Patent Publication Number: US-9845213-B2

Title: Sheet diverting unit

Description:
FIELD OF THE INVENTION 
     The present invention relates to a sheet diverting unit for selectively diverting a sheet. The present invention further relates to a printing system for printing on a sheet comprising a sheet diverting unit according to the present invention. The present invention further relates to a sheet handling device for transporting a sheet comprising a sheet diverting unit according to the present invention. 
     BACKGROUND ART 
     A known productive printing apparatus for printing on cut sheets comprises a printing station for applying an image on both sides of said cut sheet, a sheet input station for storing cut sheets to be printed, a sheet output station for collecting processed cut sheets and a sheet transport path arranged for advancing cut sheets throughout the printing apparatus. Said sheet transport path may be arranged for in a simplex printing mode selectively moving cut sheets from said sheet input station along the printing station, which prints a first image on the cut sheet, towards the sheet output station. Alternatively said sheet transport path may be arranged for in a duplex printing mode selectively after printing the first image circulating the cut sheet along a circulating duplex path back to the printing station for printing a second image on another side of the cut sheet opposite to the first image. 
     A sheet diverting unit may be arranged downstream of the printing station for selectively diverting a sheet towards a first receiving path, such as said circulating duplex path, or towards a second receiving path, such as an output path towards the sheet output station. The sheet diverting unit comprises an inlet path for advancing a sheet in a sheet supply direction towards a diverter. The diverter comprising a shaft, a deflector being connected to said shaft and extending between said shaft and a tip. Said actuator is arranged for rotating the shaft thereby selectively pivoting the deflector between a first deflector position for directing the sheet into the first receiving path and a second deflector position for directing the sheet into the second receiving path. The deflector comprises a curved edge and a guiding edge, said curved edge arranged facing a second trajectory to the second receiving path in the second deflector position for deflecting the sheet into the second receiving path and said guiding edge arranged facing a first trajectory to the first receiving path in the first deflector position for guiding the sheet into the first receiving path, such as a straight path or straight first trajectory arranged in line with inlet path. 
     To achieve higher productivity in printing cut sheets a demand exists for reducing a inter sheet gap (or free distance) between successive sheets advancing in the sheet transport path. Similar to the free distance a free distance time, which is a time between a trailing edge of an outgoing sheet and a leading edge of a subsequent sheet, may be reduced. As the free distance between successive sheets is reduced the diverter of the sheet diverting unit needs to switch faster between the first deflector position and the second deflector position. However faster switching, i.e. faster pivoting of the deflector, may lead to uncontrolled positioning of the deflector in the first deflector position and in the second deflector position. Furthermore the outgoing sheet may become damaged at a trailing edge by a fast switching deflector. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a sheet diverter unit for increasing the productivity of cut sheets in a transport path by supporting a shorter free distance between successive sheets and/or support a shorter free distance time between successive sheets. 
     The present invention provides a sheet diverting unit for selectively diverting a sheet towards a first receiving path or a second receiving path, comprising: an inlet path arranged for advancing a sheet in a sheet supply direction towards a diverter; the diverter comprising a shaft, a deflector being connected to said shaft and extending between said shaft and a tip, and an actuator arranged for rotating the shaft thereby selectively pivoting the deflector between a first deflector position for directing the sheet into the first receiving path and a second deflector position for directing the sheet into the second receiving path; said deflector comprising a guiding edge and a second edge, said second edge arranged facing a second trajectory to the second receiving path in the second deflector position for directing the sheet into the second receiving path and said guiding edge arranged facing a straight first trajectory to the first receiving path thereby said guiding edge facing a guiding element in the first deflector position for guiding the sheet into the first receiving path characterized in that the guiding edge comprises a recess portion, the recess portion being arranged inwardly away from the straight first trajectory to the first receiving path when the deflector is arranged in the first deflector position, wherein the recess portion is arranged for extending substantially from the guiding element towards the shaft when the deflector is arranged in the second deflector position. 
