EP3921164B1 - Method for adjusting a colour profile in a sheet-fed offset printing press using preprinted faulty sheets - Google Patents

Description

The invention relates to a method for setting a color profile in a sheet-fed offset printing press according to claim 1.

through the WO 2010/091947 A1 a method for setting an area coverage is known, wherein the area coverage is achieved by a quantity of printing ink transferred to a printing material by an inking unit of a printing press, wherein when a final phase of a printing process previously executed by the printing press is reached, an ink supply to the inking unit is switched off at least in zones or is interrupted in the inking unit, with the quantity of printing ink remaining on the printing material side after the ink supply in the inking unit has been switched off or interrupted being transferred to the printing material in the final phase of the printing process previously carried out by the printing press until the quantity of printing ink transferred to the printing material has equaled The area coverage that takes place corresponds to a target value of the area coverage, with a changeover of the printing press from the printing process currently running in this printing press to a subsequent printing process in an automated control process ss is carried out, with the same printing ink being transferred from the inking unit to the printing material in the subsequent printing process as in the previous printing process, with the target value of the area coverage corresponding to the area coverage provided for a proof of the subsequent printing process, the control process taking into account the specified target value for the area coverage to be set is carried out.

through the DE 37 07 695 A1 is a method for the defined generation of a color distribution in the inking unit of rotary printing presses that is close to that of production beginning of printing, in which the values stored in a computer for the zone-by-zone setting of the metering elements and the length of the color stripe for the previous print job are compared with the values entered into a second memory of the computer for the zone-by-zone setting of the color metering elements and the length of the color stripe for the following print job are compared and the zonal color difference amounts are formed from the values for each ink zone, which, supplemented by the zonal storage quantities of the inking unit, are transported back from the rotating inking unit into the ink fountain or are conveyed into the inking unit, depending on whether the color difference quantity is positive or negative, with before the number of inking unit revolutions required for this is determined until the zonal differential ink quantities are equalized and only then is the setting of the ink metering elements and the length of the inking unit required for the subsequent print job in the inking unit to be practiced r-carrying color stripe is carried out, with this setting color being conveyed neither out of the inking unit nor into the inking unit.

through the DE 10 2010 003 913 A1 a method for operating sheet-fed printing presses is known, in which a sheet-fed printing press lays out a stack of sheets in one printing pass, which stack contains at least one waste sheet and the sheets in this stack of sheets are printed in a subsequent printing pass, with the waste sheet being stored in the following printing pass by means of a storage or Sensor device of a sheet-fed printing press is detected, this memory or sensor device interacting with a machine controller which controls the sheet-fed printing press during the subsequent printing pass as a function of the detection result determined by the memory or sensor device.

through the DE 10 2013 217 099 A1 a method for detecting an order change in a stack of sheets to be processed is known, in which a sheet is marked by being marked in a preceding printing pass at least remains partially unprinted.

through the DE 10 2017 202 937 A1 is known, with a z. B. as a sheet-fed printing press or as a web-fed printing press trained printing machine a variety of print images with any design in their respective color and / or brightness and often changing motifs on a substrate z. B. from paper, cardboard, cardboard, from a plastic or from a metallic material to print.

The object of the invention is to provide a method for setting a color profile in a sheet-fed offset printing press.

The object is achieved according to the invention by the features of claim 1. The dependent claims each relate to advantageous refinements and/or developments of the solution found.

The advantages that can be achieved with the invention consist in particular in the fact that the printing press can be changed over quickly and economically from a first printing process currently running in the printing press to a subsequent second printing process. In addition to a saving in material costs, especially for the printing material, machine and operating costs can also be reduced because the printing press with the subsequent second printing process reaches the production of salable printed products after a very short time.

An embodiment of the invention is shown in the drawings and is described in more detail below.

Fig. 1

schematisch eine Bogenoffsetdruckmaschine;

Fig. 2

einen ersten und einen zweiten jeweils von der Bogenoffsetdruckmaschine auszuführenden Druckauftrag;

Fig. 3

den zeitlichen Ablauf eines Verfahrens zur Einstellung eines Farbprofils in der auf einen neuen Druckauftrag einzustellenden Bogenoffsetdruckmaschine.

Show it:

1

schematic of a sheet-fed offset printing machine;

2

a first and a second print job to be executed by the sheet-fed offset printing press;

3

the timing of a method for setting a color profile in the sheet-fed offset printing press to be set for a new print job.

When changing over a sheetfed offset printing press from a first currently running printing process to a subsequent second printing process, it is necessary to cancel a distribution of a printing ink to be transferred to a sheet-shaped printing material to be printed in this printing press along a transport path during the execution of the first printing process in order to to be able to produce a high-quality printed product in the second printing process, which is free from an undesired reaction to the printed product produced in the first printing process.

