EP1156383A2 - Method and apparatus for adjusting registration in an colour printer - Google Patents

Abstract

When print substrates of a different sort are fed into the printing machine (1) to correct the register setting, the creation and combination of the sub-color images (3,3') is controlled. If there is a change in the print substrate thickness due to a change of print substrate, the influence of the substrate thickness on the register is taken into account immediately. An Independent claim is also included for an apparatus for performing the method.

Description

The invention relates to a method for setting the register in a multi-color printing press with several devices for the digital generation of partial color images, whereby when feeding printing substrates of a different kind to Correction of the register setting, the creation and merging of the part color images is controlled.

The invention further relates to a device for carrying out the method a multi-color printing machine with several devices for digital generation of partial color images, with at least one controller when feeding printing substrates another type a register correction by controlling the generation and Merges the part color images.

The printing of colored representations, in particular colored images, takes place in that several partial color images are printed on top of each other. These are usually the ones Colors yellow, magenta and cyan as well as black. Special colors are also available if required added. By printing these colors on top of each other you can create all color combinations achieve, the quality of the prints significantly from the register Overprinting the partial color images depends. With digital, for example electrostatic Printing process becomes the register of overprinting achieved by controlling the imaging devices such that the Partial color images in register with each other when transferred to a printing substrate to meet.

A method and a device of the type mentioned at the outset is known from US Pat. No. 5,689. 757 known. It teaches there when feeding substrates of a different kind to take into account the influence of paper roughness on the register. For this, the Roughness of a paper to be printed is recorded. The influence of paper roughness on the register is then considered by the register control before the paper is fed to the printing process.

It has been shown that the change in register accuracy is affected of the printing substrate can only be detected in such an insufficient manner that high print quality cannot be achieved. This leads to the fact that only one Correction based on the evaluation of the print result is a satisfactory one Register accuracy can be achieved. The disadvantage of register setting However, there is an evaluation of the print result, for example using register marks in that when changing the print substrate by changing the print page Countermeasures are only possible for the next print because the effect of the Change of an influencing variable is only recorded if it already has a register error caused. This means that test prints are necessary and time is lost, what is uneconomical with small runs or only one copy to be printed is therefore not acceptable.

The invention is therefore based on the object of a method and a device of the type mentioned in such a way that in the event of a change in the printing substrate counteracted the influence of this change on the register to a high degree before the printing substrate is fed to the printing process.

The object is achieved according to the invention in that a change in print substrate thickness due to a change of print substrate the printing substrate thickness on the register using existing influencing variables directly is taken into account when implementing the change.

The object is achieved according to the invention in that the at least one controller is designed such that it changes when the Print substrate thickness due to a change of print substrate the influence of the print substrate thickness on the register using the available influencing variables directly with the Implementation of the change considered.

The invention is based on the knowledge that when changing the printing substrate the decisive influencing variable with regard to the register is the printing substrate thickness. This stems from the fact that the movements of the drawing and substrate-carrying elements Friction are linked. This is done by changing the print substrate thickness the for the transmission ratio between the print substrate carrier and decisive radius changed in a cylinder. This changing gear ratio affects the register to a much greater extent than the paper roughness. Above all, there is no other regarding the influence of the printing substrate thickness Possibility as the consideration when creating and combining the part color images. The influence of paper roughness, however, can be done in other ways can be counteracted, in particular by slipping through less Power transmission, the surface condition of the drawing frame cylinders as well the quality of the toner or other factors influencing the power transmission Materials is counteracted.

By considering the substrate thickness, the influence of the Register is essentially detected by a change of printing substrate. By this influencing variable on the register before feeding another type of printing substrate the printing process is taken into account when setting the register, it is possible that the occurrence of a register error is prevented from the outset, so that test prints on printing substrates, for example with register marks, is generally not required are. This is economical, especially for short runs or single copies important because machine time and often also printing substrates are saved. In addition, test prints are on the print substrate carrier without feeding Printing substrates for the correction of other influences on the register possible because the essential influence of the printing substrates is taken into account by the detection of their thickness is.

