US3060429A - Certificate of correction - Google Patents

Description

1962. c. R. WINSTON 3,060,429

METHOD OF AND APPARATUS FOR TRANSFERRING INK Filed May 16, 1958 INVENTOR CHARLES R. WINSTON ATTORN Y tinned Patent-p 3,060,429 METHUD 9F AND APPARATU FUR TRANSFEERENG ENK Charles R. Winston, Chicago, 1111., assignor to Teletype Corporation, Chicago, lilh, a corporation of Delaware Filed May 16, 1958, Ser. No. 735,817 7 Claims. (Ci. Me -1) This invention relates to a method of and apparatus for applying a marking medium to a recording medium, and more particularly, to an electrostatic inking apparatus and a method for electrostatically depositing ink on controlled areas of a receiving surface.

In the past, there have been numerous attempts to effect non-impact printing by positioning a plate, having conductive character-delineating electrodes formed on it, behind sheets of recording media such as paper or like receiving surfaces, and then generating a spray, mist or smoke of marking medium such as a dye or an ink in front of the receiving surface and attracting the ink to the plate by an electromagnetic or electrostatic field, thereby to attract particles of ink to the paper or other receiving surface in the areas outlined by the character-delineating portions of the plate. There have also been attempts to attract a jet of ink to a receiving surface, but such attempts have not proved to be commercially feasible due to the tendency of the jet to form into a spray and due to the inability of the prior-known devices to control the jet.

It is an object of the present invention to provide a method of and apparatus for applying a controlled jet of a marking medium to a recording medium.

Another object of the present invention is to provide a method of and apparatus for electrostatically forming a controled ray-like jet of a marking medium and directing it to a receiving surface.

A still further object of the present invention is to provide a method of and apparatus for forming a controlled jet of ink electrostatically, and for guiding the jet so formed to deflect its course in accordance with a prede termined pattern.

Yet another object of the invention is to provide a mechanism for and a method of electrostatically generating a ray-like jet of ink between a source of ink and a receiving surface and for utilizing electrostatic devices to accelerate the travel of the jet and to deflect the jet in accordance with a predetermined pattern.

In accordance with one embodiment of the invention, ink is delivered to a capillary nozzle under suflicient pressure to form a bulge or convex meniscus at the end of the nozzle, but not suflicient to product a flow of the ink out of the nozzle. An electrostatic field is established between the nozzle and a conductive platen which is placed opposite the exit of the nozzle, by applying a potential difference between the platen and nozzle, whereby the ink is drawn out and the bulge will be drawn into an elongated shape having a tip from which a fine ray-like jet is drawn toward the plate or platen. This will result in a jet of ink being directed from the capillary nozzle toward the platen, approximately in a direction normal to the surface of the platen. If a sheet of paper or strip of paper or other recording medium is placed against the platen, a line may be drawn on the tape or sheet if the sheet is moved along the plate or platen. Interruption of the jet may be effected by reducing the potential difference between the platen and the nozzle, and consequently, marks of controlled length may be made on the sheet of paper.

While the just described method is the preferred method of maintaining a supply of marking medium at the required distance from the platen, it has been found that a jet will be drawn from other types of supply means which will so localize the supply that the point from which the jet is drawn, may be controlled.

In another embodiment of the invention, the method may be practiced by utilizing a valving plate or anode having a hole in its through which the jet of ink is directed. By varying the voltage applied to this valving plate, the jet may be controlled to interrupt its flow toward the ink receiving surface and platen. This plate also serves to prevent the jet of ink from forming into a spray and maintains the jet in a ray-like stream.

In a still further embodiment of the invention, there are provided deflecting electrodes for deflecting the direction of the jet by varying the voltage applied to the electrodes and these electrodes are controlled to cause the jet to form characters or other patterns on a tape or sheet may be held stationary against the platen or may be moved continuously or step by step along the platen.

