EP1167033A1 - Method for presetting an inking unit - Google Patents

Abstract

Ink layer commands are set for ink layer in each color zone (s) of inking unit according to ink cover distribution. Ink feed is simulated to calculate simulated ink coverage distribution, whereby steady state error between ink cover command for printed ink layer and simulated ink cover distribution is brought to zero. Ink zone screw presettings are determined. Ink zone screws are preset before or at start of actual print run. Independent claim for system to control inking unit of offset printing machine, and for computer readable medium with operation program.

Description

The present invention relates to a method for presetting an inking unit and a system for controlling an inking unit in offset printing machines according to the The preamble of claims 1 and 8.

In offset printing, color is transferred from a color box to a color unit Plate cylinder and finally fed to a blanket cylinder, of which the latter the ink is transferred to a substrate (e.g. paper). The inking unit includes an ink fountain roller that picks up the ink on the ink fountain and places it on the lifting roller transfers. The lifter roller swings between the ink fountain roller and a friction roller back and forth and in this way transfers the ink from the ink fountain roller to the Distributor roller. From this the ink is transferred to other friction rollers via distributor rollers which distribute the ink over several inking rollers. The Ink application rollers transfer the ink to the lipophilic surfaces on the Plate cylinder clamped printing plate. From there, the colored print image is on transfer the blanket.

The amount of ink transferred is a critical factor in print quality. Too much Color in the inking unit leads to smearing of the printed image. With too little color the printed image is too weak and the color is not evenly distributed.

Different amounts of color are required for different zones of the printed image. Around to achieve a different ink distribution along the width of the ink rollers the amount of ink picked up from the ink fountain with the help of ink fountain keys can be set. Each ink zone screw determines the ink supply for a specific one Area, d. H. a zonal color transmission path. Different types of Printing units have a different number of color zones along the width of the Ink rollers on. The number of ink zones and ink zone screws is in Usually between six and sixty or even more.

The ink supply depends on various variables. Due to the Flow properties of the color is first of all the ratio between the gap at the Ink fountain key and the amount of ink supplied to a specific Ink fountain key not linear. In addition, the steady state behavior of the color, d. H. the behavior of the color and the inking unit in a stable condition or State of equilibrium, the type of ink, dampening solution and paper as well as the working temperature and the humidity in the print shop. In addition, the various friction rollers in the inking unit cause a considerable lateral Distribution of the color so that the one supplied to a specific zone on the rubber blanket Color quantity not exclusively from the corresponding ink zone screw Ink zone, but also by the adjacent ink keys. Since the Paint on its way from the ink fountain to the rubber blanket several laterally oscillating When rubbing rollers happen, a certain amount of ink is transferred from one zone to the neighboring zones transfer. This phenomenon can be referred to as blurring the color zones laterally become. The ink application on the substrate is still dependent on the Transfer rate, d. H. from splitting the color layer from the rubber blanket to the Printing material. (The ink layer is only partially transferred from the rubber blanket, so that a Part of the color is transferred to the paper and part of the color on the rubber blanket remains and is transported back to the inking unit.) Typical transfer conditions are z. B. 50:50, 30:70. 70:30 etc.

The nominal value of the color transfer is usually during the set-up of the machine using a file or data from a plate scanner or digital Platesetter determined. Because of the various parameters inherent in the system however, the actual setting of the ink zone opening differs significantly from the nominal value of the paint layer. It therefore always takes a certain amount of time to start up the press for a new print job the correct inking unit setting for production has been reached. When the plate cylinder finally for the Production printing is started on the blanket cylinder, some substrates printed with too much or too little ink, so that a lot of waste arises.

Accordingly, it is an object of the present invention to provide a method for Presetting of an inking unit and a system for controlling an inking unit for To create offset printing machines, by which the disadvantages of the known Devices and methods of this type are eliminated and which are more reliable and enable more precise adjustment of the machine with ink zone presets which enables fast and reliable inking unit adjustment while setting up the Machine and thus a minimum of waste.

