US3901443A

US3901443A - Ultrasonic wave nebulizer

Info

Publication number: US3901443A
Application number: US431202A
Authority: US
Inventors: Sadao Mitsui; Minoru Takahashi
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 1973-02-06
Filing date: 1974-01-07
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26
Also published as: FR2216030A1; FR2216030B1

Abstract

An ultrasonic wave nebulizer according to the present invention comprises a nebulizing chamber containing a liquid to be nebulized and capable of adjusting the surface level of said liquid to a predetermined value, a chamber base disposed at the bottom portion of said nebulizing chamber, a piezo-electric transducer mounted on said chamber base in such a manner that its vibration surface has an inclination of 2*-22* with respect to said surface level of said liquid, a pair of transistors for ultrasonically oscillating the transducer and directly mounted on said chamber base, a conical horn having a predetermined reflection surface and being located on the upper portion of said piezo-electric transducer which makes contact with the bottom portion of said liquid, an exhaust cylinder or duct for exhausting fog composed of minute liquid particles and formed in said nebulizing chamber, and an air supply inlet for guiding or flowing said fog to the generating direction of said fog whereby the effective nebulized amount of said liquid per unit input electric power can be increased, so that a high nebulizing efficiency can be provided.

Description

United States Patent [1 1 Mitsui et al.

[451 Aug. 26, 1975 ULTRASONIC WAVE NEBULIZER [73] Assignee: TDK Electronics Co., Ltd., Tokyo,

Japan 22 Filed: Jan. 7, 1974 211 Appl. No.: 431,202

[30] Foreign Application Priority Data Feb. 6, 1973 Japan 48-15459 Feb. 12, 1973 Japan 48-17601 Feb. 12, 1973 Japan.... 48-17602 Aug. 31, 1973 Japan 48-103005 [52] US. Cl 239/102; 239/338 [51] Int. Cl. B05B 3/14 [58] Field of Search 239/101, 102, 338

[56] References Cited UNITED STATES PATENTS 3,243,122 3/1966 Snaper 239/102 3,469,785 9/1969 Boucher et al. 239/102 3,472,455 10/1969 Johnson et al.. 239/338 3,525,476 8/1970 Boling et al..... 239/338 3,589,606 6/1971 Fish 239/338 Primary ExaminerLl0yd L. King Attorney, Agent, or FirmBurgess, Ryan and Wayne 5 7] ABSTRACT An ultrasonic wave nebulizer according to the present invention comprises a nebulizing chamber containing a liquid to be nebulized and capable of adjusting the surface level of said liquid to a predetermined value, a chamber base disposed at the bottom portion of said nebulizing chamber, a piezo-electric transducer mounted on said chamber base in such a manner that its vibration surface has an inclination of 222 with respect to said surface level of said liquid, a pair of transistors for ultrasonically oscillating the transducer and directly mounted on said chamber base, a conical horn having a predetermined reflection surface and being located on the upper portion of said piezoelectric transducer which makes contact with the bottom portion of said liquid, an exhaust cylinder or duct for exhausting fog composed of minute liquid particles and formed in said nebulizing chamber, and an air supply inlet for guiding or flowing said fog to the generating direction of said fog whereby the effective nebulized amount of said liquid per unit input electric power can be increased, so that a high nebulizing efficiency can be provided.

8 Claims, 11 Drawing Figures AIR INLET PATENTEB A1182 61975 SHEET 1 [1F PATENTEDAUBZBIQYE I 3.901.443

sum 2 OF 5 Fig. 2

PATENTEDAUGZBIHYS R801 4-43 SHEET 3 OF AAA PATENTED EZ IQYS sum 5 n; 6

INPUT POWER P (w) ULTRASONIC WAVE NEBULIZER The present invention relates to an apparatus for nebulizing various liquids utilizing an ultrasonic wave in which the effective nebulized amount of the liquid per unit of input electric power can be increased.

