EP1652806B1 - Device for detecting of successive units of an endless web - Google Patents

Abstract

A sensor (4) detects characteristics of an endless conveying path (1), such as the spacing of one of the prints (2,3) from the edge of each unit (10) in the conveying path. The sequencing of such units can be repeated based on the detected result. A sound is emitted upon recognition of such sequencing. An independent claim is also included for a method for recognizing successive units in a conveying path.

Description

The invention relates to an apparatus and a method for the detection of successive units of an endless, in a conveying process web with a sensor for detecting along the path changing properties thereof. Such devices are well known in the art and are used, for example, in the paper or printing industry for cutting printed or unprinted paper webs into individual sheets or sheets. In order to be able to trigger a cutting process as accurately as possible at a transition between two successive units or sheets or sheets, according to the prior art, the endless web or the endless paper strip is provided with markings which are located at a predetermined relative position to the desired reference interface , These markings can then be detected by, for example, sensors designed as contrast sensors, each detection of a marking triggering a cutting process.

A disadvantage of these known devices and methods is the fact that specifically for the processing of the endless web or for cutting a paper strip markings must be provided on the web, which are basically undesirable for design reasons. Furthermore, the markings per unit can undesirably lead to a repeated switching of a contrast scanner, so that it can not be clearly recognized which of the on the desired cutting position related switching operation, which in turn can have a faulty cut result.

document DE 10154003 A discloses an apparatus and a method according to the preamble of claims 1 and 8, respectively.

An object of the invention is to develop a device and a method of the type mentioned in such a way that on the one hand can be dispensed with the disadvantageous markings and on the other hand it is ensured that the processing or cutting of the web takes place in each case at the correct position.

This object is achieved with a device according to the invention according to claim 1.

According to a method of the invention, said object is achieved by the features of claim 8.

The invention is therefore based on the surprising finding that for the detection of successive units of an endless web not necessarily dedicated markers must be attached, but that it is sufficient, the existing anyway on the web, varying over the length of the web properties sensorially to capture and evaluate in an appropriate manner. In this case, according to the invention, it is possible in particular to make use of the fact that the said changes in the web properties are repeated in successive units, so that the detected ones Changes can be assigned to exactly one unit of the train. As a result of this assignment possibility, the successive units of a web can be detected accordingly. Since the changing web properties also have a constant location reference to the transitions of adjacent units, these transitions can also be easily determined with the device according to the invention and with the method according to the invention, so that, for example, automatically a cutting process can be triggered at these transitions.

In customary applications, the changes to the web properties to be detected are repeated in all units of the web, so that they can be cut, for example, in noisy mutually identical units. However, there are also other applications conceivable in which the repetitive changes in the web properties are not present in all units in the same way. For example, it is possible for a web to have two different types of units, each of which has mutually repeating changes in web properties, but the changes of one type differ from the other type. In this case, it can then be distinguished according to the invention, of which of the two types is the respectively recognized unit, whereupon a matched to the respective type processing can be triggered.

According to the invention, the sensor is designed to detect a sequence of a plurality of mutually different changes in the web properties. This makes it possible to detect two or more changes in the web properties relative to each unit of the web, which increases the uniqueness of the detection result. If, for example, three different changes per unit are to be detected, of which the last change occurs during the transition to the subsequent unit, it can be checked according to the invention whether the first two changes were detected first, whereupon the third change only counts as a transition to the next unit if the first two changes were detected correctly before. The security and reliability of a correct recognition can thus be significantly increased by this preferred variant of the invention.

According to the invention, a memory is provided in which a chronological setpoint sequence of the changes to be detected per unit can be stored. Furthermore, an evaluation unit is provided for comparing the actually chronologically detected change sequence with the stored desired sequence, with which it is checked whether the expected change sequence was actually detected and thus a unit was recognized. In the case of the correspondence between the stored desired sequence and the detected change sequence, the evaluation unit can then emit a detection signal related to the detected unit.

