US 3884370 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 Bradshaw et al.
1 51 May 20, 1975 1 1 SYSTEM FOR SORTING AND PROCESSING ARTICLES INCLUDING FLAT MAIL PIECES  Inventors: Robert S. Bradshaw; Alfred A.
Greene, both of Broomall; James R. Hunter, Chadds Ford; S. James Lazzarotti, Broomall; Abe Mann, Bala Cynwyd; Herbert L. Rosenblatt, Broomall, all of Pa.
 Assignee: Burroughs Corporation, Detroit,
221 Filed: Sept. 28, 1973 211 App]. No.: 401,954
 US. Cl 214/11 R; 198/38; 104/88; 209/74 M  Int. Cl. 865g 43/00  Field of Search 214/11 R, 11C; 198/38; 104/88; 340/1725; 209/73, 74 R, 74 M, 72
 References Cited UNITED STATES PATENTS 3.005.537 10/1961 Schmeck et a1 214/11 R 3,100,040 8/1963 Kleist 214/11 RX 3,140,767 7/1964 Hau'er 1 1 198/38 X 3,152,681 10/1964 Byrnes et a1. 214/11 X 3,200,766 8/1965 Gorjanc 214/11 X 3,312,358 4/1967 Atanasoff et a1 214/11 R 3,803,556 4/1974 Duffy 198/38 Primary Examiner-Allen N. Knowles Attorney, Agent, or FirmFrancis A. Varallo; Edward J. Feeney, Jr.; Kevin R. Peterson  ABSTRACT The present disclosure describes a system for sorting and processing a variety of articles including certain mail pieces known as flats which cannot be processed on letter mail equipment. The system includes mechanical carriers, which may be magnetically encoded with the sort destinations, to transport and remain with the respective items through the total processing cycle. The system further comprises a monorail conveyor distribution system having a three dimensional suspension system consisting of belts to provide transport, storage, switching and supporting of the carriers during the processing operation.
12 Claims, 9 Drawing Figures PATENTED MAY 20 I975 SHEET 2 U! F IIIIIIA PATENTED HAYZOISYS 4 370,
sIIEET 30F 5 4s 45 4| 3 MAG TAPE 7 |D,EXTRACTION DUDE, :I I IIIIIIT INTERFACE STATUS |PROCESS| T0 ESTIMATION CODES,SCHEME CONTROL] DIRECTORY ATA,MODE INFORMATION i DEVICE PRINTING (POD) IITEREIIcEcoIITRoI (POD) l OONISOLE COMPUTER AND RESPONSE I 5,5 DISPLAY AND CARD IIIsRIIIY REA/DER T AND C0NTR0L. 59
g INTERFACE PANEL 5T T IJ SWEEP SY STEM PRINTING AND I RESPONSIE SIGNAL CODES 49 swEER AND TRAIIsRoRT IIoTIoII SORT CODES CONTROLS INDUCTION PRNTDATA I STATIONS I WRAP CONTROL FSEOD Fig.9
PATENTEU him/201975 3,884,370
SHEET 5 OF 5 Fig. 8
SYSTEM FOR SORTING AND PROCESSING ARTICLES INCLUDING FLAT MAIL PIECES BACKGROUND OF THE INVENTION The system described herein, while applicable to the sorting and processing of articles of varying descriptions and physical sizes and weights, resulted from an appreciation of the special problems and difficulties in sorting machinable mail flats. The latter are defined as certain mail pieces from the first, second and third class categories of mail of such characteristics that they cannot be processed on letter mail equipment but are of relatively uniform thickness and do not exceed the maximum machinable flat dimensions. The flat pieces generally exceed one or more of the maximum dimensions allowed for letter mail, namely height 6 /8 inches; length I 1 /2 inches; thickness A inch. Machinable flats are regarded as falling within the following size ranges, height 3 inches to l inches; length 4% inches to inches; thickness 0.006 inches to A; inch; weight up to 1 pound; and aspect ratio (height to length) of l to I up to l to 4.
The processing of flats by using well-known standard letter mail processing techniques would require practically every mail handling operation extant. These oper ations include mail singulating (feeding), transporting, gating, stacking (for re-feed), sweeping, storage, packaging, and labeling. Letter mail is extremely variable in size and weight, but flats exceed even this wide variability. Because of this variability, letter mail techniques could be applied to flats only with great difficulty, cost, and risk. The mechanisms to handle the flats would become complex, transports would become large and space consuming, and equipment, difficult to maintain. These general shortcomings, however, are overshadowed by one major requirement that of stacking the flats for storage and then re-feed. In sorters, the standard methods of transport such as belts with drag fingers, pinch belts, rollers and letter carts all have the common characteristic that mail is gated into some form of receptacle where a stack is formed. The difficulty of establishing a stack of sufficient uniformity to allow for automatic re-feed could possibly be overcome, but only with a complex mechanism at great expense, and with the risk of low reliability and poor performance. The system of the present invention eliminates this problem by using low cost carriers to transport the flats and no stacking is required at any time during the processing operation.
SUMMARY OF THE INVENTION The system of the present invention comprises three major components, a mini-carrier to support each item to be processed, a monorail conveyor to transport the carriers, and magnetic coding on the carriers to provide control.
With particular reference to the handling of flats, the mini-carrier is a simple, reusable and low cost suspension device which holds a flat securely during processing operations. Stated another way, the carrier and the flat are processed as a unit through all the required operations of the sorting equipment up to packaging. The carrier thus provides a standardized interface between the processing operations and the flat so that the full range of flat sizes and weights can be handled with ease. The carrier also provides a well controlled and accurately locatable base for an escort memory.
The monorail conveyor is a three dimensional suspension system consisting of simple belts to provide transport, storage, switching, and support of the minicarrier during mail processing operations. The use of this conveyor system permits low speed operation resulting in low noise level, high reliability, low maintenance costs, and long life.
The magnetic coding techniques provide an electrically alterable magnetic stripe which is placed on the mini carrier and provides a vehicle for the escort memory. Local decoding of the information placed on the magnetic stripes can be achieved using low cost, reliable readers. The use of these techniques significantly reduces the control system complexity and data transmission requirements.
In operation, the flats enter the system by way of an input conveyor from which they are stacked onto one of a plurality of induction stations. Each flat is automatically fed from the stack, clipped to a waiting minicarrier and advanced to the viewing station where the operatorkeys the desired code, which may be a ZIP code or an extraction code. The flat is then advanced to an encoding station where a destination code determined by the data keyed and the computer translation, is encoded on the carriers magnetic stripe. From herein, the flat enters the monorail conveyor distribution system in which code readers read the escort memory data on the carriers stripe and direct the flat via appropriate gating to a destination in either the high or low density output sections.
