EP0590165B1 - Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité - Google Patents

Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité Download PDF

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Publication number
EP0590165B1
EP0590165B1 EP92116182A EP92116182A EP0590165B1 EP 0590165 B1 EP0590165 B1 EP 0590165B1 EP 92116182 A EP92116182 A EP 92116182A EP 92116182 A EP92116182 A EP 92116182A EP 0590165 B1 EP0590165 B1 EP 0590165B1
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EP
European Patent Office
Prior art keywords
nozzle according
electrostatic nozzle
duct
liquid
spraying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92116182A
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German (de)
English (en)
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EP0590165A1 (fr
Inventor
Hans Ing. Fischer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Schablonentechnik Kufstein GmbH
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Schablonentechnik Kufstein GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Schablonentechnik Kufstein GmbH filed Critical Schablonentechnik Kufstein GmbH
Priority to ES92116182T priority Critical patent/ES2099187T3/es
Priority to AT92116182T priority patent/ATE149102T1/de
Priority to DE59208075T priority patent/DE59208075D1/de
Priority to EP92116182A priority patent/EP0590165B1/fr
Publication of EP0590165A1 publication Critical patent/EP0590165A1/fr
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Publication of EP0590165B1 publication Critical patent/EP0590165B1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/14—Forme preparation for stencil-printing or silk-screen printing
    • B41C1/147—Forme preparation for stencil-printing or silk-screen printing by imagewise deposition of a liquid, e.g. from an ink jet; Chemical perforation by the hardening or solubilizing of the ink impervious coating or sheet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
    • B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
    • B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
    • B05B17/0607—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns

