EP1553034A2 - Method and device for controlling events synchronous with a running web - Google Patents

Abstract

The method for the control of events synchronously to a moving material sheet (10) entails the sensing of the brightness and/or colour contrast differences of a sequence of marking patterns (3) applied to the material sheet for the purpose of identifying the marking pattern. The scanning of the marking pattern takes place through at least two linear-form sensors (2) consisting of several discrete sensor elements lying next to each other. The determined marking pattern is compared with a predetermined pattern and a control signal is sent out corresponding to the result of the comparison. An independent claim is included for a system to carry out the aforesaid method.

Description

The invention relates to a method and a device for Control of events synchronous to a moving Material web according to the preamble of claim 1 or claim 11.

Such an event or series of Events that synchronize to a high accuracy moved material web to be controlled for example, an observation of a moving printing web represent by means of a video camera, in which the recorded Picture frozen by a flash lighting and is recorded. The moment of triggering the flash determines which image content has been captured on the camera is.

To hit a well-defined point on the web You must have a resource installed that has a reference to a point of the printing line manufactures.

Usually, webs are transported by rollers, so these rollers as a starting point an assignment to a allow specific location of the material web. In case of a Application in a printing machine or a machine that Processes a pattern produced by printing especially the printing form a very good reference to printed motif. This is usually exploited, by fitting a rotary encoder to such a cylinder, whose pulses have a good relation to the web.

The disadvantage here is that by slippage and elongation of Material web moves this relation and thus the goal the pinpoint triggering is no longer achieved.

An improvement of this situation can be achieved be that a block mark is printed, which then to Synchronization by means of a conventional punctiform scanning Scanned light button. A disadvantage of this improved solution, however, is that this brand is a considerable size (especially width) must have to Even with lateral web run fluctuations still reliably recognized to be able to. The pressure of such a brand requires an additional cost of paper, on which the Brand is arranged.

Another improvement uses an ID code brand, which is recognized on the basis of its given pattern and can be used as a fixed point on the track. It will Although possible, the brand in an environment of print motifs However, the disadvantage remains that the brand must be relatively large in order to lateral Trajectories still to be found.

When using camera-like working sensors is It requires the entire image with a shot too to capture. This leads to longer codes for either several pictures have to be taken and processed or an adjustment must be made via a zoom function, which in turn leads to considerable costs.

It is therefore an object of the present invention, a method and a device for controlling events synchronous to a moving material web according to the preamble of Claim 1 or claim 11 to provide it allows to provide a controller with high accuracy To carry out comparatively little effort.

The solution to this problem is provided by the features of Claim 1 or claim 11. The dependent claims 2 to 9 have advantageous developments of the invention Method and subclaims 12 to 14 have advantageous Further developments of the device according to the invention to content.

According to the principles of the present invention is a novel method and a novel device for Recording and evaluation of signals created by a preferably come from a small brand and preferably with a fixed focal length and constant imaging characteristics can be included.

On the material web, in particular the printing web, is of a printing cylinder periodically (usually per Cylinder revolution once) a trademark (code mark) printed using dashes and spaces different dimensions. Over the track, in the this mark pattern is printed is the invention Device arranged.

According to the method of the invention, the trade mark pattern becomes recorded in the subsequent evaluation process preferably a brand recognition for the connected Process reached quickly enough.

This is preferably done by using a corresponding sensor device with at least two cells, arranged in a very short distance one behind the other are, each having a brightness difference signal between two successive sensor elements of the one and other line is formed.

This training is advantageous in that as the Influence of brightness fluctuations, for example caused by ambient light changes, as well as the Background to the signal formation is significantly reduced.

The emergence of the output signals is practically a local differentiation of the gray value curve, by the only at the brightness transitions a signal peak formed becomes. About a threshold operation are preferably all Signals are cut below a defined level, so that only significant light / dark transitions be marked.

The distances between the light / dark transitions are with the corresponding known distances from an ID code mark put into proportion and directly with a previously determined Ratio compared.

