Abstract: A method for compensating for disruption torques in driving a jetting cylinder in an inkjet printing machine includes recording print image products for at least one color and at least one complete rotation of the jetting cylinder by using an image sensor and using a computer for a time parallel measurement of a driving torque of the jetting cylinder, generating an average gray value profile above a circumferential coordinate based on the recorded image data by using the computer, transforming the average gray value profile and the measured profile of the driving torque into a frequency range by using a computer-assisted Fourier transform and extracting order components from the frequency range. A periodic compensation torque is calculated based on the extracted order components, and the calculated periodic compensation torque is factored-in when actuating the jetting cylinder of the inkjet printing machine in the course of a printing operation.

Abstract: A method for the automated calibration of a printing machine with an image capture system by using a computer, includes putting at least one printed sample substrate with defined deviations into the printing machine, generating a digital image of the printed sample substrate by using the image capture system, calculating current compensation values including defined deviations for configuration parameters of the printing machine relating to optimizing the printing quality by using the computer, and comparing the current compensation values created with target compensation values known from the defined deviations of the printed sample substrate. Serviceability of the printing machine is checked by evaluating the comparison by the computer and/or calibrating the printing machine by using the evaluated comparison by the computer.

Abstract: A method for detecting and compensating defective printing nozzles in an inkjet printing machine includes periodically printing at least one printing nozzle test chart having horizontal rows of equidistant vertical lines underneath one another, with only nozzles contributing to the test chart in every row corresponding to horizontal rows, and printing an area coverage element geometrically associated with the test chart. Both elements are recorded by an image sensor and evaluated by a computer. The computer identifies print defects by evaluating the area coverage element and allocates the defects to defective nozzles. The computer evaluates the test chart based on thresholds to detect defective nozzles and compensate detected defective nozzles. The computer compares the detected defective nozzles from the area coverage element and the test chart to identify detected defective nozzles causing defects in only one element and calculates the thresholds based thereon to minimize the detected defective nozzles.

Abstract: A method corrects color density unevenness during a printing operation on an inkjet printing machine having printing nozzles and a computer. The computer modifies the number or size of the drops to be applied to a printing substrate to attain nominal color density values after the processing of a rasterized print image. For different actual tone values, it is determined which target tone value is required to attain a nominal coloration by measuring a test image for every printing nozzle using a color measurement device, and, based thereon, an area coverage-dependent compensation profile is determined and saved on the computer to be applied in the printing operation to calculate the number and size of the drops on the computer.

Abstract: A method for carrying out a printing operation on an inkjet printing machine compensates for failed printing nozzles by using a computer. After a screening process in which a halftone image is created for an image to be printed, failed printing nozzles are compensated for by increased ink application from neighboring printing nozzles by precalculating at least one corrective halftone image for the adjacent printing nozzles by using the computer, replacing the halftone image created in the screening process by the corrective halftone image in the at least one column of the neighboring printing nozzles, and carrying out the printing operation on the inkjet printing machine using the corrected halftone.

Abstract: A method for compensating for printing substrate deformation in a multicolor duplex printing operation by way of a computer. The substrate deformation that arises when individual color separations are printed onto the first and second sides of the printing substrate in the printing units is established and compensated for in the course of an automated register correction process. The computer calculates a forecast of the substrate deformation on a basis of the established first side deformation parameters of the printing substrate. When further color separations are printed onto the second side the forecast is used as an input parameter for a compensation of the substrate deformation of the second side.

Abstract: Curable compositions are based on ethoxylated triacrylates and alkylglycidyletheracrylates which can be employed to obtain printing products with a soft touch coating. The curable compositions are processed in conventional printing machines where sheets of glossy and matt paper have the curable compositions applied thereto with an anilox roller and then the paper is dried by UV lamps.

Abstract: A method calibrates image sensors and adjusts print heads in an inkjet printing machine via a computer. The method includes printing a test print chart, recording the printed test print chart via an image sensor to create a digital image, determining a coordinate transformation between the coordinates on the test print chart and the coordinates of the image sensor and the print heads, implementing a computer-assisted evaluation process of the digital image to determine the coordinates on the test print chart, deriving correction values for print head adjustment and camera calibration from results of the coordinate transformation and/or the comparison thereof with the determined measured values, and implementing the print head adjustment and the camera calibration by the computer. The test print chart has filled circular discs. The filled circular discs have a minimum diameter that is selected for them to function even if defective printing nozzles occur.

Abstract: A method for printing a print control strip onto a sheet of printing material. The print control strip is divided into strip sections and the strip sections are printed into gripper gaps at the leading sheet edge and/or the trailing sheet edge of the sheet. In a variant embodiment, there is also printed a print control strip onto two sheets of printing material. The print control strip is divided into at least two portions of respective strip sections and the strip sections of a first portion and of a second portion are printed into respective gripper gaps at at least one sheet edge of a first sheet and of a second sheet, respectively. Waste production is eliminated or at least reduced and costs are thus lowered.

Abstract: A method for producing a printed product includes coating a preferably paper or cardboard substrate with a precoat or supplying a substrate that has been coated with a precoat, in which the precoat contains at least one acid, applying a water-based ink to image areas on the coated substrate by using at least one ink print head, and drying the printed substrate and/or the ink, preferably using IR radiation and/or heated air. The precoat includes a photobase generator or a photobase generator is applied at least locally to non-image areas on the substrate, the substrate is irradiated at least locally in non-image areas, preferably using UV radiation, to locally generate a base, and the printed substrate is varnished with a water-based varnish.

