EP2388136A1 - Combination printer - Google Patents

Abstract

The press (10) has printing devices (30, 40, 50) with a printing block for color separation of a color e.g. cyan, magenta, yellow, black. Block-less printing devices (60, 70) are provided for color separation of another color and are provided in the form of ink-jet printing devices or electrophotographic printing devices. The block-less printing devices comprise printing heads and a guide element i.e. guide roller, for a substrate (2) to be printed at a region of the color separation of the printing heads. The printing devices comprise an erasable printing block. An independent claim is also included for a method for printing a multi-colored print image.

Description

The invention relates to a printing machine, in particular a rotary printing machine, for example a web-fed printing press or web-fed rotary printing press, in particular a printing press for the newspaper printing or the printing of daily newspapers in, for example, a large circulation. The printing machine according to the invention can be printed, for example, in the offset process, preferably in the wet printing process. Preferably, the printing press according to the invention has the features of the main claim, is thus used in particular in multi-color printing and preferably represents a combination printing unit.

In industrial newspaper production, a printing unit is usually used for each color and web page, which can print several pages next to each other simultaneously, depending on the machine type. On a printing forme cylinder such as a plate cylinder of the printing unit several printing plates or printing plates are mounted side by side or in the scope one behind the other usually. For a newspaper production, a large number of printing plates must be produced and mounted on the appropriate cylinder in the right place. When changing the print image then the printing forms of the affected newspaper pages are changed, for which a stoppage of the printing press is necessary. The more printing forms that have to be changed, the greater the downtime. Downtimes and errors in the assembly of printing plates reduce productivity and lead to increased costs.

It is known to equip a newspaper printing press with additional equipment to include variable content in a newspaper. For example, an additional printing device, in particular an inkjet printing device or an inkjet print head can be used to apply a part of the printed image to the substrate to be printed.

So revealed the EP 211985 A1 a newspaper printing machine with additional printing device and a corresponding method for variable printing, in which in particular an inkjet print head is arranged at a deflecting body for the web to be printed in order to provide the web with an additional pressure when looping around the deflecting body. Furthermore, several inkjet printheads can be arranged next to one another or one behind the other or spatially offset with respect to the web running direction. According to this document, the assignment of the additional printing device differs to a Rollenabwickler or the individual web fundamentally different from the assignment to the primary printing process. This allows a variable, for example, individual printing of each web independently of the web guide.

DE 10 2006 016 065 A1 discloses an auxiliary printing device for an offset printing principle printing machine having the form of an inkjet printing system. In this case, an inkjet print head is arranged on a traverse transversely to the printing direction in a working position to a paper web within the printing press in one or at least close to a printing unit. This additional device is variable for printing, provided during a print run often changing information.

The invention has for its object to provide a printing machine for multicolor printing, in particular a printing press for the multicolor newspaper printing, which allows a saving of printing plates (in particular printing plates) while maintaining an acceptable print quality and printing speed.

The invention achieves this object by means of a printing machine for printing a multicolor print image composed of a plurality of, in particular different color separations, comprising at least a first printing device with a printing form for a first color separation of a first color and at least one printing-formless further, second printing device for a second color separation for printing in a different, second color. Each of the color separations is advantageous a color separation of a different color. A color separation is understood in particular to be a negative or transparency obtained by recording with a corresponding color separation filter. In other words, a color separation represents a print template which consists of the information for a print image to be printed in a base color or a print image part to be printed in a base color. Advantageously, a color separation therefore only includes those in one of the different Basic colors, for example cyan, magenta, yellow or black, print information to be printed. In a pre-press, color separations are created from different color separations, which as bitmaps represent a digitization of the information contained in a color separation. By printing the information from different color separations or Farbseparationen on the same substrate then a multi-color print image can be printed on the substrate.

A color separation may, for example, be an unscreened halftone image. In particular, a different raster method can be used for each color separation. For example, different color separations may be printed with the same screen ruling and the screen angles customary in multicolor printing, but with the same resolution. In the context of the invention, however, it is also possible to use different screening methods for each color separation, in particular autotypical screening methods, stochastic screening methods or hybrid screening methods in which different of the aforementioned screening methods are combined. The color separations of the different colors together can also yield a multicolored print image, like the DE 10 2008 012 385 A1 this is taught in terms of the composition of the printed image of different colors.

The printing machine according to the invention is preferably set up for multicolor printing, thus enabling printing in several printing inks, in particular cyan, magenta, yellow and black. According to the invention it is also possible to set up the printing press such that only a subset of these primary colors is printed. The printing press can therefore be used to print a colorful or unbunted printed image. In a colorful printed image, subsets of the colorful printing inks cyan, magenta and yellow neutralize each other and thus form achromatic colors, such as black and gray tones. In the case of an unattached print image (also called black buildup), it is intended to print a separate color separation consisting of black printing ink for the corresponding unblank values.

