METHOD OF PRINTING AT LEAST TWO PRINT JOBS ON ONE PRINTING MACHINE

Abstract

A method includes the steps of: a) printing a first print job on a printing machine using a printing fluid, a substrate, a specified ICC profile, and a first machine setting; b) preparing the printing operation of a second print job involving a change of the printing fluid and/or of the substrate; and c) printing the second print job using a second combination of printing fluid and substrate. Step b) includes: b1) printing a test print having a plurality of test fields; b2) recording the test fields; b3) computationally determining and saving a quality value based on the test fields; b4) determining and saving an adjustment value for a machine setting; and b5) selectively changing a printing machine setting from the first machine setting to a second machine setting using the adjustment value or keeping the first printing machine setting, and the making a choice based on a quality value.

Claims

1. A method for printing at least two print jobs on one printing machine, which comprises the steps of: a) printing a first print job on the printing machine using a first combination of a printing fluid and a substrate, a specified international color consortium (ICC) profile, and a first machine setting of the printing machine; b) preparing a printing operation for a second print job involving a change of the printing fluid and/or of the substrate to a second combination of the printing fluid and the substrate, wherein step b) includes the sub steps of: b1) printing a test print on the printing machine, the test print including a plurality of test fields, using the second combination of the printing fluid and the substrate, the specified ICC profile, and the first machine setting; b2) recording all or at least a selection of the test fields of the test print using a recording device; b3) computationally determining and saving a quality value on a basis of the test fields recorded; b4) computationally determining and saving at least one adjustment value for a machine setting; and b5) selectively changing a printing machine setting from the first machine setting to a second machine setting using the at least one adjustment value or selectively keeping the first printing machine setting, and making a choice of the printing machine setting in dependence on the quality value; and c) printing the second print job on the printing machine using the second combination of the printing fluid and the substrate, the specified ICC profile, and in accordance with the choice made in step b), the first machine setting or the second machine setting.

2. The method according to claim 1, wherein the printing fluid is selected from the group consisting of: a first printing fluid being a first offset printing ink or a first set of offset printing inks, and a second printing fluid being a second offset printing ink or a second set of offset printing inks.

3. The method according to claim 2, wherein the second machine setting comprises changing a volume of at least one of the first or second offset printing inks or a volume of at least one printing ink of at least one of the first or second set of printing inks compared to the first machine setting, wherein the changing step involves using the at least one adjustment value.

4. The method according to claim 1, wherein the substep b5) further comprises creating a second printing forme or a set of second printing formes.

5. The method according to claim 4, wherein the second printing forme or the set of second printing formes is created such that a modified volume of the printing fluid is applied to the substrate.

6. The method according to claim 5, wherein the creating step comprises exposing the second printing forme using the at least one adjustment value or a value corresponding to or calculated from the at least one adjustment value.

7. The method according to claim 4, wherein the second printing forme or the set of second printing formes is used in the step c).

8. The method according to claim 1, wherein the printing fluid is selected from the group consisting of: a first printing fluid being a first inkjet printing ink or a first set of inkjet printing inks, and a second printing fluid being a second inkjet printing ink or a second set of inkjet printing inks.

9. The method according to claim 8, wherein the second machine setting comprises a change of a volume of at least one of the first and second inkjet printing inks or of a volume of at least one inkjet printing ink of the first or second set of inkjet printing inks compared to the first machine setting, the change involving the at least one adjustment value.

10. The method according to claim 9, wherein the substep b5) includes changing a calibration of printing heads of the printing machine.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] FIG. 1 illustrates details of a preferred exemplary embodiment of a method of printing at least two print jobs on a printing machine, FIG. 1 illustrates steps a to c;

[0045] FIG. 2 illustrates steps b1 to b5 and optionally to steps b5a or b5b of the method of printing at least two print jobs;

[0046] FIG. 3 is an illustration of a preferred exemplary embodiment of the printing machine; and

[0047] FIG. 4 is a diagram illustrating a color gradation in what is referred to as the a-b plane.

DETAILED DESCRIPTION OF THE INVENTION

[0048] In the figures, corresponding features have the same reference symbols. Repetitive reference symbols have sometimes been left out for reasons of visibility.

