DE102007059177B4 - Apparatus and method for controlling the composition of the printing ink on a printing machine - Google Patents

Abstract

Method for controlling the composition of a color mixture (11, 31) for at least one printing press (2), - in which optical actual values (I) of light (7) are obtained, the light (7) at least with parts of a printed image (9) which the printing press (2) has produced on a printing material (6) with an ink mixture (11) located in the ink feed system (61) of the printing press (2), has experienced an interaction - and in which due to deviations in the actual optical values (I) At least one correction color mixture (31) is generated from optical target values (S), which is added to the color mixture (11) located in the ink supply system (61) of the printing press (2) and there changes the quantitative ratios of the color pigments to one another, the color mixtures used in the method (11, 31) are provided by different color mixing devices (16, 24), characterized in that - the first color mixing device (16) is a color kitchen (16) which to provide ink (11) for a first number (N) of printing machines (2), ...

Description

The invention relates to a method for controlling the composition of a color mixture on at least one printing press, a mixing device for a color mixture and a system for controlling the composition of a color mixture on at least one printing press.

Printing presses are printed with printing inks, which usually consist of various chemical components.

The carrier of the color or the intended color impression, which is to occur after the printing process in the viewer of the printed image, is usually of color pigments, such as organic chromophores, which consist of a combination of carbon, oxygen and nitrogen and can absorb certain wavelength ranges of light , provided. The color impression can also be given by long-chain hydrocarbons, so-called polymers. The polymer chain comprises chromophoric groups which give the desired color impression to the resulting polymer film after the crosslinking process.

In many printing inks several such dyes are present, so that the subsequent color impression of the viewer of the printed image is already significantly influenced by several optically active components of an ink. Of course, the printing substrate and the solvents of the printing ink, which often make up a large proportion of the volume of the ink, have a further influence on the color perception of the observer.

According to the prior art, the composition of ink is determined in central facilities ("color kitchen") of the printer concerned.

For this purpose, usually so-called color recipes that specify the composition before. The colors compiled on the basis of the color recipes are transferred to the respective color reservoirs of the printing presses and processed there. It is also known in this connection to obtain different measured values from the print images. Thus, with optical measuring devices, which the printer calls "densitometer" or "spectrophotometer", light which has undergone an interaction with the printed image is examined. The interaction is usually in a reflection or transmission of light. Light that has experienced any relevant interaction in this context with the printed image (especially reflection or transmission) is referred to in this document as a remitted light.

As measured values, light intensities L (of the remitted light) are recorded in a spectral range. In a "densitometric" measurement, different narrower spectral ranges of visible light (eg nine spectral ranges) are measured.

The densitometer consists of several color filters, which limit the light to a relevant ink for the measurement. As a rule, four color filters are provided for the cyan, magenta, yellow and black inks. Behind each color filter is a photoelectric sensor (photodiode). The densitometer is used inter alia for the quantitative measurement of color density (solid density). During the measurement, light is irradiated onto a printed measuring surface and then, after passing through a color filter, the remission or transmission value is determined with a photoelectric sensor (photodiode). Deviations of the printed measuring surface from a "color standard", such as color deviation, color depth, contrast, etc., can be calculated from the measured values.

The higher-quality "spectrometric" measurement usually contains measured values from the entire spectrum of visible light. This broad spectral range is measured, for example, by 36 sensors with narrower spectral ranges.

The spectrophotometer measures the reflectance values of light over the entire visible spectrum of the light, which is returned by the measuring surface (usually a printed measuring surface). As a rule, the substrate is illuminated with suitable light, in this case white.

The spectrophotometer thus measures the remission degree of the sample (in percent) over the visible spectral range of the light (about 400 to 800 nm) and calculates from this remission spectrum with suitable software the coordinates of the measured color in a color space. The coordinates indicate the so-called color location of the color.

The EP 1 245 387 A2 and DE 24 10 753 show processes for ink supply of printing presses. In order to control the optical color impression on a printing material, actual values of the color on the printing material are determined in the pressing phase with a suitable measuring device (for example a densitometer) and these are compared with desired values. By means of a color mixing device, the desired color impression can be produced by adding color from the color tanks of the color mixing device to a color container of the printing press.

The patent application EP 0 228 347 A1 proposes control of the color impression on a material web which uses a spectral color analysis instead of a densitometric color density measurement. Measuring the spectral distribution of the color enables a very accurate correction calculation of the above-described base recipe of the ink by suitable software. However, a method according to EP 0 228 347 A1 still has disadvantages. So often several correction cycles are necessary until the desired color impression is achieved due to the corrections.

The object of the present invention is therefore to propose devices, methods and a system with which a faster adjustment of the printed image is possible than in the prior art.

According to the invention, this object is solved by the features of claims 1, 15 and 18.

The present invention takes advantage of various circumstances: if at least two color mixing devices are used, then one of these color mixing devices may be located in closer proximity to one printing press than the other. In addition, at the mixing device already probable correction colors may be present or anticipated corrective mixtures may be premixed.

The mixing devices may be differentiated into central mixing devices and decentralized or more decentralized mixing devices. The central mixing devices will usually be responsible for more printing presses than the decentralized ones. In this case, a mixing device has at least two paint containers in which color mixtures but preferably primary colors are present. The mixing device has the ability to supply color components from their containers. This can be done by metering devices, wherein a mixture of colors or color mixtures in a metering device of the mixing device or only in the ink supply system of the printing press can be made.

Such a mixing device can also be mobile. In this case, her aforementioned components can be moved with her. If the mixing device is mobile and has several dosing taps or downpipes for color mixtures or individual colors, then a paint bucket of a printing press can receive color from various of these dosing taps, wherein the mixing device can be moved such that the respectively filling dosing tap is located in a filling position for the paint bucket is.

Decentralized mixing devices may contain fewer primary colors or, more generally, fewer color containers than decentralized mixing devices. Thus, it is advantageous if a decentralized mixing device contains at least 11 primary colors (base colors). Another container may contain solvents. In addition, the central mixing unit often also contains spot colors and the like.

The mobility of a decentralized mixing device can be made by means of locomotion such as wheels. It may have drives, auxiliary drives and steering or remote steering devices. It can also be designed as a rail vehicle.

