JPS6141632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for electrostatic spraying of liquids. The invention has particular, but not exclusive, application to the application of pharmaceutical compositions to crops and the application of paints, and also to the formation of aerosol dispersoids.

When a liquid leaves the vicinity of a conductive member at a voltage above or below ground potential, it takes on a net charge as it exits into free space resulting from the exchange of charge with the potential source. This technique can be used to atomize the ejected liquid as the net charge in the liquid interferes with the surface tension of the liquid as it exits from the vicinity of the conductive member into free space. The amount of charge in the exiting liquid droplet after atomization is related in part to the electric field strength at the conductive member.

In known devices, particularly used for electrostatic painting, the electric field strength in the conductive member is determined by (i) the edge of the conductive member, which may be, for example, a rotating sharp-edged disk; (paint is extruded adjacently)
(ii) to sharpen the potential of the conductive member in general;
and (iii) the paint target at the ground boundary of the electrostatic field that is grounded and thus exists between the conductive member and the paint target surface is conductive from which the liquid exits. The electric field strength in the parts is maximized by ensuring that they are close enough to maintain high field strength. The conductive member and the target surface define the main boundaries of the electric field.

A distinctive feature of such known devices is that the combination of high voltage and electrically conductive elements with sharp edges causes a disruption of the surrounding air (by a phenomenon known as corona discharge). The effect of this is that not all of the current supplied to the conductive member is used to charge the liquid. Therefore, when a corona discharge occurs, unnecessary current losses result and also greatly increase the current drawn from the high potential source. This is a disadvantage, and one significant disadvantage is that the power required for the high potential source is too high to be easily obtained with portable energy sources such as torch batteries.

Surprisingly, when an electrode member, hereinafter referred to as a conductive surrounding member, is provided in close proximity to the conductive member, a relatively low voltage of about 1 to 20 KV can be used to charge the droplets. It has been found that a sufficiently high electric field strength can be obtained in a conductive member.
Thus, high charge densities of the order of 10 ⁻² coulombs/Kg can be obtained in the liquid, for example. This provides high charge utilization, allowing low power sources such as piezoelectric crystals, torch cells or solar cells to be utilized as charge transfer devices, and liquids to be electrostatically atomized.

Such atomizing action does not require any mechanical means such as air blasts or rotating disks.
The combination of the electric field due to the voltage in the conductive member and the space charge of the atomized liquid itself can direct the droplets to a grounded object and create an aerosol cloud.

The conductive surrounding member can be considered a "pseudo target" since it strongly influences the electric field within the area where the liquid is atomized. However, unlike a real target, it is placed in close proximity to a conductive member, thus intensifying the electric field. Surprisingly, it has been found that the electrically conductive enclosure member can be easily positioned such that it does not itself become a target for spraying.

The reasons for this are not fully understood, but given that the physical properties of the liquid (e.g. resistivity, viscosity) and flow velocity seem to form (electrostatically) bands of about 1 cm or more according to observations. , it is observed that the atomizing action takes place in that part of the electric field where the resultant of the inertial and gravitational fields and the electrostatic field is directed away from the electrically conductive surrounding member.

It has been discovered that an electrically conductive envelope can be placed downstream of the tip of the spray strip to cause the spray to impinge on the electrically conductive envelope. In this case, with a relatively small amount of the impinging liquid, assuming that the surface of the conductive surrounding member is sufficiently conductive and grounded, the impinging particles will release their charge and reverse their charge due to the induced action in the electric field. It is recognized that it carries an electric charge. This causes these impinging particles to become atomized again and not remain in the electrically conductive envelope.

According to the invention, a liquid is supplied to a conductive or semi-conductive member forming part of a spray orifice which is electrically charged to a first potential, and which is adjacent to said spray orifice and which prevents atomization from the spray orifice. applying another potential to at least one electrode positioned away from the substantial trajectory of the droplet, and controlling at least one of the first and the other potential to increase the distance from the spray orifice to the object to be sprayed. A method for electrostatic spraying of liquids is provided which is characterized by obtaining desired spray characteristics regardless of distance.