This object is achieved by a method with the features of Claim 1 and solved by a system with the features of claim 8. Further Features of the invention are contained in the subclaims.

A method for presetting an inking unit in an offset printing press with the Process step Entering a color coverage distribution for an image to be printed is characterized by a setting of ink layer commands for the printed Ink layer in each ink zone of the inking unit according to the ink coverage distribution; a Simulation of an ink supply process to calculate a simulated one Ink coverage distribution, with a steady state error between the ink layer commands for the printed ink layer and the simulated ink coverage distribution Is brought to zero and ink fountain key presets are determined; and a pre-setting of the ink fountain keys of the inking unit before or at the beginning of the actual print job with the determined ink fountain key presets.

Furthermore, it can be provided that a Printing plate is scanned using a plate scanner and the Color coverage distribution is determined. Alternatively, you can enter the Color coverage distribution the transfer of data from a digital file Platesetters include. However, the data can also be obtained directly from prepress be taken over.

Diskretisierung aller Farbübertragungswege im Farbwerk mit gleichgroßen Segmenten durch eine Einteilung in seitliche Segmente und Umfangssegmente;

Drehung der Druckwerkskomponenten um ein Umfangssegment,

Berechnung einer Farbmenge auf jedem Segment nach dem Durchlaufen eines zwischen zwei Walzen gebildeten Spalts;

Berechnung einer seitlichen Überlappung der Segmente auf der Basis einer seitlichen

Bewegung mindestens einer Reiberwalze in einem vorgegebenen Farbübertragungsweg; Wiederholung der Drehung der Druckwerkskomponenten und der Berechnungen für eine

Vielzahl von Umdrehungen eines Plattenzylinders.

The simulation can include the following steps:

Discretization of all ink transfer paths in the inking unit with segments of the same size by division into lateral segments and circumferential segments;

Rotation of the printing unit components around a circumferential segment,

Calculating an amount of ink on each segment after passing through a gap formed between two rollers;

Calculate a side overlap of the segments based on a side

Movement of at least one friction roller in a predetermined ink transfer path; Repeat the rotation of the printing unit components and the calculations for one

Variety of revolutions of a plate cylinder.

The color mass is preferably calculated by summing up the color in the gap ink layers arriving from the rollers on the ink transfer paths and that Divide the calculated ink mass between the two rollers forming the gap in accordance with a predetermined color layer splitting rate. In this way, the amount of color in can be calculated advantageously.

Furthermore, it is preferably provided that the amount of ink entering the gap is one is the weighted sum of overlapping segments, the weighting being proportional to Overlap rate is.

In addition, the parameters of a closed color control loop are preferred optimized.

A system according to the invention for controlling an inking unit of an offset printing press, wherein the inking unit has an ink fountain for supplying ink depending on the respective settings of a large number of ink fountain keys, each one zonal ink transfer path are assigned along the color from the ink fountain a printing material to be printed is transferred, and a large number of Ink transfer nip forming rollers with at least one friction roller, one Plate cylinder and a blanket cylinder for printing on a printing material comprises, is characterized by a device for receiving data input regarding the color registration distribution for an image to be printed, which is programmed to to simulate a proportional-integral control device that works with a variety of Adjusting elements is connected, each for setting an ink fountain key opening a respective ink zone screw of the ink fountain; to paint layer commands for that Ink fountain keys of the ink fountain depending on the ink coverage distribution set; to simulate an ink feed process to calculate a simulated one Ink coverage distribution, whereby by means of feedback from printing unit information Steady state errors between the paint layer commands and the simulated one Ink coverage distribution is calculated; to bring the steady state error to zero and determine ink fountain key presets; the device being a Output to output the ink fountain key presets of the inking unit Begins an actual print job to print the image.

It can also be provided that a computer-readable medium, e.g. B. a Computer program product to create which is an operating program for definition of a method as described above.

