Inductor station for sortation conveying system

An inductor station for a sortation conveying system is able to accommodate an assortment of substantially rectangular items which in general each have unique dimensions. A worker loads the inductor station with a charge of items each standing upright on edge and side-by-side. The charges are loaded in sequence to a feeder tray, and a programmably controlled feeding assembly feeds the charges along the feeder tray to a loading mechanism. The loading mechanism loads the endmost item from a discharge end of the feeder tray onto a takeaway conveyor. The items are loaded on the takeaway standing upright and on edge. An indexing motion stripping conveyor is used to time the loading of the items onto the takeaway conveyor so that the items are conveyed to an appropriate pocket on the core conveyor for the sortation conveying system. The feeding assembly and the loading assembly are each programmably controlled to coordinate movement of items through the inductor station with each item substantially maintaining its upright orientation.

FIELD OF THE INVENTION
 The invention relates to sortation conveying systems used to fulfill orders
 of assorted rectangular items such as books, packaged software, compact
 discs, games, video cassettes, etc. In particular, the invention relates
 to an inductor apparatus that loads items into assigned pockets on a core
 conveyor for the sortation system in single file with each item standing
 upright on edge in an essentially vertical orientation, thus facilitating
 efficient downstream processing and sorting.
 BACKGROUND OF THE INVENTION
 In centralized distribution applications, order fulfillment is often
 accomplished using computer controlled sortation conveying systems. Such
 systems can sometimes have lengths approaching 300 feet. Quite often, it
 is desirable that the sortation system be capable of fulfilling orders of
 intermingled items having assorted sizes. For example, it is not uncommon
 for an order to require a selected number of books having assorted sizes,
 intermingled with video cassette containers, compact disc containers,
 software, or the like.
 In sortation conveying systems, a core conveyor conveys assorted items in
 single file, preferably in an upright position standing on edge so that
 bar code readers can easily identify the item prior to subsequent sorting
 and processing downstream. One type of core conveyor has separators or
 cleats dividing the conveyor belt into individual pockets. Sortation
 conveying systems normally include several inductor stations that are
 coordinated with the core conveyor to supply items to the pockets on the
 core conveyor in an organized manner. The items within the pockets on the
 core conveyor are then processed, sorted and stacked into separate
 outgoing orders. It is not unusual for outgoing orders to consist of
 hundreds of intermingled items, each generally having a rectangular shape
 but unique dimensions.
 This invention relates to improvements to the operation of the inductor
 stations that load the items onto the core conveyor. It is desirable that
 workers be able to load assorted items into the inductor station in an
 easy and efficient manner, and that the inductor station be able to have
 items continually ready for loading onto the core conveyor under normal
 operating conditions. Preferably, the items should be standing upright on
 edge as the items are loaded onto the core conveyor. It is also desirable
 that the inductor stations be capable of efficiently handling assorted
 items having various dimensions.
 SUMMARY OF THE INVENTION
 The invention provides an inductor station that is able to accept charges
 of assorted items at an inconsistent or sporadic rate, yet is designed to
 continuously provide individual items ready for loading into assigned
 pockets in the core conveyor. In its preferred configuration, the inductor
 station accepts an assortment of substantially rectangular items each
 standing upright on edge and grouped in series side-by-side with other
 items. Each group of assorted items loaded into the inductor station is
 referred to as a charge. Each charge of assorted items is conveyed into a
 feeder tray for the inductor station in sequence one charge at a time,
 preferably using a gravity feed ramp with retractable queuing plates. A
 feeding assembly feeds the charge of assorted items along the feeder tray
 to a loading mechanism located at a discharge end of the feeder tray. The
 loading mechanism strips the endmost item from the charge, and loads the
 item onto a takeaway conveyor with the item standing upright on edge. The
 loading mechanism and takeaway conveyor belt are controlled in sync with
 the core conveyor to load the respective item into an assigned pocket on
 the core conveyor. Preferably, this is accomplished using a
 computer-controlled indexing motion stripping conveyor to load the items
 from the charge on the feeder tray in single file onto the takeaway
 conveyor belt.
 The invention is particularly efficient and reliable because each
 respective item is loaded into the inductor station standing upright on
 edge, and maintains an upright on edge orientation as it passes through
 the inductor station and into the assigned pocket on the core conveyor.
 Maintaining consistent upright on-edge orientation allows for effective
 continued alignment of items being processed through the inductor station,
 and therefore reduces the risk of misfeeds and enhances throughput.