Current losses shall mean applied high voltage current drains other than those used to charge the liquid.

Preferably both the conductive enclosure member and the target are at ground potential. However, the atomizing field can also be generated by changing the conductive surrounding member and grounding the surface.

The term "conductive member" refers to a material having a resistivity on the order of 1 Ωcm or less, and the term "semiconducting member" refers to a material having a resistivity of 1 to about 10 ^-12 Ωcm. The term "insulating material" shall mean a material with a resistivity greater than or equal to 10 ^-12 Ωcm.

The conductive or semi-conductive member that atomizes the liquid can be of various shapes. It is often the end of a spray conduit, preferably a capillary conduit, such as a nozzle opening, through which the liquid is sprayed in operation.

The conductive member also consists of the edges of two concentric tubes that form an annular opening through which the liquid can exit. The edges of these tubes can be serrated or grooved. Alternatively, the conductive member may preferably consist of two edges forming a capillary width slot. This slot may be rectangular or other shaped. The atomizing action can take place from a flat surface of a solid conductor or semiconductor that is supplied with liquid.

The geometry of the electrically conductive surrounding member is generally adapted to correspond to the shape of the electrically conductive or semi-conductive member. If the surface is defined by a nozzle, the electrically conductive surrounding member may be annular in shape surrounding the nozzle.

The conductive surrounding member is generally placed as close as possible to the conductive member without creating a corona discharge between the conductive member and the conductive member. For example, if the potential at the conductive member is 20 KV, the conductive surrounding member is preferably placed approximately 2 cm apart from the conductive member. The electrically conductive surrounding member may be located at, either in front of or behind the electrically conductive member that sprays the liquid.

In a preferred embodiment of the invention, the electrically conductive enclosure has an insulating surface. For example, it may be a thin wire embedded in a body or sheath made of plastic material. This allows the spacing between the conductive surrounding member and the conductive member to be much narrower than would be possible with air gap insulation alone. This increases the electric field strength in the vicinity of the conductive member.

Preferably, the electrically conductive surrounding member is adjustably mounted so that the spatial relationship between it and the electrically conductive member can be easily varied.

It has been found that the position and geometry of the conductive enclosure control the angle of droplet flow exiting into free space. If the conductive envelope is behind the exiting spray, the angle of flow is increased, and if it is in front of the exiting spray, the angle is decreased.

Additionally, the average size of the atomized droplets can generally be controlled by the position of the electrically conductive surrounding member relative to the electrically conductive member. For example, for a given flow rate of liquid, the average droplet size is generally reduced by moving the conductive surrounding member closer to the conductive member.

By adjusting the position of the conductive envelope, droplets of selected dimensions suitable for a particular use can be formed. For example, for maximum target coverage, a large number of small particles (e.g. 20-30μ) is preferred for insecticides, and large droplets that are less likely to be blown away by the wind are required for herbicides. obtain. This selected droplet size can be maintained despite movement of the target relative to the conductive member since the electric field strength generated by the conductive surrounding member is heavier than that produced by the target.

It has also been found that for a given voltage and constant conductive enclosure position, the size of a given liquid droplet is related to the spray volume.

It has been found that the spray of liquid is related to the electrically conductive surrounding member and the electrical potential of the electrically conductive member, the position of the electrically conductive surrounding member, the amount of liquid ejected and the properties of the liquid.

The atomization of the liquid carried out by the method according to the invention does not require any mechanical means such as forced air blasts or rotating disks. However, once the liquid has been atomized and exits the atomizing field, forced air blasting may be used to propel the atomized droplets over a longer distance to the target and thus help penetrate, for example, leaves. .

It is known to use a charged rotating disk as a surface for atomizing liquid. However, the provision of a conductive enclosure allows operation with less current and lower voltage than with the known device alone.

Spray action and spray trajectory are influenced by both inertial forces and field effect electrostatic forces. Surprisingly, it has been found that both these forces combine advantageously to give a fine spray even at potential differences of the order of 10 KV or more. For example, if a 3-inch diameter disk rotating at 1.500 rpm is used as the conductive member, and an air gap is used to insulate between the conductive surrounding member and the conductive member with a potential difference of approximately 20 KV, the rate of 1.0 cc/s An average droplet diameter of around 20-30μ was observed at a flow rate of .

