WO2022207275A1

WO2022207275A1 - Method for operating an inkjet printing machine with a base coat

Info

Publication number: WO2022207275A1
Application number: PCT/EP2022/056296
Authority: WO
Inventors: Oliver BAAR
Original assignee: Koenig & Bauer Ag
Priority date: 2021-03-31
Filing date: 2022-03-11
Publication date: 2022-10-06
Also published as: DE102021108143A1

Abstract

The invention relates to a method for operating an inkjet printing machine (01), wherein print actuation data (41) for inkjet printheads (03) are generated from template image data (38), said print actuation data determining color separations (21; 22; 23; 24) to which respective pixels to be generated of a respective color are assigned, wherein a color separation sum (47) is to be understood as the registered overlay of all of the color separations (21; 22; 23; 24) determined by the print actuation data (41); each homogenous region (43; 44; 46) is assigned a respective selection of color separations (21; 22; 23; 24), said pixels contributing to the aforementioned homogenous region (43; 44; 46); a critical boundary line (26) is a line at which two homogenous regions (43; 44; 46) of a respective pair of homogenous regions (43; 44; 46) directly adjoin each other; the template image data (38) and/or the print actuation data (41) is analyzed in order to identify at least one critical boundary line (26); base coat actuation data (36) is generated for base coat heads (07) and a base coat agent is applied onto a substrate (02) on the basis of said base coat actuation data; and ink is applied onto the substrate (02) on the basis of the print actuation data (41).

Description

description

Method of operating an inkjet printing machine with a primer

The invention relates to a method for operating an inkjet printing machine.

In inkjet printing, individual drops of ink are ejected from nozzles of printheads and applied to a printing material in such a way that a printed image results on the printing material. Different print images can be created by individually controlling a large number of nozzles. In the case of multi-color printing, different nozzles or print heads usually eject inks with different properties, in particular differently colored inks. A print image to be printed has a large number of color tones. These different hues are usually created by a series of primary colors that are combined to form different color structures, resulting in different secondary colors.

A primary color is to be understood as meaning a color of a print image that has a single ink and that comes about in the full-area print image, for example, simply by printing this one ink. For example, a commonly used system of primary colors is cyan, magenta, yellow, and black. In order to determine the necessary proportions of the primary colors at the individual points of the print image to be printed from a template image, in particular from template image data of a print image to be printed, an algorithm is usually used which is also called a color profile, for example. Pressure control data are used to control the individual nozzles. This algorithm creates color separations for all primary colors. The print control data define the color separations or contain the color separations. A particularly printed color separation is, for example, a single-color partial image of a multicolored overall print image. The individual color separations are Printing process together and result in the printed overall print image according to the template image data. The respective pixels of a respective color to be generated are assigned to the respective color separation as part of the print control data.

In the case of multicolored prints, it is desirable to achieve high register or color register quality. Since the different printing inks are usually applied to the respective substrate one after the other, this quality depends, among other things, on how precisely a second color separation is applied to the substrate relative to a first color separation. The trapping technique, which is also known as "contour trapping" or "overfilling", is often used in the area of form-bound printing processes in particular. In this case, for example, in the case of two areas each assigned to a different primary color, the associated printing forms are generated in such a way that the different color separations of the print image to be generated that are transferred in each case overlap slightly in the corresponding area. Although this results in an unnecessarily double-printed area, this is usually designed in such a way that it does not attract negative attention. The process offers the advantage that printing the color separations slightly offset from one another does not lead to a conspicuous white area in the gap. Trapping can also be used accordingly for two monochromatic areas, of which at least one is assigned a secondary color.

Such trapping is usually not desired in inkjet printing. One of the reasons is to avoid too large a coverage ratio or TAC (total area of coverage) to avoid negative effects. If the degree of area coverage is too high, there is a risk that too much ink will be applied to the printing material and the printing material will not be able to cope with the applied amount of ink, for example because the printing ink then smears on the transport rollers and/or because the printing material softens with a water-based printing ink and/or or tears and/or because cloudiness occurs and/or ink shows through the substrate and/or because The layers of printing material can stick together (blocking) and/or problems can occur during drying. Cloudiness is preferably to be understood as meaning uneven ink coverage, for example on full-tone areas and/or areas with a high level of ink application. Cloudiness can be caused, for example, by irregular penetration behavior of the ink into the printing material.