 In the preferred embodiments of the invention, the feeding assembly, which
 feeds the assorted items along the feeder tray to the loading mechanism,
 includes two pushing mechanisms: namely, a main pushing mechanism and a
 secondary pushing mechanism. The operation of the main pushing mechanism
 and the secondary pushing mechanism are coordinated electronically to
 facilitate substantially continuous feeding of assorted items to the
 loading mechanism. More specifically, the main pushing mechanism uses a
 pushing hand mounted for travel along the feeder tray between a home
 location and a stop location for the main pushing mechanism. The home
 location for the main pushing mechanism is located on the side of the
 feeder tray opposite the discharge end of the feeder tray. The main
 pushing mechanism is positioned at its home location when the feeder tray
 is ready to receive the next charge of assorted items. The main pushing
 mechanism then applies pressure against the charge to move the charge of
 assorted items along the feeder tray to the loading mechanism at the
 discharge end of the feeder tray. As mentioned, the endmost item in the
 charge is loaded onto the loading mechanism. In order to facilitate
 appropriate cooperation between the pushing mechanism and the loading
 mechanism, the pushing mechanism pushes in a controlled pulsating manner
 such that the pushing pressure is relieved when the endmost item is loaded
 from the feeder tray onto the loading mechanism. The pushing pressure is
 reapplied after the endmost item has been loaded onto the takeaway
 conveyor and the loading mechanism is ready to be loaded with the next
 item in the charge. The controlled pulsating action is preferred because
 it is desirable to relax the tension in the charge after the endmost item
 is loaded into the loading mechanism in order to reduce frictional and
 normal forces operating between the endmost item and the next item in the
 charge. The relaxation improves the reliability of the loading mechanism
 and helps to prevent misalignment and misfeeds. The secondary pushing
 mechanism has a retractable pushing hand that is mounted for travel along
 the feeder tray between a home location for the secondary pushing
 mechanism and the discharge end of the feeder tray. The home location for
 the secondary pushing mechanism is located between the home location for
 the main pushing mechanism and the discharge end of the feeder tray, and
 preferably substantially closer to the discharge end of the feeder tray.
 As the main pushing mechanism moves the charge along the feeder tray and
 becomes close to the discharge end of the feeder tray, the secondary
 pushing mechanism is implemented as a substitute for the main pushing
 mechanism. After substitution, the main pushing mechanism returns to its
 home location ready to accept the next charge of assorted items while the
 secondary pushing mechanism continues to feed the remainder of the charge
 to the loading mechanism. The pushing hand for the secondary pushing
 mechanism retracts for travel under the floor of the feeder tray as it
 returns towards its home position prior to substitution for the main
 pushing mechanism, thus avoiding interference with assorted items in the
 feeder tray as it returns. When it is time for the secondary pushing
 mechanism to substitute for the main pushing mechanism, the fingers on the
 pushing hand for the secondary pushing mechanism extend upward through
 slots in the feeder tray and into openings in the hand for the main
 pushing mechanism. The secondary pushing mechanism then continues to feed
 the charge towards the loading mechanism, and the main pushing mechanism
 returns to its home position in order to receive the next charge of
 assorted items.
 In another embodiment, the feeding assembly uses a stabilizing hand to
 prevent the endmost items from tipping in the feeder tray. The stabilizing
 hand is preferably mounted for travel along the feeder tray between the
 home location for the secondary pushing mechanism and the discharge end of
 the feeder tray. The stabilizing hand is retractable, like the hand for
 the secondary pushing mechanism. While movement of the main pushing
 mechanism and movement of the secondary pushing mechanism are
 independently powered and controlled for coordinated operation (preferably
 using pneumatic controls to slide the mechanisms along the linear
 bearings), the movement of the stabilizing hand is not powered. Rather,
 the stabilizing hand travels towards the discharge end of the feeder tray
 when it is pushed by a charge of assorted items being pushed by the main
 pushing mechanism. In this manner, the stabilizing hand prevents the
 endmost item in the charge from tipping in the feeder tray. When the
 stabilizing hand approaches the remaining portion of the previous charge
 on the loading mechanism, the stabilizing hand retracts. The stabilizing
 hand then returns to its home position, which is the home position for the
 secondary pushing mechanism, when it is pushed by the retracted secondary
 pushing mechanism returning to its home position. Preferably, separate
 pneumatic lifts control the retraction of the pushing hand for the
 secondary pushing mechanism and the retraction of the stabilizing hand,
 although it is preferred that these pneumatic lifts be operated in unison.
 In this embodiment, the openings in the hand of the main pushing mechanism
 should be sufficiently large to accommodate both the fingers on the
 pushing hand for the secondary pushing mechanism and the fingers on the
 stabilizing hand.
 The preferred loading mechanism is designed to ensure that only the endmost
 item from the charge of assorted items on the feeder tray is loaded onto
 the takeaway conveyor belt per each loading cycle. This sometimes can be
 difficult because friction between adjacent items within the group is
 often significant, especially when boxed items are wrapped in film. The
 preferred loading mechanism overcomes the friction attraction forces and
 substantially reduces the probability of misfeeds and misalignment. The
 loading mechanism comprises a lift to lift the endmost item of the charge.
 A substantially vertical guide plate is located adjacent the lift and
 substantially perpendicular to the feeder tray. A vertical stripping
 conveyor is located adjacent the guide plate on the side opposite the
 lift. The stripping conveyor has cleats extending from the conveyor beyond
 the guide plate in the direction of the lift. The stripping conveyor is
 preferably an indexing motion stripping conveyor which is
 computer-controlled to coordinate operation with the core conveyor. The
 feeding assembly pushes the endmost item against the guide plate and onto
 the lift. The item on the lift is lifted and then the stripping conveyor
 indexes forward to push the item onto the takeaway conveyor.
