should be understood in that embodiment that the mesh 3 provides the thin water film of uniform thickness on the vibrator. The area of the liquid is large as the water film is thin, and so, the ultrasonic wave energy is efficiently converting the water film to mist. When the input power to the vibrator element TD is 3.5 watt, an amount of water of 2 cm³/minute is converted to mist in our experiment. So, the amount of mist per input power is quite high as compared with that of Fig. 1A. As no horn like in the prior art is necessary, the present invention provides a small size nebulizer . One of the important features of the present invention as compared with the prior structure of Fig. 1 is that the operation surface of the vibrator is essentially disposed in air, while the operation surface of the prior art is disposed in water for cooling the vibrator. If the vibrator of the prior art was disposed in air, it would be broken in a short time because of the high input power to the vibrator. So, the prior art device must have an alarm means for switching off the vibrator when no water is supplied. The present vibrator is not broken even if no liquid or no water is supplied, since the input power is small. So, no alarm means for switching off the vibrator is necessary in the present invention. The input power of high frequency to the vibrator in the present invention is preferably less than 5 watts. Fig. 6 shows a modification of the invention. In Fig. 6, a supply felt 21 is used, instead of a supply capillary tube 7, for supplying liquid or water to the peripheral portion of the vibrator element TD. Fig. 7 shows another modification, which has no specific water supply means. In this modification, a part of the vibrator TD and a part of the mesh 3 are placed in liquid or water which is to be turned to mist, and the liquid or water raises up and expands in the gap between the vibrator and the mesh by capillarity. Fig. 8 shows another embodiment of the present invention. The essential feature of the embodiment of Fig. 8 is that the width of the mesh is smaller than the diameter of the vibrator. In Fig. 8, (A) is a plane view, (B) is an enlarged side view, and (C) shows modifications of the mesh. A disc shaped vibrator 1 is kept in a resilient holder 4, which is fixed to the main holder 31. The mesh 3A which has a plurality of small holes is tapered as shown in the figure so that the extreme end 3A-b of the mesh 3A is narrowed. The narrow tapered end 3A-b touches the central portion of the vibrator 1. Thus, the essential width W which provides a gap space between the mesh and the vibrator 1 is smaller than the diameter D of the vibrator 1. In the above structure, the mist conversion is effected in the area (i) in which a thin gap is provided between the mesh 3A and the vibrator 1. The mesh 3A is fixed to the holder 31 by an essentially L-shaped plate 22 which is fixed to the holder 31 by using a screw 23. The mesh 3A is fixed to the L-shaped plate by using a screw 24 and a nut 25 so that the tapered end 3A-b is positioned close to the vibrator 1. The water or liquid which is subject to mist conversion is contained in the container 26 which supplies water to the area (i) through capillary attraction by a supply means 21, which has a pair of thin plastics sheets f-f which sandwich fiber g. The fiber g and the sheets f-f are fixed by the stopper h. The supply means 21 has one end in the water W, and the other end on the mesh 3A at the area (i). Thus, the water W is supplied to the area (i) through the capillary attraction and at the area (i) the water is converted to mist. In an experiment with the structure of Fig. 8, an amount of water of 2 cm³/minute is converted to mist with a supply power of 3 W. The size of mist depends upon the exciting frequency, but not on the size of holes of the mesh, and so, the preferable exciting frequency is 1.0-3.0 MHz so that fine mist is obtained. The amount of water supplied by supply means 21 must be smaller than the mist conversion capability at the area (i) by the vibrator 1, since if too much water is supplied, the mist conversion stops and no mist is generated. Fig. 8C shows two modifications of the mesh. Fig. 8C(a) shows a rectangular mesh 3B which has no tapered end. The width W of the mesh 3B is smaller than the diameter D of the vibrator 1. The end of the mesh 3B is placed close to the vibrator 1 so that a narrow gap is provided between the mesh and the vibrator at the area (i). Fig. 8C(b) shows another modification 3C of the mesh, in which the mesh is circular, but has a pair of fan-shaped windows 3C-b so that an essentially tapered end (i) with a width smaller than the diameter of the vibrator disc, is provided around the center of the mesh. The diameter of the mesh 3C is almost the same as that of the vibrator 1. The embodiment of Fig. 8 has the advantage that a uniform gap with the desired spacing is obtained between the mesh and the vibrator. In the structure of Fig. 3, when the mesh is deformed, a uniform gap with a desired