Method for printing a decoration to be printed, and device
The method addresses color deviations in digital printing by measuring and adjusting digital templates and settings, ensuring accurate color fidelity before further processing, thereby reducing waste and costs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SWISS KRONO TEC AG
- Filing Date
- 2025-11-04
- Publication Date
- 2026-05-15
AI Technical Summary
Existing digital printing methods for decorative designs on printing surfaces suffer from color deviations, necessitating multiple correction rounds and resulting in scrap due to non-conforming products, thereby increasing production costs.
A method involving determining a digital template and reference color measurement data, printing a part of the design, measuring color parameters, comparing with reference data, and adjusting the template/settings if deviations exceed a criterion, ensuring accurate color fidelity before further processing.
Reliably detects and corrects color deviations, reducing material waste and production costs by minimizing unnecessary processing steps and ensuring high-quality print outputs.
Smart Images
Figure EP2025081869_15052026_PF_FP_ABST
Abstract
Description
[0001] G intraallemctumal pr Lopienrtsy
[0002] SWISS KRONO Tec AG Legal File: Museggstrasse 14 2459-0772 PCT-1 6004 Lucerne Date:
[0003] Switzerland, November 4, 2025
[0004] Method for printing a decoration to be printed and apparatus
[0005] The present invention relates to a method for printing a decoration to be printed onto a plurality of printing surfaces using a digital printing system and to a device for carrying out the method.
[0006] From EP 4 216 531 A1, a method for printing a paper web with a print motif using a digital printing system is known. First, a reference decor pattern, containing a section of a digital image of the original print motif, and a hyperspectral reference data set for the reference decor pattern are provided. Then, a copy of the reference decor pattern is printed, and a hyperspectral data set for the printed copy is created. For this purpose, the reference copy and the printed copy are impregnated as a whole, pressed onto a core, and subsequently checked for color fidelity and reproducibility.
[0007] A disadvantage is that even with this type of printing process, deviations can occur between the printed designs and the desired designs. Color differences between the designs cannot be reliably detected, so several correction rounds are often necessary to obtain printed designs that meet the requirements. Each correction results in scrap due to the designs that do not meet the requirements, thus increasing overall production costs.
[0008] The invention is therefore based on the objective of providing a method and a device that eliminate or at least mitigate the disadvantages. The invention solves this problem by providing a method for printing a design onto a plurality of printing surfaces using a digital printing system, the method comprising the following steps: a) determining a digital template and reference color measurement data of a design to be printed, which were determined by measuring color values of a design, b) printing at least a part of the design to be printed based on the digital template onto at least one printing surface with printing settings of the digital printing system, so that at least one print proof is produced, c) measuring color parameters of the at least one print proof, so that print color measurement data is obtained.d) Compare the print color measurement data with the reference color measurement data and determine an initial measure of the deviation of the print color measurement data from the reference color measurement data; e) Change the digital template and / or the print settings of the digital printing system if the initial measure of deviation meets a first predetermined criterion; f) Repeat steps b) to e) if the initial measure of deviation meets the first predetermined criterion.
[0009] Preferably, in process step b) the entire decoration is printed.
[0010] Preferably, the reference color measurement data of the decor to be printed were determined by measuring the color values of an unprocessed decor. Preferably, the at least one print proof is unprocessed. Preferably, at least one unprocessed print proof is produced in step b). Preferably, the at least one unprocessed print proof is measured in step c).
[0011] Alternatively, the pre-printed proof can be further processed or can be further processed. In particular, it is possible to further process the pre-printed proof before measuring color parameters, especially by impregnation, application of an overlay, and / or pressing. In a method according to the invention, color parameters are measured, i.e., corresponding print color measurement data are recorded, and compared with stored reference color measurement data. The print color measurement data are acquired using the unprocessed pre-printed proof, which, after printing the decoration onto the printing surface in process step b), is preferably not further processed. In particular, no further impregnation with a synthetic resin or a varnish, no laminating or mounting onto a core, for example, a wood-based panel, no application of an overlay, and no pressing under pressure and temperature influence takes place before the print color measurement data is acquired.Further impregnation with a synthetic resin refers in particular to the application of synthetic resin to a printed surface of a wood-based panel. Laminating or bonding onto a core board refers in particular to the application of a printed wood-based panel to a core board. Preferably, the wood-based panel is then particularly thin, especially less than 5 mm thick. Preferably, the core board is another wood-based panel, preferably a particleboard or a fiberboard, especially an HDF, MDF, or OSB panel. All these steps are advantageous in the production of laminate panels that can be used as flooring, wall and / or ceiling cladding or as furniture panels.They are preferably carried out in the manufacture of such objects; however, in a method according to the invention, the color parameters are measured first after the decoration has been printed onto the printing surface.
