Abstract:
The device ( 6 ) for unloading an open-top receptacle ( 2 ) filled with flat objects ( 3 ) arranged in a stack in the bottom of the receptacle comprises a pivoting member ( 18 ) capable of taking hold of the receptacle ( 2 ) and of downwardly inclining its opening ( 2   a ). The device ( 6 ) additionally comprises a pusher ( 26 ) for holding the flat objects ( 3 ) in place in the bottom of the receptacle ( 2 ) when the receptacle ( 2 ) is inclined, a shuttle compartment ( 7 ) moved by a conveyor ( 12 ) between the pivoting member ( 18 ) and a compartment unloading zone ( 13   b ) remote from the pivoting member ( 18 ), the compartment ( 7 ) having a bottom ( 7   b ) with rear ( 7   d ) and front ( 7   c ) walls which are removable with respect to the bottom ( 7   b ), a compartment inclination device ( 31 ) for inclining the compartment ( 7 ) into an inclined position in vertical alignment with the receptacle ( 2 ), and a moving pallet ( 14 ) which can be moved vertically and horizontally and which is designed so as to retract the front wall ( 7   c ) of the compartment ( 7 ) and to insert itself between the rear wall ( 7   d ) of the compartment ( 7 ) and the stack of flat objects ( 3 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a 35 U.S.C. 371 National Phase Application from PCT/FR2008/052070, filed Nov. 18, 2008, and designating the United States, which claims the benefit of U.S. Provisional Application No. 60/988,932, filed Nov. 19, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a device for unloading an open-top tray filled with flat articles, e.g. mailpieces, that are placed in a stack on the bottom of the tray, the device including a pivot member suitable for taking hold of the tray and for tilting its opening downwards. 
         [0004]    2. Discussion of the Background Art 
         [0005]    In general, during a mail sorting process, the mailpieces are transported in stacks inside trays by conveyors, and they are unloaded by an operator at a Tray Unloading Device (TUD). For example, the trays are brought from the sorting outlets of a sorting machine or from the outside towards the tray unloading device where the mailpieces are unloaded and then transferred to a feed magazine where the mailpieces are unstacked so as then to be transported towards other steps of the sorting process. 
         [0006]    Document EP 1 829 804 discloses an unloading device for automatically unloading articles, e.g. mailpieces, contained in a tray conveyed by a conveyor. That unloading device comprises a clamping and pivoting device  50  that firstly holds the tray firmly between a lid  21  and a base  48 , and that secondly causes the tray to pivot with the lid about a horizontal axis via articulated arms  22 ,  45 ,  47 , so as to cause the mailpieces to slide out of the tray via an opening  53  formed in the lid  21  and so as to direct them onto a guide plate  23 . However, while the tray is pivoting, the operator keeps a hand on the mailpieces so as to prevent them from slipping on one another and from falling into the tray too early, and then the operator must help the mailpieces to slide out of the pivoted tray. 
         [0007]    Patent Document U.S. Pat. No. 7,195,236 also discloses a system for unloading articles contained in a tray and for conveying them on a conveyor  20  to a feed magazine. The mailpieces F are initially placed in a stack on edge in a tray  160  that has a retractable or removable front wall  160 FR and that is transported by a conveyor  110  to an elevator  200  that lowers the mailpieces to the unloading system. That unloading system includes a device for raising the front wall  160 FR of the tray and a paddle  30  that is mounted to move vertically and horizontally and that is designed to be inserted into the tray between the mailpieces and a back wall  160 B of the tray, and then to push the mailpieces out of the tray, so that the mailpieces are transported directly on another conveyor  20  towards the feed unit. The paddle is comb-shaped and its teeth  30 T are complementary to tines  160 T on the back wall  160 B of the tray so as to facilitate inserting the paddle between the mailpieces and the back wall of the tray. A plurality of paddles  30 - 1 ,  30 - 2 ,  30 - 3  disposed in front of the first paddle serve to straighten up the mailpieces on the conveyor. However, in that system, it is an operator who initially loads the mailpieces in a stack on edge into the tray. 
