Abstract:
A sheet post processing machine has a first shelf for assembling a number of sheets without causing any inhibition to the speed of sheet delivery from a host printer or copier, and the assembled sheets are dumped from the first shelf to a second shelf at which the sheets are collected in sets, jogged into edge alignment, stapled at the corners or along an edge, the sets are offset from one another, and finally, dumped from the second shelf onto a stacker tray.

Description:
BACKGROUND OF THE INVENTION 
     With the advent of printers and digital copiers which produce sets or jobs at a high page per minute rate of production of printed sheets, there has become an increasing need for post processing machines which interface with the printer or copier and which function to collect the sheets into sets or jobs and finish the sets or jobs by stapling at either of the corners or, if desired, along the edge of a set or job. 
     On certain machines known in the prior art, the post processing machine also performs hole punching operations to enable the set of sheets or job to be bound into loose leaf binders, after having been stapled or not. 
     PRIOR ART 
     The need for assembling sheets in an assembly station prior to post processing is recognized in Lawrence U.S. Pat. No. 5,649,695, granted Jul. 22, 1997, wherein the machine is capable of continuously assembling sheets in an assembly station, and retracting a support from the trailing end of the sheets while gripping the sets and moving them into a finishing station before releasing the grip on the set and depositing the finished set on a tray. 
     In Canon U.S. Pat. No. 5,385,340, granted Jan. 31, 1995, for example, it is recognized that sheets may be assembled partially on a stacker tray and partially on a fixed shelf in a position for post processing, and then the processed sets may be pushed or displaced from the fixed shelf to the stacker tray. 
     In Coombs application, Ser. No. 280,599, filed Mar. 29, 1999 and co-owned herewith, it is recognized that sheets may be assembled on a stacker tray and on a shelf on which the sets of sheets are finished, as by stapling at their trailing end, and the stapled set is then dropped or dumped for dropping the set from the shelf completely onto a stacker tray. 
     In Coombs application, Ser. No. 078,202, filed May 14, 1998 and co-owned herewith, there is shown a sequentially operated apparatus in which sets of sheets or a job are assembled on a first tray which is then opened to drop sheets to a second tray for finishing. The second tray opens to drop the finished set onto a stacker tray. 
     SUMMARY OF THE INVENTION 
     The present invention relates to utilization of two stations, each having a shelf which is capable of being dumped. On the top shelf sheets are assembled in a number which may be less than an entire set so that as subsequent sheets making up a complete set are fed to the top shelf and dumped to the lower second shelf on which the completed set may be finished, so as to ultimately create a completed set, while additional sheets used in the composition of the next set are being fed onto the top shelf. 
     While the first referred to set is on the second shelf, the sheets can be progressively jogged into edge alignment, stapled, offset, if desired, and then dumped onto a stacker tray. 
     In such an apparatus, using a punch mechanism as the sheets are being fed to the top shelf, the sheets can also be punched on the fly so as to not inhibit the speed of input of the sheets from the printer or copier to the top shelf. 
     In the case that the sheets require inversion, which is a function of whether the sheet is exiting the printer or copier face up or face down, the post processing machine of the invention can include a simple inverter structure located so as to invert the sheets as they exit the printer or copier without inhibiting the speed of the printer or copier itself. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of the apparatus of the invention; 
     FIG. 2 is a vertical section with the side cover removed to show the internal mechanism, showing a number of sheets fed to the top shelf for assembly; 
     FIG. 3 is a section as in FIG. 2, but showing the first shelf dumped to deposit a number of sheets on the second shelf; 
     FIG. 4 is a section as in FIG. 3, but showing a set of sheets dumped by the first shelf and in position for offsetting and stapling on the second shelf, as additional sheets are supplied to the first shelf; 
     FIG. 5 is a fragmentary horizontal section showing the temporary support associated with the upper shelf for initially supporting the trailing ends of the sheets. 
     FIG. 6 is a horizontal section, as taken on the line  6 — 6  of FIG. 4 showing the stapling assembly at one side; 
     FIG. 7 is a view corresponding to FIG. 6 showing corner stapling of a set of sheets; and 
     FIG. 8 is a view corresponding with FIG. 6 showing edge stapling of a set in one location. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, there is shown an apparatus according to the invention including infeed means  1  having an inverter I and a paper feed path having appropriately drives feed rolls for delivering sheets to a first shelf S 1 , a lower shelf S 1 , a stapler S for finishing sheets on shelf S 2  and a stacker tray ST for receiving finished sets. 
     The apparatus may also have an upper receiving tray RT and a wheeled based support B to position the apparatus appropriately in relation to a printing or copying machine. In other cases the apparatus of the invention may be mounted upon the printer or copier or otherwise supported. 
     The apparatus of the invention will be better understood by reference to FIG.  2 . 
     In FIG. 2 the inverter I of the infeed  1  has a gate  2  having driven rolls  3 . The gate  2  is pivotal between a broken line position at which sheets will be delivered to the receiving tray RT, a second broken line position for delivery of sheets to the inverter I and a horizontal position for delivery of sheets to the feed path to shelf S 1 . 
