DE2257150A1 - METHOD AND DEVICE FOR IMPACTLESS PRINTING WITH LIQUID INK - Google Patents

Description

üattelle Memorial Institute,
Carouge-Geneva (Switzerland)

Method and device for seamless printing with liquid ink

The invention relates to a method and an apparatus for seamless printing with liquid ink, in particular for creating print samples by selectively attracting Color on a conventional printing substrate made of ordinary paper or the like Print patterns are formed.

The invention can be used for those taking place in printed form Use to transmit information received in the form of electrical signals from some external data source were, for example, printed texts or curves corresponding to the information output from computers, electronic Desktop computers, measuring devices, telegraph or teletype receivers and of devices for image transmission, facsimile printing or the like. to be provided.

there are various known, impactless printing devices, based on their common principle of selective deposition of stationary electrical charges the surface of a dielectric carrier medium in

- 2 -

9 072/0875

- ² - '2257Ί50

Mood with desired printing patterns are based to thereby generate a latent electrostatic image, which is then used for the transfer of ink by electrostatic attraction from an ink-bearing part to a printing substrate such as ordinary paper or the like. These two distinct steps of image formation and color transfer have certain limitations in terms of high-speed, high-resolution printing.

For example, Jo requires the generation of a satisfactory latent image at high speed the application of complicated measures to ensure a precisely localized one Deposition of electrical charges on your picture carrier and to prevent migration and thus dissipation of the charges in the medium that forms it. It also makes the subsequent transfer of the color to the printing substrate precise positioning of the printing substrate relative to the latent image is required by means of the image mentioned, As a result, the aforementioned two-step process is subject to image formation on the one hand and image formation on the other Color transfer, while it may be suitable for certain applications, imposes certain limitations on the Consistency and quality of the imprint samples that are available for quick printing.

In order to avoid some of these limitations, a printing method has been proposed in which the aforementioned dielectric support medium for the latent image consists of a porous belt from which the latent image is formed on one side and the ink is applied on the other side so that an attraction of the paint through the pores of the tape is caused by the electrostatic charges of the image. A color pattern is generated for subsequent transfer onto a sheet of paper or the like by touching the same with the color image. The dielectric carrier medium thus simultaneously forms a carrier for the latent image and a color donor _, however

- 3 309822/0876

Printing involves three consecutive steps, namely image formation, surface ink attraction, and ink transfer to the paper by touch printing. Such a procedure is subject to various restrictions, especially with regard to the control of the selective color transfer at high speeds.

A printing device has also been proposed in which an electrically insulating printing ink is held in an electrically insulating, cylindrical grid ". It is comprised furthermore a device for negatively charging the paint in accordance with an electrostatic pattern and one positively charged drum that brings a printing substrate into contact with the grid in order to transfer the color to the Printing pad in accordance with the electrostatic cough due to the between the negatively charged ink and to allow electrostatic force to be exerted on the positively charged drum. However, it is one of these Arrangement difficult to create a very precise electrostatic pattern by selective charging of the paint and to ensure precise control of the color transfer only from the individual selected points in the raster as well as to ensure that no random color transfer can occur when the screen and the printing material are in contact with each other.

In a proposed modification of this device the color retained in the insulating grid is uniformly charged positively, and the device comprises a device for the negative charging of the printing substrate corresponding to an electrostatic cough as well as' means for the Movement of the printing substrate in contact with the grid for the purpose of transferring the positively charged color to the Printing base in accordance with the electrostatic riuster through which between the ink and the printing base applied electrostatic force. The aforementioned problems

A {} $ ?, '? 7 I 0 8 7 6

ensuring precise control of the ink transfer and the prevention of arbitrary color transfer nevertheless remain the same with this modification.

The main object of the invention is to achieve high-speed printing with liquid ink that is carried out without interruption, with the greatest possible extent To avoid the disadvantages and limitations mentioned above.

Another object of the invention is to enable a controlled attraction of the paint so that one with high speed color transfer is provided for printing color dots of a predetermined size.

Furthermore, it is an object of the invention to quickly produce print patterns which have a high resolution, it being possible to produce printing color dots of sharp delimitation, their size can be varied within certain limits while maintaining the same printing process.

