EP2379335B1 - Method and printing press for printing a substrate - Google Patents

Description

The invention relates to a method of printing a substrate in a printing press, wherein in a first step, ink is transferred from a flexible support to the substrate according to a predetermined pattern by energy from a device for introducing energy through the flexible support into the ink is introduced, a portion of the color evaporates in the Einwirkbereich the energy and thereby a drop of paint is spun on the substrate to be printed and the step is repeated at least once, wherein color for amplifying the pattern generated at least partially transferred to the same positions on the substrate. Furthermore, the invention relates to a printing machine, comprising a flexible support, which is coated with a paint aufzudruckenden, and a device for introducing energy into the paint. The device for introducing energy is arranged so that the energy can be introduced in a printing area on the side of the flexible carrier remote from the color, so that color is transferred from the flexible carrier to a substrate to be printed.

A method for printing on a substrate, in which drops of paint are thrown from a color-coated carrier onto a substrate to be printed, is for example off US-B 6,241,344 known. To transfer the ink, energy is introduced by the carrier into the ink on the carrier at the position where the substrate is to be printed. As a result, a part of the color evaporates, so that it dissolves from the carrier. Due to the pressure of the evaporating paint, the ink droplet thus dissolved is thrown onto the substrate. By directed introduction of energy can be transferred in this way, the color corresponding to a pattern to be printed on the substrate. The necessary energy for transferring the color is introduced, for example, by a laser. The carrier on which the paint is applied, for example, is a circulating belt, on which by means of a coating device in front of the printing area color is applied. The laser is located inside the circulating belt, so that the laser acts on the carrier on the side facing away from the paint.

A corresponding printing machine is still for example also off US 5,021,808 known. Again, color is applied from a reservoir with an applicator on a circulating belt, which is within the circulating belt, a laser through which the ink is evaporated at predetermined positions and is thrown onto the substrate to be printed. The tape is made of a transparent material for the laser. To evaporate the paint in a targeted way, For example, it is possible for the circulating belt to be coated with an absorption layer in which the laser light is absorbed and converted into heat, thus evaporating the paint at the laser's exposure position.

The application of the paint on the flexible support is generally carried out by rolling mills, wherein a roller immersed in a paint-containing reservoir and the color is transferred by means of the roller on the flexible support.

During the printing process, the ink layer amount to be printed can be changed, for example, by varying the ink layer thickness on the ink carrier or by varying the laser power. This is for example in WO-A 03/074278 disclosed.

Alternatively, to vary the ink layer thickness, it is possible to print one print line multiple times with the same information. In this case, the print line is built up in several layers. The amount of printing substance to be transferred is thus almost unlimited. However, the disadvantage here is that in conventional printing machines, the substrate to be printed continues to move continuously. As the line reprint increases, the pressure precision to be achieved thereby decreases.

In EP 0 523 647 and EP 0 343 443 Laser printers are disclosed.

The object of the present invention is to provide a method and a printing press which make it possible to vary the quantity of ink layer to be printed by multiple printing of a line, whereby an improved printing precision is achieved in comparison with the methods known from the prior art.

The object is achieved by a method according to claim 1 for printing a substrate in a printing press.

Furthermore, the object is achieved by a printing machine according to claim 5.

By repeating at least once the transfer of ink to the substrate to be printed in each case at the same position, a multi-layer paint application is achieved. The multi-layer paint application creates a stronger image on the substrate. By moving the Einwirkbereiches the energy on the flexible support with the substrate to be coated ensures that the repeated application of paint takes place in exactly the same position as the previous application of paint. As a result, the printing precision can be improved compared to the methods known from the prior art.

In order to be able to transfer the ink in several layers at the same position to the substrate to be printed, the substrate is transported line by line in each case after the printing of one line. Here, the line is first printed, if a multiple application of color in the line is desired, the multiple application of the line is done and only after complete writing of the line, the substrate to be printed on is moved to print the next line. However, a line by line transport is also possible by first printing a line, after printing the line, the substrate is transported on and the device for introducing energy is controlled so that it also moves on one line, so that the next line at the same position on the substrate as the previous one is printed and so a multiple application is possible.

