NL2003117C2

NL2003117C2 - Document seperator and method for the same.

Info

Publication number: NL2003117C2
Application number: NL2003117A
Authority: NL
Inventors: Freek Willem Laurens Ridder; Menno Koppen
Original assignee: Buhrs Zaandam Bv
Priority date: 2009-07-02
Filing date: 2009-07-02
Publication date: 2011-01-04
Also published as: WO2011002297A1

Description

Title: Document separator and method for the same

Field of the Invention

The present invention relates to the automated handling of large 5 volumes of documents, and more in particular, to the automated separation of individual documents from a stack of documents.

Background

Document separators, also called document feeders, serve the 10 purpose of repeatedly separating a document from a stack of documents so as to allow for the performance of subsequent actions on each individualized document. Here the term ‘document’ is to be construed broadly, and intended to include substantially flat, somewhat flexible products, such as, for example, printed matter, envelopes, sheets, magazines, brochures, leaflets, newspapers 15 etc. However, the term ‘document’ also includes stiff documents, i.e. documents that are relatively inflexible.

An exemplary application of document separators is a document wrapping line for the compilation of a bundle of mixed documents (i.e. documents of varying dimensions), such as a bundle of advertising brochures, 20 and the wrapping thereof in a sealed plastic covering. Such a document wrapping line may comprise a main conveyor lane for transporting the document bundle in the making towards a wrapping unit, with a series of document feeders disposed alongside or above the main conveyor lane for successively adding individual documents to the bundle as it passes by. Each 25 document feeder may comprise a document separator, the part of the feeder that individualizes documents from a document stack serving as the supply for document feeder.

Since the composition of a document bundle may vary per batch, a document separator is preferably capable of handling a variety of documents 30 having different dimensions and made of different materials. Particularly 2 challenging are documents that comprise multiple folded pages, possibly stapled together in the form of a booklet. The folds and/or staples in the spines of the booklets make them thicker at the spine than at the open side. Consequently, only a limited number of such booklets can be stacked on top of 5 each other before the pile starts to slide. Such booklets typically arrive from a printer in ‘compensated stacks’: stacks wherein a fixed number of booklets with the spine on one side is each time alternated with an equal number of booklets with the spine on an opposite side, so as to form a stack that is level and facilitates transport. Not all types of document separators are capable of 10 properly separating booklets from a stack. Rotary feeders, for example, which use a suction cup to pull a lead product from the stack, which product is then engaged by a gripper mounted on a rotating drum, do not handle multi-page products such as booklets well. Other document separators typically require the spines of the booklets to be aligned one way or another. This is because 15 these document separators apply a shear force to the (lead page of the) lead booklet in order to nudge it off the stack. As the booklets include several pages, chances are that a shear force, especially when exerted in a direction towards the spine of a booklet, will shear the pages from each other causing at least the page that is acted on to buckle, crease and possibly even tear.

20 This threat is most immediate to documents that are made of very thin and/or flexible paper. In practice, therefore, stacks of easily shearable documents are often ‘decompensated’ before they are fed into the document separator. By providing all documents with the same orientation, such that the shear force of the separator can always act in the most favorable direction, 25 the risk of damaging the documents is minimized. This approach works, but it is rather labor intensive - and therefore expensive - since the decompensation has to be carried out manually.

It is an object of the present invention to provide for a document separator and a method for separating documents from a stack, capable of 30 reliably handling compensated stacks of easily shearable documents.

3

Summary of the Invention

According to one aspect of the invention, a product separator for separating substantially flat products is provided. The product separator 5 comprises a first transport surface and a second transport surface. The first and second transport surfaces extend substantially parallel and opposite to each other, defining a product travel path having a path direction between them. The first and second transport surfaces are moveable in the path direction along the product travel path at different speeds. The product 10 separator further comprises a product supply system, configured to insert products in an overlapping manner (i.e. partially overlapping/shingled, or completely overlapping) into between the first transport surface and the second transport surface at an upstream end of the product travel path, so as to allow the transport surfaces to convey the products downstream along the 15 product travel path, and to thereby gradually decrease an overlap between successive products.

According to another aspect of the invention, a method for processing substantially flat products is provided. The method comprises providing a first transport surface and a second transport surface, the second 20 transport surface being disposed substantially parallel and opposite to the first transport surface, so as to define a product travel path having a path direction between them. The method further comprises moving the first transport surface and the second transport surface in the path direction along the product travel path at different speeds. The method also comprises 25 feeding two or more mutually overlapping products into between the first transport surface and the second transport surface at an upstream end of the product travel path, and conveying the products downstream along the product travel path, thereby allowing the transport surfaces to gradually decrease an overlap between successive products.

