Electrodynamic propulsion system for conveying sheet material

A transport system for conveying sheet material along a feed path. The transport system includes an electro-dynamic propulsion system for moving sheet material, or a stacked collation of sheet material, along a support deck which defines the feed path. More specifically, the electro-dynamic propulsion system includes at least one guideway and a ferromagnetic element disposed internally of the guideway. The guideway includes a magnetic coil to produce a variable magnetic field. By varying the flux density and polarity of the magnetic field the ferromagnetic element may be propelled within the guideway. An abutment member is coupled to the ferromagnetic element, extends through the elongate opening of the support deck and engages an edge of sheet material. A processor is operative to control the electro-dynamic propulsion system and, accordingly, the rate of travel and position of the sheet material along the feed path.

FIELD OF THE INVENTION

The present invention relates to apparatus for conveying sheet material and, more particularly, to an apparatus for transport and/or alignment of sheet material, multi-sheet collations and other media items.

BACKGROUND OF THE INVENTION

Various apparatus are employed for arranging sheet material in a package suitable for use or sale in commerce. One such apparatus, useful for describing the teachings of the present invention, is a mailpiece inserter system employed in the fabrication of high volume mail communications, e.g., mass mailings. Such mailpiece inserter systems are typically used by organizations such as banks, insurance companies and utility companies for producing a large volume of specific mail communications where the contents of each mailpiece are directed to a particular addressee. Also, other organizations, such as direct mailers, use mail inserters for producing mass mailings where the contents of each mailpiece are substantially identical with respect to each addressee. Examples of inserter systems are the 8 series, 9 series, and APS™ inserter systems available from Pitney Bowes Inc. located in Stamford, Conn., USA.

In many respects, a typical inserter system resembles a manufacturing assembly line. Sheets and other raw materials (i.e., a web of paper stock, enclosures, and envelopes) enter the inserter system as inputs. Various modules or workstations in the inserter system work cooperatively to process the sheets until a finished mailpiece is produced. The precise configuration of each inserter system depends upon the needs of each customer or installation.

Typically, inserter systems prepare mailpieces by arranging preprinted sheets of material into a collation, i.e., the content material of the mailpiece, on a transport deck. The collation of preprinted sheet may continue to a chassis module where additional sheets or inserts may be added to a targeted audience of mailpiece recipients. From the chassis module, the fully developed collation may continue to a stitcher module where the sheet material may be stitched, stapled, or otherwise bound. Subsequently, the bound collation is typically folded and placed into envelopes. Once filled, the envelopes are conveyed to yet other stations for further processing. That is, the envelopes may be closed, sealed, weighed, sorted and stacked. Additionally, the inserter may include a postage meter for applying postage indicia based upon the weight and/or size of the mailpiece.

The mailpiece collation may comprise several individualized documents, i.e., specific to a mailpiece addressee, and/or one or more preprinted inserts which may be specifically tailored to the addressee. Generally, a barcode system is employed to command various sheet feeding mechanisms (i.e., one of the components of the chassis module mentioned in the preceding paragraph) to feed/add a particular insert to a collation. Of course, the mailpiece collation may comprise any combination of sheet material, whether they include personalized documents, preprinted inserts or a combination thereof.

FIGS. 1a-1cshow the relevant components of a prior art chassis module/station100of an inserter system. The figures show the chassis module100conveying a sheet material112along a transport deck114(omitted fromFIG. 1ato reveal underlying components). The transport deck114includes a drive mechanism116for displacing the sheet material112as it slides over the transport deck114. InFIG. 1c, the transport deck114includes a low friction surface114S having a pair of parallel grooves or slots114G formed therein. Riding in the grooves or through the slots114G are fingers116F which extend orthogonally from the surface114S of the deck114.

Referring toFIGS. 1a-1c, the fingers116F are driven by a belt or chain118C1, which in turn wraps around a drive sprocket or gear118G. Furthermore, the fingers116F1are spaced in equal length increments while the fingers116F2, of adjacent chains118C1,118C2are substantially aligned, i.e., laterally across the transport deck114. As such, a substantially rectangular region or pocket is established between the fingers116F1,116F2.

