Pallet unit for stacking sheets with a central lifting device

Abstract

Transport device (20) for transporting a stack (10) of print media, the transport device (20) comprising: - a support body (22) mounted on at least one support foot (24), wherein the support foot (24) extends perpendicular to a print medium support surface (26) and is positioned on a side of the support body (22) opposite the print medium support surface (26), wherein the print medium support surface (26) is configured to support the stack (10) of print media, characterized by a lifter (27) which is movable at least partially through a recess (25) between a first position in which the lifter (27) is at least partially above the print medium support surface (26) and a second position in which the lifter (27) is below or at the level of the print medium support surface (26).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The invention relates to a transport device for transporting a stack of print media, a pallet unit designed as such a transport device, a stacker for use with such a transport device and a printer with such a stacker. 2. Description of the state of the art

[0002] It is known to use pallet units in printers for stacking sheets. In the unpublished patent application EP 23 200 468.9, for example, the pallet unit is positioned on a pallet holder. The sheets are stacked directly onto the pallet using a stacking device. It has been found that the stacking capacity, i.e., the maximum number of sheets that can be stacked into a single stack, is limited due to the uneven compaction of the stack. This uneven compaction causes the outer edges of the stack to curl upward due to the relatively stronger compaction in the center of the stack compared to the center. SUMMARY OF THE INVENTION

[0003] It is an object of the invention to increase the stacking capacity when stacking sheets on a pallet unit in a stacker of a printer.

[0004] According to the invention, a transport device for transporting a stack of print media according to claim 1, a pallet unit according to claim 8, a stacker according to claim 9 and a printer according to claim 14 are provided.

[0005] The transport device includes: - a support body mounted on at least one support foot, wherein the support foot extends perpendicular to a print medium support surface and is positioned on an opposite side of the support body with respect to the print medium support surface, wherein the print medium support surface is configured to support a stack of print media.

[0006] The transport device is characterized by a lifter which is movable at least partially through a recess between a first position in which the lifter is located at least partially above the print medium support surface during use, and a second position in which the lifter is located below or at the level of the print medium support surface during use.

[0007] The at least one support foot ensures that the support body is above the surface on which the at least one support foot stands, so that the transport device can be easily picked up, for example by engaging the underside of the support body with a forklift. The transport device can be designed, for example, as a pallet unit. The aforementioned recess is provided in the support surface for the printing medium so that the lifter can engage the underside of a stack when a stack is resting on the support surface. In a second position, the lifter is retracted into the recess so that the printing medium support surface is freely accessible for positioning or handling the first sheets of a stack thereon. In the second position, the lifter does not hinder the stacking device during its stacking process. The same applies to any other device used to handle the sheets on the support body.When the stack height becomes so large that uneven compaction of the stack begins, the lifter is moved to the first position, extending upward through the recess above the print media support surface. This lifts a central section of the stack. This reduces uneven compaction, allowing more sheets to be stacked until the uneven compaction prevents further stacking with the stacker.

[0008] In one embodiment, the recess is located at an edge of the support body. The edge with the recess is the edge adjacent to the stacking device during stacking. This reduces uneven compaction on the side of the stack where the sheets are fed into the stack.

[0009] In one embodiment, the recess is located in the center of the edge. The lifter is a central lifter positioned to lift a central portion of the stack. "Central" here means a location close to the center of the stack, viewed horizontally.

[0010] In one embodiment, the transport device further comprises a joint for pivoting the lifter between the first and second positions. The lifter is movable through the recess between the first and second positions. The movement path of the lifter is defined by the joint. The lifter is preferably connected to a pivot axis via a pivot arm. The joint is preferably attached to the support body.

[0011] In one embodiment, the transport device further comprises a limiting device that determines an end point of the pivoting range of the lifter, which in turn defines the second position. The second position is determined by the limiter, which forms an end point on one side of the lifter's travel path. The limiter is, for example, a stop that ensures that the lifter abuts the recess in the second position.

