Abstract:
A post-processing mechanism for a printer or the like includes a curved paper path. Post-processing operations such as stapling or other binding are performed either within the curved paper path or during the withdrawal of a document from the curved paper path. The curved paper path permits such post-processing operations to be performed within a limited space, while reducing the complexity of the post-processing mechanism and reducing the complexity of operations performed by the post-processing mechanism.

Description:
FIELD OF THE INVENTION 
     The present invention relates to paper handling. More specifically, the invention relates to folding and manipulation of documents for folding. 
     BACKGROUND OF THE INVENTION 
     Printing of documents is often followed by post-processing paper handling. In a simple form, this includes collating or stapling. Often the document is such that post-processing includes stapling and folding, with registration and paper trimming requirements. Such post-processing requires additional equipment and increases the “footprint” or floor space required for such a machine. 
     Post-processing usually follows the printing process in which printing material is applied to paper or other sheet media. By “printing material” it is intended to describe laser toner, printing ink, or any other type of toner or material which is used for providing an image which is produced on the document. These are various types of imaging materials. It is, of course, possible that a variation in the material be established in suitable circumstances so that the pigmentation of the printing material is less noticeable. Such printing material is deposited upon “sheet media” which may include paper or other materials which are used for receiving a printed image. Typically, printed documents include at least sheet media and printing material. 
     “Document” is intended to describe one or more sheets which may be in the form of a booklet. A “print job” may include multiple copies of a document. A document can take a number of forms, but is often an assembly of sheets of paper or other sheet media. In this invention, the documents are generally bound by a row of staples. Typically, this is a “booklet,” sometimes called “saddle stitch and fold.” A booklet has more than one page, usually two to five or more pages. It has one or more staples that hold the pages together. The staples are located along a line, approximately at the middle of the page. Unless portions of the booklet are intentionally offset, and after the pages are stapled, the pages are folded along a staple line, meaning a line defined by the staples. 
     The term “MOPy” stands for multiple original prints. A “MOPy” is a reproduction of an original that is bounded within a single job that a user sends to print. The original can be in either physical or electronic form, and the print job can be composed of “n” MOPies. Each MOPy may have “x” number of sheets. Both n and x may be one or more MOPies and sheets, respectively. By way of example, a particular print job may include 5 MOPies “n” MOPies). Each MOPy may be comprised of 28 sheets “x” sheets). The print job would therefore comprise 140 sheets. By printing multiple MOPies, documents can be created, controlled, managed and finished from the user&#39;s desktop, eliminating the extra step of going to a photocopier. 
     The attachment of multiple larger sheets to form booklets is well-known, and the bookbinding art even has conventional number of pages in which smaller sections, called “signatures” or “units,” containing 16, 32, or 64 pages, are assembled for purposes of printing and bookbinding. The present invention relates to a technique useful for creating signatures as well as for smaller signatures, pamphlets, as well as other folded or bound documents. 
     One commonly used method of permanently fixing multiple pages is stapling of the pages. When print jobs are produced by laser printing, photocopying and other short-run processes, it may be desired to fold or otherwise manipulate assembled documents. In the prior art, this was either done by hand, or by the use of paper handling equipment, such as sheet folders. 
     One of the aspects of sheet folders is that it was necessary to separately align, staple and then fold individual documents. This increased the expense of paper folding equipment. Additionally, the complexity of the equipment decreased reliability and increased the space required for a printer. 
     In the case of documents which are produced by the use of laser printers or photocopiers, any additional procedures involved in producing a final product, such as folding equipment,require the use of additional equipment. This additional equipment would be either within the printer or external to the printer, but in either case requiring additional expense and bulk. That means that the ability of providing office printers which are capable of providing assembled booklets or ether multi-page brochures is limited. It would be desired to provide a printer arrangement which allows assembly of multiple sheets of paper or other sheet media, but does not require a substantial investment in additional equipment for folding and other paper handling purposes. It is desired that the additional features be provided without making the printer or copier substantially more complicated or less economical to operate. It is therefore desired to provide a simplified automatic paper folder for such equipment. 