The substrate is transported continuously through the printing machine. A continuous transport is particularly favorable when large and heavy substrates are to be printed. It is carried out together with the substrate to be printed, a continuous movement of the Einbringbereiches of energy to print on the substrate. Only after completion of the printing of one line, for example a multiple print or a single print, the device is moved relative to the substrate to be printed so that the next line can be printed. In addition to a single-line printing, it is of course also possible to first print several lines, then to move the Einwirkbereich the energy so relative to the substrate that a renewed pressure on the same positions and thus a multiple printing with a multi-layer inking is possible.

With multiple printing, it is advantageous to move the substrate at a slower speed than a single print to provide sufficient time to realize multiple inking.

If the energy input device comprises a plurality of energy generators, the multiple printing is realized by writing the line once each with a power generator, a first power generator writing the line a first time and overwriting the line with other existing power generators until the first power source desired number of superimposed line printing is reached. The maximum number of superimposed line printing in this embodiment corresponds to the number of power generators. In order to be able to print in each case at the same position on the substrate, the energy generator are arranged offset. This makes it possible to compensate for the transport of the substrate.

Furthermore, in one embodiment it is also possible for a plurality of energy generators to be provided and for at least one of the energy generators to also be controllable such that the area of influence of the energy generator can be moved with the substrate. In this way it is possible to print one line in succession with different power generators and at the same time to print one line multiple times with a power generator. As a result, the number of superimposed line printing can be greater than the number of energy producers.

In order to achieve a clean print image, the area of influence of the energy on the ink is preferably punctiform. This is achieved in particular by the energy being introduced into the paint in a focused manner by the flexible carrier. The size of the point to which the energy to be introduced is focused corresponds to the size of the point to be transferred. The points to be transmitted preferably have a diameter in the range of 10 to 200 .mu.m, in particular in the range of 40 to 100 .mu.m. However, the size of the point to be transferred may differ depending on the substrate to be printed and the printed product produced therewith. For example, it is possible to choose a larger focus, especially in the production of printed circuit boards. On the other hand, in printed matters in which a font is displayed, generally small printing dots are preferred for producing a clear typeface. Even when printing images and graphics, it is advantageous to print as small dots as possible to create a clear image.

In order to obtain a multi-layer inking, it is possible with the inventive method, one line or multiple lines first easy to print and then to overprint the lines again, to provide parts of a line with a multi-layer inking or only single dots several times in succession to print and in this way already to produce the single point in a multi-layer paint application. The multiple printing of individual dots has the advantage that only one line movement of the device for introducing energy per line is necessary for multiple printing of one line and also for a single print, and no multiple line movement.

The flexible carrier used in the printing machine, which is coated with the ink to be printed on, is preferably configured in the form of a ribbon. Particularly preferably, the flexible carrier is a film. The thickness of the flexible carrier is preferably in the range of 1 to 1000 .mu.m, in particular in the range of 10 to 300 microns. It is advantageous to carry out the flexible carrier as possible in a small thickness, so that the energy introduced by the carrier is not scattered in the carrier and so a clean print image is generated. As a material, transparent polymer films are suitable, for example, for the energy used. Suitable polymers are, for example, polyimides.

In one embodiment of the printing machine, the flexible carrier is stored in a suitable device. For this it is possible, for example, that the carrier, which is coated with paint, is wound up into a roll. For printing, the carrier coated with ink is then unwound and passed over the printing area, in which color is transferred from the carrier to the substrate to be printed with the aid of a laser. Subsequently, the carrier is rewound for example again on a roll, which can then be brought to disposal. However, it is preferred that the flexible support is designed as a circulating belt. In this case, paint is applied to the flexible support with a suitable applicator before it reaches the printing position, ie the point at which the ink is deposited by means of the energy input from the support is transferred to the substrate to be printed achieved. After printing, some of the ink has been transferred from the support to the substrate. As a result, there is no more homogeneous color film on the support. Thus, for a next printing operation, it is necessary to coat the support again with paint. This is done the next time the corresponding position on the paint application device. In order to avoid that the ink dries on the flexible support and in order to produce a uniform ink layer on the support, it is advantageous to first remove the paint present on the support before a subsequent application of ink to the support. The removal of the paint can be done for example by means of a roller or a squeegee. If a roll is used to remove the paint, it is possible to use the same roll with which the paint is also applied to the backing. For this purpose, it is advantageous if the rotational movement of the roller is in the opposite direction to the movement of the flexible carrier. The color removed from the flexible carrier can then be returned to the ink supply. Alternatively, if a roller is provided for removing the paint, it is of course also possible to provide a roller for removing the paint and a roller for applying paint.