The features of the present invention will become apparent in the following description preferred embodiments in connection with the attached, below listed drawings explained in more detail.

Fig. 1

eine schematische Darstellung eines Farbwerks einer Offsetdruckmaschine mit einem erfindungsgemäßen Farbsteuerungs-Voreinstellungssystem;

Fig. 2

ein Ablaufdiagramm des erfindungsgemäßen Verfahrens;

Fig. 3

ein Blockdiagramm, das ein Farbsteuerungssystem des Standes der Technik darstellt;

Fig. 4

ein Schaubild, das Farbsteuerungsbeispiele unter Einsatz des erfindungsgemäßen Verfahrens zeigt;

Fig. 5

eine schematische Darstellung einer beispielhaften Farbverteilung auf der Druckplatte; und

Fig. 6

ein Schaubild einer Ausführungsform eines Systems zur Voreinstellung der Farbzonenschrauben.

Show it:

Fig. 1

a schematic representation of an inking unit of an offset printing press with a color control preset system according to the invention;

Fig. 2

a flowchart of the method according to the invention;

Fig. 3

a block diagram illustrating a prior art color control system;

Fig. 4

a diagram showing color control examples using the method of the invention;

Fig. 5

a schematic representation of an exemplary color distribution on the printing plate; and

Fig. 6

a diagram of an embodiment of a system for presetting the ink fountain keys.

Fig. 1 shows an upper inking unit of an offset printing machine. The color is in the Ink fountain 1, which has a flexible lower section formed by ink squeegees. The opening of the ink squeegee is determined using ink fountain keys and controlled. The inking unit is divided into lateral zones, each with an ink zone screw include. The invention is based on six color zones, i. H. out of six Ink zone screws are described along the width of the inking unit. As already mentioned, inking units of conventional offset printing presses can be any number of Have color zones. The present invention has e.g. B. already at one M1000BE printing press from Heidelberg Web Systems, New Hampshire, tested, which has 24 color zones.

The ink is picked up by an ink fountain roller 2 from the ink fountain 1. A Lifter roller 3 oscillates between the ink fountain roller 2 and an ink transfer roller 5, which transfers the ink to a friction roller 4. The friction roller 4 oscillates laterally, i. H. with respect to its axis in the longitudinal direction, so that the paint is rubbed laterally and remains at a constant temperature. The ink transfer rollers 5 connect the different ones Friction rollers 4 with each other. Ink application rollers 6 contact at least one Transfer roller 5 and transfer the ink to a printing plate on a Plate cylinder 7. From there, the paint on a rubber blanket 8a Blanket cylinder 8 and then transferred to a paper web 9.

The system is divided into zones s, through the entire ink transfer path segments of the same size are created. The segments are separate elements that are in one digitized or discretized format can be processed. The number of Ink zone screws of the ink fountain 1 in the exemplary embodiment described here defines six zones. In addition, several zone fields are on the periphery of the Blanket cylinder defined along its circumference.

The present invention is based on a web-fed rotary printing press described, but can also be used in sheet-fed rotary printing machines.

For each zone, a paint layer command, ie a command regarding the thickness of the paint layer, is input to a control device 10. The control device 10 defines the ink fountain key openings in accordance with the transfer function G _C. The control system for the presetting receives error signals from a measuring bar which measures the ink thickness in each of the six zones on the rubber blanket 8a. When the ink is adjusted before the actual printing process, the control system receives the error message from a measurement on the inking roller 6.

The flowchart shown in FIG. 2 shows a printing group simulation with an error feedback signal F (s). The commands for the desired ink layer thickness R (s) are entered via an adding device 11. The signals are processed in a control device 12 of the ink fountain keys. In the present exemplary embodiment, the control device 12 is designed as a proportional-integral control (PI) with a transfer function G _C , which contains a proportional gain K _P and an integral term K _I / _p , where K _{I stands} for the integral gain.

