Abstract:
A printing apparatus has a sheet path and is adapted to produce print job sheets and dividing sheets. The apparatus includes a printing unit for printing the print job sheets. A first device in the sheet path downstream of the printing unit generates dividing sheets. The device includes a deforming unit with a stamp for punching and deforming a partial area of a dividing sheet so that a hook-shaped deformation is imparted in the dividing sheet. An output tray is arranged in the sheet path downstream of the first device and includes an inclined support for receiving the print job sheets and the dividing sheets.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/EP2010/054157, with an international filing date of Mar. 30, 2010 which is incorporated herein by reference in its entirety. 
     This application is co-filed with and has related subject matter to U.S. patent application Ser. No. 13/253,093filed Oct. 5, 2011. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to dividing print jobs for a sheet-processing machine, in particular for a printing machine. 
     BACKGROUND OF THE INVENTION 
     When printing different or identical print jobs that are printed in multiple copies, it is desirable to separate said print jobs for the user at the delivery point and to identify where one print job ends and the next one starts. Regarding this, several possibilities for dividing jobs are known. 
     For example, a dividing sheet can be interposed between print job sheets that are to be placed on top of each other, the format of said dividing sheet being different from the format of the print job sheets that are to be divided, and, in particular, having a larger format. In order to ensure an automated operation of the printing machine, it is practical to transport said dividing sheets out of a feeder that is located in the printing machine. Inasmuch as, however, the dividing sheets must be different from the format of the print jobs to be generated, a feeder is now loaded with dividing sheets that do not participate in the value-added function of the print job, but occupy a feeder and thus lower the productivity of the printing machine because—as a result of the reduced number of usable feeders—the remaining feeders must be loaded more frequently. 
     Furthermore, there is the possibility of transporting print jobs to an output tray module that consists of several trays arranged in a fan-like manner and that receives a single print job in each tray as is known, for example, from copiers. An output tray that is configured in this manner is significantly more expensive and more susceptible to paper jams than a simple plate-like tray. In addition, due to the number of fan-like arranged plate-like trays in a relatively confined space, their respective stacking height is limited, thus impairing the output of large print jobs in view of the number of pages. 
     Furthermore, it has been known to move lateral guides of an output tray in lateral direction in order to guide individual print jobs into an end position on the output tray that is different from that of the previous job. On the one hand, such a modification is expensive and, on the other hand, it involves problems in view of the use of an additional substrate and format range of the printing sheet. 
     Beyond that, it is possible to use another type of output tray, e.g., a rotating or oscillating tray that, due to its principle of operation, allows the sheets to be shifted transversely to their transport direction. These output trays can fulfill the function of the print job division using an offset function, as it were; however, they are significantly more expensive than a plate-like output tray. 
     Consequently, it is the object of the present invention to simply divide different or identical print jobs that are to be successively fed to a plate-like output tray of a sheet printing machine. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, there is provided a printing apparatus having a sheet path and adapted to produce print job sheets and dividing sheets, the apparatus comprising: 
     a printing unit for printing the print job sheets; 
     a first device in the sheet path downstream of the printing unit for generating dividing sheets, the device including a deforming unit with a stamp for punching and deforming a partial area of a dividing sheet so that a hook-shaped deformation is imparted in the dividing sheet; and 
     an output tray in the sheet path downstream of the first device, the output tray including an inclined support for receiving the print job sheets and the dividing sheets. 
     In various embodiments, a method is provided for dividing print jobs in an output tray of a printing machine, wherein, when a print job is running, the sheets are initially output onto an inclined support of the tray, and the sheets subsequently slide against an abutment of the output tray. Upon completion of the print job and before running the next print job, a dividing sheet is placed on the stack of sheets located in the output tray, whereby, before the output of the dividing sheet, said dividing sheet is imparted with a hook-shaped deformation so that it is possible for the deformation of the dividing sheet to be propped up against the stack formed by the previous print job. As a result of this, the dividing sheet projects from the remaining sheets of the stack underneath and allows an easy identification of the end of the print job. The dividing sheet also projects from the sheets of a print job that is subsequently deposited thereon and thus marks a clear separation between said print jobs. The ejection of a dividing sheet can occur between a plurality of successive print jobs. 
     Preferably, when being delivered to the output tray, the dividing sheet overshoots the stack that has been previously formed by delivered sheets and subsequently slides back in the direction of the abutment. The hook-shaped deformation of the dividing sheets is then propped up against the stack when said deformation comes into contact with a stack edge and prevents a further sliding back. 
     The hook-shaped deformation in the dividing sheet can be imparted in the center, for example, in order to ensure that the dividing sheet is securely held and in order to prevent the dividing sheet from shifting relative to the stack of sheets underneath. 
