EP2067620A2 - Method for drying a multicolour printed material - Google Patents

Abstract

The method involves transforming high resolution image data that describes print image and/or content of a printing plate for color separation into low resolution image data. Position data is obtained from a transporting device for a print substrate (121). Control data for modulation of the intensity of a radiation source (119a) and/or a group of sources of LED arrays are generated from the low resolution image data and the position data. The substrate in the device is smeared with temporally modulated radiation points, which include multiple image points of high resolution print image.

Description

The invention relates to a method and a device for drying printed material, for example printed paper sheets, paper or fabric webs or plastic films, labels, etc.

In particular, in multi-color printing, it is difficult to dry the substrate quickly and effectively, before it is either printed with the next color or finished by a paint job or is turned in the printing press for the purpose of printing the back. Because due to the relatively short time in which the substrate dwells between the printing units, it is not easy to let the required radiation power act on the substrate, without the printed image z. B. damage by overheating.

It has already been proposed to reduce the drying performance in the form that only the actually covered with ink parts of the substrate are irradiated. For example, in the EP 0 355 473 described to use for drying of so-called UV ink, an array of UV waveguides, wherein the intensity of the emerging from the individual fibers UV radiation is controlled by a sensor that detects the color assignment of the swept image.

In the DE 102 34 076 It is stated that IR-absorptive inks can be dried by using a two-dimensional array of IR laser diodes while taking into account the image content, without specifying how to do this.

From the EP 0 993 378 B1 It is known for inkjet printing to dry the printing dots by the surface of the substrate is swept by means of a mirror wheel scanner with laser radiation, the radiation is only to get to the areas covered with ink of the substrate. Again, it is not specified how this has to be done in detail.

Furthermore, from the patent application DE 10 2004 015 700 A1 It is known to use single or multi-dimensional arrays of UV laser diodes to dry sheets printed with UV ink. There, however, no image content-dependent drying, but a uniform possible illumination of the substrate with UV radiation is desired.

It is the object of the present invention to provide a method by which printing materials can be dried quickly and effectively.

This object is achieved with the features specified in claim 1.

The substrate, d. H. the material, so z. As a paper sheet or a web, is dried by means of a one- or two-dimensional array of radiation sources. Here are already generated in the pre-press image data low resolution, as z. B. are used for presetting the ink fountain openings in offset printing machines, also used to dry the substrate depending on the image content. Accordingly, no sensors are required to recognize the color assignment in the print image. Furthermore, the control and control effort required to control the light sources or groups of light sources in the dryer according to the image content is of an acceptable order of magnitude because image data of reduced resolution are used and not every print dot or pixel of the rasterized bitmap must be addressed individually. The same applies to the optical effort required to focus the radiation sources on the surface of the printing substrate.

The image data of low resolution does not necessarily correspond to the pitch of the radiation sources of the array. For expediently, the "coarse" image data taken over by the prepress are converted into data with a further reduced resolution only in a second step, wherein the further reduced resolution corresponds to the pitch of the radiation sources. The advantage of this two-stage process is that data supplied by the prepress stage can be used uniformly for completely different setting or working processes in the printing press, ie multiple times. At the radiation sources of the Arrays may be, for example, the face of waveguides or semiconductor emitters such as light or laser diodes. Depending on the type of color used, the wavelength of the radiation required for the drying process is selected: z. As UV radiation for reactive curing inks, visible light, which is tailored to the absorption by the pigments of the printed color, for offset inks, or infrared radiation in paints, which IR-absorber are mixed.

Further advantages of the invention will become apparent from the following description of exemplary embodiments with reference to FIG FIGS. 1 to 7 of the accompanying drawings and are set forth in the subclaims.

FIG. 1 is a simplified schematic diagram which serves to explain the data flow from the prepress to the printing press with respect to the method according to the invention.

In FIG. 1 is denoted by 1 the workstation on which the imposition of the image to be printed, the so-called impositioning, is performed. At this point, the data of the printed page are available as vector graphics, which are printed with a resolution of typically 600 dpi z. B. can be output as a proof on a printer, the pixels of the image on the proofer can typically have a color depth of 16 bits. These data are used, among other things, as a basis for creating the four printing plates in the colors black, cyan, magenta and yellow, which are used in the FIG. 1 denoted by 4. For the exposure of these printing plates, the data in the four color separations are rastered in the so-called raster image processor 2. The resolution of the raster pixels in the rasterized color separation is typically 2400 dpi, so is much finer, since each pixel corresponding to the color depth in a different number of Raster pixels is decomposed. The raster image data are transferred to a plate-setter 3, a so-called "computer-to-plate" device, in which the four printing plates in the aforementioned primary colors are successively exposed.

