MXPA99004034A - Dispensing devices - Google Patents

Abstract

A device for dispensing material such as liquid formulations comprises a nozzle (12, Fig. 3), a passage (42) leading to the nozzle, means (50, 56, 52, 54) for establishing a slug of material in the passage (42), means (66, 68, 72, 74) for pneumatically ejecting the slug of material from the nozzle in response to operation of actuator (36) and means (32, 46, 44) for applying high voltage to the slug of material so that when the slug breaks up following ejection, the spray comprises electrically charged particles.

Description

SUPPLY DEVICES DESCRIPTIVE MEMORY This invention relates to delivery devices. The invention has particular application in electrostatic spraying devices for use in applications involving, for example, air freshening, air purification, spraying insecticides, personal care / hygiene products (eg deodorants, cosmetics and perfumes) and medical products and almost doctors such as nasal and respiratory tract sprays. The present invention seeks to provide a device that is capable of efficiently supplying material in small quantities and / or in a relatively short period of time. EP-A-224352 discloses an electrostatic spraying device for delivering ophthalmically active compounds in defined measured amounts. In the device described, liquid is supplied to the tip of the nozzle and a potential difference is applied between the nozzle and a separate electrode therefrom, so that an electric field of sufficient intensity is provided at the outlet of the nozzle to extract the formulation from the outlet as one or more ligaments that are then separated into drops. To allow the fluid to be extracted in ligaments, the liquid must be present at the tip of the nozzle at the time of the application of the potential difference. The Liquid feed is supplied to the nozzle from a liquid reservoir within the device, or extracting the liquid from a separate source using a pipetting action. According to one aspect of the present invention, there is provided an electrostatic spraying device comprising a nozzle, means for establishing a column of material to be sprinkled within a passage leading to the outlet of the nozzle, so that the surface The main column is separated from the outlet of the nozzle, means for pneumatically expelling said column or part thereof from the nozzle, and means for applying high voltage to the material, so that the spray particles formed by dissolving the column during the ejection from the nozzle are electrically charged. According to a second aspect of the invention, an electrostatic spraying method is provided which comprises establishing a column of material that will be sprinkled within a passage leading to the outlet of the spray nozzle of the device, so that the main surface of the column is separated from the outlet of the nozzle, pneumatically ejecting the column of material or part thereof from the nozzle, and applying high voltage to the material, so that the spray particles formed by dissolving the column during ejection from the nozzle are electrically charged.

