Registers – Records – Particular code pattern
Reexamination Certificate
1999-11-19
2001-10-16
Lee, Michael G. (Department: 2876)
Registers
Records
Particular code pattern
Reexamination Certificate
active
06302330
ABSTRACT:
The present invention relates to a method and a device for checking patterns disposed on a material strip by photoelectric or other means, comprising control means and arrangements defined in the preambles of claims
1
and
9
, and a material strip.
BACKGROUND OF THE INVENTION
It is already known in the art to control processing operations on a travelling material strip by means of control marks printed on the strip which can be detected by photocells or other optical devices. These patterns which are disposed on the material strip are usually printed in a color tone which contrasts with the surroundings, thus enabling the detection means to detect the exact position of the material strip. These patterns can also be made with magnetically sensible material or with the help of patterns sensible by mechanical means, for example holes, crease lines, slots etc.
By the detection of the exact position of the material strip it is possible to apply multicolour printing on the material strip and to adapt the position of the pictures. These pictures contain several colours which are printed on the material strip by the usage of several processing machines, each of them printing a certain colour on top of the picture in process which has been prepared by preceeding processing machines which have printed other colours on the material strip. Therefore, a multicolour picture can be created and printed on the material strip wherein the different colours overlay each other at the exact position.
Another use of the checking device or checking method, respectively, is to detect the exact position of the material strip in order to apply a certain printing pattern on top of the previously preprinted material strip at a certain point or in order to arrange a printed pattern and a crease line pattern which facilitates the folding in register with each other.
Further fields of application exist, for example, where a packaging material strip is to be advanced in a packaging machine or the like over exactly the length of pattern so as to obtain, on the one hand, the printed pattern in the same position on all packages, and to ensure, on the other hand, that the said crease line pattern coincides with the forming device of the packaging machine so that the folding of the material takes place along the crease lines which are predetermined in their position. In order to manufacture the material strip, like stamping holes, applying opening apertures or additional crease lines, it is necessary to know the exact position of the material strip as well.
SUMMARY OF THE INVENTION
Up to know, it is well known to provide such material strips with patterns which can be detected by sensors, thus determining the exact position of the strip. It is known from EP-A-0 131 241 to use a pattern like a bar code with two groups of dark and light areas which succeed in the direction of the detection wherein the position of the dark areas and/or the light areas of one group with respect to a related detector is displaced in regard to the dark areas and/or the light areas of another group with respect to another related detector. These detectors detect the existence or, respectively, the non-existence of dark areas and/or light areas and produce output signals which depend on the result of the detection. This is carried out by using one detector which activates upon the detection of dark and/or light areas the other detector which detects the existence or the non-existence of dark and/or light areas wherein the output signals of the second detector are compared with a predetermined sequence of signals. If the sequence of output signals is equal to the predetermined sequence of signals the comparator will output an activation signal which activates the above described processing machines which require the exact position of the material strip.
These patterns usually disturb the general appearance of a décor of the material strip and it is desirable therefore, to accommodate the control patterns within the existing décor or on a very small blank surfaces which, in principle, only comprise the control patterns. However, this has given rise to great problems since the elements adapted to sense the patterns conceive and register all parts of the décor as well as the control patterns with the consequence that many output signals are supplied by the second detector depending on the dark and/or light areas of the décor and the control pattern. Since these output signals have to be compared within a real-time procedure it is quite likely to detect false signals by an undesired identity of a sequence of dark and/or light areas of the décor and the predetermined sequence of signals. Consequently, the wrong position of the material strip is detected and the following processing machines destroy the décor or the material strip by getting the wrong information.
It has been another great problem that the control pattern should be as small as possible, in order to avoid the optical disturbance of the décor, but should avoid the detection of false signals.
Additionally, there is a need of the packaging industry to be independent from any control patterns and to detect the décor of the material strip by, for example, the décor itself.
It is an object of the present invention to provide a device and a method for exactly and safely checking patterns disposed on a material strip in order to e.g. precisely detect the exact position of the material strip.
It is another object of the invention not to enlarge the size of the control but to increase the reliability of the checking device.
It is moreover another object of the invention to provide a method and a device for detecting the exact position of the material strip without any additional control patterns which could disturb the décor of the material strip.
Additionally, it is an object of the invention to be independent from the position of the control pattern and to increase the reliability of the method and of the device by using synergistically the outputs of the detectors.
The invention is characterized in claims
1
,
9
.
The invention is realized by using the output signals of at least two detectors, by combining the output signals to form a sequence of output signals in a predetermined way wherein each detector may enable the other detector to write output signals into a comparator upon detection of an edge of a dark or light area, and by comparing said sequence with a predetermined sequence, wherein the output signals comprise information concerning the dark and/or light areas.
This can be done by using the output signals of both detectors by combining them within the comparator. Upon detection of a dark area of one of the detectors a signal (e.g. a “1”) is written into the comparator, upon the detection of a light area, another signal (e.g. a “0”) is written into the comparator. Upon equivalence of the achieved sequence of output signals with a predetermined sequence of signals one or more actuators are activated.
This can also be done by using the output signals of one detector as a clock input for the comparator which enable a data input of the comparator to write output signals of the other detector into the comparator wherein the clock input is activated upon detection of an edge of one of the dark and/or light areas and vice versa. In order to enhance the reliability of the system the clock input can additionally be used as an output signal for the sequence of output signals which is compared with a predetermined sequence of signals and which depends on the transition of light to dark and dark to light areas. Consequently, the comparator receives a lot of output signals of more than one detector and therefore much better prevents the detection of false signals, pretending to have detected the control pattern, by detecting a sequence of dark and light areas within the décor on the material strip which is identical to the sequence of the control pattern. The comparator afterwards outputs an output signal upon equivalence of the sequence of output signals with the predetermined sequen
Hopgood, Calimafde, Judlowe & Mondolino LLP
Lee Diane I.
Lee Michael G.
Tetra Laval Holdings & Finance S.A.
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