US2547706A - Selective discharge control for inks - Google Patents

Description

April 3, 1951 w. c. HUEBNER 3 SELECTIVE DISCHARGE CONTROL FOR INKS ON PRINTING PRESSES 6 Sheets-Sheet 1 Filed Aug. 6, 1945 INVENTEIR f/u EB/VER ATTORNEY April 3, 1951 w. c. HU'EBNER SELECTIVE DISCHARGE CONTROL FOR INKS 0N PRINTING PRESSES 6 Sheets-Sheet 2 Filed Aug.' 6, 1945 INVENTOR 1.1.14 C. H EBA/Efl mRNEY u l l l l h l 4 April 3, 1951 w. c. u BNER 2547 706 SELECTIVE DISCHMEEEEIONTROL- FOR INKS ON PRINTING PRESSES Filed Aug. 6, 1945 6 Sheets-Sheet 4 INVENTOR. W121 mM 6'. /uea/vse 1M miem z gm 4 rrae/ve Y5 April 3, 195fi w. c. HUEBNER SELECTIVE DISCHARGE CONTROL FOR INKS ON PRINTING PRESSES Filed Aug. 6, 1945 6 Sheets-Sheet 5 INVENTOR. Wu. 4 mm C Haas/wee BY April 1951 w. c. HUEBNER 2,547,706

SELECTIVE DISCHARGE CONTROL FOR INKS ON PRINTING PRESSES Filed Aug. 6, 1945 6 Sheets-Sheet 6 INVENTOR. W/LL/AM 6. Hues/wee A ram/vex:

l aten tecl Apr. 3, i951 OFFICE SELECTIVE DISCHARGE CONTROL FOR INKS ON PRINTING PRESSES William 0. Huebner, New York, N. Y. Application August 6, 1945, Serial No. 609,269.

This invention relates to a process and apparatus for printing and more particularly to the method and means for selectively controlling the density or color value-of the ink deposition on the print receiving material.

This application is a continuation-in-part of my application Serial No. 530,787, filed April 13, 1944, for Means and Method of Selective Control of Ink Deposition in Printing, and abandoned September 13, 1945.

The sense in which certain terms are employed herein is set forth at the outset to clarify the statement of the objects of the invention and the description and claims which are to follow and to avoid all likelihood of confusion or misunderstanding.

The terms printing, electronographic printing or related terms are used herein in the same sense as in my earlier Patents 1,820,194 of October 25, 1931, and 2,224,391 of December 10, 1940, and refer to the reproduction of an image or the production of a desired design on the print receiving material by the use of electro lines of force to transfer the ink to the print receiving material and without relying on pressure to effect such transference as is usual in ordinary pressure printing. The terms image and design are employed as meaning letters, words, texts, illustrations, zones and all other representations, singly or in combination, and which are ordinarily produced on print receiving material in the printing art. The term print receiving material or elementrefers to paper, cloth or other textiles, metals and any other material capable of having produced thereon an image or design. The term ink is to be understood as including not only ink such as commonly used in the printing art, but also pigments, coloring matter, paints and all other fiowable materials that may be employed in producing an image or design on print receiving material.

The expression field of force is used herein in the sense generally employed in writings on electrical phenomena 'to indicate the field, zone or sphere within which electrostatic forces are sufiiciently active or powerful enough to effect a transference of ink from one surface to another. The expression lines of force similarly is employed to indicate the forces themselves acting in a definite path or direction ineffecting the transference of the ink. Such lines of force are measurable in direction and amount and their effects, even though the theoretical 30 Claims. (01. rol -42s) explanation of what produces these effects may not be entirely clear or certain. v

, An object of the invention is to provide a method of and means for electronographically printing whereby various densities or color values of the ink deposition can be obtained in different portions of the reproduced image on the print receiving material or whereby the ink deposition can be controlled to produce different desired designs on said material.

In printing it is ordinarily and frequently necessary to apply different densities of ink on certain areas of the print receiving material than on other areas thereof, that is, certain areas should be heavier or more solid than other areas withvarying gradations between the light and heavy reproduced image areas in order to obtain commercially satisfactory printing. In my prior patents above referred to, the transference of the ink to the print receiving material is effected by passing the material through a uniform strength electro field of force and subjecting the ink to the lines of force to effect the transfer thereof. I Consequently, due to the uniform strength of the electro field of force, the deposition of ink on the print receiving material is of substantially uniform density.

An object of the present invention therefore is toprovide improved means and method in the art of electrostatic printing for selectively and automatically controlling the intensity of the electro lines of force, to the end that the resulting image produced on the print receiving material will have the desired density gradations of ink deposition on different areas thereof.

A further object of the invention is to provide in electroncgraphic printing apparatus improved means for varying the volume of ink transferred to the print receiving material at selected points or areas in accordance with the requirements of the image to be reproduced thereon or in accordance with the character of the design it is desired to produce on the material.

Another object is to provide in an electronographic printing apparatus a plurality of separately and selectively controlled sets of opposed ink discharge and attraction elements and between which elements the print receiving material passes, whereby the volume of ink transferred to the print receiving material at any predetermined point within the zone of transference may be varied or controlled to meet predetermined requirements.

Another object is to provide an electronographic printing apparatus such as referred to in the last named object and wherein a master control drum is employed to automatically control the intensity of or to interrupt the electro field of force between the discharge and attraction elements of the separate sets of elements to thus vary the density of the ink deposition on the various areas of the reproduced image or to produce on the print receiving material a desired or predetermined design.

In multicolor printing it IS desirable and commercially essential that line uniform quality of printing be maintained throughout an entire edition. In order to obtain such fine, and form quality, the differently colored inks, such as yellow, red, blue, emerald green, purp e, black and other colors should be applied accurately as to quantity or volume if the correct balance of colors is to be obtained. It will be understood that should anyone of the component colors of the printed matter be too light or too strong an adverse result maybe obtained and the uniform quality of the edition destroyed.

An object of the invention is to provide an improved method of and apparatus for multicolor printing whereby the quantity or volume of the inks or pigments deposited upon the print receiving material is so controlled as to result in producing the desired color values of the printed edition with the requisite uniform quality throughout.

Another object is to control inmulticolor printing the color values over the entire width of the print receiving material whereby localareas may be accentuated where more solid color is needed for greater strength to enhance the brilliancy ofthat local area.

A general object of the invention is to provide an improved method of and means for electronographically printing that broadens the adaptability of this art to meetrequired or desired results necessary for commercial printing and give to electronographic printing; an advantageous flexibility.

Further and additional objects and advantages not hereinbefore referred to will become apparent during the detailed description of several embodiments of the invention which is to follow.

Referring to the accompanying drawings,

Fig. 1 is a fragmentary vertical longitudinal sectional view through a printing couple of an electronographic printing press taken substantially on line l-l-'"of Fig. 2- and embodying one form of the present invention.

Fig. 2 is a vertical transverse sectional view taken substantially online 2-2 of Fig. 1.

Figs. 3 and 4 are views similar to Figs. 1 and 2, respectively, but illustrating a diiferent embodiment of the? present invention.

Fig. 5 is a developed view partly in end elevation and partly in section of" the printing press embodyingthe invention andillustrated in Figs. 1 and 2 and shows the master control; drum which is employed; in the printing couple.