     The recess portion of the guiding edge is shaped for guiding the sheet into the first receiving path in the first deflector position. The recess portion further provides a cavity in the straight first trajectory to the first receiving path in the second deflector position, which recess portion is arranged for extending substantially from the guiding element, such as a baffle, towards the shaft, thereby providing space for a shorter free distance between successive sheets. As defined herein the recess portion extending substantially from the guiding element towards the shaft when the deflector is arranged in the second deflector position means that the recess portion extends over at least a part of a width of the first trajectory, wherein the recess portion is arranged for allowing a trailing edge of an outgoing sheet, which is present in the straight first trajectory, to advance further along the straight first trajectory to the first receiving path. As such, the recess portion is suitably arranged proximate to the guiding element or intersecting the guiding element, while extending over at least a part of the width of the first trajectory. In this way, the outgoing sheet is not obstructed or damaged by the guiding edge of the deflector when the deflector is moved from the first deflector position to the second deflector position when said outgoing sheet is still in the straight first trajectory to the first receiving path. 
     The recess portion may extend from the guiding element over a part of the width of the first trajectory to the first receiving path or may extend over the entire width of the first trajectory to the first receiving path when the deflector is arranged in the second deflector position. The width of the straight first trajectory is defined as being lateral to the advancing direction of the sheet along the first trajectory. 
     Additionally, the recess portion may be arranged for additionally extending outside the width of the first trajectory, thereby protruding the guiding element towards the tip when the deflector is arranged in the second deflector position. 
     The outgoing sheet in the first trajectory to the first receiving path may have a trailing edge present facing the guiding edge, while the deflector is already switched into the second deflector position for directing a subsequent sheet into a second receiving path. Thus the recess portion according to the present invention provides a cavity for accommodating the trailing edge of the outgoing sheet, thereby allowing a shorter free distance between successive sheets by allowing an earlier switching of the deflector into the second deflector position. 
     The recess portion may have an acute angle with respect to a downstream portion of the guiding edge arranged downstream of the recess portion, wherein said acute angle is selected to be at most a maximum acute angle, such as 15°, for controllably guiding the sheet along guiding edge. As a result a leading edge of the sheet which is curved towards the guiding edge is reliably guided along the guiding edge. Said downstream portion of the guiding edge is preferably arranged substantially parallel to the straight first trajectory to the first receiving path. 
     The recess portion may have a concave shape curved inward away from the straight first trajectory to the first receiving path, may have a tapered shape arranged away from the straight first trajectory to the first receiving path, and may have any other shape suitable for allowing an outgoing sheet advancing along the shaft. 
     In a particular example of the recess portion, an upstream part of the recess portion has an upstream acute angle away from the first receiving path being steeper than a downstream part of the recess portion having a downstream acute angle towards the first receiving path. The upstream part of the recess portion in the sheet transport direction may for example have an angle of about 45°-90° away from the first receiving path in the first deflector position. 
     In an embodiment, the recess portion is arranged for providing a cavity in the straight first trajectory to the first receiving path, wherein the cavity is arranged for accommodating a trailing edge of an outgoing sheet when the deflector is arranged in the second deflector position, thereby allowing a reduction in distance between successive sheets. The cavity in the straight first trajectory to the first receiving path in the second deflector position allows and does not obstruct the outgoing sheet, in particular a trailing edge of the outgoing sheet, advancing in the first trajectory to the first receiving path. As a result the trailing edge of the outgoing sheet is not damaged by the guiding edge of the deflector in the second deflector position and a shorter free distance between successive sheets is supported. 
     In an embodiment, wherein the second edge is a curved edge arranged for deflecting the sheet into the second receiving path. This embodiment supports a second receiving path which is arranged in an arched direction away from the sheet supply direction. This may be useful for selectively splitting off sheets from a main transport path continuing in the sheet supply direction. The second receiving path in this embodiment may for example be part of a circulating path, such as a duplex path, and may be part of an error sheet removal path. 