     Inasmuch as, directly upon leaving the sheet path, some plate-like output trays slow down the sheets with an actively controlled pair of rollers in order to improve stack accuracy, it can be necessary to decelerate less severely the sheets that have been deformed into dividing sheets, so that the hook-shaped deformation can reliably overshoot a stack edge formed under said deformation. By imparting the hook-shaped deformation it is thus prevented that the sheet descending on the plate-like tray slides back up to a stack guiding plane. Thus, the dividing sheet projects beyond the stack of the previous print job below said dividing sheet and also projects beyond the stack of the subsequent print job to be formed thereon. 
     Furthermore, the sheet that is to be deformed can be printed in an information field addressed to the user, where the information field printed on the sheet can contain information regarding, for example, a job name, an edition, or a sheet property, etc. Preferably, the format of the dividing sheet is the same as the format of the other sheets used for print jobs. Therefore, the sheet used as the dividing sheet can be transported out of the same or out of another feeder using the same sheet format. Therefore, there is no need to transport the dividing sheets out of a separate, specifically provided feeder of the printing machine. As a result of this, improved productivity of the printing machine is achieved. 
     The hook-shaped deformation in the dividing sheets is preferably imparted offset relative to transport rollers of the printing machine, for example between adjacent pairs of transport rollers, in a direction transverse to the sheet transport direction. This ensures that the hook-shaped deformation imparted by the punch-type deforming unit in the dividing sheet does not come into contact with the transport rollers when the dividing sheet is delivered. Therefore, the hook-shaped deformation of the dividing sheet retains its shape during the output of the dividing sheet onto the output tray, so that the dividing sheet can be propped up against the stack formed by the previous print job. 
     In addition, the hook-shaped deformation can also be imparted during and with the movement of the dividing sheet. This can, for example, allow a reduction of the speed with which the punch-type deforming unit must be moved back and forth without impairing a movement of the sheet to the tray. The required speed of movement of the punch-type deforming unit results from the sheet velocity along the sheet path of the printing machine. As a rule, a deceleration of the sheet due to the punching and deforming operation is not desirable. Due to the movement of the punch-type deforming unit with the movement of the dividing sheet in transport direction, the punching and deforming operation can thus take place at a speed that is lower than that of a strict back-and-forth movement of the punch-type deforming unit in a direction orthogonal to the dividing sheet. 
     In accordance with one embodiment of the present invention, the hook-shaped deformation can be imparted in the dividing sheet using a rotating punch-type deforming unit, said unit being rotated synchronously with the sheet velocity, for example, when the punching and deforming operation is being performed. 
     Alternatively, in accordance with a further embodiment of the present invention, the hook-shaped deformation can be imparted in the dividing sheet by using a punch-type deforming unit that can be moved back and forth. In addition to the back-and-forth movement, such a punch-type deforming unit could also perform a movement in sheet transport direction. 
     Furthermore, in accordance with a preferred embodiment of the present invention, a device for dividing print jobs for a printing machine is provided, said device being an integral part of a sheet path of the printing machine and comprising a punch-type deforming unit with a stamp for punching and deforming a partial area of a sheet. 
     For example, the stamp can be coupled with an electric or pneumatic drive for the punching movement. A matrix can be provided under the stamp, said matrix acting as a counter-part to the stamp and thus allowing precise punching and deforming of the sheets. However, there need not necessarily be a matrix. Due to the fact that the sheets in the printing machine usually are held in place by transport rollers on both sides, the sheets exhibit a tension that makes it possible to punch and deform the sheets even with the application of only the stamp provided therefor. 
     Preferably, the stamp has at least one cutting edge. If the stamp is provided with only one cutting edge, the dividing sheet can be cut not in the middle but on the sides, and can subsequently be deformed. In accordance with a preferred embodiment of the present invention, the stamp is V-shaped. However, it is also conceivable that the stamp has a shape that is different therefrom, as long as the deformed partial area forms a hook and remains on the sheet, i.e., is not punched out completely. 
     The punch-type deforming unit can be configured in such a manner that it performs a linear back-and-forth movement in order to perform the punching operation. In order to avoid a delay caused by the punch-type deforming unit during the punching and deforming operation, it is advantageous if the punching operation is very short, this being achievable, for example, with the use of a piezo element. 