Preferably, the column of material is established in the passageway as a defined fraction having a major surface separated from the outlet of the nozzle, and a rear surface to which air can be applied, gas or steam under pressure to effect the ejection of the fraction from the nozzle. In accordance with a further aspect of the present invention, there is provided an electrostatic spraying device comprising a nozzle, means for establishing a defined fraction of material to be sprinkled within a passage leading to the outlet of the nozzle (preferably such so that the main surface of the fraction is separated from the outlet of the nozzle), means for pneumatically ejecting said fraction from the nozzle, and means for applying high voltage to the material, so that the spray particles formed by dissolving the column during the ejection from the nozzle are electrically charged. Usually, the material will comprise a single-phase liquid formulation; however, the application of the invention to materials in the form of a liquid containing suspended solids is not excluded. The formulation may comprise, for exe, more than one liquid in admixture, for exe, the formulation may comprise an active ingredient, such as a nasal decongestant, a diluent and other agents such as viscosity modifying and / or resistivity agents. The possibility that the material is in the form of a pneumatically transportable flowable material other than a liquid, for exe a powder, is also not excluded. In the device according to said aspect of the present invention, a column, preferably in the form of a defined fraction, of the material to be sprinkled, is established within the passage, so that the column / fraction is located with its main surface (meniscus) separated from the outlet of the nozzle. This allows the column / fraction to be expelled cleanly from the outlet of the nozzle since the column / fraction undergoes acceleration as it travels toward the tip of the nozzle, and a relatively high velocity can thus be imparted to the liquid before it arrives. to the tip of the mouthpiece. If, for example, a liquid is located with its main meniscus at the tip of the nozzle before being pneumatically displaced, the liquid will have a low velocity at the beginning of the sprinkling operation and, in these circumstances, it has been found that the tendency for sprinkler to be fixed to the nozzle at the start of the spray action. In the same way, because the method and the preferred devices isolate a fraction of the liquid within the passage leading to the outlet of the nozzle, the fraction has a back surface and can exit cleanly from the nozzle without any significant tendency for it to occur. fixation of the spray, as would be the case, for example, where the liquid in the passage is a continuation, rather than being an isolated, of the liquid body from which it is derived. Preferably, the high voltage is applied to the material at or near the outlet of the nozzle. In accordance with a narrower aspect of the invention, there is provided an electrostatic spraying device comprising a nozzle, means for establishing a column of liquid within a passage leading to the outlet of the nozzle, so that the main surface of the fraction is located upstream of a fraction in cross section reduced that leads to the outlet of the nozzle, means for pneumatically ejecting the fraction as a jet from the nozzle, and means for applying high voltage to the fraction, so that the spray droplets formed by dissolving the jet are electrically charged. Although not limited to any particular scale of resistivity, the invention has particular application in materials of low resistivity, especially liquids; for example, liquids having an overall resistivity of less than about 1 x 107 ohms cm, including liquids having a resistivity significantly less than 1 x 104 ohms cm, for example, 1 x 103 ohms cm, and smaller. Preferably, the arrangement is such that the jet of material at the point of egress from the nozzle has a diameter of no more than 300 microns, and usually not less than about 15 microns. For example, the diameter of the jet at the point of egress may be on the scale of about 20 to about 150 microns, more preferably 25 to 125 microns, and most preferably 30 to 80 microns. The design of the nozzle is preferably such that the surface thereof at the point of egress of the material to be sprayed is prone to create corona discharge. Thus, as described in EP-A-510725, the blunt-ended nozzles are therefore preferred when the material to be sprinkled has low resistivity. The fluid pressure generated to effect the pneumatic ejection of the fraction is conveniently produced in response to the operation of drive means by the user, and said operation of the driving means can also be achieved by filling the passage leading to the outlet of the nozzle with the column / fraction in preparation for pneumatic ejection. The filling action and the compression of the fluid can occur substantially simultaneously, and the arrangement can be such that the operation of the driving means is also achieved by the operation of a high-voltage generator associated with the means for applying high voltage to the material to be sprinkled, whereby all these operations together with the expulsion of the column / fraction are effected in response to an individual operation of the means of actuation by the user. For example, the actuating means can normally be in a standby state, and the arrangement can be such that the operation of the actuating means is initially accompanied by the compression of the fluid and filling of the passage leading to the nozzle with the fraction / column , followed by communication of the compressed fluid with the interior of the passage, and by operation of the high-voltage application means so that, as the fraction is displaced by the fluid pressure, the fraction passes through a contact region at or near the immediate vicinity of the outlet of the nozzle, where the high voltage is applied to the fraction. Instead of all operations being performed in response to a single operation by the user, they can be rather decoupled. For example, at least the filling of said passage with the fraction / column may occur in response to the operation of a first actuator, and fluid compression (when necessary), high voltage application and communication between the compressed fluid and fraction / column may occur in response to the operation of a second actuator. In cases where the fluid used to expel the liquid is not previously compressed, but has to be compressed during the course of use of the device, said compression can be effected in response to the operation of the first actuator or the second actuator. In this way, the uncoupled operation of the device may be convenient where it is more convenient for the user to fill the device initially in preparation for use without necessarily having to locate the nozzle in some specific position before the filling is effected, for example, as It is required where the device functions as a nasal decongestant spray. In one embodiment of the invention, the actuating means may be movable from a standby condition by the user, and may be diverted to the standby condition, for example, by spring loading, so that the drive means return. automatically to the standby position consecutive to the drive by the user. Thus, for example, the displacement of the acclider performed by the user from his standby condition can be achieved by said fluid compression (and optionally filling said passage), and the automatic return of the actuator can be achieved by pneumatic ejection of, and application High voltage to, column or fraction. Alternatively, the displacement of the actuator effected by the user in one direction from its condition in Waiting can be achieved by such fluid compression, expulsion of the column or fraction, and application of high voltage to the fraction. The return stroke of the actuator can be returned to the device in preparation for the next supply operation, and can be achieved, for example, by disabling the voltage supply and filling the passage with a fresh fraction / column.

