DE102016221745A1 - Method for operating a multi-color ink printing machine - Google Patents

Abstract

The invention relates to a method for operating a multicolor inkjet printing machine with at least seven printing stations, wherein printheads (1a to 8a) of the printing stations (1 to 7) display an at least four-color printed image (20) on a printing material (11) moved in a transport direction (12). is printed with a predetermined in the transport direction print resolution of at least the Buntanteils of the printed image, wherein three print stations print a first field (21) of the printed image with bright colors of a first color system and half the printing resolution and three other printing stations a complementary to the first field, second field ( 22) of the printed image with chromatic colors of a second color system identical to or different from the first color system and with half the printing resolution, such that the first and the second partial image are complementary to the colored portion of the printed image and at least one further printing station is a third partial image (23) of the print image with black arzer ink and prints at half the print resolution.

Description

The present invention relates to a method of operating a multicolor inkjet printing machine having the features of claim 1.

The invention is in the technical field of the graphic arts industry and in particular in the field of inkjet printing (inkjet). In the known DOD ink-jet printing method (drop-on-demand), a printed image is produced on a printing substrate in that a print head generates the ink image corresponding to the finest ink droplets and transmits them contactlessly onto the printing substrate. The substrate can be made of paper, cardboard or plastic and be curved or web-shaped.

A known under the product name "Primefire" and designed by Heidelberger Druckmaschinen AG inkjet printing machine for industrial production prints paper sheets with water-based inkjet inks. The machine consists of seven consecutive print stations that transfer the colors CMYK (cyan, magenta, yellow and black) and OGV (orange, green, violet) to the paper with fixed printheads.

The EP 373 957 A1 In contrast, describes a printing machine with moving printheads. Industrial production speeds are generally not achieved as a result of the heads moving back and forth. However, the document discloses a way to at least increase the production speed. Instead of printing with the four colors CMYK, it is also possible to print only with black, ie in the configuration KKKK. The production speed can be quadrupled.

Basically, there is a desire on the part of the printing media manufacturers to produce printed products faster and faster, i. To operate printing machines with ever higher production speed. However, there is also a desire to save costs, e.g. already with the purchase of different printing machines for different requirements, but also in their operation.

Against this background, it is an object of the present invention to provide a method improved over the prior art which enables high-quality printed products, i. Produce high-resolution print products at least in the chromatic portion of the print image at high print speeds. Another object is to provide a method which makes it possible to use a printing machine variably, i. to operate in a suitable color configuration depending on the print job.

These objects are achieved by a method according to claim 1. Advantageous and therefore preferred developments of the invention will become apparent from the dependent claims and from the description and the drawings.

The invention relates to a method for operating a multi-color ink printing machine with at least seven printing stations, wherein printheads of the printing stations an at least four-color printed image is printed on a moving in a transport direction substrate with a predetermined direction in the transport printing resolution of at least the Buntanteils of the printed image, wherein three printing stations a print first partial image of the printed image with chromatic colors of a first color system and with half the printing resolution, and three further printing stations print a second partial image of the printed image complementary to the first partial image with chromatic colors of a second color system identical or different to the first color system and with half the printing resolution, in that the first and the second partial image are complementary to the colored portion of the printed image and at least one further printing station is printing a third partial image of the printed image with black ink and with half the printing resolution t.

According to the invention, the chromatic component of the printed image is composed of partial images. Both partial images together result in the desired print resolution. On the other hand, if only one print station is provided for black, the black component is only printed at half the desired print resolution.

A preferred further development of the method according to the invention can be distinguished by the fact that the colored portion of the printed image is constructed for each chromatic color in the transport direction from consecutive print lines and the first field comprises all even-numbered lines of the color portion of the print image and the second field comprises all odd-numbered lines of the chroma component of the printed image. "Even" and "odd" stand here only as a name for alternately consecutive lines. The construction of the print image from complementary sub-images using at least two print heads advantageously allows an increase and a maximum doubling of the production speed.