The at least one first printing device with a printing form (also referred to below as "printing plate printing device") preferably comprises at least one printing unit with a plate cylinder and a transfer cylinder, in particular also two, be provided three or four printing units. The printing units are advantageously arranged in a printing tower. The first printing device comprises a printing form, that is to say preferably an impact printer, operates, for example, on the principle of a rotary printing press, for example a rotary printing press or rotary printing press or offset printing press, but can also operate on the principle of a printing press operated in high or low pressure. Within the scope of the invention it is also possible for the first printing press to operate on the principle of screen printing. The printing form thus has the function of a template for the printed image, wherein the printed image applied by means of the printing form preferably does not change in an edition of the printed copy, in particular therefore in a newspaper edition. A change of the transmitted by the first printing device print image or printed image part thus makes a change of the printing form or a change of the image information of an erasable printing form necessary.

The first printing device is provided for transmitting a first color separation of a first color, in particular a base color. The base color is advantageous one of the colors cyan, magenta, yellow and black. When arranging a plurality of printing plate printing devices in the sense of the first printing device in the printing press according to the invention, the printing plate printing devices of the same type, but also printing plate printing devices of different in particular of the aforementioned types. Advantageously, then each of the printing form printing devices transmits a different color separation, in particular a color separation, which differs in color from the color separations of the other printing plate printing devices on. In the context of the invention, a "different" color separation or a "different" color designate, in particular, a color separation or a color that is in particular in the shade of another color separation or another color and / or color separations or other colors differ.

The first printing device comprises in particular at least one printing unit, which can print several pages at the same time, depending on the type of machine, a plurality of printing plates or printing plates are usually mounted side by side or circumferentially one behind the other on a plate cylinder. The printing form is preferably an erasable printing form. For example, an erasable printing form may be a printing form, on the surface of which a polymer layer is present, which contains the information to be printed, and through physical or chemical processes can be neutralized, that can be put into a state in which it no longer has pressure information.

The further, second printing device is a pressure-formless printing device (that is to say a printing device which does not comprise a printing form), which works in particular in a printing process according to the principle of non-impact-printing (NIP), that is to say without a solid printing form (for example, without printing cylinder or stamp). gets along. The second printing device is preferably an inkjet printer (inkjet printer), a printer operating on the principle of electrophotography (for example a laser printer) or a thermal printer.

The conjunction "or" is understood here as well as in any other place in the usual logical sense, ie includes the meaning "either ... or" and also the meaning of "and", as far as the respective context is not exclusively a limited sense results.

The second printing device works advantageously according to another printing principle or is of a different kind than the first printing device. The printing press according to the invention is therefore in particular a combination printing unit comprising at least two printing devices of different types or different functional principles. The second color separation of another, second color transmitted by the second printing device is in particular a color separation whose color is not applied by the first printing device. If a plurality of first printing devices are arranged in the printing press according to the invention, advantageously none of the first printing devices prints a color separation in the second color. If a plurality of second printing devices are arranged in the printing press according to the invention, they can be of the same type or even different, in particular, of the abovementioned printing-form-free types of printing devices. The second printing devices can then each print a different color separation or the same or in each case a part of the same color separation. These color separations or parts of the color separation are then not printed by the first printing device or one of the first printing devices. In particular, therefore, no first printing device prints a second color separation of the other, second color and none second printing device a color separation of the first color. In particular, the set of second colors is not a subset of the first colors.

The printing image to be printed by the printing machine according to the invention is thus preferably made up of a plurality of color separations or color separations, wherein the first printing device and the second printing device are arranged to transmit different color separations or color separations. In particular, the color separation, which is transmitted from a second printing device, preferably differs in color from all color separations, which are transmitted by means of a first printing device.

The invention therefore has the advantage that one of the base paints usually applied by means of a first printing device is applied exclusively by means of a second printing device, the second printing device having no printing forme. This makes it possible to save a printing form in the printing press according to the invention and thus also the saving or shortening of interruptions in operation which become necessary when the printing form changes due to a change in the printing form. The use of the second printing device according to the invention has the further advantage that the number of offset printing units can be reduced compared to the prior art and thus a reduction of the printing plates to be produced and mounted is made possible.