         [0008]    The use of such unloading systems raises certain problems. For example, the trays must be transferred manually from the unloading point of the unloading system, and that is an arduous and tiring task for the operator in view of the weights of the trays and of the mailpieces, and of the distance to go along the conveyor for unloading each tray. In addition, the rate of throughput of the machine is slowed down because the operator cannot feed the feed magazine as quickly as would be necessary to keep up with the speed of the feed magazine. 
         [0009]    Document US 2007/0201968 also discloses a system for unloading mailpieces at the end of sorting from a standard tray to a shuttle while putting them in a stack, and then for unloading the stack of mailpieces from the shuttle to a special tray for a feed magazine. The standard tray  9  is loaded manually or automatically onto an unloading device having a pivot frame  22  provided with a closure plate for closing and blocking the tray  9 . The pivot frame pivots about a horizontal axis so as to cause the opening of the tray to face downwards, and a shuttle  8  is brought by a conveyor under the pivot frame, so as to receive the mailpieces  10  once the closure plate has been removed. The shuttles have V-shaped bottoms so as to jog and align the mailpieces. Then the shuttles are brought by a conveyor to a pivot device  52  so as to empty the mailpieces from the shuttle onto a surface  66  by means of a comb-shaped paddle  74  having its teeth complementary to ribs  86  on a wall of each of the shuttles. A plurality of pallets  73 ,  74  and  78 ,  79  serve to push the mailpieces towards the special tray  12  from which a removable or retractable wall is removed in order to enable the mailpieces to be loaded. 
       SUMMARY OF THE INVENTION 
       [0010]    An object of the invention is to propose another device for automatically unloading a tray filled with flat articles, e.g. mailpieces, that is automated so as to help an operator, so as to reduce the workload of the operator, and so as to avoid manual unloading tasks that are arduous for the operator. In addition, another object of the invention is to propose a device for unloading a tray filled with flat articles that transfers the flat articles semi-automatically from a tray transfer system to a feed magazine with both reduced action from the operator and also a high rate of unloaded trays. 
         [0011]    To these ends, the invention provides a device for unloading an open-top tray filled with flat articles placed in a stack on the bottom of the tray, the device comprising a pivot member suitable for taking hold of the tray and for tilting its opening downwards, said device being characterized in that it further comprises:
       a moving pusher suitable for holding the flat articles at the bottom of the tray when the tray is tilted by the pivot member;   a shuttle box suitable for being moved by a conveyor in both directions along a conveying axis between the pivot member and a box unloading zone remote from the pivot member, the shuttle box having a bottom with opposite back and front side walls along the conveying axis, which walls are retractable or removable relative to the bottom;   a box tilting device suitable for tilting the shuttle box into a tilted position immediately below the tray, and an opening device suitable for retracting the back wall of the tilted shuttle box and then for repositioning the back wall of the box on the box;   a moving paddle mounted on an articulated arm, which paddle is firstly suitable for being moved vertically by pivoting of the articulated arm from a low position at the same level as the bottom of the box to a high position above the box, and secondly suitable for being moved horizontally by sliding along a rail, the paddle being designed in such a manner as to retract the front wall of the box and as to be inserted between the back wall of the box and the stack of flat articles.       
 
         [0016]    With such an arrangement, parallel mail handling is performed with it being possible to achieve an unloading rate of 6 trays per minute. 
         [0017]    The device of the invention for unloading flat articles can present the following features:
       the bottom and the back and front walls of the box are provided with grooves, and the paddle is in the form of a comb having teeth adapted to be inserted into the grooves of the box;   the opposite left and right side walls of the shuttle box are equipped with a plurality of opposite notches designed to receive the back wall of the shuttle box so as to close the shuttle box in a plurality of different operational closure positions;   the pusher is in the form of an L-shaped comb having teeth adapted to be inserted into the grooves of the front wall of the shuttle box;   the device further comprises a crossing sensor for detecting the passing of a shuttle box between the pivot member and the box unloading zone, which sensor is suitable for holding the shuttle box in a stationary position in response to said crossing sensor detecting it going past; and       
 
         [0022]    a control button that, in response to being actuated, causes the conveyor to operate so as to move the shuttle box from said position to the box unloading zone and from the box unloading zone to the pivot member;
       the device further comprises a presence sensor for sensing the presence of a box in the box unloading zone, which sensor is suitable for stopping the conveyor if a shuttle box is present in the box unloading zone;   the pivot member comprises a frame suitable for holding the tray firmly, a pusher actuator suitable for moving the pusher from a first position outside the tray to a second position inside the tray, in which second position the pusher retains the flat articles at the bottom of the tray, and a frame actuator suitable for causing the frame to pivot with the pusher and with the pusher actuator about a horizontal axis so as to tilt the opening of the tray downwards; and   a second conveyor is provided in parallel with the first conveyor and a box diverter is provided for diverting the boxes from the first conveyor to the second conveyor.       