Fig. 6 is a fragmentary vertical transverse sectional view taken substantially on line 6-6 of Fig. 5 and shows an inking roller for inking the image carrying cylinder of the couple.

Fig. '7 is a diagrammatic developed view of a portion of the circumference of the control drum shown in Figs. 5 and 6 and taken substantially on line I -l of-Fig. 9 and also of the control circuit for one set ofopposed discharge and attraction elements carried,respectively, by the image cylinder and the supporting cylinder of the printing couple.

Fig. 8 is a view of a portion of the control drum and control switch shown in Fig. '7 and is taken looking from the right hand side of Fig. 7 with the support for the control switch shown in section.

Fig. 9 is a developed fragmentary elevational view of a portion of the circumference of the control drum shown in Figs. 5 and 6 and illustrates the various positions assumed by the control switch actuating lever as the drum rotates.

Fig. 10 is a diagrammatic illustration indicating by dash lines the areas of the print receiving material on which the ink depositions are made under the control of the portion of the control drum shown in Fig. 9 and correlated to the different positions of the switch actuating lever shown in. Fig. 9.

Figs. 11 and 12 are similar to Figs. 9 and 10, respectively, but illustrate a different portion of the control drum circumference and the form of design produced by said portion.

Fig. 13 is a developed partial end elevational and sectional view of the printing couple disclosed in Figs. 3 and 4 and has added thereto the master control drum and other elements of the control mechanism for controlling. the intensities of the electrostatic fields of force between the discharge and attraction elements or blades of the separate sets of elements or blades.

Fig, 14 is a fragmentary vertical transverse sectional view taken substantially on line Hi -4'4; of Fig. 13 looking in the direction of the arrows. Fig. 15 is a diagrammatic illustration of the electrical control means employed in the embodi-- ment of the invention shown in Figs. 13. and 14.

Fig. 15a is a diagram of portions of an electrical control circuit similar to Fig. I5 but showing a modified form of control, and

Fig. 16 is a detached detail view looking at the slotted'end of one of the-cylinders containing the light sourcein the control mechanism.

Inasmuch as'the present invention maybe incorporated in single or multipleunit presses; in sheet or web presses, with relief, intaglio or planogr-aphic printing plates, all as shown in my: sa-id prior Patents the-discharge and attraction elements disclosed in. said applications. are each in the form of asingle element extending the-longitudinal length of: the respective cylinder within which it is mounted, while inthe construction shown herein in Figs. 1 and 2 the opposed discharge and attraction elements: are arranged? in a multiplicity of separate or independent sets of. elements zlocated'i within the respectivecylinders.

Referring now to'Figs 1. and 2, the vertical;

members of a press frame are indicatedat Ill and non-rotatable sleeves H are supported in said members. Collars 12, are mounted onthe inner ends of the sleeves, H. and. said collars support antifriction bearings IS. The bearings, l3 rotatably support disks It which form the opposite, ends of the image carrying,w cylinder A andthe. supporting cylinder 13. The disks I4 arepro videdon their circumferences with gears l5with 1,820,194 and 2,224,391, it is: deemed necessary to illustrate onlya singleprintmeans such as the dowel pin [8. The image or plate carrying cylinder A and the supporting cylinder B are mounted on the insulating rings l6 and hence are electrically insulated from the disks [4.

The image cylinder A may be provided with a printing plate of the relief, intaglio or planographic type as desired, or it may be provided with image portions permeable to electro lines of force and non-image portions impermeable thereto all as disclosed in my said prior Patent 2,224,391. Also the cylinder A may be a plain cylinder in those instances wherein the transference of ink to the print receiving material to produce a desired design is controlled solely by the existence or non-existence of electro fields of force between the pairs of discharge and attraction elements, as will later be pointed out.

The cylinder A can be inked in any of the known and usual ways, depending upon the type of printing plate used, one such way of inking the cylinder being indicated in Fig. 6 by the inking roll l1.

The lower or supporting cylinder B will have a smooth plain surface and its function is to sup-- port the print receiving material directly, as

shown in my said Patent 2,408,1 i3, or to support a feed belt (not shown in Figs. 1 and 2 but shown in Figs. 3 and 4) which in turn supports the print receiving material.

As described in my prior patents hereinbefore referred to, the electro lines of force passing between the discharge and attraction blades or elements, later to be described and located within the cylinders A and B, respectively, act to transfer the ink from the image areas of the cylinder onto the print receiving material passing between the cylinders A and B and moving in timed relation thereto.

Extending through the center of each of the cylinders A and B is a hollow insulator tube 38, supported in the sleeves I I. Straddling each tube 38 at relatively closely spaced intervals substantially the length of each cylinder is a series of U- shaped magnet cores 39. These magnet cores are centered by and slidable with respect to the corresponding tube 38 and are adjustable radially of the cylinders by means of the adjusting screws 3| which are swiveled in a supporting plate id supported in turn by the tube 38. Each magnet core 39 is provided with right and left windings or spools 42 and all of the windings or spools are connected to a suitable source of electric current as will be well understood and as is disclosed in my hereinbefore mentioned Patent 2,224,391.

Although the magnet windings in both cylinders A and B are stated at this time to be connected to the same source of electric current, it will be pointed out hereinafter that the magnet windings in cylinder A need not be energized while the separate magnet windings in the supporting cylinder B can be variably energized to create magnetic fields of different intensities which will act to transfer the ink from the printing cylinder A to the print receiving material in such manner as to produce ink deposition oi? various densities on the material.

As shown in Fig. 2 the magnet spools in cylinder A are aligned with the magnet spools in cylinder B and are arranged in vertical pairs with a north pole or spool in the cylinder A disposed opposite a south pole or spool in the cylinder B, and correspondingly a south pole or spool of cylinder A opposite a north pole or spool of cylinder B.

Specially shaped field bars-44 are secured to the ends of the respective sets of ends of the magnet cores 39 and are provided with arcuate outer surfaces 45 disposed closely adjacent the inner surface of the corresponding cylinder with the respective adjacent edges of the field bars located closely together along a line extending lengthwise of the cylinders.

Y Secured to the insulator tube A andarranged lengthwise of said tube is a series of slightly separated relatively narrow blade sections or segments constituting separate discharge elements. Similarly the tube 38 in the supporting cylinder B is provided with a series of slightly separated relatively narrow blade sections or segments 41- constituting separate attraction elements. Said blade sections extend radially of the respective cylinders and have in this instance sharp or knife-like edges disposed opposite each other and as shown terminating closely adjacent the inner surfaces of the respective cylinders at the printing zone, it being remembered that the two cylinders are slightly spaced apart so that there is no mechanical pressure or contact between the cylinders and in the illustration no mechanical pressure or contact between the cylinder A and the print receiving material 25 when the latter is passing between the cylinders.

It will be understood that the width of the blades 35 and ll and therefore the number of said blades may be varied in accordance with the nature of the printing to be produced on the print receiving material.

Also secured to each of the insulator tubes 3 and extending radially therefrom on each side of the respective sectional or segmental blades 35 and 41 between said blades and corresponding magnet spools are insulating shields or plates 10 which-extend throughout the length of the series of blades.

The blade sections or segments are each electrically connected with an independent wire or conductor 49 and all of said wires or conductors for a set or series of the blades will lead to the exterior ofthe cylinder through the insulator tube 38. The respective sets of conductors are connected to acontrol mechanism one form of which is illustrated in Figs. 6 to 12 inclusive and will later be explained.