Flats in a given low density storage destination remain there until a sweep signal occurs which is generated by the control system in response to a full storage destination or whenever a sweep of the destination is desired.
Flats in a given high density storage area are rerouted passed the induction station where the operator can either re-key a new extraction code or, if completely encoded in the first pass, the flat would proceed directly to be sorted in the low density storage area.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a pictorial diagram illustrating the layout of the sorting and processing system of the present invention.
FIG. 2 is an end view of a carrier suitable for use in the system of FIG. 1.
FIG. 3 is a plan view of a transfer area depicting the unconditional transfer of a carrier from a horizontal to a vertical belt.
FIG. 4 is a section view taken along lines 4-4 of FIG. 3 illustrating the relationship of the carrier tooth structures to the timing belts.
FIG. 5 illustrates the tooth structures on the underside of the upper carrier T section.
FIG. 6 is a plan view of a switich or gate station depicting the conditional transfer of carriers from one belt to another.
FIG. 7 is an elevation view of the switch station of FIG. 6 depicting the relative orientations of the two belts to effect transfer.
FIG. 8 is a pictorial representation of the induction station used in the system of FIG. 1.
FIG. 9 is a block diagram of ccontrol means suitable for use in the system of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT The layout of an embodiment of the flat sorting equipment of the invention is depicted in FIG. 1. The basic elements of the system are the induction stations 10, the low density output 12, the high density output 14, the packaging and labeling station 16, and the various transport paths (identified hereinafter) required to interconnect the system elements. It must be emphasized that the characteristics presented herein relating for example to specific configurations and quantities of system elements have been chosen for purposes of example, and are not to be construed as limitative of the inventive concepts taught herein.
With reference to FIG. 1, the flats 18 from the mail preparation area enter the system on the input conveyor which travels past each of the six induction stations 10. Stacks of mail are manually removed from the conveyor and transferred to the induction station. Each induction station is attended by a single operator for direct viewing of the mail piece. The first operation at the induction station 10, which is described in greater detail hereinafter in connection with FIG. 8, occurs when each flat is automatically fed and attached to an individual mechanical carrier 22. The carrier with the attached flat then passes in front of the operator at which time the extraction code which may be derived from the address is entered into the keyboard. When keying is completed, the carrier leaves the viewing station and passes an encoding station where the sort pocket information obtained through the sort system control device from the process control device directory is encoded on a magnetic stripe mounted on the carrier. The carriers from each of the six induction stations leave via paths 23 and are interleaved as they enter a common transport path 24.
The level select portion of the transport consists of a series of four gates at locations 26 and transport sections 28 which direct the carrier to one of five vertical levels of transport paths. Four transport gates of the type shown in FIGS. 6 and 7, each having a read head 30, control the path that the carrier takes such that the proper level is selected which leads to the final sort destination. The five transport levels leaving the level select station go to both the low density and high density storage areas, 12 and 14 respectively.
The low density storage area 12 depicted in FIG. 1 consists of 60 separations 12' on each level, for a total of 300 separations. Gates on the main transport paths 32, at points 34, divert the carriers 22 into the storage separations when the proper code for the particular gate is sensed by a read head located at each gate. Each low density storage separation 12' consists of a short length of transport path 36 capable of holding 40 carriers. Under system control, the mail is accumulated in the low density storage area 12 until a destination accumulates 40 mail pieces or a demand sweep is initiated. For sweeping, the short length of storage transport 36 is actuated and the closely spaced carriers move out in a group onto transport paths 38 leading to the packaging and labeling station 16. Just prior to the station, the five levels of transport are merged in a single level (transport 40) at the low density level return station 42.
At the packaging station 16 the flats 18 are automatically released from the carriers 22 and are packaged and labeled for exit from the system. The empty carriers 22a are then directed to the high density storage area 14 via paths 44 and 32.
The high density storage area 14 consists of five levels of transport paths with six sort destinations 14' per level, for a total of thirty sort destinations. Each sort destination consists of three adjacent transport paths 46. The combined length of the three transport paths 46 is sufficient to store 3000 mail pieces per destination. The transport gates at locations 48 on main transports 32, leading into the sort destinations 14' read the sort information encoded on the carrier and automatically divert the flats 18 into the appropriate transport paths. Simultaneously with the flats entering the high density storage 14, empty carriers 22 leave the opposite end and are transported via paths 50, 52 to the induction stations 10 to receive the flats 18 entering the system.
When the primary sort has been completed the mail stored in the high density storage area 14 is ready for the secondary sort. At this time the transport path 46 of a selected high density sort destination 14 is activated and the carriers 22 are advanced to the main transport path 50 leading to the induction stations 10. The five levels of transport path are merged into a single level through the high density level return station 54, and a single level transport path 50 continues by the six induction stations. A queuing system is used to distribute the mail to the individual induction stations as required.
At the induction station 10, the mail pieces 18 remain on the carriers 22, and are transported through the viewing station as before, and the operator encodes the alphanumeric extraction code for the secondary sort. The carriers are encoded with the new sort information and are transported and sorted to the low density output 12 via transport paths 28, 32 and 36 in the same manner as the primary sort.
It is obvious that the mail involved in the secondary sort could be completely encoded on the primary sort, held in high density storage, and then be automatically refed for the secondary sort without going through the induction station a second time. This method of operation would require a slightly longer time for operator keying on the first pass but would completely eliminate the need for operator keying on the second pass.
It should be noted that although not used in the system described herein, another potential mode of operation is dynamic sort allocation. In this mode both the low density and the high density sort destinations, 12' and 14' respectively, are assigned to storage lines as needed by the volume of the incoming mail categories. In the low density storage area, a storage line after being swept can be assigned a different sort destination, while in the high density area new storage lines can .be assigned after previous lines have been filled. The net effect of dynamic sort allocation is the ability to use the fixed storage capacity more efficiently and thereby reduce the total amount of fixed storage required.
The present concept for sorting mail is extremely flexible in that in can be easily expanded or contracted for various size sites simply by altering the number of transport gate sections and increasing or decreasing the length of the transport storage sections. Also, in the system described, there are ninety separate high density output lines which would also allow the number of high density separations to be increased and/or the number of lines per sort destination to be optimized,
based on the sort density profile. The concept can also be expanded to utilize the carriers for transporting and processing the mail from a point beginning in the mail preparation area and ending where the mail is sequenced to delivery order.
In summary, these advantages plus the previously mentioned advantages of escort memory and not having to stack and refeed flats during the secondary sort operation are significant attributes which are derived from the use of the concept of a mechanical carrier for processing flats.
