SHEET STACKER COMPRISING A SHEET FLIPPING DEVICE AND A SUPPORT DEVICE

Abstract

During flipping sheets may fold upon themselves under the influence of gravity. To prevent a sheet stacker is provided with a support device for supporting an inner surface of the sheet during flipping, the support device comprising a plurality of flexible fingers elements of different length, each configured to support a different inner area of the sheet during its flipping motion.

Claims

1. A sheet stacker comprising : A sheet flipping device for flipping a received sheet around a flipping axis with respect to an orientation wherein the sheet was received; A support device for supporting a surface of the sheet facing the flipping axis during the flipping of the sheet, the support device comprising a plurality of flexible fingers elements of different length, each configured to support a different inner area of the sheet during its flipping motion.

2. The sheet stacker according to claim 1, wherein the sheet flipping device comprises a flipping wheel provided with at least one slot for receiving the sheet.

3. The sheet stacker according to claim 2, wherein the support device rotatable around the flipping axis.

4. The sheet stacker according to claim 3, wherein the support device is at a different angular position than the slot.

5. The sheet stacker according to claim 1, wherein the support device is rotatable around the flipping axis independently from the flipping device.

6. The sheet stacker according to claim 1, wherein the flexible fingers elements of the support device are moveable between a first position, wherein the support device is positioned outside the path of an incoming sheet which sheet is to be received by the flipping device, and a second position, wherein the support device contacts the sheet.

7. The sheet stacker according to claim 6, wherein the flipping device is moveable between a receiving position for receiving a sheet and a ejecting position for releasing the sheet from the flipping device, wherein the support device is in the first position when the flipping device is in the receiving position and moves to the second position when the flipping device moves from the receiving position to the ejecting position.

8. The sheet stacker according to claim 1, wherein the finger elements are configured to move radially outward as it passes through a flipping volume through which the sheet is flipped.

9. The sheet stacker according to claim 8, wherein the finger elements are configured to move radially inward outside of the flipping volume when approaching a sheet supply path for transporting sheets to the flipping device.

10. The sheet stacker according to claim 9, wherein the finger elements are elastic, such that they expand radially outward after passing by the sheet supply path.

11. The sheet stacker according to claim 8, wherein further comprising a guide element positioned between a trajectory of a sheet on the sheet supply path and the support device, such that contact between the support device and the guide element moves the flexible finger element radially inwards.

12. The sheet stacker according to claim 7, further comprising a guide element positioned between a trajectory of a sheet on the sheet supply path and the support device, such that contact between the support device and the guide element moves the flexible finger element radially inwards, wherein the guide element is positioned such that a trajectory of a sheet from the sheet supply path into the flipping device in the receiving position is unobstructed by the support device.

13. The sheet stacker according to claim 12, wherein the stop element is formed by a transport pinch of the sheet supply path.

14. A printer comprising a sheet stacker according to claim 1.

15. A method for stacking sheets, comprising the step of flipping a sheet around a flipping axis, the step of a support device moving radially outward with respect to the flipping axis to support an inner surface of the sheet facing the flipping axis, and the step of the support device supporting the inner surface of the sheet during flipping of said sheet, wherein the support device comprising a plurality of flexible fingers elements of different length, each supporting a different inner area of the sheet during its flipping motion.

16. The method according to claim 15, comprising the step of moving the plurality of flexible fingers of the support device radially outward through an inner volume of the folding sheet to engage the inner surface and to limit the folding movement.

17. The method according to claim 16, further comprising the step of moving the plurality of flexible fingers of the support device radially inward, such that the plurality of flexible fingers do not pass through a trajectory of a sheet being fed from a sheet supply into a flipping device.

18. The method according to claim 17, wherein the step of flipping the sheet comprises rotating the flipping device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0025] FIG. 1 is a schematic cross-sectional side view of the sheet stacker according to the present invention when receiving a sheet;

[0026] FIG. 2 is a schematic cross-sectional side view of the sheet stacker of FIG. 1 with the leading edge of the sheet at its ejecting position;

[0027] FIG. 3 is a schematic cross-sectional side view of the sheet stacker of FIG. 1 with the support device supporting the sheet;

[0028] FIG. 4 is a schematic cross-sectional side view of the sheet stacker of FIG. 1 when receiving a further sheet after stacking the sheet;

[0029] FIG. 5 is a schematic cross-sectional side view of another embodiment of the sheet stacker according to the present invention; and

[0030] FIG. 6 is a schematic cross-sectional side view of a further embodiment of the sheet stacker according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] 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.

