EP0668824B1 - Process for influencing the optical density of a printing ink layer on a print carrier - Google Patents

Process for influencing the optical density of a printing ink layer on a print carrier Download PDF

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Publication number
EP0668824B1
EP0668824B1 EP93924518A EP93924518A EP0668824B1 EP 0668824 B1 EP0668824 B1 EP 0668824B1 EP 93924518 A EP93924518 A EP 93924518A EP 93924518 A EP93924518 A EP 93924518A EP 0668824 B1 EP0668824 B1 EP 0668824B1
Authority
EP
European Patent Office
Prior art keywords
measuring
microprocessor
printing ink
colorimetric
values
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.)
Expired - Lifetime
Application number
EP93924518A
Other languages
German (de)
French (fr)
Other versions
EP0668824A1 (en
Inventor
Dietrich Roland Kamillus Leuerer
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.)
Koenig and Bauer AG
Original Assignee
Koenig and Bauer Albert AG
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
Priority to DE19924238557 priority Critical patent/DE4238557A1/en
Priority to DE4238557 priority
Application filed by Koenig and Bauer Albert AG filed Critical Koenig and Bauer Albert AG
Priority to PCT/DE1993/001083 priority patent/WO1994011192A1/en
Publication of EP0668824A1 publication Critical patent/EP0668824A1/en
Application granted granted Critical
Publication of EP0668824B1 publication Critical patent/EP0668824B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41FPRINTING MACHINES OR PRESSES
    • B41F33/00Indicating, counting, warning, control or safety devices
    • B41F33/0054Devices for controlling dampening

Abstract

In a process for setting the moisture content in an offset rotary machine, a signal for modifying the moisture content is to be generated before the scumming limit is reached. For that purpose, the densitometrically measured optical density on a control strip is compared with a number of variably selectable adjacent zones. When an adjustable measurement threshold is exceeded, the moisture content is modified as appropriate, thus preventing spoilage.