SYSTEM ELEMENTS The following is a detailed description of all the elements which comprise the present system.
A. The Carrier The mechanical details of the carrier 22 used to transport the flat 18 is illustrated in the end view thereof in FIG. 2. The carrier comprises a T shaped upper section 56 (which may be assymetrical as shown in the drawing) and a lower clamping section 58. The latter is comprised of a moveable jaw 60 adapted to pivot at point 62 and to contact a document 18 positioned adjacent a stationary jaw 64. Jaw 60 is attached to a moveable member 66 by a link 68. A compressed spring 70 normally pushes upward against the upper portion of member 66, causing jaw 60 to rotate about point 62 in a direction to grasp document 18. Release of the document when required is effected by downward pressure upon the upper portion of member 66 in opposition tothe spring force. The latter causes jaw 60 to pivot away from stationary jaw 64. Additional details of the carrier will become more apparent in the description of the transport and gating arrangements which follow and which are illustrated in FIGS. 3-7 inclusive.
The carrier contains a magnetic stripe 72 (as seen FIG. 3) on the top surface. This stripe is similar to the well known magnetic stripe which is used on credit cards and passbooks. The stripe is recessed in the carrier so that the surface of the magnetic stripe is flush with the adjacent carrier surface. This arrangement allows the magnetic read and write head holders to be spring loaded to contact the surface of the carrier and ensure uniform head-to-stripe spacing during recording and reading, without the heads wearing against the magnetic stripe. The read heads are wider than the magnetic stripe, and allow liberal tolerances on "the horizontal positioning of the carrier at the read station. The engagement of the carrier with the teeth on the timing belt transport controls the amount of skew between the read head and the recorded data.
B. Carrier Transport The upper T section 56 of the carrier 22 is used to transport and guide the carrier. This is illustrated in FIGS. 3, 4 and 5. In FIG. 3, for example, the carrier is shown positioned on belt 74 having its surface in a horizontal plane at the instant where it is being transferred to a belt 76 having its surface in a vertical plane. The underside of the assymetrical T section as seen in FIG. 5 has along the long portion thereof, tooth sections 78 adapted to mesh with the teeth in horizontal belt 74, and along the short portion thereof, tooth sections 80 adapted to mesh with the teeth in vertical belt 76. These tooth sections and their relationship to the belts is illustrated in the section view of FIG. 4 taken along lines 44 of FIG. 3.
The horizontal belt 74 runs a U channel 82, and one edge of the channel serves as a guide to retain the carrier on the belt. When the carrier is transported on the vertical belt 76 (driven by gears 84 in a conventional manner) the recessed portion of the carrier itself provides the restraint.
The plan view of FIG. 3 illustrates the arrangement for unconditionally transferring the carrier 22 from a horizontal belt 74 which is used for straight runs to a vertical belt 76 which is used for turnd in a horizontal plane. The direction of motion of both belts of FIG. 3 in the transfer area is assumed to be from left to right. The vertical belt approaches the transfer area at a vertical elevation less than that of the horizontal belt, but within the transfer area assumes an elevation which equals and then surpasses the elevation of the horizontal belt. Thus, the selected horizontal displacement of the belts together with the above described elevation conditions permit the carrier 22 to be lifted from the horizontal belt by the vertical belt. The section view of FIG. 4 illustrates the instant at which the teeth on the underside of the short portion of the carrier T section are in synchronism with the teeth of the vertical belt 76. Commencing with this point, the carrier 22 is quickly lifted by the vertical belt. The comparative elevations of the belts, while not shown in FIG. 3 are assumed to be the same as those illustrated in FIG. 7 (in which like reference characters have been used for similar components) in connection with a gated transfer of a carrier from a horizontal to a vertical belt.
It is apparent that at the end of the turn, the carrier may be transferred back to a horizontal belt in a similar manner except that the elevation of the vertical belt declines with respect to the horizontal belt in the transfer area, and the carrier is lifted off the vertrical belt by the horizontal belt. It should also be apparent that similar unconditional transfers may be effected by maintaining the elevation of the vertical belt constant and permitting a change in the elevation of the horizontal belts in the transfer areas. In any event, the carrier 22 is supported by the belts close to the vertical centerline and significantly above the center of gravity of the carrier and the fiat, so that there is only a slight shift of the vertical alignment of the carrier during transfer between belts.
The transport as illustrated is used in both the storage areas and for transport from the. storage areas to both the packaging and labeling station and to the induction stations. For these applications the carriers are spaced at three-fourth inch intervals, and for the basic rate of 6 mail pieces per second the belts can travel at a velocity as low as 4 /2 inches per second. The loading on the horizontal belt is distributed between the surface of the belt and the slider plate formed by the U channel. This is a standard arrangement for conveyor belts and at the low velocities required produce a quiet, low cost, long life transport system. The vertical belts are supported on rotating pulleys.
For the transport paths from the induction stations and through the switching sections leading to the storage lines, a slightly different transport is used. For this application it is desired to space the carriers on 3-inch centers in order to allow time for switching the carriers between transport paths. For this application a standard one-half inch pitch timing belt is used. The carrier is shaped to nest over the timing belt tooth, and will maintain its position relative to the other carriers as they are transported through the switch sections. For carriers spaced on 3-inch centers and with the basic rate of six flats per second, a transport belt speed of 18 inches per second is required. This velocity is relatively low and provides quiet, long life operation.
C. Gate Mechanism The transport switch mechanism used to direct the carrier to a sort destination is illustrated in plan and elevation views in FIGS. 6 and 7 respectively. The belts 74 and 76 in the latter Figures are assumed to be moving from left to right, that is, the carriers approach the transfer area from the left. Depending upon the sort information encoded on the individual carrier magnetic stripe 72, the carrier will either be permitted to continue on the horizontal timing belt past the switch section, or to be gated onto the vertical belt 76. The information on the magnetic stripe is read by the magnetic head 30, mounted adjacent the horizontal belt 74 and positioned to be in proximity to the magnetic stripe 72 as the carrier 22 traverses the head. In FIGS. 6 and 7 the information stored on the magnetic stripe of carrier 22!) has resulted in the actuation of a solenoid 86 by head 30 which in turn pivots a vane 88 positioned on one side of the horizontal belt 74 into the path of the oncoming carrier. The vane pushes against the upper T section of the carrier, displacing it toward the vertical belt 76. In the manner described hereinbefore in connection with FIG. 3, and as illustrated in FIG. 7, the elevation of vertical belt 76 relative to horizontal belt 74 in the transfer area is such that the carrier is lifted onto the vertical belt. The latter continues to transport the carrier 22b into the sort destination. When, as in the case of carrier 220, the information on the magnetic stripe 72 does not call for gating, the vane 88 is not actuated and due to the horizontal spacing between the belts, the carrier 220 is not able to contact the vertical belt. It therefore is transported past the switch section, as illustrated.