The invention is also intended to provide high quality facsimile printing be provided in such a way that dots of different sizes are printed so that a progressive Tone gradation can be provided in the print image.

Finally, the invention is intended to provide a device for completely eliminating any uncontrolled color transfer provided during the printing process.

To achieve these objects, the invention consists in a method for non-impact printing with a liquid ink on an arcuate dielectric printing pad made of ordinary paper or the like. consists by creating colored dots thereon in accordance with printing signals corresponding to a printing pattern, this method comprising the steps of:

- 5 -

3 0HH22 / 087B

- Arrangement of the printing substrate between an electrically conductive, perforated ink carrier and at least one Electrode, the ink carrier having an electrically conductive ink in a plurality of capillary perforations passing through it of the same size and also with a correspondingly perforated ink-repellent Layer is provided which is arranged so that it is opposite to the one surface of the printing substrate, and wherein the electrode is disposed adjacent the opposing surface of the pad and selectively aligned with one of the capillary perforations;

- Maintaining the color carrier at a constant potential; and

- Applying a (voltage pulse of a given amplitude and short duration to the electrode corresponding to one of the pressure signals, in such a way that momentarily a localized an electric field of predetermined intensity is generated between the electrode and the ink carrier, thereby creating a selective attraction of paint from the one perforation aligned with the electrode and thereby a color point of a predetermined size is printed on one surface of the printing substrate.

The invention also relates to an apparatus for printing with liquid ink on a sheet-like dielectric Printing base by creating color dots thereon in accordance with printing signals corresponding to a desired one Printing samples, said device comprising:

- a perforated, electrically conductive paint carrier,

on one oeite a correspondingly perforated one Color-contrasting Lc is not arranged, with a reciprocating number by ilapilLarperlOrations of the same size that

-G-
: U) U t:> Ί / 0 8 1 ß

enforce the paint carrier and hold a conductive paint by capillary action;

- A device for maintaining a constant predetermined potential of the ink carrier;

a printhead comprising at least one electrode which is sized such that it is selectively positioned opposite no more than one of the capillary perforations at any one time;

- guiding means, which the relative arrangement of the ink carrier, allow the printhead adjacent, the printing pad is arranged therebetween in such a way that a their surfaces opposite the ink-repellent layer and that the electrode is adjacent to the opposite is located above the surface of the printing pad and in alignment with one of the perforations;

- Means for supplying the print signals to the print head in the form of short voltage pulses of predetermined amplitude and lower in order to momentarily generate a localized electric field of predetermined intensity which extends between the electrode receiving the pulse and the ink carrier in such a way that it enables a selective color transfer from the selected perforation and thereby produces the imprint of a color point of predetermined size as a result of the color transfer onto the printing substrate.

Various aspects of the invention and its particular meaning the combination of their factory features can be found in the following description with reference to the drawing show m this:

Fig. 1 is an overview of the general arrangement a printing device according to one embodiment

~ 7 -30 90 2 2/0 8 7 δ

the invention;

FIG. 2 shows a sectional plan view along the line II - II in FIG Removal of the ink carrier;

3 shows a section along the line III - III in B ¹ Ig. 1;

FIGS. 4a and 4b show the pressure zone of that illustrated in FIG Printing device before or during the ink absorption; and

'S -

Figs. 5 to 11 are test graphs showing the mutual relationships of various types for printing according to reflect important parameters of the invention.

In the general arrangement illustrated, for example, in Figure 1, the printing device comprises According to this embodiment, an ink carrier in the form of a perforated ink ribbon 1, which is an endless Forms a loop, which around three pairs of rollers 2a, 2b; 3a, 3b; and 4a, 4b moved past a stationary print head 5 is, with a printing pad in the form of a paper strip 6 between the ribbon and the print head is arranged.

As can be seen from FIGS. 2 and 3, the rollers are closed within those formed by the ribbon 1 Loop arranged to guide the ribbon along its side edges, with the rollers of each pair respectively are arranged on a common axis 7, 8 and 9. The rollers 3a, 3b. Form drive rollers, the common Axis 8 is in wiriamgsverbindungen with a drive system 10, while the rollers 2a, 2b and 4a, 4b Represent guide rollers which are arranged freely rotatable on their common axes 7 and 9. This lead

- 3 -

3 09822/0876 "

Approximation and drive rollers consist of narrow drums, at least the pair of rollers 4a, 4b made of metallic "Material is made to have a ground connection via the axis 9, as shown schematically in Fig. 1, to enable.

