WO2002058855A1 - Flats bundle collator - Google Patents

Abstract

A method and an apparatus for collating a plurality of groups of mail items, such as flats mail, each group being pre-sequenced according to prioritized delivery addresses, into a final sequenced set of the mail items from the groups, utilizing the prioritized delivery addresses is described. Each bundle of mail items is formed into a single input stream of the individual mail items. The mail items are transported along a conveyor system from the input stream to a staging station. The mail items are sorted at the staging station (16) into a plurality of subsets of mail items re-sequenced as an intermediate step to achieving the final sequenced sets. The mail items are then collated and merged into a single output stream from the respective subsets of mail items in the final sequenced set. Portions of the output stream from the staging station are collected in batches which maintain the sequence consistent with the prioritized delivery order sequence of the mail for a given carrier route.

Description

FLATS BUNDLE COLLATOR BACKGROUND OF THE INVENTION

The present invention relates to a method and system for collating a plurality of groups of mail items, each group being pre-sequenced according to prioritized delivery addresses, into a final sequenced set of the mail items from the groups, utilizing the prioritized delivery addresses. More specifically, the present invention relates to a process and system that merges several sequenced bundles of flats mail into one sequenced set of mail for delivery by a mail carrier according to a prioritized delivery address sequence, commonly known as a delivery order sequence (DOS) or walk sequence (WS). Flats mail, routinely delivered by mail carriers, includes magazines, newspapers, padded envelopes, single sheet fliers, compact disks in boxes, poly-wrapped items, and miscellaneous other types of mail items. These flats range in size from 4" to 15.75" in length; 4" to 12" in width; .007" to 1.25" in thickness; and 1/ 100 lb. to 6 lb. in weight. Delivery of these flats in dehveiy order sequence, or walk sequence, requires special sorting in a post office facility such as a delivery unit (DU). In general, DU operations are consistent from one office to another within the U.S. postal system. However, different route types (rural, city, park and loop) may process flats in slightly different manners within the same facility. The flats to be processed arrive from a variety of sources in a number of different ways. Mailers may drop ship saturation mailings (mass mailings) two to seven days prior to the dehveiy per an agreement with the local Postmaster. Other mailings can arrive on pallets (periodicals, national advertisements or catalogs) after passing through the postal network of facilities as cross-dock material. Other material may be broken down from pallets at an upstream facility if a pallet was shipped as three-digit material. Other flats may have been processed on flats sorting equipment known in the art, and are then processed according to carrier route. Still more material can pass through bulk mail centers as bundles before arriving at the dehveiy unit (DU).

Currently, with the exception of saturation (mass) mailings, the majority of this material is not in carrier walk sequence (WS) or dehveiy order sequence (DOS). Bundles may be in enhanced carrier line-of-travel (ECLOT) or in carrier route, but not walk sequence. Less than 1% of the mailings in the field have an eleven digit (ZIP+4+2) dehveiy point barcode representative of the delivery point sequence (DPS). Many saturation mailings have no barcode at all and are addressed to "Postal Customer" with no address. Other mailings have 5 or 9 digit ZIP codes and "marriage" mailings consisting of two materials; an address card or leaflet, and a second mailing with no address label intended to be left at the same address as the card. However, in order to provide for flats bundle collating in an automated fashion, it is possible to provide all of the flats mail with eleven digit coding inclusive of dehveiy point sequence information.

In current operations, the source and configuration of the flats being processed has little or no impact on how they are processed in the DU in preparation for dehveiy. In general, the following preparation of flats for dehveiy occurs (there are other activities such as held mail or registered mail that are performed that are not noted here to simplify the explanation):

1. In preparation for casing operations, mail personnel sort through flats, bundles and mailings from all sources and separate them by carrier early in the morning (beginning around 4:00 AM). This is done in staging areas using tubs, hampers or large cases. 2. Flats are delivered to the carrier casing area and set in a staging area.

3. Carriers case the flats, along with other mail types (this activity is performed in the morning usually from 6:00 AM or 7:00 AM to sometime between 9:00 AM and 11 :00 AM, depending on route size and the amount of mail). The current postal standard for casing unsequenced flats is 8 per minute. On some routes or in some DU's, carriers do not case saturation mailings and treat them as an additional bundle during dehveiy. Other carriers may split saturation mailings and deliver portions of them on consecutive days to load level the amount of mail to be delivered. 5 4. Cased mail is removed and placed in trays to be delivered.

5. The carrier leaves the facility and delivers the mail.

6. In some DU's, carriers case mail upon return to the facility in the afternoon in preparation for the next day.

For some portion of the morning, activities 1 and 2 above, can overlap 0 with the casing operation and may extend until after the carrier has left the facility leaving mail to be cased either later that day or the next morning. All cased mail is removed in carrier walk sequence, and carriers carefully case flats so that all address labels are on the same edge of the mail (even if this means that the label is upside down relative to other addresses in the 5 bundle) to ensure easy reading while doing deliveries. Depending on the route type and/or the carrier's preference, marriage mailings may case either the address card or both the address card and the mailing cased (some prefer to case only the card and pull the mailing at each house that has a card in the dehveiy). o These activities can take up to 50% of a carrier's in-office time, and therefore, limit the amount of deliveries can perform in the remainder of the day. This is one of the limiting factors in the number of stops that a carrier route can contain (obviously the amount of mail, the distance between the stops, the demographics of the route area, and other factors are involved as 5 well). It stands to reason, that by making the in-office activities more efficient, i.e. providing delivery point sequence (DPS) flats, then carriers can be expected to spend less time in the facility and more time on the route. This added time can allow for additional stops on routes and the possible consolidation of some routes into others. This scenario is analogous to the o introduction of DPS letter mail through the use of automation to a great degree. However, the types of mail (flats) and the different ways that the mail arrives at a facility does make the task of creating a single bundle of DPS flats a challenging proposition. The automation of sorting and- collating of flats by their physical nature is a very difficult task due to the large variation in sizes and types of the flats material.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to develop a system and process for collating flats mail using a small, flexible, inexpensive machine that is easy to operate, reliable, and requires easy and infrequent maintenance.

It is the further object of the present invention to develop a process and system which utilizes standard sort schemes for carrier walk sequences utilized for sorting conventional mail other than flats.

It is another object of the present invention to provide an apparatus for sorting flats having a small footprint in order to take up a minimum amount of space in the sorting facility.

It is yet another object of the present invention to provide an apparatus for sorting flats, which is modular in construction for flexible sizing through the use of additional modular components, including staging towers.

It is still another object of the present invention to provide an apparatus for sorting flats wherein only a single operator is required.

It is another object of the present invention to provide an apparatus for sorting flats having low maintenance and operating costs. The objects of the present invention are fulfilled by providing a method and apparatus for collating a plurality of groups of mail items, such as flats, each group being pre-sequenced according to prioritized delivery addresses (dehveiy order sequence DOS), into a final sequenced set of the mail items from the groups, utilizing the prioritized dehveiy addresses (DOS), comprising the steps of: separating each bundle of mail seriatim into a single input stream of the individual mail items; transporting the mail items from the input stream to a staging station; sorting the mail items at the staging station into a plurality of subsets of mail items re-sequenced as an intermediate step to achieving said filial sequence sets; merging the mail items into a single output stream from the respective subsets of mail items in said final sequenced set; and collecting portions of the output stream of the mail items consistent with the sequence of the final sequenced set to form batches of mail for orderly dehveiy to the prioritized dehveiy addresses (DOS) according to dehveiy criteria reflected in said final sequenced set.