Description

  • The invention relates to a method for evaluating changes in the color density or colorimetric values of a printing ink application on printing substrates.
  • US 48 81 182 A describes a method for regulating the color density for offset printing during printing on a rotary printing press. The corresponding color density is periodically scanned on a color control strip for the selected color using a densitometer. Deviations in the ink densities from target values are used to meter the amount of printing ink. Control deviations of the ink density are used alternately for dosing the ink and dampening solution quantities, starting with the dosing of the dampening solution quantities. The amounts of dampening solution are dosed in a search procedure. The search process is controlled by comparing grid areas. The individual search process is limited to a predeterminable maximum number of setting steps in the same direction.
  • From DE 38 30 732 A1 a method for monitoring the dampening solution guidance in offset printing presses is known, with which unprinted or printed areas in the area of edges of or on predetermined color areas with the aid of a opto-electrical converter and the signals generated by the scanning are evaluated.
  • A disadvantage of the method is that signals for changing the amount of dampening solution are only triggered when toning occurs on a full-tone surface of the measuring field. The consequence of this is that the copies printed until the printed control sheet is removed are already of reduced quality.
  • The invention has for its object to provide a method for evaluating the fluctuations in the color density or colorimetric values of an offset rotary printing press.
  • According to the invention, this object is achieved by the features of patent claim 1.
  • The solution according to the invention results in particular in the following advantages. As a result of the determination of the ink density over a plurality of zones lying next to one another, the ink density values can be kept constant or these ink density values can be evaluated in a downstream logic, as a result of which the amount of dampening solution can be regulated continuously. A signal to change the amount of dampening solution is generated before the tone limit is reached, so that quality defects in printing are avoided for these reasons. The operating personnel or the automatic ink density control in the event of ink density changes can be given an indication or a signal as to whether and in which direction the amount of dampening solution or the amount of ink must be changed in order to achieve a desired ink density again. The method thus makes it easier to determine the causes of changes in color density of a color on a print carrier.
  • The invention is explained in more detail below using an exemplary embodiment. Show in the accompanying drawings
  • Fig. 1
    a block diagram of the device arrangement;
    Fig. 2
    a procedural schedule.
  • The color density of an ink job on a print carrier 1, - z. B. a printed sheet -, printed, extending transversely to the direction of the print substrate 1 z. B. color control strips with a plurality of measuring fields (measuring spots = with a standardized measuring surface) z. B. measured by means of a densitometer or colorimetric measuring device 2. However, suitable measuring spots from the subject itself can also be printed across the direction of rotation of the printing medium 1. For each color zone there is a measuring spot of the color involved z. B. "Magenta" in full tone and assigned in several tones. In a microprocessor 4, -. B. a computer with storage device and input and output units -, the position on the print medium 1 and its value are each stored by the color density or colorimetric measurement value 3. At the same time, the microprocessor 4 is given further selectable parameters or input values via an input device, e.g. B. Input keyboard 6 entered. However, the exact coordinates of the position of the measurement spots and the associated color density or colorimetric values with their permissible tolerance can also be entered. This makes it possible to take over values from previous productions. The amount of dampening solution supplied is changed in accordance with the method steps to be described below. This is done by increasing or decreasing the speed of the wet duct, not shown, which is driven by a motor 8. The speed of a motor 8 z. B. a DC motor, a speed sensor 9 is detected, and its
  • Measured values are supplied to the microprocessor 4 as the actual value.
  • In a first method step 21 an operator enters a start signal, e.g. B. via the input keyboard of the microprocessor 4. Subsequently, the input of parameters or input values via the input device 6 is carried out by the operator in a second method step 22 AZ - z. B. 11 adjacent zones of one of several colors -, also the time constant τ for the machine settling time, z. B. 50 sheets; a multiplier x for the time constant τ z. B. 4 can be entered. However, the aforementioned, selectable input values can also be temporarily stored in the microprocessor 4.
  • Then, in a third method step 23, the microprocessor 4 is supplied with the measured values determined by the densitometer 2 of a print carrier 1 to be tested and stored. The third method step 23 can run simultaneously with the method step 22. Measured values are the number of printed sheets T since the last change in ink moisture content; the number of adjacent zones with changed color density or. colorimetric value ANZ; a zonal density change Delta D.
  • In a fourth method step 24 the number of printed sheets determined during the period T after the last change in the amount of ink moisture.
  • In the event that the time period T from the last change in color and moisture is less than x times τ, z. B. at least 4 times 50 sheets, the process is completed. Otherwise, usually after the z. B. 200 sheets, it is determined in a next (fifth) method step 26 whether the number of preselected, adjacent zones AZ of a color is less than or equal to the number ANZ of adjacent, measured zones with changed color density or colorimetric value. In this case there is no reason to continue the procedure. If the color density value in process step 26 has only changed in a few adjacent zones or only in one zone, the logical conclusion that no moisture difference is present across the ink zones is derived from this, provided that there is no zonal dampening unit. In this case, the procedure is completed. Otherwise, in a further (sixth) method step 27, namely if the number ANZ of the adjacent zones with changed color density is greater than, for example, 11 adjacent zones of the same color with color density or colorimetric value deviations (measurement threshold) in the same direction -, brings about a color density or colorimetric change in value Delta D. The bringing about the color density or. colorimetric value change Delta D takes place in of the type that either the speed n of the dampening roller motor 8 and thus the speed of the dampening ductor is increased in a process step 28 if the color density or colorimetric value is too high, or in a step 29 if the color density or colorimetric value is too low Speed of the dampening motor 8 and thus the speed of the damping duct is reduced, for. B. by a readjustment of 1%, so that in the first case more dampening solution and in the second case less dampening solution is supplied. If it was recognized that the color density or the colorimetric value deviation is based on a deviation in the amount of dampening solution and a change in the speed of the dampening duct has taken place, then the time T can be significantly reduced due to the knowledge that a small change in dampening solution within a few printed copies causes a change in density that can be detected densitometrically . The zone with the greatest color density or colorimetric value deviation is used as a guide. The method is now ended with a last method step 31.
  • Not only paper sheets and webs can be seen as printing media in the sense of this invention, but also rubber blankets and clamped printing plates with an ink application.
  • To sum up, it can be said that the method according to the invention is a method for influencing the color density or colorimetric values of a printing ink application on a printing medium. Here, the color density or the colorimetric value of a plurality of color and position-defined measuring spots is measured on a printed, that is to say having a color application. For each color z. B. "Magenta" is the color density or the colorimetric value for each selected stain spot of an ink job on a print carrier for a plurality of position-defined, selected stain spots. These color density or colorimetric values, which are stored as a setpoint, and which can be measured on a print carrier designated as good, but also originate as pure measurement values from completed print jobs, can be supplied to a microprocessor as setpoints and stored there. For each of the color density or. The colorimetric values are therefore indicated on their target position on a print carrier and the permissible color density or colorimetric value with or without a permissible tolerance. The color density or colorimetric values of the selected, position-defined measuring spots are then measured and stored on a support to be checked for printing ink. These values are compared with the color density or colorimetric setpoints assigned to them and the determined color density or colorimetric deviations from the color density or colorimetric setpoints are temporarily stored in terms of value and position in a memory of the microprocessor. From these color density or. Colorimetric deviation values are then determined using an evaluation algorithm in the microprocessor to determine whether there are continuous rows of several adjacent measurement spots with color density or colorimetric deviations with the same direction (± direction). The gapless rows determined in this way are examined to determine whether they correspond to the required number of adjacent measurement spots of the same color density or colorimetric deviations. Then, if one or more rows of measuring spots with color density or colorimetric deviations in the same direction and a predetermined quantity of the immediately adjacent measuring spots are present, an electronic signal is generated by the microprocessor and an output device is passed on. There, this signal can be used to display ads for to generate an operator with the instruction to correspondingly increase or decrease the amount of dampening solution in accordance with the color density or the colorimetric deviations in the plus or minus direction. However, this electronic signal can also be fed to a control of a drive for a dampening solution supply device in order to then make the electromotive drive of the dampening solution quantity device run faster or slower. At the same time, this electronic signal can also be used to emit a second signal that the operator, such as an ink quantity supply device, gives the command not to change the ink quantity supply.
  • If none of the rows described above are identified, the microprocessor generates a command to change the amount of printing ink accordingly.
  • Parts list
  • 1
    Print carrier
    2nd
    Densitometer
    3rd
    Color density or colorimetric value
    4th
    Microprocessor
    5
    -
    6
    Input device
    7
    Speed controller
    8th
    engine
    9
    Speed detector
    10th
    -
    21 to 31 process steps
    AZ
    Number of adjacent zones, selected
    τ
    Time constant for machine settling time, measured in number of sheets
    x
    Multiplier for τ
    Δn
    Speed change of damping duct
    T
    Time since the last color moisture change, measured in number of sheets
    NUMBER
    Number of adjacent zones with changed color density
    ΔD
    zonal density change
    n
    Speed dampening

