EP1744885A1 - Inline measurement and regulation in printing machines - Google Patents

Abstract

Spectral, densitometric, or color measured values are detected on sheet printing materials during the printing process in a sheet-fed printing press. The measured values are determined on sheets as they are moving through the printing press and the measured values are used in real-time by a computer to control parameters for controlling the printing process in the sheet-fed printing press.

Description

Inline measurement and control in printing machines

The present invention relates to a method for recording spectral, densitometric or color measurement values on substrates during the printing process in a printing press.

With every printing process, the aim is to achieve that the printed copies correspond as closely as possible to the original print template. This requires extensive quality control and monitoring of the printed substrates in a printing company by the printing staff. According to the prior art, this is done by visual inspection by the operating personnel and by the use of optical measuring devices which measure either densitometrically or spectrally. In the case of sheetfed offset printing presses, a sheet must be removed from the delivery, which is usually placed on a sheet support desk. On this desk, the sheet is illuminated with a standardized lighting source and measured with the help of optical measurement technology or visually inspected. However, this process takes time, and this is aggravated by the fact that the printing press continues to print during the quality control and may result in waste if the inspected sheet does not yet meet expectations. Since a printing press requires a certain number of sheets after each interruption until the printing process has reached a stable state, waste cannot be prevented by quickly switching off the printing press during the media check. In addition, to assess the printed sheet, printing personnel are required who are not available for other activities during quality control. Since many setting options, particularly in the inking unit area, have to be made during the set-up phase of a printing press, there is normally a waste of between 150 and 400 sheets. To make matters worse, the printing process is generally difficult to reproduce, since the printing result depends on a large number of parameters such as color, temperature, water, paper, printing speed, rubber blanket, nature of the printing plate, etc. All of these parameters mostly change in some form from print job to print job, it is It is therefore not sufficient to save the setting of a print job and to call it up for repeat jobs in the same way. For example, the air temperature or humidity could have changed in the meantime, so that new settings must also be made for the same print job due to changed environmental conditions.

Since the printed newspaper webs cannot be easily removed from the press in web offset printing presses, there are already measuring systems that try to record the quality of a printed web spectrally or densitometrically. A method for operating a scanning device for optical density measurement is known from DE 10023 127 AI. Here, the printed web is guided in a web offset printing machine, which leaves a last printing unit, over a deflection roller, a scanning device for optical density measurement, color measurement or spectral measurement being attached parallel to the deflection roller. In this way, the quality of the printed web can be determined. The description of the exemplary embodiments suggests that the method disclosed in the application can also be used for printing on sheet-shaped substrates. However, a precise description of how this actually has to be done cannot be found in the application, in particular not solving the problem that, in the case of sheet-shaped printing materials, the sheet-shaped printing materials cannot be guided over a deflection roller as in DE 123 127 AI , because sheet-shaped printing materials must be held at least at one point by a holding device such as a gripper or the printing nip of a printing unit. For this reason, the device disclosed in DE 123 127 AI is not suitable for the quality assessment of sheet-shaped substrates during the printing process in sheet-fed offset printing machines.

Furthermore, from the Ifra Special Report 3.35 mine measuring systems for web-fed rotary printing presses are known, which operate with a closed control loop, i.e. the measured values recorded by the inline measurement for assessing the print quality of the printing substrate web are forwarded directly to a computer of the web-fed rotary printing press and processed there. The computer then corrects any Deviations automatically and changes settings of the printing press. However, this method also has the disadvantage that only deviations can be corrected in a frame that is permitted by the control of the printing press. In particular, corrections of the color profile are not automatically possible, since they can only be made in connection with the data from the prepress stage. Furthermore, in the known inline measurements, only the data of a single one, namely the current print job, are taken into account when correcting the settings in the printing press.

It is therefore an object of the present invention to provide a method which enables automatic correction of deviations in the printing press over several print jobs.

According to the invention the present object is achieved according to claim 1. Further advantageous embodiments of the invention can be found in the subclaims and the drawings. The current state of the printing press system can always be determined by means of the acquisition of measurement data on sheets transported through the printing press, and corrections can thus be made immediately, which is otherwise not possible with sheet-fed printing presses. This regulation can take place during the setup phase but also during the production run. Corrections are, however, required much less frequently during production, since the condition of the printing press is more stable here. That is why there are not so many measurements to be carried out in production printing, which is why the measurement strategy can be adapted to the current condition of the printing press. This is described in more detail below in the text.

In an advantageous embodiment of the invention, not only are spectral, densitometric or color measured values continuously recorded on the produced substrates during the printing process in the printing press, but the measured values are evaluated in a computer of the printing press or a separate computer and at least those deviations which are not sufficient by changing the Settings on the press can be avoided, are forwarded to the control in the prepress. This is relatively easy to accomplish, in particular, in what is known as computer-to-plate technology (CTP), since these digital prepress stages also have computers which can receive the corresponding data from the computer of the printing press. In this way, a closed control loop is started, starting with the finished substrate via the printing press and back to the printing press. The measured values sent by the printing press or their assessment can thus be taken into account in the prepress stage during the production of the printing plates and thus also deviations which cannot be compensated for in the printing press alone can be corrected. It should be noted that color measurement values are understood to mean values in color spaces such as the Lab space, the RGB color space or other unambiguous color spaces. Measured values can also be taken into account across multiple print jobs when creating printing plates, so that over many print jobs there is a continuous improvement process in the entire production chain from the scanner in prepress to the end product in the press. In this way it is possible to carry out an improvement process without having to record special test forms in a complex process. Since in a digital workflow, as is usually the case today, prepress with scanners, platesetters, raster image processors and the printing press are networked with each other, this data can also be exchanged without additional hardware or with little additional effort.

In a first embodiment of the invention it is provided that the measured values recorded are fed to a computer and the computer uses the measured values to create or correct a color profile when controlling inking units of a printing press. For color reproduction true to the original, it is essential to link the color profile of the printing press with the color profile of the prepress stage, so as to minimize any discrepancies between the original and the final product. It is possible to determine the color profiles of the printing press and the data obtained from the prepress stage by inline measurement Relate prepress to each other and correct the color profile of the press in the event of any deviations. This means that the color profile of the printing press is automatically checked and adjusted if necessary without the intervention of the printing staff.

In a further or alternative embodiment of the invention it is provided that sensors for recording the measured values are available and for color calibration are calibrated at certain time intervals by means of a calibration device. Since measured values are continuously determined with an inline measuring method, it must be ensured that these measured values are comparable with each other. For such an accurate measurement, in addition to a one-off calibration during commissioning, a regular system calibration rank is necessary to take into account changes in the measured values due to heat or wear, age-related changes in lighting sources or contamination. For this purpose, the inline measuring device present in the printing press has a calibration device which is put into operation at certain intervals. This ensures that the mine measurement system is constantly recalibrated and operational errors are avoided.