The distribution of this printing ink that occurs during the execution of the first printing process along the transport path of the printing ink is transverse to a transport direction of the printing material that is being transported through the printing press and is to be printed on i. i.e. R. uneven, d. H. along a line of intersection of the transport path of the printing ink that runs transversely to the transport direction of the printing material, several mostly differently shaped accumulations for the printing ink that is ultimately to be transferred to the printing material are formed, which is due to the fact that the printing material to be printed is transverse to its own during its transport through the printing press Transport direction due to an i. i.e. R. uneven design of a print image to be produced on the printing material absorbs printing ink unevenly.

The transport path of the printing ink leads, starting from an ink metering system belonging to an inking unit of the printing press, through the inking unit supplied with ink by the relevant ink metering system, via a z. B. on one of the belonging to a printing unit of the printing press printing unit cylinder arranged printing form up to the to be printed with the printing ink in question. The transverse to the transport direction of the printing material that occurs during the execution of the first printing process along this transport path uneven distribution of the printing ink provided by the ink metering system occurs in a rotary printing machine printing in an offset printing process, in particular on the surfaces of rollers arranged in the inking unit and on the at least one printing forme arranged on a printing unit cylinder designed as a forme cylinder and on the lateral surface of another one acting as a transfer cylinder that interacts with the forme cylinder trained printing unit cylinder.

In a printing press, along the transport path of the printing material in its transport direction, there are usually several printing units arranged in a row, each with its own inking unit, different printing inks being transferred onto the same printing material transported through the printing press by means of at least two of these printing units. A plurality of printing units, each with their own inking unit, can also be provided on both sides of the transport path of the printing material. A printing machine producing a printed product in multi-color printing can transport the printing material along the transport path, e.g. B. with the inks cyan, magenta, yellow and black. The inking unit of each printing unit is z. B. designed as a roller inking unit, z. B. as a vibrator inking unit or as a film inking unit, these types of inking unit are known to those skilled in the art. The color dosing system, e.g. B. an ink fountain, which supplies the inking unit in question with ink, z. B. an ink ductor rotatable about its longitudinal axis and at least one dosing element; preferably, transverse to the transport direction of the printing material, there are several ink metering elements or metering elements that can be adjusted in zones and controlled in particular by means of an adjusting element. B. as in a distance range of a few tenths of a millimeter to the ink ductor variably arranged ink blades are formed. At least one belonging to the inking unit transfers the inking roller provided by the inking, z. B. in the zones of the ink metering system arranged transversely to the transport direction of the printing material, in particular differently metered ink onto the at least one printing forme, the e.g. B. is arranged on the forme cylinder assigned to this inking unit.

As mentioned, in order to convert the printing press from a first printing process currently running in the printing press to a subsequent second printing process, it is necessary to adjust the distribution of the distribution from one inking unit to the substrate to be printed in the printing press during the execution of the first printing process along the transport path ink to be transferred. The following procedures are known from practice for carrying out this conversion, provided that the relevant inking unit of the printing press is to transfer the same printing ink to the printing material in the subsequent second printing process as in the first printing process:
After the end of the first printing process currently running in the printing press, at least individual rollers, preferably all rollers of the relevant inking unit, are washed and thus freed of residual ink, ie ink left over from the first printing process. After this washing process, the inking unit in question is adjusted to metering and transporting the printing ink required to carry out the subsequent second printing process. This procedure requires a lot of time and leads to a high consumption of printing ink.

A further procedure consists in turning off an ink supply from the relevant ink metering system to the inking unit or at least interrupting it in the inking unit when a final phase of the first printing process previously executed by the printing press is reached, with the after stopping or interrupting the ink supply in the inking unit amount of ink remaining on the substrate side in the final phase of the printing process previously executed by the printing press, e.g. B. is still transferred to the printing material for a certain time, in particular until the ink remaining in the inking unit from the first printing process is at least almost used up. Such a procedure is e.g. B. from the DE 10 2008 029 998 A1 famous. This empty printing of the inking unit produces waste to a not inconsiderable extent. This procedure is also time-consuming. In addition, the distribution of the printing ink, which originates from the first printing process and is transverse to the transport direction of the printing material, is in principle retained, which can have an unfavorable effect on a proof of the subsequent second printing process.

In a third procedure, the proof of the subsequent second printing process is carried out deliberately with the distribution of the printing ink originating from the first printing process and existing transversely to the transport direction of the printing material, wherein during the proof of the subsequent second printing process the dosage of the z. B. in the respective zones of the ink metering system arranged transversely to the transport direction of the printing material is adapted to the metering required for the execution of the subsequent second printing process. This procedure then leads to difficulties if in a zone or in several zones a surface coverage of the new second printing process to be produced therein is very small in places or completely in comparison to the previous first printing process. In this case, the excess printing ink in the affected zone must be removed completely during the printing process, i. H. the second printing process take place. This can take a long time and result in a not inconsiderable amount of waste.

