Measuring strip arrangement

Abstract

Measuring strip arrangement for a double-sided coated substrate, wherein at least a portion of the measuring strip on one side of the substrate overlaps with at least a portion of the measuring strip on the other side of the substrate, characterized by that at least one measuring strip in the middle of the machine width of a machine coating the substrate has a reduced coating, that a color measurement area of ​​a measuring strip is opposite an area not used as a color measurement area and / or that at least one measuring strip contains a center-of-arc marker.

Description

[0001] The invention relates to a measuring strip arrangement according to the preamble of claim 1.

[0002] Particularly problematic in the design of measuring strips for rotary printing machines are especially thin and / or penetrating printing materials.

[0003] Currently, measuring strips in perfecting presses must be positioned offset on opposite sides of the sheet to prevent interference from ink showing through or bleeding through from the underside onto the side being measured. To prevent interference from the reverse side printing (which also includes a measuring strip), the measuring strips can be positioned either offset circumferentially or at the beginning of the sheet behind the gripper area. These solutions require twice the surface area on the substrate, corresponding to the height of the measuring strips.

[0004] DE 10 2004 031 129 A1 discloses a method for detecting color bars on double-sided color prints, a system for quality control of a color print and a device for quality assessment of a color print.

[0005] DE 10 2006 061 997 A1 shows a measuring unit for the continuous, automatic acquisition of color data.

[0006] DE 10 2008 031 735 A1 shows a grey balance correction of a printing process.

[0007] DE 10 2008 056 170 A1 shows a color measuring device with automatic side detection.

[0008] The invention is therefore based on the objective of creating an alternative arrangement for measuring strips on substrates.

[0009] According to the invention, the problem is solved by a measuring strip arrangement with the features of the independent first claim. Advantageous embodiments are described in the dependent claims, the description, and the drawings.

[0010] The invention has the advantage that an alternative arrangement for measuring strips on substrates, in particular on double-sided printable materials, preferably on sheets in a printing machine, is created.

[0011] The measuring strip arrangement is suitable for use with a substrate that can be coated on both sides. Each substrate can be coated on both sides. The coating material, for example, one or more colors, varnishes, foil, and / or other materials, can be applied to the substrate using any coating process. The coating can be applied by contact or without contact (non-impact printing, NIP). In particular, double-sided printing of a substrate is carried out in a printing press. Printing is especially preferred in a sheet-fed printing press that can be operated in a single-sided printing mode.

[0012] The arrangement of a measuring strip on both sides of a given substrate is such that at least a portion of the measuring strip on one side of the substrate overlaps with at least a portion of the measuring strip on the other side, particularly taking into account the functionality of the measuring surfaces of the measuring strips. The function of a measuring surface can be understood as the different information encoded by that surface. The measuring strips are designed in such a way that the functionality of the measuring surfaces is not restricted. In particular, the measuring surfaces are not influenced or disrupted by opposing measuring surfaces. Functionality can be ensured, for example, by placing an uncoated measuring surface opposite a coated one.

[0013] In a preferred embodiment, the measuring strip for perfecting machines is specially designed, wherein a "transparent measuring strip" is constructed such that non-printing fields are mounted on the opposite printed side. Particularly advantageous is the unprinted color measuring fields on the opposite printed side. Existing paper whiteness measuring fields are unprinted in both measuring strips. The measuring strips have a main extent across the sheet width, i.e., perpendicular to the sheet direction. The size of the measuring fields allows, in particular, one solid color measuring field per color zone. Measured values ​​and / or correction values ​​can be supplied to the machine, for example, via a control element or a control station. The color zone settings can then be changed accordingly via adjusting elements in the machine control system.

[0014] In a further training course, it is planned to design a print pressure measuring strip with a wider recess, for example in the middle, for a brake band in a delivery unit of a printing press, which prevents smearing.

[0015] In a preferred embodiment, one or both measuring strips have a sheet center mark, in particular a visual contact point and / or an assembly aid in the prepress stage. By means of at least one side identification mark, for example a side identification mark, in the measuring strip, the measured sheet side can be further assigned to a printing unit, preferably automatically, by a quality control device. In particular, coded register marks are present in one or preferably both measuring strips.

