Abstract:
A paper sheet gate actuation and guide system for a paper finishing device includes a guide rail, a drive system, a paper gate unit and a sliding cam unit. The guide rail is disposed along a side of the paper finishing device. The drive system includes a torque supplier to controllably supply torque, a timing belt connected to the torque supplier, and a plurality of pulleys to move laterally along the guide rail when the torque supplier supplies torque. The paper gate unit includes a gate arm to enable a paper sheet to pass through when the gate arm is opened, and a lift foot to open the gate arm when the lift foot is raised. The sliding cam unit includes a shoe to slide along the guide rail, a gate cam to raise the lift foot when engaged against the lift foot, a paddle to push a trailing edge of the paper sheet forward as the paper gate unit moves forward along the guide rail, and a fastener to attach the sliding cam unit to the timing belt.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relate to finishing devices and sorting devices for printers and/or copiers. 
     2. Description of Related Art 
     Devices that process sheets of paper, such as high-speed photocopiers, often require finishing operations to be performed. Such a finishing device causes the paper sheets to be deposited in manner either selected by the user or by a default fashion. 
     Many finishing devices and sheet stacking devices are known in the sheet handling equipment industry, involving different sheet ejection points for sheets of varying lengths. Conventional finishing devices convey paper sheets through a gate selected from a series of gates based on the length of the sheet being conveyed. Transporting the sheets to a compiling area in the finishing device typically requires redundant drive devices. In addition, a sheet constraint may be needed to align the trailing edge of the sheet as and/or after it passes through the appropriate gate. 
     In addition to multiple gate selectors, separate sheet constraints are employed in commercially available finishing devices. Consequently, a large number of moving components are required to complete a sheet finishing process, resulting in reduced reliability and shorter service life than desired. 
     SUMMARY OF THE INVENTION 
     In most downhill compiling systems, a different sheet ejection point is required for sheets of different lengths. Such systems in finishing and sorting devices typically use a series of gates to direct a sheet along a paper path. The sheet passes through an appropriate gate that is selected and actuated based on the length of a sheet being conveyed. 
     This invention provides devices and methods for opening a paper gate by a gate cam. 
     This invention further provides devices and methods for pushing a sheet by a paddle connected to the gate cam. 
     This invention also provides devices and methods for maintaining the gate open by the gate cam for a range of paper lengths. 
     This invention separately provides devices and methods for moving a gate cam by a stepper motor. 
     This invention separately provides devices and methods for moving the gate cam along a rail. 
     In various exemplary embodiments of the methods and devices according to this invention, a paper sheet entering a finishing device passes through a gate selected and controlled by a combined paper path selector, actuator and sheet constraint structure, which is referred to below as a combined gate system. In various exemplary embodiments, the selected gate is actuated by moving a sliding cam unit along one or more guide rails disposed along at least one side of the finishing device. 
     Upon entering into the finishing device, the sheet is transported along nip rollers until passing through the appropriate gate, which has been selected and opened based on the size of the sheet being conveyed by the combined gate system. 
     In various exemplary embodiments, the sliding cam unit includes a gate cam to raise a follower for actuating the gate. In various exemplary embodiments, the gate cam includes a forward ramp for a head surface, a horizontal plateau, and a rearward ramp for a tail surface. 
     In various exemplary embodiments, a paddle on the combined gate device constrains the sheet from becoming misaligned after passing through the combined gate device. 
     In various exemplary embodiments, the movable cam is connected to a sliding cam unit that moves along the guide system or structure by a drive system. In various exemplary embodiments, the drive system includes a stepper motor to move a driver belt that is connected to the sliding cam unit. 
     In various exemplary embodiments, the sliding cam unit travels over the one or two guide rails on polymer shoes or sliding structures. The sliding cam unit includes a gate cam formed as a wedge from molded plastic. In various exemplary embodiments, the rail and shoe materials are low friction materials. 
