AN APPARATUS AND A METHOD FOR MAINTAINING SURFACE SMOOTHNESS OF A DOCUMENT DURING HIGH SPEED PROCESSING

Abstract

 The invention relates to an apparatus (100) for a document sorting machine, in particular a banknote sorting machine, comprising: an inspecting plate (1) of a sensor unit and a conveyor belt-free and/or roller-free gap, the belt-free and/or roller free gap being configured to accommodate the inspecting plate (1); the length of the gap being substantially shorter than the length of the document, the apparatus (100) further comprising at least one hollow air guide between an outlet of a valve and an outlet of the air guide at an end of the air guide opposite to the outlet of the valve for blowing air on a document moving along the inspecting plate (1), wherein the cross-sectional area of the air guide remains either constant or increases between the outlet of the valve towards and until the outlet of the air guide including the cross-sectional area of the outlet of the air guide. The invention also relates to a document sorting machine and methods.

Description

FIELD OF INVENTION

[0001] The invention relates to an apparatus and a method for maintaining surface smoothness of a document during high speed processing.

BACKGROUND

[0002] Automated, high- volume currency processing is an important technical field affecting numerous aspects of the distribution, collection, and accounting of paper currency. Currency processing presents unique labor task issues that are intertwined with security considerations. Currency processing requires numerous individual tasks, for example: the collection of single notes by a cashier or bank teller, the accounting of individual commercial deposits or bank teller pay-in accounts, the assimilation and shipment of individual deposits or accounts to a central processing facility, the handling and accounting of a currency shipment after it arrives at a processing facility, and the processing of individual accounts through automated processing machines. Any step in the process that can be automated, thereby eliminating the need for a human labor task, saves both the labor requirements for processing currency and increases the security of the entire process. Security is increased when instituting automated processes by eliminating opportunities for theft, inadvertent loss, or mishandling of currency and increasing accounting accuracy.

[0003] A highly automated, high-volume processing system is essential to numerous levels of currency distribution and collection networks. Several designs of high-volume processing machines are available in the prior art and used by such varied interests as national central banks, independent currency transporting companies, currency printing facilities, and individual banks. In general, currency processing machines utilize a conveyer system which transports individual notes past a series of detectors.

[0004] One of the major challenges in high-volume banknote sorting and processing consists in detecting properties of the banknote, as for example images of the banknote in order determine their authenticity or fitness. In order to obtain these properties, the banknotes have to be flat during detection/sensing. However, if the banknotes are held between conveyor belts, parts of the banknote are hidden and cannot be analyzed.

[0005] Various concepts have been developed in order to keep the banknotes flat without conveyor belts. In one of these concepts, the conveyor belts are omitted on one side while the banknote is sucked to the opposite conveyor or a plate. This, however, allows only taking images from one side of the banknote.

[0006] EP 2 081 862 A2 discloses a banknote processing machine that relies on inertia or centrifugal forces for keeping the banknotes flat during inspection. A curved document guide is used to generate the inertia/centrifugal force. However, this solution requires too much space.

SUMMARY

[0007] It is an object of the present invention to provide an apparatus and methods for a valuable or security document or banknote processing machine having reduced size and costs.

[0008] According to an aspect, an apparatus for a document sorting machine, in particular for a banknote sorting machine is provided. The invention also provides a document sorting machine, in particular a banknote sorting machine comprising the apparatus. The apparatus can also be regarded a module.

[0009] The apparatus for a document sorting machine, in particular the banknote sorting machine can comprise an inspecting plate of a sensor unit and a conveyor belt-free and/or roller-free gap. The belt-free gap and/or roller-free gap can be configured to accommodate the inspecting plate. The length of the gap can be substantially shorter than the length of the document.

[0010] The apparatus or module can comprise a first conveyor unit for passing the document to the inspecting plate and a second conveyor unit for receiving the document. The area of the inspecting plate is conveyor belt free.

[0011] As per definition, the document, while moving through the apparatus and over the document guiding surface, has a leading edge and a trailing edge in the direction of movement of the document.

[0012] The document can advantageously always be held by at least one of the conveyor units or rollers while moving along the gap and the inspecting plate. The conveyor units and/or rollers are arranged outside the gap or, in other words, outside the upper surface and area of the inspecting plate. The document can always be driven by at least one of the conveyor and/or roller units.

[0013] In an aspect, the document is substantially held by the first and the second conveyor unit and/or roller unit while moving over the inspecting plate. The document may then be pushed by the first conveyor and/or roller unit towards the inspection plate and/or pulled by the second conveyor and/or roller unit away from the inspection plate.

[0014] In the context of the present specification a conveyor unit can generally also be a roller unit without any belt. Likewise, the belt-free gap can always also be considered a roller-free gap.

[0015] The first conveyor unit only releases the document when the trailing edge of the document leaves the first suction block and/or when the trailing edge enters the inspecting plate (belt-free gap). The second conveyor unit is configured such that it pulls (moves, grabs) the document when the leading edge of the document leaves the inspecting plate (belt-fee gap) and/or when the leading edge of the document enters the second suction block.

[0016] The conveyor units (first and/or second conveyor unit) can be of a one-belt, two-belts or three-belts type. The document may therefore be moved through the processing machine between two (one-belt type), four (two-belts type) or six (three-belts type) conveyor belts. The respective conveyor belt systems are known in the art. The aspects and embodiments of the invention also apply to systems using only rollers.

[0017] The apparatus can further comprise a hollow air guide (or fluid guide). The hollow air guide can be arranged between an outlet of a valve and a document guiding surface of the inspecting plate, such that an outlet of the air guide at an end of the air guide opposite to the outlet of the valve is in a position to blow air or fluid on a document moving along the inspecting plate.

[0018] A cross-sectional area and/or diameter of the air guide can remain either constant or can increase from the outlet of the valve towards and until the outlet of the air guide, i.e. in the direction of the air flow (downstream). In other terms, the cross-sectional area and/or diameter of the air guide is monotonically increasing (including remaining constant) in the direction of the air flow.

[0019] In particular, the cross sectional area of the outlet of the air guide should not be smaller or narrower than the cross-sectional area at any point upstream. According to this aspect, it has been recognized that it is crucial that the cross-sectional area or the diameter of an air guide is not decreased or narrowed over the entire length of the air guide in the direction of the air flow (downstream).

[0020] Air guides according to the prior art have portions where a cross-sectional area of the air guide is widened and subsequently narrowed in the direction of the air flow. This can mainly entail two negative effects: the speed of the air or the fluid propagating through the air guide is slowed down and reflections or even resonance can occur, in particular when the air or fluid is supplied in pulses. If, however, an air guide is configured according to the aspects of the invention, the air or fluid supplied at an outlet of the air guide can be much better adapted and tailored to various kinds of applications. The speed of the air can then be maintained along the entire air guide.

[0021] Advantageously, the valve is a high speed valve. The term "high speed" means that the valve can switch within a very short time. More specifically, such a high speed valve can be configured to switch within 1 ms or less and at a frequency of 1 kHZ or more.

[0022] The high speed valves may advantageously have the following values: a flow rate in the range of 50 to 150 L/min, a supply pressure in the range of 0.2 to 0.7 MpA, an operating frequency from 150 Hz to 1200 Hz, an ON-response time from 0.45 to 1.7 ms, an OFF-response time from 0.4 ms to 0.75 ms. The values are advantageously configured to be controlled by pulse width modulated signals (PWM) driving an internal coil of the valves in order to reach the timing performances. The high speed valves can advantageously have a service lifetime of 5 billion switching cycles.

[0023] The fast switching capacity of the high speed valve can very advantageously be used in combination with the air guide being configured according to the aspects and embodiments of the invention. Since the air guide prevents reflections or deceleration of the air, any apparatus can fully benefit from the fast switching capacity of the valves.

