EP1385641B1 - Method and apparatus for sorting mail articles - Google Patents

Abstract

A method and apparatus for sorting articles to a delivery point sequence includes at least one sortation assembly adapted to sort articles and a buffer. The buffer is operable to arrange and convey containers of articles sorted in a first sort pass to an induct of the at least one sortation assembly for a second sort pass or process of the articles. The buffer automatically arranges the containers in an arranged manner prior to conveying the containers and articles to the induct of the at least one sortation assembly for the second sort process. The second sort process is then performed to sort the articles to a delivery point sequence or carrier walk sequence depth of sort. A conveyor assembly may be operable to convey containers to an appropriate one of multiple sortation assemblies and/or buffers to increase the sequencing matrix capability of the apparatus.

Description

The present invention relates generally to an article sorting method and apparatus and,more particularly, to an article sorting method and apparatus for the sortation of articles ofmail. The present invention is especially adapted to sort flat mail to a delivery pointsequence or carrier walk sequence, but may also apply to sort a mix of flat mail and lettermail.

BACKGROUND OF THE INVENTION

Typically, mail is received in a distribution center or warehouse from two sources.One source or type is local mail which is to be delivered within the local area. This iscommonly known as turnaround mail. Local mail may also be sorted for delivery to otherdistribution centers. Another source or type of mail is out-of-area mail received from otherdistribution centers. Mail which is to be delivered locally must, ultimately, be sorted todelivery point sequence, also known as "carrier walk sequence," i.e., the mail is sorted andarranged such that the first address stop is followed by the second address stop, which isfollowed by the third address stop, and so on. A Dual Bar Code Sequenced (DBCS)machine is capable of achieving delivery point sequence for letter mail. However, it requirestwo or more passes of the mail through the same sequence.

A process exists today to delivery point sequence letter sized mail, which sorts themail into a specific mail carrier's route sequence. The approach commonly used to sequencethe letter mail requires that the mail be processed through a Letter Sorting Machine (LSM)twice. Each of these two sort processes is referred to as a pass. The first pass inducts mail,which arrives in somewhat random order, into an LSM, which arranges it into groupings ofaddresses. The number of discreet addresses (sequences) in each grouping depends on howmany output bins of the LSM are utilized in the sorting process.

The device used to provide places to hold the mail in order is a sorting matrix, such asa grouping of slots, with each slot representing an address in the carrier's route. This sortingmatrix can be as large or as small as necessary or desired. For example, a larger matrix (ornumber of slots) allows for a larger carrier route or more individual smaller carrier routes to be processed at one time. If an LSM contains output bins equal to the number of stops on thecarrier's route, then mail for each address would be sorted to one bin. However, to be able toprocess more carrier routes at one time, a theoretical grouping of sorting slots is created usinga specific number of LSM output bins. The number of slots is typically equal to the numberof bins squared. For example, if an LSM is equipped with 10 output bins, a matrix of 100slots can be created.

Therefore, mail for the first carrier route address or sequence may be sorted to the firstassigned bin, the second address to the second bin, the third sequence to the third bin and soon to the tenth bin. The eleventh sequence may then be sorted to the first bin, the twelfth tothe second bin, and so on, up to the twentieth sequence being sorted to the tenth bin. Thissame sorting process is repeated so that the first, eleventh, twenty first, thirty first and so on,up to and including the ninety-first sequence, are sorted into the first bin, while the second,twelfth, twenty-second, thirty-second, etc. sequences are sorted into the second bin and so onfor all ten output bins.

Having completed the first sorting pass, mail is usually manually removed from theLSM and loaded onto manual carts and/or temporarily stored on shelves in racks inpreparation for the second pass. The trays are then unloaded from the manual carts and thesorted articles in the trays are reprocessed during a second pass. An alternative to manualhandling of the trays of mail between sort passes is disclosed in U.S. Pat. No. 5,385,243,which utilizes a storage and retrieval machine to stage the letter trays for the second pass.

For the second pass, it is absolutely essential that proper order of trays be maintained.First pass mail trays from bin number one of the first pass must be inducted into the LSMfirst, followed by the trays of bin number two, three and so on up to bin number ten. Thecurrent process requires machine operators to properly maintain this sequence. Wheninducted for the second pass, the sequences are sorted with address orsequence 1 beingsorted tobin 1,sequence 11 tobin 2, sequence 21 tobin 3, and so on up to sequence 91 to bin10. Trays of mail for the second bin (containingsequences 2, 12, 22, 32, 42, 52, and so on upto 92) are inducted and sorted such that address orsequence 2 is sorted tobin 1,sequence 12tobin 2,sequence 22 tobin 3, etc. When the trays of mail sorted at all ten bins during thefirst sort pass are inducted and sorted during a second sort pass,bin 1 will containsequences1 through 10,bin 2 will containsequences 11 through 20, and so on.

Accordingly, when the second sort pass is completed and the mail is removed fromthe LSM, it is sorted in carrier route sequence, i.e., first address stop followed by secondaddress stop followed by third address stop, etc. The delivery point sequence sorting matrix described above is recognized as the process currently utilized for letter mail, and can beadapted to flat mail sequencing. However, as discussed above, this process requires manualhandling of the trays between sort passes to ensure that the trays are in the proper order orsequence for the second sort pass.

Flat mail is mail which ranges in length from approximately 5 inches toapproximately 15 inches, height from approximately 6 inches to approximately 12 inches,thickness from approximately 0.009 inches to approximately 0.75 inches, and weight fromapproximately 0.01 pound to approximately 1.0 pound. It may include paper envelopes,plastic wrappers, bound catalogs, banded newspapers, open mail pieces without wrappers,and the like. Such flat mail has traditionally been sorted to the distribution center levelautomatically, such as via a model AFSM 100 flat sorting system manufactured byMannesmann Dematic Postal Automation and marketed in the United States by MannesmannDematic Rapistan Corp. The sortation from distribution center to carrier walk sequence hastraditionally been performed manually utilizing pigeon-hole bins. Such manual sorting of flatmail to the delivery point sequence may take several hours, up to half of the time availablefor a carrier to deliver his/her route.

It would be desirable to provide a carrier walk sequence for mail, especially for flatmail. It would be most desirable if the carrier walk sequence depth of sort is accomplishedautomatically. It would also be desirable if the carrier walk sequence of flat mail isaccomplished irrespective of the source or type of the mail. In particular, it would bedesirable to be able to sort turnaround mail to carrier walk sequence.

U.S. Patent No. 5,009,321 requires manual arrangement andunloading of the bins following the first sort pass to inductthe sorted mail pieces in the proper order for the secondsort pass. There is no teaching or suggestion ofautomatically sorting and conveying the bins andautomatically arranging the bins to maintain this sortintegrity.

U.S. Patent No. 5,119,954 discloses a multi-pass sortingmachine which sorts mail and stacks the mail in appropriatebins. U.S. Patent No. 5,119,954 does not disclose any meansfor sorting and conveying trays containing sorted articles;the bins of the sorting machine do not move and are notsorted and arranged in an arranged manner and conveyed to theinduct of the sorting machine. There is no disclosure,teaching or suggestion of moving or conveying the bins in anymanner or of arranging the bins in an arranged manner andconveying the arranged bins to the induct of the sortingmachine for a second sort of the mail.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for sorting flat articles whichis capable of automatically sorting the articles to delivery point sequence. The method andapparatus may utilize one or more flat sorting machines, whereby multiple flat sortingmachines may be arranged together with a tray sorting, queuing and handling system.

According to an aspect of the present invention, an article sortation system for sortingarticles to a delivery point sequence depth of sort includes at least one article sorter and abuffering assembly. The at least one article sorter has an induct and a discharge, and isoperable to sort articles into a plurality of trays and discharge the trays of sorted articles at thedischarge. The buffering assembly is operable to automatically sort and convey the trayscontaining sorted articles sorted during a first sort of the at least one article sorter from thedischarge of the at least one article sorter to the induct of the at least one article sorter. Thebuffering assembly is operable to automatically arrange the trays in an arranged manner and convey the arranged trays to the induct of the at least one article sorter for a second sort of thearticles.

The buffering assembly may include a plurality of conveyors which are cooperativelyoperable to arrange and accumulate trays in the sequenced manner on the buffering assemblyas the trays are received from the discharge of the at least one article sorter. In one form, theplurality of conveyors includes at least one transport conveyor and a plurality of zoneconveyors connected to the transport conveyor. The zone conveyors and the transportconveyor are cooperatively operable to receive trays from the at least one transport conveyorand discharge trays to the at least one transport conveyor in an appropriate order for thesecond sort. The plurality of zone conveyors are positioned along at least one side of the atleast one transport conveyor. The at least one transport conveyor may include a plurality oftransfer units, with each of the plurality of transfer units being positioned at at least one of theplurality of zone conveyors and being operable to move trays between the at least onetransport conveyor and a respective at least one of the plurality of zone conveyors.

In another form, the plurality of conveyors define at least one generally continuousloop between the discharge of the at least one article sorter and the induct of the at least onearticle sorter. The buffering assembly is operable to circulate trays in the at least onegenerally continuous loop and input new trays into appropriate spaces between the circulatingtrays in the at least one generally continuous loop as the new trays are received from thedischarge of the at least one article sorter. The at least one generally continuous loop mayinclude at least two generally continuous loops. The at least one article sorter may theninclude a plurality of individual article sorting stations, with each of the at least twocontinuous loops being operable to convey trays received from different groups of individualsorting stations of the at least one article sorter.

Optionally, the at least one article sorter may include a first article sorter and a secondarticle sorter. The buffering assembly may then be positioned along a return conveyor whichis connected between at least one of a discharge of the first article sorter and a discharge ofthe second article sorter and at least one of an induct of the first article sorter and an induct ofthe second article sorter. The article sortation system may include a second bufferingassembly connected between a discharge of the second article sorter and an induct of thesecond article sorter. The article sortation system may then include a connecting conveyorpositioned between the buffering assembly and the second buffering assembly and betweenthe discharges of the first and second article sorters. The connecting conveyor is operable toconvey trays from the discharge of the first article sorter and/or the second article sorter to an appropriate one of the buffering assembly and the second buffering assembly. Theconnecting conveyor may define a generally continuous conveying loop.

Optionally, the at least one article sorter comprises a single article sorter. Thebuffering assembly may be operable to sort and convey the trays containing sorted articlessorted during the first sort of the article sorter from the discharge of the article sorter to theinduct of the article sorter for a second sort of the single article sorter.

Optionally, the buffering assembly is positioned at a level above the at least onearticle sorter. The article sortation system may then include elevating devices which areoperable to convey trays upward from the discharge of the at least one article sorter to thebuffering assembly and downward from the buffering assembly to the induct of the at leastone article sorter.

The first sortation process may resolve the address of each article, apply a pseudoidentification to the article, which is retained in a control, and sort the article to trays, bins orcontainers. The second sortation process calls for containers from the first sortation processin a particular order and carries out a delivery point sequence sortation on the articles in thosecontainers using the information stored in the control by the first sortation process.Preferably, the delivery point sequence sortation is to 9 zip code digits and, most preferably,to 11 zip code digits.

According to another aspect of the present invention, a method for sorting articles to adelivery point sequence depth of sort includes providing at least one article sorter having aninduct and a discharge. Articles are then sorted in a first sort of the at least one article sorterinto a plurality of trays. A buffering assembly is provided for automatically sorting andconveying trays containing sorted articles sorted during a first sort of the at least one articlesorter. The trays of sorted articles are conveyed and arranged in an arranged manner on thebuffering assembly. The arranged trays of sorted articles are conveyed to the induct of the atleast one article sorter for a second sort of the articles. The articles are then sorted in asecond sort of the at least one article sorter.

In one form, the method may include conveying each of the trays to an appropriateone of a plurality of zone conveyors. The trays may be cooperatively discharged from thezone conveyors in an arranged manner.

In another form, the method may include conveying the trays in a continuous loop.The trays may be generally continuously conveyed in the continuous loop. The trays may beinducted into the generally continuous loop in an arranged manner.

Optionally, the method may include providing at least two article sorters and at leasttwo buffering assemblies. The trays may be conveyed from the discharge of one of the atleast two article sorters to one of the at least two buffering assemblies. Alternately, themethod may include providing a single article sorter.

According to another aspect of the present invention, a method of sorting articles to adelivery point sequence depth of sort via a first sort pass and a second sort pass of at least onearticle sortation assembly provides a delivery point sequencing sortation matrix. The methodincludes supplying articles for multiple carrier routes to an induct of the sortation assembly,and then sorting articles in a first sort pass to a first set of output bins of the sortationassembly, whereby each output bin of the first set of output bins receives articles for each ofthe multiple carrier routes. The sorted articles are then arranged at the induct of the sortationassembly for a second sort pass, and then sorted to a second set of output bins of the sortationassembly. The sortation matrix provides that articles from each output bin of the first set ofoutput bins are sorted to each output bin of the second set of output bins.

The first and second sets of output bins may have a different quantity of binsassociated therewith. For example, the first set may include 110 of 120 bins of the sortationassembly, while the second set may include all 120 bins, in order to maximize the number ofcarrier routes that the sortation matrix may sort. For carrier routes having approximately 650stops, the sortation matrix of the present invention is capable of sorting the articles for 20different routes to a delivery point sequence depth of sort via two sort passes through asortation machine having 120 output bins.

According to another aspect of the present invention, a delivery point sequencingsystem includes a conveying assembly for automatically sorting and conveying trayscontaining sorted articles from a discharge of at least one sorting assembly to an induct of theat least one sorting assembly. The conveying assembly has a generally continuous conveyingtrack and is operable to automatically provide the trays containing sorted articles to the inductof the sorting assembly in a sequenced manner.

In one form, the at least one sorting assembly includes a single sorting assembly. Theconveying assembly is operable to sort and convey trays between the discharge end of thesingle sorting assembly to the input end of the single sorting assembly.

In another form, the at least one sorting assembly includes a first sorting assembly anda second sorting assembly. The conveying assembly is operable to sort and convey traysbetween a discharge end of the first sorting assembly and an induct end of the second sortingassembly.

The conveying assembly preferably includes a plurality of conveyors which arecooperatively operable to arrange trays in a sequenced manner on the conveying assembly asthe trays are received from the discharge of the sorting assembly. In one form, the pluralityof conveyors define at least one continuous loop between the discharge of the sortingassembly and the induct of the sorting assembly. The conveying assembly is then operable tocycle trays around the at least one continuous loop and input new trays into appropriatespaces between the cycling trays in the at least one continuous loop as the new trays arereceived from the discharge of the sorting assembly.

