Abstract:
A stacking apparatus and method. A document set stacking apparatus and method is provided for use in a document creating apparatus. A set stacking area is provided that has been adapted to accept a stack of a plurality of document sets having fasteners. A set relief area is provided for the portion of the document sets containing the fasteners. At least one fastener attractor is provided adjacent the set relief area. The fastener attractor attracts the fasteners and the portions of the document sets containing the fasteners toward the set relief area.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to copying machines and printing machines, and, more particularly to copying systems or printing systems with a document stacking apparatus and method.  
           [0003]    2. Prior Art  
           [0004]    Many different output sections for electrostatographic copying systems or printing systems are known in the art for stacked document sets having fasteners. For example, U.S. Pat. No. 5,609,333 discloses a sheet stacking height control system used in a sheet stacking apparatus for stacking plural sheets into at least one stacking tray. Another example, U.S. Pat. No. 5,026,034 discloses an apparatus for feeding and stacking sets of finished sheets in an electrostatographic copier or printer including an anti-dishevelment device for preventing the tearing, dishevelment and other damaging of the top sheet of the top set of the sets in the stack by contacting and holding down such top sheet during the feeding of a new set onto the top of the stack. Both of the above referenced patents are incorporated by reference in their entirety. Document output devices commonly stack fastened, stapled or otherwise finished sets of document sheets one at a time on top of others for later removal by an operator.  
           [0005]    A common problem associated with the stacking of document sets is bin or tray under utilization due to stack height variations and the resultant tray or bin capacity variations. The actual and maximum stacking height in a tray or bin can vary considerably with different print job factors. For example, with variations in the sheet thickness, humidity, sheet curl, staples or other binding, edge climbing by sheet edges partially hanging up on vertical registration edges, and other factors affecting stack height. Additionally, maximum stack height may occur only in certain areas of the stack. This is demonstrated especially when fasteners or staples are used in the document set. Stacks of plural fastened or stapled sets tend to have a much higher height level where the fasteners or staples overlie or overlap on top of one another in the stack. Fastener or staple buildup is particularly pronounced for small sets of only a few sheets per stapled set. It has been found for example that a stack of multiple sets of only two sheets per stapled set, such as a common two page letter, can have a maximum stack height in the area of the stack where all those staples overlie one another of more than twice the stack height of other areas of that stack. Consequences of bin or tray under-utilization can include unnecessarily splitting up final print jobs for a user by redirecting them to another mailbox bin or an overflow tray when there was actually still enough stacking room or headspace in the first bin to finish stacking that job or jobs in the first bin. Increased bin or output tray capacity can help to better maximize bin and tray usage and availability when more sheet or document set stacking room is actually available in a given bin or tray. Increased bin or output tray capacity can help to increase productivity and maximizes utilization of the printer output and mailbox system by reducing printing stoppages of the reproduction apparatus, and/or reducing the required number of mailbox bins or output trays. There is a desire to provide a stacking apparatus that provides additional stack capacity to reduce bin or tray under utilization due to stack height variations and particularly stack height variations due to fastener or staple buildup.  
           [0006]    Another common problem associated with the stacking of document sets is the tendency of the set being fed and stacked to tear or otherwise damage the top sheet of the top set of the sets already in the stack. This problem is further complicated by limitations with respect to which edge or corner of the document sheets are, for example, fastened, stapled or bound for forming the set. There is a desire to provide a stacking apparatus that provides a reduced tendency of the set being fed and stacked to be torn or otherwise damaged by the sets already in the stack or of the set being fed and stacked to tear or otherwise damage the top sheet of the top set of the sets already in the stack or to be torn or otherwise damaged by the sets already in the stack.  
         SUMMARY OF THE INVENTION  
         [0007]    In accordance with one embodiment of the present invention, a document set stacking apparatus is provided for use in a document creating apparatus. A set stacking area is provided that has been adapted to accept a stack of document sets having fasteners. A set relief area is provided which a portion of at least one of the document sets containing the fasteners can be attracted toward by a fastener attractor. In one embodiment, the fastener attractor can be at least one magnet provided adjacent to the set relief area. The magnet attracts the fasteners and the portions of the document sets containing the fasteners toward and into the set relief area.  
