Improved Print Control Strip for Color Measurement on Printing Material, Measuring Method and Method of Metering Ink

Abstract

A print control strip to be applied to printing material during a multicolor printing process, includes multiple measuring fields associated with one ink zone on the printing material. The measuring fields, which are associated with one ink zone, include at least two gray measuring fields. A method of measuring fields in print control strips on printing material with a measuring device and a control unit connected thereto, and a method of controlling metering of ink in offset printing presses including at least one ink metering device in each printing unit and a control unit, are also provided.

1 . A print control strip to be applied during a multicolor printing operation to printing material having ink zones, the print control strip comprising:
 multiple measuring fields associated with an ink zone on the printing material;   said measuring fields associated with one ink zone including at least two gray measuring fields.   
   
   
       2 . The print control strip according to  claim 1 , wherein said measuring fields associated with one ink zone include three gray measuring fields. 
   
   
       3 . The print control strip according to  claim 2 , wherein said gray measuring fields represent a 25% continuous tone, 50% continuous tone, and 75% continuous tone formed of three basic process colors cyan, magenta and yellow. 
   
   
       4 . The print control strip according to  claim 1 , which further comprises at least one measuring field for spot colors. 
   
   
       5 . The print control strip according to  claim 1 , wherein said measuring fields are disposed in at least two parallel rows. 
   
   
       6 . The print control strip according to  claim 5 , wherein each measuring field in one row is present at least once in each other row. 
   
   
       7 . The print control strip according to  claim 5 , wherein said measuring fields are disposed in different orders in said rows. 
   
   
       8 . The print control strip according to  claim 5 , wherein said measuring fields are provided only once in said rows. 
   
   
       9 . A method of controlling metering of ink in offset printing presses having printing units, at least one ink metering device in each printing unit, and a control unit, the method comprising the following steps:
 measuring a measuring strip including a plurality of gray measuring fields within an ink zone on a printed product, with a color measuring device;   feeding measured gray values to the control unit for controlling the metering of the ink in the printing units; and   calculating nominal values for controlling the metering of the ink in the printing units with the control unit and transmitting the nominal values to the printing units.   
   
   
       10 . The method according to  claim 9 , which further comprises influencing an evaluation of the gray measuring fields with the control unit through an input device, prior to the step of measuring the gray measuring fields with the color measuring device. 
   
   
       11 . The method according to  claim 10 , which further comprises controlling the ink metering devices in the printing units of the printing press with the control unit in dependence on selected gray measuring fields. 
   
   
       12 . The method according to  claim 9 , which further comprises introducing the measured gray values as average values in the control of the metering of the ink in the printing units, for ink control by the control unit. 
   
   
       13 . A method of measuring fields in print control strips on printing material, the method comprising the following steps:
 providing the measuring fields in at least two rows in the print control strips;   providing each measuring field at least once in each row of the print control strips;   measuring the measuring fields with a measuring device to provide measured values; and   subjecting the measured values, during the measuring step, to a plausibility check in a control unit connected to the measuring device.   
   
   
       14 . The method according to  claim 13 , which further comprises, upon an occurrence of implausible measured values in one ink zone, using measured values of a neighboring ink zone in the control unit for controlling ink metering devices in printing units of a printing press.