spacing is not obtained. When the gap is not uniform, the thickness of the water film is not uniform, and the resonance frequency of the vibrator which has a non-uniform water film is distributed on the operation surface, because of the difference of thickness of the water film. As the vibrator must be excited with a frequency which is almost the same as the resonance frequency of the vibrator, a non-uniform water film decreases the mist conversion. Fig. 9 shows a modification which provides the desired spacing of a gap between the mesh and the vibrator. The same numerals in Fig. 9 designate the same members as those in Fig. 3. In Fig. 9(A), the mesh 3D has steps so that a plurality of projected portions 3D-a and a plurality of recessed portions 3D-b are provided on the mesh 3D. The recessed portions 3D-b touch the vibrator 1, so that a gap spacing is provided between the projected portions 3D-a and the vibrator 1. As the area of each projected portion is rather small, it is easy to keep the desired gap spacing in the projected portions 3D-a. The periphery of the mesh is made by recessed portions. Fig. 9B shows another modification, in which the mesh 3E has a ring shaped recessed portion 3E-b, and a single projected portion 3E-a. The gap spacing between the mesh and the vibrator is provided between the projected portion 3E-a and the vibrator. Fig. 10 shows another embodiment of the nebulizer according to the present invention. The same numerals in Fig. 10 designate the same members as those in Fig. 3. The essential features of Fig. 10 are that the electrodes 2A′ and 2B′ of the vibrator have the same diameter as that of the vibrator, and have no offset portion, and that the power is supplied to the vibrator through the conductive mesh 3F. It should be noted that the electrode 2A in Fig. 3 is offset to the rear surface of the vibrator so that the power is supplied from the rear surface. In Fig. 10, the numeral 1 is a disc-shaped vibrator, which has a pair of disc-shaped electrodes 2A′ and 2B′. The diameter of those electrodes is the same as that of the vibrator 1. The vibrator 1 is sealingly mounted in an annular groove 5 of a resilient holder 4. The mesh 3F is essentially in rectangular shape, and preferably has a tapered end as shown in Fig. 8. The width of the mesh 3F is smaller than the diameter of the vibrator 1. One end of the mesh 3F is inserted in a slit 4A which is provided in the holder 4 so that the mesh 3F is essentially horizontally fixed to the holder 4. In this case, the other end of the mesh 3F touches the vibrator 1, and the preferable gap spacing is provided at a portion between the mesh 3F and the vibrator 1. It should be appreciated that the portion inserted in the holder 4 does not need to be meshed, but a mere conductive plate is sufficient for the operation. The resilient holder 4 is covered with a conductive cap 42 which has a circular opening 41, and has an essentially L-shaped cross section. The end 3F-b of the mesh 3F is offset when the cap 42 engages with the holder 4, and the cap 42 and the mesh 3F are electrically coupled through the offset end 3F-b of the mesh 3F. The vibrator 1 is excited by a high frequency oscillator 35. The preferable circuit diagram of the oscillator is shown in Fig. 5. The numerals 36A and 36B are lead wires for coupling the oscillator 35 with the vibrator 1. One lead wire 36A is coupled with the cap 42, and the other lead wire 36B is coupled with the electrode 2B′ of the vibrator 1. Therefore, it should be noted that only one lead wire is soldered to the vibrator, and so, the assembling work of the vibrator is reduced. It should be noted that the mesh which is conductive electrically connects the cap 42 and the electrode 2A′ of the vibrator 1. The water or liquid is supplied through the supply tube 7 to the vibrator, and the water or liquid is converted to mist at the portion where the preferable gap spacing between the mesh 3F and the vibrator is provided. As a modification of Fig. 10, the vibrator 1 may be fixed horizontally, and the mesh 3F may, be inclined. Fig. 11 shows another embodiment of the present invention, and the same numerals designate the same members as those in Fig. 8. The electrodes 2A′ and 2B′ in Fig. 11 have the same diameter as that of the vibrator 1, as with the device of Fig. 10. The essential feature of Fig. 11 is that the operation surface 2A′ of the vibrator 1 is placed outside of the holder 4B, so that a distance (a) is provided between the operation surface 2A′ of the vibrator 1 and the main surface 31a of the holder 31. The advantage of that structure is that all the area of the operation surface of the vibrator 1 functions to generate mist. So, a vibrator of small diameter is sufficient for operation. The vibrator 1 is sealingly fixed to the resilient holder 4B by adhesive or snap fix. The electrical lead wires are coupled with the rear electrode 2B′ and the L-shaped plate 22 which is coupled electrically with the electrode 2A′ by means of the mesh 3A. Alternatively, the electrical lead