Sheet feeder having sheet shaping means

Abstract

To minimize or eliminate the problem that manual setting and adjustment for operating a sheet feeder is associated with duplicate feed, sheet jam or different sheet size and quality.SOLUTION: A sheet feeder (1) comprises an air supply system (3) that is configured to supply and induce airstream to an upper region thereof, a support (5) that is allowed to move in a vertical direction for supporting a bundle of sheets from below, first and second side-support members (6), (7) that are configured to support respective opposite sides of the bundle of sheets laterally, and a vacuum belt feeder (8) that is configured to catch and feed an uppermost one of floated sheets. The side-support members (6, 7) each have, on their upper parts, at least one cam (9) having a guide face extending obliquely upper inward from each of the side-support members (6, 7).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a sheet feeding apparatus for the printing industry, for example a sheet feeding apparatus for a printer, copier, or sorter. [Background technology]

[0002] Sheet feeders are commonly incorporated into printers or copiers into which a number of sheets are manually loaded for automatic feeding of the sheets, one at a time, for a subsequent operation on the sheets, such as printing or sorting.

[0003] An example of a prior art sheet feeder by the applicant is described in the international patent application published as WO2015 / 147732A1. The sheet feeder comprises a storage surface for a stack of paper. The storage surface is adapted to move vertically between a first bottom position and a second top position as sheets are consumed from the top of the stack of sheets. The sheet feeder further comprises feed rollers for feeding the paper from their positions above the storage surface and for imparting a horizontal displacement to the topmost paper sheet. And the feed roller is movably mounted such that it can pivot to account for variations in the angle of the topmost sheet of the stack of paper. The feed roller is driven by a motor.

[0004] A challenge for sheet feeders is to handle sheets of various materials and qualities while minimizing or eliminating problems associated with double feeding, sheet jams, or manual setup and adjustments to operate the sheet feeder with different sheet sizes and qualities. Summary of the Invention

[0005] The present disclosure therefore aims to alleviate the above mentioned drawbacks, singly or in combination, by providing a sheet feeding apparatus as defined in the attached independent claims. The sheet feeding apparatus comprises an elevator for a stack of sheets and an air supply system configured to supply and direct one or more air flows towards an upper region of the sheet feeding apparatus to float a plurality of upper sheets of the stack of sheets, the elevator comprising a vertically movable support for supporting the stack of sheets from below. The sheet feeding apparatus also comprises first and second side support members configured to laterally support respective opposite sides of the stack of sheets. The sheet feeding apparatus also comprises a vacuum belt feeder arranged above the elevator and configured to grab and feed the topmost one of the floated sheets. Furthermore, an upper portion of each side support member is provided with at least one respective cam with a respective guide surface extending obliquely upwards and inwards from the respective side support member. Each "cam" may alternatively be referred to as a "guiding means".

[0006] A sheet feeder is typically used in front of a printer or copier to feed individual sheets one by one into the printer / copier. To enable this, the stack of sheets is loaded onto an elevator with the side support members arranged to laterally support each opposing side of the stack of sheets, defining a space corresponding to the width of the stack of sheets. The elevator then moves the top sheet of the stack of sheets upwards or downwards until it is at a suitable height in the upper region. An air supply system is used to supply and direct an air flow towards the upper region, thereby levitating the top sheets of the stack of sheets so that they are separated and suspended in the air flow. When levitated by the air flow, the top sheets are fed upwards from the stack of sheets, and on their way upwards they strike cams that together define a space narrower than the width between the side support members. Upon striking the cams, a reaction force is applied to the edges of the sheets, which causes them to assume a curved shape. Thus, each sheet follows the cam, thereby acting like a cam follower. The curved shape is advantageous because it makes the sheet stiff in one direction, which results in all floated sheets having a similar shape with fewer areas of variation due to airflow and turbulence. Furthermore, stiffer sheets can be handled more predictably by the vacuum belt feeder, thereby avoiding sheet jams. The vacuum belt feeder provides a vacuum through its perforated belt that causes the top of the floated sheets to be pressed against the belt, which can then be operated to move the sheet and deliver it for further processing.

[0007] Each cam may be elastic. The elasticity of the cam allows the surface of the cam to deform and / or move when a reaction force is applied from the sheet(s) contacting the cam. Thereby, friction between the cam and the sheet is limited, so that the sheet feeder can be used with sheets of various stiffnesses with reduced risk of poorly functioning sheet separation or stuck sheets.