A more complete understanding of the invention may be had by reference to the following detailed description when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is an illustration of the simplest form of the apparatus, wherein a jet of ink is directed against a paper tape;

FlG. 2 is a fragmentary detailed view showing the capillary nozzle;

FIG. 3 is a diagrammatic view illustrating a second embodiment of the invention, wherein a valving plate is used for controlling the flow of the jet of ink;

FIG. 4 is a diagrammatic view of an alternate embodiment of the invention utilizing an accelerating plate and a valving plate for controlling the fiow of the jet, and

FIG. 5 is a diagrammatic view similar to FIGS. 1, 3 and 4 showing, in addition to the material shown in FIG. 4, sets of electrodes for deflecting the ray-like jet or beam of ink from its path to control the deposition of the ink on the paper in a predetermined pattern which may be controlled by controlling the voltages supplied to the defleeting electrodes.

Referring to the drawing wherein like reference numerals designate the same parts in the several views, particular reference being had to FIG. 1, wherein there is illustrated the simplest form of the apparatus for practicing the invention, it will be seen that there is provided a web or tape 10 of paper or other ink receiving medium. This tape 10 may be moved across the face of a conductive platen 11 by any suitable driving means and serves as a record strip onto which a stream or jet of ink 12 is to be directed from a nozzle 13.

In a form of the invention which has been found to operate satisfactorily, the nozzle 13 at its exit end comprises a capillary tube 14 having an inside diameter of the order of .005 inch and an outside diameter of the order of .010 inch. This tube 14 may be made of conducting or non-conducting material. The exit end of the nozzle 13 was spaced from the platen 11 a distance of approximately .035 inch and the nozzle 13 was supplied with ink from a reservoir 15 under suflicient hydrostatic pressure to cause the ink to form a convex meniscus such as shown at 16 in FIG. 2, but not suflicient to cause the ink to flow from the nozzle 13 unless influenced by other forces than the hydrostatic pressure. With a capillary tube 14, having the just-mentioned dimensions, it was found that a proper meniscus 16 was formed if the surface of the ink in the reservoir 15 was 6 inches above the capillary tube 14. The ink used was a red stamp pad ink manufactured by Phillips Process Company, of Rochester, New York, under the trade name Clear Print.

In this apparatus, since a non-conducting tube 14 was used, an electrode 17 was positioned in contact with the ink in the nozzle 13 and connected through a control device 18 to the positive side of a voltage source 1?, the negative side of which was connected to the platen or plate 11. Upon operation of the control device, a potential difference of approximately 1800 volts was applied between the platen 11 and the ink through the electrode 17. This caused the ink bulge or meniscus 16 at the exit end of the capillary tube 14 to be attracted toward the platen 11 in a ray-like jet 12 of minute droplets. The voltage applied between the plate 11 and the ink through the electrode 17 produces a force on the surface of the ink which is equivalent to a positive pressure tending to extend the bulge at the capillary orifice. This pressure was found to be equivalent to several inches of hydrostatic pressure.

In addition to this electrostatic pressure effect, which is aanlogous to hydrostatic pressure, there is the further effect peculiar to electrostatics, that the force on any portion of the surface of the ink increases as that area approaches the platen 11. Thus, there is a pressure gradient along the jet 12 of ink which reaches a muimum at the point closest to the platen 11. Therefore, the bulge or meniscus 16 is modified by the application of the voltage between the electrode 17 and platen 11 and the central portion of the meniscus being originally closer to the platen 11 will be more strongly attracted toward the platen 11 than the circumference thereof. This results in the meniscus 16 being drawn out into a progressively narrower stream or jet 12 as illustrated in FIG. 2.