Above the transport deck114are one or more feeder mechanisms120A,120B (two are shown for illustration purposes) which are capable of feeding inserts122, i.e., sheet material, to the transport deck114. The inserts122may be laid to build a collation112or may be added to the sheet material112(i.e., a partial collation) initiated upstream of the transport deck114. A controller (not shown) issues command signals to the feeder mechanisms120A,120B to appropriately time the feed sequence such that the inserts122are laid in the rectangular region124between the fingers116F1,116F2. More specifically, as each pair of lateral fingers116F1,116F2is driven within the grooves or slots144G, one edge of the sheet material112is engaged to slide the collation112along the transport deck114. As the sheet material112passes below the feeding mechanisms120A,120B, other sheets or inserts122are added. At the end of the transport deck114, the fingers116F1,116F2drop beneath the transport deck114such that the collation (i.e., the combination of the sheet material and inserts122) may proceed to subsequent processing stations.

While the drive mechanism116of the prior art provides rapid transport of collated sheet material112,122and has proven to be effective and reliable, sheets or inserts122fed by the feeding mechanisms120A,120B can become misaligned in the rectangular space or pocket124provided between the fingers116F1,116F2. That is, inasmuch as the pocket124is oversized to accept the sheets or inserts122, the inserts122can become misaligned due to a lack of positive registration surfaces on all sides of the collation112,122.

Various mechanisms are employed to vary the pocket size, i.e., sometimes referred to as the “pitch”, between the chassis fingers. The ability to change pitch not only enables greater efficiency, i.e., a greater number of pockets for inserts, but also minimizes the misalignment of inserts being laid on a collation. Notwithstanding the ability to minimize pocket size, it will be appreciated that without positive restraint on all free edges of the collation, individual sheets or inserts will be misaligned. Consequently, prior art inserters commonly employ complex registration mechanisms or jogging devices to align the free edges of a collation. For example, inserters may employ a series of swing arms which pivot onto the transport deck, i.e., into the conveyance path of the collation. The swing arms engage and align the leading edge of a collation, i.e., the edge opposite the fingers. While the swing arms effectively maintain alignment of the collation, the mechanical complexity associated with the pivoting mechanism is a regular source of maintenance, jamming or failure.

In the absence of such swing arms, an inserter may employ other jogging mechanisms downstream of the chassis module to align the edges of the collation. That is, before subsequent processing, e.g., stitching or enveloping, the edges of the collation are aligned to: (i) ensure that stitching does not result in permanent misalignment of the collation or (ii) provide a smooth transition and/or snug fit within a mailing envelope. Such jogging mechanisms often employ a complex arrangement of solenoid activated stops which tap or “jog” each edge by a predetermined displacement with each motion of the stop. By jogging the stops several times, the edges of the collation are aligned. Like the swing arm mechanisms described above, the jogging mechanisms are highly complex and prone to increased maintenance, jamming and failure.

A need, therefore, exists for a transport system for sheet material which eliminates mechanical complexity, enhances reliability and minimizes maintenance.

SUMMARY OF THE INVENTION

A transport system is provided for conveying sheet material along a feed path. The transport system includes an electro-dynamic propulsion system for moving sheet material, or a stacked collation of sheet material, along a support deck which defines the feed path. More specifically, the electro-dynamic propulsion system includes at least one guideway and a ferromagnetic element disposed internally of the guideway. The guideway includes a magnetic coil to produce a variable magnetic field. By varying the flux density and polarity of the magnetic field, the ferromagnetic element may be propelled within the guideway. An abutment member is coupled to the ferromagnetic element, extends through the elongate opening of the support deck and engages an edge of sheet material. A processor is operative to control the electro-dynamic propulsion system and, accordingly, the rate of travel and position of the sheet material along the feed path.

DETAILED DESCRIPTION

The present invention will be described in the context of a mailpiece inserter for processing mail communications. It should be appreciated, however, that the inventive transport system is broadly applicable to any apparatus/system which conveys sheet material, or a collation of stacked sheets, along a feed path. In the context used herein, “sheet material” means any sheet, page, document, or media wherein the dimensions and stiffness properties in one dimension are a small fraction, e.g., 1/100th, of the dimensions and stiffness characteristics of the other dimensions. As such, the sheet material is substantially “flat” and flexible about axes parallel to the plane of the sheet. In addition to individual sheets of paper, plastic or fabric, objects such as envelopes and folders may also be considered “sheet material” within the meaning provided herein. Furthermore, the terms “sheet”, “sheet material”, “media item”, and “content material” (i.e., when referring to sheets to be inserted within a mailpiece envelope) may be used interchangeably herein.