           [0008]    In accordance with another embodiment of the present invention, a document set stacking apparatus is provided for use in a document creating apparatus. A tray is provided onto which a plurality of document sets having fasteners can be placed. A magnetic device is provided adjacent to the tray and adapted to attract the fasteners. The fasteners are attracted to the magnetic device. As a result, the documents sets are, at least partially, retained in the stack when a new document set is fed on the stack.  
           [0009]    In accordance with another embodiment of the present invention, a method of stacking one or more document sets having fasteners on a stacking surface is provided comprising a first step of placing at least one document set on the stacking surface. The fasteners and consequently the region of the set containing the fastener are attracted toward a relief area of the stacking surface by an attracting force. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a general understanding of the present invention, as well as other aspects thereof, reference is made to the following description and drawings, in which like reference numerals are used to refer to like elements, and wherein:  
         [0011]    [0011]FIG. 1 is a schematic view of a copying system;  
         [0012]    [0012]FIG. 2A is a top view of a stapled document set with a single staple in a corner;  
         [0013]    [0013]FIG. 2B is a top view of a stapled document set with two staples along an edge;  
         [0014]    [0014]FIG. 2C is a top view of a stapled document set with holes punched along an edge;  
         [0015]    [0015]FIG. 2D is a top view of an alternative stapled document set with holes punched along an edge;  
         [0016]    [0016]FIG. 3A is a perspective view of a stack of document sets without fasteners;  
         [0017]    [0017]FIG. 3B is a perspective view of a stack of document sets with a fastener in each set, such as shown in FIG. 2A, which shows the normal build up of thickness in the staple area;  
         [0018]    [0018]FIG. 3C is a perspective view of an alternative stack of document sets with a fastener in each set, such as shown in FIG. 2B, which shows the normal build up of thickness along the stapled edge;  
         [0019]    [0019]FIG. 4A is a view of a document tray;  
         [0020]    [0020]FIG. 4B is a view of a document tray with a relief area;  
         [0021]    [0021]FIG. 4C is a view of an alternative document tray with a relief area;  
         [0022]    [0022]FIG. 5A is a side schematic view of a document tray with a stack of stapled document sets;  
         [0023]    [0023]FIG. 5B is a side schematic view of another document tray with a stack of stapled document sets;  
         [0024]    [0024]FIG. 5C is a side schematic view of still another document tray with a stack of stapled document sets;  
         [0025]    [0025]FIG. 5D is a top view of a document tray with a stack of stapled document sets;  
         [0026]    [0026]FIG. 6 is a view of a magnet mounted on a document tray.  
         [0027]    [0027]FIG. 7 is a view of a electromagnet. 
     
    
       [0028]    While the present invention will be described with a reference to preferred embodiments thereof, it will be understood that the invention is not to be limited to those preferred embodiments. On the contrary, it is intended that the present invention cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. Other aspects and features of the present invention will become apparent as the description proceeds.  
       DESCRIPTION OF EMBODIMENTS  
       [0029]    It will become apparent from the following discussion that the stacking apparatus and method of the present invention is equally well suited for use in a wide variety of printing systems including electrophotographic or electronic printing systems, as for example, ink jet, bubble jet, ionographic, laser based exposure systems, etc.. Further, the stacking apparatus and method of the present invention is equally well suited for use in any type of document handling system wherein documents having fasteners, staples or the like are stacked.  