     In an embodiment, the guiding element is a baffle. A baffle is a common guiding element for guiding the sheet along a transport path or trajectory. The baffle may be suitable shaped in a straight direction for guiding the sheet along the first trajectory to the first receiving path. The baffle may comprise a hole for receiving a portion of the deflector, e.g. the tip of the deflector, when the deflector is arranged in the second deflector position. In this way, the baffle allows the deflector to be moved towards a second deflector position wherein the deflector partially protrudes the baffle. As such, the receiving hole supports a reliable guiding of the sheets towards the first receiving path. 
     In an embodiment, said guiding edge comprises a straight portion, which is arranged substantially parallel to the guiding element of the straight first trajectory to the first receiving path when the deflector is arranged in the first deflector position. The recess portion is curved inwardly away from the straight direction of the first trajectory to the first receiving path and/or is curved inwardly away from the straight portion of the guiding edge. 
     In an embodiment, the straight portion of guiding edge and the straight first trajectory to the first receiving path are arranged substantially parallel to the sheet supply direction. In this embodiment the sheet is guided along the first trajectory into the first receiving path without deflecting the sheet as such, thereby minimizing loads on the deflector. In a particular example, the first trajectory to the first receiving path is arranged in line to the inlet path. 
     In an embodiment, the recess portion is shaped having an acute angle being not larger than 15° with respect to the first trajectory to the first receiving path when the deflector is arranged in the first deflector position. The acute angle of the recess portion towards the first trajectory to the first receiving path being not larger than 15° supports a reliable guiding of a leading edge of the sheet into the first receiving path in the first deflector position. In case the angle is larger than 15° a leading edge of the sheet may be obstructed by the recess portion, for example in case of a leading edge curling towards the guiding edge of the deflector. 
     In an embodiment, the tip comprises a front edge arranged at an acute angle being at most 30° with respect to the guiding edge. The acute angle of the front edge being at most 30° supports a guiding of the sheet into the first receiving path in the first deflector position. 
     In an embodiment, the diverter of the sheet diverting unit comprises a plurality of deflectors distributed along an axial direction of the shaft, each deflector comprising said guiding edge arranged facing the first trajectory to the first receiving path in the first deflector position for guiding the sheet into the first receiving path, wherein the guiding edge comprises said recess portion. The plurality of deflectors supports a relative light weight and fast switchable diverter between the second deflector position and first deflector position. 
     In an embodiment, each deflector has a first side surface and a second side surface arranged at both sides of the deflector in an axial direction of the shaft, wherein both first and second side surfaces of at least one of the plurality of deflectors is arranged at an acute angle away from the sheet supply direction. The axial direction of the shaft is arranged substantially perpendicular to the sheet supply direction. The acute angle of both the first and second side surfaces supports guiding of side edges of the sheet in the sheet supply direction along the diverter. The side edges of the sheet do not get obstructed at the side surfaces of the deflector even in case of small lateral movements in the axial direction perpendicular to the sheet supply direction. 
     In an embodiment, a first acute angle of said first side surface is smaller than a second acute angle of said second side surface facing towards an end of the shaft in the axial direction. In this embodiment the guide edge is a tapered edge from the tip to the shaft in the sheet supply direction. This shape supports a fast switchable deflector providing proper guiding of the sheet along the shaft. 
     In an embodiment, the guiding edge is arranged along the shaft at a distance between the guiding edge and the shaft, which is at least a predetermined distance for guiding the sheet away from the shaft. The predetermined distance from the shaft is selected such that a leading edge and/or a corner of the sheet is guided away from the shaft. As a result a reliable guidance of the sheet along the shaft is obtained. The predetermined distance may be for example 5 mm. The predetermined distance may be determined based on a distance between adjacent deflectors in the axial direction of the shaft. 
     In an embodiment, the curved edge has a radius of at least 100 mm. In this embodiment the sheet is deflected into the second receiving path thereby minimizing loads on the deflector during deflection of the sheet. This supports a smaller size and/or weight of the deflector and especially a smaller size and/or weight of the tip of the deflector. The relative light weight deflector supports a fast switchable diverter between the first deflector position and second deflector position. 
