SU1278250A1 - Method of registering flying drops in device of electrodropjet manufacturing engineering - Google Patents

Abstract

The invention relates to electron-ion technology, computing and printing and can be used in the development of devices that carry out the output of information from computers and duplicating equipment. The aim of the invention is to increase the reliability of droplet registration. This is achieved by the fact that with the method of registering flying droplets in devices of electric droplet-jet technology based on passing droplets through a discharge gap in which corona discharges occur, as recorded, for example, by optical means, when flying droplets through the discharge gap, excite their self-oscillations, like, an electromagnetic field. With S, due to the occurrence of ellipse drops in the discharge gap of the SL, the conditions for the occurrence of a corona discharge are facilitated. 5 il.

Description

one

The invention relates to electron-ion technology, supervisory technique and printing and can be used in the development of devices that carry out the output of information from computers and duplicating equipment.

The purpose of the invention is to increase the reliability of registration of droplets.

In Fig.1, a, b, c, d, d are represented on a diagram of a device implementing this method and distribution of intensity; 2 shows micrographs illustrating the occurrence of self-oscillations of a drop in flight, as well as oscillograms of corona pulses; 3-5, experimental results.

FIG. 1 a, b shows a diagram of a device implementing the registration method. To the main needle electrodes 1 or plane-parallel plates 2, a high voltage is connected from a low-power source of power to the ear. The trajectory of droplets 3 passes through the zone 4-6 of the registration of droplets - the poles of the droplet.

The device works as follows.

In the droplet registration zone 4, in the absence of droplets, the electric field intensity along the central power line (along the axis of symmetry of the electrodes) is distributed as shown in Fig. 1 for the needles 1 and in Fig. 1e for the plates 2 as dashed lines. The parameters of the electrodes (interelectic distance h, needle sharpening angle h), needle radius r, voltage TJ) are chosen so that in the initial state the maximum strength E f in a sharply inhomogeneous field of needles or the strength of a uniform field

plates E

DZ "less than the initial intensity of copying E, from the top

of the electrodes 1, plates 2. At the moment of entry into the registration zone of an uncharged conductive or dielectric drop 3, the field strength at the poles of drop 3 abruptly increases by about three times compared with the initial value, which is due to the redistribution of charges in the external field on the surface of the drop and reaches the level E. If for strayed

drops required amount of initial

the coronary intensity of E is less than E

GLO.H,

then from the poles drop 3

1PHYPOHOUSE short pulse

ten

20

 , - j - 25

2782502

corona discharge in the direction of electrodes 1 or plates

Fig. 1d shows experimentally removed oscillograms of corona pulses. Corona discharge can also be detected by photoelectric luminescence. The moment of occurrence of the corona pulse t corresponds to the moment of the entry of a drop 3 into the zone 4 of the registration of droplets, and the duration of the pulse t can serve as an indicator of the speed of flight of the drop.

Figure 2 shows micrographs illustrating the occurrence of auto-oscillations of a droplet in flight when droplets are emitted by a strong electrostatic field (nozzle diameter 0.45 mm, fluid pressure P 3.7 kPa, emission voltage U 3.9 kV, mm, aqueous ink) as well as experimental oscillograms of corona pulses (frequency f 768 Hz, V, R 440 kΩ, oscilloscope C1-16.

If, however, charged drops along the trajectory fly, then the occurrence of a corona discharge is facilitated and the amplitude of the corona pulse will be an indicator of the charge of the droplets. The corona discharge conditions can also be alleviated by causing the droplet in flight to oscillate with respect to the spherical equilibrium position (Fig. 1a, dashed droplets). To do this, the droplet can be affected at the time of its formation or at any point of flight, for example, a periodic electromagnetic field or mechanical action. If the droplet in the registration zone has the shape of an ellipsoid with a major axis in the direction of the force lines, then its curvature increases significantly and a corona discharge pulse will require less stress. To select the relative position of the point of initial disturbance of a drop, it is necessary to use the relation for the frequency of natural oscillations of a drop:

f l, 27W / (pd;

55

gdes4, | - coefficient of surface tension and fluid density; d ,, is the diameter of the drop.

ts

Figure 3 illustrates the ability of a drop to amplify, for example, a single-field electric field at its poles. The field gain is the reciprocal of the depolarization factor 36. As can be seen, the spherical droplet enhances the initial electric field three times, the ellipsoid stretched along the lines of force with the ratio of semi-axes in / 0.5 and strengthens the field by about 6 times, in / a 0.25 - 12.5 times, w / a 0.1 - 28 times. A spherical drop in the registration zone can be given the desired shape of an ellipsoid drawn along field lines by perturbing it either at the point of formation of the droplet or in flight, or in the registration zone by various force factors (electric field, mechanically, pneumatically, etc.). .).