[0012] Within the scope of the present invention, the term "unprocessed" for the print proof means, in particular, that no impregnation, mounting, or laminating onto a core, no application of an overlay, and no pressing of the print proof under pressure and temperature influence takes place before the printing color measurement data is obtained. For the purposes of the present invention, a print proof is not yet further processed, except that it may have been dried after printing. Specifically, the print proof is thus unprocessed if it has not been further processed beyond a possible drying step. However, drying is not absolutely necessary for the print proof to be considered unprocessed. Rather, it is also conceivable that the print proof is dried alternatively or additionally after the printing color measurement data has been measured.
[0013] According to the invention, the reference color measurement data are obtained by measuring color parameters on an unprocessed decor, preferably an unprocessed reference decor. Preferably, the decor on which the color parameters are measured to obtain color measurement values is fed to the sensor with which the measurement is to be carried out directly after the respective decor has been printed onto the printing surface. In some embodiments of the method, it is advantageous to dry the decor after printing and only then feed it to the sensor. It is advantageous if the printed proof undergoes the same steps before measuring the color parameters that the reference decor underwent before the reference color measurement data was obtained. The reference decor is therefore also referred to as the reference proof.
[0014] The comparison of the unprocessed, printed proof with a corresponding unprocessed, printed reference proof is carried out using the various color measurement data. The printed color measurement data is compared with the reference color measurement data, both of which, according to the invention, refer to unprocessed decors, i.e., proofs. The reference color measurement data corresponds in particular to the data measured on a reference proof that can serve as a reference, i.e., that corresponds exactly to the desired, unprocessed decor.
[0015] The digital template preferably corresponds to the printing instructions for the digital printing system, specifying which color value should be assigned to which area of the print surface. For example, the digital template can be an image file such as a JPEG (Joint Photographic Experts Group) or TIFF (Tagged Image File Format) file, or a print file such as a PDF (Portable Document Format) file, a PCL (Printer Command Language) file, or a PostScript file. Such a print file can also be generated from an image file like a JPEG or from other working documents. The digital template is distinct from the print settings of the digital printing system, which are not part of the digital template.These settings are preferably stored in a digital memory within the digital printing system and contain, in particular, information about the quantity of which ink should be applied for a given color value in the digital template. These print settings thus contain information about how a digital printing system responds to the print instructions. The printing system is used to apply an image, corresponding to the print instructions and the information they contain, to the printing surface. These print instructions contain information about colors, color values, and tonal values to be generated by the digital printing system. The digital printing system must translate these print instructions into information about how much ink of a specific color should be applied to which area of the printing surface.The print settings are used for this purpose, which in this respect correspond to a calibration of the digital printing system. In particular, changing the print settings does not adjust the digital template, especially the color values it contains, nor does it preprocess the printing instructions in any other way, but it does change the printed result.
[0016] Preferably, the first predetermined criterion is met if a deviation of one or more of the print color measurement data from corresponding reference color measurement data is greater than a first predetermined limit value for the corresponding measurement quantity. If, in the inventive method, a first measure of deviation is detected that meets a first predetermined criterion, for example, exceeding a first predetermined limit value for the first measure of deviation, the digital template and / or the print settings of the digital printing system are changed. This ensures that the first measure of deviation is lower in a subsequent printing process using the modified digital template and / or the modified print settings of the digital printing system. If necessary, the first predetermined criterion is then no longer met, i.e., the first predetermined limit value for the first measure of deviation is no longer exceeded.If the first deviation measurement does not meet the first predetermined criterion, the printed proof is qualitatively equivalent to the desired, unprocessed decoration. However, if the first deviation measurement does meet the first predetermined criterion, an adjustment of the digital template and / or the printing settings is required. In this case, the printed proof does not meet the print quality requirements and must be rejected. The first deviation measurement is preferably determined separately for each parameter being measured and compared.
[0017] An advantage of the method according to the invention is that color deviations in the decorations can be reliably detected and thus corrected by the digital printing system. Other influences, such as those resulting from impregnation, overlay, and / or pressing, are disregarded, so their effects on color fidelity are not reflected in the detected color deviations of the preliminary samples. At the same time, the absence of impregnation, overlay, and / or pressing of decorations that do not meet the print quality requirements eliminates significant wasted production effort, thereby effectively reducing manufacturing costs.