If the ink is to be removed from the flexible carrier with a doctor blade, then any doctor known to those skilled in the art can be used.

In order to avoid that the flexible support is damaged when applying the paint or when removing the color, it is preferred if the flexible support with the aid of a counter roll against the applicator roll, with which the color is applied to the carrier Roll that removes the paint from the backing or presses the squeegee that removes paint from the backing. The backpressure is adjusted so that the color is substantially completely removed, but there is no damage to the flexible support.

The device for introducing energy preferably comprises at least one laser. Advantage of a laser is that the laser beam used can be bundled to a very small cross-section. Thus, a targeted energy input is possible. In order to at least partially vaporize and transfer the ink from the flexible support to the substrate, it is necessary to convert the light of the laser into heat. For this purpose, it is possible, on the one hand, that a suitable absorber is contained in the ink, which absorbs the laser light and converts it into heat. Alternatively, it is also possible that the flexible carrier is coated with a corresponding absorber or is made of such an absorber or contains such an absorber, which absorbs the laser light and converts it into heat. However, it is preferred that the flexible carrier is made of a transparent material for the laser radiation and the absorber that converts the laser light into heat is contained in the paint. Suitable absorbers are, for example, carbon blacks, metal nitrites and metal oxides.

As a laser used to transfer the color from the flexible support to the substrate, for example, fiber lasers that are operated in the fundamental mode are suitable. In order to be able to print one line multiple times, it is preferred if the printing press comprises a control unit with which the device for introducing energy can be controlled. The control unit is in particular designed so that an exact multiple printing is possible without a slight line offset arises, so that no applied in a subsequent layer color is printed next to the previous layer.

When using a laser as a device for introducing energy, the control unit in a first embodiment comprises a controllable mirror device. With the controllable mirror device, the laser beam can be redirected according to the requirements of the pattern to be printed. With a suitable control and suitable drives for the mirrors, a very precise control of the laser is possible in this way. Actuators, for example, are used as the drive for the mirrors, as are known to the person skilled in the art.

As an alternative to a controllable mirror device, it is also possible to control the laser, for example, by using at least one acousto-optic or electro-optical modulator. It is also possible to use a plurality of acousto-optical or electro-optical modulators or to use acousto-optical and electro-optical modulators. In addition, a controllable mirror device may be provided in addition to the modulators.

In a third embodiment, the control unit includes controllable lens systems, with which the laser can be controlled so that a multiple printing of a line on the substrate is possible. On the one hand, the laser is bundled by the controllable lens systems, so that it can be focused more precisely; on the other hand, precise control of a point on the flexible carrier is possible in order to be able to selectively transfer a colored dot to the substrate to be printed. The control of the lenses is done, for example, by tilting individual lenses or by moving the lenses. For this purpose, as well as in the case of the controllable mirror device, servomotors known to the person skilled in the art are preferably used. The controllable lens system can also be used together with a controllable mirror device and / or acousto-optical or electro-optical modulators.

In addition to the use of a control unit, by means of which, for example, the laser used is specifically controlled in order to realize a multiple pressure, it is alternatively also possible for the area of action of the energy to be moved with the substrate or moved counter to the transport direction of the substrate, the device is movably received for introducing energy. In this case, the entire device for introducing energy is moved along. This is required, for example, when a different energy than a laser is used. In particular, when using a laser, however, it is preferred to use a control device with which the laser beam is deflected targeted to allow multiple printing.

In addition to the use of only one laser, it is also possible that the device for introducing energy comprises at least two lasers as energy generators, which are arranged offset from one another in order to compensate for the line offset generated by the advance of the substrate can. In this case, one line is first printed with the aid of the first laser and then a second print is made at the same printing position as the first line with the second laser, so that a line is printed several times by using several lasers. A shift of the laser in the transport direction of the substrate for a multiple overprinting of the same line is then not necessary. The deflection of the laser in the transport direction of the substrate can thus be reduced. However, if multiple prints are to be realized in which the number of superimposed prints of one line is greater than the number of lasers present, it is additionally possible to control at least one laser so that it can write a line multiple times.