The term p stands for the differential operator p ≡ d / dt , and the term l / p for the

Auf die Steuerungsvorrichtung folgt eindifferential operator

The control device follows

Minimum / maximum limiter 13, which the output signals of the control device on Values between the maximum setting (e.g. 20 = fully open) and the minimum Setting (0 = completely closed) limited.

The feedback of the system, ie of the printing unit, is defined as a transfer function H (s), which requires an input of the color coverage for each zone s. The coverage corresponds to the desired color coverage of a zone determined by a plate scanner file or a file of a digital platesetter. As is clear from the following example, the transfer function G _{C of} the control system defines the final output signal C (s) - the ink fountain key setting or the ink film thickness on the ink fountain roller 2 - both after the initializing simulation and after the final calculation of the ink control presetting.

The transfer function H (s) stands for the printing press or the examined Printing unit. It can be a simulation or the actual system. The Output of the feedback or simulation 14 stands for the actual color layer or the optical density on the rubber blanket 8a or for the actually printed ink layer.

• Konfiguration des Farbwerks: die Durchmesser der verschiedenen Walzen und der Farbübertragungsweg, d. h. die Farbübertragungsspalte zwischen den verschiedenen Walzen;
• Durchmesser der Reiberwalzen: Die Reiberwalzen 4 definieren die seitliche Verwischung des Farbwerks. Das System enthält also Informationen über die Reiberwalzen, z. B. die Oszillationsfrequenz, die Amplitude und die relative Bewegungsphase.
• Farbschichtspaltung: die Farbschichtspaltungsrate definiert die Farbmenge, die an jedem Farbübertragungsspalt übertragen wird, d. h. der Teil der Farbmenge, der von der ersten Übertragungswalze nach dem Übertragungsspalt auf die nächste Walze übertragen wird.
• Parameter des Farbzufuhrmechanismus: Die Heberwalze, die zwischen der Farbkastenwalze und einer weiteren Übertragungswalze hin und her schwingt, ist durch eine Schwingungsperiode und durch den Zeitraum der Schwingungsperiode definiert, in dem die Heberwalze die Farbkastenwalze und die Übertragungswalze kontaktiert.
• Einteilung der Platte: Wenn die Platte in beispielsweise 30 seitliche Segmente und 50 Umfangssegmente unterteilt ist, enthält die Bildinformation 1500 einzelne Segmente, die jeweils eine bestimmte Deckung aufweisen, die wiederum selbst diskretisiert oder als Prozentwert ausgedrückt werden kann (0 bis 100%).
• Farbzufuhr: Im beschriebenen Ausführungsbeispiel beziehen sich Angaben zur Farbzufuhr auf die Farbschichtdicke auf der Farbkastenwalze.

The simulation for the function H (s) requires several inputs:

• Configuration of the inking unit: the diameter of the different rollers and the ink transfer path, ie the ink transfer gaps between the different rollers;
• Diameter of the friction rollers: The friction rollers 4 define the lateral blurring of the inking unit. The system thus contains information about the friction rollers, e.g. B. the oscillation frequency, the amplitude and the relative movement phase.
• Ink layer splitting: the ink layer splitting rate defines the amount of ink that is transferred to each ink transfer nip, ie the part of the amount of ink that is transferred from the first transfer roller after the transfer nip to the next roller.
• Ink delivery mechanism parameters: The siphon roller that oscillates between the ink fountain roller and another transfer roller is defined by an oscillation period and the period of the oscillation period in which the elevator roller contacts the ink fountain roller and the transfer roller.
• Classification of the plate: If the plate is divided into 30 lateral segments and 50 circumferential segments, for example, the image information contains 1500 individual segments, each of which has a certain coverage, which in turn can be discretized or expressed as a percentage (0 to 100%).
• Ink supply: In the exemplary embodiment described, information about the ink supply relates to the ink layer thickness on the ink fountain roller.