4

The device and method according to the present invention do not, unlike many known document separation devices and methods, attempt to separate individual documents from a stack at once. Instead, they do so in at least two stages: a first stage wherein products are successively nudged off 5 the stack, each preferably without losing overlapping contact with either the product that preceded it or with the one that will follow behind, and a second stage wherein the overlap between successive products, separated from the stack, is gradually decreased as they are conveyed downstream along a product travel path. The second stage allows a continuous separation force to 10 be applied over a longer period of time, instead of over a very short period. An optional third stage may be added at the downstream end of the product travel path to pull each most downstream product from the train of still partially overlapping (yet by then individually engageable products), so as to individualize them. It is noted that the removal of products from the stream 15 of partially overlapping documents travelling downstream the product travel path to individualize these products, is truly optional for the purpose of document singulation since a sufficiently long product travel path itself will also lead to a stream of mutually separated, non-overlapping products. The third stage may be integrated or combined with a product positioning unit or 20 action that orderly arranges the individualized products for further processing. Such a product positioning unit may thus expand the field of application of the disclosed product separator, and, for example, allow it to be employed to convert a stack of products or an irregularly shingled stream of products into a regularly arranged/shingled stream of products. The first two 25 stages of the singulation process will now be elucidated somewhat further.

In the first stage, a main surface of a substantially flat lead product of the stack may be engaged by means of a shear force that pushes it into between the first and second transport surface. As soon as the product makes frictional contact with at least one of the transport surfaces, it is not 30 only pushed but also pulled in the direction of the product travel path. The 5 pulling action of the transport surfaces in the transport direction helps to prevent buckling of the product that might result from the shearing push action. Furthermore, the lead product may preferably be pushed off the stack before it loses overlapping contact with its predecessor. Consequently, the 5 lead product is clamped between the supply stack on the one side, and the last product (i.e. the previous lead product) of a train of shingled products on the other. This clamping configuration counteracts a tendency of the product to buckle under the applied shear force. This is even more so in case the stack is oriented vertically and lead products are fed from the top, such that a lead 10 product is always carrying part of the weight of its predecessor, which weight presses down on the lead product thereby preventing its deformation.

The second stage of the separation process takes place between the two parallel transport surfaces that define the product travel path between them. To allow for an effective separation, the two transport surfaces are 15 preferably spaced apart closely, possibly such that they contact each other where no products are present between them, and that they are parted by products where present. Consequently, each inserted product typically contacts at least one of the first and the second transport surface. (This is different only for so-called multi-feeds comprising three or more products that 20 completely overlap each other, and wherein only the outer products contact the transport surfaces.) The transport surfaces both move in a downstream direction of the product travel path, yet at different speeds. The speed of the slowest transport surface is preferably close to the speed with which the lead product is nudged off the stack in the first stage, promoting a smooth 25 transition from the stack into between the transport surfaces. Due to the difference in speed between the two transport surfaces, the at least partially overlapping products clamped between them are gradually separated as they move along the product travel path. The separation process is somewhat erratic, but observed to be very effective. The erratic nature of the process 30 may be explained by the continuously changing interaction between the 6 products on the one hand and the fast- and slow-moving transport surfaces on the other. A product typically moves with the speed of one of the transport surfaces. Which one of the transport surfaces effectively dictates the speed with which a product moves along the product travel path may change any 5 time, depending on the frictional inter-product forces between the product and its neighbors, and the surface area of its main surfaces across which it is in frictional contact with either transport surface.

Because the products travel along the product travel path in an at least partially overlapping manner, typically shingled, the transition between 10 the main surfaces of successive products - viewed in the path direction - is stepwise, in particular when the products have a certain non-negligible thickness. The transport surfaces may preferably be flexible to enable them to follow the contours of the stream of mutually overlapping products, ensuring optimal frictional contact between the transport surfaces and the 15 main surfaces of the products present there between. Two-sided clamping of the products across their main surfaces by - in effect - the two transport surfaces additionally prevents buckling of the products in the direction of the product travel path.

Indeed, the force responsible for the gradual separation of the 20 products as they move along is a shear force, generated by the difference in speed between the two transport surfaces that engage the products from opposite sides. Nevertheless, the products hardly deform as a result of the shearing action. Apart from the clamping action of the transport surfaces, this is partly because the separation takes place gently, over a relatively long 25 product travel path. In a preferred embodiment, the product travel path is long enough to accommodate at least 1.5 products (i.e. the product travel path is at least 1.5 longitudinal - longitudinal being the direction of the product travel path - product dimensions long). By virtue of the minimum length, the graduality of the separation process is optimized. The gradual decrease of the 30 mutual overlap causes the products to progressively take up more path 7 length along the product travel path. To enable a continuous separation process on a finite product travel path, path length between the transport surfaces must be freed continuously, for example by periodically removing the most downstream product from the stream at the end of the product 5 travel path. Removal of downstream products may be performed before the documents have been separated from each other completely; downstream products having only a modest partial overlap with the products that follow them are individually engageable, and may therefore be quickly pulled from the stream.

10 The device and method according to the invention thus allow vulnerable shearable documents, such as for example the above-described paper booklets, to be reliably separated from a stack without damaging them. Shear forces are applied gently, and measures are taken to prevent buckling at every stage.

15 It is noted that some known document processing apparatus and methods employ two oppositely disposed, moving transport surfaces to singulate a stack or stream of documents. United States patent 6,135,341, for example, discloses a singulating apparatus including a singulator having a retard assembly and a feed assembly disposed opposite to each other along a 20 document feed path. The retard assembly and the feed assembly co-operate on a stream of documents being transported along the document feed path.

As the documents arrive at the feed assembly and the retard assembly, they are separated and transported, one by one, downstream along the document feed path. The method disclosed by US’341 is quite different from the method 25 proposed by the present invention.

