Abstract:
A folding apparatus includes a feed unit for supplying a medium to be folded, a folding substrate forming a convexly curved support surface for the medium and adapted to be driven back and forth in a circumferential direction of the curved support surface, and a pinch and guide structure for folding and guiding the medium on the support surface. The pinch and guide structure includes at least one endless belt that is arranged to have a belt portion held in mating engagement with a portion of the curved support surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(a) to Application No. 07110399.89, filed in Europe on Jun. 15, 200, the entirety of which is expressly incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a folding apparatus that includes a feed unit for supplying a medium to be folded, a folding substrate forming a convexly curved support surface for the medium and adapted to be driven back and forth in a circumferential direction of the support surface, and a pinch and guide structure for folding and guiding the medium on the support surface, wherein the pinch and guide structure includes two endless belts each of which is arranged to have a belt portion held in mating engagement with a portion of the curved support surface, so that the two endless belts define two separate paths for the medium. 
         [0004]    2. Description of Background Art 
         [0005]    A folding apparatus of this type has been disclosed in EP 0 717 486 A1. A similar apparatus is described in EP 05 90 359 A1. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide a folding apparatus of the type indicated above which has a simple construction and an improved operational flexibility. 
         [0007]    In order to achieve this object, according to the present invention, the folding substrate and the pinch and guide structure define a closed circulation path, in which the two separate paths are joined at a point remote from the feed unit. 
         [0008]    The portion of the belt held in mating engagement with the support surface will smoothly and reliably guide the medium along the support surface. Since the belt portion may easily be deflected in the direction away from the support surface, the pinch and guide structure may easily adapt to media with varying thicknesses and configurations. Thus, the folding apparatus according to the present invention is particularly useful for forming crossfolds in media that have been fan-folded into a multi-layer structure in a preceding folding station. 
         [0009]    Moreover, the endless belt may be driven so as to move with a speed that is essentially identical with the speed of the surface of the folding substrate, so that the sheet may be conveyed without any substantial friction and, consequently, reduced risk of shear strain and damage. 
         [0010]    Since the two separate paths are joined at a point remote from the feed unit, it is possible to accommodate larger media. 
         [0011]    The folding substrate may be a drum or an endless belt, so that the medium that is being processed may be caused to revolve in the apparatus. In this way, by suitably controlling a discharge gate that is disposed at the periphery of the endless folding substrate, it is possible to discharge a folded sheet in either of two orientations, so that, if the medium to be folded is a design drawing, for example, the legend of the drawing may always be placed in the right position. 
         [0012]    A pinch roller may be provided for pressing the belt against the support surface of the substrate at the position where the fold is to be formed. This pinch roller may at the same time serve as a deflection roller for deflecting the endless belt or may be provided in addition to a set of deflection rollers and arranged at an intermediate portion of the belt that is in mating engagement with the support surface. 
         [0013]    Preferably, the pinch and guide structure comprises a pair of endless belts and associated deflection rollers and/or pinch rollers arranged symmetrically with respect to the feed unit. This provides a high flexibility in forming different folding patterns, including zig-zag folds and C-folds. 
         [0014]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0016]      FIG. 1  is a schematic overall view of a folding apparatus according to one embodiment of the present invention; 
           [0017]      FIG. 2  is a schematic cross-sectional view taken along the line II-II in  FIG. 1 ; 
           [0018]      FIG. 3  is a schematic perspective view illustrating the function principle of the folding apparatus; 
           [0019]      FIGS. 4-7  are simplified schematic views similar to  FIG. 1 , illustrating different stages in a first mode of operation of the apparatus; 
           [0020]      FIGS. 8 and 9  are views illustrating a second mode of operation; 
           [0021]      FIGS. 10-16  are views illustrating a third mode of operation; 
           [0022]      FIG. 17  is a schematic overall view of a folding apparatus according to another embodiment of the present invention; and 
           [0023]      FIG. 18  is a schematic overall view of a folding apparatus according to yet another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views. 