In some cases, the at least one printing forme arranged on a forme cylinder and the outer surface of the transfer cylinder interacting with this forme cylinder are only printed clean by removing the at least one inking roller belonging to the inking unit from the forme cylinder in question and continuing the first printing process until the printing ink remaining on the at least one printing forme and/or on the lateral surface of the transfer cylinder is at least almost used up during the first printing process. Included the distribution of the printing ink, which originates from the first printing process and is transverse to the transport direction of the printing material, is retained in the inking unit, which can have an unfavorable effect on a proof of the subsequent second printing process.

The procedures described for converting the printing press from a first printing process currently running in the printing press to a subsequent second printing process show that in practice the printing press initially produces a large number of sheets with poor inking before the printing press is ready for continuous printing. in which the printing press produces salable printed copies. Depending on the color profile of the pre-order and/or the method used to set the color zones to their new desired color, z. B. significantly more than 100 waste sheets, sometimes even more than 400 waste sheets are generated. This high number of waste sheets is when using high-priced substrates such. B. in metal printing, in which sheet metal sheets are used as a substrate, very expensive and unacceptable. In this context, high-priced means that each individual unprinted sheet intended as printing material already costs a few euros, so that the usual consumption of a three-digit number of sheets until the sheet-fed printing press is ready for production is an expensive affair and has a considerably negative impact, especially for smaller print jobs beats. There is therefore a need for a method which, in particular, brings a sheetfed offset printing press to the desired coloration significantly faster and with considerably less waste than the resulting sheets in a first proof after starting production or in a proof after a job change. When using high-priced substrates, the aim is to save material costs by reducing waste and unproductive machine time and labor costs by shortening the proofing phase. It must be taken into account that an inking unit with rollers cannot react spontaneously or erratically with regard to the amount of printing ink transported to the printing material, but always takes a certain amount of time to adapt the amount of printing ink required on the printing material to a new desired color profile, starting from a previous color profile. Each sheet-fed offset printing machine thus has a certain time constant for its reaction to a changed setting of ink zone openings on an inking unit, which corresponds to a certain number of sheets, ie printed sheets, transported through this sheet-fed offset printing machine. Color density values, which are detected on a printed sheet inked with this changed setting, typically react to a changed setting of ink zone openings on an inking unit in the form of an exponential function. Up to now, 100 to 150 printed sheets have usually been printed in a sheet-fed offset printing press until, after a changed setting of ink zone openings on an inking unit, new color density values are set stably within previously defined permissible tolerance limits on printed sheets inked with this changed setting. If several cycles are required, each with a changed setting of ink zone openings on an inking unit, until the desired desired inking is set stably, the need for sheets previously produced as waste quickly adds up to several hundred printed sheets, which is extremely disadvantageous.

the 1 shows an example of a section of a sheet-fed offset printing press 01, shown only schematically, with several, e.g. B. four in the transport direction T of a printed sheet 02, in particular a z. g. as a sheet metal plate, printing units 03 arranged in a row, the printed sheets 02 being guided one after the other along a transport path through this sheet-fed offset printing press 01. Each of these printing units 03 has an inking unit 04. The respective inking unit 04 has, among other things, a z. B. an ink fountain 06 and an ink ductor 07 having an ink metering system on and in a roller train transporting ink, e.g. B. at least one ink transfer roller 08, possibly an ink lifter 14 and at least one, preferably several, z. B. two inking rollers 09, which are each employed on a forme cylinder 11 of the printing unit 03 or at least are adjustable, with this forme cylinder 11 rolling on a transfer cylinder 12 at least during a printing process, with the transfer cylinder 12 in turn being adjusted against an impression cylinder 13, with the printed sheet 02 passing through a gap formed between the transfer cylinder 12 and the impression cylinder 13. The other printing units 03 are constructed accordingly. A different ink can be transferred to the same printed sheet 02 in each of the printing units 03. The relevant inking unit 04 providing the relevant printing ink has a plurality of ink zones arranged in a row transversely to the transport path of the printed sheets 02, with each of these ink zones having an ink metering element set or at least adjustable by a control unit 16 or regulating device 16 for metering the ink in the relevant ink zone onto the printed sheets 02 the amount of printing ink to be applied is arranged. The respective ink dosing system, ie its dosing organs or ink dosing elements and/or its ink ductor 07, is e.g. B. via a communication network 22, at least in terms of data technology, to the control unit 16 or control device 16, with at least one control command originating from this control unit 16 or control device 16 by means of the metering elements or ink metering elements and/or the ink ductor 07 controlling the ink supply to the relevant inking unit 04 with regard to the quantity of printing ink to be fed to the relevant printed sheet 02 can be adjusted in zones.