However, in order to enable sufficient quality for the color separation transferred from the second printing device, attention is paid in particular to the resolving power of the human eye. While inkjet technology generally prints high-resolution images, difficulties arise when the print surface moves at high speed relative to the inkjet print head, as is commonly the case in newspaper printing. A high image resolution for the print image of the second color separation requires the formation of correspondingly small drops, ie the ink must be passed through small nozzles, which, depending on the nozzle geometry and viscosity of the liquid ink, means a considerable expenditure of energy. The small drops are formed at a certain distance from the surface, have their own speed and have a specific location on the moving surface with high accuracy. The smaller the drops are, the greater are the difficulties to be overcome due to air flows between the print head and the surface.

However, in order to be able to meet pressure requirements with a lower output resolution using, for example, an ink jet printhead in the second printing device, it is advantageous to reduce the output resolution for those colors where the human eye is less sensitive. Advantageously, a color separation of such a color is transmitted by means of the second printing device. In the case of newspaper printing in particular, this applies, for example, to the yellow printing ink, but also other bright colors such as cyan, magenta or also spot colors can under certain circumstances be perceived by the human eye with only lesser sensitivity. Thus, if the output resolution of the second color separation is reduced compared to that of the first color separation, a sufficient quality of the print image to be transmitted by means of the second printing device can also be supported by means of an inkjet method. For this purpose, the yellow color separation (ie a color separation of a color in the yellow wavelength range) or a color separation of a colored color is advantageously transmitted by means of the second printing device. In the newspaper printing is usually a autotypical grid with screen frequencies of about 40 1 / cm to about 48 1 / cm. The screening is preferably carried out for each ink with a certain screen angle. Usually the grids of each color are rotated by 60 ° to each other. Since it is not possible to shift the screen angle by 60 ° for all four inks, there is one exception: Yellow is rasterized at an angle of 0 °. The moire effect between the yellow grid and the grids of the other color separations is not perceived as disturbing by the human eye. The absorption range of the yellow ink is in the short-wavelength range of the visible spectrum, in which the receptors of the eye are less sensitive. According to one embodiment of the invention, therefore, the yellow color is preferably applied by the second printing device. Preferably, the resolution of the print image or color separation to be transferred with the second printing device differs from the resolution of the part of the print image or color separation to be transferred by means of the first printing device, ie, the resolution of a print to be applied in yellow (In particular, each individual) to be transmitted by the first printing device print image. In particular, the resolution of the second Printing device to be transmitted print image or color separation less than the print device to be transmitted by the first printing device or color separation or the means of the first printing device to be transferred print images or color separations, if the printing machine comprises a plurality of first printing devices.

In particular, the second printing device comprises at least one inkjet printhead or inkjet printhead, for example, it may be an inkjet printhead, which according to the continuous inkjet principle, the drop-on-demand inkjet principle, the thermal Inkjet principle, the bubble inkjet principle or any other inkjet principle works. An advantage of the inkjet method over the offset method is that no printing form is produced, mounted and changed to change the print image to be transferred from the inkjet print head. Inkjet printheads can be made more compact and lighter than offset printers.

Preferably, a print head of the second printing device is arranged in the direction of rotation of the printing cylinder between a contact point of the printing cylinder with the transfer cylinder and the substrate to be printed. Preferably, the print head is mounted on a position of the printing cylinder, which lies in the direction of rotation of the printing cylinder between the contact point and the substrate or the transport path of the substrate.

According to a further embodiment of the invention, all color separations (i.e., both the color separations transferred by the second printing device and those transferred by the first printing device) are printed with the same screen pitch and screen angles, but not the same resolution. Also in this case, the color separation transferred from the second printing device is advantageously printed with a lower resolution than the color separation transferred from the first printing device.

According to a further embodiment of the invention, the printing press in particular has a plurality of second printing devices each with in particular three print heads, wherein each print head is advantageously set up to print another color ink. Advantageously, the first printing device is then set up for printing with black ink (especially exclusively black ink). Advantageously, the printheads are each a second printing device then set up their colors on a common

Transfer transfer cylinder. In this case, different second colors can be transferred to the common transfer cylinder. In the context of the invention, however, it is also possible for a second printing device to apply its color to a separate transfer cylinder individually assigned to each print head of a second printing device. In particular, at least one print head of a second printing device prints on a transfer cylinder, advantageously a transfer cylinder of a first printing device.

The printing by means of the second printing device can also be done directly on a substrate to be printed. When printing a paper web, it is advantageous to provide a guide element for the web, for. B. to use a guide roller that keeps the distance between the paper web and inkjet printhead constant. The application of the ink by an inkjet printhead takes place, for example, in a region in which the web wraps around the guide roll, or at least in the vicinity of the contact region of the guide roll and the web.