Typically, pneumatic ejection will involve the delivery of up to about 100 μl of the material from the nozzle. Usually, the amount supplied in each operation will be a substantially constant volume in the range of about 2 to about 50 μl. The material from which the nozzle is manufactured is conveniently one to which the material to be sprinkled is not prone to adhering, especially over that region of said passage which is occupied by the material before the pneumatic ejection. In the case where the liquid to be sprayed is a liquid or a liquid-based formulation, the nozzle is conveniently manufactured, at least in part, from a hydrophobic material which has low wetting characteristics, such as PTFE. Alternatively, the nozzle may be provided with a hydrophobic coating in said region and / or on its outer surface around the outlet of the nozzle, to suppress the wetting and "slippage" of the liquid. The coating may be, for example, an organosilicon compound. Preferably, the tip region of the nozzle is of reduced diameter with respect to said section of the nozzle upstream of the tip region. The diameter of the passage leading to the exit of the nozzle will be usually sufficiently fine, so as to avoid any tendency for the pressurized fluid to bypass the column or fraction. The device can be portable as a unit, that is, the device can comprise a housing that incorporates a high-voltage generator, a reservoir for containing the material to be sprayed, the nozzle tube with means for transferring a column or fraction of the material in the nozzle tube, and means for pneumatically expelling the column or fraction of matepal from the outlet of the nozzle. In some applications, the device may be suitable for manual use, preferably in such a way that the operation of the device can be effected by manipulating it using the hand in which said device is held. Such manipulation may involve, for example, the use of one of the fingers or the thumb to operate one or more actuators of the device. In other applications of the invention, the device may be portable as a unit, but it may be designed to be placed on a support surface, for example, the device may be used to supply formulations suitable for flavoring rooms and / or for air purification. , in which case it can be designed to be placed on a horizontal surface such as the threshold or shelf of a window, or to be mounted on a vertical surface such as a wall. In some cases, the device may be non-portable as such, but it may be designed as a fixed unit, for example, in the coating of articles or the application of agents for brand application thereto. In In this case, the operation of the device can be initiated automatically by means of a sensor arranged to detect the presence, for example, of the article at the site in which the coating or other formulation will be applied to the article. In each case mentioned above, ie portable, manual and fixed devices, the operation of the device is conveniently initiated in response to the actuation of one or more actuators or sensors, and the arrangement is such that the drive leads to the start of the following steps : Transfer of the material that will be sprinkled in said passage; pneumatic ejection of the column / fraction; and application of high voltage to the column / fraction in the course of ejection. The high voltage may be unipolar, or may be bipolar as described in the prior documents of the authors EP-A-468735 and EP-A-468736, the complete descriptions of which are incorporated herein by reference. Thus, the bipolar voltage can be used to ensure a shock suppression measurement and / or to facilitate the spraying of insulating labels (e.g., as in the case of a hair spray), as described in EP-documents. A-468735 and EP-A-468736. In cases where a bipolar voltage source is used, the arrangement is preferably such that the successive fractions (or groups of successive fractions) of material discharged from the nozzle are charged with voltage of opposite polarity. So, you can provide means to coordinate the application of voltage to the material that is being discharged with pneumatic ejection, in such a way that successive fractions of the material (or groups of successive fractions) are charged with voltage of opposite polarity. This is particularly the case where each operation of the device results in the ejection of multiple fractions of material, rather than only a single fraction per operation of the device. In the various aspects of the invention defined above, preferably the arrangement is such that the voltage is applied to each fraction of material only after the fraction has been physically isolated from the reservoir of material within the device. In accordance with a further aspect of the present invention, there is provided an electrostatic spraying device comprising a nozzle, a reservoir for containing material which will be sprayed, a passage connecting the reservoir to the nozzle, means for establishing a column of said material that will be sprinkled within the passage, such that the back surface of the column is separated from the rest of the material in the reservoir, whereby the space produces electrical insulation between the tip of the nozzle and the reservoir, and means to apply high voltage to the column of material, so that the spray particles formed by dissolving the column after ejection from the nozzle are electrically charged.