To improve the printed image, it is also possible to provide a tensioning device with which the flexible carrier is tensioned, for example, to smooth waves in the flexible carrier. In addition, with a clamping device, for example, the distance between the flexible support and the substrate to be printed can be adjusted. This makes it possible to set a constant distance between flexible carrier and substrate to be printed even with multiple printing and thus to ensure a uniform print quality. For example, a tensioning device with which the pressure gap can be set and the flexible carrier smoothed comprises at least two guide elements arranged on both sides of the device for introducing energy. In this case, generally at least one guide element in the transport direction of the flexible support is arranged in front of the device for introducing energy and at least one guide element behind the device for introducing energy. Due to the guide elements, the flexible support is located exactly in the area in which the energy is introduced and the color the substrate to be printed is transferred, stretched. Alternatively, it is also possible to use only one guide element. In this case, the guide element is exactly in the way of the energy to be introduced, so that the guide element for the energy to be introduced must be transparent. In this case, suitable as a guide element, for example, a transparent rod or preferably a guide element which is designed as a rod lens. The advantage of using a rod lens is that the laser is bundled in it and so the print quality can be further improved. In order to realize a multiple printing, in which the Einwirkbereich the energy is moved with the substrate to be printed, it is necessary that the clamping device moves with the Einwirkbereich of energy. Alternatively, when using at least two guide elements, they may also be positioned far enough apart that the distance between the guide elements is sufficient to realize a multiple pressure. For example, tensioning rollers or rigid guide elements are suitable as guide elements, but they must not be sharp-edged in the area in which the flexible carrier is guided over the bars in order to avoid damaging the flexible carrier.

As a color that can be transferred to the substrate to be printed with the printing press according to the invention, any, known in the art ink is suitable. The color can be both liquid and solid. However, the use of liquid colors is preferred. These preferably have a viscosity of less than 10,000 mPas and more preferably a viscosity of less than 1,000 mPas. Usually, liquid paints used contain at least one solvent and color-forming solids, for example pigments. Alternatively, however, it is also possible that the paint contains, for example, a solvent and electrically conductive particles dispersed in the solvent. In this case, for example, a printed circuit board can be printed with the ink used. In addition, it is particularly preferred when using a laser for energy input, if the color also contains an additive that absorbs the laser radiation and converts it into heat. Suitable additives are, for example, carbon black or metal oxide pigments.

When conventional printing inks are used, the substrate to be printed is preferably paper. However, any other substrate can also be printed with the device according to the invention. Thus, for example, paperboard or other paper products, plastics, for example plastic films such as those used for packaging, metal foils or composite films can be printed with the printing press according to the invention. Also suitable are the printing machine and the method for printing printed circuit boards. In this case, the substrate to be printed is usually any printed circuit board substrate known to those skilled in the art. The printed circuit substrate can be both solid and flexible.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

Figur 1

eine schematische Darstellung einer erfindungsgemäß ausgebildeten Druckmaschine,

Figur 2

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zum Einbringen von Energie.

Show it:

FIG. 1

a schematic representation of an inventively designed printing machine,

FIG. 2

a schematic representation of a device according to the invention for introducing energy.

FIG. 1 shows a schematic representation of an inventively designed printing machine.

A printing machine 1 comprises a flexible carrier 3, which is designed as an endless belt in the embodiment shown here and is guided around a plurality of deflection rollers 5. On the flexible carrier 3, a color for printing a substrate 7 is applied.

For printing the substrate 7 9 energy is introduced through the flexible carrier 3 in the paint in a pressure range. By introducing the energy into the paint, a part of the color evaporates, whereby a drop of paint is thrown onto the substrate 7. For example, a laser 11 is suitable as energy that is introduced into the paint. Suitable lasers 11 which can be used to introduce energy into the paint are, for example, fiber lasers. The advantage of using a laser 11 is that it can be concentrated to a very small point with a cross section in the range of 10 to 100 μm and in this way a very accurate printed image can be generated.

