EP1300243A2 - Method and means for determining the position of a printed web - Google Patents

Abstract

Method for determining the position of a printed paper web (44) in a print machine, especially a rotary printing press, whereby: reference values for position determination are gained from a preliminary printing stage; at least a part of a print image on the paper web is measured using a sensor (43); the reference values are compared with the image data acquired with the sensor; and the position of the paper web is determined from the result of the comparison. <??>An Independent claim is made for a device for determining the position of a printed paper web in a rotary printing press using a CCD, CMOS or a linear camera and a contrast sampler.

Description

The invention relates to a method and a device for detection the position of at least one printed web, preferably a paper web in a printing machine, in particular for determining the cutting position of a printed paper web in a rotary printing press for newspaper printing.

Newspapers are mainly produced by offset printing. there several paper webs are unwound from rolls in the printing units printed and finally folded in the folder and cut. While one Paper web runs through the machine, it is constantly in one tense state.

In wet offset printing, paper comes into contact with water and paint, causing the elongation properties of the paper are changed. The addition of Water and color is not the same for all printing works. The ways, which the run through individual paper webs, have different lengths. The Elongation properties vary between different types of paper, and even within the same paper type, there is difference in Expansion behavior of the paper.

Double-width paper webs become two after printing in the direction of travel or more strands split. The individual strands of a paper web can go through different paths over turner bars before they multiply Bundles are merged.

The different strands are added before entering the folder multilayered bundles merged and through funnels in the direction of the Folded tracks. Subsequently, the bundles in the folder are transverse to Direction of cutting cut so that the cut outside the type area of the Pages lies. Errors of the cutting position lead to the printed newspapers are not salable.

The cutting position can be adjusted by the printer by Register rollers the web length between printing unit and cutting blade or Cutting cylinder is adjusted. It is also possible, the cutting position by the same Adjust the angular position of the printing cylinder to be printed and thus to dispense with a register roller, what also as a virtual Main register is called. Through the register rollers of the secondary registers The cutting positions of the individual strands of a paper web can be independent be adjusted from each other.

Difficulties in correctly cutting the bundled webs in the Folder arise from the different ways of each Orbits and strands, and the different strains that the individual paper webs and strands running through the printing press experience.

When similar productions are repeated, the appropriate positions are the Main registers and secondary registers are known and can be at the start of the Production runs are more or less exactly preset. Most of the time Printer but still the cutting positions at the beginning of the production run of Hand adjust. This results in a lot of paper copies and a Loss of time during production.

Methods are known which provide automatic control of the cutting position enable. Here, special markings, so-called brands, printed, the multilayer before the convergence of the individual strands Bundles at the funnels detected by suitable optoelectronic sensors and thus provide readings necessary for automatic measurement and Control of the cutting position can be used.

For example, a large measuring mark on the printed paper web through a simple optoelectronic sensor, e.g. a contrast button, be detected. However, large brands affect the appearance of the printed product, e.g. the newspaper. Smaller brands, which are less annoying require more sophisticated optoelectronic sensors, e.g. CCD cameras, in Connection with digital pattern recognition or image data processing. in the general, the technical effort to recognize the marks is greater, the smaller these are.

Furthermore, methods are known which without the use of print marks the Automatically measure and regulate the cutting position. The cut register becomes set manually by the printer from the control desk first. Than it will be by a scan of the printed image on the paper web by optoelectronic Sensors formed a reference signal. The cutting position is then through Comparison of the current measurement signal with the reference signal automatically certainly. The disadvantage of this method is that the printer first the Manual cutting position must be set. This means that the cutting position at Starting a new production run can not be controlled automatically immediately can. It is also not possible, the cutting position in flying Change of expenditure without manual interventions. The manual intervention cause spoiled copies and lost time in production.

Another way to detect cutting position errors is from DE199 10 835 C1 and consists in scanning the printed image in two places. The first scan at the output of the print engine forms a reference that coincides with the Sampling before the funnel inlet can be compared. From the correlation of the signals, the positional error between the two measuring locations can be determined which can then be automatically corrected by appropriate regulation. The disadvantage of this method is that only the positional error between the two Measuring points is corrected and that multiple sensors must be used.

In another known from DE 195 06 774 A1 method is with a sensor detects a magnetic field of a mark. This procedure requires the printing of magnetizable marks, for example by colorless ink with metal particles and has the disadvantage that these marks by an additional Printing unit must be applied.

It is an object of the invention to provide a method and an apparatus which the position of a printed paper web in the running direction of the paper web Automatically in each without the use of printed stamps Machine state can determine. A preferred application is the automatic measurement and control of the cutting position of printed Paper webs in rotary printing machines for newspaper printing.