BACKGROUND OF THE INVENTION It is well known that in the conventional ultrasonic wave nebulizer, an ultrasonic wave is injected into a liquid from beneath the surface thereof toward the vertical upward direction, whereby a continuously spouting column of liquid is formed in the injecting direction, and the desired minute liquid particles can be produced and nebulized at a position adjacent to the top end portion of the liquid column. However, such an ultrasonic wave nebulizer as used in the conventional art has objectionable features as described below.

a. The vibration surface of the transduucer for generating a supersonic wave is attached to the bottom portion of the nebulizing chamber in parallel with the surface of the liquid in the nebulizing chamber so that a continuous stream liquid column is formed in a direction vertical to the liquid surface, and large liquid parti cles and water drops which are not being nebulized are produced in an area adjacent to the top end portion of said continuously spouting liquid column, and intermittently fall down therefrom. As a result of this, the form of the continuously generating and spouting liquid column is disturbed and nebulization at the abovementioned adjacent position is decreased, so that a fog of minute liquid particles is intermittently produced.

b. Generally, the transducer of the nebulizer is driven by one to four transistors with an output power of 15 to 50 watts. In this case, as is well known, it is necessary to disperse the heat generated in each transistor during its operation so as to operate the transistor normally. Consequently, in the prior art, a natural air cooling means is utilized for dispersing the heat generated in the transistor into the atmosphere, such as a cooling fan exclusively used for the transistor, or other oscillating frames having a heat dispersing structure. However, according to this natural air cooling method, it is necessary to enlarge the construction of both the heat disperser and entire nebulizer.

c. The relationship between a liquid surface level L (cm), that is the distance between the supersonic wave source and the liquid surface, and a nebulized amount of the liquid Q (cc/hr) is as follows. When the liquid surface level L is in a range of from to 8.0 cm. a sufficient nebulizing capacity can be obtained, and the more preferable conditions are when the liquid surface level L is from to 7.5 cm, the frequency is 1.3 MHz and the diameter of the source is 25. However, to keep the liquid surface level L approximately at a constant value, it is necessary to use an additional liquid supply pump or a liquid surface detector, but in either case, a driving power source or an additional electron circuit is needed.

d. Further, in a conventional supersonic wave nebulizer, since the largest part of an air stream around the spouting liquid formed in the nebulizing chamber flows vertically upward, parallel to the forming direction of the spouting liquid and some part of which flows in the opposite direction, the amount of fog flowing to the exterior of the chamber, inevitably becomes less than that of the generated fog.

SUMMARY OF THE INVENTION The principal object of the present invention is to eliminate the above-mentioned conventional objectionable features and greatly increase the nebulized amount of liquid.

The first characteristic feature of the present invention is that a piezo-electric transducer is mounted on the horizontal bottom portion of a nebulizing chamber containing a liquid to be nebulized by said piezoelectric transducer in such a manner than its vibration surface has a predetermined inclination with respect to the surface of said liquid, so as to continuously form a liquid column spouting stream in a direction inclined to said liquid surface. As a result, large liquid particles and water drops not being nebulized, produced at a position adjacent to the top end portion of said liquid column, are prevented from dropping therethrough.

The second characteristic feature of the present invention is that a conical horn having a predetermined reflection surface is provided on the upper portion of said piezo-electric transducer in contact with the liquid to be nebulized.

The third characteristic feature of the present invention is that the heat produced by transistors is dispersed by a metallic chamber base of the nebulizer and by a water cooling means utilizing the liquid or water to be nebulized as a coolant, so that the constructions of both the heat disperser and the entirenebulizer can be miniaturized.

The fourth characteristic feature of the present in vention is that means are provided for maintaining a distance between the ultrasonic wave source and the liquid surface, that is, the liquid surface level, is kept approximately at a constant value.

The fifth characteristic feature of the present invention is the all the produced fog can be expelled from the nebulizing chamber by arranging the direction of the air flow around the generating portion of the fog approximately parallel to the direction of the water spout produced by the transducer is formed the forming direction of the spouting water.

BRIEF EXPLANATION OF THE DRAWINGS Further features and advantages of the present invention will be apparent from the ensuing description with reference to the accompanying drawings to which, however, the scope of the invention is in no way limited.