Figure 4 shows the found distribution of the electric field intensity for hyperbolic needle-shaped electrodes along the axis of symmetry JC, depending on the angle of conicity i-p) at the interelectrode distance of mm and kV. In order to increase the initial intensity at the point of entry of drop 3, it is necessary to reduce the interelectrode distance h, increase the angle H and the voltage and. In this case, in the case of flat electrodes, the decrease in the interelectrode distances h is limited to h 10 d, in order not to increase the aero Dynamic resistance of years w; it drops in the registration zone. From this point of view, the use of needle electrodes is preferable, since the needles create a smaller aerodynamic interaction with protrayushchimi drops, i.e. you can decrease h and U while saving E.

As can be seen from Fig. 4, in the gap between the needles, the electric field has areas of a sharply inhomogeneous and quasi-uniform electric field. When a droplet enters a quasi-homogeneous section, the effect on the moment of registration of the misalignment of the trajectory is almost eliminated, and it is easier to create a sharply non-uniform section.

corona discharge. Since the angle of sharpening of the needles H 80 ° sharply decreases the heterogeneity and the probability of coronation from the needles, the initial intensity in the gap decreases and the sensitivity to the mixing of the trajectory of the drops decreases.

j y 15 20 25

thirty

0

50

five

When a droplet enters a sharply inhomogeneous field, such as needles, wires, etc., if you select a certain ratio of the radii of curvature of the droplet and electrodes, you can create conditions for coronaging not from the droplet, but from the electrodes (unipolar corona discharge) or get simultaneous corona discharges both from the drop and from the electrode (bipolar corona). With the bipolar corona, it is possible to obtain a large amplitude of pulses and increase the response speed (steeper fronts).

Figure 5 presents the theoretically found and experimentally confirmed values of the initial coronation strength E for spherical and ellipsoidal drops (negative pole), as well as for needle-shaped electrodes in the form of rotation hyperboloids and concentric cylindrical electrodes for different radii of curvature. Corona corona depends significantly on the radius of the drop (at the poles). The maximum intensity of a uniform electric field between the plates is limited by the condition of a sample of kV / cm. When passing through the registration zone of a spherical droplet, the intensity at its poles will increase by 3 times and reach 90 kV / cm. This is sufficient only to obtain a pulsed corona discharge from droplets with a diameter d of 1 mm. In order to ignite the corona discharge from droplets of smaller diameter, they must be stretched into an ellipsoid. In this case, in a uniform electric field at the poles of an ellipsoid drop, you can get at, 5; 0.25; 0.1. Corresponding values of strains E, 180; 360; 840 kV / cm. As can be seen from FIG. 5, such a strength is sufficient to create a corona pulse with any elliptical drop and register it.

Claims (2)