Definitions

  • the invention relates to an electrostatic nozzle according to the preamble of patent claim 1.
  • Such an electrostatic nozzle is already known from DE-B-1 103 191 and contains a piezo element for generating high-frequency mechanical vibrations, a membrane coupled to the piezo element, to which the mechanical vibrations can be transmitted, and which forms a wall of a pressure chamber for Receiving a liquid to be sprayed out and under pressure serves an ejection channel leading from the pressure chamber for ejecting the liquid from the pressure chamber and a plunger connected to the membrane, which extends through the pressure chamber and into the ejection channel, and onto which the vibrations are so transferable that it swings in its longitudinal direction.
  • Electrostatic nozzles can be used to make printing stencils, for example to be able to print on textile webs.
  • the printing stencils mentioned are usually thin sieves which are flat or cylindrical in shape and have a pattern which is usually carried out in printing ink-resistant lacquer. It is known to produce such stencils by coating screens with light-sensitive varnishes, exposing these so-called photoresists with a pattern and then developing them. A distinction is made between negative and positive varnishes, depending on whether the exposed areas have remained after development or have been removed by the development process. The exposure can take place in a conventional manner via a large film or can be projected on using optics. It is also known to coat the see with an easily evaporable lacquer and then to remove this lacquer thermally or photolytically with a focused laser beam.
  • a covering liquid must be applied in the finest drops, the liquid having a high viscosity in order to be able to carry a sufficient proportion of solid substance with a relatively small drop size.
  • this method only makes sense if a very high drop frequency can be achieved.
  • the cover liquid it can be, for. B. an aqueous emulsion of a synthetic resin varnish or an aqueous suspension of pigments.
  • the invention has for its object to provide an electrostatic nozzle of the type mentioned in the preamble of claim 1, with which highly viscous liquids can be sprayed in droplets, and which at the same time has a shorter overall length.
  • An electrostatic nozzle according to the invention is characterized in that the liquid can be discharged continuously from the ejection channel and that in the ejection channel the tappet excited to vibrate ensures regular disturbances of the liquid flow in that annular flow channel which is formed by the tappet and the ejection channel.
  • the plunger preferably consists of a needle holder connected to the membrane and lying within the pressure chamber, the free tip of which carries a needle protruding into the ejection channel.
  • the needle holder is horn-shaped and tapers in the direction of the ejection channel. So he can z. B. taper stepwise or according to an exponential function.
  • the piezo element is coupled to the membrane via a pressure piece tapering in the direction of the membrane.
  • a pre-amplification of the amplitude to be transmitted to the needle holder is achieved mechanically, so that the disturbances to be transmitted to the liquid jet can be further amplified.
  • the electrostatic nozzle according to the invention can, for. B. are used in a device, the at least one bearing device for the frontal storage of a hollow cylindrical screen, a drive device for rotating the screen about its cylinder axis, a parallel to the cylinder axis movable processing table and a control device for controlling the drive device, the transport of the processing table and Control of the nozzle arranged on the processing table has.
  • the nozzle receives electrical ejection signals from the control device, in accordance with a predetermined pattern and in dependence on the rotary position of the screen cylinder and the position of the processing table.
  • the pattern or print pattern can be pre-stored in electronic form in an electronic memory of the control device.
  • Each saved sample point is assigned a pair of values that contains the rotary position of the screen cylinder (angular position) and the axial position of the machining table. As soon as this pair of values is supplied to the control device by sensors, the assigned value of the pressure pattern is read out of the named electronic memory and used to form an ejection signal which is transmitted to the nozzle.
  • the control device outputs the electrical ejection signals to the respective nozzle located further back in the transport direction of the processing table, in such a way that one and the same point on the screen surface is sprayed successively through the respective nozzles.
  • the electrical ejection signals are transmitted to all the nozzles at the same time, in order to combine different liquids at one point, which react with one another there to form a highly viscous gel.
  • flow movements often occur which can lead to a deterioration in the edge structure if the cover layer is produced from only a one-component material which has a relatively long drying time.
