EP0123257A2 - Method and device for regulating the ink supply in the inking units of multicolour printing machines - Google Patents

Abstract

When producing a multi-color print, precise and economical regulation of the coloring of the shape can be achieved by converting the optical frequencies corresponding to the light remitted by a template (1) into acoustic frequencies by means of a light pressure converter (4) and by means of a frequency filter device (9). are divided into narrow frequency ranges, which are detected spectrally according to intensity by means of an evaluation device (10), and that the resulting intensity values are set in relation to the colors used to produce the multicolour print and regulating variables, preferably the zone screws, are used to supply the colors used (15) regulating variables.

Description

According to a first idea of the invention, the invention relates to a method for regulating the zone-by-zone ink supply fed from a color memory to the inking units of a multicolor printing machine, in particular for regulating the position of zone screws influencing the ink supply, and according to a further inventive concept to an apparatus for carrying out this method.

To regulate the zone screws, test strips have been printed on the edge of the actual print image Use. These test strips consist of solid color fields provided for each inking unit zone and assigned to the primary colors used. These spot fields are recorded densitometrically and compared with a target value to determine whether there is a lack of color or excess color. The disadvantage here is that a certain area must be reserved for the test strips on the substrate per cylinder circumference. This not only means a loss of available usable space, but also requires a great deal of effort to subsequently remove the test strips mentioned when further processing a printed web into sheet-like products. Another disadvantage is the only very rough resolution of the color spectrum, which is far from the function of the human eye. The color spectrum is practically broken down into just three fields corresponding to the primary colors. In practice, however, it is not uncommon for the colors used to contain a certain proportion of another color. For example, the blue may have a slight red cast or the like. However, this cannot be determined in the case of the rough resolution of the color spectrum mentioned. The consequence of this can therefore be that if blue and red are overprinted, the red component is obviously too large for the eye and the blue component becomes too small, even though the full-tone areas of the test strips correspond to the desired value. The print quality that can be achieved is therefore not quite up to high demands.

Proceeding from this, it is therefore the object of the present invention, while avoiding the disadvantages of the known solutions, to provide a method of the type mentioned at the beginning which does not require test strips and nevertheless enables a comparatively high print quality. According to a further object of the invention, a device for carrying out the method is to be created which is simple in construction and nevertheless ensures high accuracy.

In terms of method, the solution of the parent object is achieved in a surprisingly simple manner by the corresponding the extracted from one of the current production submission of at least one inking zone corresponding width remitted light optical frequencies are reacted ^q Uenzen in acoustic frequency and spectrally detected by intensity and that the resultant intensity values are set in relation to the colors used for producing the multicolor print and regulating variables are implemented in the supply of the colors used.

The device according to the invention for solving the object on the device side is characterized by at least one light pressure transducer which can be acted upon by a light which can be exposed to light at least in zones, the output signals of which can be recorded by means of an acoustic sensor and transmitted to an acoustic receiver, one of which assigns the assigned spectrum to any one A number of frequency filter devices dividing frequency ranges is arranged, whose output values assigned to the individual frequency ranges can be implemented zone by zone by means of a downstream evaluation device in the manipulated variables assigned to the colors used for producing the multicolor print.