In a certain state, for example, if the amount of liquid ejected is large enough,
A strong space charge can be generated between the spray nozzle and the target due to the presence of a large number of charged particles.
This space charge is large enough to dislodge very fine charged particles exiting the nozzle, imparting a suitable velocity component to them both perpendicular to the nozzle-to-target direction and in the opposite direction. This effect is called backspraying.

In the present invention, it has been devised that a suitably placed deflection electrode at high potential can prevent this backspray.

The deflection electrodes may be made of metal such as steel or aluminum. If the electrically conductive surrounding member is of annular shape, the deflection electrode takes the form of a coaxial ring with a diameter slightly larger than the diameter of the electrically conductive surrounding member;
and may be located slightly behind the conductive surrounding member. The deflection electrode can be fixed in space and mounted on an insulating support so as to maintain an electrical charge.
Discs made of plastic material such as "perspex" can be used for this purpose.

The voltage at the deflection electrode may be (a) tapped from a high voltage source used to charge the conductive surfaces of the spray device, either directly or through a voltage divider of very high resistance to prevent unwanted power dissipation; or (b) it may be set up by a separate high voltage source which may be of a low power rating since the deflection device does not consume power during its operation and is therefore essentially not an active device.

For example, when the voltage of the conductive member is 20KV, the suitable voltage for the deflection electrode is 15-20KV.
Also, as an example, the total resistance of a suitable voltage divider is 10 ¹¹ Ω
That's about it. Such a resistor has a length of 2 cm and a cross-sectional area (of any geometrical shape) of 1 cm ² , with electrodes placed at the ends and a tap electrode suitably set between the ends to obtain the required partial pressure. It can be obtained using an insulating material. Strips of materials such as wood, cardboard and rubber may also be used.

The invention can also be particularly used in multi-row crop spraying and can also be applied to crop and tree spraying by tractor or aircraft mounted sprayers.

Some embodiments implementing the method of the invention will now be described, by way of example only, with reference to the accompanying drawings.

Referring to FIG. 1, an electrostatic sprayer has a hollow tube 1 made of plastic material and providing a rigid support to the rest of the sprayer.
Inside this hollow tube 1, it acts as an electrical energy source.
A layer of 16 1.5 volt batteries 2 is housed. Brandenburg223P (0-
20KV, 200μA) high voltage module 3 is installed, and this high voltage module 3 is connected to battery 2 and on/off.
It is connected to the off switch 4 and constitutes a high potential source. The front end of the hollow tube 1 is provided with an integral internally threaded eye 5 adapted to receive a bottle 6 containing the liquid to be sprayed. The eye 5 carries with its lower part an upper part of a tubular distributor 7 made of an insulating plastic material, the lower end of which carries a disk 8 (FIG. 2) made of the same material. There is. Now, referring more particularly to FIG. 2, from the disk 8 there are eight metal capillaries 9.
protrude, and these capillary tubes 9 constitute a spray nozzle assembly. The capillary tubes 9 are each glued to a bare metal wire 10, which is connected via a high potential cable 11 to the high potential terminal of the module 3.

Around the distributor 7 is provided an inverted honeycomb 12 of insulating plastic material. A metal ring member 13 serving as a conductive surrounding member is supported at the edge of this inverted honeycomb member 12, and this metal ring member 13 is electrically grounded via a ground wire 14. The inverted bevel 12 can be moved up and down relative to the distributor 7, but is sufficiently anchored to the distributor 7 to maintain it in any selected position by frictional engagement.

When assembling the atomizer for use, the bottle 6 containing the liquid to be atomized is screwed onto the eye 5 and the atomizer is inverted into the position shown in FIG. By inverting the atomizer into the position shown in FIG. 1, liquid enters the distributor 7 and drips out of the capillary tube 9 under the action of gravity.