[0016] Advantageously, only the paper area of ​​one measuring strip is required. The measuring fields in the center of the sheet are not smeared by braking elements. The measured values ​​are not influenced or distorted by the other printed side, thus enabling standard-compliant measurement. Furthermore, fully automatic detection and measurement of the measuring strip on both sides is possible. At the same time, simple installation in the prepress stage is achieved.

[0017] The invention will now be explained by way of example. The accompanying drawings schematically illustrate the following: Fig. 1: Turning device for a sheet processing machine; Fig. 2: Print quality measuring strip of a sheet; Fig. 3: Back pressure measuring strip of the sheet.

[0018] The Fig. Figure 1 shows, in one embodiment, a section of a substrate-processing machine, particularly a sheet-fed printing press, especially a sheet-fed offset rotary printing press, preferably in a modular or series configuration with a turning device. The machine contains at least two units arranged in series, which can be configured, for example, as setup, printing, coating, drying, and / or finishing units. Furthermore, the machine can include a feeder for sheet feeding and a delivery unit for ejecting the processed sheets. Preferably, the delivery unit includes a sheet brake with at least one braking element contacting each sheet to decelerate and then deposit the sheet, for example, onto a sheet stack.The turning device is arranged between two printing units of the machine, and the turning device has at least one sheet guide system with which at least one of the sheets can be turned. Preferably, the turning device turns each sheet transported in a sequence. The printing press can, for example, have four printing units before and four printing units after the turning device.

[0019] The turning device is arranged here between a cylinder, for example a printing cylinder 4 of an upstream unit, in particular a printing unit, and another cylinder, for example a printing cylinder 4 of a downstream unit, in particular a printing unit, of the machine. The printing cylinders 4 have solid outer surfaces and are operatively connected here to rubber cylinders 5, and these in turn to plate cylinders in the printing units. Known inking units or inking and dampening units (not shown) are arranged in the printing units, which apply the corresponding printing ink to a printing plate stretched on the respective plate cylinder. A plate cylinder is inked by at least one, but preferably several, rollers of the associated inking unit or inking and dampening unit during its rotation. The inking of the printing plate can take place in ink zones across the width of the printing plate.The inking in the color zones can be set or regulated separately. As the plate cylinder rolls down the rubber cylinder 5, the printing ink is transferred to the rubber cylinder 5, which is covered with a rubber blanket, in accordance with the image design. A printing gap is formed between the rubber cylinder 5 and the printing cylinder 4, through which the sheet to be printed is conveyed from the printing cylinder 4. In this printing gap, the printing ink of the partial print image and at least part of a measuring strip is transferred from the rubber cylinder 5 to the sheet in accordance with the image design. Conventional ink and / or UV ink can be used, for example. The rubber cylinder 5 and plate cylinder can, for example, be of single size. Alternatively or additionally, a turning device can be arranged between other units in the machine.

[0020] The machine includes sheet conveying systems, in particular sheet guide cylinders, for transporting the sheets through the printing units. In the printing units, for example, printing units, and in the turning device, sheet guide cylinders and / or sheet guide drums are arranged, preferably featuring gripper systems (not shown) for securing the sheets during transport. The gripper systems are designed, in particular, as clamping grippers for clamping the leading edge of the sheet. The printing cylinders 4 can, for example, be twice the size and transport the sheets to be printed through the printing nip or printing unit during their rotation. For transport, the sheets are clamped and thus secured at the leading edge by means of gripper systems. The sheets can be transported and transferred between two printing cylinders 4 by at least one sheet conveying system. For example, one or more sheet guide cylinders can be arranged between the printing cylinders 4.The sheet guide cylinders can be single or multiple sizes. For sheet transport, the sheet guide cylinder(s) can have a complete cylindrical surface or at least cylindrical surface segments on which the sheets are placed. Alternatively, sheet guide drums can also be designed as so-called transferrs without cylindrical surface segments. Between the sheet guide cylinders and the printing cylinders 4, the sheets are transferred at their leading edge by the gripper. Additional sheet guide elements, such as sheet guide plates, can be assigned to the sheet conveying systems for sheet guidance.