FIG. 1 is a cross-sectional view, along Il, of FIG. 2, of one embodiment of a nebulizer according to the present invention, showing the assembly thereof;

FIG. 2 is a bottom view of the nebulizer shown in FIG. 1;

FIG. 3 is a cross-sectional front view of the piezoelectric transducer included in FIG. 1, illustrating its mounting portion in detail;

FIG. 4 is an ultrasonic wave oscillation and amplification circuit diagram for driving the piezo-electric transducer used in FIG. 1;

FIGS. 5 and 6 are respectively characteristic curves of the nebulizer shown in FIG. 1;

FIG. 7 is a cross-sectional front view of another embodiment of the nebulizer according to the present invention;

FIG. 8 is a characteristic curve of the nebulizing apparatus shown in FIG. 7;

FIGS. 9 and 10 are respectively modified embodiments of the nebulizer according to the present invention, and;

FIG. 11 is a photoelectric circuit connection diagram used in FIG. 10.

FIRST EMBODIMENT ACCORDING TO THE PRESENT INVENTION As shown in FIG. 1, an ultrasonic wave nebulizer ac cording to the present invention comprises a nebulizing chamber 2 containing a predetermined amount of liquid l, a piezo-electric transducer 4 inserted into a through hole 3 formed at the bottom portion of said chamber 2 and tightly secured to the bottom portion of the chamber 2 by means of a pair of thumb screws 20 as shown in FIG. 3. Said piezo-electric transducer 4 is electrically driven by an ultrasonic oscillation and amplification circuit shown in FIG. 4 with a natural frequency. A liquid or water column 5 in the shape of a spouting stream is formed on the surface of said liquid 1 in a direction vertical to the transducer surface of said transducer 4, so that water drops 6 such as large liquid particles and fogs 7, consisting of minute liquid particles, are produced at a position adjacent to the top end portion of said water column 5. The fogs 7 so generated are forcibly expelled through an exhaust duct 9 mounted on the upper portion of the nebulizing chamber 2 by applying an air current from an air supply inlet FIG. 2 is a bottom view showing the main elements of the nebulizer shown in FIG. 1. In FIG. 2, there is clearly shown a power transformer 10, a pair of transistors 11 mounted on the bottom portion of the nebulizing chamber 2, a printed circuit plate -12 for mounting or supporting said ultrasonic oscillation and amplification circuit shown in FIG. 4, a motor 13 for driving a fan 14, a power fuse 15, a power cord 16 and a power cord connector 16a.

FIG. 3 is a diagram showing, in detail, the elements for mounting or securing the piezo-electric transducer 4 shown in FIG. 1. In FIG. 3, there is clearly shown a piezo-electric transducer 4 (having a diameter of 20 d) and a thickness of 1.66 mm), a rubber support 17, an aluminum chamber base 18 of the nebulizing chamber 2, a cap 19 for securing the piezo-electric transducer 4, a pair of thumb screws 20 for fastening the transducer 4 and the supporting rubber 17 by securing the cap 19 of the disc 4, and a pair of through holes 21a formed at the bottom portion of the liquid tank 21 shown in FIG. 1. Further, a pair of positive and negative electrodes (not shown) are provided which are sintered on the top surface of the transducer 4 and turned around from a part of the top surface to the bottom surface of the transducer 4 and respectively soldered to lead wires (not shown).

FIG. 4 is an embodiment of an ultrasonic wave oscillation and amplification circuit diagram for driving the piezo-electric transducer 4 used in the nebulizer shown in FIG. 1, according to the present invention. The circuit comprises: an oscillator or oscillation circuit composed of a transistor an inductance coil L capacitors C C and resistors R R a buffer amplifier, composed of a transistor Q a tuning circuit of C and T capacitors C and C and resistors R R a power amplifier, composed of a transistor Q an emitter resistor R and a tuning circuit of C and T An oscillatory output of the oscillator is supplied via a coupling condenser C to the buffer amplifier, via a coupling resistor R to the power amplifier, and then to the piezoelectric transducer 4 shown in FIG. 1. Rectifiers D, D and a condenser C compose a rectifier bridge circuit, and a resistor R and condensers C C compose a smoothing circuit.