In connection with printing processes, an area coverage is understood to be the sum of the areas of the picture elements of a total area broken down into picture elements and non-picture elements (DIN 16544). A degree of area coverage describes a ratio of the area coverage to the total area broken down into picture elements and non-picture elements (DIN 16544). The degree of area coverage is specified, for example, in % (percent). A surface coverage of 100% describes, for example, an area completely printed with one layer. In particular, such a print image is described with a degree of area coverage of 100%, for example, in which the maximum possible quantity of a coating agent with the corresponding printing process or with the corresponding printing device has been transferred to the printing material. When using a number of coating agents, for example a number of different printing inks or inks, degrees of area coverage which exceed 100% can also be achieved. For example, by coating a complete surface with the three colors cyan, magenta and yellow, one achieves a degree of surface coverage of 300% and a black color impression on the viewer. If, on the other hand, an entire surface is coated with a black ink, a degree of surface coverage of 100% is achieved and the viewer also gets a black impression of the color. In inkjet printing, even lower values are usually specified for the maximum permissible total area coverage than is the case in offset printing, for example 250%.

A secondary color is to be understood as meaning a color of a printed image that comes about as a result of a mixture of at least two primary colors, for example one Mixture of cyan with a dot area of 30% and magenta with a dot area of 20%. This concrete mixture then results in a total area coverage of 50% with a hue of a corresponding secondary color. A color separation is a sub-image that consists of all picture elements of only one primary color. The printed image with all the necessary primary colors and secondary colors results from the superimposition of all partial images of all primary colors.

Due to their design, modern inkjet printing machines are able to print in such a register that trapping is not necessary. However, template images and/or template image data are created in a way that is tailored to form-based printing methods and are nevertheless used as the starting point for inkjet printing. If such template image data and/or template images already contain color separations in which trapping is used, the negative effects mentioned can occur in inkjet printing.

Another problem is the so-called "intercolor bleeding", ie the particularly undesirable bleeding of differently colored inks into one another. This can occur in particular in areas in which a relatively sharp boundary between different colored areas is to be printed with little or no mixing, but the printed image is disturbed by contact of the liquid inks and the resulting undesired running of the inks into one another.

The problems mentioned can occur both when printing on a sheet-like substrate and when printing on a web-like substrate. The problems mentioned can occur when printing different substrates, in particular paper, cardboard, corrugated cardboard, plastic, metal or mixed substrates.

It is known in ink jet printing to apply a primer before applying the colored ink. An inkjet printing machine with a device for applying primer is known from WO 2019/020236 A1.

DE 102017 101 289 A1 discloses a method in which a primer, a first ink and a second ink are applied to a substrate one after the other using an inkjet printing method and a region is then recorded by means of a sensor in which the two inks adjoin each other and optionally run into one another, in which case an analysis of the bleeding behavior is then carried out and, on the basis of this analysis, an amount of the primer to be applied is optionally adjusted for subsequent prints.

The object of the invention is to provide a method for operating an inkjet printing machine.

The object is achieved according to the invention by the features of claim 1.

A method for operating an inkjet printing machine preferably has a conversion process, wherein in the conversion process print control data for inkjet printheads for generating a print image are generated from in particular digital template image data of a template image, in particular for generating a print image on a substrate. The print control data contain information about pixels to be generated. In this case, the image points result in particular from ink drops which strike a substrate. The pixels are the elements that make up the printed image. The print control data define at least one first color separation, to which first pixels of a first color to be generated are assigned. The print control data define at least one second color separation, the second pixels to be generated in particular from the first color are assigned different second color. The print control data preferably define at least one third color separation, to which third pixels of a third color to be generated are assigned. More preferably, the print control data define at least one fourth color separation, to which fourth pixels of a fourth color to be generated are assigned. Other color separations are possible. Each color separation is preferably assigned to a respective printing position of the inkjet printing machine.