As clearly explained in my prior Patents 1,820,194 and 2,224,391 the discharge and attraction elements, 1. e., the blades, when connected with a source of high potential electric energy, produce an electro field of force extending between theelements and acting to transfer the ink from the cylinder A to the print receiving material. As already stated, the magnet spools or windings are so arranged that north and south poles are disposed radially opposite each other in the two cylinders. With this arrangement the magnetic lines of force parallel those of the electronographic lines of force and in close proximity thereto and form shields on each side of the electronographic lines of force, thus preventing 38 in the cylinder I arrives J? or at least minimizing any tendency to spread or disperse that the electronographic lines of force might otherwise have and thereby insuring a more sharply defined and clear out reproduction of the image on the print receiving material.

The insulator shields I serve both to prevent dissipation of the electrical energy supplied to the discharge and attraction blades or elements and to prevent the magnetic fields from distorting the electronographic fields of force. Where relatively high voltages are used to supply the attraction and discharge blades and particularly when the magnetic field is employed, the insulator shields I0 will preferably be used as shown and described. However, the magnets may be omitted in some instances and in such case the insulator shields may also be omitted.

In commercial printing, as previously mentioned, certain portions of the reproduction may require a greater or heavier concentration or deposition of ink than other areas thereof consequently it is proposed to vary the voltages of the currents supplied to the different sets or discharge and attraction blades and 41 in correlation to the densities of the ink deposition to be made on the print receiving material. Inasmuch as the width of the blades of the sets of blades is relatively narrow various relatively narrow fields of force of different intensities can'be produced thus providing selective control of the deposition of the ink when actual printing of texts on irregular images is being performed or spot or area control when the deposition of ink is to produce a desired design and the ink has been applied over the entire surface of the cylinder A. Although the blades of each series are shown as slightly spaced apart, it will be understood. that the transferred ink will have a certain spread and the printing produced will not indicate the spaces shown between the blades.

A mechanism for controlling the intensities of the fields of force produced by the sets of discharge and attraction elements will now be explained with particular referenc'e'to Figs. 5 to 12 inclusive. As previously stated, the gears (*5 of the cylinder Bmesh with driving gears and reference to Fig. 5 discloses said driving gears 19 as mounted on a driving shaft 2|) thatis. actuated by asuitable power source not shown; The frame members Ill rotatablysupport belowthe shaft '20 a master control drum 2| which is provided on its opposite ends with gears 22 that constantlymesh with the gears I9. Although the axis-of the control drum is shown in vertical alignment with'tlre axes of the cylinders A and B and shaft 20; 'it will be understood that this relationship can-be varied if desired, as, for instance, to reduce the height of the press. The cylinders A andB and the drum 2| rotate in timed relation to each: other with the cylinder A rotating in a counterclocke wise direction as viewed in Fig. 6- and. the cylinder B and drum 2| in a clockwise direction.

The drum 2| is divided longitudinally thereof into zones correlated in number to the sets of discharge and attraction-elements in. the cylinders A and B. Each zone of the drum-2| is in the formof a' circular groove: formed in the drum and is provided with a series oficircumierentially spaced openings 23. The openings 23-arez adapted to'receive pins formed on cam blocks: Zeandsa-id pins areheld' inthe holes 23 inany'd'esired' orwell known manner. The cam blocks 2 t'are'of such width that they'interfit the z'onegrooves-andzconsequently are held againstturning movement (see Figs. Tami 8). Thet'difier-entz caml'blocks 2'4rare provided with different shaped camming portions and said cam blocks are mounted in the zone grooves in correlation to the image that is to be reproduced on the print receiving material or to a desired design that is to be produced thereon, as will later be readily understood.

A supporting bar 25 i carried by the frame members H1 and extends longitudinally of the control drum 2! and carries a series of control switches '26, there being as many control switches as there are grooved zones on the drum 2|, see Fig. 5.

The control switches 26 are illustrated merely by way of example as having two on positions and an intermediate or off position, it being understood that a different form of switch might be employed if desired to meet certain conditions. The switch 26 is illustrated as comprising two spaced contacts 21 and 28 and an arcuate wiper contact 29'. A switch bar 30 is constantly in contact with the wiper 29 and can be selectively en'- gaged with the contacts 21 or 28 or can be positioned intermediate said contacts 21 and 28 when the switch is in its off position.

The switch bar 38 is insulated from but carried by a rockable lever arm 32 that is pivotally mounted on the support 25 and extends radially toward the control drum 2| as viewed in Figs. 6 and 8, with the end of the lever arm cooperating with the cam block '24. It will be seen that as the control drum 2| rotates and the lever arm 32 comes into engagement with one of the cam blocks 24 said cam block can effect a rocking movement of the lever arm to position the switch plate 30 in either one of the two on positions or in the intermediate on osition.

Each attractionblade 41 is electrically connected by a wire 33 to the wiper contact 29 of its correlated switch 25 as clearly shown in Fig. '7. Each discharge element 35 is electrically connected by a wire 34 to one side of a source of high potential-electric energy. The other side of said source of electric energy is represented by the wire 36 which is electrically connected to the adj us'table wiper arms 37 of a pair of rheostats 4| and 43. The resistance 46 of the rheostat 4| is electrically connected by a wire 48 to the contact 28 of the switch 26. The resistance 50 of the rheostat 43 is electrically connected by'a wire 5| t0 the contact 21 of the switch 26.

As shown inFig. 7 the wiper arm 31 of the rheostat 4| is positioned to cut out the resistance 46 from the circuit, wherefore said resistance does not reduce the intensity or the current in the circuit in this instance and full source current can pass between the discharge and attraction elements 35 and 41 when the switch bar is contacting the contact 28.

It will also be noted by reference to Fig. 7 that the wiper arm 31' on the rheostat 43 is positioned to include a portion of the resistance 50 in the circuit between the discharge a'nd attraction elements when the switch bar 3i? is engaging the Contact?! of the switch 28 and hence the intensity o'f the current in the-circuit will be reduced a predetermined amount.

It will be understood that when the switch bar 30 is in the intermediate position between the switch contacts 21- and 28 no induced current will be flowing between the discharge and attraction elements 35and- 4'I in this partioular instance.

Assuming that the entire exterior surface of the cylinder Ais: inked by the inking. roller IT in a manner well known in the art and that a desired design is to be produced on the print receiving material 25 the cam blocks 24 correlated to each set of discharge and attraction elements are positioned in a predetermined manner circumferentially of the drum to control the circuits to the respective sets of discharge and attraction elements so as to provide in this instance a circuit of high intensity, a circuit of low intensity or to interrupt the circuit.

In Fig. 9 there is illustrated in a developed manner one groove zone of the control drum 2| with the cam blocks 24 arranged therein in said predetermined manner. Assuming that the printing couple is operating and the control drum is rotating in the direction of the arrow in Fig. 9 and referring to the lowermost cam block 24 in said view, it will be noted that the end of the lever arm 32 is in its most left hand position before it contacts with said lowermost cam block 24. Therefore the switch bar 3!] is engaging the contact 28 of the switch 26 and consequently the induced current between the discharge element 35 and the attraction element 41 is of maximum intensity and the deposition of ink on the print receiving material at this moment will be of heavy density or color and will produce a heavy color zone on the material represented by the lowermost dash line outline of Fig. and which for illustration purposes parallels the groove control zone of Fig. 9.