[0024] The apparatus can generally comprise more than one air guide. Regarding the locations of the air guides, the present specification refers to the outlets of the air guides. Since the air guides can generally have any shape (such as curved or the like) except for the diameter and/or cross sectional area that should not decrease, it is the location of the outlet(s) of the air guide(s) and direction of the air flow after having left the outlet(s) of the air guide(s) that is relevant. This air flow after having left the outlet(s) of the air guide(s) is also referred to herein as the "air flow axes".

[0025] If there is a substantially flat document guiding surface of the apparatus and/or module according to the invention, the outlets of the air guides are arranged above this document guiding surface such that any banknote or other valuable document moves between the document guiding surface and the outlet(s) of the air guide(s).

[0026] Furthermore, the outlets of the air guides can be arranged under beneath this document guiding surface. Still further the outlets of the air guides can be arranged above and under beneath this document guiding surface such that any banknote or other valuable document moves along the document guiding surface and between at least two outlets of the air guides arranged on opposite sides of the document guiding surface.

[0027] Accordingly, the outlets of air guides can generally be duplicated at the opposite side of the moving document or document guiding surface, thereby, for example substituting at least parts (or all) of the document guiding surface. The aspect provides that the friction of the moving documents on the document guiding surfaces is reduced and the speed of the documents is preserved. Furthermore, any delay can be reduced and any possible erosion of detector surfaces (i.e. erosion of the document guiding surface) can be reduced. This aspect further helps to manage the levitation of the transported documents between detector surfaces (document guiding surface and opposite surface of a sensor unit), with a symmetrical or non-symmetrical position of the trajectory of the document between them, by controlling the average force provided by each outlet of an air guide along the passing document. The trajectory may then be controlled in real time, with the feed-back of the control unit, as a fully active system. The control of each couple of valves in opposite positions can be differential. For example, the trajectory position following a track or a portion of track can be adjusted by a differential management of valves, by applying more force pressure to the front surface, and less force pressure the reverse side by using a pulse width modulation principle (conjugated or alternated). Each couple of valves can be independently managed, for example according to a feedback control principle.

[0028] Some of the plurality of outlets of the air guides can generally be arranged as a sequence one after the other in the direction of movement of a valuable document/ banknote. A line or band of a certain width in the direction of the banknote may generally be referred to as a track.

[0029] One or more air guides can be arranged such that their outlets are within a single track.

[0030] If the outlets of two air guides are arranged side by side and perpendicular to the direction of the movement of the document, the two outlets of the air guides can then be considered being located in two different tracks. The outlets of the two air guides can be located at substantially the same distance or position in moving direction of the valuable document or at different distances with respect to an input of a valuable document.

[0031] As apparent for those skilled in the art, a track may not necessarily be a strictly straight line, which means that the outlets of air guides of the same track do not need to be located on a strictly straight line, but rather within a straight band. A track may therefore be understood as a straight band in the direction of movement of the document. The air guides can generally belong to different tracks and/or can be located at different distances from an input of valuable documents (document input).

[0032] The apparatus can comprise a first air guide and a second air guide being arranged such that their outlets are located in a first position from the document input and in a second position from the document input, wherein the second position is further apart from the document input than the first position.

[0033] The outlet of the (for example first air guide and the second air guide) air guides can have a distance of 10 mm to 20 mm, in particular 15 mm or 17 mm in the moving direction of the valuable document.

[0034] The first air guide can have an angle with respect to the document guiding surface of the inspection plate of 50° to 55°, such that the air output by the first air guide is partially blown into the moving direction of the valuable document. It has turned out that such a configuration is advantageous for guiding and moving the document over the inspecting plate. In particular, the incident air supports the transport of the documents.

[0035] The outlet of the second air guide can be arranged such that the air is blown substantially normal (perpendicular) to the document guiding surface. This configuration is also advantageous for guiding the document.

[0036] The outlets of the first and the second air guide can be arranged in the same track.

[0037] There can also be a third air guide. The outlet of the third air guide can be located at a third position which is closer to the document input than the location of the outlet of the second air guide.

[0038] The third air guide can be arranged such that the air output by the third air guide has a smaller angle with respect to the document guiding surface than the second air guide, i.e. the amount of air blown into the direction of the movement of the valuable documents is greater than the amount of air in this direction provided by the second air guide.

[0039] The outputs of the first, second and third air guide can be arranged within the same track (first track).

[0040] There can further be a fourth, fifth and/or sixth air guide. The outputs of these air guides can then be arranged similar to the outputs of the first, second and third air guide, but in a second track that is different from the first track.

[0041] The outlet of a third air guide or any additional air guide can also be arranged in a middle track between a first and a second track.

[0042] The air guides can have the shape of a tube and/or the air guides can be tubes.

[0043] Generally, a separate valve can be provided for each air guide. This can further improve the performance, in particular the velocity, the energy and the delay time of the air flow and/or air pulses.

[0044] The distance between the outlet of an air guide and the guiding surface of the inspection plate can be between 5 mm, and advantageously 10 mm to 12 mm. The distance of the outlets of the air guides from the document guiding surface can vary within the same and/or different tracks and for different positions with respect to the document input.

[0045] The apparatus can further comprise a control unit configured to control the air flow by the valve. The control unit can control the valve such that the air is supplied in pulses.

[0046] The pulses can be modulated. The air flow through an air guide can be controlled such that there is an ON-cycle during which air is blown with a substantially constant pressure and/or speed and an OFF-cycle during which substantially no air is blown through the air guide. Accordingly, a duty cycle of blown air and/or pulses through the air guide can be created having a determined OFF-time and a determined ON-time.

[0047] The air flow through different air guides can be controlled differently in response to one or more detected or predetermined properties of the banknote. The modulation of the air flow can be controlled in response to one or more detected or predetermined characteristics of the banknote.

[0048] The air flow can be configured and controlled such that a position of the banknote is changed. This can be used that the valuable document is aligned or the position or orientation is adjusted during the movement of the document.

[0049] One or more light barriers can be used for detecting a banknote approaching the inspection plate and for triggering the air pulse through the air guide(s). The one or more light barriers can then be coupled to the control unit.

[0050] The apparatus can comprise a cover/housing or air chamber for removing dust, reducing noise, controlling temperature, shielding light, protecting against EMI and/or removing additional air. The cover can be made of a metallic material, in particular a electrically conducting material. The air chamber (housing) or closed room concept can generally improve the dynamic pressure on the moving documents. There can further be an input wall and a cover that close the cross section at the end of the belt-free and/or roller-free gap. This provides that the air remains between the sensor units (within the gap) and does not blow out in other directions. Using a cover in form of an air chamber or closed room according to this aspect helps to reduce the air consumption. The air chamber AC or housing can further be configured to protect against dust, reduce noise, control temperature, shield light, and/or protect against EMI.

[0051] In case of an at least substantially circular cross sectional area of the air guide, the diameter of an air guide can be 2.6 mm, 2 to 3 mm, 2 to 5 mm.

[0052] The air guide can be made of metal and in particular of copper. Plastic is advantageously avoid due to potential ESD problems.

[0053] At least one air guide can comprise a branching. The branching can be conceived such that there is one incoming air guide and two output air guides. An angle between the two output air guides (or any pair of adjacent outputs) can be less than 180°.

[0054] The apparatus or module can comprise: a first suction block (or air sucking block), a second suction block (or air sucking block), a first conveyor unit for passing the document to and/or along the first suction block and a second conveyor unit for receiving the document at second suction block and/or passing the document along the second suction block.

[0055] The apparatus can further comprise a sensor unit for determining properties of the document.

