Abstract:
A document sorting machine having at least one pocket for stacking documents according to a common criteria. Each pocket has a gate for diverting the document from the transport of the machine and into the designated pocket. The pocket also has a kicker for moving the tail of the document away from the pocket&#39;s entry and into the pocket and a detent which allows the tail to be moved into the pocket but which prevents the tail from moving back towards the pocket&#39;s entry after the tail of the document has been moved into the pocket.

Description:
TECHNICAL FIELD 
     The present invention relates to a machine used for sorting documents, e.g. mail, and more particularly relates to a means for retaining the tail of a document away from the entry of a stacker pocket of a document sorting machine once the document has entered the pocket so that the next document to be stacked in that pocket can easily enter the pocket without jamming. 
     BACKGROUND OF THE INVENTION 
     For several years, automated “sort machines” have been available which sort large volumes of documents (e.g. letters, postcards, checks, flats, and the like) into groups having a common identifying criteria (e.g. Zip Codes, mail boxes, etc.). A sort machine is typically comprised a “front end” or feed section and one or more “stacker sections”. The front end feeds the pieces, one-by-one, past a reader (e.g. optical character reader (“OCR”), bar code reader (“BCR”), or the like) and onto a transport that carries it to a designated sort pocket in the stacker section(s). 
     As the piece passes the reader, the desired criteria on a piece is read and a signal is generated that, in turn, is processed to generate a designation signal for that particular piece. This designation signal, in turn, triggers a diverter or “gate” at the designated pocket in the stacker section as the piece approaches to divert the piece from the transport into the designated pocket where it is stacked with other pieces having the same identifying criteria. Such machines are well known and are commercially-available, e.g. Vsort™ Flat Sort Machine, OMEGA™ Sort Machine, both manufactured and distributed by National Presort, Inc., Dallas, Tex. 
     One problem that exists in such machines arises from the occasional jamming of pieces as they are diverted into their designated pockets. One major cause of this jamming is that the “tail” of a previously diverted piece is not sufficiently moved away from gate (i.e. pocket entry) and into the pocket so that it may interfere with the leading edge of the next piece diverted into that same pocket. That is, if the tail of the last piece in a particular pocket is not moved sufficiently into the pocket and away from the gate, the leading edge of the next piece can be driven into the tail of the last piece thereby causing a “jam”. 
     One highly successful “fix” in alleviating jamming in machines of this type is to provide a “kicker” at each pocket which aligns with the gate of that pocket when the gate is actuated to divert a piece into the pocket. This allows smooth entry of the piece from the transport into the pocket. Once the piece has cleared the pocket&#39;s entry, the kicker is moved to “kick” the tail of that piece inwardly into the pocket and away from the entry point into the pocket. This allows the next piece to smoothly enter the pocket without engaging the tail of the previous piece. For complete details of such an anti-jamming means, i.e. “kicker”, see U.S. Pat. Re. 34,330, which is incorporated herein in its entirety by reference. 
     While this kicker works extremely well in preventing jamming in most instances (even with a wide variety of different types of mail pieces), there are some instances where the possibility of jamming still exists. For example, if the pieces are too stiff (e.g. glossy brochures) or too flimsy (e.g. tissue paper-like pieces), the tails of these pieces may not stay in the “kicked” position but may have a tendency to return toward the entry of the pocket once the kicker returns to its original position. Hence, the tail of the last sorted piece will be exposed for possible contact with the next piece entering that pocket and jamming can occur. Since the commercial market for this type of sort machines is highly competitive, any improvement in preventing jams may be significant in selling the machines since the downtime required for clearing jams is a major consideration when selecting the machine. 
     SUMMARY OF THE INVENTION 
     The present invention provides a document sorting machine having at least one pocket for stacking documents according to a common criteria. Each pocket has a means for diverting the document from the transport of the machine and into the designated pocket. The pocket also has a means for moving the tail of the document away from the entry into the pocket and completely into the pocket and a detent means for preventing the tail from moving back towards the pocket entry after the tail of the document has been moved completely into the pocket. 
     More specifically, the present invention provides a pocket for a document sorting machine wherein the pocket is comprised of a base plate having a means (e.g. a gate) thereon for diverting a document from the machine&#39;s transport and into the pocket. The pocket includes a means (e.g. a kicker) on said base plate for moving the tail of the document away from the pocket&#39;s entry and completely into the pocket In accordance with the present invention, a detent means is provided on the base plate for preventing the tail of the document from moving back towards the entry after the tail has been moved or kicked into the pocket. This prevents the tail of the sorted document from interfering with the leading edge of the next document diverted into the same pocket, thereby alleviating the possibility of the “jamming” of the documents. 
     Basically, the detent means is comprised of a detent which is movably mounted within an opening which, in turn, is formed through the base plate at a point inwardly from the pocket&#39;s entry. The detent, when in a first position, extends above the base plate to thereby prevent the tail of said document from moving back towards pocket&#39;s entry and, when in a second position, allows the tail to be kicked away from the entry and into the pocket. A means biases the detent towards its first position so that the detent will normally extend above the upper surface of the base plate to thereby present a barrier against the return of the tail towards the pocket&#39;s entry. 