     In addition, it can be possible, for example, to move the punch-type deforming unit in sheet transport direction as well as in a direction orthogonal to a sheet plane. As a result of this, it is possible to synchronize the movement of the punch-type deforming unit with the sheet speed. This makes it possible, for example, to reduce the speed with which the punch-type deforming unit must be moved back and forth during the punching and deforming operation. The required speed of movement of the punch-type deforming unit results from the sheet velocity along the sheet path of the printing machine. As a rule, a deceleration of the sheet due to the punching and deforming operation is not desirable in this instance. Due to the movement of the punch-type deforming unit with the movement of the dividing sheet in transport direction, the punching and deforming operation can thus take place at a lower speed than with a strictly back-and-forth movement of the punch-type deforming unit in a direction orthogonal to the dividing sheet. 
     Alternatively, the punch-type deforming unit can comprise a rotatable element such as, for example, a roller with the stamp being provided on said roller. Preferably, the rotatable element can be rotated synchronously with the sheet transport speed—via a corresponding drive—when the punching and deforming operation is performed. The rotatable element has a starting position or idle position, in which the sheet can freely pass and in which it is positioned when no punching operation is being performed. If a punching operation is performed, the punch-type deforming unit is activated by the machine control in such a manner that the punch-type deforming unit initiates the punching operation, that the stamp arranged on the punch-type deforming unit rotates in synchrony with the sheet speed and punches, as well as deforms, the sheet at the desired position. For example, a partial area of the roller can be recessed in the form of a segmented roller, so that, depending on the position of the roller, said roller does not come into contact with the sheet when running a print job. 
     Preferably, the punch-type deforming unit is offset relative to the transport rollers of the printing machine and is arranged, in particular, between adjacent pairs of transport rollers transversely to the sheet transport direction. This ensures that the hook-shaped deformation imparted by the punch-type deforming unit will not come into contact with the transport rollers when the dividing sheet is being delivered. The hook-shaped deformation of the dividing sheet thus retains its shape when said dividing sheet is being delivered to the output tray, so that the dividing sheet can be propped up against the stack formed by the previous print job. 
     In various embodiments, a device for dividing print jobs is contained in a sheet printing machine, said machine comprising—downstream of the device for dividing print jobs—a plate-like output tray with an incline as well as with an abutment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, which are not necessarily to scale, in which: 
         FIG. 1  is a plan view of a dividing sheet having a partial area that is partially punched out and bent in a hook-shaped manner; 
         FIG. 2  is a side view of the sheet as in  FIG. 1 ; 
         FIG. 3  is a side view of a plate-like output tray loaded with three different print jobs that are separated by two different dividing sheets as in  FIG. 1 ; 
         FIG. 4  is a side view of a punch-type deforming unit in accordance with a first embodiment of the present invention; 
         FIG. 5  is a side view of a punch-type deforming unit in accordance with another embodiment of the present invention; 
         FIG. 6  is a cross-sectional view of the punch-type deforming unit as in  FIG. 4 , to show how said unit is arranged in a sheet path of a printing machine; and 
         FIG. 7  is a side view of a sheet printing machine. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Location and directional indications used in the description hereinafter primarily relate to the illustrations in the drawings and should thus not be viewed as being restricting. However, they can also relate to a preferred final arrangement. 
       FIG. 7  shows a schematic side view of a sheet printing machine  1  that comprises a feeder  2 , a transport device  3 , a printing unit  4 , a fusing unit  5  and an output tray  6 . 
     The feeder  2  can be of any type that is able to feed individual sheets to the transport device  3 . Of course, it is also possible to provide several feeders  2  in order to be able to feed different sheets  13  to the transport device  3 , for example. The transport device  3  comprises a suitable unit for receiving the fed sheets and for transporting said sheets past the printing unit  4  in order to allow printing the sheet. The unit can comprise a circulating transport belt, in the known manner, to which belt the sheet can be affixed electrostatically. The printing unit  4  can be any printing unit such as, for example, an electrophotographic printing unit or also an inkjet printing unit. Although only one printing unit  4  is shown, it is possible, for example, to also provide several printing units  4  adjacent to the transport device  3 . The fusing unit  5  is of a type suitable for fusing or drying printing medium applied to a sheet, before said sheet is fed to the output tray  6 . 
       FIG. 3  shows output tray  6 , plate-like output tray. The output tray  6  has an inclined support  10  that can be moved up and down by using a not-specifically-illustrated lifting mechanism, as indicated by the double arrow A. Furthermore, the output tray  6  of the printing machine  1  has an abutment  11  arranged adjacent to the support  10 . The support  10  is inclined toward the abutment  11 , so that a sheet  13  located on the support  10  slides against the abutment  11 , as indicated in  FIG. 3 . Furthermore, above the abutment  11 , the output tray  6  comprises pairs of transport rollers  14  that, between them, form a transport nip for the sheets  13 , as shown in  FIG. 3 . As shown in  FIG. 6 , two pairs of transport rollers  14  are provided, said rollers being disposed to receive and transport a sheet  13  between them in order to transport said sheet out of the printing machine  1  and onto the support  10  in the direction of the arrow C. 
