Apparatus for strapping stacks of sheet documents, apparatus for forming stacks of sheet documents and corresponding methods

Abstract

A strapping apparatus ( 100 ) is provided for strapping a stack (S) of sheet documents. The apparatus comprises: a strap feeder ( 160 ) adapted to feed a length of strap material (M) into the strapping apparatus; a guide channel ( 110 ) arranged to receive the leading edge of the strap material from the strap feeder, to guide the leading edge around a stack receipt zone ( 101 ) and to overlap the leading edge with an upstream portion of the strap material, resulting in overlapping portions of strap material in an overlap region of the guide channel, so as to form a closed loop of strap material around the stack receipt zone, the stack receipt zone being configured to accommodate a stack of sheet documents in use; a sealing unit ( 120 ) adapted to join the overlapping portions of the strap material to one another at a joining point; and a cutting unit ( 130 ) for cutting the strap material upstream of the joining point. The invention also provides a stacking apparatus ( 50 ) for forming stacks of sheet documents.

1 . A strapping apparatus for strapping a stack of sheet documents, the apparatus comprising:
 a strap feeder adapted to feed a length of strap material into the strapping apparatus;   a guide channel arranged to receive the leading edge of the strap material from the strap feeder, to guide the leading edge around a stack receipt zone and to overlap the leading edge with an upstream portion of the strap material, resulting in overlapping portions of strap material in an overlap region of the guide channel, so as to form a closed loop of strap material around the stack receipt zone, the stack receipt zone being configured to accommodate a stack of sheet documents in use;   a sealing unit adapted to join the overlapping portions of the strap material to one another at a joining point; and   a cutting unit for cutting the strap material upstream of the joining point.   
     
     
         2 . A strapping apparatus according to  claim 1  wherein the sealing unit is adapted to apply pressure to the overlapping portions of the strap material. 
     
     
         3 . A strapping apparatus according to  claim 2  wherein the sealing unit comprises a pressure member movable between a storage position in which the passage of the strap material is not impeded, and a sealing position in which the pressure member is extended towards the stack receipt zone at which, in use, the overlapping portions of the strap material are pressed against a stack of documents in the stack receipt zone. 
     
     
         4 . A strapping apparatus according to any of the preceding claims further comprising an adhesive station adapted to apply adhesive to the strap material. 
     
     
         5 . A strapping apparatus according to  claim 4  wherein the adhesive station is disposed upstream of the overlap region of the guide channel. 
     
     
         6 . A strapping apparatus according to  claim 4  or  claim 5  wherein the adhesive station is disposed between the guide channel and the strap feeder. 
     
     
         7 . A strapping apparatus according to any of  claims 4  to  6  wherein the adhesive station is configured to apply adhesive adjacent the leading edge of the strap material on its surface forming the outer surface of the loop. 
     
     
         8 . A strapping apparatus according to any of  claims 4  to  7  wherein the adhesive station is configured to apply adhesive adjacent a trailing edge position of the strap material on its surface forming the inner surface of the loop. 
     
     
         9 . A strapping apparatus according to any of the preceding claims further comprising a tensioning unit arranged to adjust the tension of the loop of strap material prior to sealing by the sealing unit. 
     
     
         10 . A strapping apparatus according to  claim 9  wherein the tensioning unit comprises means for reversing the trailing edge of the strap material out of the guide channel. 
     
     
         11 . A strapping apparatus according to  claim 10  wherein the tensioning unit further comprises retardation means arranged to oppose reversal of the leading edge of the strap material, preferably a brake arranged to hold the leading edge of the strap material at a fixed position. 
     
     
         12 . A strapping apparatus according to  claim 11  wherein the retardation means comprises a clamp portion of the guide channel which is movable relative to the remainder of the guide channel from a guiding position, in which the clamp portion is arranged to guide the leading edge of the strap material into a closed loop, in conjunction with the remainder of the guide channel, and a clamping position, in which at least part of the clamp portion is extended toward the stack receipt zone so as to, in use, press a portion of the strap material against the stack of documents. 
     
     
         13 . A strapping apparatus according to  claim 12 , wherein the clamp portion of the guide channel is pivotable between the guiding position and the clamping position, an end of the clamp portion extending toward the stack receipt zone when the clamp portion is in the clamping position. 
     
     
         14 . A strapping apparatus according to any of the preceding claims further comprising means for reversing the trailing edge of the strap material out of the guide channel. 
     