As the control drum rotates in the direction of the arrow the end of the lever arm 32 engages the cam surface of the lowermost cam block and is moved toward the right until it is in its extreme right hand position. This movement of the lever arm 32 causes the switch bar 30 to move off of the contact 28 and momentarily into a position intermediate the contacts 28 and 21, at which time the circuit through the discharge and attraction elements is momentarily interrupted and then to move into engagement with the contact 21,- whereupon the circuit is reestablished but at a lower intensity. Consequently there will be a space on the print receiving material on which no ink deposit will be made and then the ink deposition will be resumed with a light deposit. During the further rotation of the drum the lever arm 32 stays in the position to which it has been moved and the light deposition of ink continues to be made on the print receiving material as indicated in Fig. 10 by the elongated dash line outline marked light. As the drum continues to rotate the end of the lever arm. 32 engages the camming surface of the next cam block 24 which is spaced circumferentially from the first mentioned cam block and said lever arm is rocked by the second cam block to its intermediate position, at which time the circuit to the discharge and attraction elements is interrupted and consequently no ink deposit is made on the print receiving material. As the drum 2| continues to rotate the camming surface of the third circumferentially spaced cam block 24 engages the end of the leve arm 32'and moves said end of the arm from its intermediate position to its most left hand position, whereupon the switch bar 30 again engages the contact 28 and the high intensity circuit between the discharge andv attraction elements is restored and a heavy ink deposit is now being made on the print receiving material, as indicated by the dash line outline at the upper end of Fig. 10.

It will be understood that the camblocks can be so positioned as to vary the path which the end of the lever arm 32 will follow during the relative rotation between the drum and the lever arm so as to selectively produce predetermined heavy or light ink depositions on the print receiving material or areas where no ink is deposited.

Figs. 9 and 10 as already explained indicate one arrangement of the cam blocks for produc-. ing predetermined design of ink deposit on the print receiving material, while Figs. 11 and 12 represent a different arrangement which can be employed as will be clearly understood. It will be understood that the cam blocks will be arranged in this predetermined manner in all of the groove Zones of the control drum so as to control simultaneously. the transference of ink between the discharge and attraction elements of all of the-sets of-said elements and thereby produce the desired design on the print receiving material extending the width thereof.

In place of the switches 26. being of the type to provide two on positions and an oil posi-. tion, said switches can be of dififerent type so as to provide a different number of on and off positions as desired according to the desired design that is to be produced on the print receiving material but for the sake of simplicity only a three-position switch has been illustrated herein. Y

The description just above given refers to the production of a desired design on the print receiving material as indicated in Figs. 10 and 12 and when the drum A is entirely permeable to the electro lines of force. The present invention can also be employed when the drum A is provided with a predetermined image thatis to be reproduced on the print receiving material as, for example, when the drum A is constructed as in my prior Patent 2,224,391 with image areas permeable to lines of force and non-image areas impermeable thereto. e

When a predetermined image is to be reproduced on the print receiving material the intensity of the induced electro lines of force between the discharge and attraction elements of each set can be controlled in a manner somewhat similar to that previously described herein to cause the ink deposit corresponding to certain image areas or to certain portions of certain image areas to be of different degrees of density, 1. e., heavy, light or intermediate shades. In such case the control switches used would have a number of positions corresponding to the number of shades desired, it being understood that theoutline of the reproduced image would be attainedby the outline of the permeable image portions of the drum. j

It will also be-understood'that thepresent invention can be employed to control the color shades of the reproduced image whenthe drum A is provided with a printing or image plate of either the intaglio, relief or planographic type as will be apparent to one skilled in the printing art.

In describing hereinafter another embodiment of the invention a more detailed description 'as to how the invention is adaptable for controlling the color shades of the reproduced image will be set forth.

Referring now to the embodiment of the invention shown in Figs. 3 and 4, the selective con trol of the intensityof the lines of force throughout the length of the field is illustrated as incorporated in that type of printing apparatus shown in mycopending application Serial No. 518,470, filed January 15 1944. now= Patent 2,451,288, wherein the ink is transferred from the discharge blade or element. directly to the .print receiving material and withoutintervening The cylinder A application of the ink to an image carrying plate or surface. Also in said Patent 2,451,288 the supporting cylinder for the print receiving material or the conveyor printing cylinder and is provided with image portions permeable to the electro lines of force and non-image portions impermeable thereto, wherefore the ink is transferred to the print receiving material only in those areas correlated to the permeable image portions of the cylinder.

'In Figs. 3 and 4 the cylinder A is the printing or image cylinder and preferably is constructed and mounted in the frame as in the previously described construction of the cylinders A or B. is adapted to be driven from any suitable source of power as by the shaft 90, pin-ions SI and gears I5, while the paper or other print receiving material 86 is conveyed by a belt 82 as in my said Patent 2,451,288.

As in the construction of the press shown in Figs. '1 and 2 the attractor blades within the cylinder A comprise a series of sections or segments I41 with individual conductors I49 leading to the control mechanism later to be described. As shown, the blade sections are mounted on an insulator tube 92 vertically slidably guided by and adjustable on the insulator tube I38 by means of the adjusting screws I92, whereby the spacing between the knife edges of the sectional attractor blades 14! and the surface of the cylinder may be regulated. The sectional discharge or repulsion blades I35 are constructed similarly to the attractor blades, with the individual conductors 52 for the blade sections leading to the control mechanism later to be explained.

A controlled and conditioned supply of ink to the discharge blades I35 is provided in the following manner. If all of the discharge blades are to receive ink of the same color a longitudinally extending container I25 may be used, with said container in turn supplied through the supply pipe I26. The container I25 may have a series of nozzles I30 projecting downwardly from the bottom thereof and corresponding in number and correlated to the discharge blades I35. Each nozzle is provided with a control valve I3I and the ink from each nozzle is disposed on an inclined plate I and flows downwardly of the plate and onto the respective discharge blade I35. To insure a steady and uniform flow through the nozzles air pressure may be employed, the air being admitted to the cori-- tainer I25 through the pipe I33. Also in order to regulate the fluidity of the ink strip electric heaters I31 may be secured to the underside of the plates I10, as described in my said Patent 2,451,288. It will be understood that in certain instances it will be desirable to have the different discharge blades I35 receive ink of different colors and in such cases instead of a single container I 25 for all of the discharge blades I35 individual containers for each discharge blade may be employed.

I Referring now to Figs. 13 to 16 inclusive, the mechanism for selectively and automatically controlling the intensities of the fields of force between the opposed discharge and attraction elements of th sets of said elements will now be described. The pinions I9I mesh with gears 53 on the opposite ends of a master control drum #4 which is rotatable on a shaft 55 fixedly secured in the frame members. Although the drum 54 is illustrated in Figs. 13 and 14 as in vertical alignment with the axis of the c linder belt acts as the image or A" and shaft it will be understood that the axes of the drum, cylinder and shaft could be displaced from this vertical relationship if it: were desired to lower the height of the printing press. The control drum 54 will have secured on its periphery by suitable means a master sheet containing a chart correlated to the image to be reproduced on the print receiving material. It will also be understood that where the image is reproduced in different colored ink the chart will have differently colored portions correlated to the different colored ink containers and the sets of blades associated with said containers.