A color separation sum is to be understood above and below as a register-correct superimposition of all color separations defined by the print control data. Ideally, the total color separation corresponds to the original image and/or the printed image, although a degree of this correspondence can depend, for example, on properties and behavior of the ink, the substrate and the printheads. A respective homogeneous area is to be understood as a respective area of the total color separation, which is used to generate a respective printed monochromatic area. A color impression of the same color is preferably assigned to this respective printed monochromatic area in its entire surface area, in particular a color impression that can be achieved by itself. This is independent of whether it is a color impression that corresponds to a primary color or a secondary color.

Each homogeneous area is assigned a respective selection of color separations that contribute pixels to this homogeneous area. A homogeneous area can be made up of only one primary color or of several or all available primary barbs. It should be noted that several different homogeneous areas can be built up using the same color separations, i.e. can be assigned the same selection of color separations, but can lead to different color impressions due to a different ratio of the amounts of primary color used per area. A pair of unequally composed homogeneous areas, on the other hand, is to be understood as meaning two homogeneous areas in each case Selection of color separations differ, in particular regardless of how many pixels are provided per area.

An exemplary homogeneous area, which corresponds to a full-surface print with the color cyan, has the same selection of color separations as an exemplary homogeneous area, which corresponds to a print with an area coverage of 50% with only the color cyan. Accordingly, these two do not form a pair of unequally composed homogeneous regions. In contrast, an exemplary homogeneous area that corresponds to printing with only the color cyan forms a pair of homogeneous areas of unequal composition with another homogeneous area that is made up of cyan and magenta. A respective critical boundary line is such a line at which two homogeneous regions of a respective pair of homogeneously composed homogeneous regions directly adjoin one another. Specifically, this critical boundary line is the area where intercolor bleeding or problematic trapping could occur. For this reason, at least one critical boundary line is identified in particular in an analysis process, with priming control data for priming heads being generated in a generation process on the basis of the at least one identified critical boundary line, and with a first priming agent being applied to a substrate by means of the priming heads in a first priming process based on the priming control data . The appropriate primer is preferably applied in those areas where the critical boundary lines will lie. By selecting the appropriate primer, it is then possible to prevent the ink drops from running off unintentionally. In a printing process, ink is applied to the substrate on the basis of the print control data, in particular by means of the inkjet print heads. This results in preferably clearly delimited homogeneous areas, even when using different primary colors. This leads to a particularly high-quality print image. This priming control data preferably has information about priming dots to be generated. The priming control data preferably have at least one first priming excerpt, to which first priming points to be generated of a first priming agent are assigned. In a first priming operation, based on the priming control data, a first priming agent is applied to the substrate by the priming heads. The first priming process preferably begins before the printing process, but more preferably takes place at least partially simultaneously with the printing process. In the printing process, based on the print drive data, ink is preferentially applied to the substrate both in those areas that were primed in the first priming process and in areas that were not primed in the first priming process.

The advantages that can be achieved with the invention are, in particular, that a high quality of the printed image can be achieved, in particular through a particularly sharp representation and/or through a larger possible color range. In addition, the use of relatively inexpensive and/or relatively thin substrates is also made possible. Compared to an untargeted, full-surface primer, there is a saving in material and costs.

In one embodiment, the method is characterized in that the template image data is analyzed in the analysis process in order to identify the at least one critical boundary line. The analysis process can take place before or after the conversion process. In an alternative or additional embodiment, the method is characterized in that, in particular after the conversion process, the pressure control data are analyzed in the analysis process in order to identify the at least one critical boundary line.

In a development, the method is preferably characterized in that the primer control data are created automatically, in particular by a Machine control and/or a raster image processor of the inkjet printing machine. Then there is less operating effort. In an alternative or additional development, the method is preferably characterized in that the primer control data are created manually and/or with the involvement of an operator. Influence can then be exerted, for example to have particularly critical areas checked.