[0056] The apparatus can also comprise a processing unit for processing data from the sensor unit. The processing unit may include the control unit as previously described. However, the control unit may be substantially independent from the processing unit.

[0057] The apparatus can be a stand-alone system (module) including a control unit for performing the modulation of the air through the air guide(s).

[0058] In an aspect, the belt-free gap can be located between the first suction block and the second suction block. The first conveyor unit and the first suction block can be arranged on one side of the belt-free gap and the second suction block and the second conveyor unit can be arranged on a second side of the belt-free gap (in the direction of the movement of the document). In other words, they are arranged on opposite sides of the belt-free gap (or inspecting plate).

[0059] The belt-free gap can be configured to accommodate the inspecting plate of a sensor unit. The length of the gap can be substantially shorter than the length of the document. This implies that the length of the inspection plate in the direction of the movement of the document is also substantially shorter than the document.

[0060] The air suction blocks are advantageously configured to create an air flow under beneath the document (between the document guiding surfaces of suction blocks) that serves to suck the documents to the suction blocks. This keeps the document already flat. Furthermore, the air suction blocks also create an air flow in the belt-free gap and in particular between the document guiding surface of the inspecting plate and the document. This air flow towards the first and the second air suction blocks reduces or prevents air buffering in the area of the inspecting plate and keeps the document substantially flat.

[0061] The inspecting plate can be arranged between the first suction block and the second suction block and fill the gap. The upper surface of the inspecting plate is configured as a conveyor-free area. The sensor unit may then further be configured to detect a property of the document while passing over the inspecting plate.

[0062] The suction blocks and the inspecting plate are advantageously arranged such that there is no further gap between them.

[0063] The upper surfaces (document guiding surfaces) of the first suction block, the second suction block and the inspection plate are advantageously in the same flat plane on which the document can move.

[0064] However, in an aspect the plane of the upper surface of the first suction block can also have a very small inclination with respect to the plane of the upper surface of the inspection plate.

[0065] All the previously described aspects support that the document remains flush on the inspecting plate. Once the document is released from any conveyor unit, an air buffer can built up between the document and the upper surface of any plate or block (suction block, inspecting plate) on which the document is supposed to move. The effect of the air guides and/or suction blocks is that an air buffering between the document and the upper surface of the inspecting plate is reduced or even prevented and the surface smoothness of the document during quality control by the sensor unit is maintained.

[0066] Dependent on the type of the sensor unit, the inspecting plate can be made of various suitable materials as for example metal, steel, hardened glass, and/or ceramics. The inspecting plate may have a ceramic coating.

[0067] The sensor unit can be any kind of detector of properties or features of the document. It might be a sensor for detecting magnetic properties, or properties of the document like size, authenticity or fitness in general. In an embodiment, the sensor unit may be an image capture device which is configured to determine whether the document is complete or other properties of the document. The sensor unit may also be configured to detect security features on the document. If the sensor unit is an image capture device, the inspecting plate is advantageously transparent.

[0068] The sensor unit may comprise a first (may also be referred to as upper) sensor module and a second (may also be referred to as lower) sensor module. The first sensor module and the second sensor module can be arranged on opposite sides of the inspecting plate for sensing a property of the document from both sides. This aspect provides that the document and/or banknote can be sensed from both sides.

[0069] If the sensor unit is an image capture device, the first and second sensor module may take an image of the document in at least reflection of one side (or both sides) and/or transmission.

[0070] In case of an image capture device, the first sensor module of the image capture device may comprise a first light source and the second sensor module of the image capture device may comprise a second light source. The two light sources are arranged on opposite sides of the inspecting plate. The document or banknote may then be checked in reflection from both sides and in transmission.

[0071] The processing unit may generally be configured to process sensor data from the sensor unit, for example an image of the document received from the sensor unit, and to determine the authenticity and/or soiling and/or fitness of the document based on the sensor data.

[0072] In an advantageous embodiment, the inspecting plate can be coupled or fixedly coupled or can even form part of the first or second sensor module. If the inspecting plate and the sensor module are coupled to each other as an integral single component, the amount of soil or dust between the inspecting plate and the portion of the sensor unit can be reduced.

[0073] The length of the inspecting plate in the direction of the movement of the document can advantageously be 7 mm to 40 mm. This means also that the gap (when the inspecting plate is absent) can advantageously be 7 mm to 40 mm. Accordingly, there is a small belt-free gap for accommodating the inspecting plate over which the document and/or banknote passes. While passing over the gap (inspecting plate), properties can be sensed and/or detected from both side. For example, images can be taken from both sides of the document in reflection, but additionally images can be taken in transmission. This means that many if not all necessary checks of the authenticity and/or fitness of the banknote can be made within a single step.

[0074] Advantageously, a distance between the inspecting plate and the first or second sensor module can be between 2 mm and 12 mm, and advantageously 5 mm to 12 mm. This means that the opening through which the document moves has a limited height. This is possible as the document remains flat and flush on the plate due to the air pulses provided by the air guides and/or the suction blocks.

[0075] The first suction block and the second suction block can comprise through holes through which air is sucked by an underpressure below atmospheric pressure in a range of 0.1 bar to 0.8 bar, in particular 0.3 bar to 0.4 bar. The underpressure not only serves to keep the document close to the suction blocks. It also provides that any air buffers between the document and the flat surface of the suction blocks and/or the inspecting plate are prevented.

[0076] In an aspect, the document guiding surfaces of the first suction block, the inspecting plate and the second suction block lie in one plane. In other words, the surfaces of the three elements, suctions block and inspecting plate can provide one even surface for the document.

[0077] However, in an advantageous embodiment, the upper surface of the first suction block may be slightly, and only slightly, tilted with respect to the surface of the inspecting plate. The angle of inclination of the upper surface of the first suction block may only be 0° to 4°. Such a small inclination of the upper document guiding surface of the first suction block can provide an improved aerodynamic effect for the document. The risk of air buffering below the banknote may thereby be further reduced. The angle of inclination has to be kept very small to avoid negative effects when the leading edge of the document gets in contact with the inspecting plate.

[0078] There may also be small steps between the upper surfaces of the first suction block, the inspecting plate and the second suction block. These small steps may have a height of up to 0.3 mm. This further reduces the risk of air buffering below the banknote.

[0079] The invention also provides a document or banknote sorting machine including a device in accordance with the aspects and embodiments of the invention.

[0080] The invention further provides a method of sorting documents, in particular banknotes. The document can be passed from a first conveyor unit to an inspecting plate and from there to a second conveyor unit. Air pulses provided by air guides or rather the outlets of the air guides serve to smoothen and flatten and move the document or banknote. If air suction blocks are used in addition to air pulses from air guides, a document may be passed from a first conveyor unit to a first suction block. The first suction block can provide an underpressure to the lower surface of the document. The document can then be passed/pushed to an inspecting plate by the first conveyor unit over the upper surface of the first suction block. The document can be passed over the inspecting plate while sensing properties of the document by a sensor unit.

[0081] With or without suction blocks, the document is moved over the conveyor-free inspecting plate by either one or both of a first conveyor unit and a second conveyor unit both being arranged outside the area of the inspecting plate.

[0082] After having (partially) passed the inspecting plate, the document is received at a second suction block and/or a second conveyor unit opposite to the first suction block and/or the first conveyor unit with respect to the inspecting plate. The document is finally passed from the second suction block and/or the second conveyor unit for further processing the document.

[0083] The document can advantageously be tilted by a predetermined angle with respect to the upper document guiding surface of the inspecting plate before passing it to the inspecting plate. This further decreases air buffering between the document and the upper document guiding surface of the inspecting plate.

