BACKGROUND OF THE INVENTION

Field of the invention

The invention generally relates to conveyor and transport systems. In particular, the invention relates to a transport system for sheet material including but not limited to banknotes and the like.

Description of Related Art

The position of each sheet in a transport system shall be accurately adjusted to deliver sheets with needed positioning precision.

Widely used in the art are transport systems using flat belts, round belts rollers and their combinations. However, most of them are not appropriate for adjusting sheet material position across transport direction as well as its rotational position. Belt and roller transport systems of this type provide rather low accuracy for transportation of such sheet material and low possibilities for adjusting positions of the sheets.

US 4,855,607 describes a system for transportation paper envelopes driven between drive rollers and spring biased pinch rollers. The speed of each drive roller is adjustable, so that the position of each envelope is adjusted by varying the speed of drive rollers.

However, the fact that drive rollers are used for the adjustment means that an envelope can only be adjusted within a limited angle range. In fact, to increase this angle the speed difference between the drive rollers shall be increased. A roller has a certain area of contact with a transported sheet, and considerable speed difference between adjacent rollers may obviously lead to deflection of the transported sheet between the contact areas of the rollers. This may lead to inaccurate adjusting or even jamming the sheet. A relatively small number of rollers in US 4,855,607 makes this risk even higher.

Also known is a belt transport system for transporting sheets, the system including balls supported by a frame positioned above the belt, drive rollers and idler rollers (US 6,650,865). Balls and rollers in combination with each other adjust the position of the sheets. Here, as in US 4,855,607, the sheets can only be adjusted within a limited (however, slightly wider) angle range. The angle range is wider because more rollers are used. This transport system, however, cannot provide accurate adjustment if the transported sheet material is dirty or has defects.

Some of mentioned drawbacks were eliminated in a transport system known from US 5,120,290 in which sheet material is moved between a drive wheel and a steel ball retained in a cage. The transportation of the material can be interrupted when the ball is lifted by a coil positioned above the ball and can be resumed when the ball is dropped. The direction of transportation is defined by an alignment rail. However, deflections of sheet material can occur in such system because a wheel (having a relatively large contact area) is used as a drive. Moreover, sheet material can not be rotated such it has another direction of movement.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a transport system for sheet material which does not introduce noticeable deflections into the movement of sheet material. Further, such transport system shall accurately transport any kind of sheet material and shall adjust sheet material by any angle while being a small-scale system.

Accordingly, a transport system for sheet material is provided which comprises a first positioning means for positioning balls and a retaining means, wherein the positioning means together with the retaining means form therebetween a passage for transporting sheet material. The first positioning means includes first cells and wherein each first cell has a first ball received therein with a gap, each first cell is constructed to be at least partly open on its side facing the passage such that the first ball can project out of the first cell towards the passage and engage the sheet material in the passage. Each first cell is provided with a drive, and the drives in the first cells are controllable by a control unit. The drives are configured to rotate the first balls under the control of the control unit, and the retaining means comprises a second positioning means for positioning balls. The second positioning means includes second cells, wherein each second cell has a second ball received therein with a gap and each second cell is constructed to be at least partly open on its side facing the passage such that the second ball can project out of the cell towards the passage and engage the sheet material in the passage. Using balls for sheet transportation has made it possible to increase accuracy for transportation because the forces arising when balls and sheet material engage with each other are applied to multiple areas of engagement and can have different directions and values. To achieve the above effect, the balls are received in the cells in such way that they can be rotated in any direction, thus sheet material can be also rotated by any angle.

According to an embodiment of the invention the drive in each cell is configured to rotate the first ball in different directions and to rotate the first balls with any rate within a predetermined range.

According to an embodiment of the invention the control unit is configured such that the drives in at least two cells can simultaneously rotate respective first balls in different directions and with different rates.

In this manner it is possible to perform independent movement of at least two first balls that can help to remove initial deflections or deflections in the process of transportation as soon as they occur under the control of the control unit. Also sheet material can be rotated by any angle while keeping small dimensions of the transport system.