In an alternative or additional development, the method is preferably characterized in that the template image data are in the form of page description data and/or are written in a page description language.

In an alternative or additional development, the method is preferably characterized in that a computer device and/or a machine controller of the inkjet printing machine has access to at least one stored data record in which a relationship between the inks used and settings for generating primer control data is stored.

In an alternative or additional development, the method is preferably characterized in that the priming control data have information about priming points to be generated and that the priming control data have at least a first priming excerpt to which first priming points to be generated of a first priming agent are assigned and that the priming control data has at least a second Have priming extract, the second priming points to be generated are associated with a second priming agent.

In an alternative or additional development, the method is preferably characterized in that in addition to the at least one first priming process in a base priming process, in particular independently of the primer control data, a base primer is applied in particular over the entire surface of the substrate. The basic priming process can also take place before the so-called first priming process.

In an alternative or additional development, the method is preferably characterized in that the ink jet print heads and/or the priming heads are designed as piezo print heads.

Exemplary embodiments of the invention are shown in the drawings and are described in more detail below.

Show it:

1 shows a schematic representation of a web-fed printing machine which operates according to an inkjet printing method;

FIG. 2 shows a schematic representation of a sheet-fed printing machine that operates according to an ink-jet printing method; FIG.

3 shows a schematic representation of several priming points and pressure points;

4a shows a schematic representation of a template image formed without trapping from two monochromatic areas or homogeneous areas or a corresponding color separation sum;

Fig. 4b is a schematic representation of a first color separation for

Print control data for an original image or a color separation total according to FIG. 4a; Fig. 4c is a schematic representation of a second color separation for

Print control data for an original image or a color separation total according to FIG. 4a;

FIG. 4d shows a schematic representation of a printed image defective due to ink running into one another, based on a template image according to FIG. 4a;

FIG. 4e shows a schematic representation of a grounding excerpt to avoid the errors shown in FIG. 4d; FIG.

5a shows a schematic representation of a template image formed with trapping from two monochromatic areas or a corresponding color separation total, with three homogeneous areas resulting from the overlapping;

Fig. 5b is a schematic representation of a first color separation for

Print control data for an original image or a color separation total according to FIG. 5a;

Fig. 5c is a schematic representation of a second color separation for

FIG. 5d shows a schematic representation of a printed image defective due to ink running into one another, based on a template image according to FIG. 5a;

FIG. 5e shows a schematic representation of a grounding excerpt to avoid the errors shown in FIG. 5d; FIG. Fig. 6a is a schematic representation of operations of the method, wherein

Print drive data is analyzed to identify critical boundary lines;

Fig. 6b is a schematic representation of operations of the method, wherein

Template image data is analyzed to identify critical boundary lines.

A printing press 01 is preferably embodied as an inkjet printing press 01. Printing press 01 preferably has at least one inkjet printing unit 04 embodied as an inkjet printing unit 04. For example, the printing press 01 exclusively has printing units 04 that are embodied as inkjet printing units 04. Alternatively, in addition to at least one inkjet printing unit 04, printing press 01 has at least one printing unit 06 or application unit 06 that operates according to a form-based printing process. Printing press 01 and/or the at least one inkjet printing device 04 preferably has at least one inkjet print head 03 and more preferably a plurality of inkjet print heads 03. The at least one inkjet print head 03 is preferably embodied as a piezo print head 03. Printing press 01 is preferably used for printing substrate 02 or printing material 02. Substrate 02 is embodied, for example, as a substrate web 02 or as at least one and preferably a large number of sheets 02. The printing press 01 is embodied, for example, as a web-fed printing press 01 or as a sheet-fed printing press 01. The substrate 02 is preferably transported along a transport path and/or in a transport direction T through the printing press 01 and/or through the at least one inkjet printing unit 04.

Printing machine 01 preferably has at least one material source 08; 09, which, depending on the type of printing press 01, is embodied, for example, as a sheet feeder 08 or, for example, as a roll unwinding device 09 and/or roll changer 09. Printing press 01 preferably has at least one drying system 11. Printing machine 01 has, for example, at least one substrate delivery device 12; 13, which, depending on the type of printing press 01, is embodied, for example, as a sheet delivery 12 or, for example, as a winding device 13.

