METHOD FOR CHECKING THE QUALITY OF PRINTED MATERIALS

Abstract

Some examples include checking the quality of printed products that are consecutively produced by multiple printing presses to have at least three printed patterns spaced apart from one another. The printed patterns are printed using different printing processes, such as a steel engraving process, an offset printing process, and a screen printing process that may be used for printing the three printed patterns of each printed product. A screen printing press is used for the screen printing process, with multiple steel plates being alternately used in the same production operation for the steel engraving process in an intaglio printing press. For at least two of the steel plates involved in carrying out the steel engraving process, a processing unit may selectively ascertain the deviation of the respective value of the relevant distances associated with the printed patterns, which may be instantaneously ascertained from a defined scale.

Claims

1-14. (canceled)

15. A method for checking the quality of printed materials, which are consecutively produced in a particular production operation by means of multiple printing presses, in each case at least three printed patterns being arranged on a respective area to be printed of each of these printed materials so as to be spaced apart from one another at a distance defined for this printed material; these at least three printed patterns being each printed in printing methods that differ from one another; for checking the quality of the respective printed material, two printed patterns printed in differing printing methods being selected by an inspection system for forming a printed pattern pair; the printed pattern pair being assigned a scale that is defined for the distance of its printed patterns; prior to the start of the particular production operation, this scale being provided with a tolerance that is defined as a function of the printing methods used in the relevant printed pattern pair; at least in a subset taken from the quantity of all printed materials that have been consecutively produced in the particular production operation, the quality of the produced printed materials being checked in that, during the particular printing operation, in each case an instantaneous value for the respective distance between the printed patterns selected for this printed pattern pair being ascertained by means of a processing unit of the inspection system, with the printed pattern pair being the same in each case; the processing unit comparing the respective value of the relevant distances, which is instantaneously ascertained in each case, to the scale defined for this distance, taking into consideration the associated tolerance, and ascertaining a deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from its defined scale, taking into consideration the associated tolerance; a steel engraving method and an offset printing method being used as printing methods for printing the printed patterns involved in the production of each printed material; an intaglio printing press being used for carrying out the steel engraving method, and an offset printing press being used for carrying out the offset printing method, characterized in that, additionally, a screen printing method is used as a printing method for printing the printed patterns involved in the production of each printed material; a screen printing press being used for carrying out the screen printing process; multiple steel plates being alternately used in the same production operation for carrying out the steel engraving process in the intaglio printing press; and for at least two of the steel plates involved in carrying out the steel engraving process or for all steel plates involved in carrying out the steel engraving process, the processing unit in each case selectively ascertaining the deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from its defined scale.

16. The method according to claim 15, characterized in that the printed materials are produced in a production system that comprises a combination of multiple printing presses in a single pass through this production system, or by means of respective separate printing presses that are arranged in a spatially separated manner in consecutive production steps.

17. The method according to claim 15, characterized in that the inspection system each case forms multiple printed pattern pairs for each printed material whose quality is to be checked, the respective distance scale of at least two of these printed pattern pairs being provided with a respective tolerance prior to the start of the particular production operation; the tolerances of printed pattern pairs that differ in at least one printing method in each case being differently defined; and the processing unit of the inspection system in each case ascertaining a deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from the respective scale, which is defined in each case, in the formed printed pattern pairs.

18. The method according to claim 15, characterized in that, in the relevant subset from the quantity of all printed materials that have been consecutively produced in the particular production operation, in each case an instantaneous value for the respective distance between the respective printed patterns of several of the printed materials belonging to this subset is ascertained by the processing unit of the inspection system, with the at least one printed pattern pair being the same in each case; the processing unit ascertaining a mean value from these instantaneously ascertained values for the respective distances and the processing unit ascertaining a deviation of the ascertained mean value from its scale defined for this distance, taking into consideration the associated tolerance.

19. The method according to claim 15, characterized in that, in the case of multiple subsets that are taken in each case from the quantity of all printed materials that have been consecutively produced in the particular production operation, a respective instantaneous value for the respective distance between the respective printed patterns of the printed materials contained in the respective subsets is ascertained by the processing unit of the inspection system, with at least one respective printed image pair being the same in each case; the processing unit in each case ascertaining a first mean value from these instantaneously ascertained values for the distances for each subset; the processing unit ascertaining a second mean value from these first mean values; and the processing unit ascertaining a deviation of the ascertained second mean value from its scale defined for this distance, taking into consideration the associated tolerance.