  • the setting time can be shortened considerably if several suitable liquid components are selected, which leads to an improved contour definition of the pattern.
  • the reference numeral 1 denotes a rotating sieve in the shape of a cylinder, to which paint or varnish is applied as a covering liquid through one or more nozzles.
  • This turns one of the nozzles 2 sprayed jet 3 of the covering liquid is controlled by means of a computer 4 so that the covering liquid is applied to the screen 1 only at those points at which the screen 1 must be covered due to the pattern and those areas of the screen 1 remain uncovered where they remain permeable should.
  • the sieve 1 is received between two synchronously driven end heads 5 and set in rotating motion (direction of rotation D).
  • the right end head 5 can, for example, be displaced in the direction of the cylinder axis of the circular screen 1.
  • the sieve 1 is placed between the right and left end heads 5 and the right end head 5 is brought up to the sieve 1.
  • the screen 1, which is usually very thin and light, can possibly be set in rotation by the axially acting clamping force and the friction between the screen 1 and the left driven end head 5.
  • the rigidity of the screen 1 is always sufficient to notify the right end head 5 of the rotational movement via the acting frictional forces, if only the speed of the screen 1 is increased so slowly that the required acceleration torque does not overwhelm the transmission capacity of the circular screen 1.
  • Both end heads 5 are rotatably mounted on pedestals 6, the pedestals 6 being arranged on a machine bed 7. To guide the right pedestal 6 in Figure 1 guide rods 8 are available, the z. B. can be attached to the machine bed 7.
  • the left end head 5 is driven by a motor 9 and a belt 10.
  • This belt 10 spans a drive wheel 11 which is fixed on an axis 12 which carries the left end head 5.
  • an incremental pulse generator 13 which determines the rotational position of the axis 12 or the sieve 1 and outputs corresponding signals S D to the computer 4.
  • the nozzles 2, which are fastened on a processing table 14, are slowly advanced in the direction of the cylinder axis 1b of the sieve 1, so that a thin jet of droplet and consisting of masking liquid, which emerges from the nozzles 2, is very low along a helix Slope hits the sieve 1.
  • the feed table is impressed on the processing table 14 via a spindle 15, this spindle 15 being driven for this purpose via a stepper motor 16, which also receives its step signals S T from the computer 4.
  • step signals S T are converted into power pulses P T by a driver stage 17.
  • the rotation of the motor axis of the stepper motor 16 is controlled by a belt 18 and a pulley 19 transferred to the spindle 15. This extends through the processing table 14, which in turn is guided on guide rails 20 on the machine bed 7.
  • the nozzles 2 must be supplied with a covering liquid suitable for the subsequent printing process.
  • they are connected to small pressure vessels 21 via supply lines 22.
  • the covering liquid is under a slight excess pressure of approximately 1 to 5 bar.
  • a separate pressure container 21 will be provided for each nozzle 2, since differences in the line resistances and the need to be able to regulate the application quantity separately per nozzle 2 cause different outlet pressures of the covering liquid.
  • Each nozzle 2 also has a not inconsiderable amount of unused covering liquid which has to be continuously sucked off and conveyed back.
  • vacuum tanks 23 are provided, into which the unused covering liquid is returned via return lines 24 due to the negative pressure prevailing in these tanks.
  • the recirculated cover liquid which has lost diluent as a result of the process which has passed through, can in turn be supplied to the application process as a cover liquid after preparation.
  • the nozzles 2 are arranged several times, in the present case twice. They are spaced apart from one another in the direction of the cylinder axis 1b or template axis in order to give the covering liquid time to dry at least slightly before the second application. This drying can be supported by blowing warm air, or by generating appropriate heat radiation.
  • a correspondingly designed heating device H can be mounted on the processing table 14.
  • UV radiation Irradiation of the liquid drops sprayed onto the sieve 1 with ultraviolet (UV) radiation is also possible in order to start or accelerate the crosslinking reaction earlier, which leads to an even better edge definition of the pattern (UV hardening).
  • the short phase of lowering the viscosity, which occurs during heating, is therefore avoided with pure UV curing.
  • This curing with UV light takes place, for. B. by means of a arranged on the processing table 14 light source z. B. can be a mercury vapor lamp.
  • the nozzles 2 can also be displaced in the circumferential direction of the cylinder 1 or sieve, but this leads to difficult handling the coating process if successive circular screens 1 of different diameters are to be coated.
  • the nozzles 2 are designed as electrostatic nozzles, each of which is supplied with a control signal S 1 , S 2 from the computer 4 in order to spray out the covering liquid when a control signal is received.