The method according to the invention effects a gradual decrease in overlap between successive products by enabling two substantially parallel transport surfaces to act on the overlapping products inserted between them. In doing so, the transport surfaces move in the same direction so as to shear 30 the products relative to each other while transporting them downstream.

8

Even in case the faster transport surface does not get a (static) hold of a product, it is still transported downstream by the slower transport surface, making way for the insertion of new lead products at an upstream point of the product travel path. This is all in contrast to US’341, in which the retard 5 assembly and the feed assembly run in opposite directions, so as to prevent shingled products from being inserted between them. In US’341, the separation of products is not gradual, but to take place at a defined location and before any of the products makes contact with both assemblies. To this end, a first, upstream section of the retard assembly is disposed at an angle 10 with the feed assembly, thereby defining a wedge-shaped document entry opening. As a shingled stack of documents approaches the document entry opening, documents other than the lead document are fed upstream relative to the document feed path due to frictional contact with the retard assembly, while the lead document is fed downstream through frictional contact with 15 the feed assembly. A distinct drawback of this way of separating shingled documents is that it does not work satisfactorily for shearable documents, as is acknowledged by the publication itself (see col.7, ln.10-53). Also, the spine must be leading. The effect achieved by the present invention is thus not achieved by US’341 and similar devices and methods.

20 According to an elaboration of the invention, at least one of the transport surfaces has a dimension, transverse to the path direction, that is smaller than a transverse dimension of the products.

Using transport surfaces that are narrow relative to the products conveyed between them, especially when the transport surfaces are set up to 25 engage center portions of the products, improves control over the motion imparted to the products. Transport surfaces that extend over the full transverse dimension of the products may engage them at many different, difficultly controllable positions across their main surfaces. This may cause a product to experience a moment that works to turn it around an axis 30 perpendicular to the product travel path. Such rotation causes misalignment 9 of the respective product, which misalignment may then propagate along the product travel path and give rise to jams and damaged products. Relatively narrow transport surfaces that centrally engage the products’ main surfaces prevent this.

5 According to a further elaboration of the invention, the products are conveyed along the product travel path in a transversely bent condition relative to the path direction.

The shear forces exerted on the products by the transport surfaces act in a direction parallel to the product travel path. Bending the products in 10 a direction transverse to the direction of the shear forces/product travel path (i.e. such that (at least a directional component of) an axis of curvature extends parallel to the path direction), significantly increases their stiffness and resistance to buckling due to the shear forces. The products do not need to be bent much to achieve the advantageous stiffening effect. The bending of 15 the products may be effected in any suitable manner, and for example include the use of curved transport surfaces, product bending guides alongside the product travel path, or gravity to pull the product sides protruding sideways from between the transport surfaces downwards.

Allowing gravity to bend the products is perhaps easiest. By using 20 first and second transport surfaces that, viewed in a direction transverse to the path direction, extend substantially horizontally, and of which at least the lower one has a transverse dimension (i.e. the dimension perpendicular to the path direction of the product travel path) that is smaller than a transverse dimension of the products, gravity is enabled to bend the sideward 25 protruding edges of the products downwards, around said lower transport surface.

It is noted that the bending of products may not be restricted to the second stage of conveying the products along the product travel path, but may to the same effect be applied to the first stage during which products are 30 inserted into between the transport surfaces. To this end, the product supply 10 system of the product separator may be configured to insert the products in a transversely bent condition. In a constructionally simple yet effective embodiment, for example, this may mean that a vertically oriented stack of products is supported by a transversely bent support plate, whereby the 5 products - thus held in a bent conditions - are nudged off the top of the stack.

These and other features and advantages of the invention will be more fully understood from the following detailed description of certain embodiments of the invention, taken together with the accompanying drawings, which are meant to illustrate and not to limit the invention.

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Brief Description of the Drawings

Fig. 1 schematically illustrates a longitudinal cross-sectional view of a first embodiment of an exemplary document separator according to the present invention; 15 Fig. 2 schematically illustrates a longitudinal cross-sectional view of a second embodiment of an exemplary document separator according to the present invention;

Fig. 3 schematically illustrates a perspective view of a document separator similar to the one shown in Fig. 2; and 20 Figs. 4-6 schematically illustrate three transversal cross-sectional views of a product being conveyed in a transversely bent condition between two transport surfaces.

Detailed Description 25 Fig. 1 schematically illustrates a longitudinal cross-sectional view of a first embodiment of an exemplary product separator 1 according to the present invention. The product separator 1 includes a first belt conveyor 10, a second belt conveyor 30 disposed opposite the first belt conveyor, and a product supply system 50 that is disposed at an upstream location relative to 30 the belt conveyors 10, 30.

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In the embodiment of Fig. 1, the product supply system 50 comprises an elevator 52 that supports a stack 2 of products 4. The elevator 52 is controlled by a central control unit 8 that aligns the top of the stack 2 with the product travel path 6 extending between the first and second belt 5 conveyors 10, 30. The depicted product supply system 50 further comprises a nudge wheel 54 that rests on the top of the stack 2. The nudge wheel 54 is bearingly mounted to a motorized arm 56 that, under the control of central control unit 8, periodically moves the nudge wheel from left to right, and back. When the nudge wheel 54 is moved from left to right, its rotational motion 10 relative to the arm 56 is restrained by a freewheel assembly (not shown). Accordingly, the nudge wheel 54 makes frictional contact with the lead product 5, and pushes it sideways into between the first belt conveyor 10 and second belt conveyor 30. After such a nudge stroke the arm 56 is retracted to the left. The nudge wheel 54 thereby rolls back across the top of the stack 2, 15 from the just nudged lead product 5 onto the next, to subsequently make a new nudge stroke, and so on. A new nudge stroke is preferably initiated before the last-nudged product clears the stack 2 completely, so as to ensure an overlapping insertion of products between the belt conveyors 10, 30.