[0018] Preferably, the printing surface is the top surface of a wood-based panel, more preferably a particleboard or a fiberboard, for example, an HDF (high-density fiberboard), an MDF (medium-density fiberboard), or an OSB (oriented strand board). In advantageous embodiments of the process, the top surface of the wood-based panel is pretreated to create the printing surface. For example, the top surface of the wood-based panel is sanded, primed with a synthetic resin, primed with a colored primer, for example, by applying one or more coats of a color, such as white, and / or coated with a primer onto which the design is subsequently printed. Preferably, the surface of the wood-based panel is dried in a dryer at least once, preferably after each of the aforementioned preparation steps, in which a liquid is applied to the top surface.Preferably, the top surface of the wood-based panel has only one printing surface. Alternatively, the top surface of the wood-based panel has several printing surfaces. Preferably, in step b), several color variations of a section of the decor to be printed are printed with different color settings onto the at least one printing surface. In particular, at least one unprocessed print prototype is then produced in step b).
[0019] The color variations all refer to the same section of the design to be printed. The different color settings primarily involve different color settings in the digital template and / or different color settings in the print settings used for each color variation. In other words, the digital template may have different colors depending on the color variation, and / or different print settings may be used depending on the color variation.
[0020] Preferably, steps c) and d) are performed for each of the color variants. Preferably, after step d), the color variant with the smallest first degree of deviation is determined. Preferably, steps e) and f) are performed at least for the color variant with the smallest first degree of deviation. This configuration is particularly advantageous when the printing surface is the top side of a wood-based panel. Especially with this direct-to-substrate printing, material waste can often be reduced. Frequently, faster ink removal is possible in this way.
[0021] Overall, this can significantly reduce the costs for color approval before series production in many designs.
[0022] In a preferred embodiment, in step e), the digital template and / or the print settings of the digital printing system are changed depending on the color settings of the color variants and the associated first dimensions of the deviation. Preferably, at least 4, more preferably at least 8, more preferably at least 12, and in particular at least 20 color variants of the section are printed.
[0023] Preferably, at least in the first pass of step b), several color variations of the section of the decoration to be printed are printed with different color settings onto the at least one printing surface. Preferably, at least in a subsequent pass of step b), several color variations of the section of the decoration to be printed are printed with different color settings onto one or more printing surfaces. Preferably, this section is the same section that was printed in the first pass of step b).
[0024] Preferably, in step b), several color variants of multiple sections of the design to be printed are printed with different color settings onto one or more printing surfaces. Preferably, the same number of color variants are printed for each section. Preferably, one color variant of one section corresponds to a color variant of the other section(s). In particular, the corresponding color variants each have the same color settings. For example, the corresponding color variants are printed using the same digital template and / or with the same print settings of the digital printing system. Preferably, steps c) and d) are performed for each color variant of the individual sections. Preferably, a first overall deviation measurement is determined based on the first measurements of the deviation of the color variants of the individual sections with the same color settings.In particular, for each of the color settings, a first overall deviation measurement is determined based on the color variants printed with those color settings. Preferably, steps e) and f) are then performed at least for the color variants with the lowest first overall deviation measurement. Preferably, in step e), the digital template and / or the print settings of the digital printing system are changed if the first overall deviation measurement meets the first predetermined criterion, and in step f), steps b) to e) are repeated if the first overall deviation measurement meets the first predetermined criterion.
[0025] Preferably, at least in the first pass of step b), several color variants of several sections of the design to be printed are printed with different color settings onto at least one printing surface. Alternatively or additionally, at least in a subsequent pass of step b), several color variants of several sections of the design to be printed are printed with different color settings onto at least one printing surface.
[0026] Preferably, the cutout covers at most 50%, more preferably at most 30%, more preferably at most 20%, and in particular at most 10% of the total size of the decoration to be printed.
[0027] Preferably, several, and preferably all, color variants are printed on a single printing surface. In this case, an unprocessed print proof has several, preferably all, color variants. Alternatively, each color variant is printed on a separate printing surface. In particular, only a single color variant is then printed on each printing surface. Preferably, each color variant is then printed on a separate wood-based panel.
[0028] In this case, each unprocessed print proof only has one color variant.