[0012] In one embodiment, the recess extends at least partially over the at least one support leg, so that the support leg forms the boundary. The support leg blocks the movement of the jack in one direction. During a downward movement, for example, the pivoting body or pivoting arm touches the support leg, preventing further downward movement. The recess is located above the support leg, so that an upper side of the support leg is accessible via the recess to form an end stop for the movement of the jack.

[0013] In one embodiment, the support body and the at least one support foot are formed from panels, preferably from wood panel material. The support body is preferably a panel in which the recess is provided as an indentation or cutout along one of its edges. Alternatively, the recess can also be designed as a hole or through-bore. The support foot is also designed as a panel mounted vertically on the panel of the support body. Preferably, at least two support feet are provided on or at opposite edges of the support body. Wood is a suitable and easy-to-work material for such a transport device. Other suitable materials can also be used.

[0014] The invention further relates to a pallet unit configured as a transport device according to one of the preceding embodiments. The transport device is preferably a pallet unit as known from the prior art. The pallet unit is provided with the recess and the lifter.

[0015] The present invention further relates to a stacker having a stacking device for stacking sheets on a print medium support surface of a pallet holder, wherein the pallet holder is further configured to support a transport device such that the stacking device is capable of stacking sheets on the print medium support surface of the transport device. The stacking device is characterized by a lifter that is movable through a recess in the print medium support surface of the transport device between a first position, in which the lifter is located at least partially above the print medium support surface during use, and a second position, in which the lifter is located below or at the level of the print medium support surface of the transport device during use.

[0016] The stacker includes a lifter that can be moved through the recess so that, during use, it extends over the print media support surface on the transport device. This allows the lifter to locally raise a (central) portion of the stack to reduce the uneven compaction effect and thereby increase stacking capacity, as explained above. The lifter can be retracted to the second position at or below the print media support surface so that it is out of the way of the stacker and the first sheet(s) to be stacked.

[0017] In one embodiment, the pallet holder comprises a drive for moving a lifting body of the pallet holder between: - an upper position in which the lifting body of the pallet holder is located below a lifting body of the central lifter of the transport device, so that the latter lifting body is located at least partially above the pressure medium support surface of the transport device during use, and - a lower position in which the lifting body of the pallet holder is located below the lifting body of the central lifter of the transport device, so that the latter lifting body is located below or at the level of the pressure medium support surface of the transport device during use. The drive is designed to raise and lower the lifting body of the pallet holder. The lifting body of the pallet holder is arranged so that it touches the lifting body of the transport device and thereby lifts it. The drive pushes the lower lifting body of the pallet holder upwards until it touches the lifting body of the transport device. The drive then moves the lower lifting body of the pallet holder further upwards, thereby pushing the upper lifting body of the transport device upwards into the first position. Lowering the lifting body of the pallet holder causes the lifting body of the transport device resting on it to also be lowered.Likewise, a single drive is sufficient to prevent uneven compaction during stacking directly on the pallet holder and on the transport device. Preferably, the drive is also configured to raise and lower the support body of the pallet holder, on which the transport device rests.

[0018] In one embodiment, the pallet holder comprises receiving means for receiving the at least one support foot of the transport device, so that the recess of the transport device in the received state lies at least partially above the lifting body of the pallet holder.

[0019] The receiving means, e.g., a slot or a locking mechanism on the pallet holder, determine the position of the transport device on the pallet holder. This position is selected so that the lifters of the pallet holder and the transport device overlap vertically. The lifting bodies are arranged one above the other so that the upward movement of the lower lifting body drives the upper lifting body upward against the underside of the stack. Preferably, the support body of the pallet holder comprises several parallel support fingers, between which the support feet of the transport device can be accommodated.

[0020] In one embodiment, the lifting body of the pallet holder can be moved to the upper position to contact a lifting body of the transport device, thereby bringing the lifting body of the transport device into the second position.