The signal C (s) relates to the opening of the ink zone screws on the ink fountain 1. The signal C (s) is formed by multiplying the proportional gain component of the transfer function G _C by the error signal E (s), ie C (s) = G _C · E (s), where

E (s) = R (s) - H (s) C (s) and G _C = K _p + K ₁ / p. Here C (s) is limited to 0 ≤ C (s) ≤ 20.

This results in: C (s) = Gc (p) 1 + GCH () R (s) and E (s) = 1 1 + GCH (s) R (s).

The parameters K _P and K _{i of} the control device are set for the respective inking unit configuration in order to reduce the error and to maintain the stability. The response of the inking system depends on the speed at which the rollers 2-8 are driven and on the number of rollers involved. The aim is to bring the error signal feedback F (s) (e.g. the ink layer on the rubber blanket) closer to R (s) by reducing the error signal E (s) to zero.

The property of the new color control and presetting system becomes all the clearer in comparison with the prior art presetting system shown in FIG. 3. The transmission properties of the system are estimated here by simulation or tests. The test results are used to estimate the transmission matrix H (s). Finally, the matrix H (s) for calculated ink fountain key presets is inverted to H ^-1 (s) for a given ink coverage and ink layer thickness. It should also be noted that the color zone openings are limited, ie the zones can be completely closed or open, but not more or less. The ink transfer system function H (s) depends on the ink coverage distribution. The function H (s) developed in this way is an estimate. The method according to the invention reverses the actual system matrix by using a feedback system with high controller gain.

The simulation output according to the invention represents that printed on the paper Coat of paint. Is z. B. assumed a color layer splitting ratio of ½ (50:50), so the ink layer printed on the paper is just as thick as that on the rubber blanket the gap left between the blanket and the paper Coat of paint. 4 and 5 is a color control simulation in six adjacent zones of the inking unit of an offset printing press of the type M1000BE shown by Heidelberg Web Systems. To simplify implementation uniform coverage was assumed within all zones. The Ink zone screw width on the ink fountain is approximately 41 mm. As in Fig. 5 is shown, the color coverage distribution for the zones was as follows percentage coverage determined: 100, 10, 50, 30, 80, 100.

The first prediction on which the calculations were based was that when attempting online color control by measuring the optical density (OD) and setting the ink fountain keys for a given laterally varying ink requirement and inherent lateral inking unit coupling, no zero-order error, e.g. B. stability. The simulation was carried out with a temporal inking unit simulation program, a software-controlled multivariable inking unit simulation. The ink film thickness on the blanket was used as a control loop feedback variable, and each zone was subjected to the proportional-integral control process on the fault using the transfer function G _C (s) of the PI controller 12.

The first simulation shown in Fig. 4 started with completely closed Ink fountain keys in all six zones. The target value for the printed ink layer was set to 0.00254 mm. The diagram shows the color layer on the rubber blanket (which is directly proportional to the layer of ink on the paper) against the number of complete revolutions of the plate cylinder. In the range between about 50 and 100 A first overshoot was observed in all color zones. At about 150 revs there was a deficit in the ink supply to the plate cylinder. After one slight overshoot at about 230 revs the system reached steady State after about 260 turns. Both overshoot (smear of color) as well as a deficit in the ink supply (pale, blurred printing) are undesirable and lead to waste.

The unpredictability of the individual color zone settings for the different zones becomes clear from the final color zone setting listed in the following table: even coverage final color zone setting C (s) Zone 1 100% 430.0 Zone 2 10% 0.0 Zone 3 50% 151.6 Zone 4 30% 80.3 Zone 5 80% 1,421.6 Zone 6 100% 508.0

The final color zone setting determined by the simulation was then used as the initial setting for a new production run of the same printing process. The second run of the presetting process shown in FIG. 6 can be again as Simulation or performed as an actual preset process for the inking unit become. This open process-linked process begins with an empty inking unit. The The desired ink layer thickness is 0.00254 mm. As shown, there are none Overshoots or deficits more noticeable. The system only reaches about 100 revolutions of the plate cylinder the steady state.