This object is solved by the features of the independent claims. Advantageous embodiments will be apparent from the dependent claims.

According to the invention in the method for determining the position of a printed paper web in a printing press, in particular in one Rotary printing machine for newspaper printing, reference values for Position determination or position determination from the z. B. digital or obtained analog image data of the pre-press or the artwork.

With one or more sensors, such. B. optoelectronic sensors, is the print image or a part of the print image on the paper web in the Captured press. The signals measured by the sensors become advantageously prepared for suitable digital measured values.

The reference values of the prepress or the print templates are then with compared to the measured values, z. For example, the correlation of these values is examined or calculated. From the comparison of the reference values with the measured values can the position of the printed paper web in running direction can be calculated. Thus Can easily do without attaching an additional mark in the print image the position of a printed paper web can be precisely determined.

The digital or analog image data from the publisher or prepress may be e.g. in the form of the image content of multicolored newspaper pages present and e.g. in the form of files in Postscript format or PDF format to be delivered.

The digital image data from the publisher or from the prepress can for example, in the form of the image contents of the printing plates. The Image data of a multicolor newspaper page are usually by raster Image Processing (RIP) and into the image data of the printing plates for the Basic colors cyan, magenta, yellow, black separately. So arise from the digital image data of a colored newspaper page the digital image data of the associated printing plates. The separated image data of the printing plates become also referred to as bitmaps, RIP pixel maps or separations. The separated Image data of the print templates may e.g. delivered as files in TIFF-G4 format become.

From the digital image data from the publisher or the pre-press can Reference values are calculated. The reference values may e.g. the Specify the brightness gradient on a narrow strip of a newspaper page.

An opto-electronic sensor in the printing machine, which increases the brightness the corresponding strip of printed paper web, then becomes a provide similar brightness when the printed paper web on the Sensor is moved past.

By comparing the measured values with the reference values, e.g. through correlation of the measured brightness curve with that from the digital image data of Prepress calculated brightness gradient, then the position of the Paper web to be determined in the direction of travel.

The thus determined position of the printed paper web is advantageous in Direction of movement for automatic control of the cutting position of the printed Paper web used in printing presses.

The inventive device for determining the position of a printed Paper web in a printing machine, in particular a rotary printing machine for newspaper printing, includes a data processing system for calculating the Reference values from the preferably digital image data of the print original or the Prepress.

Furthermore, at least one preferred optoelectronic sensor for Observation of the printed paper web provided, which at least one Part of a print image on the web can capture.

The reference values obtained from the digital image data of the prepress are compared in a comparison device with the measured values, which of the optical sensor or sensors were recorded to from the difference or correlation of reference values and measured values the Determine the position of the printed paper web. Is the correlation too low? an error message can be generated.

Advantageously, the device according to the invention also has a control, with which using the thus determined actual position of the printed Paper web in running direction, the cutting position of the paper web, e.g. by the Controlling a register roller, can be controlled.

Below are advantageous embodiments of the invention Method and apparatus of the invention are described, wherein the invention by way of example with reference to a preferred embodiment of a Cutting position measurement and control is described. However, the invention also for determining or regulating the position of a printed paper web used elsewhere or for other purposes in a printing press become.

Through the evaluation of preferably digital image data from the publisher or the Pre-press and the use of suitable optical sensors for observation the printed paper web in the printing press can cut position errors automatically measured and corrected by regulation.

From the digital image content from the publisher or from the pre-press can reference values are calculated using a suitable method. By mounted as close to the cutting cylinder in the printing press opto-electronic sensors which capture the printed image on the paper web, measured values are supplied, which are compared with the reference values can.

By comparing the measured values with the reference values in one Calculating device by means of suitable methods, in particular suitable Correlation method, the actual value of the position of the printed paper web is in Direction determined.

The thus determined position of the paper web in the running direction can subsequently be fed to a cutting position controller as an actual value. The cutting position controller can then by comparing the actual value with a predetermined setpoint the Automatically regulate the cutting position. The control value of the cutting position controller can be for the control of main register, secondary register, bundle register or one virtual registers are used.

It is possible with this method, without the application of an additional Feature in the print image, the cutting position automatically at any time to measure and to regulate. It is an automatic startup of a printing press without manual Interventions to correct the cutting position possible. Even with flying Change of expenditure, the cutting position can be regulated automatically become.