 
         [0026]    The invention also provides a mailpiece handling system comprising a postal sorting machine having a feed magazine and sorting outlets equipped with removable trays for storing the mailpieces in them, a tray transfer system that is arranged to bring full trays from the sorting outlets of the machine to the feed magazine of the machine and to bring empty trays to the sorting outlets of the machine, which trays have been previously emptied into the feed magazine of the machine or come from outside the machine, and said mail handling system further comprising a tray unloading device of the invention, interposed between the tray transfer system and the magazine of the machine. 
         [0027]    The invention also provides a method of unloading open-top trays filled with flat articles placed in a stack on the bottom of the tray, the method using a pivot member suitable for taking hold of the tray and for tilting its opening downwards, said method being characterized in that it comprises the steps consisting in:
       automatically moving an empty shuttle box by means of a conveyor between the pivot member and an unloading zone remote from the pivot member, the shuttle box having a bottom with opposite back and front side walls that are retractable or removable relative to the bottom, so as to bring the empty shuttle box, in a first stage, automatically to a tilted position immediately below the tray, also in a tilted position, by subjecting the box to an upward movement during which the back wall of the box is retracted so as to enable the flat articles to be transferred by sliding through the opening in the tray into the box;   automatically moving the full shuttle box for automatically bringing the shuttle box, in a second stage, towards the unloading zone in a downward movement during which the back wall of the box is re-positioned in an operational box closure position on the box;   automatically moving the full shuttle box in an essentially horizontal movement in translation to a waiting zone where the box going past is detected by a crossing sensor, the conveyor being stopped so as to hold the shuttle box in a stationary position in the waiting zone in response to the box going past being detected by said crossing sensor, and the conveyor being started again in response to a control button of the conveyor being actuated so as to move the shuttle box to the unloading zone;   moving a moving paddle mounted on an articulated arm downwards by pivoting of the arm so as to retract the front wall of the box;   moving the paddle horizontally by sliding it along a rail so as to place the paddle substantially vertically above the back wall of the box;   moving the paddle downwards by pivoting of the articulated arm so as to insert it between the back wall of the box and the stack of flat articles;   moving the paddle horizontally by sliding it along the rail so as to push said stack of articles out of the box;   moving the paddle downwards so as to reposition the front wall of the box in an operational box closure position on the empty shuttle box; and   automatically moving the empty shuttle box in an essentially horizontal movement in translation in the opposite direction in response to the control button of the conveyor being actuated so as to move the shuttle box towards the pivot member.       