The invention relates to electron-ion technology, supervisory technique and printing and can be used in the development of devices that carry out the output of information from computers and duplicating equipment. The purpose of the invention is to increase the reliability of registration of droplets. In Fig.1, a, b, c, d, d are represented on a diagram of a device implementing this method and distribution of intensity; 2 shows micrographs illustrating the occurrence of self-oscillations of a drop in flight, as well as oscillograms of corona pulses; 3-5 are experimental results. FIG. 1 a, b shows a diagram of a device implementing the registration method. To the main needle electrodes 1 or plane-parallel plates 2, a high voltage is connected from a low-power pitahush source. The trajectory of the droplets 3 passes through the zone 4-6 of the registration of the droplet pole drops. The device works as follows. In the droplet registration zone 4, in the absence of droplets, the electric field strength along the central power line (along the axis of symmetry of the electrodes) is distributed as shown in Fig. 1 in the needles 1 and in Fig. 3d for the plates 2 in the form of dashed lines. The parameters of the electrodes (interelectic distance h, needle sharpening angle h), needle radius r, voltage TJ) are chosen so that in the initial state the maximum stress E f in a sharply inhomogeneous field of needles or the strength of a uniform field of the plate is E dZ " less than the initial strength of the copying E, from the surfaces of the electrodes 1, plates 2. B The moment of entry into the registration zone of an uncharged conductive or dielectric drop 3 The field strength at the poles of drop 3 increases abruptly by about three times compared with the initial value, which is associated with the redistribution of charges in the external field over the surface. drops and reaches E level. If for the droplet that has flown in it is necessary the magnitude of the initial coronation strength E is less than the poles of the droplet 3 times more than E 1FOZOIDOUT short-term pulses 1 02 corona discharges in the direction of the electrodes 1 or plates. Corona discharge can also be detected by photoelectric luminescence. The moment of occurrence of the corona pulse t corresponds to the moment of the entry of a drop 3 into the zone 4 of the registration of droplets, and the duration of the pulse t can serve as an indicator of the speed of flight of the drop. Figure 2 shows micrographs illustrating the occurrence of auto-oscillations of a droplet in flight when droplets are emitted by a strong electrostatic field (nozzle diameter 0.45 mm, fluid pressure P 3.7 kPa, emission voltage U 3.9 kV, mm, aqueous ink) as well as experimental oscillograms of corona pulses (frequency f 768 Hz, V, R 440 kΩ, oscilloscope C1-1-16. If charged droplets fly along the trajectory, the corona discharge is alleviated and the amplitude of the corona pulse will be an indicator of the charge droplets Make it easier Corona discharge can also cause a drop in flight to oscillate relative to the spherical equilibrium position (Figure 1a, stroke drops). For this, the drop can be affected at the time of its formation or at any point of flight, such as a periodic electromagnetic field or mechanical action. If the droplet in the registration area will have the shape of an ellipsoid with a major axis in the direction of the force lines, then its curvature increases significantly and a corona discharge pulse will require less stress. To select the relative position of the initial point of disturbance of a droplet, use the ratio for the natural frequency of the droplet: fl, 27W / (pd; gdec4, | is the surface tension coefficient and the density of the liquid; d ,, is the droplet diameter. Figure 3 illustrates the ability of the droplet for example, amplify a single-field electric field at their poles. The field gain is the reciprocal of the depolarization coefficient 36. As can be seen, a spherical droplet amplifies the original electric field three times, an ellipsoid along the lines of force with a ratio of semi-axes in / a 0.5 enhances the field by about 6 times, with in / a 0.25 - 12.5 times, with in / a 0.1 - 28 times. Give a spherical a drop in the registration area, the desired shape of an ellipsoid, drawn along the power lines, can be due to its perturbation either at the point of formation of the drops or in flight, or in the registration area by various force factors (electric field, mechanically, pneumatically, etc.). Figure 4 shows the found distribution of the electric field intensity for needle electrodes of a hyperbolic which shape along the axis of symmetry JC depending on the angle of conicity of the conicity i-p) at the interelectrode distance of mm and kV. In order to increase the initial intensity at the point of entry of drop 3, it is necessary to reduce the interelectrode distance h, increase the angle H and the voltage and. In this case, in the case of flat electrodes, the decrease in the interelectrode distances h is limited to h 10 d in order not to increase the aerodynamic resistance of years w; it drops in the registration area. The use of needle electrodes from this point of view is preferable, since the needles create less aerodynamic interaction with flow drops, i.e. it is possible to reduce h and U while maintaining E. As can be seen from figure 4, in the gap between the needles, the electric field has areas of a strongly non-uniform and quasi-uniform electric field. When a droplet enters a quasi-homogeneous area, the effect on the moment of registration of the misalignment of the trajectory is almost eliminated, and it becomes easier to create a corona discharge when entering a sharply non-uniform area. initial stress in the gap and reduces with sensitivity to the mixing of the trajectory of the droplets. When a droplet enters a sharply inhomogeneous field, such as needles, wires, etc., if you select a certain ratio of the radii of curvature of the droplet and electrodes, you can create conditions for coronaging not from the droplet, but from the electrodes (unipolar corona discharge) or get simultaneous corona discharges both from the drop and from the electrode (bipolar corona). With the bipolar corona, one can obtain a large amplitude of pulses and increase the response speed (steeper fronts). Figure 5 presents the theoretically found and experimentally confirmed values of the initial coronation strength E for spherical and ellipsoidal drops (negative pole), as well as for needle-shaped electrodes in the form of rotation hyperboloids and concentric cylindrical electrodes for different radii of curvature. Corona corona depends significantly on the radius of the drop (at the poles). The maximum intensity of a uniform electric field between the plates is limited by the condition of a sample of kV / cm. When passing through the registration zone of a spherical droplet, the intensity at its poles will increase by 3 times and reach 90 kV / cm. This is sufficient only to obtain a pulsed corona discharge from droplets with a diameter d of 1 mm. In order to ignite the corona discharge from droplets of smaller diameter, they must be stretched into an ellipsoid. In this case, in a uniform electric field at the poles of an ellipsoid drop, you can get at, 5; 0.25; 0.1. Corresponding values of strains E, 180; 360; 840 kV / cm. As can be seen from FIG. 5, such a strength is sufficient to create a corona pulse with any elliptical drop and register it. Claims of the method for registering flying droplets in electro-jetting devices based on passing droplets through a discharge gap in which corona discharges occur as they fly past, for example, optical media 512782506 With the help of the results, the discharge gap excites that, in order to increase the reliability of oscillatory oscillations of the droplets, for example, electro-emission, before the passage of the droplets by the magnetic field. 0.1 0.6 0.8 (Rig. 3 w / a