wires may be coupled with the electrodes 2A′ and 2B′. The electrical lead wires are connected to an oscillator (not shown) through a terminal 60. The mesh 3A is engaged with the operation surface 2A of the vibrator. The shape of the mesh 3A may be tapered and rectangular as shown in Fig. 8A, or rectangular, or circular with a pair of sector windows. One end of the mesh 3A is fixed to the L-shaped plate 22, which is then fixed to the holder 31, as with the device of Fig. 8. The water tank 26 which contains water W supplies water to the vibrator 1 by a capillary means 21. The water thus supplied to the vibrator 1 provides thin water film between the operation surface of the vibrator 1 and the mesh 3A, and the water film is converted to mist by the ultrasonic wave vibration. Fig. 12 shows another embodiment of the present invention. The same numerals in Fig. 12 designate the same members as those in Fig. 8. The important features of Fig. 12 are that the vibrator is placed horizontally, and that the water tank 26 is located at a higher level than the operation surface of the vibrator 1 so that the water is supplied to the vibrator 1 downwardly. The structure of the vibrator is similar to that of Fig. 10 which has a pair of electrodes having the same diameter as that of the vibrator. However, another type of vibrator, for instance, the vibrator of Fig. 3, may be used in the embodiment of Fig. 12. In Fig. 12, the numeral 1 is a vibrator which has a pair of electrodes 2A′ and 2B′ on the surfaces of the vibrator disc. The vibrator 1 is mounted in an annular groove in a resilient holder 4 which is fixed in a rigid holder 31. A conductive mesh 3A which is of rectangular shape, or tapered rectangular shape, or circular shape with a pair of sector windows as shown in Fig. 8B or Fig. 8C is engaged with the operation surface of the vibrator so that one end of the mesh contacts the operation surface of the vibrator. The other end of the mesh is fixed to the L-shaped plate 22 by a screw 24 and a nut 25. The L-shaped plate 22 is then fixed to the rigid holder 31 by a screw 24a. The vibrator 1 is supplied high frequency energy through the rear electrode 2B′ and the front electrode 2A′ which is connected to the terminal 60 through the mesh 3A, and the L-shaped conductive plate 22. The water tank 26 is located above the vibrator 1, and has a cap 55 which seals the tank 26. From the tank 26 protrudes a hollow extension 54A at the bottom 54 of the tank 26. The bottom 54 has at least one small hole 57. The diameter of the hole 57 is for instance less than 1 mm so that water does not flow through the hole 57 because of the surface tension of water. A bundle of fibers 58 is fixed in said extension 54a so that water W in the tank 26 is supplied to the vibrator 1 through the fibers 58. One end of the fibers 58 is slanted, and is engaged with the surface of the mesh 3A. Preferably, the tank 26 is located at any place except just above the vibrator 1 so that the tank does not disturb the operation of the mist generation. In operation, water in the tank is supplied to the vibrator through the fibers 58. The water thus supplied to the vibrator is converted to mist by the vibration, and then, fresh water is supplied by the amount which is converted to mist. When water is supplied from the tank, the pressure in the tank 26 decreases, and air is supplied into the tank 26 through the small hole 57. The advantage of the embodiment of Fig. 12 is that no surplus water is supplied to the vibrator even when the vibrator is switched off. If surplus water is supplied to the operation surface, no mist conversion is carried out. In the structure of Fig. 12, when water is on the vibrator 1, no water is supplied to the vibrator, and when the water film of the operation surface is used up, fresh water is supplied, because of the closed structure of the tank 26. It should be noted that no water spills out through a hole 57, since the hole is very small and prevents leak of water by surface tension. When water in the tank 26 is used up, fresh water is supplied into the tank by opening the cap 55. In a modification of Fig. 12, lead wires for power supply to the vibrator may be soldered to the electrodes 2A′ and 2B′, instead of supplying the power through a mesh and an L-shaped plate. In the above description, the vibrator is located either horizontally, or vertically, in any embodiments. When a nebulizer is used as a smoke generator in a toy of a steam locomotive, a horizontal vibrator would be preferable. In another application of the nebulizer , for instance as a sprayer for medical purposes, a vertical vibrator would be preferable. From the foregoing it will now be apparent that a new and improved neublizer or an atomizer has been found. It should be understood of course that the embodiments disclosed are merely illustrative and are not intended to limit the scope of the invention. Reference should be made to the appended claims, therefore, rather than the specification as indicating the scope of the invention.

