RU2110409C1 - Drop forming device - Google Patents

Abstract

FIELD: drop forming of fusible powdered, solid or high-viscosity material, for instance of paints. SUBSTANCE: drop forming is realized by decreasing the material viscosity to viscosity at which drop forming becomes possible. Paint of a decreased viscosity is fed to the area of ejection, constant or impulse electric potential is applied to the area of ejection for setting up an electric field in this area, ejection of drops from the area of ejection is accomplished by means of electric means. Alternatively constant electric potential may be applied for setting up a static electric field in the area of ejection and accomplishing an impulse heating of the area of ejection. EFFECT: enhanced efficiency. 15 cl, 3 dwg

Description

 The invention relates to devices for forming droplets of material from a solid, powdery or highly viscous fusible material.

 One of the applications of the present invention can be the transfer of droplets of a material with high coloring ability to the surface of a recording medium for contactless printing, however, the invention is not limited to the delivery of coloring materials for contactless printing, but can also be used to form droplets as such or to be applied onto a substrate other materials in accordance with a given pattern.

 Examples of other applications are the application of phosphors (fluorescent or phosphorescent) to protect documents, hot molten adhesives and aerosols without using a propellant. The invention can also be used to obtain and eject pharmaceutical preparations in the form of particles in a fusible carrier suitable for a pharmacy, without the use of a propellant.

 Despite the fact that the invention will be described in connection with its use in print, its scope is much wider.

 There are a large number of different devices used in contactless printing systems, which are commonly called inkjet printers. Typically, the ink passes through the nozzle, with the nozzle output diameter being the main factor determining the size of the droplets and therefore the points on the surface of the recording medium. Drops from the nozzle can flow continuously — in this case, the method is called the continuous printing method, or they can be formed individually as needed — in this case, the method is called the interrupted printing method. In continuous printing, ink flows through the nozzle at high pressure, and this pressure in the nozzle is modulated at a substantially constant frequency, resulting in droplets of a constant size. If the droplets are informed of the charge and an electric field external to the nozzle is applied, then, when moving to the recording surface in its path, the selected droplets can be rejected in response to the signal that creates the electric field, thus forming a pattern on the surface in accordance with the control signal. With interrupted printing in a liquid, in the immediate vicinity of a small nozzle, local pressure pulses are generated, as a result of which droplets of liquid can be ejected from the nozzle at predetermined times.

 With any inkjet printing method, the coloring material is a soluble dye in a liquid carrier with binders in order to make the printed image more durable.

 The disadvantage of soluble dyes is that the density of the printed image is not high enough for many applications, and the dye fades under the influence of the environment.

 Another disadvantage of soluble dye is the dependence of the quality of the printed image on the surface properties of the recording medium.

 It is known that pigment-containing paints provide a higher image density than soluble dyes and are more durable. Pigments can also be used in inkjet printers in conjunction with a liquid medium, but to create high density images, it is necessary that the concentration of pigment in the liquid medium is high. High pigment concentration leads to the destruction of droplets in continuous printers, which results in less uniform printing. In interrupted printers, there is no constant high pressure, and droplet formation is highly dependent on local conditions in the nozzle, so the presence of pigments can change these conditions or clog the nozzle so that proper droplet formation is impaired.

 Another process known as ink jet printing with electrostatic inks is characterized by electrostatic attraction of a liquid and is described, for example, in US Pat. No. 3,060,429. This process involves the formation of charged droplets from a nozzle containing liquid and accelerating them toward the electrode in the form of a plate in the form of a high voltage applied between the nozzle and the plate. This process is optimized by introducing a valve electrode, which is used to interrupt the jet or control the jet, as well as two pairs of electrodes used to control the path of the droplets. Printing is done by placing a paper substrate directly in front of the electrode in the form of a plate and using a conductive ink solution.

 It was proposed, for example, in US Pat. No. 3653932 to use a paint that is in solid form at room temperature, but to melt it in a heating vessel before being fed into the nozzle before it flies through the gap to the substrate under high voltage. This system and device has the disadvantage of the excessive complexity of supplying the potential difference between the nozzle and the valve electrode, as well as between the valve electrode and the plate containing the substrate on which to print. A similar device is described in an article published in IS & T's Eighth International Congress on Advances in Non-Impact Printing Technologies, (1992), p. 334 - 339.

 The purpose of the invention is to provide a device for forming droplets from fusible powder, solid or highly viscous materials, for example paints, in which droplets are not formed by a nozzle and, therefore, the size of the droplets does not depend on the size of the nozzle.