In a preferred embodiment, the staging station includes a plurality of juxtaposed vertical stacks in staging towers, each stack including a plurality of vertically stacked and spaced shelves for supporting the flats mail thereon. The flats are stored in the stacks of the respective staging towers in a last-in- first-out sequence (LIFO).

Each flat has a machine-readable number thereon representative of the dehveiy order sequence (DOS) with lower numbers representing higher dehveiy priorities. A reader is provided for generating control signals for routing the flats to predetermined ones of the vertical stacks or towers at the staging station, the flats in each stack being positioned in ascending order number from the bottom to the top of the stack.

The unloading of each stack to form the output stream of mail items in the final sequenced set is fed out in reverse order, mainly from the lower numbers at the bottom of the respective stacks to the higher numbers in the stacks, until all items are merged into the final output stream.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: Fig. 1 is a perspective view of a modular flats bundle collator

(FBC) system according to the preferred embodiment of the present invention;

Figs. 2A and 2B are perspective views illustrative of the flats diverter module of the system of Fig. 1 ; Fig. 2C is an exploded view of the embodiment of a combined orienter and reader module for use in the system of Fig. 1;

Fig. 2D is a perspective view of the orienter/ reader module of Fig. 2 depicting the module assembled;

Fig. 3 is a perspective view of one of the staging tower modules of Fig. 1 illustrating details of the elevator mechanism thereof;

Fig. 4 is a perspective view of a portion of the transport conveyor of the flats bundle collator system illustrating how the flats are edge- justified as they traverse the surface of the conveyor within the staging towers; Fig. 5 is an alternative embodiment of conveyor roller structures of a transport conveyor suitable for use in the system of the present invention;

Fig. 6 is a top perspective view of the interleaved shelf and conveyor structures of the present invention in the region of the staging towers; Fig. 7 is a perspective view illustrating a detail of the shelves within the staging towers and their operative association with the timing belts of the elevator mechanisms of the towers;

Fig. 8 is a side elevational view illustrating the shelf transfer from one belt to another of the elevator mechanism;

Fig. 9 is a side elevational view showing the transfer of shelves between the belts of the elevator mechanism in slightly more detail than illustrated in Fig. 8;

Figs. 10A and 10B are perspective views illustrating two options of the present invention for storing mail in standard United States Postal Service mail tubs;

Fig. 11 is a perspective view of a dual containerizer module of the present invention and a reject tub;

Fig. 12 is a diagrammatic end view of a preferred method of edge justifying flats mail in order to achieve a uniform stack profile;

Fig. 13 is a block diagram of the hardware architecture for controlling the flats bundle coUator system of the present invention;

Fig. 14 is a block diagram of the software architecture for controlling the hardware of Fig. 13; Figs. 15A and 15B are illustrative of an operational block diagram of the method performed by the flats bundle collator system of the present invention;

Fig. 16 is a flowchart of the collation logic software of the flats bundle collator system of the present invention; and Figs. 17, 18A, 18B and 19A to 19L are diagrammatic illustrations of the flow of the pre-sequenced bundles of flats through the flats bundle collator system of the present invention;

Figs. 20 through 23 are illustrative of flats position and jam detection control parameters of the flats bundle coUator system of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawing figures, Fig. 1 depicts the overaU flats bundle coUator system of the present invention. The system includes the following components: a feeder assembly 10; a combined orienter/ reader assembly including a transport conveyor TC, a flats orienter module 12, a barcode reader module 14; a staging tower assembly 16 including multiple staging towers 16-1, ..., 16-n; and a containerizer module 18 including two containerizer assemblies 18-1 and 18-2. Bundles of mail in the United States Postal System mεάl tubs T are loaded onto the feeder assembly 10 by an operator O. The mail is first oriented to have the mailing label up by the orienter module 12. The address is then read by the barcode reader module 14. AU of the mailings F, except for the last, are staged in the staging tower assembly 16. Mail is removed from the multiple staging towers as the last mailing is fed from the feeder 10 in such a way as to make the mail stream in a desired final sequence. The mail is conveyed out of the staging tower assembly 16 to the containerizer module 18, where it is stacked in selected ones of United States Postal Service (USPS) tubs, not shown. Multiple pre- sequenced mailings can be fed into the machine. Each mailing can consist of several bundles of mail, each bundle containing several pieces. Each mailing is in dehveiy point sequence (DPS) or walk sequence (WS).

The operator O places aU but the last mailing in the feeder 10 with the lower number stop in the first position. The feeder 10 then removes one piece of flats maU F at a time from the stack and injects it into the flats orienter module 12. The feeder 10 wiU feed all of the maU in this manner until it reaches the last mailing. The last mailing is loaded with the lowest number stop in the last position.

If there is not a saturation mailing (a mass mailing) to be included in the sorting process, the operator notifies the system that loading is complete by pressing a button on the system control panel to be described hereinafter. However, if there is a saturation mailing, the operator notifies the system and begins loading the saturation mailing into the feeder 10. The system compares the contents of the staging tower assembly 16 to the carrier's walk sequence and calculates the output sequence to coUate the system contents into the sequence. If there is not a saturation mailing, the system calculates the output sequence directly from the tower contents. If a saturation mailing is included, the system calculates the output sequence from the towers 16-1, ..., 16-n and includes the feeder 10 saturation output in the coUation calculation.

The tower assembly 16 outputs the flats F, and the feeder 10 inputs saturation flats if they are present, such that they are transported into the maU tubs in the containerizer module 18. The operator O then removes the tubs and prepares to input the next carrier route bundles into the system. A more complete description of operation foUows in the description of Fig. 15.

The flats bundle collator according to the preferred embodiment of the subject invention occupies about 75 square feet of floor space with a ten tower configuration. The system weighs about 8000 pounds, and exerts floor loading not to exceed 42 psi. The coUator requires 3-phase electric power for operation.

The feeder module 10, for use with the system of the present invention, is a commercially avaUable component manufactured by Alcatel, known in the industry as the "Alcatel TOP Feeder". This feeder is highly rehable and easy to maintain. The feeder has a throughput of 3 flats per second; a jam rate of 1/2500 flats; a jam recovery in 5 seconds; accepts aU USPS flats mail sizes; feeds on demand with a 20 ms response time; and is well accepted in the user community.

As noted above, the flats orienter module 12 receives the output of the feeder module 10. Its operation is illustrated in Figs. 2A and 2B.

