Abstract:
A method for sweeping mail pieces from pockets of a sorter including the steps of (1) sorting mail pieces to a plurality of pockets based upon a preselected sorting criteria, (2) positioning an unloading robot adjacent to a selected one of the pockets when the pocket has received a predetermined volume of mail pieces, the robot carrying a tray having upright side walls and bottom wall, (3) engaging the pocket with a sweeping apparatus, (4) removing mail pieces in the pocket with the sweeping apparatus, (5) loading the removed mail pieces into the tray carried by the robot, and (6) carrying the tray containing the removed mail pieces to a destination with the robot. An apparatus for implementing the method is also disclosed.

Description:
[0001]    This application claims priority of U.S. Provisional Patent Application Serial No. 60/280,169, filed Mar. 30, 2001. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates to the field of mail sorting, and particularly to a method and apparatus for mechanized sweeping of a pocket, and more specifically, to a method and apparatus for mechanized sweeping of mail items from the pockets of an automated mail sorting machine.  
         BACKGROUND OF THE INVENTION  
         [0003]    Modern postal services, for example, the U.S. Postal Service, handle massive volumes of mail pieces on a daily basis. Machines for receiving and sorting these massive volumes of letter mail are known. Typically, such machines are adapted to receive large volumes of flat articles and sort the articles into a plurality of pockets or bins based upon selected criteria. In the case of letter mail, the criteria is associated with the destination of the individual mail pieces which may be an indicia such as a Zip+4 destination code. Typically, such sorting machines have a feeding station, sensing and detecting equipment for determining the appropriate output compartment or pocket for the article to be sorted and diverting gates or other mechanisms for selectively diverting articles to selected ones of an array of output compartments or pockets for the sorted articles. An example of an advanced sorting machine is the DBSCII sorting device, available from Siemens ElectroCom, L. P., Arlington, Tex.  
           [0004]    The feeding and sorting of articles by a mail sorter to a pocket normally continues until the pocket become sufficiently full of a stack of sorted articles or mail. When the pocket or receiving compartment is full, an operator manually removes a stack of the sorted articles from the pocket and places the stack of articles into a box. This removal of stacked articles is typically referred to as “sweeping” the compartment or pocket. The stack of sorted articles placed by the operator into a box may be further reprocessed through the same sorting machine, may be transferred to another sorting machine for additional sorting or may be transported to a delivery person, such as a mail carrier, or may be transmitted for ultimate delivery to the intended location, address or recipient when all desired sorting is completed.  
           [0005]    Although automatic sorting machines have greatly speeded and improved prior processes for manual article sorting, sweeping and retrieving the sorted and stacked articles from the output pockets of the sorting machine is still a manual operation. The need for such manual sweeping is undesirable for ergonomic reasons because of the bending and reaching required of humans to perform these tasks. Furthermore, the need for such manual handling of mail articles tends to limit the maximum benefits of automation that can be gained from the automatic sorting machines.  
           [0006]    Thus there exists a need for a mechanized sweeping method and apparatus to alleviate the shortcomings of manual sweeping.  
         SUMMARY OF THE INVENTION  
         [0007]    The invention provides a method for sweeping mail pieces from pockets of a sorter including the steps of (1) sorting mail pieces to a plurality of pockets based upon a preselected sorting criteria, (2) positioning an unloading robot adjacent to a selected one of the pockets when the pocket has received a predetermined volume of mail pieces, the robot carrying a tray having upright side walls and bottom wall, (3) engaging the pocket with a sweeping apparatus, (4) removing mail pieces in the pocket with the sweeping apparatus, (5) loading the removed mail pieces into the tray carried by the robot, and (6) carrying the tray containing the removed mail pieces to a destination with the robot.  
           [0008]    In one aspect, the invention includes an apparatus for sweeping mail pieces from the pockets of a sorter including an unloading robot for carrying and positioning a mail tray with a false bottom, adjacent to a pocket to be emptied, the robot including a sweeper drive assembly and means for lifting the false bottom of the tray. A sweeper assembly for the pocket includes a telescoping arm with a projection that is coupled to a moveable gate for sweeping the pocket. The sweeper assembly is engaged by the sweeper drive assembly carried by the unloading robot to sweep letter mail laterally from the pocket.  