The conversion of the optical frequencies of the colored light remitted from the original into acoustic frequencies advantageously enables frequency filtering without loss of intensity. The entire intensity of the circularly polarized light is therefore included in the result. Polarization of the light and associated intensity losses are advantageously not required here. This therefore gives measured values with a high intensity level. The influence of disturbance variables on the measured values obtained is therefore advantageously small. At the same time, the conversion of the optical frequencies into acoustic frequencies enables the use of acoustic sensors which are advantageously not only extremely robust, but also have a uniform sensitivity over the entire spectrum. Another advantage of the measures according to the invention can be seen in the fact that no mechanical movement of parts of the optics or no geometric representation of the template are required here. Rather, the light pressure converter used can process a luminous flux of any shape, which has a positive effect on the construction of the required optics. A very particular advantage of the measures according to the invention can be seen in the fact that a high selective sensitivity can be achieved, ie. that the division of the spectrum on the acoustic side can advantageously be carried out in such a fine manner that a resolution of the recorded frequency band covering the entire optical spectrum that is appropriate for the resolution of the human eye is achieved. The measures according to the invention practically provide an intensity which corresponds very precisely to the actual color of the original tity curve across the entire spectrum, which also allows the semitones etc. which are spectrally located in the transition regions to be detected without further ado and assigned to the spectral range of the colors used. The fine screening advantageously also enables the use of colors which deviate from the standard colors in the tinting without this having a negative effect on the result, which increases the versatility of a printing press with regard to the colors to be used. The foregoing makes it clear that the invention achieves its object with simple and inexpensive means. The advantages that can be achieved with the invention can therefore be seen in particular in excellent economy.

The cited light pressure converter is a known component for converting a light signal into a corresponding acoustic signal. However, arrangements of this type have so far only been used to determine the type of composition of a liquid or a gas. Here, a light pressure converter containing the medium to be determined is acted upon by monochromatic light. The acoustic signal that can be recorded by means of an acoustic sensor can be set in relation to the material properties of the medium. From this, however, no reference to the combination according to the invention could be seen.

Furthermore, it is also known to determine the intensity of light across the entire spectrum with the aid of a so-called acousto-optical filter. Derar term acousto-optical filters are excited by means of a vibration generator and only allow a certain frequency range dependent on the excitation to pass through. Devices of this type have so far been used for polarizing light in light guide systems. However, polarization of the light is clearly required here. However, this means that a large proportion of the light intensity is lost. The achievable measured values are therefore at a very low level, so that disturbances can have a noticeable influence. Accordingly, no suggestion for solving the object according to the invention could be derived from this either.

The light pressure converter is advantageously subjected to light chopped according to its natural frequency. This measure advantageously results in self-reinforcement.

To accomplish a simple calibration of the device according to the invention, the intensity values remitted from an existing template can be compared with the intensity values resulting in full light and the intensity difference values can be converted into corresponding manipulated variables, preferably after comparison with corresponding target values.

To achieve a suitable evaluation curve, light with a known spectrum, in particular intensified daylight, is expediently used.

Another expedient measure can consist in the fact that the running printing material web is used as a template in a web-fed rotary printing press, whereby the light remitted therefrom is integrated over a predetermined distance, preferably corresponding to a cylinder circumference. This measure allows advantageously an ongoing surveil _- monitoring the coloring based on the moving paper web and therefore represents advantageously a very short-term intervention option available.

In a further development of the higher-level measures, the frequency intensity can be determined within the range of 10 to 20, preferably 15, frequency ranges of the same width. Such frequency ranges can advantageously be filtered out on the acoustic side without loss of intensity from the frequency band received by means of a so-called panorama receiver. The division of the Fre ^q uenzbands in 10 to 20, preferably 15 frequency ranges resulting in an advantageous manner already a 4- to 5-fold finer resolution than is achievable with the known three-filter method. The individual frequency ranges are expediently filtered out of the recorded frequency band one after the other. For this purpose, a so-called panorama receiver can be followed by a frequency filter that can be set and queried by a computer for each frequency range. This measure ensures that you can practically get by with a Freauenzfilter that is set and queried accordingly, which greatly simplifies the calibration.

In a further advantageous development of the superordinate measures, the light pressure converter (s) can each be formed by a glass body. This measure advantageously results in a high level of accuracy and nevertheless proves to be extremely simple and inexpensive.

Further expedient further developments and advantageous refinements of the superordinate measures result from the following description of an exemplary embodiment with reference to the drawing in conjunction with the remaining subclaims.

• Figur 1 ein Blockschaltbild einer erfindungsgemäßen Regeleinrichtung und
• Figur 2 ein Intensitäts-Frequenz-Koordinatenkreuz.