In order to obtain additional security with regard to the comparison result in the aforementioned comparison between the desired sequence and the actually detected change sequence, the relative time references and / or the respective type of changes and / or the respective degree of changes can be taken into account in addition to the chronology of the changes. In this case, it is then examined in which temporal relation the detected changes are related to each other and / or of which type and of which magnitude the detected changes were.

All changes detected on one unit preferably lead to the delivery of only a single detection signal, which can be unambiguously assigned to the respectively detected unit. This single detection signal is preferably dependent on a change with a comparatively high degree of change, since such a change, which may be formed for example as a particularly striking, sharp color transition, can be recognized particularly well by the sensor. If the distance between this change and the beginning or the end of the respective unit is known, the start and end of the unit can be identified with a particularly high spatial resolution, since the respective position can be simply calculated from the position of the detected change and the known distance ,

A delay element may also be provided for triggering the detection signal with an adjustable time delay after detection of the correspondence between the stored desired sequence and the actually detected change sequence. With such a delay element can be taken into account, for example, the fact that a cutting device is behind the sensor according to the invention in the conveying direction and thus must depend on the detection of a unit dependent on the delivery speed time until the detected unit or its beginning or the End is located in the area of the cutting device. The delay element can thus be set, for example, exactly so that, depending on the units detected according to the invention, a cut always takes place exactly at the transition between two units by the cutting device. Furthermore, it can be considered with the delay element, if the last detection of a change in a unit not at the end of the unit but already before, so that the end of the unit is not yet below the sensor at detection of the last change. The delay element is then adjusted in dependence on the conveying speed such that the delay time or at least a component thereof corresponds to the time required to further convey the unit by the distance between the last detected change and the end of the unit. Of course, the delay element can also be adjusted so that, on the one hand, the latter delay and, on the other hand, the already mentioned distance between the sensor and a cutting device is taken into account.

The delay times caused by the delay element do not necessarily have to be constant. Rather, they can be adapted to the respective conveying speeds. In particular, however, a change in the delay times during the conveying process of a single web can take place, if this web is conveyed at different times at different speeds.

Alternatively to the use of a delay element with adjustable delay time, a constant delay time can also be given at a constant conveying speed, since in this case, for example, the sensor can simply be displaced along the conveying path as part of a teaching operation, until e.g. a separation process initiated by the sensor always takes place exactly at the transitions between two units.

With known conveying speed can be closed from the detected changes on the length of color elements, which are located on the web. The beginning and the end of such color elements are detected as changes according to the invention, and the time elapsed between these detection operations can then be considered the conveying speed the length of a color element is calculated and stored. Furthermore, the length of the color elements calculated in this way can then be used as a recognition feature for successive units by checking on each unit of the web whether the color elements assigned to the respective unit have the length determined in previous units.

If, on the other hand, the conveying speed is known only during a training phase and is no longer known during further operation, the length of a color element determined in normal operation can be used to calculate the currently present relative conveying speed. For example, a normalized conveying speed of 1 may be present within the scope of the teaching process, in which the value of 1, which is also normalized, is determined as the length of a color element, for example. If a length of the color element of 2 is now detected in the normal operation of the system following the training phase, it can be assumed that the instantaneous conveying speed-also normalized-is 0.5.

The sensor for detecting the changes in web properties used according to the invention can be designed so that it can detect changes in the color, the contrast, the reflectivity and / or other surface textures of the web. Different types of changes in the web properties can thus be used to implement the inventive concept, whereby, for example, sensor arrangements consisting of a plurality of sensors can also be used, which can simultaneously detect different types of changes. It is therefore quite possible to detect a single unit by detecting successive changes in the web properties of different types. Basically you will always use those types of changes for the evaluation, with which the amplitude-wise largest sensor signals can be generated, since in this way the risk of misdetections is minimized.

In a preferred embodiment, the sensor can be designed as a contrast scanner, which can illuminate the web with different transmission colors. In this case, depending on the color of the changes to be detected during the scanning of each unit, the transmission color can then be changed such that a respective maximum contrast value is established.