     In addition, the output tray comprises a punch-type deforming unit  16  that is indicated, for example, in  FIG. 6 , and that is arranged between the pairs of transport rollers  14 .  FIG. 4  shows a first exemplary embodiment of the punch-type deforming unit  16  that comprises a drive element  18  and a stamp  19 . The stamp  19  can be moved up and down via the drive element  18 , as is indicated by the double arrow B in  FIG. 4 . The stamp is arranged in such a manner that, when it is moving downward, it crosses the path of movement of a sheet defined by the transport rollers  14 . To do so, the drive element  18  can comprise, for example, a pneumatic or piezo drive for the stamp  19 . Of course, also other drives are conceivable. 
     If, during the downward movement, a sheet  13  is located under the stamp  19 , a partial area of the sheet  13  is punched out and bent. In so doing, the partial area is always punched out in such a manner that it remains in contact with the sheet along a line of contact. To do so, the stamp  19  has—in a suitable manner—two blades that are arranged relative to each other so as to form a V-shape, said blades punching out the partial area of the sheet  13  along two straight lines, and has an area located between the blades that ensures that the punched-out partial area is being bent. It is also possible to optionally arrange matrix  20  below the stamp  19 , matrix  20  acting as a counter support for the sheet and ensuring reliable punching. Subsequently, such a sheet with a punched out and bent partial area can be used as the dividing sheet  13 ,  13 ′ as will still be explained in detail hereinafter. 
       FIG. 1  and  FIG. 2  show a schematic plan view and a schematic side view, respectively, of such a dividing sheet  13 ′ with a partial area that has been punched out in the above-described manner, said partial area having been bent into a hook-shaped deformation  24 . The deformation  24  is provided in the center, viewed in transverse direction of the dividing sheet  13 ′. Of course, the deformation can also be provided away from the center of the dividing sheet  13 ′ when viewed in transverse direction. In any event, the deformation  24  should be provided so as to be offset relative to the pairs of transport rollers  14  in transverse direction of the sheet  13 , so that said deformation is not being reformed by the transport rollers. In longitudinal direction, the deformation  24  is provided in the front end region, viewed in transport direction of the dividing sheet (indicated by the arrow C in  FIG. 1 ). Preferably, the deformation should be in the front third and, in particular, in the front fourth, of the sheet. An information field  26  is indicated between the front end of the sheet and the deformation  24 , where information can be printed on, for example, about a print job (prior to the punching and deforming operation). 
       FIG. 5  shows an alternative embodiment of the punch-type deforming unit  16 , where the same reference numerals as in  FIG. 4  are used for the same or similar elements. Again, the punch-type deforming unit  16  comprises a drive element  18  and a stamp  19  that essentially can have the same configuration as that of  FIG. 4 . The drive element  18  comprises a roller  28  that is provided with the stamp  19  on its outside circumference. The roller  28  can be selectively rotated via a corresponding drive (not illustrated), as is indicated by the arrow D. The roller  28  has a starting or idling position, in which the stamp  19  is positioned outside the path of movement of a sheet  13 , so that said sheet can be freely transported underneath and past the roller  28  when no punching operation is to be performed. However, due to a selective rotation of the roller  28 , it is also possible for the stamp  19  to plunge into a sheet  13  in order to again punch out and deform a partial area of said sheet. Subsequently, the sheet can be used as the dividing sheet  13 ′. 
     Hereinafter, the operation of the printing machine  1  and, in particular, a method for dividing print jobs will be explained in detail with reference to the figures. 
     Referring back to  FIG. 7 , first, the sheets  13  are transported out of the feeder  2  and past the printing units  4  of the printing machine  1  where they are printed in accordance with a print job. Such a print job can have a random number of sheets that are either identically or differently printed, as is known in the art. After printing the sheets, they are guided through the fusing unit  5  where a printing medium is fused in the known manner, and the sheets are subsequently transported to the output tray  6 . 
     Referring back to  FIG. 3 , the sheets  13  are ejected via the transport rollers  14  onto the inclined support  10  in such a manner that they land on the support  10  at a certain distance from the abutment  11  and then slide against the abutment  11  and, in so doing, form a stack  15 . Following the sheets of a print job (defined by the prespecified number of sheets that are to be considered one print job), another sheet  13  that is to act as the dividing sheet  13 ′ is transported out of the feeder  2  ( FIG. 7 ) past the printing units  4  ( FIG. 7 ) and is optionally printed in an information field  26  ( FIG. 1 ). After potential fusing of printing medium in the fusing unit  5  ( FIG. 7 ), the sheet  13  is transported to the output tray  6  ( FIG. 7 ). 