In another form, the conveyors include a plurality of zone conveyors which areoperable to receive trays from and discharge trays to at least one transfer conveyor whichconveys the trays to the induct of the sorting assembly. The zone conveyors and the transferconveyor are cooperatively operable to arrange the trays in a sequenced manner on thetransfer conveyor for the second sort pass.

According to another aspect of the present invention, a method of sorting mail to adelivery point sequence depth of sort includes providing at least one article sorter adapted toperform at least two sort processes to articles supplied thereto and providing at least oneconveyor between a discharge of the at least one article sorter and an input of the at least onearticle sorter. Articles are supplied to the at least one article sortation assembly and a firstsort pass is performed to sort the articles. Containers of the sorted articles are substantiallycontinuously conveyed to arrange the containers in an arranged manner. The arrangedcontainers are conveyed to an input of the at least one article sorter and a second sort pass isthen performed to sort the articles to the delivery point sequence depth of sort. Preferably,the method includes buffering the containers on the at least one conveyor.

The at least one conveyor may be operable to automatically convey and arrangecontainers from a discharge of the at least one article sorter to the input of the at least onearticle sorter.

In one form, the method may include providing at least one continuous conveyingloop between the discharge and the input of the at least one article sorter. The at least oneconveyor may include at least one incoming conveyor leading from the discharge of the atleast one article sorter to the at least one continuous conveying loop and at least one outgoingconveyor leading from the at least one continuous conveying loop to the input of the at leastone article sorter. The method may include substantially continuously circulating containersaround the at least one continuous conveying loop and inducting containers from the at leastone incoming conveyor at appropriate places between the circulating containers to arrange the containers in the arranged manner. The method may provide at least two independentlyoperable continuous loops between the at least one outgoing conveyor and the at least oneincoming conveyor.

In another form, the method may provide a plurality of zone conveyors which areoperable to receive containers from and discharge containers to at least one transportconveyor which conveys the containers to the input of the at least one article sorter. Thecontainers may be cooperatively discharged from the zone conveyors in an appropriate orderonto the transport conveyor to arrange the containers on the transport conveyor in thearranged manner for the second sort pass.

Optionally, the method may provide a single article sorter and convey arrangedcontainers from the discharge of the single article sorter to the input of the single articlesorter. Alternately, the method may provide first and second article sorters. Articles may besupplied to an induct of the first article sorter, and the arranged containers may be conveyedto an induct of the second article sorter. The method may provide at least two of the firstarticle sorters, where each of the first article sorters has a throughput that is approximatelyone-half the throughput of the second article sorter.

According to yet another aspect of the present invention, an article sortation systemfor sorting articles to a delivery point sequence depth of sort includes at least two articlesorters and a conveying system. Each of the article sorters includes an induct and adischarge. The article sorters are operable to sort articles into a plurality of trays anddischarge the trays of sorted articles at the discharges. The conveying system isinterconnected between the inducts and the discharges of the article sorters. The conveyingsystem is operable to sort and convey trays containing articles sorted during a first sort passof the article sorters. The conveying system is operable to automatically arrange the trays inan arranged manner and provide the arranged trays to the inducts of the article sorters for asecond sort of the articles.

Preferably, the conveying system includes at least two buffering assemblies connectedto the induct of a respective one of the article sorters and a conveyor assembly connectedbetween the discharges of the article sorters and the buffering assemblies. The conveyor isselectively operable to convey trays from the discharges to an appropriate one of thebuffering assemblies, where the trays are arranged and then conveyed to a respective one ofthe article sorters for a second sort pass through the respective one of the article sorters. Theat least two buffering assemblies include a first buffering assembly connected to the induct ofa first one of the at least two article sorters and a second buffering assembly connected to the induct of a second one of the at least two article sorters. Each of the first and secondbuffering assemblies preferably includes a plurality of conveyors which are cooperativelyoperable to arrange and accumulate trays in a sequenced manner on the buffering assembliesas the trays are received from the conveyor assembly.

In one form, the plurality of conveyors define at least one continuous loop betweenthe conveyor assembly and the inducts of the first and second article sorters. The plurality ofconveyors are operable to circulate trays on the at least one continuous loop and induct traysinto appropriate spaces between the circulating trays in the at least one continuous loop as thenew trays are received from the conveyor assembly.

In another form, the plurality of conveyors include at least one transport conveyor anda plurality of zone conveyors connected to the at least one transport conveyor. The pluralityof zone conveyors and the at least one transport conveyor are cooperatively operable toconvey trays from the at least one transport conveyor to the plurality of zone conveyors, andto convey trays from the plurality of zone conveyors to the at least one transport conveyor inan appropriate order for the second sort.

The conveying system may be positioned at a level above the article sorters. Thearticle sortation system may then further include elevating devices which are operable toconvey trays upward from the discharges of the article sorters to the conveyor assembly anddownward from the conveyor assembly or buffering assemblies to the respective one of theinducts of the article sorters.

Preferably, the article sortation system further includes a control which is operable todetermine an appropriate one of the article sorters for a second sort pass for articles in aparticular tray, whereby the conveying system is operable to convey and arrange the tray forinduction to the appropriate one of the article sorters in response to the control.

According to yet another aspect of the present invention, a method of sorting mail to adelivery point sequence depth of sort includes providing at least two article sortationassemblies adapted to perform at least two sort processes to articles supplied thereto. Articlesare supplied to the at least two article sortation assemblies and a first sort pass is performedon the articles. The method includes determining an appropriate one of the at least twoarticle sortation assemblies for the sorted articles to be inducted into for a second sort pass.Trays containing sorted articles sorted by the first sort pass are conveyed to arrange the traysin an arranged manner. The arranged trays are then conveyed to an input of the appropriateone of the at least two sortation assemblies. A second sort pass of the articles is performed tosort the articles to a delivery point sequence depth of sort.

Preferably, the step of conveying trays includes buffering trays of sorted mail andarranging the trays in the arranged manner. The step of buffering trays may includecirculating trays around at least one continuous loop positioned between a discharge of thefirst sortation assembly and an induct of the second sortation assembly, and inductingcontainers at appropriate places between the circulating containers to arrange the containersin the arranged manner.

Optionally, the step of conveying trays of sorted articles may include conveying traysof sorted articles along at least one transport conveyor, conveying the trays to a plurality ofzone conveyor connected to the at least one transport conveyor, and cooperativelydischarging trays from the plurality of zone conveyors in an appropriate order onto the atleast one transport conveyor to arrange the trays on the at least one transport conveyor in anappropriate order for the second sort pass.

Optionally, the step of conveying the arranged trays may include conveying thearranged trays from a discharge of the at least two article sortation assemblies to an induct ofan appropriate one of at least two buffering assemblies. The step of conveying the arrangedtrays may then include conveying the arranged trays along a generally continuous conveyorassembly positioned between the discharge of the at least two article sortation assemblies andthe at least two buffering assemblies.

According to yet another aspect of the present invention, an article sortation systemfor sorting articles to a delivery point sequence depth of sort includes at least one articlesorter, a plurality of zone conveyors and at least one transport conveyor. The at least onearticle sorter has an induct and a discharge, and is operable to sort articles into a plurality oftrays and discharge the trays of sorted articles at the discharge. The at least one transportconveyor is operable to convey trays from the discharge of the at least one article sorter to theinduct of the at least one article sorter. The plurality of zone conveyors are positioned alongthe at least one transport conveyor. The at least one transport conveyor and the plurality ofzone conveyors are cooperatively operable to arrange and accumulate trays in a sequencedmanner on the at least one transport conveyor. The at least one transport conveyor isoperable to discharge the sequenced trays to the induct of the at least one article sorter.

Preferably, the plurality of zone conveyors are positioned along at least one side ofthe at least one transport conveyor. The at least one transport conveyor may include aplurality of transfer units, where each of the plurality of transfer units is positioned at at leastone of the plurality of zone conveyors and is operable to move trays between the at least onetransport conveyor and a respective at least one of the plurality of zone conveyors.

Optionally, the at least one transport conveyor and the plurality of zone conveyors arepositioned at a height above the at least one article sorter. The article sortation system maythen include a tray elevating device between the discharge of the at least one article sorter andthe transport conveyor and a tray lowering device between the transport conveyor and theinduct of the at least one article sorter.

Optionally, the article sortation system may includes a single article sorter.Alternately, the article sortation system may include at least two article sorters.

Therefore, the present invention provides an automatic delivery point sequenceapparatus and process for sequencing flat mail. The present invention provides an automatedmeans for sorting, queuing and presenting trays of sorted articles to inducts of one or moresortation assemblies for a second sort pass of the articles. The trays may be automaticallyremoved from their respective output bins, and automatically identified and labeled so thatthe trays can be provided to the inducts in the proper order. The present invention thus savestime, improves accuracy of sorting and more fully utilizes the production capacity of the flatsorting machines, especially when two or more machines are coupled together.

These and other objects, advantages, purposes and features of this invention willbecome apparent upon review of the following specification in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an upper perspective view of a sequencing conveyor and article sortationassembly in accordance with the present invention;

FIG. 2 is an upper perspective view from an opposite end of the sequencing conveyorand article sortation assembly of FIG. 1;

FIG. 3 is a perspective view of a plurality of sorting mechanisms useful with thepresent invention;

FIG. 4 is a top plan view of the sequencing conveyor of FIGS. 1 and 2;

FIG. 5 is a side elevation of an alternate embodiment of a sequencing conveyor andarticle sortation assembly in accordance with the present invention, with conveyor rampsbeing configured to convey trays from a discharge end of the sortation assembly to an inputend of the sequencing conveyor;

FIG. 6 is a top plan view of the sequencing conveyor of FIG. 5, with portions cutaway to show the discharge end of the sortation assembly;

FIG. 7 is a perspective view of a tray handling system useful with the presentinvention;

FIG. 8 is a perspective view of the tray handling system of FIG. 7 from an oppositeend;

FIG. 9 is a top plan view of an alternate flat article sortation apparatus according tothe present invention;

FIG. 10 is a top plan view of a sequencing conveyor useful with the sortationapparatus of FIG. 9;

FIG. 11 is a perspective view taken generally from the direction XI-XI in FIG. 9;

FIG. 12 is the same view as FIG. 9 of an alternate embodiment thereof;

FIG. 13 is the same view as FIG. 9 of another alternate embodiment thereof;

FIG. 14 is the same view as FIG. 9 of yet another alternate embodiment thereof;

FIG. 15 is a top plan view of another alternate embodiment of the present invention,which utilizes multiple flat sorting machines;

FIG. 16 is an upper perspective view of another sequencing conveyor and articlesortation assembly in accordance with the present invention;

FIG. 17 is a top plan view of the sequencing conveyor and article sortation assemblyof FIG. 16;

FIG. 18 is an upper end view of the sequencing conveyor and article sortationassembly of FIGS. 16 and 17;

FIG. 19 is a lower, opposite end view of the sequencing conveyor and article sortationassembly of FIGS. 16-18;

FIG. 20 is a view along one side of the sortation assembly and beneath the sequencingconveyor of FIGS. 16-19;

FIG. 21 is a perspective view of the discharge end of the sortation assembly and theinduct end of the sequencing conveyor of FIGS. 16-20;

FIG. 22 is a flow chart of a flat mail sequencing process according to the presentinvention;

FIG. 23 is a schematic of a first sort pass of a sorting matrix useful with the presentinvention;

FIG. 24 is a schematic of a second sort pass of the sorting matrix of FIG. 23;

FIGS. 25A and 25B are schematics of a first sort pass of a sorting matrix of thepresent invention; and

FIGS. 26A and 26B are schematics of a second sort pass of the sorting matrix ofFIGS. 25A and 25B.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now specifically to the drawings and the illustrative embodiments depictedtherein, a flat article sortation apparatus orsystem 10 includes a sorter unit orassembly 12and a sort conveyor orbuffer assembly 14.Sorter unit 12 includes aninduct end 16 and anoutput or dischargeend 26 and a sortation mechanism, generally illustrated at 18.Bufferassembly 14 includes aninduct end 20 and anoutput end 22, and is cooperativelyinterconnected betweendischarge end 26 and inductend 16 ofsorter assembly 12.Bufferassembly 14 automatically arranges and conveyscontainers 25 of articles sorted by an initialsortation process ofsorter assembly 12 fromdischarge end 26 back to inductend 16 ofsorterassembly 12 in order to induct the sorted articles for further sortation bysorter assembly 12,as discussed in detail below. Accordingly,article sortation system 10 is operable to provide adelivery point or carrier route sequence depth of sort via first and second passes throughsorter units 12 and viabuffer 14, which provides trays containing sorted articles from the firstpass to theinduct end 16 of thesorter assembly 12 in a sequenced or arranged manner.

In the illustrated embodiment,sortation assembly 12 is a flat-sorting system, such asthe type manufactured and marketed by Alcatel Postal Automation System and/orMannesmann Dematic Postal Automation and/or Mannesmann Dematic Rapistan Corp.and/or Siemens Dematic Corp. under Model AFSM100.Sortation assembly 12 sorts mailreceived atinduct end 16. An OCR-Optical Character Reader, VCS-Video Coding System(OCR/VCS) attempts to resolve the address to the full 11 digit zip code during the first passon the sortingassembly 12. If the OCR/BCR (BCR-Bar Code Reader) cannot resolve theaddress to 11 digits, the VCS is used to complete the result. The address is resolved to 11digits during the first pass. This information is retained by a high level sortation computerand used during the first and second pass operations. The OCR/VCS system connects thepseudo number with the 11 digit zip code. Thesortation assembly 12 uses the 11 digit zipcode to send the mail piece to the correct output during the first pass, so that it can be fedback through the second pass to be sorted to the delivery point sequence. The mail piecemust be sorted correctly (using the 11 digit zip code) each pass to be properly sorted to thedelivery point sequence.

Sortation mechanism 18 includes a carousel (not shown) which deposits articles intoparticular chutes 24 for depositing incontainers 25 positioned under the chutes (as shown inFIG. 3). After the containers ortrays 25 are at least partially filled with articles, a trayhandling system, such astray handling system 110 of FIGS. 7 and 8, discharges the at leastpartially filled trays automatically tooutput end 26, which, in the illustrated embodiment, is a conveyor, such as a belt conveyor, powered roller conveyor, or the like. A preferred form oftray handling system 110 is disclosed in commonly assigned, U.S. pat. application, Ser. No.09/629,009, filed July 31, 2000 by Olson et al. for AUTOMATIC TRAY HANDLINGSYSTEM FOR SORTER (Attorney Docket RAP04 P-601), the disclosure of which is herebyincorporated herein by reference, and is illustrated in FIGS. 7 and 8 and discussed brieflybelow. In the illustrated embodiment, eachinduct end 16 includes threeinduct lines 16a,16b, 16c and thesorter unit 12 and tray handling system have 120 bin positions, but may beextended up to 240 bins or more, depending on the application. For a 120 bin system, thethreeinduct lines 16a, 16b, 16c may randomly feed any of three groups of 40 bins during thefirst sort pass operation. The bins may be divided so there are three groups, such as group A,having bins 1-40 of the sortation assembly, group B, having bins 41-80 of the sortationassembly, and group C, having bins 81-120 of the sortation assembly.Sortation assembly 12is preferably capable of sorting up to 10,000 pieces of flat mail per hour and, most preferably,approximately 20,000 or more pieces of flat mail per hour.