[0029] Preferably, several, preferably all, color variants of the respective section are printed onto a single printing surface. Preferably, the different sections are each printed onto separate printing surfaces. In particular, the respective printing surface then displays only one or more, preferably all, color variants of the associated section. Alternatively or additionally, several, preferably all, corresponding color variants of the sections are printed onto a single printing surface. Preferably, the respective printing surface then displays only several, preferably all, corresponding color variants. In particular, the respective printing surface then contains only color variants that have been printed with the same color settings.
[0030] Preferably, in step b), several color variants of several decors to be printed are printed onto at least one printing surface. More preferably, in step b), several color variants of at least one section of the decors to be printed, or more preferably several sections of the decors to be printed, are printed onto the at least one printing surface. For example, three decors are printed in four different color variants each. The advantage of this is that production release for several decors to be printed can be achieved in a single print run, thus enabling particularly efficient color release.
[0031] Preferably, several color variants, preferably all color variants, in particular all color variants of a respective section, are printed in one printing pass, especially simultaneously.
[0032] Preferably, providing the reference color measurement data in step a) includes the following steps: a1) providing a digital template of a decor to be printed, a2) printing at least a part of the decor to be printed based on the digital template onto at least one reference surface, so that at least one reference prototype is created, a3) measuring the color measurement parameters of the at least one unprocessed reference prototype, so that the reference color measurement data are obtained.
[0033] Preferably, in step a2), the same part, in particular the same section or sections, of the design to be printed is printed as in step b). The printing surface to be printed during the process preferably corresponds to the reference surface, for example, in material, size, texture, and / or color. The closer the printing surface corresponds to the reference surface, the more accurately and easily the reference color measurement data can be compared with the printing color measurement data. If a deviation between the reference surface and the printing surface is known, a conversion tool can be used to improve the correspondence and comparability of the color measurement data.
[0034] Preferably, the print color measurement data covers the same locations and / or the same area of the design as the reference color measurement data, thus ensuring comparability of the color measurement data. Preferably, the print color measurement data and the reference color measurement data cover the entire design or the entire part of the design printed in step b). This means, in particular, that a plurality of measurement points are available at which the respective color measurement data are determined, and that this plurality of measurement points extends over the entire design or the part of the design printed in step b). Alternatively, the print color measurement data and the reference color measurement data do not cover the entire design. For example, it may be advantageous to collect print color measurement data and reference color measurement data at one or more locations and / or in one or more areas of the design, for example, at prominent points.Preferably, the measuring points are distributed equidistantly over the measured area or locations.
[0035] Preferably, the color measurement data includes hyperspectral data. This preferably applies to both the print color measurement data and the reference color measurement data.
[0036] The respective color measurement data are preferably obtained by hyperspectral area measurement. The color value for a measurement pixel is determined by measuring an area of which the measurement pixel is a part and calculating an average value, which is then stored as the color value for the respective measurement pixel. The area being measured is larger than the measurement pixel and preferably includes other pixels. The measurement pixel is preferably located in the center of the area. The average value can be calculated across all measured pixels. The respective data of the measured pixels can be summed and divided by the number of pixels to determine the average value. The data of the different pixels are preferably assigned different weights in the sum thus created, with the measurement pixel receiving the highest weight. The further a pixel is from the measurement pixel, the smaller the weight preferably assigned to its corresponding data.
[0037] Since both the print color measurement data and the reference color measurement data were measured on a prototype, the comparison can only identify deviations caused by the work steps already carried out in the production of that prototype. Most of these deviations are caused by the digital printing system and the ink used in it. Deviations caused by subsequent work steps cannot, by their very nature, be detected. In order to also capture these and, if necessary, to make corrective measures and adjustments, it is advantageous to also measure the processed decor, for example, in the form of a manufactured laminate panel, and determine corresponding color values. These are therefore obtained not by measuring a prototype, but by measuring a finished product.To enable a comparison with target values, it is advisable to also perform corresponding measurements on a reference sample. The resulting reference sample color measurement data are preferably provided in step a).
[0038] Preferably, step a) therefore also includes providing reference copy color measurement data. Preferably, the method comprises at least one of the following steps: g) further processing the at least one pre-printed copy with predetermined finishing parameters so that at least one printed copy is produced; h) measuring color parameters of the at least one printed copy so that printed copy color measurement data is obtained; i) comparing the printed copy color measurement data with the reference copy color measurement data and determining a second measure of deviation of the printed copy color measurement data from the reference copy color measurement data; j) changing the digital template, the printing settings of the digital printing system, and / or the finishing parameters if the second measure of deviation meets a second predetermined criterion; k) repeating steps b) to j) if the second measure of deviation meets the second predetermined criterion.