In this way, it is possible to ensure the electrical isolation of the material in the reservoir from the column or fraction of material to which it is applied the high voltage. This, in turn, allows the reservoir to be grounded if desired, and the part of the device housing the reservoir can be held in the hand without having to necessarily isolate the user from the material in the reservoir. Said electrical insulation of the main body of the material to be sprayed from the column or fraction at which the voltage is applied, can be particularly advantageous, since the capacitance of the device during spraying can be significantly reduced, and faster accumulation is possible of the electric field during the application of the high voltage, since the voltage is applied to a much smaller amount of the material that will be sprinkled. In cases where the voltage is bipolar, the main body of the material stored in the device is not subject to the voltage oscillations that occur, and since the material fraction can be expelled cleanly from the nozzle, there is a reduced tendency for ejection to occur. Heretofore, the invention has been defined in terms of producing a spray in which the spray particles are charged electrically by the application of high voltage. However, the possibility of eliminating the high voltage source is not excluded. In this aspect of the invention, a spray device is provided comprising a nozzle, a reservoir for containing material which will be sprayed from the nozzle, means for filling a passage leading to the nozzle with material of the main body of the material in the nozzle. reservoir, and means for pneumatically expelling the material thus loaded from the nozzle.

In this aspect of the invention, the material to be sprayed may comprise, for example, a liquid formulation in which case the liquid forms a spray as a result of hydraulic dissolution. In cases where the material comprises a powder, the spray may be formed as a result of the powder that becomes dispersed after ejection from the nozzle. The invention will now be described by way of example in relation to the accompanying drawings, in which: Figure 1 is a schematic view of a nozzle for use in the present invention; Figure 2 is a view similar to Figure 1, showing the fraction or column of liquid that will be sprayed, partially expelled from the nozzle; Figure 3 is a schematic view showing an embodiment of the invention for use in the delivery of nasal decongestant or similar formulations; Figure 4 is another schematic view of another embodiment in which the sequence of operation is effected by means of an individual actuator; and Figures 5 and 6 are views similar to those of Figures 1 and 2, but showing a modified method of liquid discharge. Figure 1 illustrates the principle of operation of devices in accordance with the present invention. The device comprises a nozzle tube 10 ending in a tip 12 at one end of which a output from which the liquid to be sprayed is supplied during use. The liquid to be sprayed is established within the nozzle tube 10 as a column or fraction 14, such that the main surface of the column 14 is separated from the tip 12 of the nozzle. In this way, an air pocket is present between the main surface of the column 14 and the tip of the nozzle. In addition, prior to, or during the course of ejecting the column 14 from the nozzle tube 10, an air pocket (or other gas or vapor) is established on the rear surface of the column 14. The column 14 is expelled from the nozzle tube 10 by means of a pressurized gas or steam applied to the rear surface of the column 14 (see arrow P). The diameter of the tube 10 is sufficiently small, so that the pressurized gas or vapor can not deviate from the column 14. High voltage, for example, typically of the order of 1 to 8 kV (but dependent on the particular application of the device), it is applied to the nozzle tube by the voltage generator (not shown). For this purpose, the tube 10 includes a section 16 which is sufficiently electrically conductive for the designed purpose of applying high voltage to the liquid to be sprayed. The rest of the tube upstream of section 16 is fabricated from an electrically insulating material. The part of the tube downstream of section 16 may be electrically insulating, but preferably the section below will have some means for conducting the voltage toward the waste liquid in the downstream section after its back surface has cleaned the electrode section 16. So, the tube section below section 16 it may be semiconductive, or it may have a conductive or semiconductive path or its like, along its inner surface. In operation, when the pressurized fluid is applied to the tube , the column 14 is displaced towards the tip of the nozzle 12, and passes through the section 16, where it is electrically charged. Before reaching the tip of the nozzle 12, the column 14 is accelerated by the pressurized fluid and, consequently, will be moving rapidly for when the main surface of the column 14 reaches the tip of the nozzle. In this way, a clean start is achieved in the spraying operation, since the liquid does not reach the tip of the nozzle until it has been accelerated. The column 14 during ejection from the tube 10 forms a stable jet 18 which is separated into electrically charged particles which disperse as a spray. In the case of liquids, the jet separation may be mainly of a hydraulic nature, or may be determined at least to