For reasons of clarity, the document separator 1 shown in Fig. 1 is 20 depicted at the start of a new batch process. Because of this, no products 4 (other than the lead product 5) are present along the product travel path 6. In full operation though, these further downstream products play an important role in preventing buckling of the lead product 5 as is it nudged off the stack. This is because the products 4 are inserted into between the first and second 25 belt conveyors 10, 30 in an overlapping manner, such that each product at least partially rests on the product following it. Accordingly, the tendency to buckle under the action of the nudge wheel 54 is effectively counteracted by the weight of the preceding product(s). This is clearly visible in Fig. 3, which shows a perspective view of an alternative embodiment of the document 30 separator 1 to be discussed below.

12

One skilled in the art will recognize that various modifications may be made to the product supply system 50 just described. The nudge wheel 54, for example, may be replaced by an elongate roller possessing a larger surface area to contact the products 4 than the nudge wheel. Such a roller may allow 5 the force required to nudge a product 5 off the stack to be distributed over a larger portion of a main surface 4b of the product, so as to minimize the chance of damaging it. Further, although a top feed assembly 50 as shown in Fig. 1 is preferable because it limits the inter-product frictional forces that must be overcome when a product 5 is nudged from the stack 2, a bottom feed 10 assembly is conceivable as well. In that case, however, the weight of the stack 2 is likely to press on the lead (bottom) product, and to be too large to allow the product to be nudged from the stack without significant shear forces. Of course, in a bottom feed assembly an elevator 52 to lift products may be omitted. As an intermediate alternative, the orientation of the stack 2 may be 15 changed. The stack 2 may, for example, extend horizontally with the products 4 having a vertical orientation. Other orientations are possible as well. It is also contemplated that the product supply system 50 may not feed products 4 off a stack 2. It may, for example, include a supply conveyor feeding an irregularly shingled stream of products into between the first and second belt 20 conveyors 10, 30.

An advantageous alternative embodiment of the product supply system 52 may comprise two elevators that are moveable upwards within a vertically extending elevator shaft. The shaft may snugly accommodate the stack of products to prevent the products from accidentally sliding relative to 25 each other, while the elevators may move the products upwards through the shaft. The elevator shaft may not be closed all-around, and may for example comprise a series of horizontally spaced, upright bars that define its cross-section (seen from above or below). Each of the elevators, in turn, may include a forklift whose fork teeth reach through the bars of the shaft to support and 30 lift a stack of products. At any one time only one of the elevators is intended 13 to support the stack of products from below. As the stack is slowly depleted due to the continuous removal of products off the top, and the stacksupporting elevator moves upwards to keep the top of the stack in alignment with the product travel path, room is created in the shaft for the other 5 elevator to bring in a new supply of products. The new supply may be inserted into the shaft from an underside thereof, and be moved upwards by the other elevator so as to connect it to the stack held by the stack-supporting elevator. Upon connection, the stack-supporting elevator may be retracted sidewards from the shaft, passing its load on to the other forklift, which at 10 that moment becomes the stack-supporting elevator. Outside of the shaft, the retracted elevator may be reloaded with a supply of the products, from which point on the cycle may start all over again. Two (or more) forklifts may thus ‘leapfrog’ over one another to provide a continuous supply of products.

The elevator 52 may comprise a support surface 53 to support and 15 lift the stack 2 of products 4. The support surface 53 may be continuous (e.g. a plate, as shown) or discontinuous, including several sub-surfaces that together define the support surface (e.g. a number of teeth of a forklift). In either situation, the support surface may be transversely bent, such that products supported by the elevator 52 are curved with respect to an axis of 20 curvature that has a least a directional component parallel to the direction in which the shear force, exerted by the nudge wheel 54, is applied to the lead product 5. In the case of the continuous support surface 53, such a situation may be achieved by bending the support surface accordingly. In the case of the discontinuous support surface, the sub-surfaces may be thought of as 25 selected portions of a transversely bent continuous support surface. The transversely bent condition of the products 4, 5 has a stiffening effect, and counteracts the tendency of the products to buckle under any shear force applied in a direction parallel to the axis of curvature.