 The lift is preferably a pivotally mounted lever and has an actuation arm
 for moving the lever between a lowered position and a raised position. The
 top surface of the lever preferably has a width that is less than the
 width of assorted items fed to the lift, thereby ensuring that it lifts
 only the endmost item in the charge on the feeder tray. The loading
 mechanism also preferably includes a holdback member that is located
 between the lift and the takeaway conveyor belt. The holdback member is a
 rail or some other object defining a horizontal obstacle for items lying
 in the feeder tray immediately upstream of the infeed to the takeaway
 conveyor belt. The height of the horizontal obstacle is preferably no
 higher than the loading height for the takeaway conveyor belt. When the
 endmost item is loaded onto the takeaway conveyor belt, the holdback
 member holds subsequent items in the charge in place within the feeder
 tray even if there is significant frictional attraction between adjacent
 items. The lift raises the endmost item so that the lower edge of the item
 is raised at least as high as the loading height of the takeaway conveyor
 belt and above the horizontal obstacle of the holdback member, and at the
 appropriate time the stripping conveyor pushes the item onto the takeaway
 conveyor belt.

DETAILED DESCRIPTION OF THE INVENTION
 FIG. 1 illustrates a sortation conveying system 10 that is capable of
 fulfilling orders of intermingled items having assorted sizes, such as
 assorted books, intermingled with video cassette containers, compact disc
 containers, packaged software, or the like. The sortation conveying system
 10 includes a core conveyor belt 12 that extends for essentially the
 entire length of the sortation conveying system 10, e.g. approximately 300
 feet. The core conveyor belt 12 is divided into pockets 14 of equal length
 (see reference numeral 14 in FIG. 2). Each pocket 14 is separated by a
 cleat 16, FIG. 2, on the conveyor belt 12. The core conveyor 12 operates
 at a relatively high rate of speed, for example, approximately 250 parts
 per minute can be processed and sorted by the system 10.
 Referring still to FIG. 1, the sortation conveying system 10 includes a
 plurality of inductor stations 18 that load items onto the core conveyor
 belt 12. Each of the items is loaded onto the core conveyor belt 12
 standing upright on edge and into an assigned pocket 14 on the core
 conveyor belt 12. The core conveyor belt 12 then conveys the items single
 file for downstream processing and sorting. The system 10 includes a bar
 code reading station 20 that is able to accurately and quickly identify
 the item being moved by the core conveyor 12. The system 10 may also
 include a label application station 22 for applying a label to each item
 on the core conveyor 12. At the downstream end of the system 10, the items
 pass through a guide assembly 24 that includes a series of diverting gates
 or doors which are selectively operated to divert items passing along the
 core conveyor 12 into several stacking stations 26. FIG. 1 shows twelve
 stacking stations 26, each allocated to a specific outgoing order of
 assorted items. The computer control system for the sortation system 10
 programs the guide assembly 24 to sort the items traveling on core
 conveyor 12 into the appropriate stacking station 26 to fulfill the
 assigned order. Orders typically contain up to or more than 100 assorted
 items. If an item on the core conveyor is not diverted in the one of the
 several stacking stations (e.g. the item was loaded onto the system 10 but
 was not required to fulfill an order), the item is sent to a downstream
 bin and can be reprocessed at a later time.
 Referring now to FIG. 2, the operation of each of the inductor stations
 18a, 18b, 18c is controlled by a dedicated programmable controller 28a,
 28b, 28c. Each of the programmable controllers 28a, 28b, 28c, communicates
 with a master controller 30 for the system 10. The controllers 28a, 28b,
 28c are programmed to independently control the operation of the
 respective inductor stations 18a, 18b, 18c, as well as coordinate the
 discharging of individual items from the respective inductor station 18
 into an assigned pocket 14 on the core conveyor 12. Each inductor station
 18a, 18b, 18c includes a gravity feed ramp 32a, 32b, 32c that transports
 charges of assorted items in sequence to a feeder tray 34a, 34b, 34c. An
 operator loads the charges of assorted items onto the respective gravity
 feed ramp 32a, 32b, 32c. Each charge contains items standing upright on
 edge and grouped together in series side-by-side (see for example FIG. 3).
 FIG. 2 shows staging areas or shelves 36a, 36b, 36c which are optional.
 Staging shelves 36a, 36b, 36c are useful for preparing one or more charges
 of assorted items prior to loading onto the gravity feed ramps 32a, 32b,
 32c.
 A feeding assembly 38a, 38b, 38c on each inductor station feeds assorted
 items in the respective feeder tray 34a, 34b, 34c to a loading mechanism
 40a, 40b, 40c. The loading mechanisms 40a, 40b, 40c load items from a
 discharge end 42a, 42b, 42c of the respective feeder tray 34a, 34b, 34c
 onto a takeaway conveyor 44a, 44b, 44c one by one in a singular fashion.
 The endmost item in the charge of assorted items on the respective feeder
 tray 34a, 34b, 34c is loaded onto the takeaway conveyor 44a, 44b, 44c such
 that the item stands on the takeaway conveyor upright on edge. The
 operation of the respective loading mechanisms 40a, 40b, 40c and takeaway
 conveyors 44a, 44b, 44c are coordinated to transfer items into an assigned
 pocket 14 on the core conveyor 12 as previously mentioned. Thus, while the
 charges of assorted items are loaded manually by workers in a facility in
 a typically inconsistent manner, the inductor stations 18a, 18b, 18c are
 designed to provide items in single file standing upright on edge to
 assigned pockets 14 on the core conveyor 12 in a synchronous manner.