     
         15 . A strapping apparatus according to any of the preceding claims wherein the strap feeder is further adapted for reversal of the strap material out of the strapping apparatus. 
     
     
         16 . A strapping apparatus according to any of the preceding claims further comprising at least one sensing unit for sensing the position of the leading edge of the strap material. 
     
     
         17 . A strapping apparatus according to any of the preceding claims further comprising a stack support assembly arranged outside the guide channel and configured to support the stack of sheet documents within the stack receipt zone at a position spaced from the guide channel. 
     
     
         18 . A strapping apparatus according to any of the preceding claims wherein the guide channel is configured so as to receive the strap material on the innermost surface of the guide channel in the region of the strap material, such that in use the closed loop of strap material is formed around the stack receipt zone only. 
     
     
         19 . A strapping apparatus according to any of the preceding claims wherein the guide channel comprises one or more guide elements encircling the stack receipt zone, arranged to receive the leading edge of the stack material on their interior surface. 
     
     
         20 . A strapping apparatus according to  claim 19  wherein the one or more guide elements form a substantially closed loop, at least part of the one or more guide elements overlapping, and the overlapping portions of the guide elements being spaced from one another so as to receive the leading edge of the strap material therebetween. 
     
     
         21 . A strapping apparatus according to  claim 19  or  claim 20  wherein the guide channel comprises first, second and third guide elements, the second and third guide elements being movable relative to each other and to the first guide element. 
     
     
         22 . A strapping apparatus according to  claim 21  wherein the first guide element forms a base portion of the guide channel and is in fixed relation to the stack receipt zone. 
     
     
         23 . A strapping apparatus according to  claim 21  or  claim 22  when dependent on at least  claim 12  wherein the second guide element constitutes the clamp portion of the guide channel and is spaced from and arranged to at least partially overlap a portion of the first guide element. 
     
     
         24 . A strapping apparatus according to any of  claims 21  to  23  wherein the third guide element forms an upper portion of the guide channel and is movable between a guiding position in which the third guide element adjoins the first and second guide elements to guide the leading edge of the strap material to form a closed loop, and an open position in which the third guide element is removed from the first and second guide elements so as to permit entry of sheet documents into the stack receipt zone. 
     
     
         25 . A method of strapping a stack of sheet documents positioned at a stack receipt zone, the method comprising:
 a) feeding the leading edge of a length of strap material into a guide channel arranged to guide the leading edge around the stack receipt zone and to overlap the leading edge with an upstream portion of the strap material, resulting in overlapping portions of strap material in an overlap region of the guide channel, so as to form a closed loop of strap material around the stack receipt zone;   b) sealing the overlapping portions of strap material to one another at a sealing point; and   c) cutting the strap material upstream of the sealing point.   
     
     
         26 . A method according to  claim 25 , wherein in step (a), the strap material is received by the innermost surface of the guide channel in the region of receipt of the stack material so as to form the closed loop around only the stack receipt zone. 
     
     
         27 . A method according to  claim 25  or  claim 26 , further comprising placing a stack of sheet documents into the stack receipt zone either before, during or after step a), and prior to step b). 
     
     
         28 . A method according to  claim 27 , wherein the stack of sheet documents is supported at a position within the stack receipt zone spaced from the guide channel by a stack support assembly outside the guide channel. 
     
     
         29 . A method according to any of  claims 25  to  28 , wherein step b) comprises applying pressure to the overlapping portions of strap material. 
     
     
         30 . A method according to  claim 29  wherein pressure is applied to the overlapping portions of strap material by pressing them against the stack of sheet documents. 
     
     
         31 . A method according to any of  claims 25  to  30  wherein at least portions of the strap material are self-adhesive. 
     
     
         32 . A method according to any of  claims 25  to  30  further comprising a step of applying adhesive to the strap material. 
     
     
         33 . A method according to  claim 32  wherein adhesive is applied to the strap material at a location upstream of the overlap region of the guide channel. 
     
     
         34 . A method according to  claim 32  or  33  wherein adhesive is applied to the strap material at a location upstream of the entrance to the guide channel. 
     
     
         35 . A method according to any of  claims 32  to  34  wherein adhesive is applied adjacent the leading edge of the strap material on its surface forming the outer surface of the loop. 
     
     
         36 . A method according to any of  claims 32  to  34  wherein adhesive is applied adjacent a trailing edge position of the strap material on its surface forming the inner surface of the loop. 
     
     
         37 . A method according to any of  claims 32  to  36  wherein the adhesive is a pressure adhesive or a contact adhesive. 
     