According to a further embodiment, the color of at least one color separation of another, second color is applied to the same transfer cylinder of a first printing device in which a color separation of a first color is printed by means of the second printing device.

According to a further embodiment of the invention, the second printing device comprises a plurality of print heads with nozzles or output devices. In the case of a second printing device in the form of an ink jet printing device, a print head advantageously comprises a plurality of output devices in the form of print nozzles. However, it is also possible to use a plurality of print heads of an electrophotographic printing device (for example a laser printer). An inkjet printhead may for example consist of elements perpendicular to the web transport direction, but in the web transport direction but offset from each other elements, wherein an element is an arrangement or grouping of advantageous multiple inkjet nozzles. Accordingly, the inkjet nozzles can also be arranged, for example, at an angle, in particular at an acute angle to the web transport direction, in order to achieve a higher resolution. Advantageously, at least one nozzle is provided for each position transversely to the web transport direction, which can apply paint to the web at this position. The way to one in particular web-width print head combined elements thus form a print line, although the pressure nozzles belonging to the line do not necessarily have to be in line.

For example, an inkjet element has 1000 nozzles that are in line with each other at intervals of 100 μm between the nozzles. An element may be oriented so that the nozzles are arranged in a line transverse to the direction of web travel. With a web width of 1270 mm in particular then 13 elements are needed, which are summarized in a print head. This printhead can print on the web at a resolution of 256 dpi. If one were not to arrange these elements at an angle of 90 ° to the web transport direction, but at an angle ω, then the print width is reduced by the factor sin (ω). At ω = 45 °, the printing width per element is then 70.7 mm. The nozzle spacing across the web transport direction is 70.7 microns, it is for a 127Q mm wide web 18 mm needed and the resolution is then 359 dpi. The second printing device may have multiple printheads for different colors, but multiple printheads may print the same color. At least one printhead is required for each color to be printed.

According to a further embodiment, the printing machine according to the invention is adapted to apply the second color, in particular a colored ink to a transfer cylinder, in particular a transfer cylinder for black color. The transfer cylinder to which the second ink is applied, according to another embodiment, a transfer cylinder on which also the first printing device applies a color.

In the context of the invention, the color spots of the printed image applied with the second printing device can be arranged with a predominantly surface part only in non-ink spots of the printed image transferred with the first printing device. The first and second colors are spatially separated in this sense. Preferably, however, the first and the second color are separated from each other over an at least predominant surface portion of the print image formed jointly by them so that they have no overlap there. More preferably, they have no overlaps at all. Color spots of the first color and color spots of the second color can collide laterally. In a According to another embodiment of the invention, it is possible for the color points of the first and second colors to overlap one another in principle or in a largely predominant area proportion of the common printed image. If the first and second printing device use the same transfer cylinder, the inking of the second printing device is preferably carried out in the direction of rotation of the transfer cylinder after the inking of the first printing device and before the contact of the transfer cylinder with the substrate. Finally, according to the invention, the first and the second color separation are applied to the same substrate, in particular to the same side of a substrate.

The invention also provides a method for printing a printed image composed of a plurality of color separations, wherein each of the color separations is a color separation of a different color and wherein in the method at least a first color separation of a first color is transmitted by means of a printing form of a first printing device and at least one second color separation of a second, different color is transmitted by means of a printing forme further, second printing device. Other features of the method may be formulated according to the device features of the above-described printing machine. In particular, the printing machine described above is set up to carry out the method according to the invention.

Features of different embodiments of the invention may be combined between the embodiments, as technically feasible and reasonable.

• Figur 1 zeigt eine erste Ausführungsform der Erfindung, bei der drei erste Druckvorrichtungen und zwei zweite Druckvorrichtungen vorgesehen sind. Die zweiten Druckvorrichtungen drucken dabei direkt auf das Substrat.
• Figur 2 zeigt eine zweite Ausführungsform der Erfindung mit drei ersten Druckvorrichtungen, wobei mehrere zweite Druckvorrichtungen auf die gegenüberliegenden Übertragungszylinder einer ersten Druckvorrichtung Farbe auftragen.
• Figur 3 zeigt eine dritte Ausführungsform der Erfindung mit drei ersten Druckvorrichtungen und einem getrennten Satz Übertragungszylinder für mehrere zweite Druckvorrichtungen.
• Figur 4 zeigt eine vierte Ausführungsform der Erfindung, bei der zwei Gegendruckzylinder einer ersten Druckvorrichtung jeweils als Führungsrolle für das Substrat bei direktem Farbauftrag durch die zweite Druckvorrichtung wirken.
• Figur 5 zeigt eine bevorzugte Anordnung von Druckköpfen der zweiten Druckvorrichtung. Zum Zwecke der Figurenbeschreibung werden einzelnen Druckwerken der ersten Druckvorrichtungen verschiedene Farbauszüge (insbesondere cyan - C, magenta - M und schwarz - K) zugeordnet. Diese Zuordnung ist jedoch nicht fest, sodass auch eine andere Verteilung der Farben auf die Druckwerke im Rahmen der Erfindung möglich ist. Insbesondere kann einer ersten Druckvorrichtung auch die Farbe gelb - Y zugewiesen werden.

