EP1310088A1 - Procede pour la gravure de cylindres d'impression - Google Patents

Procede pour la gravure de cylindres d'impression

Info

Publication number
EP1310088A1
EP1310088A1 EP00982988A EP00982988A EP1310088A1 EP 1310088 A1 EP1310088 A1 EP 1310088A1 EP 00982988 A EP00982988 A EP 00982988A EP 00982988 A EP00982988 A EP 00982988A EP 1310088 A1 EP1310088 A1 EP 1310088A1
Authority
EP
European Patent Office
Prior art keywords
engraving
densities
values
corrected
strand
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00982988A
Other languages
German (de)
English (en)
Inventor
Ernst-Rudolf-Gottfried Weidlich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hell Gravure Systems GmbH and Co KG
Original Assignee
Hell Gravure Systems GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hell Gravure Systems GmbH and Co KG filed Critical Hell Gravure Systems GmbH and Co KG
Publication of EP1310088A1 publication Critical patent/EP1310088A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4076—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on references outside the picture
    • H04N1/4078—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on references outside the picture using gradational references, e.g. grey-scale test pattern analysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/02—Engraving; Heads therefor
    • B41C1/04—Engraving; Heads therefor using heads controlled by an electric information signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4076—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on references outside the picture

Definitions

  • the invention relates to the field of electronic reproduction technology and relates to a method for engraving printing cylinders in an electronic engraving machine, in which at least two engraving strands lying next to one another in the axial direction are each engraved with one engraving member on a printing cylinder.
  • an electronic engraving machine for engraving printing cylinders by means of an engraving member is already known.
  • the engraving element with an engraving stylus controlled by an engraving control signal as a cutting tool moves in the axial direction along a rotating printing cylinder.
  • the engraving stylus cuts a series of cups arranged in a printing grid into the outer surface of the printing cylinder.
  • the engraving control signal is formed in an engraving amplifier by superimposing a periodic raster signal, also called vibration, with image signal values which represent the print densities to be reproduced between "light" and "depth". While the raster signal causes an oscillating stroke movement of the engraving stylus to engrave the cells arranged in the printing raster, the image signal values determine the depths of cut of the engraved cells in accordance with the tonal values to be reproduced.
  • a large number of axially adjacent, strip-shaped cylinder areas, called engraving strands often have to be engraved on a printing cylinder or on the printing cylinders of a color set, which are engraved in succession in an engraving machine or simultaneously in several engraving machines, with one engraving element each , For example, the different print pages of a print job are produced in the individual engraving strands.
  • the engraving control signals for the individual engraving organs are generated in separate electronic units, called engraving channels.
  • a prerequisite for good reproduction quality is that the engraved print densities in the individual engraving strands match, ie that a called strand equality is achieved.
  • the engraving styluses Even if the individual engraving channels are electrically balanced, the engraving styluses often have a different degree of wear. The result is that wells with different geometrical dimensions or volumes are engraved in the individual engraving strands, as a result of which disruptive differences in printing density occur in the engraving strands. Worn engraving styluses also produce cells with a rougher inner surface, which changes the ink acceptance behavior in the printing press and thus the printing density.
  • Different printing densities in the engraving lines can also be attributed to influences in the printing machine, e.g. if the contact pressure between the printing cylinder and the impression cylinder varies in the axial direction or if the doctor blade with which the excess printing ink is wiped does not lie equally close to the printing cylinder.
  • the differences in printing density in the engraving strands can occur with respect to a printing density value or with respect to a printing density range and can be of different sizes for each engraving strand.
  • the engraving properties on the circumference of the printing cylinder can change, so that differences in printing density can also occur within an engraving strand.
  • the engraved printing cylinder is in practice chemically post-treated in a time-consuming and labor-intensive work process, particularly when the quality of the printed products printed with the cylinder is high.
  • the invention is therefore based on the object of improving a method for engraving printing cylinders in an electronic engraving machine, in which at least two engraving strands lying next to one another in the axial direction, each with an associated engraving member, are engraved on a printing cylinder in such a way that disturbing differences in printing density in the engraving strands automatically be compensated.
  • FIG. 1 shows the relationship between signal value and pressure density for three characteristic target density values
  • FIG. 2 shows the relationship between the target pressure densities and the corresponding transverse diagonals (standard calibration function) corresponding to them
  • FIG. 3 shows the residual deviations of the actual pressure densities for three characteristic
  • FIG. 4 the residual deviations between actual printing densities and target printing densities in an engraving strand
  • FIG. 6 the corrected calibration function for an engraving strand
  • FIG. 7 the correction of the signal values
  • FIG. 8 shows the assignment between signal values and corrected signal values
  • FIG. 9 shows the change in the geometric values over time.
  • target printing densities D so n are used for characteristic tonal values of a test wedge to be engraved specified in each engraving strand of a printing cylinder.
  • a test wedge with the specified signal values S is engraved in a engraving cylinder in each engraving strand.
  • the test wedges can be engraved on the printing cylinder separately or simultaneously with the engraving of the actual printing form in cylinder areas lying outside the printing form.
  • Areas of production engraving can also be used for calibration if they contain the characteristic tonal values.
  • the engraved impression cylinder is printed on in a printing machine.
  • the actual pressure densities Dj S t of the test wedges engraved in the individual engraving strands are measured with a suitable density measuring device and the deviations from the target pressure densities D so n are determined (FIG. 1).
  • These deviations are compensated for by a suitable calibration of the transfer function of the engraving systems in the individual engraving lines, for example by setting the signal amplification and the starting point of the amplification of the engraving systems.