The carriers move through the switch at a maximum rate of six per second, or 167 milliseconds per carrier. The carrier is three-fourths inch wide, and at a transport velocity of 18 inches per second this is equivalent to 42 milliseconds time for a carrier to clear the switch. This results in a mazimum time of 125 milliseconds available for switch operation. The solenoid-actuated switching vane is a low-inertia system, and the actual switching time is of the order of 30 to 40 milliseconds.
A merging transport section is similar to the switch section except that the carriers move unconditionally from a number of paths to a main transport, and the solenoid-operated mechanism is not required. In areas where there is a transition between one and five transport levels, either a switch or merge station may be used. For example, in the case of the low density level return station 42, the individual level transports are inclined to change elevation and then are displaced horizontally from the main transport 40 before transfer occurs as described hereinbefore. D. High Density Storage The high density storage area, as shown in FIG. 1, consists of 30 sort destinations 14'. Each sort destination consists of three adjacent storage conveyor lines 46. There are six sort destinations 14' or 18 storage lines 46 on each of five levels. The physical arrangement illustrated, groups the storage lines in modules which are three storage lines wide by five levels high. This grouping allows aisles between the lines for access. The lines are spaced on l6-inch centers for a maximum flat width of 15 inches, and the aisle width is a minimum of 37 inches between maximum-size flats. This results in a total width of 39 feet. The levels are spaced at 20-inch increments, with the top level located at a 12-foot elevation. This allows a walk-under clearance for service access.
The carriers containing the flats are stacked closely together on the storage lines. With a carrier thickness of three-fourths inch, 62 /2 feet of storage line is required to store 1000 flats (3000 flats per sort destination).
A. single storage line 46 will consist of approximately six 10-foot sections of horizontal belt transport (without teeth). Each transport section is individually powered and controlled. A shorter section, approximately 2 /2 feet, of continuously running horizontal belt transport adjacent line 46 receives the incoming carriers 22 from the transport switch sections at locations 48 and transports them to a solenoid-operated stop (not shown). The carriers accumulate against the stop until there is approximately 2 /2 feet of carriers. At this time the conveyor storage belt 46 is energized, the solenoidoperated stop is withdrawn, and the 2 /2 foot length of carriers is transferred to the storage belt. The transfer between belts is accomplished by picking up the carrier on the side opposite to that which was being used for transport initially. This is a direct flat-belt to flat-belt transfer.
At the completion of transfer, power is removed from the storage belt 46, the solenoid-operated stop is restored, and the next group of carriers is accumulated. This process continues until the storage line has been filled, at which time the switch on the main transport 32 at point 48 is deactivated and the incoming carriers continue along the main transport 32 to the next storage line.
The high density storage area is also used to store empty carriers. The individually controlled conveyor storage sections advance the empty carriers 22 to the end of the storage line and via the high density level station 54 onto the main transport to the induction stations 10. Initially, empty carriers are supplied from each of the sort destinations to provide room for the incoming carriers. As the sort continues, some loaded carriers are directed to the low density output section 12 with the result that empty carriers 22a will be leaving the high density area 14 at a faster rate than loaded carriers are entering. During this period the control system will remove empty carriers from those sort destinations which are being filled. When the low density sort destinations are swept, empty carriers become available and are transported back to the high density storage area. The empty carriers are directed to the storage lines which have not received any mail. Although not illustrated, it is apparent that if every high density storage line has received mail, an auxiliary path may be required to return empty carriers to the induction stations. D. Low Density Storage The low density storage area, as shown in FIG. 1, consists of five transport levels with each level having a conveyor storage line 36 for each of the sort destinations 12' per level. The storage lines are spaced on I6-inch intervals, and the length of the low density storage area is 84 feet. Each storage line is 30 inches long, sufficient to store forty carriers spaced at three-fourthsinch intervals. The elevation of the five levels is the same as the high density storage area.
Each low density storage line 36 is a horizontal belt transport without teeth. The belt, which is continuously running, receives the carriers from the transport switch at locations 34 along main paths 32 and moves them along the storage line towards a solenoid-operated stop (not shown) similar to the high density mechanization. The carriers 22 accumulate behind the stop until a sweep command is received, at which time the solenoid is activated to remove the stop, and the carriers are transported as a group out of the storage area and onto the main transport path 38 and via level return station 42 and path 40, to the package and labeling station 16. A transport velocity of nine inches per second in the storage and main transport areas allows 30-inch long groups of carriers to travel to the packaging and labeling area with a 30-inch separation distance, for a sweep rate of 540 packages per hour.
A significant advantage of the low density output is the feature which allows mail pieces to continue to enter a sort destination 12' while the sweeping operation is removing the accumulated mail pieces from the opposite end.
E. Induction Station Mail enters the system via the induction stations 10. There is one induction station for each operator, for a total of six identical induction stations in the system illustrated. Each station may be operated independently of any other station. FIG. 8 illustrates the station.
Its major elements consist of an input buffer storage 96, singulator 92, elevator 94, document carrier transport 96, view station 98, and a document carrier encoder 100. Its purpose is to receive stacks of mail, singulate individual mail pieces, insert them into the carrier, present them to the operator for viewing, accept keyboard sorting instructions for each piece, and encode the data onto the magnetic stripe. Each carrier with its flat and destination data is then sent to the distribution system for processing. A description of each of the major elements in the station follows.
The buffer 90 consists of a set of horizontal support belts 11 located in a V-shaped trough 13, capable of supporting up to a 3-foot stack of mail 18. Each mail piece is supported in the vertical plane and rests against its lower edge and leading edge surfaces. The support belts 11 contain teeth similar to timing belts, that prevent relative motion between the belts and the mail stack pieces. These belts are not only located beneath the stack to support the majority of the stack weight, but are also employed in the side wall to support the leading edge of the mail piece. The teeth of the side wall advancement belts aid in keeping the stack vertical at all times. The front of the mail stack rests against, and is supported by, the fixed vertical front support plate 15. The rear of the stack is supported by the stack follower 17. As mail is removed from the front of the stack by the singulator (feeder) 92 using vacuum techniques, the entire stack is incrementally advanced by driving all advancement belts 11, including the side wall belts, and the stack follower 17, in unison. This assures stack integrity during advancement.
A singulator or feeder 92 is provided to individually and successively remove the documents 18 from the buffer to permit them to be further processed in the induction station 10. Such feeder mechanisms are well known in the paper handling arts and special care is taken to avoid skip-feed and double-feed conditions.