According to another embodiment of the invention the drive in the first cell is configured to shift the first ball between the position in which the ball projects out of the cell and the position in which the ball is removed into the cell.

Preferably the control unit is configured such that the drives can simultaneously keep at least two first balls in respective first cells in different positions.

According to another embodiment the first balls comprise permanent magnetic balls, and the drive of each cell comprises at least two coils at least partly enclosing the first ball. By this means the first balls are precisely driven by electromagnetic fields generated by electromagnetic drives.

According to another embodiment the drive of each cell comprises one of an induction motor, piezoelectric actuators, pneumatic motor, hydraulic motor and electrostatic motor.

According to another embodiment a transport system further comprises a first guiding means and a second guiding means which are located between the first and the second positioning means, wherein the first guiding means has openings which correspond to the positions of first balls and allow engagement of first balls and the sheet material in the passage, and the second guiding means has openings which correspond to the positions of second balls and allow engagement of second balls and the sheet material in the passage. The guiding means being additional supportive elements in the passage make the transportation of sheet material more accurate.

According to further embodiment the first and the second guiding means are configured to adjust the height of the passage for transporting sheet material in accordance with the thickness of the sheet material. Such adjustment helps to reduce deflections and improve accuracy of the transportation.

According to another embodiment the surface of at least two first balls has different micropattern or different coating.

According to another embodiment adjacent first cells are equally spaced.

According to another embodiment at least two first cells are unequally spaced.

According to another embodiment at least one second cell is arranged according to a different pattern than arranging patterns of any of the first cells.

According to another embodiment at least one of the second cells is provided with a drive being controllable by the control unit.

Advantageously the sheet material comprises banknotes.

According to a still another embodiment a transport system further comprises optical sensors configured to generate signals defining locations and inclinations of pieces of sheet material transporting in the passage and send these signals to the control unit.

Optical sensors provide accurate performance of the transport system and verification of adjustment of sheet material.

Further aspects and features of the present invention can be appreciated from the appended drawings and the written description.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a side schematic view of a transport system for sheet material according to one of the embodiments.

Fig 2 shows an enlarged schematic side view of a transport system of Fig. 1.

Figs 3-8 illustrate the stages of adjusting the position of sheet material by a transport system according to another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transport system 1 for sheet material (see Fig. 1 ) is used for transporting sheet material 2 along shown direction of movement. According to this embodiment a passage for transporting sheet material 2 is formed between two positioning plates 3, 4 and a positioning plate 5. Positioning plates 3, 4 include a number of first cells 8 and the positioning plate 5 includes a number of second cells 9 opposing first cells 8; however, in other embodiments the first cells may be arranged according to a pattern different from that of the second cells. Each first cell has a first ball 10 received therein with a gap such that the first balls 10 can engage with the sheet material 2 in the passage the sheet material 2. In a similar manner, every second cell 9 has a second ball 11 received in it with a gap such that second balls 1 1 can engage with a sheet material in the passage. According to other embodiments the first cell and/or the second cell may have a plurality of first balls and/or a plurality of second balls, accordingly, of the same size or different sizes one of which engages with a sheet material while others provide the function, for example, of supporting, bearing or positioning the engaging ball. Each first ball 10 can be rotated in any direction and with any rate within given range by the drive provided for each first cell 8 (shown as part of each cell 8) and by this means each ball 10 can move the sheet material 2 in the passage by the friction force.

The drives in the first cells 8 are controlled by a control unit (not shown). In another embodiment some of the second balls may also be provided each with a drive controlled with the control unit. In this embodiment the drive of each first cell 8 is defined as two coils at least partly enclosing the first ball 10 which is made of a permanent magnetic material. In another embodiment an induction motor principle is used as a drive of each first cell, in this case each first ball is used as a rotor of the appropriate indication motor so that it can freely rotate. Piezoelectric actuators can also be employed as drives, and then each first ball should be connected to the appropriate piezoelectric actuators in such way the ball can rotate. Besides, each second cell can be also provided with a drive controlled by the control unit which is analogous to the type of drive provided for each first cell.