From the following description of the figures, some specific embodiments of the invention will become apparent.

• FIG. 1 shows a first embodiment of the invention, in which three first printing devices and two second printing devices are provided. The second printing devices print directly onto the substrate.
• FIG. 2 shows a second embodiment of the invention with three first printing devices, wherein a plurality of second printing devices apply to the opposite transfer cylinder of a first printing device color.
• FIG. 3 shows a third embodiment of the invention with three first printing devices and a separate set of transfer cylinders for a plurality of second printing devices.
• FIG. 4 shows a fourth embodiment of the invention, in which two impression cylinders of a first printing device each act as a guide roller for the substrate in direct ink application by the second printing device.
• FIG. 5 shows a preferred arrangement of printheads of the second printing device. For the purposes of the description of the figures, individual color prints of the first printing devices are assigned different color separations (in particular cyan C, magenta M and black K). However, this assignment is not fixed, so that a different distribution of colors on the printing units within the scope of the invention is possible. In particular, the color yellow-Y can also be assigned to a first printing device.

In FIG. 1 is a printing machine 10 for printing a substrate 2 with three first printing devices, each in the form of a printing unit 30, 40, 50 shown. Further, two second printing devices 60, 70 are provided with two and three ink-jet printheads 61, 71 for direct printing of the substrate 2, respectively. The substrate 2 has a web shape, is in particular a roller conveyor, preferably made of paper. The printing units 30, 40, 50 are provided for double-sided printing of the substrate 2, so that each plate cylinder 32, 32 '; 42, 42 '; 52, 52 'and transfer cylinders 31, 31'; 41, 41 '; 51, 51 'are symmetrical with respect to the web plane. The transfer cylinders 31, 31 '; 41, 41 '; 51, 51 'are for example rubber cylinder or blanket cylinder. The printing gaps of the printing units 30, 40, 50 are formed by the opposite transfer cylinders. The second printing devices 60, 70 have a plurality of print heads 61, 71, each facing a web side, so that the second printing device 60 and the second printing device 70 each print a different web page. The second printing device 60 is disposed between the second printing unit 40 and the third printing unit 50 on a first web side, the second printing device 70 is disposed downstream of the third printing unit 50 on the other, second web side.

The first printing unit 30 is adapted to transfer the hue cyan, the second printing unit 40 to transfer the hue magenta and the third printing unit 50 to transfer the hue black. The arrows indicate the direction of rotation of the transfer cylinder. The substrate 2 is thus transported in the direction from the first printing unit 30 to the second printing device 70.

The second printing devices 60, 70 are arranged to transmit the yellow Y color. The output resolution of the yellow separation is between 100 and 600 dpi, preferably between 180 and 300 dpi. The color separations black, cyan and magenta are conventionally rasterized with high resolution and printed using the offset method. The output resolution of yellow is below the output resolution of black, cyan and magenta.

The ink jet printing by the second printing devices 60, 70 takes place directly on the substrate 2. The printing width of each print head 61, 71 corresponds to the maximum paper size, in particular the web width. Each printhead 61, 71 is associated with a paster. In this embodiment, 25% less offset printing units are required compared to the conventional offset printing, since the printing machine 10 has no offset printing unit for the hue yellow Y. The printing of this color separation is done by the second pressure devices 60, 70th

In the embodiment of the printing press 11 according to FIG FIG. 2 like reference characters designate the same components of the printing press of the invention as in FIG FIG. 1 , However, in the printing machine 11, the second printing devices 60 ', 70' are not designed for direct printing of the substrate 2. Rather, they transfer yellow color Y to the transfer cylinders 81, 81 'of the printing unit 80 for black color K arranged on both sides of the substrate. The transfer cylinders 81, 81' are driven by plate cylinders 82, 82 '. The second printing device 70 'in this case has a print head for yellow color Y, the second printing device 60' in this case has two print heads 61 'for yellow color Y. The second printing devices 60 ', 70' are again ink jet printing apparatus. In this case, the print head of the second printing device 70 'is opposite the transfer cylinder 81' at a position of the transfer cylinder 81 ', which in the direction of rotation of the transfer cylinder 81' between a contact with the black plate cylinder 82 '. and the paper web or the substrate 2 is located. Likewise, the print heads 61 'of the second printing device 60' are opposed to the transfer cylinder 81 at a position lying in the direction of rotation of the transfer cylinder 81 between its contact with the black plate cylinder 82 and the paper web.

