KR100326679B1 - Liquid spraying apparatus and method - Google Patents

Abstract

A method of and apparatus for atomising a liquid are disclosed, in which a liquid is caused to pass through tapered perforations (50) in a vibrating membrane (5) in the direction from that side of the membrane (5) at which the perforations (50) have a smaller cross-sectional area to that side of the membrane (5) at which the perforations (50) have a larger cross-sectional area.

Description

Liquid Spray Apparatus and Method

The present invention relates to an apparatus and method for producing sprays of liquids or emulsions or suspensions (hereinafter referred to as 'liquids') using actuators.

It is known to produce a fine droplet spray by the reaction of the air with high frequency mechanical vibration of the liquid on its surface. Possible related prior arts include EP-A-0 432 992, GB-A-2 263 076, EP-A-0 516 565, US-A-3 738 574, EP-A-0 480 615, US-A- 4 533 082 and US-A-4 605 167.

In some cases (e.g. US-A-3 738 574), the liquid is employed as a thin film formed on a plate that is excited when bending the vibration by transmitting supersonic vibrations from the remote piezoelectric transducer through the solid bond medium structure. do.

Also, in some cases (eg US-A-4 533 082), mechanical vibrations are the speed of sound or supersonic vibrations through a liquid toward a perforated film or plate (hereinafter referred to as a film) that holds liquid. Propagated as a wave. The action of the oscillating wave in this liquid is to cause the liquid to be ejected as droplets through the pores of the coating. In these cases, there is an advantage in that the size of the pores from the rear surface (the surface opposite to the surface from which the liquid droplets emerge) to the front surface (the surface from which the liquid droplets emerge) is reduced.

In other cases in which the above two cases are combined (eg EP-A-0 516 565), mechanical vibrations pass through a thin layer of liquid towards the perforated coating holding the liquid. However, this EP-A-0 516 565 does not provide any advantages or disadvantages for the particular geometric shape of the holes.

In other cases (eg GB-A-2 263 076, US-A-4 605 167 and EP-A-0 432 992), the mechanical vibration source is mechanically bonded to the perforated coating holding the liquid. . The action of this vibration is to cause the liquid to be ejected as drops through the pores of the coating. In these cases as well, there is an advantage that the size of the hole toward the front surface from which the droplets emerge from the rear surface of the coating is reduced.

The above devices can be classified into two types.

That is, the first general type of spray apparatus, as disclosed, for example, in US-A-3 738 574 and EP-A-0 516 565, transmits vibrations through the liquid to the surface of the liquid from which the spray is produced. There is no disclosure of geometrical features of the surface that affects. They do not have perforated coatings that hold liquid by vibration (US-A-3 738 574), or they have perforated coatings but these holes do not affect droplet size (EP-A-0 516 565, eg, 6 columns 21 rows).

In addition, the second general type of spray apparatus, as disclosed, for example, in US-A-4 605 167, US-A-4 533 082, EP-A-0 432 992 and GB-A-2 263 076, produces droplets. In this case, a perforated film bounding or confining the liquid surface is provided, but the film hole does not affect the drop size. In these cases, the inventors have found that a substantially circular fluid spray emerges from a small opening opened in the front of the coating, and this spraying vibrates toward or away from the coating once per vibration cycle. When the excitation is strong enough, the termination of the injection stops forming free droplets. This state is shown in FIG. In both cases, the diameter of the droplet is typically in the range of 1.5 to 2 times the diameter of the small opening that opens in front of the coating. This relationship is well known in ink jet printing and has been found in many studies of instability of liquid jet. The advantages of spray generation with holes of decreasing size towards the front face are common to both of these devices and are also known from ink jetting techniques. See, eg, US-A-3 368 212.