20. The method according to claim 18, characterized in that, prior to the determination of the mean value, the processing unit eliminates instantaneously ascertained extreme values in the respective subset for the respective distance between the respective printed patterns.

21. The method according to claim 18, characterized in that for at least two of the steel plates involved in carrying out the steel engraving process or for all steel plates involved in carrying out the steel engraving process, the processing unit in each case selectively ascertains the deviation of the ascertained mean value from its scale defined for this distance or the deviation of the ascertained second mean value from its scale defined for this distance.

22. The method according to claim 15, characterized in that the ascertained deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from its defined scale or the ascertained deviation of the ascertained mean value from its scale defined for this distance or the ascertained deviation of the ascertained second mean value from its scale defined for this distance is in each case represented on the display device.

23. The method according to claim 22, characterized in that a coordinate system is represented on the display device, in which, in each case with reference to the origin of this coordinate system, the respective deviations, as ascertained by the processing unit, of the respective values of at least one of the relevant distances, which are instantaneously ascertained in each case, from the associated defined scale and/or the ascertained deviations of the ascertained mean value from its scale defined for this distance and/or the ascertained deviation of the ascertained second mean value from its scale defined for this distance, are represented.

24. The method according to claim 23, characterized in that the respective permissible tolerances are represented around the origin of the coordinate system and characterize a tolerance range.

25. The method according to claim 24, characterized in that values to be represented outside the tolerance range situated around the origin of the coordinate system are represented in different colors than values to be represented within the respective permissible tolerance range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] An exemplary embodiment of the invention is illustrated in the drawings and will be described in greater detail below. The drawings show:

[0022] FIG. 1 a banknote including multiple printed patterns spaced apart from one another; and

[0023] FIG. 2 a representation of results obtained according to the invention on a monitor of a display device.

DETAILED DESCRIPTION

[0024] FIG. 1, by way of example and only schematically, shows a printed material 01 in the form of a security document 01, in particular a banknote 01, including printed patterns 03; 04; 06 that are spaced apart from one another, wherein these printed patterns 03; 04; 06 have each been consecutively printed in differing printing processes. In this example, it shall be assumed, without being limited thereto, that the printed pattern denoted by reference numeral 03 has been printed in an offset printing process, and the multiple, for example three, printed patterns each denoted by reference numeral 04 have each been printed in a steel engraving process, and the printed pattern denoted by reference numeral 06 has been printed in a screen printing process, on a preferably rectangular, in particular planar, area 02 to be printed of the printing substrate, which is used to produce the printed material 01 and preferably configured as a sheet. In the design of this printed material 01, reference lines indicated with dotted lines in FIG. 1 were defined, which show the distances A; B; C; D, defined before the start of production, between the printed patterns 03; 04; 06 to be printed or printed in the differing printing processes. A respective scale and a respective associated respectively permissible tolerance are assigned to these distances A; B; C; D. These scales, which each define a target value for each of the distances A; B; C; D, and their respective permissible tolerances are stored in a preferably digital processing unit, wherein this processing unit is configured, for example, as part of a, for example, opto-electronic inspection system, that is, comprising a camera. The quality of printed materials 01 is checked, for example, by evaluating the camera images photographically recording the printed patterns 03; 04; 06 printed onto the printing substrate, wherein these camera images are created by a camera of the inspection system, which is preferably configured as a semiconductor camera.

[0025] A method for checking the quality of printed materials 01 is now proposed, which are consecutively produced in a particular production operation by means of multiple printing presses, wherein, for each of these printed materials 01, in each case at least three printed patterns 03; 04; 06, which are each printed in printing methods that differ from one another, are in each case arranged on a respective area 02 to be printed of a printing substrate so as to be spaced apart from one another at the relevant distance A; B; C; D defined for this printed material 01. The inspection system in each case selects two printed patterns 03; 04; 06 printed in differing printing processes for forming a printed pattern pair, wherein, for example the inspection system, that is, preferably a program running in an in particular digital processing unit of this inspection system, in each case assigns a scale that is defined for the respective distance A; B; C; D of the selected printed patterns to the respective printed pattern pair. The respective scale is provided with a tolerance in the inspection system by its processing unit before the particular production operation starts. The respective tolerance is, or is being, defined in each case as a function of the printing methods used in the relevant printed pattern pair. The respective permissible tolerances may range between 0.3 mm and 3 mm, for example.