Claims (3)

  1. A process for influencing ink density or the colorimetric values of a printing ink layer on a print carrier by measuring the ink density or colorimetric values at a plurality of measuring spots which are defined by their position, and adjusting the printing ink supply and/or the dampening agent supply to give a colourfulness, which process comprises the following steps:
    for colourfulness there are selected a plurality of measuring spots which are located in colour zones lying next to one another without gaps;
    for the selected measuring spots, ink density or colorimetric set values are preset and stored in a microprocessor;
    subsequently the ink density or colorimetric values of the selected measuring spots on a print carrier, which is to be checked and which carries the printing ink, are measured and are stored as actual values in the microprocessor;
    subsequently, for each of the selected measuring spots, the actual value corresponding to the measuring spot is compared with the set value corresponding to the measuring spot, and from this any deviation from the set value is determined, each deviation being stored at intervals in time in the microprocessor along with the position of the respective selected measuring spot;
    subsequently, by means of an evaluation algorithm from the microprocessor, a determination is carried out as to whether there have formed in the plurality of selected measuring spots one or more rows in which a plurality of measuring spots located in the colour zones lying next to one another without gaps have deviations with the same sign; and
    finally, if one or more such rows are present, the microprocessor generates an electrical signal to alter the dampening agent supply accordingly.
  2. A process according to Claim 1, characterized in that if one or more such rows are present, the microprocessor generates the electrical signal such that the dampening agent supply is altered according to the deviations and the printing ink supply is left unaltered.
  3. A process according to Claims 1 and 2, characterized in that if the said rows are not present, the microprocessor generates a further electrical signal such that only the printing ink supply is altered according to the deviations.
EP93924518A 1992-11-14 1993-11-12 Process for influencing the optical density of a printing ink layer on a print carrier Expired - Lifetime EP0668824B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE19924238557 DE4238557A1 (en) 1992-11-14 1992-11-14 Method for adjusting the amount of dampening solution in an offset rotary printing press
DE4238557 1992-11-14
PCT/DE1993/001083 WO1994011192A1 (en) 1992-11-14 1993-11-12 Process for influencing the optical density of a printing ink layer on a print carrier