The ribbon 1 moving in this way is arranged in the direction of the arrow shown in Fig. 1, contains a plurality of closely spaced Capillary perforations 11, which are arranged evenly in transverse and longitudinal rows and extend through the Extend the ribbon in the zone that lies between the rollers. The texture of the ribbon is enlarged Cross-section illustrated in Figure 4 and will be described in more detail below with reference thereto Figure described.

The printing device is further provided with an ink supply device 12, which is illustrated schematically by a spray head, by the color on the Inner surface of the endless ink ribbon 1 is distributed and sucked into the perforations 11 by capillary action, a doctor blade 13 is also provided adjacent to the inner surface of the ink ribbon to guide the introduction of the To support paint in the ribbon 1 and to strip off excess paint from its inner surface.

The printing paper strip 6 is pulled from a supply roll and fed to a take-up roll 15, whose Axis is also operatively connected to the drive system 10 so that a synchronized movement of the Ribbon 1 and the paper strip 6 past the print head 5 is made possible.

The print head 5 comprises a block 16 made of insulating material

l _ Q _

3 0 9 8 2 2/0 8? B.

rial, which has a curved upper surface, which serves as a guide surface for precise positioning of the paper strip serves against the ribbon 1 during its passage through the print zone, which is in the center plane of the Is arranged printhead.

The printhead 5 also includes a rectilinear transverse arrangement of seven electrodes 17, which are embedded in the insulating block 16 and located in its central plane extend in the vertical direction up to its upper curved surface, and a contact of these electrodes 17 takes place with your paper strip 6 during its run over the Block 16. ·

The seven electrodes 17 are each .. one of the. in Allocated longitudinal rows of perforations 11, and form a transverse to the direction of movement of the Ribbon 1 extending row; they are arranged so that the perforations ■ a longitudinal row of perforations over the associated electrode is running.

A pulse generator 18 is also connected to the electrodes 17 of the print head 5 and is capable of supplying each of them with print signals ΰ corresponding to a desired print pattern, which occur in the form of voltage pulses of a given amplitude and short duration in order to control the printing of color dots in a more descriptive manner Way to enable.

The drive system 1Ü is in operative connection with the ink ribbon and the paper strip, so that both pass the print head in synchronism and the transverse rows of seven perforations 11 one after the other to align with the corresponding electrodes 17, as shown in Fig. 5 can be seen to be brought .

- 10 -10 OV 11/0 81 B ■

- 1 night -

The drive system Iu can have any drive means include, e.g. an iilektromctor that works with a Iransmissioriseinriciitung, e.g. a toothed gill gear system is equipped.

This motor can either be a constant speed motor to ensure that the ribbon moves evenly 1 and the paper strip o, both with the same Running speed, or even a stepper motor that has a synchronized stepping movement provides, wherein the ribbon 1 and the paper strip stand still between successive steps to the Allow color transition.

As different drive systems for the precise movement of the High speed tapes are well known in the printing apparatus and other fields, and the special design and arrangement of the same can thus be quite conventional, the drive system was only illustrated schematically by block 10 and shall not be described in further detail. The pulse generator 18 may also comprise any circuit of conventional design capable of selectively actuating each of the electrodes 1? of the printhead a sequence of printed signals S in Form of voltage pulses of controlled amplitude and. Duration supplied according to the data which correspond to a desired draft program. These dates can be used by some external programming device, e.g. a computer. Since the pulse generator 1b can be of any conventional design and does not need to form part of the actual printing device, but without further ado a part of the printer programming device can be, it was demonstrated by Block 1ö-

UR X / / 0 8 7 6

light and is not described in detail.

