Patent Publication Number: US-2017369269-A1

Title: Forming and folding sheet portions

Description:
BACKGROUND 
     The process of producing printed articles such as books or booklets from digitally printed sheets on which are imposed multiple pages of a printed article to be produced may involve folding each printed sheet, gathering together several of the folded sheets, joining the gathered sheets, for example by stitching or sewing them together, and trimming. 
     In some known processes, and depending on the number of pages imposed on each sheet, the sheets may be folded two or more times, in different directions, before they are gathered and stitched or sewn. 
    
    
     
       BRIEF DESCRIPTION 
       Some non-limiting examples of the present disclosure will be described in the following with reference to the appended drawings, in which: 
         FIG. 1  is a schematic diagram illustrating how a booklet may be produced from a printed sheet having printed thereon several pages of the booklet, according to a prior art method; 
         FIG. 2  is a schematic diagram illustrating how an example of a booklet may be produced from a printed sheet having printed thereon several pages of the booklet, according to examples disclosed herein; 
         FIGS. 3, 4, 5 and 6  are schematic diagrams of finishing devices according to examples as disclosed herein; and 
         FIG. 7  is a schematic diagram of a digital sheet printer according to implementations as disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     It is known to use finishing devices for producing books or booklets from large sheets, such as digitally printed B2-size sheets (500 mm×707 mm), A2-size sheets (420 mm×594 mm), A1-size sheets (594 mm×841 mm), or other larger or smaller sheets, each sheet having imposed and printed thereon multiple pages of the booklet to be produced. In the following reference will be made to B2-size sheets by way of non-limiting example. 
     Finishing devices may perform one or more operations such as for example folding the sheets, gathering the folded sheets, stitching or sewing the sheets to join them together, and/or trimming. 
     Depending on the number of pages that are imposed on each printed sheet, the process of producing a book or booklet may involve several folds of each printed sheet, e.g. folds in two different directions, before the sheets are gathered together in the desired number and order. For example, in a 4-up booklet imposition where eight A4 size pages are printed on each B2 size sheet, two folds perpendicular to each other have to be made to form a signature for the booklet. In another example, illustrated in  FIG. 1 , an 8-up booklet imposition where sixteen A5 size pages are printed on each B2 size sheet S, three subsequent folds F 1 , F 2  and F 3  have to be made to form the signature. 
     It is known to produce booklets from e.g. printed B2 size printed sheets by a process in which printed sheets are folded in a folding device and stacked at the output of this device, and subsequently the folded sheets are fed to another device, where they may be further folded, gathered together, stitched or sewn to form the booklets, and finally trimmed. 
     A book or booklet may be made up of several B2 or other large size sheets, each having multiple pages imposed thereon. Furthermore, digital printers may print and output the sheets already collated: for example, to produce a number of copies of a booklet each being made up of a predetermined number of B2 sheets. 
     However, known finishing devices and processes produce booklets using complete sheets, and therefore may produce booklets with a number of pages that is a multiple of the number of pages imposed on each sheet, but not with another number of pages. 
     For example, from digitally printed B2 size sheets S with 16 pages imposed thereon, as in  FIG. 1 , books or booklets having a number of pages of 16 (one B2 sheet S), 32 (two B2 sheets S), 48 (three B2 sheets S), etc. may be produced. 
     This doesn&#39;t happen in offset printing, since in this case each sheet with a different content is printed separately, and several different sheet sizes may be printed and combined in a printed article such as a booklet. However offset involves an additional operation to collate the sheets after they are printed. 
     An example of a method for producing printed articles from printed sheets as disclosed herein is illustrated in  FIG. 2 . 
     Printed sheets S on which are imposed and printed multiple pages of a printed article to be produced, for example sixteen A5 pages as shown, may be obtained, from example from a digital printer, and cut in a direction perpendicular to a sheet advance direction A to form at least two sheet portions SP. In this example four sheet portions SP 1 , SP 2 , SP 3  and SP 4  are formed. 
     As each cut sheet portion SP is output from the cutting operation, it may be folded. The fold may be made along a line in the sheet advance direction A, as in the example shown in  FIG. 2 . 
     In some implementations, all the sheet portions SP that result from cutting the sheets S are folded and gathered in a booklet. However, in some other implementations, preselected cut sheet portions of each sheet S, or of some of the sheets S, may be diverted towards a waste unit and discarded. 
     The folded sheet portions may then be gathered one over the other with their fold lines coinciding, and may be joined together, for example at the fold line. 
     In some implementations of the method, such as that illustrated by  FIG. 2 , each printed sheet is cut to form between two and four sheet portions SP, depending on the number of pages of the printed article that are imposed on each printed sheet S, wherein each cut sheet portion SP comprises on each side two pages of the printed article, one adjacent to another in the direction of the cut. Each resulting sheet portion SP is thus a “column” having two pages on each side. 
     Implementations of the method disclosed herein allow including in a booklet or other printed article a desired number of sheet portions SP (e.g. the desired number of columns of two pages), and not necessarily all the pages imposed and printed on a large sheet, e.g. B2 size sheet. 