           [0009]    In one aspect the sweeper drive assembly includes a frame and a sliding elevator clamped to a timing belt for lateral movement. The elevator is mounted on a pair of parallel rails for longitudinal movement along a frame and includes a hook-like sweeper arm catch, configured to engage a projection on the sweeper arm and move the sweeper arm horizontally and vertically to sweep the mail pocket. Lifting means for lifting a false bottom of the tray to align the false bottom with the bottom of the pocket comprise one or more cylinders operating through apertures in the bottom of the mail tray. Once the mail tray is positioned adjacent to the pocket to be swept, the sweeper drive assembly engages the sweeper arm to sweep mail from the pocket onto the false bottom of the mail tray. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:  
         [0011]    [0011]FIG. 1 is a perspective view of an array of mail receiving pockets used for sorting mail including a sweeping apparatus suitable for practicing the method of the invention;  
         [0012]    [0012]FIG. 2 is partial perspective view of an individual pocket and the unloading robot during the sweeping operation;  
         [0013]    [0013]FIG. 3 is a partial perspective view of the unloading robot showing the sweeper drive assembly; and  
         [0014]    [0014]FIG. 4 is a partial perspective view of the unloading robot with a mail tray positioned on the robot with a portion of the tray cut away. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.  
         [0016]    Turning now to FIGS. 1 and 2 the invention may be implemented with a mail sorting machine includes a mechanized mail receiving and sweeping system  10 . A plurality of pockets  12  are arranged in a plurality of rows  14  and columns  16  for receiving mail pieces from an automated sorter that uses a preselected criteria such as destination indicia, for example a bar code appearing on the mail, to sort the mail pieces into pockets  12 . System  10  includes an unloading robot  20  equipped with a tray platform  22  including a pair of belts  24  for loading and unloading trays  25 . Robot  20  is configured for longitudinal movement to enable alignment of the robot with a selected column  16  of pockets  12 . Tray platform  22  is configured for vertical movement, allowing the platform to be aligned a particular row  14  of pockets  12 . Robot  20  is provided with a sweeper drive assembly  26  for sweeping pockets  12  after the robot has been positioned at a full pocket.  
         [0017]    Sweeper drive assembly  26  includes a frame  28 , timing belt  30  driven by motor  32  and a sliding elevator  34  that is clamped to belt  30  for moving elevator  34  laterally. Although as illustrated elevator  34  is driven with a belt drive, any conventional drive means such as a screw type cam, hydraulic or pneumatic cylinder, rack and pinion drive or similar drive unit may be utilized to move elevator  34 , depending upon the particular design. Elevator  34  is mounted on a pair of parallel rails  38  for movement along frame  28  parallel to rails  38  and includes a hook-like sweeper arm catch  40 , mounted for vertical movement relative to frame  28  Sweeper arm catch  40  may be raised and lowered with any conventional linear drive such as a solenoid or pneumatic or hydraulic cylinder (not shown). Sweeper arm catch  40  is configured to engage a projection  55  that is part of or coupled to telescoping sweeper arm  58 , enabling the sweeper drive assembly  26  to move the sweeper arm horizontally and vertically to sweep pocket  12 .  
         [0018]    Each pocket  12  includes an input end  44  and discharge end  46  and is provided with a mail sweeper assembly  48 . Sweeper assembly  48  includes a stationary frame  50 , support rail  52  and a telescoping sweeper arm  54 , including a paddle support rail  56  and paddle  58  mounted for movement along rail  56 . As noted above, sweeper arm  54  also includes projection  55 , enabling catch  40  to engage the sweeper arm. Paddle  58  is mounted on rail  56  with a sliding clamp  60  and is biased toward the input end of  44  of pocket  12  with a spring  62 . In operation, the biasing action of spring  62  holds paddle  58  against mail sorted into pocket  12 . In this regard it should be noted that paddles  58  in FIG. 1 are shown extended to the discharge ends  46  of pockets  12  for the purpose of illustration. In normal operation, paddles  58  would be biased against sweeper gates  64 , or mail in the pocket, by action of springs  62 .  