[0021] The sheet guide cylinders are preferably driven rotaryally by a gear train of a continuous gear train. The continuous gear train can be driven by a single main drive or by several individual motors coupled at different points. In a further embodiment, it is also possible to drive cylinders and / or rollers individually or in groups. Preferably, for example, a plate cylinder can be assigned its own drive, which drives the plate cylinder individually and / or independently of the machine's gear train during printing. The individual drive for the plate cylinder can, in particular, be designed as a direct drive with, for example, a rotor arranged concentrically to its cylinder axis and / or directly connected. In the turning device, the driven cylinders shown here rotate in the direction indicated by the arrows.

[0022] The perfecting unit is preferably designed as a three-drum perfecting unit and includes three sheet guide cylinders for transporting sheets. The perfecting unit comprises, for example, a double-sized transfer drum 1, a double-sized storage drum 2, and a single-sized perfecting drum 3, wherein a single-sized cylinder can typically accommodate a sheet of maximum format circumferentially. The transfer drum 1 is located immediately upstream of the storage drum 2, and the perfecting drum 3 is located immediately downstream of the storage drum 2. The machine is preferably designed to be switchable between a single-print mode and a double-print mode. In the single-print mode, the sheets can be transferred between the sheet guide cylinders without being perfected.In perfecting mode, the sheets are turned over by the turning device so that the reverse side of the sheet can be processed, in particular printed, in the subsequent printing unit. The turning drum 3 also contains grippers (not shown) for taking a sheet from the storage drum 2 at the leading edge in perfecting mode and at the trailing edge in perfecting mode. The grippers of the turning drum 3 can be pivoting grippers and / or suction cups or a clamping gripper system. The sheet transfer from the storage drum 2 to the turning drum 3 takes place in a transfer unit. The transfer unit formed between the two drums is an imaginary line in which a sheet held by the storage drum 2 is taken over by the gripper of the turning drum 3. The sheet is transferred in register while being briefly held by both drums.Alternatively, other cylinder sizes and / or a different number of cylinders can of course be used in the units, for example printing units, and the turning device. Intermediate dryers and / or measuring systems (not shown) may be assigned to and / or upstream of the turning device.

[0023] In the perfecting unit, during perfecting mode, the sheet to be perfected is guided with its leading edge first on the storage drum 2. During perfecting, the sheet is guided from the storage drum 2 past the transfer unit and gripped at its trailing edge by the perfecting drum 3. The trailing edge of the sheet, resting on the storage drum 2, is then picked up by the gripper, in particular a gripper gripper or grippers and / or suction cups that are pivotably mounted in the rotating perfecting drum 3. The gripped sheet is then turned over during the rotation of the perfecting drum 3 according to the principle of trailing-edge turning, so that its old trailing edge becomes the new leading edge upon reversal of movement, and the old leading edge, which was resting on the storage drum 2, becomes the new trailing edge. The perfecting print, including at least one measuring strip, is applied to the sheet in the printing slits upstream of the perfecting unit.In the double-sided printing mode, the reverse print, including at least one measuring strip, is applied to the sheet in the printing gaps downstream of the turning device.

[0024] The Fig. Figure 2 shows, in one embodiment, a proofing strip 6 of a sheet, which, for example, has been processed in a sheet-processing machine. The proofing strip 6 shown has a marking indicating the center of the measuring strip 8. The center of the measuring strip 8 is preferably always positioned centrally with respect to the machine width. The measuring fields located in the area of ​​the center of the measuring strip 8 have a reduced coating or ink coverage, or in particular, no ink coverage at all. The reduced coating in the area of ​​the center of the measuring strip 8 allows for quick visual identification, which, among other things, enables easy alignment of the sheet on a measuring table. This allows, in particular, the immediate positioning of geometric measuring coordinates or the placement of a handheld measuring device.Furthermore, the measuring strip center 8, which is preferably always positioned centrally with respect to the machine width, allows for a direct relationship to the ink zones to be measured. This enables, for example, even faster machine control. Preferably, the uncoated area of ​​the measuring strip center 8 is at least 10 to 20 mm, more preferably at least 14 mm across the sheet width. In this area of ​​the uncoated machine center 8, particularly at maximum sheet size, a non-lubricating contact with a braking element of a sheet brake can be achieved. Alternatively or additionally, depending on the design and / or format, other locations on the front-printing measuring strip 6 can be provided for braking elements. The front-printing measuring strip 6 also shows the ink zone width 9, which extends across the sheet width.