Publications (2)

Publication Number Publication Date
EP0668824A1 EP0668824A1 (en) 1995-08-30
EP0668824B1 true EP0668824B1 (en) 1997-02-19

Family

ID=6472940

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93924518A Expired - Lifetime EP0668824B1 (en) 1992-11-14 1993-11-12 Process for influencing the optical density of a printing ink layer on a print carrier

Country Status (5)

Country Link
US (1) US5568769A (en)
EP (1) EP0668824B1 (en)
JP (1) JP2793718B2 (en)
DE (2) DE4238557A1 (en)
WO (1) WO1994011192A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10013876B4 (en) * 1999-04-08 2013-10-02 Heidelberger Druckmaschinen Ag Method for controlling the coloring when printing with a printing machine

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19518660C2 (en) * 1995-05-20 1997-10-09 Koenig & Bauer Albert Ag Procedure for adjusting the amount of dampening solution
DE19546260C1 (en) * 1995-12-12 1996-11-21 Weitmann & Konrad Fa Monitoring spray quantity on material conveyor method , e.g. paper path moved towards a moistening position, in graphics industry
DE19643354A1 (en) * 1996-10-21 1998-04-23 Heidelberger Druckmasch Ag Wetting method for offset printing machine printing plate
US5791249A (en) * 1997-03-27 1998-08-11 Quad/Tech, Inc. System and method for regulating dampening fluid in a printing press
JP2003334930A (en) * 2002-05-21 2003-11-25 Dainippon Screen Mfg Co Ltd Printing press and damping water supply method therein
JP4638685B2 (en) * 2003-06-10 2011-02-23 ハイデルベルガー ドルツクマシーネン アクチエンゲゼルシヤフトHeidelberger Druckmaschinen AG Method of metering dampening water during printing on an offset press
US6796227B1 (en) * 2003-08-18 2004-09-28 Quad Tech Lithographic press dampening control system
DE102008041427B4 (en) * 2008-08-21 2013-09-19 Koenig & Bauer Aktiengesellschaft Method for automatic color control in a running printing process within a printing press
DE102010034350A1 (en) * 2010-08-14 2012-02-16 Manroland Ag Device for controlling fountain solution application and ink application in a printing machine

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD156239A1 (en) * 1981-01-07 1982-08-11 Eva Luebbe Method for correcting deviations from insertion and heating on offset printing machines
DE3444892C2 (en) * 1984-12-08 1986-11-13 M.A.N.- Roland Druckmaschinen Ag, 6050 Offenbach, De
US4972774A (en) * 1985-04-29 1990-11-27 Baldwin Technology Corporation Automatically controlling water feedrate on a lithographic press
DD253679A1 (en) * 1986-11-13 1988-01-27 Polygraph Leipzig Process for regulating color density
DE3830732C2 (en) * 1988-09-09 2000-05-25 Heidelberger Druckmasch Ag Process for dampening solution control in an offset printing machine
DE3907584A1 (en) * 1989-03-09 1990-09-13 Heidelberger Druckmasch Ag Method for humidity control in an offset printing machine
DE3912811A1 (en) * 1989-04-19 1990-10-25 Heidelberger Druckmasch Ag Method and device for the moistant controlling of an offset printing machine
AT123443T (en) * 1990-02-22 1995-06-15 Komori Printing Mach Apparatus for the examination of printed matters and related procedure.
FI103395B1 (en) * 1991-03-21 1999-06-30 Wifag Maschf A method for adjusting the raster spot size for an offset rotary printing press

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10013876B4 (en) * 1999-04-08 2013-10-02 Heidelberger Druckmaschinen Ag Method for controlling the coloring when printing with a printing machine

Also Published As

Publication number Publication date
DE4238557A1 (en) 1994-05-19
US5568769A (en) 1996-10-29
JP2793718B2 (en) 1998-09-03
WO1994011192A1 (en) 1994-05-26
DE4395722D2 (en) 1996-01-11
JPH07508692A (en) 1995-09-28
EP0668824A1 (en) 1995-08-30

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