In order to enable multiple printing of individual lines during the transport of the substrate 7 in the transport direction 13, according to the invention, the laser 11 can be moved with the substrate 7 in the transport direction 13 or moved against the transport direction 13 of the substrate 7. The movement of the laser 11 in the transport direction 13 of the substrate 7 is shown with a first arrow 15 and the movement of the laser 11 against the transport direction 13 of the substrate 7 with a second arrow 17. The movement of the laser 11 thus makes it possible to describe a line exactly several times without the edges of the pattern to be printed becoming unclear. The next ink layer can be applied in this way in exactly the same position as the previously applied.

When one line has been printed multiple times, after printing the line, the laser 11 is moved to the next line to print it. If a multiple printing is provided, it is advantageous that the substrate 7 is moved slower than with a single print in order to be able to print the substrate 7 within the movement window of the laser 11.

In order to be able to transfer fresh paint to the substrate 7 in each case, it is necessary to guide the laser in each case over regions of the flexible support from which no ink has yet been removed. For this purpose, the flexible carrier 3 is moved around the deflection rollers 5 at a constant speed. The transport direction of the flexible carrier 3 is shown by an arrow 19.

The ink that is printed on the substrate 7 in the printing area 9 is applied to the flexible substrate 3 with an applicator 21. In order to ensure a uniform application of ink, the applicator 21 in the embodiment shown here comprises an applicator roll 23 with which the ink is applied to the flexible support 3. The contact pressure required for applying the ink is realized by a counter-roller 25, which also serves as a deflection roller for the flexible carrier 3. With the help of a Einfärbewalze 27, the color is applied to the applicator roll 23. The inking roller 27 is inked in the embodiment shown here via a Einärbeschild 29. As an alternative to the inking label 29, however, the inking roller 27 can also be coated with paint by any other device known to the person skilled in the art. It is thus possible, for example, for the inking roller 27 to be immersed in a reservoir of paint and thus to be coated with paint. It is also possible that the inking roller 27 is dispensed with and only one application roller 23 is provided. Also, more than two rollers may be provided to apply the paint on the flexible carrier 3.

In order to catch dripping paint from the inking roller 27, a drip catcher 31 is provided in the embodiment shown here. Trapped by the drip 31 color is passed back into a reservoir 33 containing the color. The color contained in the reservoir 33 can be added as needed from a solvent tank 35 solvent. This is necessary, for example, to replace evaporating solvent from the reservoir 33. It is also possible to add solvent from the solvent container 35, which has evaporated from the ink which is applied to the flexible carrier 3 and, with the aid of the applicator roll 23, is removed from the latter after printing and returned to the storage container 33. In order to keep the color in the reservoir 33 homogeneous, an agitator 37 is further preferably provided. Suitable agitator 37 is any agitator known to the person skilled in the art. For example, any stirrer be provided. Suitable stirrers are, for example, propeller stirrers, disk stirrers, lattice stirrers, blade stirrers, anchor stirrers or radial stirrers.

The amount of solvent that has to be metered from the solvent tank 35 into the storage tank 33 can be determined, for example, by measuring the viscosity of the paint in the storage tank 33. For this purpose, it is possible, for example, to equip the storage container 33 with a viscometer 45. The amount of solvent to be metered is then determined via the viscometer 45. Preferably, the viscometer 45 is equipped with an automatic dosage for the solvent.

From the reservoir 33, the paint is transported by a circulation pump 39 through a feed line 41 to the Einzeichbeschild 29. The ink is then applied to the inking roller 27 with the inking label 29. Excess paint drips back into the drip 31 and runs from there via a return line 43 back into the reservoir 33rd

In order to avoid that ink dries on the flexible support 3 and thus leads to unevenness and thus deterioration of the printed image, color not transferred to the substrate 7 is removed again from the flexible support 3 after printing with the aid of the applicator roll 23. For this purpose, it is advantageous if the direction of rotation of the applicator roll 23 is opposite to the transport direction 17 of the flexible carrier 3. The removed by means of the applicator roll 23 from the flexible support 3 color is stripped by means of the inking roller 27 of the applicator roll 23 and drips into the drip 31, from which it is conveyed via the return line 43 back into the reservoir 33.