It is also possible to use the feedback signals F (s) from neighboring zones, z. B. F (s-1), F (s) and F (s + 1) to feed respective adders 11, wherein respective error signals E (s), e.g. B. E (s-1), E (s) and E (s + 1) are generated, which with a respective desired weighting provide an additional one Weighting device are supplied, from where a weighted error signal E ' Control device 12 is supplied. In this way, the weighting of the Influence of neighboring zones on a selected zone in the calculation with be included.

The results obtained from the simulations shown in the graphs show that color control can be used with the new method without any problems.

As already mentioned, the color control can be used to preset the ink fountain keys be used during machine setup. As soon as the simulation has reached stable condition and the OD errors on the printed substrate are minimized, the determined ink fountain key openings can be regarded as new Presets can be used. The presets can be changed during the Setup can be determined by setting the necessary parameters such as the desired coverage and the color properties are entered into the processor. The processor program typically has the necessary information about the machine-specific parameters such as B. the number and width of the color zones that Actuator information etc.

Furthermore, it is possible not only to adjust the ink zone according to the invention Presetting the color zones to use, but also to make changes or Carry out fine adjustments during production. For this, the The simulation described is carried out in parallel with the production run to ensure that the necessary Receive changes to the color zone settings or to individual color zones and then carried out on the printing press. So z. B. a change in Color thickness of a certain color zone is first simulated in this way and then by means of the calculated ink zone opening.

Although the exemplary embodiment is based on a web-fed rotary printing press has been described, it can also be used for sheet-fed rotary printing machines. The The procedure is also to adjust the inking unit before the actual printing process beneficial to ensure that the paint as quickly as possible when the machine starts up possible on the substrate in the right amount. This is done by a Presetting of the inking unit reached before the inking rollers on the Plate cylinders can be turned on.

The measurement of the ink layer thickness for the feedback signal can be done on the rubber blanket respectively. It is also possible to measure the color layer thickness or the optical Measure density at a downstream location, e.g. B. on the cooling rollers.

a) Alle Farbübertragungswege werden mit gleichgroßen Segmenten diskretisiert.

b) Das Druckwerk wird um ein Umfangssegment vorwärts gedreht.

c) Die Farbe auf jedem Element, die gerade an einem Spalt übertragen wird, wird mit Hilfe von Massenerhaltungsprinzipien berechnet. Die in einem Spalt übertragene Farbe ist die Summe der Farbschichten, die von den vorgeordneten Walzen eingelaufen sind. Die Farbschicht teilt sich zwischen den beiden Walzen gemäß der jeweils voreingestellten Farbschichtspaltungsrate auf.

d) Die seitliche Überlappung von Elementen wird auf der Basis der seitlichen Bewegung der Reiberwalze berechnet. Die einlaufende Farbmenge wird als die gewichtete Summe der überlappenden Elemente betrachtet. Die Gewichtung ist proportional zur Überlappungsrate.

e) die Schritte b) bis d) werden für die gewünschte Anzahl von Plattenzylinder-Umdrehungen wiederholt.

The invention is implemented in computer technology as follows:

a) All color transmission paths are discretized with segments of the same size.

b) The printing unit is rotated forward by a circumferential segment.

c) The color on each element that is currently being transferred to a gap is calculated using mass conservation principles. The color transferred in a gap is the sum of the layers of paint that have entered the upstream rollers. The ink layer is divided between the two rollers according to the preset ink layer splitting rate.

d) The lateral overlap of elements is calculated based on the lateral movement of the friction roller. The amount of color coming in is considered the weighted sum of the overlapping elements. The weighting is proportional to the overlap rate.

e) steps b) to d) are repeated for the desired number of plate cylinder revolutions.

