BACKGROUND OF THE INVENTION [0002] Various machines exist for processing sheets, i. e. , typically paper, or stacks of sheets. Such machines may include, for example, punches, holders, trimmers, and <BR> <BR> binders. In processing either individual sheets or lifts, i. e. , a small stack of sheets from a larger stack, it is frequently desirable to maintain the sheets in a given order and orientation. This is particularly true in stacks of printed sheets, for example, when the order can be critical. To this end, inverters are commonly used in the industry to invert the individual sheet or stack of sheets during processing. Such inverters may be included as part of a processing machine or as a separate process in and of itself. In operation, an individual sheet or a lift is removed from the top of the stack, a process is then performed on the sheet or lift, and the sheet or lift is then moved to a facedown position by an inverter. The next sheet or lift removed from the input stack is then subsequently inverted and placed facedown on the previous sheet or lift. In this way, the input stack is essentially flipped to a facedown position by movement of either the individual sheets or lifts.

[0003] In an automatic paper punch, for example, a stack of printed sheets will be loaded, faceup on a feeder. A mechanism grasps or picks a lift of sheets from the top of the stack. The lift size is dependent upon the capabilities and settings of the machine, but lifts of 10 to 12 sheets are common for such devices. The lift is moved as a single unit, still faceup, into a punching mechanism that perforates all the sheets simultaneously in a predetermined pattern. The punched lift is then moved to a stacking device that will place successive punched lifts into a stack, with each lift being placed on the top of the preceding lift. If the first lift is placed faceup, however, and the succeeding lift is placed on the top of the first lift, again, faceup, the page order of the document will be incorrect.

[0004] To alleviate this problem, a turnover device, or inverter, may be provided between the punching mechanism and the stacking device. The turnover device receives a lift faceup at its input area and delivers the lift facedown at its output area. In this way, the turnover device builds the stack facedown, in the correct order and orientation.

Thus, the use of a turnover device allows automatic paper processing machines to pick lifts from the top of an input stack and place them, facedown, on the top of an output stack, preserving document page order and orientation and simplifying the feeding and stacking processes.

[0005] Such inverters typically include a rotating barrel or a stationary polished barrel, the individual sheets or lifts typically moving on the order of 180° about the periphery of the barrel to reposition the sheet or lift in a facedown configuration.

Additional components may be provided to assist in the movement of the sheets or lifts about the barrel, such as belts or rollers.

[0006] A common type of turnover device utilizes two belts passed around a drum.

The lift is trapped between the two belts. In this way, if the input orientation of the lift is faceup, after going over the drum the output orientation will be facedown. One example of such a prior art device is shown in the schematic drawings of FIGURES 1 and 2.

[0007] In most such devices, the turnover drum 120 is driven by a power source, and the inside belt 122 is driven by the drum 120. That is, the friction between the surface of the turnover drum 120 and the inside belt 122 imparts a velocity to the belt 122 causing the belt 122 to rotate with the drum 120. The velocity of the inside belt 122 is thus determined by the angular velocity and radius of the turnover drum 120. The outside belt 124 is driven by the frictional contact between it and the inside belt 122. As long as the belts 122,124 are in intimate contact with one another as they rotate, they will have the same velocity at the point of paper contact. As a lift 126 proceeds around the turnover drum 120, however, the outside belt 124has a larger radius than the inside belt 122. That is, the outside belt 124 is disposed at a greater distance from the axis of rotation of the turnover drum 120 than the inside belt 122. As a result, the outside belt 124 will have a slightly faster tangential velocity than the inside belt 122 at the arc along the turnover drum 120. This resulting speed differential is particularly apparent along the essentially straight sections 124a, 122a of the parallel belts 124,122. As a result, the speed differential acting on the top and bottom surfaces of the lift 126 induces shear between the individual sheets, typically causing the outermost sheet and the lift 126 to slide in the direction of motion ahead of the innermost sheet. This cascading effect may be evenly distributed between the sheets or may tend to be concentrated between two particular sheets within the lift. In either event, this phenomenon is referred to as <BR> <BR> "shingling. "As an exemplary lift 126 is schematically illustrated in FIG. 3A, while a shingled lift 126 is schematically illustrated in FIG. 3B.

[0008] A number of factors influence the degree of shingling that a lift experiences.

For example, thicker lifts result in a greater differential velocity between the inside belt 122 and the outside belt 124. As a result, as the thickness of a lift increases, the degree of shingling typically increases. While a larger drum radius reduces the differential velocity between the inside and outside belts 122,124 in relative terms, the larger drum typically results in a longer paper path along which the differential velocity can affect the shingle. Further, the total length of the paper path in the turnover device is sufficiently long and/or the timing between the lifts entering the turnover device is sufficiently short, two or more lifts may be trapped between the inside and outside belts 122,124. In the event that the belts 122,124 do not stretch sufficiently, the increased velocity imparted to the outside belt 124 by a lift 126 going around the turnover drum 120 will induce a greater shear on any other lifts trapped between the belts 122,124 that have not yet reached the drum. This relationship can compound the total shingling a lift experiences prior to reaching the output stacker.