The characteristic features of the ultrasonic wave nebulizer having the above-mentioned construction as shown in FIGS. 1 through 3, according to the present invention, will hereinafter be illustrated in detail.

As shown in FIG. I, the surface of the piezo-electric transducer 4 is not arranged in parallel with the surface of the liquid 1, but is mounted on a bottom portion of the nebulizing chamber 2 in such a manner that its vibration surface has a predetermined inclination 9 with respect to the surface of the liquid 1. Consequently, the water column 5 in the shape of the spouting stream is continuously formed on the surface of the liquid 1 with a certain inclination to the surface of the liquid 1. In this case, water drops such as large liquid particles are scattered from the tip end portion of the water column 5 and drop down onto a position separated from said tip end portion of the water column 5. As a result of the above, said water column 5 is steadily formed on the surface of the liquid 1, and the liquid 1 is continuously nebulized by the pieZo-electric transducer 4. FIG. 5 is an experimental result showing a change in the amount of the nebulized water when the inclination angle 6 of the vibration surface of the piezo-electric transducer 4 with respect to the surface of the water 1 was changed from 0 to more than while maintaining the exciting or driving power of the piezo-electric transducer 4 at a constant value of W. As is clear from FIG. 5, the nebulizing capacity can be enhanced about 23% when the inclination angle 9 is in a range of from 2 to 22. Further, it was found that when the inclination angle 0 was increased more than 22, the reflection of the ultrasonic wave on the liquid or water surface was increased, while the nebulizing capacity was decreased.

As shown in FIG. 2, since the transistors 11 are directly attached to the surface of the chamber base 18 of the nebulizing chamber 2, the transistors 11 are effectively cooled by the water 1 by way of the chamber base 18.

Generally, the temperature of the water 1 rises to approximately C, however, if cool water is injected into the nebulizing chamber 2 during the generation of fog, the cooling effect on the transistors 11 is further raised.

Further, as shown in FIG. 1, in the ultrasonic nebulizer, the liquid tank 21 is provided in such a manner that its surface level becomes equal to the surface level of the water 1 in the nebulizing chamber 2 so that the nebulization of the liquid 1 can be continuously carried out for many hours. Generally, the relationship between the liquid surface level L (cm), that is, the distance between the ultrasonic wave transducer 4 and the surface of the liquid 1, and the nebulized amount Q (cc/hr) of the liquid 1 is shown in FIG. 6. As is clear from FIG. 6, when the liquid surface level L is in a range from 0 to 8.0 cm, a sufficient nebulizing capacity can be obtained, and the more preferable conditions are when the liquid surface level L is 5 7.5 cm, the frequency is 1.3 MHz and the diameter of the piezoelectric transducer is 25 d).

In the above-mentioned embodiment, the bottom portion of the exhausting duct 9 for air and fog 7 is disposed adjacent to the upper surface of the liquid 1 so as to insert the fog generating front portion of the water column 5 into the exhaust duct 9. The air supplied from the air supply inlet 8 flows through a passage formed between the inside wall of the nebulizing chamber 2 and the outside wall of the exhaust cylinder 9 and is guided adjacent to the surface of the liquid 1 in the nebulizing chamber 2. The air then flows upwardly into the exhaust cylinder 9, while the air around the fog generating front portion of the water column 5 flows in the same direction as the water column. Thus, the air, together with fog 7, are expelled through the exhaust cylinder 9 to the exterior of its nebulizer. As a result, the generation of fog 7 from the front portion of the water column 5 is not restricted by the pressure of the air and, also, the air flow in the above-mentioned passage formed between the inside wall of the nebulizing chamber 2 and the outside wall of the exhaust cylinder 9 is not disturbed. Consequently, the amount of water drops caused by the adherence of the fog 7 to the inside wall of the exhaust cylinder 9 decreases, so that the fog transmitting efficiency is enhanced. Further, under a condition of absence of air flow, since the generated fog 7 is floating around the water column 5, the water column 5 is gradually surrounded by the floating fog 7 and, therefore, it is difficult to generate a fog 7 of minute liquid particles, but a fog 7 of large liquid particles is likely to be produced. However, by flowing the air as mentioned before, a fog 7 of minute liquid particles of a constant small size is easily produced and this produced fog 7 is effectively expelled. Also, since the direction of the air flow and the formation direction of the water column is the same, even if the velocity of the air flow is increased to some extent, the top portion of the water column 5 is not scattered.