 Another objective of the invention is to provide a device for forming droplets from fusible powdery, solid or highly viscous materials, for example, paints, with a high concentration of pigment or other solid materials, which allows you to get a high brightness image on the surface of the recording medium or to obtain drops containing a relatively large amount solid material.

 Another objective of the invention is to provide a device for forming droplets of fusible powder, solid or highly viscous materials, such as paints, including a carrier or using a carrier, which may be non-conductive.

 In accordance with one embodiment of the invention, there is provided a device for forming droplets of material from a fusible solid, powdery or highly viscous material, comprising means for reducing the viscosity of a solid, powdery or highly viscous material to a viscosity at which droplets may form, means for supplying material with a reduced viscosity to the ejection point and means for supplying electric potential to the ejection point to create an electric field at this point, as a result of which it is possible the formation and ejection of droplets of material from the ejection point.

 In accordance with another embodiment of the invention, there is provided a device for forming droplets of material from a fusible powder, solid or highly viscous material containing a solid body of particles and a fusible carrier, the device comprising means for reducing the viscosity of the material to a viscosity at which droplets may form, means for supplying material with reduced viscosity to the ejection point and means for supplying electric potential to the ejection point to create an electrostatic field at this point , Whereby it is possible the formation and ejection of droplets of the material from the ejection point by electrostatic repulsion.

 A powdery, hard or highly viscous material can be a paint containing a coloring matter and a carrier. The coloring matter may be a pigment.

 It is obvious that in these embodiments of the invention, the size of the droplets of the material, for example, paint, does not depend on the size of any nozzle that delivers a material with a reduced viscosity to the ejection point, but depends on the geometry of the ejection point, the magnitude of the electric field, the amount of heat at the ejection point and the nature of the material with a reduced viscosity, such as paint, and its viscosity at the time of ejection.

 It is also obvious that the difference of the present invention from known devices is that a material with a reduced viscosity, such as paint, does not necessarily contain an electrically conductive liquid as a carrier at the time of droplet formation. It turns out that droplets are formed by electrostatic agents acting on particles of a solid, such as pigment, in a material with a reduced viscosity, for example in paint. The liquid component acts only as a carrier. The transfer of pigment instead of the transfer of liquid solutions of the coloring matter leads to the fact that a brighter image can be obtained on the substrate, and smaller dots can be obtained faster.

 The paint may consist of paraffin or a low melting point resin mixed with pigment. Examples of such materials are AC6, polyethylene paraffin manufactured by Allied Sinal, Elvax 210, ethylene vinyl acetate resin manufactured by Du Pont, Synta Wax, hydrogenated castor oil manufactured by Lever and Kitchen; paraffin manufactured by Exxon and mixtures thereof. The pigment can be selected from any pigment, depending on the desired color. Examples of pigments are organic pigments such as Irgalite Blue LGLD; Pigment Blue 15: 3, manufactured by Ciba Geigy; Microlith Black CT, Black Pigment 7, manufactured by Ciba Geigy, Monolite Yellow GNA, Yellow Pigment 1, manufactured by ICI, or inorganic pigments such as silicas, metal particles or magnetic iron oxides.

 The viscosity of the paint can be changed by adding a viscosity adjusting agent such as Energol WM2, paraffin oil sold by BP Chemicals, or the like.

 Means for reducing the viscosity of a powdered, solid or highly viscous material can be made with the possibility of reducing the viscosity by heating or creating pressure.

 The implementation of the means of supplying material with reduced viscosity to the ejection point depends on the nature of the material.

 In the case of a solid fusible material, these means of supply contain a spring chamber adapted to place granules or a rod of material in it, and means for reducing viscosity include means of resistive or induction heating to melt the granules or rod of material to achieve the desired viscosity.

 Alternatively, the means for reducing viscosity may include a two-stage heater, the first stage being used to soften the material until a viscosity is achieved so that it can be moved to the second stage heater, which is designed to reduce the viscosity to the desired final viscosity, the desired final viscosity.

 For some paints, it was found that if they are placed in a vertically closed container, then two-stage heating together with the force of gravity and / or thermal expansion of the material facilitates both a decrease in viscosity and the supply of material to the ejection point.

 These heaters can be resistive or induction type.

 The resistive type heater may be a resistive wire wound around a material tank.

 The induction type heater consists of a coil wound around a ferrite core located next to the paint container. Alternatively, a coil can be wound around the container, said container acting as a core, directly heating the paint. In addition, heating of the ejection point may be provided to maintain the desired viscosity of the ink.

 According to one embodiment of the invention, the ejection point includes heating means to maintain such a viscosity of the material that droplets are possible.