As the lead product is nudged from the stack, it is received between 30 the first belt conveyor 10 and the second belt conveyor 30. Each of the belt 14 conveyors 10, 30 features a flexible belt 12, 32 that is wrapped around a number of pulleys 18, 38. At least one of the pulleys 18, 38 of each belt conveyor 10, 30 may be driveable by a motor (not shown) that is under the control of the central control unit 8; the other pulleys may be idler pulleys, 5 possibly spring loaded to keep the respective belt taut. The belt conveyors 10, 30 are disposed opposite to each other, on opposite sides of a product travel path 6. The immediately opposing belt runs 14, 34 of belts 12, 32 define this product travel path 6 between them. It is clear that, in the embodiment of Fig. 1, the product travel path 6 is straight and extends entirely in a path 10 direction L. Furthermore, the path direction L at the point where products 4 are inserted into between the belt runs 14, 34 is substantially parallel to the direction in which the nudge wheel 34 pushes the products 4 off the stack 2. Although this latter relation is preferably preserved, it is contemplated that the product travel path 6 may not be straight in other embodiments. The 15 product travel path 6 may for example be curved around a rotating drum, a circumference of which may provide for the first transport surface. It is further understood that, for reasons of clarity, the (vertical) distance that separates the belt runs 13 and 24 is somewhat exaggerated; in practice, the belt runs may even abut each other in case no products are present between 20 them. It is also contemplated that different embodiments of the product separator according to the invention do not include belt conveyors 10, 30, but instead different conveying devices, such as, for example series of separate, juxtaposed (driveable) wheels, to define the product travel path, and to receive the products and carry them forward.

25 The belt runs 14, 34 provide a first transport surface 16 and a second transport surface 36 respectively. Viewed in both the path direction L and the transverse direction T (i.e. the two mutually perpendicular directions that define the plane of the transport surfaces), the transport surfaces 16, 36 extend in a substantially horizontal plane. In other embodiments, however, 30 the orientation of the transport surfaces may be chosen differently.

15

The two belt conveyors 10, 30 are driven such that the belt runs 14, 34 both move in the path direction L, but at different speeds. In the embodiment of Fig. 1, the speed of the first, lower transport surface 16 is close to the speed with which a lead product 5 is nudged off the stack 2 by the 5 nudge wheel 54. This promotes a smooth, buckle-free transition of the lead product 5 from the stack 2 into between the transport surfaces 16, 36. The speed of the second, upper transport surface 36 is preferably higher than that of the first, lower transport surface 16. In some embodiments, however, the lower transport surface 16 may move faster than the upper transport surface 10 36.

Using the setup shown in Fig. 1 a continuous stream of overlapping, typically shingled products 4 may be inserted between the two transport surfaces 16, 36. As mentioned, such a stream of shingled products is clearly illustrated by Fig. 3. The continuity of the stream contributes to a high 15 throughput capacity, but is not a strict requirement otherwise. As the products 4 travel downstream along the product travel path 6, their main surfaces 4a, 4b are in contact with the transport surfaces 16, 36: the lower main surfaces 4a of the products are, at least partially, in frictional contact with the first transport surface 16, while the upper main surfaces 4b are, at 20 least partially, in frictional contact with the second transport surface 36. Due to the flexibility of the belts 12, 32, the transport surfaces 16, 36 are capable of following the step-wise transitions between the main surfaces 4a, 4b of adjacent products 4 so as to ensure optimal frictional contact between the transport surfaces 16, 36 and the main surfaces 4a, 4b of the products. As can 25 be seen in Fig. 3, the degree of mutual overlap between the inserted products 4 is relatively large at the upstream side of the product travel path 6. It is even possible that occasional multi-feeds occur: two or more products 4 having a one hundred percent overlap, incidentally fed from the stack 2 as a whole due to relatively high inter-product frictional forces. Such multi-feeds 16 do not present a problem to the apparatus and method according to the invention and may, in some embodiments, even be inserted purposefully.

Due to the difference in speed between the two transport surfaces 16, 36, which are in contact with the overlapping products 4 as described 5 above, the products are gradually separated as they move along the product travel path 6. It is conjectured that the difference between the dynamic and static friction coefficients of the transport surfaces 16, 36 plays an important role in the gradual separation process. A transport surface 16, 36 that drags a product 4 along does so under static friction; the product does not move 10 relative to that transport surface. At the same time, the product 4 will move relative to the other transport surface 16, 36 under dynamic friction.

Both the static and dynamic friction experienced by a product 4 depend on the normal contact force, i.e. the force with which a main surface 4a, 4b of a product 4 is pressed against a transport surface 16, 36. The larger the surface 15 area of a main surface 4a, 4b contacting the respective transport surface 16, 36, the larger the frictional force between the product and said transport surface is. The size of the contacting surface area is, of course, dependent on the overlap between successive products 4. Due to the continuous interaction between the transport surfaces 16, 36 and the main surfaces 4a, 4b of the 20 products 4, the amount of surface area through which a product contacts either one of the transport surfaces changes over time. Accordingly, a product 4 may at one moment favor being dragged under static friction by the first transport surface 16, while at the next it may have made sufficient areal contact with the second transport surface 36 to attach thereto, or vice versa. 25 The underlying frictional force balance for each product may tip back and forth as the products travel along the product travel path 6, causing the products 4 to move relative to each other, thereby gradually diminishing their mutual overlaps.

Referring again to Fig. 1. Downstream of the belt conveyors 10, 30 a 30 product positioning unit 70 is disposed. By the time the products 4 reach the 17 product positioning unit 70, the separation process is in a sufficiently advanced phase to ensure that possible multi-feeds have been rectified, and that the overlap between successive products 4 has become small enough to allow a most-downstream product to be quickly extracted from the stream.