Also in this embodiment, 25% fewer offset printing units are needed compared to the conventional offset printing technique, since the order of the yellow color separation Y is done exclusively by second printing devices 60 ', 70'.

In the third embodiment of the printing press 12 according to the invention FIG. 3 In turn, like reference numbers refer to the same components as in FIG FIGS. 1 and 2 , In the printing machine 12 of the third embodiment will be accordingly FIG. 1 three first printing devices in the form of printing units 30, 40, 50 are used to transfer the colors cyan C, magenta M and black K to the substrate 2. Downstream of the third printing unit 50, two transfer cylinders 62, 72 for yellow color Y are arranged symmetrically to the web plane, second printing devices 60 ", 70", which are opposite to the preferably web-facing half of the transfer cylinders 62, 72, apply yellow ink Y in the inkjet printing process the transfer cylinders 62, 72. This corresponds to an indirect color application, since the color is first applied to the substrate 2 by the transfer cylinders 62, 72. The second printing device 60 "has four print heads 61. The second printing device 70" on the opposite web side has two print heads 71. However, it is also possible that the second printing devices 60 ", 70" each have only one print head 61, 71.

In this embodiment, the second printing devices 60 ", 70" are each assigned a separate transfer cylinder, which is not simultaneously used by a first printing device 30, 40, 50. In FIG. 3 Although it is shown that the printheads 61, 71 for each of the two second printing devices 60 ", 70" apply the same colors (here yellow color Y), in the invention it is also possible that the printheads 61, 71 for each of the second Print devices 60 ", 70" apply a different color. Likewise, it is also possible for the print heads 61, 71 to apply different colors to a transfer cylinder 62, 72 common to each of the two second printing devices 60 ", 70" within a second printing device 60 ", 70". In that sense, equality is or difference in the colors applied by the second printing devices 60 ", 70" is not important to the feasibility of this embodiment. In this case, advantageously, at least two of the first printing devices 30, 40, 50 apply the same color, since the amount of color separations of the first printing devices and the amount of color separations of the second printing devices do not intersect and form no subset of each other.

In a fourth embodiment of the invention according to FIG. 4 In turn, like reference numbers refer to the same components as in FIG FIGS. 1 to 3 ,

The printing press 13 according to FIG. 4 has two printing units 100, 200 with plate cylinder 101, 201 and transfer cylinders 102, 202 for printing a substrate 2 with black color K. The impression cylinders 103, 203 are looped around by the web of the substrate 2. Downstream of a contact point between the transfer cylinders 102, 202 and impression cylinders 103, 203 (ie downstream of the printing gaps for each of the two sides of the substrate 2), the impression cylinders 103, 203 each have a second printing device 110, 210 for the printing inks Cyan C, Magenta M and yellow Y opposite. The second printing device 110 again operates by the ink jet method and has print heads 104, 105, 106, 107, 108. The second printing device 210 also operates by the ink jet method and has print heads 204, 205, 206, 207, 208. Prior to entry into the printing nip for the first web side between transfer cylinder 102 and impression cylinder 103, a guide roller 109 is provided upstream of the first printing nip, which assists in orderly redirecting the substrate 2 into the first printing nip. Similarly, a guide roller 209 downstream of the second printing device 210, which prints on the other side of the web, is provided, which supports a discharge of the substrate 2 from the printing press 13. The distribution of the same or different colors on the printheads 104,..., 108 and 204,..., 208 and the number of printheads per second printing device 110, 210 are the same as in the embodiment of FIG FIG. 3 not relevant to the feasibility. In particular, every second printing device 110, 210 may comprise only one print head.

The chromatic colors cyan C, magenta M and yellow Y in each of the second printing devices 110, 210 are applied to the individual print heads 104, 105, 106, 107, 108 and 204, 205, 206, 207, 208, respectively Each one of the printheads of a second printing device prints each one of the bright colors. When two printheads of a second printing device print the same ink, the printing is preferably made at a different resolution. However, each of the two second printing devices 110, 210 is set up in order to be able to print the entirety of the three bright colors. In this embodiment, therefore, only the black K ink is printed by the offset method, and the three chromatic colors are ink jet printed by the second printing devices 110, 210.