Claims: An ultrasonic wave nebulizer comprising: a piezoelectric vibrator (1) defining an operation surface (2A) on one of its surfaces, a holder (4, 5) for holding said vibrator (1), a mesh (3) having at least a portion located close to said operation surface (2A) so that an essential gap space (G) is provided between said portion of the mesh and the operation surface (2A) of the vibrator (1), means (7) for supplying liquid to said gap space (G), a high frequency generator, and connecting means (6) for connecting said generator to electrodes of the vibrator, characterized in that: it has a front electrode (2A) and a rear electrode (2B), a thin liquid film is provided in said gap space (G) through capillarity, and said vibrator (1) vibrates in thickness direction of the vibrator (1) upon being excited with high frequency power between said electrodes (2A, 2B) substantially at the resonance frequency of the vibrator (1) to convert said thin liquid film to mist. An ultrasonic wave nebulizer according to claim 1, wherein said vibrator (1) is in disc shape, and made of polarized ceramics. An ultrasonic wave nebulizer according to claim 1, wherein said mesh (3A) is of rectangular shape with one end tapered and providing said gap space. An ultrasonic wave nebulizer according to claim 1, wherein said mesh (3B) is of rectangular shape with one end providing said gap space. An ultrasonic wave nebulizer according to claim 1, wherein said mesh (3C) is of circular shape with a pair of sector shaped windows. An ultrasonic wave nebulizer according to claim 1, wherein said mesh (3D,3E) has a step so that the mesh has a projected portion and a recessed portion, and said gap space is provided between the projected portion and the operation surface of the vibrator. An ultrasonic wave nebulizer according to claim 1, wherein said mesh (3F) is conductive, and touches with one of the electrodes, and comprising connecting means connecting said generator with the electrodes of the vibrator through the conductive mesh. An ultrasonic wave nebulizer according to claim 7, wherein said mesh (3F) is held in a slit (4A) provided in the holder (4), which is covered with a conductive cap (42) so that the mesh (3F) is electrically coupled with the cap (42), and said connecting means connects the generator to one electrode (2A′) of the vibrator through said conductive cap (42) and said mesh (3F). An ultrasonic wave nebulizer according to claim 1, wherein operation surface (2A′) of the vibrator (1) is placed outside of said holder (4B). An ultrasonic wave nebulizer according to claim 1, wherein said vibrator (1) is held so that the operation surface of the vibrator is essentially horizontal, a closed liquid tank (26) is located above said operation surface, and comprises a conduit (53) connecting said tank to said operation surface. An ultrasonic wave nebulizer according to claim 1, wherein the oscillation frequency of said generator is higher than 1 MHz. An ultrasonic wave nebulizer according to claim 1, wherein said gap spacing (G) is less than 100 µm. An ultrasonic wave nebulizer according to claim 1, wherein the distance of holes of the mesh is less than 200 µm, and diameter of a hole of the mesh is in the range between 5 µm and 100 µm. An ultrasonic wave nebulizer according to claim 1, wherein said operation surface of the vibrator is essentially held vertically, and liquid is supplied to the operation surface through capillarity. An ultrasonic wave nebulizer according to claim 11, wherein the oscillation frequency is 1.6 MHz. An ultrasonic wave nebulizer according to claim 11, wherein the oscillation frequency is 2.4 MHz. An ultrasonic wave nebulizer according to claim 1, wherein said high frequency generator is supplied with operation power by a battery. An ultrasonic wave nebulizer according to claim 1, wherein one (2A) of the electrodes of the vibrator is offset to a rear surface of the vibrator. An ultrasonic wave nebulizer according to claim 1, wherein input power to said vibrator from said high frequency generator is less than 5 watts.

Inventors: ONO MAKOTO, TAKAHASHI MINORU, ONO, MAKOTO, TAKAHASHI, MINORU
Applicants: TDK CORP, TDK CORPORATION
Application year: 1992
Main classification: B05B17
IPC codes: B05B17