At least one detection device 17 is preferably located inside sheet-fed offset printing press 01, in particular in or on the last printing unit 03 that prints on the relevant printed sheet(s) 02. During production of this sheetfed offset printing press 01, the relevant detection device 17 detects at least one color density, e.g. B. densitometrically and forwards their respective at least one measured value as a color density value z. B. likewise via the communication network 22 of the control device 16. Alternatively or in addition to detecting the color density be provided that the at least one detection device 17 records a colorimetric value of at least one print image generated on the printed sheet 02, e.g. B. detected spectrophotometrically. Moreover, the detection device 17 or one of the detection devices 17 z. B. be designed as an inline inspection system, wherein the relevant detection device 17 z. B. at least one camera, in particular an electronic, preferably video-optical camera, with which the relevant detection device 17 of the printed image generated on the printed sheet 02 by a photographic image z. B. captures a sequence of images. From the recorded image, ie the captured image, the control unit 16 or control device 16 can, for. B. the respective color density and / or at least one colorimetric value, preferably of all the printing inks involved in the structure of the print image in question, e.g. B. be determined by separation. It can e.g. B. be provided that several printing units 03 each at least one z. B. for a specific ink optimized detection device 17 is assigned. The detection device 17 is arranged in the transport direction T of the printed sheets 02 at the output of the respective printing unit 03. The detection device 17 detects z. B. the color density and/or at least one colorimetric value directly in the print image in question or in a color measurement strip formed on the printed sheet 02 in question, with several color measurement fields preferably being arranged side by side or in a row in the color measurement strip in question.

The measured value recorded by the relevant recording device 17 forms an actual value for a z. B. surface coverage of at least one printing ink transferred to the printed sheet 02 in question, which can be determined based on its color density. The concept of area coverage refers to a z. B. percentage of coverage of the printing material with at least one of the printing ink applied to this printing material in the printing process, with the indication of area coverage being based on a total area of the printed image or on a partial area thereof, e.g. B. can be related to only a single zone running through the printed image in the form of a strip. The attitude of Area coverage takes place in particular with reference to several different sub-areas of the same printed image, preferably arranged in parallel strips, the associated area coverage being set for several, in particular for each of these sub-areas. The control unit 16 or regulating device 16 is connected in terms of data technology to at least one memory device 18 and, if appropriate, also to an operating device 19, with at least one target value for the area coverage and/or the color density and/or the at least one colorimetric value being stored in the memory device 18 , wherein the respective actual value and target value of the area coverage and/or the color density and/or the at least one colorimetric value each relate to the same total area or partial area of the print image in question. Operating device 19 is used to manually input values and/or control commands to control unit 16 or regulating device 16.

The control unit 16 or control device 16, the memory device 18 and the computing unit 19 can be formed in the same assembly, which is in the 1 is indicated by a dashed border, this assembly can be referred to as a color controller 24. This assembly or at least individual of its components can be connected in terms of data technology to a control station 21 belonging to the sheetfed offset printing press 01, ie to a higher-level control unit, or can be designed or arranged to be integrated in the control station 21. With the control station 21 z. B. a display device 23 is connected in terms of data technology, on which at least one image of one of the printed sheets 02 inked in the sheet-fed offset printing press 01, captured by the relevant capture device 17, is displayed.

2 illustrates the conversion of the sheet-fed offset printing press 01 from a printing process currently running in this printing press to a subsequent printing process, with the 2 the print image in question on a print sheet 02 of a currently running print process (job A) and in the right-hand column of the 2 the corresponding printed image on a printed sheet 02 of a new one subsequent printing process (order B) is shown. This is how it shows 2 the initial situation and, in comparison, the desired new situation.

A method for setting an ink profile in a sheet-fed offset printing press 01 will now be described below, with which the sheet-fed offset printing press 01 can be switched from a printing process currently running in this printing press to a subsequent printing process, particularly when using high-priced printing materials, e.g. B. of sheet metal, can be changed quickly and inexpensively. In this sheet-fed offset printing press 01, a plurality of printed sheets 02—hereinafter referred to as sheets 02 for short—are guided through this sheet-fed offset printing press one after the other along a transport path, with these sheets 02 being inked with at least one printing color on the transport path. For inking the sheets 02, the sheetfed offset printing press 01 has at least one inking unit 04 that provides the printing ink in question, each with a plurality of ink zones arranged in a row transversely to the transport path of the sheets 02, with each of these ink zones having an ink metering element set or at least adjustable by a control unit 16 for metering the in the amount of printing ink to be applied to the sheet 02 in the relevant ink zone. In doing so, the control unit 16 sets the color profile that applies to this inking unit 04 by adjusting the respective ink metering elements of the relevant inking unit 04. The setting of the respective ink metering elements of the inking unit 04 in question is carried out with the aim that the inking unit 04 in question inks the sheets 02 with a desired inking in a production run of the sheet-fed offset printing press 01. To achieve this goal, control unit 16 iteratively sets the respective color profile applicable to the inking unit 04 in question for its target inking based on color density values and/or colorimetric values recorded on several of these sheets 02 and based on a recorded image of a print image applied to the respective sheet 02 a. The respective color density values and/or the respective colorimetric values and also the respective image of the print image in question applied to the respective sheet are each with at least a detection device 17 located in sheet-fed offset printing press 01 and connected at least in terms of data technology to control unit 16.

