Process and apparatus for controlling the inking process in a printing machine

A printing plant, comprising:

• a printing machine;
• an acquisition apparatus for photoelectrically measuring a printed sheet;
• and
• a control apparatus for processing measured data produced by the acquisition apparatus and for automatically producing control signals for ink control elements of the printing machine in response to said measured data, wherein the acquisition apparatus is equipped for generating spectral photometric measurement data of the printed sheet at a plurality of different wavelengths as colorimetric data, and the control apparatus converts spectral photometric data produced by the acquisition apparatus into spectral reflections and color position coordinates for producing the set signals based on colorimetric deviations.

Measuring apparatus for producing color data for a printing machine comprising:

• an acquisition apparatus for zonal photoelectric measuring of a printed sheet and for generating measured data;
• and
• a processing apparatus for processing the measured data and generating control data from said measured data, said control data representing color deviations of print sheet areas scanned by the acquisition apparatus from corresponding set values, said acquisition apparatus further including:
• a spectrometer module for measuring the printed sheet at a plurality of different wavelengths by spectral photometrical means, and for converting measured data produced by the acquisition apparatus to spectral reflections and color position coordinates, said processing apparatus comparing the color position coordinates with set color position coordinates, determining a color deviation between said color position coordinates and said set color position coordinates and automatically generating the control data for the printing machine from said color deviations.

A process for controlling the inking process in a printing machine comprising the steps of:

• (a) establishing desired reference color coordinates in a standardized color coordinate system wherein each coordinate value uniquely defines a particular color;
• (b) measuring color spectral characteristics of a test area printed by the printing machine to establish measured color coordinates for said test area in said color coordinate system;
• (c) determining a color deviation of said test area on the basis of the reference color coordinates and said measured color coordinates;
• and
• (d) automatically calculating inking control data on the basis of said color deviation for controlling the inking process of the printing machine.

An apparatus for producing inking control signals for a printing machine comprising:

• means for establishing desired reference color coordinates in a standardized color coordinate system wherein each coordinate value uniquely defines a particular color;
• means for measuring color spectral characteristics of a printed test area to establish measured color coordinates for said test area in said color coordinate system;
• means for determining a color deviation of said test area in response to said reference color coordinates and said measured color coordinates;
• and
• means for automatically calculating inking control signals as a function of said color deviation for providing inking control signals.