 FIGS. 3 through 5 illustrate a first embodiment of one of the inductor
 stations 18 constructed in accordance with the invention. It should be
 recognized that each of the inductor stations 18a, 18b, 18c shown in FIG.
 2 for the sortation conveying system 10 are preferably substantially
 identical to one another.
 Referring in particular to FIGS. 3-5, a charge 47 of assorted items is
 shown to be held in place on the gravity feed conveyor 32 by a retractable
 queuing plate 48. The charge of items 47 contains an assortment of
 substantially rectangular items each standing upright on edge and grouped
 in series side-by-side. Although the invention is capable of handling
 rectangular items having consistent dimensions, it is designed especially
 to accommodate intermingled items having assorted substantially
 rectangular dimensions.
 The gravity feed conveyor 32 includes a plurality of horizontally mounted
 idler rollers 50. The ramp 32 is inclined such that an infeed end 52 which
 receives the charges 47 of assorted items is located higher than a
 discharge end 54 of the ramp 32. The discharge end 54 of the ramp 32 is
 located adjacent a feeder tray 34. As shown best in FIGS. 4 and 5, the
 ramp 32 includes three retractable queuing plates 48, 56 and 58. Each of
 the queuing plates is able to hold a charge 47 of assorted items on the
 ramp 32 when positioned in a non-retracted or extended position, and
 retracts below the conveying surface of the idler rollers 50 to allow the
 charge 47 to feed downward along the ramp and eventually onto the feeder
 tray 34. As discussed later in connection with FIG. 13, photoelectric
 sensors are used to monitor whether assorted items are being held by a
 respective queuing plate 48, 56, 58, and the operation of the queuing
 plates 48, 56, 58 is controlled in response to signals from the sensors to
 automatically feed sequences of charges 47 to the feeder tray 34. A manual
 switch 60 is provided for the first queuing plate 58 on the ramp 32. An
 operator of the inductor station 18 pushes the manual switch 60 when a
 charge 47 is fully loaded against the first queuing plate 58. After the
 manual switch 60 has been pushed, the control system is enabled to retract
 the first queuing plate 58 in accordance with the signals from the
 proximity sensors, as well as operation of downstream components of the
 inductor station 18.
 The gravity feed ramp 32 includes longitudinal guide rails 33 on either
 side of the rollers 50 for guiding the charges 47 of assorted items down
 the gravity feed ramp 32. The guide rails 33 on the side of the ramp 32
 closest to the discharge end 42 of the feeder tray 34 preferably terminate
 at a location prior to the location where the gravity feed ramp 32
 intersects the feeder tray 34, see FIG. 5. In this manner, the rail 33
 does not interfere with movement of assorted items 47 along the feeder
 tray 34. However, a guide wall extension member 45 (see FIGS. 3 and 4) is
 provided along the longitudinal ramp guide rail 33 located closest to the
 discharge end 42 of the feeder tray 34. The guide rail extension member 45
 is retractable. Its position is controlled by pneumatic cylinder 43. The
 retractable guide wall extension member 45 is shown in a retracted
 position in FIGS. 3 and 4 such that assorted items are able to be pushed
 along the feeder tray 34 towards the discharge end of the feeder tray 34
 without interference from the guide wall extension member 45. However, the
 pneumatic cylinder 43 extends the guide wall extension member 45 over the
 feeder tray 34 when a charge 47 is being loaded from the gravity feed ramp
 32 onto the feeder tray 34. The extended guide wall extension member 45
 prevents tipping of the endmost items in the charge 47 while the charge 47
 is being loaded onto the feeder tray. The feeder tray 34 preferably has a
 floor 62 that is inclined at the same angle as the gravity feed ramp 32.
 The feeder tray 34 also includes a backstop 64, FIG. 5, which facilitates
 alignment of the assorted items in the feeder tray 34. Preferably, the
 backstop includes rails 66 that provide an alignment plane for assorted
 items in the feeder tray 34. The backstop alignment plane should be
 substantially perpendicular to the floor 62 of the feeder tray 34.
 Preferably, the floor 62 and the backstop rails 66 are made of plastic
 materials having a relatively high level of lubricity in order to minimize
 frictional forces acting on assorted items being moved along the feeder
 tray 34.
 FIG. 3 illustrates the feeding assembly feeding a charge 47 of assorted
 items along the feeder tray 34 to the loading mechanism 40 located at the
 discharge end 42 of the feeder tray 34. In FIG. 3, the endmost item 47a in
 the charge on the feeder tray 34 is loaded onto a lifting lever 68 which
 constitutes part of the loading mechanism 40. A substantially vertical
 guide plate 70 is located adjacent the lifting lever 68 on the side
 opposite the feeder tray 34. The feeding assembly pushes the charge 47 of
 assorted items to press the endmost item 47a flush against the vertical
 guide plate 70.