[0021] In one embodiment, the lifter of the transport device comprises a lifting body attached to the transport device by means of a joint. In another embodiment, the transport device can be provided with a drive to move the lifting body between the first and second positions. In a further embodiment, the pallet holder can be configured so that sheets can be stacked directly on it when no transport device is located thereon. The lifter of the pallet holder can be configured similarly or identically to that of the transport device. The pallet holder can further be provided with a drive for raising and lowering the lifting body of the pallet holder, which, if a transport device is present, also raises and lowers the lifting body of the transport device. Any suitable drive can be used as the drive, such as an (electric) motor, a linear drive, a pneumatic drive, etc.

[0022] The present invention further relates to a printer with a stacker according to one of the above embodiments. The printer is preferably a sheet-fed printer having a stacker with a stacking device.

[0023] Further scope of applicability of the present invention will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be better understood from the following detailed description and the accompanying drawings, which are given for illustrative purposes only and thus are not limitative of the present invention. In the drawings: Fig. 1 is a schematic cross-sectional view of a stacking device with a pallet unit underneath according to the prior art, which supports an unevenly compacted stack of print media; Fig. Figure 2 is a schematic cross-sectional view of a stacking device under which a pallet unit according to the invention is located; Fig. 3 is a perspective view of a stacker with a pallet unit in a first step of insertion into a stacking device of a stacker of a printer according to the invention; Fig. 4 is a perspective view of the stacker with the pallet unit in a second step of loading into the stacking device of the stacker of the printer according to the invention; Fig. 5 is a perspective view of the stacker with the pallet unit in a third step of loading into the stacking device of the stacker of the printer according to the invention; Fig. 6 is a cross-sectional view of the stacker including the pallet unit in the first step of insertion into the stacking device of the stacker of the printer according to the invention; Fig. 7 is a cross-sectional view of the stacker with the pallet unit in the second step of loading into the stacking device of the stacker of the printer according to the invention; Fig. 8 is a cross-sectional view of the stacker with the pallet unit in the third step of loading into the stacking device of the stacker of the printer according to the invention; Fig. 9 a schematic perspective view of the pallet unit in the Fig. 3 to 8 with a central lifter in its first position; and Fig. 10 a schematic perspective view of the pallet unit in the Fig. 3 to 9 with the central lifter in its second position. DETAILED DESCRIPTION

[0025] The invention will now be described with reference to the accompanying drawings, in which the same reference numerals are used to identify the same or similar elements in the several views. printing system

[0026] Fig. 1 shows a transport device 20' for handling stacks 10' of print media. The transport device 1' comprises a support body 22' having a print medium support surface 26'. Two or more support feet 24' are attached to the support body 22' opposite the print medium support surface 26'. The support feet 24' extend away from the print medium support surface 26' in a direction perpendicular to the print medium support surface 26'. This results in a free space 25' for the support feet 24' below the support body 22'. Fig. 1, the transport device 20' is designed as a pallet unit. This pallet unit can be made of any suitable material, e.g., wood, metal, plastic, etc.

[0027] In Fig. 1, the transport device 20' is positioned in a stacking position relative to a stacking device 3'. Such a stacking device 3' is known, for example, from US 9 457 980 B2. The stacking device 3' comprises a rotatable turning wheel with one or more slots for receiving a leading part of a print medium. The turning wheel is rotated so that the held sheet is pivoted onto the transport device 20'. The sheet is released from the stacking device 3' by contact with a stop element. In this way, several sheets can be stacked on top of one another by lowering the transport device 20' relative to the stacking device 3' as the stack height increases. As the stack 10' grows, its central part 12' can compress more strongly than its outer edges under the influence of gravity, as shown in the cross-section in Fig. 1. As a result, the outer edges of the top sheet in the stack 10' are in a higher position than the middle section 12'. In Fig. 1, the stacking device 3' is positioned relative to the stack 10' so that it corresponds to the height of the central section 12'. In the situation of Fig. 1, the upwardly rolled edges then come into contact with the outer turning wheels of the stacking device 3'. This prevents the stacking device 3' from stacking any further sheets, so that the maximum capacity of the stack 10' is limited by this uneven compaction of the stack.