In the operation of atomizing a liquid, the atomizer is held in position along the length of the hollow tube 1 by hand.

When switch 4 is placed in the on position, capillary tube 9 will be charged to the same potential and with the same polarity as the output produced by module 3. As a result, when the atomizer is tipped over to the atomizing position, the liquid is ejected from the capillary tube in an electrostatically charged state.

When the metal ring member 13 is grounded via the earth wire 14, the electrostatic field in and around the capillary tube 9 causes the potential at the atomizing nozzle assembly to be only eg 10-15 KV (relative to the metal ring member 13). (with positive or negative polarity) both the atomization action and the spray shape are improved. Furthermore, due to the close proximity of the metal ring member 13 and the atomizing nozzle assembly, the current from the high potential source or module 3 is primarily caused by the change in charge between the capillary tube 9 and the liquid being atomized. Therefore, it is extremely small.

As an example, the charge density of an atomized liquid is 1×10 ⁻³ coulombs/liter. Therefore, if the flow rate of the liquid is, for example, 1 x 10 ^-3 liters/second, the current drawn from module 3 is only 1 x 10 ^-6 amperes, and when the high potential is 1 x 10 ^-3 volts. An output power of simply 1×10 ⁻³ watts appears. At this low power, the useful life of the battery 2 used to power the module 3 is several hundred hours.

In order to maintain the metal ring member 13 at a low or zero potential, the ground wire 14 must be in contact with the actual ground or some other low voltage high capacitance. For portable use of the atomizer shown in FIG. 1, it is sufficient to run the ground wire 14 so that it touches or occasionally touches the ground. The atomizer can be used for short periods of time without grounding the ground wire 14 without appreciably affecting the atomization characteristics. Even if the ground wire 14 is not electrically grounded, the atomizer will continue to atomize electrostatically, even if its performance is degraded.

An inverted honeycomb member 12 along the longitudinal direction of the distributor 7
By changing the position of the metal ring member 13 with respect to the fixed position of the capillary tube 9, the potential difference between the metal ring member 13 and the capillary tube 9 and other factors such as the electrical resistivity of the liquid can be adjusted. Depending on the variables the best spray characteristics can be achieved.

Tests were conducted with various liquids and various target surfaces for the specific examples described above.

In the first test, a sprayer was used to spray an acrylic acid-based paint solution (with a resistivity of approximately 1x10 ⁷ Ωcm) onto a flat surface and a portion of a metal tube. In all cases, the spraying action was satisfactory and the well-known electrostatic "covering" effect was evident.

For the second test outdoors, 1-15 m from the sprayer.
A liquid insecticide (with a resistivity of approximately 5 x 10 ⁸ Ωcm) is electrostatically sprayed onto a pair of grounded, vertically oriented metal tubes (each 1 inch in diameter) placed downwind at a distance of However, the liquid turned into a mist at a height of about 1m above the ground. Comparative tests were conducted using a commercially available mechanical atomizer for agricultural spraying operations, which provides the atomizing action by means of an unelectrified spinning disk.

It has been found that the droplets from an electrostatic atomizer are deposited more uniformly on all metal tubes than with mechanical atomizers. Also, the electrostatic sprayer clearly provided a significant "covering" effect.

In the third test, 223P, 0-20KV,
A second test was repeated using an 11 KV device that had no regulation or feedback control and was capable of producing only 1 μA output at about 11 KV in place of the 200 μA Module 3 (eg, manufactured by Brandenburg).

In this test, the liquid was electrostatically atomized and sprayed satisfactorily.

The apparatus shown in FIG. 1 can be used to form an electrostatically charged aerosol cloud, i.e., a cloud of droplets with an average droplet size less than 50 microns in diameter, usually in the range of 1 to 10 microns. Such an aerosol cloud is formed using a liquid with a resistivity of approximately ^{5.times.10.sup.8} .OMEGA.cm at a total flow rate of 0.05 cc/sec per eight capillaries in the apparatus of FIG. 1 with capillary tubes having an internal diameter of 0.1 mm.