     
         38 . A method according to any of  claims 25  to  37  further comprising a step of tensioning the loop of strap material prior to step b). 
     
     
         39 . A method according to  claim 38  wherein the tensioning step comprises reversing the trailing edge of the strap material out of the guide channel. 
     
     
         40 . A method according to  claim 39  wherein the tensioning step further comprises retarding motion of the leading edge of the strap material while the trailing edge is reversed. 
     
     
         41 . A method according to  claim 40  wherein motion of the leading edge of the strap material is retarded by moving a clamp portion of the guide channel relative to the remainder of the guide channel from a guiding position in which the clamp portion is arranged to guide the leading edge of the strap material into a closed loop, in conjunction with the remainder of the guide channel, into a clamping position, in which at least part of the clamp portion extends toward the stack receipt zone so as to press a portion of the strap material against the stack of documents. 
     
     
         42 . A method according to any of  claims 25  to  41  further comprising, after step c), reversing the new leading edge formed by cutting the strap material out of the guide channel. 
     
     
         43 . A method according to any of  claims 25  to  42 , wherein the guide channel comprises a plurality of guide elements movable relative to one another, further comprising, prior to performing step a), the steps of:
 i) removing at least one of the guide elements from the guide channel, so as to provide an opening; 
 ii) receiving sheet documents at the stack receipt zone through the opening so as to form a stack; and 
 iii) returning the at least one of the guide elements to the guide channel, so as to substantially close the opening. 
 
     
     
         44 . A stacking apparatus for forming stacks of sheet documents, comprising:
 a stacker unit adapted to receive sheet documents from a transport path and to output the sheet documents face to face;   a stack support surface for receiving the sheet documents from the stacker unit so as to form a first stack, and supporting the first stack thereon;   a separation unit adapted to deploy a separator member between a selected sheet document received by the stacker unit and the next, the separator member being movable between a home position, in which the separator member does not impede passage of the sheet documents, and a holding position between the stacker unit and the stack support surface, at which the separator member receives stacked sheet documents from the stacker unit so as to form a second stack thereon, the second stack being spaced from the first stack such that the first stack can be removed from the stack support surface while the second stack is being formed; and   a controller adapted to control the deployment of the separator member.   
     
     
         45 . A stacking apparatus according to  claim 44 , wherein the separation unit is further adapted to retract the separator member once the first stack has been removed from the stack support surface such that the second stack is placed on the stack support surface. 
     
     
         46 . A stacking apparatus according to  claim 44  or  claim 45 , wherein the separator member is arranged to move from the home position to the holding position along a deployment path which follows the path of a sheet document through the stacking unit. 
     
     
         47 . A stacking apparatus according to any of  claims 44  to  46 , wherein the separator member is arranged to move from the holding position to the home position along a retraction path which follows the path of a sheet document between the holding position and the stack support plate, and does not intercept the path of sheet documents through the apparatus between the stack support plate and the home position. 
     
     
         48 . A stacking apparatus according to any of  claims 44  to  47 , wherein the separator member is arranged to follow a path which is a continuous loop. 
     
     
         49 . A stacking apparatus according to any of  claims 44  to  48 , wherein the stacking unit comprises at least one stacker wheel, the or each stacker wheel having a plurality of tines extending from a central hub, each pair of the plurality of tines defining a channel therebetween for receiving a sheet document from the transport path at a receipt position, and stacker drive means for rotating the or each stacker wheel such that, at a release position, the sheet documents exit the channel(s) facing one other to thereby form a stack, the receipt position being angularly displaced from the release position. 
     
     
         50 . A stacking apparatus according to  claim 49 , wherein the separator member is arranged to follow a path which includes an arcuate portion concentric with the at least one stacker wheel such that the separator member follows the path of a sheet document carried by a channel of the at least one stacker wheel between the receipt and release positions. 
     
     
         51 . A stacking apparatus according to  claim 49  or  50 , wherein, in the home position, the separator member is disposed in line with or behind the trailing tine of a channel of the stacker wheel(s) at the receipt position, such that a sheet document arriving at the stacker wheel is not prevented from entering the channel. 
     
     
         52 . A stacking apparatus according to any of  claims 44  to  51 , wherein the separator member is moved between its home and holding positions by a timing belt driven by a motor, preferably a stepper motor. 
     
     
         53 . A stacking apparatus according to any of  claims 44  to  52 , wherein the separator member is supported by a carriage mounted on a track along which the separator member is movable between its home and holding positions. 
     