The first pass throughsortation assembly 12 is used by the system to determine theaddress information. The system must learn how many letters are to be sent to each deliverypoint. Note that this first pass preferably has the addresses resolved to the delivery pointlevel (11 digits for the U.S.). During the first pass, all of the mail destined for the firstdelivery point of each route is sent to output orbin 1, the second delivery point tooutput 2,and the third tooutput 3, and so on. The mail is inducted into the sortation assembly by allthree inducts orfeeders 16 randomly. A schematic of the first pass sortation process is showngenerally at 15A in FIG. 23.

After the first pass is concluded, the trays are then swept automatically from thesortation assembly 12 and sent to sorter conveyor orbuffer assembly 14, and then to theinduct end 16 ofsortation assembly 12, but only whensortation assembly 12 calls for eachparticular container. The trays may be swept as disclosed in U.S. pat. application, Ser. No.09/629,009, referenced above, or via other means or processes, without affecting the scope ofthe present invention. For correct delivery point sequencing,output 1 is processed beforeoutput 2, which is processed beforeoutput 3, and so on. Therefore, the trays are arranged inorder bysorter conveyor 14 for induction into the second pass ofsorter assembly 12. Duringthe second pass, mail for a first carrier route will be sent to bin oroutput 1, mail for anothercarrier route will be sent tooutput 2, and mail for yet another carrier route will be sent tooutput 3. This pass splits mail from the original output 1 (first delivery point regardless ofroute) betweenfinal outputs 1, 2, and 3. The same process is followed fororiginal outputs 2 and 3. The mail is inducted to the sortation assembly by a particular one of the inducts orfeeders which is dedicated to a particular group of 40 bins. A schematic of the second sortpass is shown generally at 15B in FIG. 24. The idea is to ensure that the delivery points inthe stackers at the end of the first pass are in separate outputs at the end of the second pass.

Alternately,sortation assembly 12 may comprise a dual carousel system, such as thesortation assembly marketed by Mannesmann Dematic Postal Automation under ModelTOP2000, the sortation assembly marketed by Lockheed Martin Postal Automation underModel FSM 1000 or any other flat mail sortation system. Details of one type of suchsortation assemblies are disclosed in French Pat. Application Nos. 9908610, filed July 5,1999 by Fabrice Darrou, Vincent Grasswill, Alain Danjaume, entitled DISPOSITIF DECONVOYAGE D'OBJETS PLATS AVEC UN SYSTEME D'AIGUILLAGE; 9909163,filed July 15, 1999 by Jean-Luc Astier, Pierre Advani, Dino Selva, entitled DISPOSITIF APLUSIEURS CONVOYEURS A GODETS SUPERPOSES POUR LE TRI D'OBJETSPLATS; and 9907316, filed June 10, 1999 by Fabrice Darrou, Vincent Grasswill, RobertVivant, entitled DISPOSITIF DE CONVOYAGE DE COURRIER AVEC DES ROUES ENMATIERE ELASTOMERE ELASTIQUEMENT DEFORMABLES; International Pat.Application published 6 July 2000 by Francois Agier et al. as International Publication No.WO 00/39010, entitled DEVICE FOR CONVEYING FLAT OBJECTS BETWEENPROCESSING EQUIPMENT ITEMS; and International Patent Application published 6 July2000 by Francois Agier et al. as International Publication No. WO 00/39012, entitledROUTING DEVICE FOR GROUPING TWO STREAMS OF FLAT OBJECTS, SUCH ASMAIL ENVELOPES, INTO ONE STREAM, the disclosures of which are herebyincorporated herein by reference. Alternately,sortation assembly 12 may use the principlesdisclosed in U.S. Pat. No. 5,718,321, the disclosure of which is hereby incorporated herein byreference, adapted to flat mail sortation capability.

In the illustrated embodiment,buffer 14 is positioned at a height abovesortationassembly 12, and thus conveys the containers ortrays 30 over top ofsort assembly 12 fromthedischarge end 26 back to theinduct end 16 of sorter assembly orunit 12. As seen in FIG.2, dischargeend 26 ofsort assembly 12 includes afirst sort discharge 26a and asecond sortdischarge 26b at each side ofsort assembly 12 for discharging the trays after respective firstand second sort passes, as discussed below. A pair of elevating or liftingdevices 28 arepositioned at thefirst sort discharge 26a at each side ofsort assembly 12. Eachtray liftingdevice 28 is operable to raisetrays 25 fromfirst sort discharge 26a upward and onto inductend 20 ofbuffer 14.Tray lifting devices 28 may be any known elevating or lifting device, such as a Vertiveyor manufactured and marketed by Vertical Systems, Inc. of Walton,Kentucky, or a Mechanical Vertical Lift manufactured and marketed by P-flow VerticalMaterial Handling Systems of Milwaukee, Wisconsin, or any other known vertical conveyingor lifting device, without affecting the scope of the present invention. Optionally, asdiscussed below, thevertical lifting device 28 may comprise a ramped conveyor or any othermeans of elevating trays fromfirst sort discharge 26a ontoinduct end 20, as discussed below.

Likewise, one or moretray lowering devices 30 may be positioned at the dischargeend 22 ofbuffer 14, to lower the sorted or sequenced trays fromdischarge end 22 ofbuffer14 to theinduct end 16 ofarticle sort assembly 12. In the illustrated embodiment, threeloweringdevices 30a, 30b, 30c are operable to lower trays from a respective one of threeoutput conveyors 22a, 22b, 22c ofbuffer 14 to a respective one of threeinduct stations 16a,16b, 16c ofsort assembly 12, as discussed below. Similar to elevatingdevices 28, loweringdevices 30 may be any known vertical lowering device or may be a ramped conveyingsurface or the like, without affecting the scope of the present invention. Although shown anddescribed as being positioned generally abovesort assembly 12, it is further envisioned thatthe sort conveyor or buffer of the present invention may otherwise be positioned elsewhere,such as alongsidesort assembly 12, without affecting the scope of the present invention.Although shown and described as having three output conveying paths to three inducts,clearly, the buffer of the present invention may be adapted to sorter units having less than ormore than three inducts, without affecting the scope of the present invention.

As best shown in FIG. 4,buffer 14 includes a plurality ofconveyors 32 positionedside by side one another along at least a portion ofbuffer 14 and betweeninput end 20 anddischarge end 22 ofbuffer 14.Conveyors 32 are preferably powered roller conveyors and areoperable to convey the sorted trays along the conveying portions in a selected direction.However, other conveying surfaces may be utilized, such as a belt conveying surface or thelike, without affecting the scope of the present invention. A plurality of 90 degree transfersor pop-upbelt transfer units 34 are preferably positioned at each end of each of the pluralityofconveyors 32 to change the direction of conveyance of the trays as they are conveyedalongconveyors 32, as discussed in detail below. Such transfer units are commerciallyavailable and known in the art, such that a detailed discussion will not be included herein.Briefly,transfer units 34 are operable to convey a tray in a direction along the conveyor atwhich they are positioned, and may be operable to raise one or more belt conveyor strips orthe like to convey a tray positioned at the transfer unit in a direction which is generallytransverse or normal to the conveyor direction.

Conveyors 32 include afeed conveyor portion 32a and an accumulating orcyclingconveyor portion 32b. In the illustrated embodiment,conveyor portions 32a, 32b providethree conveying paths from induct end 20 to a respective one ofoutput conveyors 22a, 22b,22c atoutput end 22, as discussed below. Induct end 20 ofbuffer 14 includes a pair ofinduction conveyors 20a at thetray lifting devices 28 at either side ofbuffer 14.Inductionconveyors 20a extend acrossbuffer 14 and are interconnected by a plurality ofsecondinduction conveyors 20b and 90degree transfer units 39.Induction conveyors 20a areoperable to convey the trays inducted via thevertical lifting devices 28 acrossbuffer 14 toalign each tray with an appropriate one of the threeinduct conveyors 20b, which aregenerally aligned with a respective or corresponding one of thefeed conveying portions 32aofbuffer 14. The 90 degree or pop-up transfer units 39 are positioned along the crossinduction conveying portions 20a and function to convey the trays across theinductionconveyors 20a or change the direction of conveyance of the trays onto an appropriatesecondinduction conveyor 20b and toward the appropriatefeed conveying portion 32a, as discussedbelow. Athird cross conveyor 20c may extend acrossbuffer 14 at an upstream end offeedconveying portions 32a to facilitate additional movement of trays across thebuffer 14 and/orto facilitate operation of a larger sort loop, as discussed below. Providing separatecrossconveying portions 20a facilitates generally continuous flow of trays from both sides ofsorterunit 12 onto both sides ofinduct end 20 and onto and along the appropriate conveying path ofbuffer assembly 14, as also discussed in detail below.

Each conveying path ofbuffer 14 has one of thefeed conveyor portions 32aconnected to a corresponding one of theinduct conveyors 20b, preferably via atransfer unit39a. Thefeed conveyor 32a then conveys or feeds the trays from induct end 20 onto arespective one of the accumulatingconveyor portions 32b via atransfer unit 34a. Eachconveying path of accumulatingconveyor portion 32b further includes a first,input conveyor33a and a second, return or accumulatingconveyor 33b, which conveys the trays in anopposite direction from theinput conveyor 33a. A pair oftransfer units 34b, 34c and 34d,34a are positioned at opposite ends of accumulatingconveyor portions 32b, such that thetrays may be conveyed in a generally continuous loop aroundinput conveyor 33a andaccumulatingconveyor 33b via 90degree transfer units 34a, 34b, 34c, 34d. Moreparticularly,transfer unit 34a is positioned at an upstream end ofinput conveyor 33a and isoperable to convey trays fromfeed conveyor 32a ontoinput conveyor 33a or to transfer traysfromtransfer unit 34d ontoinput conveyor 33a. Additionally,transfer unit 34b is positionedat a downstream end ofinput conveyor 33a and is operable either to change the direction of or transfer the tray being conveyed alonginput conveyor 33a to thetransfer unit 34c at anupstream end of the accumulatingconveyor 33b, or to discharge the tray frominput conveyor33a onto a respective one of the output or take-awayconveyors 22a, 22b, 22c atdischargeend 22 ofbuffer 14. Thetransfer units 34c, 34d at opposite ends of the second accumulatingconveyor 33b function to change the direction of travel of the trays at each end.

Buffer 14 is operable to convey the trays in a generally continuous loop viatransferunit 34a, first accumulatingconveyor 33a,transfer units 34b, 34c, second accumulatingconveyor 33b andtransfer unit 34d. The trays are cycled or circulated in the loop while newtrays are input into the loop at appropriate spaces between the trays being cycled. After thetrays are sorted and positioned in a sequenced manner along accumulatingconveyor portion32b, the trays are continuously transferred fromtransfer unit 34b onto theappropriatedischarge conveyor 22a, 22b or 22c. The discharge or take-awayconveyors 22a, 22b, 22cconvey the sorted trays from the accumulatingportion 32b to thevertical lowering devices 30at the discharge end 22 ofbuffer 14.

Accordingly,buffer 14 receives trays from thevertical lifting devices 28 and arrangesthe trays onto appropriate feed andaccumulation conveyor portions 32a, 32b, depending onthe particular sortation station at which the articles were input into the particular trays.Preferably, each of the three feed and accumulatingconveyor portions 32a, 32b alongbuffer14 are associated with a particular set or group of sortation stations of thesortationmechanism 18. For example, because each of theinduct lines 16a, 16b, 16c is associatedwith and sorts articles for 40 of the 120 tray positions or sortation stations ofsorter unit 12,the trays associated with a particular group or set of 40 of the sortation stations are conveyedto an appropriate path defined by one of the feed and accumulating conveyingportions 32a,32b and further conveyed onto theappropriate output 22a, 22b, 22c and loweringdevice 30a,30b, 30c to provide the appropriate trays in an arranged or sequenced manner at thecorresponding induct station 16a, 16b or 16c for a second pass or sort of the articles. Thisallows the articles within the containers after the first sortation pass to be re-input or re-inductedinto an appropriate induct station and in an appropriate sequence for a secondsortation process to achieve a delivery point sequence depth of sort of the articles.

During operation, articles are originally input atinduct stations 16a, 16b and 16c ofsort assembly 12 in a random manner. The articles are sorted during the first pass anddischarged into containers positioned at the appropriate sortation station or bin position viathe carousel and chutes ofsort assembly 12. When the trays become filled or at least partiallyfilled, they are discharged from their sortation station and conveyed toward discharge end 26 ofsort assembly 12. The trays are preferably discharged from the sortation stations andconveyed alongsort assembly 12 via the tray handling system such as discussed in detailedbelow with respect totray handling system 110. In the illustrated embodiment of FIGS. 1and 2, the filled or at least partially filled trays are conveyed along the conveying paths of thetray handling system to alabeler station 41, whereby the trays are identified and labeled priorto being discharged either atfirst sort discharge 26a to vertical conveyingdevices 28 after thefirst sort pass, or atsecond sort discharge 26b to the takeaway conveyor or device after thesecond sort pass ofsort assembly 12.

After a first sort pass ofsort assembly 12, the identified containers or trays aredischarged atfirst sort discharge 26a and lifted upward by liftingdevice 28 onto induct end20 ofbuffer 14. Each of the trays provided atinduct end 20 are then conveyed across theirrespective crossinduction conveying portion 20a until they are aligned with an appropriateone of thesecond induction conveyors 20b andfeed conveyors 32a corresponding to theirrespective set of initial sortation stations of thesort assembly 12. The trays are thenconveyed onto and along theappropriate feed conveyor 32a toward the correspondingaccumulating conveyingportion 32b. As trays are initially received by the accumulatingconveyor portion 32b, the trays are cycled or circulated around a generally continuous loopvia conveyance along theinput conveying portion 33a and thereturn conveying portion 33band pop-up transfer units 34b and 34c, as indicated by the arrows in FIG. 4. The trays mayinitially come to rest at adownstream end 33c ofreturn conveying portion 33b to temporarilyaccumulate and/or buffer the trays being sorted and conveyed alongbuffer 14. The trays mayremain at thedownstream end 33c or elsewhere along accumulating conveyingportion 32buntil a new tray arrives at therespective feed conveyor 32a, whereby the trays are againcycled or circulated around the loop.