[0028] Fig. 2 shows that the maximum capacity of a stack 10 compared to the situation in Fig. 1 can be improved by providing a central lifter 27 which can lift a central portion 12 of the stack 10 via a recess 25 in a support body 22 of a transport device 20. It is pointed out that the stacking device 3 and the transport device 20 are similar to Fig. 1 and that similar components are provided with similar reference numerals. The lifter 27 is movable through the recess 25 so that it can locally lift the central portion of the stack 10 above a print medium support surface 26. The central portion 12 is thereby lifted at its underside, resulting in a curvature which, compared to that of the upper sheets in the stack 10', Fig. 1 is reversed. Raising the middle section increases the capacity of the stack 10, as the effect of uneven compaction is at least partially reduced. The height at which the stacking device 3 touches the upwardly directed outer edges of the top sheet is greater than in Fig. 1.

[0029] Fig. 3 to 5 show the transport device 20 when it is arranged in a stacker 40 of a printer. The stacker 40 comprises a pallet holder 30, e.g., in the form of a tray, as is commonly used in printers. The pallet holder 30 comprises a support body 32 ( Fig. 7). The support body 32 consists of a plurality of parallel support fingers 33. The upper sides of the support fingers 33 together form a support surface 36 for the printing medium, on which the sheets are stacked by means of the stacking device (in the Fig. 3 to 5 not shown). The support body 32 of the pallet holder 30 is movable relative to the stacking device 3 by means of a drive 34. During stacking, the support body 32 of the pallet holder 30 is lowered relative to the stacking device 3 so that the uppermost sheet of the stack remains substantially at the level of the stacking device 3. The support body 32 of the pallet holder 30 also comprises a central lifter 37. The central lifter 37 of the pallet holder 30 is arranged to raise the central lifter 27 of the transport device. The support body 32 is configured to support the transport device 20 and can optionally also be configured so that sheets are stacked directly thereon when no transport device is present. The support body 30 can comprise one or more receiving and positioning means for receiving the support feet 24 of the transport device 20.The mounting and positioning devices are in . Fig. 3 are formed as slots between the support fingers 33. The slots are preferably arranged such that the transport device 20 is in a predetermined, fixed position relative to the support body 32 when mounted thereon. This ensures that the central lifter 37 is aligned with the central lifter 27. It goes without saying that other receiving and positioning means, such as recesses, locks, clamps, etc., can also be used to appropriately receive and hold the support feet 24.

[0030] Fig. 3 and Fig. 6 show the step of inserting the support feet 24 of the transport device 20 between the support fingers 33 by moving the transport device 20 in the Y-direction. In doing so, a lifting body 29 of the upper central lifter 27 is positioned above a lifting body 39 of the lower central lifter 37. The lower central lifter 37 is formed by a projection on an outer one of the support fingers 33. Preferably, the projection is designed as a smoothed bead. The lifting body 29 of the transport device 20 preferably has a similar shape and / or size, but is movably mounted on the support body 22. Viewed in the Z-direction, the support body 29 fits into the recess 25, which is in the Fig. 4 and Fig. 7 is arranged overlapping with the lifting body 39 on the support finger 33, viewed in the Z direction.

[0031] In the Fig. 4 and Fig. 7, the transport device 20 is arranged with its support feet 24 between the support fingers 33 on the stacking device 1. The support feet 24 extend in the Y direction, as do the support fingers 33. Preferably, a support foot 24 is pushed in the X direction into contact with a predetermined one of the support fingers 33. Additionally, a stop can also be provided in the X direction, so that upon contact with the stop, the upper lifter 27 lies above the lower lifter 37. As a result, the transport device 20 is positioned with respect to the pallet holder 30 such that the lifter 27 is located at the same location in the X direction as the lifter 37. In Fig. 4, the support body 32 of the pallet holder 30 is arranged at a distance below the support body 22 of the transport device 20. The support feet 24 of the transport device 20 rest on a lower support 50. This enables quick and easy loading of the transport device 20.