The side frame members of the printing apparatus support on opposite sides of the shaft 90 bars 56 extending between the frame members and provided with a series of openings corresponding in number to the sets of discharge and attraction blades and with each opening aligned with a respective set of blades, as shown in Figs. 13 and 14. The openings in one of the bars 56 mount housings 51 for light sources 58 of any suitable known form, while the openings in the other bar 56 mount housings 59 for photoelectric cells 60. The housings 51 and 59 are in the illustration disposed substantially at an angle of 459 to the vertical center line of the press, although they might be otherwise disposed. The housings 51 are provided at their lower ends with cover plates having slots 6| extending dia metrally thereof parallel to the axes of the master drum 54 and cylinder A and corresponding in length to the width of the blade sections (see Figs. 14 and 16). The housings 59 mount condensing lenses 52 which act to condense the light beams reflected from the surface of the master sheet to the photoelectric cells 65. The light beams from the light sources striking the master sheet correspond in width to the width of the blade sections and said beams are re flected in varying degrees of strength according to the density of color upon which they im; pinge on the master sheet. Therefore the strengths of the reflected beams acting on the photoelectric cells are in inverse proportion is the density of the color on the different portionsof the master sheet by which the beams are reflected. Therefore the intensities of the induced electro fields of force between the different sets of discharge and attraction blades can be controlled in relation to the different color densities on the various areas of the master sheet as the sensitivity of the photoelectric cells will effeet through an amplifying arrangement later to be described a control of the separate electrical circuits for the sets of blades. Similar light sources and photoelectric cells are employed which scan the ink deposit on the print receiving material and cause the strength of the light beams reflected to the photoelectric cells to be in inverse proportion to the color densities of the ink deposited on the material. The duplicate series of light sources and photoelectric cells are located on opposite sides of the series of discharge blades I35 and above the print receiving material. The supporting bars for the duplicate series of light sources and photoelectric cells are indicated at 56a, while the housings therefor are indicated at 51a and59a, with the light sources indicated at 58c and the photo- "electric cells at 60a. The housings 51a will be provided at their lower ends with cover plates having slots Bla therein while the housings 590. will be provided with condensing lenses 62a.

Referring to Figs. 13 and 14, containers 63 shown as located below the drum 54 house the amplifying circuits and devices with which each set of photoelectric cells BI] and 60a is operatively associated, there being one container 53 for each set of discharge and attraction blades. The amplifying circuits referred to effect forward and reverse energization of special split phase reversing motors t l supported by the containers externally thereof. It will be understood that the motors 6c correspond in number to the number of opposed sets of discharge and attraction blades and that said motors are arranged for convenience in two series with the motors related to the even numbered sets of opposed blades located on one side of the containers 63 and the motors related to the odd numbered sets of opposed blades located on the opposite side of the containers. Each motor shaft 65 extends upwardly and is provided with a worm 65a which meshes with a worm wheel 66 mounted on the shaft 61 of a rheostat later to be referred to.

Referring to the diagrammatic showing of Fig. 15, the rheostat referred to includes a resistance 68 and a wiper hand 59 mounted on the shaft 61 and contacting the resistance 68, wherefore rotation of the shaft 61 by the motor 64 (operatively connected therewith as indicated by. dash and dot lines) varies the position of the wiper hand relative to the resistance as will be well understood. One terminal of the resistance 68 is connected by a wire II to one side of a source of high potential electric energy, while the other side of said source is connected to the attraction blade I 41 by the wire I49 previously referred to. The discharge blade I35 is electrically connected by the previously mentioned wire 52 with the wiper hand 69 of the rheostat. Consequently the intensity of the current in the circuit to the blades I35 and I4! can be varied by the adjustment of the wiper hand 69 and thus the intensity of the induced electrostatic field of force between said blades can be varied to change the density of the ink deposition on the print receiving material. It will be understood that the intensity of the induced field of force between each set of opposed discharge and attraction blades is similarly controlled by a rheostat actuated by a motor 64. The wires 52 and I 45 and the wires, later referred to, forming the photoelectric cell circuits extend through openings in a frame member I6 and into a cover Illa (see Fig. 13) and thence to the container 63 and the rheostats.

The forward or reverse operation and the stopping of each motor 64 is controlled'in the manner now to be described.

The photoelectric cells 60 and 60a correlated to each set of opposed discharge and attraction blades or elements are connected in series parallel to wires 12 and I3. A control tube 14 is in the direct current circuit indicated generally at 75 and said circuit is connected to any suitable source of regulated voltage direct current. The wire 12 is connected to one grid of the tube 14 while the wire 13 is connected to the other grid of said tube. As long as the photoelectric cells 60 and 60a are activated by reflected light beams of equal intensity and are thus in balance nocurrent is passing through the control tube 14 to the amplifying tubes 76 andTI. However, when the reflected light beam activating one of the photoelectric cells is stronger-than the beam activating the other cell then one'of the grids of of the motor 14 the control tube 14 is activated more strongly than the other grid and current flows from said grid through the tube 14 to an amplifying tube connected to the grid circuit. Consequently any unbalanced condition in the photoelectric cells 60 and 60a will operate through the control tube 14 to activate either the amplifying tube 76 or the amplifying tube 11. It will be understood that so long as the light beams reflected by the master sheet on the control drum and by the ink deposit on the print receiving material are of the same intensity the cells 60 and 60a are in balance and the amplifying tubes I6 and 11 are not driven. The amplifying tube 16 may be termed the reverse amplifying tube while the tube 1'! may be designated as the forward amplifying tube. It will be further understood that as soon as the reflected light beams vary in intensity and create an unbalanced condition between the cells 60 and 660. then either the reverse tube 16 is driven or the forward tube 11, depending upon which photoelectric cell has the stronger output.

The reverse amplifying tube 76 is connected to the primary of a saturable reactor 78 while the forward amplifying tube 11 is connected to the primary of a saturable reactor 19. The secondaries of the reactors l8 and 19 are connected respectively to the shaded poles or windings 80 and BI of the motor 64. These poles or windings 80 and BI act as small transformer secondaries and have voltage induced therein from the field winding 83 of the motor and which winding 83 is continuously excited from an outside alternating current source 34. The alternating current source 84 has the primary of a transformer 85 connected thereto, while the secondary of such transformer supplies current to the filaments of the tubes I4, 16 and 11.

So long as the photoelectric cells 60 and 60a are in balance and no current is flowing through the control tube M to the amplifying tube 16 or the amplifying tube 71 the induced voltages in the poles or windings 80 and BI by the winding 83 are in balance and cause no rotation of the motor 64.. As soon as an unbalanced condition exists between the photoelectric cells 60 and 60a and the grid of the tube 16 or the grid of the tube 11 is activated and either the reactor 78 or the reactor 19 becomes active then the induced voltages in the windings or poles 80 and 8! are unbalanced and a current flow takes place in one or the other of said windings to effect rotation of the motor 64 in either the reverse or forward direction. As previously explained, the rotation 64 in the forward or reverse direction will act through the rheostat and wiper hand 69 to decrease or increase the current to the discharge and attraction blades I35 and I4! to thereby decrease or increase the intensity of the induced electrostatic field of force between said blades and thus to decrease or increase the density of the ink deposit on the print receiving material.

