GB2218046A

GB2218046A - Determining registration errors in printing apparatus

Info

Publication number: GB2218046A
Application number: GB8907046A
Authority: GB
Inventors: Udo Blasius; Manfred Korinek; Juergen Reithofer
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1988-04-02
Filing date: 1989-03-29
Publication date: 1989-11-08
Anticipated expiration: 2009-03-29
Also published as: CH680353A5; JPH01310963A; DE3811359C2; DE3811359A1; GB2218046B; GB8907046D0

Description

1 71 4 6

DESCRIPTION PRINTED PRODUCT REGISTER ERROR DETERMINATION APPARATUS

This invention relates to a register error determination apparatus suitable for use in the determination of register errors on a multicolour printed document, said printed product being provided with register mark S.

From DE-OS 32 26 078, a device is known with which the individual inking systems of a multi-colour printing press can be adjusted with regard to their register accuracy. This device contain a censor, which detect by optoelectronic meant the register mark on printing plate and converts them Into electrical signals. This sensor it permanently Installed Inside the printing unit of a printing press and In the region of the plate cylinder.

Usually, the register mark are situated in the region of non-image area on a printing plate. Their precise position I not laid down, but Is variable depending on the printed subject. Therefore, they may be located at any point on the printing plate.

For this reason, a measuring head for detecting register mark has already become known. aid measuring head being disposed on a crosa-member and thus being able to be adjusted across the entire width of the printed product. However, this measuring head mutt be cot and adjusted by hand. This is very time-consuming; furthermore, a large quantity of waste Is produced If the measuring head I adjusted while the press is in operation.

Consequently, the object of the invention is to create an arrangement with which the rapid positioning of the measuring head Is possible In order to detect the register marks.

The object of the Invention is achieved by an arrangement according to the features of the characterizing part of claim 1.

An essential advantage of the Invention consists In the fact that It Is no longer necessary to perform any manual adjustments to the measuring head on the printing press or at a measuring table. The positions of the register marks can be Input already during preparations for the printing job or also during the setting-up of the printing press, with the result that no furtheradjustments are necessary during the operation of the'printing press and, consequently, the measuring head supplies measured data for the control of register Immediately during the printing of proofs.

According to an advantageous further development of the invention, the measuring head comprises a finepositioning apparatus. This has the advantage that the measuring head need by moved only Into the vicinity of the register marks. By means of a search run, the measuring head scans a defined region within its position and automatically sets Itself to the precise position of the register marks. If the arrangement is used In a web-fed offset printing press, It is practical for the measuring head to be disposed In a location where the paper web runs smoothly. The Invention can be used to advantage particularly in a web-fed offset printing press with its large dimensions. The operator can position the measuring head directly from the control console without covering long working distances.

11 Of course, it is also possible to dispose the measuring head on a control console for a printing press. This has the advantage that the printed product can.#'multantsously be measured and visually assessed with regard to register error, with this being performed offline, i.e. outside of the printing press.

According to an advantageous further development of the invention, the position of the measuring head can be inputted prior to the start of printing, i.e. during preparations for the printing job. The Inputted position is stored, for example on a data cartridge. When the printing press Is being set up for the associated printing job, the data are read In from this data cartridge and the measuring head is positioned on the basis of these data. Owing to these preparatory measures, it is possible for the setting-up time of the printing press and thus the downtime of the printing press during production to be reduced.

In order to determine the positions of the register marks, It is possible to use a printing plate. From this printing plate, the Inking zone is determined In which the register mark Is located; the thus determined inking zone is Inputted via the Input apparatus. Of course, it is also possible to determine the positions of the register marks from a trial print. The procedure for inputting the position Is the same.

According to a further development of the Invention, it Is proposed to use as a control console for Inputting the position an inking-zone displayand Input system of the kind used in the majority of remote- control consoles for controlling a printing press. Such a so-called inking-zone display Indicates the Ink-film profile across the entire printing width. It consists, for example, of a plurality of rows of light- omitting diodes, with each row being assigned to an inking zone, and the length of each row represents the size of an Inking gap. By means of keys or other controls, the respective Inking zone can be activated and the Inking gap within the Inking zone can be adjusted. Such an Inking-zone display can be used In advantageous manner to input the position data for adjusting the measuring head. If a printing plate or a trial print Is placed on the control console above the Inking-zone display, it is Immediately apparent In which Inking zone the register marks are located. By actuating, for example, a specific key In this inking zone, It is possible to Input the position of the register marks into the control console. Thereupon, the measuring head moves to the corresponding position.

If the special case occurs in which the register marks are located between two inking zones, then, In a further embodiment of the invention, the Input apparatus may be designed in such a manner that, if the keys of two adjacent inking zones are actuated, the measuring head assumes a position between the two Inking zones.

