GB2189743A

GB2189743A - Presetting zone inking controls

Info

Publication number: GB2189743A
Application number: GB08618048A
Authority: GB
Inventors: Gerd Eckelmann
Original assignee: Miller Johannisberg Druckmaschinen GmbH
Current assignee: Miller Johannisberg Druckmaschinen GmbH
Priority date: 1986-04-29
Filing date: 1986-07-24
Publication date: 1987-11-04
Also published as: IT1196603B; IT8648416A0; JPS62257849A; GB8618048D0; FR2597792A1; DD250295A5; FR2597792B1

Abstract

A method of presetting the zone ductor controls of a printing machine, wherein an image bearing surface (which may be an original document, or a transparency, or a printing plate, or a printed copy, or the like) is imaged onto a television camera tube, and the output from the tube is processed and normalised to produce zone ink data, characterised in that the television camera (4) has a halftone resolution, of at least 32 gradations and an individual calibrating characteristic line for each picture point, the image scanned is digitalised and fed into a microcomputer (7) for numerical calibration and for calculation of the presetting points of the zone adjustment screws and from there is passed to a picture screen (9), whilst the width and number of colour zones can be adjusted at will using the microcomputer (7) and the limits of the colour zones are displayed on the picture screen (9) by means of light or dark lines, and the halftones stored in the memory of the microcomputer are equalised using characteristic lines and totalled zone by zone. <IMAGE>

Description

SPECIFICATION Method of presetting the various zones of an inking device of a printing machine This invention relates to a method of presetting the various zones of inking devices of printing machines by optical scanning of an illuminated original, such as a printing plate, printing film or printed product, which, if transparent, is placed on a glass plate and light shone through, by means of a colour intensity measuring device in the form of a television camera, and by presetting the various zone adjustment screws of a colorimeter or other elements of the inking device which adjust the quantity of ink, this presetting being controlled buy a computer, in a picture evaluating system using the picture data stored.The original may be,forexample, a printing plate, a printing film or a finished printed product which has already been printed earlier.

Such presetting is desirable to ensure that the inking devices are set exactly right at the very start of printing or are set so that only very minor adjustments are required.

It is known, when optically scanning the illuminated original to be printed, to use a television camera with a picture halftone resolution of at least eight gradations per picture point, which is associated with computer control and a coordinate memory, whilst the area ofthe memory which defines the original in the coordinate memory can be preselected and the addresses of the memory values which are to be totalled in order to obtain the zone averages can be selected by the computer in the freed area ofthe coordinate memory in accordance with the number of zones present and the zone width and the memory values can be added together. In this apparatus the printed sheet of paper is measured, whilst different colour filters are successively swung in front of the camera.The quantity of ink actually printed is not determined by this procedure, since individual colours are partly concealed by successive printing inks.

There is thus a need for a generally improved method of presetting the various zones of the inking devices of printing machines by optical scanning which minimises or eliminates the disadvantages described hereinbefore.

According to the present invention there is provided a method of presetting the various zones of an inking device of a printing machine by optical scanning of an illuminated original, such as a printing plate, printing film or printed product, which, if transparent, is placed on a glass plate and light shone through, by means of a colour intensity measuring device in the form of a television camera, and by presetting, forthe various zones, adjustment screws of a colorimeter or other elements of the inking device which adjust the quantity of ink, with this presetting being controlled by a computer, in a picture evaluating system using the picture data stored, in which the television camera used has a picture halftone resolution of at least 32 gradations and an individual calibrating characteristic line for each picture point, the image scanned is digitalised and fed into a microcomputerfor numerical calibration and calculation of the presetting points for the zone adjustment screws and from there is passed to a picture screen, whilst the width (xz) ofthe colourzones and the number ofcolourzones can be adjusted at will using the microcomputer, and the limits of the colour zones are displayed on the picture screen by means of light or dark lines, and the halftones stored in the memory of the microcomputer can be equal wised by means of characteristic lines and totalled zone by zone. The characteristic lines are formed by means of calibrating patterns and stored in the memory.

The method according to the invention enables the person observing the picture screen to check the image which has actually been digitalised and correct the intensity of iilumination and also, if necessary, detect any dirt on the surface ofthe plate orfilm or other original and so remove it. Once again, the width of the colour zones and the number of such zones can be selected freely.

The total values of the individual zones are conveniently standardised (0 - 100%). To do this, a characteristic line is calculate using a reference grid.

In afurtherembodimentofthe invention the individual colourzonevalues are stored on a digital cassette which is adapted to the data format ofthe main ink device controls. Using a picture screen the userfeeds in the identity code of the colour to be printed from the original in question so that the remote control console can automatically selectthe right inking device to perform the presetting.

