EP1421022B1 - Method and device for identifying double feeds - Google Patents

Abstract

The invention relates to a method and a device for identifying overlap during the successive transport of flat mail in a double belt system. After edges have been detected on both sides of the transport path and after the distances between the detected edges and the respective guiding front edge measured by a light barrier have been determined, both sides of the longitudinal sides of the mail are acted upon with different transport speeds, ensuring that the minimum gaps are maintained. The distances between the edges and the guiding front edge are then re-measured. A double feed is detected if there is a change in distance.

Description

The invention relates to a method and an arrangement for Recognition of double copies according to the preambles of the claims 1 and 6.

There is a problem with singulation devices in so-called double deduction errors resulting from that in addition to being deducted from a pile Shipment another shipment is deducted. In distribution systems for flat shipments are the unrecognized double prints Of particular importance, as these are the miscalculation rate by read errors of the automatic address recognition increase, but also a shipment traffic jam with consignment destruction can result.

In a known solution are movable consignment parts temporarily deflected perpendicular to the conveyor. By Evaluation of the Rückschnellverhaltens the broadcasts is then the presence of overlapped broadcasts detected (EP 0 650 911 B1). Because a different offset of the overlapped Shipments, the deflection must be both broadcast front side as well as on the back of the broadcast, what increased effort results. Another disadvantage is the mechanical Loading of the shipments at the deflection. One Another shortcoming of this solution is that the offset the rear edges do not fall below a minimum value (about 10 mm) may.

In another known solution, the profile of the shipment height measured and at a height jump becomes an overlap reported (DE 196 25 044 A1).

There are possibilities of overlaps of two programs, which by the o.g. Solutions can not be detected.

This is especially true for identical, congruent shipments the case. However, it is also possible that a largest Broadcast a smallest so covers that a double deduction undetected is transported further.

The present invention is therefore based on the object a method and apparatus for detecting shipment overlaps to create, with whose help the overlaps regardless of the size of the items and their position to each other be recognized.

According to the invention, this object is achieved by the features of the claims 1 and 6 solved.

• Detektieren von Kanten auf beiden Seiten des Transportpfades und Ermitteln der Abstände der detektierten Kanten von der jeweiligen führenden, mit der Lichtschranke (Li) gemessenen Vorderkante,
• Einwirken mit beidseitig unterschiedlichen Transportgeschwindigkeiten mittels Reibkraft auf die freien Längsseiten der vereinzelten Sendungen in einem Transportabschnitt zur Sendungsverschiebung nach der Kantendetektion, wobei die Wahl der differierenden Transportgeschwindigkeiten so erfolgt, dass bei einer Überlappung die Sendungen so zueinander verschoben werden würden, dass die Mindestlücken nicht unterschritten werden, wobei die Einwirklängen und - zeitpunkte so gewählt sind, dass an jeder Seite immer nur eine Sendung gefasst wird,
• Ermitteln der Kanten auf beiden Sendungsseiten, der führenden Vorderkanten und der Abstände der Kanten von der jeweiligen führenden Vorderkante noch einmal nach der Verschiebung der Sendungen zueinander und Detektieren einer Überlappung bei mindestens einem gegenüber den ersten Messungen veränderten Abstand zwischen den einander entsprechenden Kanten und der jeweiligen führenden Vorderkante oder zusätzlichen Kanten.

After the determination of the leading and trailing edges of the consignments and the consignment gaps by means of light barriers, the following steps are carried out with the aid of the arrangement:

• Detecting edges on both sides of the transport path and determining the distances of the detected edges from the respective leading edge measured with the light barrier (Li),
• Acting on both sides with different transport speeds by means of frictional force on the free longitudinal sides of the individual shipments in a transport section for shipment shift after edge detection, the choice of differing transport speeds is such that in an overlap transmissions would be moved to each other so that the minimum gaps are not exceeded , the Einwirklängen and - times are chosen so that on each side only one consignment is taken,
• Determining the edges on both sides of the mail, the leading leading edges and the distances of the edges of the respective leading leading edge again after the transmission of the programs to each other and detecting an overlap at least one compared to the first measurements changed distance between the corresponding edges and the respective leading Leading edge or additional edges.

