Printing – Inkers – Roller
Reexamination Certificate
2002-10-24
2004-01-20
Hirshfield, Andrew H. (Department: 2854)
Printing
Inkers
Roller
C101S364000, C101S365000, C101S350400
Reexamination Certificate
active
06679169
ABSTRACT:
Priority to German Patent Application No. 101 52 158.8, filed Oct. 25, 2001 and hereby incorporated by reference herein, is claimed.
BACKGROUND INFORMATION
The present invention relates to a method for controlling the ink feed of a machine which processes printing substrates and features at least one inking unit and a computer and to a device which is suitable for carrying out the method.
In the production of printed matter, it is important, above all, that the products leaving a printing press correspond as far as possible to an original copy provided by a customer. This results in complex adjustment procedures, in particular, in the case of sheet-fed printing presses, because, compared to web-fed rotary printing presses, the jobs change much more frequently here. The settings of the printing press have to be changed for each job change, which is very time-consuming. In addition to changing the printing plates on the individual printing units of the printing press, these settings also include those the for the inking unit of each printing unit, especially when the inks in the inking units have to be changed. In this context, the adjustment of the inking unit and thereby of the ink feed depends on many parameters, including the printing speed of the printing press as well as environmental factors such as air humidity and temperature in addition to properties of the printing substrates and the printing inks.
To avoid unnecessary spoilage, state-of-the-art printing presses are calibrated to specific printing inks and specific paper so that spoilage can be reduced using these specific consumables. However, this results in only very limited success because the printing ink properties are subject to relatively large variations, resulting in considerable spoilage in spite of the calibration. For this reason, many printing presses operate with measuring systems which measure the finished, printed sheets or parts of the sheets opto-electronically, mostly on the basis of spectra, the measurements being subsequently compared to an original copy which is measured in the same manner. The differences between the original copy and the printed product determined in this comparison are then used to appropriately adjust the ink feed of the inking units until, in accordance with the requirements, the original copy and the printed product no longer differ. In this case, an OK sheet exists and the print run can start.
A method of that kind is known from European Patent Application No. EP 0 585 740 A1, where screen tints of individual printing colors or of the whole print are photoelectrically scanned and the reflectance values obtained in the process are converted to a characteristic curve. The characteristic curve determined in this manner is adjusted to a predetermined reference characteristic curve by influencing the printing process accordingly. The adjustment of the actual characteristic curve to the predetermined reference characteristic curve is accomplished in that a parameter of the actual characteristic curve is varied and in that, using a performance index, that actual characteristic curve of the resulting actual characteristic curves is selected which leads to a particularly good match with the reference characteristic curve. Hence, this is a closed-loop control circuit which measures reflectance values of a printed product and subsequently changes the characteristic curves stored in the printing press accordingly. However, a closed-loop control circuit of that kind can only react because consumption parameters such as ink and paper cannot be taken into account by the control, as a result of which considerable spoilage is produced until the OK sheet is achieved.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and a device for carrying out the method which are capable, in particular, of taking into account the properties of consumables and of adapting the ink feed according to the properties already before the start of printing.
The present invention provided a method for controlling the ink feed in a machine which processes printing substrates (
12
) and features at least one inking unit, wherein a computer knows at least the physical properties of printing ink and/or printing substrates (
12
) as data; the stored data is read into an ink control model which is stored in the computer; and the optimum settings with regard to the ink feed are made on the basis of this ink control model before the start of printing or during the printing process. A device for performing the method is also provided.
The method according to the present invention can preferably be implemented on a printing press having a control computer which is able to exchange signals for controlling one or more inking units. However, it is also possible that a separate computer exists which calculates the optimum settings using the ink control model and that the data is transmitted from the computer to a printing press or to manually entered there. The ink control model can also be implemented on a computer which is provided in the printing press in addition to the control computer. Besides, the data can also be calculated in the preliminary stages. The place of calculation does not matter, it is only crucial that the physical properties of the consumables be available to the ink control model on a computer and that the results be subsequently used to control a printing press.
The control computer or separate computer has stored therein the ink control model in which the physical properties of the consumables such as printing ink and printing substrate or paper, as well as ambient parameters such as air humidity and temperature are mathematically correlated. Because of this, the ink control model stored in the computer is able to control the ink feed of the inking unit on the basis of the physical properties of the printing ink or printing substrates and of the ambient parameters in such a manner that as little spoilage as possible is produced and the set-up time during job change-over can be minimized. To this end, the physical properties of the consumables must be known, whether they are provided by the consumable supplier or whether the consumables are measured accordingly and thus the physical properties are known on the basis of the measurements. Since the different properties of the consumables and the ambient parameters are known and can be introduced into the control of the printing press, the ink control functions of the printing press can be optimally adapted, and much less deviation from the expected printing result is to be expected than if the printed copies were measured only during printing, as in the related art, and possibly considerable deviations from the original copies would have to be found. In the related art, it can take a very long time until the quality of the printed products has reached a satisfactory degree, especially when the physical properties of the printing inks or printing substrates strongly deviate from the usual standard. Using the method according to the present invention, these problems can be prevented to the greatest possible extent through the a priori knowledge of the properties of the printing substrates and printing inks and through the ink control model.
In a first embodiment of the present invention, provision is made for the stored inks to be used by the ink control model for optimum ink presetting. Optimum ink presetting is an important aspect for achieving good printing results in a rapid manner and with as little spoilage as possible. Using the ink control model, the ink presetting can be optimally adjusted in such a manner that no complex readjustments are required during the printing process, as in the related art.
Moreover, provision is made for the stored data to be used by the ink control model for speed compensation in case of a change in printing speed. For each printing speed, there is a printing unit setting that leads to optimum printing results. As soon as the printing speed is changed, the ink feed has to be change
Anweiler Werner
Gateaud Caroline
Hauck Axel
Mayer Martin
Chau Mina
Davidson Davidson & Kappel LLC
Heidelberger Druckmaschinen AG
Hirshfield Andrew H.
LandOfFree
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