The device of the first type is quite inefficient for the use of electrical input energy into its (piezoelectric) vibrating actuator. For example, a real device of the type disclosed in US-A-3 73S 574 can spray 2.5 microliters of water with one joule of input energy. Improvements in EP-A-0 516 565 require about 10 microliters to be sprayed by one joule, but limit the capillary action, which requires a liquid film to be carefully separated from the actuator, and its structure is extremely Complex. Moreover, it does not provide the apparatus which a film hole has a practical influence on droplet size. Moreover, in the supply of suspension-type drugs and other applications, the limitations of EP-A-0 516 565 for capillary transfer and the ability of the holes to limit or affect drop size may be disadvantageous. It is generally desirable to choose freely from the wide variety of liquid transfer methods to achieve the most suitable method for that application. For example, in spraying a medicament, it is desirable to provide a metered dose of liquid to the spray to avoid remaining of the residual chemical on the spray, which may promote contamination of the subsequent dose supply. In the case of other larger suspensions, such as antiperspirant suspensions, limiting the range of the capillary gap can result in impediment of capillary transfer. This helps the drop size to determine or at least affect the physical characteristics of the device so as to aid in the repeatability of the drop size by maintaining the manufacturing quality of the device.

In general, the device of the second type having a hole that narrows in the direction in which the droplet is ejected has a larger proportion of the droplet size than the outlet diameter of the hole. This makes it difficult for such devices to spray the suspension into droplets without the size of the solid particles becoming significantly smaller than the desired droplet diameter. Secondly, the device of the second type is also not often employed for the production of sprays with very small droplet sizes. For example, it is desirable to produce a spray of the suspension or heart disease liquid in a shape suitable for inhalation by the patient. Typically, in the supply of pulmonary arteries (vein) to asthma medicine, it is desirable to supply the medicine by targeting a spray having an average droplet size in the range of 6 μm to an optimal region in the pulmonary artery (vein) canal. According to this second aspect of the apparatus, this requires a hole having an outlet diameter in the range of 3 µm to 4 µm. Such small pore size coatings are difficult to manufacture, are expensive, and cannot have pore size, droplet size, and good repeatability of such targeting. Moreover, the formulation of such suspension-shaped drug can most easily be produced with an average solids size of around 2 μm. Such small holes and such solid particle sizes can cause disturbing or poor feeding.

Third, even if the droplet size is large, it is possible to block the flow of the solids carried in the suspension into the narrowing holes, especially when the solid size is comparable to the size of the channel. As an example, a hole with a relatively large diameter at the back of the coating allows particles that are too large to pass through a hole with a relatively small diameter at the front. As a second example, by narrowing the hole, generally two or more solid particles are in contact with each other or with the sidewalls of the hole. At this time, this makes the forward motion unable to be measured, causing blocking.

It is an object of the present invention to provide a spray apparatus which is simple in construction and inexpensive, and which can be operated in a wide range of liquids, suspensions and liquid conveying means.

According to one embodiment of the present invention, there is provided a perforated coating, an actuator for vibrating the coating, and means for supplying liquid to the surface of the coating, wherein the opening of the coating is spaced apart from the surface from which the droplet comes out. A droplet spray apparatus is provided, characterized in that the cross section of the film surface has an inverse taper shape larger than that of the opposite surface of the film. In this specification, what is called a film shall contain a plate.

The actuator is a piezoelectric actuator employed to operate in a bending mode. The thickness of the actuator is substantially smaller than at least one other dimension.

In addition, when the pressure which is directly or indirectly affected by the atmospheric gas on the droplet ejection surface of the film is equal to or exceeds the pressure of the liquid in contact with the film layer on the opposite surface, when gas passes through the hole of the film into the liquid. Means for generating a pressure difference are provided so as not to be substantially greater than the pressure of. The pressure influenced by the atmosphere gas is indirectly affected when it acts as a liquid film formed on the surface of the film. In order to create this pressure difference, the influence of the action of the device for releasing the droplet from the liquid supply means or the closed reservoir or any other means may be used.

The apparatus also includes pressure bias means for applying a lower pressure to the liquid against the passage of the liquid through the aperture.

The holes in the coating surface which are separated from the surface from which the droplets come out are not in contact.

Means for supplying a liquid to the surface of the film is a capillary feed mechanism or bubble generator feed mechanism.

This apparatus may include ordinary tapered and reverse tapered holes. It is preferable that a normal tapered hole is disposed on the outer circumference of the reverse tapered hole. Means for supplying a liquid to the surface of the film may be employed to supply the liquid to the film surface away from the surface from which the droplets emerge.

According to another embodiment of the present invention, liquid is passed through the tapered holes by vibrating the film from the side of the film in the hole with the smaller cross-sectional area to the side of the film in the hole with the larger cross-sectional area. It provides a liquid spray method, characterized in that.