A preferred embodiment of the method according to the invention may be characterized in that the color component of the printed image is constructed checkerboard-like for each color and that the first partial image comprises a first chessboard half of the color component of the printed image and the second partial image comprises a second chessboard-like half of the multicolor component complementary to the first half of the printed image. Also in this way can the printing speed can be doubled maximally. The checkerboard printing leads advantageously to a "quieter" printed image.

• - C bzw. Cyan, M bzw. Magenta und Y bzw. Gelb, oder
• - O bzw. Orange, G bzw. Grün und V bzw. Violett, oder
• - Y bzw. Gelb, G bzw. Grün und V bzw. Violett, oder
• - F1, F2 und F3, wobei, auf den von den Buntfarben aufgespannten Farbraum bezogen, F1 zwischen Gelb und Magenta, F2 zwischen Gelb und Cyan und F3 zwischen Cyan und Magenta liegen.

A preferred development of the method according to the invention can be distinguished by the fact that the first color system comprises the following chromatic colors:

• C or cyan, M or magenta and Y or yellow, or
• - O or orange, G or green and V or violet, or
• Y or yellow, G or green and V or violet, or
• F1, F2 and F3, where F1 lies between yellow and magenta, F2 between yellow and cyan, and F3 between cyan and magenta relative to the color space defined by the chromatic colors.

• - C bzw. Cyan, M bzw. Magenta und Y bzw. Gelb, oder
• - O bzw. Orange, G bzw. Grün und V bzw. Violett, oder
• - Y bzw. Gelb, G bzw. Grün und V bzw. Violett, oder
• - F4, F5 und F6, wobei, auf den von den Buntfarben aufgespannten Farbraum bezogen, F4 zwischen Gelb und Magenta, F5 zwischen Gelb und Cyan und F6 zwischen Cyan und Magenta liegen.

A preferred development of the method according to the invention can be distinguished by the fact that the second color system comprises the following chromatic colors:

• C or cyan, M or magenta and Y or yellow, or
• - O or orange, G or green and V or violet, or
• Y or yellow, G or green and V or violet, or
• F4, F5 and F6, where F4 lies between yellow and magenta, F5 between yellow and cyan and F6 between cyan and magenta relative to the color space spanned by the chromatic colors.

• - K C M Y C M Y, oder
• - K C M Y Y M C, oder
• - K C M Y O G V, oder
• - K C M Y Y G V, oder
• - K C C M M Y Y, oder
• - K F1 F2 F3 F4 F5 F6.

A preferred development of the method according to the invention can be distinguished by the fact that the printing stations are arranged consecutively in the transport direction in one of the following configurations:

• - KCMYCMY, or
• - KCMYYMC, or
• - KCMYOGV, or
• - KCMYYGV, or
• - KCCMMYY, or
• - K F1 F2 F3 F4 F5 F6.

In the configuration K C M Y O G V, the second group O G V can simulate the first group C M Y, i. C, M and Y are then mixed from the bright colors O, G and V. The print data are processed accordingly in the prepress. A printing machine in the configuration KCMYOGV therefore offers the advantage that the group OGV can be used either to extend the color space (in the production of seven-color printed products) or to double the Print speed (when producing only four-color print products with seven active print stations).

Likewise, in the configuration K C M Y Y G V, the groups C, M and Y can be simulated by Y, G and V. Since yellow, as one of the brightest colors in additive color mixing, is difficult to mix from other colors, the configuration K C M Y Y G V of configuration K C M Y O G V is preferred.

In the configuration K F1 F2 F3 F4 F5 F6, the first group F1, F2 and F3 forms a base of bright colors of a first color system and F4, F5 and F6 form a base of bright colors of a second color system. The color location of F1 can be e.g. close to cyan, corresponding to F2 for magenta, F3 for yellow, F4 for orange, F5 for green and F6 for violet. Alternatively, the chromatic colors F1 to F6 can also occupy other color locations.