Thus, when a voltage is applied between the electrode 17 and the platen 11 opposite charges build up on the ink at the nozzle 13 and the platen 11. Any one unit charge on the surface of the ink is attracted by every charge on the platen 11, but the unit charge at the geometric center of the ink meniscus, being closer to more charges on the platen than any other, will be more strongly attracted to the platen 11 and hence will tend to move toward the platen, lifting the ink in its vicinity above the surrounding level to form a protuberance. When this occurs, another effect takes place. All the like charges on the surface of the ink repel each other and will therefore tend to push an excess of charge to the end of the protuberance. This extra charge is also attracted toward the platen and therefore increases the force on the protuberance, making it extend even more. The cumulative effect of this action is to form a ray-like jet of the ink moving toward the platen. The degree of extension of the meniscus and drawing out of the ink into the jet depends upon the surface tension of the liquid (which seeks to minimize the area of the bulge), the net hydrostatic pressures (which tend to exert a pressure outward in all directions) and on the outside diameter of the capillary tube 14 (which determined the basic size of the meniscus or bulge in the first place). It has been found that the ink which enters the meniscus or bulge 16 at the exit end of the capillary tube 14 at a very low velocity will be accelerated along the extended portion or protrusion and that, due to the increasing velocity of flow, the protrusion will become narrower as it moves out. This narrowing continues until some undetermined point at which the protrusion becomes no smaller, but breaks up into droplets which maintain the diameter of the stream independently of their velocities and constitute a ray-like jet which has diminished to a diameter order of magnitude less than the diameter of the capillary tube 14 (Le, on the order of one-twentieth to one one-hundredth). It has also been discovered that the stream can be maintained uniform along its entire length after it has been reduced to the size of the jet only under proper conditions of the shape of the electrostatic field and the intensity gradient. Otherwise, because of diverging field effects and mutual repulsion of the droplets, a spray will be formed.

It has also been discovered that, in order to produce a satisfactory jet of ink over a predetermined distance, the applied voltage should be maintained within predetermined limits. For example, if the end of the capillary tube 14 and the web supporting surface of the platen 11 are spaced apart .040 to .045 inch and a potential difference of 2000 volts is applied between the capillary tube 14 and the platen 11, a jet will be formed substantially conforming to the configuration disclosed in FIG. 2. This jet will start to form when the potential diiference is 1800 volts, will completely form when the potential difference reaches 2000 volts and will be maintained if the potential difference is maintained between 2000 and 2200 volts. If the potential difference between the nozzle 13 and the platen 11 is increased to 2500 volts, there is a tendency for the meniscus to move back toward the shape shown at 16. However, a jet of ink will still be formed and may be guided by suitable electrodes at the proper potentials. When the potential diflference is raised to approximately 3000 volts, a corona or are is formed and the jet is destroyed. In the just-described procedures the spacing of the nozzle 13 from the platen 11 was .040 to .045 inch.

In arriving at the proper voltages to use in the method of the present invention a plate, similar to the platen 11, was spaced from a nozzle, similar to the nozzle 13, a distance of approximately .075 inch, this plate was covered with a layer of insulation approximately .006

inch thick and a potential difference of 3000 volts was applied between the plate and nozzle. Under these conditions the jet became somewhat erratic and the surface of the bulge or meniscus became somewhat ragged. When the potential diiference, under the just-stated conditions, was raised to 5000 volts, a series of jets were formed which were separate and the meniscus moved back to a position about flat with the end of the capillary tube 14-. When the potential difference was raised to 6000 volts a corona effect was noted, the jets stopped forming and a spray-like discharge occurred. Upon raising the potential difference between the nozzle and plate to 7000 volts, the insulation covering the plate broke down and a spark discharge occurred at the surface of the supply of ink at the end of the nozzle, disrupting operation.

The ray-like jet of ink is so fine that, while a very fine line of ink on a moving web of paper will be formed when the hydrostatic head of ink at the capillary is maintained as described hereinbefore, it has been found that the jet will be forced to carry more ink if the hydrostatic pressure at the nozzle is increased. As a matter of fact, a head of pressure of 18 inches has produced a highly satisfactory jet even though this high a head of pressure may cause the ink to ooze out of the capillary tube when no jet is being formed electrostatically.