The nature of the ribbon 1 and its relative ' Arrangement opposite the paper strip 6 and the print head 5 are shown in an enlarged cross-section in Pig. 4a and 4b which show an enlarged sectional view of the print zone before or during the printing process. That Ribbon 1 consists of a perforated, metallic, color-bearing tape IA, with a correspondingly perforated, ink-repellent layer IB on the outside of the endless loop formed by him is provided. The perforations 11 contain an electrically conductive ink that is held therein by capillary action, like much is indicated schematically in Fig. 4a by the liquid column 20. The ribbon 1A must be electrically conductive and may be made of, for example, stainless steel, nickel, copper, or aluminum, whichever is well known in the printing art physical or chemical treatment is made wettable (water-absorbing). On the other hand, the layer 1B paint repellant, and any known water repellant coating material such as polytetrafluoroethylene ("Teflon") or certain silicone compounds, can be used for the Use formation of this layer, for example by spraying on the perforated metallic ink ribbon 1A. However one can also think of applying the conductive ink ribbon 1A to a surface treatment such as electrolytic polishing, subjected to water-repellent properties on its surface. However, the choice is special Materials and techniques that are used to produce the perforated ink ribbon, as long as they are not critical, than the ink ribbon 1A is electrically conductive and wettable by ink used for printing, while the Layer 1B is relatively non-wettable by color.

- 12 -

309Ö22 / 087

As can be seen from FIGS. 4a and 4b, the ink-repellent layer 1B lies between the conductive ink ribbon 1A and 1A the printing paper strip 6, and it has been put into practice found that this is a remarkable thing in terms of obtaining flawless prints at high speed Result. As will be explained below, experimental results have consistently shown that color transfer can be precisely controlled to enable the printing of color dots of a given size at high speed. However, the exact effect of the ink-repellent layer 1B cannot be fully understood in this connection explain.

It is also readily apparent that there are various parameters that influence the behavior of the color during can influence their transmission at high speeds, so that a correlation of all these parameters is very high difficult, if at all possible.

The following explanation with reference to Figs nevertheless shows the influence of various parameters that were determined experimentally and thus a consideration this parameter enables to achieve satisfactory color transition control at high speed.

Fig. 4a shows various system parameters related to the dimensions of the composite ribbon 1 and its Arrangement opposite the printing substrate (paper). These parameters are:

- diameter 0 of the perforations 11;

- thickness h. the conductive tape 1A;

- Thickness h ^ of the color repellent layer 1B;

- thickness h of the printing substrate;

9 822/0876

- Distance χ between layer Ί'Β and the printing substrate (paper 6).

Fig. 4b shows three successive perforations one Longitudinal row, with the first and third perforations containing paint in equilibrium under the capillary action, while the ink from the second perforation is attracted to its transfer to the paper.

As also from B ¹ Ig. 4a and 4b, the ink ribbon 1 is furthermore provided with spacers 21 which are attached to the conductive tape 1A and protrude through the layer 133 so that they come into contact with the paper 6 and thus the distance χ (cf. 4a) determine between him and the layer 1B.

The perforations 11 of the ribbon 1 all have the same size and can either be cylindrical (constant diameter), or, as can be seen on the left in FIGS. 4a and 4b, one according to the free (inner) surface of the Ribbon 1A, where paint is supplied by the supply device 12 (Fig. 1), have increasing cross-section.

The use of such perforations with increasing cross-section has proven to be advantageous in terms of introduction the color and its retention in the perforations proved by capillary action by breaking the meniscus Color is formed and held at the point of the perforation which has the smallest diameter. Figure 4a and 4b are only intended to show a principle model, but experimental results show that the B'arb meniscus is deformed and deformed in the manner generally illustrated very schematically in these figures behaves.

So if there is liquid paint on the surface of the ^ conductive

-14-

309 8 22/087

Ribbon 1A is spread out, it enters the perforations 11 and is retained therein by capillary action, as shown essentially in Fig. 4a, the composite Ribbon 1 thus ensures that the color is held within its perforations and thereby prevents an uncontrolled Color transition. Furthermore, if a voltage pulse 3 of sufficient amplitude V and duration t is applied to the electrode a localized electric field is momentarily created therebetween and the meniscus of the paint is attracted and thereby deformed in the axial direction so that it protrudes from the layer 1B for contact with your paper, to effect the color transfer thereon, as shown schematically in Fig. 4b.

The extent of the deformation of the color meniscus will apparently depend on various parameters such as; on the attractive potential V, the diameter 0 of the perforation, the distance over which the meniscus _{must be shifted for the purpose of contact of the ink with the paper (h ß} and χ possibly go to zero), the duration of the attraction of the surface tension <5 ~ and the viscosity M of the paint.

