Heidelberger Druckmaschinen Ag

Jens Forche

Andreas Henn

Steffen Neeb

Nicklas Raymond Norrick

Hans-Peter Hiltwein

Andreas Fehlner

Thomas Wolf

Willi Becker

Karl-Heinz Helmstädter

Christian Hieb

Dieter Stephan

Volker Weyde

A device for controlling the printing operation in an inkjet printing machine includes at least one inkjet print head disposed at an adjustable distance from a substrate to be printed on. A device receives a print job and a bad sheet sensor has a trigger threshold. A machine control unit adjusts the distance between the inkjet print head and the substrate to be printed on as well as the trigger threshold of the bad sheet sensor before or after the printing operation as a function of a received print job.

Device for controlling an inkjet printing machine to provide a variable distance between an inkjet print head and a substrate

A method for detecting and compensating for defective print heads in an inkjet printing machine uses a computer to analyze printing nozzle test charts and/or area coverage elements to obtain characteristic values of individual printing nozzles in a print head, to calculate the failure probabilities of these printing nozzles on the basis of thresholds, and to compensate for a printing nozzle that exceeds a specified failure probability. The computer uses the individual failure probabilities of the individual printing nozzles in a print head to calculate the failure probability of the print head and initiates compensation measures as a function of the calculation. The thresholds correspond to a multi-dimensional characteristic value threshold based on which the computer calculates the failure probability of a printing nozzle by using an algorithm including kernel density estimation through a multidimensional distribution function.

Method for detecting and compensating for defective print heads in an inkjet printing machine by stochastic print head monitoring

A method detects defective print nozzles in an inkjet printing machine by a computer. In a first phase within the context of a print job, print nozzle test patterns are printed beside a subject on a printing substrate. These print nozzle test patterns are then digitized by an image sensor and sent to the computer, where they are analyzed by the computer to determine the current state of the print nozzles, including defective print nozzles. After the first phase, the print nozzle test patterns are modified by the computer on the basis of the current state of the print nozzles and, in a second phase, the modified print nozzle test patterns are printed, digitized and evaluated by the computer with regard to the determination of the current state of the print nozzles and defective print nozzles.

Method for detecting a defective print nozzle using a variable print nozzle test pattern

A method for detecting and compensating for defective printing nozzles in an ink jet printing machine by using a computer includes printing printing nozzle test charts next to an actual print in a production run, subsequently recording and digitizing the printed printing nozzle test charts by using at least one image sensor, evaluating recorded test charts and, based thereon, defining characteristic values for all printing nozzles contributing to the printed printing nozzle test charts by using the computer, calculating a failure probability for every contributing printing nozzle based on the determined characteristic values by applying a statistical prediction model using the computer, and switching off and compensating for all printing nozzles exceeding a first defined threshold for the calculated failure probability. A printing operation is then carried out on the ink jet printing machine with printing nozzle compensation.

Method for detecting and compensating for defective printing nozzles in an ink jet printing machine

An apparatus for feeding sheets to a sheet processing machine smoothes out and fixes a sheet through the use of a suction groove disposed transversely relative to a sheet transport direction, before the sheet is gripped by an onward transport device. A sheet-fed rotary printing press having the apparatus is also provided.

Method for feeding sheets to a sheet processing machine

In a sheet gripper, a dimensionally stable base material and an elastic clamping surface material are connected to each other in a form-fitting manner. The elastic clamping surface material functions as a clamping surface of the sheet gripper. This forms a sheet gripper having a long service life and is easy manufacture.

Printing material sheet gripper and method for producing the sheet gripper

A gripper system for a machine that processes printing material sheets has a gripper with a first clamping surface and a gripper pad, for cooperating with the gripper, with a second clamping surface. One of the two clamping surfaces is formed with a surface relief. The clamping surface which has the surface relief is placed in such a way that, when a narrow printing material sheet is gripped, the clamping surface is covered by the sheet only within a subregion of the clamping surface and, when it grips a broad printing material sheet, it is covered by the latter beyond the subregion. The surface relief is structured differently within the subregion than outside the subregion, in that it is provided within the subregion with an antideformation structure which protects the narrow printing material sheet from excessive clamping deformation.

Gripper system for a machine which processes printing material sheets

In a gripper system having grippers disposed in a row and interspaces between the grippers and hold-downs for holding down in each case a free edge of a printing material sheet gripped by the grippers, the hold-downs being disposed to project into the interspaces and being mounted such that they can be displaced together with the grippers when gripping the printing material sheet.

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Mannheim, Germany

Jens Forche