The measure according to the invention enables a register setting of a known type to be optimized in such a way that they change with print substrate changes when printing page changes not "getting out of hand" first to be corrected afterwards, but the register setting remains within the range of tolerable fluctuations, so that continue printing with another type of printing substrate without interruption can be. The invention includes the additional consideration of others Influencing factors, such as the paper stiffness, the toner application and also the paper roughness, not as far as they have an influence on the register. It plays with the invention Measure also does not matter whether the print substrate carrier with the Print substrates for transferring the partial color images directly with the image cylinders cooperates or whether image transfer cylinders are interposed.

A further development of the method provides that as a result of a register correction a change in the print substrate thickness, the retroactive influence of the print substrate thickness the previous but still in the printing process on the print page Register of the new print page already in the printing process is taken into account. It is taken into account for each printing unit if the gear ratio is still is determined by the printing substrates of the previous printing page, while already an illustration of the image cylinder with a partial color image of the new print page is made. It is also taken into account how this change of Printing substrate thicknesses takes place successively on one printing unit after the other, so to speak, "runs through the machine". In this way the register is correct the prints are even better guaranteed when changing the print page. The printing press can continue printing without interruption even if between the creation of two partial color images the print page change takes place in such a way that the new partial color image is already being created, while the previous partial color image is the previous print page not yet or not yet completely transferred to the print substrate has been. The register accuracy is therefore also high in this Guaranteed overlap between two printed pages and any mutual Influencing is compensated. This will make the printing press more economical significantly increased. With regard to the device, this is achieved in that the at least one controller is designed such that it is in a register correction due to a change in the substrate thickness the retroactive influence of Print substrate thickness of the previous one, but still in the printing process Print page on the register of the new print page already in the printing process considered.

The influencing variables of the printing substrate thicknesses can be taken into account on the basis of stored Data done. The detection of a print substrate thickness change by the Changing the type of printing substrates can be due to manual entry or by measuring the thicknesses of the printing substrates before they are fed to the printing process respectively. The influencing variables can be entered yourself or it is possible that data stored by the entry is activated for the register setting become. It is also possible that the consideration of the printing substrate thicknesses due to a saved file of the print pages. The influencing factors can be stored as stored data, the different print substrate thicknesses or are assigned to different types of paper.

The device can be provided with at least one memory is equipped, the stored empirical values of influencing variables of different Includes print substrate thicknesses, with the at least one control based of these empirical values, the creation and the assembly of the partial color images controls. However, it is also possible to use an input device equip, over which the influencing factors to be considered different Print substrate thicknesses can be activated manually. Another alternative is that the device is equipped with at least one memory, the stored Contains empirical values of influencing variables of different print substrate thicknesses, whereby the at least one controller using this data to create and merge controls the part color images.

Furthermore, the device can be a device for measuring printing substrate thicknesses have and the consideration of the latter activated by the device become. It can also have a press control and memory with files from Print pages may be provided, taking into account the influencing factors of various Print substrate thicknesses are based on these files. In this case it is useful if the files of the printed pages with different data stored Print substrate types are linked.

In essence, the invention has the purpose of correcting an intended one To serve register regulation. The latter can be designed such that it is on the detection is based on register marks, which are printed by the individual printing units become. The invention provides that this correction is carried out before a printed page and print substrate changes can affect the register marks. For the Device can also be provided that the at least one controller in this way is designed so that the register by means of register marks, which the individual Printing units printed and a register sensor are recorded, controls and the influencing variables the printing substrate thicknesses are taken into account as correction factors, the Correction is made before a print substrate and print page change affects the Can have registers.

However, the invention can also be used to correct a register regulation based on the detection of the positions of the part-color image and substrate-carrying elements. With regard to the device, it is then provided that the at least one controller is designed so that it registers by detecting the positions of the Part color image and substrate-carrying elements through position detection elements regulates and takes into account the influencing variables of the print substrate thicknesses as correction factors. The position detection elements can, for example, be rotary angle transmitters act. Such corrections are made before changes affect the Can have register marks.

Of course, it can be provided that other influencing variables that influence the Registers resulting from a change have been taken into account when setting the register become. For example, it can be toner profiles, types of paper, paper stiffness or other influencing factors. With regard to the device then at least one controller may be provided which takes these into account Influencing factors is formed.

Fig. 1

eine Erläuterung der der Erfindung zugrundeliegenden Erkenntnis und

Fig. 2

ein Ausführungsbeispiel der Erfindung.