Advantageously controllable color valves, a control device that can control the color valves, and color lines that lead in any way color from a container in a collection point of the printing press.

A paint mass determining device is capable of detecting the mass of paint at least in a part of the color pipe system. A color line system of a printing press leads the ink from one supply point to the printing material. It usually includes a bucket-like color reservoir, the color is supplied. Furthermore, pipelines are present in the paint line system. At least a portion of the piping carries paint from the paint reservoir to other paint containers. In color works are such color containers, which are often known as color pans or doctor chambers, available. Especially in gravure printing and flexographic printing such containers have the task to pass on color involved in the printing process rollers. In flexographic printing, often a transfer to an anilox roller, which in turn the color to the Printing plate cylinder, which is often called cliché roll in flexographic printing, passes. The printing plate cylinder transfers the ink to the substrate.

All of the aforementioned reservoirs, containers, lines and rollers which transport the ink to the printing substrate for the printing material are referred to in the present document in their entirety color line system. A color is thus associated with a color line system that contains the entire amount of that color.

An accurate determination of the mass of this color is difficult. It is possible to determine the mass of the paint in one or more reservoirs and / or containers by measuring the weight and / or measuring the volume. In general, such a measurement will take place immediately on a paint bucket, which represents the paint reservoir. Even in a paint trough or even a doctoring chamber such a measurement appears possible, even if vibrations are to be considered during the printing process.

However, it is advantageous to estimate the mass of paint that is present in at least part of the piping and containers of the paint supply system. This can be based on the volume of the elements concerned.

A (real) mass measurement can be made by measuring the weight and / or by measuring the volume (level) of the ink in the relevant ink reservoir or container.

Typically, the mass detection will be done by a mass discovery device due to the addition of such estimates and such measurements. In this way, the mass of the in the supply system (or in parts thereof) located color with reasonable effort can be determined very accurately.

These measured values are fed to a control and evaluation device assigned to the printing press. Whether this device is physically present on the printing machine itself or whether it has any distance to this, is in the light of today's information transfer options subordinated. Also of secondary importance is whether the intelligence of this facility is achieved in one place or in several places (centralized or decentralized machine control). It is important, above all, that the device has a preferably electrical or electronic contact possibility with the measuring and control components of the printing machine mentioned in this publication. This possibility of contact should give the device the opportunity to control and exchange information with various functional units of the printing press and thus access to such units. If this is the case, the control and evaluation device is assigned as the printing press.

The control and evaluation device can also determine the deviation of the optical actual values, which the optical measuring device determines, from the optical nominal values which are also stored in the device in the form of light intensity values in selected wavelength ranges.

The optical measuring devices may be spectrophotometers, which allow a suitable software a very precise calculation of a correction recipe. Also densitometric measurements can advantageously be based on the creation of a correction color mixture. These measured values can be extrapolated in such a way that they also allow statements about non-measured spectral ranges. The quality of the densitometric measured value and estimation or extrapolation can also be checked from time to time with spectrophotometric measured values.

Advantageous embodiments of the control and evaluation device convert the optical measured values, which are determined by the optical measuring devices, into colorimetric values at an earlier or later point in time of the evaluation. The same applies to optical actual and setpoint values.

Colorimetric measurements can be used to express the visual result of a color view (of a human observer) or a color comparison with a "numeric value" (often called a color locus).

Due to this deviation and the weight of the paint in the machine, the device calculates the mass and composition of the paint that must be added to achieve the desired change. Here are the control and evaluation in the respective Farbmisch- and metering available basic colors and the effect of these colors on light that interacts with these colors, known.

Advantageously, the device is also known the effect of the printing material currently being processed on the printing press.

Using a software implemented in the control and evaluation device, the desired values for the mass and composition of the color can then be determined. Such computer results, which are determined on the basis of colorimetric desired values, can also be used as a basis for the basic recipe. When determining and using the correction prescriptions, a control process that approximates the actual values in one or more steps to the nominal values is possible with the measures mentioned.

The determination of the mass of paint in the paint circuit or parts thereof is very useful, as it can monitor how much paint (from the mixed base paint recipe) is still present on the machine. At least the part of the color that is not yet on any of the rollers (ie the paint in the piping, reservoirs and containers) will most likely be part of a resulting color mixture that occurs after the correction color has been added and is therefore for the this color caused effect on light relevant. Therefore, the mass measurement is of great benefit.

It also follows from the above facts that it may be advantageous to measure and / or estimate only the mass of that color which is not yet on the rollers (ink transfer rollers such as anilox rollers and printing plate cylinders).

In addition to measuring and / or estimating the amount of ink, it is also advantageous to measure the viscosity of paint in the feed system. As already mentioned, the color consists of various components, of which the color pigments and the solvents should be mentioned. The color-splitting and evaporation characteristics differ between all the components (between the different pigments among each other and between the pigments and the solvents) of the color, so that their composition changes during the processing of a color quantum. The biggest differences naturally occur between solvents and pigments. Thus, the proportion of solvents in the ink may be greatly reduced as a result of evaporation, which has a significant influence on the density of the ink and on the effect of the paint on light. A measurement of the viscosity usually allows an appropriate inference to be drawn on the concentration of the color components in the ink and thus again to mix with higher accuracy adequate correction colors.

As already mentioned, the above-mentioned method steps enable the determination or at least adequate estimation of the quantity and composition of the ink which is located on the printing press. This also applies if the first or already several quanta have been admixed to optionally differently composed correction color, since the control and evaluation device yes the amount and composition of these correction colors are known and it is advantageous to save them. The control and evaluation device can then continue to monitor the composition and composition of the resulting ink by adding the accompanying and the colorant components still present on the printing press and, if necessary, by further observing the weight and the viscosity.

Thus, among other things, it is possible to record and store with which color composition has been printed at what time. It is also possible to set this original or resulting ink composition in direct relation to the colorimetric values (actual values) measured on the printing substrate (at this time).

In this way, the operator can gain an overview of the color compositions and the respective results.

He can selectively repeat the colorant compositions with which good results have been achieved by mixing colors according to the associated resulting recipes. Thus, good results can be at least largely reproduced by repeating the same procedure.