By the number of usable light / dark transitions that out resulting in the ID code mark, this creates one Consequence of relationships that, if equal, the pattern code represent. If there is sufficient agreement then an output signal is triggered. This output signal formation occurs when through at least one pair of sensors the wanted pattern has been recognized.

In a particularly preferred embodiment of the The device according to the invention has a measuring head, with a lighting device, a cell sensor element, that is preferably a photodiode double line represents, in which both cells are parallel to each other and are arranged perpendicular to the direction of movement, a Calculator with a memory, which signals the two Evaluates photodiode lines at high speed and an output which, upon detection of a Match of current code and pattern a signal emits.

This signal is synchronous with high accuracy and can for controlling, for example, an image recording of a Video camera, to be used.

The code mark is made of bars of alternating brightness (Alternatively, changing colors can be provided, the perceived as brightness change of the sensor array are) and is preferably a previously known Pattern of light / dark arrangements and thus transitions. The preferably provided beams lie in the web running direction seen one behind the other and thereby run when moving the Trace under the sensor array through.

Accordingly, they generate in the sensor elements that they happen, each a brightness change.

Since the controller according to the method or the device according to the invention in a running web, which is also printed with other print motifs, permanent must be done, is preferably a calculator structure provided, which performs the evaluation practically continuously and in the described application, the output signal with only very short delay, preferably less than 6 μs is.

For this purpose, the arithmetic unit may preferably be constructed so that the comparison process is parallel for all sensor elements the sensor arrangement is executed and thus almost immediately, if a coincidence is reached in a lane, the Output signal is formed.

For lower delay requirements until detection The model can also be a calculator and a method chosen be in the recorded signals first cached and then processed sequentially. When using CCD line sensors this can Process part be formed so that when parallel Reading out the lines immediately this difference value is formed and then proceed as described above.

Similarly, with a mixed mode of operation one can limited parallel processing with caching of Subareas are worked out of the lines when the accepted delay time allows this.

Preferably, in the method according to the invention further a further method step is inserted, accordingly the in signal formed in a preceding process step is further processed if it is below a defined Threshold is.

Preferably, in the method of the invention Sensor element consisting of a number of individual sensors be used.

As a standard distance can be in the inventive method of Distance between at least two previous signals to be used. Preferably, the standard distance is the distance between any two selected distances from the Signal sequence used.

Alternatively, it is possible to change the standard distance from one of a track synchronous driven pulse originating pulse train to build.

As another alternative, it is possible that the standard distance from the known movement speed of the Material web and the known geometric length of the Code pattern is calculated.

In the apparatus according to the invention can as Illumination device preferably a constant light source be provided for adequate illumination of the Recording field provides.

Another advantageous embodiment of the lighting device is that a LED lighting is used. Such a source consists of discrete ones Light-emitting surfaces. This training can be used others, the brightness distribution on the sensor affecting effects, e.g. the edge drop of an optic, to compensate. This, in turn, can be done, for example happen that driving the luminescent diodes with according to different currents, so that individual diodes also shine differently strong and thus cause a non-homogeneous illumination on the measurement object, but their distribution is precisely designed so that they, superimposed with the edge drop of the lens, a uniform Signal generated on the sensor. The same can also be done be achieved that the arrangement of the light emitting elements in a different surface density (diodes each Area unit) or in a respectively adapted different distance from the measuring field.

The passing object, in particular the material web, becomes advantageously via an optical system on the sensor level displayed. The arrangement of the light source and the Sensor arrangement depends on which type of Underground (reflective, transparent, reminiscent ...) the Trademark or Code mark has been and can be printed to serve different lighting principles, such as for example, a dark field illumination or a Bright field illumination.

A particularly advantageous development is given if the calculator is integrated with the measuring head such that such a unit only needs a power supply as well an output line and possibly a bus interface to Communication needed.

In the previously described, particularly preferred Embodiment, for example, via an integrated bus system the brand pattern to be detected by another external computer system, which also has a same bus interface equipped to be transmitted. It will possible, situation-adapted, different codes with the System to recognize.