some degree by the high potential gradient that prevails in the region of the tip of the nozzle with respect to the surroundings or a target which will be sprayed. In the latter case, the jet formed by the column as it emerges from the tip of the nozzle 12 may undergo some electrostatically induced narrowing in the manner described in the prior document of the authors, EP-A-510725, the complete description of which is incorporated in the present as a reference. After the entire column 14 has been expelled, the pressurized fluid continues to discharge from the tip of the nozzle 12, and serves to purge the tube for the next operation. The purge action performed by the pressurized fluid reduces any tendency for the disperse liquid to remain in the vicinity of the tip of the nozzle 12, which may otherwise lead to the disorderly affixation of the spray at the tip of the nozzle at the end of the operation of aspersion and / or at the beginning of the next spray operation. The tip of the nozzle 12 is conveniently of reduced diameter, as shown, so that the column is "extruded by impact" through the outlet of the nozzle, thus further increasing the speed of the jet 18. Said reduction in diameter The tip of the nozzle 12 can be achieved by carrying a tube down at one end thereof, or by molding the tube with a closed end and then drilling a small diameter hole through the closed end by laser drilling or ultrasonic drilling. Typically, the volume of column 14 will be substantially constant for a given application, and will range from about 2 to 100 microliters, more usually from 2 to 50 microliters. With the proper design of the nozzle, particularly the diameter of the outlet at the tip of the nozzle, materials with a broad scale of volume resistivities can be successfully sprayed. In the case of liquids, for example, it has been found that satisfactory spraying can be achieved with liquids having volume resistivities as low as 1 X 103 ohms cm, and even lower (e.g., 2 x 102 ohms cm), although with resistivities as low as this, the "shrinkage" effect referred to above is not usually observed. How I know described in EP-A-510725, the electrostatically induced narrowing is advantageous when very fine droplet sizes are required. In cases where very low resistivity liquids are used, the absence of some electrostatically induced significant narrowing can be compensated, if desired, by the use of a small diameter nozzle outlet. Typically, the diameter of the outlet at the tip of the nozzle is not more than 300 microns, and usually not less than about 15 microns. For example, the diameter of the outlet can be on the scale of around 20 to about 150 microns, more preferably 25 to 125 microns, and most preferably 30 to 80 microns. Referring to Figure 3, the nasal spray comprises a housing 30 suitably dimensioned for manual use. The housing accommodates a high-voltage generator 32 and a low-voltage battery source 34 to turn on the generator. The battery source may comprise one or more replaceable batteries which may be of the rechargeable type, if desired. The generator typically produces a high voltage output of about 1 to 3 kV to about 12 to 15 kV, preferably 2 to 3 kV to about 9 to 10 kV. The operation of generator 32 is controlled by means of a switch actuator 36 suitably positioned for operation by the user, while holding the device in one hand. In this embodiment, the switch actuator 36 is of the push button type, and is generally located in the central part of the housing 10 to facilitate its Operation with the thumb or other fingers while holding the device in the palm of the hand. A return path to ground can be established through the user, for example, by providing some form of contact on the housing 30, for example, the switch actuator 36, so that when the device is held in the hand, a ground connection is provided through the user. The housing 30 is made of a plastic material which has good electrical insulation properties, and is designed in accordance with the teachings of EP-A-441501 above to allow the use of an economical and compact generator. A nozzle 38 is provided at one end of the housing 30, and is located within a nasal piece 40, which can be formed by one or more openings (not shown) through which air can be extracted by the user in the course of inhalation through the nose. The nozzle 38 is conveniently made of a plastic material not electrically insulating (for example PTFE), and communicates with an axially extending passageway 42, which may be in the form of a tube of electrically insulating material. In the vicinity of the tip of the nozzle 38, the passageway 42 is provided with an electrode 44 which may be cylindrical with an inside diameter that corresponds generally to the interior diameter of the passage. 42. The electrode 44 is connected to the high voltage output of the generator 32 via the terminal 46. The generator 32 is energized by the operation of the switch actuator 36, which part 36A is arranged to effect the closing of a switch contact. 