As soon as the platen 11 and the electrode 17 are restored to the same potential, the electrostatic effect will disappear and the ink configuration will return to that of the slight bulge or meniscus as shown at 16 in FIG. 2. When the potential difference is reapplied, the dynamic configuration will re-appear, but not immediately. There is a time lag of the order of a millisecond or less between the instant voltage is applied and the instant When the dynamic equilibrium condition is reached. The time lag is largely a function of the viscosity of the marking medium or ink that is used, and obviously, the time lag will increase as the viscosity increases. The time lag thus could decrease if a less viscous ink were used than the ink described hereinbefore.

From the foregoing, it will be apparent that if the tape 10 is moved across the platen 11 at a known con stant velocity, a record may be made upon the tape 10 in the form of a line which will indicate the duration of a pulse sent through the control device 18, to indicate the condition of the control device 18 in graphic form on the tape.

In the embodiment of the invention disclosed in FIG. 3, the nozzle 13, having ink supplied to it at a pressure sufficient to form the proper meniscus or bulge 16, is

positioned at a distance of .040 to .045 inch from a valving plate 21 and is maintained at +2000 volts either by utilizing the electrode 17 or by using a nozzle made of conducting material and connecting the voltage source to the nozzle. The platen 11 is constantly maintained at approximately 5000 volts and the valving plate 21 is interposed between the nozzle 13 and the platen 11. The valving plate 21 has an aperture 22 formed in it which is of the order of .015 inch in diameter and the jet 12 is directed from the nozzle 13 toward the platen 11 through this aperture. The valving plate 21 is connected to a suitable voltage source through a control device 23 which may be operated to maintain the plate 21 at either ground potential or at +500 volts. When the valving plate 21 is maintained at ground potential, the jet 12 will be directed through it and will be accelerated by it, toward the platen 11. When the control device 23 is operated to change the voltage of the plate 21 from ground potential to +500 volts, this change in the potential difference between the nozzle 13 and the valving plate 21 will be sufficient to interrupt the flow of ink from the nozzle 13 and cause the meniscus at the nozzle to return to the configuration as illustrated at 16 in FIG. 2. Thus the valving plate 21 serves as a means for turning the jet 12 on and off and may be controlled by the control device 23 in any suitable manner to determine the duration of the jet. Consequently, if the tape is drawn past the platen 11 as shown in FIG. 3 at a constant known rate, the apparatus as shown in FIG. 3 will effect the same result as described in connection with the apparatus of FIG. 1.

It "has been found that if a relatively large plate 2.1 is used, with an aperture of the size specified hereinbefore, the tendency of the jet to form into a spray is inhibited to such an extent that the jet may be maintained at a uniform size when projected over an appreciable distance. For example, with the voltages mentioned herein, in connection with the apparatus shown in FIG. 3, a jet has been projected for a distance of over .250 inch without appreciably enlarging and at the point of its impingement on the paper, produced a line .002 inch W1 e.

In FIG. 4 there is illustrated an embodiment of the invention wherein the jet 12 is directed from the nozzle 13 onto the tape 10 in front of the platen 11 and is con trolled by a pair of electrodes or plates 31 and 33 having apertures 32 and 34 in them, respectively. The electrode or plate 31 serves as a jet forming electrode whereas the plate 33 serves as a valving or shut-off electrode. The aperture 32 in the plate 31 was .015 inch in diameter and the aperture 34 in plate 33 was .040 inch in diameter. In this embodiment of the invention, the plate 31 was positioned .035 inch from the end of the nozzle 13, the plate 33 was located .045 inch from the plate 31 and the platen 11 was .200 inch from the plate 33. With this arrangement, it was found that if a positive potential of +3500 volts were applied to the nozzle 13, a positive potential of +1500 volts were applied to the accelerating electrode 31, ground potential were applied to the valving plate 33 and a negative potential of -5000 volts were applied to the platen 11, a jet of ink would be directed from the nozzle through the apertures 32 and 34 in the plates 31 and 33, respectively, onto the paper 10 in front of the electrode 11. When the potential of the valving or shut-off plate 33 was raised from ground potential to a positive potential of +2500 volts, the jet 12, after passing through the aperture 32 in the plate 31, would be directed back to the plate 31 and would then drop off the plate 31. With the arrangement shown in FIG. 4, it will thus be apparent that a jet of ink may be directed to the tape 10 under control of the valving plate 33. When the potential of the valving plate 33 is raised to approximately +2500 volts, the jet of ink will be directed back against the surface of the plate 31 substantially as indicated by the dotted lines at 35 and with this arrangement, it is possible to get a faster response than with the previously described embodiments of the apparatus, by varying the voltage of the valving plate or electrode 33, since the stream of ink from the nozzle 13 is never stopped but rather is diverted by the valving plate or electrode 33 away from the paper 10.