It will be understood that as soon as the density of color of the ink deposit corresponds to the density of the color on the correlated portion of the master sheet on the control drum the photoelectric cells are in balance and rotation of the motor 64 ceases and no further change in the current value to the discharge and attraction blades takesplace until said color densities again vary. In this way an accurate control 'of the ink densities of the ink deposit on the print receiving material is maintained and an accurate .tube H to effect reverse or control sheet is obtained on the print receiving material.

Although the series of photoelectric cells 60a.

has been illustrated and described as scanning the ink deposit on the print receiving material, it is possible to eliminate the series of cells 69a. and light sources therefor and rely only upon the series of cells 60 and their light sources which scan the master sheet of the control drum and commercial printing can be obtained by this modified arrangement.

Reference to Fig. 15a will indicate a simple way in which the control circuit shown in Fig. 15 could be modified to eliminate the photoelectric cell 60a and still eifectively control the density of the ink deposit on the print receiving material in correlation to the color densities on the master sheet. In Fig. 15a a variable resistance is connected between the wires 12 and 13 in place of the photoelectric cell 60a.

The variable resistance comprises a resistance coil 60b connected to the wire 12 and a wiper hand 600 connected to the wire 13 and cooperating with the resistance coil Gllb. The variable resistance controls the function of the grid of the control tube 14 that is controlled by the photoelectric cell iill'a in the diagram shown in Fig. 15, while the photoelectric cell 60 in both instances controls the other grid of the control tube Hi. The wiper hand 600 of the variable resistance is operatively interlocked with the wiper hand 69 of the rheostat that controls the high potential electric circuit to the discharge and attraction blades indicated by the dash and dot line in Fig. 15a, wherefore the wiper hands 69 and 600 move in unison and have inverse relative positions with respect to the resistances 68 and 60b.

When the variable resistance just described is placed in the circuit instead of the photoelectric cell 60a the control tube 14 functions in the same way as in the circuit shown in Fig. 15 to control the flow of current to either the reverse amplifying tube I6 or the forward amplifying forward rotation of the motor 64. It will be seen that when the current value flowing through the variable resistance is in balance with the output current value of the photoelectric cell to the motor 64 is not rotating. When the reflected light beam on the photoelectric cell 60 causes the output current value of said cell to be above the current value flowing through the variable resistance,

the grid of the tube 14 connected with the photoelectric cell predominates over the other grid of said tube and current flows through the amplifying tube 11 to effect forward rotation of the motor 64 to operate the wiper hand 69 of the rheostat to increase the resistance and reduce the high potential electric current intensity to the discharge and attraction blades and to cause a less dense ink deposition on the print receiving material, it being recalled that the wiper hand 69 is mechanically interlocked with the wiper hand 60c of the variable resistance. It will be seen that the wiper hand 600 will also be moved by the rotation of the motor 64 to cut out resistance until the current value flowing through the variable resistance steps up until it is in balance with the output current value of the photoelectric cell 60, whereupon the motor stops. A similar sequence takes place when the output current value of the cell 60 becomes less than the current value flowing through the variable resistance,

such condit on occurring when the reflected light beam acting on the photoelectric cell 60 is reduced in strength. When this happens the grid of the control tube 14 connected to the variable resistance is activated to cause current to flow through the amplifying tube 16 and effect reverse rotation of the motor 61; to move the wiper hand 69 of the rheostat to cut out resistance and thus to increase the intensity of the high potential electric current to the discharge and attraction blades to effect a heavier deposition of ink on the print receiving material. Simultaneously with the movement of the wiper hand 69 the wiper hand (We of the variable resistance moves to increase the resistance and thus decrease the current value flowing to the grid of the tube 14 connected with said resistance until said grid is in balance with the grid connected to the photoelectric cell Bil, whereupon the rotation of the motor 64 terminates.

From the foregoing explanation in connection with Fig. 15a it will be seen that the one series of photoelectric cells scanning the master sheet on the control drum can effectively control the deposition of ink on the print receiving material in coordination with the color values on the master sheet.

As previously stated herein the magnets in the cylinder A of Figs. 1 and 2 could be eliminated and the magnets in cylinder 13 utilized to produce magnetic fields of force acting to transfer the ink from the cylinder A to the print receiving material as fully disclosed in my said Patent 2,224,391. It will be clearly understood that the individual electromagnets in the cylinder B as shown in Figs. 1, 2 and 6 each could be connected by a separate circuit to a source of electrical energy and that the current value of each of such circuits could be controlled to create magnetic fields of varying intensities to control the densities of the ink deposition on the print receiving material. The control of the current values of these separate circuits could be carried out in ways similar to the methods disclosed herein for controlling the intensities of the electrostatic fields of force between the discharge and attraction blades as will be clear to one skilled in the art.

Therefore the present invention contemplates printing by means of a plurality of separate magnetic fields of force the intensities of which are automatically controlled to produce ink deposits on the print receiving material of predetermined densities.

From the foregoing description it will have been seen that an extremely flexible and efficient printing couple results from the use of the present invention and one wherein the volume of ink transferred by the electro fields of force can be controlled to produce ink deposits of predetermined densities on the print receiving material. It will also be noted that the present invention lends itself admirably to a single printing couple capable of producing multicolor printing and wherein the desired and necessary color values can be maintained throughout an entire edition.

Although a number of embodiments of the invention have been illustrated and described herein it will be understood that the invention is susceptible of various modifications and adaptations within the scope of the appended claims.

Having thus described my invention, I claim:

1. A method of printing by utilizing an electro field of force and which comprises passing print receiving material through a printing zone and moving a master chart in timed relation to said l7- material, producing by means of an applied electric current a field of force at the printing zone with the lines of force directed to transfer ink from an ink supply to said material, and varying said current to vary the intensity of said field of force in correlation to said master chart as said material moves through said zone to predeterminately vary the densities of the ink deposits on different areas of said material to produce a printed image or design having varying color shades or densities on diiferent portions thereof as indicated by said master chart.

v 2. A method of printing by utilizing an electro field of force which comprises passing print receiving material through a printing zone and moving a master chart in timed relation to sa d material, producing by means of applied electric currents a plurality of separate fields of force at the printing zone and extending transversely of said material with the lines of force of each field of force directed .to transfer ink from an ink supply to said material, and varying said currents to vary the intensities of said separate fields of force in correlation to said master chart as said material moves through said zone to predeterminately vary the densities of the ink deposits on different areas of said material to produce a printed image or design having varying densities or varying color effects on different portions thereof as indicated by said master chart.

3. A method of printing by utilizing an electro field of force and which comprises passin print receiving material through a printing zone and moving a master chart in timed relation to said material, producing by means of an applied electric current a field of force at the printing zone with the lines of force directed to transfer ink from an ink supply to said material, and maintaining the densities of the ink deposits on different areas of said material in balance with .the color densities on different areas of said chart correlated thereto by varying said current .to vary the intensity of said field of force.

4, A method of printing by utilizing an electro .field of force and which comprises passing print receiving material through a printing zone and' 'field of force which comprises passing print re- -Q ceiving material through a printing zone, and movin a master chart in timed relation to said material, producin by means of applied electric currents a plurality of separate fields of force w at the printing zone and extending transversely of said material with the lines of force of each field of force directed to transfer ink from an :ink supply to said material, and maintaining the densities of the ink deposits on different areas of said material in balance with the color densities on different areas of said chart correlated thereto by varying said currents to vary the intensities of said separate fields of force.