[0025] The printing strip 6 further contains color measurement fields 10 for printing inks of the printing units upstream of the perfecting unit and blank fields 11 that are unprinted. Only one color measurement field 10 and one blank field 11 are shown here. The color measurement fields 10 can have different coating thicknesses. The size of the color measurement fields 10 preferably allows for one solid color measurement field per color zone, here for four printing inks of the four printing units upstream of the perfecting unit. Paper whiteness measurement fields 12 are also provided, which also remain unprinted. A field located in the area of ​​the center of the printing strip 8 can also be used for paper whiteness measurement. Furthermore, coded register marks are preferably present in the printing strip 6 and / or page identification marks are provided, by which the measured sheet side is automatically assigned to the printing unit by means of a quality control device, in particular a camera with an attached computer unit.The computer unit can be connected to or integrated into the machine control system. Measurement can be performed offline or inline, particularly on arcs moving in the conveying direction, by the quality control device. Alternatively or additionally, quality control can also be performed outside the machine, for example, on a measuring table.

[0026] The Fig.Figure 3 shows a reverse print test strip 7 of the same sheet, located on the opposite side of the front print test strip 6. The reverse print test strip 7 preferably overlaps the front print test strip 6 across its width and / or height. The reverse print test strip 7 is thus particularly preferably arranged congruently with the front print test strip 6. The reverse print test strip 7 also includes a center mark 8, color measurement fields 10, and blank fields 11. Color measurement fields 10 can be arranged in the area of ​​the center mark 8, since this reverse print test strip 7 is located on the side of the sheet facing away from the sheet brake. Furthermore, coded register marks are preferably present in the reverse print test strip 7 and / or side identification marks are provided, by which the measured sheet side can be automatically assigned by the quality control device.

[0027] Regarding the operating principle: The measuring strips (front printing measuring strip 6 and / or back printing measuring strip 7) are designed to overlap at least partially and preferably assume the same position on the sheet when it is turned over, i.e., rotated 180° around the longitudinal axis of the sheet (corresponding to the sheet travel direction). A color measuring field 10 of a first measuring strip is preferably located opposite a free field 11 of a second measuring strip. Similarly, a color measuring field 10 of the second measuring strip is preferably located opposite a free field 11 of the first measuring strip. This enables proper quality control. A paper whiteness measuring field 12 of one measuring strip is preferably always located opposite a paper whiteness measuring field 12 of the other measuring strip. Furthermore, it is possible to integrate center marks, register marks, and / or page identification marks in one or both measuring strips. List of reference symbols used 1 transfer drum 2 storage drums 3 reversing drum 4 pressure cylinders 5 rubber cylinders 6 printing strips 7 back pressure measuring strips 8 Measuring strip center 9 color zone width 10 color measurement fields 11 free field 12 Paper whiteness measuring field

Claims

[1] Measuring strip arrangement for a double-sided coated substrate, wherein at least a portion of the measuring strip on one side of the substrate overlaps with at least a portion of the measuring strip on the other side of the substrate, characterized by , that at least one measuring strip in the middle of the machine width of a machine coating the substrate has a reduced coating, that a color measurement area of ​​a measuring strip is opposite an area not used as a color measurement area and / or that at least one measuring strip contains a center-of-arc marker. [2] Measuring strip arrangement according to claim 1, characterized by , that at least a partial area of ​​the measuring strip on one substrate side overlaps with at least a partial area of ​​the measuring strip on the other substrate side, taking into account the functionality of the measuring surfaces of the measuring strips. [3] Measuring strip arrangement according to at least one of the preceding claims, characterized by that opposite paper white measuring areas in both measuring strips are unprinted. [4] Measuring strip arrangement according to at least one of the preceding claims, characterized by that one or both measuring strips contain a registration mark and / or a side identification mark. [5] Measuring strip arrangement according to at least one of the preceding claims, characterized by that one or both measuring strips contain a coded register mark. [6] Measuring strip arrangement according to at least one of the preceding claims, characterized by , that the measuring strips on both substrate sides of the same substrate overlap at least approximately completely.

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