         [0025]    As is shown in  FIG. 1 , a folding apparatus comprises a feed unit  10 , a folding substrate which, in this embodiment, is configured as a cylindrical drum  12 , and a pair of pinch and guide structures  14  that are arranged symmetrically with respect to the feed unit  10  at the peripheral surface of the drum  12 . A discharge unit  16  is arranged in a position diametrically opposite to the feed unit  10 . 
         [0026]    The feed unit  10  comprises a guide channel  18  arranged for guiding sheet-like media (not shown in  FIG. 1 ), e.g. print media such as paper or the like, vertically downward onto the peripheral surface of the drum  12 . A pair of feed rollers  20  form a nip in the supply channel  18 . At least one of the feed rollers  20  is driven, so as to control the supply of the sheets to the drum  12 . 
         [0027]    Two deflection fingers  22  and  24  are arranged at the downstream end of the feed unit  12  for deflecting the sheets at the transit point between the feed unit  10  and the surface of the drum  12 . The deflection fingers  22 ,  24  are adjustable by means of a set mechanism that has not been shown, so that they may optionally be brought into an operative position. In the example shown in  FIG. 1 , the deflection finger  24  is in the operative position. 
         [0028]    Each pinch and guide structure  14  comprises a pinch roller  26  and an endless belt  28  or rather an array of several parallel belts that are trained around the pinch roller  26  and two deflection rollers  30  and  32 . The pinch roller  26  and the deflection rollers  30 ,  32  are arranged such that a portion  28   a  of the belt  28  is held in mating engagement with the peripheral surface of the drum  12 . In the example shown, the portion  28   a  extends over an angle of almost 180° from the feed unit  10  to the discharge unit  16 . The belt  28  may be elastic, or one of the deflection rollers, e.g., the roller  30 , may be supported elastically so as to hold the belt  28  under appropriate tension, so that the portion  28   a  will suitably be pressed against the surface of the drum  12 . 
         [0029]    The drum  12  is connected to a drive mechanism (not shown) so as to be rotatable in either direction about its central axis. The belts  28  and the pinch rollers and deflection rollers may be driven through frictional contact with the peripheral surface of the drum  12 . Preferably, however, one of the pinch rollers  26  and deflection rollers  30 ,  32  of each pinch and guide structure  14  is driven actively by means of a drive mechanism (not shown). 
         [0030]    The discharge unit  16  comprises a discharge gate  34  that is disposed between the two deflection rollers  32  and is pivotable about an axis  36 . Further, a pair of discharge rollers  38  form a transport nip below the deflection rollers  32 . 
         [0031]      FIG. 2  shows a cross section of a portion of the peripheral wall of the drum  12  as well as cross sections of the plurality of belts  28  that are trained around the deflection roller  32 . The discharge gate  34  has a comb-structure with a plurality of fingers  40  arranged in the intervals between the individual belts  28 . In the condition that has been shown in solid lines in  FIGS. 1 and 2 , the fingers  20  project into the gaps between the belts  28 , whereas, when the gate is pivoted about the axis  36  into the position that has been shown in phantom lines in  FIGS. 1 and 2 , the fingers  40  project into grooves  42  that are formed in the peripheral surface of the drum  12 . 
         [0032]    Thus, when the gate  34  is in the position shown in phantom lines, a sheet that is conveyed downwardly between the surface of the drum  12  and the belts  28  on the left side of the drum will be separated from the drum surface by the fingers  40  and guided into the nip of the discharge rollers  38  so as to be discharged from the apparatus. On the other hand, when the gate  34  is in the position shown in solid lines, the leading edge of a sheet that is paid out between the belts  28  and the drum surface will be deflected into the narrowing gap between the drum surface and the belts  28  of the other pinch and guide structure  14  (on the right side in  FIG. 1 ), so that the sheet will be caught again between the drum and the belts  28  and continue to revolve about the axis of the drum  12 . 