5. A method of printing by utilizing an electro field of force which comprises passing print re-- ceiving material through a printing zone and .moving a master chart in timed relation to said material, producing a plurality of separate electrostatic fields of force at the printing zone and extending transversely of said material with the U lines of force of each field of force directed to transfer ink from an ink supply to said material, and varying the intensities of said separate fields :of force in correlation to said master chart as said material moves through said zone to predeterminately vary the densities of the ink deposits'on different areas of said material to pro- --duce a printed image or design having varying densities or varying color eifects on different 18 portions thereof as indicated by said master chart;

6. A method of printing by utilizing an electro of force and which comprises passing print receiving material through a printing zone and moving master control means in timed relat on to said material, producin by means of an applied electric current a field of force at the print.- in zone bridging a predetermined gap with the lines of force directed to transfer ink across said gap-from an ink supply to said material, and varying said current to vary the intensity of said field of force in correlation to said control means as said material moves through said zone to predeterminedly vary the densities of the ink deposits on different areas of said material to produce a printed image or design having varying COiOl shades or densities on difierent portions thereof and correlated to said control means.

r 7. A method of printing by utilizing an electro eld of force which comprises passing print receivin material through a printing zone and moving a master control means in timed relation to said material, producin by means of applied electric currents a plurality of separate fields of force at the printing zone and extending transversely of said material with the lines of force of each field of force directed to transfer {design having varying densities or varying color effects on different portions thereof and correlated to said control means. 7 r

8. A method of printing by utilizing an electro moving a master control means in timed relation to said material, producing by means of an applied high potential electric current an electrostatic field of force at the printing zone with the lines of force directed to transfer ink from an ink supply to said material, and varying the potential of said current to vary the intensity of said field of force as said material moves through said zone and in correlation to said control means to predeterminedly vary the densities of the ink de-- posits ondifferent areas of said material to produce a printed image or design having varying color shades or densities on different portions 7 thereof.

9. YA method of printingiby utilizing an electro field of force which comprises passing print receiving material through a printing zone and,

moving a master control means in timed relation tosaidmaterial, producing by means of applied high potential electric currents a plurality of separate electrostatic fields of force at the printing zone and extending transversely of said material with the lines of force of each field of force directecl to transfer ink from an ink supply to said material, and varying the potentials of said currents to vary the intensities of said separate fields of force in correlation to said control means as said material moves through said zone to predeterminedly vary the densities of the ink deposits on diiferent areas of printed image or design having varying densities or varying color efiects on different portions thereof.

said material to produce a 10. A method of printing by utilizing an electro field of force which comprises passing print rec'e'iving material through a printing zone and moving a master control means in timed relation with said material, producing by means of applied high potential electric currents a plurality of separate electrostatic fields of force at the printing zone extending transversely of said material with the lines of force of each field of force directed to transfer ink from an ink supply to said material, restricting the effective width of said fields of force by producing magnetic fields of force closely adjacent to and paralleling each side of said electrostatic fields of force, and varying the potentials of said currents to vary the intensities of said separate electrostatic fields of force in correlation to said control means as said material moves through said zone to predeterminedly vary the densities of the ink areas of said material to produce a printed image or design having varying densities or color efiects on different portions thereof.

ll. In a printing couple, ink carrying means, means for moving print receiving material rela- .tive to said ink carrying means and through the printing zone, means for producing by an electric current an electro field of force at the printing zone with the lines of force thereof acting in a direction to transfer ink from said ink carrying means to said material, and means correlated to the movement of said material for automatically varying said current to vary the intensity of said field of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities.

12. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing zone, a plurality of means for producing by electric currents separate electro fiields of force at the printing zone, with the lines of force of each of said fields of force acting in a direction to transfer ink from said ink carrying means to said material, and separate means correlated to the movement of said material for automatically individually varying said currents to vary the intensities of each of said fields of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities.

13. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing-zone, a master control member movable in timed relation to the movement of said material through the printing zone, means for producing by an electriccurrent an electro field of force at the printing zone with the lines of force thereof acting in a direction to transfer ink from said ink carrying means to said material, and means operatively controlled by said control member for varying said current to vary the intensity of said field of force as said material moves.

through the printing zone toproduce ink deposits on said material of predetermined varying density and correlated to said control member.

14. In a printing couple, ink carrying means,

means for moving print receiving material relative to said ink carrying means and through the printing zone, a master control member movable in timed relation to the movement of said material through the printing zone, a plurality of separate meansfo'r producing separate electro fields of force at the printing zone with the lines of force of each field of force acting in a direction to deposits on different transfer ink from said ink carrying means to said material, and separate means operatively controlled by said control member for varying the intensities of said separate fields of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities correlated to said control member.

15. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing zone, a master control member movable in timed relation to the movement of said material through the printing zone, means for producing by an electric current an electrostatic field of force at the printing zone with the lines of force thereof acting in a direction to transfer ink from said ink carrying means to said material, and means operatively controlled by said control member for varying said current to vary the intensity of said field of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities correlated to said control member.

16. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing zone, a master control member movable in timed relation to the movement of said material through the printing zone, separate means for producing a plurality of separate electrostatic fields of force at the printing zone with the lines of force of each field of force acting in a direction to transfer ink from said ink carrying means to said material, and separate means operatively controlled by said control member for varying the intensity of each of said fields of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities.

17. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing zone, separate means for producing by electric currents a plurality of separate electro magnetic fields of force at the printing zone with the lines of force of said field of force acting in a direction to transfer ink from said ink carrying means to said material, and means correlated to the movement of said material for automatically varying said currents to vary the intensities of said fields of force as 'said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities.

18. In a printing couple, ink carrying means, means for moving print receiving material relative to said ink carrying means and through the printing zone, separate means for producing by electric currents a plurality of separate electrostatic fields of force at the printing zone with the lines of force of said fields of force acting in a direction to transfer ink from said ink carrying means to said material, means for'producing magnetic fields of force on each side of said electrostatic fields of force to prevent dispersion of the latter and to confine the'same to'theprinting zone, and separate means movable in 'correlation to the movement of said material for automatically varying said currents to vary'the intensities of each of said electrostatic fields 'of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying densities.

l tions of said member determined varying densities can be made said material, in timed relation with said movable member and and including spaced having image portions adapted to be inked, means for moving print receiving material in operative and timed relation to said member and through the printing zone, means for producing by an electric current an electro field of force at the printing zone with the lines of force of said field of force acting in a direction to transfer ink from said image portions of said member to said material, and means correlated to the movement of said material for automaticallyv varying said current to vary the intensity of said electro field of force as said material moves through the printing zone, whereby the ink deposits on said material may be of predetermined varying densities.

20. In a printing couple, a printing member having image portions adapted to be inked, means for moving print receiving material in operative and timed relation to said member and through the printing zone, separate means for producing by electric currents a plurality of separate electro fields of force at the printing zone with the lines of force of said fields of force acting in a direction to transfer ink from the image porto said material, and separate means movable in correlation to the movement of said material for automatically varying said currents to vary the intensities of each of said fields of force as said material moves through the printing zone, whereby ink deposits of preon said material.