In order to properly sequence or arrange the trays for the second sortation passthroughsort assembly 12, as additional trays are provided alongfeed conveyor portion 32a,the trays accumulated along second accumulatingconveyor 33b are cycled or conveyedaround the generally continuous loop via thetransfer units 34a-d and theconveyors 33a, 33bof accumulatingconveyor portion 32b. As the trays are conveyed from accumulatingend33c acrosstransfer units 34d, 34a and onto first accumulatingconveyor 33a, one or more ofthe trays being conveyed alongfeed conveyor 32a may be inducted into the loop of trays viatransfer unit 34a at an appropriate space between adjacent or consecutive trays being cycled,such that the trays are sorted into the proper order or sequence as additional trays areprovided frominduct end 20 ofbuffer 14.

As additional trays are received and conveyed alongfeed conveyor 32a, the trays andthe accumulatingconveyor portions 32b may be generally continuously recirculated aroundthe continuous loop, whereby the trays alongfeed conveying portions 32a are individuallyinducted onto accumulatingconveyor portion 32b in the appropriate places between thecirculating trays. This process continues until a sweep process is performed at thesortationunit 12 andtray handling system 110, whereby all of the filled or at least partially filled traysare removed from thesorter unit 12 and provided to theinduct end 20 ofbuffer 14. The traysat accumulating conveyingportion 32b are then circulated while the swept trays areindividually input into the loop at their appropriate location relative to the other trays. Oncethe trays are fully sorted and accumulated at accumulatingportion 32b ofconveyors 32, thetrays are conveyed and discharged along a respective one of thedischarge conveyors 22a,22b, 22c viatransfer units 34b and then lowered to theappropriate induct station 16a, 16b or16c via therespective lowering device 30a, 30b, 30c. The articles are then input intosorterunit 12 for a second sortation process or pass ofsorter unit 12 to sort the articles to thedelivery point sequence depth of sort. As the articles are sorted for the second time, they areagain discharged into the trays orcontainers 25 viachutes 24, whereby the containers areagain discharged from the sortation stations and conveyed along their conveying paths via thetray handling system. The trays are then identified at thescanning station 41 and dischargedto the take-away conveyor or device atsecond sort discharge 26b.

Flat articles that have been sorted to delivery point sequence bysortation system 10may be dispatched to a transportation system utilizing the DISPATCH SYSTEM FORCONTAINERS OF SORTED MAIL AND METHOD THEREFOR disclosed in U.S. pat.application, Ser. No. 09/600,204, filed July 12, 2000 (Attorney Docket RAP04 P-571A) asthe U.S. national phase application for International Application, Ser. No. PCT/EP99/00317,filed Jan. 21, 1999, claiming priority from U.S. provisional pat. application, Ser. No.60/072,032, filed Jan. 21, 1998, the disclosures of which are hereby incorporated herein byreference.Sortation system 10 may also utilize the principles of DOCK-TO-DOCKRECEIVING AND DISPENSING FOR A POSTAL PROCESSING CENTER disclosed incommonly assigned International Application, Ser. No. PCT/EP00/04283, filed May 10, 2000and published Nov. 16, 2000 as International Publication No. WO 00/67922, claimingpriority on U.S. provisional pat. application, Ser. No. 60/133,413, filed May 11, 1999(Attorney Docket RAP04 P-582), the disclosures of which are hereby incorporated herein byreference.

Although shown and described as having the cycling and accumulatingconveyorportion 32b separate and downstream from thefeed conveyor portion 32a, clearly, thefeedconveyor portion 32a may be combined with the sorting and accumulating conveyingportion32b, such that a larger continuous loop may be defined by the conveying portions, in order toaccommodate additional trays on the sorting conveyor of the present invention.Transfer unit34d then functions to convey trays in the same direction from accumulatingconveyor 33bonto a third accumulatingconveyor 33d alongsidefeed conveyor 32a, while atransfer unit34e is positioned at a downstream end of third accumulatingconveyor 33d and function inthe same manner astransfer unit 34d, as discussed above with respect to the smallercontinuous loop ofsortation station 10. The trays inducted atinduct end 16 are then inputinto the appropriate space between trays conveyed around the larger continuous loop attransfer unit 39a at the upstream end of thefeed conveyor 32a.

Referring now to FIGS. 5 and 6, an alternate embodiment of an article sortationsystem 10' in accordance with the present invention includes sorter unit or sort assembly 12and a sort conveyor or buffer 14' positioned generally abovesorter unit 12. As discussedabove, sortassembly 12 includesinduct stations 16a, 16b, 16c, anddischarges 26a, 26b.Buffer 14' is generally similar to buffer 14, discussed above, and includes an input or inductend 20', three sort paths defined by afeed conveyor portion 32a' and an accumulatingconveyor portion 32b', and adischarge end 22, which further includes threetray loweringdevices 30a, 30b, 30c for lowering the trays frommultiple discharge conveyors 22a, 22b, 22cto one ofinduct stations 16a, 16b, 16c, in the same manner as discussed above with respect toarticle sortation system 10.

As best seen in FIG. 5,discharge 26a ofsort assembly 12 is connected to a verticallifting or conveying device 28', which comprises a ramped or inclined conveying surfacewhich is operable to convey articles upward and along the conveying surface fromdischarge26a ontocross induction conveyors 20a atinduct end 20 of buffer 14', similar to theverticallifting devices 28 ofsortation system 10, discussed above. Because the inclined ramps 28'extend further from thedischarge 26a ofsortation assembly 12, buffer 14' extends furtheralongabove sort assembly 12 thanbuffer 14, discussed above. However, buffer 14' isotherwise generally identical to buffer 14, discussed above, such that a detailed discussion ofthe sorter conveyor will not be repeated herein.

Prior to discharging the containers after the first sortation pass onto the inclinedconveying surface of inclined conveyor 28',discharge 26a ofsort assembly 12 may furtherinclude a rotator orrotating device 42, which is operable to rotate the trays or containers for proper orientation with respect to the inclined conveying surface. Preferably, the trays arerotated at rotatingdevice 42 so they are conveyed lengthwise upward and along inclinedconveyor 28'. The trays are then conveyed up the inclined conveying surface and ontocrossinduction conveyors 20a, where they are conveyed acrossinduct end 20 of buffer 14' and intoalignment with the appropriatefeed conveyor portion 32a' and accumulating conveyingportion 32b' of buffer 14', in the same manner as discussed above with respect to buffer 14.The inclined conveyors 28' may comprise any conveying means, such as powered rollerconveyors, belt conveyors or the like, and may include means for limiting slippage of thetrays as they are conveyed upward, such as ridges, platforms or the like, which move along orwith the conveying surface to support the trays as they are conveyed therealong, withoutaffecting the scope of the present invention.

Optionally, other buffering assemblies may be implemented to buffer or temporarilystore trays or containers between sort passes of one or more sorter units, in order to providethe trays for the second sort pass in a sequenced or arranged manner. For example, a verticalcarousel buffer or a horizontal carousel buffer may be implemented between the discharge ofat least one sorter unit and an induct of the sorter unit or another sorter unit, without affectingthe scope of the present invention.

Therefore, the present invention provides an article sortation apparatus or systemwhich is operable to automatically arrange or sequence trays of sorted material to anappropriate order or sequence for re-induction into the sorter unit for a second sortationprocess or sort pass, in order to achieve a delivery point sequence depth of sort of the articles.The present invention provides a buffer assembly which functions as a random accessaccumulator and temporarily stores or accumulates trays and facilitates providing the trays toan induct of a sorter in an arranged or sequenced manner. Preferably, the buffer functions tocycle or circulate trays containing the sorted articles in a generally continuous loop, whileadditional trays are input into appropriate spaces between the trays being cycled until thetrays cycled and accumulated on the sorter conveyor or buffer are in the proper order orsequence. The trays are then automatically conveyed to the appropriate induct station of thesorter unit, whereby the articles are re-inducted into the sorter unit for the second sortationprocess. Accordingly, trays discharged from the sortation unit following the second sortprocess contain articles which have been twice sorted and are thus sorted to a delivery pointsequence or carrier walk sequence.

An example of a tray handling system ortray management system 110 that is usefulwith the present invention is illustrated in FIGS. 7 and 8 and disclosed in commonly assigned U.S. pat. application, Ser. No. 09/629,009, filed July 31, 2000 by Olson et al. forAUTOMATIC TRAY HANDLING SYSTEM FOR SORTER (Attorney Docket RAP04 P-601),which is hereby incorporated herein by reference. However, other tray managementsystems, including ones that are manual or semi-automatic, can be used, without affecting thescope of the present invention. For example, an automatic tray handling system whichautomatically destacks and loads empty trays onto a conveyor to provide empty trays to thesorter unit or units may be implemented with the delivery point sequencing sortation systemof the present invention. Such a tray handling system is disclosed in commonly assignedU.S. provisional application, Ser. No. 60/275,789, filed Mar. 14, 2001 by Schiesser et al. forTRAY DESTACKER (Attorney Docket RAP04 P-624), U.S. Provisional Application, Ser.No. 60/297,516, filed June 12, 2001 by Schiesser et al. for TRAY DESTACKER (AttorneyDocket RAP04 P-624A), and U.S. pat. application, Ser. No.          filed          by Schiesser et al. for TRAY DESTACKER (Attorney Docket RAP04 P-624B), which are allhereby incorporated herein by reference.

Automatictray handling system 110 includes a plurality of conveyingsurfaces 116,which are operable to move thetrays 25 along one or both sides of the sorter unit or sortassembly 12. A plurality oftray moving devices 120 are operable at respective sorter stationsofsort assembly 12 to pull empty trays onto atray support 172, which supports the emptytray while the sort assembly discharges sorted mail into the tray. After the tray is at leastpartially filled by the sort assembly, thetray moving device 120 is then operable to move theat least partially filled tray back onto the conveying surface. A continuous supply of emptytrays is provided to thesort assembly 12, and filled or at least partially filled trays areautomatically discharged from the sorter units onto the conveyingsurface 116.

Aninput end 111a (FIG. 8) oftray handling system 110 preferably provides one ormore tray inductstations 138 and 140 for loading or inducting empty trays onto the trayhandling system, while adischarge end 111b (FIG. 7) oftray handling system 110 provides adownstream operation, such as alabeling station 122, which is operable to label the trays asthey are discharged fromtray handling system 110 tooutput 26. As can be seen in FIG. 2and discussed above, the discharge end 11b may provide afirst pass discharge 26a to theinduct 20 of the sequencing conveyor of buffer or sequencingassembly 14, and asecond passdischarge 26b, which discharges trays to a discharge or take-away conveyor or device (notshown) after the articles have been sorted to the delivery point sequencing depth of sort. Thesorter unit 12 may each be arranged in a pair of rows, and the conveyingsurfaces 116 ofautomatictray handling system 110 may extend around both sides of the rows ofsorter unit 12. However, thetray handling system 110 could be used with a single side of a mailsortation system which has one or more rows of sorter units.Empty trays 25 are movable ina continuous loop via conveyingsurfaces 116 and a pair of vertical tray moving ortray returndevices 118 at one end of the tray handling system.

Conveyingsurface 116 includes a plurality of conveying surfaces. More particularly,conveyingsurface 116 preferably includes a pair of oppositeupper conveyors 124 and 126, apair of oppositelower conveyors 128 and 130 and a pair of tray moving or return devices,such as inclined or connecting surfaces orramps 132 and 134, which are operable to moveempty trays fromlower conveyor 128 toupper conveyor 126 and fromlower conveyor 130 toupper conveyor 124, respectively, atinput end 111a. A pop-up transfer unit or 90degreetransfer unit 136 is positioned at each end of the incline ramps 132 and 134 to change thedirection of travel of thetrays 30 as they move from one of the lower conveyors to therespective incline ramp, and from the incline ramp to the respective upper conveyor.Transfer units 136 are operable to convey a tray in a direction along the conveyor at whichthey are positioned, and may be operable to raise one or more belt conveyor strips to conveya tray positioned at the transfer unit in a direction which is generally transverse or normal tothe conveyor direction, similar to transferunits 34 and 39, discussed above.

Incline ramp 132 is connected between a pair of 90degree transfer units 136a and136b at adownstream end 128b oflower conveyor 128 and anupstream end 126a ofupperconveyor 126, respectively. Similarly,incline ramp 134 is connected between a pair of 90degree transfer units 136c and 136d at adownstream end 130b oflower conveyor 130 and anupstream end 124a ofupper conveyor 124, respectively.

Lower conveyors 128 and 130 are preferably operable in a reverse direction fromupper conveyors 124 and 126, to return the empty trays back towardinput end 111a. The 90degree transfer units 136a and 136c are positioned atdownstream ends 128a and 130a ofconveyors 128 and 130, respectively, to move the empty trays onto the respective inclineramps 132 and 134 to transport the trays to theupper conveyors 124 and 126, respectively, atthe other side of thesortation system 12. In order to provide a continuous loop for the emptytrays about the conveyor surfaces 116, verticaltray moving devices 118 are positioned atdownstream ends 124b, 126b ofupper conveyors 124, 126 andupstream ends 128a, 130a oflower conveyors 128, 130. Each verticaltray moving device 118 is operable to move anempty tray from the respectiveupper conveyor 124, 126, lower the tray to the level of thelower conveyors 128, 130, and then move the tray onto the respectivelower conveyor 128,130.

Tray inductstations 138 and 140 are preferably positioned side by side one another.Preferably, tray inductstations 138 and 140 preferably include belt conveyors, which areoperable to transport or convey an empty tray onto a corresponding 90degree transfer unit136a and 136d, respectively. Empty trays may be manually loaded onto the induct stations toinduct the empty trays into theconveyor system 116 of the automatictray handling system110 or may be automatically fed from atray return conveyor 125a, 125b. Preferably,trayinduct station 140 includes an inclined belt conveyor, such that aninput end 138a and 140a ofeach of theinduct stations 138 and 140, respectively, is positioned at substantially the samelevel for easy access and loading of empty trays onto theinduct stations 138 and 140.