It should also be mentioned that a resulting recipe can be calculated by analyzing the resulting color mixture and that it is advantageous if the software suitable for this purpose is installed on the control and evaluation device. As mentioned above, the control and evaluation are indeed the Quantity and composition of the correction colors known, and advantageous control and evaluation store them. The control and evaluation device can thus - as also mentioned above - continue to monitor the mass and composition of the resulting color by adding the accompanying and the color components still present on the printing press and optionally by further observation of the weight and viscosity. The control and evaluation device can then assign recipes to the different compositions.

From a resulting color composition at a given time, resulting color recipes can be determined, which indicate how to use a color mixture "directly", for. B. as a basic recipe, to the relevant resulting color composition. Thus, a desired color location can be achieved "without detours".

In general, it is useful to save used recipes (especially basic recipes, correction recipes). The corresponding measurements (in particular optical, but also advantageously mass and viscosity) can be stored.

It is also advantageous to repeat several of the aforementioned measurements at certain time intervals.

It has been mentioned above that the use of the knowledge of already used recipes (basic recipes, correction recipes) and above all the recipes which lead to the provision of resulting color mixtures can be advantageous.

Alternatively, however, you can proceed as follows:
The deviations of the colorimetric desired values from the colorimetric actual values, which are recorded as part of a printing process according to the above teaching, are likewise stored. These values are often referred to as ΔK. The various deviations that are measured until a satisfactory result is achieved are added together and to the setpoint. With the help of the color mixing software implemented on the control and evaluation device, a basic recipe is created which is optimized to achieve the resulting (cumulative) color locus and not the desired color locus. The color produced according to this "bypass recipe" is printed.

The methods mentioned for using a resulting color recipe or the bypass recipe are particularly well suited if the other process parameters are as constant as possible for the different orders:
These process parameters include: same press, same anilox rolls, same temperature, etc.

In the context of the present document, a method for operating a printing press is understood as meaning both a method for processing a print job and a method for sequentially executing a plurality of print jobs. The operation of a printing press encloses here so also the order conversion.

When processing several jobs, in which at least one color is to cause the same color impression and / or has the same setpoint (color location) in a color space, it is advantageous to resort to "experiences" from earlier of these orders with the same color setpoint. These experiences include, above all, measured values from these earlier orders. However, these experiences also include color mixtures, the color recipes underlying these color mixtures, correction recipes and resulting color recipes.

With regard to the measured values, it is particularly interesting to note the deviations of the colorimetric actual values from the colorimetric desired values that have resulted in earlier printing processes when it was attempted to achieve the colorimetric target value with a color mixture.

As already mentioned elsewhere, it is possible to calculate color recipes based on predefined colorimetric target values as well as information on the color values of primary colors (how the primary colors affect light), with which the underlying color locus can be calculated relatively accurately. In order to be able to carry out such calculations, the control unit of a printing press can be supplied with color calculation software (color formulation software). The deviation in a color space, which results when printing with the color mixture based on the calculated recipe, allows a whole series of conclusions to be drawn on the calculation method itself and on the process parameters.

Therefore, it is advantageous to store the deviation and the process parameters of such printing operations. Especially the deviation is of great interest. If one or more correction cycles are necessary to achieve the desired color location (colorimetric target value of a color) with sufficient accuracy, the other deviations (ΔK ₁ , ΔK ₂ , etc.) are also of interest. The different deviations can be transferred into the coordinates of a color space and be compressed by vectorial addition to a total deviation (ΔK).

In a further order, which provides for reaching the same color location, which is stored in the control device, then the total deviation can be vectorially subtracted from the desired color location. The resulting difference color location (D = S - ΔK) is then controlled by the Ink Formulation Software as the reference location instead of the target color location.

In the case of a measurement of the mass of the ink present on the printing machine, it is possible in the manner already described above to determine exactly with which color mixture which deviation has come about. This measure benefits all the aforementioned devices and methods. It is just as possible to take into account which deviation was due to which color mixture in the machine came about.

In general, one will adjust the control components of a printing press so that they can perform the procedures. This setting can be due to the implementation of software components in suitable hardware elements.

Further details and embodiments will become apparent from the dependent claims and the description.

The individual figures show:

1 A system for providing color mixing

2 A mobile (decentralized) mixing device

3 Another embodiment of the mobile decentralized mixing device

4 An inking unit of a central cylinder flexographic printing machine

5 The course of the spectral light intensity of a color

6 The course of the spectral light intensity of a color

7 The course of the spectral light intensity of a color

8th The course of the spectral light intensity of a color

9 The vector addition in the color space E

10 The vectorial calculation of the target color location S in the color space E

11 Another system for providing color mixing

1 shows a system 1 for providing a color mixture for printing substrate 6 , The system 1 also has the ability to correct the color mixture. The correction can also be carried out during the printing operation.

The printing press 2 has a control device 3 on that over the control line 5 with an optical measuring device 4 connected to the currently printed substrate 6 examined. The light cone 7 indicates this from the printing material web 6 remitted light, which has interacted with the printing material on. From the printing press 2 is only a printing unit 8th shown. Nevertheless, the printing press can 2 have any number of printing units. If that is the case, there are different methods to using the measuring device 4 the print image 9 to investigate. Once special print marks can be examined, which are printed in certain areas of the substrate web. On the other hand, certain Selected zones of the print motif, in which a color occurs very often, are examined. However, it is also possible to examine each color sequentially when proofing each color.

The one shown printing unit 8th the printing press 2 gets its color 11 from the paint bucket 10 , its weight from the weighing device 12 is controllable. The weighing device can measure the mass of paint via the control line 14 the control device 3 to transfer. The amount of color that is in the remaining ink delivery system of the press can be estimated.

The color lines 13 lead the color to the inking unit / printing unit 8th to. The inflow is from the paint valves 15 regulated.

With a corresponding device of the control device 3 This can be the mass of color constantly 11 in the paint bucket 10 record. It can also measure the readings of the optical measuring device 4 record the optical measurements and the mass values recorded at one time. As long as the control device 3 Knowing the composition of the color in the printing press, it can always determine at which time which color mixture has produced which color values in a color space (E).