The inventors believe that the device according to the invention operates by exciting capillary waves in the liquid to be sprayed. The capillary wave spray will be described later.

Hereinafter, in the specification and claims, a hole having a larger area at the rear side than at the front surface where a drop occurs will be referred to as a conventional tapered hole, and a hole having a smaller area at the rear side than at the front side will be referred to as an inverse tapered hole. do. Correspondingly, it is defined as an inverse tapered shape and a normal tapered film.

An electronic drive circuit for operating an actuator and an actuator mounted thereon are, for example, the prior art disclosed in WO-A-93 10910, EP-A-0 432 992, US-A-4 533 082, US-A-4 605 167. Either the shape or any other suitable shape may be taken. In general, it is desirable to use actuators and drive electronics that interact to create such resonance excitations.

The first advantage of this configuration is that the ratio of the average droplet size to the average suspension particle size can be reduced compared to the prior art apparatus, and a simple and inexpensive apparatus can be used to generate the droplet spray of the suspension. .

The second advantage of this configuration is that by using a coating which can reduce the possibility of hole obstruction and can be easily manufactured, it is possible to produce a small droplet diameter liquid and suspension spray suitable for lung inhalation.

A third advantage of this configuration is that it can produce a relatively slow liquid spray suitable for uniform coating of the surface.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as an example.

1 is a schematic cross-sectional view of a device according to the prior art, which sequentially shows the subsequent steps of ejecting droplets from a hole whose area at the front (surface of the coating) is smaller than the area at the rear of the coating;

2 is a cross-sectional view of the proposed droplet dispensing apparatus,

3 is a cross-sectional view illustrating the proposed shape of the perforated film in the apparatus of FIG.

4 is a plan view and a cross-sectional view of the spray head according to the proposed embodiment,

5 is a cross-sectional view schematically showing an alternative hydraulic control device that can be used as a spray head for forming a distribution device for a room according to the invention,

6 is a view showing a room generating apparatus according to the present invention,

7 is a view schematically showing an apparatus for distributing a room according to a second embodiment of the present invention;

8 is a cross-sectional view illustrating an alternative coating structure in the apparatus of FIG. 7;

FIG. 9 is a view for schematically explaining droplet ejection from normal tapered holes and inverse tapered holes.

1 shows an arrow (marked in a direction substantially perpendicular to the plane of the film; 58) with a conventional tapered aperture membrane (membrane) 61 and the liquid body 2 in contact with the rear face thereof. Vibration bus is shown by. 1 (a) to 1 (c) are for continuously forming and releasing free droplets 64 by substantially circulating and spraying the fluid 62 from the tapered holes during one cycle of vibration motion. The occurrence of liquid meniscus 63 is shown in order.

2 shows an enclosure 3 which transfers the liquid 2 directly to the rear surface 52 of the perforated coating 5, vibrating means or actuators 7 formed by annular electroacoustic disks and substrates, and the like. And a droplet dispensing device 1 which can be operated by the electronic circuit 8. The electronic circuit 8 obtains power from the power supply 9 and vibrates the perforated film 5 substantially perpendicular to the plane of the film, thereby separating it from the front surface 51 of the perforated film. Produces droplets of liquid coming out. In the following, the combination of the perforated coating 5 and the actuator 7 will be referred to as an aerosol head 40.

The aerosol head 40 is captured and held so that the vibration motion thereof is not excessively limited by, for example, a groove-shaped annular laminate formed of a soft silicone rubber (not shown). The liquid storage and supply to the back side are made, for example, by the enclosure 3 shown in FIG. 2.

Thirty-one (a) details the first example of a perforated coating (5) operable to vibrate substantially in the direction of arrow (58) and suitable for use in droplet dispensing apparatus (1) for producing a fine aerosol spray. It is sectional drawing shown. In this example, the coating 5 consists of a circular layer of polymer with a plurality of tapered conical holes 50. Each hole 50 is provided with an opening 53 of the exit port surface and an opening 54 of the rear entrance surface laid out in a square lattice. These holes may be introduced into the polymer film, for example, by laser drilling with an excimer laser.