[0009] Turnover devices typically have no additional features to correct such shingling before the lift is inverted into the output stacker. As a result, if the paper punching machine is required to generate a varying stack or some future operation, e. g., feeding into a processing station such as an inserter or binder, the output stacking device must"square up"the sheets and eliminate the shingling. Depending upon the turnover device, the shingling may vary from, for example, as little as one-eighth of an inch to as much as one-half an inch or more. In general, the greater shingling the lift experiences, the more active and complicated the output stacker mechanism required to correct such shingling. Thus, while a drum style turnover device is a fairly simple mechanism to design and execute, in its present form it has a significant flaw that limits its effectiveness for use on paper processing machines needed to generate neat, square stacks.

OBJECTS OF THE INVENTION [0010] It is a primary object of the invention to provide an automated inverter that minimizes shingling in an inverted stack of sheets.

[0011] Another object of the invention is to provide an inverter that is of a non- complex design. A related object is to provide an inverter that requires minimal maintenance.

[0012] Another object of the invention is to provide an inverter that may be economically and efficiently manufactured.

[0013] These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.

BRIEF SUMMARY OF THE INVENTION [0014] In accordance with these and other aspects of the invention, there is provided an inverter arrangement which minimizes the resulting shingling in an inverted stack of sheets. The belt arrangement includes an approach path defined by an approach section, and an inversion path defined by an inversion section. The approach section typically includes an elongated relatively straight section disposed prior to engagement with the drum, while the inversion section is disposed along a portion of the periphery of the drum.

[0015] In a preferred embodiment, the inside belt thus includes an approach section and an inversion section, the inversion section being disposed about a portion of the periphery of the drum. In this way, the inside belt is driven by the rotation of the drum.

The belt arrangement further includes movement facilitators, preferably including an outside inversion belt. The portion of the outside inversion belt, which along with the inside belt defines at least a portion of the sheet path, however, extends substantially only along the inside belt inversion section. In this way, as the outside inversion belt contacts the inside belt, rotation is likewise imparted to the outside inversion belt.

[0016] Significantly, the outside inversion belt preferably does not extend along substantially any portion of the inside belt approach section. Rather, an outside movement facilitator in the form of either rotatable rollers or an outside approach belt is provided. When such freely rotatable rollers are utilized, any forward shingling along the approach path that would otherwise result from a more quickly moving outside belt is essentially eliminated along the approach section. That is, the rollers will have a surface speed substantially equal to that of the inside belt along the approach path.

Alternately, the rotatable rollers may be designed to provide a certain amount of drag along the top surface of the lift. In this regard, drag could be provided by either surface treatment of the rollers themselves or mounting of the rollers with a given drag that would resist rotation. As a result, the rotatable rollers could induce a certain negative shingling in a stack passing along the approach path.

[0017] Alternately, an outside approach belt may be provided which is linked to the outside inversion belt by reduction coupling. In this way, the outside approach belt would have a surface speed slightly less than the outside inversion belt surface speed. If the surface speed of the outside approach belt is thus made approximately equal to the surface speed of the inside belt, there will be essentially no or minimal shingling as a lift moves along the approach path. If, however, the surface speed of the outside approach belt is made less than the surface speed of the inside belt, a reverse shingling will be induced in the lift as it moves along the approach path. This difference between outside belt speeds may be accomplished by way of a simple reduction coupling or the like.

[0018] Alternately, the arrangement of the movement facilitators may be such that the movement facilitators along the inside of the approach path may be operated at a faster surface speed than the movement facilitators along the outside of the approach path. Thus, if a single outside belt is utilized having a surface speed along the sheet path that is greater than the surface speed of the inside belt along the inversion section, the more rapid surface speed of the movement facilitators along the inside of the approach path will minimize forward shingling or produce a reverse shingling, accomplishing the same objective as described above.

[0019] In embodiments where a reverse shingling is induced in the lift as it moves along the approach path, the reverse shingling will be counteracted by some degree by the forward shingling normally induced along the inversion path. It will thus be appreciated that the inventive inverter will minimalize shingling in the resulting inverted stack of sheets. Further, the inverter is of a relatively noncomplex design that may be economically and efficiently manufactured, while requiring minimal maintenance in use.

BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIGURE 1 is a fragmentary perspective view of a turnover device of the prior art.

[0021] FIG. 2 is a front elevational schematic view of an inverter device of the prior art.

[0022] FIG. 3A is a schematic view of a representative lift of sheets.