The purpose of the elevation station 94 is to lift each document 18 and insert its top edge into the document carrier clip 58. In order that documents of all sizes be approximately centered in the carrier clip, it is necessary to measure the length of each document as it enters the elevation station 94, and then extend the correct one of several document leading-edge stops. To sense the document length, photocell assemblies are used. The first cell is the strobe photocell 25, while the rest are length-detector photocells 27. The document length will be measured as the document trailing-edge restores the light beam to the strobe photocell 25. At this instant, the number of length-detector photocells 27 covered by the document will reveal the documents length. This data is then used to extend the correct one of four solenoid-actuated stops 21.
The document enters the elevation station 94, advanced by the edging rollers 29, until it comes to rest against the selected one of the extended stops 21. Elevation is performed by a set of pusher fingers 31 at tached to timing belts 33. The belts are driven in an intermittent fashion by a motor and a clutch/brake package (neither of which is illustrated).
To elevate the document, the clutch is engaged and the fingers 31 come up between the edging rollers 29 and contact the document 18. The document carrier clip 58 is positioned to receive the document with its clip jaw held open by an energized solenoid 19. The document is elevated until its top edge is at the correct height within the open clip as sensed by a photocell (not shown). At this point, the elevator clutch is deenergized and the brake is applied. The clip solenoid will then be de-energized to allow the spring-loaded clip to close and support the document. Upon command from the viewing station 98, the document carrier transport 96 will then advance, removing the document from the elevation station 94. The elevator clutch will then re-engage to complete the cycle and bring the following set of elevator fingers into position ready to receive the next document.
The document carrier transport 96 consists of a timing belt equipped with attachments 35 capable of supporting document carrier clips. The transport operates in an intermittent fashion by means of a clutch/brake and motor (not shown) to advance documents 18 from the elevation station 94 to the viewing station 98, and then to a removal station 37 where the document carrier clip changes direction and moves past the carrier encoder 100. Document carriers enter the carrier holder attached to. the belt, one at a time, at the elevation station from a carrier storage conveyor 52 (see also FIG. 1).
The carrier storage conveyor 52 consists of a continuously moving flat belt capable of supporting a group of carriers 22. The leading carrier in the stack is prevented from advancing with the belt that supports it by means of a solenoid-actuated stop (not shown). Following carriers simply advance until they contact the stopped carrier in front of them, thus generating a group of carriers. When the elevation station 94 is ready to accept a carrier, the solenoid stop is energized to release the leading carrier. The moving belt supporting the carrier then advances the carrier into position in the carrier holder 35. A fixed stop guide located behind all carrier holders assures that only one carrier enters the transport. The solenoid stop is then deenergized to retain the following carriers before advancement of the documentation carrier commences.
Carriers leave the document carrier transport 96 at the removal station 37. Upon command, a solenoid is energized to push the carrier out of the transport holder in a horizontal plane in a direction 90 to that of the carrier transport motion. The carrier is pushed onto a section of horizontal support conveyor 23 (see also FIG. 1). This conveyor then transports the carrier past the document encoder 100.
Each document is brought to rest in the viewing station 98 where the operator observes the address and enters the appropriate data into an alphanumeric keyboard 39. Upon completion of data entry, the document carrier transport 96 advances, removing the existing document and presenting the following document. It is important to note that the induction station is operator-paced and all mechanisms including the document carrier transport 96, elevator 94, and singulator 92 are sequentially interlocked to one another.
A control and display panel (not shown) is provided to allow the operator to control the induction station and to know the status of its significant elements.
As each document carrier leaves the induction station, it passes the encoder station 100. This station contains a writing head and associated electronics that transfer the appropriate address data to the magnetic stripe 72 (FIG. 6) on carrier 22. The magnetic stripe 72 receives and stores the destination data for the attached document. This results in an escort type of memory control system.
When performing hi-density resorting, documents will enter the induction station 10 via the carrier input conveyor 52 rather than the input buffer storage 90. The buffer 90, singulator 92, and elevator 94 will not be in operation. Instead, the returning document carriers 22 will contain the flats 18 to be resorted. They will engage the document carrier transport 96 one at a time at the position directly above the elevator station 94. They will then be advanced into the viewing station 98 in the same fashion as during primary sorting. The operator will then read the address and enter the proper extraction coding. Upon receipt of the coding, the document will be removed from the viewing station 98 and replaced with the following document. It should be noted that the induction station 10 can easily be made to process hi -density record pass mail without need of an operator, simply be entering all the required address data during the primary sorting operation. Operation of the induction station beyond the viewing station is identical to that described herein before.
F. Output Subsystem The output subsystem 16, performs the functions of removing the flats from the carriers, stacking, labeling, insertion into the packaging machine, and packaging. In summary, the system operates as follows.
Stacks of mail to be packaged and labeled enter the output subsystem as groups of up to 40 mail pieces at one time. Each document is supported on its own carrier. The carrier clip jaws 60 (FIG. 2) are opened one at a time sequentially by the clip-opening roller, to form a stack of mail. This stack then receives a destination label and enters a plastic encapsulation machine where it is wrapped with plastic. The package then passes through a heated shrink tunnel where the plastic wrap is shrunk to produce a tight bundle. The bundle 41 (FIG. 1) is then ready to be conveyed to the system container area and the empty document carriers 22a are rerouted back to the system for reuse.
CONTROL FLOW A number of ancillary operations 'are required in order for the present system to perform the primary operation of sorting flats. A description of the flow of data and material through these operations follows.
With reference to FIG. 9 and general reference to FIG. 1, at the start of operations, transfer of scheme data is required from the Processor Control Device (PCD) 41 which is external to the present Flat Sorting System. This data defines the destinations, label data, packaging requirements, and perhaps quantity distribution for the particular sort scheme to be performed. This transferred data is stored in the Flat Sorting Equipment Control Device (FSECD), comprising computer 43, ready to be used as required for label printing. At this time data storage areas for data logging and status are established, and these areas will be used to accumulate data relative to a particular run.