The at least one inkjet printing device 04 has, for example, at least one print head arrangement that extends over the entire working width of inkjet printing device 04 and/or printing machine 01. This print head arrangement has at least one print head 03 and preferably a plurality of print heads 03. If there is only one print head 03 per print head arrangement, this one print head 03 preferably extends over the entire working width of the inkjet printing device 04 and/or the printing press 01. However, the case in which a plurality of print heads 03 together form the respective print head arrangement and with their respective working areas is preferred together cover the entire working width of inkjet printing device 04 and/or printing press 01. The working width of inkjet printing unit 04 and/or printing machine 01 is preferably defined as the maximum width that a substrate 02 may have in order to still be able to be processed using inkjet printing unit 04 and/or printing machine 01 and/or corresponds to the maximum using the inkjet printing device 04 and/or the printing press 01, the width of the respective substrate 02 that can be processed.

Inkjet printing machine 01 preferably has at least one first printing position 16 for a first ink. At least one first inkjet print head 03 is preferably assigned to this first printing point 16. The first ink preferably has a first color. Under a respective pressure point 16; 17; 18; 19 is preferably to be understood as the area in which ink drops of one of these printing points 16; 17; 18; 19 associated color are or can be applied to the substrate 02. The inkjet printing machine 01 preferably has at least one second printing point 17 for a second ink. This second pressure point 17 is preferably at least a second one Inkjet print head 03 assigned. The second ink is preferably a second color, more preferably different from the first color. Inkjet printing machine 01 preferably has at least one third printing point 18 for a third ink. At least one third inkjet print head 03 is preferably assigned to this third printing point 18. The third ink is preferably a third color, more preferably different from the first color and from the second color. Inkjet printing machine 01 preferably has at least one fourth printing point 19 for a fourth ink. At least one fourth inkjet print head 03 is preferably assigned to this fourth printing point 19. The fourth ink preferably has a fourth color, which more preferably is different from the first color and from the second color and from the third color. Depending on requirements, the inkjet printing machine 01 has additional printing points for additional inks.

Inkjet printing machine 01 preferably has at least one first priming point 33 for at least one first priming agent. At least one first priming head 07 is preferably assigned to this first priming point 33. Inkjet printing machine 01 more preferably has at least one second priming point 34 for at least one second primer, which more preferably differs from the first primer. At least one second priming head 27 is preferably assigned to this second priming point 34 . Depending on requirements, the inkjet printing machine 01 has further priming points for further priming agents. For example, one priming agent can serve as a full-surface priming, while another priming agent is only relevant for critical boundary lines 26 where there would be a risk that different inks would adversely interact with one another. For example, different primers can be considered and/or used for different combinations of inks.

The at least one first primer point 33 is along a for a transport of substrate 02 is arranged in front of the at least one first printing point 16, more preferably in front of each printing point 16; 17; 18; 19. At least one drying device 11 is preferred after the first printing point 11 and more preferably after each printing point 16; 17; 18; 19 arranged. For example, at least one drying device 11 is provided along the transport path provided for the transport of substrate 02 before the first printing point 11 and after the first priming point 33, more preferably after each priming point 33; 34 arranged.

In a method for operating an inkjet printing machine 01, the print heads 03 are provided with print control data 41. The method is preferably characterized in that print control data 41 for the inkjet print heads 03 for generating a print image 42 printed in particular on the substrate 02 is generated in a conversion process from, in particular, digital template image data 38 of a template image 39. The print control data 41 is preferably generated by means of a computer device 14, which is more preferably a component of the printing press 01 and/or its machine controller. The conversion process includes, for example, the usual processes such as halftoning, screening, etc., which are necessary to generate print control data 41 . The computing device 14 is embodied, for example, as at least a raster image processor 14 and/or has at least one raster image processor 14 .