Referring now to Figs. 2A and 2B, as flats F exit the feeder module 10, the orienter module 12 places them label up on the transport conveyor TC using one of two tillable conveyor sections 12A and 12-B. Flats F to be staged are processed on one path as Ulustrated in Fig. 2A and saturation mailings are processed on the other path Ulustrated in Fig. 2B. The flats orienter module 12 indexes conveyor section 12A via a traversing carriage which moves in the direction of the double arrow in Figs. 2A and 2B to move the section 12A between the respective left-hand and right-hand positions Ulustrated in these figures. The carriage remains in a "home" position for all mail to be staged in the towers, as illustrated in Fig. 2A and indexes to the position shown in 2B only f the operator notifies the system that a saturation mailing is about to be fed. Where ten towers comprise the towers 16-1, ..., 16-n, saturation mailings (mass mailings) must be fed in reverse order relative to mailings staged in the towers. MaU F enters the towers from the first stop to last, and because the towers are Last In First Out (LIFO), the maU F leaves the towers, last stop to first, during the coUation process. To process saturation mailings directly from the feeder 10 the saturation mailing must be fed last stop to first. This is accomphshed by placing the bundles into the feeder 10 facing the opposite direction of the staged maU. The orienter module 12 then reorients the flats for reading by the reader 14 as they exit the feeder 10. That is, all of the maU flats F but the last mailing leave the feeder 10 with the bound side of the flat (assuming there is a bound side) and the address label facing right. The orienter 12 tips the mail over to the left, so that maU leaves the orienter with the bound side to the right and the label side up. The maU in the last mailing leaves the feeder with the bound edge down, and the label facing the left side. The orienter 12 tips this maU over to the right, so that the maU leaves the orienter with the bound side to the left and the label facing up. The mail leaves the flat orienter section 12 and then enters the barcode reader module section 14. The barcode reader module 14 is typicaUy a reader, such as the AccuSort Model No. AVI 200. This type of barcode reader is a high quality off-the-shelf reader, which has proven to be very rehable in service to the USPS. In this reader section, a barcode including the destination point sequence (DPS), carrier walk sequence printed on the flats F is read by the reader 14 and the address is sent to the main computer controller to be subsequently described. The location that is assigned to the flat wiU be used later to determine the output order of the flats F with, the lowest number on the top of the output stack.. The flats maU then leaves the barcode reader section 14 and enters the staging tower assembly 16. Each piece of mail F is inducted into the staging tower 16 that has the closest, lower number flat. If there is no tower that fits this requirement, the flat is inducted into the first empty tower. When all but the last mailing has been staged in one or more towers of the tower assembly 16, the last mailing is loaded in the feeder 10 as described hereinbefore. The mail F is processed normally until it reaches the staging tower assembly 16. When the first piece of mail arrives at the staging towers 16-1,..., 16-n, a coUation algorithm stored in the control system operates the unloading of the staging towers to form the final maU stream.

The mail is fed from the barcode reader module 14 and/or the staging tower assembly 16 to achieve a final sequenced set of flats with the highest number stop first. The maU is sequenced, and the maU uniformly spaced. When the maU leaves the staging tower assembly 16, it is fed into the containerizer assemblies 18-1 and 18-2 of containerizer module 18. The containerizers 18-1 and 18-2 stack maU in the sequence in which it was received, and maintains that sequence. Two containerizers 18-1 and 18-2 are preferably utilized so that when the operator is emptying one, the machine can continue to fiU the other. Referring now to Figs. 2C and 2D, the flats items are fed between the feeder 10 and the staging tower assembly 16 through the orienter module 12 and the reader module 14 via the transport conveyor TC. The detaUs of the combined orienter/ reader assembly is Ulustrated in the exploded view of Fig. 2C. The assembly includes an open frame structure F having four juxtaposed sections for receiving the orienter/ diverter module 12, the barcode reader module 14, a power distribution module 11 and system input/ output electronics assembly 13. These components are enclosed within a top panel TP and two side panels SP in the upper two sections of the frame structure. Side panels SP also include one or more observation windows OW therein so that the flats items can be observed as they pass through the modules 12 and 14 from the feeder 10 to the staging tower assembly 16. Observation windows, not shown, can also be provided in the sections of the staging towers 16-1, ..., 16-n.

Fig. 2D depicts the orienter/ reader modules 12 and 14 in an assembled condition. It can be seen that the path of flats items fed from feeder 10 to the staging tower assembly 16 via the orienter/ reader modules 12 and 14 passes the items along a horizontal path via the conveyor TC at the output side of the module into the staging tower assembly 16.

Any number of staging towers 16-1, ..., 16-n may be utilized and any number of containerizers 18-1, ..., 18-n without departing from the spirit and scope of the present invention. In fact, an advantage of the system of the present invention is its modularity, which facilitates the addition or deletion of staging towers and containerizers as needed to satisfy the footprint requirement of the space in which it is to be utilized. DetaUs of one of the staging towers 16-1 is shown in Fig. 3. Staging tower 16-1 includes a section of a roUer conveyor TC, a shelving assembly S, a shelf drive system including a motor EM, a chain and sprocket drive assembly 24, and drive shafts 26 coupled to the elevator mechanism, timing belts 20A, 20B, 20C. Each tower also includes a housing H formed from the frame and body panels.

The conveyor drive systems are designed to be "daisy chained" together aUowing the system to function with a single drive motor and providing easy expansion by simply adding more towers 16-m to the drive line through the use of universal joint couplings. The shelf drive system including motor EM, chain and sprockets assembly 24, and drive shafts 26 is located in a bottom section 16M of the tower for easy access. Each tower has an access door, not shown, that fuUy exposes the interior of the tower when open to provide easy access by an operator.

. . The tower roUer conveyors TC transport flats mail F through the tower assembly 16. The shelves S include outwardly projecting fingers 17 which are designed to interleave with and pass through a plurality of cantilever mounted roUers 28 of the conveyor TC as illustrated in Fig. 6, allowing the shelves S to lift flats off the rollers 28 of the conveyor TC. This will place the flats F onto or off of the roUers as the shelves S are indexed down or up, respectively. The roUers 28 of the conveyor TC-16 are skewed to the direction of travel by 2 degrees, as Ulustrated in Fig. 4 to facilitate edge justification of the flats F against a C-shaped channel 30 for rehable mail orientation. An alternative configuration for the interleaved numbers 17 and 28 is shown in Fig. 5 where the finger members 17A and roUer members 28A include transversely oriented projections P.

Tower shelves S are supported by a set of guides 31 as shown, for example, in Fig. 7 which engage slotted arms 29. Guides 31 maintain orientation and the belts determine the vertical position of the shelves S. Further as shown in Fig. 3, each staging tower, such as tower 16-1, has three zones 16A, 16B, 16C through which the shelves S move. 16A designates the shelfs storage zone, 16B the maU stream or transfer zone, and 16C the maU staging zone. Shelf position is determined by the operation of the respective endless timing belts 20A, 20B, 20B in the respective zones. Each shelf S is driven by a tooth or lug protruding from the endless timing belts in a manner Ulustrated in more detaU in connection with Figs. 7 to 9.

The timing belts 20A, 20B, 20C coUectively constitute an elevator mechanism for raising and lowering the shelves S and flats F thereon within each tower of the tower assembly 16. Each timing belt comprises an endless belt with protruding lugs L thereon spaced in predeteπnined pitches which differ between the respective vertical zones between the tower. These endless belts are wound around puUeys 22. Pulleys 22 are driven by the drive mechanism in zone 16. As depicted in Fig. 3A, the drive mechanism includes an electric motor EM coupled to drive shafts 26 via a chain and sprocket drive assembly 24. The respective endless belts of the timing belts are wound around the drive shafts 26 and are selectively driven in response to rotation of those shafts, which are under control of the central computer of the system to be described further hereinafter.

In the transition zones between the respective timing belts, the shelves S are moved up and down the support guides 31 and are transferred from one belt to another. The shelves S are engaged by the lugs L on the respective timing belts to effect movement and transfer of the shelves from one belt to another. When a shelf S comes to the top of a zone, its supporting belt curves around a puUey 22. As the shelf S rises, its support tooth or lug L begins to disengage from the shelf S. There is a large window of time when the support tooth or lug is still supporting the shelf, but the tooth or lug above the shelf no longer restricts the shelf from traveling up. In this window, a tooth from the belt in the next zone rises to lift the shelf S from the first zone to the next within the tower 16. This transition from one zone to another is depicted in Figs. 8 and 9. Referring to Fig. 9, timing belt 20A in the shelf storage zone, is a low- speed timing belt with a narrow pitch to accommodate a plurality of shelves S in close, juxtaposed, stacked positions. The timing belt 20B, in the transfer zone in the maU stream region of the towers 16, is a high-speed timing belt with a coarse or wide pitch between the lugs L. The pitch of the timing belt 20B is chosen to be wide enough to accommodate the maximum thickness of a piece of flat mail moving along the conveyor.