[0026] The quality of the produced printed materials 01 is now checked in that, during the particular production operation, preferably inline, that is, during ongoing production, a value for the respective distance A; B; C; D between the printed patterns 03; 04; 06 selected for this printed pattern pair is ascertained, preferably by way of programming, by means of the processing unit of the inspection system, at least in a subset from the quantity of all printed materials 01 that have been consecutively produced in the particular production process, with the printed pattern pair of these printed materials 01 being the same in each case. The processing unit then compares the instantaneously ascertained value of the relevant distance A; B; C; D to the scale defined for this distance A; B; C; D, taking into consideration the associated tolerance, and ascertains a deviation of the instantaneously ascertained value of the relevant distance A; B; C; D from its defined scale, taking into consideration the associated tolerance. In the event that the processing unit ascertains an intolerable deviation of the instantaneously ascertained value of the relevant distance A; B; C; D from its defined scale, the relevant printed material 01 is, for example, discharged from the ongoing production process and/or the processing unit, preferably automatically, changes a setting of the relevant printing press which influences the ongoing production process, or at least prompts such a change, so that printed materials 01 produced thereafter by this printing press in each case correspond to the desired quality again.

[0027] It may be provided that the inspection system each case forms multiple printed pattern pairs for each printed material 01 whose quality is to be checked, wherein the respective scale of at least two of these printed pattern pairs is provided with a respective tolerance by the inspection system prior to the start of the particular production operation, the tolerances of printed pattern pairs that differ in at least one printing method in each case being differently defined, and the processing unit of the inspection system in each case ascertaining a deviation of the respective value of the relevant distances A; B; C; D, which is instantaneously ascertained in each case, from the respective scale, which is defined in each case, in the formed printed pattern pairs.

[0028] As mentioned, a steel engraving method and an offset printing method and a screen printing method are used as printing methods for printing the printed patterns 03; 04; 06 involved in the production of each printed material 01, an intaglio printing press being used for carrying out the steel engraving process, and an offset printing press being used for carrying out the offset printing method, and a screen printing press being used for carrying out the screen printing method. The printed materials 01 can be produced in a single pass in a production system that comprises a combination of multiple printing presses arranged contiguously, or by means of respective separate printing presses that are arranged in a spatially separated manner in consecutive production steps.

[0029] In a preferred embodiment of the invention, in the relevant subset, which consists of multiple, for example 50 to 200 printed materials 01, taken from the quantity of all printed materials 01 that have been consecutively produced in the particular production process, the respective instantaneous value for the respective distance A; B; C; D between the respective printed patterns 03; 04; 06 of several of these printed materials 01 belonging to this subset is ascertained by the processing unit of the inspection system, with the at least one printed pattern pair being the same in each case, wherein the processing unit ascertains a mean value from these instantaneously ascertained values for the distances A; B; C; D, and wherein the processing unit ascertains a deviation of the ascertained mean value from its scale defined for this distance A; B; C; D, taking into consideration the associated tolerance.

[0030] In a particularly preferred embodiment of the invention, in the case of multiple subsets that are in each case taken from the quantity of all printed materials 01 that have been consecutively produced in the particular production process, a respective instantaneous value for the respective distance A; B; C; D between the respective printed patterns 03; 04; 06 of the printed materials 01 contained in the respective subsets is ascertained by the processing unit of the inspection system, with at least one respective printed image pair being the same in each case, wherein the processing unit ascertains a first mean value from these instantaneously ascertained values for the distances A; B; C; D for each subset, wherein the processing unit ascertains a second mean value from these first mean values, and wherein the processing unit ascertains a deviation of the ascertained second mean value from its scale defined for this distance A; B; C; D, taking into consideration the associated tolerance.

[0031] In the two aforementioned embodiments of the invention, the processing unit, in each case before the respective mean value is determined, advantageously checks an instantaneously ascertained value of the relevant distance A; B; C; D for its plausibility and excludes the value from the mean value determination if a lack of plausibility is present. As an alternative or in addition, likewise prior to the determination of the respective mean value, the processing unit can eliminate instantaneously ascertained extreme values, that is, at least one instantaneously ascertained minimum value and/or at least one instantaneously ascertained maximum value, in the respective subset for the respective distance A; B; C; D between the respective printed patterns 03; 04; 06. Moreover, the processing unit can also calculate a standard deviation from the respective mean value in each case.