To mention is still the viscosity measuring device 22 that constantly measures the viscosity of the ink on the press. Especially in gravure printing and in flexographic printing, it can happen that the ratio of the solvents in the ink to the color pigments changes, which may be due, for example, to different evaporation properties of pigments and solvents. Such a development can be observed quite well by measuring the viscosity, since solvents usually greatly reduce the viscosity. When the viscosity measuring device 22 their readings also in some way to the controller 3 the printing press 2 - or another control device 19 - passes on, are this measuring device values to the actual color I place on the substrate 6 , to the weight of the color 11 at the machine 2 as well as the viscosity of the same 11 to disposal. Based on these measurements, a good overview of the composition and amount of color is given.

Typically, a printing process in which an order is processed begins with the provision of color mixtures 21 for the various inking units through the central color kitchen 16 , In this central color kitchen are colors 17 , mainly also primary colors, in suitable containers 18 stored. In the illustrated advantageous embodiment, these color containers are also 18 with weighing devices 12 Mistake. Alternatively, the volume of colors could be 17 be measured with level measuring devices. The weighing and / or level measuring devices can transmit their measured values via a control line 14 the control device 19 the central color kitchen 16 to hand over.

This control device 19 controls the "way" in which the color mixtures are composed. When providing color recipes that underlie the color mixtures, it is often attempted to achieve color locations that should arise on the printing material as precisely as possible. Based on the knowledge of the color locations and on the knowledge of the optical properties of the color in the paint containers 18 the color kitchen 16 You can calculate with which mixture of these colors the color point S can be reached. For this purpose, of course, a knowledge of the optical properties of the printing material advantage.

The mentioned computational work can be provided by a software. This can be in the control unit 19 be implemented, so this control unit 19 for calculating a color recipe based on these color set points S is established.

As already mentioned, the printing process usually begins with a basic color mixture produced in the central color kitchen on the basis of a basic recipe - which has been calculated on the basis of color setpoints in the aforementioned manner. However, the basic color mixtures can also be specified by the color manufacturer. This basic color mix 21 will be in a container 20 - Alternatively, in a piping system, not shown - to the printing press 2 brought. With the basic color mixture 21 begins the printing process.

The investigation of the resulting print images 9 with the optical measuring device 4 often shows that the target color locations S deviate from the measured actual values I by a difference ΔK. This circumstance is deplorable, since it comes in many areas on an accurate compliance with the specified color locations. For example, in packaging printing great importance is placed on compliance with such target color locations. In Flexographic printing and gravure printing are leaders in this area, whereby offset printing machines are also used. The printing press 2 So, among other things, it can be a gravure, flexo or offset printing machine.

After the deviation .DELTA.K of the actual value of the color locus from the nominal value of the color locus S has been determined, it can be decided whether and how measures are to be taken in order to bring about a greater agreement between the actual value I and the setpoint value S. This is difficult especially during the current printing operation to a print job. In the in 1 shown embodiment of the system 1 There is next to the central color kitchen 16 , which may well be assigned to several printing presses of a printing company, a decentralized color mixing unit 24 , This color mixing unit 24 can definitely be assigned exclusively to a printing press. In this case, it may even be structurally connected to the printing press. However, it may in turn be intended to provide color, and preferably, correction color to multiple machines.

This can be done by this unit 24 also mobile, so for example as a whole unit on wheels 34 to be movable.

In 1 is shown that the color mixing unit 24 in turn, base color for correction 26 , Paint containers 25 , Weighing equipment 27 as well as color lines 13 and paint valves 28 Has. As a rule, in the decentralized color mixing unit 24 a smaller amount of ink and a lower number of colors are stored than in the central color kitchen 16 , The decentralized color mixing unit 24 is also a control device in this embodiment 23 associated with the color mixing by the decentralized color mixing unit, by the control of color valves 28 or the like. This control device 23 can over the data line 14 , the node 29 and the interface 30 Information about the composition and amount of correction color will be sent. Based on this information, a color recipe emerges, and from the decentralized color mixing device 24 a correction color mixture of the printing press is provided. This process is indicated by the arrow 31 indicated.

The correction color can be brought back to the printing machine with a container, as through the container 20 and the arrow 32 in relation to the basic color mixture 21 is indicated. Again, an unillustrated piping system is available as an alternative. In the case of a mobile decentralized mixing device 35 This can also be attached to the paint buckets 10 the printing press 2 moved up and fill them with a drain cock.

To mention still remains that the dots between the color containers 18 and 25 indicate that their number is usually higher than in 1 shown. Usually N become primary colors 17 be present in the central color kitchen. In a decentralized unit should at least M colors 26 be saved.

In the central color kitchen 16 In addition, individual pigment containers may be provided in which pigments for the individual primary colors 17 are located. By mixing primary color pigments with solvents and other additives, which are not discussed in detail, can be found in the central color kitchen 16 primary colors 17 getting produced.

To mention still remains that by the networking of the control devices 3 . 19 and 23 always useful information can be exchanged. Such is by measuring and / or estimating the amount of color 11 at the printing press 2 , by observing their composition, by the optical measurement on the substrate 6 but also, if necessary, by measuring their 11 Viscosity works well, well known prior to color correction, which composition of the color is printed at a time T on the machine. By adding an at least the control device 23 the decentralized color mixing device 24 known quantity and composition of the correction color changes the composition of the color 11 at the machine 2 considerably. However, this composition after the first correction step is by adding the amounts of the individual color components of the color 11 at the machine 2 and the correction color 31 relatively accurately calculable.

This applies in adapted form even after further such correction steps. Therefore, it is possible in the manner described to determine relatively accurately, even after any number of correction steps, with which color mixture which colorimetric actual value I has been reached. This knowledge is very helpful, among other things, when subsequent jobs with the same or similar colors (to be attached to the color locations) to be printed.

2 shows a decentralized mobile color mixing unit 35 , which is the role of the decentralized color mixing unit 24 in 2 could take. The other reference number 35 was awarded here to emphasize that the color mixing unit 35 is mobile while the color mixing unit 24 in the system diagram 1 just be stationary. Otherwise, the functional components carry paint container 25 , Control line 14 , Color line 13 , Control device 23 , Paint valve 28 and interface 30 the same reference numerals as in 1 , The aforementioned functional components are of the frame or the frame 33 on the wheels 36 movable, worn. In addition, with the supports 34 indicated that the aforementioned functional components are supported by the frame. The decentralized mobile unit 35 is able to drive from press to press and deliver correction color there. Here, the decentralized mobile unit is able to detect certain quanta of color in the different paint containers 25 are stored, and thus produce a corresponding correction color mixture and through the color lines 13 leave.