The upper timing belt 20C is not shown in Fig. 9 for clarity, but it preferably includes a low-speed timing belt with a pitch wide enough to accommodate both the shelves S and flats maU F disposed thereon. As the staging towers are unloaded by the lowering of the shelves in the staging or storage zone 16C by selective operation of the timing belts under control of the central computer, a stream of flats mail arranged in dehveiy point sequence emerges from the staging towers and approaches the containerizers 18, which maintain the sequence of the stack.

The flats may be stacked in maU tubs 40, either as Ulustrated in Fig. 10A with the edges facing up, or in Fig. 10B with the edges extending horizontaUy and vertically stacked. Fig. 10A depicts the flats maU being stacked on edge in a USPS mail tub 40. This method is desirable because it is a preferred arrangement for letter carriers, since the maU standing on edge in the tub is similar to the arrangement of file folders in a filing cabinet and lets the carrier flip through the mail easUy. OptionaUy, the containerizer stacking arrangement illustrated in 10B can be used. This type of output gives a tub of maU that looks simUar to the tubs produced by popular flats sortation machines for other types of maU.

As the flats maU F leaves the staging tower section 16 of the flats bundle coUator, it enters the containerizer section 18 as shown in Fig. 11. Flats F are diverted into either of two output tubs 40-1 or 40-2. This diversion is achieved by movement of the pop-up conveyor sections 42-1 and 42-2 up or down in response to activation of fluid motors 44-1 or 44-2. This up or down movement of the conveyor section 42-1 or 42-2 permits the flats F to shde down one of the respective angular shoots 46-1 or 46-2, which communicate with the open sides of the maU tubs 40-1, 40-2. Each maU tub 40-1 and 40-2 includes an angular guide flap 40A-1 and 40A-2 in order to capture and guide the flats entering the tub for assembly into a stack. The shoots 46-1 and 46-2 constitute acceleration ramps, which are shaped to justify the flat to one side of the ramp. There flats F are accelerated to the end of the ramp where they enter either the tub 40-1 or tub 40-2, and slip onto the maU stack being formed therein as they are guided by the flaps 40A-1 and 40A-2. The relative height of the stack at the end of the acceleration ramp 46-1, 46-2 is controUed by sensing the stack height and indexing the tubs 40-1, 40-2 downward as the stack height grows. This indexing of the tubs 40-1 and 40-2 is affected by an elevator mechanism including motors Ml, M2 and a plurality of belts 48-1, 50-1 driven by the motors Ml, M2. The tubs 40-1, 40-2 are supported on the belts 48-1, 48-2, 50-1 and 50-2 at 52 by appropriate teeth or lugs protruding from the belt. A third tub 40-3 is provided at the end of conveyor section 42-2 for system rejects, which is selectively loaded by operation of the pop-up conveyor sections 42-1 and 42-2 described herein before. Edge justification of the flats within the tubs is preferably performed by justifying the unbound edges of flats, rather than the bound edges. As the maU stack grows in height in a tub 40-1, 40-2, the uniformity of the stack is maintained by the tilt of the tub, and the type of edge justification. It is a discovery of the present invention that a stack of maU quickly becomes lop-sided if it is edge justified with the bound edge of the maU, which tends to be thicker than any other part of the flats maU. This phenomenon is illustrated in the diagrammatic illustration of Fig. 12, wherein the left-hand portion of the figure shows "bound edge justification" and the right-hand portion of the figure depicts "unbound edge justification". With the unbound edge justification the maU stack grows uniformly, as iUustrated in Fig. 12, during testing stacks of mail which were 12" taU with bound edge justification and had an average height of 10 %" when justified by the unbound edge. Therefore, a stack of flats mail justified by the unbound edge is more compact and less lop-sided than one stacked by bound edge justification.

The operation of the flats bundle coUator of the present invention is controUed by a combination of hardware and software described in connection with Figs. 13 to 19. Referring first to Fig. 13, which depicts the hardware architecture of the system of the present invention; a system controUer 50 is the heart of the hardware and in a preferred embodiment is a commercially avaUable IBM compatible, Pentium class computer, with monitor and keyboard. The various control devices are coupled to the system computer 50 and include an operator interface 54, and a power controUer 52. The other operative components of the system including the feeder 10, barcode reader 14, staging towers 16, conveyor TC, containerizer 18, reject tub 56, and diverter module 12 are also operatively connected to system computer 50.

The system controller 50 is a computer containing the application programs and databases. It also contains a controUer card for a commerciaUy avaUable high-speed daisy chain controUed bus. This bus is used throughout the system to activate and sense the other control components. For position tracking, the computer 50 also contains a counter card to interface with conveyor encoders to be described hereinafter.

The operator interface 54 allows the computer 50 to display information on its monitor to the operator and to receive inputs. The computer also includes a standard keyboard. Also included are emergency stop controls. These controls consist of buttons and indicators.

The power controller 52 provides the 3-phase electrical connection to the buUding power source. It includes power on/off indicators, circuit breaker protection, phase load balancing, and motor power emergency stop capability. The computer senses when an emergency stop has occurred. The components of the subsystem are located throughout the flats bundle coUator modules, and wiU be described hereinafter with reference to Figs. 20 to 23. The feeder 10, described hereinbefore, interfaces with the computer

50 through a control bus in order to synchronize the feeder operation with the other components of the system.

The barcode reader 14 is a commerciaUy avaUable item as described hereinbefore. The computer 50 interfaces to the barcode reader 14 through the control bus. The computer controls the operation of the mail transport conveyors TC. There are two independently powered sections. The first section TC-1 is located between the feeder 10 and the first staging tower 16. The second section TC-2 runs from the first tower 16 to the end of the system. To track maU position, the computer reads an encoder from each section. These encoders wiU be described further hereinafter with reference to Figs. 20 to 23.

The staging towers 16 handle the insertion and extraction of mail pieces to the staging towers 16-1 to 16-n, wherein n represents the total number of modular staging towers assembled for a given configuration. Mail F is inserted or extracted by indexing the towers 16 up or down. Because this is a modular system, where additional towers can be added, the controls interface to the computer 50 is a commerciaUy avaUable control bus described hereinbefore. The computer 50 controls the indexing of the shelves S within the towers 16. It reads a sensor position on a conveyor and keeps track of the locations of maU pieces travelling on that section. The components of the staging tower 16 have been described hereinbefore and include a shelf lift motor, position sensors, limit switches, and override switches. The containerizer module 18 is also coupled through the control bus to the system computer 50. This provides the controls for the loading of the maU pieces into the output tubs 40-1, 40-2. The computer 50 diverts the conveyor section to pass the maU into a tub 40 or allows it to continue along the conveyor through the use of the pop-up conveyor sections in containerizer 18. The elevation of the maU tub is controUed locaUy and the operator has manual override controls. The computer 50 senses when an output tub is present and when it is full.