[0039] The at least one unprocessed print prototype is preferably characterized by the fact that further processing according to step g) has not yet taken place, in particular has not taken place before the print color measurement data is obtained.
[0040] Preferably, steps c) to f) are performed for a first number of print surfaces printed in step b), and steps h) to k) are performed for a second number of print surfaces printed in step b). Preferably, the first number is larger than the second number. For example, it may be advantageous to perform steps c) to f) for each of the print surfaces printed in step b) and steps h) to k) only for a smaller proportion of the print surfaces printed in step b).
[0041] In a preferred embodiment, further processing comprises at least one of the following steps: l) applying an overlay to the at least one printing surface, m) pressing the overlay with the at least one printing surface under pressure and temperature influence.
[0042] Preferably, step a) included providing reference copy measurement data, the method further comprising: - impregnating the pre-printed copy, applying an overlay and / or pressing with predetermined further processing parameters, so that at least one printed copy is produced,
[0043] - Measuring color parameters of at least one printed copy, so that printed copy color measurement data is obtained,
[0044] - Comparing the printed copy color measurement data with the reference copy color measurement data and determining a second measure of the deviation of the printed copy color measurement data from the reference copy color measurement data,
[0045] - Changing the digital template, the print settings of the digital printing system and / or the post-processing parameters, if the second measure of deviation meets a second predetermined criterion,
[0046] - Repeat steps b) to j) if the degree of deviation meets the second predetermined criterion.
[0047] The further processing parameters include, for example, the application weight of the impregnating agent, a drying temperature, a drying time, a pressing pressure, a pressing temperature and / or a pressing time.
[0048] The second predetermined criterion is preferably met if a deviation of one or more of the printed copy color measurement data from corresponding reference copy color measurement data is greater than a second predetermined limit value for the corresponding color measurement parameter. Preferably, the second predetermined limit value corresponds to the first predetermined limit value. Alternatively, the second predetermined limit value can be smaller or larger than the first predetermined limit value.
[0049] The first predetermined limit value and / or the second predetermined limit value are preferably color-dependent and / or location-dependent. Preferably, the provision of reference sample color measurement data comprises the following steps: a4) further processing, in particular by impregnation, application of an overlay and / or pressing, of the at least one reference pre-sample with predetermined further processing parameters, so that at least one reference sample is produced; a5) measuring parameters of the at least one reference sample, so that reference sample color measurement data is produced.
[0050] Preferably, the corresponding copy is not checked for every checked pre-copy, but only for at most every second, preferably at most every fifth, most preferably at most every tenth, printed surface in the process in step b).
[0051] Preferably, steps c) to f) are performed for each printed surface in the process in step b). Preferably, steps c) to f) are performed for a first number of printed surfaces and the inspection of the copies, preferably at least one of steps g) to k), and in particular all of steps g) to k), are performed for a second number of printed surfaces, the first number preferably being larger than the second number. Advantageously, steps g) to k) are not performed for every, and in particular only for one, of the color variants of the respective section, and in particular only for the color variant with the smallest first degree of deviation. Alternatively, the first number can be equal to or smaller than the second number.
[0052] Preferably, the color parameters of the at least one unprocessed print proof are measured in the digital printing system. Preferably, the color parameters of the at least one unprocessed print proof are measured at least partially, but preferably completely, during the printing of at least a portion of the decoration to be printed in process step b). This allows for particularly efficient and cost-effective color approval of the decorations. Preferably, the color parameters of the at least one unprocessed reference proof are measured in the digital printing system. Preferably, the color parameters of the at least one unprocessed reference proof are measured at least partially, but preferably completely, during the printing of at least a portion of the decoration to be printed in process step a2).
[0053] Preferably, the printed copy color measurement data covers the same locations and / or the same area as the reference copy color measurement data.
[0054] Preferably, the reference color measurement data and the print color measurement data, on the one hand, and / or the reference copy color measurement data and the print copy color measurement data, on the other hand, each comprise at least one color intensity and / or at least one luminance. Preferably, the at least one color intensity and / or the at least one luminance of a specific color is included. Color intensity is understood to mean, in particular, a measure of the saturation of the respective color.
[0055] Preferably, the color parameters of at least one unprocessed print proof and the color parameters of at least one unprocessed reference proof are measured under initial predetermined lighting conditions. This ensures good comparability between the print color measurement data and the reference color measurement data. The initial lighting conditions are identical for both measurements.