The drawing shows:

• Figure 1 is a block diagram of a control device according to the invention and
• Figure 2 shows an intensity-frequency coordinate cross.

The structure and mode of operation of a multicolor printing press, for example in the form of a high-pressure or, in particular, an offset roll rotary printing press, are known per se. In FIG. 1, the printing material printed multicolored in such a web-fed rotary printing press is only indicated schematically on the basis of a paper web 1. The print quality here depends in particular on the correct coloring of the shape. Both excess color and lack of color can be harmful. However, since the required color density differs across the machine width, it is known that it is divided into several zones, each of which is assigned a zone screw that determines the ink supply. In the present case, the setting of the zone screws, not shown, is set as a function of measured values taken directly from the respective zones of the print image present on the paper web 1, so that a number of controlled systems corresponding to the number of zones present is obtained results in compliance with the desired coloring.

The measured values to be recorded here consist of colored light remitted by a template containing the printed image and generated by means of a light source 2. In the case of a sheet-fed machine, the template can be a sheet taken from the current production. In the case of a rotary printing press, this is expediently, as already mentioned above, the printed material web or respectively a web section corresponding to a forme cylinder circumference. A light source 2 is provided per zone, through which light is applied to the original. Here, light with a known spectrum is used to achieve an exact evaluation. In this context, light with the spectrum corresponding to daylight has proven to be expedient. Daylight lamps with an output of 4000 to 5000 Kelvin have proven to be expedient as the light source 2 for generating appropriately amplified daylight. The light sources 2 respectively assigned to the adjacent zones of the paper web 1 are expediently arranged in the region before the paper web 1 enters a folding device arranged downstream of the printing press. The arrangement can be offset relative to one another in the direction of the running direction of the web so that there is no fear of mutual interference if all light sources are activated at the same time. However, this can also be achieved in an advantageous manner by activating the light sources 2 in a correspondingly graduated manner.

The light cast by each light source 2 onto the respectively assigned zone of the paper web 1 is, as indicated by the beam path 3, remitted by the paper web 1. The remitted light is fed to a light pressure converter 4. This is a device that contains an anisotropic medium, i.e. a medium that reacts to light printing in such a way that a known response in the form of a frequency in the range of the acoustic spectrum is assigned to each frequency in the range of the visible spectrum. This can be a chamber filled with a gas or a liquid. In the exemplary embodiment shown, a glass body 5 with a crystalline structure is used as the anisotropic medium. The glass is doped with foreign atoms so that the same light pressure is achieved across the entire spectrum. The glass body 5 is accommodated in a housing 6 which is open on the light input side. In order to bring about an amplification of the resulting light pressure, it is expedient to apply light chopped according to the natural frequency of the respectively assigned light pressure transducer 4, so that corresponding resonance phenomena result. 1, each zone of the paper web 1 is assigned a light source 2, each with a downstream light pressure converter 6. These units can therefore be arranged stationary. However, it would also be conceivable for an arrangement to be movable over the width of the paper web. In such a case, one would get along practically with an aggregate.

The output signals of the light pressure transducers 4 present here in a number corresponding to the number of zones are combined with an associated acoustic signal Sensor 7, in the form of a microphone attached to the respectively assigned light pressure transducer 4, is recorded and fed via it to an acoustic receiver 8 in the form of a so-called panorama receiver, which can receive all frequencies over the entire spectrum.

The receiver 8 assigned to each zone here thus receives an acoustic spectrum which corresponds to the optical spectrum of the light supplied to the respectively assigned light pressure converter 4. The intensity of the received acoustic frequencies is thus an exact measure for the intensity of the optical frequencies of the remitted light and thus for the intensity of the coloring of the printed image contained on the scanned paper web 1. The acoustic frequencies recorded by the receivers 8 per zone are recorded spectrally according to intensity. To this end, the entire range is ^q in an arbitrarily large number of adjacent, non-overlapping end Fre divided rich uenzbe-. A division into 10 to 20, preferably 16, frequency ranges of equal width has proven to be expedient. These areas are filtered out of the spectrum received by the receivers 8.