 A vertical stripping conveyor belt 72 is located adjacent the vertical
 guide plate 70 on the side of the guide plate 70 opposite the lifting
 lever 68. The stripping conveyor has a plurality of cleats 74 which extend
 from the stripping conveyor beyond the vertical guide plate in the
 direction of the lifting lever 68. The stripping conveyor belt 72 is
 preferably an indexing motion conveyor which is computer controlled. When
 the lifting lever 68 lifts the endmost item 47a in the charge 47, the
 indexing motion stripping conveyor 72 moves at the appropriate time and
 cleats 74 on the stripping conveyor belt 72 push the endmost item 47a onto
 the takeaway conveyor 44.
 The feeding assembly preferably comprises at least two pushing mechanisms
 76, 78: namely, a main pushing mechanism 76 and a secondary pushing
 mechanism 78. The main pushing mechanism 76 includes a pushing hand 80
 attached to the body of the pushing mechanism 76. The hand 80 for the main
 pushing mechanism 76 includes openings 82 in which fingers on a hand 84
 for the secondary pushing mechanism 78 can reside when the main pushing
 mechanism 76 and the secondary pushing mechanism 78 are located at the
 same or nearly the same location along the feeder tray 34. The operation
 of the main pushing mechanism 76 and the secondary pushing mechanism 78
 are coordinated to facilitate substantially continuous feeding of assorted
 items to the loading mechanism 40 at the discharge end 42 of the feeder
 tray 34.
 As shown best in FIG. 3, the body of the main pushing mechanism 76 is
 mounted to a bearing block 88. An arm of a pneumatic cylinder 92 is
 connected to the body 76 of the primary pushing mechanism and moves the
 bearing block 88 linearly along a rail 90, and thus moves the hand 80 for
 the main pushing mechanism along the feeder tray 34. The linear motion of
 the main pushing mechanism 76 is indicated by arrow 94 in FIG. 3. The
 actuation of the pneumatic cylinder 92 is computer controlled.
 The hand 84 for the secondary pushing mechanism 78 is retractable as
 depicted by arrow 96 in FIG. 3. The arm of pneumatic cylinder 100 controls
 the vertical position of the body and hand 84 of the secondary pushing
 mechanism 78. The arm of the pneumatic cylinder 100 as well as guide rails
 97 are mounted to slide through bearing block 98 for the secondary pushing
 mechanism 78. The bearing block 98 is mounted to a rail 102 for linear
 horizontal motion as depicted by arrow 104 in FIG. 3. The arm of pneumatic
 cylinder 108 is connected to bearing block 98 for the secondary pushing
 mechanism and controls the horizontal position of the secondary pushing
 mechanism along the feeder tray 34. Note that the body of the retractable
 secondary pushing mechanism 78 is located below the floor 62 of the feeder
 tray 34, whereas the body 76 of the main pushing mechanism is preferably
 located above the floor 62 of the feeder tray 34. The floor 62 of the
 feeder tray 34 includes slots 106 to accommodate motion of the fingers 84
 of the secondary pushing mechanism 78 when the secondary pushing mechanism
 78 moves towards the discharge end 42 of the feeder tray 34.
 The operation of pneumatic cylinders 92, 100 and 108 is coordinated in
 order to continuously feed assorted items 47 along the floor 62 of the
 feeder tray 34 to the loading mechanism 40. FIGS. 6a-6e schematically
 represent coordinated operation of the main pushing mechanism 76 and the
 secondary pushing mechanism 78. In FIG. 6a, the main pushing mechanism is
 located in its home location such that the hand 80 for the main pushing
 mechanism 76 is ready to accept the next charge 47 of assorted items from
 the gravity feed ramp 32. FIG. 6a shows guide wall extension member 45
 being extended to guide the charge 47 as it is fed onto the feeder tray
 34. The pushing hand 84 for the secondary pushing mechanism 78 is
 retracted so that the pushing hand 84 is located below the floor 62 of the
 feeder tray 34. Next, the guide wall extension member 45 is retracted, and
 the pneumatic cylinder 92 begins to drive the main pushing mechanism 76
 along the feeder tray 32, thus pushing the charge 47 of assorted items
 towards the loading mechanism 40. FIG. 6b illustrates movement of the main
 pushing mechanism 76 in the direction of arrow 110. In FIG. 6b, several
 items have been loaded onto the takeaway conveyor from the charge 47 of
 assorted items. Note that the hand 80 for the main pushing mechanism has
 pushed the endmost item in the charge 47 against the guide rail 70 to
 approximately position the item on the lift for the loading mechanism 40.
 After the endmost item in the charge 47 is appropriately positioned on the
 lift for the loading mechanism 40, the pneumatic cylinder 92 for the main
 pushing mechanism 76 momentarily relieves pulling pressure on the
 mechanism 76. Relieving the pressure allows tension in the charge 47 to
 relax and reduces friction and normal forces on the endmost item in the
 charge 47 so that the loading mechanism 40 works more reliably. After the
 endmost item of the charge 47 has been loaded onto the takeaway conveyor,
 the cylinder 92 again reapplies pressure to move the main pushing
 mechanism 76 and push the charge 47 towards the loading mechanism 40. Note
 that FIG. 6b shows the hand 84 for the secondary pushing mechanism 78 in a
 retracted position in which the hand 84 is located below the floor 62 of
 the feeder tray 34. In FIGS. 6a and 6b, the secondary pushing mechanism 78
 is retracted and located in its home position.