In FIG. 5, there is illustrated an embodiment of the invention wherein the beam or jet of ink 12 which is projected from the nozzle 13 is directed through an aperture 40, in a valving plate 41, in its path toward the platen 11. The jet or ray of ink 12, after passing through the aperature 40 is directed between a pair of vertical deflection electrodes 42 and 43 and thence between a pair of horizontal deflecting electrodes 44 and 45. The electrodes 42, 43, 44 and 45 serve to guide the jet 12 somewhat in the manner that the deflecting electrodes of a cathode ray tube deflect the electron beam therein.

In the apparatus shown in FIG. 5, there is embodied the structure to provide for generating an ink jet and using it for the printing of character images. In this embodiment of the invention, the reservoir 15 would prefer-ably be positioned approximately 6 inches above the nozzle 13 in order to provide the proper meniscus 16 at the orifice of the nozzle, as is true in all the other embodiments of the invention discussed hereinbefore. In one embodiment of the structure thus briefly described, it has been found that with a nozzle having an inside diameter of .005 inch, and an outside diameter of .010 inch located .035 inch away from the plate 41, the aperture 40 in the plate 41 being .015 inch in diameter and the exit orifice of the nozzle 13 being .280 inch from the platen 11 and the thickness of the plate 41 being .004 inch, a suitable jet 12 may be generated and directed from the nozzle to the tape or web of paper 10. In this embodiment of the invention, the nozzle voltage has been found to be effective if it is maintained at +4000 volts with the plate 41 at a potential of +2000 volts and the platen 11 potential at -3000 volts. With this arrangement, the jet may be turned off by raising the voltage of the plate 41 from +2000 volts to +2500 volts positive so that the potential difference between the nozzle 13 and the plate 41 is reduced from 2000 volts to 1500 volts. This shift in potential difference will turn the jet on or ofl. The deflecting electrodes 42, 43, 44 and 45 comprise two pairs of fine wires, but might well be plates, spaced about .015 inch to either side of the axis of the jet 12. The pair of electrodes 42 and 43 were located approximately .040 inch from the plate 41 and the second pair, that is, the pair of electrodes which effects the horizontal deflection and are designated 44 and 45, were spaced .040 inch from the first pair. The vertical deflection electrodes 42 and 43 were maintained at a level of about 1200 volts positive while the horizontal deflection electrodes 44 and 45 were maintained at a level of about 400 volts positive. These levels are such as to keep an approximately constant potential gradient between the plate 41 and the platen 11. Deflection of the jet 12 may be produced by raising the potential of one electrode of a pair of electrodes while lowering the potential on the other electrode. A potential difference of 500 volts between the members of either the pair 42 and 43 or the pair 44 and 45 will produce a deflection of about .070 inch at the platen 11.

It should be borne in mind that the voltages and dimensions given in connection with the description of FIG. 5 and also FIGS. 1, 3 and 4 are more or less dependent upon the characteristics of the ink being used. especially its viscosity, surface tension, and conductivity. The Clear Print ink described hereinbefore has been found to be satisfactory and to be usable with the mechanisms described hereinbefore. It should be understood, however, that the specific examples given hereinbefore, particularly the dimensional examples, may be varied over a relatively wide range, and that the examples given are simply illustrative.