• - von K C M Y C M Y nach K C M Y O G V oder umgekehrt, oder
• - von K C M Y Y M C nach K C M Y O G V oder umgekehrt, oder
• - von K C M Y Y G V nach K C M Y O G V oder umgekehrt, oder
• - von K C C M M Y Y nach K C M Y O G V oder umgekehrt,

wobei in der Konfiguration K C M Y O G V ein siebenfarbiges Druckbild mit der halben Druckauflösung gedruckt wird.A preferred embodiment of the method according to the invention can be characterized in that an ink change takes place between two print jobs, wherein the configuration of the print stations changes as follows:

• - from KCMYCMY to KCMYOGV or vice versa, or
• - from KCMYYMC to KCMYOGV or vice versa, or
• - from KCMYYGV to KCMYOGV or vice versa, or
• - from KCCMMYY to KCMYOGV or vice versa,

wherein in the configuration KCMYOGV a seven-color print image is printed at half the print resolution.

The configuration K C M Y C M Y offers the advantage that the group C M Y occurs twice in the same arrangement. The configuration K C M Y Y M C has the advantage that Y and O are both bright colors and therefore a trouble-free ink change to K C M Y O G V is possible with little cleaning effort and detergent consumption. The same applies a fortiori to K C M Y Y G V when changing to K C M Y O G V. The configuration K C C M M Y Y has the advantage that the printing stations are arranged one after the other for the same bright colors.

By the ink change, it is advantageously possible to use a printing machine with seven printing stations in a first mode for the production of seven-color printed products at maximum first production speed v1 and use the same machine in a second mode for the production of four-color printed products at maximum second production speed v2 where v2 = 2 * v1. If desired, ie due to corresponding print jobs, it is possible to switch between "fast" printing of seven colors and "very fast" printing of only four colors.

A preferred development of the method according to the invention can be distinguished by the fact that each printing station at which an ink change takes place comprises a supply module for a first ink, a supply module for a second ink and a supply module for a first cleaning liquid and that between the printing with the first Ink and the printing with the second ink is a cleaning, being switched between the supply modules.

A further development of the method according to the invention can be distinguished by the fact that an eighth printing station prints a fourth partial image of the printed image with black ink and half the printing resolution such that the third and the fourth partial image complement each other to form the black component or the non-colored component of the printed image. In this configuration, the black component (like the colored component) is printed in high resolution. A refinement of the method according to the invention can also be distinguished by the fact that the printing stations are arranged consecutively in the transport direction in the following configuration: K K F1 F2 F3 F4 F5 F6. Advantageously, the two partial images of the black component are printed first here. However, it is preferred to produce the black component with only one printing station, particularly preferably the first printing station, and to generate the colored components with two printing stations each. If a black component in high print resolution is desired, advantageously a fourth subframe complementary to the black, third subframe can also be generated from the bright colors of the first and / or second color system, i. Black or as dark a hue as possible is then mixed from bright colors. The provision of an additional (possibly eighth) printing station can then be avoided with cost advantage.

The invention and its preferred developments are described below with reference to the drawings with reference to a preferred embodiment. For the sake of clarity, corresponding elements in the drawings are provided with the same reference numerals, and reference numerals which merely repeat themselves are omitted in part.

• 1 Druckmaschine zur Durchführung des erfindungsgemäßen Verfahrens;
• 2A Druckbild nach dem Stand der Technik;
• 2B Buntanteil eines erfindungsgemäß zusammengesetzten Druckbilds;
• 2C Buntanteil eines erfindungsgemäß zusammengesetzten Druckbilds;
• 2D Schwarzanteil eines erfindungsgemäß zusammengesetzten Druckbilds;
• 3 Einrichtung für den Tintenwechsel; und
• 4 Farbraum.