In the broadest sense of the invention, a transport system is provided which employs an Electro-Dynamic Propulsion (EDP) system to provide the motive force for conveying a sheet of material, or a stacked collation of sheet material. The EDP system develops a magnetic field which propels and/or positions ferromagnetic elements within an elongate channel therein. The ferromagnetic elements are coupled to abutment members or fingers which engage an edge of the sheet material through openings formed in a support deck. A processor controls the motion/position of the ferromagnetic elements to transport the sheet material along a feed path defined by the support deck.

InFIGS. 2,3and4, an exemplary embodiment of a transport system10according to the present invention is shown. The transport system10is operative to convey sheet material, or stacks of sheet material12, along a support deck14which defines a feed path FP. The support deck14includes one or more elongate openings or slots16which are generally parallel to each other and/or parallel to the feed path FP. Further, the elongate slots16essentially extend the entire length of the feed path, or the travel length along the support deck14. In the described embodiment, the support deck14includes two (2) closely-spaced pairs of elongate slots16a,16b(discussed in greater detail below) which (i) produce variable size pockets for conveying sheet material12, (ii) jog the edges of sheet material to register the sheets of a stacked collation, and (iii) correct the orientation of sheets and/or stacked collations12which have been become misaligned during transport.

An Electro-Dynamic Propulsion (EDP) system20is located adjacent, e.g., beneath, the support deck14and includes an assembly housing22which collectively supports the various EDP system elements. More specifically, the EDP system20includes one or more guideways24each having one or more ferromagnetic elements26disposed therein. In the described embodiment, a guideway24is disposed beneath, and corresponds to, each of the elongate slots16, i.e., a guideway24is formed beneath each of the elongate slots16. Furthermore, each guideway24contains a plurality of ferromagnetic elements26which are longitudinally spaced-apart along the length of the guideway24.

Moreover, each guideway24includes a guideway channel24C and a magnetic coil28surrounding, e.g., imbedded within, the sidewalls24S of the channel24C. The magnetic coil28includes a propulsive coil28adisposed along each side of the guideway channel24and a suspension coil28bdisposed along the top and bottom of the guideway channel24. While the magnetic coil28may be configured in a variety of ways, the coil28generally includes plurality of windings capable of generating a controllable magnetic field which produces multiple polar regions. That is, the windings are configured, i.e., wound in a continuous series of loops, to produce a combination of steady and alternating polar regions which may be varied in intensity and direction. A processor30controls the magnitude and polarity of the magnetic field such that a flowing wave, e.g., sinusoidal wave, of polar crests and troughs are produced within and around the ferromagnetic elements26.

InFIGS. 4,5and6, each ferromagnetic element26is fabricated to form a permanent magnet, i.e., a magnet having a prescribed molecular alignment. The poles NF, SF(seeFIG. 5) of each ferromagnetic element26are responsive to, or interact with, the magnetic field MF of the propulsive coils28asuch that each element26IS propelled within the guideway24. The processor30causes the magnetic field MF of the propulsive coil28ato develop north and south polar regions NG, SGat various locations with respect to each ferromagnetic element26. At one location, e.g., aft of the ferromagnetic element26, a first magnetic field MF1may be produced such that the north pole NGleads the south pole SG, i.e., from left to right, inFIG. 5. At another location, e.g., forward of the ferromagnetic element26, a second magnetic field MF2may be produced such that the north NGtrails the south pole SG. The polar north NGof the first magnetic field MF1causes the north pole NFof the ferromagnetic element26to be repelled from left to right, inFIG. 5, i.e., in the direction of arrow F. Further, the polar north NGof the second magnetic field MF2causes the south pole SFof the ferromagnetic element26to be attracted or pulled from left to right, thereby augmenting the propulsive forces F applied to the ferromagnetic element26.

From the foregoing, it will be appreciated that the position and rate of travel of the ferromagnetic elements26along the feed path FP is dependant upon the control of the coils28a,28b. That is, the position and speed of the ferromagnetic elements26is dependant upon the location and rate of change of the magnetic fields MF1, MF2, i.e., the rate that the magnetic fields MF1, MF2are shifted in toward or away from each ferromagnetic element26. Accordingly, the longitudinal position of the ferromagnetic elements26, the relative position of the elements26within the same guideway (i.e., the spacing between ferromagnetic elements26), the position of one element26in a first guideway24relative to the position of another element26in an adjacent or second guideway24, and the rate of travel may be precisely controlled.

