Abstract:
A method and apparatus for singling sheet material, in particular papers of value such as bank notes, checks, etc., for subsequent processing of single pieces of sheet material. To permit recognition of mix-ups in the singling order, maintenance of the singling order is checked at the place of singling by monitoring whether the next piece of sheet material to be singled is singled.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a §371 of PCT Application Serial No. PCT/EP02/08427, filed Jul. 29, 2002. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method and apparatus for singling sheet material, in particular papers of value such as bank notes, checks, etc., for subsequent processing of single pieces of sheet material. 
   2. Description of the Background Art 
   Sheet material, e.g. bank notes, are usually processed using bank note processing machines wherein the bank notes are inserted into an input pocket in a stack. The input pocket is connected with a singler that singles the bank notes present in a stack and transfers them singly to a transport system. The transport system then transports the single bank notes e.g. past sensors for e.g. counting, recognizing and checking the state and authenticity of the bank notes. In dependence on the check results the single bank notes can finally be sorted into different output pockets. 
   Problems in processing can always arise when errors occur in the singling of the bank notes. A well-known error of this kind is the so-called double pick. Instead of a single bank note, two or more bank notes are grasped by the singler and transferred to the transport system. Errors of this kind can be recognized without any great problems by determining the thickness of the singled bank notes. If the determined thickness exceeds a predetermined threshold value, it is recognized that more than one bank note was singled. Greater problems result when the error involves a mix-up of the singling order. In this case the bank note to be singled next is not singled, but a bank note disposed after said note in the stack of bank notes inserted into the input pocket. A mix-up of singling order is problematic within a stack of bank notes in particular in the processing of different groups of bank notes separated from each other by separation or header cards. In this case a mix-up of singling order can lead to bank notes being erroneously attributed to the wrong group of bank notes. 
   The problem of the present invention is therefore to specify a method and apparatus for singling sheet material, in particular papers of value such as bank notes, checks, etc., for subsequent processing of single pieces of sheet material wherein mix-ups of the singling order can be recognized. 
   The invention starts out from the consideration that singling order is always maintained when at the place of singling it is checked whether the piece of sheet material to be singled next is singled. 
   The advantage of the invention is to be seen in particular in that it permits problems to be avoided that result from a mix-up of singling order. Such mix-ups are problematic in particular in the processing of different groups of bank notes by means of separation cards since in this case the single groups of bank notes are accounted for incorrectly. 
   In a development it is provided that monitoring of the singling order is effected by checking a motion of the next piece of sheet material to be singled. 
   The advantage of the development is to be seen in particular in that monitoring the motion of the next piece of sheet material to be singled permits an especially simple realization of the monitoring of singling order. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages of the present invention can be found in the dependent claims and the following description of embodiments with reference to figures, in which: 
       FIG. 1  shows a schematic structure of an inventive apparatus for singling sheet material according to a first embodiment, and 
       FIG. 2  shows a schematic structure of an inventive apparatus for singling sheet material according to a second embodiment. 
       FIG. 3  shows a schematic structure of an inventive apparatus for singling sheet material according to an embodiment of the present invention 
   

   The figures show only the components essential in connection with the present invention. Similar components of the figures are marked by the same reference signs. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a first embodiment of an apparatus for singling sheet material consisting of singler  10  to  13 . Singler  10  to  13  works as a so-called friction wheel singler in the shown example and has singling wheels  10  and  11 , retaining wheel  12  and input pocket  13  with a support for bank notes BN 1  to BN 3  to be singled. During singling by singler  10  to  13 , bank notes BN 1  to be singled are grasped by singling wheels  10  and  11 , singled and transferred to a transport system (not shown) of a bank note processing machine in which singler  10  to  13  is integrated. The transport system transports singled bank notes BN in stated direction T to permit further processing, such as testing, counting, sorting, etc. While one bank note BN 1  is being grasped and singled, other bank notes BN 2 , BN 3  of the stack of bank notes inserted into input pocket  13  are retained by retaining wheel  12 , so that only bank note BN 1  to be singled is singled. 
   In the case shown in  FIG. 1 , however, there is the danger of following bank note BN 2  being singled instead of bank note BN 1  to be singled next, and thus the predetermined singling order changed. This danger exists since bank notes BN lie on each other in the stack inserted into input pocket  13  in such a way that the leading edge of following bank note BN 2  is located before the leading edge of bank note BN 1  to be singled next. Thus there is a high probability in the shown case of following bank note BN 2  being grasped and singled by singling wheels  10 ,  11  instead of bank note BN 1  to be singled next. 