         [0030]    [0030]FIG. 1 shows one embodiment of the present invention. In FIG. 1 there is shown, in schematic form, a view of a copying system  2  for processing, printing and finishing document copying jobs in accordance with teachings of the present invention. A copying system of the type shown is preferably adapted to provide, in a known manner, duplex or simplex, stacked fastened, stapled or bound document sets from duplex or simplex collated document or print sets which result from either duplex or simplex original documents. Copying system  2  has any suitable processing or printing section  3 , such as a xerographic processor, a finishing section  6  and an output section  9 . The exemplary xerographic processing or printing section  3  is a generally well known type such as made by Xerox Corporation, such as Models “1075”, “5090” or “5100” duplicators. Such electrostatographic printing systems are illustrated and described in detail in various patents including U.S. Pat. No. 4,961,092, the principal operation of which may also be disclosed in various other xerographic or other printing machines. U.S. Pat. No. 4,961,092 is incorporated by reference herein in its entirety. Finishing section  6  is a generally well known type and may incorporate a hole punch, a stapler and a bin sorter which are illustrated and described in detail in various patents including U.S. Pat. No. 3,467,371 and U.S. Pat. No. 5,842,624 and U.S. Pat. No. 5,762,329, all three of which are also incorporated herein by reference in their entirety. Output section  9  incorporates a tray  11  which accepts and stacks stapled or unstapled documents or document sets ejected from finishing section  6  at ejection zone  12 . Tray  11  can be vertically movable in direction  15  in order to facilitate stacking of document sets.  
         [0031]    In FIGS. 2A through 2D there is shown views of several representative styles of stapled document sets. In FIG. 2A there is shown a stapled document set  18  with a single staple  21  in a corner of stapled document set  18 . In FIG. 2B there is shown a stapled document set  24  with a two staples  25  along an edge of stapled document set  24 . In FIG. 2C there is shown the stapled document set of FIG. 2A with holes  28  punched along an edge. In FIG. 2D there is shown the stapled document set of FIG. 2B with holes  31  punched along an edge. The stapled document sets shown in FIGS. 2A through 2D are intended to be exemplary, and it will be understood that the stacking apparatus and method of the present invention is equally well suited and can be adapted for use with document sets with any one of a number of types of fasteners including but not limited to staples, clips or rivets or the like located at any of a number of varying locations or quantities on the document sets.  
         [0032]    In FIGS. 3A through 3C show various orientations of stacked document sets. In FIG. 3A there is shown a stack of documents or document sets which do not have staples or fasteners. Note that thickness  34  of the stack is generally of uniform thickness across the stack. In FIG. 3B there is shown a stack of stapled document sets similar to that of FIG. 2A. Note that thickness  41  of the stack in proximity with the staples is greater than thickness  38  of the stack distant from the staples. In FIG. 3C there is shown a stack of stapled document sets similar to that of FIG. 2B. Note that thickness  47  of the stack in proximity with the staples is greater than thickness  44  of the stack distant from the staples.  
         [0033]    In FIG. 4A there is shown a view of a representative prior art document tray. In FIG. 4A there is shown tray  50  with stacking area  53 . Tray  50  is suitable for stacking sets of documents or document sets which do or do not have staples or fasteners similar to that shown in FIG. 3A. However, when the sets have staples, the area of the stack in the region of the staples will be thicker than the rest of the stack, as shown in FIG. 3B, and this will limit the amount of sets that the tray can hold as opposed to when the sets are not stapled.  
         [0034]    In FIG. 4B there is shown tray  56  with stacking area  59 , relief area  63  and magnet  66 . Tray  56  is suitable for stacking a stack of stapled document sets similar to that shown in FIG. 2A. Note that magnet  66  is placed in proximity to the corners of the document sets with the staples in order to attract the stapled corners into the relief area  63 . Magnet  66  may be imbedded in tray  56 , molded with tray  56 , be mounted on a surface of tray  56  or otherwise be placed in proximity of tray  56  such that magnet  66  is placed in proximity to the corners of the document sets with the staples in order to attract the stapled corners into the relief area. As document sets are stacked in tray  56 , magnet  66  attracts the staples or fasteners of the document sets such that relief area  63  accommodates the bulk produced by the stapled corner and the region of the document set associated with the stapled corner. The rest of the stack of document sets remains relatively flat similar to stacks of document sets that have no fasteners or staples. The result is that more document sets may be placed in tray  56 . Further, as a result of the staples or fasteners being attracted to magnet  66  and as a result to each other, the retaining force generated provides a reduced tendency of the set being fed and stacked to be torn or otherwise damaged by the sets already in the stack or of the set being fed and stacked to tear or otherwise damage the top sheet of the top set of the sets already in the stack or to be torn or otherwise damaged by the sets already in the stack.  