[0032] The Fig. 5 and Fig. 8 shows the step of raising the support body 32 with the support fingers 33 in the Z direction by actuating the drive 34. The support fingers 33 move upward until they rest against the underside of the support body 22 of the transport device 20. By raising the support fingers 33, the transport device 20 is raised and its height position relative to the stacking device 3 can be controlled. During the upward movement, the central lifter 37 on the last support finger 33 is brought into contact with the central lifter 27 of the transport device 20 in the X direction. Since the lifter 27 is movable relative to the support body 22, the lifter 27 is pressed upward by the recess 25 so that it extends over the print medium support surface 26 of the support body 22.

[0033] In Fig. 9 and Fig. 10, the transport device 20 is shown. The support body 22 is mounted on two spaced-apart support feet 24, which keep the support body 22 at a distance from the surface on which the support feet 24 rest. The support body 22 and the support feet are preferably made of a sheet or plate material such as wooden boards. Other materials such as plastic, metal, composite materials, etc. can also be used. The recess 25 is provided on an outer edge of the support body 22. This edge is the edge that borders the stacking device 3 when the transport device 20 is positioned in the stacker. The central lifter 27 comprises a lifting body 29, which rests against the underside of the stack 10. The lifting body 29 has a smaller cross-section in plan view than the recess 25, so that the lifting body 29 can pass through the recess 25.The lifting body 29 has a curved upper surface that follows the curvature of the lower sheet in the stack 10, thereby preventing the sheet from being indented. The center of the upper surface may be flattened. The lifting body 29 is held by a joint 21. The joint 21 has an arm that is journaled in a pivot bearing attached to the support body 22. The joint 21 enables the lifting body to be raised to the first position in which it extends over the support surface 22 of the printing medium, as shown in FIG. Fig. It is clear that the central lifter 37 can be configured similarly, but is provided with a drive 38. In the present example, the lifting of the two central lifters 27, 37 is controlled by the drive 38. When not raised, the joint 21 allows the lifting body 29 to rest in the second position ( Fig. 6), in which the lifting body 29 is located below the pressure medium support surface 22. In Fig. 6, the recess 25 at least partially overlaps the support foot 24, so that the support foot 24 limits the pivoting movement of the lifting body 29 and determines the second position. The joint 21 is designed such that the lifting body 29 returns to the second position under the influence of gravity when no upward force acts on it.

[0034] The lifting body 29 can be made of any suitable material, e.g., plastic, wood, metal, rubber, etc. The lifting body 29 can be formed using any suitable process, such as 3D printing, injection molding, cutting, milling, etc. It goes without saying that other shapes of the lifting body 29 can also be used. The recess 35 can be positioned at any suitable location and, e.g., formed by a through-hole in the support body 22. It is further clear that in the example in Fig.3 a single central lifter 37 can also be used, which can move through both recesses 25, 35.

[0035] It is understood that the invention can also be applied analogously to the input side of a printer. In this case, the transport device 20 is provided in a sheet input module, which, instead of a stacking device 3, comprises a sheet separator for separating individual sheets from a stack on the transport device 20.

[0036] Although specific embodiments of the invention are shown and described herein, those skilled in the art will recognize that numerous alternative and / or equivalent embodiments exist. It should be understood that the exemplary embodiment or exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description are intended to provide one skilled in the art with a convenient road map for implementing at least one exemplary embodiment; it should be understood that various changes may be made in the function and arrangement of the elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.In general, this application is intended to cover any adaptations or variations of the specific embodiments described herein.