Trays 25 are conveyed along upper conveyingsurfaces 124 and 126 towarddownstream ends 124b and 126b, respectively. Verticaltray moving devices 118 arepositioned near or at the downstream ends 124b and 126b to remove empty trays from theupper conveyors and move the empty trays onto anupstream end 128a and 130a of thelowerconveyors 128 and 130, respectively, as discussed in detail below.Labeling stations 122 maybe positioned at or near adischarge end 124c and 126c ofupper conveyors 124 and 126,respectively, and are operable to label the filled trays as they are conveyed towardoutput 26of automatictray handling system 110. Optionally, one or both of the upper conveyorsurfaces included acurved section 127, such that the discharge ends 124c and 126c ofupperconveyors 124 and 126, respectively, may be in close proximity, in order to reduce themanual labor of the system. However, as shown in FIG. 2, the discharge ends of the upperconveyors may be positioned at opposite sides ofsort assembly 12 for discharge of trays ontorespective vertical tray lifting devices or the like. Ascanner 146 may be positioned atoutputend 26 to verify the information contained on the label applied to the trays. A pair ofrejectconveyors 148 and 150 may be provided adjacent to discharge ends 124c and 126c,respectively, to allow incorrectly labeled trays to be discharged to a separate area viarespective 90degree transfer units 136e and 136f and rejectconveyors 148 and 150.

Referring now to FIGS. 9-11, an article sortation apparatus orsystem 210 includesprimary sort assemblies 212a and 212b and a delivery point sequence (dps)sort assembly213, which is connected to sortassemblies 212a, 212b by respective sequencing or sortingconveyors or buffer assemblies, shown generally at 214 in FIG. 9. Such an arrangement ofsortation assemblies is disclosed in commonly assigned U.S. pat. application, Ser. No.09/629,007, filed July 31, 2000 for DELIVERY POINT SEQUENCING MAIL SORTINGSYSTEM WITH FLAT MAIL CAPABILITY (Attorney Docket RAP04 P-613), whichclaims priority on U.S. provisional application, Ser. No. 60/146,689, filed Aug. 2, 1999, and in U.S. provisional applications, Ser. No. 60/289,329, filed May 7, 2001 (Attorney DocketRAP04 P-613A); Ser. No. 60/302,527, filed June 29, 2001 (Attorney Docket RAP04 P-629A);and Ser. No. 60/328,160, filed Oct. 10, 2001 (Attorney Docket RAP04 P-629B),which are all hereby incorporated herein by reference. Eachsort assembly 212a, 212bincludes aninduct 216 and a sortation mechanism generally illustrated at 218.Sort assembly213 includes aninduct 217 and asortation mechanism 219. Induct 217 preferably includesfour feeder conveyors or spurs 238 with a tray unloader (not shown) at eachinduct station239 at eachspur 238.Buffer assemblies 214interconnect outputs 226 ofsortation assemblies212a, 212b withinduct 217 ofsortation assembly 213 via one or more transfer switches 236and spurs 238. The purpose ofbuffer assemblies 214 is to automatically arrange and conveycontainers of articles sorted byinitial sortation assemblies 212a, 212b fromdischarge 226 ofsort assemblies 212a, 212b to induct 217 ofsort assembly 213, in order to induct the sortedarticles for further sortation bysubsequent sortation assembly 213, similar to buffer 14,discussed above.

Similar to sortassembly 12 discussed above,sort assemblies 212a and 212b areoperable to sort articles or mail received atinduct 216. Thesort assemblies 212a, 212b maybe any known sortation unit or system, such as the flat sorting system marketed by AlcatelPostal Automation System, Mannesmann Dematic Postal Automation, Mannesmann DematicRapistan Corporation, Solystic and/or Siemens Dematic Corp. under Model AFSM100 or thelike. Clearly,sort assemblies 212a, 212b may otherwise be any other sortation assembly,such as the sortation assembly marketed by Lockheed Martin Postal Automation under ModelFSM 1000 or any other flat mail sortation system, without affecting the scope of the presentinvention. The sortation assemblies may even be a dual carousel system, such as thesortation assembly marketed by Mannesmann Dematic Postal Automation, Solystic and/orSiemens Dematic Corp. under Model TOP2000.

Sort assemblies 212a, 212b are operable to resolve the address of the mail to elevendigits during the sortation process. Also, similar to sortassembly 12, discussed above, traysare discharged in a generally random manner fromsort assembly 212a, 212b atdischarge end226 ofsort assembly 212a, 212b. The trays are then conveyed along conveyingportions 227and onto aninduct end 220 of buffer 214 (FIG. 10), where the trays are arranged or sortedprior to induction into thesecond sorter unit 213 in a manner similar to that discussed abovewith respect tosortation apparatus 10.

Preferably, sort assembly 213 is capable of sorting up to 20,000 flat articles per hourand, most preferably, up to approximately 40,000 flat articles per hour, or more. Preferably, sort assembly 213 has a sort rate that is approximately double the sort rate of eachsortassembly 212a, 212b for reasons that are set forth in more detail below. For example, in theillustrated embodiment, sort assembly 213 is a dual-carousel system having 300 or more binsmarketed by Mannesmann Dematic Postal Automation under Model TOP2000. Mail can besorted to each of the bins from either of the dual carousels as fed by each of thespurs 238 andthe dual induct lines 234. Details ofsort assembly 213 of the illustrated embodiment aredisclosed in French Pat. Application Nos. 9908610, filed July 5, 1999 by Fabrice Darrou,Vincent Grasswill, Alain Danjaume, entitled DISPOSITIF DE CONVOYAGE D'OBJETSPLATS AVEC UN SYSTEME D'AIGUILLAGE; 9909163, filed July 15, 1999 by Jean-LucAstier, Pierre Advani, Dino Selva, entitled DISPOSITIF A PLUSIEURS CONVOYEURS AGODETS SUPERPOSES POUR LE TRI D'OBJETS PLATS; and 9907316, filed June 10,1999 by Fabrice Darrou, Vincent Grasswill, Robert Vivant, entitled DISPOSITIF DECONVOYAGE DE COURRIER AVEC DES ROUES EN MATIERE ELASTOMEREELASTIQUEMENT DEFORMABLES; Published International Pat. Application WO00/39010, published 6 July 2000 by Francois Agier et al., entitled DEVICE FORCONVEYING FLAT OBJECTS BETWEEN PROCESSING EQUIPMENT ITEMS; andPublished International Patent Application WO 00/39012, published 6 July 2000 by FrancoisAgier et al., entitled ROUTING DEVICE FOR GROUPING TWO STREAMS OF FLATOBJECTS, SUCH AS MAIL ENVELOPES, INTO ONE STREAM, the disclosures of whichare hereby incorporated herein by reference. Alternately, sort assembly 213 may use theprinciples disclosed in U.S. Pat. No. 5,718,321 adapted to flat mail sortation capability, thedisclosure of which is incorporated herein by reference. Atray return conveyor 225a, 225breturns empty trays from thedps sortation assembly 213 to a respectiveprimary sortassembly 212a, 212b, while full trays containing sorted mail are discharged to a takeawayconveyor or the like (not shown), or to a return orloop conveyor 229, as discussed in detailbelow.

As containers or trays are dispatched fromsort assemblies 212a and 212b accordingto the sort plan, they are buffered, sorted and discharged bybuffer 214 towardinduct 217 ofsortation assembly 213. As shown in FIG. 10,buffer 214 may be substantially similar tobuffer 14, discussed above, and may include one or more circulating and accumulatingconveying portions orloops 232b for circulating trays therearound. Alternately, the bufferassembly may include a vertical carousel buffer or a horizontal carousel buffer or otherbuffering assemblies or systems, without affecting the scope of the present invention.

Becausebuffer 214 is substantially similar to buffer 14, discussed above, a detaileddescription of the buffer will not be repeated herein. Suffice it to say that the trays arecirculated and sorted about one or more continuous loops at accumulating conveyingportions232b ofbuffer 214 until all of the trays have been swept from thesorter units 212a, 212b andinducted intobuffer 214. The trays are then discharged from accumulating conveyingportion232b onto a single discharge conveyor or onto two or more discharge conveyors, such as twodischarge conveyors 222a and 222b, for conveying trays toward the induct ofsortationassembly 213. Each loop of accumulating conveyingportion 232b may sequentiallydischarge all of its trays in order ontodischarge conveyors 222a and/or 222b, such that all ofthe ordered or sequenced trays from one loop are discharged first, all the trays from anotherloop are discharged second and so on. In the illustrated embodiment with three loops andtwo discharge conveyors, all of the trays from one loop may be discharged onto onedischarge conveyor 222a, all of the trays from another loop may be discharged onto theotherdischarge conveyor 222b, and the trays from the third loop may be split, with a portion of thetrays being discharged in an appropriate sequence or order on each of thedischargeconveyors 222a, 222b before or after the other trays from the other loops. The trays may thenbe conveyed alongdischarge conveyors 222a, 222b toward a series of transfer switches 236.

Transfer switches 236 selectively transfer the trays or containers ontospurs 238leading to induct 217 viainduct stations 239. Transfer switches 236 are operated incoordination with the overall sortation plan in order to stage the containers atinduct stations239 in a sequence called for bysortation assembly 213. Optionally,other transfer switches237a may discharge trays frombuffer 214 onto a return orloop conveyor 229, which conveysthe sorted or sequenced trays back to theinduct 216 ofsorter units 212a, 212b for a secondsort pass throughsorter units 212a, 212b. In the illustrated embodiment, returnconveyor 229conveys trays fromtransfer switches 237a to transferswitches 237d and further towardinduct216 ofsorter units 212a, 212b. Such a return conveyor facilitates two or more sort passesthrough thefirst sorter units 212a, 212b and/or one or more sort passes through thefirst sorterunits 212a, 212b, followed by a sort pass through thesecond sorter unit 213.

Optionally, returnconveyor 229 may also or otherwise be connected between transferswitches 237c at the discharge ofsorter unit 213 and transferswitches 237b at theinduct end227 ofbuffers 214, in order to facilitate multiple sort passes of thesorter unit 213 to furthersort and consolidate the sorted mail. Although shown as having a buffer at the discharge endof eachsorter unit 212a, 212b, optionally, or additionally, a single buffer assembly may bepositioned between the discharge of each of thesorter units 212a, 212b and 213 and the induct to each of thesorter units 212a, 212b and 213, in order to facilitate multiple sort passesthrough one or more of thesorter units 212a, 212b, 213, without affecting the scope of thepresent invention.

Thebuffers 214 and/or thereturn conveyor 229 may be elevated above the level ofsorter units 212a, 212b, such that one or moretray lowering devices 230 may be positioned atinducts 216 ofsorter units 212a, 212b to lower the trays fromreturn conveyors 229 to inducts216, similar totray lowering devices 30, discussed above. Additionally, one or moretrayraising devices 228 may be positioned at the discharge ofsorter unit 213 to raise the traysupward ontoreturn conveyor 229 via transfer switches 237c. However, clearly, buffers 214and/or returnconveyors 229 may be positioned elsewhere or at the same level ofsorter units212a, 212b, 213, such that the tray raising and/or lowering devices are not required, withoutaffecting the scope of the present invention. As discussed above with respect to tray raisingand loweringdevices 28, 30, the tray raising and loweringdevices 228, 230 may alternatelycomprise inclined or ramped conveyors or the like, depending on the application.

Accordingly, returnconveyor 229 may convey full or at least partially filled traysbeing discharged fromsorter unit 213 tobuffers 214 viatray raising devices 228, and transferswitches 237c, 237b. The partially filled and sorted trays may then be inducted tosorter unit213 for a second sort pass therethrough. Additionally, return orloop conveyor 229 mayconvey at least partially filled trays frombuffers 214 to theinduction 216 ofsorter units212a, 212b viatransfer switches 237a andtray lowering devices 230. The at least partiallyfilled trays from eithersorter units 212a, 212b and/orsorter unit 213 may thus be sorted andsequenced bybuffers 214 and then inducted into one of thesorter units 212a, 212b or 213 foran additional sort pass, depending on the application. This allows for multiple sort passesthrough one of the sorter units or through a combination of two or more of the sorter units, inorder to automatically further sort the mail after a first sort pass through one ofsorter units212a, 212b or evensorter unit 213.

In the illustrated embodiment of FIG. 9, the first passprimary sortation assembly212a, 212b is used by the system to determine the address information. The systemdetermines how many letters are to be sent to each delivery point. The first machine, inaddition to discovering address and mail piece information, starts the sorting process. Notethat the address is resolved to the delivery point level (11 digits for the U.S.) for the first pass.During the first pass, all of the mail destined for the first delivery point of each route is senttooutput 1, the second delivery point tooutput 2, and the third tooutput 3, etc. After the firstpass is concluded, the trays are then swept automatically from thesort assembly 212a, 212b and sent to sort assembly 213 viabuffer 214, but only when sort assembly 213 calls for eachparticular container. For correct delivery point sequencing,output 1 is processed beforeoutput 2, which is processed beforeoutput 3, and so on. Therefore, the trays are arranged inorder bybuffer 214 for induction intosecond sorter assembly 213. During this second pass,mail for a first carrier route is sent tooutput 1, mail for another carrier route is sent tooutput2, and mail for yet another carrier route is sent tooutput 3, and so on. This pass splits mailfrom the original output 1 (first delivery point regardless of route) betweenfinal outputs 1, 2,and 3. The same process is followed fororiginal outputs 2 and 3. The idea is to ensure thatthe delivery points in the stackers at the end of the first pass are in separate outputs at the endof the second pass.

As would be apparent to the skilled artisan,article sortation system 210 is capable ofsorting turnaround mail, which is mail collected in a local area in whichsortation system 210is located, and sorting the mail to the delivery point sequence at the output ofsort assembly213. Additionally, mail received in the mail preparation area may be placed in one or morecompartments intrays 25 and conveyed in the rigid plastic containers ortrays 25 to theinducts 216 ofsort assemblies 212a, 212b for an initial sort pass of the mail through the sortunits or assemblies.

Each piece of mail is identified efficiently (to 11 digits) on the first pass, such as byusing OCR/VCS and a spray-on PSEUDO ID# (or other means of application as may bemore technically prudent, such as a printed and applied label, an RF tag, or the like). Each ofthesort assemblies 212a, 212b sorts the mail in an efficiently balanced throughput scenario ofapproximately 17,000 pieces/hr (in balance with spray-on system and OCR/VCS delay).Buffer 214 then automatically arranges or sorts or sequences the containers into anappropriate order or sequence for induction into thesecond sorter 213 for the second sort passof the articles or back to thefirst sorter units 212a, 212b viareturn conveyors 229 for asecond pass therethrough. The product can now be called for in sequence (and processed) ata higher speed in the second pass (40,000 pieces/ hr). This allows for substantial reduction inlabor and utilizes mail containers or cartridges that allow the efficient and timely input ofdpssort assembly 213. The system maximizes, optimizes and balances the various levels oftechnology (for product ID, software and VCS delay) and captures the savings by allowinguse of a high speed second pass. Various levels of technology may be integrated in anefficient (time-balanced) scenario, which addresses a complex series of process constraints tocapture saving previously achievable. The present invention thus advantageously utilizes theextremely fast sortation capacity ofsort assembly 213 by supplying articles initially sorted bysort assemblies 212a and 212b, each of which has a lower capacity thansort assembly 213,but, when combined, are capable of supplying containers of first-pass sorted flat articles at arate that utilizes the capacity ofsort assembly 213. Multiple sort passes may be performed onthe mail through thesort assemblies 212a, 212b and/or 213 to further consolidate the sortedmail into delivery point sequence.