The influence of these parameters will be explained below with reference to the experimental results illustrated in Figs explained.

The curve according to FIG. 5 shows the change (for 0 = 0.2 mm) the maximum air gap χ (Fig. 4a), the color transition on the paper as a function of the color-attracting potential V allowed, i.e. the amplitude of the voltage pulse applied to the electrode, the duration t of the pulse being constant remains at 9.5 ms. The ribbon 1A used here is made of copper and has a thickness h. of 0.1 mm, while the ink-repellent layer 1B is made of "Teflon"

30 9 822/087 5.

and a thickness h. of 0.05 mm. One based on water manufactured paint of a commercial type was used, which has a surface tension (T of 39 dyn / cm and has a viscosity / U of about 1 cp.

The areas below this experimental curve according to FIG. 5 give all values of V and χ in the considered Areas of the same again, which allow a color transfer.

The three curves according to FIG. 6 show the change in the gap dimension χ for three color-accepting potentials Y as a function of the diameter 0 of the perforations 11. Both the color used and the materials and Thicknesses L and h "of the ink ribbon are the same as above with respect to FIG. 5 indicated.

The areas lying under these three experimental curves according to FIG. 6 therefore give in the area under consideration all permissible fourths of χ and 0, which enable the color transition with the corresponding values of V.

The curves according to FIGS. 7 and 8 show the influence of the viscosity / U and the surface tension & of the color on the minimum potential V which is required to achieve the color transition. In both cases a composite copper "Teflon" color ribbon was used with 0 = 0.2 mm, h, _v = 0.1-min and JbL, = 0.05 mm. Furthermore, the surface tension 6 ″ is constant at 68 dynes / cm for the paint used for the curve of FIG. 7, while the viscosity / U of the paint is constant at 1 cp in the paint used for the curve of FIG The duration t of the voltage pulses was again 9.5 ms.

The curves according to FIGS. 5 to 8 thus allow a suitable one

- 16 -

3 0 9 B 2 2/0 8 1 p

Selection of the applitude V of the voltage pulses required for the printing process as a function of 0, x, tr and / U.

It should be noted that reducing the size of the gap χ appears to be beneficial in that it is reducing allowed by V, so that the gap can be left out at all. Experiments have shown that no gap may be required provided the surface tension of the paint is sufficiently high (e.g. 50 dynes / cm or more) and the conductive tape 1A is very large easily wettable by the paint, in contrast to the paint-absorbing layer 1B. However, the application seems a small height gap of up to about 0.1 mm is advisable for various practical reasons, in particular when the ink ribbon and the printing sheet are moved at high speed during the printing process.

It should also be noted that the duration t «9.5 ms des The voltage pulse used in determining the experimental curves of FIGS. 5 to 8 is much higher was considered to be the minimum "response time" required for color transfer. However, the minimum pulse duration depends required for printing depends on various dimensional and operational parameters as well on the properties of the color, and is therefore difficult to determine for all cases. However, research has shown that the pulse duration t can be reduced to 4.5 ms without that illustrated in FIGS Relationships are changed significantly. Furthermore, printing of the color dots has been found to be satisfactory in practice reached with values of t that were only 0.1-0.2 ms.

printed color points as a function of V, t and x, if

9, 10 and 11 show the change in size 0 _d of

.on of

- 17 309822/0178

the same color is used with <T = 39 dynes / cm and / U = 1 cp will.

Fig. 9 shows three curves which represent the point size 0 as a function of V "and a t = 9.5, 4.6 and 0.4 ms (for 0 = 0.2 and χ = 0.04 mm). The curves of Figures 9 and 10 (same color band and color) show that is, the influence of the pulse duration t on the point size 0 £ in the area under consideration is considerable.

11 shows the influence of the gap size χ on the point size 0 ^ for t = 9.5 or 0.4 ms (for 0 = 0.3 mm, h _A = 0.1 mm, h _B '= 0 , 04 mm and V = 1750 V). So this figure shows that the gap size is also an important parameter with regard to the point size 0, which is between 0.2

and 1.4 mm in the curve of FIG. 11 varies.

The ink used for printing according to the invention must be electrically conductive, but its conductivity is not critical and can vary over a wide range. Any polar solvent based Paint, e.g., a water-based paint, can be used for the purposes of the invention.