48 by means of a cam action according to actuator 36 is displaced internally with respect to the housing against the action of a spring 49. The closure of contact 48 terminates a circuit including generator 32 and low voltage source 34, thus igniting the generator. The generator can be of the design described in EP-A-441501. The spring 49 serves to bias the switch actuator 36 to a position corresponding to the deactivation of the generator 32. The liquid from a reservoir 50 is supplied to the passage 42 via the tube 52 and the unidirectional valve 54 in response to the displacement of the plunger 56. connected by the rod 57 to an actuator 58 slidably mounted at the end of the housing away from the end of the nozzle. The reservoir 50 can be a replaceable "plug-in" cartridge. The actuator in this case is increasingly operated under the control of a detent 60 mounted in the housing for cooperation with a pawl 62 provided internally to the actuator 58 which is in the form of a cap that surrounds the far end of the housing. The liquid that will be delivered extends from the reservoir 50 through the tube 52 to the valve 54, so that in response to each increment of movement of the actuator 58, a small amount of liquid is transferred from the tube 52 to fill the passageway. 42 in the manner illustrated in Figure 1. The gradual actuation of the actuator 58 also serves, through displacement of a plunger 68 mounted on the rod 64, to pressurize air in a reservoir 66. The air passes through the valve 70 in a pressure chamber 72 which can communicate with passage 42 under control of a slide valve 74 carried by the actuator 36. The valve 74 includes a hole 76 which moves in register with the passageway 42 when the actuator 36 is operated. Normally, the valve 74 serves to isolate the pressure chamber 72 from the passage 42. However, when the orifice 76 moves in register with the passageway 42 and provides communication with the pressure chamber 72, a pulse of compressed air is injected, which serves to expel the fraction of liquid from the passage. It will be noted that the registration of the orifice 76 with the passage 42 is achieved by energizing the generator, and consequently high voltage is applied to the liquid through the electrode 44 as the liquid travels toward the tip of the nozzle. At the point of time when the high voltage is applied to the liquid, the back surface of the fraction will be downstream of the junction between the passage 42 and the passage 52 and, consequently, the fraction will be physically and electrically isolated from the liquid in the passage 52 and reservoir 50. Accordingly, if the relevant components of the device are made of an electrically insulating material, the liquid in the reservoir 50 can be at or near the ground potential. The passage 80 at the tip of the nozzle is of reduced cross section compared to the passage 42 for the reasons mentioned in relation to the embodiment illustrated in figure 1. In operation, the user initially fills the device and compresses the air by operating the acclimator 58, that is, moving it in the direction A in figure 3. This results in a fraction of liquid that is introduced into passage 42 in readiness for the next stage of the operation. The user then registers the nasal piece 40 with the nostrilo, which will receive the spraying, and operating the actuator 36 which, during the initial part of its trip, operates the switch 48 to activate the generator 32, and then moves the orifice 76 in register with the passage 42 allowing the release of the air pulse from the chamber 72 and the consequent expulsion of the liquid fraction in the manner described in relation to Figure 2. While operating the actuator 36, the user can inhale through the appropriate nozzle to produce an air flow through the mouthpiece. the nasal piece 40 to facilitate the extraction of the spray in the nasal cavity, although this is not essential for the functioning of the device. Because the spray drops are electrically charged, they will quickly deposit on the lining of the nasal cavity or inside the upper respiratory tract, thus ensuring that their penetration is limited. Any tendency for spray deposition on parts of the device during the spraying process can be reduced by fabricating the nasal part of a good electrically insulating material which will tend to retain any load that it picks up during spraying. Thus, when the spray starts, the corona effects lead to some deposition of loads on the nasal piece, which, in turn, tends to repel equally charged spray particles. In relation to figure 4, this modality is similar to that of the figure 3, but is configured to allow operation of the device by means of a single operation by the user. The device comprises a housing 80 which is suitably sized for manual use, and accommodates a high-voltage generator 82 and a low-voltage battery source 84 to turn on the generator. The operation of the generator 82 is controlled by means of a switch actuator 86 suitably positioned for operation by the user while holding the device in one hand. A return path to ground can be established through the user, for example, by providing some form of contact about accommodation 80, so that when the device is held in the hand, a ground connection is provided through the user. A nozzle 88 is provided at one end of the housing 80, and is located within a nosepiece 90 which may be formed by one or more openings (not shown) through which air may be withdrawn by the user in the course of inhalation through the nose. The nozzle 88 is conveniently made of a non-wettable electrically insulating plastic material (e.g. PTFE), and communicates with an axially extending passage 92, which may be in the form of a tube of electrically insulating material. In the vicinity of the tip of the nozzle 88, the passage 92 is provided with an electrode 94 which may be cylindrical with