     Shelf S 1  is pivotal for tilting movement on pivots  4 , one of which is a roller adapted to be driven by a roller  5  and a motor M 1 . As shown, the shelf S 1  is formed by a normally vertical wall  6  and a normally horizontal wall  7  on which is a centrally located finger  8  which is pivotally movable between a normal position extending horizontally outwardly and to a position beneath the wall  7 , as by a solenoid  9 . 
     As seen in FIG. 2, the horizontal extent of shelf wall  7  is such that the trailing ends of sheets supplied through the inlet and the inverter rest on the wall  7  and are further partially supported by finger  8 , while the leading ends of the sheets extend forwardly and are supported on the inclined top surface of the stacker tray ST or on sheets previously disposed upon the stacker tray. 
     Also, as seen in FIG. 2, the lower shelf S 2  is of right angular construction and has a normally Vertical wall  10  and a horizontally extended wall  11 . Lower shelf S 2  is horizontally pivotable by suitable means such as a motor M 2  and a linking belt drive  12 . 
     When support finger  8  is retracted beneath the upper shelf wall  7  and the upper shelf S 1  is pivoted, as shown in FIG. 3, the trailing end of the sheets are dumped and fall downwardly onto and gravitate to the rest on the horizontal wall  11  of shelf S 2 . As indicated in FIG. 4, following dumping of shelf S 1 , it is immediately reset to its normal position for reception of additional sheets constituting a portion of the total sheets of a set. Therefore, when a full set is being finished or stapled, the upper shelf will continue to receive a number of the sheets of the next set, so that, at least, the infeed rate of sheets from the printer or copier to shelf S 1  will not be impeded. 
     As seen in FIG. 5, the support finger  8  is relatively narrow and extends forwardly of the sheet delivery direction a sufficient distance to preliminarily support the trailing ends of the sheets as they are supplied to the shelf S 1  as shown in broken lines, the finger  8 , as previously indicated, is actuated to a position beneath the horizontal portion  7  of the shelf S 1  by the solenoid  9  or other actuator means to an out of the way position for releasing the trailing ends of the sheets upon downward pivotal movement of the shelf S 1  as seen in FIG.  3 . 
     Also, as seen in FIG. 4, the motor M 2  is actuated to dump shelf S 2  to drop sheets onto the stacker tray, so that a set of sheets on the stacker tray ST can be finished or stapled, on shelf S 2 , as hereinafter described. 
     The stapling mechanism is seen in FIGS. 6,  7  and  8 . 
     As illustrated, the stapling mechanism is adapted to apply a staple to a set of sheets on the stacker tray ST in either corner of the set of sheets or at plural locations along the trailing edge of the set of sheets. 
     Accordingly, the stapler S is adapted to be translated laterally of the apparatus by a motor M 3  and a driven belt  13  to which the stapler S is connected. 
     As seen in FIG. 7, the stapler S is mounted upon a carriage  14  interconnected with the belt  13  by suitable means and supported on transversely exteded rails and rollers. Means such as a pair of elongated slots  15  and pins  16  shiftable in the slots as the stapler base support  17  is caused to move by drive motor M 4 . Gearing or rolls  18  and  19  cause pivotal movement of the stapler. The gear  19  has a pin  20  reciprocal in a guide slot  21  so that upon energization of the motor M 4  the stapler is caused to pivot about a pivot point  22  into engagement with a stop pin  23 , as permitted by a pair of flexible links  24  connected to the stapler. 
     At the other side of the apparatus is a stop pin  23   a  which is utilized to locate the position of the stapler at the other side of the apparatus during the stapling of the sets of sheets shown in broken lines. 
     The sets are jogged and aligned by joggers  25  at opposite sides of the apparatus having an extensible steel rule type member  26  driven by the jogger motors  25  towards and away from one another and causing engagement of a pad  27  with the opposite sides of the set of sheets. Such steel rule type joggers are more particularly described and claimed in Coombs, et al U.S. Pat. No. 5,713,566, granted Feb. 3, 1998. 
     When it is desired to staple sets of sheets, as seen in FIG. 8 along the trailing edge of the set of sheets, the jogging devices are centralized. In addition, the stapler S is actuated by the motor M 4  selectively into a pair of notches  28  provided in the shelf S 2 . 
     From the foregoing, it will be seen that the present invention provides primarily for the progressive handling or reception of, say, two or more sheets supplied to the upper shelf S 1 , which upon dumping of shelf S 1 , deposit on shelf S 2  the trailing edge of the sheets on which the set of sheets, when completed, will be finished. 
     In such an arrangement the fact that the upper shelf receives small numbers of sheets making up a portion of the full set of sheets and continuously drops, say, two sheets from shelf S 1  to shelf S 2 , then the apparatus functions without impeding the speed of the infeed of sheets from the printer or copier. 
     The apparatus can be controlled in the customary fashion to cause corner stapling, without impeding the input speed of sheets into the apparatus, and depending upon the infeed speed or the provision of an inter-document gap, then the stapler may be used to edge staple the set of sheets without impeding the speed of the printer or copier. 
     Moreover, the entire set of sheets is not required to drop from shelf S 1  to shelf S 2 , but only the trailing end of the sheets need be dropped as the sets of documents or sheets are being finished on the second or lower shelf, before dumping only the trailing end onto the stacker tray.