[0049] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown in step a) printing (a) of a first print job 2 on a printing machine 1 (cf. FIG. 3) using a first combination K1 of printing fluid and printing substrate, a specified ICC profile ICC, and a first machine setting M1 of the printing machine. By way of example, the printing fluid is a first printing fluid F1. In the illustrated example, the substrate is a first substrate S1, for instance paper. In the illustrated example, the setting is K1 (i.e. F1 and S1), ICC and M1. The combination K1 may also comprise a halftone.

[0050] Step b): preparing (b) the printing operation of a second print job 4 involving a change W of the printing fluid and/or of the substrate (and/or the halftone) to a second combination K2 of printing fluid and substrate (and/or halftone). In the illustrated example, the first printing fluid F1 remains the same and the substrate changes to a second substrate S2, i.e. a different paper. Alternatively, other changes may be made, for instance from F1 to F2 while S1 remains unchanged or from F1 to F2 and from S1 to S2. Even more than just two printing fluids or substrates may be available for the change W: i.e. a number n of different printing fluids and a number m of different substrates (with n>1 and m>1).

[0051] Step b comprises step parts b1 to b5, optionally to b5a or b5b.

[0052] Step part b1): printing b1 a test print 4 on the printing machine 1, the test print 4 including a plurality of test fields 5, using the second combination K2 of printing fluid and substrate, the specified ICC profile ICC, and the first machine setting M1. The test print 4 may comprise a media wedge 11 such as a Fogra media wedge.

[0053] Step part b2): recording b2 all or at least a selection of the test fields 5 (and/or of the media wedge 11) of the test print 4 using a device for recording 6 such as a camera or a spectrometer. The result of the recording, e.g. a camera image, is preferably transmitted to a digital computer 7.

[0054] Step part b3): computationally determining and saving b3 a quality value GW on the basis of the recorded test fields 5 (and/or of the recorded media wedge 11). This may be done by means of the digital computer 7 (or, alternatively: by means of a further digital computer).

[0055] Step part b4): computationally determining and saving b4 at least one adjustment value EW for a machine setting; in the illustrated example, it is for a second machine setting M2 (cf. step part b5). This may be done by means of the digital computer 7 (or, alternatively: by means of the further digital computer).

[0056] Step part b5): selectively changing b5 a setting of the printing machine 1 from the first machine setting M1 to a second machine setting M2 using the adjustment value EW or selectively keeping b5 the first machine setting M1 of the printing machine 1; the choice is made as a function of the quality value GW. This may be done by means of the digital computer 7 (or, alternatively, by means of the/a further digital computer). In the illustrated example, the machine setting is changed from setting M1 to setting M2 as a function of the quality value GW. More than two machine settings may be available for the change: i.e. a number k of different machine settings (with k>1). For example, the change may be made if the quality value exceeds a specified threshold.

[0057] The second machine setting M2 may comprise changing the volume of the printing ink or the volume of at least one printing ink of the set of printing inks compared to the first machine setting M1 and the change may be made using the adjustment value EW. The adjustment value may for instance be the value of the change (i.e. relative) or the new value to be set (absolute).

[0058] Optional step part b5a (in the case of a printing machine using printing masters, for instance in offset printing): creating a second printing forme 8 or a set of second printing formes 8. The second printing forme or set of second printing formes may be created in such a way that it transfers the modified volume of printing ink to the substrate. The creation may comprise exposure in a platesetter 9 using the adjustment value EW or a value corresponding to the latter.

[0059] Optional step part b5b (in the case of a printing machine using printing heads, for example in inkjet printing): Changing the calibration of the printing heads 10 in the printing machine 1.

[0060] Step c): Printing c the second print job 3 on the printing machine 1 using the second combination K2 of printing fluid and substrate, the specified ICC profile, and—depending on what was chosen in step b)—the first machine setting M1 or the second machine setting M2. In the illustrated example, the setting is K2 (i.e. F1 and S2), ICC, and M2. The combination K2 may also comprise a halftone, in particular a modified halftone.

