A stacker for sheet objects

Field of the invention

This invention relates to a stacker for sheet objects such as banknotes.

Background

Hitherto, banknotes collected for example at a point of sale, are fed into a removable container, traditionally in the form of a lockable metal cash box, which is removable and transportable to a remote location such as an accounting office. The banknotes may be fed into the container through an apparatus which counts and validates the banknotes for authenticity. It has been proposed to replace conventional metal cash boxes by closable bags formed of plastics material that can be sealed shut for transport and opened at the accounting station. If the bags are found to be damaged on arrival at the accounting station, a visible indication is provided that the bag may have been tampered with and money removed.

Summary of the invention

Difficulties arise in providing an ordered stack of banknotes in a transportable container. EP-A-0852279 discloses apparatus for feeding banknotes into a bag formed of plastics material which has an insertion slot at its upper end through which individual banknotes are inserted to form a stack within the bag. However, a problem with this prior arrangement is that the banknotes may engage the side walls of the bag and become crumpled, and so do not readily form into an ordered stack.

According to the invention, there is provided a stacker for sheet objects, comprising a container with a base, an opening above the base, and sidewalls extending from the base to the opening, and an input feed mechanism to feed sheet objects successively into the container through the opening such that the sheet objects adopt a configuration with their major planar surfaces generally

horizontal and spaced by an air gap from all of the sidewalls, such as to free-fall towards the base and form an ordered stack thereon.

The sheet objects may comprise banknotes. The input mechanism may be configured to feed a plurality of banknotes of a predetermined denomination, with a predetermined length and width, into the container, and the base of the container is generally rectangular with length and width dimensions greater than those of the banknotes.

The container may comprise a flexible bag with no air release passageways in the sidewalls or the base, and a rigid platen on the base.

In accordance with the invention, it has been found that if sheet objects such as banknotes are fed generally horizontally into the container to a start position in which an air gap exists between all sides of the sheet objects and the adjacent sidewalls of the container, the sheet objects can free-fall towards the base without spuriously becoming attached to the sidewalls, so as to form an ordered stack.

The opening of the bag may be attached to a generally rectangular inlet frame which is removably mounted on the input feed mechanism. A lid may be provided for insertion into the inlet frame to close the opening for example when the bag becomes full of sheet objects. The bag may be attached to the frame by a tamper-evident tape.

In order to achieve reliable free-fall of the sheet objects, the width and length of the container in the horizontal dimension is preferably between 10% and 30% greater than the respective width and length dimensions of the sheet objects.

The input feed mechanism may include a body with plenum overlying the opening of the container, an inlet slot to receive the sheet objects edgewise, and

a drive mechanism to drive the sheet objects from the inlet to the plenum in a generally horizontal configuration for free-fall towards the base of the container.

The invention also includes a method of stacking sheet objects in a container with a base, an opening above the base, and sidewalls extending from the base to the opening, comprising feeding sheet objects successively into the container through the opening such that the sheet objects adopt a configuration with their major planar surfaces generally horizontal in space by an air gap from all of the sidewalls, such as to free-fall towards the base and form an ordered stack thereon.

Brief description of the drawings

In order that the invention may be more fully understood, an embodiment thereof will now be described by way of illustrative example with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a stacker in accordance with the invention;

Figure 2 is a perspective view of the stacker when assembled;

Figure 3 is an elevational view of the assembled stacker from one end; Figure 4 is a vertical sectional view of the stacker illustrating the passage of banknotes from the inlet into the bag by free-fall in order to achieve an ordered stack; and

Figure 5 is a sectional view from above of the configuration shown in Figure 4 taken along the line A-A'.

Detailed description

Referring to Figures 1, 2 and 3, the stacker comprises an input feed mechanism 1 with a body 2 having an inlet slot 3 for banknotes formed in its upper surface 4.

A container 5 in the form of a rectangular bag of plastics material has a rectangular base 6 and sidewalls 7, 8, 9, 10 that extend upwardly from the side edges of the base respectively to a bag opening 11, which is fitted over a rigid,

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rectangular inlet frame 12. The bag 5 is held in position on the frame 12 by a self-adhesive tape 13 shown configured to change colour if tampered with so as to provide a visual indication of pilfering. The frame 12 is provided with side rails 14a, 14b which are received in corresponding slots 15a, 15b on the underside of the body 2 of the feed mechanism 1.

A self latching lid 16 can be slid into the frame 12 when the container full of banknotes is to be removed from the inlet mechanism 1.

A platen 17 is provided on the upper side of the base 6 within the bag 5 in order to provide a support onto which an ordered stack of banknotes can be developed. The platen 17 is of sufficient weight to stretch the sidewalls into a generally planar, vertical configuration depending from the inlet frame 12.

Referring to Figure 4, which shows a sectional view of the stacker, the inlet feed mechanism 1 includes pinch rollers 18, 19, 20 mounted in the body 2 and driven by a motor in the body (not shown). Banknote 21 received in the slot 3 is driven from a generally vertical configuration by the pinch rollers 18, 19, 20 so as to be ejected through outlet 22 into a plenum 23 which opens onto the frame 12 and the opening 11 of the bag 5.