     
         54 . A stacking apparatus according to any of  claims 44  to  53  wherein the separation unit further comprises a home sensor configured to detect when the separation member is at its home position. 
     
     
         55 . A stacking apparatus according to any of  claims 44  to  54  wherein the separation unit is configured to stop the separator member at the holding position when a predetermined duration has elapsed since the separator member left the home position. 
     
     
         56 . A stacking apparatus according to any of  claims 44  to  55  wherein the separation unit further comprises a stack sensor configured to detect when the first stack has been removed from the stack support plate. 
     
     
         57 . A stacking apparatus according to any of  claims 49  to  56 , wherein the separator member comprises an elongate member having an arcuate shape, preferably of substantially the same form as a tine of the stacker wheel(s). 
     
     
         58 . A stacking apparatus according to any of  claims 44  to  57  wherein the separator member is hinged so as to provide a substantially flat surface for forming the second stack thereon, a hinge preferably being provided at approximately the midpoint of the separator member. 
     
     
         59 . A document handling apparatus comprising a stacking apparatus according to any of  claims 44  to  58 , and a strapping apparatus according to any of  claims 1  to  24 . 
     
     
         60 . A document handling apparatus according to  claim 59  wherein the stack support plate of the stacking apparatus is arranged to support the first stack within the stack receipt zone of the strapping apparatus. 
     
     
         61 . A document handling apparatus according to  claim 59  or  claim 60 , further comprising a transport unit for transporting the first stack from the stack support plate of the stacking apparatus to the stack receipt zone of the strapping apparatus. 
     
     
         62 . A method of stacking sheet documents, comprising:
 receiving documents from a transport path into a stacker unit;   outputting the received documents face to face from the stacker unit;   receiving the outputted documents on a stack support surface so as to form a first stack;   when a selected sheet document is received into the stacker unit, deploying a separator member between the selected sheet document and the next, by moving the separator member from a home position in which the passage of sheet documents is not impeded, to a holding position disposed between the stacker unit and the stack support surface;   receiving the outputted documents on the separator member so as to form a second stack spaced from the first stack; and   removing the first stack from the stack support surface.   
     
     
         63 . A method according to  claim 62 , further comprising halting the separator member at the holding position until the first stack is removed from the stack support surface. 
     
     
         64 . A method according to  claim 62  or  claim 63 , further comprising retracting the separator member once the first stack is removed such that the second stack is placed on the stack support surface. 
     
     
         65 . A method according to any of  claims 62  to  64  wherein the separator member is moved from the home position to the holding position along a deployment path which follows the path of a sheet document through the stacking unit. 
     
     
         66 . A method according to any of  claims 62  to  65 , wherein the separator member is moved from the holding position to the home position along a retraction path which follows the path of a sheet document between the holding position and the stack support plate, and does not intercept the path of sheet documents through the apparatus between the stack support plate and the home position. 
     
     
         67 . A method according to any of  claims 62  to  66 , wherein the movement of the separator member from the home position to the holding position and back to the home position follows a path which is a continuous loop. 
     
     
         68 . A method according to any of  claims 62  to  67 , wherein the stacking unit comprises at least one stacker wheel, the or each stacker wheel having a plurality of tines extending from a central hub, each pair of the plurality of tines defining a channel therebetween for receiving a sheet document from the transport path at a receipt position, and the or each stacker wheel is driven to rotate such that, at a release position, the sheet documents exit the channel(s) facing one other to thereby form a stack, the receipt position being angularly displaced from the release position. 
     
     
         69 . A method according to  claim 68 , wherein the separator member follows a path which includes an arcuate portion concentric with the at least one stacker wheel so as to follow the path of a sheet document carried by a channel of the at least one stacker wheel between the receipt and release positions. 
     
     
         70 . A method according to any of  claims 62  to  69  further comprising detecting when the separation member is at its home position. 
     
     
         71 . A method according to  claim 70  wherein the separator member is decelerated or halted at the holding position when a predetermined duration has elapsed since the separator member left the home position. 
     
     
         72 . A method according to any of  claims 62  to  71  further comprising detecting when the first stack has been removed from the stack support plate. 
     
     
         73 . A method according to any of  claims 62  to  72  wherein the first stack is removed from the stack support surface while the second stack is being formed. 
     
     
         74 . A method according to any of  claims 62  to  73  further comprising strapping the first stack in accordance with the method of any of  claims 25  to  43 .