 According to another embodiment of the invention, the heating means at the ejection point comprise an infrared solid-state laser diode.

 Such heating means can be characterized by specific properties, for example, a short switching time, a suitable output of thermal radiation relative to the wavelength, frequency band and heating power used to melt the material, and a suitable size of the light spot in relation to the size of the ejection point.

 In this case, it is advisable that the infrared solid-state laser diode was configured to operate in a pulsed mode to provide intermittent heating of the ejection point.

 The electric potential creates an electric field at the ejection point, which may depend on the geometry of the ejection point, for example, its radius of curvature. In a preferred embodiment, the ejection point can be formed by a needle, the radius of curvature of which at the end lies in the range of 5-50 microns. Alternatively, the ejection point may be formed by an extended pointed edge having a semi-cylindrical surface with a radius of curvature of 5-50 μm, or a matrix of ejection points.

 Using the device according to the invention, it is possible to obtain droplets from a material, such as paint, ranging in size from 1 to 500 microns in diameter or even more, depending on the geometry of the ejection point, viscosity, the type of carrier included in the material, and the applied voltage.

 The electric potential applied to the ejection point can lie in the range 500 - 5000 B.

 According to one embodiment of the invention, means for supplying electric potential to an ejection point include means for impulse feeding of electric potential so that droplets are periodically formed and ejected from the ejection point.

 According to another embodiment of the invention, the electric potential supplied to the ejection point includes a constant threshold voltage in the range from 500 to 5000 V and a pulse voltage of up to 800 V.

 In this case, it is advisable that the pulse voltage has a rectangular shape.

 The device may further comprise means for intermittently heating the ejection point to reduce the viscosity of the paint at this point, as a result of which it is possible to periodically form and eject drops from the ejection point.

 In this case, the means of intermittent heating of the ejection point to reduce the viscosity of the paint at this point can be a solid-state laser diode infrared range.

 It is generally seen that the invention provides droplet formation at the ejection point and electrostatic ejection of these droplets.

 Although the mechanism of the droplets is not fully understood, one of the theories with which there is no need to associate the applicants is as follows. Particles of material with reduced viscosity moving to the ejection point have an inherent charge or acquire a charge of the same polarity as the ejection point. More and more particles accumulate from the carrier fluid at the ejection point, within the droplet, and with increasing repulsion, the particles tend to move from the ejection point until the electrostatic repulsion between the ejection point and the forming droplet with charged particles reaches such a value that the surface tension forces in the carrier fluid cease to hold the droplets at the ejection point. At this stage, the drop is repelled by electrostatic means.

 It should be specially noted that since the repulsion is essentially electrostatic, in order to attract droplets to the substrate, a grounded substrate is not required and, in fact, a drop can fly a long distance before it reaches the substrate. This allows the use of suitable electrostatic or other deflection means to produce the desired pattern on the substrate.

 The device may include a pair of ejection points, each of which creates drops of one of the components of two-component glue.

 In this way, an adhesive dispenser can be created.

 In FIG. 1 shows a sectional view of a droplet forming apparatus according to one embodiment of the invention; in FIG. 2 is a sectional view of a device for forming drops according to another embodiment; in FIG. 3 is a sectional view of a droplet forming apparatus according to another embodiment of the invention.

 In FIG. 1 shows an embodiment of a device for forming droplets of paint.

 A device for forming discrete drops of solid paint consists of a housing 1, which tapers in one direction and can be made of electrically insulating material. A hollow tube 2 of electrically conductive and heat-conducting material protrudes from the housing, which is electrically charged through an electric conductor 3 from an external source 4. The ejection point 6 is formed by the end of the tube 2 and has a predetermined radius of curvature, in this case it is a spherical point. In the housing there is a channel 7, leading to the tube 2. Channel 7 has a first section 8 of the first diameter for receiving the rod 9 of hard paint. A heating coil 10, placed around the first portion 8, heats the paint rod 9 to soften it to such a state that the spring 11 can squeeze the paint through the tapering portion 12 of the channel 7 into a second portion 13 of smaller diameter. An additional heating coil 14, located in this second section 13, additionally heats the paint for its further melting until its viscosity becomes such that it can flow to the ejection point under the pressure of the spring 11 and form droplets. At the ejection point, droplets form under the action of an electrostatic charge, as described above.

 In FIG. 2 shows another embodiment of a device for forming drops of hard paint. Identical elements in FIG. 1 and 2 have the same position.

