Patent Application
20130291749
The invention relates to a method according to the preamble of claim 1 and an apparatus according to the preamble of claim 25. Using an apparatus and method of this type, the distance between at least two cylinders of a printing unit involved in the printing process are set.
This is necessary for various printing methods prior to the initiation of the actual printing operation. Thus, DE 44 27 967 B4 could be assigned to the offset printing method. This citation suggests feeding a paper strip through between two ink-transporting cylinders. The width of the region provided with ink in this manner is subsequently measured. In particular, if the region is too small, the setting between the rollers in question is increased.
The optimization of the setting is of particular interest in the field of flexography, as in this case relatively thick, very flexible printing plates are used, which—in particular together with the substructure thereof—have large thickness tolerances. In this context, EP 1 249 346 B1, among others, suggests using optical sensors to observe the print image of the printing machine on the printing material for setting the rollers. A control device determines the optimized relative position of the rollers involved in the printing process to one another based on the measured values and sets this position. As, according to this teaching, the measurement of the—still flawed—print image on the printing material is the foundation for setting the print roller position, spoilage is inevitably generated during the setting of the roller position.
This circumstance is criticized by EP 1 916 102 A1. As a remedy, this document suggests measuring the diameter of the plate cylinders. Based on the measurement results obtained at the plate cylinder, a control device determines the optimized relative position of the plate cylinder to the other cylinders involved in the printing process. Based on these values, the control device of the printing machine sets the position of the plate cylinder in the printing machine. In this way, a proof should be pulled without spoilage.
This teaching, however, disregards the fact that, in addition to the pure diameter of the printing plate, variables such as the modulus of elasticity or the color splitting behavior of the respectively printed ink also influence the printed result.
A further document, which addresses the optimization of ink transfer from the rollers involved in the printing process in the offset printing process, is DE 102 11 870 A1, which suggests moving rollers, which transfer ink in the printing process, toward one another in the idle state (no rotation around the primary axis of symmetry). If the first of the two rollers in the ink-transportation direction is inked at the moment of the mutual adjustment, a strip of ink arises on the second roller. This strip of ink is clearer if the two rollers touch each other for a period of time in the idle state.
This strip of ink can be measured using a Line scan camera, among others, after the second roller has been rotated around an angle from the contact position to another position, in which the strip of ink generated can be seen.
The width of the strip of ink is a measurement for the contact pressure between the rollers, such that the correct pressure can be assumed at a certain width. In case the strip has a rectangular shape (equal widths), the primary axes of symmetry of the two rollers are moving parallel.
Beyond this, the strip of ink itself, which consists of dried ink, can reduce the printing quality at the beginning of printing, and thus lead again to the accumulation of spoilage.
The present invention arises from the last-cited document. The object of the invention is to remedy the previously cited disadvantages.
The problem is solved by the characterizing features of claims 1 and 25. The change in the film of ink can consist in a removal of ink, which is transported by the cylinder in question. It can also, however, come about without a removal of ink, such that the surface of the film of ink changes as a result of a contact pressure. Further details of the phenomena mentioned are primarily discussed in the objective description.
A basic concept of the present invention thus consists in detecting the change in the film of ink on an ink-transferring cylinder. In so doing, the measurement is carried out on at least one cylinder, which is mounted upstream in the ink-transport direction (23) of the second cylinder (7) which receives ink during the printing process.
Expressed differently, a measurement is taken at a cylinder, which is mounted upstream from the roller gap in the ink-transport direction, wherein the roller gap of the two cylinders is delimited by the two cylinders, the pitch thereof being set. A measurement can also be taken at the first cylinder which delimits the gap. Alternatively or supplementally, a measurement can also be taken at an additional cylinder mounted upstream in the ink-transport direction.
In the manner described, an ink transfer, which comes about using realistic preconditions, can also underlie the detection of the optimized relative position of the rollers, without causing necessary spoilage. Thus, when using a flexographic printing press, the adjustment between anilox roller and plate cylinder is optimized on the basis of the observation of the anilox roller, without causing spoilage. An adjustment of the roller unit, anilox roller/plate cylinder, being well positioned against one other, at the impression cylinder can then be carried out while producing spoilage. Tests have shown that in the ultimately mentioned case, it is also possible to determine the contact between the plate cylinder and the printing material on the anilox roller: In this case, ink streaks, which have formed on the printed material due to insufficient ink transport, now disappear.
It should be added that the relative position of the two cylinders already adjusted with respect to one another—in this case anilox roller and plate cylinder—should advantageously not change during the adjustment at the impression cylinder.
