Apparatus and method for positioning objects/mailpieces

An apparatus and method for positioning objects at a desired reference position, including a sensor for determining the length of each object/mailpiece from a leading to a trailing edge, a transport mechanism having a positionable drive element for transporting the object/mailpiece, and a controller or processor for controlling the position of the drive element to release the object/mailpiece at a desired reference position. The described embodiments of the invention relate to positioning an object/mailpiece in a clamp assembly of a mixed mail sorter. The jaws of the clamp assembly are separated to receive the object/mailpiece by a pair of spiral cams. The spiral cams interpose and engage tabs of each jaw to open and close the clamp assembly as they concomitantly effect translation of the clamp assembly linearly past the positioning apparatus. The apparatus and method ensures predictable conveyance and release of objects/mailpieces while being manipulated by automated handling equipment.

TECHNICAL FIELD

This invention relates to conveying/positioning objects/mailpieces, and, more particularly, to an apparatus and method for positioning/centering objects/mailpieces to a desired reference position. The objects/mailpieces may be positioned in a clamping assembly employed in a mixed-mail sorting apparatus.

BACKGROUND ART

The 2003 Presidential Commission Report on the Future of the USPS concluded that the Postal Service should continue to develop effective mailstream merging systems that optimize efficiency, e.g., maximize the number of mailpieces shipped with each mile traveled, while minimizing the labor content associated with mailpiece handling. With respect to the latter, all elements of the mail stream (letters, flats, periodicals, post cards, etc,) should be sorted, merged, and/or sequenced with the expectation that no subsequent handling would be required at each of the local postal branch offices, i.e., other than the physical delivery to the recipient address.

Most postal services are actively exploring opportunities to reduce the overall cost of processing mail by investing in postal automation equipment, particularly in postal automation associated with mailpiece sorting processes. While significant progress has been made sorting conventional letter-size mailpieces, the remaining mailpieces, e.g., magazines, periodicals, newspapers, catalogues and other flats-size mailpieces, often are not machinable and must be hand sorted. While only twenty-percent (20%) of the mailstream may be catagorized as “non-machinable”, the time required to handle and sort such mailpieces is equal to or greater than the time spent sorting the other eighty percent (80%) of the mailstream.

Certain mailpieces are deemed non-machinable for two principal reasons. First, singulating mailpieces such as magazines and newspapers can present difficulties inasmuch as a portion of these mailpieces are unbound or unconstrained, that is, they have free-edges. As such, even small shear forces applied for the purpose of separating the mailpieces, can cause individual sheets or pages to be wrinkled, torn or otherwise damaged. Secondly, when such mailpieces are handled in the feeder, individual sheets or pages are prone to jam during sorting operations.

To combat the difficulties associated with handling these mailpieces, the mail entering automated postal equipment must be “prepared”, before sorting operations can begin. Preparation may include a process of culling mailpieces which are likely to stall or jam the sorting equipment, or, alternatively, packaging mailpieces so as to facilitate separation and/or reduce the propensity for jamming. For example, magazines or newspapers may be wrapped or enclosed within a larger envelope to capture or contain the free-edges of the mailpiece. While these activities can prepare mailpieces for automated processing, the labor expense can completely offset or nullify the fiscal benefits derived by such automated handling equipment.

The following documents disclose various systems and subsystems of a mail sorter capable of handling all varieties of mail, i.e., a mixed-mail sorter: WO 2006/063204, WO 2006/063121, WO 2006/063125, WO 2006/110486, WO 2006/110465, and WO 2006/110484. One of the most essential features of the mixed mail sorter relates to the use of a clamping assembly operative to secure, transport, divert, sort and release the mailpieces. in addition to its principle mechanical functions, the clamps also include a means to uniquely identify the clamp and its associated mailpiece. As such, the sorting operation may be performed by a combination of requisite information, i.e., electronically scanned information in connection with the mailpiece (e.g., its destination address) together with the unique identifier of the clamp. Further, the sorting process may be performed without altering/marking the mailpiece, such as via a printed barcode symbology or other identification mark.

Having described the functional significance of the clamping assembly, it will also be appreciated that a mailpiece should be centered within a clamp assembly to obviate certain handling difficulties/inconsistencies. More specifically, it will be understood that the gravitational center of the combined clamp/mailpiece assembly will rotate about the overhead conveyor bar (i.e., acting as a support pivot) such that all moments/forces are in equilibrium. When the centroid of the mailpiece is misaligned relative to the centerline of the clamp assembly, the combined clamp/mailpiece assembly may assume a skewed orientation (i.e., relative to the vertical) when the assembly is hung from the overhead conveyor bar. As such, difficulties may arise when attempting to divert the mailpiece to a subsequent conveyor bar or release the mailpiece into a bin/container.