  • the actual pressure densities Dj St are derived from the measurement of geometric values of the engraved test wedge cells.
  • the specified nominal pressure densities D so n correspond to nominal geometry values which define the desired shape and size of the cells to be engraved.
  • Geometric values can be the longitudinal diagonals, the transverse diagonals, the areas or the volumes of the wells, depending on which measuring method is used to measure the engraved well sizes.
  • the transverse diagonals of the cells are preferably used, since they are easy to measure. Fig.
  • the target print densities D so n are converted into the corresponding signal values for controlling the engraving amplifiers assigned to the individual engraving strands, in which the engraving control signals for controlling the engraving stylus of the engraving members are generated.
  • the actual geometry values of the wells are measured in each engraved test wedge of an engraving strand. The measurement of the geometry values can take place with the aid of a measuring microscope or in a video image recorded by a video camera.
  • the engraving systems of the individual engraving strands are set in such a way that the actual geometry values reach the target geometry values which correspond to the predetermined target printing densities.
  • correction values are derived from the residual deviations for the individual engraving strands, which are included in the calibration of the next engraving of a printing cylinder with the same engraving system in the respective engraving strand, so that the calibration takes into account the strand-specific influences and differences, and thus the Desired print densities in all engraving lines can be achieved more reliably and more precisely.
  • the method is explained below using the example of engraving strand No. 1.
  • FIG. 4 shows the target pressure densities D so n and the actual pressure densities D, s t achieved in this engraving line according to the standard calibration as a function of the transverse diagonal Q.
  • FIG. 4 shows the target pressure densities D so n and the actual pressure densities D, s t achieved in this engraving line according to the standard calibration as a function of the transverse diagonal Q.
  • the dashed curve of the actual pressure densities is obtained.
  • This correction function can also be included in the standard calibration function according to FIG. 2, as a result of which a strand calibration function is obtained which is used for this engraving strand during the next production engraving (FIG. 6).
  • the actual pressure densities D actual obtained are again determined by means of the wells engraved in the test wedges and any remaining deviations from the target pressure densities D so n (FIG. 3). From this, an improved strand calibration function is calculated in the manner described above (FIG. 6), which is then used in the subsequent production engravings.
  • a new strand calibration is expediently calculated when the residual deviations between the target pressure densities D so n and the actual pressure densities D, st have exceeded a predetermined tolerance limit.
  • the calibration of the engraving strands thus takes place in a process of "self-learning", in which the settings of the engraving amplifiers in the individual engraving channels are continuously optimally adapted to the changing technical boundary conditions, such as different degrees of wear of the engraving stylus used.
  • the calibration method according to the invention for adjusting the density of the engraving strands was explained using the example of setting the engraving channels by means of the transverse diagonals of the engraved cells.
  • the method can be carried out in the same way if a different geometry value of the engraved test wedge cells is used instead of the transverse diagonals, for example the longitudinal diagonal, the area or the volume of the cells.
  • a standard calibration function is used which relates the geometry value used to the target pressure densities D so n.
  • An improved accuracy of the calibration method according to the invention can be achieved if the geometry value used is set not only for three characteristic target pressure densities but for additional intermediate levels, for example for tonal values in a gradation of 10% between light and depth.
  • the signal values S with which the engraving channels are controlled are individually corrected for each individual strand. This is illustrated in FIG. 7, where the relationship between the signal values S and the print densities D is shown (cf. FIG. 1).
  • the target pressure densities D so n and the actual pressure densities Dj St achieved in a specific engraving line after the standard calibration are plotted as a function of the control signal values S.
  • a signal value S 80 was used for control (point E).
  • the actual pressure density thus achieved is higher by the residual deviation ⁇ D (point F).
  • This correction function can be implemented, for example, by a table memory in each engraving channel, with which a corrected signal value S k0 rr is assigned to each input signal value S.
  • This condition can be ensured, for example, by increased pigmentation of the printing ink, the pigmentation having to be increased to such an extent that the above condition is met in all strands.
  • the temporal change in the residual deviations between the actual printing density Djst and the target printing density D so n in the individual engraving lines is additionally taken into account in order to make a prediction about the expected residual deviations and thus about the expected changes in the To make strand calibration function.
  • One reason for the change over time is the progressive wear of the engraving stylus with the age or frequency of use of the engraving stylus. A different degree of wear on the engraving stylus can be due to the fact that previously differently large areas were engraved in the engraving strands and / or the engraving strands have different engraving properties, which can be attributed, for example, to an uneven galvanizing of the printing cylinder.
  • the change in the geometry values relevant for the calibration can also be applied, for example, depending on the frequency of use of the engraving stylus in order to derive a prediction of the setting values for the next engravings.
  • the frequency of use can be measured, for example, by adding up the cumulative number of engraved cells in a counter that is present in each engraving channel. Alternatively, this number can also be determined and stored in the control software.
  • the measurements of the actual print densities and the set geometry values are carried out by automatic measuring devices. Furthermore, it is advantageous to store and manage the measured values and the determined setting values for the individual strand calibrations as well as the time-dependent dependencies and development trends in a central computer, so that the density adjustment between the individual engraving strands takes place automatically and also over a longer period Time is automatically adapted to the changing technical conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)