[0008] Each cam may include an elongated resilient stem by which it is attached to a respective side support member. The elongated resilient stem allows for the use of rigid cam portions while allowing for a consistent or improved resilience of the cam as a whole. The stem bends when a force is applied to the cam from the sheet edge(s), thereby limiting the reaction force. The longer the stem, the less the amount of rotation the cam will experience as it moves. The force spring constant provided by the resilient stem is substantially uniform throughout its range of movement during use, because the stem only needs to deform slightly to allow the cam the required freedom of movement.

[0009] Each stem may extend vertically below a respective cam, on the outside of the respective side support member facing away from the stack of sheets, where the lower portion of the stem is attached to the side support member. By having the stems extend below the cams, the upper portion of the cam will flare outward on outward movement, which means that the angle of attack between the cam and the sheet will decrease, rather than increase, as the cam is pressed outward. Furthermore, by having the stems extend outside the support members, the stems will not touch the sheet, thereby reducing the risk of sheet jamming.

[0010] The side support members may be provided with openings or recesses, where each respective cam extends through each respective opening or recess from the outside to the inside of the respective side support member. By having the cam extend through the opening or recess, the overlap between the inner surface of the side support and the cam is smooth without protrusions, which reduces the risk of sheet jams and damage to the sheet edges.

[0011] The cam may be provided with a stepped guide surface, which provides multiple cam portions with increased resistance for the sheet to slide along as it floats, thereby facilitating controlled separation of the floated sheet.

[0012] The first and second side support members may be movably mounted to the sheet feeder such that their intermediate distance from each other is adjustable to support stacks of different widths, allowing the sheet feeder to be used with different types of sheets.

[0013] The vertically movable support includes a raised central portion that extends along the length of the sheet feeder in a feed direction of the sheet feeder, the raised central portion providing a raised support in the central portion of the stack of sheets to cause all stacked sheets to curve, thereby facilitating sheet lift-off and separation.

[0014] The vacuum belt feeder includes opposing outer lower belt sections separated by an intermediate lower belt section that is higher than the outer sections. The higher position of the intermediate lower belt section provides extra space for the topmost floated sheet to allow the central portion of the topmost floated sheet, curved by the cam, to move further upward, where the outer portions of the topmost floated sheet are brought closer to the outer belt sections, so that all belt sections can cooperate to attract the topmost sheet. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a sheet feeding device according to a first embodiment. [Diagram 2] FIG. 2 shows detail A, where the two right cams are visible. [Diagram 3] FIG. 3 shows a design of an embodiment of a cam used in a sheet feeding device. [Figure 4] FIG. 4 shows a design of an embodiment of a cam used in a sheet feeding device. [Diagram 5] FIG. 5 is a top view of the sheet feeding device of FIGS. [Figure 6] FIG. 6 shows a front view of the sheet feeding apparatus also shown in FIGS. 1, 2 and 5, taken along the cross section BB shown in FIG. [Figure 7] FIG. 7 shows an exploded view of the vacuum belt feeder of the sheet feeding apparatus also shown in FIGS. [Figure 8] Figure 8 shows detail C as shown in Figure 1. In particular, the nozzles of the air supply system can be seen, together with the cams and the optical sensors for measuring the state of the floated sheet.

[0016] [Table 1] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A first embodiment of the sheet feeding device 1 of the present invention will be described below with reference to the accompanying drawings. As shown in Fig. 1 and Fig. 6, the sheet feeding device 1 includes an elevator 2 for a stack of sheets (not shown) and an air supply system 3 configured to supply and direct one or more air flows toward an upper region 4 of the sheet feeding device 1 to float a plurality of upper sheets of the stack of sheets, and the elevator 2 includes a vertically movable support 5 for supporting the stack of sheets from below. The sheet feeding device 1 also includes a first side support member 6 and a second side support member 7 configured to laterally support opposite sides of each of the stack of sheets. The sheet feeding device 1 also includes a vacuum belt feeder 8 disposed above the elevator 2 and configured to capture and feed the topmost sheet of the floated sheets.

[0018] Furthermore, the top of each side support member is provided with two respective cams 9 extending diagonally upwardly inwardly D1, D2 from the respective side support member 6, 7. This means that the guide surfaces of the cams extend upwardly inwardly D1, D2 from the respective side support member 6, 7. As shown in Figures 1 and 2, each side support member 6, 7 is provided with two spaced apart cams 9, one at the front and one at the rear of the side support member 6, 7. The front of each side support member 6, 7 is closest to the vacuum belt feeder.