     In addition, the paper folding mechanism must, prior to folding the documents, transport the documents to an appropriate location for folding. This means that, often after the documents are assembled or otherwise sorted at a discharge end of a printer, these documents must again be handled. This can result in mishandling of the documents and of course results in increased complexity of the equipment. 
     Providing the ability to perform multiple post-processing operations generally increases the space or “footprint” occupied by a printer. This means that features which may otherwise be cost-effective may be undesirable because there is a space limitation. For example, if the post-processing operations include collation, alignment, center stapling, and folding, it is often necessary to provide a first space at which a stack of sheets can be accumulated, placed in registration and stapled. Additional space is needed for subsequent operations such as folding of the stapled document. In the case of booklets, often the booklet is formed from ledger sized paper (432×280 mm) or A3 paper, with the printer generally discharging the paper length wise. That means that the first receiver tray would be extending over 430 mm beyond the footprint of the printer. In addition, if, subsequent to the stapling, the document must be transferred to a folding mechanism, additional space may be required. 
     Often such printers are used for multiple purposes. Therefore, even though the printer with the stapling capability may be purchased with that capability in mind, it is often the case that the printer must perform tasks which do not require the extra equipment. In such a case, the printer may prove to be excessively large and inconvenient for everyday use. 
     It would therefore be desired to provide a printer in which such divers functions can be performed, but with less complexity of the equipment. It is further desired that post-processing operations be performed within a footprint which may be required for one post-processing process. It is further desired that the space required for any of the post-processing steps be small, particularly on equipment designed to handle larger sheets such as ledger, A 3  or B 3  paper. 
     Typically, the process to make a booklet is to add a set of staples, usually in the middle of the sheet. Once the document is stapled, it is folded at the center line so that it has a book appearance. The fold is accomplished with the aid of nip rollers in combination either with a feeding blade or with a pusher bar which buckles the document. 
     After such a booklet is folded, the cover page ends up being shorter than the center fold page if all of the sheets are printed on the same sized paper. In some cases, this is tolerated and the free edges of the pages form a tapering profile. In other cases, the tapered edge is cut so as to form a uniform profile. If a booklet is formed from multiple identical sheets folded at the center, this uniform profile can be accomplished by two techniques: 
     1. the booklet can be formed with the tapering profile and the free ends cut back. 
     2. the document can be folded so that one side of each of the sheet falls into registration, thereby doubling the misregistration of the other side. The other side may either be cut back or allowed to retain its taper. 
     In any case, the degree of taper is dependant upon the nature and thickness of the sheets as well as the open length of the sheets. It can be seen that equipment used to form such booklets must have some way of accommodating such taper. Furthermore, if booklets or signatures are to be trimmed, it is often necessary to provide the paper handling equipment with an ability to adjust for desired taper characteristics. 
     During the booklet making process, we are primarily interested in the centerline of the document, where we have to locate the staples and fold the document. The remainder of the booklet merely occupies space. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, post-processing equipment for a printer or other paper handling device is configured so as to contain the paper or other sheet media within a curved catchment. The curved catchment includes a radial finger which provides an end stop for the sheet media. The radial finger maintains the sheet media in registration and is adjusted so as to position the sheet media with paper handling mechanisms positioned along the curved catchment. The curved catchment exhibits a reduced profile “footprint” and further permits movement of the sheet media within that reduced footprint to different paper handling mechanisms. This provides the advantage of using common equipment for alignment purposes while performing multiple functions. This also provides the advantage of reducing the overall footprint of the paper handling equipment. 
     In accordance with one aspect of the invention, a curved catchment is provided at a discharge end of a printer or other sheet media handling apparatus. The curved catchment has positioned a radial finger which extends from a center axis of the catchment. The radial finger forms an end stop for the sheet media discharged into the catchment and adjusts a position at which the sheet media falls into registration. In order to accomplish multiple operations such as stapling and folding, the radial finger first stops at a position aligned with a first mechanism, such as a stapler. After stapling is performed, the radial finger moves so as to position the sheet media into alignment with a second mechanism. Therefore, if the second mechanism is a folding device, the folding device can be caused to fold the document along a staple line. 