[0032] FIG. 1 illustrates a schematic cross-sectional side view of a sheet stacker 1 according to the present invention. The sheet stacker 1 comprises a sheet flipping device 2. The sheet flipping device 2 comprises a flipping wheel 3 rotatable around the flipping axis 7. A slot 4 is provided on the circumference of the flipping wheel 3 to receive sheets S from the sheet supply path 10. When the leading edge of the sheet S is engaged in the slot 4, the flipping wheel 3 is rotated, bringing the engaged leading edge against the stop element 5. The stops element 5 is positioned besides the flipping wheel 3 or multiple stop elements 5 may be present in the between multiple flipping wheels 3 in the direction of the flipping axis 7. Contact with the stop element 5 causes the sheet S to be released from the slot 4. The trailing portion of the sheet S continues to be fed into the flipping volume by the transport devices 11, 12 of the sheet supply path 10. This causes the sheet S to fold and flip. The support device 20 which is formed of a plurality of flexible finger elements 21 is mounted on the flipping wheel 3 at a predetermined angle from the slot 4.

[0033] In FIG. 1, the flipping wheel 3 is positioned in its receiving position, which aligns the slot 4 with the sheet supply path 10. By means of the transport devices 11, 12 a sheet S is moved via the guides 14 towards and into the slot 4. The flipping wheel 3 during insertion may be stationary or move at a reduced speed, which allows the sheet S to move into the slot 4. Between the sheet supply path 10 and the flipping axis 7, the support device is forced into its first position by contact with the sheet supply path 11. The bottom roller of the transport pinch 11 in FIG. 1 acts as a guide element, which urges or presses the finger elements 21 radially inwards towards the circumference of the flipping wheel 3. The guide element ensures that the support device 20 is in its first, radially inward position while in the first angular range 9A. It will be appreciated that such a guide element may be embodied in other forms, such as a guide plate or block, either as part of the sheet supply path 10 or as a separate unit. This radially inward urging combined with the radially offset position of the support device 20 with respect to the slot 4 moves the support device 4 out of the way of sheets S which are transferred from the sheet supply path 10 to the slot 4.

[0034] FIG. 2 illustrates the flipping wheel 3 bringing the leading of the sheet S against the stop element 5. With respect to FIG. 1 the flipping wheel 3 is rotated a predetermined angle, in this example roughly 90°, towards the ejecting position shown in FIG. 2. The leading edge of the sheet S is held by the slot 4 and consequently rotated against the stop element 5. The transport devices 11, 12 are operated at sufficient velocity such that the trailing portion of the sheet S follows the leading edge. Engagement with the stop element 5 causes the sheet S to be released from the slot 4. The slot 4 passes by the stop element 5, allowing the flipping wheel 3 to continue its rotation back to the receiving position.

[0035] The support device 20 follows the slot 4 and moves into the second angular range 9B, which corresponds to the flipping volume through which sheets S are flipped. The finger elements 21 having past the guide element, which urges them towards the circumference of the flipping wheel start to expand radially outward. At least the free ends of the finger elements 21 move against the inner surface of the sheet S. Further radial outward movement of the finger elements 21 may be limited, as the trailing portion of the sheet S may still be engaged by the transport device 11. After the leading edge of the sheet S is stopped against the stop element 5, the transport device 11 continues to feed the trailing portion into the flipping volume of the flipping device 2. This results in a fold being formed in the sheet S, which fold moves away from the flipping axis 7 as more of the trailing portion passes by the transport device 11.

[0036] FIG. 3 illustrates the release of the trailing portion of the sheet S from the transport device 11. The sheet S in this example is very flexible, for example formed of low grammage paper or a thin plastic foil. Instead of rolling away from the flipping axis 7 and completing the flipping motion, the fold in such flexible sheets S tends to cause such sheets S collapse upon themselves under the influence of gravity. This is prevented by the finger elements 21 which are moved further radially outward due to the continued rotation of the flipping wheel 3. The finger elements 21 may be formed as long strips, sheets, rods, etc. The finger elements 21 extend tangentially backwards from the circumference of the flipping wheel 3. The finger elements 21 expand radially outward inside the inner volume 8 inside the fold of the sheet S. The finger elements 21 are preferably sufficiently flexible such that these are moved outward by the centrifugal forces. The finger elements 3 may further be provided with a certain rigidity or elasticity which aids in their outward movement after passing the guide element. As the sheets S are generally low weight relatively small forces are required for effectively supporting the sheet S. This allows the finger elements 21 to be formed of low costs materials. The flexibility allows the finger elements 21 to easily conform to the fold shape of the sheet S, which fold shape may vary dependent on sheet dimensions and materials. The flexibility further allows the finger elements 21 to pass between the flipping wheel 3 and the stacking surface 6 at the stop element 5. This allows existing sheet stackers to be updated with such a support device with little to no changes to the existing hardware.