 Referring now to FIG. 6c, the pneumatic cylinder 100 is actuated to extend
 the hand 84 for the secondary pushing mechanism above the floor 62 of the
 feeder tray as depicted by arrow 112. At this point in the process, the
 fingers on the hand 84 for the secondary pushing mechanism 78 typically
 nest within openings 82 in the hand 80 for the main pushing mechanism 76
 (See FIG. 7). After the secondary pushing mechanism 78 is raised, the
 secondary pushing mechanism 78 substitutes for the main pushing mechanism
 76 and continues feeding the charge 47 of assorted items to the loading
 mechanism 40 substantially in the same manner as discussed previously with
 respect to the main pushing mechanism 76. FIG. 6d shows the next stage in
 the process in which the secondary pushing mechanism 78 continues to feed
 assorted items in the charge 47 to the loading mechanism 40 as depicted by
 arrow 114, and the main pushing mechanism 76 returns to its home position
 as depicted by arrow 116. FIG. 6e shows the guide rail extension 45 being
 extended, and the feeder tray 34 accepting the next charge of assorted
 items 47. FIG. 6e also shows a situation in which the loading mechanism 40
 has exhausted the previous charge prior to the next charge being fed to
 the loading mechanism. The cylinder 100 for the secondary pushing
 mechanism 78 is actuated to retract the hand 84 for the secondary pushing
 mechanism 78, and then cylinder 108 is actuated to return the secondary
 pushing mechanism 78 to its home position. Although the situation
 illustrated in FIG. 6e can occur in cases in which subsequent charges 47
 are loaded onto the feeder tray in an untimely fashion, it is preferred
 that the feeding of items to the loading mechanism 40 be substantially
 continuous.
 The operation of the loading mechanism 40 is now described in connection
 with FIGS. 8-10. As previously mentioned, the loading mechanism 40
 includes a lever 68 that is pivotally mounted about pivot point 118. An
 actuator 120, preferably a pneumatic cylinder, is connected to the lever
 68 and moves the lever 68 between a lowered position, FIG. 10 and a raised
 position, FIG. 9. Referring in particular to FIG. 8, the pivotable lever
 68 has a top surface 122. The width of the top surface 122 is less than
 the width of assorted items 47 fed to the lift. In this manner, the lift
 lever 68 lifts only the endmost item 47a from the charge 47 of assorted
 items otherwise standing on the floor 62 of the feeder tray 34. The
 pivotable lifting lever 68 includes an inside surface 124 which moves in a
 plane parallel to the vertical guide plate 70 and is immediately adjacent
 to the vertical guide plate 70. Note that the vertical guide plate 70 has
 an upper portion 70a and a lower portion 70b, see FIG. 8. The endmost item
 47a in the charge 47 is kept an upright position by the upper 70a and
 lower 70b portions of the guide plate 70 as the item is loaded onto the
 lever 68, and also while the lever 68 lifts the endmost item 47a.
 The loading mechanism 40 also includes a holdback member 126 (see FIGS. 3,
 4, 9, 10). The holdback member 126 is preferably an extension of the
 lowest backstop bar 66. The holdback member 126 is located between the
 lifting lever 68 and the infeed for the takeaway conveyor belt 44. The
 holdback member defines a horizontal obstacle for items located in the
 feeder tray 34 immediately in front of the infeed to the takeaway conveyor
 belt 44 (see FIG. 10). The height of the horizontal obstacle should be no
 greater than a loading height for the takeaway conveyor belt 44. The front
 edges of the assorted items 47 in the feeder tray 34 are positioned lower
 than the loading height of the takeaway conveyor belt 44 and the holdback
 member 126 prevents these items from moving forward against the takeaway
 conveyor belt 44. This is particularly important in order to counteract
 frictional attraction forces between adjacent items when the endmost item
 47a is loaded onto the takeaway conveyor 44.
 When the lever 68 is in the lowered position (FIG. 10), the lifting lever
 68 is preferably flush with the floor 62 of the feeder tray 34. When the
 lifting lever 68 is lifted to the raised position (FIGS. 8 and 9), the
 endmost item 47a in the charge 47 is lifted such that the lower edge of
 the item 47a is raised to the loading height of the takeaway conveyor belt
 44 and above the holdback member 126. Cleats 74 on the stripping conveyor
 72 then push the item 47a onto the takeaway conveyor 44 as shown in FIG.
 9. Note that subsequent items in the charge 47 remain with their lower
 edge on the floor 62 of the feeder tray 34 when the loaded item 47a is
 lifted by the pivotable lifting lever 68.
 FIGS. 11-13 relate to a second embodiment of the invention in which the
 feeding assembly employs the use of a retractable stabilizing hand 128. In
 many ways, the embodiment shown in FIG. 11 is similar to the embodiment
 shown in FIG. 3 and similar reference numerals are used where appropriate.