[0023] FIG. 3B is a representative schematic view of the lift of FIG. 3a having shingling induced therein as a result of travel along a paper path in a conventional inverter of the prior art.

[0024] FIG. 4 is a front elevational schematic view of an inverter constructed in accordance with teachings of the invention.

[0025] FIG. 5 is a front elevational schematic view of a second embodiment of an inverter device constructed in accordance with teachings of the invention.

[0026] FIG. 6 is a top plan view of the inverter device of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION [0027] Turning now to the drawings, there is shown in FIG. 4 an inverter device 10 for inverting individual sheets or lifts of multiple sheets. The inverter device 10 includes a rotatably mounted inverter drum 12 and movement facilitators, here, a belt arrangement 14, defining a lift path 16. It will be appreciate that the inverter drum 12 could alternately be stationary, but include a polished surface. The belt arrangement 14 includes an approach section 18 and an inversion section 20 defining an approach path 22 and an inversion path 24, respectively. The approach path 22 is defined by the relatively elongated and linear approach section 18 of the belt arrangement 14, while the inversion path 24 is defined by the arcuate inversion path 20 of the belt arrangement 14 as it extends about the periphery of the inverter drum 12. The approach and inversion paths 22,24 are further defined by inside and outside belts or other movement facilitators. In the illustrated embodiment of FIG. 4, the inside belt 26 extends partially about the periphery of the inverter drum 12 along an inversion section 26b, and further includes an elongated approach section 26a defining the approach path 22. The belt arrangement 14 further includes an outside inversion belt 28 which extends along and contacts the inside belt 26 along the inside belt inversion section 26b such that driven movement of the inside belt 26 likewise drives the outside inversion belt 28. An outside movement facilitator 30 is likewise provided along the upper side of the approach path 22. In the prior art devices, such as is shown in FIG. 2, the outside movement facilitator is actually an extended portion of the outside inversion belt 124 (see FIG. 2). As a result, in typical prior art structures, this outside movement facilitator is moving at the same surface speed as the outside inversion belt 124.

[0028] Inasmuch as movement is imparted to the outside inversion belt 28 as a result of its contact with the inside belt 26 along the inversion section 20 and with individual lifts along the inversion path 24, the actual surface speed of the outside inversion belt 28 along the sheet path is actually slightly greater than the surface speed of the inside belt 26. That being the case, forward shingling typically results in a lift moving along the sheet path. Such forward shingling results not only along the inversion section 20, but along the approach section 18 in the prior art structure inasmuch as the outside belt 28 extending along the approach section 18 similarly has a slightly greater surface speed than the inside belt 26 extending along the approach section 18.

[0029] In accordance with the invention, the movement facilitators or the belt arrangement 14 is provided to either essentially eliminate shingling or induce a reverse shingling along the approach section 18 by varying the speed or drag of the belts or other movement facilitators along the approach section 18.

[0030] In the first embodiment of the invention illustrated in FIG. 4, the outside movement facilitator is in the form of one or more rotatable rollers 32. It will be appreciated that if the rollers 32 are freely rotatable and induce no drag on the lift as it moves along the approach path 22, no shingling will be developed in the lift in the approach section 18. In contrast, if the rollers 32 induce a drag in the lift by either incorporating some drag in the rotation of the rollers 32 or if the rollers include a surface treatment (e. g. , a roughened surface or a rubber surface) that induces a drag in the lift, a negative shingling will develop in the lift as it passes along the approach path 22. Such a negative shingling would then be counteracted, at least in part, by the forward shingling that would be produced along the inversion path 24 as the lift passes around the inverter drum 12.

[0031] An alternate embodiment of the invention is illustrated in FIGS. 5 and 6. In this embodiment, the outside movement facilitator 30 is in the form of a separate outside approach belt 34. If there is sufficient space between the successive lifts passed along the approach path 22, the outside approach belt 34 may be freely rotatable such that the rotation induced in the belt 34 results from contact with the inside belt approach section 26a between the successive lifts. Under these circumstances, if there is no friction involved in the rotation of the outside approach belt 34, the outside approach belt 34 will have the same surface speed as the inside belt 26, that is, a slower speed than the outside inversion belt 28. As a result, essentially no shingling should be induced in a lift passed along the approach path 22. Conversely, if the outside approach belt 34 is not freely rotatable or rotates with a slower surface speed as the inside belt 26, a negative shear may be developed in a lift passed along the approach path 22.