     More specifically, the detent is comprised of a bent L-shaped member which is rotatably mounted within the opening in said base plate. The bent L-shaped member, when in its first position, has one leg extending substantially downward through the opening in the base plate and has another leg bent at a angle and extending above said base plate to provide a cam surface facing towards the pocket&#39;s entry. This cam surface and/or the depression of the member into the base plate allows the kicker to move the tail of the document over the detent and into the pocket. The means for biasing the member to its first position is preferably a small mass suspended by a chain or the like from the downwardly extending leg of the member but can equally be comprised of spring(s) appropriately positioned between the member and the base plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The actual construction operation, and apparent advantages of the present invention will be better understood by referring to the drawings, not necessarily to scale, in which like numerals identify like parts and in which: 
         FIG. 1  is an idealized top view of a typical sort machine into which the present invention can be incorporated; 
         FIG. 2  is a perspective view of a pocket module which can be used in the typical sort machine shown in  FIG. 1  and which includes the detent of the present invention; 
         FIG. 3  is a perspective view of the pocket module as shown in  FIG. 2 , partly broken away, to better show the details of the detent; 
         FIG. 4  is an enlarged, sectional top view of the pocket module of  FIG. 2 , partly broken away, when the gate and kicker are in their original positions; 
         FIG. 5  is a enlarged, section top view similar to  FIG. 4  when both the gate and kicker of the module have been actuated to a second position; and 
         FIG. 6  is a partial view of the module of  FIG. 2  illustrating another embodiment of the detent of the present invention. 
     
    
    
     While the invention will be described in connection with its preferred embodiments, it will be understood that this invention is not limited thereto. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents that may be included within the spirit and scope of the invention, as defined by the appended claims. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to the drawings,  FIG. 1  is a plan view of a typical document sort machine  10  of the type into which the present invention can easily be incorporated. Machine  10  is comprised of a feeder section  11  and a stacker section  12 . The feeder section  11  is comprised of a magazine  13  onto which a batch of documents (e.g. letters or pieces  14 ) are positioned. Conveyor  15  (e.g. motor driven chain-link belts) feeds document  14  forward onto pickoff  17  which picks off one piece at a time and delivers it onto transport  16 . As the document passes by optical character reader  18  and/or bar code reader  19 , an identifying mark, (e.g. a sort code such as a Zip Code or bar code, respectively) on the document  14  is read by the appropriate reader which, in turn, generates a signal representative of the mark. These signals are then processed in unit  20  which outputs a designation signal to stacker section  12 . 
     While stacker section  12  is shown as being comprised of a plurality, horizontal stacker bins or “pockets”  21  arranged in pairs having one pocket on either side of the transport  16   a , it should be understood, that as far as the present invention is concerned, the layout of the pockets, themselves, can take other configurations. For example, the pockets can be aligned on only one side of the transport in a single row or a plurality of single rows can be vertically spaced one above the others in a multi-level machine, see U.S. Pat. No. 5,109,987, issued May 5, 1992 and which is incorporated in its entirety by reference. 
     Each pocket  21  has a diverter means (i.e. gate  22 , only some of which are numbered in  FIG. 1  for clarity) which is actuated by the designation signal from processing unit  20  as a designated document  14  approaches its pocket. Gate  22 , when activated, rotates to temporarily intersect the centerline of transport  16  ( FIGS. 1 ,  4 , and  5 ), to thereby divert document  14  from transport  16  into the designated pocket  21   a . The construction and operation of sort machine  10  as described up to this point is well known, e.g. Models NP8000, Vsort™ and OMEGA™ Mail Sorters, manufactured and distributed by National Presort, Inc., Dallas, Tex. 
     Turning now to  FIGS. 2-5 , a single pocket module  30  incorporating the anti-jamming means of the present invention is described in detail. While the module  30  is illustrated as a single pocket module, again it should be recognized that the present invention is equally adaptable for use with a module having two opposed pockets ( FIG. 1 ) or in machines wherein the pockets, themselves, are formed integrally on the deck of the stacker section, as is the case in some older sort machines. 
     As shown in  FIGS. 2-5 , module  30  is comprised of base plate  31  on which a gate  22  and a kicker  23  are rotatably mounted. In its original position, gate  22  lies parallel to transport  16  so that any document  14  not designated to be sorted into the pocket adjacent module  30  will pass on by gate  22  and continue on transport  16  until it reaches a downstream destination. As will be understood in this art, transport  16  is typically comprised of a series of driven belts mounted on spaced pulleys or the like (not shown) which provide the “pinch” necessary for a document to be transported through module  30  to the next adjacent module if the document is not to be diverted to a pocket controlled by that particular module. 