The invention is explained below with reference to the drawing. Show it

Fig. 1

an explanation of the knowledge on which the invention is based and

Fig. 2

an embodiment of the invention.

In Fig. 1 it is shown how a change in the printing substrate thickness 17 with a change the printed pages 5, 5 'has an influence on the register. A printing unit 8 is shown a multi-color printing machine 1. Multi-color printing machines 1 have several Printing units 8, 8 ', ..., which must be considered here. The printing unit 8 has a device 2 for the digital generation of partial color images 3 an image cylinder 9. The partial color image 3 is by a transfer 30 from the Image cylinder 9 placed on an image transfer cylinder 10. Another one Transfer 31, the partial color image 3 comes on a printing substrate 16. The printing substrates 16 are transported through a print substrate carrier 11, the Printing substrates 16 pass through all printing units 8, 8 ', ... in succession.

In many multi-color printing machines 1 with digital generation of partial color images 3, 3 '... the drive takes place via a drive roller 23 of the print substrate carrier 11. In the exemplary embodiment shown, the print substrate carrier 11 in turn drives the Image transfer cylinders 10, 10 ', ... and these drive the image cylinders 9, 9', .... Of course, the printing substrate carrier 11 could directly the image cylinder 9, 9 ', ... drive. This is the case with machines that do not have an image transfer cylinder 10, 10 ', ... have. The arrows 22 show the directions of rotation of the cylinders 9, 9 ', ...; 10, 10 ', ... and arrow 29 the transport direction of the printing substrates 5 and thus the direction of movement of the print substrate carrier 11.

However, since the print substrate carrier 11 with the print substrates 16 via friction with the Image transfer cylinders 10, 10 ', ... and these with the image cylinders 9, 9', ... in Connection is made because, for example, the carrier 11 and the image transfer cylinder 11 drives, a curve 24 forms at the point of transmission 31, which the Speed of the image transfer cylinder 10 is affected. For example, if Paper thickness 17 changed in the direction of a thicker paper, so increases effective radius for driving the image transfer cylinder 10, because in this the Paper thickness 17 is included. The effective scope of the image transfer cylinder 10 thus becomes larger and thereby the image transfer cylinder 10 relative to the drive roller 23 slower. However, this problem is independent of whether the drive on the Drive roller 23 or elsewhere is initiated because the surfaces of the drawing and substrate elements 9, 9 ', ...; 10, 10 ', ...; 11 definitely on top of each other unroll.

A further problem is explained below with reference to FIG. 1 : While the partial color image 3 of the previous print page 5 is transferred from the image transfer cylinder 10 to a printing substrate 16, it is possible that the image cylinder 9 is already one with the partial color image 3 by the device 2 new print page 5 'is illustrated. This is shown with the reference numerals 3 and 5 'and the dash-dotted arrows. In this case, the printing substrate thickness 17 of the previous printing page 5 must be taken into account when imaging the image cylinder 9 in order to achieve register accuracy of the new printing page 5 '. Therefore, a further development of the invention provides that the at least one controller 12, 12 ', ...; 15 is designed such that it takes into account the retroactive influence 4 of the printing substrate thickness 17 of the previous printing page 5, which is still in the printing process, on the register of the new printing page 5 'already in the printing process when the register is corrected as a result of a change in the printing substrate thickness 17.

2 shows an exemplary embodiment of the invention, a multi-color printing press 1 with two printing units 8, 8 'being shown. This is also a simplification, normally four or more printing units 8, 8 ', ... are available. These have to be considered.

As already described, the multi-color printing press 1 has devices 2, 2 ', ... for the digital generation of partial color images 3, 3 ', ... on image cylinders 9, 9', ... on. Each printing unit 8, 8 ', ... has an image cylinder 9, 9', ... and an image transfer cylinder 10, 10 ', ..., the latter the partial color images 3, 3', ... on the Transfer printing substrates 16. These are in the direction of arrow 29 by one Print substrate carrier 11 transported by the printing press 1.

So that the partial color images 3, 3 ', ... are generated by the devices 2, 2', ... in this way that they are transferred in register to the printing substrates 16 are controls 12, 12 ', ... are provided which control the devices 2, 2', ... such that Image beginnings, lines or areas of the partial color images 3, 3 ', ... matched to one another are. The controls 12, 12 ', ... can each be assigned to a printing unit 8, 8', ... or it is possible that their task is a press control 15 for the entire multi-color printing press 1 takes over.

