Heidelberger Druckmaschinen Ag

Novartis Ag

X-rite Switzerland Gmbh

Gretag-macbeth Ag

Wolfgang Geissler

Werner Huber

Harald Bucher

Bernd Kistler

Helmut Kipphan

Peter Ehbets

Frank Schumann

Gerhard Fischer

Frank Muth

Christopher Riegel

Manfred Schneider

Clemens Rensch

Gerhard Loeffler

Anton Rodi

Martin Mayer

Adrian Kohlbrenner

Robert Lange

Loris De Vries

Peter Hagmann

Hans Koehler

Jan Krieger

Peter Elter

Roland Hauck

Hans-Peter Grossmann

Rudolf-Karl Uhrig

Hubert Lutz

Peter H&ouml;fer

Guenther Uhlig

Peter Dr Ehbets

Adrian DrKohlbrenner

A method for detecting printing nozzle errors in an inkjet printing machine provides a high degree of robustness in the detection of errors by printing a nozzle test pattern in the inkjet printing machine. The test pattern is then digitalized by using a camera and transmitted to a computer for evaluation. There, the recorded test pattern is investigated by using methods of digital image processing, such as a Fourier analysis, and evaluated in the frequency range with regard to specific anticipated printing nozzle errors. Specific printing nozzle errors can be detected especially on the basis of amplitude, phase and variance errors in the signal in the frequency range. Moreover, by using the phase error, it is possible to evaluate whether the two print heads are disposed in an incorrect adjustment position relative to one another by calculating displacements of the phase error in transition regions of two print heads.

Method for detecting printing nozzle errors in an inkjet printing machine

A method for detecting and compensating for failed printing nozzles in an inkjet printing machine by using a computer, includes printing a current print image, recording the printed print image by using an image sensor and digitizing the recorded print image by using the computer, adding digitized color values of the recorded print image of every column over the entire print image height and dividing the added-up color values by the number of pixels to obtain a column profile, subtracting an optimized column profile without failed printing nozzles from the original column profile to obtain a differential column profile, setting a maximum value threshold defining a failed printing nozzle when exceeded, applying that maximum value threshold to the differential column profile to obtain a resultant column profile every maximum of which marks a failed printing nozzle. The marked printing nozzles are compensated in a subsequent printing operation.

Method for detecting and compensating for failed printing nozzles in an inkjet printing machine

A color measurement on printed materials produced by a printing press is performed by at least a first color measuring device installed in the printing press and at least a second color measuring device. A signal is output by the first color measuring device in the printing press when the measured color values registered on the printing materials are located within a predefined tolerance limit for a predefined period and that, after the signal has been output, a color measurement on one of the printed materials thus produced is performed with the second color measuring device.

Method for color measurement in printing presses

An apparatus in a machine for processing printing material has a register sensor for register measurement between at least two color separations of a printed image printed above one another on a printing material. The register sensor registers optically deviations between the two color separations and forwards the deviations onto a computer. The register sensor contains at least one photodiode having at least two quadrants. The largely rectangular evaluation areas of the photodiode are aligned obliquely in relation to the edges of the conveyed printing material. A register mark to be detected by the register sensor has a plurality of wedge-shaped colored areas pointing in a peripheral direction of the printing material, one of the wedge-shaped colored areas being a reference color used as a reference variable and others of the wedge-shaped colored areas being register colors to be controlled. An alternative register mark has a first field for length calibration; a second field having a wedge of a reference color selected as a reference variable; and a third field containing a register color to be controlled. The may also be provided a measuring field formed as a point-symmetrical field exhibiting a color of a color separation as a full tone.

Register mark to be detected by a register sensor

A method for the correction of measurement errors caused by surface effects induced by ink splitting during the color measurement of a printed sheet on a running printing device, includes scanning the printed sheet photoelectrically point by point and forming color and/or density measured values from scanning signals from the scanned points. Those scanned points which have a brightness exceeding a limiting value are identified, and the measured values are corrected by using the identified scanned points. In particular, during the formation of the color and/or density measured values, the scanning signals from the identified scanned points are not taken into account.

Ink splitting correction method

An apparatus in a machine for processing printing material has a register sensor for register measurement between at least two color separations of a printed image printed above one another on a printing material. The register sensor registers optically deviations between two color separations lying one above the other on the printing material and forwards the deviations onto a computer. The apparatus includes register marks to be measured by the apparatus. The apparatus is distinguished in that the register sensor contains at least one photodiode having at least two quadrants, and in that the largely rectangular evaluation areas of the photodiode are aligned obliquely in relation to the edges of the conveyed printing material.