The reject tub 56, receives nonconforming maU pieces. It is simUar to the maU tubs 40 and is Ulustrated at the output of the containerizer module 18 in Fig. 11. The elevation of the reject mail tub 56 is controlled locaUy and the operator has manual override controls. The computer 50 can sense when a reject tub is present and when it is fuU. The components include a tub elevation motor, position sensors and indicators, limit switches and override switches. AU of the control hardware of the system, illustrated Fig. 13, is run by appropriate software architecture. The computer 50 runs under the standard Microsoft NT operating system, with a commerciaUy avaUable realtime kernel. Parts of the application software are interrupt driven, from the conveyor encoders, and need to be executed soon after they interrupt the curves. Because NT is not a true real-time operating system, it does not have a consistent or fast capability in this area. The purpose of the real-time kernel is to provide this capability. Application software is programmed using high-level Microsoft C/C++ language using standard coding practices.

The operator O interacts with the system using the computer 50, its associated keyboard and monitor, and the feeder control panel. There are also emergency stop buttons within easy reach. Operator displace grains conform to standard usage guidelines and lead the user with appropriate prompts through the task to perform.

The application software is grouped into modules iUustrated in Fig. 14. These modules include a main control sequencer (software of computer 50) 57 initialized by appropriate initialization procedures 58, a data manipulation module 62, operational process module 64, and machine control interface modules 66.

After power on and computer initialization is effected by procedures 58, the application program is automatically started. Initialization includes the tasks such as reading hardware sensors, and setting actuators, setting software data tables and configurations. The main control sequencer software 57 is then started.

The main control sequencer software 57 has primary control over aU the tasks to be performed. It starts tasks, controls the sequence of events, and stops tasks. The type of tasks performed include; user logon/ logoff, accessing carrier route data for display or update, initiating carrier route sortations, generating reports, accessing machine performance statistics, and initiating maintenance tasks. The machine control interface software modules 66 are the interface and low level drivers for the system. These are used by the software to sense and control the operation of the hardware components of Fig. 13. Examples of these operations include: feed a single mail piece; start conveyor section one; and check to see if the maU output tub is full. The data manipulation software 62 handles the storage and retrieval of various types of data. Examples of this data include: number of stops on a route; the DPS code for each stop on a route, in order of dehveiy; the number of pieces misread by the barcode reader; and total number of maU pieces fed by the feeder. The operational processing software modules 64 handle the operations associated with several larger tasks. These are identified in each of the blocks within block 64 in Fig. 14, and include: flats insertion sort algorithms; flats extraction sort algorithm; error /jam handler; maintenance trouble-shooting routines; and report generation.

As the main control sequencer software 57 executes, it caUs functions in the various modules. The hardware 50 and software 57 work together to lead the operator through the completion of desired tasks.

The overaU operation of the flats bundle coUator system of the present invention is Ulustrated in the block diagram of Figs. 15A and 15B . A typical carrier route sortation includes the foUowing sequence of steps. At the start, in step 68, the operator enters the route ID and sets up an output tub 40-1 or 40-2 to be fiUed. This data is stored in database 86 and fed to the computer 50 for processing at step 94 to be described hereinafter. In step 70, the operator loads the bundles of flats into the feeder 10. The bundles are separated according to mailings. In step 72, the operator teUs the computer 50 to start the sortation. In step 74, the feeder 10 singulates and feeds the flats F to the diverter module 12. In step 76, the barcode reader 14 reads the barcode on the flats F, including the dehveiy point sequence (DPS), namely, the walk sequence of the route carrier (WS). In step 78, the system computer 50 checks the barcode for validity and identifies the tower for staging. This information is stored in the database 88 for comparison with the database 86 at step 94 by the computer 50. In step 80, the flats F travel on the conveyor to the target tower 16 and are inducted therein. In step 82, the system computer 15 waits for the last flat to be inducted into the towers 16. In step 84, the operator removes tub 56 of rejected flats, which have been processed in step 86 to include misreads on the conveyor placed in the reject tub. The process continues onto Routine A in Figs. 15A and 15B.

In step 90 of routine A, the operator loads saturation (mass mailing) bundles into the feeder 10. In step 92, the operator notifies the computer 50 to begin coUation. In step 94, as described hereinbefore, the computer 50 checks the inventory in the towers against the carrier sequence and determines the proper output sequence. In step 96, the flats F are moved onto the conveyor TC in carrier walk sequence (WS). In step 98, the flats F travel to a selected one of the output tubs 40-1, 40-2 in containerizer module 18. In step 100, the system notifies the operator that the coUation process for unloading tower 16 is complete. The operator in step 102 removes the tub of coUated flats and substitutes the next tub to be filled. In step 104, any rejected flats in the reject tub 56 are manuaUy placed in proper sequence for the mailings. This completes a typical operational scenario for the coUation of a carrier's route of flats maU. There is a simple order in which the mailings are fed through the FBC of the present invention. If there is a mailing with pieces thicker than .375", the operator feeds those first. The normal thickness mailings are fed next. If there is a saturation mailing, it is fed last. This provides better utilization of the tower capacity. The saturations are fed last, because they can be coUated directly from the feeder 10 and do not have to be stored in the tower 16. This increases the actual capacity of the system, as weU as increasing the system throughput.

The FBC system operation consists of two phases. During the induction phase, maU pieces are fed into the system and stored in tower locations 16. During the coUation phase, an algorithm determines the extraction sequence; maU pieces are extracted from their storage locations in towers 16 and placed in a selected one of output maU tubs 40-1, 40-2, 56. If a saturation mailing is to be sorted, it is fed into the system during the coUation phase. As the regular pieces are extracted, the system interrningles the saturation pieces at the proper times to achieve the desired output sequence. This aUows the system to handle a larger volume of maU and have higher throughput. A flowchart of the coordination of the induction and coUation phases of the system of the present invention is iUustrated in the flowchart of Fig. 16. At the start, in step 106, maU induction is performed. At this point, the operator has selected the carrier's route. The computer 50 has retrieved this route information from the internal databases and performed necessary utilizations.

In step 106, the operator places the mailings into the feeder. If there is a saturation or other large mailing, the operator wiU feed that during the performed maU extractions, step 114, to be described hereinafter. As each piece of maU F is fed, it is read by the barcode reader 14 and its carrier stop is determined from the database. Starting at the first upstream tower 16-1, the computer 50 examines the carrier stops of the last piece in each tower. It determines the tower whose last piece is closest, but stiU earlier, to the fed piece and sends the pieces down the conveyor to be conducted into that tower. AU barcode misreads and pieces that the system is unable to stage are sent to the reject tub 56, as iUustrated in Fig. 15. This operation continues for all non-saturation pieces.

As pieces are fed, the computer 50 tracks where each piece goes and all other relevant information about it. When aU of the non-saturation pieces have been fed, the operator informs the computer and loads the saturation, or large mailings, as iUustrated in Routine A of Figs. 15A and 15B. This is done at the beginning of the coUation phase.

Returning to the description of the flowchart of Fig. 16, step 108 is a decision block as to whether or not a saturation mailing is being processed. If "NO", the process proceeds to step 112 to deteimine the extraction sequence. If "YES", the process proceeds to perform maU feed at step 110. In step 110, this function is only performed if there is a saturation or large mailing. If a piece needs to be fed, the feeder wiU feed pieces until the barcode reader 14 has read a vahd piece for the carrier's route. This piece travels down the first conveyor connected to the output of the feeder 10 and stops just before the first upstream tower 16. At this time, the feeder 10 wiU stop feeding the pieces. This piece remains stored at the end of the first conveyor TC-1, until the computer determines that it needs to be extracted, and placed on the second conveyor TC-2, to be sent directly to a selected one of the output tubs in containerizer module 18. In step 112, the determination of the extraction sequence consists of several steps. The end result is an ordered list describing the extraction and move events. This list begins with the current events and continues until the last piece is placed in the tub selected.