At this point, it should be explicitly mentioned once more, that an impression cylinder, which guides the printing material at the surface of said cylinder, so that ink is transferred to the printing material in the printing operation, is also, within the meaning of this citation, an ink-receiving cylinder.
The previously mentioned method for optimizing the plate cylinder position according to DE 102 11 870 A1 additionally requires a large expenditure in time, as the cylinders must be paused for a certain period of time, as mentioned, so that the ink strip develops on the second cylinder.
With regard to the inventive method, it is advantageously possible to analyze the film of ink at the rotating cylinders. In this case, the cylinders can continue to rotate. It is advantageous to carry out at least one continuous rotation (360° around the primary symmetrical axis), at least two or more rotations of this type. During a part of the inventive method, the cylinders rotate during the entire test or sensing run.
Interestingly, it is also possible to measure a contact between downstream mounted ink-transporting cylinders at an upstream mounted cylinder, without implementing a printing process, that means without ultimately transporting the ink to the printing material.
It is, however, advantageous in exactly this context to conduct the measurement and adjustment of the operating distance within a few rotations (e.g., 1, 2, or 3), because otherwise saturation effects develop in the region of the contact surface.
As a rule, the adjustment of the roller distance based on the measured values is implemented by a control device installed for this purpose. For this purpose, the control device is, as a rule, loaded with a corresponding computer program. Anyway, it is advantageous to carry out or support all inventive methods as computer-implemented in this way.
This method is also advantageous in the case of the presence of only two rollers. Thus, for example the removal of ink from the gravure cylinder—that is the printing plate cylinder—is measured in the case of gravure printing machines. The impression roller or general impression cylinder is involved in the printing process in this case; however, it is not involved in the transport of ink to the printing material or into the print gap.
By this means, the method has advantages for two rollers as well as for a transport of ink via a multiplicity of cylinders and a measurement of the film of ink at one of the previous rollers. As mentioned, the covering of the surface of the roller with ink also changes in the ultimately mentioned case, when the rollers downstream in the ink-transporting direction are contacted against the subsequent roller or the printing material, and ink is actually transported onto the printing material.
As has likewise already been addressed, it is advantageous to observe the film of ink at an anilox roller used for example in flexographic printing. Said rollers primarily lose ink when further cylinders are contacted.
In various printing methods, however, smooth rollers are also used for inking further rollers involved in the printing process.
It should be added at this point, that the terms roller and cylinder are used in this document as interchangeable or equivalent to one another.
In determining the optimized relative position of the at least two rollers, the question is: how strong the change in the area of coverage on the roller must be, so that the control device has initial reference points for an optimized roller distance and ends the test run. In this context, “test run” is understood as the phase of convergence of the rollers, during which the measured values are obtained, which are used to determine a first optimized relative position.
A possibility exists thereby to end the test run as soon as a change in the film of ink is indicated at the roller at which the measurement is taken. Naturally, the amount of ink, which is transferred at this point in time, is dependent on the sensitivity of the measurement system. As a rule, however, in this way a contact situation could be found, which is known to printers as “kiss print.” At this point, a first, light contact between the rollers occurs.
At this point, for example, the further measurement of ink transfer can be ended. A further convergence can, however—as needed—be implemented by the control device. Thus, after achieving this “kiss print point,” or in this case a first optimized relative position, an adjustment of the cylinders toward one another by an empirically or computationally determined offset value—thus a further convergence of the cylinders by an amount of distance—can be effected by the control device. In this way, an optimized operating distance between the effected cylinders can be achieved, which is indeed as a rule not yet fulfilled by achieving a kiss print point.
An essential alternative to this process consists in that the convergence of the cylinders is further continued at simultaneously analyzed measurement—“the test run”—until a primary threshold value or tolerance value is achieved—in this case the removal of ink. This primary threshold value can be selected such that the optimized operating distance between the cylinders is already achieved upon exceeding the primary threshold value, such that no further measures are required in this regard. According to this, the adjustment of the relative positions of the rollers would be ended at the end of the test run and the optimized operating distance would coincide with the first optimized relative position. However, upon reaching this threshold value for the removal of ink at the cylinder, at which the measurement is taken, a further convergence of the cylinders by an amount of distance (“offset value”) can additionally be implemented.