With the previously described inventive method and The device according to the invention is in principle also possible to evaluate arbitrarily long codes without a code must be recorded completely and simultaneously.

Furthermore, it is possible according to the invention, in comparison to usual techniques smaller ID code brands or brand designs to recognize, even if the lens by procedural lateral movements a sensor at different location happens. Disturbing effects on detection, caused by Lighting fluctuations or fluctuations in the subsurface, can with the inventive method largely from the Measurement results are eliminated, so the way of working compared to conventional pure gray scale based methods can be significantly improved. Against a flutter of the Material web, resulting in both brightness variations, as also expresses picture size changes, that is Inventive method largely insensitive.

Furthermore, the inventive method and the Device according to the invention a training, the Real-time recognition process.

The device according to the invention preferably also has Sensor elements, which at an angle to the web running direction of> 0 ° are arranged.

Preferably, the angle between the web running direction and the sensor elements here at 90 °.

Furthermore, it is possible according to the invention that the sensor cells, in which the sensor elements are arranged, parallel are arranged.

Furthermore, it is preferably possible that the sensor lines integrated in a sensor.

Preferably, it is also possible to have an interface provide that the predetermined pulse train an arithmetic unit transmitted. Preferably, the arithmetic unit is a freely programmable logic device (FPGA device), which includes all operations.

The individual sensor elements can in the inventive Device further consist of lines that are not more than 128 Include sensor elements. Preferably, the exist Sensor elements themselves in turn from a number of Individual sensors. Preferably, as sensor elements two CCD cells (Charged Couple Devices) may be provided.

Alternatively, it is possible for the sensor elements to be a CMOS area sensor is provided, of which at least selected two lines are provided for evaluation.

In a further preferred embodiment is in the Sensor element for each two lines a known per se Hardware structure integrated.

Furthermore, the device according to the invention can be constructed in this way be that the light-emitting elements individually so be controlled that the emitted light power through other assemblies or elements caused known compensated for local inhomogeneities.

The arrangement of the light-emitting elements can Preferably, be chosen such that they by a different density in the arrangement by others Assemblies or elements caused known local Inhomogeneities compensated.

In a further preferred embodiment can be provided be that the arrangement of the light-emitting elements so it is chosen by a different distance the light emitting elements of the illuminated surface is suitable, by other assemblies or elements caused known local inhomogeneities compensate.

The lighting device may preferably have a Light stripes parallel to the arrangement of the sensor lines produce.

Furthermore, it is possible that between the sensor arrangement and the material web is provided an optical arrangement.

In a further preferred embodiment, between the sensor arrangement and the calculating unit, a device for Signal preprocessing be arranged.

Finally, it is basically conceivable that the Signal processing devices of the invention Device a controller for controlling or regulating the Calculator, the lighting control device and the Has interfaces.

Further details, features and advantages of the invention result from the following description of a Embodiment.

The sole figure of the drawing shows a schematic strong simplified block diagram of an inventive Contraption.

The device 1 shown in the drawing has first a lighting device 1a, which in the particular preferred embodiment shown with a Lighting control 1b is connected. The Lighting device 1a is used to illuminate one measuring material web image area of a material web 10. As the figure illustrates, the image area is in Example trap provided with a brand pattern 3 that off three arranged in the web running direction L one behind the other Brand elements 3a, 3b and 3c is constructed. in principle However, it would also be possible to have only two brand elements or to provide a greater number of these elements.

Furthermore, the device 1 according to the invention has a Signal processing device, which in the illustrated Embodiment an arithmetic unit 4a, an interface 7 and a Controller or a control / regulating device 9 has. Between the material web 10 and a sensor arrangement 2, the in the illustrated embodiment as a line sensor element is formed, an optic 5 is arranged. Between the Sensor assembly 2 and the calculator 4a is in the particular preferred embodiment according to the drawing a Device 4b arranged for signal preprocessing.