5 This is what the product positioning unit 70 does. The unit 70 may comprise two rollers 72 or other rotational elements, disposed on opposite sides of the product travel path 6. The rollers 72 may be disposed at fixed mutual positions, so as to define a certain gap between them of approximately the thickness of a single product. Alternatively, at least one of the rollers 72 may 10 be (spring-) biased into contact with the other, so as to allow for a flexible gap size between them. At least one of the rollers 72 is driveable, preferably at a relatively high speed compared to the speeds of the belts 12, 32. In the embodiment of Fig. 1, both rollers 72 are driveable under the control of the central control unit 8. Extraction of products 4 from the stream of products 15 requires that the driveable rollers 72 rotate in the directions indicated in Fig. 1: clockwise for the lower roller 72 and counter-clockwise for the upper roller 72. As soon as a lead edge of a most-downstream product 4 comes into frictional contact with the rotating rollers 72, the product will be pulled into between them and be accelerated in the path direction L. The fast 20 acceleration draws the most-downstream product loose from any remaining overlap with the product following it, and effects its definitive separation from the stream.

Downstream of the product positioning unit 70, a further belt conveyor or another product handling unit may be disposed to accept the 25 individualized products for further processing. In the case of a further belt conveyor, for example, the product positioning unit 70 may arrange the individualized products in a regularly shingled manner on a belt thereof, so as to transport them to a further processing station.

The product separator 1 according to the invention may be fitted 30 with a control unit 8 that controls one or more of the product supply system 18 50, the first belt conveyor 10, the second belt conveyor 30 and the product positioning unit 70. The control unit 8 may be configured to gear the operations of these components towards one another, enabling a smooth operation of the separator 1 as a whole. To this end the control unit 8 may for 5 example provide an adjustable master clock signal, from which clock signals for driving the other components, such as the product supply system 50 and the conveyor belts 10, 30, may be derived through a fixed multiplier. Additionally, the control unit 8 may comprise a number of sensors, disposed at various locations in or around the separator 1, to provide the control unit 10 with operational information, e.g. about the number of inserted and extracted documents, the occurrence of multi-feeds, extraction timing information, normal pressure applied to the transport surfaces 16, 36, etc. The control unit 8 may further include an operator control panel through which an operator can monitor and adjust the performance of the product separator 1. It is 15 understood that conventional technology, e.g. Siemens’ SIMATIC product range, may be used to implement the control unit and its functionality.

Fig. 2 schematically illustrates a second exemplary embodiment of a product separator 1 according to the invention. Relative to the embodiment shown in Fig. 1, both the product supply system 50 and the belt conveyors 10, 20 30 have undergone some modifications. Fig. 3 depicts a perspective view of an embodiment of a product separator 1 similar to the second embodiment shown in Fig. 2, but in some more detail and in an advanced phase of operation. Both figures clearly illustrate the modifications of the second embodiment relative to the first embodiment of Fig. 1 25 The product supply system in Figs. 2 and 3 does not make use of a nudge wheel 54 that executes discrete nudge strokes to push products 5 off the top of the stack 2. Instead, the belt 32 of the second, upper belt conveyor 30 has been extended with a belt run 42 that extends up to above the top of the vertically oriented stack 2. The elevator 52 forces the top of the stack in 30 contact with this belt run 42, which provides a third transport surface 44. As 19 the second belt conveyor 30 is driven, the third transport surface 44 moves (in unison with the second transport surface 36) in the path direction L, and products 5 forced in contact with the third transport surface 44 will be successively nudged off the stack in a shingled manner. Again, the flexibility 5 of the belt 32, and hence of the belt run 42, is important. Due to its flexibility, the third transport surface 44 is able to follow the step-wise transitions between the main surfaces 4b of successive lead products 5, and thus to engage a following product before a certain preceding product is fully clear of the stack 2. This aspect is well illustrated by Fig. 3.

10 The belt conveyors 10, 30 of the embodiment of Fig. 2 have additionally been adapted to include a number of pressure pulleys 20, 40. A first series of pulleys 20 is associated with the first belt conveyor 10, such that belt run 14, and hence the first transport surface 16, is supported from below at a series of discrete points along the product travel path 6. A second 15 series of pulleys 40 is associated with the second belt conveyor 30, such that belt runs 34, 42, and hence the second transport surface 36, are pressed on from above at a series of discrete points above the stack 2 and along the product travel path 6. The pulleys in each series may be disposed equidistantly from each other, whereas the two series may be shifted relative 20 to each other in the path direction L, so that the pulleys of the first series 20 and the second series 40 are alternatingly and non-opposingly disposed along the product travel path 6, as shown in Fig. 2. Here the phrase ‘alternatingly and non-opposingly’ is intended to convey that the idea that, viewed along the path direction L, a number of pulleys 20 of the first series disposed on a first 25 side of the product travel path 6 is alternated with a number of pulleys 40 of the second series disposed on a second side of the product travel path, and so on, such that the pulleys of the first and second series do not immediately oppose each other. Along the product travel path 6, the pressure pulleys 20, 40 gently force the first and second transport surfaces 16, 36 towards each 30 other, whereby their alternating, non-opposing placement distributes the 20 overall pressing force. It has been observed that a finer distribution of the pressing force leads to more efficient separation of products. The pressing force exerted by the pulleys 20, 40 is preferably non-progressive in the sense that thicker products 4 would cause the transport surfaces 16, 36 to be 5 pressed together harder. This is because a larger normal pressing force increases the inter-product frictional forces between overlapping products 4 conveyed along the product travel path 6, and thus renders separation of these products through shearing more difficult. An alternative approach to applying normal forces between products 4 and transport surfaces 16, 36 may 10 employ vacuum belt conveyors. An advantage of using vacuum belts it that they barely affect the inter-product frictional forces. This is because they do not force overlapping products 4 onto each other, but merely suck the products against the belts (indeed often diminishing inter-product frictional forces).