A further possibility for determining an optimized print infeed situation consists in tracking the course of the removal of ink as a function of the relative roller position. The possibility then exists, at the onset of a characteristic progression of this function, based on experience and calculations, to assume the achievement of the optimized relative position of the cylinders. Thus, achieving the optimized print position of the cylinders often shows prematurely, because the ink transfer scarcely increases after reaching this position, but instead enters into the saturation range at further convergence of the rollers. Due to these issues, the function under discussion often has turning points or relative maximums in the range of the optimized print position. Characteristic points of this type can be used by the control device for determining the optimized printing position. Often, an optimized relative print position determines a “secondary threshold value” (i.e., a further amount of ink removal) or an “offset value” (i.e., a certain amount of distance) at a distance from a characteristic point of this type. If the progression of the function is recorded far enough to calculate the position of such points, the test run can also be ended at this point.
Method steps like recording the function of the change in the film of ink/relative roller position, ending the test run, detecting one or more characteristic points of this function, overriding a threshold value and/or offset value, can be carried out in a computer-implemented way by the control device. This also applies naturally for the other methods introduced in this document.
It should be gathered from the previous embodiment, that the offset values and the secondary threshold values can be used in conjunction with all of the methods presented, which determine the duration of the test run. The mathematical sign of the offset value (“more or less infeed”) or the secondary threshold values (more or less ink transfer) can be positive or negative.
It is advantageous to limit the region of the cylinder or of the roller, at which the measurements are taken, to the region in which ink can be removed. As a rule, the maximum measuring range of the sensor device is therefore oriented at the maximum print range (often the same or somewhat larger). A possibility for realizing this consists in the use of a line scan camera, which can display the maximum printing width. This camera is suspended at the affected cylinder in a working position, in which it can scan the print range of the machine. It makes sense to disassemble the entire measuring range of the sensor system into sections. The sensor system itself can already be modularly constructed—e.g., from photo diodes. In this case, the modules of the sensor system already deliver partial images of the entire measuring range, which then no longer need to be disassembled into sections by a calculating unit.
In addition to the disassembly of the entire contact surface possible between two cylinders into various sections, it is also worth considering the measurement of the change in the film of ink in a subset of the sections. Thus, under certain circumstances, a measurement in a one square centimeter large section can suffice. With new sensors, sections with an area in the range of a square millimeter are also conceivable. As compression rollers are mounted at the two face ends thereof, it is therefore advantageous to carry out measurements in the respective region of one or both faces, in order to obtain measured values for each of the two sides. In particular, in fields of print technology, in which large tolerances at printing plates and rollers are considered—as in packaging printing—a plurality of measurements is advantageous.
If measurements are carried out in a plurality of sections, then the previously sketched methods for determining the optimized relative print positions of the cylinders involved are advantageously applied to the sections. The optimized contact situation may be considered to be advantageously achieved when the conditions of the respective method are satisfied in a subset of sections.
As mentioned, optical sensors such as cameras can be considered as sensor devices. The expression, “optical sensors and cameras” is then also used in this context, when non-visible electromagnetic radiation is recorded.
If electromagnetic radiation is measured, then the prismatic light intensity is an advantageous measurement variable (light intensity per prismatic range per surface). In this case, it is advantageous to provide a specific radiation source, which radiates the appropriate radiation on the roller. The sensors then measure the remitted radiation. When mounting the radiation sources and sensors, the laws of reflection should generally be observed (as is shown, among others, in the figures).
A device for determining an optimized operating distance between two cylinders involved in the printing process can be equipment specific to a printing unit or can be, from the view of the printing machine, an external rack with corresponding additional measures. A commonality of these devices is that recesses are provided, in which the impression cylinders are rotatably mounted and adjustable with respect to one another. In addition, the preparation of the impression cylinder for printing, that is, equipping with the printing plate, can take place in an external rack. For this purpose, a rack of this type can be additionally equipped with device features, which are appropriate for the so-called mounters that are typically used for equipping flexographic impression plate cylinders. A device of this type is described for example in U.S. Pat. No. 5,132,911 B. In more recent times, rack-type devices have also become known in the field of the preliminary stage of flexography, in which devices a plate cylinder is likewise rotatably mounted. Said cylinder is, however, provided with a smooth, still completely unprocessed, rubber type cliché, which is processed by a laser ablation unit to form the desired printing plate. An inventive apparatus can also be equipped with a laser ablation unit of this type or another gravure unit for processing the cliché. A unit of this type is shown in WO 9713641.