The setting of the respective color profile applicable to the relevant inking unit 04 for its desired inking is now carried out in the following process steps:
Until the start of production of salable printed sheets 02 on this sheetfed offset printing press 01, several packs of sheets 02 made up of different quantities of waste sheets and/or good sheets are guided in succession along the transport path through this sheetfed offset printing press 01. In this case, pre-printed sheets 02 are used as waste sheets, each with a print image from a previous print job that deviates from the continuous print of sheet-fed offset printing press 01, and unprinted sheets 02 are used as good sheets.

At least the following packs of sheets 02 are then fed one after the other through this sheetfed offset printing press 01, with one metal plate preferably being used as the waste sheet and/or as the good sheet: a) a first pack of sheets 02 consisting of a plurality of waste sheets, b) a second packet consisting of several good sheets, and c) at least one third packet of sheets 02, each with several waste sheets and with at least one good sheet each. The waste sheets of the first bundle and the good sheet(s) of the second bundle are each inked according to the color profile that does not correspond to the target inking, from which control unit 16 used when setting the color profile of the at least one inking unit 04 when converting, e.g. B. after a job change or when the sheetfed offset printing press 01 is printed, i.e. with a color profile which z. B. corresponds to the inking of sheet 02 of a print job that preceded the print job currently to be set. While said packages of sheets 02 one after the other through the sheet-fed offset printing machine 01, the control unit 16 recognizes the good sheets of the second pack either as a result of a z. B. by an operator of the sheet-fed offset printing press 01 made manual input on the operating device 19 data-technically connected to the control unit 16 or, in a higher technical development stage, in each case automatically as a good sheet. With the detection of the good sheet, the control unit 16 determines a respective position of a plurality of color measuring fields, with each position of these color measuring fields being arranged in one of the ink zones of the relevant inking unit 04. Following the second bundle of sheets 02 fed through the sheet-fed offset printing press 01, the control unit 16 uses the relevant recording device 17 to record the respective color density values and/or colorimetric values of the other sheets 02 fed through this sheet-fed offset printing machine 01 at the respective specified positions of the color measuring patches.

In addition, the control unit 16 uses the relevant detection device 17 to capture an image of the print image applied to the respective sheet 02 from the sheets 02 fed through the sheet-fed offset printing press 01 at the latest at the beginning of the sheets 02 of the second bundle. In addition, the control unit 16 stores a master image upon detection of the good sheet(s) in the second bundle, the master image having at least one contour of the print image to be created on the sheets 02 during continuous printing of the sheet-fed offset printing press 01. The control unit 16 compares the respective images recorded with the relevant recording device 17 of the sheets 02 fed through the sheet-fed offset printing press 01 following the second bundle in each case with the master image, with the control unit 16 checking these additional sheets 02 for the presence of a print image corresponding to the master image checks. The control unit 16 evaluates sheets 02 with a print image that corresponds to the master image as a good sheet and sheet 02 with a print image that does not correspond to the master image as a waste sheet. The control unit 16 then leaves sheets 02 that are classified as waste sheets in the formation of the respective color profile, the set by control unit 16 following the second bundle of sheets 02 fed through sheet-fed offset printing press 01, so that only sheets 02 evaluated as good sheets are used to form the respective new color profile to be set. Accordingly, starting with the sheets 02 of the third pack, the control unit 16 iteratively sets the respective color profile on the relevant inking unit 04 based on the respective color density values and/or colorimetric values recorded from good sheets until it matches the respective color profile applicable for the target inking.

Provision is preferably made for the control unit 16 to store the respective image of the print image in question from the good sheets of the second packet and to display it on the display device 23 connected to the control unit 16 .

In a preferred embodiment, the control unit 16 determines a mean value from a number of color density values and/or colorimetric values recorded with the relevant detection device 17 in the same positions of the respective good sheets of the third bundle and uses these mean values to set the respective color profile.

The master image can be created by the control unit 16 in such a way that the control unit 16 reduces the resolution, given by its number of pixels, of the relevant originally recorded image of the good sheet or sheets of the second packet and uses the remaining number of pixels as an image signature representing the master image, wherein the control unit uses the image signature representing the master image to check the presence of a print image corresponding to this master image on sheets 02 fed along the transport path through the sheet-fed offset printing press 01 after the master image has been created.

In the event that a detection device 17 having a plurality of color channels is used to capture the respective image of the print image in question applied to the respective sheet 02, the control unit 16 forms the respective image signature of the master image, e.g. B. separately for each color channel of the detection device 17 and uses the color channel formed image signature of the master image to check the presence of a print image corresponding to this master image. In principle, the master image can be formed from the respective image of the good sheet or sheets of the second pack.