Register sensor

In a method for determining color and/or density values for use in monitoring and regulating a printing process in a printing apparatus, specifically in a sheet-fed offset printing press, measuring areas of a printed sheet are measured photoelectrically during the printing process, directly in or on the running printing apparatus. From the measured values obtained in the process, the color and/or density values for the relevant measuring areas are formed. From the measurement, measured value deviations caused directly in the printing process with respect to a measurement outside the printing process can be corrected computationally.

Method for determining color and/or density values and printing apparatus configured for the method

Spectral, densitometric, or color measured values are detected on sheet printing materials during the printing process in a sheet-fed printing press. The measured values are determined on sheets as they are moving through the printing press and the measured values are used in real-time by a computer to control parameters for controlling the printing process in the sheet-fed printing press.

Inline measurement and closed loop control method in printing machines

A printing press for processing sheet printing materials includes at least one printing unit, a computer and a measuring device for monitoring printing quality during a printing process. The measuring device has a sensing device for measuring by color or spectrally to register the printing material. At least one sheet-guiding element leads the sheet printing material past the sensing device. A measuring device for monitoring printing quality during a printing process in a printing press for processing sheet printing materials, is also provided.

Printing press and device for the inline monitoring of printing quality in sheet-fed offset printing presses

An apparatus and a method for exchanging information about tonal values and calorimetric values between a prepress stage, a printing stage and a quality control stage are provided. The apparatus and the method create characteristic curves which are used to optimize a process calibration and a color calibration.

Apparatus and method for creating color-calibration characteristic curves and/or process-calibration characteristic curves

A device for inspecting a printed image of a product of a printing press, comprising an image detecting device that furnishes actual image data of the product, and a comparison circuit comparing the actual image data with master image data from a defect-free master image, dividing means for performing a preselectable division of the printed image into inspection areas, and wherein if a defect is detected by the comparison circuit the associated inspection area is designated as being defective.

Device for image inspection

A method for image inspection and color guidance for printing products of a printing press, in which in on-line operation, actual image data of the printed images of the printed products are obtained and compared with nominal image data for the purpose of locating image defects, which comprises the steps of checking, upon the appearance of a defect, before any change in the ink feed is made, as to whether on the basis of the type of defect, some other cause than the color guidance for the deviation is possible.

Method for image inspection and color guidance for printing products of a printing press

A process and an apparatus for the examination, especially the quality control, of optical components, in which an image of the particular component to be examined is produced and flaws in the imaged article are detected by image analysis, as well as the integration of that examining process into the manufacture of the component. The optical components may be optical components for the eye, such as spectacle lenses, contact lenses, intraocular lenses and the like.

Process and apparatus for examining optical components, especially optical components for the eye and device for illuminating clear-transparent

A process for controlling coloration in multicolor printing, wherein a photoelectric measuring arrangement (,) is used to obtain actual color measurement values from the printed image (,), wherein the actual color measurement values are compared with specified setpoint color measurement values, and wherein the comparison signals are supplied to a color controlling device (,), with the layer thickness of the ink to be applied to a material to be printed (,) being controllable by means of color controlling elements (,), monitoring signals are continuously derived at selected measuring locations (,), whereby the number of the measuring locations (,) is increased if the monitoring signals exceed a specified threshold value and the actual color measurement values obtained at the increased number (N,) of measuring locations (,) are processed into comparison signal. The invention can be used in multicolor printing machines.

Process for controlling coloration in multicolor printing

A method for regulating inking of a printing press. The method includes a first step of providing a picture taking device, a closed-loop control device, and a printed product having a surface with a printed image. A second step of printing a print control strip on the surface next to the printed image. A third step of deriving first picture signals from the print control strip and deriving second picture signals from the printed image with the picture taking device. A fourth step of using the closed-loop control device for deriving actual values representing inking of the print control strip from the first picture signals and comparing the actual values to desired values for deriving resultant comparison values. A fifth step of determining ink adjusting signals for controlling ink distribution devices from the resultant comparison values for varying inking of the print product until a desired value is reached during a printer tuning phase. A sixth step of generating an OK signal when the desired value is reached. A seventh step of using the closed-loop control device for deriving further actual values representing inking of the printed image from the second picture signals and comparing the further actual values to further desired values for creating further resultant comparison values. Lastly, one determines further ink adjusting signals for controlling the ink distribution devices from the further resultant comparison values for varying inking of the printed product.

Growing community of inventors

Bad Schönborn, Germany

Wolfgang Geissler