3 (b) shows the detail of the second example of the perforated coating 205 according to the present invention which is operable to vibrate substantially in the direction of the arrow 58 and is suitable for use in the drop dispensing apparatus 1. It is a cross section. The coating is formed as a circular disk of 8 mm in diameter from electroformed nickel, for example manufactured by Stork Veco of Irvik, The Netherlands. The thickness is 70 microns, and is formed with a plurality of holes represented by 2050 of the front surface 2051 of 120 microns in diameter denoted by "a" and the rear surface 2052 of 30 microns in diameter denoted by "b". These holes are laid out in a regular lattice with a pitch of 170 mu m. The profiles of these holes fluctuate smoothly between the front and rear diameters through a thick coating having a substantially flat ground area (represented by "c") of the smallest dimension 50 μm in the front surface 2051.

In addition, a film having a geometrical shape similar to that described with reference to FIGS. 3A and 3B made of alternative materials such as glass or silicon may be used.

4 shows a plan view and a cross section along one suitable shape of the aerosol head 40. The aerosol head 40 has an electroacoustic disk 70 with a nickel-iron alloy annulus 71 known as Invar, a piezoelectric ceramic annulus 72 and a circular hole coupled thereto. It consists of a perforated film 5. This hole-perforated film is as described with reference to FIG. 3 (b). The nickel-iron hospitality has an outer diameter of 20 mm and a thickness of 0.2 mm and consists of a hole 73 sharing a center. Piezoelectric ceramics are of type P51 from Hoechst CeramTec, Lauf, Germany, having an outer diameter of 16 mm, an inner diameter of 10 mm and a thickness of 0.25 mm. The upper surface 74 of the ceramic is provided with two electrodes, a driving electrode 75 and a selection sensing electrode 76. This sensing electrode 76 is made of a metal of width 1.5mm which in this example substantially extends easily from the inner diameter to the outer diameter. The drive electrode 75 extends over the other surface and is electrically insulated from the sensing electrode by a 0.5 mm gap. Electrical contact is made by the solder connection by the fine wire which is not shown in figure.

In operation, the drive electrode 75 is driven by a sinusoidal or sawtooth signal at a frequency in the range of 100 to 300 kHz with an amplitude of approximately 30 V by means of the electronic circuit 8, so that the front surface of the perforated film Generate drop spray coming off 51. Here, the average size of the drops is typically in the region of 10 microns. The actuator head may normally have vibration resonance at all frequencies that effectively produce drops. At this resonance the signal from the sensing electrode 76 has a local maximum at that frequency. The drive circuit may be an open-loop that does not use the feedback signal from the electrode 76 or may be a closed-loop that uses the feedback. In each case, the electronic drive circuit can cause the actuator head and the drive circuit to cooperate with each other to maintain the resonance vibration of the actuator head in response to a change in the electrical behavior of the actuator head upon resonance. The shorted loop can ensure that the piezo actuator maintains the resonant vibration by maintaining a phase angle between the predetermined drive and the feedback or sensing electrode to give the maximum supply.

Figure 5 (a) is a cross-sectional view of a fluid transfer mechanism having a conduit composed of open-celled capillary foam rubber. Such capillary feed mechanism may be used to provide hydraulic control. (The advantages of the hydraulic pressure control will be described later.) By the action of the vent hole 83 and the capillary tube 81, the liquid is accommodated in the capillary tube 81 at a pressure below ambient air pressure. The pore size of the capillary foam rubber can be controlled to control this pressure value. The surrounding capillary 81 is a solid outer housing 82. This arrangement is particularly useful for supplying a spray of dangerous eg addictive liquids while reducing the risk of liquid loss. The capillary action of the material 81 has the effect of accommodating the liquid to reduce or minimize the escape of the liquid even if damage to the outer housing 82 occurs. This advantage can be applied to retain the drug, the liquid of liquid or flammable liquid.

5B is a cross-sectional view showing a so-called bubble generating device known from the recording machine technology that may be used to provide hydraulic pressure control. The operation of dispensing the liquid from the hole provided in the coating generates pressure in the storage container 90 so that the pressure of the liquid 91 in contact with the coating decreases below atmospheric pressure. When this pressure is low enough to suck air through the holes in the coating or through the auxiliary tool 92 compared to the liquid meniscus pressure, the pressure of the storage vessel may rise sufficiently compared with the liquid meniscus to withstand the pressure difference. Until it sucks air as bubbles. In this way, the hydraulic pressure is adjusted to a value below atmospheric pressure. (The opening 92 is generally chosen small enough so that liquid does not easily leak out of the enclosure.) It can be seen that both of these pressure control methods can increase the spray supply from the spray head 40 within the above-mentioned pressure ranges. It will be readily understood that other methods may be applied within the scope of the present invention.