The size and location of the areas to be exposed is different for the four printing plates, as in the example FIG. 2 is shown.

FIG. 2 shows a colored picture 20 of a well-known German university city on the left side and on the right next to it shown reduced in size the color separations yellow (Y), magenta (M), cyan (C) and black (B). The areas to be inked on the corresponding printing plate are shown dark, while the color-free areas are bright.

A pre-press workstation 5 ( FIG. 1 ), on the basis of the imposed color image, the color separations and the rasterized separations can be created, edited, stored and displayed. It is assumed that the data on this workstation 5 is in the so-called PPF format (print production format), which was generated especially for the exchange of data between the various devices used in the production of printed products. According to the CIP3 / CIP4 standard underlying this format, the generation of a so-called "rough image" (preview image) from the data of the imposed print image is furthermore provided. This thumbnail typically has a much coarser resolution of 50 dpi and is also available in the four color separations.

The CIP3 / CIP4 specification recommends to use the data of these coarse images for presetting the ink-zone openings, of which each of the four printing units 7a to 7d of the printing press 7 or the inking unit 16a to 16d contained therein ( FIG. 5 ) typically has between 16 and 32 pieces, depending on the format width of the printing press. This is done at the various printing press manufacturers typically in a so-called pre-press interface (PPI) 6. This is a personal computer or industrial PC, which sums the shares of color assignment from the data of the previews within the individual color zones and in a control value for convert the engines in the individual inking units, from which the zone openings are actuated. These control values are transferred to the machine control 8, where they are converted into control signals for the engine controls.

According to an embodiment of the present invention, the data of the roughly resolved thumbnails should also be used for the sheets printed in the printing machine 7 or, in the case of a web-fed printing press, for the printed web Depending on the image to dry, ie to apply at the sites with radiation, where actually ink is located.

Before this is explained in more detail, we turn to the in FIG. 5 illustrated schematic diagram of a typical four-color sheetfed press with downstream coating unit too. The FIG. 5 shows an offset printing machine 7 in a row construction with a feeder 9, in which the unprinted paper stack is, as well as four printing units 7a to 7d for the four primary colors. Each printing unit has an impression cylinder 13a, a blanket cylinder 14a, a plate cylinder 15a and an inking unit 16a, these assemblies being provided with reference numerals only for the first printing unit 7a. Transferters 21a to 21d between the printing units transport the printed sheets from one printing unit to the next. The fourth printing unit 7d is followed by a coating unit 7e of the type "chambered doctor blade", ie it has a screen cell roller 19e and a chamber doctor blade 20e. 22e is a so-called "anilox roll star", which contains three further anilox rollers with different cup size, against which the anilox roller 19e can be exchanged, in order to determine the amount of lacquer to be applied in this way. In the coating unit 7e, the printed sheet of the paint application cylinder 21e is coated over its entire surface with a varnish or printed with spot varnish, depending on the type of varnish plate used (blanket or flexo-form).

The coating unit 7e is followed by a drying tower 7f. In this drying tower, the sheet transported through is dried in the area of the cylinder 37f by hot air and infrared radiation, if e.g. B. aqueous dispersion varnish in the coating unit 7e is applied to the printed sheets.

On the dryer 7f follows the boom 10 of the printing press. In it grabber bridges run by means of a chain guide 11. These gripper bars 18 take over the lacquered sheets and guide them under dryer inserts 110a to b through, where the sheets are again dried with infrared radiation and / or hot air and the applied lacquer is solidified. The sheets thus dried are then deposited in the arm 10 on the sheet stack 12.

In the described embodiment, the printing machine 7 is to print with so-called UV inks, d. H. Colors that do not oxidize oxidatively, as in offset printing, by the action of heat or infrared radiation and by being smashed into the paper, but rather colors that are cured by exposure to ultraviolet light. Such inks and offset printing machines, which are specially equipped for printing with UV inks, are known per se. For drying the inks, a so-called intermediate deck dryer 17a to 17d, which provides the required UV radiation, is arranged in the sheet transport path above the counter-pressure cylinders 13a to 13d. Such an intermediate deck dryer 17e is also located above the impression cylinder 13e of the coating unit 7e. With this intermediate deck dryer 17e, for example, UV spot varnish can be dried, and in the same way print image, d. H. in this case paint image dependent, as in the Zwischendecktrocknern 17a to d.