An alternate article sortation apparatus or system 210' (FIG. 12) includes aninput/output assembly 240 forconveyor 227, which conveys sorted trays frombuffer 214 ordirectly fromsort assemblies 212a, 212b. Input/output assembly 240 includes one ormorelanes 242 which may transfer containers from an exterior source, such as a transportationsystem (not shown) or from abuffer assembly 214a (if additional buffering capacity isdesired or required) to feed the containers to induct 217 ofsortation system 213. Alternately,input/output section 240 may transfer containers of articles that have been sorted bysortassemblies 212a and 212b to a transportation system (not shown). This allows sortationsystem 210' to dispatch to the transportation system trays of articles sorted bysort assemblies212a and 212b to the level of dispatch to other distribution/sortation centers. Accordingly,mail received at the distribution center in which sortation system 210' is located can beinducted at induct 216 on eachsort assembly 212a and 212b and sorted to other distributioncenters, as will be understood by the skilled artisan. This could be done either separate fromor in combination with sorting turnaround mail to delivery point sequence withsort assembly213.

Input/output 240 could additionally be utilized to input trays or containers of flatarticles received from other distribution centers to be combined with trays of flat articlesinitially sorted bysort assemblies 212a and 212b and finally sorted bysort assembly 213 todelivery point sequence. This allows the output ofsort assembly 213 to handle bothturnaround mail and mail originating from other distribution centers. The mail from otherdistribution centers could be sorted separately or in combination with locally collected mailin the area surrounding the distribution center in which sortation system 210' is located. Insortation system 210', the conveyingassembly 227 would utilize bi-directional transferswitches 236' in order to provide transferring of articles to either induct 217 or to input/output240 andvice versa. Transfer switches 236, 236' are preferably of the type disclosed incommonly assigned U.S. pat. application, Ser. No. 09/831,210, filed May 7, 2001 by Craig J.M. Stephen for CONVEYOR TRANSFER ASSEMBLY (Attorney Docket RAP04 P-581A),which is the U.S. National application for International Application No. PCT/EP00/04995, filed May 31, 2000, claiming priority on U.S. provisional application, Ser. No. 60/137,785,filed June 4, 1999, the disclosures of which are hereby incorporated herein by reference.

Preferably,dps sort assembly 213 is capable of handling both flat articles, such as flatmail, and the smaller letter mail. With such capacity, it may be possible to merge not onlyflat mail from distribution centers remote from the distribution center in which sortationsystem 210' is located, but also to insert letters such as from other such distribution centers orfrom other sorters such as a sorter dedicated to sorting letter mail. As such, the maildispatched from the output ofsort assembly 213 may be integrated into individual bundles ofboth flat mail and letter mail for each household in order to further maximize the efficiencyof each mail carrier while walking the mail route.

Additionally, similar tosortation system 210, sortation system 210' may include oneor more return conveyors (not shown in FIG. 12) between transfer switches positioned alongthe conveyors and inducts 216 or sorter units orsort assemblies 212a, 212b and/or betweenthe transfer switches and the discharge of sorter unit or sort assembly 213, in order tofacilitate multiple sort passes ofsorter units 212a, 212b and/or 213. Optionally, buffers 214may be replaced with a single buffer (not shown) positioned along the return or loopconveyor, without affecting the scope of the present invention.

Another alternate embodiment of an article sortation apparatus orsystem 210" (FIG.13) in accordance with the present invention is similar tosortation system 210, except that itincludes a dps sortation assembly 213' with an induct 217' having only twoinduct lines 238.By using rigid containers capable of automatic unloading, sortation assembly 213' can besupplied with a sufficient quantity of articles utilizing only two induct lines. Similar tosortationsystems 210 and 210',sortation system 210" may also include one or more returnconveyors (not shown in FIG. 13) which may convey trays between one or more transferswitches and theinducts 216 of thesort assemblies 212a, 212b and/or the discharge of thesortation assembly 213', in order to facilitate multiple sort passes throughsort assemblies212a, 212b and/or 213'.

Another alternate article sortation apparatus or system 210'" (FIG. 14) is shownhaving a singleinitial sort assembly 212 for conducting an initial sort plan on the flat articlesand abuffer 214 for sorting and supplying the containers of initially sorted flat articles fromsort assembly 212 todps sort assembly 213. In the illustrated embodiment,primary sortassembly 212 has a capacity that is similar to that ofsubsequent sort assembly 213. Becausethe capacities ofsort assemblies 212 and 213 are relatively closely matched, only oneprimary sort assembly 212 is provided inarticle sortation system 210"'.

Optionally, sortation system 210'" may include a return or loop conveyor (not shownin FIG. 14) which connects between one or more transfer switches alongconveyors 222a,222b and theinduct 216 ofsort assembly 212 to facilitate multiple sort passes through theinitial sort assembly 212 if desired. The return conveyor may also be connected between thedischarge of thesecond sort assembly 213 and one or more transfer switches alongconveyor227 to facilitate multiple sort passes of either of thesort assemblies 212 and/or 213.

Referring now to FIG. 15, a sortation system 310 includes multiple sortationassemblies or machines, such as threesortation assemblies 312a, 312b and 312c. Eachsortation assembly 312a, 312b, 312c is connected to a conveying assembly orsystem 315,which is operable to sort, arrange, sequence and convey trays from adischarge conveyor 326of eachsortation assembly 312a, 312b, 312c to an induct 316 of an appropriate one of thesortation assemblies 312a, 312b, 312c. Theconveyor system 315 includes a buffer orsorter314a, 314b, 314c positioned at a level generally above or adjacent to arespective sortationassembly 312a, 312b, 312c.Sortation assemblies 312a, 312b, 312c andbuffers 314a, 314b,314c are substantially similar tosortation assembly 12 andbuffer 14, discussed above, suchthat a detailed discussion of these assemblies and buffers will not be repeated herein. In theillustrated embodiment,sortation assemblies 312a, 312b, 312c are flat-sorting machines, suchas the type marketed by Alcatel Postal Automation System and/or Mannesmann DematicPostal Automation and/or Mannesmann Dematic Rapistan Corp. and/or Siemens DematicCorp. under Model AFSM100. Alternately, however, the sortation assemblies may be anyother type of sortation assembly, such as a dual carousel system, such as the sortationassembly marketed by Mannesmann Dematic Postal Automation under Model TOP2000, thesortation assembly marketed by Lockheed Martin Postal Automation under Model FSM 1000or any other flat mail sortation system, without affecting the scope of the present invention.

Similar tosortation assembly 12, discussed above, eachsortation assembly 312a,312b, 312c includes threeinducts 316 adjacent to threetray lowering devices 330 of therespective buffer 314a, 314b, 314c.Inducts 316 receive the articles from trays or binslowered by loweringdevices 330 and are operable to induct the articles into therespectivesortation assembly 312a, 312b, 312c, where the articles are sorted and discharged into thebins or trays at the appropriate sortation station, as discussed above with respect tosortationassembly 12. The trays are preferably conveyed along the sortation assemblies via a trayhandling system, such astray handling system 110, which is operable to automaticallyremove partially filled trays from the sortation stations and convey the trays to a labelingstation (not shown in FIG. 15) and ontodischarge conveyor 326 of the respective sortation assembly. Similar to buffer 14,buffers 314a, 314b, 314c include at least one, and preferablythree,conveyor loops 332 between aninduct end 320 and adischarge end 322. Trays ofsorted articles are received atinduct end 320, andbuffers 314a, 314b, 314c are operable tosort, stage and accumulate the trays as the trays are conveyed around thecontinuous loops332 to arrange and sequence the trays in an arranged manner prior to discharging thearranged trays atdischarge end 322. The trays are then lowered via loweringdevices 330 toinducts 316 of therespective sortation assembly 312a, 312b, 312c.

Conveyor system 315 further includes aconveyor loop 327, which is preferablyelevated and positioned at and interconnected between the discharge conveyor orconveyors326 of eachsortation assembly 312a, 312b, 312c and theinduct end 320 of eachbuffer 314a,314b, 314c. Atray elevating device 328 is positioned at adischarge end 326a of eachdischarge conveyor 326 and is operable to elevate or raise trays upward and onto theelevatedconveyor loop 327.

Conveyor loop 327 provides a generally continuous conveying loop for trays to beconveyed around, such as in the counterclockwise direction as shown in FIG. 15.Conveyorloop 327 includes a plurality oftransfer units 337a, 337b positioned therearound for changingthe direction of travel of the trays, similar to transferunits 237, discussed above. Forexample, atransfer unit 337a is positioned adjacent to eachtray elevating device 328 and isoperable to receive the trays from the elevatingdevice 328 and redirect or transfer the traysonto the conveyingloop 327. Similarly, atransfer unit 337b is positioned at each induct 320ofbuffers 314a, 314b, 314c, and is operable to transfer the appropriate trays onto theappropriate induct 320 of theappropriate buffer 314a, 314b or 314c for sorting and arrangingthe trays prior to the second sort pass through the sortation assemblies.Buffers 314a, 314b,314c then automatically sort, accumulate and arrange the trays, and discharge the arrangedtrays attray lowering devices 330 for induction of the articles for the second sort pass, in asimilar manner as discussed above.

During operation, trays are filled or at least partially filled at their respective stationsand then conveyed along thetray handling system 110 towarddischarge end 326a ofdischarge conveyor 326. As trays containing articles sorted during the first pass areconveyed along thetray handling system 110 of each sortation assembly, the trays areidentified and labeled at the labeling station, as discussed above with respect tosortationsystem 10. The trays are then moved toconveyor loop 327, such as viadischarge conveyors326 and elevatingdevices 328.Conveyor loop 327 is operable to identify, such as via a laserscanner or the like (also not shown), the trays and direct the trays to the appropriate sortation assembly in preparation for the second sort pass. Sortation system 310 thus further includes acontrol (not shown) which is operable to identify the trays and determine and select theappropriate sortation assembly for the second sort pass. Theconveyor loop 327 may then beoperable in response to the control to selectively convey trays from any one of thesortationassemblies 312a, 312b, 312c back to the induct of the same sortation assembly or to theinduct of any of the other sortation assemblies to whichconveyor loop 327 is connected. Forexample, the conveyor loop may convey a group of trays fromsortation assembly 312a to theinduct 320 ofbuffering assembly 314b atsortation assembly 312b. The buffering assemblyis then operable to sort and arrange the trays and to discharge the arranged trays to the inductend of the respective sortation assembly for the second sort pass.

Because thesortation assemblies 312a, 312b, 312c are connected together viaconveyor loop 327, the sortation system 310 may accommodate a greater sequencing matrixthan a single or double assembly system. For example, if eachsortation assembly 312, 312b,312c provides 120 output bins (such as three 40 output bins at each assembly), and thesequencing matrix of FIGS. 23 and 24 is implemented, the second pass through theassemblies allows all 120 bins of each assembly or machine to be dedicated to a120x 120sequencing matrix, so that each of the three sortation assemblies is able to sequence 4800addresses for a total of 14,400 addresses. For example, during the first pass, each sortationassembly may sort articles to three groups of 40 bins (e.g.,sortation assembly 312a may sortsequences 1, 41, 81, up to 1600 to one bin of a group of 40 bins, andsort sequences 2, 42, 82,up to 1582 to a second bin and so on, whilesortation assembly 312b may sort sequences1601, 1641, 1681 up to 3200 to one bin of a group of 40 bins, and sort sequences 1602, 1642etc. to a second bin of that group and so on, withsortation assembly 312c sorting sequences3201 to 4800 in a similar manner). The second set or group of 40 bins for each machine issimilarly processed for sequences 4801 to 9600, while the third group of 40 bins for eachsortation assembly is likewise processed for sequences 9601 to 14400.

After the first pass, theoverhead conveyor loop 327 andbuffer systems 314a, 314b,314c sequence and arrange the trays for the second sort pass, such as by queuing all traysdischarged from one group of 40 bins on the three assemblies at a selected one of theassemblies, while the trays for each of the other groups of 40 bins are similarly assigned andqueued at a selected one of the other assemblies. The first sortation assembly may, forexample, then processsequences 1 to 4800 in its 120 bins, while the second and thirdassemblies then process sequences 4801 to 9600 and 9601 to 14,400, respectively.Alternately, however, other sequencing matrices may be implemented, such as the sequencing matrix shown in FIGS. 25A, 25B and 26A, 26B and discussed below, or othersequencing matrices, without affecting the scope of the present invention.

Theconveyor loop 327 is operable to connect the multiple sortation assemblies insuch a way as to route trays from and to the same sortation assembly or to any of the othersortation assemblies, depending on the sequencing matrix and sequences associated with thetrays or bins. Although shown as having three sortation assemblies, sortation system 310may include more or less sortation assemblies, whereby theconveyor loop 327 may beadapted to convey trays to one or multiple sortation assembly arrangements, without affectingthe scope of the present invention. Also, although shown as being an overhead conveyorconnected to overhead buffers, the conveyor system, including the conveyor loop and/orbuffers, may be at a lower level, with the buffers positioned to one side or end or otherwisenear their respective sortation assembly, without affecting the scope of the present invention.

Referring now to FIGS. 16-21, asortation system 410 includes a buffer or sequencingconveying assembly orsystem 414, which is operable to sort, arrange and convey trays froma discharge conveyor 426 (FIGS. 19-21) of asort assembly 412 to inductstations 416a, 416b,416c of thesort assembly 412. Thebuffer conveyor system 414 is preferably positioned at alevel generally above or adjacent to sortassembly 412.Sort assembly 412 is substantiallysimilar to sortassembly 12, discussed above, such that a detailed discussion of the assemblywill not be repeated herein. Similar to sortassembly 12, sort assembly 412 may have 120 binpositions (as shown), or may be extended up to 240 bins or more, or any other number ofbins, depending on the application. Providing additional bin positions facilitatesimplementation of a substantially larger sequencing or sortation matrix with the sortationsystem. In the illustrated embodiment, sort assembly 412 is a flats sorting machine, such asthe type marketed by Alcatel Postal Automation System and/or Mannesmann Dematic PostalAutomation, Mannesmann Dematic Rapistan Corp., Solystic and/or Siemens Dematic Corp.under Model AFSM 100. Alternately, however, the sort assembly may be any other type ofsortation assembly, such as a dual carousel system, such as the sortation assembly marketedby Mannesmann Dematic Postal Automation, Solystic and/or Siemens Dematic Corp. underModel TOP2000, the sortation assembly marketed by Lockheed Martin Postal Automationunder Model FSM 1000, or any other flat mail sortation system, without affecting the scopeof the present invention.