         [0035]    In FIG. 4C there is shown tray  69  with stacking area  72 , relief area  75  and magnet  79 . Tray  69  is suitable for stacking stapled document sets similar to that shown in FIG. 2B. Note that magnet  79  is placed in proximity to the edge of the document sets with the staples in order to attract the stapled edges into the relief area. Magnet  79  may be imbedded in tray  69 , molded with tray  69 , be mounted on a surface of tray  69  or otherwise be placed in proximity of tray  69  such that magnet  79  is placed in proximity to the edge of the document sets with the staples in order to attract the stapled edge into the relief area. As document sets are stacked in tray  69 , magnet  79  attracts the staples or fasteners of the document sets such that relief area  75  accommodates the bulk produced by the stapled edge and the region of the document set associated with the stapled edge. The rest of the stack of document sets remains relatively flat similar to stacks of document sets that have no fasteners or staples. The result is that more document sets may be placed in tray  69 . Further, as a result of the staples or fasteners being attracted to magnet  79  and as a result to each other, the retaining force generated provides a reduced tendency of the set being fed and stacked to be torn or otherwise damaged by the sets already in the stack or of the set being fed and stacked to tear or otherwise damage the top sheet of the top set of the sets already in the stack or to be torn or otherwise damaged by the sets already in the stack.  
         [0036]    Magnets  66  or  79  can be a single magnet or a plurality of magnets. Magnets  66  or  79  can be any suitable piece of iron, steel or other material that has the property of attracting the material of the fastener, for instance, iron, steel or other suitable fastener materials etc.. The property that produces the force attracting the staples or fasteners may be naturally present or artificially induced, as by selectively passing an electric current through a coil of wire thus making a magnetic field with an electromagnet, or as by selectively canceling out the field produced by the magnet with an additional opposing naturally present or artificially induced magnetic field. When the field is selectively produced, the field may be switchable between a on - fastener attracting state and a off - fastener release state. This may be useful, for example, to facilitate higher capacity stacking and to further facilitate document set retention with the on - fastener attracting state and for ease of removal of the document sets with the off - fastener release state. Magnets  66  or  79  can be of any suitable shape for the function they provide, for instance, they can be generally cylindrical in shape but may be in the shape of a rectangle, disk, ring or any other suitable shape. Magnets  66  or  79  may be a permanent magnet of types known in the art. Magnets  66  or  79  may be made by any suitable material. For instance, they can be made of a Rare Earth, Neodymium-Iron-Boron magnet, ½″ diameter, ½″ length, model number RMND112 manufactured by the Rochester Magnet Company of Rochester, N.Y. Magnets  66  or  79  may be an electromagnet, or any type of magnet with fixed or switchable field. Magnets  66  or  79  may be a single magnet or multiple magnets. If magnets  66  or  79  are of the electromagnet type or a magnet of the type with a switchable field, the field may always be on, thus attracting the fasteners or staples and retaining the document sets. Alternately, the field may be on only during the stacking operation thus allowing ease of removal of the stack of stapled document sets when the field is off and not attracting the stapled document sets.  
         [0037]    [0037]FIGS. 5A through 5D show views of document trays with stacks of stapled document sets. In FIGS. 5A and 5C, magnets are placed in proximity to the fasteners or staples. As a result of the staples or fasteners being attracted to the magnet(s) and to each other, the retaining force generated provides a reduced tendency of the set being fed and stacked to be torn or otherwise damaged by the sets already in the stack or of the set being fed and stacked to tear or otherwise damage the top sheet of the top set of the sets already in the stack or to be torn or otherwise damaged by the sets already in the stack.  