Drawings show:

• 1 Printing machine for carrying out the method according to the invention;
• 2A Printed image according to the prior art;
• 2 B Colored portion of a printed image composed according to the invention;
• 2C Colored portion of a printed image composed according to the invention;
• 2D Black portion of a printed image composed according to the invention;
• 3 Device for ink change; and
• 4 Color space.

1 show the 1 shows a sheet-processing ink printing machine 10 for the industrial production of multicolored printed products in the inkjet printing process, which is suitable for carrying out the process according to the invention. The machine includes a stack feeder 13 , a so-called precoat work 14 for the application of a pre-coating, an inkjet printing unit15 for the image-wise printing of the sheets 11 , a coating plant 17 and a stacking boom 19 , The sheets are transported by cylinders through the machine and are preferably made of paper, alternatively made of cardboard. The printing unit comprises seven in the sheet transport direction successively arranged printing stations 1 to 7 for transferring ink drops, preferably the process colors black, cyan, magenta, yellow, orange, green and violet. Each station comprises a substantially transversely directed to the transport direction arrangement of print heads stationary in the printing operation, each with a plurality of individually controllable pressure nozzles for generating the drops ("drop on demand" or DOD). The stations enable page-wide printing of the sheets in so-called single-pass operation, ie the sheets only enter the working area of the stations once. The inks are water-based inks whose droplets react with the precoat to form dots of high dot sharpness and contain pigments as colorants. The dryer 18 is a thermal dryer with infrared emitters, preferably LED spotlights, and serves to evaporate the water from the printed ink or from the substrate. It can also be provided more dryers, for example after the precoat and the paint factory and in the boom. The machine also includes a machine control with a computer and a control program running on the computer, wherein the computer may be part of a control panel, not shown. Also not shown are means for supplying the printing stations with inks and a device for cleaning the printheads.

The printing material is supplied by the investor 13 to the inkjet printing unit 15 guided and lies there on the surface of a cylinder 16 , The cylinder can be powered by a motor 16 ' be driven directly or indirectly via a gearbox with a variable speed.

The printing press in 1 has a configuration A. In this configuration are the seven printing stations 1 to 7 are inked such that inks of the following colors are printed on the substrate in the following order: black, K, cyan, C, magenta, M, yellow, and Y, and cyan, magenta, and yellow again. Configuration A allows the production of a four-color print image. Since two printing stations are provided for each of the three chromatic colors CMY, it is advantageously possible to produce printed images with a predetermined printing resolution and thereby the transport speed of the printing material 11 to increase and maximally double. For example, with printheads 1 A to 7A, which are designed for a print resolution of 1200 dpi, a print image are generated, which has a predetermined print resolution of 1200 dpi in the color component. Compared to a conventional printing machine, which with the same structure 7 Colors prints, so z. B. KCMYOGV, a print image with 1200 dpi in the color component at up to twice the production speed can be generated.

However, in the configuration A, only one print head 1A is available for the black component or the unscented component of the print image. This means that in the above example with the given printing resolution of e.g. Although 1,200 dpi is achieved in the 1,200 dpi color ratio at twice the production speed, the black portion is only printed at 600 dpi. However, the reduced print resolution in the black portion is often not disturbing, because black is often used in pictures only as a contour color and in text portions of printed images is a high print resolution and high area coverage often not required. In addition, black can be compensated by mixing the three colors, but only limited.

1 further shows alternative configurations B through F, in which the illustrated printing press 10 can also be operated. For this purpose, the seven printing stations 1 to 7 each supplied with the appropriate inks or process colors.

The illustrated press may remain in the same configuration across multiple print jobs. On the other hand, it is also possible to transfer the printing press from one configuration to another depending on the print jobs. For this purpose, an ink change on at least one printing station is possibly necessary. One intended for such an ink change means is in 3 shown.

2A shows a printed image, as generated by the prior art. For simplicity, only a color is shown. The printed image 20 is made up of printed lines 20 ' together, which is substantially perpendicular to the transport direction 12 lie. For this purpose, a print head is driven with a printing cycle and thereby line by line on the substrate 11 printed.