A general indication of the flow of maU is iUustrated in Fig. 17. This figure depicts only three towers for simplicity to provide a coherent overview of the coUation of pieces of maU through the system. In the left-hand portion of Fig. 17, the three towers are indicated as Tower 1, Tower 2, and Tower 3. In each tower, the pieces of maU are inserted as designated mailings M, bundles B, and pieces, represented by a numeral, 1, 2, 3, etc. As indicated, Tower 1 includes mailings M3, bundles Bl, and pieces 1, 2 and 3 of those mailings and bundles. Tower 2 stores mailings M2, bundles Bl, and pieces 1 and 2. Tower 3, stores mailings Ml, bundles Bl, and B2, and pieces 1 and 2 from the respective bundles. In the middle section of Fig. 17, the mailings, bundles, and pieces of the left-hand section are designated by the dehveiy point sequence numbers (carrier walk sequence) obtained from the ZIP code on the pieces of mailing as read by reader 14. It can be seen that the pieces are stored in descending order from bottom to top in the respective towers in the walk or dehveiy point sequence.

Fig. 17 depicts the coUation output sequence of the pieces of maU, which is in reverse of the dehveiy point or walk sequence in the center portion of the figure. Returning to the flowchart of Fig. 16, in step 112, the determination of the extraction sequence consists of several steps. The end result is an ordered list describing the extraction and move events. The hst begins with the current events and continues until the last piece is placed in the output tub. In step 1, the carrier's walk sequence is stored in the system database. Using this sequence and the known piece information, the algorithm calculates through aU avaUable pieces and creates an output sequence table Ulustrated in Fig. 18A. This table shows the sequence each piece wiU be in, in the final output stack and the pieces' current location. The coUation rules are iUustrated in the left-hand column of Fig. 18, the sequence number in the next column, the current time in the next column, the calculation in the next column, and the resulting feed time in the final column. The last piece to be dehvered by the carrier wiU be the first piece into the selected maU tub. Exactly what time to extract a maU piece from its storage location is dependent on several factors. If the current piece tower 16 is downstream from the previous piece tower, then the current tower has to postpone extraction until the previous piece has passed by. If the current piece tower is upstream from the previous piece tower, then the current tower may possibly extract before the previous piece is extracted, because current piece wiU be on the conveyor for some time before it reaches the previous piece's tower. The algorithm steps through each piece in the output sequence table of Fig. 18A and calculates an extraction time for each piece. The extraction time computed is listed in the output sequence table of Fig. 18B. Referring again to the flowchart of Fig. 16, the program proceeds to step 114; perform maU extraction. In this step, which is completely Ulustrated in the diagrammatic sequence of extraction steps of Figs. 19A to 19L, the extraction events in the extraction time hst of Fig. 18B are performed. This places one or more pieces of flats from the tower 16 on the second conveyor section TC-2, as iUustrated in the steps of Fig. 19. The mail pieces are numbered in Fig. 19 in correspondence to the numbers assigned in Figs. 17, 18A, and 18B described hereinbefore.

In the final step of the flowchart of Fig. 16, the computer 50 at step 116 checks to see if there is more maU in the system to be processed. If there is, the computer needs to get ready to perform another extraction of maU. At this point, the routine is done and the coUation of this particular carrier's mailings is complete. The operator can then start another carrier's route and the input associated bundles of maU therefor.

Referring to Fig. 20, there is iUustrated in diagrammatic form, tracking information for the pieces of flats mail passing through the system; and Figs. 21 and 22 fllustrate tracking data obtained from the system of Fig. 20. Fig. 23, in conjunction with Figs. 20 to 22 fllustrate how a jammed condition of flats mail can be detected in the system of the present invention.

As pieces of maU travel along the conveyors TC-1 and TC-2, the computer 50 needs to track where they are. It needs to know when a piece is at a tower 16 and can be inserted into that tower, when a piece is not at a tower and one can be extracted, and when a piece did not arrive when it was supposed to and may be jammed. There are two types of hardware in system of the present invention used for tracking maU, namely, pulse encoders PE and photo sensors PS. Each conveyor section TC-1, TC-2 has an encoder PE that generates a pulse as the conveyor system moves. There are a fixed number of pulses during an inch of conveyor travel. Therefore, by counting pulses, the computer 50 can determine how far along the conveyor TC-1, TC-2 a piece should have traveled. Since the position is derived directly from the conveyor, instead of by timing the pieces based on a speed calculation, the system automatically accounts for start and stop accelerations, as weU as running speed variations.

Several photo sensors PS are placed along the conveyor to detect when a piece F actuaUy passes by. They are spaced such that only one maU piece F would be between them. The distance from the feeder 10, for each sensor, can be determined and expressed as a number of encoder pulses from pulse encoder PE. This hardware provides information on where the piece should be and where it actuaUy is or is not to the computer 50. This tracking information is Ulustrated in the tables of Figs. 21 and 22. When a piece of maU is fed, the software adds information about the piece to a temporary tracking table. As the piece travels along the conveyor, the table in Fig. 21 is updated. This is used to track the piece and detect abnormal conditions. The table in Fig. 22 includes information such as the last known position of the piece, the next expected sensor position, the gap between adjacent pieces, and the destination tower for that piece.

Because the maU pieces are not physicaUy constrained on the conveyors TC-1, TC-2, they may slip and move slightly slower than the conveyor itself. At a given sensor PS, this effect appears as a larger actual pulse. The system is very tolerant of slippage because it initiates tower motion based on the actual location of the piece. If the difference in pulse counts from the encoders is too large or the gap too small, then something significant must have happened to the piece, which is interpreted as a jam condition. The test threshold conditions for determining a jam are Ulustrated in Fig. 23. When a jam condition is detected, the computer 50 stops the system and describes the problem to the operator. In addition, there are a series of indicator hghts along the length of the machine. These wiU hght at the location of the jam. When the operator has cleared the jam condition, he/she notifies the computer to continue with the sortation.

The present invention has been described for sorting flats mail, which are the preferred items to be coUated. However, other items of manufacture requiring orderly sequencing could be sorted in accordance with the present invention, such as circuit boards, and other electrical components.

Claims

WHAT IS CLAIMED:

1 1. A method of coUating a plurality of groups of maU items,

2 each group being pre-sequenced according to prioritized dehveiy

3 addresses, into a final sequenced set of the maU items from the

4 groups, utilizing the prioritized dehveiy addresses, comprising the

5 steps of:

6 separating each bundles of maU seriatim into a single input

7 stream of the individual maU items;

8 transporting the maU items from the input stream to a staging

9 station;

10 sorting the maU items at the staging station into a plurality of

11 subsets of maU items re-sequenced as an intermediate step to

12 achieving said final sequenced set;

13 merging the maU items into a single output stream from the

14 respective subsets of maU items in said final sequenced set; and

15 coUecting portions of the output stream of maU items consistent

16 with the sequence of the final sequenced set to form batches of maU

17 for orderly dehveiy to the prioritized dehveiy addresses according to

18 dehveiy criteria reflected in said final sequenced set.

1 2. The method of claim 1, wherein the maU items comprise

2 flats mail from the group consisting essentiaUy of: magazines,

3 newspapers, padded envelopes, single sheet fliers, compact disks, and

4 poly- wrapped items.