A. Primary Sorting After the scheme is established, sorting operations can begin. In a primary sort, mail 18 is loaded into each induction station 10 manually. Each mail piece is then automatically moved to the insertion area where as described hereinbefore in connection with FIG. 8, it is centered as a function of electronic measurement, inserted into a waiting carrier 22, and then movedwith its carrier to the keying station where the operator reads the address and enters the required extraction code in the keyboard. When the last data entry is made, the carrier is moved to an adjacent station where it awaits the encoding data on the magnetic stripe. During this period, keyed data is transmitted to the FSECD on request, and then is retransmitted to the PCD 41. The PCD performs a table look-up in memory, determines the destination code (1 of 330 locations in the present system), and transmits this destination code back to the FSECD. The FSECD examines the destination code received and, via a table look-up determines the code format required to route the carrier to the sort location assigned to the specified destination. If a high density area is designated, the FSECD must decide which of the sort locations assigned to the designated destination is to receive the flat. The tally of flats sent to that location is increased for the statistical records. The decision is based on the loading of each area, each of which can hold 1000 flats. Although the nominal requirement is for 3000-piece storage capacity for each destination, any number of 1000-piece storage areas may be assigned to each destination, either dynamically or as specified in the scheme data. This provides areas which can be assigned.
The sort code thus determined must be transmitted to the correct induction station 10. To be sure of this, every transfer of data previously described has been accompanied by additional information which identifies the originating induction station.
When the sort code arrives at the induction station 10, the code 22 is moved through the encoding station (FIG. 8). In the encoder the data is converted from logic ONE and ZERO levels to a special audio tone code. This series of tones is recorded on a stripe of magnetic material 72 (FIG. 3) which is permanently attached to each carrier. The carrier and flat now leave the induction station and prepare to enter the main transport 24 (FIG. 1).
At the main transport 24, each carrier 22 must be merged with the flow from preceding induction stations without interference. At the merge points, sensing devices look for the availability of a valid position on the transport. If such a position is not available, a solenoidactuated mechanism (not shown) prevents the entry of the wating carrier. If, however, a position is open, the mechanism allows the carrier to enter the stream properly synchronized. During the time the carrier is in the sort stream, the computer does not have to be concerned with it, and attention can be turned to controlling sweep operations, induction, and output functions. Control of the flat is now under control of the transport and the individual magnetic code readers 30 (FIG. 6) strategically located at each point where a change in route may take place.
The first potential change in direction can take place at the level select station, comprising gate locations 26 and transports 28. Here the carrier must be diverted to the level determined by its destination. Four solenoidactuated transfer diverter mechanisms of the type shown in FIGS. 6 and 7 perform the mechanical task required. A reader 30 associated with each mechanism interprets the code previously encoded on the carriers magnetic code stripe 72. Three bits in the code specify the level, and thereby the transfer mechanism to be operated.
After a carrier is diverted to the appropriate level, the carrier must select a path through the low density 12 or high density 14 sort areas, and then into the appropriate sort location, 12' or 14'. The decisions at each point are handled in precisely the same manner as in the level selection.
Each low density sort location 12' has a capacity of approximately 40 flats. The quantity sent to any location is accumulated in the computer 43. When this capacity is reached, or when a command from the PCD 41 so designates, a sweep of the location is initiated.
Before actual initiation of sweep, the computer 43 examines special memory areas to be sure no group of flats from another sort location is in the zone adjacent to the output point of the sort location to be swept. If such interference is likely, the sweep initiation is withheld until it can be executed safely. If there will be no interference, the computer generates a start sweep command. This command contains the sort location address and code bits which start the sweep. A similar transmission over the same line, with code bits to terminate a sweep, will be issued when the computer is sure all the flats have left the sort location. This is determined by timing the constant velocity transfer.
Initiation of the sweep, sets the solenoid-actuated transfer mechanism (not shown) at the output side of each sort location so that the carriers are moved via paths 36 onto. the main stream of the transport 38. The carriers remain grouped, and the computer ensures that a gap exists between groups from different sort locations 12. The group is transported to a descending level changer 42, which merges all five levels of the sweep transports into path 40. Tracking of each group allows the computer to halt segments of the transport if interference is expected at the merging point.
If no interference is predicted, the group of flats proceeds to the labeling and packaging area 16. A magnetic code reader is located immediately preceding the entrance into the printer. This reader ascertains the sort location from which the group originated, and transmits the sort code to the FSECD. The FSECD in turn determines the label information required by accessing the table in memory where this infomation was stored during scheme entry. The label data and appropriate print commands are then transmitted to the printer, and a label is produced. Completion of the printing operation initiates transfer of a group of flats to the packaging area where the flats are released from the carriers. The label is deposited and the group of flats is wrapped by the packaging medium, with the label in a visible area.
After packaging, the resulting bundle is transferred from the Flat Sorting Equipment to await further processing. The empty carrier 22a proceeds out of the area and passes a magnetic encoder (not shown) of the type used in the induction station 10. A photocell signals the computer 43 that a carrier is approaching the station. The FSECD determines the storage area to which the carrier is to be sent (perhaps an unused or currently emptying high or low density sort location), and sends a sort code to the encoder, where it is applied to the carriers stripe 72. The FSECD must keep track of the number of empty carriers sent to each location in order to efficiently manage the system,
After leaving the encoder, the empty carrier is transported to a level selector including paths 44 which operates exactly like the unit described earlier. The carrier is diverted to the proper level, merges under sensor control into the main sort stream 32 for that level, and is routed to its coded destination just like a flat-bearing carrier.
B. Secondary Sorting Flats that are sorted into the high density sort area 14 initially must be re-sorted in a finer resolution at some point in the process. The present system is designed to allow flats stored in the high density area 14 to be recirculated past the induction station 10 without removing them from their carriers. A command from the PCD 41 initiates this secondary sort scheme. First, sorting on the primary scheme is terminated, and new sort and label data is transferred from the PCD to the F SECD. The FSECD is notified which flats are to be sorted and the FSECD may notify the operator by a display indication if new operating instructions are required.
The FSECD then determines in which sort location 14 the subject flats are stored, and signals the sweep mechanism with a start sweep code. This code has several variations which allow the FSECD to individually start or stop motion of each of the separately controllable segments of the storage area. The address is, of course, the same as that originally used to sort the flats to this location.
The flats leave the storage area 14 and proceed to a point where the various levels are merged to a single level (level station 54). Merging of individual flats is not a problem here. Secondary sorting applies only to groups of flats with the same primary destination, and hence all are stored on the same level. From the merge point, flats progress to the induction stations it) where each is held until required by an operator.
A demand-controlled transfer mechanism at the input of the induction station switches flats on their carriers into the induction station queue. As each flat reaches the keying station it is read, and the appropriate extraction code is keyed by the operator. The cycle of encoding and sorting is from this point identical to that previously described for primary sorting. The feeding, centering, and carrier insertion has been removed from the procedure, thus eliminating the need for these activities.
CONTROL SYSTEM COMPONENTS The Control System for the present sorting system comprises a number of functional elements, some of which are centrally located, some of which are concentrated locally in specific subsystems, and some of which are distributed throughout the system.