[0019] It should be understood that cover plates are not shown in Figures 1 and 2 for illustrative purposes. Usually, one cover plate is mounted over the opening of the space of each side support member, and a cam is mounted in this space. This plate ensures that an overpressure can be achieved inside each space so that air can be pushed out of the four arrow-shaped air outlets of each side support member 6, 7. In the lower central part of Figure 1, one fan is shown to increase the air pressure in the space of the second side support member 7.

[0020] In this embodiment, all the cams 9 are identical, and Figures 3 and 4 show the design of such a cam 9. Each cam 9 is elastic and can therefore be pushed outwards by pressure from the seat. Elasticity can be achieved in a number of ways. In this embodiment, each cam 9 comprises an elongated elastic stem 10 by which it is attached to a respective side support member 6, 7. The stem 10 is made of spring steel and extends vertically below a head 17 of the cam 9, which provides a guide surface 12 for the seat to move along. The cam head 17 is made of injection moulded plastic, but in other embodiments it can be made of any other material and manufactured using any other suitable method. The head 17 is attached to the stem 10 by a screw, but any other suitable means such as riveting or press fitting can be used instead. Each cam 9 is arranged so that its head 17 extends through a respective opening or recess 11 in the top of the side support member 6, 7. A hole or recess 11 is formed in the wall plate of the side support member, which provides a support surface for the stack of sheets. The cam 9 is attached to the "outside" of each side support member 6, 7, said outside facing away from the stack of sheets, where the lower part of the stem 10 is attached to the side support member 6, 7. In this embodiment, as shown in FIG. 4, the guide surface 12 of the cam 9 is stepped. The steps extend substantially horizontally, thus providing a "vertically stepped" guide surface 12. The steps provide multiple cam portions with increased resistance for the sheets to slide along during surfacing, thereby facilitating controlled separation of the surfacing sheets. In other embodiments, the guide surface 12 of the cam can alternatively be straight / planar or arcuate. Furthermore, instead of geometrical steps, in other embodiments, these steps may alternatively be provided in the form of parts of the guiding surface provided with means for providing locally increased friction in said parts of the guiding surface, such as a TPU or rubber layer, a patterned surface structure or the like.

[0021] The vertical positioning and extension of the cam 9 is such that the cam 9 guides the sheet to a position where it can be captured by the vacuum belt feeder 8. The cam 9 thus ensures that the top sheet is curved when the vacuum belt feeder 8 captures it. Curved sheets are stiffer than flat sheets and therefore easier to handle as they are more stable.

[0022] In this embodiment, each cam 9 is provided with a respective stop means 18 in the form of a protrusion provided on the stem 10. The stop means 18 are arranged to limit the movement of the cam 9 by engaging with the side support members 6, 7, thereby preventing undesired movement of the cam 9 by restricting it to a predefined range of movement. In this embodiment, the protrusion of the stop means 18 is provided on the outside of the side support members 6, 7 and extends wider than the opening or recess 11 of the side support members 6, 7 so that the stop means 18 cannot pass through the opening or recess 11, thereby defining the innermost position of the cam 9. The innermost position is therefore the position where the distance between the opposing cams 9 is minimal. From this inner position, the seat(s) press the cam 9 outwards, increasing the distance between the opposing cams 9. The outward movement of each cam 9 is against the counter force of the elastic deformation of the respective stem 10.

[0023] In general, the cams 9 may be replaced in other embodiments with cams 9 having other designs, such as alternatively having a head 17 integrated as part of the stem 10 modified to provide a guide surface 12 for the seat to slide along. Furthermore, the number of cams 9 provided on each side support member 6, 7 may be more or less than two, so long as at least one cam 9 is provided on each side support member 6, 7.

[0024] The first and second side support members 6, 7 are movably mounted on the sheet feeding apparatus 1 such that their intermediate distance from each other is adjustable to support stacks of different widths. The first and second side support members 6, 7 can be biased inwardly, thereby pressing against the stack of sheets, for example, by elastic deformation of the stems 10.

[0025] 1 and 6, the vertically movable support 5 includes a raised central portion 13 that extends along the length of the sheet feeder 1 in the top sheet feed direction 14. The raised central portion 13 is defined by two ribs / beams and each left and right support plate that are slightly angled to raise the inner portion of each plate, as shown. In other embodiments, the raised central portion 13 of the vertically movable support 5 may be achieved in any suitable manner, such as by providing one or more central elongated protrusions that extend above the height of the remainder of the vertically movable support 5.