1 3. The method of claim 2, wherein each subset is stored at

2 the staging station in a separate vertical stack of maU items.

4. The method of claim 3, wherein each subset is stored at the staging station in a separate vertical stack of maU items.

5. The method of claim 1, wherein the merging device is initiated to merge the pre-sequenced groups to form the input stream during feeding of the last pre-sequenced group of maU items into the input stream.

6. The method of claim 5, wherein each flat has a prioritized dehveiy address thereon, with a machine readable number for each envelope therein, the machine readable number being part of a numerical dehveiy order sequence with lower numbers representing high dehveiy priorities, and including the further steps of reading the numbers, and generating control signals for routing the flats to predetermined ones of the vertical stacks at the staging station; the flats in each stack being positioned in ascending order number from the bottom to top of the stack.

7. The method of claim 3, wherein each flat envelope has a prioritized deliver address and a machine readable number thereon, the machine readable number being part of a numerical dehveiy order sequence . with lower numbers representing high dehveiy priorities, and including the further steps of reading the numbers, and generating control signals for routing the envelopes to predetermined ones of the vertical stacks at the staging station; the flats in each stack being positioned in ascending order number from bottom to top of the stack.

8. A system for coUating a plurality of groups of maU items, each group being pre-sequenced according to prioritized dehveiy addresses, into a final sequenced set of maU items from the groups, utilizing the prioritized dehveiy addresses comprising; a separating device for separating each bundle of maU seriatim into a single input stream of the individual maU items; a transport conveyor for feeding the maU items from the input stream to a staging device, a sorting device for sorting the maU items at the staging station into a plurahty of subsets of maU items re-sequenced as an intermediate step to achieving said final sequenced set; a merging controUer for merging the maU items into a single output stream from the respective subsets of maU items in said final sequenced set; and a coUection device for coUecting portions of the output stream of maU items consistent with the sequence of the final sequenced set to form batches of maU for orderly dehveiy to the prioritized dehveiy addresses according to dehveiy criteria reflected in said final sequenced set.

9. The system of claim 8, wherein the merging device is initiated to merge the pre-sequenced groups to form the input stream during feeding of the last pre-sequenced group of maU items into the input stream.

10. The system of claim 8, wherein the maU items comprise flats maU from a group consisting essentiaUy of: magazines, newspapers, padded envelopes, single sheet fliers, compact disks, and poly-wrapped items.

11. The system of claim 8, wherein each subset is stored in the staging device in a separate vertical stack of mail items.

12. The system of claim 9, wherein each subset is stored in the staging device in a separate vertical stack of maU items.

13. The system of claim 10, wherein the staging device stores each subset at the staging station in a separate vertical stack of said flat envelopes.

14. The system of claim 13, wherein each flat envelope has a prioritized dehveiy address and a machine readable number thereon, the machine readable number being part of a numerical dehveiy order sequence with lower numbers representing higher dehveiy priorities, and further including a reader for reading the numbers, and generating control signals for routing the envelopes to predetermined ones of the vertical stacks at the staging station, the envelopes in each stack being positioned in ascending order number from bottom to top of the stack.

15. The system of claim 10, wherein each flat envelope has a prioritized dehveiy address and a machine readable number thereon, the machine readable number being part of a numerical dehveiy order sequence with lower numbers representing higher dehveiy priorities, and further including a reader for reading the numbers, and generating control signals for routing the envelopes to predetermined ones of the vertical stacks at the staging station, the envelopes in each stack being positioned in ascending order number from bottom to top of the stack.

16. A method of coUating a plurahty of groups of items, each group being pre-sequenced according to a prioritized order into a final sequenced set of the items from the groups, utilizing the prioritized order, comprising the steps of: separating each bundle of items seriatim into a single input stream of the individual items; transporting the items from the input stream to a staging station; sorting the items at the staging station into a plurahty of subsets of items re-sequenced as an intermediate step to achieving said final sequenced set; merging the items into a single output stream from the respective subsets of items in said final sequenced set; and coUecting portions of the output stream of items consistent with the sequence of the final sequenced set to form batches of items in the prioritized order.

17. A system for coUating a plurahty of groups of items, each group being pre-sequenced according to a prioritized order, into a final sequenced set of items from the groups, utilizing the prioritized order comprising; a separating device for separating each bundle of items into a single input stream of the individual items; a transport conveyor for feeding the items from the input stream to a staging device, a sorting device for sorting the items at the staging station into a plurahty of subsets of items re-sequenced as an intermediate step to achieving said final sequenced set; a merging controUer for merging the items into a single output stream from the respective subsets of items in said final sequenced set; and a coUection device for coUecting portions of the output stream of items consistent with the sequence of the final sequenced set to form batches of items in the prioritized order.

18. The system of claim 17, wherein the merging device is initiated to merge the pre-sequenced groups to form the input stream during feeding of the last pre-sequenced group of maU items into the input stream.

19. The system of claim 17, wherein each subset is stored in the staging device in a separate vertical stack of maU items.

20. A staging tower for storing a plurahty of items in a vertical stack above a conveyor having a conveying path passing transversely through the tower comprising: a housing for the tower defining a vertically oriented volume of space; a shelf storage zone in the housing in the space below the conveying path, for storing a plurahty of verticaUy stacked empty shelves separated by a predetermined pitch between the shelves; an item storage space above the conveying path for storing the shelves and items thereon for a stack of items separated by a selected pitch; a transfer zone between the shelf storage zone and the item storage zone for accommodating the conveyor; and an elevator mechanism for moving the shelves one at a time from the shelf storage zone, through the transfer zone, and into the item storage zone; each shelf being capable of picking up articles on the conveyor in the transfer zone and lifting the articles into the item storage zone.

21. The staging tower of claim 20, wherein said conveyor includes a plurahty of spaced movable members defining a conveying surface and the shelves include spaced fingers verticaUy movable through the space between the movable members in response to engagement with the elevator mechanism.

22. The staging tower of claim 21, wherein the elevator mechanism comprises; a first endless belt disposed on rotatable puUeys for vertical movement through the shelf storage zone; and a plurahty of spaced lugs extending from the endless belt for engaging and lifting the shelves; a second endless belt disposed on rotatable pulleys for vertical movement through the transfer zone, and a plurahty of lugs on the second endless belt for engaging shelves in the transfer shelves in the transfer zone as the shelves emerge from the top of the shelf storage zone; and a third endless belt disposed on rotatable pulleys in the item storage zone, said third endless belt having lugs extending therefrom for picking up shelves emerging at the top of the transfer zone with the articles thereon and lifting the shelves and items into the item storage zone.

23. The system of claim 12, wherein said vertical stacks are formed in a plurahty of juxtaposed staging towers disposed along the transport conveyor, each staging tower including: a housing for the tower defining a verticaUy oriented volume of space; a shelf storage zone in the housing in the space below the conveying path, for storing a plurahty of verticaUy stacked empty shelves separated by a predetermined pitch between the shelves; an item storage zone above the conveying path for storing the shelves and items thereon for a stack of second items separated by a selected pitch; a transfer zone between the shelf storage zone and the item storage space for accommodating the conveyor; and an elevator mechanism for moving the shelves one at a time from the shelf storage zone, through the transfer zone, and into the item storage zone; each shelf being capable of picking up items on the conveyor in the transfer zone and lifting the items into the item storage zone.

24. The system of claim 23, wherein said transport conveyor includes a plurahty of spaced movable members defining a conveying surface and the shelves include spaced fingers verticaUy movable through the space between the movable members in response to engagement with the elevator mechanism.