A comparison between the 2A and 2 B shows the difference of the invention to the prior art: The printed image 20 in 2 B is made up of a first drawing file 21 or first or even-numbered print lines 25 (which will be printed first) and a second part 22 or second or odd-numbered print lines 26 together (which will be printed between the first lines). Again, for simplicity, only one printed image is shown in a color.

2C shows that instead of in 2 B lines shown the first printed image 21 also a first checkered half 27 and the second print image 22 a preferably complementary, second checkered half 28 of the printed image 20 could be.

The first print lines 25 in 2 B and the first checkered half 27 in 2C are printed by a first printhead of a color. The second print lines 26 in 2 B and the second checkered half 28 in 2C are printed by a second printhead of the same color. Is it the two print images in 2 B and 2C For example, to cyan printed images, the two printheads in configuration A would be the print heads 2A of the printing station 2 and the print heads 5A of the print station 5 , The same applies to the remaining colors.

In the 2D is the line by line construction of a third field 23 of the printed image 20 shown for the black part or the uncoloured part. This is in the example on the left side of the 2D generated with only one printhead. Using the configuration A as an example, this would be the print head 1A of the print station 1 , A comparison of the left side of the 2D and the respective right side of the 2 B and 2C shows that the black part or achromatic part of the printed image 20 has a lower print resolution than the color fraction (for example, half the print resolution). It may therefore, as on the right of the 2D be provided, an eighth printing station 8th with an eighth print head 8A. With this printing station can be a third field 23 Complementary fourth partial image 24 be generated.

3 shows a device for the ink change 30 , Such a device may be a single printing station 1 to 8th be assigned. The device comprises a supply module 31a for first ink, a second ink supply module 31b, and a supply module 31c for cleaning fluid. The inks flow through a printhead 32 or its upstream line system 33 and downstream management system 34 (so-called manifolds). The supply module 31a (and also the supply module 31b in a corresponding manner) has a pump 36a , a pump 36b , a tank 37 , a degasser 38 and a filter 39 on. The ink flows from the supply module via a changeover switch 35a to the printhead and from there via a switch 35b back to the supply module. The switch can z. B. be designed as a switching valves. By means of the changeover switch can between the supply modules 31a and 31b to be changed for ink. Thus, it is z. B. possible between the in 1 to change shown different configurations A to F or a corresponding ink change at affected printing stations 1 to 8th perform. A device for ink change 30 needs only at such printing stations 1 to 8th be provided on which actually takes place an ink change. The first printing station 1 , which prints black ink in all configurations, needs z. B. no such device 30 exhibit. By means of the change-over switch, instead of two different inks, a cleaning liquid can also be passed through the lines and the print head in order to carry out a cleaning before the introduction of new ink.

4 shows a color space 40 or the well-known CIE color triangle with two axes 41 , In the illustration are the color locations of the colors C . M . Y . O . G . V and also the colors F1 to F6 shown. For the latter, only exemplary color locations were selected. Anyway, there are the bright colors of the first color system F1 to F3 and the bright colors of the second color system F4 to F6 each in the delimited by the dashed lines areas.

LIST OF REFERENCE NUMBERS

1

first printing station

1a

first printhead

2

second printing station

2a

second printhead

3

third printing station

3a

third printhead

4

fourth printing station

4a

fourth printhead

5

fifth printing station

5a

fifth printhead

6

sixth printing station

6a

sixth printhead

7

seventh printing station

7a

seventh printhead

8th

eighth printing station

8a

eighth printhead

10

press

11

substrate

12

transport direction

13

investor

14

Precoat plant

15

Inkjet printing unit

16

cylinder

16 '

engine

17

coating unit

18

dryer

19

boom

20

print image

20 '

print lines

21

first partial picture

22

second partial image

23

third part picture

24

fourth partial picture

25

first or even-numbered print lines

26

second or odd-numbered print lines

27

first checkered half

28

second checkered half

30

Device for ink change

31a

Supply module for first tine

31b

Supply module for second ink

31c

Supply module for cleaning fluid

32

printhead

33

upstream line system

34

downstream line system

35a

switch

35b

switch

36a

pump

36b

pump

37

tank

38

degasser

39

filter

40

color space

41

axes

A to G

configurations

C, M, Y

Bright colors of a first color system (cyan, magenta, yellow)