  • FIG. 2 shows a device that is basically the same as in FIG. 1, the same elements being provided with the same reference numerals.
  • the processing table 14 is mounted on a rear support wall 25 on guide rails 26 so that it can be moved in the axial direction of the cylinder 1.
  • the spindle 15 and the stepping motor 16 with spindle drive 18 and 19 are also fastened to this rear guide wall 25.
  • the nozzle openings 28 point downward.
  • the vertical ejection ensures that the path of the drops initially remains unaffected by gravity and the drops can therefore pass exactly through the center of a ring electrode in front of the ejection channel for electrostatic charging before they are finally deflected by a subsequent deflection electrode.
  • the drop path is already influenced by gravity immediately behind the ejection channel, so that it is more difficult to hit the center of the ring electrode.
  • the covering liquid In the coating process, the covering liquid must be applied in the finest drops in order to achieve a sufficiently high resolving power when generating the print pattern on the surface of the screen 1.
  • the liquid has a high viscosity in order to be able to carry a sufficient proportion of solid substance with a relatively small droplet size.
  • Several liquid components can also be sprayed on separately through different nozzles, which are combined at one point on the surface of the screen 1, as mentioned. However, the procedure only makes sense if the drop frequency is very high can be achieved.
  • electrostatically acting nozzles in which a liquid jet is regularly broken down into drops by a very high-frequency vibration, for example a pipe wall, and in which the drops are then electrically charged and deflected or, depending on the charge state, in an electrostatic field not be distracted.
  • conventional nozzles of this type are not suitable for processing the highly viscous covering liquids required for coating screens. While with low-viscosity liquids, even minor initial disturbances are enough to quickly break the liquid jet into individual drops due to the effect of the surface tension of the liquid immediately behind the nozzle outlet, jet lengths of 0.5 - 1.0 m would result with the high viscosities required for masking before the first drop is caused by beam constriction.
  • An annular charging electrode with a very small diameter must be arranged at the location of the first drop formation. Due to the inevitable air swirls, at such intervals neither the location of the first drop formation can be determined precisely nor the course of the jet, so that it can no longer be passed through such a small annular charging electrode.
  • the invention therefore uses electrostatic nozzles with a modified design.
  • Figure 3 shows the structure of such an electrostatic nozzle 2 according to the invention.
  • the covering liquid which is supplied from the pressure containers 21 shown in FIG. 1, is under excess pressure. From there it emerges continuously through a bore 30 (spray channel).
  • a thin needle 31 which is excited by ultrasound to produce high-frequency vibration in the longitudinal direction of the needle, provides regular disturbances in the annular flow channel formed by the needle 31 and the bore 30.
  • the oscillatory movement of the needle 31 also prevents the bore 30 from becoming blocked, for example. B. by small particles.
  • a ring electrode 33 is provided, which is kept small in diameter, because sufficient charging of the drops can then be achieved even at low voltages.
  • the aim is to be able to work with a voltage of 100 - 200 V. This voltage must be present at the ring electrode 33 at the moment the drop breaks off. Voltages of this size can still be conveniently switched at high frequencies using transistors.
  • the drop At the time the drop is torn off from the still connected jet, it must be kept at a zero voltage potential with respect to the ring electrode 33, so that a negative charge remains on the tearing drop, and the tear must also take place in the area of the ring electrode 33.
  • the ring electrode 33 is kept small in diameter, whereby high field strengths are achieved even at lower switching voltages.
  • the charged liquid drops which here have the reference numeral 34, are then guided into a catcher 37 by the action of a direct voltage field applied via a high-voltage deflection electrode 35 on a curved path 36. From there they arrive via the return lines 24 mentioned in FIG. 1 into the vacuum tanks 23 which are also shown there.
  • the uncharged liquid drops 38 are not deflected by this DC voltage field and accordingly continue their path almost linearly along the railway line 39 in order to finally reach the sieve 1 hold true.
  • the screen 1 here has a position perpendicular to the web 39 of the unloaded drop 38 hitting it. However, it may well be expedient to incline this sieve 1 in relation to such a position, which is shown in connection with the next FIG. 4.
  • the covering liquid must transport solids to a sufficient extent in order to form a well-covering film after drying on the sieve 1, as a result of which a high viscosity is required.