In advantageous manner, the position of the measuring head can also be inputted with a higher resolution and/or accuracy. For this purpose, it is possible to use the respective row of light-emitting diodes of an inking zone. In this connection, tho length of the row of light-emitting diodes corresponds to the width of an inking zone. If, for example, the register marks are located precisely in the middle of the inking zone, then 4 i v the middle of the inking zone can be activated via the input elements (keys). This is indicated by the lighting-up of the middle light-emitting diode. Normally, a row of light-emitting diodes comprises 18 lightemitting diodes. This means that, if these lightemitting diodes are used for the fine subdivision of an inking zone, this inking zone can be subdivided into 16 subregions. Thanks to the fine-positioning of the measuring head, the automatic fine-positioning that is performed automatically by the measuring head after positioning is considerably shortened in time, with the result that register control can take effect virtually without delay after the printing press has started up.

Further advantageous embodiments of the invention are described in the subclaims,and in the following description.

The Invention Is explained in greater detail with reference to a specimen embodiment.

Fig. 1 shows an Input apparatus; Fig. 2 shows a measuring head disposed on a crossmember.

Most known printing presses comprise a control console, which, among other things, is provided for adjusting the inking-film-thickness profile in the individual printing units. Such a control console is known, for example, under the name CPC 1 from HEIDELBERGER DRUCKMASCHINEN AKTIENGESELLSCHAFT, literature reference: "Heidelberger Nachrichten" 3/40, Volume 1982.

- a - Fig. I shows a detail of a control- and display panel of such a control console. This control- and display panel can be used as an input apparatus for positioning a measuring head. An inking-zone display 2 is situated in the bottom region on the control console 1. The inkingzone display 2 consists of 30 rows of light-emitting diodes, with each row of light-emitting diodes indicating the position of an ink-metering element by the lighting-up of one or of two light-emitting diodes. The position of a row of light-emitting diodes corresponds in each case to the position of the inkmetering element in the inking unit. There are two keys under each row of light-emitting diodes 3, with the upper key being a positive key and the lower key being a negative key. With these keys, it is possible to adjust the ink-film thickness in the respective row or in the respective inking zone corresponding to that row. Such adjustment is indicated by the light-emitting diodes. Furthermore, a light pen 5 is provided. With this light pen also, it is possible to adjust the ink-film thickness in the individual inking zones. For this purpose, the light pen is moved to the appropriate row of light-emitting diodes. By means of suitable sensor devices, it-is then possible with the light pen to adjust an ink-metering element in the corresponding inking-zone row.

A supporting surface 6 is provided above the inking-zone display 2. A printed product can be laid on this supporting surface 6 In order to make a visual assessment of the application of ink In the Individual Inking zones. In order to position the measuring head, a printing plate 7 1 laid on the supporting surface 6. The position of the printing plate with reference to the i zc rows of light-omitting diodes 3 corresponds to the position of the printing plate in the printing press with reference to the corresponding ink-motoring elemenlis. The printing plate contains register marks 8 at a suitable point. The location of the register marks 8 on the printing plate Is not fixed, but is selected depending on the subject being, printed.

The register marks 8 ehown here are suitable for the online measurement of the register errors, i.e. a measuring head detect# these register marks while the paper web or a sheet of paper is moving past under the measuring head.

Fig. 2 shows a measuring head 9. Such a measuring head is manufactured, for example, by the company Croofield under the name "Autocrat 200. This measuring head Is situated inside a printing press on a croes-member 10. For the sake of simplicity, the printing press Is not shown. In a web-fed printing press, It has proved advantageous to position thie measuring head In front of the cutting register, since, In this region, the movement of the paper web Is very smooth and, therefore, It is possible to make a precise and accurate measurement of the register marks. The paper web 11 moves under the measuming headjunder the cross-member 10 in the direction of the arrow. The measuring head can be moved longitudinally on the cross-membor 10. Longitudinal movement is by means of a threaded spindle 12. This threaded spindle Is driven by a motor 13. The position of the measuring head 9 is adjusted to the positions of the register marks prior to the start of printing. Since the measuring head has an automatic fine-positioning facility, it is completely sufficient - a - to sat the measuring head approximately to the register marks 14. The position of the measuring head Is inputted via the control console 1 shown In Fig. 1. As has already been mentioned, the positions of the register marks 8 are evident from the printing plate 7. After actuating a command-initiation key 15, with which the positioning of the measuring head is started, the operator actuates the key 16, which I situated in the key panel 4 in the zone In which the register marks 8 are located. Thus, the positions of the register marks have been Inputted into the control panel. Via an input key 17, the command, I.. the positioning of the measuring head, Is executed. Thereupon, the motor 13 moves the measuring head 9 Into the region of the position of the register marks that are printed on the paper web 11 during printing (register marks 14). Instead of a printing plate 7, It is also possible, of course, to lay a printing proof or an already finished printed product on the supporting surface 6. The measuring head is positioned In the above-described manner.