Abstract

L'invention concerne un procédé pour la gravure de cylindres d'impression dans une machine à graver électronique. Dans le procédé selon l'invention, au moins deux bandes à graver adjacentes dans le sens de l'axe sont gravées sur un cylindre d'impression, chacune à l'aide d'un organe de gravure qui lui est affecté. Selon l'invention, les propriétés électriques des organes de gravure sont réglées à l'aide d'une fonction de calibrage standard de sorte que, lors de la commande des organes de gravure avec des valeurs de signaux S faisant partie de densités d'impression de consigne caractéristiques Dcons, des godets sont gravés avec des valeurs géométriques prédéfinies par la fonction de calibrage standard. Afin de compenser les densités d'impression dans les différentes bandes à graver, les écarts entre les densités d'impression de consigne Dcons et les densités d'impression réelles Dréelle sont calculés et un calibrage de bande corrigé en est déduit pour la bande à graver concernée. Les calibrages de bande corrigés sont générés par détermination, à partir des écarts, de valeurs géométriques corrigées ou de valeurs de signaux corrigées S. Grâce aux calibrages de bande corrigés, le calibrage est adapté en continu automatiquement aux propriétés changeantes des organes de gravure et des bandes à graver.
EP00982988A 1999-10-19 2000-10-12 Procede pour la gravure de cylindres d'impression Withdrawn EP1310088A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19950278 1999-10-19
DE19950278 1999-10-19
PCT/DE2000/003581 WO2001031911A1 (fr) 1999-10-19 2000-10-12 Procede pour la gravure de cylindres d'impression