         [0038]    [0038]FIG. 5A shows a tray similar to that shown in FIG. 4A. In FIG. 5A there is a magnet  82  placed in proximity with stapled edge or stapled corner  87  of stapled document set stack  84 . The height  91  of stapled document set stack  84  in proximity to stapled edge or stapled corner  87  is reduced as compared to if magnet  82  were not present. This allows for increased capacity of tray  89  as compared to a tray of similar size without magnet  82 . Stapled documents can continue to be ejected from ejection zone  83  until stack height sensor  85  detects that tray  89  is at capacity, at which point the system can be shut off until the documents sets are removed. Stack height sensor  85  can read that tray  89  is at capacity with less stapled documents than when magnet  82  is not present. Stack height sensor  85  can read that tray  89  is at capacity with more stapled documents when magnet  82  is present.  
         [0039]    [0039]FIG. 5B shows a tray similar to that shown in FIG. 4B or FIG. 4C without magnet  66  or  79 . Height  93  of stapled document set stack  84  is greater than if a magnet were present to compress it. FIG. 5C has a magnet  95  placed in proximity with stapled edge or stapled corner  87  of stapled document set stack  84  allowing height  97  of stapled document set stack  84  in proximity to stapled edge or stapled corner  87  to be less than if magnet  95  were not present. Again, this allows stapled edge or stapled corner  87  of stapled document set stack  84  to be drawn into recess  94  and also allows for increased capacity of tray  99  as compared to a tray of similar size without magnet  95 . Stapled documents can continue to be ejected from ejection zone  83  until stack height sensor  85  detects that tray  99  is at capacity. Stack height sensor  85  will read that tray  99  is at capacity with less stapled documents when magnet  95  is not present. Stack height sensor  85  can read that tray  99  is at capacity with more stapled documents when magnet  95  is present.  
         [0040]    [0040]FIG. 5D shows tray  99  in the configuration of the tray shown in FIG. 4B. The increased height of the stapled end of the stapled documents does not affect the height at which stack height sensor  85  detects that tray  99  is at capacity. If magnet  95  were not present in FIG. 5C, the increased height of the stapled end of the stapled documents would affect the height at which stack height sensor  85  detects that tray  99  is at capacity, resulting in reduced capacity of tray  99 .  
         [0041]    [0041]FIG. 6 shows a detailed view of one embodiment of mounting a magnet on a document tray. Tray or relief area  102  has a document set side  106  and a magnet mounting underside  107 . Magnet  109  is retained in tray recess  111  with magnet retaining plate  114 . Posts  116  and  117  are molded or fabricated as part of tray or relief area  102 . Posts  116  and  117  are sized to accept magnet retaining plate  114  and snap washers  118  and  119 . Magnet retaining plate  114  is held in place relative to tray or relief area  102  with snap washers  118  and  119 .  
         [0042]    [0042]FIG. 7 shows a view of a electromagnet where the property that produces the force attracting the staples or fasteners is artificially induced. Electric current  130  is produced by power source  125  when switch  127  is closed. Electric current  130  passes through coil of wire  123  that incduces a magnetic field in core  121 . The magnetic field is selectively produced by changing the state of switch  127  either manually or automatically as with a controller. The field may be switchable between a on - fastener attracting state and a off - fastener release state. This may be useful, for example, to facilitate higher capacity stacking and to further facilitate document set retention with the on - fastener attracting state and for ease of removal of the document sets with the off - fastener release state.  
         [0043]    It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Such alternatives may include substituting any suitable materials for the magnets or fasteners herein described. Such alternatives may further include configuring the magnets or fasteners in any suitable manner. Such alternatives may further include configuring the magnets or fasteners in an alternative system or subsystem of a copier, printer or paper or document set handling apparatus. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.