 The housing 1 tapers in one direction and can be made of electrically insulating material. A hollow tube 2 of electrically conductive and heat-conducting material protrudes from the housing, which is electrically charged through the conductor 3 from an external source 4. The ejection point 6 is formed by the end of the tube 2, tapering to a point having a given radius of curvature, in this case a spherical point. In the housing there is a channel 7 that goes to the tube 2 and the ejection point 6. Channel 7 is used to receive the rod 9 of hard paint. The heating coil 10, placed around the channel 7, softens and expands the core 9 of hard paint, while the paint with the required viscosity at which droplets can form is pushed out of the channel 7 into the tube 2 and flows under pressure to the ejection point 6. At the ejection point, droplet formation occurs under the influence of an electrostatic charge, as described above. The plug 15 closes the end of the channel 7, remote from the tube 2, to ensure the pressure resulting from the expansion during melting of the fusible paint, for directing it to the ejection point 6.

 In FIG. 3 shows yet another embodiment of a device for forming drops of hard paint. In FIG. 3 and 1, the same elements are denoted by the same positions.

 The housing 1 tapers in one direction and can be made of electrically insulating material. A hollow tube 2 of electrically conductive and heat-conducting material protrudes from the housing, which is charged electrically from an external source 4 through the conductor 3. The ejection point 6 is formed by the end of the tube 2, which tapers to a point at the end having a given radius of curvature, in this case a spherical point. In the housing there is a channel 7, leading to the tube 2. Channel 7 has a first section 8 of the first diameter for receiving the rod 9 of hard paint. A heating coil 10, placed around the first portion 8, heats the solid paint rod 9 to soften to such a state that the spring 11 can extrude the paint through the tapering portion 12 of the channel 7 into a second portion 13 of smaller diameter. Additional heating by an infrared solid-state laser 16 is provided through an optical fiber 17 connected to the tube 2. This provides the heat necessary to further melt the ink until it reaches a viscosity at which it can flow to the ejection point and form droplets. At the ejection point, when the viscosity of the ink decreases due to heat transferred through the optical fiber 17 from the infrared solid-state laser 16, droplets are formed by the electrostatic charge, as described above. This heating can be pulsed to provide predetermined or interrupted formation and ejection of droplets.

 Drop formation according to the present invention is described in examples 1-6 below.

In these examples, the paint is made from a mixture of 99 g of Syntha Wax (hydrogenated castor oil) and 1 g of Pigment Blue 15, which were placed in a friction mill and heated to 150 ^° C to melt these thermoplastic materials. After grinding for 6 hours, the molten paint was removed from the mill and hardened upon cooling.

 The viscosity of this paint at operating temperature, necessary for the formation of droplets, was 10 MPa • s.

Example 1. The specified paint was placed in the device made according to FIG. 1, and at a distance of 20 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 600 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 1500 V. The size of the printed dot formed by the drop was 10 μm with excellent optical density of the ink and integrity.

Example 2. The specified paint was placed in the device made according to FIG. 1, and at a distance of 20 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The size of the printed dot formed by the drop was 20 μm with excellent optical density of the ink and integrity.

Example 3. The specified paint was placed in the device made according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 600 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 1500 V. The size of the printed dot formed by the droplet was 70 μm with excellent optical density of the ink and integrity.

Example 4. The specified paint was placed in the device made according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The size of the printed dot formed by the drop was 150 μm with excellent optical density of the ink and integrity.

Example 5. The specified paint was placed in the device made according to FIG. 1, and at a distance of 5 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 600 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 1500 V. The size of the printed dot formed by the drop was 150 μm with excellent optical density of the ink and integrity.

Example 6. The specified paint was placed in the device made according to FIG. 1, and at a distance of 5 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The size of the printed dot formed by the drop was 300 μm with excellent optical density of the ink and integrity.

 Examples 7 to 13 illustrate the formation of droplets according to the method and apparatus described in this invention, using other inks. These paints were prepared according to the method described in the previous examples. All viscosity measurements in these examples were performed on a Haak Rheomenter: Rheostress RS100 instrument.

 Example 7

Paraffin wax - 43 g
AC-6 - 43 g
Irgalite Blue LGLD - 4 g
The viscosity of this paint at operating temperature was 45 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 145 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by the droplets had excellent optical density and integrity.

 Example 8

Paraffin wax - 80 g
Elvax 210 - 9 g
Irgalite Blue LGLD - 4 g
The viscosity of this paint at a working temperature of 32 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by the droplets had excellent optical density and integrity.

 Example 9

Paraffin wax - 80 g
Elvax 210 - 9 g
Energol WM2 - 20 g
Irgalite Blue LGLD - 4 g
The viscosity of this paint at operating temperature was 15 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by the droplets had excellent optical density and integrity.