An effect of the nebulizer according to the present invention will be clearly understood from the following experimental result. This experiment was carried out at normal temperature and normal pressure, with a constant ultrasonic wave frequency and a constant ultrasonic wave intensity, and a constant amount of air was supplied from the air supply inlet 8. In this experiment, the measured amount Q (cc/hr) of fog 7 extruded from the exhaust duct or cylinder 9 was l,400 cc/hr, while that of the conventional nebulizer is 600 650 cc/hr.

SECOND EMBODIMENT ACCORDING TO THE PRESENT INVENTION In an ultrasonic wave nebulizer constructed as shown in FIG. 1, an oscillatory frequency f (Hz) having a wave length of k (mm) transmitted through an optional medium at a velocity of V (m/s) is expressed by the equation:

A suitable frequency f for nebulizing the liquid is preferably in a range from 0.8 to 2.0 MHz, and when water is utilized as a medium, the wave length A becomes approximately O.75 1.90 mm. In such a range of the wave length A, to transmit the oscillation of the oscillator 4 through the medium with a high efficiency, a conical horn 22 is provided between the bottom of the nebulizing chamber 2 and the top of the transducer 4 as shown in FIG. 7. It is possible to obtain a sharp directivity by suitably selecting the angle of inclination of the conical horn 22. The relationship between an input power P (W) and a nebulized amount Q (cc/hr) of the liquid in this second embodiment is graphically shown in FIG. 8. When the horn 22 is not provided, the curve is as shown by a broken line in FIG. 8. That is, according to the nebulizer of the present invention, provided with the horn 22, the nebulizing efflciency can be increased or improved by approximately 10 15%.

SEVERAL MODIFIED EMBODIMENTS ACCORDING TO THE PRESENT INVENTION In the above-mentioned ultrasonic nebulizer of the first embodiment shown in FIG. 1, the liquid tank 21 is provided in such a manner that its surface level becomes equal to that of the nebulizing chamber 2 so as to maintain the liquid surface level L at a constant value with respect to the ultrasonic transducer 4. Next, other modified embodiment for maintaining the liquid surface level L at a constant value will be explained.

FIG. 9 is a first modified embodiment for maintaining the surface level L of the liquid 1 contained in the nebulizing chamber 2 at a constant value. When the transducer 4, mounted on the bottom portion of the nebulizing chamber 2, is excited by an electric circuit, the liquid 1 contained in the nebulizing chamber 2 is nebulized and then expelled through the exhaust duct 9 to the exterior by the air flow produced by means of the fan 14. Consequently, the amount of the liquid 1 contained in the nebulizing chamber 2 decreases. However, the liquid contained in a liquid tank 27 is pushed upward by means of, for example, a propeller pump 23 connected to the fan 14, and then the liquid corresponding to the above-mentioned decreased amount is supplied from a water supply inlet 24 into said nebulizing chamber 2. In this case, the amount of the so supplied liquid is somewhat in excess of the amount of the nebulized and exhausted liquid, and the extra amount of the supplied liquid is returned to the liquid tank 27 from a vertical over-flow pipe 26 via an overflow portion 25. Thus, the surface level L of the water 1 contained in the nebulizing chamber 2 can be maintained at a constant value by the liquid supply means.