 The stabilizing hand 128 includes fingers 130 which pass through the same
 slots 106 as the fingers on the hands 84 for the secondary pushing
 mechanism. The stabilizing hand is mounted for vertical sliding movement
 to a bearing block 132. The bearing block 132 is mounted to the same rail
 102 as the bearing block 98 for the secondary pushing mechanism 102. An
 arm for a pneumatic cylinder 134 is mounted to the mounting block 132 and
 connected to the stabilizing hand 128. The pneumatic cylinder 134 controls
 vertical movement for the retraction and vertical extension of the
 stabilizing hand 128. The pneumatic cylinder 134 which raises and lowers
 the stabilizing hand 128 is separate from the pneumatic cylinder 100 which
 raises and lowers the hand 84 for the secondary pushing mechanism 76,
 however, it is preferred that theses cylinders 100, 134 be controlled in
 unison so that the hands 128, 84 retract and extend vertically in unison.
 The operation of the feeding assembly shown in FIG. 11 having a stabilizing
 hand 128 is now discussed in connection with FIGS. 12a-12g. FIGS. 12a-12c
 illustrate a start-up mode. In FIG. 12a, the hand 84 for the secondary
 pushing mechanism 78 and the fingers 130 for the stabilizing hand 128 are
 extended vertically and present above the floor 62 of the feeder tray 34
 in the home position for the stabilizing hand 128. Also, the hand 80 for
 the main pushing mechanism 76 is located in its home position, and the
 feeding assembly is ready to accept the first charge 47 of items between
 the hand 80 for the main pushing mechanism 76 and the fingers 84, 130 for
 the stabilizing hand 128 and the secondary pushing mechanism 78. Once the
 charge 47 is loaded onto the feeder tray, the hand 80 for the main pushing
 mechanism 76 pushes the charge 47 towards the loading mechanism 40 as
 shown in FIG. 12b. The hand 84 for the secondary pushing mechanism and the
 fingers 130 for the stabilizing hand 128 remain essentially tight against
 the leading edge of the charge 47 of items in order to prevent the endmost
 item from tipping. Note that the stabilizing hand 128 is moved along the
 feeder tray towards the loading mechanism as the endmost item in the
 charge 47 pushes against the fingers 130 for the stabilizing hand 128.
 When the fingers 84, 130 for the secondary pushing mechanism 78 and the
 stabilizing hand 128 reach the loading mechanism 40, the secondary pushing
 mechanism 78 and the stabilizing hand 128 retract such that the fingers
 84, 130 will be located underneath the floor 62 of the feeder tray 34.
 FIG. 12c shows the fingers 84, 130 being retracted, and returning
 underneath the floor 62 of the feeder tray to the home position for the
 secondary pushing mechanism 78. Note that the stabilizing hand 128 is
 pushed along rail 102 by the secondary pushing mechanism 78 as it returns
 to its home position.
 After the secondary pushing mechanism 78 and the stabilizing hand 128
 return to the home position for the secondary pushing mechanism 78, the
 fingers 84, 130 for the secondary pushing mechanism 78 and the stabilizing
 hand 128 are extended vertically upward as depicted in FIG. 12d by arrow
 136. The fingers 84, 130 are not raised until the hand 80 for the primary
 pushing mechanism 76 passes beyond the home location for the secondary
 pushing mechanism 78. After the fingers 84, 130 are extended, the
 secondary pushing mechanism 78 moves towards the loading mechanism 40, and
 substitutes for the main pushing mechanism 76. FIG. 12e shows the process
 after the hand 84 for the secondary pushing mechanism 78 has taken over
 the feeding of charge 47 to the loading mechanism 40. The main pushing
 mechanism 76 has returned to its home position along the feeder tray, and
 the hand 80 for the main pushing mechanism 76 and the fingers 130 for the
 stabilizing hand 128 are ready to accept the next charge 47b of assorted
 items. After the next charge of assorted items 47b has been loaded onto
 the feeder tray, the hand 80 for the main pushing mechanism 76 pushes the
 second charge 47b and the stabilizing hand 130, 128 towards the loading
 mechanism 40. FIG. 12f shows a point in the process in which the main
 pushing mechanism 76 has pushed the second a charge 47b close to the
 remaining portion of the first charge 47b, but the fingers 84, 130 for the
 secondary pushing mechanism 78 and the stabilizing hand 128 still remain
 vertically extended above the floor 62 of the feeder tray 34. FIG. 12g
 shows the next step in the process in which the fingers 84, 130 for the
 secondary pushing mechanism 78 and the stabilizing hand 128 retract
 underneath the floor 62 of the feeder tray as depicted by arrow 138. As
 further shown in FIG. 12g, the secondary pushing mechanism 78 and the
 stabilizing hand 128 then return again to the home position for the
 secondary pushing mechanism 78. The process continues as shown and
 described in connection with FIGS. 12d, 12e, 12f and 12g in sequence to
 continue feeding assorted items to the loading mechanism 40.
 As mentioned, the inductor station 18 is programmably controlled using a
 controller 28 which communicates with the main controller 30 for the
 system 10. In general, the station controller 28 controls motors and/or
 pneumatic cylinders or other actuators to control the operation of moving
 parts in the inductor station 28. The controller 28 is programmed to
 provide an item to the core conveyor at the appropriate time in response
 to information it receives from the main controller 30, as well as various
 sensors throughout the system.