If the invention is realized in an external unit, then it is also not necessary to actually set the relative distance ultimately considered to be optimal between the participating cylinders in the external unit. On the contrary, it is necessary in this case to forward the data determined to the actual printing machine, which then also sets these values. For this forwarding of information, all known possible means of communicating between the devices come into consideration, as well as a memory in the relevant cylinders (e.g., RFID with read options in the printing machine).
An inking device is among the device components that are as a rule present in an inking system, but which are generally lacking from an external rack. A rudimentary inking device of this type can be mounted for the purpose of an external rack. Said device can also be loaded with a specific test ink. A test ink of this type can have similar color splitting characteristics, yet have different optical characteristics (“easier to measure”) from the actual ink.
In particular, the performance of the film of ink on a roller—in the rack or in the inking device—can also be determined by capacitive sensors when using extensively dielectric inks. In this case, it is easy to recognize that the thickness of the film of ink on the surface of the roller, at which measurements are taken, influences the capacitive measurement. However, even an uneven structure of a film of ink may play a role here.
The development of the film of ink on the roller can also be observed during the printing operation by using the inventive inking device. In this way, dynamic changes in the printing conditions can be recognized with respect to the printing operation. It is possible to react to these changes in the ongoing printing operation (e.g., by a different adjustment of the rollers or by changing the viscosity of the printed ink).
At this point, it should be mentioned once again that the change in the film of ink on the at least one ink-transferring cylinder can be carried out while the roller is rotating. The measurement can take place while the cylinders—for example the cylinders for which the relative position is optimized—are adjusted toward one another in the vicinity of the kiss print point of said cylinders and, if necessary, while a test run for determining an optimized printing position takes place. A displacement of the rollers away from one another to implement the measurement is generally unnecessary.
In the subsequent description of the subject matter, sensors are shown that are mounted in an operating or measuring position at an ink-transporting roller. Radiation sources are also often provided with respect to optical sensors—cameras. It has been demonstrated that, by means of measurements at the ink-transporting rollers, which measurements are possible using the indicated sensors, still other variables or phenomena, which are relevant to the printing process, can be measured or determined. These are subsequently explained with reference to the observation of a flexographic printing anilox roller:
Evaluation of the Negative Image
It has been surprisingly demonstrated that, when using suitable sensors, a clearly visible negative image of the print motif stands out on the anilox roller. Said negative image can be compared with the target image of the print image, which target image is often known from the preliminary printing step and which is often available in electronic format (e.g., pdf). In this way, errors can be recognized before they occur—likewise while generating spoilage.
Inking Monitoring
The performance of the inking of the anilox roller—which as a rule takes place using a doctor blade chamber—can be monitored prior to or during the printing process. This is very important as it can always occur that little or even no ink is on the roller, which naturally negatively influences the print image. Running rollers of all types when dry can, however, also cause combustion and explosions in printing machines, such that the recognition of dry rollers can be used for “explosion protection” (e.g., printing abort or warning signal).
Ghosting or Doctor Blade Streaks or Oscillations
Ink deposits, which can lead to so-called ghosting, or doctor blade streaks, which can come about due to a too strongly adjusted and/or vibrating doctor knife on the surface of the anilox roller, can be recognized using the sensors. As a remedy to ghosting, the anilox roller can be cleaned. During printing operation, more solvent can be fed. For the doctor blade streaks, a counter measure is to justify the doctor blade. Streaks on the anilox roller can come about due to oscillations in the inking device. Oscillations of this type often lead to regular thickness fluctuations of the film of ink on the roller.
Dynamic Measurement
As has already been mentioned above, changes in the film of ink on an ink-transporting roller can also be measured during the printing operation. An additional optimization of the roller position can result based on the measurements of the sensor system with respect to such changes. Measures of this type are advantageous, as changes in the parameters are set based on dynamic changes in the printing operation. Therefore, in general, additional measurements are made at increasing print speeds.
Registration or Pre-Registration
Based on significant points in the above-mentioned negative image of the print image on the anilox roller, or based on register marks provided for this purpose, which register marks are likewise displayed in the negative image, a registration or pre-registration of the printed-image carrying cylinder—the plate cylinder in flexography—can be carried out at the printed-image carrying cylinder by at least one additional inking device. For this purpose, the significant point or the mark on the surface of the anilox roller is recognized at this point in time, and the angle position of the anilox roller at this point in time is recorded, e.g., using a rotary position transducer. A significant point or a mark on the surface of the anilox roller of the additional inking device must then be brought into a suitable relative angle position. This circumstance would likewise be checked using an optical sensor and a rotary position transducer. This method would enable, for example, a spoilage-free pre-registration.