The mixing of the different color components can be done in a mixing device (not shown) of the decentralized mobile unit 35 be made. However, mixing can be done in the paint bucket 10 the printing press 2 be made. The control unit 23 Information about the required correction color is given. Im in 2 This embodiment is done by the interface 30 the decentralized mobile color mixing unit 35 to the interface 37 the printing press 2 that gets the correction color, is docked. In the embodiment shown, the control device shares 3 the printing press 2 the control device 23 the decentralized color mixing device 35 with, with which color mixing which deviations ΔK on the printing material 6 have resulted. The control device 23 the decentralized color mixing device 35 is set with a "color formulation software" such that it can calculate the composition and amount of color mixture that can be used for correction. For this purpose, this control device 23 Also known, which amounts of correction colors with which optical properties are in the containers 25 the mobile decentralized mixing device. If a color is lacking for creating a correction mixture because it is used up or is not present from the beginning, the control device gives 23 a corresponding signal.

For the execution of the predetermined scope of work, it is advantageous if the optical properties of the printing material 6 the control device 23 be made known.

The above lines have a very "smart" controller 23 described. The way in which the networking of the control devices 3 . 19 and 23 in 1 however, shows that each of the controllers can be tuned to handle these steps if it has the hardware requirements and if the data lines 14 between the control devices 3 . 19 . 23 give this.

The interfaces 30 and 37 can be ethernet interfaces. However, it is advantageous, in particular with regard to the mobile decentralized unit 35 if they get their information via radio or mobile phone frequencies (such as UMTS, WLAN, IR, etc). In this case, it can be constantly supplied with information and the docking of the interfaces 30 . 37 eliminated.

Regarding the decentralized color mixing devices 24 and 35 It should be said that these will usually only provide correction color blends. To relieve the central color kitchen 16 However, in exceptional cases they are also a basic color mixture 21 (eg for proofing). To conceptualize the decentralized color mixing devices 24 . 35 is to say that they provide color or color quanta available in any case, but that - as already indicated above - is not said that a real mixing of these color components for correction color mixture or base color mixture necessarily at these decentralized color mixing devices 24 and 35 must take place. Rather, this can, for example, only in the color buckets 10 the printing press concerned 2 be performed.

Especially with regard to the decentralized color mixing devices 24 and 35 is to say that providing any containers or paint lines 13 that lead color mixtures, is not necessarily beneficial. The colors mixed in this way inevitably contaminate the color mixtures for further jobs. Therefore, it is beneficial to the color line 38 in the decentralized color mixing unit 35 Also, mixed color leads to make it interchangeable or easy to clean.

In 3 is another embodiment of a mobile decentralized color mixing unit 35 shown, in their color lines, as downpipes 38 are designed, each only color 24 from one each ink pool 25 is directed. Each of these downpipes 38 again has a color valve 28 that from the control device 23 over the control lines 14 can be controlled. The control device 23 controlled with the weighing equipment 27 also the weight of the colors 26 , the interface 30 is an antenna that is suitable for radio and / or (mobile) reception. The attachment of the different functional components on the frame 33 is with the props 34 and the mounting platform 39 shown.

The mobile unit 35 becomes the paint bucket 10 a printing press 2 proceed in such a way that successively one or more downpipes 38 come into their filling position to the paint bucket and the control unit 23 calculated color quanta are delivered.

A solvent tank may also be attached to such a mobile decentralized color mixing unit 35 be provided. However, it is in the illustrated system 1 Also beneficial if such a tank directly on the press 2 is and at a decrease in viscosity at the behest of the control unit 3 the printing press solvent into the relevant paint bucket 10 (As a rule, it is to be assumed from an application of this doctrine on multi-color printing machines, therefore, often more paint buckets 10 at the printing press 2 available).

In 4 becomes an inking unit 8th a central cylinder flexographic printing machine shown. Machines of this type are used in packaging printing and often have eight to twelve such inking units B. The scope of the functional components of the inking unit 8th is through the rectangle 44 indicated. The application of the teaching of the present document to such a Zentralzylinderflexodruckmaschine is advantageous. Based on 2 can be the color transport of a paint reservoir, the color of the outside of the printing press is supplied - here the paint bucket 10 - up to the substrate 6 sketch.

The color lines 13 make the connection between the paint bucket 10 and the doctoring chamber 40 ago. In a paint line is color to the doctoring chamber (as indicated by the arrow 46 indicated) and in the other line 13 from the doctoring chamber 40 to the bucket 10 directed (as by the arrow 46 indicated). The color flow in the color lines 13 the printing press from and to the bucket 10 is therefore often referred to as a color cycle, but this is misleading, as well as color from the doctor chamber to the anilox roller 41 , which rotates in the direction indicated by the arrow C, is discharged. The anilox roller 41 Gives the color to the cliché 43 the cliché roller 42 which turns in the direction indicated by arrow B. With the cliché is the substrate 6 printed while that by the cliché roller 42 and impression cylinder 45 defined pressure gap 48 running.

The printing material is further promoted in the direction of rotation A of the impression cylinder, runs on the guide roller 49 over, is from the counterpressure roller 45 lifted off and from the optical measuring device 4 examined. The light cone 7 put that from the print image 9 remitted light.

For the purposes of weighing or determining the color mass or the color volume of the ink in question on the printing machine is in 4 only the weighing device 12 that the weight of the bucket 10 monitored, shown. The color lines 13 could also be weighed. It seems more appropriate to determine their volume and thus to estimate or calculate the volume of the paint in the pipes. The doctoring chamber 40 contains significant color volumes and therefore could be weighed as well. In view of the vibrations prevailing in an inking unit, however, a weighing device was dispensed with at this point and moved in the same way as the volume determination in the color lines.

The on the rollers 41 . 42 or the cliché color in the broadest sense also belongs to the color contained in a color supply system. However, only a fraction of the paint once on one of the rollers returns to the paint bucket 10 so that the volume of this color does not need to be taken into account or only slightly, for example, to close the color composition of the color after a color correction.