[0084] In the context of this description, the document or banknote is considered to be a flat sheet of material. The document or banknote is also considered to basically define a plane or extend in a single plane. If the document or banknote is described to be tilted, rotated or turned by an angle, this means that the entire plane of the flat document is tilted by the respective angle. Furthermore, the angle of tilting or inclination relates to the direction of movement in a sorting machine. With respect to this movement, the document or banknote has a leading edge and a trailing edge. The document or banknote is assumed to be flat (in a single plane). The angle of rotation or inclination is then considered to occur around an axis that is parallel to the leading edge and/or trailing edge of the document or banknote.

[0085] The invention generally provides methods and devices for sorting machines for valuable documents, in particular banknotes. The invention ensures surface smoothness of the document during quality control by sensor evaluation. A belt-free support for the document is provided, along which properties of the document are detected and determined. In case of an image capture device, images (be it by any kind of camera or scanning device) can be taken from the document in reflection from both sides and in transmission (through the document). The document is kept flat on the inspecting plate (for example glass, metal, steel, or ceramics etc.) and is driven by at least one conveyor unit which is arranged outside the inspecting plate (conveyor free area).

[0086] Underpressure can be provided below the document by vacuum suction. However, the respective suction blocks remain outside the inspecting plate. Furthermore, the upper document guiding surface of a device along which the document is guided towards the inspecting plate can have a (small) angle of inclination in order to further reduce any risk of air buffering between the document and the inspecting plate. Still further, small steps may be provided between the upper surface of the inspecting plate and the upper surfaces of the suction blocks.

[0087] The present invention also provides a method of guiding a document through a belt-free and/or roller-free gap of a document/banknote sorting machine, the method comprises the step of applying air pulses through outlets of air guides on the document moving through the gap. Other aspects of the method can be derived from the aspects and embodiments described herein.

BRIEF DESCRIPTION OF DRAWINGS

[0088] Further aspects, characteristics and advantages of the invention will ensue from the following description of the embodiments with reference to the accompanying drawings, wherein

FIG. 1 is a simplified cross-sectional view of an embodiment of the invention

FIG. 2 is a simplified top view on the embodiment shown in FIG. 1,

FIG. 3 is a simplified cross-sectional view of an embodiment of the invention,

FIG. 4 A-C are simplified views on embodiments of air guides,

FIG. 5 is a simplified view on an embodiment of a branching of an air guide,

FIG. 6 is a simplified cross-sectional view of an embodiment of the invention,

FIG. 7 is a simplified top view on the embodiment of FIG. 1,

FIG. 8A-C are simplified cross-sectional side views on possible details of the embodiments shown in FIG. 1 and FIG. 2,

FIG. 9 is a simplified block diagram of a document processing and/or sorting machine according to an embodiment,

FIG. 10 is a simplified cross-sectional view on another embodiment, and

FIG. 11 is a simplified cross-sectional view on another embodiment.

DETAILLED DESCRIPTION OF EMBODIMENTS

[0089] FIG. 1 is a simplified cross-sectional view of an embodiment of the invention. There is a module or apparatus 100 for a document or banknote sorting machine. The apparatus comprises an inspecting plate 1 which is arranged between a first conveyor unit 50 and a second conveyor unit 51. There is a sensor unit (for example, image capture device) comprising a first sensor module 21 and a second sensor module 22. The document or banknote moves along the direction indicated by the arrow BN. The first conveyor unit 50 is only represented in a simplified manner and comprises conveyor belt 12 and roller 4. The second conveyor unit 51 is also only represented in a very simplified manner and comprises conveyor belt 14 and roller 9. The document is initially held and transported between the first conveyor belt 12 and a second (complementary) conveyor belt (not shown) of the first conveyor unit 50. After the document has passed with a leading edge the inspecting plate 1 and reaches or passes the second end SE1 of the inspecting plate 1 to reach the second conveyor unit, the document is also held and transported between the first conveyor belt 14 and a second conveyor belt (not shown) of the second conveyor unit 51. When the trailing edge of the document leaves the first conveyor unit 50 and/or reaches or passes the first end of the inspecting plate 1, the document is moved/transported by the second conveyor unit 51.

[0090] There can be one two or three first and respective second belts arranged side-by-side (meaning two, four or six conveyor belts all together) dependent on the type of conveyor system.

[0091] Both conveyor units 50 and 51 are only represented in a very simplified manner. The document or banknote passes from the first conveyor unit 50 along the inspecting plate 1 to the second conveyor unit 51.

[0092] There are further two deflecting plates MP1 and MP2 for guiding the moving document.

[0093] Two air guides AG1 and AG2 are shown having respective outlets OL1 and OL2 in the area of the inspecting plate (belt-free gap) providing an air flow AF1 (also referred to as air flow axis AF1) and AF2 (also referred to as air flow axis AF2) which are advantageously pulses of air. The air guides AG1, AG2 are coupled to outputs VO1, VO2 of respective high speed valves V1 and V2 (i.e. valves having a response time of 1 ms and shorter and/or a switching frequency of 1kHz and higher). The valves are coupled to a tank T comprising air of a pressure in the range of 2 bar bar to 8 bar. The tank is advantageously arranged as close as possible to the valves. The outlets of the valves are arranged as close as possible to the valves. In other words, the length of the air guides is as short as possible. The valves are controlled by a control unit CU. The air pulses provided at the outputs OL1 and OL2 of each of the air guides AG1 and AG2 keep the document flat on the inspecting plate.

[0094] The outlets OL1 and OL2 of the two air guides are located within the same track. The outlet OL2 of the second air guide AG2 is arranged such that the air flow AF2, or air flow axis AF2 is substantially normal to the document guiding surface. This means that an angle γ between the output direction of the outlet OL2 (or the air flow AF2) and the document guiding surface DS is 90°. The outlet OL1 of the first air guide AG1 is arranged such that the angle β between the direction of the air flow AF1 (or air flow axis AF1) output by the outlet OL1 is smaller than 90°, advantageously 50° to 55°.

[0095] The air guides AG1 and AG2 have cross-sectional areas and/or diameters that remain at least constant or increases along the extension of each air guide AG1 and AG2, respectively, in the direction of the air flow, i.e. from the respective valve V1 or V2 to the output OL1 or OL2.

[0096] As a consequence, the document remains flush on the inspecting plate 1 and the properties of the document can be well sensed. For example, images can be taken in reflection from both sides of the document and in transmission.

[0097] Accordingly, the first and second sensor modules 21, 22 of the sensor unit, for example two image capture devices can be configured to sense or detect a property (for example images) of the document while passing over the inspecting plate 1. The sensed or detected property (for example captured images) may then be further processed and evaluated in a processing unit (not shown).

[0098] The first sensor module 21 and the second sensor module 22 are arranged on opposite sides of the inspecting plate 1. In case of image capture devices, the image capture devices take a picture or scan of both sides of the document in reflection and also one scan or picture in transmission.

[0099] In case of an image capture device, the first sensor module 21 of the image capture device may comprise a first light source and the second sensor module 22 of the image capture device may comprise a second light source. The two light sources can be arranged on opposite sides of the inspecting plate 1. The first sensor module 21 of the image capture device may also comprise a first image capture unit, for example a camera or scanner, and the second sensor module 22 of the image capture device may comprise a second image capture unit, for example a camera or a scanner. The two light sources can be arranged on opposite sides of the inspecting plate 1. The document or banknote may then be checked in reflection from both sides and in transmission.

[0100] A processing unit (not shown) can be configured to process any sensor data, for example an image, of the document received from the sensor modules 21, 22 and to determine the authenticity and/or soiling and/or fitness of the document.