15 Fig. 3 illustrates an embodiment of the document separator 1 that is similar to that shown in Fig. 2, this time in a perspective view. Some aspects illustrated by Fig. 3 have already been referred to above, but are summarized here briefly for the sake of completeness. Firstly, the figure elucidates the gradually diminishing overlap between successive products 4 20 as they travel down the product travel path 6. As can be seen, most upstream products 4 overlap with their neighbors and the transitions between the main surfaces 4a, 4b of these overlapping products are step-wise. The flexibility of belts 12 (not visible) and 32 enables them to follow these transitions, thereby promoting proper frictional contact between the main surfaces and the belts. 25 Fig. 3 also illustrates how gravity mildly bends the products 4 in a transverse direction as they are conveyed. This manner of bending the products 4 to counteract buckling is further discussed in relation to Fig. 5.

Figs. 4-6 schematically illustrate, in transverse cross-sectional views, three alternative approaches to transversely bending products 4 as 30 they are conveyed downstream along the product travel path 6. In the 21 embodiment of Fig. 4, two bending guides or rails 80 are used to bend the products 4. The bending guides 80 extend in the path direction L, parallel to the product travel path 6. For symmetry, one guide or rail is disposed on either side of the product travel path 6. The guides or rails 80 are configured 5 to engage a side portion of the products 4 so as to bend them around an axis of curvature C, parallel to the path direction L. To minimize friction between the products 4 and the guides 80, the guides may for example be provided with small, interfacing rollers (not shown). In the embodiment of Fig. 5, gravity is used to bend the products 4. This is made possible by using first 10 and second transport surfaces 16, 36 that, viewed in the transverse direction T, extend substantially horizontally, while at least the first, lower transport surface 16 has a transverse dimension that is smaller than a transverse dimension of the products 4. The products 4 thus protrude from between the transport surfaces 16, 36, which allows gravity to bend them transversely, 15 relative to an axis of curvature C. In the embodiment of Fig. 6, the transport surfaces 16, 36 themselves are curved relative to an axis of curvature C. Consequently, the products 4 clamped and conveyed between them are too. It will be appreciated that the illustrated manners of bending products are merely exemplary, and that other approaches may be implemented to the 20 same effect.

Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying drawings, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by 25 those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present 30 invention. Thus, the appearances of the phrases "in one embodiment" or "in 22 an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, it is noted that particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new, not 5 explicitly described embodiments.

23

List of elements 1 product separator 2 stack of products 5 4 product 4a,b first, lower (a) and second, upper (b) main surface of product 5 lead product of stack 6 product travel path 8 central control unit 10 10 first belt conveyor 12 belt of first belt conveyor 14 belt run defining first transport surface 16 first transport surface 15 18 pulleys of first belt conveyor 20 pressure force distributing pulleys 30 second belt conveyor 32 belt of second belt conveyor 20 34 belt run defining second transport surface 36 second transport surface 38 pulleys of second belt conveyor 40 pressure force distributing pulleys 42 belt run defining third transport surface 25 44 third transport surface 50 product supply system 52 elevator 53 elevator support surface 30 54 nudge wheel 56 motorized arm 70 product positioning unit 72 wheel or roller 35 80 product bending guide C axis of curvature L path direction 40 T transverse direction relative to path direction

Claims

A product separator (1) for separating substantially flat products (4, 5), such as for example documents, comprising: - a first transport surface (16) and a second transport surface (36), the first and second transport surfaces extend substantially parallel to and opposite each other such that they define between them a product path (6) with a path direction (L), and wherein the first transport surface and the second transport surface are movable along the product path in mutually different speeds in the path direction; and - a product supply system (50), arranged for inputting products in an overlapping manner between the first transport surface and the second transport surface at an upstream end of the product path, in order to enable the transport surfaces to carry the products downstream along the product path , and thereby gradually reducing an overlap between successive products. 20

The product separator of claim 1, wherein a first belt conveyor (10) provides the first conveyor surface (16), and wherein a second belt conveyor (30) provides the second conveyor surface (36). 25

The product separator according to claim 1 or 2, wherein the product path (6) is sufficiently long to receive at least 1.5 products (4).

The product separator according to any of the preceding claims, wherein the product supply system (50) is adapted to introduce the products (4) in a state bent transversely to the path direction (L).

The product separator according to any of the preceding claims, wherein at least one of the conveying surfaces (16, 36) has a dimension, transverse to the path direction (L), which is smaller than a transverse dimension of the products (4).

The product separator according to any of the preceding claims, wherein the first and second conveying surfaces (16, 36), viewed in a direction transverse to the path direction (L), extend substantially horizontally.

7. The product separator according to any one of the preceding claims, adapted for transporting products (4) along the product path (6) in a state bent transversely of the path direction (L).

8. The product separator according to any of the preceding claims, wherein at least one of the first conveying surface (16) and the second conveying surface (36) is curved transversely of the path direction (L).