In the event that 7e water paint is printed in the coating unit, which is also applied over the entire surface over the printed image, the drying tower 7f downstream of the coating unit 7e can be activated, which contains a hot air dryer 27a, with which the water vapor is expelled from the water paint.

For further drying of the printed and varnished sheets 10 additional dryer 110a and 110b may be provided as known per se and generally customary in the region of the chain guide of the boom. These may be, for example, infrared dryers or UV dryers, depending on the nature of the printed colors or paints, in order to dry them even further before being deposited on the delivery stack 12. These dryers 110a and 110b are typically formed as bays, so that different types of dryers can be used as needed at the location.

In this embodiment of the invention, the intermediate deck dryers 17a to 17e are formed as shown in FIG FIGS. 6a to c described. They each contain a closed and inert gas, z. B. N ₂ , rinsed housing 118 each one or more array (s) 119 of UV lamps. These are light-emitting diodes 119a to n, which emit ultraviolet radiation in a wavelength range of 370 to 385 nanometers, as they are needed for the activation of photoinitiators, with their help polymerize the UV inks. These photoinitiators, such. B. Lucirin® TPO, which is offered by BASF AG in Ludwigshafen, Germany, have an absorption maximum in the wavelength range of 380 nanometers.

UV diodes in this spectral range are currently offered with powers in a range between several microwatts to several watts and can be obtained, for example, from the company Roithner Lasertechnik in Vienna, Austria. UV diodes have typical housing dimensions of 3 or 5 millimeters in diameter, as far as they are single diodes and can be obtained with different beam divergences 120. With such diodes can be built linear arrays of individually addressable UV light sources that produce without special intent optics at a working distance of several centimeters spots of d = about 3 to 10 millimeters diameter on the printed sheet 121, so that under such an array continuous sheet 121 can be irradiated sideways with coverage.

In the housing 118 and the electronics 123 for driving the light-emitting diodes 119a to n is housed, as well as each intermediate deck dryer associated and in FIG. 5 for the sake of clarity, schematically drawn as a block diagram control computer 122, whose function will be described later. The housing 118 is made of solid aluminum ribbed in the area of the LED array 119 in order to ensure good cooling of the LEDs 119a to n of the array. The LEDs 119 a to n are used in thermal contact in bores of an intermediate plate 118. The LEDs 119a to n are protected by both sides projecting strips 118b and 118c against contamination, wherein the effluent from the slot between the strips inert gas N ₂ prevents the penetration of paint mist or moisture in the space in front of the front side of the LEDs 119a to n. Alternatively, between the strips 118b and 118c a z. B. removable radiation window may be appropriate, which protects the end faces of the LEDs 119a to 119n against contamination.

It is also possible to arrange a plurality of rows of LEDs 219a to n, 219b to n in the intermediate deck dryer 218. If several rows of LEDs, for example, 50 rows in the transport direction of the printed sheet are arranged one behind the other, that corresponding LEDs lie on a line, the same pixels of the printed image can be repeatedly irradiated in succession, so as to increase the performance of the dryer. Furthermore, the beam cone can be uniformed over a suitably selected coverage of the luminous density on the sheet to be dried.

The latter is based on FIG. 3 Once more clearly illustrated: In the upper area, the linear array 119 of the UV diode arrangement can be seen simplified in a plan view of the end face. Underneath, the coarse thumbnail of the Magenta color separation is drawn. About this color separation is a rectangular auxiliary grid laid, which is only for explanation. Each square cell of this auxiliary grid has a dimension of b = 10 millimeters. The distance a, under which the diodes 119a of the LED array 119 are arranged, is 5 millimeters, ie each cell of the auxiliary grid is swept with LEDs on by two UV light bars 129a and 129b, which partially overlap, so that the intensity drop of the central axes 130a, 130b of the light bands 129a, 129b is compensated towards the edges.