The core of the control system is the Flats Sorting Equipment Control Device (FSECD) shown in FIG. 9, which synchronizes and unites the remainder of the control system into an integrated whole.
A computer 43 provides the FSECD with the ability to flexibly communicate data and commands between the constituents of the sorting system via interface 45 and the Process Control Device (PCD) 41 external thereto.
The computer 43 also performs data translation, such as that required to convert sorting information (destination codes) received from the PCD into the form required to control the sort mechanisms (sort codes), which are sent via interface 47 to the induction stations 10. It controls execution of orders from the PCD, such as commands to sweep sort locations or change sort schemes via interface 49.
A. Central Controls The computer also accepts from PCD and stores (or directs storage of) scheme and label information, and prepares and transmits status and data log information to the PCD. Routing and storage of empty flat carriers are also managed under Program Control by the computer. Several peripheral components are provided to augment the system capabilities. These include a punched card reader 51 for program and data entry, a tape memory 53 for program and data entry, and for program and data base bulk storage, and a printing console 55 to facilitate two-way communication between the system and operating or maintenance personnel.
Special hardware 57 to interface the computer with the remotely located elements of the control system and the PCD, and a display and control panel 59 complete the complement of centrally located control system elements.
B. Display The FSECD incorporates a comprehensive display panel 39 as an aid to monitoring system status. The display system enables the supervisor to determine the load state of each sort location 12' and 14, operating state of each induction station 10, and other significant information.
C. Induction Station and Address Transcription Station Controls The induction station 10 contains logic and electrical controls required to manipulate flats to feed them, in-
sert them in carriers, and move them from station to station. This logic is interlocked with the keying and encoding functions.
Keyboard data (extraction codes and control codes) are buffered and transmitted to FSECD through the locally situated logic. Sort code data from the FSECD is received and formatted in this area, and is used to control the flow of mail as well as the encoder. Each induction station contains a local control panel for power and mode switching and status display.
D. Labeling and Packaging Station Controls Each labeling and packaging station 16 contains logic to control the label printer, flats release mechanism, and packaging mechanism as well as the motion of flats through the station. In addition, a magnetic code reader (not shown) precedes each station 16, and an encoder (also not illustrated) follows it. Data from carriers passing the reader are transmitted to the FSECD where a determination of label information to be printed is made. The correct information is then sent to the printer, where a label is produced and applied to the flats, which have been released from their carriers and await packaging. Packaging is initiated under control of local sensors and logic, and the empty carriers 22a are transported past a special magnetic encoding.
station. At this point a code is applied, under computer cognizance, which will route the carrier to the desired area for storage. The computer 43 retains full knowledge of the quantity and whereabouts of empty carriers.
E. Magnetic Stripe Escort Memory The flat carrier mechanism 22 contains a magnetically encodable stripe 72, which will serve as the sort escort memory for the flat sorter. Systems using magnetic stripe memory technology have been employed in applications such as accounting and banking machines for many years and are well known in the art. Various digital encoding techniques are commonly used in such applications. Although not limited thereto, the present system employs a self-clocking mode in which a data encoding pattern changes state at regular intervals, thereby providing data and synchronization. This technique was chosen because it is insensitive to variations in the alignment of the magnetic stripe across the magnetic head from the encoding station, to any read station. Such misalignments might otherwise cause the read head to miscorrelate information in the clock track with the data on the second track, producing read errors.
Considering factors such as magnetic stripe speed and speed variation, bit density required, and noise immunity, a frequency shift keying method of selfclocking encoding was selected for the present system. In this method, an audio carrier is shifted between two preset frequencies. The frequency to be recorded is selected by the binary data signal the resulting frequency selection corresponding to the O and 1 binary states.
The data pattern to be encoded on the magnetic stripe associated with each carrier is transmitted to the induction station encoders by the FSECD. The binary ls and Os will be recorded on the stripe 72 as tones having different frequencies, and for predetermined portions of the time period allotted to a bit the latter technique providing a means of synchronizing the demodulator clock located at each reader station to the data pattern. The encoders include suitable ampli fier means to provide the proper drive signal to the encoding write head.
Reader amplifiers are provided to demodulate the tone modulated binary signals into ls and Os and also, strobe signals. Means are provided to allow the demodulator circuits to continuously accept data from the sweep mechanism control line except for the period of time during which a carrier passes a read station. The read-out of the carrier information, thus takes precedence over the line data.
Finally, escort memory decoder means are utilized. The decoder accepts the output of the reader amplifier and converts the data into parallel form. A shift register may be used to store this data, and together with associated control logic decodes certain basic functions. For example, a gate code match can be ascertained and operation of a bin or level gate switch initiated. Similarly, a bin code match can be used to start or stop a bin sweep operation. The type of function to be executed by the decode logic is controlled by the format of the data pattern received. Decoded commands are further stored, and the shift register mentioned hereinbefore may be cleared at predetermined intervals. The latter avoids any decoding errors resulting from partial entry of data as might occur if a bin sweep command entry is interrupted by a gate code signal arriving from a carrier stripe or vice versa. Execution of a command is started upon detection of a particular pattern in the shift register, for example, a l bit in both the first and last positions of the register.
F. Distributed Controls The escort scheme for routing and tracking flats through the sorter has the advantages of being essentially immune to variations in transport speed and variations in predicted flat locations which could be caused by transport belt stretch. Each carrier carries with it the code which is written on the tape 72 in the induction station by an encoder 100 as a function of the data transcription and translation process. Each position in the sorter system at which a routing decision must be made has an associated reader capable of interpreting the encoded information and operating the required switching mechanism.
In the present system there are 300 low density sort locations 12 and ninety high density sort locations 14', each of which has a controllable input and output mechanism actuated by a solenoid. The input mechanism is controlled by the reader decoder, which interprets the frequency shift code (tone code) on each carriers magnetic stripe. This information is picked up by a read head 30 and the tone code (two different fre' quencies represent 1 and 0 respectively) is translated to logic 1 and 0 levels. These levels are stored and decoded to determine whether or not a flat (carrier) is to be diverted into the adjacent sort location. A photocell (not shown) near the reader senses the presence of a carrier in front of the reader, and contributes to the logic initialization and decision process.
The output mechanism control must be timed and executed on command of the computer 43. This is necessary to prevent interference between swept flats for different sort locations. If data on the line is in the form of a tone code, an exact analog of the carrier magnetic stripe data exists, and precisely the same tone decoding and code interpretation logic at each location can serve both code reader and transmitted data. The code transmitted by line would, of course, be interpreted to start or stop sweep operations, while the reader codes would operate so as to divert or not divert carriers to the same sort location.