Alternatively to the applicator roll 23, with which the paint is removed from the flexible support 3, it is also possible to remove the paint from the flexible support 3, for example by means of a doctor blade or any other device, before applying new paint. It is also possible, for example, to provide a second roller with which the paint is removed from the flexible carrier 3.

To improve the printed image, it is possible in one embodiment to provide a clamping device in the printing area 9, with which the flexible support 3 can be tensioned so as to avoid bumps and waves in the flexible support. In addition, with such a clamping device, for example, a constant distance between the flexible support and the substrate to be printed 7 can be adjusted. Such a tensioning device comprises, for example, a guide element, via which the flexible carrier 3 is guided. If only one guide element is provided, then this is preferably for the energy to be introduced, that is in the embodiment shown here for the laser 11, transparent. The laser 11 is then passed through the guide member to the flexible carrier 3.

Alternatively, it is also possible to provide, for example, two guide elements, of which a guide element is located in front of and a guide element behind the laser 11. At a small distance of the guide elements, these move with the laser. Alternatively, it is also possible to keep the distance between the guide elements so large that the laser can be moved between them with the substrate or moved counter to the transport direction 13 of the substrate 7.

By such a clamping device, the pressure region 9 can be realized with constant dimensions. This makes it possible to keep the printing gap between the flexible support 3 and the substrate 7 to be printed homogeneous and thereby to realize constant printing conditions and thus to improve the printed image.

In FIG. 2 In detail, a device for introducing energy is shown, with which a multiple printing is possible during transport of the substrate to be printed.

In the embodiment shown here, the energy is introduced by means of a laser 11 into the flexible carrier 3 in order to transfer color to the substrate to be printed. In order to achieve a multiple printing, that is, a multiple printing of a line to increase the layer thickness of the ink on the substrate to be printed 7, the laser beam 51 is first passed through a laser modulator 53. In the laser modulator 53, for example an AOM or EOM, the intensity of the laser 11 can be changed. This allows, for example, the laser on and off to print in a line only certain areas. Alternatively, however, it is also possible to use, for example, an acousto-optic or an electro-optical modulator with which the laser beam can be deflected in order to enable multiple printing while the substrate 7 is moving.

After leaving the laser modulator 53, the laser beam 51 is directed via a deflection mirror 55 to a polygon mirror 57. The deflection mirror 55 includes, for example, a servomotor 59 with which the direction of the deflection mirror 55 can be varied. As a result, the laser beam 51 can be moved with the substrate 7 in the transport direction 13 or against the transport direction. At the polygon mirror 57, the laser beam 51 is deflected in accordance with the desired line position. For this purpose, the polygon mirror 57, as shown here with an arrow 61, rotatable.

In order to keep the laser focus in a plane after reflection on a 45 ° mirror 63, an f-theta lens 65 is positioned between the polygon mirror 57 and the 45 ° mirror 63. Depending on the position of the point to be printed, the laser is deflected at the polygon mirror 57, guided by the f-theta objective 65, reflected at the 45 ° mirror and thus hits with its focal point on the flexible support 3, which is coated with a color layer, on. In an adsorption layer on the flexible support 3 or by a suitable adsorbent in the color, the energy of the laser 11 is converted into heat. As a result, a portion of the solvent evaporates in the paint and it forms a drop of color 67. The color drops from the color layer of the flexible support 3 and is thrown onto the substrate to be printed 7, where it then dries, thus providing a printed color point. In this way, any pattern can be displayed. In order to reinforce the pattern, a multiple printing is possible according to the invention by deflection with the aid of the deflection mirror 55, in which color is applied to the substrate 7 to be printed in several layers.

In addition to the embodiment shown here with a laser modulator 53 and deflecting mirror 55, it is alternatively also possible to use only one or more laser modulators or, alternatively, only deflecting mirrors for deflecting the laser beam 51. Furthermore, the deflection of the laser beam can also be realized by suitable controllable lenses. Any combination of controllable lenses, deflecting mirrors and laser modulators is conceivable.

