EP0228347B1 — Process for controlling the application of colour…

Claim 1

Independent Claim 126 words

Process for controlling the application of ink by a printing machine, wherein a printed sheet printed by the machine is measured photoelectrically in a plurality of test areas, measured data obtained in this manner are processed into control data in combination with set values, and the inking process of the printing machine is controlled automatically using said control data, characterised in that the test areas are measured colorimetrically, and their colour positions relative to a selected colour coordinate system are determined, that for the test areas measured the colour deviations between associated set colour positions related to the same colour coordinate system are determined, and that the formation of control data and control of the inking process take place on the basis of said colour deviations.

Claim 2

Dependent Claim 126 words

Process for controlling the application of ink by a printing machine, wherein a printed sheet printed by the machine is measured photoelectrically in a plurality of test areas, measured data obtained in this manner are processed into control data in combination with set values, and the inking process of the printing machine is controlled automatically using said control data, characterised in that the test areas are measured colorimetrically, and their colour positions relative to a selected colour coordinate system are determined, that for the test areas measured the colour deviations between associated set colour positions related to the same colour coordinate system are determined, and that the formation of control data and control of the inking process take place on the basis of said colour deviations.

Claim 3

Dependent Claim 25 words

Process according to claim 1, characterised in that the inking process is controlled so as to minimise the individual colour deviations of given test areas.

Claim 4

Dependent Claim 27 words

Process according to claim 1, characterised in that the inking process is controlled so as to minimise a total colour deviation resulting from the individual colour deviations.

Claim 5

Dependent Claim 29 words

Process according to one of claims 1 - 3, characterised in that the individual colour deviations are considered with various degrees of significance when calculating the total colour deviation.

Claim 6

Dependent Claim 34 words

Process according to one of claims 1 - 4, characterised in that the control data are calculated by printing zones from the colour deviations of the test areas belonging to the printing zones involved.

Claim 7

Dependent Claim 27 words

Process according to one of claims 1 - 5, characterised in that the zonal control data are calculated from the colour deviations of zone- overlapping test areas.

Claim 8

Dependent Claim 28 words

Process according to one of claims 1 - 6, characterised in that the application of significance to the individual colour deviations differs over the print width by zones.

Claim 9

Dependent Claim 38 words

Process according to one of claims 1 - 7, characterised in that in addition the control data are calculated directly by spectral photometric measurement at a plurality of different wave-lengths from the spectral reflections determined in so doing.

Claim 10

Dependent Claim 54 words

Process according to one of claims 1 - 8, characterised in that the control data are calculated from the standard colour values obtained by digital filtering (weighting) of spectral reflections with CIE-standard spectral curves and their conversion into a selected colour coordinate system suitable for colour deviation evaluation, in particular the CIELAB- or CIELUV-system.

Claim 11

Dependent Claim 37 words

Process according to one of claims 1 - 8, characterised in that in addition the control data are calculated from the colour densities obtained by digital filtering (weighting) of the spectral reflections with selected colour filter curves.

Claim 12

Dependent Claim 58 words

Process according to one of claims 1 - 10, characterised in that the setting-up of the printing machine and matching the print with the master take place under colour deviation control and subsequently the printing run is carried out based on colour densities in a manner such that said colour densities are maintained essentially at constant set values.

Claim 13

Dependent Claim 35 words

Process according to one of claims 1 - 11, characterised in that simultaneously printed colour measuring fields are used as test areas and in particular multi-colour half-tone fields are also provided as colour measuring fields.

Claim 14

Dependent Claim 55 words

Process according to claim 11, characterised in that the colour-density-controlled printing run stabilisation is superposed on the colour deviation-controlled regulation of the inking process with the object that a new colour deviation-controlled correction is made with simultaneous updating of the set values for the colour densities when the colorimetric colour deviations exceed a limit value.

Claim 15

Dependent Claim 50 words

Process according to claim 11, characterised in that the total colour deviation or deviations is or are also formed and monitored during the printing run and a warning is issued or a new colour deviation-controlled correction of the printing machine is carried out when the colour deviation tolerance is exceeded.