an inside diameter that corresponds generally to the interior diameter of the passage 92. The terminal passage 130 provided in the nozzle is sectional cross section reduced for the reasons described above. The electrode 94 is connected to the high voltage output of the generator 82 via the terminal 96. The generator 82 is energized by operation of the switch actuator 86 by an arm 150 mounted on a guide 152 after the lost motion. has been compensated, there being a space 154 between the front end of the actuator 86 and the guide 152. Thus, as the actuator 86 is displaced internally with respect to the housing against the action of a spring 99, the front end of the actuator 86 comes into contact with the guide 152, and moves it to the left, as seen in figure 4 with the consequent operation of the switch 98, the activation of the generator 82 and therefore the application of high voltage to the electrode 94. After the release of the 86 actuator, the actuator and the guide 152 are returned to the positions shown by springs 99 and 158. Liquid from a reservoir 100 (not necessarily to scale) is supplied to passage 92 via tube 102 and unidirectional valve 104 in response to displacement of plunger 106 connected to it. actuator 86 by rod 107 and arm 108. Reservoir 100 may be in the form of a replaceable "plug-in" cartridge. The liquid in the reservoir 100 is removed by the unidirectional valve 110 in the tube 102 during the return movement of the actuator 86, and is injected as a fraction in the passage 92 in response to displacement of the actuator 86 inwardly. The lost movement 154 introduces a delay between the injection of liquid in the passage 92 and the activation of the generator 82. The displacement of the actuator 86 inwards also serves, through the displacement of a plunger 114 coupled to the actuator by the rod 116 and the arm 108, to maintain a supply of pressurized air in a reservoir 118 by feeding air through tube 119 and the valve unidirectional 122 to reservoir 118 and associated tube 124. Tube 124 may communicate with tube 92, but is usually isolated from the latter by guide 152 which functions as a valve. The communication between the tubes 124 and 92 is established when the guide is sufficiently displaced by the actuator 86 to carry a hole 126 in register with the tube 124. This is phased in such a way that the switch 150 is activated to activate the generator 82, the communication between the tubes 124 and 92 being established in advance. After the communication is established, a pulse of air travels along the passage to eject the fraction of liquid in the passage 92 out of the nozzle 88 in the described in relation to figures 1 and 2. Air is drawn into the device through the filter 130 by the valve 132 during the return movement of the actuator 86 and, therefore, of the plunger 114. The reservoir 118 may be provided with means to provide a visual indication that it is sufficiently pressurized to initiate supply operations. Initially before the device can be used for supply operations, the cylinder in which the plunger 106 operates and the associated tube 102 must be filled (e.g., as part of the manufacturing process). From the foregoing, it will be noted that the sequence of operations is performed in response to a single operation of the actuator 86. In this embodiment, once the device has been initially filled for use, the user would first register the nasal piece 90 with the appropriate nostnlo, and then press the actuator 86 inwardly, resulting in the following sequence: • actuation of the pistons 106 and 114, with the consequent injection of a fraction of liquid in the tube 96 and pressurization of the reservoir 118, • activation of the generator to apply high voltage to electrode 94, • transmission of an air pulse along the tube 92, • electric charge of the liquid fraction, and • ejection and dissolution of the fraction in a spray. When the actuator 86 is released to return to the position shown, the pistons 106 and 114 and the slide valve 152 are returned to the positions shown, with the accompanying liquid replenishment and air supplies in the tubes 102 and 109 and the deactivation of the generator 82. In the embodiments described above, a defined fraction of liquid is Injected into the passage leading to the nozzle. In an alternative embodiment as illustrated in Figures 5 and 6, the arrangement is such that the liquid is established as a column within the passage leading to the tip of the nozzle and not necessarily as a fraction isolated from the liquid supply reservoir. . Thus, as shown in Figure 5 (where the parts in common with the embodiment of Figure 1 are indicated by the same reference numerals), prior to ejection, a column 200 of liquid is established within the tube 10, the which can be extended (although this it is not essential) without interruption from the main liquid reservoir. Column 200 is established in such a way that it extends beyond the entrance 202 with its main surface 204 retracted from the tip of the nozzle portion 12. The inlet 202 is connected to a source of pressurized fluid (e.g., air). When the liquid supply is started as a spray, the air is injected through the inlet 202 into the tube 10 to separate in the column of liquid at that site, and thus isolate the part 206 from the liquid which is then driven further past the high-voltage electrode 16 and out of the nozzle (see Figure 6) to form a spray of electrically charged droplets.