  • the high viscosity helps, however, that after the covering liquid has been applied to the sieve 1, it remains at the impact point despite the centrifugal force acting on it and does not shoot through the perforation of the sieve due to the high impact speed or sprayed into even smaller droplets during the impact on the sieve 1.
  • a combined liquid and air or inert gas supply is carried out in the area of the ring electrode 33.
  • liquid is first introduced through bores 40, which are introduced laterally to the spraying channel 30 and in a massive wall 55 of the pressure chamber 29 opposite a membrane 47, in order to clean the ring electrode 33. It is then blown dry through the same bores 40, for example by dry, heated air or an inert gas.
  • the same configuration of the nozzle is additionally used to prevent the thin bore 30 from drying out during longer work breaks.
  • the adjacent air space 41 in front of the bore 30 and inside the ring electrode 33 is filled with flushing liquid through the bores 40.
  • the air space 41 is greatly expanded compared to the diameter of the bore 30.
  • This rinsing liquid is kept under a very slight excess pressure (approximately 10 to 20 mm water column), as a result of which a liquid meniscus 43 is formed within the nozzle channel 42, which can persist for a long time and which prevents liquid from escaping from the nozzle channel 42.
  • This filling protects the thin bore 30 from drying out.
  • a conical countersink 44 can be provided in the wall 55. Through it the bore 30 opens into the nozzle channel 42 in the direction of the ring electrode 33.
  • the rinsing liquid may also be expedient not to let the rinsing liquid come into contact with the covering liquid within the bore 30 in order not to dilute the latter.
  • the conical countersink 44 is omitted, and there is only a correspondingly small cylindrical drilling attachment at this point.
  • the rinsing liquid will then also form a meniscus in this hole, similar to meniscus 43.
  • the covering liquid at the exit of the hole 30 also forms a meniscus.
  • Between the two menisci there is then a small air space which, thanks to its small volume, quickly contains vaporous molecules that are easily evaporated Components of the top coat and the rinsing liquid is saturated. A further evaporation of these components from the masking lacquer is then no longer possible, so that drying is prevented without the risk of the masking liquid being thinned by rinsing liquid.
  • the nozzle 2 is advantageously also flowed through by air during the application of covering liquid onto the sieve 1.
  • the dry air emerging from the bores 40 keeps small secondary droplets away from the ring electrode 33 and thus cleans them.
  • Such secondary droplets arise simultaneously with the main droplets when the liquid jet emerging from the bore 30 decays. Because of the smallness and the low mass of these secondary droplets, they can be thrown against the ring electrode 33 by the pinching process of the main droplets. If droplet deposits would form there, then the proper functioning of the electrode could be questioned over time.
  • a further effect results from the flow through the diffuser-like channel 42.
  • the flight speed of the drops should be delayed somewhat, but not too much, since they may only touch one another after they have hit the screen 1.
  • FIG. 4 shows the overall structure of the nozzle according to FIG. 3.
  • the same reference numerals apply as in FIG. 3.
  • the direction of impact of the drops 38 on the screen 1 is no longer vertical here, but is at an angle 45. This helps the drops to prevent it from passing through the sieve 1 because there is always a material wall in front of each drop in the direction of its trajectory.
  • the relative speed between the droplet and the sieve can be reduced thereby, which further reduces the risk of the droplets bursting when they strike the sieve 1.
  • the needle 31 is held in a needle holder 46 which is designed as a step horn, ie the diameter of the needle holder 46 decreases towards the tip of the needle 31.
  • the needle holder 46 is firmly held in a membrane 47 (bending vibration membrane) and this is excited by a piezo element 48 to the high-frequency vibration.
  • a pressure piece 49 transmits this vibration to the membrane 47, so that the liquid in the pressure chamber 29 is also pressurized by this membrane 47 itself.
  • the supply lines to the pressure chamber 29 must be designed to be correspondingly thin.
  • the pressure piece 49 tapers in diameter in the direction of the needle holder 46.
  • the piezo element 48 is supplied with a high-frequency sine or square wave voltage corresponding to the natural frequency of the nozzle arrangement by supply lines, which are no longer shown. Since the piezo element 48 is composed of a large number of thin layers in a sandwich-like manner, even low electrical voltages are sufficient to produce violent contractions or elongations in the longitudinal direction, in particular in the region of the natural frequency of the overall arrangement.
  • the piezo element 48 is statically prestressed in its longitudinal direction by a pressure screw 50, and a counter nut 51 secures this screw setting.
  • a housing 52 surrounds the piezo element 48 and statically and dynamically closes the flow of force of all individual components.