Such controls 12, 12 ', ...; 15 can be designed so that each printing unit 8, 8 ', ... prints a register mark 7, 7', ... and these register marks 7, 7 ', ... from a register sensor 18 can be detected. The evaluation of the position of the register marks 7, 7 ', ... then results in the assignment of the partial color images 3, 3', ... and it can in the event of deviations such a correction is made that the partial color images 3, 3 ', ... are transferred to the printing substrates 16 in register.

Another possibility is that the image cylinders 9, 9 ', ... and if necessary also the image transfer cylinders 10, 10 ', ... with position detection elements 19, e.g. B. are equipped with rotary encoders. Another rotary encoder 19 is provided on the drive roller 23 of the printing substrate carrier 11. By means of these position detection elements 19, the positions of the cylinders 9, 9 ', ...; 10, 10 ', ... and the print substrate carrier 11 assign to each other and it is possible, position shifts to detect and by the controls 12, 12 ', ...; 15 to correct so that register accurate printing is achieved.

It is true that both the detection of the register marks 7, 7 ', ... and the Position sensing a change in the register due to a change in the print substrate thickness 17 by changing the print page and correct it, but that has the disadvantage that the effect of changing the influencing variables 4, 4 ', ... different Print substrate thicknesses 17 must already have occurred in order to detect them to be able to correct. However, this means there is a continuous printing between one previous print page 5 and a new print page 5 'with another associated printing substrate thickness 17 not possible.

Therefore, the invention provides that the at least one controller 12, 12 ', ...; 15 is designed in such a way that it uses printing parameters 4, 4 ', ... of printing substrate thicknesses 17 their influence on the register immediately with a print page change 5, 5 'taken into account.

One possibility of taking into account influencing variables 4, 4 ', ... different Print substrate thicknesses 17 is that on an input device 14 data from Print pages 5, 5 'are input, via a connection 26 from the input device 14 are passed on to the controls 12, 12 ', ..., the controls 12, 12 ', ... based on this data on the printed pages 5, 5', ... stored empirical values 6, 6 ', ... for different printing substrate thicknesses 17 from memories 13, 13', ... retrieve and thereby obtain the influencing variables 4, 4 ', ... of the same, which are determined by the Controls 12, 12 ', ... are taken into account without a time delay. In this way the devices 2, 2 ', ... are able to digitally generate partial color images 3, 3 ', ... to be recorded without interruption. The stored data 6, 6 ', ... as empirical values for different printing substrate thicknesses 17 directly as influencing variables 4, 4 ', ... or to calculate them for the individual Printing units 8, 8 ', ... be stored in the memories 13, 13', ...

With regard to the determination of the influencing variables 4, 4 ', ... it is also possible that the Input device 14 and a connection 27 print pages 5, 5 ', ... to the press control 15 are given and this via a saved file Memory 21, the influencing variables 4, 4 ', ... to be taken into account - or data for Calculation of the same - for different print substrate thicknesses 17. The special one Advantage of this embodiment is that almost everything in the way of data processing he follows. The influencing variables 4, 4 ', ..., which the printing press controller 15 of the stored file of the memory 21 are connected to a connection 27 ' the controls 12, 12 ', ... relayed.

An expedient embodiment provides that a device 20 for measuring Print substrate thicknesses 17 is provided, which are the thicknesses 17 of the multi-color printing machine 1, for example printing substrates fed through a conveyor belt 25 16 measures, at least when a print page change 5, 5 'takes place. Because of this measurement can influence 4, 4 ', ... according to the measured substrate thickness 17 called or the stored data 6, 6 ', ... selected accordingly become.

2 , the partial color image 3 of the new print page 5 'is already being printed by the printing unit 8, while the printing unit 8' is still printing the partial color image 3 'of the previous printed page 5. Correspondingly, however, a print page change 5, 5 'can take place at a different point in time within a printing unit 8, 8', ... in such a way as has already been described for FIG . Then the print substrate thickness 17 of one print page 5 must be charged for the image formation of the other print page 5 '.