It is further provided that a calibration surface with associated color measurement values, which are stored in the computer, is present as a reference value for the calibration device. The measuring heads for spectral, densitometric or color measurement in the inline measuring system are directed at a calibration area at certain intervals and recalibrated. The color value of the calibration surface is known in the measuring system, so that the value determined by the measuring head can be compared with the stored color value. If deviations occur, the measuring electronics of the measuring head are recalibrated accordingly, ie a correction is made in such a way that the measured value is adjusted to the stored color value in the computer. Through this calibration, soiled measuring heads can still provide usable measurement results at least over a relatively long period of time, even without calibration after a relatively short time would require cleaning of the entire measuring device or replacement of an aging lighting device.

It is advantageously provided that the calibration surface is white. For colorimetric reasons, the calibration measurement should ideally take place on a standardized white surface, which is why the calibration surface is carried out in precisely this color.

Furthermore, it is provided that one or more calibration surfaces are arranged in the channel of an impression cylinder in the extension of the impression cylinder surface. Since the inline measuring system has several measuring heads, preferably eight measuring heads with 32 color zones, distributed across the width of the substrate, all measuring heads must be set and checked using calibration areas. However, since the lateral mobility of the measuring heads is restricted, it is not possible to move all measuring heads to a calibration surface attached to the side. It is also important that the distance between the calibration surface and the measuring head corresponds exactly to the distance between the measuring head and the substrate surface. In order to be able to attach the calibration surfaces for all measuring heads across the entire width of the printing material, they are arranged in the channel of an impression cylinder in the extension of the impression cylinder surface. As a result, the calibration surfaces are at exactly the same distance from the measuring heads as the surface of the substrate and are not in the way during the printing process.

In an alternative embodiment of the invention it is provided that at least one calibration surface is arranged laterally outside the surface of the impression cylinder between the side wall and the impression cylinder. Calibration surfaces that are located in the pressure channel have the major disadvantage that they become dirty during the printing process. On the other hand, the calibration surface is outside the printing cylinder surface, e.g. B. in the area of the side wall, it is less exposed to contamination there. This avoids frequent cleaning operations on the calibration surface. In a particularly advantageous embodiment of the invention it is provided that the sensors are measuring heads and the calibration values determined by the calibration of a measuring head are converted into calibration values for further measuring heads by means of the computer. This method is also known as transfer calibration, since here not all measuring heads are calibrated on their own calibration surfaces, but rather a calibration surface outside the cylinder surface, e.g. B. arranged between the side wall and impression cylinder is sufficient. However, this calibration area can only be carried out by one of the measuring heads that grasp the edges of the printing material, since only these measuring heads can be moved laterally beyond the limitation of the printing cylinders. The other measuring heads are calibrated by a transfer calibration by moving the entire measuring bar further by a travel distance that corresponds to the distance between the measuring heads. This means that only a single measuring head has to be calibrated in the edge area on the calibration surface, while in the next step the measuring bar is moved by the distance between the measuring heads, so that this first calibrated measuring head can detect the zone of the second measuring head. This also applies analogously to the other measuring heads, ie each measuring head now captures the measuring zone of the measuring head lying next to it. During this calibration measurement, the measuring heads are either aligned to a white printing material or to a color-printed printing material. However, this is irrelevant for the calibration measurement process. Has z. For example, if the second measuring head next to the first measuring head, which is calibrated over the calibration surface, is currently detecting a certain shade of blue, this blue tone is detected in the next step by the first calibrated measuring head. Now the measured values of the first and second measuring heads are compared with one another and, if necessary, the values of the second measuring head are corrected. So the transfer calibration is on the second

Measuring head completed and the possibly corrected measured values of the second measuring head can be compared with the measured values of the third measuring head. This is done in an iterative process for all other measuring heads, so that only a single measuring head has to be calibrated using a calibration surface, while all others are calibrated in one step by means of arithmetic comparisons. Furthermore, it is provided that at least one calibration surface can be closed by means of a cover. With such a cover, the calibration surface can be reliably protected against contamination during the printing process. The cover is only opened when a calibration process has to be carried out. This eliminates the otherwise recurring need to clean the calibration surface.

It has proven to be advantageous that the calibration is carried out with the aid of an external measuring device. Since all parts housed in the machine are prone to contamination and malfunction, the transfer calibration can also be carried out using an external measuring device. For this purpose, a permanently installed measuring device or a hand-held measuring device is available on the control panel, which has its own built-in calibration area, calibrates itself on this area at regular intervals and with which the currently printed substrate is measured. Since this substrate is measured beforehand by the mine measuring device and its measuring heads and the

When the printing press is removed, the values determined with the handheld measuring device can then be passed on directly to the measuring electronics in the measuring bar, and the corresponding calibration can be carried out in this way. Of course, the substrate in the unprinted state d. H. be measured as paper white with the handheld measuring device and then in the printing press using the measuring heads of the mine measuring device. The transfer calibration can also be carried out with an external measuring device. The calibration in the pressure-free area can be carried out particularly advantageously directly after the grippers, since the sheet is guided ideally here and paper white is also always available. This edge area usually has an unprinted area of 6-12 mm and is completely sufficient for the measurement.

The external handheld meter can also be used for another purpose. The sheet is measured in the machine for a variety of reasons with the aid of a polarizing filter, i.e. all measured values are recorded in polarized form. However, the control of the printing press works with unpolarized values, since the information from the prepress stage is only available in unpolarized form, ie the data recorded Measured values must be converted into unpolarized values. To do this, a mathematical relationship between polarized and unpolarized values must be stored in the printing press. This relationship can be established using the handheld measuring device, which measures unpolarized. For example, a sheet is measured polarized with the mine measuring device in the printing press and unpolarized and polarized outside the machine with a hand-held measuring device. If this measurement is carried out over several arcs, a relationship between the polarized and the unpolarized measured values can be seen. This relationship is then stored as a correction function in the computer of the printing press, so that the values can be converted into one another at any time.

In a further embodiment of the invention, it is provided that specific color values are stored in the computer for each measuring head, the ratios of these color values to one another are stored in the computer, and a signal is output when the stored measured value ratios change. Such a device detects the contamination of the mine measuring system. Each spectrometer has e.g. B. on delivery a white measurement as a tialization parameter. These white measurement values belonging to the respective measuring heads are stored in relation to one another for all measuring heads. Paper white measurements are then continuously carried out during the printing process and the measured value relationships determined in this way are compared with the values stored in the measuring electronics. As soon as these conditions change, whereby a certain tolerance range can be set, this is evaluated as a signal for contamination. In this case, the operating personnel are shown an acoustic or visual signal, after which the measuring heads must be cleaned.

Furthermore, it is provided that a first measuring head detects its own and the color zone of a second measuring head lying next to it, and the second measuring head also detects its own zone and that of the first measuring head, and the recorded measured values are compared with one another. In this way, a cross comparison between the individual measuring heads of the measuring modules of a bar-shaped mine Measuring device in the printing machine enables. First, all measuring heads measure a color zone on a substrate at the same time, then the entire measuring bar is moved laterally so that each measuring head can now record the measuring location of its neighbor. If the calibration is carried out correctly, these measured values must not differ or only differ within very narrow tolerance limits. Show the measurements, however

Deviations, this also suggests contamination on the optics of the measuring heads.