     In another aspect of the present invention a printing system is provided for printing on a sheet comprising a transport path for transporting said sheet along a printing station arranged for printing on said sheet, said transport path comprising a sheet diverting unit according to the present invention. 
     In another aspect of the present invention a sheet handling device is provided comprising a transport path for transporting successive sheets through the sheet handling device, said transport path comprising a sheet diverting unit according to the present invention. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Hereinafter, the present invention is further elucidated with reference to the appended drawings showing non-limiting embodiments and wherein 
         FIG. 1A  shows a schematic view of an inkjet printing system in which a sheet diverting unit according to the present invention may be used. 
         FIGS. 2A-2C  show a sheet diverting unit comprising a diverter known in the prior art. 
         FIGS. 3A-3B  show a side view of a sheet diverting unit according to an embodiment of the present invention in respectively a first deflector position and a second deflector position. 
         FIG. 3C  shows a detailed view of a diverter in the first deflector position of the sheet diverting unit shown in  FIG. 3A . 
         FIG. 4  shows a detailed view of a modified deflector in the first deflector position of a sheet diverting unit according to the present invention. 
         FIGS. 5A-5B  show a perspective view and a plane view respectively of a sheet diverting unit according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views. 
     Referring to  FIG. 1A  a inkjet printing system  1  is shown including an image forming device or inkjet marking module  9 , where image formation is carried out by ejecting ink from inkjet marking device  91 ,  92 ,  93 ,  94  arranged so that a whole width of a sheet S is covered. That is, the image forming device  9  comprises an inkjet marking module having four inkjet marking devices  91 ,  92 ,  93 ,  94 , each being configured and arranged to eject an ink of a different color (e.g. Cyan, Magenta, Yellow and Black). Such an inkjet marking device  91 ,  92 ,  93 ,  94  for use in single-pass inkjet printing typically has a length corresponding to at least a width of a desired printing range, with the printing range being perpendicular to the media transport direction along the transport path P. 
     In this regard, it will be noted that the printing system  1  in  FIG. 1A  has a transport path P which includes both a simplex path P S  and a duplex path P D . A sheet diverting unit  80  is arranged at the parting position of the simplex path P S  and the circulating duplex path P D  downstream of the image forming device  9 , which sheet diverting unit  80  is arranged for diverting a sheet being processed in the image forming device  9  selectively to either the output path as shown for a sheet S OUT  or to the circulating duplex path P D  for a duplex sheet S D . Said sheet diverting unit  80  may for example be the sheet diverting unit according to the present invention. 
     Said inkjet printing system  1  further includes an apparatus  60  for detecting defects in the printing system  1 , and particularly for identifying and for classifying deformations D in the sheets S of print medium when the sheets S are on the transport path P of the printing system  1 . In this particular inkjet printing system, the apparatus  60  comprises a sensing unit  61 , which processes the sheets S IN  on the transport path P before those sheets S IN  enter the image forming device  9 . The sensing unit  61  of the apparatus  60  is arranged such that sheets S input on the simplex path P S  and also returning on the duplex path P D  all pass via the sensing unit  61 . 
     At least one first sensor device  62  in the form of an optical sensor, such as a laser scanner, is provided within the sensing unit  61  for sensing the surface geometry or topology of the sheets S as they travel on a first pass or a second pass along the transport path P. The laser scanner or optical sensor device  62  generates digital image data I of the three-dimensional surface geometry or topology of each sheet S sensed or scanned. When performing the sensing or measuring of the surface geometry or topology of the sheets S on the transport path P of printing system  1  with the first sensor device(s)  62 , it is highly desirable for the purposes of accuracy and reliability that the sheets S are transported or conveyed in the sensing unit  61  in substantially the same manner as those sheets S are later transported in the image forming unit or marking module  9 . To this end, the sensing unit  61  includes a sheet conveyor mechanism  63  that simulates the sheet transport conditions provided by the transport mechanism  3 ′ within the image forming unit  9 . In this regard, both the conveyor mechanism  63  and the transport mechanism  3 ′ include a belt transport device with vacuum sheet-holding pressure, as seen in  FIG. 1A . 
