Eastman-kodak Company

Nexpress Solutions, Inc.

Heidelberger Druckmaschinen Ag

Frank Pierel

Heiko Hunold

Jan Dirk Boness

Stefan Schrader

Ingo Klaus Dreher

Ralph Petersen

Karlheinz Walter Peter

Matthias Wecker

Patrick Metzler

Christopher B Liston

John R Thompson

Robert Michael Peffer

Donald Calvin Buch

Helmut Buck

Rolf Spilz

Soenke Schmidt

Carsten Huschle

Dirk Kahl

Dieter Karl-Heinz Dobberstein

J&uuml;rgen Sahlmann

Gerhard Rudolf Sing

Hans-G&uuml;nter Werner Staack

Tim D'Avis

Lutz Michael Wagner

G&uuml;nther Voss

Stephan Walter Pareigis

Michael Mordhorst

Ralf Jachmann

Joachim Heinrich Haupt

A method for detecting errors in individual color separation images of a multi-color printing machine, in particular an electrophotographic printing machine, comprising a plurality of printing units, is described. Using this method, first a plurality of first register lines is printed with a first printing unit, and a plurality of second register lines is printed with a second printing unit in such a manner that each of the first register lines, together with one of said second register lines, is positioned inside a respective registration frame. Then the plurality of the first and second register lines in the respective registration frame are detected with a register sensor, and an output signal of the register sensor relating to the respective second register line is compared with an intensity threshold value in order to determine whether the second register lines can be recognized. In an alternative embodiment of the method, a plurality of the first register lines is printed with a first printing unit in such a manner that each of the first register lines is printed within a respective registration frame. Subsequently, the plurality of the first register lines in the respective registration frames is detected with a register sensor, and an output signal of the register sensor relating to the respective first register lines is compared with a pre-specified intensity threshold value in order to determine whether the first register lines are recognizable.

Method for detecting errors in individual color separation images of a multi-color printing machine

A method for calibrating a printing machine having a plurality of printing units includes transporting a first group of at-least-semi-transparent sheets at least once through the printing units. A second group of at-least-semi-transparent sheets is transported at least twice through the printing units, with the sheets being turned over between passages. Registration marks are printed on one of the sheets of the first group of sheets, and on one of the sheets of the second group of sheets during their second passage through the printing units. No registration marks are printed on the sheets of the second group of sheets during their first passage through the printing units. The registration marks are measured at a registration sensor located downstream of the printing units. Calibration parameters are determined using the measurements of the first and second registration marks provided by the registration sensor.

Method for calibrating a printing machine using semi-transparent sheets

A method for calibrating a position of a first register line in a register mark for a multi-color printing machine, said first register line consisting of a first color that does not offer sufficient contrast with respect to a printing material to allow detection above a determined threshold on a register sensor. A plurality of register marks, each consisting of at least one starting line, a background line and a first register line, is printed, said background line consisting of a second color which offers sufficient contrast with respect to the first color for detection above the specified threshold on the register sensor if the first register line is printed on the background line, and said background line having a width that is greater than the first register line, and said starting line, said background line and said first register line being printed with the use of the pre-determined control parameters, which normally cause the first register line to be printed on the background line. Subsequently, it is detected whether the first register line has been recognized by the register sensor above the predetermined threshold as being completely positioned on the background line. If not, then at least one predetermined control parameter for printing the first register line is changed and printing of the register marks and the detection are repeated. Changing of the at least one control parameter may be repeated one or more times, with the first register line being shifted each time with respect to its width.

Method for calibrating a multi-color printing machine

In a method for automatically identifying a conveyor belt in a printer as being one of a plurality of belt types, the conveyor belt is moved along a circulatory path. A start and an end of a longitudinal marking on the moving conveyor belt are detected. A distance of travel of the moving conveyor belt between the detecting of the start and the end is sensed to provide a sensed marking length. The sensed marking length is allocated to a nearest of a plurality of nominal marking lengths. Each nominal marking length is associated with a respective one of said belt types. The belt type is associated with or defined by a set of one or more printer control parameters.

Method for automatically identifying a type of transparent conveyor belt

A method for the calibration or recalibration of a conversion factor (web encoder resolution), used to determine the distance covered by a print substrate in a printing machine, in particular an electrophotographically operating printing machine, by the cycles of a rotary input type of encoder (web encoder) which sends a signal to the driver of the conveyor belt, preferably the rotation of a rotating drive component for the conveyor belt. This task is solved in that the number of phase pulse signals of the rotary input type of encoder which accumulates during the movement over the dimensions of the longitudinal extension known or otherwise measured section of the conveyer belt, is determined and compared to the known dimensions of the longitudinal extension.

Method for calibrating or recalibrating a conversion factor for determining the distance covered by a print substrate in a printing machine

The position of sheets in a printing press is measured. A problem in transporting sheets through the printing press is how to guarantee the correct orientation and lay of the sheets, which must be guaranteed particularly in the printing operation. There is provided a device for precisely determining and correcting the positions of sheets in printing presses. Margin regions of a sheet are respectively imaged, projection data are transmitted to a computing unit, and the position of the sheet is calculated with the aid of the projection data by way of an image recognition algorithm. Furthermore, the computed positions of the sheet are compared to positions which are stored in the computing unit, and from the comparison, position deviations are computed, which are transmitted to the printing press and corrected by way of a sheet registration device.

Method and device for measuring a position of a passing sheet

The invention relates to a process and a device for alignment of sheet material ( ) which is conveyed in one conveyor plane ( ). The sheet material is conveyed on bodies ( ) of revolution and aligned by means of triggerable alignment elements ( ) in the conveyor direction ( ) and perpendicular to the conveyor direction ( ). The alignment elements ( ) are assigned to an alignment unit ( ). The alignment motion necessary for alignment of the sheet material in the conveyor direction ( ) and perpendicular thereto takes placed by separate alignment elements ( ) which can be triggered independently of one another during conveyance of the sheet material ( ) with the process speed.

Process and device for alignment of sheet material during transport

A method and apparatus for setting register on a multicolor printing machine ( ) having color printing units ( ) allocated to various printing inks and having image cylinders ( ), equipment ( ) for producing images, in particular electrostatic latent images, on the image cylinders ( ), a carrier ( ) for printing substrates ( ) and image transfer points ( ) for the transfer of the color separations ( ) from the color printing units ( ) to the printing substrates ( ), an allocation of the image productions ( ) on the image cylinders ( ) to the printing substrates ( ) being carried out in order to achieve coincidence of register of the color separations ( ) in the print. This is achieved by a time-independent allocation of the positions of the image productions ( ) on the image cylinders ( ) to the printing substrates ( ) being carried out for at least one defined area ( ) of all the color separations ( ).

Method and apparatus for setting register on a multicolor printing machine by time independent allocation of positions of image productions to printing substrates

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Gettorf, Germany

Frank Pierel