A further possibility in the detection of soiling on the measuring system results from the fact that measurements are carried out on at least one color zone of a measuring head on a light / dark edge, the measuring head in uniform steps from one side beyond the light / dark edge is moved across the light / dark edge to the side on this side of the light / dark edge and the measured measurement values are compared with the known structure of the measuring head. Such a light / dark edge z. B. the transition from paper white to the color area. This measuring area is now to be traversed by a measuring head as follows. First, the measuring head measures on the side of the light / dark edge, which shows the paper white. Then the measuring bar is z. B. moved in 10 steps across the width of the measurement field of the light / dark edge, 10 measurements being carried out. That means the last measurement takes place completely in the color area of the measuring field. When evaluating these measurements, the intensity measured in each case is plotted against the spatial offset, the distance between the last measured white value and the first measured color value having an exact optical image corresponding to the known structural width of the measuring range of the spectrometer of the measuring head. This comparison is made by means of the measuring electronics and the values of the structure of the

Measuring range of the spectrometer made. If there is a discrepancy here, this is also an indication of pollution.

Furthermore, it is provided that an illumination device is present, a dark measurement is carried out before the actual measurement by a measuring head, and the measurement value recorded here is that of the one with the illumination device switched on color measurement is subtracted. In order to be able to scan the surface of the printing material, it must be illuminated with an illuminating device in the vicinity of the measuring head. However, since there is a distance of several centimeters between the substrate and the measuring bar, extraneous light can also fall into the area between the substrate and the measuring head / lighting device. This falsifies the measurement results and must be compensated accordingly. One possibility is to carry out a dark measurement, ie the lighting device is initially switched off and a measurement is carried out with the lighting device switched off. Then the lighting is switched on and measurements are taken with the lighting device switched on. The order is irrelevant, because for the correction only the measured value acquired during dark measurement has to be subtracted from the measured value acquired with the lighting switched on. Stray light or extraneous light sources are e.g. B. slots in the machine through which the ceiling lighting of a printing house or daylight can fall, but there are also light sources in the machine itself such as e.g. B. UV / TR dryer or other sensors that work with light and whose light can interfere with the measurement process. A small change can also be used to compensate for periodically operating extraneous light sources. First, a dark measurement is carried out, which means that the influence of extraneous light is recorded for the first time. Then a light measurement is carried out and then again a dark measurement in which again only the influence of extraneous light is experienced. If the extraneous light source changes, the measured values of the two dark measurements differ from one another and the computer can recognize whether the extraneous light has increased or decreased during the bright measurement by comparing the two measured values, since it can compare the measured values before and after. The gradient of the change in extraneous light can thus be determined, so that the influence of extraneous light from the bright measurement can be reliably calculated even in the case of changing, in particular periodic, extraneous light.

A further possibility for correction in the case of incident extraneous light is that the color measurement of a first measuring head by means of a second

Measuring head a measured value on a white background of a printing material and the the white reference value determined in this way is used to correct the color measured values determined with the first measuring head. For this purpose, the second measuring head must be spatially separated from the first measuring head, which always has to take a measurement on paper white. This can e.g. B. the edge area of the substrate. The white reference value determined with the second measuring head is included in the calculation of the color or density values and thus the influence of the ambient light is compensated.

There is another way of compensating for extraneous light, namely that any existing light sources are switched off, hidden or dimmed down to an uncritical value during the acquisition of measured values on the substrate by one or more measuring heads. In this case, the measuring electronics of the measuring heads are networked with the computer of the printing press, so that light sources in the printing press are switched off during the measuring process. So z. B. the influence of extraneous light by a UV dryer during the measurement is avoided by briefly switching off the dryer during the measurement and then switching it on again. Another possibility is to hide the extraneous light source by installing a shutter (shutter) in front of the extraneous light source. This shutter then hides the extraneous light source as long as the measurement process is being carried out. It is also possible to selectively filter out spectral values of the external light source, which are in the spectral range of the measuring device, by attaching a filter which filters out the spectrum of the external light source. A similar effect can be achieved through computational merpolation. Since the spectrum of the extraneous light source is known, spectral values corresponding to the measurement spectrum are not used and instead the useless values are interpolated over the spectrum of the extraneous light source by means of the neighboring values. Peaks caused by the extraneous light source can thus be eliminated in the measurement spectrum.

The following possibility is also available for compensation of extraneous light, namely that the acquisition of measured values by measuring heads with possible fluctuations of light sources is coordinated in time by means of at least one sensor which detects the fluctuations or by means of a control signal of the fluctuating light source. Also in this case, information about the temporal behavior of the external light source must be available, ie these values must either be stored in a computer or the external light source supplies the mormations online to the computer via sensors. In this case, the measurements are coordinated by the computer in such a way that measurements are always carried out when the extraneous light source is switched off or has a minimum.

Furthermore, it is provided that several measuring heads are distributed at equidistant intervals across the width of a printing material and at the same time detect ink zones. In the large format (102 cm sheet width) in sheetfed machines, 32 ink zones extend across the entire substrate width, resulting in 192 for 6 printed colors

Measuring fields, which are to be recorded by the measuring electronics and the measuring heads. Measuring cycles over at least 192 sheets are required on a single spectral measuring head, which is not sufficient for good control. For this reason, several measuring heads are required, which are able to measure in parallel and simultaneously. Since the measuring heads are shifted by one color zone after each measuring process, 8, 16 or 32 measuring heads are particularly suitable for parallel measurements. With 32 measuring heads and 32 color zones as well as 6 printed colors, 6 measuring processes have to be carried out on 6 printed sheets. After these 6 measuring steps, the settings of the printing press can now be adjusted if necessary by setting corrected values with a new ink zone setting on the printing press. In addition to the measuring strategy mentioned, the measuring heads can also be moved in such a way that the same color is always first detected across several sheets, so that this can be regulated well and only then are the measuring heads positioned on the next color, which is then also regulated , Since different measuring strategies can be used, the measuring device must save the measured values with a time stamp and a location marker in the computer of the printing press, so that the correct references can be established at any time in order to be able to correctly compare the actually comparable measured values with one another. Then the measuring strategy no longer plays a role and the measured values can be assigned correctly at any time. In one embodiment of the invention, it is also provided that the measuring heads are positioned during the printing operation after the pressing-on phase in such a way that they record several colors simultaneously. Since the mechanics and the drive motor of the measuring beam with the measuring heads are subjected to heavy stress due to frequent measurements, a so-called economy mode increases the service life. However, since the values still change strongly in the press-on phase due to the process, frequent measurements must be carried out continuously there, while a different procedure can be selected in the press phase, because during the press phase the color values remain almost constant over time, so that it is possible to position the measuring heads over mixing fields. As soon as a tolerance deviation that is too large is recognized, the measuring bar then starts again with its frequent measurements, as in the pressure phase, which cover all fields and all zones. This allows the reason for the deviation to be measured and the regulation of the printing press to be activated accordingly.