Claims (25)

NOVELTY OF THE INVENTION CLAIMS

1. - An electrostatic spraying device for forming a spray from a column of material, the device comprising a nozzle; means for establishing the column of said material to be sprinkled within a passage leading to the nozzle outlet, so that the main surface of the column is separated from the outlet of the nozzle; means for expelling the column of material from the nozzle; and means for applying high voltage to the column of material, so that the spray particles formed by dissolving the column during ejection from the nozzle are electrically charged.

2. The device according to claim 1, further characterized in that the column of material is established in the passage as a defined fraction having the main surface separated from the outlet of the nozzle.

3. The device according to claim 1 or 2, further characterized in that the ejection means comprise means for pneumatically expelling said column / fraction from the nozzle.

4. The device according to any of claims 1 to 3, further characterized in that the high voltage is applied to the column of material at or near the outlet of the nozzle.

5. - The device according to any of claims 1 to 4, further characterized in that the material is liquid; and a reduced cross-sectional portion leading to the outlet of the nozzle is provided, the main surface being located arpba current of the reduced cross-sectional portion.

6. The device according to any of claims 1 to 5, further characterized in that the arrangement is such that the column / fraction of material at the point of egress from the nozzle has a diameter no greater than 300 microns.

7. The device according to any of claims 1 to 6, further characterized in that the expulsion of the column / fraction occurs in response to the operation of means of activation by the user.

8. The device according to claim 7, further characterized in that the operation of the drive means is achieved by filling the passage leading to the exit of the nozzle with the column / fraction in preparation for ejection.

9. The device according to claims 7 or 8, further characterized in that the operation of the driving means is also achieved by the operation of a high-voltage generator associated with the means for applying high voltage to the material to be sprinkled, whereupon all these operations in conjunction with the expulsion of the column / fraction are carried out in response to a single operation of the drive means by the user.

10. The device according to claims 7 or 8, further characterized in that the expulsion of the column or fraction and / or the application of the high voltage thereto is effected in response to a separate operation of the operating or operating means. of different driving means that effect the filling and / or ejection.

11. The device according to any of the preceding claims, further characterized in that the tip region of the nozzle is of reduced diameter with respect to the section of the nozzle upstream of the tip region.

12. The device according to any of the preceding claims, further characterized in that the high voltage is unipolar.

13. The device according to any of claims 1 to 12, further characterized in that the high voltage is bipolar.

14. - The device according to claim 13, further characterized in that the arrangement is such that successive columns / fractions (or successive groups of columns / fractions) of material discharged from the nozzle are charged with voltage of opposite polarity.

15. The device according to any of the preceding claims, further characterized in that the material is discharged as a jet which, at the point of egress from the nozzle, has a diameter on the scale of about 20 to about 150 microns.

16. The device according to claim 15, further characterized in that the material is discharged as a jet that, at the point of egress from the nozzle, has a diameter in the range of 25 to 125 microns.

17. The device according to claim 16, further characterized in that the material is discharged as a jet which, at the point of egress from the nozzle, has a diameter in the range of 30 to 80 microns.

18. The device according to any of the preceding claims, further characterized in that the device further includes a reservoir to contain the material to be sprinkled, the passage connecting the reservoir to the nozzle.

19. The device according to claim 18, further characterized in that the rear surface of the column / fraction is isolated from the rest of the material in the reservoir.

20. The device according to claim 19, further characterized in that the rear surface of the column / fraction is physically isolated from the rest of the material in the reservoir.

21. The device according to claim 19, further characterized in that the rear surface of the column / fraction is electrically isolated from the rest of the material in the reservoir.

22. - The device according to claim 19, further characterized in that the rear surface of the column / fraction is physically and electrically isolated from the rest of the material in the reservoir.

23. The device according to any of the preceding claims, further characterized in that the material to be sprinkled is a liquid having an overall resistivity of less than about 1 x 107 ohms cm.

24. The device according to claim 23, further characterized in that the liquid has an overall resistivity of less than 1 x 104 ohms cm.

25. The device according to claim 24, further characterized in that the liquid has an overall resistivity of 1 x 103 ohs cm or less.