A further homogenization can be achieved, if as in FIG. 6c illustrated another array of UV LEDs 219 is provided, which is offset by half the pitch of a / 2 = 2.5 millimeters to the first array 119. Then each cell of the auxiliary grid four LEDs are assigned and it can be achieved with appropriate control of adjacent LEDs, a higher power density and more uniform distribution of UV radiation on the sheet to be dried.

The length of each light bar necessary to sweep the auxiliary cell results from the machine speed, ie the speed at which the printed sheet 121 passes under the intermediate deck dryer 117 or under the UV LED array 119, and the On time of the relevant LEDs. At full machine speed, the arc moves at about 5 meters / second, so that with a 2 millisecond on-time, the length of the lightbars 129a and 129b is 10 millimeters. If one uses LEDs emitting a light output of 500 mW, each cell of the sub-array will be exposed to ultraviolet radiation with an energy of 2 diodes x two milliseconds x 0.5 watts = 2 milliwatt seconds as it passes through the ground registered, which corresponds to a dose of 2 mJ / cm ² . This dose is already sufficient for drying UV inks. A higher radiation dose can be achieved by arranging several LED arrays in the sheet transport direction one behind the other.

Essential for the function of the present invention is the synchronization between the movement of the printed sheet under the Zwischendecktrocknern 17a to 17d through with the on or off times of the UV LEDs of the array 119 and the correct assignment of the diodes to the printed image in the axial direction based on the cylinders of the printing press. This will be explained in detail below on the basis of FIG. 7 explained. FIG. 7 FIG. 12 is a block diagram showing essential electronic components for controlling the LED arrays 119 in the intermediate deck dryers 17a-17e and exemplary signal paths for driving individual LEDs in the array of a temporary deck dryer.

As already mentioned in the description of the FIG. 1 mentioned the machine control unit 8 is connected via a data line with the so-called Prepress Interface (PPI) 6 a commercial personal computer or industrial PC with appropriate image analysis software and receives from there for presetting the ink zone openings in the inking units of the printing press the values determined in PPI 6 the color zone openings. The motor control, which are given these values, is denoted by 31. It provides the control signals for each of the z. B. 32 color zone motors with which each inking unit 16a to 16d in the four printing units 7a to d is equipped. After or, if appropriate, before these values have been transferred, the PPI 6 transfers to the machine 32 associated with the intermediate deck dryers the data describing the switching on and off of the LEDs 119a to n of the arrays in the intermediate deck dryers 17a to 17e. These data are related to the respective coordinate system of the four printing plates 4, which are connected to the precursor data after the rasterization of the images by the RIP 2 (see FIG. 1 ) were exposed in the CTP device 3 or should be exposed.

In the control module 32, these data are processed in a machine-specific manner and subsequently to the dryer controllers 122a to 122e in the intermediate deck dryers 17a to 17e to hand over. This includes, on the one hand, the determination of the time of use, ie the point in time at which the first arc z. B. enters the printing unit 7c and the drying begins in the associated Zwischendecktrockner 17c. This value is calculated from the angle value φ that the encoder 34 (see FIG FIG. 5 ) to the cylinder 13c, where the main drive of the printing press engages. The relative positions of the printing units and transport path differences of the sheets between the individual interconnected via gears printing units 7a-d are stored in the module 32, as well as the spatial assignment of the positions of the individual Zwischendecktrockner 17a to 17e to the machine angle.

As an alternative to the mathematical assignment of the print image beginning on the machine constants, it is of course also possible to provide a sensor in each printing unit over which the beginning of the printed image is detected on the under the respective Zwischendecktrockner conveyed sheet or the edge of the sheet.

The drying of the printed sheets also depends on the layer thickness of the ink with which they are printed. This can be determined, for example, by means of a test print with corresponding measuring devices. Accordingly, the control module 32 is connected in the machine control 8 with a photometer 33, via which the ink layer thickness ρ is measured. The corresponding values are used to preset the intensity of the LEDs 119 a to n in the arrays 119 and 219, respectively. Furthermore, a manual correction option for adjusting the intensity of the LEDs is provided. This may be any input tool, such as a potentiometer 39 or an input z. B. by touch screen on the screen, not shown here, the machine control. 8

In addition, it may be appropriate to check the LEDs 119a to n with regard to the radiated power emitted by them. This can be done for example by an array of photoreceivers that permanently monitors the radiation power in the area of the LED array 119 or by a regularly z. B. before each print job provided calibration

As shown in the simplified diagram, the signal curves for the individual LEDs of the arrays 119 and 219 calculated in the PPI 6 for the respective printing plates are then transferred to the dryer controllers 122a to e of the intermediate deck dryer 17a to 17e after appropriate modification by the module 32 of the machine control 8 , However, the time course of these signals depends on the machine speed v. The same applies to the intensity. Because with slow running machine, the sheet is longer in the range of action of the radiation of the individual LEDs of Zwischendecktrockner so that the intensity of the UV LEDs can be reduced or the LEDs pulsed with longer pauses between the pulses can be operated.