  • the bore 30 of the nozzle 2 is made in a sapphire plate 53, which is pressed by a screw 54 into a holder 55 and is fixed there in this way.
  • the choice of the sapphire bore material largely reduces the risk of the needle 31, which is made of a metallic material, from rubbing or welding to the bore wall due to the needle vibration.
  • the holder 55 is part of a wall of the pressure chamber 29 opposite the membrane 47. In this wall there is a through opening into which the sapphire plate 53 is placed against the stop 55. An internal thread of the through hole receives a screw 54 which presses the sapphire plate 53 against the stop 55.
  • the screw 54 has a through channel into which the needle holder 46 projects.
  • the inner contour of the through-channel is adapted to the outer contour of the needle holder 46 such that a small gap remains between them for the highly viscous liquid to pass through.
  • the ring electrode 33 which is located in a mouthpiece 61, is connected to a supply line 56 in order to be able to supply the former with an electrical potential via the supply line 56.
  • FIG. 3 Another embodiment of an electrostatic nozzle according to the invention is shown in FIG.
  • the bore 30 is so small in this embodiment, for example in the final diameter 17 microns that it is not more of the needle 31 can be penetrated in its entire length.
  • the needle 31 therefore only extends to the vicinity of the narrowest bore point.
  • the action of the needle 31 is similar to the action that was described earlier.
  • An oscillating movement of the needle 31 in the direction of the nozzle outlet increases the pressure in the ejection channel 57 both because of the wall thrust forces and because of the displacement effect of the needle end face 32.
  • the corresponding return movement of the needle 31 causes a pressure reduction.
  • the formation of the individual drops takes place in the area of the ring electrode 33, which here too is provided with a suitable supply line for applying an electrostatic potential.
  • the ejection channel 57, in which the needle 31 moves, is obtained by a nozzle body 58 which is made of hard metal or ceramic. This nozzle body 58 is inserted into a bore 59 of the holder 55, the needle holder 46 can still partially protrude into the bore 59.
  • FIGS. 6, 7 and 8 show the overall structure of the nozzle according to FIG. 5.
  • FIG. 6 shows a section through an elevation of the nozzle
  • FIG. 7 shows a cross-section
  • FIG. 8 shows a cross section through the nozzle.
  • the same elements as in FIGS. 3 to 5 are again provided with the same reference symbols and are not described again.
  • a holder 60 presses a mouthpiece 61, into which the deflection electrode 35 is cast, against a nozzle base body 62.
  • the nozzle channel 42 runs through the mouthpiece 61 and is surrounded on the input side by the ring electrode 33. It is also carried by the mouthpiece 61.
  • the oscillating membrane 47 is located between the housing 52 and the nozzle base body 62.
  • the oscillating membrane 47 is clamped between the housing 52 and the nozzle base body 62, wherein it is formed by an approximately 0.5 to 1.0 mm thick steel plate, which because of the Special type of clamping 31 can only perform bending vibrations in an area surrounding the needle. In the protruding area, this membrane 47 is used as a clamping element for a microsieve 63.
  • the relatively large thickness of the membrane causes natural frequencies that are between 200 and 300 kHz.
  • the microscreen 63 is clamped between the membrane 47 and the nozzle base body 62 and prevents particles that are larger than 5 ⁇ m and which are inadvertently carried along with the covering liquid into the one leading to the nozzle Enter the duct system.
  • the membrane 47 guided over the microsieve 63 in the inlet area of the liquid and the ultrasound oscillation introduced into it help to avoid a blockage of the microsieve 63 by interlocking pigments.
  • this is held by a system of very small, finely milled support channels 64.
  • the covering liquid is fed through the supply line 22 to the nozzle 2. This supply line 22 is placed tightly on a clamping piece 66 by means of a union nut 65.
  • an air-water supply line 67 Via an air-water supply line 67, the liquid required for the cleaning and drying of the nozzle 2 or the necessary air is fed to the nozzle 2 if necessary.
  • This line 67 is also pressed with a union nut 68 against a screw-in clamping piece 69.
  • the line 67 leads to a changeover valve 70, which is shown symbolically here and is located at a greater distance from the nozzle 2.
  • the electrostatic nozzles described in FIGS. 3 to 8 are particularly suitable for spraying a highly viscous or viscous covering liquid drop by drop onto the sieve without the length of the nozzle and thus the dimensions of the device for producing stencils having to assume extremely large values.
  • the cover liquid is resistant to abrasion and chemical influences from the printing chemicals.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Coating Apparatus (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Coloring (AREA)
  • Nozzles (AREA)
  • Electrostatic Spraying Apparatus (AREA)