The 5 to 8th illustrate the course of the spectral light intensity of a selected color. A special color or color mixture calls for a characteristic course of the spectral intensity of light, which interacts with the ink or with the printing material 6 has, which is printed with the color out. The curve (graph) 50 represents such a characteristic course. A color, which causes such a spectral intensity course of the remittierten light, will leave with the viewer a predominantly blue color impression, since the intensity maxima of the curve 50 range from 380 to 550 nm.

In the 5 to 8th the wavelength in nanometers (nm) on the horizontal axis versus the light intensity L on the vertical axis is plotted in arbitrary units.

The bars 51 are measured values in the first selected wavelength ranges. Measurements in relatively discrete regions are accomplished using measurement devices with wavelength-dependent sensitivity. For this purpose, suitable semiconductor devices are known. Often these are additionally provided with panels for certain areas. Often, only light from limited wavelength ranges is irradiated, so that only remitted light (re-emitted) can be measured in these areas. In 5 a situation is shown in which only a fraction of the spectrum is covered by the measurements. This situation is typical in so-called densitometric measurements. Often, light from nine or less first selected areas in the entire spectral range of visible light (approximately from 380 to 780 nm) is measured (for illustrative purposes in 5 only three in the range between 380 and 550 nm). It is crucial that broad areas 52 of the spectrum of visible light are not investigated in these densitometric measurements. For purposes of this document, these ranges will also become second selected wavelength ranges ( 52 ), which differ from the first wavelength ranges and in which the light intensity L is not measured or even "gaps" 52 called. This is one of the reasons why such prior art measurements are only used to correct the color density job. The density of the ink applied to the printing substrate can be brought about by changing the setting of the rollers involved in the printing process (especially in flexographic printing), by adjusting zone screws (offset printing) or by changing the solvent content of the ink.

A change in the mixing ratio of different color pigments to each other (in a color mixture 11 in an inking unit 8th is used), due to such densitometric measurements is not yet known.

In order to change or redefine this mixing ratio of different color pigments (change of the basic recipe or also change of the color mixture on the machine by adding correction color), so-called spectrophotometric measurements are necessary. 6 clarifies the nature of such a measurement. To the small number of first selected spectral ranges 51 additional selected measuring ranges occur 53 added. Both selected areas often cover the entire area to be measured, which extends from 380 to 550 nm. In a spectrophotometric measurement, there are often no "gaps" 55 or 52 between the selected areas 51 and 53 , In this case, the gaps would have 55 in 6 only representational significance.

At the lower horizontal axis 57 is by the juxtaposition of the spectral sensitivity ranges 56 the channels of a spectrophotometer 54 illustrated how such a measurement can be composed ( 8th ). Such spectral sensitivity ranges can be limited to a bandwidth of 10 nm, which then also allows conclusions about the intensity of the remitted light with such a resolution. In this case, 30 to 40 channels would be needed to map the entire spectral range of visible light. Each channel is assigned a semiconductor sensor, possibly with a corresponding aperture and other optical additional devices. The evaluation of the measurement results takes into account high data volumes and causes great computational effort. For these reasons, it is advantageous to extrapolate from densitometric measured values to spectrophotometric measured values and to use the values obtained also for changing or correcting the mixing ratio of different color pigments to one another in a color mixture or a recipe. A first advantageous step is, in general, based on measured values for the spectral light intensity L in the first selected regions 51 , to a light intensity L in at least one wavelength range 52 . 55 in which no measurement is made, to extrapolate and use the extrapolated values, if necessary together with the measured values, to correct the pigment ratio.

This process can be performed more reliably if the "normal" course of the spectral light intensity L of a color or color mixture (at least over a wavelength range), which in the figures through the curve 50 is shown is known. Individual optical values (above all the comparison of the course of the light intensity L in a measured wavelength range to the course of the light intensity L in an unmeasured wavelength range) can also be very helpful.

In this way, it is also possible to carry out a densitometric measurement which determines the spectral light intensity L, for example in only nine first selected regions 51 measures, to extrapolate one complete spectrophotometric measurement, for example, in 6 is shown, if you fill in the gaps 55 mentally fades in to attract.

7 represents a situation in which there is only one gap in the measurement range from 380 to 550 nm 52 is available. Also in the area of this gap can be extrapolated.

8th clarifies the location of the graph 50 in the entire spectrum of visible light and has, as mentioned, the lower horizontal axis 57 on, which is the juxtaposition of the spectral sensitivity ranges 56 a spectrophotometer 54 clarified.

In the 5 and 8th is sketched by the double arrow TB, the transparency range of the color mixture whose color emission behavior by the graph 50 is pictured. The graph 50 This describes the intensity profile of the remitted light, in the areas of the spectrum in which the color mixture in question has a significant degree of remission. An appreciable degree of remission should, as a rule, be a degree of remission for the printer, which is still perceptible to the viewer. Insofar as such an insignificant degree of remission can be uniformly quantified over the entire light spectrum, it is less than 5%, but advantageously less than 2%.

In the transparency region TB, the color mixture has a greater degree of remission, that is to say the color pigment layer allows more light to pass through the reflection and / or transmission of light through or through the printing substrate.

For the purposes of this document, it is important to note that extrapolating an intensity profile of remitted light 7 - as he uses the graph 50 is shown - also on the basis of a small number (here three) first selected wavelength ranges in which is measured - can be done. On measuring ranges 51 outside the transparency range TB of a particular color mixture can - for the purpose of correcting this color mixture 11 - be completely dispensed with.

9 outlines the situation in a color space E. Starting from an origin point O, which is likely to reflect the color of the printing material, one calculates in a control device 3 . 19 . 23 implemented color mixing software a color recipe, based on a color mixture 21 in a color kitchen 16 is compiled. With this color mixture, a target color location S in a color space (eg LAB, XYZ, LUV, LCH) is to be achieved. The control device 3 . 19 . 23 are the colorimetric properties of the primary colors, the substrate and the mentioned target color location S known in a color space and are based on the preparation of the recipe. With the mentioned color mixture is printed. When measuring with an optical sensor 4 it is found that the actual color location I with the color mixture 21 is reached. There is a deviation ΔK between the actual color location I and the desired color location S. This deviation is given vectorially here in the form of the value ΔK. The specification of the scalar ΔE, which in this case is the magnitude of the vector ΔK, is customary. For the purposes described below, however, the vector ΔK is better.