The previous methods can be advantageously combined with the method for setting the relative position of the at least two rollers involved in the printing process. Both types of methods have surprising advantages when they are implemented based on measurements at cylinders with uneven surfaces—such as anilox rollers, plate cylinders, or printing cylinders.
Lower signal-to-noise ratios result as a rule from smooth rollers.
Further embodiments of the invention arise from the description of the subject matter and the claims.
The individual figures show:
At this point, the doctor blade chamber 6 transfers ink to the surface of anilox roller 7. Said 7 further transports the ink by means of the rotation of the roller to the plate cylinder 8. The plate cylinder 8 supports the embossed cliché 11, which receives the ink from the surface of the anilox roller 7. Therefore, a zone forms on the surface of the anilox roller 7 in the contact region 10 between the cliché 11 of the plate cylinder 8 and the anilox roller 7, in which zone ink loss occurs. It is applicable to measure this ink loss in a printing machine 15, as is shown in
The cliché 11 transfers the ink to the printing material 9, which is transported on the circumferential surface of the impression cylinder 1. In the lower region of
A diagram largely identical to
As a rule, the line scan camera 17 is already equipped with its own radiation sources, which radiate radiation on the contact region 10.
A configuration of this type can also be seen in the sectional representation of the inking device 5 in
A further advantageous embodiment of the method can be depicted by means of
By this means the operating distance between a first group of cylinders 1, 7, 8 involved in the printing process is set, wherein the first group has a first number N of cylinders, and the first number is at least three,
wherein the operating distance between a second group of cylinders 7, 8 involved in the printing process is set based on measured values, which relate to the change in the film of ink on at least one of the two cylinders, wherein the second group is a subset of the first group, the second group has a second number M of cylinders, and the second number M is at least two,
and wherein the operating distance between a third group of cylinders 1, 8 involved in the printing process is set based on measured values, which are obtained in a different way from the measured values used for adjusting the operating distance between the cylinders of the second group from cylinders involved in the printing process, wherein the third group is a subset of the first group, the third group has a third number O of cylinders, and the third number O is at least two.
In the flexographic inking device 5 depicted in
The third group can be formed from the impression cylinder 9 and the plate cylinder 8. The adjustment of the optimized printing position for these two cylinders can take place in a different way and manner in order to reduce spoilage.
Another method of this type for setting an optimized printing position is disclosed in the as yet unpublished German patent application with the application number 10 2009 025 053. It is expressed in this citation that one cylinder rotatably involved in the printing process is contacted against another cylinder. A velocity gradient prevails between the surfaces of the cylinders, such that the drive of at least one of the two cylinders expends additional torque. Recourse to the teaching of the German patent application with the application number 10 2009 025 053 is explicitly reserved to round out the present teaching.
With regard to the teaching of the German patent application with the application number 10 2009 025 053, it is especially important how the drive of the printing machine should be equipped in order to perceive the change in torque. In addition, the way and manner, in which the cylinders in the German patent application with the application number 10 2009 025 053 are contacted against one another is of great importance. Also, the evaluation of the measured values and the actual optimizing of the printing position can be included for rounding out the method presented in the present document.
The teaching of the German patent application with the application number 10 2009 025 053 permits the adjustment of the printing position—among others, for impression cylinder 9 and plate cylinder 8—at extremely low printing speeds or even at the idle state of the impression cylinder 9. Thus printing also can take place with little spoilage or with none due to the combination of these methods.
The camera depicted in
It has been shown that cameras of this type are also fully sufficient for certain application cases. Sensors, such as reflection sensors and/or light sensors, which already find use in series printing machines as register sensors, can be considered as cameras with small fields of view (magnitude in the square millimeter range). Said sensors are equipped with optical fibers (as a rule fiberglass-based), which conduct light to the observation region as well as derive the light reflected by the roller surface, which light serves for measurement (as a rule, after is collected by a lens or something similar). Thanks to the optical fiber, the radiation source as well as the analysis unit are located in a safe mounting position at a distance from the measurement point. The sensors listed should be acquired as seamlessly integrated components (among others, mechanically resilient and relatively insensitive to chemical influences). It is also possible, thanks to the optical fibers, to adjust the positions of the light-emitting and light-remitting components (transmitter and receiver) as well as the roller surface, such that a large part of the remitted light falls back on the receiver and the measurement is carried out (as a rule using photodiodes). The generation of the light is realized as a rule using LEDs. Often, light is hereby generated that is calibrated in color with the ink of the roller to be tested. This measure is helpful with regard to all radiation sources in conjunction with the teaching introduced here.