For this purpose, a frequency filter device 9 is arranged downstream of the receivers 8. This can consist of a number of individual frequency filters corresponding to the number of desired ranges, each of which is assigned to a frequency range. In the exemplary embodiment shown, only one frequency filter is provided to form the frequency filter device 9, which can be adjusted to the desired frequency ranges, which facilitates the calibration. The frequency filters 9 are controlled by means of a central computer 10, which polls all frequency ranges of the respectively connected frequency filter 9 one after the other. The query time is very short, so that the results assigned to each zone are available practically simultaneously. The computer 10 can normally query the frequency filters 9 assigned to all zones at the same time. For this purpose, the computer 10 is provided with a corresponding number of inputs 11. The frequency filters 9 are controlled via the control line 19.

The computer 10 determines from the intensity values queried for each zone, each assigned to a frequency range, an intensity curve 12 that extends across the entire spectrum, which may have the course indicated by dash-dotted lines in FIG. 2 and that is used to create corresponding zone screw manipulated variables in relation to the the spectral ranges assigned to the primary colors yellow, red, blue can be set, so that actuating signals assigned to the zone screws of the successive inking units can be determined therefrom. Each basic color can be represented in the coordinate system according to FIG. 2 as a parabolic intensity curve 13 drawn as a solid line in FIG. 2, mutual intersections being present in the edge regions, so that a division of the entire spectrum according to such a three-part grid should lead to inaccuracies. In the present case, the entire spectrum is therefore subdivided into several, preferably 15 narrow, non-overlapping frequency ranges 14, which accordingly results in a very fine resolution and enables good assignment even in the intersection areas of the three-part color grid. The determination of the manipulated variables assigned to the individual colors can be carried out simply in such a way that the areas delimited by curve 12 are in each color intensity 13 lying frequency ranges 14 are integrated over the individual color intensity curves 13 and that the resulting values are compared with the area of the respectively associated color intensity curve 13. The manipulated variable is formed from the resulting difference. Because of the fine division of the entire frequency band, a simple assignment of the areas 14 to one or the other color is possible here in the intersection areas of the color intensity curves 13.

The central computer 10 practically forms a central evaluation device through which all zone screws 15 of all inking units can be operated. The zone screws 15 assigned to the same zone in each case in the area of the inking units assigned to the printing units arranged one behind the other here each form a zone screw group 16, to which a light pressure converter 4 with an upstream light source 2 and a downstream receiver 8 is assigned, which enables simultaneous data recording and data processing. However, as already indicated above, it would also be conceivable to provide only a corresponding receiving device which is moved from zone to zone. Each zone screw 15 is assigned a servomotor 17 which can be controlled by the computer 10. The computer 10 is provided with a corresponding number of outputs.

If the running paper web 1 is used as a template, as in the present case, the light sources 2 assigned to the individual zones are controlled by the computer 10 by means of a signal line 18 so that the paper web 1 is only in each case during the passage of a distance or a cylinder circumference a whole multiple of it is flashed at. As already mentioned at the beginning, chopped light corresponding to the natural frequency of the respective light pressure transducer 4, which allows a desired amplification to be expected and at the same time enables simple integration of the light values resulting over the detected web section. Corresponding control lines 19 are provided for controlling the interrogation frequency filter 9 by means of the central computer 10.