Additional information on the simulation described is in the publication "Computer simulation of offset printing: III. Effect of Ink Feed Mechanism" (Computer simulation in offset printing: III. The effect of the ink feed mechanism) by Chou and Niemiro, published by the Technical Association of the Graphic Arts, contain.

List of reference numbers

1

paintbox

2

Ink fountain roller

3

vibrator roller

4

distributor roller

5

transfer rollers

6

applicator rollers

7

plate cylinder

8th

Blanket cylinder

8a

blanket

9

paper web

10

control device

11

adder

12

control device

13

Min / max limiter

14

Feedback device

C (s)

output signal

It)

error signal

F (s)

Error-back signal

G _C

transfer function

H (s)

Transfer Function / transfer matrix

K _I

integral reinforcement

K _P

proportional gain

R (s)

Commands for the printed ink layer

s

Zone

Claims (9)

Method for presetting an inking unit in an offset printing machine with the method step inputting a color coverage distribution for an image to be printed,
marked by Setting ink layer commands for the printed ink layer in each Ink zone of the inking unit according to the ink coverage distribution; Simulating an ink supply process to compute a simulated ink coverage distribution, zeroing a steady state error between the ink layer commands for the printed ink layer and the simulated ink coverage distribution, and Ink fountain key presets are determined; and Presetting the ink fountain key of the inking unit before or at the start of the actual print job with the determined ink fountain key presettings. Method according to claim 1,
characterized in that when the ink coverage distribution is entered, a printing plate is scanned using a plate scanner and the ink coverage distribution is determined. Method according to claim 1,
characterized in that the input of the color coverage distribution comprises the transfer of data from a file of a digital platesetter. Method according to one of the preceding claims,
characterized in that the simulation comprises the following steps: Discretization of all ink transfer paths in the inking unit with segments of the same size by division into lateral segments and circumferential segments; Rotation of the printing unit components around a circumferential segment, Calculating an amount of ink on each segment after passing through a gap formed between two rollers; Calculating a lateral overlap of the segments based on a lateral movement of at least one friction roller in a given ink transfer path; Repeat the rotation of the printing unit components and the calculations for a large number of revolutions of a plate cylinder. Method according to claim 4,
characterized in that the calculation of the amount of ink comprises the calculation of the ink mass by adding up the ink layers entering the nip from the rollers on the ink transfer paths and dividing the calculated ink mass between the two rollers forming the nip according to a predetermined ink layer splitting rate. Method according to claim 5,
characterized in that the amount of ink entering the gap is a weighted sum of overlapping segments, the weighting being proportional to the overlap rate. Method according to one of claims 1 to 6,
characterized in that parameters of a closed color control loop are further optimized. System for controlling an inking unit of an offset printing press, the inking unit providing an ink fountain (1) for supplying ink depending on the respective settings of a plurality of ink fountain keys, each of which is assigned to a zonal ink transmission path, along the ink from the ink fountain (1) towards one printing substrate (9), and a plurality of ink transfer nip forming rollers (2, 3, 4, 5, 6), with at least one friction roller (4), a plate cylinder (7) and a blanket cylinder (8) for printing on a printing material (9)
marked by a device for receiving data entries relating to the color coverage distribution for an image to be printed, which is programmed, in order to simulate a proportional-integral control device (10), which is connected to a multiplicity of adjusting elements, for respectively adjusting an ink fountain key opening of a respective ink fountain key of the ink fountain, to set ink layer commands for the ink fountain keys of the ink fountain (1) depending on the ink coverage distribution; in order to simulate an ink supply process for calculating a simulated ink coverage distribution, a steady-state error between the ink layer commands and the simulated ink coverage distribution being calculated by means of feedback from printing unit information; to bring the steady state error to zero and determine ink fountain key presets; the device comprising an output for outputting the ink fountain key presets of the inking unit at the start of an actual print job for printing the image. A computer readable medium, with an operating program, which a Method according to claim 1 defined.

Images