     The rest of the columns of the large sheet may form another booklet, or be included in another booklet, and/or some of the columns may be discarded. 
     Consequently, a book or booklet may be produced with a number of pages that is not a multiple of the pages on one printed sheet, thus increasing the flexibility in the number of pages of the printed articles. Booklets or other printed articles with any number of pages that is a multiple of  4  may be produced. 
     For example, booklets having  24  pages may be produced from two B2 sheets each having 16 pages imposed thereon as in the example shown in  FIG. 2 . To this end, all the sheet portions SP 1 , SP 2 , SP 3 , SP 4  of a first printed sheet, and the first two sheet portions SP 1 , SP 2  of a second printed sheet are folded and joined together, while the last two portions SP 3  and SP 4  of the second printed sheet are discarded. 
     In one example, instead of being discarded, sheet portions SP 3  and SP 4  of the second printed sheet may also form another booklet having 8 pages, or sheet portion SP 3  may form another booklet having 4 pages, and sheet portion SP 4  may be discarded. 
     In other examples, sheet portions SP 3  and SP 4  of the second printed sheet may be included in a subsequent booklet, by suitably imposing the content of the booklets in the digital printer. 
     Implementations of the method disclosed herein may also avoid performing several folds on each printed sheet having multiple pages, by severing the printed sheet into sheet portions SP having a smaller number of pages, which with one fold may form the printed article to be produced. 
     Implementations of a device, such as a finishing device, as disclosed herein, are illustrated by the schematic diagram of  FIG. 3 . A device as disclosed herein may be employed for example to produce printed articles from sheets, for example printed sheets on which are imposed and printed multiple pages of a printed article to be produced, such as for example a book or booklet. The printed sheets from which the printed article is produced may be printed in a digital sheet printer, already collated in the suitable arrangement to form the desired printed article in a finishing device. They may be large format sheets, such as B2 size sheets. 
     As shown in  FIG. 3 , in some examples the finishing device comprises a sheet feeder  10 , to feed sheets from a stack of printed sheets S, a sheet path P for the advance of a plurality of printed sheets S fed by the sheet feeder  10 , a cutter  11  on the sheet path P to cut the printed sheets S in a direction perpendicular to the sheet advance direction, to form at least two sheet portions SP, such as the sheet portions SP 1 , SP 2 , etc. of  FIG. 2 , and a folder  12  on the sheet path P downstream of the cutter  11 , to fold the sheet portions SP. 
     In some implementations, such as shown in  FIG. 4 , a finishing device as disclosed herein comprises a sheet feeder  20 , a cutter  21 , a folder  22 , and a joining unit  23  that comprises a saddle folder  22 . A number sheet portions may be folded, gathered and stitched together, or sewn together, in this unit  23 . 
     As shown in  FIG. 5 , in some implementations the finishing device disclosed herein comprises a sheet feeder  30 , a cutter  31 , a diverter  34  downstream of the cutter  31 , and a joining unit  33  with a folder  32 . 
     The diverter  34  may be operated to divert preselected cut sheet portions away from the sheet path P, for example if the booklets being produced have a number of pages that is not a multiple of the pages imposed on one printed sheet S. 
     The sheet portions that are diverted away from the sheet advance path P in the diverter  34  may for example be discarded in a waste bin  35 . 
     Some implementations of a finishing device as disclosed herein, such as shown in  FIG. 6 , comprise a sheet feeder  40 , a cutter  41  to cut printed sheets in a direction perpendicular to a sheet advance direction A and form at least two sheet portions, a joining unit  43 , such as for example a stitching or sewing unit, comprising a saddle folder  42 , downstream of the cutter, to fold and join together the sheet portions, and a handling system  46  to transport the printed sheets S, or the cut portions thereof, in the sheet advance direction. 
     The sheet feeders  10 ,  20 ,  30 ,  40  of implementations of the device as disclosed herein may be for example pile feeders. 
     In some implementations of the device, the cutter  11 ,  21 ,  31 ,  41  may be a rotary cutter or a guillotine cutter. The operation of such a cutter may be programmed to perform one or more cuts on each printed sheet, so as to form the right number of sheet portions depending on the printed sheet layout and the printed article to be produced. 
     The folders  12 ,  22 ,  32 ,  42  of implementations of the device may be plow folders or saddle folders. Cut sheet portions SP may be folded and gathered in the plow or saddle folder, with the fold line in the sheet advance direction. 
     Some examples of a finishing device FD as disclosed in the present specification may have a controller, respectively indicated with reference numerals 17, 27, 37 and 47 in  FIGS. 3, 4, 5 and 6 , to perform a method as disclosed above for producing printed articles from printed sheets S. 
     As shown in  FIG. 7 , also disclosed herein is a large-format digital sheet printer DSP comprising a finishing device FD according to implementations described above, in-line with the printer DSP, such that large format sheets digitally printer output by the printer DSP are fed in-line to the finishing device FD. Large format sheets may be for example B2 size sheets. 
     In implementations of a large-format digital sheet printer DSP as disclosed herein a sheet feeder  50  operates to take each printed sheet output from a digital printing unit  60  and feed it to a cutter  51  as disclosed in examples above. Cut sheet portions are then folded in a folder  52  as disclosed in examples above. 
     Although a number of particular implementations and examples have been disclosed herein, further variants and modifications of the disclosed devices and methods are possible. For example, not all the features disclosed herein are included in all the implementations, and implementations comprising other combinations of the features described are also possible.