The formation of the reference values can be done by calculation from the image data of the Pre-press done. The reference values can be derived directly from the Print template, from the non-screened image data, from the rasterized and color-separated image data, or from the data of scanned printing plates or Films can be calculated by a suitable method. The reference values can depend on the optical sensors in the printing press by means of a Calculator so normalized and prepared that a simple comparison or a direct correlation of the reference values with the measured values is possible.

It can e.g. only a narrow strip of the printed paper web in the direction of travel of the web, e.g. as optical sensor a contrast scanner is used, which reduces the reflected light intensity on the narrow Image strip on the paper web measures and thus a curve of the brightness curve along this picture strip supplies. It can be beneficial through Optimization methods a particularly suitable image strip can be selected so that a brightness profile with a significant signal curve is measured. The Reference values and the measured values in this case can be, for example, in one-dimensional arrays of brightness values are stored.

When using an optical sensor system with CCD camera can large parts of the printed image are compared. The corresponding reference values and metrics can be stored in multi-dimensional arrays, for example become.

On the printed paper web is provided with a suitable optoelectronic Sensor system recorded the printed image. This can be done, for example Contrast, CCD CMOS cameras or line cameras are running. The Recording may e.g. continuously, e.g. by forming a Correlation coefficients the position of the printed paper web in the running direction can be determined.

Alternatively, a partial detection of the printed paper web with Help of a synchronization signal possible. The starting point of the image capture is while e.g. synchronously with the rotation of the cutting cylinder in the printing machine at each revolution at a certain angular position of the cutting cylinder respectively triggered by a start pulse, which are supplied by a position sensor can.

When using a contrast button, the amount of reflected light along a narrow image strip detected in the direction of the paper web. The way obtained signals can be digitized by a computer and conveniently stored in a one-dimensional array of measurements become. It is advantageous that several contrast scanners distributed across the web so that a particularly suitable image strip can be selected. It is equally advantageous that these contrast buttons by a manual or automatic positioning unit on a particularly suitable strip of Print image can be positioned, wherein the positioning unit is formed can be that z. B. a sensor dynamically to the printing web continuously a determined optimum position is postponed.

When using CCD cameras, CMOS cameras or line cameras the whole print image or parts of it will be used to determine the location of the recorded on a printed paper web. The data gained thereby can conveniently stored in a multi-dimensional array of measurements become.

By comparing the measured values with the reference values, the position of the printed paper web determined. It is particularly appropriate for the Comparison to use correlation methods or Fourier analyzes.

Figur 1

den Datenfluss bei der Berechnung der Lage einer bedruckten Papierbahn;

Figur 2

Beispiele für Referenzwerte und Messwerte;

Figur 3

Beispiele für einen einfachen Bilddateninhalt aus der Druckvorstufe und das entsprechende Druckbild auf der Papierbahn;

Figur 4

eine beispielhafte Anordnung zur Bestimmung der Schnittlage einer bedruckten Papierbahn in einer Druckmaschine; und

Figur 5

verschiedene Arten von Bilddaten in der Druckvorstufe.

The invention will be explained in more detail with reference to the following figures. Showing:

FIG. 1

the data flow in the calculation of the position of a printed paper web;

FIG. 2

Examples of reference values and measurements;

FIG. 3

Examples of a simple image data content from the prepress and the corresponding print image on the paper web;

FIG. 4

an exemplary arrangement for determining the cutting position of a printed paper web in a printing press; and

FIG. 5

different types of image data in prepress.

Figure 1 shows the data flow in the calculation of the position of a printed Paper web using digital image data of the prepress. From the Image data 1 of the precursor become reference values 3 in a computing unit 2 calculated. From the measuring signal 4 from one sensor or from several Sensors that capture the print image on the paper web are in one another unit 5 the measurement signals 4 to 6 measured values, which with the Reference values 3 can be compared in a comparison unit 7. By Comparison of the measured values 6 with the reference values 3, a signal 8 is determined, which indicates the position of the printed paper web.

FIG. 2 shows examples of reference values 11 and measured values 12 and shows by way of example, how the layer 14 of the printed paper web by comparing the Reference values 11 and the measured values 12 can be determined. The Reference values 11 are shown in a diagram in which the horizontal axis 10 the way in the vertical direction with a picture from the Prepress and the vertical axis 9 indicates the brightness. In this example the reference values 11 describe the brightness progression to a narrow one vertical stripes of the artwork, z. B. a multi-colored newspaper page. The Measured values 12 in this example describe the brightness progression on one corresponding strips of the printed paper web in the direction of the Paper web, shown above the axis 13. The reference values 11 and measured values 12 in this example show similar brightness gradients. By comparing the Brightness gradients of the measured values 12 and the reference values 11 can be the Position 14 of the printed web absolute or relative to a fixed point be determined.