         [0033]    It will be clear that the gate  34  may also be pivoted into a position mirror-symmetrical to the one shown in phantom lines in  FIG. 1 , so as to discharge sheets when the drum  12  rotates in an opposite direction. 
         [0034]    The function principle of the folding apparatus will now be explained in conjunction with  FIG. 3 . A sheet  44 , e.g. of a recording medium exiting from a printer, is supplied by means of the feed rollers  20  towards the drum  12 . When the leading edge  46  of the sheet  44  reaches the surface of the drum  12  and the drum is driven in the direction indicated by an arrow A, the sheet is deflected into the nip between the drum  12  and the front pinch roller  26  in  FIG. 3 . The deflection finger  24  ( FIG. 1 ) may be brought into its operating position in order to assist in this deflection. Then, when a certain length of the sheet  44  has been fed through the nip, as shown in  FIG. 3 , the direction of rotation of the drum  12  is reversed (direction B), while the feed rollers  20  continue to feed the trailing part of the sheet  44  downwardly or at least are held stationary so as to prevent the sheet  44  from being pushed upward again. As a consequence, the sheet  44  forms a blouse  48  that bulges towards the rear pinch roller  26  in  FIG. 3 . When this blouse is caught between the pinch roller and the surface of the drum  12 , it is drawn into the nip between these two members, so that a fold is formed in the sheet. 
         [0035]    This process is illustrated further in  FIGS. 4 to 7  which show a mode of operation in which a single fold is formed in the sheet and the sheet is then discharged with the fold ahead. 
         [0036]    In  FIG. 4 , the drum  12  is rotated clock-wise, and the sheet  44  is fed downwardly and deflected into the gap formed between the surface of the drum  12  and the belt  28 . When a certain length of the sheet  44  has been drawn in, the direction of rotation of the drum  12  is reversed, as shown in  FIG. 5 , so as to form the blouse  48 . 
         [0037]    When the drum  12  is rotated further in counter clock-wise direction, as in  FIG. 6 , the blouse is pinched between the drum  12  and the pinch roller and the belt  28 , respectively, and a fold  50  is formed. Then, as shown in  FIG. 7 , the fold  50  reaches the gate  34  and is deflected from the surface of the drum  12  and discharged. 
         [0038]    If the sheet is to be discharged in reverse orientation, with the fold  50  at the trailing end, the step that has been illustrated in  FIG. 7  is replaced by the steps shown in  FIGS. 8 and 9 . In  FIG. 8 , the gate  34  has been opened so as to deflect the sheet into the path on the right side of the drum  12 . Then, when the trailing end of the sheet has passed the gate  34 , the direction of rotation of the drum  12  is reversed again and the gate  34  is closed, so that the sheet is discharged with the “open” end  54  ahead. 
         [0039]    Another mode of operation, for forming a C-fold in a sheet, will now be explained in conjunction with  FIGS. 10 through 16 . In  FIG. 10 , the drum  12  is driven clock-wise, and the sheet  44  is supplied until the leading end has passed beyond the gate  34 . Then, as shown in  FIG. 11 , the drum is reversed to form the blouse  48 . Continued anti-clockwise rotation of the drum  12  produces a first fold  50 , as shown in  FIG. 12 . The drum  12  is rotated further, so that the fold  50  passes the gate  34  and approaches again the pinch rollers  26  on the top of the drum  12 , as shown in  FIG. 13 . Meanwhile, the deflection finger  22  has been brought into the operative position. 
         [0040]    Then, as shown in  FIG. 14 , the fold  50  reaches the deflection finger  22  and is deflected upwardly so as to exit between the pinch rollers  26 . In the situation shown in  FIG. 15 , the double-layered part of the sheet  44  has left the surface of the drum  12  and has passed through the gap between the pinch rollers  26 . Then, the deflection finger  22  is withdrawn and the deflection finger  24  is brought into position, instead. The drum  12  continues to rotate counter clock-wise. As a result, another blouse  56  is formed in the single-layered part of the sheet. 