The web investigated according to the invention may be a printed or unprinted paper web. During the processing of printed paper webs, the printing ink present on the web can trigger the contrast jumps to be evaluated according to the invention.

Further preferred embodiments of the invention are described in the subclaims.

Fig. 1

eine Draufsicht auf eine schematisch dargestellte erfindungsgemäße Anordnung, und

Fig. 2

ein vereinfachtes Blockschaltbild einer erfindungsgemäß zum Einsatz gelangenden Auswerteeinheit.

The invention will be described below with reference to an embodiment with reference to the figures; in these show:

Fig. 1

a plan view of a schematically illustrated inventive arrangement, and

Fig. 2

a simplified block diagram of an inventively used reaching evaluation.

In Fig. 1 a portion of an elongate web 1 is shown, which consists of paper and is transported in the conveying direction A. These Paper web was previously provided in a printing machine, inter alia, with imprints 2, 3, wherein the imprints 2 differ in color from the imprints 3.

The paper web 1 consists of adjacent, mutually identical units 10. The transition between two adjacent units is in Fig. 1 denoted by the reference numeral 11.

Out Fig. 1 It can be seen that the imprints 2, 3 are arranged in all successive units 10 in each case in the same position and in particular at the same relative position with respect to the transitions 11, so that the imprints 2, 3 along the path 1 ultimately form a periodically repeating pattern ,

Above the web 1, a sensor 4 is arranged, which is designed as a contrast sensor, which can illuminate the web 4 with different colors. In the conveying direction spaced from the sensor 4, a cutting device 5 is provided, by means of which the web 1 can be cut perpendicular to the conveying direction A.

Sensor 4 and cutting device 5 are coupled via data and control lines to an evaluation unit 6, which receives and processes data from the sensor 4 and furthermore is able to control the sensor 4 and the cutting device 5.

A block diagram of the evaluation unit 6 according to Fig. 1 is in Fig. 2 shown.

The central component of this evaluation unit 6 is the arithmetic unit 7, which can be formed, for example, as a commercially available microprocessor. Via an interface A, the arithmetic unit 7 receives signals from the sensor 4, via an interface B, the arithmetic unit 7 can control the sensor 4. Via an interface C, the arithmetic unit 7 receives information regarding the current conveying speed of the web 1.

The arithmetic unit 7 communicates with a memory 8, in which a chronological setpoint sequence of the color changes to be detected by the sensor 4 can be stored.

The arithmetic unit 7 acts on a delay unit 9 whose delay time .DELTA.t is variably adjustable via the arithmetic unit 7. The output of the delay unit 9 is fed to an interface D, which is connected to the cutting device 5 and triggers a cutting operation upon the delivery of a signal via the interface D.

When operating the arrangement according to the Fig. 1 and 2 First, a chronological setpoint sequence of the color changes to be detected per unit 10 is stored in the memory 8. This setpoint sequence can be determined, for example, by means of a teach process via the sensor 4. In the memory 8 is also stored, in which temporal sequence caused by the imprints 2, 3 changes occur. In concrete terms, it is thus stored with which temporal relation in each case the beginning and end of the imprints 2, 3 pass by the sensor 4 at a predetermined conveying speed. In the example shown, the rear end of the imprints 2 in the direction of conveyance A is the most striking color transition in the area of the imprints 2, 3 and the distance d of this color transition from the transition the unit 10 carrying the respective imprint to the next unit 10 is known to the evaluation unit 6.