By measuring the distances of the two sides determined twice Edges from the respective front edge before and after the interaction with mutually different transport speeds by friction on the shipments and the appropriate evaluation, it is possible, on the one hand, by Tabs or viewing windows created edges of leading edges overlapping subsequent programs to distinguish and thus to avoid wrong sorting and on the other hand small, concealed behind large broadcasts shipments to recognize as overlaps and to avoid for example Subsequently remove the wrong sortings.

Thus, the removal via a points arrangement quickly and can be done safely, while the overlapped broadcasts shifted so that the necessary minimum gaps between Shipments are not undershot.

Advantageous embodiments of the invention are in the subclaims shown.

In order that individual shipments pass through the transport section for shipment shift without unwanted gap displacements, it is advantageous if one of the two transport speeds is the rated speed of the shroud system and the coefficient of friction of the driven at nominal speed means of transport is greater than the coefficient of friction of the driven with deviating speed means of transport.
In order to avoid additional stresses on the consignments when transferring them to the subsequent section of the shroud system, the speed deviating from the rated speed is brought back to the rated speed before the transfer.

It is possible to have the leading leading edges after the transport section to the shipment shift directly by means of a another photocell or indirectly from the signals of the front arranged the transport section for shipment shift Photoelectric sensor using the track clock to determine.

Thus, the relocation process low interference even with broadcasts takes place with different lengths, has the transport section to the shipment shift in an advantageous embodiment on each side of the broadcast one from the rest of the shroud system separate, controlled powered, rotating shroud with own drive. The length of the shifting shroud area, its distances to the incoming and outgoing shrouds of the shroud system are so big and the acceleration and braking is started and stopped that at an overlap the Einwirklänge the length of shortest consignment and the consignments to be processed Length spectrum while moving not in the incoming and outgoing shrouds are taken.

It is advantageous in this case to execute the control device in such a way that that an acceleration phase is only started if the first edge detected after the leading edge is the one in Transport direction last nip of the transport section has just left the shipment shift and that one Braking phase is completed before the trailing edge of the shortest to be moved to the first shipment in the transport direction Has reached terminal point.

Subsequently, the invention in an embodiment explained in more detail with reference to the drawings.

FIG 1

eine Draufsicht auf ein Deckbandsystem mit einem Transportabschnitt zur Sendungsverschiebung;

FIG 2 und 3

eine Darstellung verschiedener Überlappungsvarianten mit der Angabe, welche Sendung verschoben wird.

Show

FIG. 1

a plan view of a shroud system with a transport section for shipment shift;

FIGS. 2 and 3

a representation of different overlapping variants with the indication of which consignment is being moved.

The broadcasts are conveyed in the normal case individually one after the other with a feeding part 3 of the shroud system to the transport section for shipment shift and transported away with a laxative part 4. The deflecting roles of the shrouds are offset from each other so that the broadcasts are almost uninterrupted guided at least one side while the last clamping points K1, K2 and K3, K4 are as far away from each other to provide the necessary routes for accelerating or decelerating without while the broadcasts are still clamped in the feeding part 3 of the shroud system. At the rear portion of the feeding part there is a light barrier Li and on both sides of the transport path a measuring means La1, La2 for detecting edges. At the beginning of the discharging part 4 of the shroud system accordingly measuring means La3, La4 are arranged for detecting edges on both sides of the transport path.
The transport section for shipment shift consists of two endless, separately driven over pulleys 1.2 shrouds that pinch the items during transport. The fact that all pulleys are staggered, their storage may be rigid even with different thickness shipments, without causing jamming. The beginning and end of the shifting section is defined by the clamping points K2 and K3, ie by the first clamping on the rear incoming deflection roller 2 and the last clamping on the front outgoing deflection roller. The nominal transport speed of the shroud system in the incoming and outgoing parts has the value V0, the shroud with the guide roller 1 (in the side view, the rear shroud) runs at the speed V1 and the shroud with the guide roller 2 at the speed V2.