FIG. 10 is a second modified embodiment for maintaining the liquid surface level L at a constant value. A nebulizer shown in FIG. 10 comprises the nebulizing chamber 2 and the transducer 4 mounted on the bottom portion of the nebulizing chamber 2. Water is fed into the nebulizing chamber 2 via a suitable water supply inlet 24. Further, there is provided a pair of electrodes 28, 29 in the nebulizing chamber 2. The electrode 28 is situated at a position where the surface level L of the water 1 in the nebulizing chamber 2 can be maintained at any desired position. The other electrode 29 is disposed at a lower critical position where serious trouble, for example, damage to the nebulizing chamber 2 is liable to be produced by some cause when liquid surface level L is lowered beyond the abovementioned lower position.

The pair of electrodes 28 and 29 are connected to an electric power source or circuit 30 via respective condensers C and C and the nebulizer. An AC voltage suitable for operating the electric circuit of FIG. 10 is impressed between the pair of nebulizer and the electrodes 28 and 29. Further, first and

second neon lamps

31 and 32 are provided between the electrodes 28, 29 and the nebulizer, respectively. A bridge 33 and a smoothing condenser C respectively contained in the power circuit 30 are used for supplying DC currents to a pair of first and second

photoelectric circuits

34 and 35.

When the surface level L of the liquid 1 in the nebu lizing chamber 2 drops below the lower end of the electrode 28, the electrode 28 is exposed to the air. As a result, the potential difference between the exposed electrode 28 and the nebulizer increases, so that the first neon lamp 31 is lighted. Similarly, when the surface level L drops below the bottom end of the electrode 29, the second neon lamp 32 is also lighted.

Said first and second

photoelectric circuits

34 and 35 are actuated by receiving light radiated from the first and

second neon lamps

31 and 32, respectively. These first and second

photoelectric circuits

34 and 35 are respectively constructed as shown in FIG. 11. That is, each

photoelectric circuit

34 or 35 has a photoelectric element 36 (for example, cadmium sulfide cds) placed at a position where the light radiated from the each

neon lamp

31 or 32 can be received. When the photoelectric element 36 receives luminous flux beyond a predetermined value, a voltage supplied to a base of a transistor Q via a resistor R is decreased, so that the transistor Q, is turned off. As a result of this, the potential of a collector of the transistor Q rises in accordance with the time constant of a resistor R and a condenser C and a transistor O is turned on. Further, a zener diode ZD inserted between the collector of the transistor Q and a base of the transistor Q serves to maintain the impedance of the transistor Q viewed from the transistor Q side, at a high value during the time the transistor O is off, and secure the switching operation of the transistor Q When a transistor O is turned on, a current flows in an exciting coil of a relay 37, so that the relay 37 is brought into an operating condition. The relay 37 controls a switch of a supply mechanism for supplying water into the nebulizing chamber 2 via the water supply inlet 24 shown in FIG. 9. When the liquid surface level L in the nebulizing chamber 2 rises to the position of the electrode 28, the first neon lamp 31 is extinguished due to the potential drop of the electrode 28. As a result of this, the transistor 0., of the photoelectric circuit 34 is turned on and energized and the transistor O is turned off and deenergized, so that the relay 37 returns to its non-operational condition and the supply of water into the nebulizing chamber 2 is stopped. By repeating the above-mentioned operation, the liquid surface level L can always be maintained within a predetermined range.

Further, when the liquid surface level L is lowered by some accident beyond the bottom end of the electrode 29, the second neon lamp 32 lights and this is detected by the second photoelectric circuit 35, so that the relay 37 is actuated and the operation of the nebulizer is stopped.

What is claimed is:

1. An ultrasonic wave nebulizer comprising a nebulizing chamber filled with a predetermined amount of liquid, a chamber base formed at the bottom portion of said nebulizing chamber, a piezo-electric transducer inserted into and secured to said chamber base so that the vibration surface of said piezo-electric transducer has an inclination of 2 22 with respect to the surface of said liquid in said nebulizing chamber, an electric circuit means for electrically oscillating said transducer with a natural frequency thereof, an exhaust duct for expelling fog composed of minute liquid particles and formed above said vibration surface of said transducer to the exterior, and an air supply inlet for supplying an air flow to said fog thereby forcibly expelling said fog through said exhaust cylinder.