Hereinafter, the operation method of the present invention will be described in detail with reference to FIGS. 6 (a) to 6 (g). In addition, the droplet generating mechanism provided by the present invention as well as what is currently recognized by the present inventors will be described in detail. These mechanisms are not sufficiently validated but are understood within the scope of the present invention.

If the pressure difference applied to the liquid is close to zero (i.e., the pressure of the liquid in the spray head is approximately equal to the pressure on the front surface of the perforated film), the liquid 2 is coated as shown in FIG. Is brought into contact with the meniscus 65 attached to the rear surface 52 of the film 5. As shown in the middle portion of FIG. 6 (b), in response to the vibration excitation 58, the coating liquid flows toward the front surface 51 of the coating 5.

Most generally, when the pressure difference is small compared to the pressure required to suck air through the coating hole against the liquid meniscus pressure when the coating does not vibrate, the material and hole of the coating as shown in FIG. The cross-sectional profile of allows the liquid 2 to flow out over the front surface 51 of the coating as a thin film. As shown in FIG. 6 (d), the capillary wave can be excited on the surface of the liquid meniscus 67 by the vibration of the coating 5. This was known to occur when, for example, the polymer material for the coating 5 was used for the aerosol head described above according to FIG. 3 (a). The position of these waves is not limited by the intersection of the side wall of the hole 50 or the front surface 51 bounding the opening 53. If the vibration amplitude of the liquid meniscus 67 is large enough, the droplets are typically emitted with a diameter of about one third of the capillary wavelength (eg, "Rozenberg-Principles of Ultrasonic Technology"). )" Reference). The shape of the hole allows an effective replenishment of the liquid lost as a drop from the meniscus 67. And the shape of the coating allows for effective vibrational excitation.

Rather, the face 51 is not completely filled with holes, but the liquid easily spreads through the area of the face 51 larger than the hole area. This feature balances the flow rate through the aperture 50 in response to the vibration 58 and the speed when the liquid is sprayed as drops from the capillary waves of the meniscus 67. This balance is achieved by a pressure difference (as opposed to flow through the pores due to vibration) which is alternatively or sufficient to form a thin film on the face 51 in combination with the method described above. By this balance, excess liquid can be prevented from flowing over the front surface 51 which can inhibit the formation of the drop spray.

By alternatively selecting a pressure difference against the flow through the hole 50, the bulk liquid does not flow over the front surface 51 of the coating 5, as shown in FIG. (5) and the meniscus 66 contacting between the front surface 51 and the rear surface 52 of this film. In this case, as shown in FIG. 6E, the vibration of the film can excite the vibration to each of the liquid meniscus 66. (Typically, this can be compared to the pressure required to inhale air through the encapsulation to the maximum liquid meniscus pressure of the pore when the encapsulation is not vibrating, but requires a pressure differential not greater than that.) Since the dropping arrangement complements the geometrical arrangement of the fluid meniscus, the vibration of the coating and the combination of the liquid are particularly effective in this case. Induction of the liquid meniscus takes the form of capillary waves. The integer of such capillary waves is fixed in the hole. In this way, the geometrical arrangement of the holes is excited with the capillary waves and when these waves are generated effectively they match the geometrical arrangement of the meniscus. Again the drop ejection is observed with the appropriate frequency and amplitude of vibration.

In FIGS. 6 (f) and 6 (g), which show a special case according to FIG. 6 (e), the meniscus of the liquid is formed by the holes 50 and the back surface 52 of the film with holes. The pressure difference is selected so as to be held near the intersection with 6 degrees (f) or the front surface 51 (6 (g)), and a capillary wave is formed in the meniscus through the action of the vibration 58. Again, this allows for effective vibration excitation of the meniscus, and ejects droplets if the amplitude and frequency of vibration 58 are appropriate. It can be seen that the value of the pressure difference between zero and the pressure required to suck air (or other atmospheric gas) through the coating hole against the action of the surface tension of the liquid in contact with the hole acts to improve the efficiency of droplet generation. Can be.