[0056] Preferably, the color parameters of at least one printed copy and the color parameters of at least one reference copy are measured under two predetermined lighting conditions. These second lighting conditions are identical for both measurements. Preferably, the first predetermined lighting conditions correspond to the second predetermined lighting conditions. For example, measurements can be taken under standard illuminant, in particular D50 standard illuminant or D65 standard illuminant, under mixed illuminant, or under daylight. It is possible to perform the measurements several times under different lighting conditions, thus obtaining different measurement data for the respective lighting conditions and ensuring color fidelity under various lighting conditions.
[0057] A further development of the invention is characterized in that in step b) only a part, in particular at least one section, of the decoration to be printed is printed onto a printing surface, wherein the method further comprises the following steps: n) printing the complete decoration to be printed on the basis of the digital template onto a first plurality of printing surfaces with the printing settings of the digital printing system.
[0058] Printing the complete design to be printed onto the first set of printing surfaces constitutes series production. The first set of printing surfaces preferably comprises more than 2, more preferably more than 10, particularly preferably more than 100, and especially more than 1000. An advantage of this method is that color approval for series production can be carried out cost-effectively.
[0059] A partial section of the design to be printed can first be selected as a digital template. In step b), only this partial section of the design is then printed onto a printing surface. For printing the complete design in step n), a production file is preferably created based on the digital template, incorporating the changes made to the digital template. Alternatively, the production file can correspond to a complete template file from which the digital template was created. In both cases, for the purposes of understanding the present invention, the printing of the complete design is carried out "based on the digital template." According to a second aspect, the invention relates to a device for carrying out the method according to the invention.Preferably, the device comprises a digital printing system configured to print at least a portion of the design to be printed, based on the digital template, onto at least one printing surface with print settings. Preferably, the device includes at least one sensor configured to measure color parameters of the at least one unprocessed print proof, thus obtaining print color measurement data. Preferably, the device includes an electrical control unit, for example, an electronic data processing unit, on which reference color measurement data and, preferably, reference proof color measurement data are stored. Preferably, the electrical control unit includes a comparison module configured to compare the print color measurement data with the reference color measurement data and to determine a first measure of the deviation of the print color measurement data from the reference color measurement data.The electrical control is preferably configured to change the digital template and / or the print settings if the first deviation meets a first predetermined criterion. Preferably, the device includes a memory in which the print settings are stored. Preferably, the device includes a transport device for feeding and removing print surfaces into and out of the printing unit.
[0060] In a further development of the invention, the device comprises a processing unit, in particular a pressing unit, which is configured for further processing the at least one pre-printed copy, in particular by impregnating the at least one pre-printed copy, applying an overlay, and / or pressing with predetermined processing parameters, so that at least one printed copy is produced. Alternatively or additionally, the device is connected to a processing unit, in particular a pressing unit. Preferably, the device or the processing unit, in particular the pressing unit, comprises a sensor which is configured for measuring color parameters of the at least one printed copy, so that printed copy color measurement data is obtained.Preferably, the device or finishing unit, in particular the pressing unit, includes a comparison module configured to compare the printed copy color measurement data with the reference copy color measurement data and to determine a second measure of the deviation of the printed copy color measurement data from the reference copy color measurement data. Preferably, the device or finishing unit, in particular the pressing unit, includes an electronic data processing unit configured to change the digital template, the printing settings, and / or the finishing parameters if the second measure of deviation meets a second predetermined criterion.