[0032] Printed materials 01 embodied in each case as security documents 01 or as banknotes 01 are frequently produced on a sheet in multiple-ups, so that the relevant printed materials 01 are each arranged in multiple rows and columns on the relevant sheet. The above-described averaging methods are preferably applied to those printed materials 01 that are in each case arranged at the corners of the relevant sheet since, in these positions, the largest deviations of the instantaneously ascertained value of the relevant distance A; B; C; D from the defined scale is to be expected, taking into consideration the associated tolerance. The reason is that the aforementioned disturbing influences become the most noticeable there. The processing unit can also in each case, in particular, calculate an elongation of the at least one printing forme used in a printing method, in particular an elongation of the steel plate carrying out the steel engraving method, from the deviations of printed materials 01 that are in each case arranged at the corner positions of a sheet.

[0033] In another important embodiment of the invention, multiple, for example three, steel plates are alternately used in the same production operation for carrying out the steel engraving process in the intaglio printing press, wherein the processing unit, for at least two of the steel plates involved in carrying out the steel engraving process or for all steel plates involved in carrying out the steel engraving process, in each case selectively ascertains the deviation of the respective value of the relevant distances A; B; C; D, which is instantaneously ascertained in each case, from its defined scale, or the deviation of the ascertained mean value from its scale defined for this distance A; B; C; D, or the deviation of the ascertained second mean value from its scale defined for this distance A; B; C; D. The processing unit thus in each case ascertains the respective deviation and/or the respective first and/or second mean values separately for each relevant steel plate.

[0034] The ascertained deviation of the respective value of the relevant distances A; B; C; D, which is instantaneously ascertained in each case, from its defined scale and/or the ascertained deviation of the ascertained mean value from its scale defined for this distance A; B; C; D and/or the ascertained deviation of the ascertained second mean value from its scale defined for this distance A; B; C; D, are preferably displayed in each case on a monitor 07 of a display device in a manner that is controlled, for example, by the processing unit of the inspection system.

[0035] FIG. 2, by way of example, shows a representation of results obtained according to the invention on the monitor 07 of the display device. A Cartesian coordinate system is shown, for example, on the monitor 07, in which, in each case with reference to the origin of this coordinate system, the respective deviations, as ascertained by the processing unit, of the respective values of at least one of the relevant distances A; B; C; D, which are instantaneously ascertained in each case, from the associated defined scale and/or the ascertained deviations of the ascertained mean value from its scale defined for this distance A; B; C; D and/or the ascertained deviation of the ascertained second mean value from its scale defined for this distance A; B; C; D, are in particular graphically represented.

[0036] Specifically, FIG. 2 shows, by way of example, the respective deviations, as ascertained by the processing unit, of the respective values of three distances A; B; C, which are instantaneously ascertained in each case, between a printed pattern 03 printed in each case in an offset printing process, and a printed pattern 04 printed in each case in a steel engraving process, from the respective associated defined scale. These three distances A; B; C; D result, for example, from the use of three steel plates P1; P2; P3 used alternately in the same production operation, for example around the circumference of the same impression cylinder. As mentioned above, printed materials 01 of the type in question are frequently produced on a sheet in multiple-ups. The illustration of FIG. 2 relates, for example, to a printed material 01 that is arranged on the relevant sheet in a corner position. In the illustration of FIG. 2, values generated by the first steel plate P1 are in each case represented, for example, by a square, values generated by the second steel plate P2 are in each case represented, for example, by a diamond, and values generated by the third steel plate P3 are in each case represented, for example, by a triangle. In the immediate surroundings around the origin of the coordinate system, the respective permissible tolerance for the relevant scale is represented. This illustration characterizes a tolerance range that, in this example, extends in each case, both on the x-axis and on the y-axis of the represented coordinate system, from the coordinate value −0.5 to the coordinate value +0.5, whereby a permissible tolerance of ±0.5 mm is indicated for the particular scale. Values and/or deviations to be represented outside this tolerance range and ascertained by the processing unit are represented in different colors, for example, than values to be represented within the respective permissible tolerance range. This illustration in particular allows a trend in the print register that arises during production printing to be easily recognized during the production of the printed materials 01 of the type in question. Moreover, it is possible for the processing unit to calculate further parameters, for example, a change in length of the printing formes, in particular of the steel plates P1; P2; P3, from the ascertained and/or displayed values and/or deviations, possibly taking further information into consideration, for example regarding the position of a particular printed materials 01 in the multiple-ups.

[0037] Although the disclosure herein has been described in language specific to examples of structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described in the examples. Rather, the specific features and acts are disclosed merely as example forms of implementing the claims.