     The combined gate system enables precisely timed and positioned control of a sheet passing through to a finishing station. By combining gate actuation allowing a sheet to pass through with a paddle for preventing backlash of a sheet, the combined gate system improves reliability with fewer moving parts. 
     These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various exemplary embodiments of the methods of this invention will be described in detail with reference to the following figures, wherein: 
     FIG. 1 is an elevation view of one exemplary embodiment of a document handling apparatus in accordance with this invention; 
     FIG. 2 is an isometric view of an exemplary embodiment of a combined gate device in accordance with this invention; 
     FIG. 3 is an isometric view of the exemplary embodiment of the combined gate device of FIG. 2 with the gate activated by the cam; and 
     FIG. 4 is a flowchart outlining one exemplary embodiment of a method for selecting and restraining a sheet within a finishing device according to this invention. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In most downhill compiling systems, a different sheet ejection point is required for sheets of different lengths. Such systems in finishing devices typically use a series of gates to direct a sheet along a paper path. The sheet passes through an appropriate gate that is selected and actuated based on the length of a sheet being conveyed. In various exemplary embodiments, the selected gate is actuated by moving a sliding cam unit along one or more guide rails or rods disposed along at least one side of the finishing device. 
     A sheet of paper is fed horizontally into the finishing or sorting device and passes between pairs of nip rollers to control the velocity of the sheet along a guide path. The sheet passes through one of a series of gates, depending on the size of the sheet. The gates are sequenced with, the first gate for the largest and progressing downstream towards the last gate for the smallest sheets. The sheet is ejected through a selected gate by air pressure. 
     In various exemplary embodiments, motion is imparted to the sliding cam unit by a timing belt and pulleys connected to a stepper motor. The stepper motor allows precisely placing of the sliding cam unit to open the selected gate. The stepper motor provides repeatable performance over a long service life. In various other exemplary embodiments, motion to the sliding cam unit is imparted by a direct current motor, a lead screw or a separate solenoid for each gate. 
     In various exemplary embodiments, the drive system is also used to position a trailing edge of the sheet by using a rear paper restraining tamper or paddle to push the trailing edge of the sheet forward. Concurrent with opening the gate, the stepper motor positions the paddle for the length of the sheet of paper being conveyed along the guide path. The paddle can be moved back and forth a short distance without deactuating the selected gate, due to short flat surfaces on top of the gate cam. 
     In various exemplary embodiments, a long shuttle arm connects the paddle to the gate cam. The paddle can be positioned at the end of the shuttle arm that runs out to the mid-span of the guide path width. A paper-contact surface of the paddle can be fitted with a textile “grass” or other non-slip fibrous material to reduce slippage of the sheet and thereby prevent the edge of the sheet from sliding laterally or longitudinally along the paddle surface. The shuttle arm has provision for vertical adjustment. 
     The gate cam lifts sled-shaped followers as the gate cam travels down the guide path. Each follower or lift foot is attached to a single paper-diverting gate and pivots the appropriate gate open when lifted by the gate cam. The followers are vertically adjustable to ensure that each gate may open fully without jamming. 
     The gates are selected according to the lengths of the paper sheets to be run through the finishing device. The gate cam has a plateau on top allowing the gate cam to be positioned within a given length range while under each gate. This range allows the stepper to position the paddle into precise proximity to the trailing edge for each of the several paper lengths that may be fed through a particular gate. For example, letter size and A4 sheets can pass through the same gate, both standards having similar but not identical lengths. After several sheets have passed through one of the gates, the sheets rest on a temporary compiler to accumulate a set of sheets. When the temporary compiler is subsequently retracted to drop any sheets that may be suspended towards a collection station, the paddle prevents these sheets from retreating backwards. 