     The sheet topology data from the first sensor device  62  is then transmitted (e.g. either via a cable connection or wirelessly) to a controller  64  which includes a processor device  65  for processing and analyzing the digital image data I to detect and to classify any defect or deformation D in the surface geometry or topology of each sheet S sensed or scanned. The sensing unit  61  is thus arranged to scan the sheets S for detecting and measuring any deformations or defects D before the sheets S enter the image forming device or inkjet marking module  9 . In this way, if the processor device  65  determines that a sheet S on the transport path P includes a defect or deformation D that would render the sheet unsuitable for printing, the controller  64  is configured to prevent the sheet S from progressing to the inkjet marking module  9 . The sensing unit  61  comprising the first sensor device(s)  62  is therefore desirably provided as a separate sentry unit positioned on the transport path P sufficiently upstream of the marking module  9 . 
     After the image data I has been analyzed by the processor  65  and the defects or deformations D within the sheet S have been extract and classified accordingly, the controller  64  may transmit a control signal (either via cable or wirelessly) to a removal device or ejector device  66  for regulating the transport or conveyance of the sheets S to the image forming device or inkjet marking module  9 . In particular, if the sheet S has been determined by the processor  65  to include one or more deformations D with a size or extent above a predetermined threshold sufficient to render the sheet unsuitable for printing, the controller  64  is configured to control or operate the removal device  66  to remove or eject the sheet S from the transport path P to a reject tray  67 . In this way, sheet jams within the print module or image forming device  9  may be avoided when sheets S are found to contain too much deformation. The removal device  66  located between the sentry unit  61  and the inkjet marking module  9  can employ different means optimized for redirecting the sheets S from the transport path P towards the reject tray  67 . 
     In particular the removal device  66  may employ a sheet diverting unit according to the present invention, wherein a first receiving path may be the advancing transport path towards the image forming device  9  and wherein a second receiving path may be an arched outlet path deflecting away from the transport path P towards the reject tray  67 . 
     In  FIG. 2A  a prior art sheet diverting unit  80  is shown comprising an inlet path  10  for advancing a sheet  2   a  in a sheet supply direction S towards a diverter  50 . Said inlet path  10  comprises baffles  10 ,  12  arranged at both sides of the inlet path  10  for guiding the cut sheet  2   a  towards said diverter  50 . The diverter  50  may be selectively arranged for diverting the sheet  2   a  towards a second receiving path  20  as indicated by arrow R 1 , such as said circulating duplex path, or towards a first receiving path  30  as indicated by arrow R 2 , such as an output path towards the sheet output station. The diverter  50  comprising a shaft  52  being arranged in an axial direction perpendicular to the plane of viewing, a deflector  53  being connected to said shaft  52  and extending between said shaft  52  and a tip  54 . Said tip  54  is arranged towards the inlet path  10  upstream of the shaft  52  relative to the sheet transport direction S. 
     An actuator (not shown) is arranged for rotating the shaft along arrow X thereby selectively pivoting the deflector between a second deflector position for directing the sheet  2   a  into the second receiving path  20  and a first deflector position, as is shown in  FIG. 2A , for directing the sheet  2   a  into the first receiving path  30 . The second receiving path  20  comprises baffles  22 ,  24  arranged at least in part at both sides of the second receiving path  20  for guiding the sheet  2  along the second receiving path  20 . The first receiving path  30  comprises baffles  32 ,  34  arranged at least in part at both sides of the first receiving path  30  for guiding the sheet  2  along the first receiving path  30 . 
     The deflector  53  comprises a curved edge  56  and a guiding edge  58 . Said curved edge  56  is arranged facing a second trajectory  26  to the second receiving path  20  in the second deflector position (as is also shown in  FIG. 2C ) for deflecting the sheet  2  into the second receiving path  20 . Said guiding edge  58  is arranged facing a first trajectory  36  to the first receiving path  30  in the first deflector position, as is shown in  FIG. 2A  and in  FIG. 2B , for guiding the sheet  2   a ,  2   b  along the first trajectory into the first receiving path  30 , for example a straight path or first trajectory  36  arranged in line with inlet path  10  as is shown in  FIG. 2A . 