Some time later, an order is processed on the same printing press, in which the same target color location S is to be achieved with the same inking unit. Advantageously, the color mixtures were 21 , as well as the deviation ΔK stored for this purpose.

The following calculation examples of the vector diagrams in the 9 and 10 , should be in a sense equal pitch color space, for example, in the LAB color space done.

In the present embodiment, the value -ΔK is vectorially added to the target color location S. The result is point S ', which represents an auxiliary target color location. It is advantageous, instead of the target color location S, the auxiliary target color point S 'of the control device 3 . 19 . 23 to be specified as target color location. The control device 3 . 19 . 23 then calculates a color recipe, which is actually intended to reach the auxiliary target color location S ', but with the inking unit in question 8th the target color location S is achieved relatively well.

In a further embodiment of this teaching, it may be advantageous if different successively occurred deviations .DELTA.K, .DELTA.K ₁ , .DELTA.K ₂ , .DELTA.K ₃ ... Are used in the manner described for determining a Hilfsollfarbortes S '. The determination of the auxiliary target color location S 'can then take place according to the following formula: S → = S → - ΔK → ΔK → = | ΔK → | · (S → - I →)

This is in 10 shown.

In 11 is another similar system 1 for providing a color mixture for printing substrate 6 , as in 1 shown. The same reference numerals are used, so that only the differences between the figures or systems must be shown at this point. In contrast to 1 is in 11 in addition a station 60 for the spectrophotometric investigation of parts of the substrate web 6 intended. At this station is a spectrophotometer 54 present, the parts of the printing substrate 58 examined spectrophotometrically and thereby measured values, as in the 6 and 8th are indicated. The parts of the printing material web are usually not "inline", that is in the printing press 2 during operation (= running substrate web) examined, since in this case, enormous amounts of data would be incurred in a short time, since the optical components of the spectrophotometer 54 should have certain qualities. In the future, however, it would seem desirable to also inline (running substrate web 6 , running machine 2 ) to be measured spectrophotometrically. In relation to the 5 to 8th However, densitometric readings can be taken by the optical measuring device 4 be approximated to spectrophotometric measurements. On this basis, correction recipes for one of the two mixing devices 16 and 24 to be won (actually central color kitchen 16 and decentralized mixing device 24 ).

As a rule, one will form two control circuits with the devices mentioned. With a color mixture 21 from the central color kitchen 16 is printed. The recipe, this color mixture 21 can be specified by the customer or the paint manufacturer. However, it can also be obtained by the optical examination of a template. This one becomes a spectrophotometer 54 in preference to a densitometer.

The color mixture created on the basis of the recipe 21 gets to the printing press 2 brought in the paint bucket 10 filled in and it is printed. The resulting color grades are on the current substrate 6 measured. Is the optical measuring device 4 a densitometer, its measured values are approximated in a manner that makes the results of the approximation usable at least in certain wavelength ranges of the remitted light, such as spectrophotometric measured values. In spectral ranges not measured by the densitometer 52 of the remitted light 7 the measured values are approximated and used to determine an actual color location I. Is this Istfarbort 7 in a target area around the target color location (which is often represented as a circle or a ball with a certain radius having the length .DELTA.E _Soll ), the printing operation is not stopped, but it is a correction color mixture 31 Created the paint bucket 10 is also added. In general, this correction color mix 31 from the decentralized color mixing device 16 to be created.

At regular or irregular intervals, a further, additional determination of the Istfarbortes I by a spectrophotometer 54 be performed. For this purpose, after a change of a pressure roller (in sheet-fed press by removing a sheet) substrate 58 be removed and in the station 60 to be examined. Especially if an offline measurement (substrate 58 outside the printing press 2 ) can be determined with sufficient accuracy when the relevant printing material section 58 has been printed, the function of the densitometer and the quality of the approximation can be checked.

The arrow 59 symbolizes in the 11 the transportation or transport of the printing material 58 in the station 60 , The spectrophotometer 54 is via the control line 14 in an advantageous embodiment with the other intelligent components of the system, but at least with the control device 19 connected. LIST OF REFERENCE NUMBERS 1 System for providing color mixing 2 press 3 Control device of the printing press 4 Optical measuring device 5 control line 6 substrate 7 light cone 8th Printing / inking 9 print image 10 paint bucket 11 Color / color mixing 12 weighing device 13 paint line 14 control line 15 paint valves 16 (central) color kitchen 17 Colors (basic colors) 18 Container for the colors 17 19 control device 20 Container for the basic color mixture 21 21 Basic color mixing 22 Viscosity measuring device 23 Control device of a (decentralized) mixing device 24 (decentralized) mixing device 25 Paint container of the (decentralized) mixing device 26 Basic color for correction with a (decentralized) mixing device 24 27 Weighing device of a (decentralized) mixing device 28 Color valve of a (decentralized) mixing device 24 29 junction 30 interface 31 Arrow "Transport of correction color mixture to the printing press" / correction color, correction color mixture 32 Arrow "Transport of the base color mixture to the printing press" 33 Frame of the mobile unit 34 Supports the mobile unit 35 Decentralized, mobile color mixing device 36 bikes 37 Interface of the printing press 38 downspouts 39 mounting plates 40 blade chamber 41 anilox roller 42 cliché roller 43 cliche 44 rectangle 45 Impression cylinder 46 Arrow (color conveying direction) 47 Arrow (color conveying direction) 48 nip 49 guide roll 50 Curve / graph, optical values 51 First selected areas 52 Unmeasured (wavelengths) areas ("gaps") 53 Additional selected measuring ranges 54 spectrophotometer 55 (Performing) gap between measuring ranges 56 Spectral sensitivity range of a "channel" of a spectrophotometer 57 "Lower horizontal axis" 58 Section of the substrate 59 Arrow "Transport of / Information about the section of the printing material 60 Station for spectrophotometric examination 61 Color supply system S Color location, color setpoint, target color location I Istfarbort S ' Hilfssollfarbort K correction vector O origin TB Transparent area L intensity

Claims (18)