The above-described quality of the ribbon that Placing the conductive ink ribbon a short predetermined distance from the surface of the paper to be printed and the described assignment of the electrodes to this arrangement, which are capable of receiving pressure signals from a Data source to receive which the form more precisely High voltage pulses of short duration have to attract the color from the tape to the paper when they deliver can be combined in the manner described, a special result.

■. - 18 -

309822 / 087.6

This result can be illustrated by the following advantages will:

a) The conductivity of the ribbon as well as that of the paint makes it possible that normally all of ink carried on the ribbon is held at exactly the same potential, e.g., zero potential as described;

b) the layer having an ink-repellent surface acts on the lateral spread of the ink outside the color-bearing perforations on the underside of the ribbon, which is the surface of the receiving print Paper is opposite, and so tries to keep the color within the ribbon, so that an uncontrolled Color transition is prevented in the absence of an electric field acting on the color, while a momentary one Deformation of the meniscus contained in the perforation for contact with and transfer of ink to the paper is made possible when a voltage pulse is applied to an electrode located on the opposite side of the Paper is aligned with the meniscus.

The fact that the color dot size is easily controlled by adjusting the amplitude or duration of the pressure signal allows the size of each individual dot to be changed considerably without having to change the printing device something needs to be changed.

So alphanumeric characters of different sizes can be printed while the line width is without further can be adapted to any character.

Furthermore, the advantages of the invention are in no way limited to the printing of alphanumeric characters. Indeed the possibility of easily changing the point size allows the rapid printing of complex print patterns with contours of gradually changing thickness,

- 19 309822/0876

while at the same time a great sharpness and resolution is guaranteed.

It should be noted that the embodiment described was given as an example and that the invention can easily be realized in other embodiments is where various components of the printing device and their interrelationships are essential are modified with respect to the objects described above and illustrated in the drawing.

For example, any perforated color donor of a similar nature can be used in place of one endless belt, while the printing substrate does not have to be a continuous strip or a band, but must be made up of a .paper sheet ο. Like. Can exist.

While a transverse row of electrodes has been shown and described, an arrangement can also be used each comprising the desired number of electrodes. For example, a straight arrangement of 7x5 electrodes can be used for the Printing one alphanumeric character at the same time can be used instead of performing five consecutive ones Steps as shown. Indeed, any number of arrangements can be used to print multiple characters at the same time. Such duplication of the electrodes would obviously be one enable a corresponding increase in the speed at which the characters are printed. A straight one Electrode arrangements extending the width of a sheet of paper can also be used, e.g. when the paper is moved past this arrangement in a direction perpendicular thereto. In this case it can the ink carrier can be a composite, perforated tape or sheet of this type, which is either stationary or

- 20 -

309822 / 087S

is movable, depending on the arrangement used.

The ink ribbon as well as the printing pad can also be stationary while the printhead is during printing describes a scanning movement above it.

Claims - 21 -

309822/0876

Claims (12)