     The guiding edge  58  is shaped substantially straight and is arranged in the first deflector position substantially parallel to the first trajectory  36  to the first receiving path  30 . As long as the outgoing sheet  2   b  advancing in the first receiving path  30  is facing the first trajectory  36  to the guiding edge  58  said diverter  50  may not be switched towards a second deflector position as the guiding edge  58  may damage or hinder a trailing edge of the sheet  2  from advancing in the first receiving direction R 2 . 
     In  FIG. 2B  schematically is shown the first trajectory  36  to the first receiving path  30 . The first trajectory  36  extends along the guiding edge  58  of the deflector  53 , as is indicated by the dotted lines, between the inlet path  10  and the first receiving path  30 , when the deflector  53  is arranged in the first deflector position. 
     In  FIG. 2C  schematically is shown the second trajectory  26  to the second receiving path  20 . The second trajectory  26  extends along the curved edge  56  of the deflector  53  as is indicated by the dotted lines between the inlet path  10  and the second receiving path  20 , when the deflector  53  is arranged in the second deflector position. 
       FIGS. 3A-3B  show a side view of a sheet diverting unit according to an embodiment of the present invention in respectively a first deflector position and a second deflector position. The sheet diverter unit  100  comprises a diverter  120 , which comprises a shaft  122  being arranged in an axial direction perpendicular to the plane of viewing, a deflector  123  being connected to said shaft  122  and extending between said shaft  122  and a tip  124 . Said tip  124  is arranged towards the inlet path  10  upstream of the shaft  122  relative to the sheet transport direction S. 
     An actuator (not shown) is arranged for rotating the shaft  122  along arrow X thereby selectively pivoting the deflector  123  between a second deflector position (as shown in  FIG. 3B ) for directing the sheet  2  into the second receiving path  20  and a first deflector position (as is shown in  FIG. 3A ) for directing the sheet  2  into the first receiving path  30 . The deflector  123  comprises a curved edge  126  and a guiding edge  128 . Now referring to  FIG. 3B  said curved edge  126  is arranged facing a second trajectory  26  to the second receiving path  20  in the second deflector position for deflecting the sheet  2   b  into the second receiving path  20  as indicated by arrow R 1 . Said guiding edge  128  is arranged facing a first trajectory  36  to the first receiving path  30  in the first deflector position, as is shown in  FIG. 3A , for guiding the sheet  2   a  into the first receiving path  30  as indicated by arrow R 2 . For example said first trajectory  36  including the first receiving path  30  may be a straight path arranged in line with inlet path  10  as is shown in  FIG. 3A . 
     The guiding edge  128  comprises a recess portion  130  which is curved inwardly away from the straight first trajectory  36  to the first receiving path  30 . The recess portion  130  of the guiding edge  128  is shaped concavely and provides a cavity  132  in the first trajectory  36  to the first receiving path  30 . The cavity  132  provided by the recess portion  130  is an additional space in the first trajectory  36  enclosed as schematically indicated in  FIG. 3A-3C  by the dotted line and the guidance edge at the recess portion  130 . The dotted line indicates a virtual position of a straight guiding edge, such as a guiding edge shown in  FIG. 2A , without any recess portion according to the present invention. 
     Now referring to  FIG. 3C  a detailed view of the diverter is shown in the first deflector position of the sheet diverting unit shown in  FIG. 3A . The recess portion  130  of the guiding edge  128  is shaped concavely and the cavity  132  is indicated by the dotted line and the guidance edge at the recess portion  130 . The guiding edge  128  further comprises a portion  129 , which is arranged downstream of the recess portion  130 , and which portion  129  is arranged substantially parallel to the first trajectory  36  to the first receiving path  30  and substantially parallel to the baffle  32  along the shaft  122  and the first receiving path  30 . A sheet advances along the first receiving path  30  in a direction as indicated by R 2 . The recess portion  130  has an acute angle α with respect to the direction R 2  of the sheet in the first receiving path  30 , which is at most a maximum angle being 15°. In case the acute angle α is larger than 15°, leading edges of a sheet which are curved towards the guiding edge  128  may become obstructed in the first receiving path  30  due to the acute angle of the recess portion  130 . 