The measuring device can also use its measuring strategy as a function of the acquired one

Change measured values. Color patches that show low noise are not measured as often as color patches with strong noise. That each color is recorded using a different measurement strategy so that more noisy colors are measured more often. When the noise fades from these colors, the measurement strategy is also changed so that the frequent measurements are reduced. The measurement strategy can also take place depending on the print image and the settings of the printing press itself. Since the data of the print image can be transmitted from the prepress to the computer, the measuring system can calculate an appropriate measurement strategy, since critical color areas in the print image are known in advance with their position and the color tone.

In a further embodiment of the invention, it is provided that the computer stores the position coordinates of print control strips applied to a printing material. The measurements at the ink zones usually take place in the area of the print control strip in printing machines. In order for these measurements to take place reliably, the measuring bar of the mine measuring system must have the position of the

Print control strip on the substrate to be known. One way is that the printer manually measures the position of the print control strip on the printing plates and enters the position coordinates of the print control strip in the computer of the machine control. Furthermore, the position coordinates can also be transferred from prepress in a networked workflow system to the computer of the printing press and used there. With both options, however, there is a risk that the position of the print control strip on the print sheet relative to the measuring heads will be changed when the printing plates are clamped in the printing press or by register adjustment. However, with the given rough position, the search area for an exact position determination can be restricted, which simplifies the work of the automatic position detection system.

It is further provided that a sensor is provided for determining the position of the print control strip on the printing material. By means of a two-dimensional sensor z. B, a CCD imager, the position of the print control strip can be determined. A pattern of the print control strip is stored in the machine control, which is compared with the image of the images captured by the CCD camera. As soon as the camera detects equality, the computer can calculate the position of the pressure control strip relative to the measuring bar and send a corresponding start signal to it, so that the measurement starts exactly when the pressure control strip comes to rest below the measuring heads. The use of a one-dimensional sensor is also suitable for detecting the position of the print control strip if the print control strip has a detection segment z. B. is preceded by a bar code. As soon as this barcode is recognized by a barcode reader, the system knows that the print control strip now follows at a certain time interval. The measurement process can thus be triggered in good time. The position detection is only necessary at the beginning of the printing process, since even larger local deviations are to be expected here. In the printing phase, the location of the markings is stable, so that the recognition segments only have to be scanned for checking at large time intervals. A particularly advantageous embodiment of the invention is characterized in that the measured values determined by the measuring heads are subjected to a plausibility test after each measurement. In the case of a mine measurement with a closed control loop, it is particularly important to automatically recognize and reject faulty measurement values, since otherwise the ink zone control sets the wrong color values and unnecessary waste is generated without the operating personnel being informed. For this reason, a mine measuring system with a closed control loop should subject the measured values to a plausibility test in order to be able to remove implausible measured values. Such a check is carried out, for example, by the correlation between the stored template of the pressure control strip and the values of the measuring bar recorded during each measuring process. This also ensures that the measuring bar always moves to the correct measuring fields. The choice of the correct type of print control strip can be checked by another algorithm, in which a sensor detects a coding field within the print control strip and checks the data coded therein. Furthermore, a plausibility check of the measured values is carried out both in the local area and in the time area for each measurement process. Limit values for deviation z. B. in the density range, which two successive or locally adjacent, lying values must not exceed. The plausibility test here is based on the fact that in the offset process the printing units only allow constant changes in the color values during normal operation, so that jumps in color density that exceed a certain order of magnitude are immediately due to errors in the measuring system. In addition, a display can be provided which informs about the state of the printing process. If the measuring system detects no or only slight tolerable deviations and corrects them by means of the machine control, the OK staff is shown on a display. If the machine is not in this stable condition, this can be seen on the display and the printing staff knows that waste is being produced.

The measuring method can also be used for indirect moisture measurement of the arch. In order to measure the moisture, the dampening solution is usually reduced until so-called "toning" occurs on the sheet in screen printing. This toning is evident Experience has shown that first at the beginning of the sheet, on the side of the sheet and in the grid fields with 70% - 90% area coverage. Then the moisture value is increased again by a certain fixed percentage. For the mine measurement, a 70% - 90% grid is introduced on the sheet in the print control strip or in positions specifically arranged on the sheet for each color on the sheet edge. From the knowledge of the area coverage of this field and the printed color density, light toning can thus be reliably detected with the measuring heads. This enables the color-water balance to be set and monitored.

The present invention is described and explained in more detail below with reference to several figures. Show it:

1: the measuring bar in the printing unit of a sheet-fed printing machine,

2: a sheet-fed printing machine for perfecting, FIG. 3: an interior view of the measuring bar,

4: a cross section through the measuring bar in FIG. 3,

5: the measuring bar from FIG. 3 in the view from below,

6: an optical fiber arrangement in the measuring bar,

7a: a light guide arrangement in the measuring bar with an optical interspace, FIG. 7b: the light guide arrangement from FIG. 7a with a reduced optical interspace,

8 a: a cross-over arrangement of measuring heads and lighting devices,

8 b: a conventional arrangement of measuring heads and lighting devices in the measuring bar,

9: a print control strip on a printing material, FIG. 10: a measuring bar with a glass underbody and a cover designed as a slotted sheet guide,

11: an open measuring bar with a closed measuring carriage,

12a: sheet held by the gripper and pressure gap during the measurement process,

12b: sheet held during the measurement process by two grippers, FIG. 12c: sheet held during the measurement process by gripper and a blowing device, Fig. 12d: sheet held during the measurement process by negative pressure and Fig. 13: attachment of the measuring bar in the printing unit of a printing press.

1 shows a sheet-fed rotary printing press 1 with a sheet feeder module 2 and a sheet delivery module 3 and four printing units 4, 5 arranged between them. Of course, this embodiment of a sheet-fed rotary printing machine 1 is only to be understood as an example, since the number of printing units 4, 5 between sheet feeder 2 and sheet delivery unit 3 does not matter for the essence of the invention. The printing units 4, 5 are connected to one another via transport cylinders 9, so that printing sheets 705 stacked in the sheet delivery 2 can be conveyed through the individual printing units 4, 5 to the delivery unit 3 and printed in the printing units 4, 5. The last printing unit 5 seen in the sheet travel direction differs from the other printing units 4 in that it has a measuring bar 6 as a scanning device for assessing the print quality of printed sheets. The measuring bar 6 is therefore housed in the last printing unit 5, since all the colors applied in the printing process are already present on the printing sheet 705 and the final state of the printing sheet is thus present. In this context, the term printing unit 4, 5 is to be understood further, since one or more of the printing units 4, 5 can of course also be coating units, sealing units or other sheet-processing units. Even if these other works are present in the printing press 1, it makes sense that the measuring beam is installed in the last work 5 in order to be able to check the sheet 705 with all the layers of lacquer. All printing units 4, 5 have an impression cylinder 7 and a blanket cylinder 8, which form the printing nip 100 of a printing unit 4, 5. Furthermore, each printing unit 4, 5 is equipped with an inking unit 13. The cylinders 7, 8 and the inking unit 13 are mounted in the side walls 14 of the printing press 1 and are driven by motors and gears present there.