     The gate cam has head and tail surfaces extending from either side of the plateau. As the stepper motor moves the sliding cam unit forward or backward along the one or more guide rails, the head or tail surface of the gate cam engages the follower or lift foot on the selected gate. As the gate cam moves farther forward or backward, the follower is positioned within the plateau on top of the gate cam. The vertical rise of the follower causes the selected gate to open to allow the sheet to pass through that gate. Because the stepper motor translates the sliding cam unit so that the follower is positioned within the cam plateau at precisely defined times and positions, the sheet can be controlled through the selected gate accurately and reliably. 
     These principles can be depicted by the accompanying drawings. FIG. 1 provides an elevation view of a document handling apparatus  100 , such as a photocopier having an automatic document handler  110 , a transfer station  120  and a finishing device  130 . The document handler  110  includes a document source system  112  and a paper supply  114 . The document source system  112  feeds an original document to scan the image contents as scan signals. The paper supply  114  contains paper sheets  115  held in trays  116  based on their particular sizes. The sheets  115  are fed from the trays  116  from their leading edges  117  to their trailing edges  118 . 
     The transfer station  120  includes a control panel  122  and a transfer station  124 . The control panel  122  receives commands from the user for execution by the document handling apparatus  100 . The transfer station  124  receives the scan signals from the document source system  112  to produce a toner image, which is transferred to a sheet  115  of paper or other medium. After the toner image transfer is completed, the sheet  115  is guided by a transfer guide mechanism  126  to exit from the transfer station  124  through an aperture  128  to the finishing device  130 . 
     The sheet  115  is guided into the finishing station  130  along a sheet path by a finisher guide mechanism  132  between nip rollers  134 . For small output quantities that do not require any further processing or manipulation, the sheet  115  is then ejected to an output tray  136 . Larger output quantities require more elaborate stacking operations. Additionally, sets of any size may require manipulation by a manipulation device, such as a stapler, a hole punch, a perforation, a binder or the like. For such circumstances, the sheet  115  continues along the finisher guide mechanism  132  to a temporary compiler  137  for sorting and finishing before being deposited onto a collection station  138 . The sheets  115  are sorted by paper length through a diverter gate system  140 . 
     In various exemplary embodiments, the finishing device  130  contains structures and systems that operate on the sheets  115  before being deposited on the collection station  138  for cumulative stacking. The diverter gate system or unit  140  includes a series of diverter gates  141 . These mechanisms on the diverter gate system  140  distinguish the sheets  115  based on the length of the sheets. A sliding cam unit  150  activates a selected diverter gate  141  to open and allow a sheet  115  to pass through that diverter gate  141 . The sliding cam assembly  150  is moved along by a positioning system  160 . These assemblies and systems are described in further detail below. 
     FIGS. 2 and 3 show isometric views of various exemplary embodiments of the diverter gate system  140 , the sliding cam assembly (or unit)  150  and the positioning system  160 . FIG. 2 shows the sliding cam assembly  150  while approaching diverter gate system  140 . FIG. 3 shows the sliding cam assembly  150  engaging the diverter gate system  140 . 
     The diverter gate assembly  140  includes a series of diverter gates  141 . Depending on the length of the sheet  115 , an appropriate diverter gate  141  is selected to intercept the sheet  115  as the sheet  115  is transported by the finisher guide mechanism  132 . Each diverter gate  141  includes a gate arm  142  that intercepts the sheet  115 , one or more ribs  143  that guide the sheet  115 , edge tampers  144  that limit lateral migration of the sheet  115  and a lift foot or follower  145 . 
     The sliding cam assembly  150  includes a gate cam  153 . The sliding cam assembly  150  also includes a paddle  151  attached to the gate cam  153  by a shuttle arm  152 . The gate cam  153  includes a head surface  154 , a plateau or short flat surface  155 , and a tail surface  156 . The gate cam  153  and shuttle arm  151  are attached to each other by one or more flanges  157 . One or more guide rods or rails  158  along one edge of the finishing device  130  provide the path along, which the sliding cam assembly  150  travels. The flanges  157  are attached to one or more guide sleeves or shoes  159 , which wrap around the one or more guide rods  158  so the sliding cam unit  150  moves along the direction of the guide rod  158 . 