 The controller 28 controls actuators 140, 142, and 144 which position the
 retractable queuing plates 48, 56, 58 on the gravity feed conveyor in part
 in response to signals from photoelectric sensors 146, 148, 150 and manual
 switch 60. Sensor 150 senses whether a charge of items is being held in
 place on the ramp 32 by retractable queuing plate 58. Sensor 148 senses
 whether the second retractable queuing plate 56 is holding items in place
 on the ramp 32. Sensor 146 senses whether the third retractable queuing is
 holding items in place on the ramp 32. The controller 28 operates
 pneumatic cylinders 140, 142, 144 to retract or extend the respective
 queuing plates 48, 56, 58 in order to coordinate the queuing of charges of
 items from the infeed of the gravity feed conveyor 32 to the feeder tray
 34. For example, if sensor 146 senses that the third queuing plate 48 is
 empty, and sensor 148 senses that the second queuing plate 56 is holding a
 charge of assorted items, the programmable controller 28 will send a
 control signal instructing pneumatic cylinder 142 to retract the queuing
 plate 56 and allow the charge to roll down the gravity feed conveyor 32 to
 the third queuing plate 48. When sensor 152 senses that the main pushing
 mechanism 76 has returned to its home position and sensors 154 and 156
 sense that the stabilizing hand 128 has returned to its home position with
 the fingers 130 extended above the floor 62 of the feeder tray 34, the
 electronic controller 28 instructs pneumatic cylinder 43 to extend the
 longitudinal guide wall extension member 45 and instructs pneumatic
 cylinder 140 to retract the third queuing plate 48, thus enabling the
 charge held by the third queuing plate 48 to load onto the feeder tray
 between the hand 80 for the main pushing mechanism 76 and the fingers 130
 for the stabilizing hand 128. As a worker loads items onto the infeed end
 of the gravity feed conveyor 32, the items are held in place by the first
 queuing plate 58. When the worker has filled the first queuing plate 58
 with a complete charge, the worker hits manual switch 60. Once the manual
 switch 60 is activated, charges of assorted items are allowed to descend
 in a coordinated manner onto subsequent queuing plates 56, 48 and into the
 feeder tray 34 as long as there is space available for the charge at the
 next location.
 FIG. 13 also shows various sensors which are useful for coordinating the
 movement of the feeding assembly components. For example, sensor 158
 senses when the main pushing mechanism 76 has reached its end of stroke or
 stop location. Likewise, sensor 160 senses when the secondary pushing
 mechanism 78 has reached its end of stroke or the secondary stop location.
 Sensor 162 senses when the secondary pushing mechanism 78 has returned to
 its home location. Sensor 164, which has components mounted on the
 stabilizing hand 128 and the secondary pushing mechanism 78, senses when
 the stabilizing hand 128 moves or merges into close proximity with the
 secondary pushing mechanism 78. Sensor 164 allows the programmable
 controller 28 to instruct pneumatic cylinder 92 which drives the main
 pushing mechanism 76 to slow down as the stabilizing hand 128 approaches
 the secondary pushing mechanism 78. This is important for avoiding
 potentially disruptive collisions between the stabilizing hand 128 and the
 secondary pushing mechanism 78, which could otherwise occur, for example,
 when a subsequent charge 47b of items is moved along the feeder tray 34
 towards the remaining portion of a charge 47 being loaded onto the loading
 mechanism 40 by the secondary pushing mechanism 78 as depicted in FIGS.
 12e and 12f.
 The programmable controller 28 provides instructions for operating
 pneumatic cylinders 100, 108, 92, and 134 to coordinate the movement of
 the main pushing mechanism 76, the secondary pushing mechanism 78, and the
 stabilizing hand 128, preferably as described in connection with FIGS.
 12a-12g.
 With respect to the loading mechanism 40, the programmable controller 28
 instructs a motor 73 to index the stripping conveyor belt 72 forward at
 the appropriate time to load an item from the lift 68 onto the takeaway
 conveyor belt and into an assigned pocket on the core conveyor belt.
 Sensor 166 senses whether cleats 74 on the stripping conveyor are in the
 ready position prior to indexing the stripping conveyor 72. Sensor 168
 senses whether an item is in place on the lifting lever 68 for the loading
 mechanism 40. Sensor 170 senses whether the lifting lever 68 is in the
 lowered position, whereas sensor 172 senses whether the lifting lever 68
 is in the raised position. The programmable controller 28 instructs
 pneumatic cylinders 92 or 108 to push the next item in the charge onto the
 lifting lever 68, when the sensor 170 indicates that the lever 68 is in
 the lowered position and the sensor 166 senses that the cleats 74 are
 ready for the next item. Once the sensor 168 senses that an item has been
 loaded on the lifting lever 68, the programmable controller 28 instructs
 cylinders 92 or 108 to relieve the pressure against the charge, and then
 after a slight time delay instructs pneumatic cylinder 120 to raise the
 lifting lever 68. Once the sensor 172 senses that the lifting lever 68 has
 been moved into the raised position, the programmable controller instructs
 the motor 73 to index forward, and the cleats 74 on the stripping conveyor
 72 move the item on the lift 68 to the takeaway conveyor 44.
 It should be apparent to those skilled in the art that the invention
 provides particularly reliable and efficient means for loading assorted
 items onto a sortation conveying system. While the invention has been
 described herein in connection with two preferred embodiments, the
 invention should not be necessarily limited to the details described
 herein. In determining the scope of the invention, reference shall be made
 to the following claims which particularly point out and distinctly claim
 the invention.