 
         [0037]    The method of the invention can present the following features:
       the method comprises the steps consisting, prior to transferring the flat articles by sliding them through the opening of the tray into the shuttle box, in:       
 
         [0039]    bringing the tray into a frame suitable for holding the tray firmly; 
         [0040]    moving a moving pusher from a first position outside the tray to a second position inside the tray in which the pusher retains the flat articles at the bottom of the tray; 
         [0041]    causing the frame to pivot with the pusher and with the pusher actuator about a horizontal axis so as to tilt the opening in the tray downwards; and 
         [0042]    moving the moving pusher from said second position inside the tray to said first position outside the tray so as to transfer the flat articles into the shuttle box;
       after unloading of the shuttle box in the box unloading zone, the empty shuttle box is moved to a diversion zone in which the empty shuttle box is diverted towards a second conveyor parallel to the first conveyor.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]    The invention is described in more detail below with reference to the accompanying drawings which show non-limiting examples, and in which: 
           [0045]      FIG. 1  is a diagrammatic perspective view of a mailpiece handling system of the invention; 
           [0046]      FIG. 2  is a diagrammatic plan view of the mailpiece handling system of the invention; 
           [0047]      FIG. 3  is a diagrammatic perspective view of a portion of the tray unloading device of the invention with the tray in an initial position; 
           [0048]      FIG. 4  is a diagrammatic perspective view of the tray unloading device of  FIG. 2 , with the tray unloading device in a second position; 
           [0049]      FIG. 5  is a diagrammatic perspective view of the tray unloading device of  FIG. 2 , with the tray unloading device in a third position; 
           [0050]      FIG. 6  is a diagrammatic perspective view of the tray unloading device of  FIG. 2 , with the tray unloading device in a fourth position; 
           [0051]      FIG. 7  is a diagrammatic perspective view of the tray unloading device of  FIG. 2 , with the pivot member in a fifth position; 
           [0052]      FIG. 8  is a diagrammatic perspective view of the tray unloading device of  FIG. 2  with the pivot member in a sixth position; 
           [0053]      FIG. 9  is a diagrammatic perspective view of a shuttle box for the tray unloading device of the invention, with the shuttle box in an open-front position; and 
           [0054]      FIG. 10  is a flow chart showing the tray unloading steps of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0055]      FIG. 1  shows a handling system  1  of the invention for handling flat articles, e.g. mailpieces  3 , stored in horizontal stacks in trays  2 . The handling system includes a feed magazine  4  of a sorting machine and a tray transfer system  5 . The tray transfer system  5  is arranged to feed the full trays back from the outlets to the inlet of the machine. In particular, for example, it is arranged to cause full trays  2  to be brought automatically from the sorting outlets (not shown) of the sorting machine to the feed magazine  4  where said trays are unloaded, and to cause empty trays  2  that have been unloaded into the feed magazine  4  of the machine to be brought automatically to the sorting outlets. It can be understood that this tray transfer system also has an inlet for being loaded with full trays coming from outside the machine, which full trays are brought to the feed magazine, and also has an inlet for being loaded with empty trays also coming from outside the machine, which empty trays are brought to the sorting outlets of the machine. 
         [0056]    The mailpiece handling system  1  includes a semi-automatic tray unloading device  6  interposed between the tray transfer system  5  and the feed magazine  4  firstly for automatically unloading the trays  2  into shuttle boxes  7  disposed immediately below the trays  2 , and secondly for helping the operator to unload the mailpieces  3  from the boxes  7  into the feed magazine  4 , and for justifying or aligning the stack of mailpieces  3  going into the feed magazine  4 . Thus, unloading the trays  2  into the boxes  7  is not performed by the operator, which is quicker and less arduous for the operator. It can be understood that, in general, there is a single tray unloading device  6  per feed magazine  4 . The full shuttle boxes  7  can also be taken away towards the outside, e.g. once the sorting process is finished, rather than being brought to the feed magazine  4 . 
         [0057]    The tray transfer system  5  of the invention comprises firstly an inlet elevator  8  for taking the full trays  2  brought by a tray management system (not shown) of the sorting machine and for lowering them down to the level of the tray unloading device  6  by means of a conveyor  10  that is mounted to move vertically via a respective linear actuator (not shown), and secondly an outlet elevator  9  for raising the empty trays  2  back up to the level of the tray management system by means of a conveyor  11  that is mounted to move vertically via another respective linear actuator (not shown). The tray unloading device  6  comprises a pivot member  18  for causing a current tray  2  to pivot and for emptying it into a shuttle box  7  and a box conveyor  12  that brings the full shuttle box  7  in a movement essentially in horizontal translation to the magazine, making it possible to achieve a high rate of handling of the mailpieces in the sorting machine. 