[0032] According to one feature of the invention, the outside approach belt 34 may be driven with a surface speed that is less than that of the outside inversion belt 28. To provide this reduced surface speed, the outside approach belt 34 may be coupled to the outside inversion belt 28 by a reduction coupling 36. In the embodiment illustrated in FIGS. 5 and 6, the outside approach belt 34 is disposed about a plurality of rollers including rollers 38 and 40, roller 40 being secured to a shaft 42. Similarly, the outside inversion belt 28 is disposed along a plurality of rollers including roller 44, which is secured to a shaft 46. In this way, the outside approach belt 34 and the outside inversion belt 28 are disposed substantially in a line so that a lift passed along the approach path 22 passes from contact with the outside approach belt 34 to contact with the outside inversion belt 28 along the inversion path 24.

[0033] To accomplish the desired surface speed reduction of the outside approach belt 34, the reduction coupling 36 preferably includes rollers 48,50 which are secured to the shafts 42,46, respectively, for rotation therewith. A belt 52 extends about the rollers 48,50 such that the induced rotation of the roller 44 on shaft 46 by the outside inversion belt 28 causes a rotation of the roller 50, which is likewise disposed on shaft 46.

Rotation of the roller 50 drives the belt 52, which rotates roller 48, shaft 42 on which it is secured, and roller 40, inducing a rotation of the outside approach belt 34. It will be appreciated by those of skill in the art that the respective rollers 40,44, 48,50 may be relatively sized such that the outside approach belt 34 is caused to rotate with a surface speed that is less than the surface speed of the outside inversion belt 28. For example, roller 48 may be sized relatively larger than roller 50, as is shown in FIGS. 5 and 6, or roller 40 may be sized relatively smaller than rollers 44,48 and 50, or roller 44 may be sized relatively larger than rollers 48,50 and 40. Those of skill in the art will thus appreciate that alternate relative sizes may be used to accomplish this speed reduction.

As with the rotatable rollers 32 of the embodiment illustrated in FIG. 4, the outside approach belt may be rotated with a surface speed relative to the inside approach belt section 26a to result in either no shingling or reverse shingling.

[0034] It will further be appreciated by those of skill in the art that a similar result may be accomplished in an arrangement where the outside belt is a single belt, as illustrated, for example, the prior art illustrated in FIG. 2, the outside belt being designated by the reference number 124. In such an arrangement, however, the inside belt would include at least a pair of belts, one being disposed along the inversion path and the other being disposed along the approach path. Under this arrangement, however, the coupling would be sized to cause rotation of the inside belt along the approach path at a greater speed than the other inside belt along the inversion path, in effect, including a reduction coupling between the approach path and the inversion path of the inside belt. In this way, the surface speed of the inside belt along the approach path would be either the same as or greater than the surface speed of the outside belt along the approach path (as a result of the geometry of the rotation of the inside and outside belts around the inverter drum, the inside belt would have a slightly slower surface speed than the outside belt along the inversion path). It will thus be appreciated that the arrangement of movement facilitators, such as a belt arrangement, may thus be designed to provide the same surface speed along the approach path to minimize shingling, or the surface speed of the outside movement facilitator or belt may be designed to move at a slower surface speed than the inside belt along the approach path to result in a negative shingling approaching the inversion section.

[0035] In summary, the invention provides a mechanism by which the movement facilitators or belt arrangement may be designed to either minimize shingling along the approach path or induce a negative shingling along the approach path. In this way, forward shingling resulting from movement of a lift along the inversion path would either be minimized or counteracted by the negative shingling.

[0036] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0037] The use of the terms"a"and"an"and"the"and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms"comprising,""having," "including, "and"containing"are to be construed as open-ended terms (i. e. , meaning<BR> "including, but not limited to, ") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e. g. ,"such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0038] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above- described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

WHAT IS CLAIMED IS: 1. An invertor device for inverting at least one sheet, the invertor device comprising at least one inside movement facilitator and at least one outside movement facilitator defining a sheet path for providing forward movement of said sheet, said sheet path comprising an approach sheet path and an inversion sheet path, said at least one inside movement facilitator comprising an inside approach section and an inside inversion section, said inside approach section having an inside approach surface speed along the approach sheet path, said inside inversion section having an inside inversion surface speed along the inversion sheet path and defining an arcuate path having a radius, said at least one outside movement facilitator comprising an outside approach section and an outside inversion section, said outside approach section having an outside approach surface speed along the approach sheet path, said outside inversion section having an outside inversion surface speed along the inversion sheet path and defining an arcuate path having a radius greater than the radius of the at least one inside inversion section, and at least a portion of the outside approach section having a substantially equal or slower outside approach surface speed than the inside approach surface speed of an adjacently disposed inside approach section portion resulting in minimized shingling or negative shingling in a plurality of said sheets following said sheet path along the portions.

2. The invertor of claim 1 comprising at least two outside movement facilitators, a first said outside movement facilitator being disposed along the outside approach section and a second said outside movement facilitator being disposed along the outside inversion section.

3. The invertor of claim 2 wherein said inside inversion section is driven, and wherein said first outside movement facilitator is a belt, said belt being driven by contact with said inside inversion section.