[0101] In an advantageous embodiment, the inspecting plate 1 can be coupled (or fixedly coupled) or can even form part of the first or second sensor module. If the inspecting plate 1 and one of the sensor modules 21, 22 are coupled to each other as an integral single component, the amount of soil or dust between the inspecting plate 1 and the portion of the sensor modules 21, 22 can be reduced. In this embodiment, the inspecting plate 1 forms part of the second sensor module 22.

[0102] The length D1 of the inspecting plate 1 in the direction BN of the movement of the document can advantageously be between 7 mm and 40 mm. Accordingly, there is a small belt-free or roller-free gap formed by the inspecting plate 1 over which the banknote passes. While passing over the belt-free or roller-free gap, i.e. over the inspecting plate 1, sensor data, as for example images can be taken from both sides of the document in reflection and also in transmission. Dependent on the type of the sensor unit, other properties of the document may be determined. This means that many or all necessary checks of the authenticity and/or fitness of the banknote can be made within a single step.

[0103] The distance D2 between the upper document guiding surface of the inspecting plate 1 and the surface of the first sensor module 21 can be 2 mm to 12 mm, and advantageously 3 mm to 12 mm

[0104] The speed of the documents or banknotes in moving direction BN can be about 8 m/s or faster (an advantageous value is also 10 m/s).

[0105] The inspecting plate 1 can be made of any smooth (and transparent, and hardened) material, as for example glass, metal, steel or ceramics.

[0106] FIG. 2 shows a simplified illustrating top view of the embodiment shown in FIG. 1. FIG. 2 mainly serves to describe in more detail the possible positioning of the outputs of air guides. The outputs OL1 to OL4 of the air guides AG1 to AG4 are advantageously arranged in tracks. For the four shown air guides AG1 to AG4 and their respective outputs OL1 to OL4 it can be seen that the output OL1 of the first air guide AG1 and the output OL2 of the second air guide AG2 are arranged in a first track TR1, i.e. a band or line in the direction of the movement BN of the document. The output OL3 of the third air guide AG3 and the output OL4 of the fourth air guide AG4 are arranged in a second track TR2, i.e. in a different band or line in the direction of the movement BN of the document. The outputs OL1 and OL3 have the same position P1 with respect to a document input DI and the outputs OL2 and OL4 also have the same position P2 with respect to the document input DI. The distance DIST12 between outputs O1 (03) and 02 (04) is the distance between the first position P1 and the second position P2 in direction of the movement of the document. This distance can be 15 mm.

[0107] The different air flows output by the outlets of the air guides can generally have divergent and/or convergent air flow axes. For example, OL3 and OL1, and respectively OL4 and OL2 can have convergent or divergent air flow axis. This can provide more local force or a better smoothing effect.

[0108] FIG. 3 is a simplified cross-sectional view of an embodiment of the invention that is basically similar to the embodiment of FIG. 1 and FIG. 2. However, there is a third air guide AG3 having an outlet OL3 and providing an air flow AF3 (air flow axis AF3). The air guide can be coupled to a separate high speed valve V3 which is controlled by the control unit CU. The outlet OL3 is also close to the document input or least much closer the document input than the output OL2 of the second air guide AG2. The angle δ of the air flow AF3 provided at the output OL3 of the third air guide AG3 and the document guiding surface DS is smaller than the angles γ and β of the air flows AF1 and AF2 provided by the first and second air guides. The angles δ, γ and β are angles in the plane of this cross-sectional view. The axes of the air flows or air flow axes can generally also be divergent or convergent with respect to each other and also be inclined with respect to the plane of the cross-sectional view.

[0109] The three shown outlets OL1, OL2 and OL3 of the respective air guides AG1 to AG3 can also be arranged in one track. Another three air guides (which are not shown here) and their respective outlets can be arranged in a second track similar to the arrangement shown in FIG. 2.

[0110] In this embodiment, the pulses provided by the three air guides AG1, AG2 and AG3 can be controlled according to a three phases principle. Each phase (output of air guide/valves/electronic control unit) contributes to the guidance of the moving document and can have its own timing. For instance, the first air guide AG1 can control the trajectory just after the document has left the first conveyor unit. The second air guide AG2 (second phase) can be dedicated to maintain the document in the region of the middle axis of the sensor unit. The third air guide AG3 can be configured to control the trajectory in the direction of the second conveyor unit. The global arrangement of the outputs and air guides AG1 to AG3 is such that it optimizes the fluttering in the region of sensor unit or inspecting plate.

[0111] As the output OL3 of the third air guide AG3 is almost parallel to the inspecting plate and thereby to the detector window it can also be operated to clean the sensor unit by sending air pulses between sorting sequences (batches).

[0112] AG1, AG2, and AG3 can also be operated to clean the windows by sending air pulses in sequences taking profit of bounces between surfaces.

[0113] FIG. 4 shows three examples of possible shapes of an air guide according to embodiments of the invention. FIG. 4 A shows a substantially tubular shaped air guide AG. The cross-sectional areas A1 and A2 are shown at two points along the direction of the air flow. It can be seen that the cross-sectional areas A1 and A2 remains constant along the air guide AG. Since the cross-section is substantially circularly shaped, it can also be said that the diameter of the cross-section remains constant. In the embodiment shown in FIG. 4 B, the cross-sectional area A1 which is more upstream than the cross-sectional area A2 is smaller than the cross-sectional area A2. Accordingly, for a substantially circularly shaped cross-section, the diameter only increases in the direction of the air-flow. While the increase of the cross-sectional area from A1 to A2 is rather linear in FIG. 4 B, it can also increase non-linearly as shown in FIG. 4 C. The shape can also be referred to as trumpet-like shaped.

[0114] FIG. 5 shows a simplified view on a branching of an air guide AG according to an aspect of the invention. It is advantageous if the angle Ω between any adjacent pair (here only one) of outputs of the brunching has an angle that is at least smaller than 180°. This further decreases the risk of reflection of air pulses or deceleration of air pulses propagating through the branching. Branchings which are made according to this aspect can be used if, for example a single high speed valve is to be used for more than one air guide or rather more than one outlets. However, such a branching can also be located between the tank and the valves.

[0115] FIG. 6 is a simplified cross-sectional view of an embodiment of the invention. There is a module or apparatus 100 for a document or banknote sorting machine. The apparatus comprises an inspecting plate 1 which is arranged between a first suction block 2 and a second suction block 3. The arrangement of the air guides AG1 and AG2 and the respective outputs OL1 and OL2 is similar to the one described with respect to FIG. 1 and FIG. 2. Furthermore, the embodiment shown in FIG. 3 (three phase control) and the other drawings may also be used for any air guides AG used in this embodiment. It should be noted that the use of air guides AG and air pulses is only optional but may be advantageously combined with air suction blocks as further described below. However, many aspects described below also apply to an apparatus and methods without suction blocks.

[0116] The apparatus 100 to this embodiment can comprise a first conveyor unit 50 and a second conveyor unit 51 and a sensor unit (for example, image capture device) comprising a first sensor module 21 and a second sensor module 22. The document or banknote moves along the direction indicated by the arrow BN. The first conveyor unit 50 is only represented in a simplified manner and comprises conveyor belt 12 and rollers 4, and 5 as well as the opposite or complementary conveyor belt 13 and respective rollers 7 and 6. The opposite conveyor belt 13 and in particular roller 7 of the first conveyor unit 50 are within the first suction block 2 (illustrated by dashed lines). The second conveyor unit 51 is also only represented in a simplified manner and comprises conveyor belt 14 and rollers 9, and 10 as well as the opposite or complementary conveyor belt 15 and respective rollers 8 and 11. The opposite conveyor belt 15 and in particular roller 8 of the second conveyor unit 51 are within the second suction block 3 (illustrated by dashed lines). The document is initially held and transported between the first conveyor belt 12 and the second (complementary) conveyor belt 13 of the first conveyor unit 50. After the document has passed with a leading edge the inspecting plate 1 and reaches or passes the second end SE1 of the inspecting plate 1 to reach the second conveyor unit (point H2 between the rollers 9 and 8), the document is also held and transported between the first conveyor belt 14 and the second conveyor belt 15 of the second conveyor unit 51. When the trailing edge of the document leaves the first conveyor unit 50 and/or reaches or passes the first end of the inspecting plate 1 (point H1 between the rollers 4 and 7 / release point), the document is only moved/transported by the second conveyor unit 51.