During actual operation of the arrangement, the sensor 4 then provides change signals each time the beginning and end of the imprints 2, 3 are passed past the sensor. These data are supplied to the arithmetic unit 7 via the interface A, whereupon the arithmetic unit 7 compares these data with the values stored in the memory 8. If the computing unit 7 determines in the context of a real-time processing that the sequence of detected changes coincides with the sequence stored in the memory 8, it can be assumed that after recognizing the then expected rear end of the imprint 2, which represents the most striking color transition , this rear end of the imprint 2 is just below the sensor 4. At a constant conveying speed, the arithmetic unit 7 can accurately calculate from the known distance between sensor 4 and cutting device 5 and said distance d, after which delay time the transition 11, which follows the end of the detected imprint 2, comes to lie below the cutting device 5. After elapse of a corresponding delay time .DELTA.t, which is effected by the delay element 9, then a switching signal is output via the interface D to the cutting device, which triggers a cutting process along the transition 11. If the conveying speed changes, the arithmetic unit 7 can calculate a correspondingly adapted delay time Δt, which is then made available to the delay element 9 by the arithmetic unit 7.

In the context of the above-mentioned teach process can also be checked with which color the web 1 must be illuminated by the sensor 4, so that contrast transitions of the imprints 2, 3 particularly good are recognizable. For example, it may be useful to recognize the beginning and end of the imprint 2 with the illumination color green and the beginning and end of the imprint 3 with the illumination color blue. A switching of the illumination color during the scanning of a unit 10 can in turn be performed by the arithmetic unit 7, for example via the interface B according to FIG Fig. 2 depending on stored in the memory 8 data are triggered.

LIST OF REFERENCE NUMBERS

1

train

2

imprint

3

imprint

4

sensor

5

cutter

6

evaluation

7

computer unit

8th

Storage

9

delay

10

unit

11

crossing

A

conveying direction

Claims (8)

1. An apparatus for the recognition of sequential units (10) of an endless web (1) present in a conveying process having a sensor (4) for the detection of properties of the web (1) varying along the web (1), wherein the sensor (4) is designed for the recognition of variations in the colour, in the contrast, in the reflectivity and/or in other surface properties of the web (1) which repeat in sequential units (10),
   characterised in that
   the sensor (4) is designed for the recognition of the sequence of a plurality of variations in the web properties which differ from one another of each unit (10) to be recognised;
   in that a store (8) is provided in which a desired chronological sequence of the variations to be detected per unit (10) can be stored; and
   in that an evaluation unit (6) is provided for the comparison of the actually chronologically detected variation sequence with the desired sequence and for the triggering of a detection signal related to a recognised unit (10).
2. An apparatus in accordance with claim 1, characterised in that, in addition to the chronology of the variations, their relative time relations and/or the respective kind of the variations and/or the respective degree of the variations are also taken into account in the comparison of the stored desired sequence with the actually detected variation sequence.
3. An apparatus in accordance with one of claims 1 or 2, characterised in that only one single detection signal, in particular a detection signal dependent on a variation with a comparatively high degree of variation, can be triggered per unit (10).
4. An apparatus in accordance with any one of the claims 1 to 3, characterised in that a delay member (9) is provided for the triggering of the detection signal with an adjustable or a constant time delay after recognition of the agreement between the stored desired sequence and the actually detected variation sequence.
5. An apparatus in accordance with any one of the preceding claims, characterised in that the sensor (4) is made as a contrast scanner whose transmission colour is variable in dependence on the variations to be detected during the scanning of each unit (10) for the achievement of a respective maximum contrast value.
6. An apparatus in accordance with any one of the preceding claims, characterised in that the web (1) is a paper web which is in particular printed.
7. An apparatus in accordance with any one of the preceding claims, characterised in that a cutting procedure can be triggered in dependence on the detection signal.
8. A method for the recognition of sequential units (10) of an endless web (1) present in a conveying process having a sensor (4) which detects properties of the web (1) varying along the web (1), wherein variations in the colour, in the contrast, in the reflectivity and/or in other surface properties of the web (1) are detected which repeat in sequential units (10), in particular in all sequential units,
   characterised in that
   the sensor (4) detects the sequence of a plurality of variations in the web properties differing from one another for each unit (10) to be recognised;
   in that a desired chronological sequence of the variations to be detected per unit (10) is stored in a store (8); and
   in that an evaluation unit (6) compares the actually chronologically detected variation sequence with the desired sequence and triggers a detection signal related to a recognised unit (10) on agreement.

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