FIG. 5 shows a hand-held pistol type electrostatic sprayer which is another application of the present invention. In this example, the high potential source consists of a lead zirconate crystal that generates an electrical potential by the well-known piezoelectric effect.

The hand-held pistol atomizer shown in FIG. 5 has a pistol casing 21 made of insulating plastic material.
and a metal trigger 22 (shown in the released state in FIG. 5). The upper part of the trigger 22 is configured to form a cam 23.

Inside the pistol handle are two lead zirconate crystals 24 (Vernitron, Southampton, UK).
These crystal bodies 24 are equipped with a central tap connection 25. The upper side 26 of each crystal 24 is driven by a cam 23 during operation.

A distributor 27 of insulating plastic material is mounted on the nose of the pistol, and a disk 28 of insulating plastic material is supported at the end of the distributor 27 adjacent to the nose. A supply pipe 29 projects into the distributor 27 through this disk 28,
This supply pipe 29 is equipped with a stopper 30 and communicates with a supply bottle 31 containing the liquid to be sprayed.

Attached to the other end of the distributor 27 is a disk 32 of insulating plastic material through which eight metal capillaries 33 project, forming a spray assembly. Each capillary tube 33 is coupled to a bare metal wire 34 which is connected to the center tap connection 25 via a high potential cable 35 located within the barrel of the pistol.

Surrounding the distributor 27 is a cylindrical support 36 of insulating plastic material. This cylindrical support 36 is movable along the length of the distributor 27, but is sufficiently firmly locked to the distributor 27 to maintain it in any selected position by frictional engagement. A metal ring member 37 serving as a conductive surrounding member is embedded within the support body 36, and this metal ring member 37 is electrically connected to the trigger via a ground wire 38.

In operation, the tap 30 is opened to spray the liquid. This causes the liquid to flow through the supply bottle 3 under the action of gravity.
1 through the supply tube 29 to the distributor 27 and drips from the capillary tube 33.

By pulling the trigger, the cam 23 acts on the surface 26. This action compresses the crystal 24, resulting in a potential difference, which is applied to the cable 35.
is transmitted to the capillary tube 33 via. As a result, the liquid is ejected from the capillary tube 33 in the form of a mist and in an electrostatically charged state.

Grounding the metal ring member 37 via the ground wire 38, the trigger and the operator improves both atomization action and atomization shape due to the electrostatic field in and around the capillary tubes 33.

By changing the position of the support 36 along the length of the distributor 27, the metal ring member 37
The position of the capillary tube 33 can be adjusted relative to the fixed position of the capillary tube 33 to obtain the best atomization characteristics according to the potential difference between the metal ring member 37 and the capillary tube 33 and other variables such as the electrical resistivity of the liquid. .

If the trigger is pulled slowly over, say, 5 seconds, the crystal 24 will create a potential difference of about 10 KV and will impart a charge of at least 1 microclone to the liquid being atomized during the 5 second trigger actuation. Has sufficient electric capacity. The amount of liquid flowing out is approximately 1×10 ^-4
liter/second, the charge density of the atomized droplets is on the order of 2×10 ⁻³ coulombs/liter.

In spray tests using this particular embodiment, the resulting spray exhibited satisfactory spray and covering action when the target tube was grounded and held at a distance of approximately 0.5 m.

The illustrated pistol-type sprayer can be easily modified with a mechanical connection between the trigger 22 and the valve so that the pressure of the trigger opens the valve in the supply tube 29 and the release of the trigger closes the valve. . In this way, only liquid passes through the nozzle 33 when the nozzle 33 is charged.

Other nozzles that may be used in place of the nozzle of FIG. 2 in the atomizer of FIG. 1 are shown in FIGS. 7-9.

The nozzle shown in FIGS. 7 and 8 has a hollow steel cylinder 39 with uniform holes,
Also, the outer diameter of the lower half has been reduced. Cylindrical body 39
is held in its upper part by frictional engagement in the tubular distributor 7 of FIG. The lower part of the cylinder 39 is closed with a closure member 40 and is provided with four capillary-sized holes 41 extending in the radial direction of the cylinder wall.