Claim 16

Dependent Claim 26 words

Process according to claim 12, characterised in that colour measuring fields are used having colour tones taken from selected critical image areas of the printed sheet.

Claim 17

Dependent Claim 112 words

A printing plant for carrying out the process according to one of claims 1 - 15, comprising a printing machine, an acquisition apparatus for photoelectric measurement of a printed sheet, and a control apparatus for processing the measured data produced by the acquisition apparatus and for producing set signals for the inking process elements of the printing machine from said measured data, characterised in that the control apparatus is equipped to convert the measured data produced by the acquisition apparatus into colour position coordinates and to determine colour deviations from the calculated colour position coordinates by comparison with set colour position coordinates and produce the set signals based on said colour deviations.

Claim 18

Dependent Claim 37 words

Printing plant according to claim 16, characterised in that the acquisition apparatus is equipped for spectral photometric measurement of the printed sheet at a plurality of different wave-lengths and the production of corresponding spectral photometric measured data.

Claim 19

Dependent Claim 56 words

Printing plant according to claim 17, characterised in that the control apparatus is also equipped to convert the spectral photometric measured data produced by the acquisition apparatus to colour densities and to produce the set signals for the inking process elements also from results of a comparison of said colour densities with corresponding set colour densities.

Claim 20

Dependent Claim 25 words

Printing plant according to claims 16 - 18, characterised in that the measured data and values determined therefrom are displayed and /or otherwise given out.

Claim 21

Dependent Claim 104 words

Measuring apparatus for producing control data for a printing machine comprising an acquisition apparatus for zonal photoelectric measurement of a printed sheet and a processing apparatus for processing the direct photoelectric measured data and producing therefrom the control data representing the deviation of colour of the scanned areas of the printed sheet from corresponding set values, characterised in that the processing apparatus is equipped to convert the measured data produced by the acquisition apparatus into colour position coordinates, compare them with set colour position coordinates, determine the colour deviations for them and produce the control data for the printing machine from said colour deviations.

Claim 22

Dependent Claim 104 words

Measuring apparatus for producing control data for a printing machine comprising an acquisition apparatus for zonal photoelectric measurement of a printed sheet and a processing apparatus for processing the direct photoelectric measured data and producing therefrom the control data representing the deviation of colour of the scanned areas of the printed sheet from corresponding set values, characterised in that the processing apparatus is equipped to convert the measured data produced by the acquisition apparatus into colour position coordinates, compare them with set colour position coordinates, determine the colour deviations for them and produce the control data for the printing machine from said colour deviations.

Claim 23

Dependent Claim 37 words

Measuring apparatus according to claim 20, characterised in that the acquisition apparatus is equipped for spectral photometric measurement of the printed sheet at a plurality of different wave-lengths and for production of corresponding spectral photometric measured data.

Claim 24

Dependent Claim 51 words

Measuring apparatus according to claim 21, characterised in that the processing apparatus is additionally equipped to convert the spectral photometric measured data produced by the acquisition apparatus into colour densities, compare them with set colour densities, and produce the control data for the printing machine from the result of said comparison.

Claim 25

Dependent Claim 31 words

Measuring apparatus according to one of claims 20 - 22, characterised in that it is equipped to perform the process steps according to one or more of claims 1 - 15.

Claim 26

Dependent Claim 42 words

Measuring apparatus according to claim 20, characterised in that as well as photoelectric colour measurement with a controllably movable measurement head a freely movable measurement head is connected, with which colour measurement may be effected at any location and on any samples.

Claim 27

Dependent Claim 26 words

Measuring apparatus according to claim 24, characterised in that the freely movable measurement head acts on the same spectrometer module as the controllably movable measuring head.

Claim 28

Dependent Claim 53 words

Set of colour measuring strips for performing the process according to claim 1, characterised in that it comprises a plurality of colour measuring strips having multi-colour measuring fields built up in different colour tones, said strips being chosen and mounted in keeping with the image-determining colour tones of the image to be printed.

Process for controlling the application of colours in a printing machine, printing device equipped therewith and measuring device for such a printing device

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