The print control data 41 contain information about pixels to be generated. This print control data 41 preferably contains information that corresponds directly or indirectly to information about the location at which pixels are to be generated and/or the size of these pixels and/or when the ink drops required for this are to be ejected and/or the size of such ink drops . In the case of piezo print heads 03, such information can be, for example, a profile of a voltage applied to a piezo element represent. This information is preferably stored for each relevant ink.

The print control data 41 define at least one first color separation 21, to which first pixels to be generated of a first color are assigned. The print control data 41 define at least one second color separation 22, to which second pixels to be generated, of a second color that is different in particular from the first color, are assigned.

In an alternative or additional development, the method is preferably characterized in that the print control data 41 define at least one third color separation 23, to which third pixels to be generated are assigned a third color that differs in particular from the first and the second color. In an alternative or additional development, the method is preferably characterized in that the print control data 41 define at least one fourth color separation 24, to which fourth pixels to be generated are assigned a fourth color that differs in particular from the first and the second and the third color. In particular when more than four differently colored inks are used, there are preferably a corresponding number of color separations, for example five, six, seven, eight or even more.

Any color separation 21 is preferred; 22; 23; 24 of a respective pressure point 16; 17; 18; 19 assigned to the inkjet printing machine 01.

A color separation total 47 is the register-correct superimposition of all color separations 21 defined by the print control data 41; 22; 23; 24 to understand. Under a respective homogeneous area 43;

44; 46 is to be understood above and below as a respective area of the color separation sum 47, which is used to generate a respective printed monochromatic area. In particular, this respective printed is monochromatic Surface is assigned the same color impression in its entire surface area, preferably a color impression that can be achieved by itself. This can correspond to a primary color or a secondary color. Each homogeneous area 43; 44; 46 is a respective selection of color separations 21; 22; 23; 24 assigned, the pixels to this homogeneous area 43; 44; 46 contribute. This selection of color separations 21; 22; 23; 24 can, for example, only one color separation 21; 22; 23; 24 included or more. Under a respective pair of unequally composed homogeneous regions 43; 44; 46 are in the preceding and in the following two homogeneous areas 43; 44; 46 to understand their selection of color separations 21; 22; 23; 24 differ. This is preferably independent of the amount of ink applied per color; it is then important that the appropriate ink is applied to this area at all. A respective critical boundary line 26 is such a line at which two homogeneous regions 43; 44; 46 of a respective pair of unequally composed homogeneous regions 43; 44; 46 directly adjoin each other. This adjoining then harbors the risk that “intercolor bleeding” could occur. At least one critical boundary line 26 is identified in an analysis process. For example, several critical boundary lines 26 are identified in the analysis process. This can be the case, in particular, if two desired homogeneous regions 43; 44 a third homogeneous region 46 arises.

In a generation process, priming control data 36 for priming heads 07 is generated on the basis of the at least one identified critical boundary line 26 . In particular, information is preferably created that directly or indirectly corresponds to information about the location at which priming points, i.e. points of priming agent, are to be generated and/or what size these priming points are to have and/or when the necessary drops of priming agent are to be ejected and /or what size such drops of primer should have. The priming control data 36 therefore preferably have information about priming points to be generated. In an alternative or additional development, the method is preferably characterized in that the priming control data 36 has at least one first priming excerpt 31 to which the first priming points to be generated of a first priming agent are assigned. In one embodiment, all critical boundary lines 26 can be covered by a common primer. Alternatively, different primers are available for different combinations of inks.

In a first priming operation, based on the priming control data 36, a first priming agent is applied to a substrate 02 using the priming heads 07.

In a printing process, ink is applied to substrate 02 on the basis of print control data 41 . Depending on the size of the print image to be printed and how far pressure points 16; 17; 18; 19 and primer sites 33; 34 apart, the at least one priming process and the printing process preferably overlap in terms of time. Ink droplets are preferably applied in the printing process both in those areas that were primed in the first priming process and in areas that were not primed in the first priming process.

In an alternative or additional development, the method is preferably characterized in that the template image data 38 is in the form of page description data and/or is written in a page description language, for example at least partially as a PDF document (Portable Document Format).