[0061] FIG. 3 illustrates a device implementing a preferred exemplary embodiment of the method of the invention. What is used is a printing machine 1—either a printing press (shown at the bottom of FIG. 3, e.g. an offset printing press) using printing formes 8; or a printing machine with printing heads 10 (shown at the top of FIG. 3; for instance an ink printing machine). The printing machine is controlled by the digital computer 7 or a further digital computer. (As indicated by the illustrated arrow) the printing machine conveys and processes substrates 12. In the illustrated example, the substrates 12 are sheets taken from a stack; alternatively, the substrate may be a web on a reel.

[0062] FIG. 4 is a diagram 13 which illustrates the color gradation in what is referred to as the a-b plane. The following colors, i.e. their approximate locations in the diagram are shown by way of example: cyan 14, magenta 15, blue 16, yellow 17, green 18, and orange 19.

[0063] Diagram 13 further includes graphs 20 to 25 for specific colors. The thickness of the layer of the ink of the respective color increases along the associated graph in an outward direction from the center. The following graphs are shown: a cyan graph 20, a cyan graph* 21, a blue graph 22, a blue graph* 23, a yellow graph 24, and a yellow graph* 25. Graphs 20, 22, and 24 without the asterisk (“*”) apply to the first print job and graphs 21, 23, 25 with the asterisk apply to the second print job. Graphs 21, 23, and 25 may preferably have been created using the analyzed test print, i.e. the test fields and/or media wedge, for instance.

[0064] For example, to find the optimum color target value for a solid cyan area, the cyan graph* 21 is examined to find and then select the location which is closest to the color target value of a solid cyan area on cyan graph 20 (minimum distance deltaE). A definition to determine the distance deltaE may be specified (for instance a mathematical method known for this purpose). The same applies to blue and yellow, and special colors, if they are present.

[0065] The machine may be controlled in a closed control loop in accordance with target value specifications from the ICC profile. Alternatively, a model-based adaptation of the target values to the substrate may be done and the control may be in accordance with these target values.

[0066] The following is an example of the determination of the adjustment/calibration (for instance on the basis of a Fogra media wedge):

measuring of an individual color halftone and/or of multicolor halftones;
calculating an optimized “characteristic printing forme curve” (if printing formes are used) or “characteristic calibration curve” (if printing heads are used) for every measuring field and every color;
optimization, for instance in accordance with one of the following algorithms:
a) averages of the calibration per color;
b) weighted average per color; and
c) minimization of the remaining color deviation deltaE.

[0067] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0068] 1 printing machine [0069] 2 first print job [0070] 3 second print job [0071] 4 test print [0072] 5 plurality of test fields [0073] 6 recording device, in particular camera or spectrometer [0074] 7 digital computer [0075] 8 printing formes [0076] 9 platesetter [0077] 10 printing heads [0078] 11 media wedge [0079] 12 substrate [0080] 13 diagram “color gradation in the a-b plane” [0081] 14 cyan [0082] 15 magenta [0083] 16 blue [0084] 17 yellow [0085] 18 green [0086] 19 orange [0087] 20 “cyan old” graph [0088] 21 “cyan new” graph [0089] 22 “blue old” graph [0090] 23 “blue new” graph [0091] 24 “yellow old” graph [0092] 25 “yellow new” graph [0093] F1 first printing fluid, in particular printing ink [0094] F2 second printing fluid, in particular printing ink [0095] S1 first substrate, in particular sheet [0096] S2 second substrate, in particular sheet [0097] K1 first combination of printing fluid and substrate [0098] W printing fluid and/or substrate change [0099] K2 second combination of printing fluid and substrate [0100] ICC specified ICC profile [0101] M1 first machine setting [0102] M2 second machine setting [0103] GW quality value [0104] EW adjustment value [0105] a printing the first print job [0106] b preparing the second print job [0107] b1 printing the test print [0108] b2 recording all or at least a selection of the test fields [0109] b3 computationally determining and saving a quality value [0110] b4 computationally determining and saving at least one adjustment value [0111] b5 selectively changing or keeping a setting of the printing machine [0112] b5a creating a second printing forme or a set of second printing formes [0113] b5b changing the calibration of the printing heads [0114] C printing the second print job