It is important to prevent data from the two sources from interfering with each other. Since there is only one opportunity to read a carrier, that operation is given priority. The reader-associated photocell signal controls this decision so that while a carrier is in the read station, only reader data is switched into the tone decoder. At all other times, line data may enter the tone decoder. If line data is decoded and recognized, a signal is presented to a buss common to all locations. This line is sensed by the computer and recognized as a signal of acceptance. If the signal is not received because a carrier was in the reader during all or part of the transmission, the code is retransmitted until successful. A timed gap between transmissions enables reinitialization of logic.
With respect to control needed for the merging of carriers, it is apparent that the output of each sort location must enter onto a sweep transport without interfering with flats already on the transport. This is accomplished by means of a block or zone control scheme. As each bin is swept, its location is traced by a timing algorithm and/or photo sensing. The location of each group of swept pieces is checked, and future positions are calculated before a new location on the same level is swept. A similar procedure is executed at the level change position to avoid coincidence in that area. Buffer transports may be stopped when required to prevent such accidents.
Merging of flats from the six induction stations into the main stream and from the empty carrier return path to the main stream presents a slightly different situation. In this case, individual carriers must find empty slots on the transport. This is accomplished independent of computer control by sensing empty positions with a photocell and inhibiting transfer of a carrier from one transport to the next until a position is available.
In conclusion, a sorting system has been disclosed which eliminates the deficiencies present in known methods of accumulating sorted articles and of automatically removing them from the system. The inventive concepts and implementations described herein are directed to a system for sorting mail pieces. However, as noted hereinbefore, it should be understood that the system has application in numerous situations where sorting is required, for example, in the handling of luggage at airport terminals or books in a major urban library. In these and other applications, changs and modifications may be necessary in the system implementation taught herein. Such changes and modifications, insofar as they are not departures from the true scope of the invention, are intended to be covered by the claims appendedhereto.
What is claimed is:
l. A system for sorting articles comprising in combination:
carrier means coupled to said articles for providing support therefor and remaining therewith throughout the complete sorting process, each of said carrier means being comprised of a T-shaped upper section and a lower section for clamping at least one of said articles, said upper section having a spring-loaded clamp release lever protruding therefrom and being operatively connected to the clamping means in said lower section,
transport means for transporting said carrier means to predetermined sort destinations and providing storage therefor at said destinations,
escort memory means affixed to each of said carrier means and possessing information as to the sort destination therefor,
gating means operatively positioned with respect to said transport means and responsive to the information contained in said escort memory means for switching said carrier means among a plurality of transport paths to achieve said predetermined sort destinations.
2. A system as defined in claim 1 wherein said transport means comprises a monorail conveyor suspension system having a plurality of friction belts arranged to support, transport and store said carrier means.
3. A system as defined in claim 2 further characterized in that said plurality of friction belts include belts arranged respectively with their flat surfaces lying in horizontal and vertical planes, the lower surface on either side of the T-shaped section of said carrier means being adapted to selectively contact one of said belts, the belts having vertically oriented surfaces being utilized for direction changes of said carrier means in a horizontal plane, respective horizontally and vertically oriented belts being positioned in close proximity to each other and having a preselected elevation with respect to each other at predetermined portions of said transport paths such that an unconditional transfer of carrier means is accomplished from one belt to the other by the shifting of original contact with one belt by one side of said carrier means T section to contact with the other belt by the opposite side of said T section.
4. A system as defined in claim 3 wherein said gating means comprises a vane-like member conditionally actuated in accordance with the sort destinations stored in said escort memory means, said vane being situated on one side of a horizontally oriented belt and being adapted when actuated to extend into the path of said carrier means and to engage one extremity of said T section, said carrier means being thereby deflected in a direction to cause the opposite extremity of said T section to contact a vertically oriented belt for transporting said carrier means to its sort destination, said vane when in an unactuated condition, permitting said carrier means to continue uninterrupted on its original transport path.
5. A system as defined in claim 4 wherein said escort memory means comprises a magnetic stripe mounted on the surface of said carrier, the sort destination of said carrier being encoded on said stripe, a magnetic code reader operatively connected to read the information encoded on said stripe and solenoid means responsive to said reader for actuating said vane-like member.
6. A system as defined in claim 5 wherein the friction belts used to transport said carrier means to said sort destinations are timing belts having a plurality of uniformly spaced teeth and said belts used for storage in said sort destinations are characterized by the absence of said teeth and the resultant close packing of said carrier means.
7. A system as defined in claim 6 wherein the lower surface on either side of the T-shaped section of said carrier means comprises toothed sections adapted to mesh with the teeth of said timing belts.
8. A system as defined in claim 7 wherein said sort destinations are comprised of a high density storage section capable of accommodating a large number of carrier means in a relatively small number of sort destinations for a primary sort and a low density storage section capable of accommodating a smaller number of carrier means in a relatively large number of sort destinations for a secondary sort.
9. A system as defined in claim 8 wherein said storage sections are each comprised of a plurality of spacedapart vertically mounted transport levels each having a transport path for each of the sort destinations on a level.
10. A system as defined in claim 9 further including a control subsystem comprising a computer and a plurality of interface modules for communicating data and commands between the constituents of said system.
11. A system as defined in claim 10 further characterized in that said transport means are adapted to sweep a preselected sort destination in response to a command from said control subsystem.
12. A system for sorting mail pieces comprising in combination:
carrier means coupled to said mail pieces for providing support therefor and remaining therewith throughout the complete sorting process,
transport means for transporting said carrier means to predetermined sort destinations and providing storage therefor at said destinations,
escort memory means affixed to each of said carrier means and possessing information as to the sort destination therefor,
gating means operatively positioned with respect to said transport means and responsive to the information contained in said escort memory means for switching said carrier means among a plurality of transport paths to achieve said predetermined sort destinations,
an induction station including input buffer means for temporary storage of said mail pieces to be sorted, singulator means positioned in proximity to said buffer means and operatively connected to separate said mail pieces one from the other, means for attaching each of said mail pieces to one of said carrier means, a transport loop having a plurality of brackets capable of supporting said carrier means, a viewing station located along the path of said transport loop for permitting a determination of the sort destination of each mail piece, and means for encoding the sort destination information upon the escort memory means associated with each of said mail pieces,
. said input buffer means comprising a V-shaped trough for supporting the leading and lower edges of a plurality of said mail pieces, the respective support surfaces of said trough including toothed belts, the belts in the side wall of said trough contacting the leading edge of said mail pieces thereby causing the mail stacks to maintain a vertical orientation, said belts being adapted to be driven in unison in a direction to advance said mail pieces toward said singulator means.