Publications (1)

Publication Number Publication Date
EP1310088A1 true EP1310088A1 (fr) 2003-05-14

Family

ID=7926126

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00982988A Withdrawn EP1310088A1 (fr) 1999-10-19 2000-10-12 Procede pour la gravure de cylindres d'impression

Country Status (4)

Country Link
US (1) US7085018B1 (fr)
EP (1) EP1310088A1 (fr)
DE (1) DE10050792A1 (fr)
WO (1) WO2001031911A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10159241B4 (de) * 2001-12-03 2005-05-19 Hell Gravure Systems Gmbh Verfahren zur Gravur von Druckformen
AU2008100847A4 (en) * 2007-10-12 2008-10-09 Bluescope Steel Limited Method of forming textured casting rolls with diamond engraving

Family Cites Families (17)

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Publication number Priority date Publication date Assignee Title
CH577671A5 (fr) * 1972-06-21 1976-07-15 Europ Rotogravure Ass
US4003311A (en) * 1975-08-13 1977-01-18 Bardin Karl D Gravure printing method
US4672466A (en) * 1985-02-05 1987-06-09 R. R. Donnelley & Sons Company Operator selectable multiple gradation scanner and engraver apparatus and method
US5422958A (en) * 1990-05-25 1995-06-06 R. R. Donnelley & Sons Company Printing cylinder engraver calibration system and method
JP2818525B2 (ja) * 1992-10-28 1998-10-30 大日本スクリーン製造株式会社 グラビア彫刻機のスタイラス変位調整装置
JP3274200B2 (ja) * 1992-12-28 2002-04-15 キヤノン株式会社 画像形成方法及び装置
US5831746A (en) 1993-02-25 1998-11-03 Ohio Electronic Engravers, Inc. Engraved area volume measurement system and method using pixel data
US20020135811A1 (en) * 1993-02-25 2002-09-26 Flannery David L. Error detection apparatus and method for use with engravers
US6362899B1 (en) * 1993-02-25 2002-03-26 Mdc Max Daetwyler Ag Error detection apparatus and method for use with engravers
US5440398A (en) * 1993-02-25 1995-08-08 Ohio Electronic Engravers, Inc. Error detection apparatus and method for use with engravers
US5438422A (en) * 1993-02-25 1995-08-01 Ohio Electronic Engravers, Inc. Error detection apparatus and method for use with engravers
US5617217A (en) * 1993-02-25 1997-04-01 Ohio Electronic Engravers, Inc. Engraving method and apparatus for generating engraving drive signals for engraving engraved areas of accurately controlled size in the surface of a workpiece using coefficient values and associated set up parameter values
US6348979B1 (en) * 1993-02-25 2002-02-19 Mdc Max Daetwyler Ag Engraving system and method comprising improved imaging
US5663802A (en) 1993-02-25 1997-09-02 Ohio Electronic Engravers, Inc. Method and apparatus for engraving using multiple engraving heads
US5737090A (en) * 1993-02-25 1998-04-07 Ohio Electronic Engravers, Inc. System and method for focusing, imaging and measuring areas on a workpiece engraved by an engraver
DE19814939A1 (de) * 1998-04-03 1999-10-07 Heidelberger Druckmasch Ag Verfahren zum Positionieren von Gravierorganen
DE19835303B4 (de) * 1998-08-05 2004-07-01 Hell Gravure Systems Gmbh Verfahren zur Erzeugung und Auswertung einer Probegravur

Non-Patent Citations (1)

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Title
See references of WO0131911A1 *

Also Published As

Publication number Publication date
US7085018B1 (en) 2006-08-01
DE10050792A1 (de) 2001-06-07
WO2001031911A1 (fr) 2001-05-03

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