25. The system of claim 24, wherein the elevator mechanism comprises; a first endless belt disposed on rotatable pulleys for vertical movement through the shelf storage zone; and a plurahty of spaced lugs extending from the endless belt for engaging and lifting the shelves; a second endless belt disposed on rotatable pulleys for vertical movement through the transfer zone, and a plurahty of lugs on the second endless belt for engaging shelves in the transfer zone as the shelves emerge from the top of the shelf storage zone; and a third endless belt disposed on rotatable puUeys in the item storage space, said third endless belt having lugs extending therefrom for picking up shelves emerging at the top of the transfer zone with the items thereon and lifting the shelves and items into the item storage zone.

26. The system of claim 19, wherein said vertical stacks are formed in a plurahty of juxtaposed staging towers disposed along the transport conveyor, each staging tower including: a housing for the tower defining a verticaUy oriented volume of space; a shelf storage zone in the housing in the space below the conveying path, for storing a plurahty of vertically stacked empty shelves separated by a predetermined pitch between the shelves; an item storage zone above the conveying path for storing the shelves and items thereon to form a stack of items separated by a selected pitch; a transfer zone between the shelf storage zone and the item storage zone for accommodating the conveyor; and an elevator mechanism for moving the shelves one at a time from the shelf storage zone, through the transfer zone, and into the item storage zone in response to signals from the sorting device and merging controUer; each shelf being capable of picking up items on the conveyor in the transfer zone and lifting the items into the item storage zone.

27. The system of claim 26, wherein said transport conveyor includes a plurahty of spaced movable members defining a conveying surface and the shelves include spaced fingers verticaUy movable through the space between the movable members in response to engagement with the elevator mechanism.

28. They system of claim 27, wherein the elevator mechanism comprises; a first endless belt disposed on rotatable puUeys for vertical movement through the shelf storage zone; and a plurahty of spaced lugs extending from the endless belt for engaging and lifting the shelves; a second endless belt disposed on rotatable puUeys for vertical movement through the transfer zone, and a plurahty of lugs on the second endless belt for engaging shelves in the transfer zone as the shelves emerge from the top of the shelf storage zone; and a third endless belt disposed on rotatable puUeys in the item storage zone, said third endless belt having lugs extending therefrom for picking up shelves emerging at the top of the transfer zone with the items thereon and lifting the shelves and items into the item storage zone.

29. A collection device for items moving along a transport conveyor comprising: at least two collection assemblies for selectively extracting items from the conveyor, each collection assembly including a pop-up conveyor section movable between a first position operatively aligned with the transport conveyor for receiving items exiting the transport conveyor and moving the items along the pop-up conveyor section to bypass an associated container, and a second position for diverting the items exiting the transport conveyor into the associated container, said collection assemblies being disposed in tandem at an output end of the transport conveyor; an actuator for each pop-up conveyor for moving the section between the first and second positions; and a collection controller for selectively energizing the activators.

30. The collection device of claim 29, wherein the associated containers are rectangular tubs with five closed sides and one open side, and there is further provided beams for supporting the tub with the open side tilted at an angle with respect to horizontal, an inclined chute for feeding items diverted by the pop-up conveyor section into a selected one of the tubs and an indexing device for moving selected tub down relative to an output end of the inclined chute as the tub is being filled with items at an indexing rate related to the rate of flow of the items into the tub.

31. The collection device of claim 30 further including an inclined baffle disposed within each tilted tub for engaging items exiting the chutes and deflecting the items downwardly toward a bottom end of the tilted tubs.

32. The collection device of claim 31, wherein the indexing assembly includes at least one endless drive belt disposed on rotatable pulleys, the drive belt being operatively connected to the tilted tub for transporting the relative movement thereto, and a motor for driving the endless drive belt.

33. The collection device of claim 8 comprising: at least two collection assemblies for selectively extracting items from the conveyor, each collection assembly including a pop-up conveyor section movable between a first position operatively aligned with the transport conveyor for receiving items exiting the transport conveyor and moving the items along the pop-up conveyor section to bypass an associated container, and a second position for diverting the items exiting the transport conveyor into the associated container, said collection assemblies being disposed in tandem at an output end of the transport conveyor; an actuator for each pop-up conveyor for moving the section between the first and second positions; and a collection controller for selectively energizing the activators.

34. The collection device of claim 33, wherein the associated containers are rectangular tubs with five closed sides and one open side, and there is further provided means for supporting the tub with the open side tilted at an angle with respect to horizontal, an inclined chute for feeding items diverted by the pop-up conveyor section into a selected one of the tubs and an indexing device for moving the selected tub down relative to an output end of the inclined chute as the tub is being filled with items at an indexing rate related to the rate of flow of items into the one tub.

35. The collection device of claim 34 further including an inclined baffle disposed within each tilted tub for engaging items exiting the chutes and deflecting the items downwardly toward a bottom end of the tilted tubs.

36. The collection device of claim 35, wherein the indexing assembly includes at least one endless drive belt disposed on rotatable pulleys, the drive belt being operatively connected to the tub for transporting the relative movement thereto, and a motor for driving the endless drive belt.

37. The collection device of claim 17 comprising: at least two collection assemblies for selectively extracting items from the conveyor, each collection assembly including a pop-up conveyor section movable between a first position operatively aligned with the transport conveyor for receiving items exiting the transport conveyor and moving the items along the pop-up conveyor section to bypass an associated container, and a second position for diverting the items exiting the transport conveyor into the associated container, said collection assemblies being disposed in tandem at an output end of the transport conveyor; an actuator for each pop-up conveyor for moving the section between the first and second positions; and a collection controller for selectively energizing the activators.

38. The collection device of claim 37, wherein the associated containers are rectangular tubs with five closed sides and one open side, and there is further provided means for supporting the tub with the open side tilted at an angle with respect to horizontal, an inclined chute for feeding items diverted by the pop-up conveyor section into a selected one of the tubs and an indexing device for moving the tub down relative to an output end of inclined chute as the tub is being filled with items at an indexing rate related to the rate of flow of item into the tub.

39. The collection device of claim 38 further including an inclined baffle disposed within each tilted tub for engaging items exiting the chutes and deflecting the items downwardly toward a bottom end of the tilted tubs.

40. The collection device of claim 39, wherein the indexing assembly includes at least one endless drive belt disposed on rotatable pulleys, the drive belt being operatively connected to the tub for transporting the relative movement thereto, and a motor for driving the endless drive belt.

41. A method of stacking flats mail having bound edges and opposed unbound edges comprising the steps of: edge-justifying the unbound edges by aligning the unbound edges against a planar surface; and placing the edge-justified flats mail into a vertical stack with the unbound edges aligned on one side of the stack.

42. The method of claim 2, the mail items having substantially flat major surfaces, bound edges, and unbound edges, comprising the steps of: edge-justifying the unbound edges by aligning the unbound edges against a planar surface; and placing the edge-justified flats mail into a vertical stack with the unbound edges aligned on one side of the stack.

43. The method of claim 3, wherein a portion of said flats mail includes a saturation mailing of a plurality of substantially identical flats mail items, said saturation mailing being fed into the input stream after all other mail for a given mail carrier route is stacked in the vertical stacks of the staging station.

44. The method of claim 3, including the further steps of measuring the distance between flats mail items being transported, and generating a signal indicating a jam condition of the mail items if the distance between any two or more flats items is outside of a predetermined range of distances.