Banknote 24 which has just been fed from the outlet 22 into the plenum 23, is configured with its major planar surfaces configured to be generally horizontal.

As shown in Figure 4, the banknote 24 then abuts sidewall 25 of the plenum 23 and recoils in the direction of arrow 26 so as to assume a position illustrated by banknote 27. The sidewall is generally planar and upstanding to provide a clean surface from which the banknote can recoil into a generally horizontal configuration of banknote 27. By "generally horizontal" we mean that the planar surfaces of the sheet object lie closer to horizontal than vertical so that the sheet will fall with its major surfaces transversely disposed to the air flow past it, for example within + or — 15° of horizontal.

This is illustrated clearly in the plan view of Figure 5. In this configuration, the banknote 27 assumes a position generally centrally of the opening 5 of the bag with an air gap between the side edges of the sheet object 27 and each of the sidewalls 7-10. As shown in Figure 5, the sheet object 27 has a horizontal length 1 and width w. The length L and width W of bag 5 in the horizontal direction are also shown. Preferably, each of the length L and width W of the container 5 are between 10% and 30% greater than the respective width w and length 1 of the banknote 27.

Thereafter, as illustrated in Figure 4, the banknote can fall in the direction of arrow 28 downwardly into the bag 5 to form part of an ordered stack 29 of banknotes on the platen 17 that builds upwards into the bag 5 as successive banknotes enter through the input feed mechanism 1.

It has been found that the passage of air through the air gaps between the walls of the container and the side edges has a self-centering effect which causes the banknote 27 to maintain a generally horizontal configuration spaced from the sidewalls 7-10 of the bag 5 as it falls downwardly through the bag to join the ordered stack 29.

One possible non-limiting explanation is that if banknote 27 shown in Figure 5 moves to the left, towards the sidewall 7, the air gap δwl becomes smaller and the air gap δw2 between the banknote and sidewall 9 becomes larger. Thus, the airflow through air gap δwl will be restricted with the consequence that the side of the banknote adjacent air gap δw2 will sink more easily than the opposite side adjacent air gap δwl, with the result that the edge of the banknote closest to sidewall 9 will become lower than the edge of the banknote closest to sidewall 7. Gravity acting on the so inclined sheet will produce a lateral reaction force on the sheet due to its inclination, and the laterally acting force will urge the sheet towards sidewall 9 causing it to shift laterally and close the air gap δw2 slightly. Thus, airflow through airgap δw2 becomes restricted and the process repeats in

the manner described above, mutatis mutandis. This process acts to keep the pressure under the banknote equalised across its area and hence the banknote remains level and centred.

This process operates stably within a range of values for δwl, δw2 and corresponding values of δll and δ12. If the width of these air gaps is made too narrow, a Venturi effect may be created between the sheet and the most adjacent sidewall of the bag 5, which draws the banknote towards the sidewall. This may result in the banknote being turned through 90° so that it falls vertically down one of the sidewalls. However, by making the air gaps sufficiently broad, the first mentioned self-centering process dominates and so the banknotes will fall to achieve the desired ordered stack 29. Also, if the air gaps are made too large, the self-centering process may break down.

It has been found that in practice that if each of the length L and width W of the container 5 are between 10% and 30% greater than the respective width w and length 1 of banknote 27, the self-centering process described above predominates and an ordered stack 29 is achieved.

It may be that in practice, one or two banknotes will drawn by the aforementioned Venturi effect to one of the sidewalls and fall vertically but the bag is so dimensioned with sufficiently wide air gaps that this will not prevent formation of the ordered stack 29.

When the bag 5 becomes full of banknotes, the lid 16 is slid into place over the opening 11 in the frame 12. The lid 16 may include self-latching catches which can only be opened from inside the bag, to prevent tampering. The frame 12, with the lid 16 in place, is then removed from the input feed mechanism 1 and transported to a remote location where the bag is opened, e.g. an accounting station.

The bag 5 is opened by removing the tamper proof tape 13 so that the bag opening 11 can be removed from the frame 12 to provide access to the ordered stack 29 of banknotes.

The used bag 5 can then be sent for recycling. The platen 17 and frame 12 can be re-used with a new bag 5.

The tape 13 is designed to change colour when tampered with, thereby providing a clear visible indication of tampering or pilfering.

The lid 16 and/or frame 12 may be made from a material, for example a plastic, which changes colour when tampered with, thereby providing another visible indication that tampering or pilfering might have occurred.

The stacker can be used with different denominations of banknote, with different width and length dimensions w, 1 although conveniently, banknotes of the same denomination will be fed successively into the bag 5 in order to provide a stack of banknotes of the same denomination.

Many modifications and variations fall within the scope of the invention. For example, although the bag 5 has been described as a flexible plastics bag, it could also be made of rigid material or could for example be made of a fabric. Furthermore, whilst the stacker has been described by way of example for use with sheet objects in the form of banknotes, other sheet objects can be stacked with a stacker according to the invention, in particular, but not exclusively sheet objects with an attributable value such as tokens, vouchers and the like.