[0117] The distance between the first end FE1 of the inspecting plate 1 and the touching point/release point H1 of the last complementary rollers 4, 7 of the first conveyor unit 50 can be between 0 and 2 times r, wherein r is the radius of the rollers 4,7. The radius r of the rollers in this embodiment is typically 7.5 mm and 12.5 mm.

[0118] The distance between the second end SE1 of the inspecting plate 1 and the touching point/pick-up point H2 of the first complementary rollers 9, 8 of the second conveyor unit 51 can be between 0 and 2 times r, wherein r is the radius of the rollers 9,8. The radius r of the rollers in this embodiment is typically 7.5 mm and 12.5 mm.

[0119] The distance X between the release point H1 and the pick-up point H2 can therefore be between the length D1 of the inspecting plate 1 (which is also the length of the belt-free gap) and the length D1 of the inspecting plate 1 plus 4 times r, where r is the radius of the rollers (D1 ≤ X ≤ D1+4*r).

[0120] There can be one two or three first and respective second belts arranged side-by-side (meaning two, four or six conveyor belts all together) dependent on the type of conveyor system.

[0121] Both conveyor units 50 and 51 are only represented in a very simplified manner. The document or banknote passes from the first conveyor unit 50 along the first suction block 2. The first suction block 2 comprises though holes 18 through which air can be sucked by an underpressure which is created in a suitable suction device 17. The second suction block 3 also comprises though holes 18 through which air can be sucked by an underpressure which is created in a suitable suction device 16. Suction devices 16 and 17 may of course be a single device.

[0122] The suction blocks 2 and 3 suck the parts of the document down which are not held between the complementary conveyor belts 12, 13 and 14, 15, respectively. Another important air flow due to the suction blocks (the underpressure) is indicated by arrows A1 and A2. In fact, the suction blocks 2, 3 also prevent air from buffering between the document and the upper surface (document guiding surface) of the inspecting plate 1. As a consequence, the document remains flush on the inspecting plate 1 and the properties of the document can be well sensed.

[0123] For example, images can be taken in reflection from both sides of the document and in transmission.

[0124] Accordingly, the first and second sensor modules 21, 22 of the sensor unit, for example two image capture devices can be configured to sense or detect a property (for example images) of the document while passing over the inspecting plate 1. The sensed or detected property (for example captured images) may then be further processed and evaluated in a processing unit 70.

[0125] The first sensor module 21 and the second sensor module 22 are arranged on opposite sides of the inspecting plate 1. In case of image capture devices, the image capture devices take a picture or scan of both sides of the document in reflection and also one scan or picture in transmission.

[0126] In case of an image capture device, the first sensor module 21 of the image capture device may comprise a first light source and the second sensor module 22 of the image capture device may comprise a second light source. The two light sources can be arranged on opposite sides of the inspecting plate 1. The first sensor module 21 of the image capture device may also comprise a first image capture unit, for example a camera or scanner, and the second sensor module 22 of the image capture device may comprise a second image capture unit, for example a camera or a scanner. The two light sources can be arranged on opposite sides of the inspecting plate 1. The document or banknote may then be checked in reflection from both sides and in transmission.

[0127] The processing unit 70 can be configured to process any sensor data, for example an image, of the document received from the sensor modules 21, 22 and to determine the authenticity and/or soiling and/or fitness of the document.

[0128] In an advantageous embodiment, the inspecting plate 1 can be coupled (or fixedly coupled) or can even form part of the first or second sensor module. If the inspecting plate 1 and one of the sensor modules 21, 22 are coupled to each other as an integral single component, the amount of soil or dust between the inspecting plate 1 and the portion of the sensor modules 21, 22 can be reduced. In this embodiment, the inspecting plate 1 forms part of the second sensor module 22.

[0129] The length D1 of the inspecting plate 1 in the direction BN of the movement of the document can advantageously be 7 mm to 40 mm. There is a small belt-free gap formed by the inspecting plate 1 over which the banknote passes. While passing over the belt-free gap, i.e. over the inspecting plate 1, sensor data, as for example images can be taken from both sides of the document in reflection and also in transmission. Dependent on the type of the sensor unit, other properties of the document may be determined. This means that many or all necessary checks of the authenticity and/or fitness of the banknote can be made within a single step.

[0130] The first suction block 2 and the second suction block 3 comprise through holes 18 through which air is sucked by an underpressure below atmospheric pressure in a range of 0.1 bar to 0.8 bar, in particular 0.3 bar to 0.4 bar. The underpressure not only serves to keep the document close to the suction blocks 2, 3 (outside the conveyor belts). It also provides that any air buffers between the document and the flat upper surface of the suction blocks 2, 3 and/or the inspecting plate 1 are prevented.

[0131] The volume of sucked air is advantageously in relation to the amount of underpressure. The volume may be in the range from 1 m³ to 100 m³ per hour.

[0132] The volume of the sucked air can be a function of the amount of underpressure. The volume of sucked air can be determined as a function (or in relation to) the size (for example diameter) of the holes 18. The holes 18 may have a diameter in the range of 0.5 mm to 2 mm, in particular, the holes 18 may have a diameter of 1.2 mm. The volume of sucked air and/or the amount of underpressure can also be a function of the number per area or density of the holes 18. The holes 18 may be arranged in a regular grid. The distance of the holes 18 may then be in the range of 1 mm to 20 mm, and in particular 5 mm.

[0133] In an aspect, the document guiding surfaces of the first suction block 2, the inspecting plate 1 and the second suction block 3 lie in one plane. In other words, the surfaces of the three elements, suctions blocks 2, 3 and inspecting plate 1 can provide one even guiding surface for the document.

[0134] However, in the present advantageous embodiment, the upper surface of the first suction block 2 can also be slightly tilted with respect to the surface of the inspecting plate 1. The angle of inclination of the upper surface of the first suction block 2 with respect to the document guiding surfaces of the inspecting plate 1 and/or the second suction block 3 may only be 0° to 4°, i.e. the angle may have a maximum of 4°. Such a small inclination of the upper document guiding surface of the first suction block 2 can provide an improved aerodynamic effect for the document. The risk of air buffering below the banknote is thereby further reduced. The angle of inclination has to be kept very small to avoid negative effects when the leading edge of the document gets in contact with the inspecting plate 1.

[0135] The distance D2 between the upper document guiding surface of the inspecting plate 1 and the surface of the first sensor module 21 can be 2 mm to 12 mm.

[0136] The speed of the documents or banknotes in moving direction BN can be about 8 m/s or faster (an advantageous value is also 10 m/s).

[0137] The inspecting plate 1 can be made of any smooth (and transparent) material, as for example glass, metal, steel or ceramics.

[0138] FIG. 7 is a simplified top view on the embodiment of FIG. 6. The document moves in the direction indicated by the arrow BN (from right to left). There is only one conveyor belt 12, 14 per conveyor unit 50, 51. The respective belts 12, 14 hold the document. The document, in particular a banknote can have a width between 50 mm and 90 mm. In this embodiment, the suction blocks 2, 3 can have a width of 110 mm. Some of the upper rows RU and/or lower rows RL of the holes 18 may not be covered when the document has a smaller width.