     The head surface  154  extends horizontally forward from the plateau  155  and vertically from below the lift foot  145  at rest to the plateau  155 , providing a forward curvilinear ramp. Similarly, the tail surface  156  extends horizontally rearward from the plateau  155  and vertically from the plateau  155  to below the lift foot  145 , providing a rearward curvilinear ramp. The forward and rearward curvilinear ramps form angles relative to the guide rails  158  that are adjusted based on minimized vertical acceleration of the lift foot  145 , the desired speed of the sliding cam assembly  150  and the available length of travel along the guide rod  158 . 
     As the sliding cam unit  150  moves forward along the guide rod  158 , the head or tail surface  154  or  156  engages the lift foot  145 . The plateau  155  raises or pivots the lift foot  145 , causing the gate arm  142  to change orientation. This opens the gate arm  142  of the diverter gate system  140  allowing the sheet  115  to pass through towards the temporary compiler  137 , as shown in FIG. 3, while the paddle  151  pushes the sheet  115  along the trailing edge  118 . 
     The sliding cam assembly  150  is transported along the guide rod  158  by a positioning system  160 . In various exemplary embodiments, the positioning system  160  includes a stepper motor  161 . The stepper motor  161  precisely moves the sliding cam assembly  150  along the one or more guide rods  158 . Rotational movement of the stepper motor  161  is transferred from a rotor  162  by a timing drive belt  163  suspended between two side pulleys  164  and  165  on either side of the stepper motor  161 . In other various exemplary embodiments, the positioning system includes a solenoid to activate a single gate. 
     The drive belt  163  is connected to the sliding cam assembly  150  between two end pulleys  166  and  167  by a fastener  168 . The stepper motor  161  turns the rotor  162 . This moves the drive belt  163  to slide the sliding cam assembly  150  towards the selected diverter gate  141 . The stepper motor  161  can be controlled by a controller (not shown) based on instructions provided through the control panel  122 . In various exemplary embodiments, the positioning system  160  can be positioned outboard of the sliding cam assembly  150 , as shown in FIGS. 2 and 3. In other various exemplary embodiments, the positioning system  160  can be positioned inboard of the sliding cam assembly  150 . 
     FIG. 4 is a flowchart outlining one exemplary embodiment of a method for controlling the diverter gate system  140 , the sliding cam assembly  150  and/or the positioning system  160 , in the finishing device  130 . Beginning in step S 200 , operation continues to step S 210 , where the leading edge  117  of the sheet  115  enters the finishing device  130  through the aperture  128  and is acquired by the nip rollers  134 . Next, in step S 220 , one of the diverter gates  141  of the finishing device  130  is selected based on the length of the sheet  115 . Then, in step S 230 , the positioning system  160  moves the sliding cam assembly  150  on the shoes  159  along the one or more guide rods  158  until the sliding cam assembly  150  is adjacent an edge of the finishing device  130 . Operation then continues to step S 240 . 
     In step S 240 , the gate cam  153  on the sliding cam assembly  150  raises the lift foot  145  on the selected diverter gate  141 . Then, in step S 250 , the lift foot  145  causes the gate arm  142  to change orientation such that the sheet  115  is diverted from the finisher guide mechanism  132 . Next, in step S 260 , the sliding cam assembly  150  is moved forward and backward so that the paddle  151  on the shuttle arm  152  tamps and pushes the trailing edge  118  of the sheet  115  forward. However, because of the plateau  155 , the lift foot  145  of the selected diverter gate  141  does not disengage from the sliding cam assembly  150 . Then, in step S 270 , moving the gate arm  142  allows the sheet  115  to pass through, while ribs  143  and edge tampers  144  limit lateral movement of the sheet  115 . Operation then continues to step S 280 , where operation of the method terminates. 
     While this invention has been described in conjunction with exemplary embodiments outlined above, many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the invention.