[0026] As shown in FIG. 7, the vacuum belt feeder 8 comprises opposing outer lower belt portions 15 separated by an intermediate lower belt portion 16 that is higher than the outer portions. In this particular embodiment, there are six belts - three on the left side and three on the right side. The two innermost belts are arranged with their lower belt portions 1 mm above the lower belt portions of the outer belts. The other two intermediate belts are arranged with their lower belt portions 0.5 mm higher than the lower belt portions of the outer belts. From one side to the other, the vertical offset of the lower portions of each of the six belts, measured from the lowest, is: [0 mm, 0.5 mm, 1 mm, 1 mm, 0.5 mm, 0 mm]. The upper portion of each belt may extend at any height defined by the roller arrangement around which the belt is mounted. The outer lower belt portions 15 and the intermediate lower belt portions 16 together provide an arcuate belt assembly, in other words a belt assembly that provides an arcuate feeding surface. Instead of six belts, any number of belts may be used as long as they are configured together to provide an arcuate feeding surface.

[0027] In this embodiment, three inventive concepts, 1. a cam for curving a sheet, 2. an arcuate vertically movable support, and 3. an arcuate vacuum belt feeder, are used together to mitigate the shortcomings of the prior art and promote trouble-free operation of the feeding apparatus. However, in other embodiments, the cam 9 may be used without the need for an arcuate vertically movable support 5, such as with a planar support surface of the vertically movable support 5. Also, the cam 9 may be used without an arcuate vacuum belt feeder 8, such as with a planar vacuum belt feeder. However, when the three concepts are used together, the positive impact on trouble-free operation is increased.

[0028] The sheet feeding apparatus 1 is also typically provided with a controller (not shown) configured to control the vertical position of the vertically movable support 5, to control the air supply system 3, and to control the vacuum belt feeder 8. The controller operates the vertically movable support 5 as required, taking into account the sheets fed from the sheet feeding apparatus 1. The controller also operates the air supply system 3 to provide a proper lift with good separation of the lifted sheets. The controller also operates the vacuum belt feeder 8 to capture the topmost lifted sheet and move it away so that it can be fed from the sheet feeding apparatus 1. Details regarding the control logic for the operation of the air supply system 3, the vacuum belt feeder 8, and the vertically movable support 5 of the elevator 2 are beyond the scope of the present invention and are therefore omitted from this disclosure.

Claims

1. A sheet feeding device (1), an elevator (2) for stacks of sheets; an air supply system (3) configured to supply and direct one or more air streams towards an upper region (4) of the sheet feeding device (1) to lift a plurality of upper sheets of the stack of sheets, The elevator (2) comprises a vertically movable support (5) for supporting the stack of sheets from below, The sheet feeding device (1) includes a first side support member (6) and a second side support member (7) configured to laterally support opposing sides of the stack of sheets, the sheet feeding device (1) further includes a vacuum belt feeder (8) disposed above the elevator (2) and configured to catch and feed the topmost sheet of the floated sheets; A sheet feeding device (1), wherein at least one respective cam (9) having a respective guide surface extending obliquely upward and inward (D1, D2) from the respective side support member (6, 7) is provided on an upper portion of each side support member (6, 7).

2. 2. A sheet feeding device (1) according to claim 1, wherein each cam (9) is resilient.

3. 2. A sheet feeding device (1) according to claim 1, wherein each cam (9) comprises an elongated resilient stem (10) by means of which said cam (9) is mounted to the respective side support member (6, 7).

4. 4. A sheet feeding device (1) as described in claim 3, wherein the stem (10) of each cam (9) extends vertically below the cam (9) on the outer side of the respective side support member (6, 7) facing away from the stack of sheets, and the lower part of the stem (10) is attached to the respective side support member (6, 7).

5. 5. The sheet feeding device (1) according to claim 3 or 4, wherein the side support members (6, 7) are provided with openings or recesses (11), and the cams (9) extend through the openings or recesses (11) from the outside of each of the side support members (6, 7) to its inside.

6. The sheet feeding device (1) according to any one of claims 1 to 5, wherein the cam (9) is provided with a stepped guide surface (12).

7. The sheet feeding device (1) of any one of claims 1 to 6, wherein the first side support member (6) and the second side support member (7) are movably mounted on the sheet feeding device (1) such that their intermediate distance from each other is adjustable to support sheets of different widths.

8. The sheet feeding device (1) of any one of claims 1 to 7, wherein the vertically movable support (5) has a raised central portion (13) extending along a length of the sheet feeding device (1) in a feeding direction (14) of the sheet feeding device (1).

9. The sheet feeding device (1) of any one of claims 1 to 8, wherein the vacuum belt feeder (8) comprises opposing outer lower belt portions (15) separated by an intermediate lower belt portion (16) that is positioned higher than the outer lower belt portions (15).

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