     The curve effects a partial displacement of the sheet media to form tapered ends. Therefore, some degree of automatic adjustment is accomplished by which the sheet media forms an even taper despite variations in the nature of the paper. This means that a requisite adjustment for achieving a desired taper is less than would be required for achieving such a taper property if alignment of the sheets were accomplished on a flat surface. 
     In one embodiment, a stapler mechanism is positioned along the curved catchment so that the sheet media may be stapled at a desired location such as along a center fold line. A folding mechanism is also located along the curved catchment. The radial finger can first be positioned so as to align a document with a stapling mechanism, and then repositioned so as align the document with a paper folding apparatus, even though the paper folding apparatus is offset with respect to the stapler. 
     In accordance with a further aspect of the invention, a paper handling device uses a novel curved paper path. The paper path reduces significantly the overall size of a booklet maker device and simplifies the positioning mechanisms used in current booklet makers instead of the traditional flat paper path used in all current devices. 
     Benefits of this circular approach are that the user will have a significantly more compact booklet making device which is more economical and less complex. For the designer, most of the mechanisms are highly simplified by using rotational mechanisms: there is no need to transform rotational motion from any motor into linear motion. 
     A radial finger is used as the mechanical stop that is needed to register the pages longitudinally and it may be easily adjusted to the desired paper length using a stepper motor. There is no need of any mechanism to transform rotational into linear motion to make this paper size adjustment. Pages are fed one by one and registered against the radial finger using two or three sets of flexible fingers. This will align every page and will force them to follow the surface of an outer cylinder forming the outside of the paper path. 
     Transverse registration is needed and this could be done using the same flexible fingers, at a certain angle to register the pages against a “fixed” wall. This transverse registration could also be made using a set of joggers. 
     When the document is complete and perfectly registered, the stapling process takes place, using two fixed electrical staplers. 
     Once the job is stapled, the document transported from the stapling to the folding position. It is used the same radial finger that pushes the stapled document from the stapling position to the folding position beneath the nip of the folding rollers. In the typical case, the radial finger pushes the stapled document from the stapling position at the centerline of the document beneath the stapler heads to the folding position also at the centerline of the document. Finally, a feeding blade could eject the document through a slot directly into the folding rollers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a side view across the paper path of a printer which discharges its sheets along a circular paper path; 
     FIG. 2 shows a sample of a stapled, folded document; and 
     FIG. 3 shows details of a folding station of FIGS.  1  and  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a printer  11 , such as a laser printer, discharges sheets of paper  13 - 16  one at a time. The discharged sheets  13 - 16  first pass through a discharge mechanism, represented by exit rollers  20 . After passing the exit rollers  20 , the sheets  1   3 - 16  enter a discharge path  23  which includes a catchment  27 .  25  The catchment  27  includes outer and inner walls  31 ,  32  positioned so that the sequential sheets  13 - 16 , when discharged from the printer  11  are slotted between the walls  31 ,  32 . The catchment  27  is also positioned so that, after the sheets are discharged from the printer  11 , the sheets  13 - 16  fall into catchment  27  to an end stop, established by a radial finger  35 . In the example shown, sheets  13  and  14  have already fallen to engage a surface  37  forming an end plate of the radial finger  35 . In this example sheets  15  and  16  have not reached that point. Sheet  15  is dropping toward the radial finger  35 . Sheet  16  is being moved by the exit rollers  20 . When that sheet  16  will have passed the exit rollers  20 , that sheet will be positioned along the catchment  27  so that the sheet  16  will fall into the catchment  27  and follow sheet  15  to the radial finger  35 . Thus, each of the sheets  13 - 16  will eventually come to rest against the radial finger  35 , thereby falling into registration. Since the sheets  13 - 16  rest along a curved path formed by the walls  31 ,  32  there is a difference in the circumferential distance across which each individual sheet  13 - 16  extends. The innermost sheet  16  (not yet fallen into the catchment) will therefore extend along a greater number of degrees circumferentially around the catchment  27 . Then the first sheet  13 , which has a greater average radial distance from the center of the catchment  27 . Thus, there will be a taper in the registration profile of the sheets  13 - 16 . This taper is anticipated to correspond to a taper which will occur after the sheets  13 - 16  are folded. 
