Abstract:
A method for printing includes a plurality of process steps. According to an additional step, relevant data are stored in a central relational database. Both a printing press and a data processing unit processing prepress data are interconnected.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Field of the Invention  
           [0002]    The invention relates to a method for controlling a printing process, in particular an offset printing process, wherein prepress data are generated and are then supplied to a data processing unit, in particular a Raster Image Processor (RIP), and then to a printing press.  
           [0003]    Today, the printing process usually begins at a prepress stage, where an original image to be printed is created. In several following process steps, that original image is used to produce a required number of printing plates. According to conventional printing processes, that means that color separations are created, which are then used to produce a printing form. The prepared printing forms are then positioned in the printing press and used for printing. The printing press is connected to a control unit for monitoring the printing press and for inputting data relating to a print job.  
           [0004]    If the printing forms are produced digitally, the prepress data are supplied to a data processing unit known as a Raster Image Processor, which converts the data into a bitmap. The bitmap is then used to image the printing plates either directly in the printing press or in a separate imaging apparatus. If necessary, the plates containing the image to be printed are then positioned in the printing press and the printing operation, which is controlled through a printing press control unit, is started.  
           [0005]    However, a disadvantage of the system described above is that a manual combination of the data present in the RIP and the data present in the printing press, in particular the data relating to the print job, presents considerable difficulties. Such a combination of data even becomes impossible if the print job is formed of several printing operations, since the data of the individual printing operations cannot be combined. In such a case, an automatic reevaluation of the print job becomes impossible.  
         SUMMARY OF THE INVENTION  
         [0006]    It is accordingly an object of the invention to provide a method for controlling a printing process, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known methods of this general type, which provides better control over a print job to be executed and which offers an opportunity of re-evaluating the print job.  
           [0007]    With the foregoing and other objects in view there is provided, in accordance with the invention, a method for controlling a printing process, in particular an offset printing process. The method comprises transferring data to a data processing unit, in particular a Raster Image Processor, storing the data in a database for relational linking among the data received by the database, and subsequently transferring the data to a printing press. The data transfer step is carried out either directly from the database to the printing press or from the database, through the data processing unit, to the printing press.  
           [0008]    In accordance with a concomitant mode of the invention, the method further comprises supplying the database with data relating to a print job by a print job unit.  
           [0009]    According to the invention, a database is provided which relationally combines the received data in such a way that the prepress data and the data that has been input into the printing press can be combined so that a universal re-evaluation of the data becomes possible. Therefore, an automatic re-calculation process may be initiated on the basis of the data stored in the database.  
           [0010]    Other features which are considered as characteristic for the invention are set forth in the appended claims.  
           [0011]    Although the invention is illustrated and described herein as embodied in a method for controlling a printing process, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
       
    
    
       [0012]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a flow chart of a first method according to the invention; and  
         [0014]    [0014]FIG. 2 is a flow chart of a second method according to the invention including a job allocation. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a prepress stage  10  where image data required for a printing process are generated. In most cases, the prepress data are prepared in the form of Postscript or PDF files. The Postscript or PDF file is supplied to a RIP  12 , which converts the Postscript or PDF data into what is known as a bitmap for each of the required color separations. If a direct imaging press is used, the bitmap files may be supplied to the press to be used for imaging the plate in the press. According to the invention, an additional unit  14  is provided before the bitmap files are transmitted to the printing press. A substantial component or the only component of the additional unit  14  is a database  15 , in which data received from the RIP  12  are stored. The database is able to create a relational link between all of the incoming data. The data coming from the RIP may, for example, contain an ID number, a document name, a bitmap name, a processing time for the RIP or other information relevant for the RIP. The data coming from the RIP  12  are preferably supplied to the additional unit  14  through an RIP event processing unit  16 . The RIP event processing unit  16  processes the data coming from the RIP  12  in such a way that only the data which will later be required for the printing press are stored. In this respect, the RIP event processing unit  16  acts as a data filtering logic for filtering certain data between the RIP  12  and the database  15  according to a definitely predetermined or variable logic. What is forwarded is, in particular, the name of the document or information concerning the RIP processing data. Data which are redundant or irrelevant for the printing press operation to be carried out later will not be forwarded. Among the data not to be forwarded is what is known as intermediate status information, such as the size of the generated bitmap in pixels.  
         [0016]    There are several options for extracting the data which are relevant for the printing process and are consequently to be stored in the database of the additional unit  14 . A first option is that the RIP event processing unit  16  continuously receives information on the current state of the RIP. Upon an end signal indicating the end of the RIP processing operation, the RIP event processing unit  16  receives an information signal indicating that the job has been completed. Afterwards, all operational data are stored in the database  15 , which may create a relational link between the data. A second option is that the operational data are continuously held in a file in the RIP event processing unit  16 , in particular in what is known as a “logfile”. This file is continuously analyzed to provide an analysis of the relevant information according to the logic stored in the RIP event processing device  16  and to store the relevant information in the database  15 .  
         [0017]    The data stored in the database  15  may then be fed to a printing press, in particular to a direct imaging printing press. The data may be transferred to the press along a direct path A or along an indirect path B indicated in dashed lines, i.e. through the RIP.  
         [0018]    A printing press  18  may also include additional units such as a device  20  for regulating ink keys, an imaging device  24  and a device  22  for controlling the press. The latter may also include a device for obtaining operational data.  
         [0019]    Further operational data, for example concerning the actual number of correctly printed sheets, the number of spoiled sheets, the required set-up time, the duration of the print run etc., are obtained during the print run. These operational data may be obtained automatically, may be provided by an external source or may be input by a press operator. The operational data are then fed to a print event processing unit  26 , where they are analyzed and processed, if necessary, and then forwarded to the database  15  of the additional unit  14 .  
         [0020]    The data in total, i.e. both the operational data and the RIP data contained in the relational database, may be accessed through an external module  28 , by providing the database  15  according to the invention. This provides a number of evaluation options as well as the option to introduce external information into the database  15 .  
         [0021]    Although the additional unit  14  and the database  15  are shown as individual components in FIG. 1, it is to be understood that the two components may of course be combined to form only one individual component being formed of the additional unit  14  and the database  15 .  
         [0022]    In the embodiment of the invention shown in FIG. 2, a further step is added to the method according to the invention. As soon as the respective data have been converted into bitmaps in the RIP, the bitmaps are stored in a specific index in the file  15 . This index is continuously monitored by an input and print job unit  30 . As soon as a new bitmap has been stored in the file  15 , a corresponding signal is forwarded to the print job unit  30  and displayed on a suitable display device such as a monitor. Then the press operator may be asked to input the relevant job data relating to this bitmap through a suitable program. It is to be understood that these data may be newly input, or a suitable job may be selected from a list of already existing jobs. After this step has been completed, the job is confirmed and the necessary links are entered in the relational database  15 . This ensures an automatic allocation of all files to this job. In addition, the data relating to the job, such as the number of products to be produced, recto/verso printing, printing stock etc., are written in a file which belongs to the data set and which may be read at the printing press.  
         [0023]    Thus, there is a bi-directional connection E between the relational database  15  and the print job unit  30 .  
         [0024]    As described in the context of FIG. 1, the relevant contents of the relational database  15  may be forwarded to the printing press along the direct path A or along the indirect path B indicated by the dashed line, i.e., for example, through the RIP  12 .