Method for controlling the operation of a printing press and a flexographic printing press for implementing said method

Abstract

The present invention relates to a method for controlling the operation of a printing press and a flexographic printing press for implementing said method, wherein the method comprises performing the following steps: a) capturing information from at least one image printed by said printing press; and b) comparing said information captured from said printed image with at least some digital-format information predetermined in prepress, or digital prepress information, including at least one part of the image to be printed. The method comprises adjusting the pressure and/or register setting of one or more printing units of the printing press, using at least the result of the comparison in said step b). The press is designed in order to implement the method.

1 . A method for controlling operation of a printing press, integrating several printing units selected from the group consisting of a flexographic printing press, an offset printing press, and a rotogravure printing press, said method comprising performing the following steps:
 a) capturing information from at least one image printed by said printing press; and   b) making a comparison of said information captured from said printed image with at least some digital-format information predetermined in prepress or digital prepress information, including at least one part of the image to be printed,   c) adjusting a setting of at least one printing unit of said printing press using based upon at least a result of said comparison in said step b) the adjusted setting being selected from the group consisting of a pressure setting, a register setting, a color setting and a combination thereof;   d) detecting different colors existing in the prepress digital file;   e) assigning each color of the digital prepress information with each color of a corresponding printing unit of the printing press;   f) assigning colors to the captured printed images or captured parts of the printed images to be compared, and each captured printed image of each color being associated with each printing unit of the printing press;   g) determining a relative position of a side and a longitudinal register for each color of the images or parts of the images to be compared with one another;   said digital prepress information comprising a plurality of digital files, or one digital file subdivided into a plurality of subdivisions, each of said plurality of digital files or subdivisions corresponding to a color of a final print, or to a different motif to be printed in a respective printing unit of the printing press with a certain color in the plurality of digital files or subdivisions.   
     
     
         2 . The method according to  claim 1 , wherein said digital prepress information includes non-printable digital information that is complementary to the information of the image printed; and controlling performance of said comparison in step b) with said non-printable digital information. 
     
     
         3 . The method according to  claim 1 , wherein said information capture of said step a) is performed in line with a printing process. 
     
     
         4 . The method according to  claim 1 , further comprising performing said information capture of step a) with a camera selected from the group consisting of a matrix camera, a RGB camera, an LCCD line scan camera in combination with a spectrophotometer. 
     
     
         5 . The method according to  claim 1 , wherein said digital prepress information comprises at least one file in a digital format selected from the group consisting of PDF files and TIFF files. 
     
     
         6 . The method according to  claim 1 , wherein said assigning of each color of the digital prepress information with each color of a corresponding printing unit of the printing press is performed automatically. 
     
     
         7 . The method according to  claim 2 , wherein said non-printable digital information includes, in digital files reference elements, text labels or inserted graphical references that facilitate assigning each color of the digital prepress information with each color provided by a corresponding printing unit of the printing press, and where said labels also provide information about the relative position of the side and the longitudinal register for each color of said printing units of the printing press. 
     
     
         8 . The method according to  claim 1 , wherein said step a) comprises sequential printing of different printing units, and said sequential printing is performed independently or in conjunction with different combinations of anilox and plate cylinder pressure settings. 
     
     
         9 . The method according to  claim 6 , wherein the automatic assignment of each color of the digital prepress information with the colors existing in each prining unit of the press is performed by means of a sequence of side or longitudinal register movements. 
     
     
         10 . The method according to  claim 1 , wherein said information captured from said printed image in step b) comprises a register micro-mark as in plates for assembly in an assembly machine, and wherein once a position of the register micro-mark is located, then the printing unit to which each micro-mark corresponds is determined, and once correspondence is determined all the micro-marks are moved close to one another into a position where all the micro-marks overlap, the side and the longitudinal register setting of the image to be printed being thus adjusted. 
     
     
         11 . The method according to  claim 10 , wherein the adjusting of the setting is performed on the press with all the groups printing at the same time on in an alternating manner with different printing units always taking a color as a reference mark with respect to other colors. 
     
     
         12 . The method according to  claim 1 , wherein said comparison in step b) includes detecting a different color than what is expected, because of errors in a barcode or other codes, between the expected code and the printed code. 
     
     
         13 . The method according to  claim 4 , further comprising downloading, from the prepress information, specific labels that indicate positions of zones where spectrophotometric readings are to be performed, said specific labels incorporating some additional associated information where colorimetric format value to be achieved in the final print is included. 
     
     
         14 . The method according to claim  4 , further comprising reading the printed image with the spectrophotometer, filtering a colorimetric result, and comparing the filtered colorimetric result with a desired color. 
     
     
         15 . The method according to  claim 1 , wherein the printing press regulated to implement the method is the flexographic printing press that comprises:
 a rotatable counter-pressure control cylinder and at least one printing cylinder and an inking cylinder that is rotatable and linearly movable;   drive means for carrying out said rotations;   drive means for carrying out said linear movements;   means for capturing information from at least one image printed by said printing press; and   a control unit in connection with said means for capturing information that has a capacity to store digital prepress information,   wherein said control unit integrates a comparison unit for comparing a printed image with the digital press information.   
     
     
         16 . The method according to  claim 3 , further comprising performing said information capture of step a) with a camera selected from the group consisting of a matrix camera, a RGB camera, an LCCD line scan camera in combination with a spectrophotometer. 
     
     
         17 . The method according to  claim 2 , wherein said digital prepress information comprises at least one file in a digital format selected from the group consisting of PDF files and TIFF files. 
     
     
         18 . The method according to  claim 16 , further comprising downloading, from the digital prepress information, specific labels that indicate positions of zones where spectrophotometric readings are to be performed, said labels incorporating some additional associated information where colorimetric format value to be achieved in the final print is included. 
     
     
         19 . The method according to  claim 16 , further comprising reading the printed image by means of a spectrophotometer in line with the press, applying a filter to a colorimetric result to simulate an intermediate laminated material that is used for comparing with a desired final color. 
     
     
         20 - 28 . (canceled)