     Referring back to  FIG. 4 , in the region of the output tray  6  ( FIG. 3 ), the punch-type deforming unit  16  is then activated via a corresponding control unit in such a manner that the stamp  19  plunges into the sheet  13 , thus punching out and deforming a corresponding partial area of said sheet in order to generate a dividing sheet  13 ′ ( FIG. 3 ) with a deformation  24  ( FIG. 3 ). This punching operation preferably occurs while the sheet  13  is moved, without stopping the sheet, past the punch-type deforming unit  16 . Therefore, in the embodiment in accordance with  FIG. 4 , the up-and-down movement of the stamp  19  should be carried out with appropriate speed in order to avoid a hold-up in the movement of the sheet, if at all possible, or to at least reduce the risk of such a hold-up. To do so, the stamp could optionally perform a lateral movement with the movement of the sheet  13  in addition to the strict up-and-down movement. In the embodiment comprising the rotating stamp  19  ( FIG. 5 ), the rotation should be performed as synchronously as possible with a movement of the sheet  13 . It is also possible to slow the transport speed of the sheet  13  for the punching and deforming operation and to subsequently again accelerate the sheet for the output onto the support  10  ( FIG. 3 ). 
     Referring back to  FIG. 3 , the dividing sheet  13 ′ is then ejected via the transport rollers  14  onto the so-far-formed stack  15  of sheets  13  of the previous print job so that the deformation  24  is moved beyond a front edge of the stack  15 . 
     Subsequently, the dividing sheet slides back in the direction of the abutment  11 , whereupon the deformation  24  becomes hooked on one side of the stack  15  of sheets  13  of the previous print job, so that a complete sliding-back of the dividing sheet  13 ′ against the abutment is prevented. As a result of this, the dividing sheet  13 ′ projects by a certain distance from the stack  15  of sheets  13  of the previous print job, thus marking the end of said print job. Following that, a new print job can be started, where the sheets  13  of this new print job are again processed in the above-described manner and transported to the output tray  6 . There, they are again placed on the so-far formed stack  15  in such a manner that the sheets  13  slide against the abutment  11 .  FIG. 3  shows a situation in which the sheets  13  of three print jobs are divided by appropriate dividing sheets  13 ′. As is obvious from  FIG. 3 , the optionally printed information field  26  of the dividing sheet  13 ′ projects with respect to the rest of the stack  15 , so that an operator can easily detect printed information regarding the print job here. 
     The above description makes it clear that the same sheets can be used for the dividing sheets  13 ′ as can be used for the print jobs. By punching and deforming a partial area of the sheets and by a corresponding output onto an inclined support  10  of the output tray  6 , it is possible to reliably mark the divisions between print jobs. 
     Referring back to  FIG. 1 , in various embodiments, the stamp  19  can have a different shape, so that the partial area is not punched on two sides and bent along a third side into the deformation  24 . For example, instead of two blades arranged in a V-shape, the stamp can also have three blades to form a U-shape. It is only important that the partial area is not punched out completely and allows deformation. For example, in the region of the lateral edges of a sheet  13 , a single cut can be sufficient in order to allow the deformation of a partial area of the sheet. It is also possible to provide more than one punch-type deforming unit  16  in order to be able to provide several deformations  24  within a sheet. Although the support  10  ( FIG. 3 ) is inclined in such a manner that the sheets slide back against their delivery direction through the transport rollers, it is also possible for the support to have a different inclination, so that the sheets slide, for example, transversely to the delivery direction against a corresponding abutment, so that the deformation can be configured in an appropriately different manner (transverse to the ejection direction). Furthermore, it should be noted that compatible features of the different embodiments can be combined with each other or be exchanged for each other. 
     Although the present invention has been described in detail with exemplary embodiments, the invention is not restricted to the above-described embodiments. A person skilled in the field of printing machines could perform various modifications within the scope of this invention. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
     
         
           1  sheet printing machine 
           2  feeder 
           3  transport device 
           4  printing unit 
           5  fusing unit 
           6  output tray 
           10  support 
           11  abutment 
           13  sheet 
           13 ′ dividing sheet 
           14  transport rollers 
           15  stack 
           16  punch-type deforming unit 
           18  drive element 
           19  stamp 
           20  matrix 
           24  hook-shaped deformation 
           26  information field 
           28  roller 
         A arrow 
         B arrow 
         C arrow 
         D arrow