[0037] As used in this document, the terms "comprise," "comprising," "include," "including," "contain," "containing," "having," "having," and all variations thereof are to be construed in an inclusive (i.e., non-exclusive) sense, such that the process, method, device, apparatus, or system described herein is not limited to the features, parts, elements, or steps recited, but may include other elements, features, parts, or steps not expressly listed or pertinent to the process, method, device, or apparatus. In addition, the terms "a" and "an" as used herein are to be construed to mean one or more, unless expressly stated otherwise. In addition, the terms "first," "second," "third," etc.used merely as designations and are not intended to impose numerical requirements on their objects or to establish a particular order of importance.

[0038] Having thus described the present invention, it will be obvious that it is susceptible to variation in many respects. 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. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 23 200 468.9

[0002] US 9 457 980 B2

[0027]

Claims

[1] Transport device (20) for transporting a stack (10) of print media, the transport device (20) comprising: - a support body (22) mounted on at least one support foot (24), wherein the support foot (24) extends perpendicular to a print medium support surface (26) and is positioned on a side of the support body (22) opposite the print medium support surface (26), wherein the print medium support surface (26) is configured to support the stack (10) of print media, characterized by a lifter (27) which is movable at least partially through a recess (25) between a first position in which the lifter (27) is located at least partially above the printing medium support surface (26) and a second position in which the lifter (27) is located below or at the level of the printing medium support surface (26). [2] Transport device according to claim 1, wherein the recess (25) is arranged on an edge of the support body (22). [3] Transport device according to claim 2, wherein the recess (25) is arranged in the center of the edge. [4] Transport device according to one of the preceding claims, with a joint (21) for pivoting a lifting body (29) of the lifter (27) between the first and the second position. [5] Transport device according to claim 4, with a limiting device which determines an end point of the pivoting range of the lifting body (29), which in turn determines the second position. [6] Transport device (20) according to claim 5, wherein the recess (25) extends at least partially over the at least one support foot (24), so that the support foot (24) forms the limiting device. [7] Transport device (20), in which the support body (22) and the at least one support foot (24) are formed from panels, preferably from wood panel material. [8] Pallet unit in the form of the transport device (20) according to one of the preceding claims. [9] Stacker (40) with a stacking device (3) for stacking sheets on a print medium support surface (36) of a pallet holder (30), wherein the pallet holder (30) is further configured to carry a transport device (20) so that the stacking device (3) is capable of stacking sheets on a print medium support surface (26) of the transport device (20), characterized bya lifter (27, 37) which is movable through a recess (35) in the printing medium support surface (26) of the transport device (20) between a first position in which the lifter (27, 37) is located at least partially above the printing medium support surface (26) during use, and a second position in which the lifter (27, 37) is located below or at the level of the printing medium support surface (26) of the transport device (20). [10] Stacker (40) according to claim 9, wherein the pallet holder (30) has a drive (34) for moving a lifting body (39) of the pallet holder (30) between: - an upper position in which the lifting body (39) of the pallet holder (30) is located below a lifting body (29) of the lifter (27) of the transport device (20), so that the latter lifting body (29) is located at least partially above the pressure medium support surface (26) of the transport device (20), and - a lower position in which the lifting body (39) of the pallet holder (30) is located below the lifting body (29) of the lifter (27) of the transport device (20), so that the latter lifting body (29) is located below or at the level of the pressure medium support surface (26) of the transport device (20). [11] Stacker (40) according to claim 10, wherein the pallet holder (30) has receiving means for receiving the at least one support foot (24) of the transport device (20), so that the recess (25) of the transport device (20) in the received state lies at least partially above the lifting body (39) of the pallet holder (30). [12] Stacker (40) according to claim 10 or 11, wherein the lifting body (39) of the pallet holder (30) is movable into the upper position to contact the lifting body (29) of the transport device (20), thereby positioning the lifting body (29) of the transport device (20) in the second position. [13] Stacker (40) according to one of claims 9 to 10, wherein the lifter (27) has a lifting body (29) which is held on the transport device (20) by a joint (21). [14] A printer comprising a stacker (40) according to any one of claims 9 to 13.

Images