The pressure gap 100 between the pressure cylinders 7, 8 can be seen more clearly in the enlargement in FIG. 1. The enlargement of the area surrounding the printing nip 100 in the last printing unit 5 together with the measuring bar 6 also shows the approximate size relationships of the cross section of the measuring bar 6 compared to the diameters of the pressure cylinders 7, 8. On the impression cylinder 7, sheet grips 101 are also attached, which guide the sheet 705 around the impression cylinder 7, receive them from the transport cylinder 9 and transfer them to the delivery arm 3. During the measuring process by the measuring bar 6, the printed sheet 705 is held on the one hand at its rear end by the printing gap 100 and on the other hand is held at its front end by the sheet gripper 101. This ensures that the curve 705 can only move minimally during the measurement process, which is important for the measurement process in that the distance between the curve 705 and the measurement bar 6 should not vary as far as possible during the measurement. The dimensions of the cross section of the measuring bar 6 in FIG. 1 are 102 mm in width and 69 mm in height for a printing machine 1 in a 102 cm sheet format on its end face. Furthermore, the measuring bar 6 is slightly inclined with respect to the horizontal, so that it runs parallel to the surface of a sheet 705 when it is guided by the sheet gripper 101 and the pressure gap 100. A sensor 15 is attached to the measuring bar 6, but can also be integrated in the measuring bar 6. This sensor 15 is an optical sensor, for example a camera, which can recognize markings on a printed sheet 705. In addition, the sensor 15 can be used to observe external light sources 800 and to trigger the measuring process by the measuring bar 6. For this purpose, the sensor 15 is networked with the measuring electronics 201 and the computer 200 of the printing press 1. Thus, the measuring process can be controlled by the sensor 15 in such a way that measurements are only made when no extraneous light 800 falls on the measuring surface or directly in the scanning device 6. The sensor 15 can consist of a combined sensor or of several separate sensors. A plurality of sensors 15 can also be attached distributed over the entire length of the measuring bar 6. The sensors 15 can also be integrated in the measuring bar 6.

FIG. 2 shows a sheet ration printing machine 1 which, in contrast to FIG. 1, is equipped with a sheet turning device 10, so that one side of a sheet 705 can be printed on in the first four printing units 4, 5 and two in the second four Printing units 4, 5 the other side. For this reason, the printing press 1 in FIG. 2 has two printing units 5, to which a measuring bar 6 is attached, since both the The front and the back of a sheet must be checked with a measuring bar 6. In order to be able to assess the final state of the printed sheet 705 here, both with respect to the front and back, the measuring bars 6 are located in the last printing unit 5 in front of the turning device 10 and in the last printing unit 5 in front of the sheet delivery unit 3 Sheet printing machine 1 in Fig. 2 the possibility of moving the measuring bar 6. I.e. the measuring bar 6 is designed to be easily removable and can also be installed in another printing unit 4. 2, connections are also made to the printing units 4 preceding the two printing units 5. For this purpose, the printing units 5, 4 designed to receive a measuring bar 6 are provided with electrical connections, which are each connected to measuring electronics 201. When the measuring bar 6 is inserted into the respective printing unit 5, 4, a corresponding coding of the measuring electronics 201 automatically informs in which printing unit 5, 4 the measuring bar 6 is currently located. The measuring electronics 201 is in turn connected to the control panel and computer 200 of the printing press 1, so that all measured values can be displayed there to the operating personnel of the printing press 1. In addition, the settings of the printing press 1 can be changed on the control panel 200 in order to control the print quality. The computer 200 of the printing press 1 is also connected to devices of the prepress stage 11 via a wired or wireless connection 12, for example also via a mernet connection. Such devices 11 are in particular

Platesetters for the production of printing plates for offset printing machines. The connection 12 to the prepress stage 11 makes it possible to use the data from the measurements of the measuring bar 6 also to change the manufacturing process in the prepress stage 11. This allows more extensive changes to be made in the printing process than would be possible simply by changing the settings of the printing press 1. The production of the printing plates can also be optimized. A handheld measuring device 202, which can be used for calibration purposes of the measuring modules 603, can also be connected to the computer 200 of the printing press 1. The inside of the measuring bar 6 is shown in FIG. 3, the measuring bar 6 being constructed in such a way that it can be fixed in the printing unit 5, 4, while a movable measuring carriage 605 is arranged inside the measuring bar 6. The measuring bar 6 extends over the entire width of a printing sheet in order to be able to reliably check the edge areas of the printing sheet. For this purpose, the measuring carriage 605 can be moved inside the measuring bar 6 in order to be able to also measure over the entire width of the sheet. To measure the surface of the printing sheet, the measuring carriage 605 in FIG. 3 has eight measuring modules 603 with 8 measuring heads 622, the measuring carriage 605 being movable in several steps or continuously, so that with 4 colors after 16 measurements, all 32 color zones over several printing sheets 705 have been measured away. For this travel process, the measuring carriage 605 is mounted in a guide rail 606, it being driven by a linear motor 604. For easy maintenance of the measuring carriage 605, it can be removed laterally from the measuring bar 6 by removing the side walls 601. For this purpose, the side walls 601 are designed to be easily removable, ie they are fastened to the housing of the measuring bar 6 with a plurality of screws.

The measuring bar 6 essentially consists of a U-shaped profile which is open on the side facing the printed sheet. In order to prevent the ingress of dirt and in particular printing ink, the open side of the U-profile is closed with a removable bottom 615, which additionally has transparent parts 616 made of glass, so that the measuring modules 603 on the measuring carriage 605 through the floor 616 of the measuring carriage 615 can scan the substrate underneath. In addition to the measuring modules 603 and their electronics, there are further devices on the measuring carriage 605. Since the measuring modules 603 also have lighting modules 623 in addition to the spectral measuring heads 622, the measuring carriage 605 must be provided with an illumination source 610. The lighting source represents a flash lamp 610, which is supplied with electrical energy by a power supply unit 612 located on the measuring carriage. The power supply unit 612 in turn and the electronics of the measuring modules 603 are connected to the housing of the measuring bar 6 via flexible electrical cables 618. The end of the flexible electrical cable 618 fastened to the housing of the measuring bar 6 ends in an electrical plug connection 619, by means of which the measuring bar 6 is connected to the electrical voltage supply of the printing press 1 and the measuring electronics 201. Electrical energy and signal transmission can be connected using a pluggable or rotatable combination plug. All electrical components, including the measuring modules 603, are mounted on one or fewer boards 631 in order to ensure short current and signal paths in a confined space.

Since there is only one flash lamp 610 on the measuring carriage 605, its flash light must be transported to the individual lighting modules 623 by means of coupling optics 611 and subsequent light guides 614. In addition to the power supply unit 612 of the flash lamp 610, there are also flash capacitors 607 on the measuring car 605 for providing the necessary energy. In addition, the measuring car 605 contains a distributor device 620 for distributing electrical energy to the individual electrical consumers and for distributing the electrical signals of the components networked with one another Measuring carriage 605. However, the scanning device 6 is not only capable of spectrally measuring the surface of a printed sheet, but it is also used to detect register marks and to evaluate them. For this purpose, the measuring carriage 605 has a right register sensor 608 and a left register sensor 613. This makes it possible to register the register marks in the marginal areas of a printed sheet. There may also be further register sensors, so each measuring module 603 may include a register sensor so that several register marks can be measured in parallel across the entire width of the printing substrate 705.