So that the controls 12, 12 ', ...; 15 the partial color images 3, 3 ', ... the printing substrates 16 can assign, at the beginning of the print substrate carrier 11 still one Sensor 22 for detecting the position of printing substrates 16 may be arranged, the Controls 12, 12 ', ..., 15 transmit the position in which a printing substrate 16 is located on the print substrate carrier 11.

The list in the embodiment of FIG. 2 is not exhaustive and must be not all of the alternatives shown may be provided in the machine. For example it is also possible to have only one input device 14 with a connection 26 to the controls 12, 12 ', ... to provide the stored empirical values 6, 6', ... for call up different print substrate thicknesses 17. Alternatively, it can be provided that the Influencing variables 4, 4 ', ... when changing the printing substrate directly on the input device 14 are entered or that the influencing variables 4, 4 ', ... from one Memory 21 can be removed by the press control 15. This can can be activated automatically or via an input on the input device 14. Another possibility, which is also possible separately, is the measurement of Print substrate thicknesses 17 by means of the device 20 described, in order to put down Influencing factors 4,4 ', ... or data 6, 6', ... to calculate the latter.

Most expedient, however, are all possibilities in one machine illustrated way provided depending on existing data or crucial Influencing factors in the operation of the machine select one or the other alternative to be able to. However, the configurations are only examples, other types of assignment of influencing variables and processing thereof are conceivable.

Reference list

1

Multicolour printing machine

2,2 ', ...

Devices for the digital generation of partial color images

3,3 ', ...

Part color images

4, 4 ', ...

Influencing variables of different print substrate thicknesses

5, 5 ', ...

Printed pages

5

previous print page

5 '

following print page

6, 6 ', ...

stored data for different print substrate types or thicknesses

7,7 ', ...

Register marks

8, 8 ', ...

Printing units

9, 9 ', ...

Image cylinder

10, 10 ', ...

Image transfer cylinder

11

Print substrate carrier

12, 12 ', ...

Control for achieving register-based prints (e.g. the Assigned to printing units)

13, 13 ', ...

Storage

14

Input device

15

Press control

16

Printing substrates

17th

Print substrate thickness, e.g. B. paper thickness

18th

Register sensor

19th

Position detection element, e.g. B. Angle of rotation encoder

20th

Device for measuring printing substrate thicknesses

21

Memory with files from printed pages

22

Sensor for the detection of printing substrates

23

Drive roller of the substrate for printing substrates

24th

Cornering

25th

Conveyor belt for feeding printing substrates to Multicolour printing machine

26

Connection of input device - controls

27

Connection of input device - press control

27 '

Connection of press control - controls (the printing units assigned)

28

Connection device 20 - controls (the printing units assigned)

28 '

Connection device 20 - press control

29

Arrow: direction of transport

30th

Transfer of a partial color image from the image cylinder to the Image transfer cylinder

31

Transfer of a partial color image from the image transfer cylinder a printing substrate

32

Arrows: directions of rotation

Claims (20)