Inasmuch as the control of an electro-dynamic suspension system (conventionally associated with the levitation and locomotion of large/heavy objects such as passenger trains or carting systems) is well-known in the art, further detailed description of the control algorithms is omitted to facilitate the description. That is, a description of the program logic/code to move or position a ferromagnetic element within a guideway is not necessary to appreciate or practice the teachings of the present invention. In fact, the diminished scale and size of the EDP system20described herein greatly simplifies the typical design challenges associated with the control of objects requiring extraordinarily large forces to accelerate/decelerate objects with such large inertial mass.

Continuing now with our description of the transport system10, inFIG. 6, an abutment member34is attached to each ferromagnetic element26, i.e., to a surface facing a respective elongate slot16. Each abutment member34includes a T-shaped staff or flag36which extends though the elongate slot16and defines a drive surface38D on one side thereof and a registration surface38R on its opposing side. The drive surface and registration surfaces38D,38R are generally orthogonal to the support deck14and are operative to engage an edge of the sheet material12. The function of each of the surfaces38D,38R will be discussed in greater detail below, though, at this juncture in our discussion, it is suffice to say that the drive surface and registration surfaces38D,38R are operative to transport the sheet material along the feed path FP and/or align the edges of a collation of sheet material12.

In operation and referring toFIGS. 6 and 7, the processor30controls the EDP system20such that magnetic fields developed by the coils28a,28bof the guideway24produce forces operative to the ferromagnetic elements26. While the ferromagnetic elements26may slide along the guideway channel24C, e.g., top and bottom sidewalls thereof, the ferromagnetic elements26may be levitated by the suspension coil28bto reduce or eliminate friction. As the ferromagnetic elements26move, the drive surfaces38D of the abutment members34engage a trailing edge of the sheet material/stacked collation12for transport along the feed path FP.

The ferromagnetic elements26and associated abutment members34may be controlled and positioned to define rectangular pockets for retaining sheet material therebetween. In the described embodiment, four (4) abutment members34are employed to define the sheet material pocket, i.e., two (2) abutment members34positioned along the trailing edge TE and two (2) members34located along the opposing leading edge LE. While creating a transport pocket may be useful for retaining and transporting a single sheet of material12, its principal use relates to registering the sheets of a stacked collation. With respect to this operating mode, the processor30first controls the EDP system20such that the spacing between the drive and registration surfaces38D,38R is enlarged or larger than the length dimension L1of the sheet material to be laid therebetween. As sheet material12is added to build a stacked collation, the registration surfaces38R may be bi-directionally oscillated, i.e., in the direction of arrow JS (seeFIG. 6), to jog the edges of the sheet material12. It should be noted that the bi-directional oscillation of a pair of abutment members34can occur while the stacked collation is transported by the drive surfaces38D of an opposing pair of abutment members34.

In another embodiment of the invention, the processor30may control the EDP system20such that THE relative position of a first pair of opposing abutment members34O1are moved, forward or aft, relative to a second pair of opposing abutment members34O2. While in the described embodiment, the opposing pairs34O1,34O2are each in different guideway channels24C, it should be appreciated that they may be located in the same guideway channel24C. Should the sheet material/stacked collation12become misaligned, the processor30may control the EDP system20to incrementally increase the velocity of the first pair of abutment members34O1(denoted by the delta Δ+V symbol inFIG. 7) while incrementally decreasing the velocity of the second pair of abutment members34O2(denoted by the delta Δ−V symbol inFIG. 7). By increasing or decreasing the velocity of the first or second pairs of abutment members34O1,34O2, the sheet material/stacked collation12may be rotated and brought back into the proper transport alignment, i.e., the desired angular position.

While misalignment of the sheet material or stacked collation12may be detected using a variety of sensing devices, the described embodiment depicts two (2) rows or arrays of laterally-spaced optical sensors OS1, OS2. The optical sensors OS1, OS2sense an actual angular position AP of an edge LE of the sheet material12, and issue an orientation signal indicative thereof. The processor (not shown inFIG. 7) stores prescribed position data indicative of a desired angular position DP of the sheet material12and is responsive to the orientation signal for (i) comparing the actual angular position AP to the desired angular position DP, (ii) calculating a difference value therebetween, and (iii) issuing an error correction signal, based upon the difference value, to the vary the position of the ferromagnetic elements26. As mentioned in the preceding paragraph, this may be performed by increasing or decreasing the velocity of the first and second pairs of abutment members34O1,34O2. As a consequence, the sheet material or stacked collation may be rotated or transposed to the desired angular position DP.