Similar to sortassembly 12, discussed above, sort assembly 412 includes three inducts416a, 416b, 416c adjacent to threetray lowering devices 430a, 430b, 430c (such as the threegenerally vertical lowering devices shown in FIGS. 16 and 18 or the three spiral incline conveyors shown in FIG. 17 or any other lowering means) ofbuffer 414.Inducts 416a, 416b,416c receive the articles from trays or bins lowered by loweringdevices 430a, 430b, 430cand induct the articles into thesort assembly 412, where the articles are sorted and dischargedinto the bins or trays at the sortation stations, as discussed above with respect to sortassembly 12. The trays are conveyed along the sort assembly via a tray handling system,such astray handling system 110, which is operable to automatically remove partially filledtrays from the sortation stations and convey the trays to a labeling station (not shown inFIGS. 16-21) and ontodischarge conveyor 426. The labeled trays are then conveyed tobuffer orsequencing conveyor 414, such as via aninclined ramp conveyor 428 or other traymoving device which is operable to transfer trays from the sort assembly to the sequencingconveyor. Although described as having a labeling station at the end of the tray handlingsystem, it is envisioned that the labeling station may be positioned elsewhere along the sortassembly and tray handling system, such as at the beginning or upstream end of the trayhandling system, without affecting the scope of the present invention.

Buffer 414 includes aninduct transportation conveyor 421 at aninduct end 420 and adischarge transportation conveyor 423 at adischarge end 422, with a pair of generallyparallel transportation conveyors 432a, 432b extending therebetween. A pair of 90degreetransfer units 431 are located at a junction ofincline ramp conveyors 428 and inducttransportation conveyor 421. Also, a pair of 90degree transfer units 425 are located at thejunctions of theinduct conveyor 421 andtransportation conveyors 432a, 432b, while acorresponding pair of 90degree transfer units 427 are located at the junctions oftransportation conveyors 432a, 432b and dischargetransportation conveyor 423.Transferunits 427 are operable to move the trays or containers ontodischarge transportation conveyor423 for conveying the trays to the inducts of the sortation assembly for the second sort pass,as discussed below, or to move the trays onto a pair oftakeaway conveyors 436 fordischarging the trays after the delivery point sequencing process is completed, as alsodiscussed below.

Thetransportation conveyors 432a, 432b include a plurality of temporary storage orsort location fingers, slots orzones 434 extending laterally therefrom at either side of each oftheparallel conveyors 432a, 432b. A plurality of 90 degree transfer units 429 (FIG. 17) arepositioned alongconveyors 432a, 432b and are operable to convey trays either alongconveyors 432a, 432b or laterally to either side ofconveyors 432a, 432b to direct the traysinto and out from a targeted one of thesort location zones 434. Each of thezones 434includes a motorized roller conveyor or the like and is operable to receive and discharge one or more trays from and to a respective one oftransportation conveyors 432a, 432b. In theillustrated embodiment, eachslot 434 is capable of temporarily storing or staging up to fourtrays. However, the zones may be configured to receive more or less trays, in order to adaptthe system to the applicable mailstreams, without affecting the scope of the present invention.

Trays of sorted articles are received atinduct end 420, and buffer 414 is operable tosort, stage and accumulate the trays as the trays are conveyed along a respective one of theconveyors 432a, 432b and onto an appropriate one of thezones 434. After the trays arearranged in their appropriate zones and the first sort pass is completed,buffer 414 is operableto discharge the trays from theirzones 434 and to convey the discharged trays alongconveyors 432a, 432b to arrange the trays in an arranged manner prior to conveying ortransferring the arranged trays ontodischarge transportation conveyor 423 atdischarge end422. A plurality of 90 degree transfer units 433 (FIG. 17) are positioned alongdischargetransportation conveyor 423 and are operable to move the trays onto one of threedischargeconveyors 435a, 435b, 435c, which then conveys the trays to thetray lowering devices 43a,430b, 430c, respectively. The trays are then lowered via loweringdevices 430a, 430b, 430cto inducts 416a, 416b, 416c of thesort assembly 412. As best shown in FIGS. 16 and 17,buffer 414 includesenough storage zones 434 so that each zone may be designated to aparticular output bin of thesort assembly 412. Extra zones are preferably provided forsituations where a particular sort station may provide more than four containers of sorted mailto buffer 414, and thus exceeds the space allotted for that station at its four station storagezone. In the illustrated embodiment,buffer 414 includes 142 sort location zones, such that120 of these are designated for a particular one of the 120 output bins ofsort assembly 412,and the remaining zones are designated for excess or overflow trays.

Although shown and described as a pair of transportation conveyors having a pluralityof zones connected thereto, it is further envisioned that the sequencing buffer of the presentinvention may otherwise include multiple transportation conveyors with zones extendingfrom each conveyor, such as three pairs of transportation conveyors with zones extendingfrom one or both sides of each conveyor, without affecting the scope of the present invention.Varying the number of transportation conveyors allows for variation in the overalldimensions of the sequencing buffer to adapt the sequencing buffer of the present inventionto various applications.

The delivery point sequencing process initially begins with the use of the sortationmachine or sort assembly in conjunction with a tray handling system, which preferablyautomates the flow of trays and mail through the flat sorter. A system of flats tub or container storage and tracking is implemented to again sort the mail and sequence it into itsnumerical order by the address on the mail item. The particular sort process depends on thesequencing matrix that is implemented withsortation system 410.

The containers may be stored in a designated zone or accumulation conveyor 434(such as a four zone accumulation conveyor, as shown in FIG. 17) while mail sorting is beingconducted. Each sort location of the sortation machine may have its own designated sortlocation zone.

The process of delivery point sequencing is a two step process. The articles begin thesequencing process by being delivered to the feeders of the sortation machine whereoperators feed the articles into the machine. Once the articles are fed into the machine, theyare sorted by the sortation machine according to their zip code or other identification andplaced into corresponding tubs, trays or containers, which are located in pre-designated sortlocations or stations on the sorter.

When a container becomes full, a bin full sensor temporarily halts sorting of mail tothat sort location and triggers the tray handling system to remove the full container andrelease it to the motorized roller take away conveyor 116 (FIGS. 19-21) of the tray handlingsystem. An empty container is then delivered to the open sort location and automaticallyplaced there in order to allow sorting to continue at that location.

The full or at least partially filled containers removed by the tray handling systemproceed along themotorized roller conveyor 116 until they reach the end, where they may berotated 90 degrees by a tray rotator (not shown in FIGS. 16-21). The containers then feedontoincline conveyor 428, which transports them to an overhead height, such as a height ofapproximately 12 feet, and to transfer unit 431 (FIG. 17). Thetransfer unit 431 then movesthe containers onto theinduct transportation conveyor 421. Containers that came from thereject bins (normally one or more of the later bins of the sortation machine, such asbins 119and 120) and containers with unreadable labels remain at floor level and are diverted to areject conveyor (not shown in FIGS. 16-21).

The containers are then transported to one of the twotransfer units 425 located at eachend of theinduct transportation conveyor 421. Each of thetransfer units 425 moves thecontainers onto a corresponding one of the pair of generally parallel motorizedrolleraccumulation conveyors 432a, 432b. The containers may then be scanned as they areconveyed alongtransportation conveyor 432a, 432b to a series ofbi-directional transfer units429. The information on each container bar code label is used to determine which one of thetransfer units 429 will actuate for that tray as it is conveyed along theappropriate transportation conveyor 432a or 432b. As the containers continue down the transportationconveyor, their transfer information is retained. When the container reaches its designatedlocation, the assignedtransfer 429 is actuated to move the tray onto the appropriate storageslot orsort location zone 434.

The slots orsort location zones 434 preferably correspond to the numerical order inwhich the sort bins are arranged on thesortation machine 412. For example, sortlocationzones 1 thru 60 may be located directly above thesort bins 1 thru 60 of the sortation machine,whilesort location zones 61 thru 120 may be located on the opposite side. Sortlocationzones 1 and 2 may be located closest to the charge or induct end of the accumulation orsequencing or buffer conveyor where the containers are scanned. The numerical orderpreferably continues right to left with odd numbers on one side and even on the other. Thesame order system preferably is maintained for thesort location zones 61 thru 120 on theopposite side. The containers are kept in their respective slots or sort location zone until thesecond sort pass is initiated.

This same operation is repeated for every sort location or station of thesort assembly412. Deliverypoint sequencing system 410 includes enough locations to accommodate thefull or at least partially filled containers and store them separately by their designatedsequence group and sort location. If additional storage locations are required for a particulargrouping of delivery sequences or sort location, the containers may be directed to one ofseveral overflow accumulation zone conveyors, such as to one of the twenty-two extra zonesshown in the illustrated embodiment. These overflow zones are assigned to the respectivesequencing group or sort location. The overflow zones can be assigned dynamically based onthe actual outputs from each sort plan.

Once all of the allotted articles for the first sort pass has been initially sorted throughthe sortation machine, a sweep of thesort assembly 412 is conducted and all partially fullcontainers are removed and transported in a similar manner as the full containers or trayswere during the first sort pass. The trays then proceed to theinclined ramp 428 and followthe same path as the full containers before them.

Once thesort assembly 412 is cleared and an empty container is placed in each sortlocation, deliverypoint sequencing system 410 begins to transport the stored, full or partiallyfilled containers from their designated storage locations in the reverse order they werereceived for storage. Using theaccumulation zones 434, which initially stored the containers,and thetransfer units 429 andtransportation conveyors 432a, 432b, the containers are movedto thetransfer units 427 at the opposite, discharge end of the system.Transfer units 427 then move the containers onto the motorized rollerdischarge transportation conveyor 423, wheremore transfer units 433 are used to evenly distribute the trays or containers onto one of themotorizedroller discharge conveyors 435a, 435b, 435c. All of the trays that came from aspecific bin are preferably distributed evenly to all three of the discharge conveyors. If thereare more or less than three containers per sort location, the trays preferably are alternatedthrough the feeders throughout the sort operation to equalize the feeder routine. Theaccumulation orbuffer conveyor system 414 delivers the containers, in order, to thetraylowering devices 430a, 430b, 430c, which may be any tray lowering means, such as agenerally vertical lowering device, such as shown in FIG. 16, or a spiral chute such as shownin FIG. 17. The tray lowering devices then return the trays to the floor level at the feeder areaof the sortation machine. Preferably, each of the threefeeder stations 416a, 416b, 416c onlyreceives the full containers from a specific sort location zone at any given time. All threeoperators at the feeder stations then only sort mail that came from a single location at anytime. If an operator runs out of mail before the others, that operator and station may remainidle until the others are completed. Generally, an operator that runs out of mail first will nothave to wait more than the time it takes for one or both of the other operators to complete onetray of articles. The full containers for the next sort bin location are then staged to beimmediately ready for processing once all three feeders are cleared of the articles from theprevious bin.

When the articles are fed back into thesort assembly 412 it is stored in the movingbuckets and dropped in sequence into the appropriate route designated sort locations. Whenthe containers become full, they are again removed by the tray handling system and conveyedto theinclined ramps 428. The trays are then further conveyed to the appropriate slot orzone434 for storage in their proper order, where they are retained in the zone until they are readyfor delivery. Again, overflow zones are preferably available for storing containers from binsreceiving a large supply of articles or items.

Once all of the articles have been re-sorted and sequenced by the second sort pass, thecontainers are transported, grouped by sort location, to a remote location, viatakeawayconveyors 436, where they may be brought down to floor level for loading into thecorresponding delivery vehicles.

Although shown as having a single sortation assembly, sequencing, accumulating orbuffering conveyor system 414 may be implemented with two or more sortation assemblies,whereby a conveyor loop may be adapted to convey trays to another or multiple sortationassembly arrangements, similar to sortation assembly 310, discussed above, without affecting the scope of the present invention. Also, although shown as being an overhead conveyorconnected to overhead conveyors and zones, thebuffer conveyor system 414 may be locatedat a lower level, such as to one side or end or otherwise near the respective sortationassembly, without affecting the scope of the present invention.

Referring now to FIG. 22, a flat mailprocessing flow process 500 is shown for atypical processing and distribution center.Process 500 illustrates that a two pass deliverypoint sequencing process can be accomplished on flat sorting machines with 120 bins formultiple carrier routes in a given timeframe. Process starts at 505 at a primary processingstage, where mail is collected at 510 and outgoing mail is zone sorted to 3 digits at 515 andthe targeted mail is also zone sorted to 3-digits at 520. A first pass deliverypoint sequencingprocess 525 sorts the mail to the desired bins, depending on the sort plan or sort matrix.Incoming mail, contract mail and periodicals are input into the sortation assembly or machineat 530, 535 and 540, respectively. The containers containing the mail sorted in the first passare conveyed by a tray handling system to the delivery point sequencing conveyor at 545.After the trays are sequenced by the delivery point sequencing conveyor, the trays are inputinto the sortation machine at 550 for the second pass through the sortation machine. Thesequenced carrier route mail is then dispatched at 555. Theprocess 500 may then be repeatedfor new mail being received and collected.Process 500 is not shown with what typically iscalled the first processing of collected outgoing mail or the processing of incoming andcontracted presorted mail.Process 500 also is not shown with the process involving zoningmail by carrier nor does it consider specific arrival times of various mail streams. However,these processes clearly may be included inprocess 500, without affecting the scope of thepresent invention.

The number of bins required for each carrier depends on the number of sequences(addresses) in a particular letter carrier walk (LCW). Typically, a flat sorting machine with120 output bins is divided into three groups of bins, each having 40 bins. In such anexample, it is possible to create a sequencing matrix of 1600 slots (40 rows x 40 columns).Such a sequencing matrix is depicted in FIG. 23 (first pass) and FIG. 24 (second pass). Ifeach LCW consists of 650 sequences, then 2.46 LCWs x 3 or 7.38 LCWs could besequenced at a time on each 120 bin flat sorting machine.

Referring now to FIGS. 25A, 25B, 26A and 26B, a sortation orsequencing matrix 600of the present invention provides a matrix for processing and sequencing significantly moreLCWs during a given time period. This sequencing matrix may be implemented inconnection with any of the sortation systems discussed above, or with other sortation and sequencing systems, without affecting the scope of the present invention. As shown in FIGS.25A, 25B, afirst sort pass 600A is performed with a total of 660 sequences per carrier, using110 outputs of the sortation machine and six sequences per bin or output. The remaining 10bins (120 bins - 110 bins or outputs) are preferably reserved for hold out mail and rejects andthe like.