21. In a printing couple, a movable member having image portions adapted to be inked, means for moving print receiving material in operative and timed relation to said member and through the printing zone, separate means for producing a plurality of separate electro fields of force at the printing zone with the lines of force of said fields of force acting in a direction to transfer ink from the image portions of said member to a master control member movable said material, and separate means operatively controlled by said control member for varying the intensities of each of said electro'fields of force as said material moves through the printing zone, whereby ink deposits of predetermined varying densities can be produced on said mate rial correlated to said control member.

22. In a printing couple, a movable member having image portions permeable to lines of force and non-image portions impermeable thereto, means for moving print receiving material in operative and'timed relationship to said member and through the printing zone by an electric current, means for creating at the printing zone an electro field of force with the lines of force thereof extending through said material and the permeable image portions of said member but intercepted by the impermeable portions thereof discharge and attraction elements located inthe printing zone on opposite sides of said material andsaid member, means for introducing ink to said field of force to be carried by the lines of force to areas of said material correlated to said image portions of said member, and means correlated to the movement of said material for automatically varying said current to vary the intensity of said field of force to produce on said material as it passes through the printing zone ink deposits of predetermined varying densities.

23. In a printing couple, a movable member having image portions permeable to lines of force and non-image portions impermeable thereto,

means for moving, print receiving material in operative and timed relationship to said member and through the printing zone by electric currents, means for creating at the printing zone a plurality of electro fields of force with the lines of force thereof extending through said material and the permeable image portions of said member but intercepted by the impermeable portions thereof and including a plurality of sets of spaced discharge and attraction elements located in the printing zone with the discharge and attraction elements of each set on opposite sides of said material and said member, means for introducing ink to said fields of force to be carried by the lines of force to areas of said material correlated to said image portions of said member, and separate means acting in correlation to the movement of said material for automatically varying said currents to vary the intensities of each of said fields of force to produce on said material as it passes through the printing zone ink deposits of predetermined varying densities.

24. In a printing couple, a movable member having image portions permeable to lines of force and non-image portions impermeable thereto, means for moving print receiving material in operative and timed relationship to said member and through the printing zone, means for creating at the printing zone an electro field of force with the lines of force thereof extending through said material and the permeable image portions of said member'but intercepted by the impermeable portions thereof and including spaced discharge and atti action elements located in opposite sides of said material and said member, means for introducing ink to said field of force to be carried by the lines of force to areas of said material correlated to said image portions of said member, a master control member movable in timed relation to said movable member, means for projecting light beams onto said control member to be reflected thereby, light sensitive means activated by the reflected light beams, and means controlled by the degree of activation of said light sensitive means for varying the intensity of said fieldof force in relation to the strength of the reflected light beams to produce on said material as it passes through the printing zone ink deposits of predetermined varying densities.

25. In a printing couple, ink carryingmeans, means for moving print receiving material relative to said ink carrying means and through the printing zone, a master control member movable in timed relation to the movement of said material through the printing zone, means for producing an electro field of force at the printing zonewith the lines of force thereof acting in a direction to transfer ink from said ink carrying member to said material, means for projecting light beams against said control member to be reflected thereby, light sensitive means activated by said reflected light beams, and means controlled by said light sensitive means for varying the intensity of said field of force in relation to the strength of the reflected light beams to cause ink deposits on said material of predetermined varying densities.

.o 26. In a printing couple, an ink carrying member, means for moving print receiving material relative to said member and through the printing zone, a master control member movable in timed relation to the movement of said material through the printing zone and provided with different areas of predetermined color density,

the printing zone on means for producing an electro field of force at the printing zone with the lines of force thereof acting in a direction to transfer ink from said ink carrying member to said material, and means for maintaining the densities of the ink deposits on'said material correlated to the color densities of said areas on said control member and including separate means for projecting light beams on said areas of said control member and on saidink deposits on said material to be reflected thereby, separate light sensitive means activated by said reflected light beams,

and means controlled by an unbalanced activation of said light sensitive means for varying the intensity of said field of force.

27. In a printing couple, an ink carrying member, means for moving print receiving material relative to said member and through the printing zone, means for producing an electro field of force at the printing zone with the lines of force thereof acting in a direction to transfer ink from said ink carrying member to said material and including an electric circuit, and means for varying the intensity of the current of said electric circuit and hence the intensity of said field of force as said material moves through the printing zone to produce ink deposits on said material of predetermined varying density and including a master control member movable in timed relation to the movement of said material through the printing zone and provided with switch actuating elements arranged thereon in predetermined manner, resistance means adapted to be selectively introduced into said circuit, and switch means actuated by said elements for introducing said resistance means into said circuit.

28. In a printing couple, a rotatable cylinder provided with image portions permeable to lines of force and non-image portions impermeable thereto, mearm for moving print receiving material through the printing zone and relative to said cylinder with said material supported thereby, a series of discharge blades extending transversely of said material and located on one side thereof at the printing zone, a series of attraction blades located within said cylinder and in the plane of said series of discharge blades with each attraction blade cooperating with a correlated discharge blade to form a plurality of sets of discharge and attraction blades, means for inking said discharge blades, separate means for connecting each set of discharge and attraction blades with a source of high potential electric energy to induce an electrostatic field of force between said blades with the lines of force thereof passing through said material and the permeable image portions of said cylinder and acting to transfer ink from said discharge blade to said material, a master control member movable in timed relation to said cylinder and said material and provided with areas of different predetermined color densities, light sources for projecting light beams onto said areas of said control member to be reflected thereby, light sensithe print receiving tive means scanning the control member and re ceiving the reflected light beams and activated thereby, and means operatively controlled by said light sensitive means for varying the intensities of the fields of force between the sets of discharge and attraction blades to vary the densities of the ink deposits on the print receiving material in correlation to the color densities of said areas on said master control member.

29. In a printing couple as defined in claim 28 and wherein light jecting light beams onto the ink deposits on the print receiving material to be reflected thereby, while light sensitive means scan said deposits and receive the said reflected light beams and are activated thereby, the light sensitive means which scan the control member and the light sensitive means which scan the ink deposits on the material conjunctively controlling the means which vary the intensities of the electrostatic fields of force.

30. In a printing couple, a rotatable cylinder provided with image portions adapted to be inked, a series of radial discharge blades extending longitudinally within said cylinder, means for moving print receiving material through the printing zone and in operative and timed relation ship to said cylinder, a similar series of attraction blades located in the plane of said series of discharge blades and on the side of said material remote from said cylinder with each attraction blade cooperating with a discharge blade to form a plurality of sets of discharge and attraction blades, separate means for connecting each set of blades with a source or high potential electric energy to induce an electrostatic field of force between the blades of each set with the lines of force thereof acting in a direction to transfer ink from the image portions of the cylinder to material, a master control member movable in timed relation to said cylinder and said material and provided with actuating elements correlated to the sets of discharge and attraction blades and arranged on said control member in predetermined manner, and means actuated by said elements to vary in a predetermined manner the intensities of the fields of force produced by said sets of discharge and attraction blades to effect ink depositions on the material of predetermined varying densities.

WILLIAM C. HUEBNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,275,642 Bechman Aug. 13, 1918 1,568,651 Bryson e Jan. 5, 1926 2,152,077 Meston Mar. 28, 1939 2,183,720 Lougee Dec. 19, 1939 2,224,391 Huebner Dec. 10, 1940 2,447,374 Smyser Aug. 17, 1948 sources are provided for pro,- v

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