         [0058]    As can be seen more precisely in  FIG. 2 , the box conveyor  12  brings at least one full shuttle box  7  from a box loading zone  13   a  immediately below the tray  2 , towards the feed magazine  4  in one direction along a conveying axis, as indicated by arrow A to a box unloading zone  13   b  where the box  7  is unloaded by the operator by means of a moving paddle  14 , the mailpieces  3  then being loaded into the feed magazine  4 . The box conveyor is designed also to operate in an opposite direction along the conveying axis towards the tray unloading device  6 , as indicated by arrow B in  FIG. 2 , so as to remove the empty boxes from the box unloading zone  13   b  towards the tray unloading device  6 . A box diverter  15  can be added along the conveyor  12  so as to direct an empty shuttle box  7  towards a second box conveyor  16  serving as a buffer or box accumulation zone  17  in which one or more boxes  7  remain waiting until there is no longer any box present in the tray unloading device  6  immediately below a tray  2 . 
         [0059]    The trays  2  that are used in this example are standard trays  2   a , each of which has an open top so that the mailpieces  3  can be loaded or unloaded, and a bottom  2   b  and four fixed side walls, as can be seen more clearly in  FIG. 8 . As can be seen more clearly in  FIG. 9 , each of the shuttle boxes  7  has an opening  7   a  at its top, a bottom  7   b  that is provided with grooves  7   h , front and back side walls  7   c ,  7   d  that are retractable or removable relative to the bottom  7   b  to enable the mailpieces  3  to be loaded or unloaded and each of which is provided with groves  7   i ,  7   j , and right and left side walls  7   e ,  7   f  that are provided with respective opposite notches  7   g , there being four notches on each of the right and left walls in this example, which notches are designed to receive the back wall  7   d  of the shuttle box  7  so that it is possible to put said back wall into a plurality of different operational closure positions for closing the box, thereby enabling the shuttle box to be adapted to accommodate mailpiece stacks of different thicknesses so as to transport different quantities of mailpieces  3 , as described below. 
         [0060]      FIG. 3  shows an enlarged view of the tray unloading device  6  that has a pivot member  18  for causing the tray  2  to pivot or tip about a horizontal axis C so as to tilt its opening  2   a  downwards. The pivot member  18  includes a frame  19  in which the tray  2  is held firmly, the frame being designed to prevent the tray from slipping while it is pivoting, and a frame actuator or articulated arm  20  that is connected to the frame for the purpose of causing the frame  19  containing the tray  2  to pivot. In this example, the articulated arm  20  has an arm segment  21  that is connected via a pivot at a first end  22  to the frame  19 , and at a second end  23  to a runner  24  of the articulated arm  20 , which runner is mounted to pivot on a shaft  25  that is substantially parallel to the axis C. 
         [0061]    As can be seen in  FIG. 3 , the pivot member  18  further includes a pusher  26  that is mounted to move by means of a pusher actuator  27  so as to hold the mailpieces  3  on the bottom of the tray  2  when the tray  2  is tilted so as to prevent the mailpieces  3  from moving or from slipping relative to one another while the mailpieces  3  are being transferred from the tray  2  to the shuttle box  7 , i.e. so to keep a stack of mailpieces properly formed. The pusher actuator  27  includes a runner  28  slidably receiving a slide  29   a  carrying a bar  29   b  extending substantially in the same direction as the axis C, and to which the pusher  25  is fastened, the runner  28  being mounted to pivot on a shaft  30  that is parallel to the axis C. Thus, the pusher  26  moves along the runner  28  from a first position outside the tray  2  (shown in  FIG. 7 ) towards a second position inside the tray  2  and in which the pusher  26  retains the mailpieces  3  at the bottom of the tray  2  (shown in  FIG. 3 ). 
         [0062]    Unloading mailpieces  3  from a tray  2  to a box  7  is described below with reference to  FIGS. 3 to 9 . 
         [0063]    A full tray  2  is firstly brought by the conveyor  10  of the elevator  8  to another conveyor  10 A of the tray unloading device  6  (shown more clearly in  FIG. 2 ) in an initial position inside the frame  19  inside which it is blocked, and the pusher  26 , initially in the high position above the tray  2 , is lowered to the low position along the slide  28  so as to hold the mailpieces  3  in a horizontal stack on the bottom of the tray  2 , as can be seen in  FIG. 3 . At the same time, an empty shuttle box  7  is brought by the conveyor  12  to immediately below the tray  2  in the tray unloading device  6 , whereupon the box  7  is tilted with its back wall  7   d  up by a box tilting device  31 , and the back wall  7   d  is retracted or removed by an opening device  32  as can be seen in  FIG. 4 . 