[0139] From this perspective, it becomes apparent that the conveyor units 50, 51 advantageously end before the inspecting plate 1. The last roller 4 of the first conveyor unit 50 is arranged such that document is only released from the conveyor belt 12 when the trailing edge of the document leaves the first suction block 2 (or the previously described touching point/release point H1, see FIG. 1). The first roller 9 of the second conveyor unit 51 is arranged such that document is grabbed by the conveyor belt 14 when the leading edge of the document leaves the inspecting plate and/or arrives at the second suction block 3 (or the previously described touching point/pick-up point H2, see FIG. 1). The rollers 9 and 4 (and also the respective complementary or opposite rollers 8 and 7) are arranged as close as possible to the inspecting plate 1 but still outside the inspecting area of the inspecting plate 1. There are advantageously no holes 18 between the end of the rollers 4, 9 and/or the touching or holding points H1 (also release point), H2 (also pick-up point) as shown in FIG. 1 and the opposite ends FE1, SE1 of the inspecting plate 1. However, there can advantageously be holes 18 in the suction blocks which do not have a greater distance from the respective outer edges of the inspection plate 1 than 1 cm, in particular 0.5 cm.

[0140] The through holes 18 in the suction blocks 2, 3 may be evenly distributed over the entire upper surface of the suction blocks 2, 3. They may be arranged in a regular orthogonal grid. However, other arrangements are also possible. The inspecting plate 1 does not have through holes. The inspecting plate 1 is closed and firmly sealed against soil and/or dust.

[0141] The lower or complementary conveyor belt 13 of the first conveyor unit 50 is not shown, but divides the first suction block 2 in an upper part UP2 (first part) and a lower part LW2 (second) on each side of the conveyor belt 13. The lower or complementary conveyor belt 15 of the second conveyor unit 51 is not shown, but also divides the second suction block 3 in an upper part UP3 (first part) and a lower part LW3 (second part) on each side of the conveyor belt 15. In the area of the belts 13 and 15 of the first and second conveyor unit 50, 51, there are no holes 18 in the suction blocks 2, 3. However, other more complex embodiments may even use suction holes in the conveyor belts.

[0142] FIG. 8A, 8B and 8C are simplified cross-sectional side views on possible details of the embodiments of the invention. The upper surfaces 02, O1 and O3 of the first suction block 2, the inspecting plate 1 and the second suction block 3 serve as the document guiding surfaces for the document DOC, which can be a banknote. The document moves in the direction indicated by the arrow BN (from right to left). In the first embodiment shown in FIG. 8A, the three upper surfaces O1 to 03 of the inspecting plate 1 and the two suction blocks 2, 3 are all on the same level and provide a smooth and flat document guiding surface. Air is sucked through holes 18 which are provided in the two suction blocks 2, 3. The air flows indicated by arrows A1 and A2 provide that air buffering between the document DOC and the upper air guiding surfaces O1, 02 and 03 is prevented. The document DOC has a forward momentum provided by the first conveyor unit 50 which is not shown.

[0143] In the second embodiment shown in FIG. 8B, the upper surface 02 (plane of the surface) of the first suction block 2 is slightly tilted with respect to the upper surface (plane of the surface) of the inspecting plate 1 by an angle α. This angle should be very small and not be greater than 4°. This angle provides that the document DOC is slightly tilted with respect to the upper surface O1 of the inspecting plate. The tilting or slight rotation of the plane of the document DOC provides that the document DOC is pressed to the inspecting plate 1 and air buffering between the document DOC and the inspecting plate is reduced or prevented.

[0144] In the third embodiment shown in FIG. 3C, there may also be small steps S1, S2 between the upper surfaces O1, 02, 03 of the first suction block, the inspecting plate and the second suction block. These small steps S1, S2 may have a height of up to 0.3 mm. This can further reduce the risk of air buffering below the document DOC.

[0145] The sensor unit, in particular the sensor modules 21, 22 are advantageously independent from the suction blocks 2, 3. The suction blocks 21, 22 and the conveyor units 50 are advantageously part of the general transport system of the document processing/sorting machine. The sensor modules 21, 22 are then fitted into the gap between the suction blocks 2, 3. The second sensor module 22 advantageously includes the inspecting plate 1.

[0146] FIG. 9 is a simplified block diagram of a document sorting/processing machine 200 according to an embodiment. The document sorting/processing machine 200 (or paper currency processing apparatus) comprises the apparatus 100 according the herein described aspects and embodiments. The machine 200 is generally configured to process documents, for example paper currency (banknotes). The machine may comprise a supply section 301 in which a large number of documents/banknotes can be placed (stacked). There is also a pick-up stage 302 which is configured to pick up the documents from the supply section 301. The documents are then transferred on a transfer path 303 comprising a plurality of endless conveyor units (not shown). The documents are transferred (moved, transported) by the conveyor units by holding the documents between conveyor belts. The documents are transferred to a general auditing device 306 one by one. The auditing device 306 may comprise various stages among which the apparatus 100 according to the embodiments and aspects of the invention may be located. The auditing device 306 may generally be configured to perform one or more of the following tasks: determining the denomination, shape thickness, top/back genuineness, normality or defacement and the like. Some or all of these tasks may then be performed by and in the apparatus 100 according to the aspects and embodiments of the invention. According to the result of the auditing, the documents/banknotes are either rejected and transferred to a rejection stage 304 or approved and transferred to section 305 for being re-circulated.

[0147] The apparatus 100 according to the aspects and embodiments of the present invention provides, among others, a fitness sensor (sensor unit), for example including a camera system having a clear view to the document from both sides (reflection) and in transmission without disturbing elements like belts or support fences. The belt-free gap in the transport system does not increase the jam-rate in that particular part of the transport system. The length of the belt-free gap or length of the inspecting plate 1 in the direction of the movement of the document is kept very small. It may range up to 40 mm, and advantageously ranges from 7 mm to 40 mm, while 7 mm is also an advantageous value.

[0148] FIG. 10 is simplified cross-sectional view on another embodiment. The embodiment is substantially similar to the one shown in FIG. 3. In this embodiment, however, some outlets OL1* and OL2* of the air guides AG1* and AG2* are also arranged under beneath the document guiding surface DS.

[0149] Each additional air guide AG1*, AG2* can then be coupled to another separate high speed valve V1* and V2*, which are controlled by the control unit CU.

[0150] Accordingly, the outlets OL1, OL2, OL3, OL1* and OL2* of the air guides AG1, AG2, AG3, AG1* and AG2* can be arranged above and under beneath the document guiding surface DS such that any banknote or other valuable document moves along the document guiding surface DS and between at least two outlets OL1, OL1* and/or OL2, OL2* of the air guides AG1, AG1*, AG2, AG2* which are arranged on opposite sides of the document guiding surface DS.

[0151] Accordingly, the outlets OL1, OL2 of air guides AG1, AG2 (also AG3, which is not shown or any other) can generally be duplicated at the opposite side of the moving document or document guiding surface DS, thereby, for example substituting at least parts (or all) of the document guiding surface DS. The aspect provides that the friction of the moving documents on the document guiding surfaces DS is reduced and the speed of the documents is preserved. Furthermore, any delay can be reduced and any possible erosion of detector surfaces DT21, DT22 (i.e. erosion of the document guiding surface) can be reduced. This aspect further helps to manage the levitation of the transported documents between detector surfaces (document guiding surface and opposite surface of a sensor unit), with a symmetrical or non-symmetrical position of the trajectory of the document between them, by controlling the average force provided by each outlet OL1, OL2, OL3, OL1*, OL2* of an air guide along the passing document. The trajectory may then be controlled in real time, with the feed-back of the control unit CU, as a fully active system. The control of each couple of valves V1, V1*, V2, V2* in opposite positions can be differential. For example, the trajectory position following a track or a portion of track can be adjusted by a differential management of valves V1, V1*, V2, V2*, by applying more force pressure to the front surface, and less force pressure the reverse side by using a pulse width modulation principle (conjugated or alternated). Each couple of valves V1, V1* and/or V2, V2* can be independently managed, for example according to a feedback control principle.