In an alternative or additional development, the method is preferably characterized in that the template image data 38 is analyzed in the analysis process be used to identify the at least one critical boundary line 26 . A so-called preflight system can be used for this, which analyzes the template image data 38 . In one embodiment, the analysis process takes place before the conversion process. In another embodiment, the analysis process takes place after the conversion process. In principle, the analysis process and the conversion process can also take place at least partially simultaneously.

In an alternative or additional development, the method is preferably characterized in that the pressure control data 41 is analyzed in the analysis process in order to identify the at least one critical boundary line 26 . Then the analysis process is preferably carried out after the conversion process. This can be designed, for example, in such a way that the individual color separations are compared with one another.

In an alternative or additional development, the method is preferably characterized in that the template image data 38 is analyzed in the analysis process in order to identify the at least one critical boundary line 26, and the print control data 41 is analyzed in the analysis process in order to identify the at least one identify critical boundary line 26. A comparison can then take place in order to minimize errors and/or to make the identification of the at least one critical boundary line 26 more precise.

In an alternative or additional development, the method is preferably characterized in that the primer control data 36 is created automatically, in particular by a computer device 14, which is, for example, part of a higher-level machine controller of the inkjet printing machine 01 and/or interacts with the at least one raster image processor and /or itself is at least one raster image processor. In an alternative or additional development, the method is preferably characterized in that the Primer control data 36 are created manually and/or with the participation of an operator.

For example, in a first partial process of an analysis process, homogeneous regions 43; 44; 46 is identified and the at least one critical boundary line 26 is identified in a second sub-process of the analysis process.

In an alternative or additional development, the method is preferably characterized in that the priming control data 36 has information about priming points to be generated and that the priming control data 36 has at least one first priming excerpt 31 to which the first priming points to be generated of a first priming agent are assigned and that the priming control data 36 have at least one second priming extract 32, to which second priming points to be produced of a second priming agent are assigned. For example, the different primer extracts 31; 32 coordinated created.

In an alternative or additional development, the method is preferably characterized in that, in addition to the at least one first priming process, a base priming agent is applied to substrate 02 in a base priming process, for example over the entire surface and/or independently of the priming control data 36. This can serve to enhance the entire printed image 42, regardless of those areas that also require special pretreatment to prevent defects.

In an alternative or additional development, the method is preferably characterized in that the computer device 14 and/or the one machine controller of the inkjet printing machine 01 has access to at least one stored data record in which there is a connection between the inks used and Settings for generating primer control data 36 are stored. More preferably, data on the substrate 02 used is also stored. For example, depending on the combination of substrate 02 and the inks used and depending on the master image 39, the at least one primer extract 31 ; 32 are created. Alternatively or additionally, an operator can make the appropriate settings manually, in particular taking into account the substrate 02 used and/or the inks used and/or the primer used. For example, criteria can then be specified as to the conditions under which areas are recognized as critical boundary lines 26 . For example, it is possible to set how wide an area that is to be provided with primer around a respective critical boundary line 26 should be. In the case of boundary lines 26 lying close to one another, individual priming areas can be combined to form larger priming areas.

For example, a first homogeneous region 43 has pixels at least in the first color separation 21 and possibly also in the second color separation 22 and possibly also in further color separations 23; 24. For example, a second homogeneous region 44 has pixels in the second color separation 22, but not in the first color separation 21, but possibly in further color separations 23; 24. A critical boundary line 26 can then result.