Within the drying cycle for an arc, the turn-on and turn-off times for the individual LEDs are also controlled by the machine angle that the encoder 34 provides. For this purpose, the dryer controls 122a to 122e are also connected to the encoder 34 and are synchronized in this way without the detour via the control module 32 in the machine control 8 directly with the machine angle φ. This ensures that the drying of the printed image takes place register-accurate, even when the machine is started up or shut down, relative to the circumferential register of the printing cylinder.

In addition, an automated offset printing machine usually also has an automatic register control, which acts on the axial position of the printing plate cylinder and consequently is able to move the print image laterally, as well as a diagonal register adjustment. In order to eliminate or compensate for the influence of the register control 36 on the printing image dependent drying, which is particularly important when the image-dependent drying with high resolution, the signals .DELTA.x of the register control 36 can also be transferred directly to the dryer controls 122a to 122e. If then z. For example, if the register control axially shifts the plate cylinder by 5 millimeters and the grid spacing of the LEDs is 2.5 millimeters, the stored waveforms in the dryer controls 122a-122e "are reversed two LED positions "shifted, ie reassigned by then, for example, the seventh LED with the waveform of the fifth LED is driven, etc.

The preparation of the control data for the individual LEDs in the Zwischendecktrocknern 122a to 122e in the PPI 6 takes place as follows: From the 50 dpi resolved thumbnails for the individual color separations for each UV light emitting diode z. B. 119a to n normalized waveforms over the printing plate length generated. For this, the pressure plate is similar as in FIG. 3 provided with an auxiliary grid, the grid elements include, for example, in the axial direction one or more, for example, two LEDs. In the circumferential direction relative to the cylinder, over which the pressure plate is moved, the resolution or the length of the elements of the auxiliary grid does not necessarily have to be the same as in the transverse direction, but, since this resolution is determined by the turn-on time of the LEDs, also z , B. be chosen coarser. A finer resolution in the transport direction, however, only makes sense if intent optics are used, since the light fields generated by each LED are usually circular or elliptical. However, can be with a front optics in the form of a cylindrical lens, the z. B. extends over the entire length of the LED array, also produce a line-shaped focus transverse to the transport direction. In this case, the resolution in the transport direction can also be chosen to be lower than in the direction transverse thereto.

In the present case we assume the same resolution in both coordinate directions. Since the control signals for the LEDs are generated from the 50 dpi preview image, which corresponds to about 20 image pixels per centimeter, however, the grid spacing of the LEDs is coarser and, for example, at 2.5 millimeters, several pixels, for example 50 x 50 pixels of the preview image , summarized into a cell and considered this cell as a unit.

Then it is determined in the PPI 6, whether at all color components are included for the considered color separation in the respective cell of the auxiliary grid or whether there are set by the imagesetter 3 grid points or were. If this is not the case, then the respective LEDs (s) remain dark for the corresponding time or machine angle interval. In the other case, if at least one grid point in the area of a cell of the Auxiliary grid, the corresponding LED is switched on for the relevant time interval or machine angle interval. In contrast to the Farbzonenvoreinstellung it comes in the dryer control but not on the amount and size of the illuminated on the plate halftone dots, but on whether a grid point is set or not on the printing plate in the respective cell of the auxiliary grid printed sheet a corresponding color point was printed or not. Because each color point requires UV radiation to be dried, the intensity of the LEDs can only be reduced if not only the size of the screen dots, but also their layer thickness decreases. This is usually not the case. This is clearly reflected in the simplified sketch FIG. 4 , There is shown in greatly enlarged form a section of the printed and dried sheet 4m to be dried with single LEDs. The spots 171 of the LEDs extend as shown in the figure over many columns of grid points. Although the color coverage at the top of the patch is much larger than at the bottom, the intensity of the LED that produces spot 171 must be maintained to ensure that all swept screen dots are sufficiently dried.