[0152] FIG. 11 is simplified cross-sectional view illustrating the aspect of a housing or air chamber AC with respect to the embodiment shown in FIG. 3. This can of course also be applied to all the other aspects and embodiments of the invention.

[0153] The air chamber (housing) AC or closed room concept can generally improve the dynamic pressure on the moving documents. There is an input wall IW and a cover AC that close the cross section at the end of the gap. This provides that the air remains between the sensor units 21, 21 and does not blow out in other directions (for example in the direction of the observer). Using a cover in form of an air chamber AC or closed room according to this embodiment helps to reduce the air consumption. The air chamber AC or housing can be configured to protect against dust, reduce noise, control temperature, shield light, protect against EMI, and/or removing additional air due to the air provided by the air guides.

[0154] It should generally be noted that in all the described embodiments, the air pulses provided by the air guides into the gap (bel-free or roller free) or generally between the detector surfaces DT21, DT22 tend to bounce between the surfaces and propagate further once they are reflected on a surface. This can advantageously be used to clean the detector surfaces.

[0155] While various embodiments have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the embodiments. Accordingly, the embodiments are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

1. An apparatus (100) for a document sorting machine, in particular a banknote sorting machine, comprising: an inspecting plate (1) of a sensor unit and a conveyor belt-free and/or roller-free gap, the belt-free gap and/or roller free gap being configured to accommodate the inspecting plate (1); the length of the gap being substantially shorter than the length of the document, the apparatus (100) further comprising at least one hollow air guide between an outlet of a valve and an outlet of the air guide at an end of the air guide opposite to the outlet of the valve for blowing air on a document moving along the inspecting plate (1), wherein the cross-sectional area of the air guide remains either constant or increases between the outlet of the valve towards and until the outlet of the air guide including the cross-sectional area of the outlet of the air guide.

2. The apparatus according to claim 1, further comprising a first air guide and a second air guide being arranged along the moving direction of the bank note.

3. The apparatus according to claim 2, wherein the outlet of the first air guide and the outlet of the second air guide have a distance of 10 mm to 20 mm, and in particular a distance of 15 mm to 17 mm.

4. The apparatus according to claim 2 or 3, wherein the second air guide, in particular the outlet of the second air guide, is arranged such that the air is blown substantially normal to a document guiding surface of the inspecting plate.

5. The apparatus according to anyone of claims 2 to 4, wherein the first air guide is inclined with respect to a document guiding surface of the inspection plate by an angle of 50° to 55°, such that the air output by the first air guide is partially blown into the moving direction of the document.

6. The apparatus according to anyone of claims 2 to 5, wherein the outlet of the first air guide and the outlet of the second air guide are arranged along and/or in a first track.

7. The apparatus according to claim 6, further comprising a third air guide having an outlet being arranged such that an air flow is provided that has an angle with respect to the document guiding surface that is smaller than the angle of the second air guide.

8. The apparatus according to claim 7, wherein the outlet of the third air guide is arranged along and/or in the first track and/or the outlet of the third air guide is arranged in another track, in particular a middle track, which is different from the first track.

9. The apparatus according to anyone of the preceding claims, further comprising a separate valve for each air guide, wherein the valve is a high speed valve configured to switch within 1 ms.

10. The apparatus according to anyone of the preceding claims, wherein at least one of the air guides has the shape of a tube.

11. The apparatus according to anyone of the preceding claims, wherein at least two outlets of air guides are arranged on opposite sides of the moving document and/or wherein at least on outlet of an air guide is arranged beneath the moving document such that an air flow is provided between the document and the document guiding surface.

12. The apparatus according to anyone of the preceding claims, wherein a distance between at least one outlet of an air guide and a document guiding surface of the inspection plate is 5 mm, and in particular 10 to 12 mm.

13. The apparatus according to anyone of the preceding claims, further comprising a control unit configured to control the air flow by the valve such that the air is supplied in pulses.

14. The apparatus according to claim 13, wherein the pulses are modulated.

15. The apparatus according to claim 13, wherein the air through an air guide is controlled such that there is an ON-cycle during which air is blown with a substantially constant pressure and an OFF-cycle during which no air is blown through the air guide, thereby creating a duty cycle of blown air through the air guide having a determined OFF-time and a determined ON-time.

16. The apparatus according to anyone of the preceding claims, further comprising at least one light barrier, the light barrier being configured to detect a document approaching the inspection plate so as to trigger an air pulse through an air guide.

17. The apparatus according to anyone of the preceding claims, further comprising a cover and/or housing for protecting against dust, reducing noise, controlling temperature, shielding light, protecting against EMI, and/or removing additional air due to the air provided by the air guides.

18. The apparatus according to claim 17, wherein the cover is made of a metallic material, in particular an electrically conducting material.

19. The apparatus according to claim 17 or 18, wherein the cover and/or housing provides a substantially air-tight closed chamber around the belt-free and/or roller-free gap.

20. The apparatus according to anyone of the preceding claims, wherein the apparatus is a stand-alone system.

21. The apparatus according to anyone of claims 14 to 16, wherein the modulation of the air flow is controlled and varied in response to a detected or predetermined characteristic of the document, in particular a banknote.

22. The apparatus according to claim 21, wherein the air flow through different air guides is controlled differently in response to detected or predetermined properties of the document, in particular a banknote.

23. The apparatus according to claim 21, wherein the air flow through at least one air guide is controlled such that an orientation of the document is changed during movement of the document.

24. The apparatus according to anyone of the preceding claims, wherein a diameter of an air guide is 2.6 mm, 2 to 3 mm, or 2 to 5 mm.

25. The apparatus according to anyone of the preceding claims, wherein at least one air guide comprises a branching having an input and a pair of outputs, and wherein an angle between the outputs is smaller than 180°.

26. The apparatus according to anyone of the previous claims further comprising a first suction block; a second suction block; a first conveyor unit for moving the document along a document guiding surface of the first suction block and a second conveyor unit for moving the document along a document guiding surface of the second suction block, the first suction block and the first conveyor unit and the second suction block and the second conveyor unit being arranged on opposite sides of a conveyor belt-free and/or roller-free gap, the belt-free and/or roller-free gap being configured to accommodate the inspecting plate of a sensor unit; wherein the length of the gap is substantially shorter than the length of the document.

27. The apparatus according to claim 26, wherein the first conveyor unit is configured to only release the document when a trailing edge of the document leaves the first suction block and/or the second conveyor unit is configured to only pull the document when a leading edge of the document leaves the belt-fee and/or roller-free gap and/or when or after the leading edge of the document enters the second suction block.

28. The apparatus according to anyone of the preceding claims, further comprising a sensor unit, wherein the sensor unit comprises a first sensor module and a second sensor module, the first sensor module and the second sensor module being arranged on opposite sides of the inspecting plate.

29. The apparatus according to claim 28, wherein the inspecting plate forms an integral part of the second sensor module.

30. A document/banknote sorting machine comprising an apparatus according to anyone of the previous claims.

31. A method of guiding a document through a belt-free and/or roller-free gap of a document/banknote sorting machine, the method comprising: applying air pulses through outlets of air guides on the document moving through the gap.

Drawing