   Such a mix-up of singling order is problematic in particular in cases where different groups of bank notes are being processed. Such different groups of bank notes can be formed for example by deposits from different depositors. For separating the different deposits, so-called separation or header cards are placed between the various deposits or groups of bank notes before the latter are inserted into input pocket  13  as a stack. If such a separation card is present at the place of bank note BN 2  in the case shown in  FIG. 1 , a mix-up of singling order results in the assumption, after faulty singling of the separation card (bank note BN 2 ), that a new group of bank notes or a new deposit is beginning. Bank note BN 1  subsequently singled in mixed-up singling order is thus associated with the new group of bank notes or new deposit which is marked by the separation card (bank note BN 2 ). Bank note BN 1  is thus not attributed to the previous group of bank notes to which it belongs, but to the following group of bank notes, so that the accounting of the two groups of bank notes is incorrect. 
   Such accounting errors can be avoided if the mix-up of singling order is recognized, since this permits corresponding measures for correction to be taken. This is done using sensor  20  provided in input pocket  13  or the support of input pocket  13 . Sensor  20  detects whether bank note BN 1  to be singled next is singled. For this purpose, the embodiment shown in  FIG. 1  has mechanical sensor  20  which is formed by a roller with an incremental transducer. The signal of the incremental transducer is monitored as to whether pulses are generated at the time of an expected singling due to rotation of the roller caused by the singling of bank note BN 1  to be singled next. If the number of pulses corresponding to the path that bank note BN 1  is transported and resulting from the length of bank note BN 1  is additionally determined, a statement can be made with a high degree of certainty on whether next bank note BN 1  to be singled was singled. If no pulses in the signal of the incremental transducer are observed at the time of singling, however, bank note BN 1  to be singled next was not singled. In this case two events can have occurred. The first event can be a gap in singling, i.e. no bank note was grasped and singled by singling wheels  10 ,  11  at the predetermined singling time. In the second event, another bank note BN 2  was singled instead of bank note BN 1  to be singled next. The fact that singling took place can be detected for example by means of a light barrier  25  in the transport system. Occurrence of the first event is uncritical. If the second event involving a mix-up of singling order is detected, however, suitable measures for error correction can be taken, e.g. singling stopped to eliminate the mix-up. 
     FIG. 2  shows a second embodiment of an apparatus for singling sheet material consisting of singler  10  to  13 . Except for sensor  20 , the second embodiment shown in  FIG. 2  corresponds to the first embodiment shown in  FIG. 1 . The second embodiment according to  FIG. 2  instead has sensor  30  that determines contactlessly whether bank note BN 1  to be singled next is grasped and singled by singling wheels  10 ,  11 . Sensor  30  can be formed as an optical sensor for example. For detecting whether bank note BN 1  to be singled next is singled, optical sensor  30  can be designed for motion detection or optical sensor  30  is used to perform an image evaluation. As described for the first embodiment according to  FIG. 1 , the evaluation of optical sensor  30  is also effected during the time periods when singling is expected. It is likewise determined at likewise determined at the same time whether bank note BN 1  to be singled next is grasped and moved sufficiently far. 
   It is obvious that the described inventive apparatuses and methods can not only be used for the friction wheel singlers shown by way of example in the figures. Rather, the described principle is also suitable for singlers having a different structure, e.g. so-called suction air singlers which grasp bank notes to be singled by suction air or vacuum.  FIG. 3  depicts the inventive singling apparatus according to an embodiment of the present invention. As shown in  FIG. 3 , singling wheels  10  and  11  may be replaced with a suction air singler  35  to facilitate singling. As with the apparatus shown in the previous embodiments, the fact that singling took place can be detected by means of light barrier  25 , which is downstream of the singler. 
   Likewise, it is obvious that singling can also be done from above, i.e. the uppermost bank note in the stack singled, instead of singling from below as shown in the figures, i.e. singling of the lowermost bank note in the stack. 
   Further, it is possible to mount sensor  20 ,  30  not in input pocket  13  or its support but at a different place in the area of singler  10  to  13  where the described monitoring of next bank note BN 1  to be singled is possible.