As shown in FIGS. 25A and 25B, six rows of thesequencing matrix 600 are assignedto each carrier. For example, in the illustrated embodiment,rows 1 through 6 are assigned toLCW #1,rows 7 through 12 are assigned toLCW #2,rows 13 through 18 are assigned toLCW # 3, and so on, up to row 120 rows for a total of 20 carriers.

The number of LCWs able to be processed on any given machine depends on thenumber of output bins utilized for the second pass. The example of bin assignments shown inFIG. 26B indicates that using 120 output bins permits 20 LCWs to be processed concurrentlyfor the first and second passes on a single 120 bin machine (with 6 rows per carrier). More orless rows can be assigned depending on the number of sequences required for each LCW. Iffewer rows are used in the first pass, then fewer rows are required for the second pass, suchthat more LCWs can be processed at a time.

Assuming that each LCW has 1,000 flat mail pieces distributed to 650 sequences,then, on average, each address receives 1.54 pieces of mail. With 120 sequences assigned toeach bin, each bin could receive 120 x 1.54 or 185 pieces of mail. Using an average of 70mail pieces per mail tray, an average of 2.6 trays may be discharged from each bin.

The sequencing system used withsortation matrix 600 may be a sequencing conveyorof one of the types discussed above and may be a system of conveyors installed over thesortation machine or machines, and is thus able to sort and queue trays for the second pass.The tray handling system selected for use withsortation matrix 600 is preferably capable ofhandling variances in the number of trays discharged, so that the specific number ofdischarged trays will not hamper performance. The tray handling system preferably providessignificant flexibility and is adaptable to a variety of site configurations and sortationmachine layouts.

For the second sort pass through the sortation machine, trays of mail are sent to thethree feeders in the appropriate order or sequence, as performed by the sequencing conveyoror the like. For example, the process may sort mail into the carriers' trays in a last in, first out(LIFO) order. Therefore, first pass trays frombin 120, or the last sequences in the LCW, aredelivered first to the feeders by the sequencing conveyor or system. However, the order oftray delivery does not matter and may be altered depending on the layout of the sort scheme for the first sort pass. Recall that six sequences of mail for 20 LCWs are mixed in thedelivered trays during the first sort pass. The order doesn't matter and the sequencingconveyor or system preferably distributes trays in a round robin fashion to all three feeders.Preferably, in order to ensure that articles are not inadvertently mixed, the feeder control,upon recognition of a following address sequence, will not allow mail past the buffer until allmail from the previous sequence group is inducted into the carrousel from the other one ortwo feeders.

As shown in FIGS. 26A and 26B, thesecond sort pass 600B through the sortationmachine sorts the mail sorted during the first pass into an appropriate one of the output binsof the sortation machine, where each carrier is assigned a particular block or group of bins,such as six bins in the illustrated embodiment. As the mail frombin 1 of the first pass (whichincludes mail for all six carriers) is sorted during the second pass, the mail is sorted into anappropriate bin corresponding to a particular sequence or sequences of a particular carrier.For example,bin 1 from the first sort pass includesmail pieces 1, 111, 221, 331, 441 and 551for each carrier, as shown generally in FIGS. 25A and 25B. During the second sort pass, themail is sorted such thatmail piece 1 forcarrier 1 is sorted tobin 1, whilemail piece 111 forcarrier 1 is sorted tobin 2, and so on, up tomail piece 551 forcarrier 20 being sorted tobin120, as shown generally in FIGS. 26A and 26B.

Once all of the mail has been fed and inducted, the trays are automatically swept(discharged) and labeled by the tray handling system prior to being dispatched. If a traybecomes full before the sweep can occur, the tray handling system preferably removes thefull tray, automatically applies the destination label and replaces it with an empty tray.

Once the second sort pass is complete and the sortation machine is swept, a newscheme or sort plan can be loaded while the sortation machine is being replenished withempty trays. Typically, loading a new scheme may take approximately 20 minutes, whilereplenishing with empty trays can be done concurrently and well within this timeframe.

The present invention thus provides a sortation and sequencing matrix which allowsfor significantly more LCWs to be processed at a time. For example, for routes having 650sequences, as discussed above, the sequencing matrix of the present invention allows forsortation and sequencing of 20 different carrier routes. Also, net throughput of the sortationsystem is enhanced. The sortation matrix of the present invention is flexible and adapts tovarying requirements. The sortation matrix of the present invention also allows for all threeinducts or feeders of the sortation machine to be used for all of the output bins during bothsort passes.

Therefore, the present invention provides an article sortation apparatus which isoperable to provide two sort processes or passes of articles through one or two sortation unitsin order to achieve the delivery point sequence or carrier walk sequence sort of the articles.The buffer of the present invention is operable to automatically sort the containers or trayscontaining articles from a first sort process, such that the articles are inducted into a sortationunit in a proper sequence or order for a second sort process or pass. The buffer of the presentinvention may convey the trays containing the first sorted articles in a generally continuousloop, whereby additional trays are input into the loop at appropriate spaces between traysbeing cycled around the loop, until all the trays have been accounted for and are being cycledor accumulated around the generally continuous loop in the proper order or sequence.Alternately, the buffer may provide a plurality of temporary storage zones or conveyors,where the trays are temporarily stored until the first sort pass is completed, and thenautomatically discharged in an appropriate order for the second sort pass. The ordered traysare then discharged from the loop conveying portion to the induct of the sortation unit,whereby the articles are re-inducted into the sorter unit for the second sort process. Thepresent invention thus provides an automatic and efficient system for automatically sortingflat mail to the delivery point sequence. The articles are sorted to the delivery point sequencewithout temporary storage of the trays in bins or racks or the like, and without transportingthe trays via manual processes or via carts or robotic devices or the like. The trays areconveyed along interconnected conveying portions in order to provide continuous sorting andconveying of the trays, which further expedites the sortation process.

Additionally, mail may be transferred between sortation assemblies or the input andoutput of a single sortation assembly in a highly automated manner. This avoids thenecessity for loading mail into standard trays and loading the trays on manual carts, alsoknown as Eastern Regional Mail Containers (ERMC). Advantageously, the present inventionmay utilize containers that are of rigid construction such as rigid molded plastic or the like,and bearing a permanent identification number which may be encoded by a plate attached tothe container, which may be a bar code, radio frequency tag, or the like. This eliminates thenecessity for applying temporary labels to each container dispatched from the sortationassembly as would be done if the containers were being dispatched to the transportationsystem. Rigid containers are feasible because the containers may be retained totally withinthe sortation assembly and not utilized to ship mail to other distribution centers. Mail may beprepared at a common mail preparation location or station and loaded into the rigid containersand then conveyed to the inducts of the sorter units. The utilization of rigid containers advantageously facilitates automatic transfer of flat articles from the containers at the inductsto thereby further reduce manual processing of the flat articles to be sorted.

The present invention thus provides automated means for sorting, queuing,sequencing and presenting trays of sorted articles to the inducts of the sortation assembliesfor the second sort pass. The trays may be automatically removed from their respectiveoutput bins, and automatically identified and labeled so that the trays may be provided in theproper order. The present invention also provides for automatic delivery point sequencing fora larger sequencing matrix via utilization of two or more sortation assemblies or machines. Aconveyor loop may be implemented to connect each sortation assembly with each buffer ortray sorter to facilitate sortation of a greater number of addresses or sequences with a singlesystem.

The present invention also provides for an improved sequencing matrix forsequencing the articles in appropriate output bins for multiple carriers. The sequencingmatrix of the present invention provides significantly more carrier routes to be processed at agiven time, while increasing the net throughput of the system. The sequencing matrix of thepresent invention also is flexible and adapts to varying requirements of the sortation machineor machines and the desired sequences of the articles or mail.

Changes and modifications in the specifically described embodiments can be carriedout without departing from the principles of the present invention, which is intended to belimited only by the scope of the appended claims, as according to the principles of patent law.

Claims (35)

1. An article sortation system for sorting articles to adelivery point sequence depth of sort, said article sortationsystem comprising:

   at least one article sorter having an induct and adischarge, said at least one article sorter being operable tosort articles into a plurality of trays and discharge thetrays of sorted articles at said discharge; and

   a buffering assembly for automatically sorting andconveying the trays containing sorted articles sorted duringa first sort of said at least one article sorter from saiddischarge of said at least one article sorter to said inductof said at least one article sorter, said buffering assemblybeing operable to automatically arrange the trays in anarranged manner and convey the arranged trays to said inductof said at least one article sorter for a second sort of thearticles.
2. The article sortation system of claim 1, wherein saidbuffering assembly comprises a plurality of conveyors whichare cooperatively operable to arrange and accumulate trays inthe sequenced manner on said buffering assembly as the traysare received from said discharge of said at least one articlesorter.
3. The article sortation system of claim 2, wherein saidplurality of conveyors comprise at least one transportconveyor and a plurality of zone conveyors connected to saidtransport conveyor, said zone conveyors and said transportconveyor being cooperatively operable to receive trays fromsaid at least one transport conveyor and discharge trays tosaid at least one transport conveyor in an appropriate orderfor said second sort.
4. The article sortation system of claim 3, wherein saidplurality of zone conveyors are positioned along at least oneside of said at least one transport conveyor.
5. The article sortation system of claim 4, wherein said atleast one transport conveyor includes a plurality of transferunits, each of said plurality of transfer units beingpositioned at at least one of said plurality of zoneconveyors and being operable to move trays between said atleast one transport conveyor and a respective at least one ofsaid plurality of zone conveyors.
6. The article sortation system of claim 2, wherein saidplurality of conveyors define at least one generallycontinuous loop between said discharge of said at least onearticle sorter and said induct of said at least one articlesorter.
7. The article sortation system of claim 6, wherein saidbuffering assembly is operable to circulate trays in said atleast one generally continuous loop and input new trays intoappropriate spaces between the circulating trays in said atleast one generally continuous loop as the new trays arereceived from said discharge of said at least one articlesorter.
8. The article sortation system of claim 7, wherein said atleast one generally continuous loop comprises at least twogenerally continuous loops.
9. The article sortation system of claim 8, wherein said atleast one article sorter includes a plurality of individualarticle sorting stations, each of said at least twocontinuous loops being operable to convey trays received fromdifferent groups of individual sorting stations of said atleast one article sorter.
10. The article sortation system of claim 1, wherein said atleast one article sorter comprises a first article sorter anda second article sorter.
11. The article sortation system of claim 10, wherein saidbuffering assembly is positioned along a return conveyorwhich is connected between at least one of a discharge ofsaid first article sorter and a discharge of said secondarticle sorter and at least one of an induct of said firstarticle sorter and an induct of said second article sorter.
12. The article sortation system of claim 10, wherein saidbuffering assembly is connected between a discharge of saidfirst article sorter and an induct of said first articlesorter.
13. The article sortation system of claim 12 including asecond buffering assembly connected between a discharge ofsaid second article sorter and an induct of said secondarticle sorter.
14. The article sortation system of claim 13 including aconnecting conveyor positioned between said bufferingassembly and said second buffering assembly and between saiddischarges of said first and second sorters.
15. The article sortation system of claim 14, wherein saidconnecting conveyor is operable to convey trays from saiddischarge of at least one of said first article sorter andsaid second article sorter to an appropriate one of saidbuffering assembly and said second buffering assembly.
16. The article sortation system of claim 15, wherein saidconnecting conveyor defines a generally continuous loop.
17. The article sortation system of claim 1, wherein said atleast one article sorter comprises a single article sorter.
18. The article sortation system of claim 17, wherein saidbuffering assembly is operable to sort and convey the trayscontaining sorted articles sorted during the first sort ofsaid article sorter from said discharge of said articlesorter to said induct of said article sorter for a secondsort of said article sorter.
19. The article sortation system of claim 1, wherein saidbuffering assembly is positioned at a level above said atleast one article sorter.
20. The article sortation system of claim 19 furtherincluding elevating devices which are operable to conveytrays upward from said discharge of said at least one articlesorter to said buffering assembly and downward from saidbuffering assembly to said induct of said at least onearticle sorter.
21. The article sortation system of claim 1, wherein saidbuffering assembly includes an input for receiving out-of-areaarticles received from other article sortationfacilities and supplying the out-of-area articles to saidinduct of said at least one article sorter.
22. The article sortation system of claim 1, wherein saidbuffering assembly includes an output for dispatchingarticles sorted by said at least one article sorter as out-of-areaarticles to be supplied to other article sortationfacilities.
23. A method for sorting articles to a delivery pointsequence depth of sort, said method comprising:

    providing at least one article sorter having an inductand a discharge;

    sorting articles in a first sort of said at least onearticle sorter into a plurality of trays;

    providing a buffering assembly for automatically sortingand conveying trays containing sorted articles sorted duringa first sort of said at least one article sorter;

    conveying and arranging trays of sorted articles in anarranged manner on said buffering assembly;

    conveying the arranged trays of sorted articles to saidinduct of said at least one article sorter for a second sortof the articles; and

    sorting articles in a second sort of said at least onearticle sorter.
24. The method of claim 23, wherein conveying and arrangingtrays includes conveying each of the trays to an appropriateone of a plurality of zone conveyors.
25. The method of claim 24, wherein conveying and arrangingthe trays includes cooperatively discharging the trays fromsaid zone conveyors in an arranged manner.
26. The method of claim 23, wherein conveying and arrangingtrays includes conveying the trays in a continuous loop.
27. The method of claim 26, wherein conveying and arrangingtrays includes generally continuously conveying the trays insaid continuous loop.
28. The method of claim 26, wherein conveying and arrangingtrays includes inducting trays into said generally continuousloop in an arranged manner.
29. The method of claim 23, wherein providing at least onearticle sorter comprises providing at least two articlesorters.
30. The method of claim 29, wherein providing a bufferingassembly comprises providing at least two bufferingassemblies.
31. The method of claim 30 including conveying trays fromsaid discharge of one of said at least two article sorters toone of said at least two buffering assemblies.
32. The method of claim 23, wherein providing at least onearticle sorter comprises providing a single article sorter.
33. The method of claim 23 including elevating trays fromsaid discharge of said at least one sorter to an elevatedbuffering assembly.
34. The method of claim 33 including lowering the arrangedtrays from said elevated buffering assembly to said induct ofsaid at least one article sorter.
35. The article sortation system of claim 10 including acontrol which is operable to determine an appropriate one ofthe first and second article sorters for a second sort passfor articles in a tray, said buffering system beingselectively operable to convey and arrange the trays forinduction to the appropriate ones of the first and secondarticle sorters in response to said control.

Images