2. A nebulizer as claimed in claim 1, further comprising a conical horn having a predetermined reflection surface provided on the upper portion of said transducer contacting said liquid to be nebulized.

3. A nebulizer as claimed in claim 1, further comprising transistors for ultrasonically driving said transducer directly attached to said chamber base and cooled by said water used for producing said fogs via said charnber base.

4. A nebulizer as claimed in claim 1, further comprising a means for maintaining the surface level of said liquid in said nebulizing chamber at a constant value.

5. A nebulizer as claimed in claim 4, further comprising a liquid tank, and means for maintaining the liquid surface level of said liquid tank equal to the surface level of said liquid in said nebulizing chamber.

6. A nebulizer as claimed in claim 5, wherein said liquid tank is disposed in such a manner that said liquid surface level of said liquid tank is lower than said surface level of said liquid in said nebulizing chamber, said liquid is supplied from said liquid tank into said nebulizing chamber by means of a pump and any excess amount of said supplied liquid is returned back into said liquid tank via an overflow portion connected to said nebulizing chamber.

7. A nebulizer as claimed in claim 4, further comprising a pair of first and second electrodes respectively contained in said nebulizing chamber and situated with a vertical space within a range of variations of said surface level of said liquid in said chamber, said electrodes and the bottom portion of said chamber are respectively connected to an AC source and an AC voltage is applied therebetween, a pair of first and'second lamps respectively operate after detecting changes in potentials caused by variations of said liquid surface level beyond said positions of said electrodes, and a pair of first and second photoelectric circuits being actuated by the lights radiated from said lamps, respectively, so that said liquid surface level in said nebulizing chamber can be detected.

8. A nebulizer as claimed in claim 1, wherein said air supply inlet points in the direction of said rising column of fog said fog assuming the shape of a water column formed on said liquid surface in said nebulizing chamber, whereby said fog is sent to the exterior along the direction of said air flow.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,901,443 Dated August 26,1975

Inventcr s) Sadao Mitsui, et a] It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Abstract, line 9: delete "a pair of".

Column 8, line 55: replace "said" by -a-.

line 56: insert a comma after "fog".

Signed and Scaled this eighteenth D2) of May 1976 [SEAL] A nest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissinm'r nj'lalems and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,901,443 Dated ugust 26, 1975 Inventor(g) Sadao Mitsui, et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 42 and 43: Please delete "is formed the forming direction of the spouting water".

Signed and Scaled this ninth Day of March 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oflarems and Trademarks

Claims

1. An ultrasonic wave nebulizer comprising a nebulizing chamber filled with a predetermined amount of liquid, a chamber base formed at the bottom portion of said nebulizing chamber, a piezoelectric transducer inserted into and secured to said chamber base so that the vibration surface of said piezo-electric transducer has an inclination of 2* - 22* with respect to the surface of said liquid in said nebulizing chamber, an electric circuit means for electrically oscillating said transducer with a natural frequency thereof, an exhaust duct for expelling fog composed of minute liquid particles and formed above said vibration surface of said transducer to the exterior, and an air supply inlet for supplying an air flow to said fog thereby forcibly expelling said fog through said exhaust cylinder.

3. A nebulizer as claimed in claim 1, further comprising transistors for ultrasonically driving said transducer directly attached to said chamber base and cooled by said water used for producing said fogs via said chamber base.

7. A nebulizer as claimed in claim 4, further comprising a pair of first and second electrodes respectively contained in said nebulizing chamber and situated with a vertical space within a range of variations of said surface level of said liquid in said chamber, said electrodes and the bottom portion of said chamber are respectively connected to an AC source and an AC voltage is applied therebetween, a pair of first and second lamps respectively operate after detecting changes in potentials caused by variations of said liquid surface level beyond said positions of said electrodes, and a pair of first and second photoelectric circuits being actuated by the lights radiated from said lamps, respectively, so that said liquid surface level in said nebulizing chamber can be detected.