[0061] Example 1 - Offline walnut decor
[0062] At a wood-based materials manufacturer, specializing in laminate flooring panels, wood, stone, and fantasy decors are produced using an inkjet flatbed digital printing system. Digital print data with a resolution of at least 300 dpi is required for color selection and production. When a new walnut wood decor is added, decor data is generated and retouched to ensure the grain and pattern appear harmonious and can be approved. For color selection, an A3 section is extracted from this file at a defined position and saved as a new selection file. Several color versions are created from this selection file, from which color version 12 is chosen for the collection. Upon approval of the color versions, two printed samples are produced for each. One sample is dried and pressed to create a reference sample that can be used for final approval.For example, reference color measurement data can be collected from the reference sample, or a visual comparison can be made with a pressed printed sample. The second sample remains unprocessed and is therefore a reference pre-sample. Reference color measurement data can be collected from this unprocessed reference pre-sample using a hyperspectral measuring device. The effects of pressing are disregarded for this sample. The reference color measurement data is saved. In addition, the color settings of color version 12 from the rejection file are transferred to the full production file and saved. Furthermore, a smaller file (comparison file) containing the defined A3 section from color version 12 is created and saved. The comparison file corresponds to the section of the reference pre-sample.When the production order for the walnut decor is placed (18 days later), the comparison file is printed first, and the printed proof is measured with a hyperspectral measuring device without any further processing to obtain print color measurement data. This print color measurement data is compared with the reference color measurement data. A deviation of 8.6% is detected. The tolerance for this deviation was set at 5%. Therefore, the decor does not yet meet the print quality requirements. Based on the measured values and the calculated differences in the parameters L, a, b (Lab color space) or H, L, and C (HLC color space), the comparison file (digital template) is modified and reprinted on the flatbed digital printing system. The new proof is then measured again until version 12-4 achieves a deviation of 2.6%. These color changes are then incorporated into the production file for the entire decor and, if necessary,A new comparison file is also created for any subsequent approval of the design. Sample print proofs that meet the print quality requirements are dried, impregnated, and pressed to produce print samples. These print samples are measured to obtain print sample color measurement data, enabling additional visual control for production approval, for example, by comparison with the reference sample color measurement data or by other optical comparison with a physical reference sample.
[0063] Example 2 - Inline oak decor
[0064] At a wood-based materials manufacturer, wood, stone, and fantasy decors are printed on an inkjet flatbed digital printing system. The system incorporates an inline hyperspectral colorimeter. Measuring the print proof to obtain color data for printing can therefore be done directly on the system, and especially at least partially during the printing process. Digital print data with a resolution of at least 300 dpi is required for color matching and production. When creating a new oak wood decor, 14 different real wood boards are scanned and digitized using a high-resolution scanner. This data is then retouched using software to a format of 205 x 130 cm to ensure that the grain and pattern appear harmonious and can be approved.For color selection, an A3 section is extracted from this file at a defined position and saved as a new selection file. From this selection file, various color versions are created and printed on the digital paper printing press, dried, and pressed until color version 8 is selected for the collection. The color settings of color version 8 are then transferred from the selection file to the full production file and saved. When the color versions are approved, two printed samples are produced for each version. One sample is dried and pressed to create a reference sample that can be used for approval. For example, reference sample color measurement data can be collected from the reference sample, or a visual comparison can be made with a pressed printed sample. The second sample remains unprocessed and thus serves as a reference pre-production sample.The unprocessed reference sample is measured inline at the four key positions using a hyperspectral measuring device, resulting in reference color measurement data that is then stored.
[0065] At the start of the first production run of the oak decor (24 days later), the production file is printed and measured inline with a hyperspectral measuring device at the four key positions of the unprocessed print proof, thus generating print color measurement data. Software detects a deviation of 5.5% between the print color measurement data and the reference color measurement data. The tolerance for the oak decor was set at 7%. The decor can therefore be produced, and a quality certificate can be generated based on the print color measurement data.
[0066] Character description
[0067] With the aid of the accompanying drawing, an embodiment of the present invention is explained in more detail below. Figure 1 shows a schematic representation of the sequence of a method according to a first embodiment of the present invention.
[0068] Figure 1 schematically illustrates the process according to a first embodiment of the present invention. In a first step 2, a digital template and reference color measurement data of a design to be printed are provided. In a second step 4, at least a portion of the design to be printed is printed onto a printing surface using the digital template and the print settings of the digital printing system, thus creating a print proof. The digital template contains printing instructions for the digital printing system, specifying which color value is to be displayed at which location on the printing surface.
[0069] In a third step (6), color parameters of the unprocessed print proof are measured to obtain print color measurement data. The advantage of measuring the unprocessed print proof lies particularly in the fact that color deviations of the decor can be reliably identified and then easily corrected. The effects of subsequent processing steps on color fidelity are not included in the identified color deviation, allowing for targeted optimization of print quality. Furthermore, the costs associated with impregnating and pressing decors that do not meet print quality requirements are eliminated, effectively reducing production costs.
[0070] In a fourth step (8), the determined print color measurement data is compared with the reference color measurement data, and an initial measure of the deviation between the print color measurement data and the reference color measurement data is determined. If this initial measure of deviation meets a first predetermined criterion, for example, if a first predetermined limit for a maximum color deviation, such as a Delta E of 1, between the print color measurement data and the reference color measurement data is exceeded, the digital template and / or the print settings of the digital printing system are changed in a fifth step. In the sixth step (12), it is determined whether the initial measure of deviation meets the first predetermined criterion. If so (Y), the correction process starts again from step 4. If not (N), the correction process is complete.The printed decor then lies, for example, within a specified tolerance to the reference color measurement data.