         [0064]    The tray  2  is then tilted, i.e. pivoted about the axis C, by a movement of the articulated arm  20  of the pivot member  18 , in which movement the arm segment  21  moves along a runner  24  as can be seen in  FIG. 5 , the mailpieces  3  being retained in the tray  2  by the pusher  26  that simultaneously pivots with the runner  28  about the shaft  30 . 
         [0065]    Then, the pusher  26  moves along the runner  28  so as to bring the mailpieces  3  into the box  7 , as can be seen in  FIG. 6 . The pusher  26  is advantageously implemented in the form of an L-shaped comb having a plurality of L-shaped teeth  33 , each tooth having a first portion  33 A fastened to the bar  29   b  and a second portion  33 B extending substantially perpendicularly to the first portion  33 A, and the teeth being adapted to be inserted into the grooves  7   j  in the front wall  7   c  of the box  7 , so that the mailpieces  3  are unloaded against the front wall  7   c  without changing the order of the mailpieces  3  in the stack. The pusher  26  is then removed from the box  7 , without however changing the order of the mailpieces  3  in the stack, as can be seen in  FIG. 7 , by deploying a telescopic device  29   c  mounted between the slide  29   a  and the bar  29   b  and that moves the pusher  26  away from the slide  28 . It can be understood that, since they are placed in a horizontal stack in the tray, the mailpieces  3  are transferred on the second portion  33 B of the teeth  33  and find themselves in a stack on edge in the box  7 . The back wall  7   d  of the box  7  is then put back in place by the box opening device  32 , in two opposite notches  7   g  in the left and right side walls as a function of the size of the stack of mailpieces  3  unloaded into the box. 
         [0066]    The tray  2  is then brought back to the horizontal on the conveyor  10  into its initial position shown in  FIG. 8  and in which the bottom of the tray  2  is substantially horizontal, by pivoting about the axis C caused by a movement of the articulated arm  20  of the pivot member  18  in which movement the arm segment  21  returns along the runner  24 . At the same time, the pusher  26  also returns to its initial position by the runner  28  pivoting about the shaft  30  and by the telescopic device  29   c  retracting. Finally, the box  7  is brought back to the horizontal by the box tilting device  31  so that its bottom wall  7   b  is substantially horizontal, and so that it is ready to be brought by the conveyor  12  to the feed magazine  4 . 
         [0067]    At the box unloading zone  13   b , the moving paddle  14  can be mounted on an articulated arm  35  that enables the operator to move the paddle  14  vertically, the arm being mounted on a rail  36  so as to enable the paddle  14  to slide horizontally. The paddle  14  can be fastened to the front wall  7   c  of the shuttle box  7  via a handle  7   k  so that the front wall  7   c  of the box  7  is retracted or removed when the operator raises the moving paddle  14  via a handle  34  on the paddle  14 , by causing the articulated arm  35  to pivot from a low position at the bottom  7   b  of the box  7  to a high position above the box  7 . The paddle is preferably in the form of a comb having teeth  14   a  adapted to be inserted into the grooves  7   i  in the back wall  7   d  of the box  7  so that the operator can slide the paddle  14  between the mailpieces  3  and the back wall  7   d  as can be seen in  FIG. 8 , by the teeth  14   a  engaging or meshing with the grooves  7   i  without touching the mailpieces  3 . The teeth  14   a  of the paddle  14  can be implemented in such a manner as also to mesh with the grooves  7   h  of the bottom wall  7   b  of the box  7 . In this manner, the stack of mailpieces  3  on edge is not unbalanced, or disorganized by the paddle  14  being inserted. The paddle  14  can be moved horizontally into the low position against the bottom  7   h  of the box  7  so as to push the mailpieces  3  out of the box  7  and so as to load them into the feed magazine  4 . In a variant, the articulated arm  35  can be omitted and it is then the operator who raises the paddle  14  directly, then causes it to slide along the rail  36 , and finally lowers it into the box  7  in order to unload the mailpieces  3 . 