         [0019]    A sweeper gate  64  mounted on shaft  66  is pivotable between an open position and a closed position. Shaft  66  and/or Sweeper gate  64  may be biased and pivoted using any convention means (not shown) such as a solenoid, electric motor, or hydraulic or pneumatic cylinder mounted on frame  50  or on pocket  12 . As shown, sweeper gate  64  includes a pair of fingers  68 , each of the fingers having a pair of spaced apart notches  70 , positioned so that each of the notches  70  is vertically aligned with a corresponding notch  70  in the other finger.  
         [0020]    In operation, mail pieces are sorted by destination into pockets  12 . When a particular mail piece is identified or associated with a destination corresponding to a particular pocket, the sorting machine pivots shaft  66 , opening gate  64  to allow the mail piece to enter the pocket  12 . Mail directed into pocket  12  accumulates, forming a stack  96  between spring loaded paddle  58  and sweeper gate  64 . When a pocket  12  has received a predetermined volume of mail pieces, a sensor such as a limit switch or proximity sensor (not shown) sends a signal to the computer or microprocessor (not shown) controlling the sorting machine, indicating that the pocket needs to be swept. The computer then directs robot  20  to retrieve an empty tray  25  if the robot is not already carrying an empty tray on tray platform  22 , and position tray carrier  22  adjacent to the pocket  12  to be swept.  
         [0021]    Referring now to FIGS. 2 and 3, robot  20  includes a tray platform  22  with belts  24  for positioning a false bottom mail tray  25  on the platform, a lift cylinder  74  with a shaft  76  for raising and lowering false bottom  90  of mail tray  25 . Tray platform  22  also includes a retainer cylinder  80  and shaft  82  for engaging and lifting a retainer  78 , mounted in tray  25 , that includes a pair of retaining fingers  84 . When tray carrier  22  is positioned adjacent to the pocket  12  to be swept, belts  24  are activated to position the edge of tray  25  immediately adjacent to the discharge end  46  of pocket  12  so as to eliminate or minimize any gap between tray  25  and pocket  12 . Lift cylinder  74  is actuated and shaft  76  extends, raising the false bottom  90  of tray  25  so as to align the false bottom with the top of tray  25  and the bottom of pocket  12  as shown in FIG. 2.  
         [0022]    After mail tray  25  has been positioned adjacent pocket  12  and false bottom  90  has been raised, belt  30  is activated to position the catch under projection  55  of sweeper arm  54 . Elevator  34  is then actuated to raise catch  40  a sufficient distance to engage projection  55 . After catch  40  is positioned, belt  30  is actuated to slide elevator  34 , engaging projection  55  with catch  40  and moving sweeper arm  54  from a first position (shown in phantom in FIG. 3) to a second, extended position (FIG. 2), thereby sliding mail stack  96  from pocket  12  onto false bottom  90  of tray  25 . When the mail stack is positioned on false bottom  90 , retainer cylinder  80  is activated and shaft  82  engages retainer  78 , pushing retainer pins  84  up and into notches  70  in fingers  68  of sweeper gate  64 . As shown, tray  25  includes a bottom wall  86  with holes  88  through which shafts  76  and  82  operate.  
         [0023]    When retainer pins  84  are positioned in notches  70 , lift cylinder  74  and retainer cylinder  80  are actuated, lowering false bottom  90  into tray  25  between walls  92 . Mail stack  96  moves with false bottom  90  which lowers the mail stack from between sweeper paddle  58  and sweeper gate  64  into tray  25 . When false bottom  90  is fully lowered, mail stack  96  is positioned between stack support  98  and retainer pins  84  in mail tray  25 .  
         [0024]    After the mail stack is removed from between sweeper gate  64  and paddle  58 , spring  62  pushes sliding clamp  60  along rail  56  until paddle  58  is positioned adjacent to sweeper gate  64 , ready to receive additional mail. Belt  30  is actuated to move elevator  34 , returning sweeper arm  54  to its original position. Catch  40  is lowered to disengage projection  55 , completing the operation. After the pocket sweeping operation is completed, robot  20  conveys the mail tray to its destination for further processing of the mail.  
         [0025]    The operation of the mail sweeping system of the invention is controlled with a computer, microprocessor, programable controller or similar device. Travel and positioning of the various moving components of the system may be conventionally controlled and monitored with a variety of devices such as limit switches, proximity switches, motion detectors, photocells, timers and similar devices, all of which are known.  
         [0026]    While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.