Claims (19)

  1. Buse électrostatique comportant
    - un piézoélément (48) destiné à générer des vibrations mécaniques à haute fréquence,
    - une membrane (47) couplée au piézoélément (48), à laquelle les vibrations mécaniques sont susceptibles d'être transmises, et constituant une paroi d'une chambre de pression (29) servant à recevoir un liquide à projeter et se trouvant en surpression,
    - un canal de projection (30, 57) partant de la chambre de pression (29), pour assurer l'expulsion de projection du liquide hors de la chambre de pression (29), et
    - un poussoir (31), relié à la membrane (47) et s'étendant à travers la chambre de pression (29) et jusqu'au canal de projection (30, 57) et auquel les vibrations sont susceptibles d'être transmises de manière à ce qu'il vibre dans sa direction longitudinale,
       caractérisée en ce que
    - le liquide est susceptible d'être expulsé de façon continue hors du canal de projection (30, 57), et
    - le poussoir (31) excité en vibration dans le canal de projection (30, 57) provoque des perturbations régulières de l'écoulement de liquide dans le canal d'écoulement annulaire qui est constitué par le poussoir (31) et le canal de projection (30, 57).
  2. Buse électrostatique selon la revendication 1, caractérisée en ce que le poussoir (46, 31) est constitué d'un porte-aiguille (46) relié à la membrane (47) et situé à l'intérieur de la chambre de pression (29), porte-aiguille dont la pointe libre porte une aiguille (31) pénétrant dans le canal de projection (30, 57).
  3. Buse électrostatique selon la revendication 2, caractérisée en ce que le porte-aiguille (46) est réalisé en forme de corne et en s'effilant dans la direction du canal de projection (30, 57).
  4. Buse électrostatique selon la revendication 3, caractérisée en ce que le porte-aiguille (46) va en s'effilant de façon étagée.
  5. Buse électrostatique selon la revendication 3, caractérisée en ce que l'effilement du porte-aiguille (46) est d'allure exponentielle.
  6. Buse électrostatique selon l'une des revendications 2 à 5, caractérisée en ce que le canal de projection (30, 57) est réalisé du côté de l'entrée avec une forme cylindrique creuse ainsi que dans la direction de la sortie avec un diamètre intérieur allant en diminuant de façon constante et l'aiguille (31) ne venant se placer que dans sa partie cylindrique creuse.
  7. Buse électrostatique selon l'une des revendications 1 à 6, caractérisée en ce que le canal de projection (30, 57) se trouve dans un corps (53, 58) pouvant être inséré dans la buse.
  8. Buse électrostatique selon la revendication 7, caractérisée en ce que le corps (53) est réalisé en forme de plaquette.
  9. Buse électrostatique selon la revendication 7, caractérisée en ce que le corps (58) est de configuration tubulaire.
  10. Buse électrostatique selon la revendication 7, 8 ou 9, caractérisée en ce que le corps est réalisé en saphir, en métal dur ou en céramique.
  11. Buse électrostatique selon l'une des revendications 7 à 10, caractérisée en ce que le corps (53, 58) est maintenu dans une paroi (55, 62), placée à l'opposé de la membrane (57) de la chambre de pression (29).
  12. Buse électrostatique selon la revendication 8 et 11, caractérisée en ce que le corps (53) est inséré dans un évidement du côté intérieur de la paroi (55, 62) et est maintenu au moyen d'une vis (54) cylindrique, creuse et vissée dans l'évidement.
  13. Buse électrostatique selon la revendication 12, caractérisée en ce que le contour intérieur de la vis (54) cylindrique creuse est adapté au contour extérieur du porte-aiguille (46).
  14. Buse électrostatique selon la revendication 11, 12 ou 13, caractérisée en ce que des canaux (40), ouverts vers le côté sortie du canal de projection (30, 57), sont réalisés dans la paroi (55).
  15. Buse électrostatique selon l'une des revendications 11 à 14, caractérisée en ce que le canal de projection (30) débouche dans une ouverture (44) de la paroi (55), allant en s'évasant sous une forme conique dans la direction de projection, .
  16. Buse électrostatique selon l'une des revendications 1 à 15, caractérisée en ce que le piézoélément (48) est couplé à la membrane (47) par l'intermédiaire d'une pièce de pressage (49) allant en s'effilant dans la direction de la membrane (47).
  17. Buse électrostatique selon l'une des revendications 2 à 16, caractérisée en ce que l'aiguille (31) est réalisée sous forme de tige cylindrique.
  18. Buse électrostatique selon l'une des revendications 1 à 17, caractérisée en ce que le canal de projection (30) se prolonge par un canal de buse (42) présentant du côté de l'entrée une électrode annulaire (33) placée coaxialement par rapport au canal de projection (30).
  19. Buse électrostatique selon la revendication 18, caractérisée en ce que le canal de buse (42) est réalisé dans une pièce d'embouchure (61), pouvant être reliée à la paroi (55, 60) et dans laquelle une électrode de déviation (35) est intégrée du côté de la sortie par rapport au canal de buse (42).
EP92116182A 1992-09-22 1992-09-22 Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité Expired - Lifetime EP0590165B1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
ES92116182T ES2099187T3 (es) 1992-09-22 1992-09-22 Tobera electroestatica, especialmente para la eyeccion de liquidos de alta viscosidad.
AT92116182T ATE149102T1 (de) 1992-09-22 1992-09-22 Elektrostatikdüse, insbesondere zum ausspritzen hochviskoser flüssigkeiten
DE59208075T DE59208075D1 (de) 1992-09-22 1992-09-22 Elektrostatikdüse, insbesondere zum Ausspritzen hochviskoser Flüssigkeiten
EP92116182A EP0590165B1 (fr) 1992-09-22 1992-09-22 Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP92116182A EP0590165B1 (fr) 1992-09-22 1992-09-22 Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité

Publications (2)

Publication Number Publication Date
EP0590165A1 EP0590165A1 (fr) 1994-04-06
EP0590165B1 true EP0590165B1 (fr) 1997-02-26

Family

ID=8210034

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92116182A Expired - Lifetime EP0590165B1 (fr) 1992-09-22 1992-09-22 Buse électrostatique, en particulier pour injecter des matériaux fluides à haute viscosité

Country Status (4)

Country Link
EP (1) EP0590165B1 (fr)
AT (1) ATE149102T1 (fr)
DE (1) DE59208075D1 (fr)
ES (1) ES2099187T3 (fr)

Cited By (2)

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US11839487B2 (en) 2010-07-15 2023-12-12 Eyenovia, Inc. Ophthalmic drug delivery
US11938056B2 (en) 2017-06-10 2024-03-26 Eyenovia, Inc. Methods and devices for handling a fluid and delivering the fluid to the eye

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9405952D0 (en) * 1994-03-25 1994-05-11 Zeneca Ltd Aqueous ophthalmic sprays
SE503540C2 (sv) * 1995-02-15 1996-07-01 Svecia Screen Printing Systems Sätt och anordning för att framställa en stencil
US6135357A (en) * 1998-11-23 2000-10-24 General Electric Company Apparatus for atomizing high-viscosity fluids
EP1498262A1 (fr) * 2003-07-15 2005-01-19 Kesper Druckwalzen GmbH Méthode et appareil pour la fabrication d'un pochoir sérigraphique et un écran avec un pochoir
JP5964826B2 (ja) 2010-07-15 2016-08-03 アイノビア，インコーポレイティド 滴生成デバイス
CN103124541B (zh) 2010-07-15 2015-09-30 艾诺维亚股份有限公司 眼药物递送
CA2805635A1 (fr) 2010-07-15 2012-01-19 Corinthian Ophthalmic, Inc. Procede et systeme de realisation d'un traitement et d'une surveillance a distance
US20130150812A1 (en) 2011-12-12 2013-06-13 Corinthian Ophthalmic, Inc. High modulus polymeric ejector mechanism, ejector device, and methods of use

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL250925A (fr) * 1959-05-12
DE2724931A1 (de) * 1976-06-21 1977-12-29 Lonza Ag Vorrichtung zum verspruehen von dispersen systemen
ES485764A1 (es) * 1978-11-15 1980-10-01 Thomae Gmbh Dr K Procedimiento para el recubrimiento de utiles de moldeo pa- ra la fabricacion de cuerpos moldeados.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11839487B2 (en) 2010-07-15 2023-12-12 Eyenovia, Inc. Ophthalmic drug delivery
US11938056B2 (en) 2017-06-10 2024-03-26 Eyenovia, Inc. Methods and devices for handling a fluid and delivering the fluid to the eye

Also Published As

Publication number Publication date
ES2099187T3 (es) 1997-05-16
ATE149102T1 (de) 1997-03-15
EP0590165A1 (fr) 1994-04-06
DE59208075D1 (de) 1997-04-03

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