FIG. 3 shows examples of a simple image data content 31 from FIG Prepress and the corresponding print image 33 on the paper web. It will shown as an image strip 32 from the image template of the prepress and a corresponding strip 34 selected from the printed image 33 on the paper web can be.

Figure 4 shows an exemplary arrangement for determining the cutting position of a printed paper web in a printing machine. Digital image data 50 from the Prepress are sent to a device 49 for calculating the position of printed paper web delivered.

The print image on the paper web 44 is through an optoelectronic sensor 43 sampled, which is arranged as close to the cutting cylinder 41. The Measuring signals 46 of the optical sensor 43 are connected to the position of the Cutting cylinder 41 synchronized. For this, the angular position of Cutting cylinder detected with an angular position sensor 42 and then the angular position signals 45 for the synchronization of the measuring signals 46 of optical sensor 43 used in a synchronization device 47. The Synchronized measurement signals 48 of the optical sensor 43 have such a fixed Reference to the angular position of the cutting cylinder 41 and thus to his Cutting position. The synchronized measurement signal 48 of the optical sensor 43 is sent to the device 49 for calculating the position of the printed Paper web delivered, with a corresponding position signal 51 issued becomes.

Figure 5 shows various types of image data in prepress. The image data B of a page content, e.g. a multicolor newspaper page, are e.g. in the Postscript format or in PDF format. From the image data B of a Page content is raster image processing (RIP) image content for the corresponding printing plates for the process colors Cyan C, Magenta M, Yellow Y and Black BK calculated. The rasterized and color separated image data of the Printing plates are e.g. shown in TIFF G4 format.

Claims (12)

Method for determining the position of a printed paper web 44 in a printing press, in particular a rotary printing press, wherein: a) reference values 3, 11 are obtained for the position determination from image data 1 of the prepress stage; b) at least part of a printed image on the paper web is detected by at least one sensor 43; c) the reference values 3, 11 obtained from the image data 1 of the prepress stage are compared with the measured values 46 acquired by the at least one sensor 43; and d) the position 8, 14, 51 of the printing web 44 is determined from the comparison result. Method according to claim 1, wherein the reference values 3, 11 for the Position determination from the image contents of a print template, in particular the image data of a multi-colored newspaper page, or from the rasterized and color separated image data for exposure of the printing plates or from the Image data of scanned printing plates or scanned films. Method according to one of the preceding claims, wherein as a sensor 43 an optoelectronic sensor, in particular a CCD camera and / or a CMOS camera and / or a line camera and / or a Contrast button is used. Method according to one of the preceding claims, wherein the at least a part of the printed image on the paper web 44 in synchronism with Movement of a machine part, preferably synchronously with the rotation of the Cutting cylinder 41, is detected. Method for controlling the position of a printed paper web in one Printing machine, which with the method according to one of claims 1 to 4 determined position of the printed paper web for regulation, is used in particular as an actual value. Method according to one of the preceding claims, wherein the position the paper web and / or cutting position of the printed paper web in one Rotary printing machine with a main register and / or secondary register and / or bundle registers and / or a virtual register and / or regulated. Method according to one of claims 1 to 4 for the detection of Misplacements in the arrangement of printing plates on the Printing cylinders in a printing press, with an error message is generated automatically when comparing the measured values with the reference values, the correlation between the measured values and the Setpoints is too low. Method according to one of claims 1 to 4 for the determination and / or Control of the relative position of the printed images on the recto printing side a paper web relative to the printed images on the reverse side of the same paper web. Device for determining the position of a printed paper web 44 in a printing machine, in particular in a rotary printing press with: a) a data processing device 2, which determines reference values 3 for position determination from image data 1, 50 of a prepress stage; b) at least one sensor 43 for detecting at least a part of a printed image on the paper web 44; and c) a comparison device 7, 49 which determines the reference values 3 and the measured values 6; 46, 48 of the at least one sensor 43 compares with each other to determine therefrom the position 8, 14, 51 of the printed paper web. Apparatus according to claim 9, wherein the sensor 43 is an opto-electronic Sensor, in particular a CCD camera and / or a CMOS camera and / or a line camera and / or a contrast scanner. Device for controlling the position or cutting position of a printed article Paper web in a printing press with a device according to claim 9 or 10 and a control device for controlling the position of a Paper web, which the determined position of the printed paper web as Input signal used. Device according to one of claims 9 to 11, wherein the Comparative device and / or the control device at least one of Perform in the claims 1 to 8 defined method steps.

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