Also in this embodiment, a direct application of the ink from the second printing device 110, 210 takes place on the substrate 2 to be printed. The distance between the surface of the substrate 2 to be printed and the print heads 104; ...; 108; 204; ...; 208 is constant for the entirety of all print heads.

The impression cylinders 103, 203 and the transfer cylinders 102, 202 form a rubber-steel printing unit, the impression cylinders 103, 203 acting as guide elements, in particular guide rollers for the substrate 2. The guide rollers cause a constant distance of the web 2 against the print heads 104, ..., 108; 204, ..., 208 is maintained, thereby assisting in achieving the necessary quality of ink-jet printing. It is understood that the substrate 2 has the necessary web tension, which is supported in particular by the upstream paper roll and possibly tensioning devices at the downstream end of the printing press 13 or the paper web.

The individual ink jet printheads 104, ...; 108; 204, ..., 208 of a second printing device 110, 210 in the fourth embodiment have different output resolutions. For example, the printheads 104, 105 print the cyan color separation C at a resolution of 600 dpi. The print heads 106, 107, 206, 207 print the magenta color separation M with a resolution of likewise 600 dpi. The printheads 108, 208 print the yellow color separation at a resolution of 300 dpi.

FIG. 5 shows an arrangement of pressure nozzles 511, ..., 514; 521, ..., 525 in a second printing device 500, as used as the second printing device 60, 70; 110, 210 may be used in any of the previously described embodiments. The second Printing device 500 is, for example, an ink jet printing device, and in the example of FIG FIG. 5 two printheads 510, 520 with nozzles 511, ..., 514; 521, ..., 525 on. In the FIG. 5 The geometry represented represents a projection of the position of the print heads 510, 520 with respect to the web direction of the substrate 2 in the plane and is therefore also for the embodiments of FIG. 2 to FIG. 4 applicable. The nozzles 511, ..., 514; 521,..., 525 of the print heads 510, 520 are arranged in two lines which are perpendicular to the web direction of the substrate 2. The nozzles of the two lines are cascaded, so arranged so that their line position is not coincident or offset from one another. This makes it possible to hold the nozzles stationary with respect to the position of the substrate 2 and still achieve coverage of the entire web width with nozzles. The distance d between two nozzles 521, 522 and 512, 513 is 80 μm, for example, in the case of an output resolution of the printheads 520, 510 of 300 dpi, and at an output resolution of 600 dpi, d is 40 μm. The extent of the print heads 510, 520 or of their nozzles 511, ..., 514; 521, ..., 525 covered printing area is preferably at least the full web width of the substrate 2, so that edge regions of the substrate 2 can be printed with the second printing device 500.

FIG. 6 shows, as in the embodiment according to FIG. 4 the printing on the substrate 2 is effected by means of inkjet printheads 104, 105, the inkjet printheads 104, 105 being representative of the entirety of printheads 104,..., 108 and 204,..., 208 of the embodiment of FIG FIG. 4 are. In FIG. 6 Furthermore, the counter-pressure cylinder 103 is shown, which, however, can also be regarded as a representative of the impression cylinder 203 (when the direction of rotation indicated by the arrow is reversed). The substrate 2 to be printed is guided on the surface of the impression cylinder 103. An inkjet printhead 104 irradiates at a frequency f the substrate 2 with ink drops. Typical frequencies for ink jet are at an interval of 20 kHz ≤ f ≤ 200 kHz. Preferably, the frequencies are in an interval of 50 kHz ≤ f≤100 kHz. On the substrate 2, the drops 110 adhere and form ink patches 111 with a diameter d. Typical diameters of the color spots are in a range of 20 μm ≤ d ≤ 100 μm or 1270 dpi ≤ d ≤ 256 dpi. The web transport speed of the substrate 2 is greater than d / f. Typical web speeds are in a range of 4 m / s ≦ v ≦ 15 m / s. If, for example, v = 10 m / s, f = 100 kHz is set, a color point is formed on the substrate 2 every 100 .mu.m. Now if the diameter of a color point d = 50 microns, it will Substrate not completely covered or not fully printed. A second inkjet print head 105 then also irradiates the substrate 2 at a frequency f with ink droplets 112. The droplets 112 that it produces then form color spots 113 that remain between the ink patches 111 that were produced by the first inkjet printhead 104 Close gaps. With suitable synchronization of the two print heads 104, 105 to each other and to the movement of the substrate 2, the double resolution can be achieved at the same web speed v.