     The guiding edge  128  is arranged at a distance d from the shaft  122  such that any leading edges and/or corners of sheets are guided easily along the shaft  122 . Said distance is at least equal to or larger than a predetermined distance for reliable guiding the sheets along the shaft  122  of the diverter  120 . 
     In case of a diverter comprises a plurality of deflectors  123  distributed along an axial direction of the shaft  122  the predetermined distance depends on a distance between adjacent deflectors in the axial direction. 
     The recess portion  130  may have an upstream part relative to the sheet transport direction S (or direction R 2 ) having an acute angle β away from the first receiving path  30 . Said acute angle β may be steeper than the acute angle α, such as between 45° and 90°, as the upstream part of the recess portion does not obstruct any leading edges of sheets moving along the first receiving path  30  in the direction R 2 . 
     The deflector  123  shown in  FIG. 3C  comprises a tip  124 , which comprises a front edge  125 , wherein said front edge  125  is arranged at an acute angle χ being at most 30° with respect to the guiding edge  128  and/or the first receiving path  30  in the first deflector position as shown in  FIG. 3C . The acute angle of the front edge being at most 30° supports a guiding of the sheet into the first receiving path in the first deflector position. As the front edge  125  is at least partly covered by baffle  14 , the angle χ of the front edge is less critical than the acute angle α of the recess portion  130 . 
     Now referring to  FIG. 3B  the shaft  122  is rotated to pivot the deflector  123  to the second deflector position wherein a subsequent sheet  2   b  is deflected by the curved edge  126  into the second receiving path  20 . At the same time a trailing edge  2 ′ of the outgoing sheet  2   a  in the first trajectory  36  to the first receiving path  30  is not damaged or obstructed by the guiding edge  128  as the recess portion  130  provides space (i.e. by the cavity  132 ) for accommodating the trailing edge  2 ′ of the outgoing sheet  2   b  inside the first receiving path  30 . The recess portion  130  extends from the baffle  32  towards the shaft  122 , thereby arranging the cavity  132  extending over at least a part of the width of the first trajectory  36  to the first receiving path  30  from the baffle  32  towards the shaft  122 . As a result a free distance I S  between successive sheets  2   a  and  2   b  may be reduced without damaging and/or obstructing the trailing edge  2 ′ of sheet  2   b  inside the first receiving path  30 . 
     Now referring to  FIG. 4  a detailed view of a modified deflector is shown in the first deflector position of a sheet diverting unit according to the present invention. The diverter  220  has a deflector  223  having a recess portion  230  of the guiding edge  228 , which has a tapered shape and provides a cavity in the first trajectory  36  to the first receiving path  30 , which is an additional space defined as indicated by the dotted line, virtually indicating a straight trajectory, and the guidance edge at the recess portion  230 . 
     The guiding edge  228  further comprises a portion  229 , which is arranged downstream of the recess portion  230 , and which portion  229  is arranged substantially parallel to the first trajectory  36  to the first receiving path  30  between the shaft  222  and the first receiving path  30 . A sheet advances along the first trajectory  36  to the first receiving path  30  in a direction as indicated by R 2 . The recess portion  230  has a guiding part  231  having an acute angle α with respect to the direction R 2  of the sheet in the first trajectory  36  to the first receiving path  30 , which is at most a maximum angle being 15°. In case the acute angle α is larger than 15°, leading edges of a sheet which are curved towards the guiding edge  228  may become obstructed in the first trajectory  36  to the first receiving path  30  due to the acute angle of the recess portion  230 . 