Two guiding plates 6, 7 are located between positioning plates 3, 4, 5 and provide more accurate transportation. Plates 6, 7 have corresponding openings which allow the engagements of first and second balls 10, 11 with sheet material 2. According to another embodiment guiding plates 6, 7 can also adjust the height of the passage in response to the thickness of sheet material. Moreover, plates 6, 7 may represent geometric body with a planar, cylindrical, conical or complex working surface with a solid structure or a grid structure. The cells 8, 9 have a spherical form, but in other embodiments they may have, for example, a cylindrical form, a form of a right parallelepiped, or another form such that the balls 10 can be removed into the cells 8 under the action of respective drive so that the balls 10 do not engage with sheet material. In this case, if required according to the type of sheet material or its amount part of the balls 10 can be removed into cells 8 while remaining part of the balls 10 engage with sheet material.

The adjacent first cells 8 are spaced equally but they also may have not uniform distribution in the positioning plates. For example, the positioning plates have a form of a geometrical figure having an axis parallel to the direction of transporting sheet material; then most of the first cells can be placed along this axis. Alternatively, first cells can be placed along the edges of such plate and spaced from these edges by less than half width of this plate. Such arrangement is useful when sheet material is consisted of large amounts of small pieces, for example, banknotes

The first balls 10 of the embodiment shown in Fig. 2 have the surface with a micropattern that allows necessary friction force between the balls 10 and sheet material 2. According to other embodiments each ball 10 may have a special coating, such as nanoparticles based coating, or a frictional material based coating such as electrically conductive silicone rubber. Yet, in other embodiments at least two first balls 10 can have different micropattern or different coating. A micropattern or a coating can increase the friction force when the balls and sheet material engage with each other; consequently it makes transportation of sheet material more accurate.

The transport system may also include static electricity removing means that preferably represents antistatic brushes placed for example at the beginning of the passage for transportation across it. These brushes can significantly decrease undesirable effects caused by static electricity.

According to the embodiment which operation is illustrated on Figs 3-5 a transport system comprises optical sensors that are configured to send signals to the control unit which define positions and inclinations of pieces of sheet material being transported in the passage. In this embodiment the drives represent electromagnetic coils, first balls are made of permanent magnetic material and the control unit is configured such that the drives can simultaneously rotate respective first balls in at least two first cells in different directions and can simultaneously rotate respective first balls with different rates.

Fig 3 represents the first stage of adjusting of disoriented piece of sheet material that is represented in this embodiment by a banknote (BN). As schematically shown by arrows all first balls are rotated by corresponding drives in one direction and at the same rate. During this stage the position of a banknote is analyzed by the optical sensors which generate signals defining the orientation of the banknote in the passage. Further, these signals are processed in the control unit.

Fig 4 shows the second stage of adjusting. The control unit controls the drives of respective cells in such way that the drives generate electromagnetic fields to rotate part of the first balls to the required directions and with the required rates. In this way the orientation of the banknote is corrected.

Fig 5 represents the final stage of adjusting where the directions and rates of the part of the balls which has been changed for correction of the banknote orientation are returned by the control unit to their initial values. All first balls rotate in one direction at the same rate and the banknote with corrected orientation is moved in the passage.

Similarly, sheet material can be rotated 90° or 180° to change orientation of its transporting. Alternatively, sheet material movement direction can be changed without rotating the sheet material by simultaneously changing the rotation direction of balls. Furthermore, sheet material movement direction can be changed simultaneously with rotating the sheet material.

Figs 6-8 illustrate another function of transport system where one sheet of material is moved across transport direction during transportation. This adjustment can be combined with angle adjustment shown on Figs 3-5.

It shall be noted that the construction of the transport system provides far less dimensions against known transport systems with same functions.

This invention is not limited to the specific embodiments disclosed herein which is intended to be illustrative and it covers all modifications and alternatives coming within the scope and spirit of the invention as defined in the attached claims.