FIG. 7 shows an arrangement of the printing devices 110, 210 and printing units 100, 200, in which the transfer cylinders 102, 202 serve as web guide elements or guide rollers for the substrate 2. The printheads 104, 105, 106 of a first printing device 110 and printheads 204, 205, 206 of a second printing device 210 print directly on the substrate 2. It should be emphasized that FIG FIG. 7 the transfer cylinders 102, 202 and not as in FIG. 4 the impression cylinders 103, 203 are used as web guide elements. This results, inter alia, the advantage over the embodiment of FIG. 4 in that a shorter distance of the substrate between the pulleys 109, 209 is guided.

Claims (16)

Printing machine (10, 11, 12, 13) for printing a multi-color printed image composed of a plurality of color separations, each of the color separations being a color separation of a different color (C, M, Y, K), the printing press (10, 11, 12, 13) comprising: a) at least one first printing device (30, 40, 50, 80) having a printing form for a first color separation of a first color (C, M, Y, K), b) at least one second printing device (60, 70, 60 ', 70', 60 ", 70", 500) for a second color separation of another, second color (C, M, Y, K). A printing machine (10, 11, 12, 13) according to any one of the preceding claims, wherein the second printing device (60, 70, 60 ', 70', 60 ", 70", 500) comprises an ink jet printing device or an electrophotographic printing device. A printing apparatus (10, 11, 12, 13) according to any one of the preceding claims, wherein said second printing means (60, 70; 60 ', 70'; 60 ", 70"; 500) comprises a plurality of print heads (61, 71, 510, 520 ). Printing machine (10, 11, 12, 13) according to one of the preceding claims, in which the second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500) prints directly onto a substrate (2) to be printed , Printing machine (10, 11, 12, 13) according to one of the preceding claims, wherein at least one print head (61, 71, 510, 520) of a second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500) is adapted to apply the second color (C, M, Y, K), in particular a chromatic color (C, M, Y), to a transfer cylinder (81, 81 '). Printing machine (10, 11, 12, 13) according to the preceding claim, in which the transfer cylinder (81, 81 ') for the at least one print head (61, 71, 510, 520) of a second printing device (60, 70; 60', 70 ") is simultaneously used as a transfer cylinder of a first printing device (30, 40, 50, 50, 80). Printing machine (10, 11, 12, 13) according to one of the preceding claims, in which a print head (61, 71; 510, 520) of the second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500 ) in the direction of rotation of a transfer cylinder (81, 81 ') between a contact point of a plate cylinder (82, 82') with the transfer cylinder (81, 81 ') and a substrate to be printed (2) is arranged. Printing machine (10, 11, 12, 13) according to the preceding claim, in which the second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500) is set up, color (C, M, Y, K) on a for at least two of the print heads (61, 71, 510, 520) common transfer cylinder (81, 81 ') to transmit. Printing machine (14, 11, 12, 13) according to one of the preceding claims, in which the first printing device (30, 40, 50, 80) is provided with an erasable printing form. Printing machine (10, 11, 12, 13) according to one of the preceding claims, wherein the second printing device (60, 70, 60 ', 70', 60 ", 70", 500) is arranged, the second color (C, M , Y, K), in particular a chromatic color (C, M, Y), to a part of a substrate (2) guided around a transfer cylinder (81, 81 ') or impression cylinder (103, 203). Printing machine (10, 11, 12, 13) according to one of the preceding claims, which in the region of the paint application of one or more print heads (61, 71, 510, 520) of the second printing device (60, 70, 60 ', 70 ") is a guide element for the substrate to be printed (2). Printing machine (10, 11, 12, 13) according to the preceding claim, wherein the guide element is a guide roller. Printing machine (10, 11, 12, 13) according to the preceding claim, wherein the guide element is a transfer cylinder (102, 202) or an impression cylinder (103, 203) of a first printing device (30, 40, 50, 80). A method of printing a multicolor printed image composed of a plurality of color separations, wherein each of the color separations is a color separation of a different color (C, M, Y, K) and wherein in the method a) at least a first color separation of a first color (C, M, Y, K) is transmitted by means of a printing form to a first printing device (30, 40, 50, 80), b) at least a second color separation of a second, different color (C, M, Y, K) by means of a pressure-forming further, second printing device (60, 70, 60 ', 70', 60 ", 70", 500) is transmitted. Method according to the preceding claim, in which the resolution of the print image to be transferred with the second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500) depends on the resolution of the image recorded by the first printing device (30, 40 , 50, 80) differs to transmitted print image, in particular is lower. Method according to one of the two preceding claims, wherein the second printing device (60, 70; 60 ', 70'; 60 ", 70"; 500) is arranged to print a yellow color (Y).

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