Method for controlling the composition of a color mixture ( 11 . 31 ) for at least one printing machine ( 2 ), - at the optical actual values (I) of light ( 7 ), the light ( 7 ) at least with parts of a printed image ( 9 ), which the printing press ( 2 ) on a printing substrate ( 6 ) with a color feed system ( 61 ) of the printing machine ( 2 ) color mixture ( 11 ), has undergone an interaction, and in which, due to deviations of the optical actual values (I) from optical nominal values (S), at least one correction color mixture ( 31 ) generated in the color feed system ( 61 ) of the printing machine ( 2 ) color mixture ( 11 ) is mixed and there the proportions of the color pigments to each other changed, wherein the color mixtures used in the process ( 11 . 31 ) of different color mixing devices ( 16 . 24 ), characterized in that - the first color mixing device ( 16 ) a color kitchen ( 16 ), which is used to provide color ( 11 ) for a first number (N) of printing presses ( 2 ), and that the second color mixing device ( 24 ) a decentralized mixing device ( 24 ), which is used to provide color ( 11 ) for a second number (M) of printing presses ( 2 ), the first number (N) of printing presses ( 2 ) greater than or equal to the second number (M) of printing presses ( 2 ). Method according to the preceding claim, characterized in that the second decentralized mixing device ( 24 ), which provide color ( 11 ) for a second number (M) of printing presses ( 2 ), a single press ( 2 ) assigned. Method according to one of the preceding claims, characterized that the composition of the color mixture ( 11 ) on at least two printing presses ( 2 ) and that at least one of the color mixing devices ( 16 . 24 ) between at least two printing presses ( 2 ) is moved to these printing machines ( 2 ) Color mixtures ( 11 ). Method according to the preceding claim, characterized in that the second color mixing device ( 24 ) between at least two printing presses ( 2 ) is moved to these printing machines ( 2 ) Color mixtures ( 11 ), a color delivery system ( 61 ) of an inking unit ( 8th ) of the printing machine ( 2 ) supplies different color components, and that these color components only in the color supply system ( 61 ) mix. Method according to one of the preceding claims, characterized in that at least one of the measurements with which optical actual values (I) are obtained is a densitometric measurement which only measures the light intensity (L) in first selected wavelength ranges ( 51 ), the subregions of a transparent region (TB) of the relevant color mixture ( 11 ) are included. Method according to one of the preceding claims, characterized in that from the densitometric measured values ( 51 ) Light intensity (L) estimates in second selected wavelength ranges ( 52 ), which differ from the first wavelength ranges ( 51 ) and in which the light intensity (L) is not measured, are derived. Method according to the preceding claim, characterized in that optical values ( 50 ), which in the interaction of light with the used color ( 11 ) or the color components used in an earlier measurement, are taken into account in the estimation. Method according to one of the two preceding claims, characterized in that in the estimation at least parts of a curve ( 50 ), the curve ( 50 ), the light intensity (L) of the remitted light ( 7 ), which is due to the interaction of light with the color ( 11 ) or the color components used in a wavelength range. Method according to one of the four preceding claims, characterized in that the densitometric measured values of the preparation of correction mixtures ( 31 ). Method according to one of the four preceding claims, characterized in that at least one of the measurements with which optical actual values (I) are obtained is a spectrophotometric measurement, the measurements of the light intensity (L) in all wavelength ranges ( 51 . 52 ) of a region of a transparent region of the respective color mixture. Method according to the preceding claim, characterized in that spectrophotometric measured values of the production of basic mixtures ( 21 ). Method according to one of the two preceding claims, characterized in that spectrophotometric measured values are used to check the quality of the densitometric measured values and / or the estimate. Method according to one of the preceding claims, characterized in that to provide the correction color mixture ( 31 ) less different varieties of primary color ( 26 ) are used as for the production of the basic color mixture ( 21 ). Method according to one of the preceding claims, characterized in that at least on one of the following devices measurements of the color mass and / or the color volume are made and that these results are taken into account in the preparation of the color mixtures: - to color containers ( 18 ) of the central color kitchen ( 16 ) - on paint containers ( 10 ) at least one printing machine ( 2 ) - on paint containers ( 25 ) of the decentralized mixing device. Mixing device ( 24 ) for providing color mixtures for at least one printing machine ( 2 ), which mixing device ( 24 ) at least two paint containers ( 25 ) and two metering devices ( 13 . 38 . 28 ), wherein the mixing device ( 24 ) with means of locomotion ( 36 ), preferably wheels ( 36 ) equipped with interfaces ( 30 ) to external control components ( 3 . 19 ), which provide data on the at least one printing press ( 2 ) required color mixtures ( 11 . 31 ) are transferable. Mixing device ( 24 ) according to the preceding claim, characterized in that the mixing device ( 24 ) with a control and evaluation device ( 23 ) Is provided. Mixing device ( 24 ) according to the preceding claim, characterized in that at least part of the metering devices ( 13 . 38 . 28 ) of the mixing device ( 24 ) with the control and evaluation device ( 23 ) of the mixing device ( 24 ) is controllable. System ( 1 ) for controlling the composition of a color mixture for at least one printing machine ( 2 ), - which at least one optical measuring device ( 4 . 54 ), with the optical actual values (I) of light ( 7 ) are recordable, whereby the recordable light ( 7 ) at least with parts of a printed image ( 9 ), which with the at least one printing machine ( 2 ) on a printing substrate ( 6 ) with one in a color delivery system ( 61 ) of the printing machine ( 2 ), has interacted, and which constituents ( 16 . 24 . 35 ), with which due to deviations of the optical actual values (I) from optical nominal values (S) at least one correction color mixture ( 31 ) which can be generated in the ink feed system ( 61 ) of the printing machine ( 2 ) color mixture ( 11 ) can be mixed with one another to change the proportions of the color pigments to one another there, which comprises at least two different color mixing devices ( 16 . 24 ), with each of which color mixtures ( 11 . 31 ), characterized in that - the first color mixing device ( 16 ) a color kitchen ( 16 ), which is used to provide color ( 11 ) for a first number (N) of printing presses ( 2 ), and that the second color mixing device ( 24 ) a decentralized mixing device ( 24 ), which is used to provide color ( 11 ) for a second number (M) of printing presses ( 2 ), the first number (N) of printing presses ( 2 ) greater than or equal to the second number (M) of printing presses ( 2 ).

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