Provision can also be made for the control unit 16 to set an axial register and/or a circumferential register and/or a color register after the master image has been formed for sheets 02 subsequently fed through this sheet-fed offset printing press 01. When the conversion or the proofing of the sheetfed offset printing press 01 has taken place according to the method described above, the control unit 16 i. i.e. R. enters the respective color profile, which is set at the end of the last third pack of sheets 02, on the relevant inking unit 04 as the color profile that applies to the production run.

In the method described here for setting at least one color profile during the changeover or during proofing of sheetfed offset printing press 01, typically 40 to 50 waste sheets are used for the first pack. At least these waste sheets of the first pack form so-called pre-run waste for the basic inking of the sheets 02 after the respective printing ink has entered the relevant inking unit 04. For the third packs, e.g. B. 10 to 15 sheets 02 are used, with the control unit 16 only using the sheets recognized as good sheets in each of these third packages to improve the respective color profile, until the achieved inking of the sheets 02 corresponds to the respective color profile applicable to the desired inking within previously defined permissible tolerance limits. The color profile applicable to the target inking is accordingly set and/or adjusted step by step by the control unit 16 on the basis of the detected good sheets serving as support points.

The method proposed here takes into account, on the one hand, that the color density values detected as a reaction to a changed setting of ink zone openings on an inking unit 04 on a sheet 02 inked in sheetfed offset printing press 01 with this changed setting cannot change abruptly or suddenly, but that these color density values only change after a specified time, i. H. reach a new stable state after a certain machine running time. On the other hand, the method proposed here succeeds in setting the color profile applicable for the target inking with only the smallest possible number of high-priced sheets 02.

The proposed method for setting a color profile in a sheet-fed offset printing press 01 uses pre-printed waste sheets and unprinted good sheets when converting after a job change or when making a proof on the sheet-fed offset printing press 01 in question, with at least one good sheet being printed through repeatedly, i.e. in the form of a plurality of consecutive packs, in each case after a number of waste sheets the sheet-fed offset printing press 01 is guided and the waste sheets and good sheets are each inked, in particular by means of at least one inking unit 04 each having a plurality of ink zones, with the inked good sheets in the sheet-fed offset printing press 01 owing to a z. B. by an operator of the sheet-fed offset printing press 01 manual input on an operating device 19 of the relevant sheet-fed offset printing press 01 or in each case automatically, e.g. B. by means of an image recognition as such, i.e. as a good sheet, and the setting of the color profile by means of an on the relevant inking unit 04 acting color controller 24 after a detection and evaluation of the respective inking alone, ie only the recognized good sheets. Further details of this method have been previously described, e.g. B. that the recording of the respective inking of the waste sheets and good sheets in particular inline, ie in the relevant sheet-fed offset printing press 01 with a z. g. as a camera, and/or that the automatic recognition of the good sheets takes place by means of image recognition and/or that the respective coloring of the recognized good sheets is evaluated using color density values and/or colorimetric values recorded on these good sheets.

3 once again illustrates the chronological sequence of the proposed method for setting a color profile in a sheetfed offset printing press 01 to be set for a new print job via a timeline t running from left to right. It is assumed that at a point in time t0 the conversion of the relevant sheetfed offset printing press 01 begins after a job change or the proofing of a new print job.

The proposed method starts with the fact that z. B. Waste sheets that are provided on a feeder of sheet-fed offset printing press 01 and are already provided with a printed image from at least one previous printing process, i.e. waste sheets that are printed and not intended for sale, are fed through sheet-fed offset printing press 01 and inked by the at least one inking unit 04 of this sheet-fed offset printing press 01 will. This is a first packet P1 of sheets 02 with z. B. 40 to 50 waste sheets, which are fed through this sheet-fed offset printing press 01 one after the other. At time t0, a color profile that no longer corresponds to the previous print job, but in any case does not yet correspond to the target inking of the new print job, is set on the relevant inking units 04. During the phase of the sheet-fed offset printing press 01 inking the first packet P1 of sheets 02, an inflow of printing ink to the respective inking unit 04 is generally not reduced or even stopped.