The actuating variables which can be set with the aid of the servomotors 17 are determined by comparing the measured values with those stored in the computer 10, by evaluating an ideal template, e.g. B. by evaluating the original from which reprints are to be made, the desired values obtained. If there are deviations, these are converted into corresponding actuating signals for activating the actuating motors 17 respectively assigned to the zone screws 15. To calibrate the entire arrangement, an evaluation curve of the type indicated in FIG. 2 at 20 is specified per zone, which is an intensity curve when the light pressure transducer 4 is directly acted upon by the associated light source 2, that is to say with the light source 2 not being remitted from the paper web 1, but directly emitted light is obtained. The difference values resulting from the comparison of the intensity curve 12 with the evaluation curve 20 are set in relation to target values taken in the same way from an ideal template. The resulting deviations go into the control signals assigned to the colors. In some cases, it may also be expedient to evaluate the evaluation curve 20 by evaluating an unprinted one Paper web to attract reflected light. This can be of particular advantage when using tinted or colored paper.

Claims (10)

1. A method for controlling the zone-by-zone ink supply fed from a color memory to the inking units of a multi-color printing press, in particular for regulating the position of the zone screws (15) influencing the ink supply, characterized in that the template (paper web 1) taken from one of the current production optical frequencies corresponding to at least one inking unit zone of correspondingly wide width are converted into acoustic frequencies and spectrally ordered according to intensity, and that the resulting intensity values are set in relation to the colors used to produce the multi-color printing and are used to regulate manipulated variables in the supply of the colors used will. 2. The method according to claim 1, characterized in that the intensity values determined in each case from the templates corresponding to the individual zones can be compared with predetermined target values, preferably obtained by evaluating an ideal template, with appropriate manipulated variables being formed from the deviations. 3. The method according to any one of the preceding claims, characterized in that the intensity values remitted from an existing template are compared with the intensity values resulting in full light and the intensity difference values are converted into manipulated variables after comparison with corresponding target values. 4. The method according to any one of the preceding claims, characterized in that in the presence of a running printing material web (paper web 1) this is used as a template, the light remitted therefrom is integrated over a predetermined distance corresponding to a cylinder circumference or a whole multiple thereof . 5. The method according to any one of the preceding claims, characterized in that the templates assigned to all the inking zones are processed simultaneously. 6. The method according to any one of the preceding claims, characterized in that the frequency intensity within an arbitrary number covering the entire frequency spectrum, preferably fifteen, non-overlapping, preferably equally wide frequency ranges (14) is determined, the individual frequency ranges (14) from the resulting acoustic frequency band, preferably in succession, be filtered out. 7. The method according to any one of the preceding claims, characterized in that light, preferably with light that is chopped according to the natural frequency of the associated light pressure converter (4), with a known spectrum, in particular enhanced daylight, is used. 8. Apparatus for carrying out the method according to one of the preceding claims in a multi-color printing press with inking units with a device for regulating the zone-wise ink supply fed from a color memory, in particular with a device for regulating zone screws (15) influencing the ink supply, characterized by at least one With a light pressure transducer (4) that can be acted upon by a light that is exposed to light (paper web 1) in zones that is remitted with light, the output signals of which can be recorded by means of an acoustic sensor (7), preferably designed as a microphone attached to the associated light pressure transducer (4), and preferably on that Whole frequency spectrum of receiving panoramic receivers, acoustic receivers (8) can be transmitted, to which a computer dividing the assigned spectrum into any number of frequency ranges can be set and adjusted accordingly by a computer (10) to each frequency range (14) a frequency filter device (9) that can be queried is arranged downstream, the output values assigned to the individual frequency ranges (14) in zones by means of a downstream evaluation device (computer 10), preferably by means of the individual inking unit zones All actuators assigned to all inking units (servomotors 17, zone screws 15) can be controlled, and actuating variables assigned to the colors used for producing the multicolor printing can be implemented. 9. The device according to claim 8, characterized in that for each inking zone, a light pressure converter (4) with upstream light source (2) and with a downstream receiver (8) and this associated frequency filter device (9) is provided. 10. Device according to one of the preceding claims 8 to 9, characterized in that each light pressure converter (4) contains a glass body (5), which is preferably arranged in a housing (6) which is open on the light input side and which preferably consists of glass so doped with foreign atoms that the Illuminated printing is almost constant across the entire spectrum.

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