In the cases shown in Figs. 6E, 6F, and 6G, only a single capillary wave (in other words, one capillary wave) is a hole between the openings 53 and 54. Higher frequency excitation may be used for capillary waves of more than one capillary wave which are fixed within the diameter of, and thus so fixed. This can be expressed by requiring the following relationship to be maintained almost at the vibration excitation frequency.

here:

Φ = diameter of the tapered hole at a predetermined point between the front and back of the film,

n = integer,

λc = wavelength of the capillary wave in the liquid.

The relation between the wavelength λc of the capillary wave and the excitation frequency f is given by

Where: σ = fluid surface tension (at frequency f),

ρ = fluid density.

The inventors have found that this relation also holds when the capillary wave is bound by the hole as described above. Therefore, as described above, it is preferable to design and operate the apparatus so as to satisfy the following equation with respect to the tapered hole having a diameter Φ.

The above relation Corresponding to the approximate condition of, it was found that this relation satisfies the operation when the following range is maintained.

In a device having the advantage that a capillary wave can be formed in a tapered hole only for a specific number p, the ratio of the large diameter of the hole (represented by 53) to the small diameter of the hole is 1 to (p + 1). It must be in the range of / p. This is most effective for small integer values of p.

Since the capillary wave droplets have a diameter of approximately one third of the capillary wavelength lambda c, the device according to the invention will produce droplets having a diameter of approximately one third or less of the diameter of the outlet 53. (If the liquid meniscus is held at or near the opening 54 provided in the rear surface 52 of the coating, the device according to the invention has a diameter of approximately one third or less of the diameter of the smaller opening 54). Unlike the prior art device, in this case, the size of the hole affects the size of the drop, so it can be chosen to be useful to produce a drop of the desired diameter. Is particularly useful for producing small droplets, for example in applications such as lung disease feeding.

In the case of using the perforated film described with reference to FIG. 3 (b), the spray head described with reference to FIG. 4 and the bubble generator described with reference to FIG. 5 (b), FIGS. Generation of the room occurs according to the apparatus and method described with reference to FIGS. 6 (f) and 6 (g). When spraying water from such a device, the optimum spraying is initiated at a pressure difference of -30 mbar (against the fluid flowing over the front of the coating), and as the pressure difference increases, the spray flow rate and the pressure difference of -76 mbar are increased. The efficiency is improved. The optimum spray is obtained at the pressure at which the perforated coating acts as a bubble generator. This state is typical. Thus, bubble generators, capillary feed mechanisms, and other means for imparting a pressure differential against flow provide particular advantages to the present invention. The spraying action for this device is obtained according to a sinusoidal excitation of 30V amplitude at frequencies of 115, 137, 204 and 262 kHz and a capillary wavelength in the corresponding calculated range of 51 µm to 30 µm. The latter wavelength corresponds to the minimum opening size of the pores and produces droplets of approximately 10 microns in size. This device is the best embodiment of the present invention known to the inventors in producing droplets on the order of 10 microns.

In these various embodiments, the use of the reverse tapered holes in the present invention can prevent interference when spraying the suspension. Firstly, unlike prior art devices, the holes cannot pass completely through the coating but do not allow solid particles to move by the coating vibration so as not to damage the holes forever. Secondly, two or more solid particles are not organic so as not to contact each other or to contact the side walls of the holes to block the holes. Third, because relatively large holes can be used to produce drops of a given size, it is possible to pass relatively large solid particles of the suspension without obstruction. In addition, the device according to the invention makes it possible to manufacture the film relatively easily in the case of small drops, such as the supply of waste medicines, as required.

There is a significant difference between the droplet emission frequency of the device of the present invention and the prior art device having the same pore size. For example, for a minimum diameter of 15 μm, the prior art apparatus generally operates to eject droplets at a frequency in the range of 40 Hz, while the apparatus of the present invention suitably produces droplet ejections in the range of 400 to 700 Hz. .