O, G, V

Bright colors of a second color system (orange, green, violet)

F1, F2, F3

Bright colors of a first color system

F4, F5, F6

Bright colors of a second color system

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 373957 A1 [0004]

Claims (8)

A method for operating a multi-color ink printing machine with at least seven printing stations, wherein printheads (1a to 8a) of the printing stations (1 to 7) at least a four-color print image (20) on a in a transport direction (12) moving substrate (11) with a in the Transport direction predetermined printing resolution of at least the Buntanteils of the printed image is printed, wherein three printing stations a first field (21) of the printed image with bright colors of a first color system and half the printing resolution and three other printing stations a complementary to the first field, second field (22) of the printed image with color inks of a second, identical to the first color system or different color system and with half the print resolution, such that the first and the second field complement each other to Buntanteil of the printed image and wherein at least one further printing station, a third field (23) of the printed image with black Ink and with the hal ben print resolution prints. Method according to Claim 1 , characterized in that the chromatic portion of the printed image (20) for each chromatic color in the transport direction (12) of successive print lines (25, 26) is constructed and that the first field (21) all even-numbered lines (25) of the Buntanteils of the printed image and the second partial image (22) comprises all the odd-numbered lines (26) of the color component of the printed image. Method according to Claim 1 , characterized in that the colored portion of the printed image (20) is constructed checkerboard-like (27, 28) for each chromatic color and that the first partial image (21) comprises a first checkered half (27) of the colored portion of the printed image and the second partial image (22) a complementary to the first half second checkerboard-like half (28) of the Buntanteils of the printed image comprises. Method according to one of the preceding claims, characterized in that the first color system comprises the following chromatic colors: C or cyan, M or magenta and Y or yellow, or O and orange, G or green and V or violet , or - Y or yellow, G or green and V or violet, or - F1, F2 and F3, where, based on the color space spanned by the colored colors, F1 between yellow and magenta, F2 between yellow and cyan and F3 between cyan and magenta. Method according to one of the preceding claims, characterized in that the second color system comprises the following chromatic colors: - C or cyan, M or magenta and Y or yellow, or - O or orange, G or green and V or violet , or - Y or yellow, G or green and V or violet, or - F4, F5 and F6, wherein, based on the color space spanned by the chromatic colors, F4 between yellow and magenta, F5 between yellow and cyan and F6 between cyan and magenta. Method according to Claim 5 , characterized in that the printing stations are arranged consecutively in the transport direction in one of the following configurations (A, B, C, D, E, F): - KCMYCMY (A), or - KCMYYMC (B), or - KCMYOGV (C ), or - KCMYYGV (D), or - KCCMMYY (E), or - K F1 F2 F3 F4 F5 F6 (F). Method according to Claim 6 , characterized in that an ink change occurs between two print jobs, wherein the configuration of the print stations changes as follows: from KCMYCMY (A) to KCMYOGV (C) or vice versa (C, A), or from KCMYYMC (B) to KCMYOGV ( C) or vice versa (C, B), or - from KCMYYGV (D) to KCMYOGV (C) or vice versa (C, D), or - from KCCMMYY (E) to KCMYOGV (C) or vice versa (C, E), wherein in the configuration KCMYOGV a seven-color printed image (20) is printed at half the printing resolution. Method according to Claim 7 , characterized in that each printing station at which an ink change occurs comprises a supply module (31a) for a first ink, a supply module (31b) for a second ink and a supply module (31c) for a first cleaning liquid and that between printing with cleaning the first ink and printing with the second ink, switching between the supply modules.

Images