         [0068]    For reasons of safety, the automatic tray unloading device  6  can be designed to prevent the operator having access to the device while said device is operating, e.g. by being designed to be covered. A safety device  37  can also be inserted along the conveyor  12  so as to protect the operator while the boxes  7  are being unloaded semi-automatically. For example, the safety device  37  can comprise a crossing sensor for detecting the passing of a shuttle box  7  in the direction A between the pivot member  18  and the box unloading zone  13   b , which sensor makes it possible to stop the conveyor  12  so as to hold the full shuttle box  7  stationary in a waiting zone  40  until a signal is received from the operator via a control button  38  that responds to being actuated by operating the conveyor  12  so as to move the full shuttle box  7  from its waiting position to the box unloading zone  13   b  where the shuttle box  7  is unloaded by the operator. In the same way, the control button  38  actuated by the operator triggers the conveyor  12  so as to cause it to advance in the opposite direction B for the purpose of moving the empty shuttle box  7  from the box unloading zone  13   b  to the pivot member  18 . 
         [0069]      FIG. 10  shows the steps for operation of the mailpiece handling system  1 . 
         [0070]    The full trays  2  containing the mailpieces  3  placed horizontally in respective stacks at the bottoms of the trays  2  are brought by a conveyor (not shown) from the sorting outlets of the sorting machine to the tray transfer system  5 . When the pivot member  18  is empty, in step  90 , a new full tray  2  is brought by the conveyor  10  into the inlet elevator  8 , and then, in step  91 , the full tray is lowered by the inlet elevator  8  to the level of the pivot member  18  of the tray unloading device  6 . In step  92 , the tray is transferred to the conveyor  10 A into the frame  19  inside which it is blocked, and the pusher  26  is brought onto the mailpieces  3  so as to block them at the bottom of the tray  2 . At step  93 , the tray  2  is tilted about the axis C by the pivot member  18  as described above, the pusher  26  undergoing the same movement so as to hold the mailpieces  3  in the tray  2 , and then the pusher  26  is shifted so as to transfer the mailpieces from the tray  2  to the shuttle box  7 . 
         [0071]    In step  94 , the empty tray  2  is taken by the conveyor  11  of the outlet elevator, and then raised back up to the level of the tray management system of the sorting machine either so as to be transported by the tray management system in step  95 , or else so as to be stored in the sorting machine in step  96 . 
         [0072]    In step  97 , the full shuttle box  7  is transferred by the conveyor  12  in the direction A to the feed magazine  4 , so as to be handled semi-automatically by the operator. If a first box  7  is already present in the box unloading zone  13   b , a signal delivered by a presence sensor  39  for sensing the presence of a box  7  placed in the box unloading zone  13   b  causes the conveyor  12  to stop until the first box has left the box unloading zone  13   b  and is directed by the diverter  15  towards the buffer zone  17 . The shuttle box  7  can then continue to advance in the direction A on the conveyor  12  until it reaches the waiting zone  40  where it is stopped automatically by the crossing sensor  37 . At step  98 , when the operator is ready, said operator actuates the control button  38  so as to cause the shuttle box  7  to advance in the direction A to the box unloading zone  13   b , and said operator empties the box  7  by means of the paddle  14  as described above. Then, in step  99 , the operator justifies the mailpieces  3 , i.e. further improves their alignment in the stack so as to make it easier for them to be handled or unstacked by the feed magazine  4  in step  100 . In step  101 , the operator actuates the control button  38  so as to cause the shuttle box  7  to return in the direction B towards the pivot member  8  in order to be loaded with mailpieces  3  thereat. 
         [0073]    Advantageously, a plurality of shuttle boxes  7  can then be used simultaneously in the various zones of the tray unloading device  6  in order to guarantee a high throughput rate for the sorting machine. In which case, a first shuttle box  7  is, for example, loaded in the box loading zone  13   a , while a second shuttle box  7  is being unloaded in the box unloading zone  13   b . Once said second shuttle box  7  has been unloaded and while it is returning in the direction B towards the pivot member  18 , it is diverted by the diverter  16  into the buffer zone  17  so as to allow the first shuttle box  7  to go past on the conveyor  12  towards the box unloading zone  13   b  while a third shuttle box  7  can be being loaded in the box loading zone  13   a.