Likewise, it Is possible, Instead of actuating the key 16, to use the light pen 5 for Inputting the position. For this purpose, the light pen 5 Is moved to the row of light-emitting diodes 18 that is situated in the inking zone in which the register marks 8 are also located. Furthermore, It is also possible to perform more accurate positioning of the measuring head In that the rows of light-emitting diodes 18 are used for a finer subdivision of the Inking-zone width. In this connection, an inking zone can be subdivided into 16 parts. Via the keys or via the light pen In the Inking zone In which the register marks 8 are located, the 1 4 precise position can be input and can be indicated by the lighting-up of an LED.

The specimer embodiment shown here features the on-line measurement of the register marks. It Is, of co urea, also possible to position a measuring head on the control console or on a measuring desk outside of the printing press and to perform a stationary off-line measurement. Here, too, however, the positioning of the measuring head Is effected In the above-described manner.

In addition, the specimen embodiment described here may comprise an apparatus that detects whether it is connected to a sheet-fed or to a webfed printing press. This is of advantage because, in the case of web-fed printing presses, in general, the inking zones, viewed from one end of the machine, are all counted in the same manner, for example from left to right, irrespective of whether the printing unit prints the paper web from below or from above. In conventional web-fed presses, this requires a reorientation on the part of the printer if, for example, he wishes to position the measuring head at the left-hand edge of an original for printing, because, depending on the printing unit, this may mean, for example, zone I or zone 32. Owing to the fact that the control device detects that the printing press is of the web-fed type, and owing to the fact that it has also been informed as to which inks are printed by a topprinting and by a bottom-printing unit, the apparatus is able, according to the invention, to set the zones in the correct manner in that it swaps round in a mirrorsymmetrical manner the assignment of setting data to the zones of specific printing units.

1 LIST OF REFERENCE NUMBERS 1 2 3 4 7 11 12 13 14 15 18 17 18 Control console Inking-zone display Rows of light-emitting diodes Key panel Light pen Supporting surface Printing plate Register marks Measuring head Cross-member Paper web Threaded spindle Motor Register marks Command-initiation key Key Input key Row of light-emitting diodes It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

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Claims

1. A register error determination apparatus suitable for use in the determination of register errors on a multi-colour printed product, said printed product being provided with register marks, the apparatus having a measuring head for the detection of the register marks, wherein the measuring head is displaceable across the width of the printed product, on a cross-member, by means of an actuator, and an input apparatus is provided for the lateral positioning of the measuring head in the region of an inking zone in which the register marks are located.

2. An apparatus according to claim 1, wherein the measuring head is provided with fine-positioning means, the apparatus being so designed that (in use) there is automatic fine-positioning of the measuring head at the register marks, within a predetermined working area.

3. An apparatus according to claim 1 or 2, which is installed in a web-fed offset printing press, with the measuring head disposed above and/or below the paper web after the last printing unit and before a web-cutting apparatus.

4. An apparatus according to claim 1 or 2, having its measuring head disposed on a control console of a printing press, the arrangement being such that the register marks of a printed product resting on the control console are scanned.

5. An apparatus according to any of the preceding claims, wherein the inking zone in which the positions of the register marks are located is detected by means of an input apparatus prior to the start of printing, and a storage apparatus is 12 - provided, data representing these positions being stored in said storage apparatus.

6. An apparatus according to any of the preceding claims, wherein the positions of the register marks are determined from a printing plate.

7. An apparatus according to any of claims.1 to 5, wherein the positions of the register marks are determined from a proof or trial print.

8. An apparatus according to any of the preceding claims, wherein (in use) inputting of data representing the positions of the register marks is effected with the aid of an input and display panel designed to permit ink-quantity regulation in the relevant inking zones, said panel comprising input and display elements assigned to respective inking zones, and being positioned on a printing-press console; the inputting of the data representing the positions of the register marks being effected in such a manner that, after the requisite input mode has been selected, the input element for the inking zone in which a given register mark is located is actuated in the sense appropriate to the positioning of the measuring head, and the positioning of the measuring head in the region of that inking zone is thereupon duly effected.

9. An apparatus according to claim 8, wherein the positioning of the measuring head in respect of register marks situated intermediately between two inking zones is effected by actuating the input elements of both of the two inking zones between which the register marks are located.

10. An apparatus according to claim 8 or 9, wherein finer positioning of the measuring head within an 11 1 inking zone is provided for by subdividing the width of the inking zone, in accordance with the provision of the display elements indicating the ink quantity within the inking zone, the arrangement being such that the measuring head can be positioned in fractional regions of the inking zone.

11. An apparatus according to any of the preceding claims, wherein a command-initiation key is provided to permit the initiation of a measuring head positioning procedure, and an input key is provided for effecting the positioning of the measuring head in accordance with the prior inputting of data representing the measuring head positioning required.

12. An apparatus according to claim 1, substantially as described with reference to the accompanying drawings.

Published 1989 at The Patent Offtce,State House, 65,71 High HaIbcrn.Lar. donVvClR4TP.FVrther copies maybe obtainedfrom The PatentOffice. Wes Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87