If there are two overlapped shipments (overlap) in the feeding part 3 of the shroud system due to a double take-off, first the leading edge of the photocell Li whose distance from the first nip is longer than the longest run is the leading leading edge (the leading edge of the leading overlapped transfer) detected. Next to it are the measuring means La1, La2 for edge detection. Before the overlapped items are therefore taken in the transport section to the shipment shift, the transmission gaps to the leading and trailing consignment, the length of the shipment and all edges are known.
This can be used to determine which of the two shrouds of the transport section has to move at which speed during the passage of these overlapped programs, so that the programs are shifted from each other so that the shifts are identifiable, but the gaps to the leading and trailing transmissions a minimum value not lower, which is necessary for trouble-free deflection in subsequent Weichenanordnungen.

In Figures 2 and 3 are examples for moving, dependent from the size and mutual location, overlapped shipments shown, being over the height of the differential speed for nominal speed, for the sake of clarity, no statements be made.

In FIG 2, the viewer from the rear broadcasts, which are driven at the speed V1, partially overlapped by the front broadcasts.
First of all, a) shows the special case that two programs of the same length are overlapped without any lateral offset. One of the two shrouds is driven at the rated speed V0 (V1) and the other at speed V2 = ΔV + V0, so that after the shift an additional edge is measured in front to identify a double trigger. It does not matter in this case, which of the two shrouds is driven at the speed deviating from V0.
The shift forward takes place on the premise that the gap to the preceding consignment does not fall below the minimum value despite the shift. At critical values, the differential speed ΔV is reduced.

In b) another special case is listed:
The shipments are very long and at the limit of the agreed permissibility. As a result of the partial overlap, the light barrier Li determines a transmission length lying above the permissibility, which can only be caused by an overlap. For this reason, a shift of the programs to each other is not necessary and both shrouds of the transport section for transmission shift are driven at the rated speed V0. In the case of c), the front small shipment, which is slightly behind the leading edge with the leading edge moved forward, since the gap to the leading broadcast is large enough. If this gap were close to the minimum gap, the speed V2 of the forward transmission would be reduced to a reduced value V2 = V0-ΔV. The program was only moved forward because the length of the small program is not known per se.

In the last two examples of FIG 2, the shift the front small consignment forward in the transport direction chosen, as this does not reduce the gaps become.

In the 3 examples are given in which the viewer from rear broadcasts are smaller than the front ones and are partially or completely covered by these.

Under a) is a the example b) of FIG 2 corresponding Special case listed, in which due to the excess the maximum length of an overlap is identified, so that a shift is not necessary.

In example b), the rear hidden letter is shifted forward by the rear shroud at the speed V1 = V0 + AV since the front gap is sufficiently large.
With a small gap, the hidden program would be shifted backwards by a reduced speed V1 = V0-ΔV of the rear shroud.
In the last examples c) and d), the rear broadcasts are shifted forward by increasing the speed of the rear shroud to V1 = V0 + ΔV since this maintains or increases the gaps.
For example, if the observer's rear shroud has a higher coefficient of friction at speed V1 to maintain defined gaps in single prints, the velocity V1 = V0 is maintained and the speed of the front shroud V2 is increased depending on the size of the mailpieces whose location to each other the size of the gaps or reduced. In order to ensure that the consignments are transported gently, a reduction or increase in the speed V2 to V0 takes place before the transfer of the consignment / s to the discharging part 4 of the shroud system.
At the beginning of the laxative part 4 of the shroud system, the edges are detected on both sides again by means of the measuring means La3, La4 for edge detection and their distances to the previously leading leading edge. If there is a deviation from the previous measurement or if an additional edge is recorded, there is an overlap. The position of the originally leading leading edge is determined in this example indirectly via the transport speed and the line cycle.