Already in the previous figures, the depiction of an external rack is foregone, as it must have the same mechanical functional components as the inking devices and/or printing machines diagrammed. The depiction of control devices, cables, and interfaces is also foregone. In spite of that, reference is explicitly made to the fact that the methods portrayed can be carried out by computer implementation. Often, the control device of the printing machine and/or the control device of an external rack are equipped with corresponding software and hardware components. In the presence of an external rack, the operation can also be divided between the appropriate control devices of the rack and the printing machine.
In
It is clear from
The embodiment shown in
Achieving the optimized operating distance 38 can be verified by measurements, which, however, may often not be necessary.
In
In
In
As already shown in
An embodiment is shown in
In relation to
The progressions of graphs 45 shown in the figures can appear in sections of the area or in the entire area. Therefore, it is possible to observe the change in the layer of ink in sections of the contact surface 10 or in the entire contact surface 10 using the methods depicted.
While the image area of
The light 50 remitted by the anilox roller 7 is more strongly scattered in
Exactly in view of
A change of the surface of this type can, for example, consist in a “de-smoothing” of the same—thus in an increase in the “roughness” thereof—thus actual unevenness. Already with regard to a result of this type, a greater scattering of the remitted radiation occurs, such that a first contact between rollers 1, 7, 8, involved in the printing process can be measured.
In addition, a first contact of this type between the rollers can also lead to the fact that ink is displaced from the surface of the roller into cells 30, intermediate spaces between embossed sections of the print image, or into other lower-lying regions of the roller surface without the occurrence of an ink transfer to another cylinder—in general called color splitting. In the last-described case, the reflection behavior of the roller surface can also significantly change. Thus, the ink disappears from the high-lying regions of the roller surface, such that these are no longer covered by a smooth ink layer. The as a rule irregularly embossed elements of the roller surface (often separators between the cells 30, with regard to anilox rollers, pressure active regions with regard to plate cylinders 8) prevent a uniform direct reflection and thus contribute to the generation of more diffuse or non-directionally reflected light with regard to the reflected radiation 50.
In addition to ink removal and the change of the surface structure, naturally an addition of ink resulting from a contact between rollers involved in the printing process can be measured. This can, for example, be the case when the ink addition on a plate cylinder 8 is measured against the already inked anilox roller. For the qualitative change—for example, the measured increase of intensity I of the remitted light 50 as a consequence of the adjustment—then that stated in regard to
Using the methods depicted, it is therefore possible, among others, to:
The observation can take place at the rotating roller. In this case, the generation of spoilage can be avoided. The completeness and/or smoothness of the ink transfer can be checked. It is advantageous to implement the methods mentioned, and those subsequent, using devices that are installed—for example by programming a control device—for the implementation of said methods.
The measurement of the change in the film of ink can be taken while the rollers are still being adjusted toward each other.
This takes place at a rotating anilox roller 7, such that the camera 24 records a reference curve R (
In
This loss of ink in the contact region 10 leads to a significant change of the measured value in comparison to the reference curve R measured prior to the adjustment, which curve is depicted in
It is advantageous to end further adjustment of the cylinders 7, 8 (optimized setting of the relative roller position achieved), when the difference between the test run values TM and the reference values R at an angle position φ of the roller (can be recorded using a rotary position transducer) exceed a certain value (e.g., tolerance values T1 or T2). In a case of this type, the curve TM extends beyond the dashed curves G1 or G2. Also, the progression of the difference between reference values R and test run values TM can underlie the setting of the relative roller positions. Example: The difference TM-R—respectively in a certain angle position φ1 is derived according to φ.
If the derivation exceeds a certain derivation threshold value K, then the optimized roller position is reached:
d[TM(φ1)−R(φ1)]/dφ>K
In
It is often advantageous, if the sensors 17, 19, 24 depicted in the figures are pivoted away out of the region of the inking device after scanning the roller. In this case, the sensitive sensors are no longer fouled during the further printing operation. In the pivoted away position, cleaning can take place, which can be implemented for example by a cleaning device provided for this purpose. In this position, a recalibration of the sensors can also be implemented. During changing of ink in the inking device, the spectral sensitivity range of the sensors can be adjusted by filters and/or by loading the semiconductor diodes with a counter voltage.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10162344.5 | May 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/057417 | 5/9/2011 | WO | 00 | 1/22/2013 |