However, a reduction in the intensity with which the LEDs radiate or the pulse duration in the case of pulsed LEDs is possible if the halftone dots become so small that the ink layer thickness of the halftone dots decreases in pressure and also the influence of scattered radiation on the curing of the UV Color increases. The corresponding functional relationship can also be taken into account in the PPI 6 by calculating the intensity profile I (y), which the PPI 6 calculates location-dependent in the transport direction y of the arc for the individual LEDs, with the image brightness at the relevant location with previously determined and z. B. is stored in a table stored correction values that describe the mentioned functional relationship.

As stated above, the radiation sources of adjacent LEDs overlap. It should be noted that not only the intensity in the edge regions of the irradiated field is less than in its center, on the other hand, the irradiation time on the moving arc due to the shorter secant in the edge region of the illuminated spot 171 is smaller. Therefore, it is advisable to choose the auxiliary grid so that the Cells of the auxiliary grid is smaller than the light spot generated by the respective LED, at least as far as the dimensions are perpendicular to the direction of movement.

The invention has been described above with reference to LED diodes which emit UV light to dry sheets printed with UV inks. However, it is also possible and within the scope of the invention, when printed with offset inks, to use light sources or LEDs which radiate in the visible wavelength range and are tuned to the absorption behavior of the pigments of the printed color. Likewise, it is possible to use arrays of radiation sources that emit infrared radiation when, for example, the wavelength of the infrared radiation is tuned to absorber substances admixed with the ink.

Furthermore, the invention has been described with reference to intermediate deck dryers associated with each printing unit. However, it is also possible to use a dryer after the z. B. four printing units to dry the printed ink in total. In that case it is not necessary to process the data for the individual color separations individually. For example, these may be the dryer trays present in the delivery 10, which in the case are designed as final UV dryers, either with individually controllable UV light sources, in order to dry image content-dependent, or optionally also over the entire surface.

• In einem ersten Schritt übernimmt das Prepress Interface PPI vom RIP 2 gegebenenfalls auch sequentiell die Daten des bereits gerasterten Farbbildauszuges in der Auflösung des Rasterbildes von z. B. 2.400 dpi. Anschließend führt das PPI diese hoch aufgelösten Bilddaten direkt in Bilddaten über mit der groben Auflösung, die dem Rasterabstand der Leuchtdioden in etwa entspricht. Hierbei wird so vorgegangen, dass für jede Zelle des entsprechenden groben Hilfsrasters ermittelt wird, ob sich Rasterpunkte in der Hilfszelle befinden und gegebenenfalls, wie groß diese sind, damit wie anhand des ersten Ausführungsbeispiels für das Verfahren beschrieben eine Intensitätsanpassung vorgenommen werden kann. Mit diesen Informationen berechnet der Prozessor des PPI dann die Signalverläufe I (y) für die einzelnen LEDs, speichert diese ab und übergibt sie an die Maschinensteuerung 8, wo die Signalverläufe in solche abhängig vom Maschinenwinkel ϕ transformiert werden. Im Weiteren läuft das Verfahren dann so ab, wie vorstehend anhand des anderen Ausführungsbeispiels beschrieben.

In a further embodiment, the procedure is as follows, alternatively to the described method:

• In a first step, the prepress interface PPI from the RIP 2 optionally also sequentially takes over the data of the already screened color image separation in the resolution of the raster image of z. Eg 2,400 dpi. Subsequently, the PPI translates this high-resolution image data directly into image data with the coarse resolution which approximately corresponds to the pitch of the light-emitting diodes. In this case, the procedure is such that it is determined for each cell of the corresponding coarse auxiliary grid whether grid points are located in the auxiliary cell and, if appropriate, how large these are, as described with reference to the first embodiment for the method, an intensity adjustment can be made. With this information, the processor of the PPI then calculates the signal curves I (y) for the individual LEDs, stores them and transfers them to the machine control 8, where the signal curves are transformed into those depending on the machine angle φ. In addition, the method then proceeds as described above with reference to the other embodiment.