Moreover, the difference from the prior art apparatus can be seen from the action of negative liquid bias pressure cited in the long term. In the case of the prior art device, a negative bias pressure was used, in particular, to prevent wetting of the front surface of the film as shown in FIG. However, this bias does not provide the meniscus to be isolated at the new equilibrium position in the hole. Specifically, in the prior art apparatus, as soon as the bias pressure is sufficient to separate the meniscus's edge at the intersection of the hole and the front surface of the coating, the meniscus is pulled away from the hole completely to prevent the spraying action. . In contrast, in the present invention, the fluid meniscus is tapered in the case where the pressure difference is selected to allow wetting of the front surface of the coating, or if the pressure difference is sufficient to pull the fluid meniscus upside down in the tapered hole. It is possible to reach a new equilibrium position within, thereby maintaining a stable droplet release. The latter makes it possible to set a combination of bias pressure and frequency so that the constant of the capillary wavelength is fixed in the hole to eject the droplet effectively.

7 shows a second drop dispensing apparatus with a replacement liquid transfer mechanism. The liquid transfer mechanism is provided with an annular plate 102 which acts together with the transfer tube 103 and the surface 1051 of the coating 105 to provide a capillary liquid channel to the hole 1060 in the coating 105. . The film 105 is connected to the vibrating means or the actuator 7. The actuator 7 is connected to the sealing support / laminate 108, the electronic circuit 8 and the power supply 9. The conveyance pipe 103 may be mounted corresponding to the sealing support 108 (not shown). The circuit 8 and the power supply 9 may be the same as those shown in the apparatus of the first embodiment, for example. Vibration in the direction of the arrow 58 substantially perpendicular to the plane of the perforated coating 105 produces droplets of liquid 1010 from the front surface 1051 of the coating. Hereinafter, a combination of the perforated coating 105 and the actuator 107 will be referred to as an aerosol head 1040.

8 is a cross-sectional view showing the details of the case where the liquid comes into contact with the perforated coating 105. This film 105 is provided with the conical holes of the normal tapered shape and the reverse tapered shape indicated by 1060 and 1050, respectively. A double reverse tapered hole 1050 is positioned to free the liquid on the front surface of the coating. In addition, although the conventional tapered hole 1060 is located to receive liquid from the front surface of the film, it can be placed around the hole of the reverse tapered shape 1050, for example.

Also in this 2nd drop distribution apparatus, you may use the drop generation mechanism mentioned above about the apparatus of a 1st example. However, the presence of the draft type 1060 allows various liquid transfers to be used for the entire surface of the coating 5. Liquid transfer is performed by the hole type 1060 installed on the front surface of the coating. As one of the liquid supply means, there is a capillary conveying means having an annular plate 102 which acts together with the surface 1051 of the coating 105. In use, the droplet dispensing device of this second example acts to deliver liquid through the hole type 1060 to the back side 1052 of the coating 105, and in contact with the liquid to produce a hole tile on the back side 1052 of the coating. The liquid wetting action of holding 1050 enables droplet dispensing from the front of the hole 1050 in the same manner as the droplet dispensing apparatus of the first example. Other detailed descriptions follow that of the first drop dispensing apparatus described above.

9 shows a second use example of a film provided with ordinary tapered holes and reverse tapered holes. This allows for a combination by a single device of the conventional apparatus of droplet generation as shown in FIGS. 1 and 6. The forward and reverse tapered holes may be approximately the same size or different sizes. Thus, such a device can produce droplets by one instrument at one operating frequency and droplets by another instrument at another frequency. Likewise, such a device can produce a relatively large sized droplet 1011 from a conventional tapered aperture 1060 by one mechanism and a relatively small size from the reverse tapered aperture 1050 by another mechanism. Drops 1010 may be generated. Moreover, it is possible to produce a relatively high speed spray by one mechanism and a relatively low speed spray by another mechanism. It will be readily understood that other combinations of droplet size, operating frequency and droplet velocity are possible. Finally, for example, when designing a bubble generator enclosure as described above, a drop of a conventional tapered hole 1060 is created in order to create a negative pressure bias for improved droplet generation from the reverse tapered region of the coating. Instruments can be used.

The optimum conditions and details of the spray head of the device, now known to the inventors, are shown in FIGS. 3 (b), 4, 5 (b) and 6 (e) to 6 (g). Explained with reference.