Since all of the electronics in the measuring carriage 605 are accommodated in a very small space, for example 70 percent of the volume of the measuring carriage 605 is filled with components, and a lot of waste heat is generated in a relatively small space. In order to be able to dissipate the waste heat and in particular to prevent damage and influencing of the measuring modules 603, the interior of the measuring bar 6 is liquid-cooled. A closed cooling circuit is produced by a plurality of channels 621 in the interior of the measuring bar 6 and the side walls 601, this cooling circuit being closed via coolant channels 617 in the side walls 601. The coolant channels 621, 617 are via a Coolant connection 602 on the outside of the measuring bar 6 is supplied with coolant. A pump for circulating the coolant therefore does not have to be installed inside the measuring bar 6 itself, but can be connected outside.

The side view of the measuring bar 6 shown in FIG. 4 shows, in addition to the substantially U-shaped profile of the measuring bar 6, the cooling channels 621 running in the U-profile, which on the two end faces of the measuring bar 6 through the coolant channels 617 in the side walls 601 to form a closed circuit get connected. Furthermore, the glass cover 615 can be seen in the measuring beam base, which protects the sensitive measuring modules 603 on the measuring carriage 605 against contamination. The U-shaped housing of the measuring bar 6, the side walls 601 and the measuring bar bottom 615 with its glass inserts 616 are connected to one another via seals, so that no dust or liquids can get inside the measuring bar 6. Furthermore, on the outside of the bottom 615 there is a dirt-repellent surface 628, over which webs 629 extend transversely to the longitudinal extension of the measuring bar. The webs 629 keep the printing material 705 at a distance when it is measured and thus avoid the direct contact of the printing material 705 and the floor 615. The webs 629 can also be coated so as to be dirt-repellent.

FIG. 5 shows a view from below of the measuring bar 6, the measuring bar floor 615 being clearly visible here. The measuring carriage 605 has eight measuring modules 603, each of which consists of the actual measuring heads 623 and lighting modules 623. In order to be able to measure the entire width of a printing sheet with 32 color zones, the measuring carriage 605 is moved laterally around one or more measuring fields after each measuring process. The distance between the measuring modules 603 is thus four color zones, so that the measuring modules 603 measure exactly every fourth color zone in parallel. After four scans, the sheet was then measured across all 32 color zones of one color. When printing with four colors, 16 scans are necessary. Furthermore, a movable closure 627 can be seen in FIG. 5, which can cover a measuring module 603. The lock 627 may be present on each module 603 and is electrically or mechanically driven, but it can a common lock 627 can also be used for all modules 603. 5, the closure 627 can be moved transversely to the measuring beam 6 in the sheet transport direction and protects the optics of the measuring modules 603 from damage between the measuring processes; it can also cover the entire underside of the measuring beam 6 between the individual measuring processes. For this purpose, the drive of the closure 627 is coupled to the computer 200 of the printing press.

5, a calibration surface 801 is arranged on one end face 601 or both, which can be approached by the external measurement modules 603. , If a measuring module 603 is positioned over the calibration surface 801, its standardized surface is measured. The surface is a white tile, which corresponds to paper white. By measuring the tile 801, a measuring module 603 can be calibrated at any time between two measurements on the printing substrate 705. The measurement modules 603, which cannot move to the tile 801, are calibrated by transfer calibration of the adjacent measurement modules 603. In order to protect the tile 801 from dirt, it can also be closed by means of a cover 802 which can be moved laterally. In this way, the tile 801 is always covered by the cover 802 between the calibration measurements.

5 also shows dirt-repellent webs 629 which keep the arch at a distance. These webs 629 are connected to the cover 615 of the measuring bar 6. The measuring bar is sealed by a glass layer 616 lying under the cover 615. To clean the glass layer 616, the cover 616 with the webs 629 and the cutouts for the unobstructed view of the measuring modules 603 on the sheet 705 can be folded away or removed, so that the glass layer 616 can be easily cleaned over the entire surface.

In addition to the possibility shown in FIG. 3 with the light source 610 arranged on the measuring carriage 605, it is also possible, according to the arrangement in FIG. 6, to attach the flash lamp 610 outside the measuring carriage 605 and even outside the measuring bar 6. In this case, flexible light guides 614 must be used, which are the non-moving parts of measuring bar 6 and measuring trolley 605. However, the flexible light guides 614 can also be used when the lamp 610 is located on the carriage 605, as in FIG. 3. The light guides 614 can be routed separately to each measuring module 603, as in FIG. 6, but it is also possible to bundle the light guides 614 at one point and to lead them to the respective measuring module 603 over longer distances inside the measuring carriage 605. If all measuring modules 603 receive the light from a single light source 610, it is ensured that all measuring modules 603 use the same light during the measurement and therefore the measuring conditions for all modules 603 are the same. An additional light guide 614 can also be connected to the lamp 610, which ends in a light reference measuring head 632 on the other side. This

The light reference measuring head 632 has the task of measuring the light of the lamp 610 and of emitting a signal for maintenance and control when it changes. A defective lamp 610 or a lamp 610 which is no longer adequately illuminated due to aging is thus recognized in good time.

As an alternative to flexible light guides 614 in FIG. 6, the principle of the optical trombone can also be used, as shown in FIGS. 7a and 7b. In this case, the light guides of the measuring carriage 605 and the measuring bar 6 each end on the end faces 625, 626 of the same, so that they are always exactly aligned with respect to one another. Between the end faces 626 of the light guide of the measuring carriage 605 and the end faces 625 of the

Measuring bar 6 there is an optical intermediate space 624 which, as shown in FIGS. 7a and 7b, is of different sizes depending on the position of the measuring carriage 605. The optical gap 624 between the light guides can be bridged by being mirrored. By means of these mirrors, the light beams emerging from the light guides of the measuring beam 6 can be coupled into the light guides of the measuring carriage 605 in any position thereof. Such an optical trombone is less prone to wear than flexible light guides 614, which is of enormous importance in view of millions of measurement processes. It turned out that. flexible light guides 614 tend to break after relatively few measurements and then have to be replaced. 8a and 8b each show the measuring bar 6 seen from below, with two different arrangements of measuring heads 622 and lighting modules 623. In the arrangement according to FIG. 8a, the measuring heads 622 and the lighting modules 623 are aligned crosswise to one another so that the light, which is reflected by the printing material is not scanned by the measuring head 622 located directly opposite, but is crossed over. Such an arrangement allows the arrangement of many measuring heads in a small space, since here the distance between the measuring heads 622 and the opposite lighting modules 623 can be smaller compared to an arrangement according to FIG. 8b, in which the measuring heads 622 exactly reflect the reflected light Scan lighting modules 623. The smaller installation space in FIG. 8a results from the diagonal entanglement, since the distance between the lighting modules 623 and the associated measuring heads 622 cannot be reduced arbitrarily. The distance is determined by the beam path from the illumination module 623 to the substrate and back to the measuring head 622. The width of the measuring bar 6 or the measuring carriage 605 can be reduced with the cross solution. Since the space requirement is a decisive criterion in the confined space in the vicinity of the printing gap 100 of a printing unit 4, 5, the arrangement according to FIG. 8 a is more suitable for this case.