While, in prior art mail sorters, it is generally known to align mailpieces along one or two edges, e.g., in register along adjacent edges or along a corner thereof, no methods or systems are currently available to accurately center a mailpiece within a clamp assembly. That is, there has been no physical requirement, heretofore, to align the geometric center or centroid of a mailpiece with the gravitational center of the clamp assembly.

A need, therefore, exists for an apparatus and method for positioning or centering an object/mailpiece to a desired reference position so as to ensure predictable conveyance and release of objects/mailpieces while being manipulated by automated handling equipment.

SUMMARY OF THE INVENTION

An apparatus and method are provided for positioning objects at a desired reference position, including a sensor for determining the length of each object/mailpiece from a leading to a trailing edge, a transport mechanism having a positionable drive element for transporting the object/mailpiece lengthwise in succession along an object/mailpiece transport path, and a controller or processor for controlling the position, of the positionable drive element to release the object/mailpiece at a desired reference position. The described embodiments of the apparatus and method relate to positioning an object/mailpiece in a clamp assembly of a mixed mail sorter. The jaws of the clamp assembly are separated to receive the object/mailpiece by a pair of spiral cams. The spiral cams interpose and engage tabs of each jaw to open and close the clamp assembly as they concomitantly effect translation of the clamp assembly linearly past the positioning apparatus. The apparatus and method ensures predictable conveyance and release of objects/mailpieces while being manipulated by automated handling equipment.

DETAILED DESCRIPTION

The present invention is described in the context of an apparatus and system having a clamping assembly for securing, transporting, sorting and diverting mailpieces. While the invention is advantageous for mixed mail sorters, it should be appreciated that the apparatus and method for centering mailpieces is applicable to any apparatus which may employ a clamping assembly for acquiring and transporting objects.

The apparatus according to the present invention transports objects to a desired reference location or position. InFIGS. 1A and 16, the positioning apparatus10is integrated within a mixed mail sorter for transporting mailpieces12to a clamp assembly14. The mixed-mail sorter may be similar to that illustrated and described in the following documents: PCT/US2005/044560, now WO 2006/063204; PCT/US2005/044406, now WO 2006/063121; PCT/US2005/044413, now WO 2006/063125; PCT/US2006/01892, now WO 2006/110486; PCT/US2006/012861, now WO 2006/110465; and PCT/US2006/012888, now WO 2006/110484, said applications being hereby incorporated by reference in their entireties.

The positioning apparatus10of the present invention enables processing of multiple objects/mailpieces12which may vary in size/shape and which may be advanced to positioning apparatus10via automated or manual delivery systems (not shown). With respect to size and shape variation, objects/mailpieces12for sorting using the mixed mail sorter may include conventional letter size envelopes, postcards, magazines, newspapers, flats-type mailpieces, etc. Furthermore, such objects/mailpieces may include a variety of packages including blow molded plastics and other objects suitable for pick-and-place handling equipments. Hence, for the purposes of this invention, the terms “object” and/or “mailpiece” will be used interchangeably and are intended to include letters, packages and parcels suitable for automated handling by a clamp assembly14.

Regarding preprocessing of mail, the positioning apparatus10may be integrated with a variety of automated or manual delivery systems, upstream of the various sorter subsystems. InFIGS. 1A and 1B, the positioning apparatus10is capable of loading, transporting and clamping a variety of mailpieces12from a plurality of handling systems. For example, certain letter sized mailpieces12may be most efficiently preprocessed (i.e., presorted and singulated) by conventional automated feeders while yet other mailpieces12, such as conventional newspapers, may best be manually handled (manually singulated and fed onto the transport) by an operator.

Generally, it is desirable to match the handling rate of the positioning apparatus10with the feed rate that objects/mailpieces12are fed to the positioning apparatus10. For mailpieces up to 0.35 inches, the mixed mail sorter can handle objects/mailpieces at a rate of about eighteen-thousand (18,000) pieces per hour. Inasmuch as some of the most efficient automatic flats feeders can only feed at a rate of about seventy-five hundred (7,500) pieces per hour, the input rate of the feeder limits the output handling rate of the positioning apparatus10and the sortation rate of the sorter. Consequently, multiple input feed systems can be employed to match the handling rate of the positioning apparatus10and sortation rate of the sorter. For example, two automated flats feeders can be combined to increase the handling rate to at least fifteen thousand (15,000) mailpieces. Furthermore, since certain mailpieces are best fed manually (i.e., operator assisted), both automated and manual input feed systems may be combined to best match the handling/sortation rate of the positioning apparatus10and mixed mail sorter. A buffer module (not shown) can be incorporated and used by a system controller to monitor and control input traffic.