     Further, as will be understood by those skilled in this art, each individual module  30  will control the diversion of documents into an adjacent pocket  21  ( FIGS. 1 ,  4 , and  5 ) by the actuation of the respective proper gate  22 . Each gate  22  is affixed to the upper end of a shaft  24  which, in turn, is rotated by an individual rotational solenoid (not shown) which is preferably of the type that rotates in one direction against the bias of an internal spring when actuated and which is rotated in the other direction by the spring force when deactuated. An example of such a solenoid is Model 188131-001 (Right-hand or Left-hand), manufactured by Ledex, Inc., Vandalia, Ohio. 
     Gate  22 , when in a first position ( FIG. 4 ), lies substantially parallel to the centerline of transport  16  (dotted line  16   a  in  FIG. 4 ) and intersects the centerline when a second position ( FIG. 5 ). Kicker gate  23  (only one numbered in  FIG. 1 ) which may have substantially the same configuration as gate  22  is provided for each module  30  and is mounted on the upper end of a shaft  25  of a rotational solenoid (not shown) which is of the same type as the previously described solenoid. When in a first position ( FIG. 4 ), kicker  23  is positioned so as to be basically aligned with gate  22  when gate  22  diverts a document into its pocket so that the document will move smoothly into the pocket. When kicker  23  is rotated, the kicker “kicks” the tail  14   a  ( FIG. 5 ) firmly into the pocket  21  and away from the entry of the pocket. The construction and the operation of module  30  up to this point is basically the same as that disclosed and claimed in U.S. Pat. Re 34,330 which, in turn, is incorporated herein in its entirety by reference. 
     While the kicker described above has proved highly successful in reducing jamming caused by the forward edge of an incoming document contacting the tail of a previously sorted document, unfortunately, the possibly of jamming still exists in isolated instances. That is, with certain types of documents, the tail of the document may not remain in its “kicked” position but instead may try to return towards the entry of the pocket as the kicker returns to its original position. 
     In accordance with the present invention, a biased detent  40  is provided at the front of pocket  21  which allows the tail of a document to be “kicked” fully into the pocket but prevents the tail from following the kicker back towards the entry of the pocket. More specifically, as best seen in  FIG. 3 . a detent  40  is positioned through opening  42  in base plate  21  of module  30  and is pivotably mounted therein on an axis pin  43  or the like. Detent  40 , as shown, is comprised of an bent L-shaped member having one leg  44  which extends substantially vertically downward through opening  43  with the other leg  45  defining a cam surface  46  which extends above the surface of the base plate at an angle (e.g. 20°) and slopes upwardly away from the transport  16  when the detent is in its normal operating position. 
     In the preferred embodiment shown in  FIGS. 2 and 3 , a small mass  47  (e.g. 1 oz.) is suspended from the bottom of leg  44  by a short length of chain  48  or the like. The weight of mass  47  is such as to allow contact of the tail  14   a  ( FIG. 5 ) of the incoming document to easily cam up over surface  46  of leg  45  and/or rotate leg  45  downward into base plate  31  (depending on the document being sorted) thereby allowing the tail of the document to be moved into the pocket and away from the point of entry. 
     While mass  47  is simple and easily maintained, it should be recognized that other biasing means can be used to bias detent  40  towards its normal operation position. For example,  FIG. 6  discloses an embodiment where springs are used for this purpose. Detent  40   a  is comprised of a bent L-shaped member (same as before) which has a compression spring  49   a  positioned between the long leg  44  and a vertical support  50  on base plate  31 . Likewise, a second compression spring  52  can be placed between the angled leg  45  and the base plate. Only one of these springs may be required or both can be used if desired. Other biasing arrangements will suggest themselves to those skilled in this art without departing from the present invention. 
     In operation, a document  14  is sorted by front end  11  and is sent down transport  16 . When it approaches its designated pocket, gate  22  is actuated to intersect the centerline of transport  14  ( FIG. 5 ) to divert the document into its pocket. As the document follows path (dotted lines  14   b ,  FIG. 5 ), kicker  23  is actuated to “kick” the tail  14   a  of the piece positively into the pocket and away from the point of entry into the pocket. As the tail  14   a  is moved by kicker  23 , it contacts the cam surface  46  of detent  40  and causes bent the L-shaped member to rotate about pin  43 . This effectively depresses the angled leg  45  of the bent-L member until it is level with the base plate. 
     As detent  40  rotates, mass  47  will be inherently lifted. Once the document clears the depressed leg  45 , gravity pulls mass  47  downward to thereby detent  40  back to its original position. Now if the tail  14   a  attempts to return towards its original position along with kicker  23 , it abuts the substantially vertical surface  49  of leg  45  ( FIGS. 4 and 5 ) which, in turn, blocks the tail  14   a  from moving back towards the pocket&#39;s entry. In this position, detent  40  is again in position to receive the next incoming document and the operation can be repeated without interruption. This insures that the tail of a previously sorted document will not interfere with the leading edge of the next incoming document to that pocket and the possibility of “jamming” is significantly reduced, if not eliminated.