9 shows a print control strip 700 on a printed sheet 705. The

Print control strip 700 and the actual print image are printed on sheet 705 in printing units 4, 5 of printing press 1. After the last printing unit 5, the sheet 705 and the pressure control strip 700 are complete and can be measured by the measuring bar 6. The sheet 705 is here in the so-called medium format i.e. in a sheet width of 74 cm and has 23 color zones 701, 703. Each color zone 701, 703 consists of 6 color measuring fields 702 and four further measuring fields 704. These color zones 701, 703 are measured by the measuring modules 603 of the measuring bar 6. Normally, only one measuring field 702, 704 per color separation and color zone 701, 703 is measured on a sheet 705 by a measuring module 603. With 23 color zones 701, 703 and six measuring modules 603 and 10 measuring fields 702, 704 per color zone, this results in 40

Measurements on 40 printed sheets 705 before all measuring fields 701, 703 are recorded once were. For more measurements on fewer sheets, more measuring modules 603 must be provided. Furthermore, several pressure control strips 700 can also be attached to a sheet, for example one at the beginning of the sheet and one in the middle or at the end of the sheet. Alternatively, during the production run, ie when the printing press 1 is running at production speed and all

Measuring fields 702, 704 have reached their desired state, the measuring modules 603 are also placed over special measuring fields 702, 704, which contain color information about several or all colors. The measuring modules 603 then either do not have to be moved at all, or they have to be moved much less frequently, since here the color information is locally compact in a measuring field. In the event of changes within the special measuring fields, the measuring mode is then changed again, and all measuring fields 702, 704 are measured again as in the start-up phase.

FIG. 10 shows a similar embodiment to FIG. 5, in both embodiments there is a laterally movable measuring carriage 605 in an encapsulated, closed measuring bar 6. However, in FIG. 10 the measuring bar has a continuous glass cover 634 which covers the underside of the measuring bar 6 closes. On the outside of the measuring beam 6 there is also a sheet guide plate for sheet guiding 633 above the continuous glass cover 634, which bears two slots 639 in the longitudinal direction. Through these slots 639 and the glass cover 634, the measuring modules 603, consisting of the measuring head 622 and the lighting module 623 in the measuring carriage 605, can measure a printing material 705 running under the sheet guide 633. In addition, there are webs 629 arranged on the outside of the glass cover 634 and inside the slots 639. The webs 629 prevent the printing material 705 from touching the glass cover 634 and thus becoming dirty. Since the webs 629 can, as shown in FIG. 10, be positioned in the beam path of the measuring modules 603 under certain circumstances, since the measuring carriage 605 has to measure across the entire width of the printing material, a compensation device is to be provided which measures the influence of the webs 629 in the beam path of the measuring modules 603 compensated. Such a compensation device has already been described elsewhere in this application. An alternative embodiment to FIG. 10 is shown in FIG. 11. Here, too, there is a movable measuring carriage 605 in a measuring bar 6, but the measuring bar is open at the bottom, which is why the measuring carriage 605 is closed by a floor 635. For this purpose, the measuring carriage 605 has a base 635 made of sheet metal, which is additionally provided with glazed inspection openings 636. The glass openings 636 are positioned exactly below the beam paths of the measuring modules 603. Therefore, in FIG. 11, with 8 measuring modules 603 on the measuring carriage 605, exactly 16 glass viewing openings 636 are provided below the 8 measuring heads 622 and 8 lighting modules 623. The glass openings 636 can be made circular as in FIG. 11, but they can also be oval, rectangular or in some other form. In addition to the glazed

Inspection openings 636 are in the bottom 635 of the measuring car still small blowing air channels 637 through which blowing air can escape from the inside of the measuring car 605. This blown air is used to keep the printing material 705 at a distance from the bottom 635 in order to avoid contact of the sheet 705 and thus contamination of the glass openings 636. At the same time, by means of

Blown air generated excess pressure inside the measuring carriage 605 prevents foreign objects from entering the inside of the measuring carriage 605. The blown air channels 637 are e.g. a small compressor or fan inside the measuring car 605 is blown with air.

FIGS. 12a, 12b, 12c and 12d show different fixing options for the printing material 705 during the measurement process by the measuring bar 6 in a sheet-fed rotary printing press 1. In addition to the possibility known from FIG. 1 in FIG. 12a, the printing material 705 at one end by means of a sheet transport gripper 101 and at its other end by the pressure gap 100 between the impression cylinder 7 and the blanket cylinder 8, there are still other ways to fix the sheet 705 even when it is not in the pressure gap 100. According to FIG. 12 b, a sheet 705 is held at both ends by transport grippers 101 on a transport cylinder 9 and thus fixed under the measuring bar 6 during the measurement. Instead of at least the transport gripper 101 tracking in the sheet transport direction, a blowing device 16 can also be installed above the transport cylinder 9, as in FIG. 12c. which does not press the free end of the sheet 705 fixed in a gripper onto the transport cylinder 9 and thus fixes it. Furthermore, a solution according to FIG. 12d can also be used. In this solution, the sheet 705 is fixed on the transport cylinder 9 essentially by means of negative pressure. For this purpose, the cylinder 9 has a plurality of air openings 18 on the surface which comes into contact with the sheet 705, which openings 18

Vacuum chamber 17 in the interior of the cylinder 9 are connected. The negative pressure thus fixes the sheet 705 on the cylinder, which can also be supported by a transport gripper 101, but need not. The vacuum chamber 17 can be part of a suction pump inside the cylinder 9 or can be connected to a suction pump outside the cylinder 9.

FIG. 13 explains how the measuring bar 6 is mounted in a printing unit of a printing press 1. In the top view of the installation location in the printing press 1 it can be seen that the measuring bar 6 is in principle transverse to the sheet transport direction 19 between the side walls 14 of the printing press 1 is installed. Since the measuring bar 6 should also be retrofittable in already existing machines, the assembly is carried out via two lateral mounting plates 20, which can in principle be installed in any printing press 1, as long as the required space is available. The mounting plates 20 can also compensate for different distances between the side walls 14 by being of different thicknesses. The

Mounting plates 20 are fastened to the side walls 14 by means of mounting screws 21 and carry the bearing for the measuring bar ό. The measuring bar 6 has covers 22 at both ends, which enclose the measuring bar 6 and support bearings 23. These bearings 23 support the measuring bar 6 with respect to the mounting plates 20 and reduce vibrations which the printing press 1 would transmit to the measuring bar 6. The covers 22 can be designed in such a way that the measuring bar 6 can simply be removed from the covers 22. LIST OF REFERENCE NUMBERS