     In order to accomplish a stapling operation, a stapler  51  is provided. The stapler  51  includes an anvil  53  and a hammer  55 . In this case the anvil  53  is on the inside of the catchment  27 , so that the staples are discharged from the hammer  55  to the anvil  53  in a direction from the outside to the inside of the catchment  27 . In order to properly position the staples at a desired location, the radial finger  35  is positioned so that the sheets  13 - 16  line up with the stapler  51 . This can be accomplished by either positioning the radial finger  35  at a desired distance from the stapler  51 , or by pivoting the radial finger  35  toward the stapler  51  until the sheets  13 - 16  are at a desired position. In the preferred embodiment, the radial finger  35  pivots. This allows the stapler  51  and other devices to be at a fixed position along the circumference. 
     Referring to FIG. 2, the sheets  13 - 16  are to be stapled and folded along a centerline  59  so that the radial finger  35  (FIG. 1) will position the sheets  13 - 16  so that the stapler  51  aligns with a staple line (centerline  59 ) half way along the length of the sheets  13 - 16 . The stapler  51  achieves its stapling operation while the sheets  13 - 16  are within the catchment  27 . 
     Referring to FIG. 3, subsequent to stapling, the radial finger  35  moves the sheets  13 - 16  back toward a nip roller station  61 . At the nip roller station  61 , a pair of nip rollers  63 ,  64  are used to fold the stapled sheets  13 - 16 . One of the nip rollers  63  includes magnets (not shown), so that when that nip roller  63  is positioned adjacent the centerline  59 , the nip roller  63  attracts the document by attracting the staple. This magnetic attraction did not occur during the discharge cycle previously mentioned because, prior to the stapling operation, there was no staple in the sheets  13 - 16  to become attracted by the nip roller  63 . It is also possible to avoid inadvertent magnetic attraction by rotating the nip rollers  63 - 64  so that the magnet is located a substantial distance away from the outer wall  31 . It is also possible to provide some assistance to approach the stapled sheets  13 - 16  toward the nip rollers  63 - 64 . This can be accomplished by use of a blade  71  or a second radial finger  73 , or both. The blade  71  bends the sheets  13 - 16  up toward the nip rollers  63 - 64 . The second radial finger  73  cooperates with radial finger  35  to buckle the pages by limiting the circumferential length between the radial fingers  35 ,  73 . This buckling forces the pages to engage the nip rollers  63 - 64 . When the pages  13 - 16  engage the nip rollers  63 - 64 , the nip rollers  63 - 64  draw the pages up through the nip roller  63 - 64 , thereby folding the stapled document. 
     As can be seen, it is possible to accomplish a number of different operations within the confines of a small space. It is also possible to vary the physical locations of the components such as the stapler  51  and the nip station  61 . It is possible to shift the stapler  51  and nip station  61  so that a common, circumferential location is used to perform both the stapling and folding operations. It is also possible to achieve adjustments in the position of the staples along the length of the sheets  13 - 16 . An example, if the radial finger  35  were moved close to the stapler  51 , the sheets  13 - 16  would be stapled close to an edge of the sheets  13 - 16 . While this is not normally the configuration for a folded document, this does permit the same mechanism to produce a stapled document of a different type. 
     The radial finger  35  can also be provided with a preferred profile. This is shown by end plate surface  37 . The end plate surface is canted with respect to the radial direction of the finger  35 , thus resulting in a predetermined taper for the sheets  13 - 16  after having been folded. This taper can be positive or negative within the catchment  27 , depending upon whether it is desired to provide an even taper on the left and right sides of the finished booklet or it is desired to limit the requirement for cutting of the tapered ends of the stapled document after assembly. 
     Various modifications can be made by those of ordinary skill in the art with the benefit of this disclosure without departing from the spirit and scope of the invention. For example, it is possible to achieve adjustments in the positions of the stapling along the sheets  13 - 16  by moving the stapler  51 . It is also possible to include a cutter or other post-processing device which is aligned by the catchment  27  and radial finger  35 . Thus, the invention should not be limited by the specific embodiments used to illustrate it but only by the scope of the appended claims.