At time t1, all waste sheets of the first pack P1 of sheets 02 have been fed through sheet-fed offset printing press 01. This ends the phase of sheet-fed offset printing press 01 inking the first pack P1 of sheets 02. From time t1, at least one unprinted good sheet is printed as a second packet P2 of sheets 02, e.g. B. at the feeder of the sheet-fed offset printing press 01 and then guided to its inking by the sheet-fed offset printing press 01. The good sheet(s) are recognized as such either as a result of a manual entry made by an operator of the sheet-fed offset printing press 01 on an operating device 19 that is at least technically connected to this sheet-fed offset printing press 01, or in each case automatically. With the detection of the good sheets of the second bundle P2, with reference to the sheets 02 of the new print job to be processed, a respective position of a plurality of color measurement patches is also determined, at which, in the case of further sheets 02 fed through the sheet-fed offset printing press 01, a Control unit 16 of this sheetfed offset printing press 01, whose respective color density values and/or colorimetric values are recorded. From point in time t1 at the latest, an image of the print image applied to the respective sheet 02 is captured with the aforementioned or another capture device 17 from the sheets 02 of the second bundle P2 fed through this sheet-fed offset printing machine 01 and from all other sheets 02 fed through the sheet-fed offset printing machine 01. With the recognition of the good sheets of the second bundle P2, a master image is also stored in a memory device 18 of control unit 16, the master image having at least one contour of the print image to be created on sheet 02 in continuous printing of sheet-fed offset printing press 01 in accordance with the new print job to be processed. From the point in time t2, the control unit 16 compares the images of the respective images recorded with the appertaining recording device 17 following the second packet P2 in each case by the sheet-fed offset printing machine 01, each with the stored master image, with control unit 16 checking these additional sheets 02 for the presence of a print image corresponding to the master image. In this check, control unit 16 evaluates sheets 02 with a print image that corresponds to the master image as a good sheet and sheets 02 with a print image that does not correspond to the master image as waste sheets. At time t2, control unit 16 also begins iteratively setting the respective color profile on the relevant inking unit 04 based on the respective color density values and/or colorimetric values recorded from good sheets until it matches the respective color profile applicable for the target inking, with from time t2 several packs P3n, each consisting of several waste sheets and at least one good sheet each, are fed through this sheet-fed offset printing press 01. When forming the respective color profile, which is set by control unit 16 in each case following the second pack P2 of sheets 02 fed through sheet-fed offset printing press 01, i.e. from point in time t2, control unit 16 disregards sheets 02 that it assesses as waste sheets. Only the sheets 02 recognized as good sheets by the control unit 16 serve as support points for the step-by-step setting of the respective color profile applicable to the target inking.

After all sheets 02 of the third bundles P3n have been fed through the sheet-fed offset printing press 01 one after the other and the respective color profile has been set to match the color profile applicable to the target inking more and more closely on the basis of the sheets 02 identified as good sheets, at time t3 the sheetfed offset printing machine 01 and the control unit 16 switches and/or the color controller 24 into a corresponding operating mode.

Reference List

01

sheetfed press

02

printed sheet, sheet

03

printing unit

04

inking

05

-

06

color box

07

ink fountain pen

08

ink transfer roller

09

inking roller

10

-

11

form cylinder

12

transfer cylinder

13

Impression cylinder

14

color lifter

15

-

16

Control unit, control device

17

detection device

18

storage facility

19

operating device

20

-

21

control station

22

communication network

23

display device

24

color slider

P1

first package of sheets (02)

p2

second pack of arches (02)

P3n

third pack of arches (02)

t

time beam

t0

time

t1

time

t2

time

t3

time

T

transport direction

Claims (11)

1. Method for setting a colour profile in a sheet-fed offset printing press (01), wherein a plurality of sheets (02) are guided one after the other along a transport path through this sheet-fed offset printing press (01), wherein these sheets (02) on the transport path are inked with at least one printing ink, wherein the sheet-fed offset printing press (01) comprises at least one inking unit (04), which provides the relevant printing ink and has in each case a plurality of ink zones arranged in a row transversely to the transport path of the sheets (02), wherein arranged in each of these ink zones is an ink metering element for metering the amount of printing ink to be applied to the sheets (02) in the relevant ink zone, which ink metering element is or at least can be adjusted by a control unit (16), wherein, by adjusting the respective ink metering elements of the relevant inking unit (04), the control unit (16) sets the colour profile that applies to this inking unit (04), wherein the relevant inking unit (04) in each case inks the sheets (02) with a desired inking during a production run of the sheet-fed offset printing press (01), wherein the control unit (16) in each case iteratively adjusts the respective colour profile that applies to the relevant inking unit (04) for its desired inking on the basis of ink density values and/or colorimetric values acquired from a plurality of these sheets (02) and on the basis of an acquired image of a printed image applied to the respective sheet (02), wherein the respective ink density values and/or the respective colorimetric values and also the respective image of the relevant printed image applied to the respective sheet (02) are acquired in each case by at least one acquisition device (17), which is connected to the control unit (16) for data purposes and is directed towards the transport path of the respective sheets (02), characterized

   a. in that, up until the start of the production run of this sheet-fed offset printing press (01), a plurality of batches of sheets (02) composed of different quantities of waste sheets and/or good sheets are guided one after the other along the transport path through this sheet-fed offset printing press (01), wherein previously printed sheets (02), which each have a printed image from a previous print job that differs from the printed image in the production run of the sheet-fed offset printing press (01), are used as waste sheets in each case, and unprinted sheets (02) are used as good sheets in each case, wherein at least the following batches of sheets (02) are guided one after the other through this sheet-fed offset printing press (01) :