9. The product separator according to any one of the preceding claims, further comprising at least one product-bending guide (80), placed along the product path (6) and adapted to engage the products (4) that are between the transport surfaces (16, 36). ) are transported to bend them transversely to the path direction (L).

The product separator according to any of the preceding claims, wherein the product supply system (50) comprises a top supply assembly that supplies products from the top of a substantially vertically oriented stack (2).

11. The product separator according to claims 2, 6 and 10, wherein the second conveying surface (36) is placed above the first conveying surface (16), the second belt conveyor (30) further providing a third conveying surface (44) which is substantially in extending from the second conveying surface (36) and positioned above the vertically oriented stack (2), and wherein the product supply system (50) is adapted to continuously position the stack (2) such that an upper side of the stack in is in contact with said third transport surface, which surface is adapted to move in accordance with the second transport surface. 15

The product separator according to any of the preceding claims, further comprising: - a first series of rollers (20) associated with the first belt conveyor (10); and - a second series of rollers (40) associated with the second belt conveyor (30); wherein the first and second series of rollers are adapted to drive the first conveying surface (16) and the second conveying surface (26) towards each other, the rollers of the first series and the rollers of the second series non-opposite along the product path (6) are placed.

The product separator according to any of the preceding claims, further comprising a product positioning unit (70) disposed at a downstream end of the product path (6) and comprising two roller wheels 30 (72), said roller wheels mutually parallel and on either side of the product path and wherein each roller wheel has an axis of rotation extending substantially transversely to the path direction (L) so that a product (4) that reaches the downstream end of the product path can be received between the roller wheels, and wherein at least one of the roller wheels 5 is drivable to accelerate a received product.

The product separator of at least claim 2, wherein at least one of the first belt conveyor (10) and the second belt conveyor (30) is a vacuum belt conveyor. 10

The product separator according to any of the preceding claims, wherein the operation of one or more of the product supply system (50), the first belt conveyor (10), the second belt conveyor (30) and the product positioning unit (70) is controlled by a control unit (8), which is arranged to coordinate their operation.

A method for processing substantially flat products (4), such as, for example, documents, comprising: 20. providing a first transport surface (16); - providing a second transport surface (36) which is placed substantially parallel to and opposite the first surface in order to define between them a product path (6) with a path direction (L); 25. moving the first conveying surface and the second conveying surface at mutually different speeds in the path direction (L) along the product path; - introducing two or more mutually overlapping products between the first transport surface and the second transport surface at an upstream end of the product path; and - transporting the products downstream along the product path, wherein the transport surfaces are possible to gradually reduce an overlap 5 between successive products.

The method of claim 16, wherein the product path (6) is long enough to accommodate at least 1.5 products (4).

The method according to claim 16 or 17, wherein the products (4) are introduced between the transport surfaces (16, 36) in a state bent transversely to the path direction (L).

19. The method according to any of claims 16-18, wherein the products (4) are transported along the product path (6) in a state bent transversely of the path direction (L).

The method according to any of claims 16-19, wherein at least one of the conveying surfaces (16, 36) has a dimension transverse to the path direction (L) that is smaller than a transverse dimension of the products (4) .

21. The method according to any of claims 16-20, wherein the first and second transport surfaces (16, 36), viewed in a direction (T) transversely of the path direction (L), extend substantially horizontally.

22. The method according to any of claims 20 and 21, wherein the lowest placed of the first and second transport surfaces (16, 36) has a dimension, transverse to the path direction (L), which is smaller than a transverse dimension of the products. (4), which makes it possible for gravity to bend the products around said lowest placed transport surface.

The method according to any of claims 16-22, wherein introducing two or more mutually overlapping products (4) comprises: - providing a vertically oriented stack (2) of substantially flat products; - continuously positioning the stack such that an upper product (5) is in line with the product path (6), which is defined by the first and the second transport surface (16, 36); and - repeatedly engaging the upper product and introducing it between the first conveying surface (16) and the second conveying surface (36). 15

The method of claim 23, wherein a third conveying surface (44) is provided above the vertically oriented stack (2), one wherein the stack is continuously positioned such that the top product (5) of the stack is driven into contact with the third transport surface (44), which third transport surface is moved in the path direction (L) of the product path (6) to introduce the upper product between the first (16) and the second (36) transport surface.

The method according to any of claims 16-24, further comprising: - driving the first transport surface (36) towards the second transport surface (16) at a first series of positions along the product path (6); and - driving the second surface towards the first conveying surface at a second series of positions along the product path, wherein the positions of the first series on the one hand and the positions of the second series on the other are not opposite each other along the product path.

The method according to any of claims 16-25, further comprising: - engaging a product (4) that has been led to a downstream end of the product path (6), and accelerating the engaged product to withdrawal from a remaining overlap with a subsequent product, whereby the product seized is individualized.

The method of claim 26, further comprising: - rearranging the engaged and individualized products (4) according to a predetermined arrangement. 15

The method of any one of claims 16 to 27, wherein at least one of the first, second and third transport surfaces (16, 36, 44) is flexible.

The method of any one of claims 16 to 28, wherein at least one of the first conveying surface (10) and the second conveying surface (30) is provided with perforations, and wherein a vacuum is applied to the perforations to produce products (4) suck against said at least one conveying surface.