While a variety of sensing devices may be employed to detect the status/condition of the sheet material, e.g., a paper jam, paper location or angular orientation, another advantage of the EDP system20relates to feedback which can be obtained from the ferromagnetic elements26and the coils28a,28b. For example, should a jam occur, a sheet material collation12will retard the motion of at least one abutment member34, i.e., the “pushing” member34along the trailing edge of the collation. The opposing abutment member34, i.e., the “jogging” or “aligning” member34along the leading edge of the collation, on the other hand, may continue traveling forward, unabated. Inasmuch as each of the abutment members34is tied to a ferromagnetic element26, the motion of each (whether the ferromagnetic elements26decelerate, stop, move apart or move together), will momentarily increase resistance or, alternatively induce a current spike in the adjacent coil. This fluctuation in current can then be sensed and interpreted by the controller for determining the correct or appropriate action. For example, the controller may provide a jam indication to an operator and/or momentarily pause the EDP system20.

In another embodiment of the invention, the processor30may control the EDP system20such that relative spacing between pairs of abutment members34, i.e., the longitudinal spacing, may be varied to increase or decrease the size of a transport pocket. For example, inFIG. 7, the abutment members34may be spaced to produce a first pocket P1having a length which generally corresponds to the length dimension L1of one stacked collation12. Similarly, the abutment members34may be spaced to produce a second pocket P2, adjacent to or downstream of the first pocket P1, having a length dimension which corresponds to the length dimension L2of another stacked collation. As such, the pocket size may be varied to increase the throughput of the transport system. That is, throughput is optimized by maximizing the number of collations which may be carried on the support deck14.

In yet another embodiment of the invention, it may be desirable to shield the sheet material or mailpieces from the electromagnetic flux field produced by the EDP system20. For example, certain mailpieces may contain security devices, credit cards, debit cards etc., having magnetic strips which may be influenced by the magnetic field produced by the EDP system20. As such, it may be desirable to include a wire mesh, copper shielding, or other conductive material to diminish or eliminate the flux field surrounding the mailpiece.

In summary, the present invention provides a low-maintenance, reliable, and low-cost system for transporting sheet material. The EDP system20minimizes wear, erosion and maintenance by significantly reducing friction between moving components. Furthermore, the EDP system requires no chains, belts, or mechanical drive systems which require lubrication, periodic inspection, and maintenance repair/replacement. The transport system of the present invention is highly reliable and requires a minimal number of spare or replacement parts. Accordingly, low spare part inventories can be maintained further reducing overhead costs.

Additionally, and perhaps more importantly, the transport system of the present invention is highly flexible, enabling a variety of previously unavailable controller functions. The transport system20of the present invention facilitates the initial set-up and dimension requirements for the travel pocket. Simple control inputs can be made by the processor30to establish the initial spacing between the ferromagnetic elements26and, accordingly, the abutment members34. In contrast, the prior art transport and alignment systems typically rely upon laborious/painstaking adjustments of various components e.g., the push fingers and stop mechanisms to establish the pocket size.

The transport system provides for a variable pocket size which maximizes throughput by enabling a higher percentage of the useable transport deck. The transport system also provides for nearly infinite adjustment of the pocket size. Whereas, in the prior art, finite or incremental adjustment of the pocket size is made possible through manual adjustment, the present invention enables fine differential adjustments of the position and/or speed of the ferromagnetic elements26for virtually infinite adjustment of the abutment members34and, consequently, the pocket size. Furthermore, such adjustments can be made through software control logic rather than through changes to transmission gearing as is typically required in prior art sheet material handling/transport systems.

Furthermore, the transport system of the present invention allows for registration of sheet material, i.e., by the bi-directional oscillation of abutment members34. Inasmuch as registration can occur at the same time as the stacked collation travels along the support deck, throughput efficiency is increased. Finally, the transport system provides for alignment of sheet material/stacked collations as it travels along the support deck. The transport system avoids the requirement to off-load misaligned/poorly aligned sheet material. Once again, throughput efficiency is increased.

While the transport and alignment system has been described in the context chassis module of a mailpiece inserter system, it will be appreciated that the transport and alignment system is applicable to any sheet material handling system. Furthermore, while adjacent pairs of EDP systems and abutment flags are shown, a single EDP system and abutment device for engaging the sheet material may be employed.

It is to be understood that the present invention is not to be considered as limited to the specific embodiments described above and shown in the accompanying drawings. The illustrations merely show the best mode presently contemplated for carrying out the invention, and which is susceptible to such changes as may be obvious to one skilled in the art. The invention is intended to cover all such variations, modifications and equivalents thereof as may be deemed to be within the scope of the claims appended hereto.