The outer steel cylinder 42 is connected to the cylinder 39 in its upper part.
and is held in frictional engagement therewith. The lower part of the cylindrical body 42 is the cylindrical body 39
Together with the lower part of , it forms an annular cavity 43 .
Hole 41 communicates cavity 43 with the interior of cylinder 39 .

Around the distributor 7 is provided an inverted honeycomb member 12 which supports a ring member 13.

In use, when switch 4 is turned on,
The cylinders 39, 42 will be electrically charged. The liquid passing through the distributor 7 enters the cavity 43 through the hole 41, from where it emerges in the form of a mist and in an electrostatically charged state.

The nozzle shown in FIG. 9 has a solid steel cylinder 44 which is held in its upper part by frictional engagement with the distributor 7 of FIG. The cylinder 44 is provided with a central axial bore 45 extending over substantially its entire length, which terminates in a transverse bore 46 in the lower part of the cylinder. The cylindrical body 44 includes the metal wire 10 and the cable 1
1 to module 3. The lower part of the cylinder terminates as a solid disk 47 with a bottom surface 48.

In use, when the cylinder 44 is to be charged, the liquid from the distributor 7 flows through the holes 45, 46 and around the disk 47 to the bottom surface 48, from which the liquid is atomized.

If the flow rate of liquid from the holes 46 is sufficiently reduced, a spraying action of liquid from the surfaces adjacent the two outlets of the holes 46 may occur.

The example shown in Figures 10 and 11 has the atomizer of Figure 1 fitted with a deflection electrode arrangement to prevent "backward spraying".

As shown in FIGS. 10 and 11, a disk 51 of insulating material surrounds the intermediate portion of the distributor 7 and is held therein by frictional engagement. Disk 51
A deflection electrode 52 in the form of a steel ring is partially embedded in the lower side of the . The deflection electrode 52 is connected via a high voltage cable 53 to a tap 54 of a voltage divider 55. This voltage divider 55 consists of a 10 ¹⁰ Ω resistor,
One end of this resistor is connected to the high potential cable 11, and the other end is connected to the ground wire 14. The high resistance of voltage divider 55 minimizes current drain from high voltage source 3 and acts as a current limiter in the event of a short circuit in deflection electrode 52.

In operation, when switch 4 is turned on, deflection electrode 52 receives a high potential from voltage divider 55. By suitable adjustment of tap 54 any desired potential between zero volts and the potential of high voltage source 3 can be obtained. A typical voltage at deflection electrode 52 is 14KV.

The position of the deflection electrode 52 relative to the member 13 and the spray nozzle 9 can be selected by moving the disk 51 along the longitudinal direction of the distributor 7.

The liquid ejected from the nozzle 9 is atomized and directed by the force of the electric field set up by the high voltage at the nozzle 9 and by the local low potential of the member 13 due to the high potential at the deflection electrode 52.

12-14, the head of the spray device has a rectangular body 61 of insulating plastic material.
This rectangular main body 61 is equipped with a rectangular chamber 62. The rectangular body 61 is provided with an integrally formed upright protrusion 63 along the longitudinal direction of its lower surface, and this upright protrusion 63 is provided with a longitudinal slit 6.
4, and this slit 64 communicates with the rectangular chamber 62. The upper side of the rectangular body 61 has an opening 65 adapted to receive the liquid to be sprayed (by means of a device not shown), which opening 65 is arranged in the rectangular chamber 6.
It communicates with 2.

Slit 64 is divided by a conductive surface consisting of a thin metal plate 66 connected to a high voltage source (not shown). A ground metal wire 68 is held by a support 67 adjacent to the protrusion 63 .
8 is housed within a sheath 69 made of insulating plastic material.

In operation, when a high potential is applied to the metal plate 66, the liquid to be atomized flows through the opening 65 into the rectangular chamber 6.
Enter 2. The liquid exits the slit 64 and is atomized adjacent the metal plate 66. Ground metal wire 68 acts as a conductive surround on both sides of metal plate 66. Because the metal wire 68 is provided with an insulating protective surface, it can be placed closer to the metal sheath 66 than if it were not so insulated, and the risk of arcing is also greatly reduced.