[0037] In the second angular range 9B between the receiving position and the ejecting position, the finger elements are in their second position, which is more radially outward as compared to their first position at the guide element, which urges the finger elements 21 towards or against the circumference of the flipping wheel 3 in the first angular range 9A. Similarly, the finger elements are urged into their first, radially inward position by the stacking surface, as the finger elements 21 pass by the stop element 5. Allowing the finger elements 21 to move radially outward during the flipping of the sheet S, allows for a compact solution, which does not increase the overall dimensions of the sheet stacker 1.

[0038] FIG. 4 illustrates the sheet S being flipping and positioned on the sheet stacking surface 6. The flipping wheel 3 has rotated to its receiving position as shown in FIG. 1. A further sheet S may be received into the slot 4 and stacked on top of the flipped sheet S to form a sheet stack.

[0039] FIG. 5 illustrates another embodiment of a sheet stacker 100 according to the present invention. It will be appreciated that similar components as in FIGS. 1 to 4 are indicated with similar reference numbers and will not be discussed in detail here again. The support device 120 in FIG. 5 is formed of a plurality of support bodies 121, with each support body being moveable along its predetermined path 122 from a radially inward position (indicated with the dashed contours) to a radially outward position, as shown in FIG. 5. When receiving a sheet S the support bodies 121 are positioned out of the trajectory of the incoming sheet S at their radially inward positions within the circumference of the flipping wheel 3. During flipping as the fold is formed in the sheet S, the support bodies 121 are moved with appropriate speed and timing to come into contact with the inner surface of the sheet S to prevent the sheet S from folding upon itself. The support bodies 121 may be moved along their paths 122 by arms or guides. For example, an actuator may be provided in between neighboring flipping wheels 3, which extends into the inner volume of the sheet S.

[0040] FIG. 6 shows a further embodiment of a sheet stacker 200 according to the present invention. In contrast to FIGS. 1 to 5, the support device 220 in FIG. 6 is provided on its own rotational body 224 and not directly on the flipping device 202. The rotational body 224, which is formed as a wheel 224, is rotational around the flipping axis 7 independent of the flipping wheel 203. The rotational position and/or speed of the rotational body 224, and thus of the support device 220, may be controlled differently from those of the flipping wheel 203. A first drive or motor (not shown) is provided to control the rotation of the flipping wheel 203 and a second drive or motor (not shown) is provided to rotate the support device 220.

[0041] The flipping wheel 203 is similar to those in FIGS. 1 to 5, but with the addition of a second slot 204B. The first and second slots 204A, 204B are angularly offset, in this example by 180°, though any number of slots may be applied within the context of the present invention. The support device 220 comprises a plurality of finger elements 221, 222, 223, which in this example are embodied in groups 221, 222, 223 which are distributed along the circumference of the rotational body 224. In FIG. 6, three finger element groups 221, 222, 223 are distributed at 120° with respect to one another, though any suitable number of groups may be applied. The number of finger element groups 221, 222, 223 may be the same or different from the number of slots 204A, 204B on the flipping wheel 203. The angle in this case is measured from a mounting of each finger element group 221, 222, 223 on the rotational body 224. The number of groups, positions, materials, and dimensions of the finger elements 221, 222, 224 are selected in accordance with the properties of the sheets to be stacked, the dimensions of the flipping wheel 202, and/or the dimensions of the rotational body 224.

[0042] Independent control of the movement of the support body 220 with respect to that of the flipping device 202 allows the finger elements 221, 222, 223 to be more accurately positioned where support is needed under the sheet S. It further aids in improving the media range of the sheets to be stacked to achieve handling of a wider variety of sheet dimensions and materials. Such independent control also allows the support body to be positioned in an angular position out of the way of the incoming sheet with use of a guide element. After insertion of the sheet into the slot 204A, 204B, the rotational body may be suitably accelerated to position the finger elements 221, 222, 223 under the trialing portion of the sheet S, as the sheet S begins to fold outward.

[0043] Although specific embodiments of the invention are illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiment or exemplary embodiments are examples only and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0044] It will also be appreciated that in this document the terms “comprise”, “comprising”, “include”, “including”, “contain”, “containing”, “have”, “having”, and any variations thereof, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus or system described herein is not limited to those features or parts or elements or steps recited but may include other elements, features, parts or steps not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms “a” and “an” used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms “first”, “second”, “third”, etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.

[0045] The present 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 present 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.