Furthermore, it is also possible to use instead of the controlled laser or, alternatively, a plurality of lasers, which are arranged offset from one another to compensate for the transport of the substrate 7 and with which successively one line can be written multiple times, each laser prints the line once ,

LIST OF REFERENCE NUMBERS

1

press

3

flexible carrier

5

idler pulley

7

substratum

9

pressure range

11

laser

13

Transport direction of the substrate 7

15

Movement in the transport direction 13

17

Movement against the transport direction 13

19

Transport direction of the flexible carrier 3

21

applicator

23

applicator roll

25

backing roll

27

inking

29

Einfärbeschild

31

drip catcher

33

reservoir

35

Solvent containers

37

agitator

39

circulating pump

41

supply line

43

Return line

45

viscometer

51

laser beam

53

laser modulator

55

deflecting

57

polygon mirror

59

servomotor

61

Rotation of the polygon mirror 57

63

45 ° mirror

65

f-theta Lens

67

color drops

Claims (10)

1. A method for printing a substrate (7) in a printing press, comprising the following steps:

   (a) transfer of ink from a flexible carrier (3) to the substrate (7) in accordance with a predefined pattern, by energy being introduced by an apparatus for introducing energy through the flexible carrier (3) into the ink, part of the ink being evaporated in the region of action of the energy, and an ink drop (67) being thrown onto the substrate (7) to be printed as a result,

   (b) repeating of step (a) at least once, ink for reinforcing the pattern which is produced being transferred to the substrate (7) at least partially at the same positions,

   the substrate being transported through the printing press (1) during printing, and the apparatus for introducing energy being controlled, after the transfer of ink in step (a), in such a way that, during the repetition in step (b), the ink is transferred again at the same position as in step (a), wherein the substrate (7) is transported continuously through the printing press (1) and, in order to repeat step (a), the apparatus for introducing energy is moved together with the substrate (7) in order to apply ink at the same position on the substrate (7).
2. The method as claimed in claim 1, wherein the apparatus for introducing energy comprises at least one laser (11).
3. The method as claimed in claim 2, wherein the laser (11) is controlled by a controllable lens system, controllable mirrors and/or laser modulators in order to write a line multiple times.
4. The method as claimed in claim 2 or 3, wherein the apparatus for introducing energy comprises a plurality of lasers which are arranged offset with respect to one another, in order to compensate for the transport of the substrate, with the result that the repetition of step (a) takes place in each case by way of another laser.
5. A printing press, suitable for carrying out the method according to claim 1 and comprising a flexible carrier (3), which is coated with an ink to be printed, and an apparatus for introducing energy into the ink, the apparatus for introducing energy being arranged in such a way that the energy can be introduced in a printing region (9) on that side of the flexible carrier (3) which faces away from the ink, with the result that ink is transferred in a region of action of the energy from the flexible carrier (3) to a substrate (7) to be printed, it being possible for the apparatus for introducing energy to be controlled in such a way that the region of action of the energy can be moved with the substrate (7) to be printed or can be moved counter to the transport direction (13) of the substrate (7), in order for it to be possible to write a line multiple times, and/or that the apparatus for introducing energy comprises a plurality of energy generators which are arranged offset with respect to one another, in order to compensate for transport of the substrate to be printed, with the result that a line can be written one after another by way of energy generators which follow one another, a control unit being included, by way of which the apparatus for introducing energy can be controlled in such a way that a line can be printed multiple times, by the substrate (7) being transported continuously through the printing press (1) and, in order to repeat step (a), the apparatus for introducing energy being moved together with the substrate (7) in order to apply ink at the same position on the substrate (7).
6. The printing press as claimed in claim 5, wherein the apparatus for introducing energy comprises at least one laser (11) as energy generator.
7. The printing press as claimed in claim 5 or 6, wherein the control unit comprises a controllable mirror apparatus (55, 57).
8. The printing press as claimed in one of claims 5 to 7, wherein the control unit comprises an acousto-optical or electro-optical modulator (53).
9. The printing press as claimed in one of claims 5 to 8, wherein the control unit comprises controllable lens systems.
10. The printing press as claimed in one of claims 5 to 9, wherein the region of action of the energy can be moved together with the substrate (7) or can be moved counter to the transport direction (13) of the substrate (7), by virtue of the fact that the apparatus for introducing energy is accommodated in a movable manner.

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