In using the apparatus disclosed in FIG. 5, the tape 10 may be stepped intermittently, and each time it comes to rest, a character may be formed on the tape by deflecting the jet 12 under control of the electrodes 42 to 45 and turning the jet on and off by means of the plate 41. This result may be efiected in a number of ways, for example, the ink spot can be made to sweep the character area several times in a vertical direction, and to he stepped horizontally during each retrace, forming a line raster covering the character image. During each scanning operation of the jet 112, the jet may be turned on when a dark portion of the image is to be recorded and oh when a background portion is to be recorded.

Although several specific embodiments of the invention have been described hereinbefore, it should be understood that numerous variations thereof may be employed without departing from the invention, and it is reiterated that the examples given of voltages and dimensions are simply illustrative of methods and apparatus which may be employed.

What is claimed is:

1. The method of directing a jet of ink from a nozzle and attracting it onto a recording medium mounted on a platen spaced from said nozzle which comprises (a) supplying ink to said nozzle at a hydrostatic pressure such that a supply of ink will form a meniscus at the nozzle without running or dripping from it,

(b) positioning a metallic plate in spaced relation to and opposite the exit orifice of the nozzle,

() applying a potential difference between the plate and the nozzle which difference is proportional to the distance between the plate and the nozzle in the range of approximately 1800 to approximately 2200 volts at distances between approximately .035" and .045 to generate a jet of ink in a single file of droplets,

(d) positioning a recording medium in the path of the jet of ink, and

(e) maintaining a potential difference between the nozzle and platen to attract a jet of ink to the recording medium.

2. The method of directing a jet of ink from a nozzle and attracting it onto a recording medium mounted on a platen spaced from said nozzle which comprises (a) supplying ink to said nozzle at a hydrostatic pressure such that a supply of ink will be maintained at the nozzle and a meniscus of ink will form that will not flow from the nozzle, and

(b) applying a potential to the ink at the nozzle which potential is from 1800 to 2200 volts different from that applied to the platen when the platen is spaced from the nozzle a distance of between .035" and .045" to draw a jet of ink from the nozzle to the recording medium.

3. The method of directing a jet of ink from a nozzle and attracting it onto a recording medium mounted on a platen spaced from said nozzle which comprises (a) supplying ink to said nozzle at a hydrostatic pressure such that a meniscus of ink will form at the nozzle but will not flow from the nozzle,

(b) applying a potential difference between the nozzle and platen which is proportional to the distance between them in the range from 1800 to 2200 volts at a distance between .035" and .045" to attract the jet toward platen and onto the recording medium, and

(c) raising the potential diflerence between the platen and the nozzle to approximately 2500 volts to interrupt the flow of ink from the nozzle toward the platen.

4. An apparatus for directing a jet of ink onto a recording medium which comprises (a) a nozzle, (b) means for supplying ink to said nozzle at a pres- '8 sure that maintains a bulging meniscus at the exit of the nozzle,

(0) a plate spaced approximately .035" to .045 from the the exit of the nozzle,

(11) means for applying a potential between the exit of the nozzle and the plate in the range of approximately 1800 to 2200 volts to generate a jet of ink in a single file of droplets,

(e) said plate having an aperture through which the jet is directed,

(f) a platen in line with and spaced beyond the nozzle and plate for supporting a recording medium, (g) said platen being spaced .200" to .280" from the plate,

(It) means for applying a potential of 7000 volts to 8000 volts between the platen and the nozzle to attract the file of droplets onto said recording medium.

5. An apparatus for directing a jet of ink onto a recording medium comprising (a) a nozzle,

(b) means for maintaining a supply of ink at the exit orifice of said nozzle,

(0) a platen spaced approximately .250" to .280" from said nozzle for supporting a recording medium in position opposite the nozzle,

(d) a control electrode spaced .035 to .045" from said nozzle,

(e) means for applying a potential difference between the nozzle and the platen of from 7000 to 8500 volts to attract the ink toward the platen and onto the recording medium,

(f) means for applying a potential to the control plate which is within the gradient from the nozzle to the platen and which is from 1500 to 2000 volts different from the nozzle to generate a jet of ink and direct it toward the platen, and

(g) means for applying a potential which is 2500 volts different from the potential of the nozzle in the said gradient to stop the flow of ink from the nozzle.