Although not shown in the figures, the device according to the invention may be operated to spray downwards, sideways or upwards.

Claims (25)

Perforated film, An actuator for vibrating the film, Means for supplying a liquid to the surface of the film, The hole of the film has an inverse taper shape in which the cross-sectional area of the film surface away from the surface of the liquid droplet is larger than the cross-sectional area of the opposite surface of the film, and replaces the liquid flow on the surface where the droplet spray comes out. Droplet spray device, characterized in that used. The droplet spray apparatus according to claim 1, further comprising a pressure bias means for applying a reduced pressure to the liquid in contact with the film surface opposite to the surface away from the surface where the droplet emerges. 3. A droplet spray apparatus according to claim 2, wherein the reduced pressure is in a range up to a pressure at which air is drawn out through the hole of the coating in contact with the fluid at zero. The droplet spray apparatus according to any one of claims 1 to 3, wherein the hole in the coating surface separated from the surface from which the droplet comes out is not in contact. The droplet spray apparatus of claim 1, wherein the actuator is a piezoelectric actuator. 6. A droplet spray apparatus according to claim 5, wherein said piezoelectric actuator is adapted to operate in a bending mode. The droplet spray apparatus according to claim 1, wherein the means for supplying a liquid to the surface of the film is a capillary feed mechanism. The droplet spray apparatus according to claim 1, wherein the means for supplying a liquid to the surface of the film is a bubble generator conveying mechanism. The droplet spray apparatus according to claim 1, wherein all of the holes have a reverse taper shape. 10. The droplet spray apparatus according to claim 9, wherein the film further includes a normal tapered hole. The liquid droplet spraying device according to claim 10, wherein the ordinary tapered hole is disposed on an outer circumference of the reverse tapered hole. 12. The droplet spray apparatus according to claim 10 or 11, wherein the means for supplying a liquid to the surface of the film is adapted to supply the liquid to the film surface away from the surface from which the droplet emerges. The liquid droplet spraying apparatus according to claim 1, wherein the means for supplying a liquid to the surface of the film is adapted to supply the liquid to the film surface opposite to the surface away from the surface from which the droplet emerges. The droplet spray apparatus according to claim 1, wherein the actuator is provided to vibrate the film so as to satisfy the following relational expression. Where Φ = diameter of the tapered hole at a predetermined point between the front and rear surfaces of the coating, n = any integer, λ c = wavelength of the capillary wave of the liquid, σ = surface tension of the fluid (at frequency f), ρ = fluid density. The liquid droplet spraying apparatus according to claim 1, wherein the actuator is provided to vibrate the coating in a frequency range of 20 Hz to 7 MHz. And vibrating the coating from the side of the coating in the hole having the smaller cross-sectional area toward the side of the coating in the hole having the larger cross-sectional area to allow liquid to pass through the tapered holes. 17. The liquid spray method according to claim 16, wherein a pressure bias is applied to the liquid which obstructs the passage of the liquid passing through the hole. 18. The liquid spray method according to claim 17, wherein the pressure bias is in a range from zero to a pressure for extracting air through the hole of the film in contact with the fluid. 17. The liquid spray method according to claim 16, wherein the actuator is a piezoelectric actuator and is adapted to operate in a bending mode. The liquid spraying method according to any one of claims 16 to 19, wherein the liquid is supplied to the surface of the coating through a capillary feed mechanism. 20. The liquid spraying method according to any one of claims 16 to 19, wherein the liquid is supplied to the surface of the film through a bubble generator transfer mechanism. 17. The liquid spray method according to claim 16, wherein the liquid is supplied to the coating surface away from the surface from which the droplet comes out. 17. The liquid spraying method according to claim 16, wherein the liquid is supplied to the coating surface opposite to the surface separated from the surface from which the droplet comes out. The liquid spray method according to claim 16, wherein the actuator vibrates the coating so as to satisfy the following relational expression. Where Φ = diameter of the tapered hole at a predetermined point between the front and rear surfaces of the coating, n = any integer, λ c = wavelength of the capillary wave of the liquid, σ = surface tension of the fluid (at frequency f), ρ = fluid density. 17. The liquid spray method according to claim 16, wherein the film is vibrated at a frequency in the range of 20 Hz to 7 MHz.