   a.a. a first batch of sheets (02) consisting of a plurality of waste sheets,

   a.b. a second batch consisting of a plurality of good sheets,

   a.c. at least one third batch of sheets (02) comprising in each case a plurality of waste sheets and in each case at least one good sheet,

   a.d. wherein the waste sheets of the first batch and the good sheets of the second batch are in each case inked in accordance with the colour profile not corresponding to the desired inking, from which colour profile the control unit (16) starts in each case when setting the colour profile of the at least one inking unit (04),

   b. in that the control unit (16) recognizes the good sheets of the second batch as good sheets either as a result of a manual input at an operating device (19), which is connected to the control unit (16) for data purposes, or automatically, and upon recognizing the good sheets defines a respective position of a plurality of colour measuring fields, wherein each position of these colour measuring fields is arranged in each case in one of the ink zones of the relevant inking unit (04),

   c. in that, subsequent to the second batch of sheets (02) guided through the sheet-fed offset printing press (01), and while further sheets (02) are guided through the sheet-fed offset printing press (01), the control unit (16) acquires the respective ink density values and/or colorimetric values, by means of the relevant acquisition device (17), at the respective defined positions of the colour measuring fields,

   d. in that, at the latest at the start of the sheets (02) of the second batch, the control unit (16), by means of the relevant acquisition device (17), acquires from the sheets (02) guided through the sheet-fed offset printing press (01) in each case an image of the printed image applied to the respective sheet (02),

   e. in that, upon recognizing the good sheets of the second batch, the control unit (16) stores a master image, wherein the master image comprises at least a contour of the printed image to be created on the sheets (02) during the production run of the sheet-fed offset printing press (01),

   f. in that the control unit (16) compares against the master image in each case the respective images acquired by the relevant acquisition device (17) from the sheets (02) respectively guided through the sheet-fed offset printing press (01) subsequent to the second batch, wherein the control unit (16) checks these further sheets (02) for the presence of a printed image corresponding to the master image, wherein the control unit (16) classifies sheets (02) that have a printed image corresponding to the master image as a good sheet and classifies sheets (02) that have a printed image not corresponding to the master image as a waste sheet, wherein the control unit (16) disregards sheets (02) classified as waste sheets when forming the respective colour profile that is set by the control unit (16) in each case subsequent to the second batch of sheets (02) guided through the sheet-fed offset printing press (01) ,

   g. in that the control unit (16), starting with the sheets (02) of the third batch, iteratively adjusts the respective colour profile on the relevant inking unit (04) on the basis of the respective ink density values and/or colorimetric values acquired in each case from good sheets, until the colour profile matches the respective colour profile that applies to the desired inking.
2. Method according to claim 1, characterized in that the control unit (16) stores the respective image of the relevant printed image at least from at least one or more good sheets of the second batch and displays it on a display device (23) connected to the control unit (16).
3. Method according to claim 1 or 2, characterized in that, from a plurality of ink density values and/or colorimetric values acquired in each case by means of the relevant acquisition device (17) in each case at identical positions of the respective good sheets of the third batch, the control unit (16) determines a mean value in each case and uses these mean values to set the respective colour profile.
4. Method according to claim 1 or 2 or 3, characterized in that the master image is created by the control unit (16) in such a way that the control unit (16) reduces the resolution of the relevant originally acquired image of the good sheets of the second batch, which resolution is defined by the amount of pixels, and uses the remaining amount of pixels as an image signature representing the master image, wherein the control unit (16) uses the image signature representing the master image to check for the presence of a printed image corresponding to this master image on sheets (02) guided along the transport path through the sheet-fed offset printing press (01) following the creation of the master image.
5. Method according to claim 4, characterized in that an acquisition device (17) having a plurality of colour channels is used to acquire the respective image of the relevant printed image applied to the respective sheet (02), wherein the control unit (16) forms the respective image signature of the master image separately for each colour channel of the acquisition device (17) and uses it to check for the presence of a printed image corresponding to this master image.
6. Method according to claim 1 or 2 or 3 or 4 or 5, characterized in that the master image is formed from the respective image of the good sheets of the second batch.
7. Method according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that, after forming the master image for sheets (02) subsequently guided through this sheet-fed offset printing press (01), the control unit (16) sets an axial register and/or a circumferential register and/or a colour register.
8. Method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that the control unit (16) sets on the relevant inking unit (04), as the colour profile that applies to the production run, the respective colour profile that is set at the end of the last third batch of sheets (02).
9. Method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that 40 to 50 waste sheets are used for the first batch.
10. Method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that in each case 10 to 15 sheets (02) are used for the third batches.
11. Method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that in each case a sheet-metal plate is used as the waste sheet(s) and/or good sheet(s).

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