Claims Process for seamless printing with liquid ink on a curved, conventional printing substrate, made of ordinary paper or the like. consists, by creating pressure points thereon in accordance with print signals corresponding to a desired print pattern correspond, marked ' through the following steps: - Arrangement of the printing pad between an electric conductive, perforated ink carrier and at least one electrode, -which, the .color carrier an electrical contains conductive paint in a plurality of equally sized capillary perforations penetrating it and also with an appropriately perforated color-repellent end Layer is provided which is arranged so that it is opposite to the one surface of the printing substrate, and wherein the electrode is disposed adjacent the opposite surface of the pad and is selectively aligned with one of the capillary perforations; - Maintaining the ink carrier on a constant Potential; and - Applying a voltage pulse of a given amplitude and short duration to the electrode corresponding to one of the pressure signals, in such a way that momentary a localized electric field of predetermined intensity is generated between the electrode and the ink carrier thereby creating a selective attraction of color to the one perforation aligned with the electrode is generated and thereby a color dot of a predetermined size on the one surface of the printing - 22 i 309822/0876 is printed. 2. The method according to claim 1, characterized through the steps: - Using a perforated metal strip as a paint carrier, with the paint-repellent layer on the one side thereof is arranged, and with an arrangement of the capillary perforations in the tape in a plurality of longitudinal rows; - Using a linear array of electrodes at a given short distance from the belt in the Way that a selective alignment of at least one electrode of the assembly with the perforations of each Longitudinal row is made possible, with the printing pad in between; - Providing a relative linear movement of the tape and the printing pad with respect to the electrode arrangement in such a way that the electrodes are sequentially aligned with the capillary perforations of the get the corresponding row and enable a selective color transfer from it; and - Applying the voltage pulses selectively to the electrodes of the arrangement while they are in alignment with them selected capillary perforations in the .Weise that pressure points on the printing substrate in accordance can be printed with the desired print pattern. 3. The method according to claim 1, characterized in that that the amplitude of the voltage pulses to control the size of each print point is adjustable. - 23 - 309822/0875 4. The method according to claim ^ 1, characterized in that the period of time the voltage pulse is adjustable to control the size of each color dot; 5. The method according to claim 1, characterized in that that the amplitude and. the duration of the voltage pulses for the purpose of control the size of the color dots "are adjustable. 6. The method according to claim 1, characterized g e ke. nn indicates that during the ink transfer, the printing substrate is in a short, a predetermined distance from the ink-absorbing layer. 7. The method according to claim 6, characterized in that the ink carrier with Spacer elements is provided, die.so arranged are that they protrude from the ink-repellent layer 'to with one surface of the printing substrate to get in touch. 8. Apparatus for practicing the method according to claim for printing with a liquid ink on an arc-shaped dielectric printing sheet by forming color dots thereon in accordance with a desired print pattern corresponding print signals, characterized by; - A perforated, electrically conductive paint carrier (1A), on which on one side a corresponding perforated ink-repellent layer (1B) is arranged, with a plurality of capillary perforations (11) of the same size as the ink carrier (1A) - 24 - 309822/0875 enforce and hold a conductive paint by capillary action; - A device for maintaining a constant predetermined potential of the ink carrier (1A) ₁ - A print head (5) which comprises at least one electrode (17) which is of such a size that it is in not more than one of the capillary perforations (11) is selectively arranged at a point in time; - Guide means (2a, 2b; 3a, 3b) which adjoin the relative arrangement of the ink carrier (1a) to the print head (5) allow, wherein the printing pad (6) is arranged therebetween in the V / s that one of their Surfaces of the ink-repellent layer (1B) opposite and that the electrode (17) is adjacent the opposite surface of the printing pad (b) and aligned with one of the perforations (11); - A device (13) for supplying the print signals to the print head (5) in the form of short voltage pulses of predetermined amplitude and duration to instantaneously generate a localized electric field of predetermined To generate intensity between the pulse receiving electrode (17) and the color carrier (IA) extends in such a way that there is a selective color transfer from the selected perforation (11) enables and thereby the printing of a color point of a predetermined size as a result of the color transfer generated on the printing substrate (6). 9. Apparatus according to claim 8, characterized in that - 25 - 309822/087 & - The ink carrier consists of a perforated metal band (1A), on one side of which the ink-repellent Layer (1B) is arranged and the at least one longitudinal row of capillary perforations (11) having; - the electrode (17) of the printhead (5) in the same Level is arranged like the longitudinal row of perforations (11); and - the device comprises drive means (10) connected in this way to the guide means (3a, 3b) are that they have a relative movement between the print head (5) and both the ribbon (1A) and 'Provide the printing substrate (6) in such a way that the perforations (11) of the row successively 'come into alignment with the electrode (17) and this enables selective printing of color dots on the printing substrate (6) at any point in time by applying one of the voltage pulses to the electrode during the alignment. 10. The device according to claim 9, characterized in that that the perforated tape (IA) has a plurality of longitudinal rows of capillary perforations and the print head (5) contains at least one electrode (17) each assigned to a row. 11. The device according to claim 8, characterized in that that the color carrier (1A) contains spacer elements (21), which are from the color-repellent Layer (1B) protrude and come into contact with a surface of the printing substrate (6). 12. The device according to claim 9, characterized in that that the capillary perforation - 26 309822/0875 Tionen (11) have a cross-section from one side of the perforated metal strip (1A) to the other side of the same increases. - 25 167 309822 / 087B