         [0041]    The blouse  56  is then pinched between the pinch roller  26  and the belt  28  on the one hand and the surface of the drum  12  on the other hand, so that a second fold  58  is formed, as has been illustrated in  FIG. 16 . Thus, the sheet  44  now has a C-folded configuration. 
         [0042]    In the example shown in  FIG. 16 , the gate  34  has been closed so as to discharge the sheet  44  with the fold  58  ahead. Of course, it would also have been possible to open the gate  34  and reverse the direction of rotation of the drum  12  once again so as to discharge the sheet with the fold  50  ahead, as previously explained in conjunction with  FIGS. 8 and 9 . 
         [0043]    When handling multi-layer sheets such as the sheet  44  in  FIG. 16 , it is a particular advantage of the present invention that the belts  28  can be driven to move with the same speed as the surface of the drum  12 , so that the folded package of the sheet  44  is not subject to any shear stresses. 
         [0044]    It will be understood that a plurality of different folding patterns can be formed simply by suitably controlling the timings at which the rotation of the drum  12  is reversed and at which the deflection fingers  22 ,  24  and the gate  34  are operated. 
         [0045]    In the apparatus that has been described above, the belts  28  are deflected at their top ends by the pinch rollers  26  which may be supported in such a manner that they are elastically biased against the surface of the drum  12  so as to exert a suitable pinching pressure onto the sheet so as to form the folds therein. In a modified embodiment, however, the positions of the pinch rollers  26  in  FIG. 1  may be occupied by deflection rollers that are separated from the surface of the drum similarly as the deflection rollers  32  in  FIG. 1 . Then, the belts  28  would tangentially approach the surface of the drum  12 , so that the leading edge of a sheet can smoothly be guided into the gap between the belt and the drum surface. Pinch rollers may then be provided offset from the top deflection rollers at the portion  28   a  of the belt. 
         [0046]      FIG. 17  illustrates another embodiment of the present invention, wherein the folding substrate is formed by two separate smaller drums  12 ′ that are arranged in parallel and are connected by stationary guides  60  which, together with the belts  28 , define a closed circulation path for the sheets. Here, the belts  28  have straight portions running along the guides  60  without pressing against these guides or pressing only moderately there against, so that the sheets or sheet portions, when passing along the guide  60 , will not experience any substantial friction or shearing strains. 
         [0047]    In a modified embodiment (not shown), however, friction may be reduced further by training an endless belt around the two drums  12 ′, so that this belt will then form the folding substrate. Optionally, this belt may be backed by stationary guides comparable to the guides  60  in  FIG. 17 . 
         [0048]      FIG. 18  shows another embodiment wherein the folding substrate is formed by a relatively small drum  12  and a larger endless belt  62  that is supported by the drum  12  and by a number of pairs of support rollers  64 . The belt  62  may be made of a semi-rigid material so that it can be held in a defined, e.g. circular shape with only a few support rollers  64 . The pinch rollers  26  engage the belt  62  at positions where this belt is directly supported by the drum  12 , so that a sufficient pinching pressure can be exerted. 
         [0049]    The embodiments discussed in conjunction with  FIGS. 17 and 18  are particularly useful for handling large-format sheets, because they provide a comparatively long circulation path for the sheets while, on the other hand, the mass of inertia or moment of inertia of the members that have to be moved alternatingly in opposite directions can be kept relatively small. 
         [0050]    All embodiments have the advantage that the belts  28  keep the sheets or the folded packets close to the surface of the folding substrate and smoothly guide the same, especially when they are moved synchronously with the folding substrate. Since the sheet or packet is suitably pressed against the surface of the folding substrate on almost the entire length of its path, it is successfully prevented from sliding sideways in the apparatus. 
         [0051]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.