The arithmetic unit 4a is also in mutual relationship with an output (trigger) 6 and the controller 9 coupled. Of the Controller 9 in turn is connected to the device 1b for Lighting control and the interface 7 coupled. Finally, the device 1 according to the invention has a Power supply 8 on. The one shown in the figure Embodiment of the device 1 according to the invention is used preferably for carrying out the initially described Method for controlling events synchronous to the moving web of material 10 by means of a comparison of on the Material web 10 located brand pattern 3 with a predetermined brand pattern.

LIST OF REFERENCE NUMBERS

1

contraption

1a

lighting device

1b

lighting control

2

sensor arrangement

3

mark pattern

3a-3c

brand elements

4a

calculator

4b

signal preprocessing

5

optics

6

exit

7

interface

8th

power supply

9

controller

10

web

L

Running direction of the material web

Claims (14)

Method for controlling events in synchronism with a moving material web, comprising the following method steps: Detecting brightness and / or color contrast differences of brand patterns applied one after the other in the web running direction on the material web for the purpose of identifying the brand pattern; wherein the scanning of the brand pattern is performed by at least two successive line-shaped sensors, which consist of a plurality of discrete adjacent sensor elements; Comparison of the applied and registered on the web of brand with a given brand pattern; and Outputting a control signal according to the result of the comparison made. The method of claim 1, wherein from the measured values of the two sensor elements arranged one behind the other different lines a difference is formed and this for each pair of sensor elements and in this way a differentiation of the recorded by a line Brightness course is made. Method according to claim 1 or 2, wherein the distances between the remaining pulse-shaped signals for each signal sequence formed from two sensor elements in one Ratio is set to a standard distance, so that for each signal sequence has its own sequence of Distance conditions arises. The method of claim 3, wherein the ratio sequences each compared with those for the well-known brand pattern become. Method according to Claim 4, in which, in the event that for at least one sequence of relationships a match with the known pattern is detected, an output signal is set. Method according to one of claims 1 to 3, in which the waveform at least two turning points be found and an output signal is formed, the each at the inflection point of its amplitude by one Minimum amount changed. Method according to one of claims 1 to 6, in which as Norm distance the distance between at least two previous signals is used. The method of claim 1-7, wherein a threshold a histogram of the incoming measured values is formed, where the histogram is over one revolution of the Printing forme cylinder or a benefit with known Benefit size is gained, and the threshold is around 10% or 25% of the brightness value of the substrate different. Method according to one of claims 1 to 8, wherein the Degree of agreement given by tolerance values becomes. Method according to one of claims 1 to 9, wherein In addition, information about the absolute size at least Part of the brand pattern and the speed of the moving web is determined from the web speed and the measured track conditions additionally the absolute size of the measured brand designs or parts thereof calculated as areas with contrast differences This is in addition to the known size of the Brand pattern or part of it is compared and if there is no match, no output signal is set. Device (1) for controlling events in synchronism with a moving material web (10), characterized by an illumination device (1a, 1b) for illuminating a material web image area to be measured, which has at least one brand pattern (3) applied to the material web (10) and composed of at least two brand elements (3a, 3b, 3c) arranged in the web running direction (L). having; with a sensor arrangement (2), which has at least two in the web running direction (L) successively arranged sensor elements for scanning the material web image area; and a signal processing device (4a, 7, 9) which is coupled to the sensor arrangement (2) and has a signal output (6). Apparatus according to claim 10, characterized in that the signal processing means comprises an arithmetic unit (4a) for differentiation of the incoming signal from each sensor element and the subsequent normalization of the resulting ratio sequence, wherein the arithmetic unit (4a) is formed so that it has this predetermined sequence Pulse sequence compares and outputs an output signal via the signal output (6). Device according to one of claims 10 or 11, characterized in that the illumination device (1a, 1b) is formed as a continuous device and individually has light-emitting elements to compensate for local inhomogeneities of the illumination. Device according to one of claims 10-12, characterized in that a device (1b) for lighting control is provided, which performs a control of the brightness by detecting the maximum values of the brightness profile and the brightness is controlled such that the sensor arrangement (2) in all its elements of action always below the saturation limit is operable.

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