Claims (10)

1. Method of detecting overlaps in the case of flat items of mail which are transported one behind the other in a sandwich belt system, having at least one light barrier (Li) for detecting front and rear edges of the items of mail moving past it, item lengths and gaps being determined from the measurement results from said light barrier, characterized by the following steps:

   detecting edges on both sides of the transporting path and determining the spacings of the detected edges from the respective leading front edge measured by the light barrier (Li),

   following the edge detection, subjecting the free longitudinal sides of the separated items of mail to frictional force, with different transporting speeds on both sides, in a transporting segment for item displacement, the selection of the differing transporting speeds taking place such that, in the case of overlap, the items of mail would be displaced in relation to one another such that the gap dimensions do not fall below a minimum value, and the action-specific lengths and points in time being selected such that only ever one item of mail is gripped on each side,

   determining the edges on both item sides, the leading front edges and the spacings of the edges from the respective leading front edge once again following the displacement of the items of mail in relation to one another and detection of an overlap if at least one spacing between the mutually corresponding edges and the respective leading front edge or additional edges has changed in relation to the first measurements.
2. Method according to Claim 1, characterized in that one of the two transporting speeds in the transporting segment for item displacement is the nominal speed of the sandwich belt system, and the coefficient of friction of the transporting means driven at the nominal speed is greater than the coefficient of friction of the transporting means driven at a speed which differs therefrom.
3. Method according to Claim 1, characterized in that, in order to transfer the item or items of mail to the subsequent segment of the sandwich belt system, the speed which differs from the nominal speed is changed to the nominal speed.
4. Method according to Claim 1, characterized in that, downstream of the transporting segment for item displacement, the leading front edges are detected by means of a further light barrier.
5. Method according to Claim 1, characterized in that, downstream of the transporting segment for item displacement, the leading front edges are determined, at a certain location, indirectly from the signals of the light barrier arranged upstream of the transporting segment, with the aid of the known transporting speeds and of the section cycle time.
6. Arrangement for detecting overlaps in the case of flat items of mail which are transported one behind the other in a sandwich belt system, having at least one light barrier (Li) for detecting front and rear edges of the items of mail moving past it, item lengths and gaps being determined from the measurement results from said light barrier, characterized by

   a transporting segment for item displacement in the sandwich belt system with independently activable transporting means which subject the free longitudinal sides of the separated items of mail to frictional force with different transporting speeds on both sides, the action-specific lengths and points in time being selected such that only ever one item of mail is gripped on each side,

   measuring means (La1 to La4) which are arranged on both sides of the transporting path and are intended for detecting edges upstream and downstream of the transporting segment for item displacement and for determining the spacings of the detected edges from the respective leading front edge,

   a control device for activating the transporting means of the transporting segment for item displacement in dependence on the measured edges on both sides of the transporting path, on their spacings from the respective leading front edges and on the respective gaps in relation to the adjacent items of mail, such that the different speeds are of such a magnitude that the gap dimensions do not fall below a minimum value following displacement,

   an evaluation device in which the measurements taken upstream and downstream of the transporting segment for item displacement for the spacings between the mutually corresponding edges on both sides of the transporting path and the respective leading front edge are compared and, in the case of deviations or additional edges, an overlap is detected.
7. Arrangement according to Claim 6, characterized in that one of the two transporting means of the transporting segment for item displacement is driven at the nominal speed of the sandwich belt system, and in that the coefficient of friction of the transporting means driven at the nominal speed is greater than the coefficient of friction of the transporting means driven at a speed which differs therefrom.
8. Arrangement according to Claim 7, characterized in that the transporting means in the transporting segment for item displacement at the speed which differs from the nominal speed is changed to the nominal speed again prior to transfer of the respective item or items of mail to the subsequent, discharging segment of the sandwich belt system.
9. Arrangement according to Claim 8, characterized in that the transporting segment for item displacement, on each item side, has a circulating sandwich belt which is separate from the rest of the sandwich belt system, is driven in a controlled manner and has a dedicated drive, and the length of the displacing sandwich belt region, its spacings from the feeding and discharging sandwich belts (3, 4) of the sandwich belt system are of such a magnitude that, and the accelerating and braking operations are started and ended such that, in the case of overlap, the action-specific length corresponds to the length of the shortest item of mail and the items of mail in the length range which is to be processed are not gripped in the feeding and discharging sandwich belts during their displacement.
10. Arrangement according to Claim 9, characterized in that the control device is configured such that an accelerating phase is only started when the first detected edge following the front edge has just left the final clamping location (K3) of the transporting segment for item displacement, as seen in the transporting direction, and in that a braking phase is ended before the rear edge of the shortest item of mail which is to be displaced has reached the first clamping location (K2), as seen in the transporting direction.

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