The method according to the invention hasthe advantage over optical methods using photoelectric cells and measurement of reflected lightthat, owing to the definition of the image, it is impossible for measurements to be falsified by non-planar originals. For each picture point, calibrated values can automatically be determined and stored in the memory, compensating not only the uneven light distribution butalsothe non-uniform ageing of the individual light sensors in the camera. These calibration values are stored in a non-transient manner.

By comparing the image shown on the picture screen with the original the measuring equipment can very easily be monitored. The apparatus used in the method according to the invention can be adapted to all widths and numbers of colour zones.

There is a simple error-toleranttransfer ofthe measured values to the control console ofthe printing machine.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figures 1 and2showdiagrammaticallyan apparatusforcarrying outthe method ofthe invention, Figure3 is a block circuit diagram of the entire apparatus of Figures 1 and 2, and Figure 4 is a plan view of a printing original for a colour for use with the apparatus of Figures 1 to 3.

Figure 2 shows an original for printing 1 which is placed on a glass platen 2. A plurality of lamps 3 are provided in orderto illuminate the original 1 as evenly as possible. In the case of a transparent original such as a film, light is shone through the original by a lighting apparatus 8. The light intensity ofthe lamps 3 or lighting apparatus 8 can conveniently be adjusted.The original for printing 1 is scanned by a television camera 4 with a picture halftone resolution of at least 32 gradations for each picture point. 5 is a device for detecting the image and storing the image generated by the television camera 4.6 is a disc store and 7 is a microcomputer which has a keyboard for programming. As shown in Figure 1,9 is a picture screen for displaying the original and showing measured data. 10 is a cassette recorder for storing and transmitting data to the remote control console (not shown) and 11 is a line printer. The microcomputer7 has a CPM standard operating system. Consequently the user can reprocess the data generated generated whenever he wishes and adapt them, for example, to the coupling procedure of different data processing equipment.

The block circuit diagram of Figure 3 shows the connections between the individual units. The television camera 4 serves to receive the image from the original which is to be printed and the apparatus 5 serves to detect and store the digitalised image in at least 32 picture halftones. The picture screen 9 serves to display the image seen bythetelevision camera 4and has markingsforthe individual zones evaluated. The microcomputer 7 serves to evaluate the image and for data inputandoutputandthe disc memory 6 is for non-transient recording of instructions, measurements and calibration data.

The cassette recorder 10 serves as an intermediate storeforthe measurements and is used to transfer them to the control of the printing machine, particularly the ink device controls. The line printer 11 prints out measurements for recordal or for presetting printing machines without a cassette recorder 10. 12 is the computer bus, i.e. the connecting system for the individual functional units. 3 is the illuminating device in the form of the lamps in Figure 2 orthe lighting apparatus 8.

Figure 4 showsthatthe original for printing 1 has a calibration mark 13, an area with 100% covering for presetting the camera intensification in orderto achieve the best possible results. 14 denotes a scanning dot or picture point ofthe television camera 4, measuring about 2 mm x 2 mm.

The following measurements are also shown on this drawing: ypsize of the printing plate inthecircumferential direction ofthe cylinder xp size ofthe printing plate in the axial direction of the cylinder yz size ofthe zone in the circumferential direction ofthe cylinder Xz size ofthe zone in the axial direction of the cylinder yA position of the zones in the circumferential direction ofthecylinder xA position ofthe zones in the axial direction ofthe cylinder n = maximum numberofzones All these values can be fed into the microcomputer 7 using a keyboard.

Claims

1. Method of presetting the various zones of an inking device of a printing machine by optical scanning of an illuminated original, such as a printing plate, printing film or printed product, which, iftransparent, is placed on glass plate and lightshonethrough, by means of a colour intensity measuring device intheform of a television camera, and by presetting, for the various zones, adjustment screws of a colorimeter or other elements of the inking device which adjustthe quantity of ink, with this presetting being controlled buy a computer, in a picture evaluating system using the picture data stored, in which the television camera used has a picture halftone resolution of at least 32 gradations and an individual calibrating characteristic linefor each picture point, the image scanned is digitalised and fed into a microcomputer for numerical calibration and calculation ofthe presetting points for the zone adjustment screws and from there is passed to a picture screen, whilstthe width (xz) ofthe colourzonesandthe numberofcolourzones can be adjusted at will using the microcomputer, and the limits ofthe colour zones are displayed on the picture screen by means of light or dark lines, and the halftones stored in the memory of the microcomputer can be equalised by means of characteristic lines and totalled zone by zone.

2. Method as claimed in claim 1, in which the totals are standardised (0 -100%).

3. Method as claimed in claim 1 or claim 2, in which the individual colour zone values are stored in a digital cassette and printed out on a printer.

4. Method as claimed in any one of claims 1 to 3, in which, using the picture screen,the userfeeds in an identification code which is allocated to the printing plate usedforthecolourin question.

5. Method of presetting the various zones of an inking device of a printing machine by optical scanning of an illuminated original, substantially as hereinbefore described with reference to the accompanying drawings.