[0071] In an optional seventh step 14, series production of the (complete) decor can take place.
[0072] To further reduce the costs of color approval, it can be advantageous in step 4 to print only a portion of the design to be printed onto a printing surface at a time. Subsequently, series production (step 14, seventh) can take place, in which the complete design to be printed is printed onto a large number of printing surfaces using the corrected settings.
Claims
SWISS KRONO Tec AG Legal file: Museggstrasse 14 2459-0772 PCT-1 6004 Lucerne Switzerland Date: November 4, 2025 Patent claims 1. A method for printing a design to be printed onto a plurality of printing surfaces using a digital printing system, comprising the following steps: a) providing a digital template and reference color measurement data of a design to be printed, which were determined by measuring color parameters of a design; b) printing at least a part of the design to be printed, based on the digital template, onto at least one printing surface using the printing settings of the digital printing system, so that at least one print proof is produced; c) measuring color parameters of the at least one print proof to obtain print color measurement data; d) comparing the print color measurement data with the reference color measurement data and determining a first measure of any deviation of the print color measurement data from the reference color measurement data; e) modifying the digital template and / or the printing settings of the digital printing system.f) Repeat steps b) to e) if the first measure of deviation meets a first predetermined criterion.
2. Method according to claim 1, characterized in that the reference color measurement data were determined by measuring color measurement parameters of an unprocessed decor and that at least one printed proof is unprocessed.
3. Method according to one of the preceding claims, characterized in that the printing surface is the top surface of a wood-based panel.
4. Method according to one of the preceding claims, characterized in that in step b) several color variants of a section of the decor to be printed with different color settings are printed onto the at least one printing surface.
5. Method according to claim 4, characterized in that steps c) and d) are performed for each of the color variants.
6. Method according to claim 4 or 5, characterized in that after step d) the color variant with the smallest first degree of deviation is determined.
7. Method according to one of claims 4 to 6, characterized in that steps e) and f) are carried out at least for the color variant with the smallest first degree of deviation.
8. Method according to one of claims 4 to 7, characterized in that at least in a first pass of step b) and / or at least in a subsequent pass of step b) several color variants of the section of the decor to be printed with different color settings are printed onto the at least one printing surface.
9. Method according to one of claims 4 to 8, characterized in that at least 4, preferably at least 8, more preferably at least 12, in particular at least 20 color variants of the cutout are printed.
10. Method according to one of claims 4 to 9, characterized in that in step b) several color variants of several sections of the decoration to be printed are printed.
11. Method according to one of claims 4 to 10, characterized in that several, preferably all, color variants are printed on a printing surface.
12. Method according to one of the preceding claims, characterized in that the provision of the reference color measurement data in step a) comprises the following steps: a1) providing a digital template of a decor to be printed, a2) printing at least a part of the decor to be printed based on the digital template onto at least one reference surface, so that at least one reference prototype is created, a3) measuring the color measurement parameters of the at least one unprocessed reference prototype, so that the reference color measurement data are obtained.
13. Method according to one of the preceding claims, characterized in that color measurement data includes hyperspectral data.
14. Method according to one of the preceding claims, characterized in that steps c) to f) are performed for each printing surface printed in the method.
15. Method according to one of the preceding claims, characterized in that the measurement of color parameters of the at least one unprocessed print proof is carried out in the digital printing system.
16. Method according to one of the preceding claims, characterized in that the measurement of color parameters of the at least one unprocessed printed proof is at least partially, but preferably completely, during the printing of at least part of the decoration to be printed in process step b).
17. Method according to one of the preceding claims, characterized in that the measurement of color parameters of the at least one unprocessed printed proof and the measurement of color parameters of the at least one unprocessed reference proof are carried out under first predetermined light conditions.
18. Method according to one of the preceding claims, characterized in that in step b) only a part of the decoration to be printed is printed on at least one printing surface, the method further comprising the following step: n) printing the complete decoration to be printed on the basis of the digital template onto a first plurality of printing surfaces with the printing settings of the digital printing system.
19. Device for carrying out a method according to one of the preceding claims comprising a digital printing system for printing at least a part of the decoration to be printed, at least one sensor for measuring the color measurement data and an electrical control system configured for carrying out a method according to one of the preceding claims.