6. An apparatus for directing a jet of a marking me dium from a nozzle and attracting it onto a recording medium comprising (a) a nozzle,

(b) a platen mounted in spaced relation to and opposite the exit orifice of the nozzle for supporting a supply of recording medium in the path of a jet of marking medium drawn from the nozzle,

(c) means for maintaining said nozzle at from +3500 to +4000 volts potential,

(d) means for maintaining said platen at from +5000 to +3000 volts potential to attract the marking medium to the recording medium, said platen being positioned approximately .280" from said nozzle,

(e) an accelerating electrode spaced approximately .035 from said nozzle and having an aperture in alignment with a jet of marking medium drawn from the orifice of the nozzle.

(7) means for maintaining said accelerating electrode at approximately +1500 volts,

(g) a valving electrode between the platen and the accelerating electrode and spaced approximately .045" from the accelerating electrode, and

(h) means operable to maintain the valving electrode at zero potential to sustain the jet of marking medium and direct it toward the paten and to shift the potential of the valving electrode to +2500 volts to direct the jet of marking medium back onto the surface of the accelerating electrode closest to the platen.

medium comprising (a) a nozzle,

(b) a platen mounted in spaced relation to and 0p posite the exit orifice of the nozzle for supporting a supply of recording medium in the path of a jet of marking medium drawn from the nozzle,

(0) means for maintaining said nozzle at a potential of approximately +4000 volts,

(d) means for maintaining said platen at a potential of approximately -3000 volts,

(e) an accelerating electrode spaced approximately .035" from said nozzle and having an aperture in alignment with a jet of marking medium drawn from the orifice of the nozzle,

( means for maintaining said accelerating electrode at a potential of approximately +2000 volts to direct said jet of marking medium towards said platen,

(g) means for changing the potential of said accelerating electrode to approximately +2500 volts to stop said jet of marking medium from coming from the nozzle,

(h) two pairs of deflecting electrodes interposed between the accelerating electrode and the recording medium, one of said pairs being spaced from the accelerating electrode a distance of approximately .040" and both electrodes of said one pair being maintained at approximately +1200 volts, the other of said pairs being spaced .040" from said one pair, both of said electrodes of said other pair being maintained at approximately +400 volts,

(i) and means for varying the potential of the deflecting electrodes by raising the voltage of one electrode of a pair while lowering the voltage of the voltage of the other electrode of the same pair to deflect the jet.

References Cited in the file of this patent UNITED STATES PATENTS 1,941,001 Hansell Dec. 28, 1933 2,143,376 Hansell Ian. 10, 1939 2,512,743 Hansell June 27, 1950 2,600,129 Richards June 10, 1952 2,676,868 Jacob Apr. 27, 1954 2,869,510 Renner Jan. 20, 1959 2,894,799 McCreary July 14, 1959 2,925,312 Hollmann Feb. 16, 1960 FOREIGN PATENTS 24,397 Australia Mar. 27, 1931 1,027,113 Germany Mar. 27, 1958 TENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,060,429 October 23, 1962 Charles R, Winston It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 51 for product" read produce column 2, line 5, for "its" read it line 15, after sheet" insert which column 3, line 16, for "aanlogous" read analogous "3 column 4, line 59, after "instant", first occurrence, insert th column 6, line 12, for "aperature" read aperture column 8, line 67, for "paten" read platen column 10, line 9, strike out "voltage of the;

ERNEST w. SWIDER v DAVID A Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,060,429 October 23, 1962 Charles R, Winston It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 51, for "product" read produce column 2, line 5, for "its" read it line 15, after "sheet" insert which column 3, line 16, for "aanlogous" read analogous column 4, line 59, after "instant", first occurrence, insert th column 6, line 12, for

aperature" read aperture column 8, line 67, for "paten" read M platen column 10, line 9, strike out "voltage of the";

Signed and sealed this 3rd day of September 1963.,

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

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