     The recess portion  230  comprises an upstream part  233  relative to the sheet transport direction S (or direction R 2 ) having an acute angle β away from the first trajectory  36  to the first receiving path  30 . Said acute angle β may be steeper than the acute angle α, such as between 45° and 90°, as the upstream part of the recess portion  233  does not obstruct any leading edges of sheets moving along the first trajectory  36  to the first receiving path  30  in the direction R 2 . 
     The recess portion  230  may additionally comprise a base part arranged between the upstream part  233  and the guiding part  231 , wherein said base part is directed substantially parallel to the first trajectory  36  to the first receiving path  30 . 
       FIGS. 5A-5B  show a perspective view and a plane view respectively of a sheet diverting unit according to an embodiment of the present invention. 
     Now referring to  FIG. 5A  the diverter of the sheet diverting unit  300  comprises a shaft  122 . Said shaft  122  has an axial direction A which extends perpendicular to a sheet transport direction S. A plurality of deflectors  123   a ,  123   b ,  123   c  which are distributed along said shaft  122 . Each of the plurality of deflectors  123   a ,  123   b ,  123   c  has a curved edge and a guiding edge including a recess portion as shown in  FIG. 3C . Further each of the plurality of deflectors  123   a ,  123   b ,  123   c  are plate like structures having a first side surface  142  and a second side surface  144  arranged at both sides of the deflector  123  in an axial direction A of the shaft  122 . 
     An actuator  140  is arranged at both ends of the shaft  122   a ,  122   b  for controllably rotating the shaft  122  in a direction X, thereby selectively pivoting the deflectors  123   a ,  123   b  and  123   c  between a second deflector position (as shown in  FIG. 3B ) for directing the sheet  2  into a second receiving path  20  and a first deflector position (as is shown in  FIG. 3A ) for directing the sheet  2  into a first receiving path  30 . Each of the deflectors  123   a ,  123   b ,  123   c  have a guiding edge comprising a recess portion, for example as shown in  FIG. 3C  or as shown in  FIG. 4 . The recess portions of the plurality of deflectors  123   a ,  123   b ,  123   c  are substantially aligned in the axial direction A such that a trailing edge of an outgoing sheet is not obstructed by any of the deflectors  123   a ,  123   b ,  123   c  in the second deflector position. 
     Now referring to  FIG. 5B  a first set of deflectors  123   a  is arranged in a middle portion of the shaft  122  relative to the axial direction A. In each of said first set of deflectors  123   a  both side surfaces  142 ,  144  are arranged substantially parallel to the sheet transport direction S. 
     A second set of deflectors  123   b  is arranged in a lateral portion of the shaft  122  in a direction L 1  relative to the axial direction A to a first end of shaft  122 . In each of said second set of deflectors  123   b  both side surfaces  142 ,  144  are arranged at an acute angle δ, ε respectively with respect to the sheet transport direction S, wherein a first acute angle δ of said first side surface  142  is smaller than a second acute angle ε of said second side surface  144  facing towards an end of the shaft  122  in the axial direction A. 
     A third set of deflectors  123   c  is arranged in a lateral portion of the shaft  122  in a direction L 2  relative to the axial direction A to another end of shaft  122  opposite to the first end of shaft  122 . In each of said second set of deflectors  123   c  both side surfaces  142 ,  144  are arranged at an acute angle δ, ε respectively with respect to the sheet transport direction S, wherein a first acute angle δ of said first side surface  142  is smaller than a second acute angle ε of said second side surface  144  facing towards an end of the shaft  122  in the axial direction A. 
     In an example the first acute angle δ is about 5-15° and the second acute angle ε is about 20-30°. 
     Both side surfaces  142 ,  144  of the second and third set of deflectors  123   b ,  123   c  reliably guide side edges of sheets moving through the sheet diverting unit  200  from the inlet path  10  towards either one of the second receiving path  20  or the first receiving path  30 . 
     Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any advantageous combination of such claims is herewith disclosed. 
     Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the present invention. The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly. 
     The present invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.