In alternative embodiments, the electrically conductive member may consist of a metal wire.

In another example using a straight slit structure, multiple lines or metal plate conductive wire surfaces are arranged in parallel between multiple armored wire conductive enclosures. Such a structure results in an increased volume of liquid to be atomized.

The various devices described above are particularly useful in the method of the present invention, i.e., spraying liquid insecticides. These devices are easily portable and self-contained and are advantageously powered by a low power source such as a dry cell battery, piezoelectric device or photoelectric device.
These devices can also be easily used for atomization and deposition (eg, paint spraying, painting) or for many other purposes where only atomization is required. The method of the invention has the particular advantage that the insecticide can be applied leaf by leaf over the known methods of applying liquid insecticides. Electrostatic forces can direct the spray particles to their target with less drift and spread them to both sides of the leaf. The method of the invention also allows the shape of the spray to be varied without changing the size spectrum of the spray droplets. Liquid pharmaceutical ingredients that are applied by the method of the invention are, for example, insecticides, fungicides and herbicides. By way of example, they are in the form of solutions or dispersions of the drug in pharmaceutically inert organic diluents (eg liquid hydrocarbons), but it is also possible to dispense substantially undiluted liquid drugs. Because the distribution is uniform, drifts are minimized, and low flow rates can be used, the method is particularly suitable for distributing undiluted or highly concentrated drugs (ultra-low volume spray). There is.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the main parts of a preferred electrostatic sprayer implementing the method according to the present invention, FIG. 2 is a sectional view showing the nozzle of the sprayer shown in FIG. 1, and FIG. Fig. 2 is a bottom view of the nozzle of the atomizer, Fig. 4 is an electrical circuit diagram of the atomizer shown in Fig. 1,
FIG. 5 is a partially cutaway plan view schematically showing the main parts of a pistol-type atomizer implementing the method of the present invention, FIG. 6 is an electric circuit diagram of the pistol-type atomizer shown in FIG. 5, and FIG. Cross-sectional view of a nozzle consisting of two concentric tubes for an atomizer embodying the invention, No. 8
7 is a bottom view of the nozzle of FIG. 7; FIG. 9 is a sectional view of a nozzle consisting of a fixed conductive block for an atomizer embodying the invention; and FIG. 10 is a view of the atomizer of FIG. 1 with a deflection electrode. Figure 11 shows the 10th
12 is a perspective view showing the head of the spray device having a straight slit structure, FIG. 13 is a sectional view taken along the line - in FIG. 12, and FIG. FIG. 3 is a bottom view of a portion of the illustrated device; In the figure, 1 is a hollow tube, 2 is a battery, 3 is a high-pressure module, 4 is an on-off switch, 6 is a bottle, 7 is a tubular distributor, 8 is a disk, 9 is a metal capillary tube, 10 is a bare metal wire, 11 is a high potential cable, 13 is a conductive surrounding member, and 14 is a ground wire.

Claims (1)

Claims: 1. Supplying a liquid to a conductive or semi-conductive member forming part of a spray orifice electrically charged to a first potential, adjacent to said spray orifice and causing atomization from the spray orifice. applying another electrical potential to at least one electrode positioned away from a substantial trajectory of the droplets, and controlling at least one of the first and the other electrical potential from the atomizing orifice to the object to be atomized. 1. A method for electrostatic spraying of liquids, characterized in that desired spray characteristics are obtained regardless of the distance. 2. The method of claim 1, wherein the first potential is higher than the other potential. 3. The method of claim 1, wherein the first potential is lower than the other potential. 4. A method according to any one of claims 1 to 3, wherein the electrodes are adapted to maintain the electric field necessary to atomize the liquid into electrically charged droplets. 5. Claim 1, wherein the electrode comprises one or more electrode sections, each of which has a different control potential applied to control the spray characteristics.
4. The method according to any one of items 4 to 4. 6. Claim 5, wherein the electrode portion is selectively charged to a predetermined potential level to alter the spray characteristics.
The method described in section.