Method for setting the register in a multicolor printing machine (1) with a plurality of devices (2, 2 ', ...) for the digital generation of partial color images (3, 3', ...), with another when feeding printing substrates (16) Sort to correct the register setting the creation and merging of the partial color images (3,3 ', ...) is controlled,
characterized in that in the event of a change in the print substrate thickness (17) as a result of a change in the print substrate, the influence of the print substrate thickness (17) on the register by means of existing influencing variables (4, 4 ', ...) is taken into account immediately when the change is carried out. Method according to claim 1,
characterized in that when the register is corrected as a result of a change in the print substrate thickness (17), the retroactive influence (4) of the print substrate thickness (17) of the previous print page (5), which is still in the printing process, on the register of the new print page already in the printing process ( 5 ') is taken into account. The method of claim 1 or 2,
characterized in that the influencing variables (4, 4 ', ...) of the print substrate thicknesses (17) are taken into account on the basis of stored data (6, 6', ...). Method according to claim 3,
characterized in that the thicknesses (17) of a new type of printing substrate (16) are measured before they are fed to the printing process. Method according to one of claims 1, 2 or 3,
characterized in that the detection of a change in printing substrate thickness (17) takes place on the basis of a manual input. Method according to one of claims 1, 2 or 3,
characterized in that the influencing variables (4, 4 ', ...) of the print substrate thicknesses (17) are taken into account on the basis of a stored file (21) of the printed pages (5, 5', ...). Method according to one of claims 1 to 6,
characterized in that the influencing variables (4, 4 ', ...) of different print substrate thicknesses (17) are available by storing the data (6, 6', ...) of different print substrate types. Method according to one of claims 1 to 7,
characterized in that it serves to correct a register regulation based on the detection of register marks (7, 7 ', ...) which are printed by the individual printing units (8, 8', ...), this correction takes place before a print page and print substrate change can influence the register marks (7, 7 ', ...). Method according to one of claims 1 to 8,
characterized in that it serves to correct a register control which is based on the detection of the positions of the partial color image and substrate-transmitting elements (9, 9 ', ...; 10, 10', ...; 11) before a change in the printing substrate takes effect can have on the register marks (7, 7 ', ...). Method according to one of claims 1 to 9,
characterized in that further influencing variables which have an influence on the register as a result of a print page change (5, 5 ', ...) are taken into account when setting the register. Device for carrying out a method according to one of claims 1 to 10 with a multicolor printing machine (1) with a plurality of devices (2, 2 ', ...) for the digital generation of partial color images (3, 3', ...), at least one Control (12, 12 ', ...) performs a register correction by supplying printing substrates (16) of another type by controlling the generation and combining of the partial color images (3, 3', ...),
characterized in that the at least one controller (12, 12 ', ...; 15) is designed in such a way that when the printing substrate thickness (17) changes, the influence of the same on the register by means of existing influencing variables (4, 4',. ..) immediately taken into account when implementing the change. Device according to claim 11,
characterized in that the at least one controller (12, 12 ', ...; 15) is designed in such a way that, when the register is corrected as a result of a change in the print substrate thickness (17), it has the retroactive influence (4) of the print substrate thickness (17) of the previous one , but the printing page (5) still in the printing process is taken into account in the register of the new printing page (5 ') already in the printing process. Device according to claim 11 or 12,
characterized in that it is equipped with at least one memory (13, 13 ', ...) which contains stored empirical values of influencing variables (4, 4', ...) of different print substrate thicknesses (17), the at least one controller ( 12, 12 ', ...) controls the creation and assembly of the partial color images (3,3', ...) based on these empirical values. Device according to claim 13,
characterized in that it has a device (20) for measuring printing substrate thicknesses (17) and the consideration of the latter is activated by the device (20). Device according to one of claims 11 to 14,
characterized in that it is equipped with an input device (14) via which the consideration of the printing substrate thickness (17) can be activated manually. Device according to one of claims 11 to 15,
characterized in that a printing press control (15) and a memory with files (21) of printed pages are provided, the influencing variables (4, 4 ', ...) of different printing substrate thicknesses (17) being taken into account on the basis of these files (21). Device according to claim 16,
characterized in that the at least one controller (12, 12 ', ...; 15) determines the influencing variables (4, 4', ...) of the various printing substrate thicknesses (17) by means of memories (13, 13 ', ... ; 21) stored data (6, 6 ', ...; 21) of different print substrate types. Device according to one of claims 11 to 17,
characterized in that the at least one controller (12, 12 ', ...) is designed such that it registers the register by means of register marks (7, 7', ...) which are used by the individual printing units (8, 8 ', ... ...) are printed and a register sensor (18) is recorded, regulates and the influencing variables (4, 4 ', ...) of the print substrate thicknesses (17) are taken into account as correction factors, the correction being carried out before the print page-related change affects the register marks (7, 7 ', ...). Device according to one of claims 11 to 18,
characterized in that the at least one controller (12, 12 ', ...) is designed such that it registers the register by detecting the positions of the partial color image and substrate-carrying elements (9, 9', ...; 10, 10 ', ...; 11) through position detection elements (19) and the influencing variables (4, 4', ...) of the print substrate thicknesses (17) are taken into account as correction factors before the print substrate changes influence the register marks (7, 7 ',. ..) may have. Device according to one of claims 11 to 19,
characterized in that the at least one controller (12, 12 ', ...) is designed in such a way that it has further influencing variables which influence the register as a result of a print page change (5, 5', ...) when setting the register considered.

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