Reference List

01 printing machine, inkjet printing machine, web printing machine, sheet-fed printing machine

02 substrate, substrate web, sheet, printing material

03 ink jet print head, piezo print head

04 Inkjet printing device, inkjet printing unit 05 -

06 printing device, application device

07 priming head, first

08 Source of material, sheet feeder

09 Material source, roll unwinding device, roll changer 10

11 drying device

12 substrate dispenser, sheet delivery

13 substrate delivery device, winding device

14 Computing Device, Raster Image Processor

15 -

16 pressure point, first

17 pressure point, second

18 pressure point, third

19 pressure point, fourth 0 1 color separation, first 2 color separation, second 3 color separation, third 4 color separation, fourth 5 - 6 critical boundary line Priming head, second computer device - - priming extract, first priming extract, second priming point, first priming point, second - priming control data - template image data template image - print control data print image homogeneous area homogeneous area - homogeneous area color separation total transport direction

Claims

Expectations

1. A method for operating an inkjet printing machine (01), wherein print control data (41) for inkjet print heads (03) for generating a print image (42) are generated in a conversion process from template image data (38) of a template image (39), and wherein the print control data (41) Have information about pixels to be generated and wherein the print control data (41) define at least a first color separation (21) to which first pixels to be generated of a first color are assigned and wherein the print control data (41) define at least a second color separation (22), the second pixels to be generated are assigned to a second color, and a color separation sum (47) means the register-correct superimposition of all color separations (21; 22; 23; 24) specified by the print control data (41), and a respective homogeneous area (43; 44 ; 46) a respective area of the color separation sum (47) is to be understood, which is used to generate a respective printed monochromatic area and wherein each homogeneous area (43; 44; 46) a respective selection of color separations (21; 22; 23; 24) is assigned which contribute pixels to this homogeneous area (43; 44; 46) and wherein under a respective pair of unequally composed homogeneous areas (43; 44; 46) respectively two homogeneous areas (43; 44; 46) are to be understood, whose selection of color separations (21; 22; 23; 24) differ and wherein a critical boundary line (26) is such a line at which two homogeneous areas (43; 44; 46) of a respective pair of unequally composed homogeneous regions (43; 44; 46) directly adjoin one another and wherein the template image data (38) and/or the print control data (41) are analyzed in an analysis process in order to identify at least one critical boundary line (26). and wherein in a generating process based on the at least one identified critical boundary line (26)

Priming control data (36) for priming heads (07) are generated and wherein in a first priming operation based on the priming control data (36), a first priming agent is applied to a substrate (02) using the priming heads (07) and ink is applied to the substrate (02) in a printing operation based on the print control data (41). .

2. The method according to claim 1, characterized in that the primer control data (36) are created automatically.

3. The method as claimed in claim 1, characterized in that the primer control data (36) are created automatically by a machine controller and/or a raster image processor of the inkjet printing machine (01).

4. The method according to claim 1 or 2 or 3, characterized in that the primer control data (36) are created manually and/or with the assistance of an operator.

5. The method according to claim 1 or 2 or 3 or 4, characterized in that the template image data (38) are in the form of page description data.

6. The method according to claim 1 or 2 or 3 or 4 or 5, characterized in that a computer device and/or a machine controller of the inkjet printing machine (01) has access to at least one stored data record in which a connection between the inks used and settings for generating of primer control data (36) are stored.

7. The method of claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the primer control data (36) information about have generating primer points and that the

Priming control data (36) specify at least one first priming extract (31) to which first priming points to be generated of a first priming agent are assigned and that the priming control data (36) specify at least one second priming extract (32) to which second priming points to be generated of a second priming agent are assigned.

8. The method according to claim 7, characterized in that the different primer extracts (31; 32) are created in a coordinated manner.

9. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that in addition to the at least one first priming process, a base priming agent is applied to the substrate (02) in a base priming process.

10. The method according to claim 9, characterized in that in the base priming process, the base priming agent is applied to the substrate (02) independently of the priming control data (36).

11. The method according to claim 9 or 10, characterized in that in the base priming process, the base priming agent is applied to the entire surface of the substrate (02).

12. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11, characterized in that the inkjet print heads (03) are designed as piezo print heads (03).

13. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12, characterized in that the priming heads (07) are designed as piezo print heads (03).

14. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13, characterized in that the pressure control data (41) are generated by means of a computer device (14), which is part of the inkjet printing machine (01) and/or its machine control.

15. The method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14, characterized in that each color separation (21; 22; 23; 24) of a respective Printing position (16; 17; 18; 19) of the inkjet printing machine (01) is assigned.