Abstract: A method for compensating substrate shrinkage during printing on a printing machine includes generating multiple image parts of a digitally available image to be produced, factoring in information on substrate shrinkage by subdividing the image using a computer, subdividing generated image parts into data blocks using the computer, saving actual positions of blocks in the digital image using the computer, calculating target positions of all blocks in the digital image using the computer by shifting the blocks away from one another by one pixel creating single-pixel-wide gaps between blocks in the digital image, copying and rearranging blocks in the digital image according to calculated target positions using the computer, calculating positions of single-pixel-wide gaps using the computer, filling gaps with digital image data of neighboring pixels using the computer to create a compensated digital image. The compensated digital image is printed on the printing machine.

Abstract: A method corrects for defective printing nozzles in an ink jet printing machine via a computer. The defective printing nozzles are compensated for after the screening process by neighboring printing nozzles applying an increased amount of ink. The method includes precalculating different compensation halftones for different area coverages by the computer, printing the compensation halftones embedded in area coverage halftone areas, evaluating the printed compensation halftones via the computer, and selecting and saving, for every area coverage level, the compensation halftone that best matches the coloration of the original halftone in the respective area coverage halftone area. A defective printing nozzle is detected during production printing by the computer. The local area coverage is determined along the detected defective printing nozzle by the computer.

Abstract: A digital printing machine includes a first sheet-conveying belt made of a first material, a second sheet-conveying belt made of a second material, and a print head for printing on a front side and a back side of the print sheet. The print head is directed towards the first sheet-conveying belt. A reversing device reverses the print sheet between receiving a print on the front side and receiving a print on the back side. A drier dries a print that has been printed onto the print sheet by the print head. The drier is directed towards the second sheet-conveying belt. For instance, the first sheet-conveying belt may be a metal belt and the second sheet-conveying belt may be a plastic belt.

Abstract: A rotary die-cutter for cutting a piece of material or scrap out of a printing material such as paper, includes a die-cutting cylinder and an associated impression cylinder. The die-cutting cylinder is connected to a vacuum source. A die-cutting tool which is disposed on the die-cutting cylinder includes at least one die-cutting knife having a closed form and a suction opening within the closed form. A cylinder cover is disposed on the impression cylinder. At least one raised or recessed first guide element is disposed within the closed form for guiding suction air and/or at least one recessed or raised second guide element is disposed in the cylinder cover for guiding air. The scrap to be removed from the printing material can therefore be transported with the die-cutting cylinder and ejected from the die-cutting tool or knife in a trouble-free way.

Abstract: A method for preserving the black composition of at least one object positioned to overprint a special color in a print image for preprint color management of a printing operation using a computer, includes transforming the special color and the object into a combination of process colors of the printing operation during the color management process and then using this combination of process colors to generate the print image in a printing machine. The color transformation into the process colors of the printing operation is achieved in two stages. In a first stage, the color transformation into the process colors is carried out while keeping the special colors, then checking if the object is overprinted onto the special color, then removing the black proportion of the object and then in a second stage, transforming the special color into the process colors and subsequently maximizing the black proportion of the object.

Abstract: A method for the automated generation of reference color values for color control purposes in a printing machine by using a computer includes, within a process of setting up the printing machine for a print job, initially carrying out printing operations and using a spectrophotometer to determine coloration values for every process color used in the print job. For every process color that is used in the print job, the computer automatically selects that coloration value of a process color that has the smallest deviation from a color set point that has been established at the beginning of the job and saves this coloration value as a new reference value for this process color.

Abstract: In a method for operating an inkjet printing machine, a condition of an ink is determined. A sedimentation and/or agglomeration of a pigmented ink is determined by refractometry, i.e. the value of the refractive index of the ink is measured with a refractometer and compared with a stored value with computer assistance.

Abstract: A method for detecting and compensating for defective printing nozzles in an inkjet printing machine by using a computer, includes shrinking the height of a digitally available image to the image height of a print control strip by using the computer while the image width remains uninfluenced, printing the shrunk digital image onto a printing substrate, recording the printed shrunk digital image by using at least one image sensor, comparing the recorded image with the shrunk digital image by using the computer, detecting defective printing nozzles for the digital image by using the computer based on the comparison and compensating for the detected defective printing nozzles. The digital image is printed onto the following printing substrate by using defective printing nozzle compensation.

Abstract: A method for improving the print quality of graphic elements, in particular vectorized letter graphics, in PDF documents in the prepress stage of a printing process by using a computer, includes analyzing the page content of the PDF document by using the computer and saving the page content in a suitable data structure, searching the data structure for graphic elements, in particular letter graphics, that fulfill specific predefined criteria relating to an evaluation of the height and width of the graphic paths of graphic elements that are present in the PDF document, by using the computer, converting the selected graphic elements into image masks by rendering the selected graphic elements on the computer and substituting the generated image masks for the originally selected graphic elements in the PDF document by using the computer. The PDF document with the generated image masks are printed on a printing machine.

Abstract: A method for printing on an inkjet printing machine including color space transformation between target and process color spaces using a computer, includes calibrating the machine by printing and colorimetrically measuring a process color space test chart for printing in the target color space including printing-operation-related limitations in the applied ink amount. The generated measured values correspond to sampling points in the measured target color space. The sampling points are interpolated to define further sampling points. The color space transformation uses sampling points in the target color space and input values from the chart in the process color space corresponding to sampling points in the target color space. The physical variable of ink drop volume is directly used for ink application limitations and input values in the process color space. The calibration of the machine is adapted and the printing operation is carried out.