Eastman-Kodak Company

Nexpress Solutions, Inc.

Heiko Hunold

Stefan Schrader

Jan Dirk Boness

Patrick Metzler

Karlheinz Walter Peter

Ingo Klaus Dreher

Frank Pierel

Ingo Klaus Michael Dreher

Christopher B Liston

Ralph Petersen

Matthias Wecker

John R Thompson

Robert Michael Peffer

Donald Calvin Buch

Wolfgang Eberhard Luxem

Rolf Spilz

Thomas Jacobsen

Volker Otto

Dieter Karl-Heinz Dobberstein

Walter Dworschak

Stefan Theden

G&uuml;nther Voss

Michael Mordhorst

Stephan Walter Pareigis

Ralf Jachmann

Michael Kowalczyk

Christian Friedrich Engeln

Tim D'Avis

Stefan Schlünss

Rolf Johannes Spilz

Franck Pierel

Jan Boness

V Jörg Leyser

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

A method of preventing a registration error while printing at least one printing image, wherein, in order to control or adjust the correct length of the printing image, the start and/or the distance of the printing image lines of the printing image are controlled by determining the ratio of the number of rotary encoder signals of a transport web counted during a specific time interval to the number of rotary encoder signals of a cylinder of a printing and by taking into account a change of this ratio as a correction, said ratio being a function of a printing sheet located in a printing nip between the transport web and the printing unit, is characterized in that a changed printing material situation occurring in said printing nip between the transport web and the printing unit is used to achieve registration accuracy immediately.

Method of preventing a registration error while printing

The invention relates to a method and a device for controlling the circumferential register in a digital multi-color printing machine for printing sheets during a printing process, whereby, for each sheet, at least one register mark per color printing unit of the multi-color printing machine is produced, assigned to said sheet and defined with respect to its position, and whereby, based on the determination of the position of the register marks of a sheet, the circumferential register of at least one sheet, which follows the sheet associated with said determined register marks downstream of the printing process, is controlled. In duplex printing a sheet by recto and verso printing with the invention, register marks are applied for each side and, in order to control recto and verso printing of at least one subsequent sheet, said register marks are analyzed.

Method and apparatus for controlling the registration of sheets

A device and a method using a printing device and system for printing sheets whereby, for each sheet, at least one register mark per color printing unit of the multi-color printing machine is produced, assigned to said sheet and defined with respect to its position, so that in duplex printing register marks are applied to each side. The position of each mark is determined by analyzing the position of the mark assigned to the appropriate previous recto or verso sheet.

Method and device for controlling registration

A method and control device for determining a register error, whereby at least one register mark is printed and at least one sensor records the register mark, whereby the sheet edge of the sheet is recorded by the sensor, and the register error is determined from the sensor data and the target data.

Method and control device for determining a register error

A method for correction of the calibration of the register mark accurately and/or register accurate printing process of an electrophotographic printing unit, preferably of a color-printing unit. Large surface toner fields are placed on a conveyor belt for the substrate to be printed, particularly in the larger spaces between the substrate sheets to be printed. The influence of a toner field placed on a conveyor belt for print substrate sheets on the register mark and/or registration of the printing process is identified, and such influence is expressed in the form of at least one correction value or parameter suitable for the correction of the calibration.

Method for correction of the calibration of a register mark accurate printing process

Ensuring proper compass and register positioning during printing. Marks are imprinted on a carrying element and at least one sensor is present to detect the marks on the carrying element and a second sensor detects a seam on the carrying element. A control mechanism receives mark values from the first sensor and seam values from the second sensor, and discarding mark values when the seam is detected.

Process and control mechanism for avoiding register errors

Controlling the position accuracy in color printing with an electrophotographic printing device in regard to the register, namely the position accuracy of a printed image on the print substrate, in particular on the printed sheet regarding an edge of the printed sheet and in regard to the gage-pin, namely the position accuracy of the color printouts of the color print in relation to each other. Register and gage-pin position accuracy are executed with one and the same sensor unit, having one light receiver (sensor), which receives light from at least one light emitter. In this way, both of the position accuracy can be checked economically while saving space and in extreme cases, be corrected, preferably using a control fitting.

Technique and device for controlling the position accuracy in color printing

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

Determining and correcting registration errors, which are caused by the rotational speed of a print cylinder changing because of a sheet passing between the print cylinder and a sheet transport conveyor belt. At least one first registration mark is applied onto the conveyor belt prior to a sheet being transported thereby, and at least one second registration mark is applied onto the conveyor belt after the transported sheet. By the detection of the first registration mark and the second registration mark, a calculation of a timing number between the detection of the first registration mark and the second registration mark can be made. The calculated timing number is compared to a target value to determine any error due to change in angular velocity of the print cylinder due to engagement with the sheet.

Process and device for determining registration errors

A process and printing machine for determining registration errors and correcting therefore. At least one first registration mark is applied onto a conveyor belt for transporting a sheet, and at least one second registration mark is applied onto the sheet adjacent to the first registration mark. The first registration mark and the second registration mark are detected, the distance between the first registration mark and the second registration mark is calculated, and the difference between the calculated distance and a distance without different speeds of the conveyor belt and the sheet (a target value) is calculated.

Process and printing machine for determining registration errors

A method and apparatus for setting register on a multicolor printing machine ( ) having color printing units ( ) assigned to various printing inks, at least one image cylinder ( ), image production equipment ( ) for producing color separations ( ) on the at least one image cylinder ( ) and a carrier ( ) for printing substrates ( ). An assignment of the image production points ( ) on the at least one image cylinder ( ) is carried out in order to achieve coincidence of register between the color separations ( ) in the print, by both the production of the image starts ( ) and the production of areas ( ) of the color separations ( ) set on the basis of the print and the evaluation of register marks ( ).

Method and apparatus for setting register on a multicolor printing machine

Correcting register faults in a multicolor printing machine having a number of items of equipment for the digital production of color separations, wherein correction values are determined and assigned to angular positions of at least one image cylinder and, as a result, taken into account for the control of the production of the color separations on the image cylinder. Correction values are to be made available for the correction of register faults, which, with a fine graduation, make it possible to assign them to angular positions of machine elements in a repeatable way. This is achieved by determining circularity errors of machine elements which have an influence on the register, assigned to their angular positions and, from these, the correction values for the control of the production of the color separations on the at least one image cylinder being determined.

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Wattenbeck, Germany

Heiko Hunold