LIST OF REFERENCE NUMBERS

1

workstation

2

Raster Image Processor

3

platesetter

4

printing plate

5

workstation

6

Prepress interface

7

press

7a - d

printing units

7e

coating unit

7f

dryer

8th

machine control

9

investor

10

boom

11

chain guide

12

sheet pile

13a - e

Impression cylinder

14a

Blanket cylinder

15a

plate cylinder

16a - d

inking

17a - e

Steerage dryer

18

gripper

19e

Rasternäpfchenwalze

20

colored picture

20e

chambered doctor blade

21e

Coating cylinders

22e

Anilox roll star

27a

Hot air dryer

31

motor control

32

control module

33

photometer

34

encoder

35

./.

36

register control

37f

cylinder

38

./.

39

potentiometer

110a - b

dryer slot

117

Steerage dryer

118

casing

118b - c

Afford

119

array

119a - n

LEDs

120

beam divergences

121

printed bow

122

tax calculator

122a - e

dryer control

123

control electronics

129a - b

UV light bars

130a - b

central axis

171

commercial

218

Steerage dryer

219

LEDs

ρ

Ink layer thickness

v

machine speed

Δx

signals

I

intensity curve

y

transport direction

φ

machine angle

N ₂

inert gas

Claims (15)

Method for drying printed material with the aid of a one- or two-dimensional array (119, 219) of radiation sources which can be controlled individually or in groups, the high-resolution image data describing the printed image or the contents of the printing forms (4) being used for the individual color separations ( 4m) are converted into image data having a lower resolution, position data from the substrate transporting device (7) are also obtained, which describe the position of the print image in the transport direction, from the image data of lower resolution and the position data control data for modulation of the intensity of the radiation sources (119a to n, 219a to n) or groups of radiation sources of the array (119, 219) are generated, wherein the substrate (121) is swept in the transport direction with time-modulated radiation points (171), each comprising a plurality of pixels of the higher-resolution print image. Method according to claim 1,
wherein the high-resolution image data are converted into lower-resolution image data in a first step, and the second-resolution image data is converted in a second step into further reduced-resolution data matched to the radiation source array (119, 219) grid. Method according to claim 1,
wherein the high-resolution image data are those of the screened color separations and the image data of lower resolution are adapted to the grid of the radiation source array (119, 219). Method according to claim 1,
wherein the printed image is printed with UV-curing, visible or infrared curing ink and the one or two-dimensional radiation source array consists of the faces of waveguides or semiconductor light sources (119, 219) which emit UV, visible or infrared radiation, wherein the wavelength of the light or the radiation is tuned to components contained in the color such as pigments, IR absorbers or UV photoinitiators. Method according to claim 1,
wherein the resolution of the image data of the lower-resolution color separation image or the resolution of the control data for modulating the intensity of the radiation sources in the transport direction of the printing substrate is coarser than transverse thereto. Method according to claim 1,
wherein a multi-dimensional array or a plurality of linearly arranged one behind the other linear arrays of light sources are used and in the transport direction of the printing material successively arranged light sources are driven such that they each irradiate the same pixels of the printed image. Method according to claim 1,
wherein the intensity of the radiation of the light sources (119a to n) is controllable continuously or in stages. Method according to claim 1,
wherein the drying of the printed image takes place in the printing press (7),
which preferably has a plurality of printing units (7a to d) for the different colors and either a drying device (17a to d) is provided behind or in individual printing units. Method according to claim 1,
wherein the drying of the printed image takes place in the printing press (7) and one or more dryers (17f) are provided, which serve primarily for the integral drying of lacquer layers applied over the printed image. Method according to claim 1,
wherein the control of the dryer device additionally data are supplied, which are a measure of the layer thickness (p) of the printed image or the printed color separations (YMCB) or of which the contrast or the local variation of the layer thickness of the printed color is described. Method according to claim 1,
wherein the one- or two-dimensional array (119) of radiation sources (119a to n) is encapsulated and the encapsulation is preferably provided with a removable radiation window. Method according to claim 11,
wherein the space within the enclosure (118) and / or the space between the array (119) and the substrate is filled with inert gas (N ₂ ). Method according to claim 1,
wherein the resolution of the lower-resolution image data is between 5 and 100 dpi, preferably about 50 dpi. Method according to claim 2 or 3,
wherein the pitch of the radiation sources (119a to n) in the range between 0.2 millimeters to 8 millimeters, preferably between 2 and 5 millimeters, is located. Method according to claim 1,
wherein the light sources of the array or groups of light sources are checked for the radiation emitted by them.

Images