1 printing press

2 feeders

3 outriggers

4 printing unit

5 printing unit with measuring bar

6 measuring bars

7 impression cylinders

8 blanket cylinders

9 transport cylinders

10 sheet turning device

11 prepress

12 networking

13 inking unit

14 side wall

15 sensor

16 blowing device

17 vacuum chamber

18 air vents

19 Transport direction 0 Mounting plates 1 Mounting screws 2 Covering the measuring bar 3 Bearing of the measuring bar

100 printing nip

101 Transport transport grips 00 Control panel / computer 01 Measuring electronics 02 Handheld measuring device 01 Sidewall of the measuring bar 602 coolant connection

603 measuring module

604 linear motor

605 measuring car

606 guide rail for measuring car

607 capacitors for flash lamp

608 Register sensor on the right

609 reference measuring head

610 flash lamp

611 optical fiber coupling optics

612 power supply for flash lamp

613 Register sensor on the left

614 light guide

615 Cover of the measuring bar

616 Glazed area in the cover

617 Coolant guide in the side wall

618 Flexible electrical connection

619 Connection for measuring electronics

620 Electrical distribution device

621 Cooling channel in the measuring bar

622 measuring head

623 lighting module

624 Optical intermediate room

625 end face of second light guide bundle

626 end face of first light guide bundle

627 movable lock

628 dirt-repellent surface

629 footbridge

630 second measuring head

631 circuit board

632 light reference measuring head 633 bow guide

634 continuous glass cover

635 Bottom of the measuring car

636 glazed inspection openings 637 blown air ducts

638 blown air source

700 print control strips

701 color zone

702 color measuring field 703 further color zone

704 further measuring field

705 substrate

800 extraneous light source

801 calibration area 802 cover calibration area

Claims

claims

1. A method for recording spectral, densitometric or color measurement values on sheet-shaped printing materials (705) during the printing process in a sheet-fed printing press (1), characterized in that the measurement values are determined on sheets (705) moving by the printing press (1) and can be used as a control parameter for controlling the printing process of the sheet-fed printing press (1) by means of a computer (200).

2. The method according to claim 1, characterized in that the measured values determined are used by means of a computer (200) as control parameters for the production of printing forms in the prepress stage (11).

3. The method according to claim 1 or 2, characterized in that the measured values are used by means of a computer (200) to create a color profile for the control of inking units (13) of a printing press (1).

4. The method according to any one of claims 1 to 3, characterized in that the measured values are used by means of a computer (200) for setting the printing press (1) during the setup phase.

5. The method according to any one of claims 1 to 4, characterized in that the measured values are used by means of a computer (200) for setting the printing press (1) during the production printing phase.

6. The method according to any one of claims 1 to 5, characterized in that sensors (622) for recording the measured values for color calibration are calibrated at certain time intervals by means of a calibration device.

7. The method according to claim 6, characterized in that one or more calibration surfaces (801) with associated measured values, which are stored in the computer (200), are present as a reference value for the calibration device.

8. The method according to claim 7, characterized in that at least one white tile (801) is present as a reference value for the calibration device.

9. The method according to any one of claims 7 to 8, characterized in that one or more calibration surfaces (801) in the channel of a printing cylinder (7, 8) are arranged in an extension of the surface of the printing cylinder.

10. The method according to any one of claims 7 to 9, characterized in that at least one calibration tile (801) laterally outside the. Printing cylinder surface arranged between the side wall (14) and printing cylinder (7, 8).

11. The method according to any one of claims 7 to 10, characterized in that an arc-shaped printing material (705) with known spectral measured values before the proof is transported as a spectral reference for calibration by the printing press (1) and measured by the measuring sensors (622).

12. The method according to any one of claims 7 to 11, characterized in that the sensors are measuring heads (622) and the calibration values determined by the calibration of a measuring head (622) by means of the computer (200, 201) into calibration values for further measuring heads (630, 622) can be converted

13. The method according to claim 12, characterized in that a transfer calibration is carried out in such a way that a calibrated measuring head (622) also scans a measuring field (701) of a further non-calibrated measuring head (630) which it has already scanned.

14. The method according to any one of claims 7 to 13, characterized in that at least one calibration tile (801) can be closed by means of a cover (802).

15. The method according to any one of the preceding claims, characterized in that a calibration is carried out with the aid of an external measuring device (202).

16. The method according to any one of claims 12 to 15, characterized in that for each measuring head (622) certain color values are stored in a computer (200, 201), the ratios of these color values to one another are stored in the computer (200, 201) and at Change of the stored measured value ratios a signal is output.

17. The method according to any one of the preceding claims, characterized in that a first measuring head (622) detects its own color zone (701) and the color zone (703) of a second measuring head (630) lying next to it, and the second measuring head (630) also its own zone (703) and the zone (701) of the first measuring head (622) are recorded and the recorded measured values are compared with one another

18. The method according to any one of the preceding claims, characterized in that in at least one color zone (701) by a measuring head (622) measurements are carried out on a light / dark edge, the measuring head (622) in uniform steps from one side is moved beyond the light / dark edge over the light / dark edge to the side on this side of the light / dark edge and the measured measurement values are compared with the known structure of the measuring head (622).

19. The method according to any one of the preceding claims, characterized in that an illumination device (800) is present, a dark measurement is carried out before the actual measurement by a measuring head (622) and the measured value recorded in this case is that of the one with the lighting device (800) switched on. color measurement is subtracted.

20. The method according to any one of the preceding claims, characterized in that simultaneously with the color measurement of a first measuring head (622) by means of a second measuring head (630) a measured value on a white background (704) of a printing material (705) is recorded and the white reference value determined thereby Correction of the color measurement values determined with the first measuring head (622) is used.

21. The method according to any one of the preceding claims, characterized in that, during the acquisition of measured values on the printing substrate (705) by one or more measuring heads (622, 630), any existing light sources (802) are switched off, hidden or dimmed to an uncritical value ,

22. The method according to any one of the preceding claims, characterized in that the measuring duration and the measuring method of the measuring heads (622, 630) are adapted to the existing light sources (802) when the measured values are recorded on the printing substrate (705).

23. The method according to any preceding claim, characterized in that the detection of measured values by measuring heads (622, 630) with any fluctuations in light sources (802) by means of at least one sensor (15) which detects the fluctuations, or by means of a control signal of the fluctuating ones Light source (802) is coordinated in time.

24. The method according to any one of the preceding claims, characterized in that a plurality of measuring heads (622, 630) are distributed at equidistant intervals across the width of the printing substrate (705) and simultaneously detect ink zones (701, 703).

25. The method according to claim 24, characterized in that the measuring heads (622, 630) are offset by a color zone (701, 703) after each measurement.

26. The method according to any one of the preceding claims, characterized in that during the printing operation after the pressure phase, the measuring heads (622, 630) are positioned such that they detect several colors (702) at the same time.

27. The method according to any one of the preceding claims, characterized in that the computer (200, 201) stores the position coordinates of print control strips (700) applied to a printing material (705).

28. The method according to claim 27, characterized in that a sensor (15) is provided for determining the position of a print control strip (700) on the printing material (705).

29. The method according to any one of the preceding claims, characterized in that the measured values determined by measuring heads (622, 630) are subjected to a plausibility test after each measurement.