 Example 10

Paraffin wax - 49 g
AC-6 - 49 g
Irgalite Blue LGLD - 1 g
The viscosity of this paint at operating temperature was 31 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. The ejection point was at 135 ^° C., and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by droplets had excellent optical density of the ink.

 Example 11

Paraffin wax - 99 g
Microlith Black CT - 1 g
The viscosity of this paint at operating temperature was 2.5 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. The ejection point was at 135 ^° C, and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by the droplets had poor optical density and integrity.

 Example 12

Paraffin wax - 99 g
Monolite Yellow GNA - 1 g
The viscosity of this paint at operating temperature was 13 MPa • s.

The paint was placed in the device according to FIG. 1, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. The ejection point was at 135 ^° C., and 800 V pulses with a frequency of 5000 Hz were superimposed on a threshold voltage of 2000 V. The printed dots formed by the droplets had poor optical density and integrity.

 Example 13

Paraffin wax - 43 g
AC-6 - 43 g
Irgalite Blue LGLD - 4 g
The viscosity of this paint at operating temperature was 45 MPa • s.

The paint was placed in the device according to FIG. 3, and at a distance of 10 mm from a single ejection point with a radius of curvature of 25 μm, document paper was placed. In this case, excellent results were obtained when the ejection point was at 135 ^o C, and the laser was modulated at a frequency of 5000 Hz. A voltage of 2800 V was applied to the ejection point. The printed dots formed by the droplets had excellent ink optical density and integrity.

 Thus, the present invention provides a simple method and device by which droplets can be formed from a fusible solid, powdery or highly viscous material, for example, paint.

Claims (15)

 1. A device for forming droplets of material from a fusible solid powdery or highly viscous material, comprising means for reducing the viscosity of a solid, powdery or highly viscous material to a viscosity at which droplets are possible, means for supplying material with reduced viscosity to the ejection point and means for supplying electric potential to the point ejection to create an electric field at this point, as a result of which it is possible to form and eject material drops from the ejection point ui.  2. A device for forming droplets of material from a fusible powdery solid or highly viscous material containing a solid body consisting of particles and a fusible carrier, the device comprising means for reducing the viscosity of the material to a viscosity at which droplets may form, means for supplying material with a reduced viscosity to the ejection point and means for supplying electric potential to the ejection point to create an electric field at this point, as a result of which it is possible to form ktsii material droplets from the ejection point by electrostatic repulsion.  3. The device according to claim 2, in which the means of reducing the viscosity of the powdered, solid or highly viscous material is made with the possibility of reducing the viscosity by heating or creating pressure.  4. The device according to claim 2, in which the means of supplying material with reduced viscosity to the ejection point contain a spring chamber adapted to place granules or a rod of material in it, and means for reducing viscosity include means of resistive or inductive heating for melting the granules or rod from the material until the desired viscosity is achieved.  5. The device according to claim 4, in which the means of reducing the viscosity include a two-stage heater, the first stage being used to soften the material until such a viscosity is achieved that it can be moved to the second stage heater, which is designed to reduce the viscosity of the material to the desired final viscosity.  6. The device according to claim 2, in which the ejection point includes heating means to maintain such a viscosity of the material at which droplets are possible.  7. The device according to claim 6, in which the heating means at the ejection point contain a solid-state infrared laser diode.  8. The device according to claim 7, in which the infrared solid-state laser diode is configured to operate in a pulsed mode to provide intermittent heating of the ejection point.  9. The device according to claim 2, in which the ejection point is a needle tip with a radius of curvature of 5 to 50 μm or an extended edge having a semi-cylindrical surface with a radius of curvature of 5 to 50 μm, or a matrix of ejection points.  10. The device according to claim 2, in which the electric potential supplied to the ejection point lies in the range of 500-5000 V.  11. The device according to claim 2, in which the means for supplying the electric potential to the ejection point includes means for impulse supply of the electric potential so that periodic formation and ejection of droplets from the ejection point is carried out.  12. The device according to claim 2, in which the electric potential supplied to the ejection point includes a constant threshold voltage in the range of 500 - 5000 V and a pulse voltage of up to +800 V.  13. The device according to claim 2, in which the pulse voltage has a rectangular shape.  14. The device according to claim 1, additionally containing intermittent heating means of the ejection point to reduce the viscosity of the paint at this point, as a result of which it is possible to periodically form and eject drops from the ejection point.  15. The device according to 14, in which the means of intermittent heating of the ejection point to reduce the viscosity of the ink at this point is a solid-state infrared laser diode.

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