The top and profile views shown inFIGS. 1A and 1B, respectively, show a sensor20for determining the length of each object or mailpiece12from a leading edge12LE to a trailing edge12TE thereof, a transport mechanism30having a positionable drive element30PE for transporting the object or mailpiece12, and a controller or processor40for controlling the position of the drive element30PE to release the object or mailpiece at a desired reference position RP. InFIG. 1B, the reference position RP is shown as the centerline of a clamp assembly14, though the reference position can be any desired location depending upon the configuration of the clamp assembly14, and/or the desired spatial relationship between the object/mailpiece12and the clamp assembly14.

In the described embodiment, the length sensor20can be any of a variety of sensing devices. For example, a photocell24(seeFIG. 1B) can be employed to view the time-differential between the leading and trailing edges12LE,12TE of the mailpiece12. That is, the photocell24in combination with a velocity transducer (not shown) for measuring the speed of the transport mechanism30may be used to issue a length signal to the controller40. Alternatively, if the velocity of the transport is known, the sensor can transmit change-of-state signals indicating the time of the lead and trail edges of the mailpiece passed by the sensor, and the controller40can calculate the mailpiece length using the known transport velocity.

More specifically, inFIGS. 2 and 3, the transport mechanism30may comprise two transport segments, i.e., a constant velocity transport segment32and a variable velocity transport segment34. The transport mechanism30may further comprise pairs of aligned transport belts32B,34B for transporting mailpieces12lengthwise in succession along a transport path and delivering the mailpieces12to the clamp assembly14. Rollers36a,36b,36cand36P may be disposed in combination with the transport belts to effect frictional engagement of the mailpiece12with each of the transport belts32B,34B. As such, the rollers36a,36b,36cand36P function as spring loaded nips to press the mailpiece12with frictional engagement with transport belts32and34, and thereby provide drive force to mailpiece12.

In the illustrated embodiment, shown inFIG. 2, the positionable drive element30PE may include any of a variety of mechanisms for positioning a roller so as to release the mailpiece12at the desired reference position. More specifically, and referring toFIGS. 3,4A and4B, the length sensor20provides a length signal to the controller40. Controller40issues a command to motor43to turn lead screw41, which causes carriage44to translate, and thereby to move the roller36P, forward or aft. In the described embodiment, a link42connects the roller36P to carriage44to move the roller36P in the direction of arrows A. With data obtained from the length signal, the position of the roller36P may be determined such that the trailing edge12TE of the mailpiece12(seeFIG. 3) is released when the mailpiece12has reached its desired reference position RP. In the described embodiment, the desired reference position RP corresponds to alignment of the area centroid12CEN or the mailpiece12with the gravitational centerline14CL of the clamp assembly14(seeFIG. 4B).

To further control the position of the mailpiece12, the second transport segment34may include a means for varying the velocity of the belts34B. As such, the speed, and consequently, the inertia of the mailpiece12may be reduced so that the mailpiece remains in the desired reference position once it is released by the positionable drive element30PE. The variable velocity drive means (not shown) may also be controlled by signals derived from the controller40.

While a principle feature of the invention relates to the sensing, positioning and control elements for positioning an object at a desired position, the system for opening the clamp assembly14has its own inventive features. InFIGS. 5,6A and6B, the clamp assembly14includes a drive mechanism50having a pair of rotating spiral cams52a,52bfor separating and closing the jaws54a,54bof the clamp assembly14. More specifically, the jaws54a,54bof the clamp assembly14each include separation tabs56a1,56a2,56b1,56b2formed along a lateral edge of each clamp assembly jaw54a,54b. Furthermore, spiral cam surfaces52sc1,52sc2, of each of the spiral cams52a,52binterpose the separation tabs56a1,56a2,56b1,56b2such that rotation of the spiral cams52a,52b, effects opening and closure of the clamp assembly jaws54a,54b(best seen inFIGS. 5,6A and6B). Moreover, rotation of the spiral cams52a,52effects linear translation of the clamp assembly14in the direction of arrow FP along the length of the drive mechanism50. This linear translation is synchronized with clamp transport elements60aand60b. Such translation moves the mailpiece12away from the belts34B of the transport mechanism30to obviate any further motion or displacement once the mailpiece has reached its desired reference position RP. This motion, in a direction transverse to the lengths of the mailpieces and, more particularly, perpendicular to the direction of transport30, also enables a next mailpiece13to be positioned in the next clamp53.

In summary, the apparatus and method for positioning/centering objects/mailpieces includes a novel positionable drive element to release the object/mailpieces at a desired reference position. The invention includes a variable velocity transport mechanism to decrease the speed and inertia of the object/mailpiece as it comes to rest in the clamp assembly jaws. Furthermore, the clamp assembly includes an inventive drive mechanism operative to open and close the clamp assembly jaws as the object/mailpiece is conveyed away from the transport mechanism and to subsequent stations of the mixed mail sorter. Consequently, the apparatus and method ensures predictable conveyance and sorting of objects/mailpieces while being manipulated by automated handling equipment.

Although the invention has been described with respect to a particular embodiment thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention.