Sheet feeding device equipped with a sheet forming means

Abstract

a sheet feeding device (1) comprising: an elevator (2) for a stack of sheets; and an air supply system (3) configured to supply and direct one or more air streams toward an upper region (4) of the sheet feeding device (1) to float upper sheets of the stack of sheets, the elevator (2) comprising a vertically movable support (5) for supporting the stack of sheets from below, the sheet feeding device (1) comprising first and second side support members (6) and (7) configured to laterally support opposite sides of the stack of sheets, the sheet feeding device (1) further comprising: a vacuum belt feeder (8) disposed above the elevator (2) and configured to capture and feed an uppermost sheet of the floated sheets away from the floated sheets, and at least one respective cam (9) is provided at an upper portion of each side support member (6, 7) with a respective guide surface extending obliquely upward and inward from the respective side support member (6, 7).

Description

Technical Field

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

Background Art

[0002] A sheet feeding device is generally incorporated in a printer or a copier, and a large number of sheets are manually loaded to automatically feed the sheets one by one for subsequent operations on the sheets such as printing or sorting.

[0003] An example of a prior art sheet feeding device by the present applicant is described in an international patent application published as WO2015 / 147732A1. The sheet feeding device includes a storage surface for a stack of sheets. The storage surface is adapted to move vertically between a first lower end position and a second upper end position as sheets are consumed from the top of the stack of sheets. The sheet feeding device further includes a feed roller for feeding the sheets from their positions above the storage surface and applying a horizontal displacement to the top sheet of the stack of sheets. Also, the feed roller is movably attached so that it can pivot to account for variations in the angle of the top sheet of the stack of sheets. The feed roller is driven by a motor.

[0004] The problem of the sheet feeding device is to handle sheets of various materials and qualities while minimizing or eliminating problems associated with double feeding, sheet jams, or manual settings and adjustments for operating the sheet feeding device with different sheet sizes and qualities.

Summary of the Invention

[0005] Accordingly, the present disclosure aims to alleviate the above-mentioned drawbacks, either alone or in combination, by providing a sheet feeding device as defined in the appended independent claims. The sheet feeding device includes a lifter for a stack of sheets, and an air supply system configured to supply and direct one or more air flows toward an upper region of the sheet feeding device to lift a plurality of upper sheets of the stack of sheets. The lifter includes a vertically movable support for supporting the stack of sheets from below. The sheet feeding device also includes first and second side support members configured to support respective opposing side surfaces of the stack of sheets from the side. Further, the sheet feeding device includes a vacuum belt feeder provided above the lifter and configured to grab and feed out the topmost sheet among the lifted sheets. Additionally, at least one respective cam is provided at an upper portion of each side support member, each respective cam having a respective guide surface extending obliquely upward and inward from the respective side support member. Each "cam" may alternatively be referred to as "guiding means".

[0006] A sheet feeding device is typically used in front of a printer or copier to supply individual sheets one by one to the printer / copier. To enable this, a stack of sheets is loaded onto a lift in a state where side support members define a space corresponding to the width of the stack of sheets such that the side support members support the respective opposing side surfaces of the stack of sheets from the sides. Next, the lift moves the top sheet of the stack of sheets upward or downward until it reaches 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 causing a plurality of upper sheets of the stack of sheets to float such that they are separated and suspended in the air flow. When lifted by the air flow, the top sheet is fed upward from the stack of sheets, and as they move upward, they hit a cam that defines a space narrower than the width between the side support members in cooperation. When hitting the cam, a reaction force is applied to the edge of the sheet, whereby the sheet takes a curved shape. Accordingly, each sheet follows the cam, thereby operating like a cam follower. The curved shape is advantageous as it makes the sheet rigid in one direction, which results in all the lifted sheets having a similar shape with less variation due to the air flow and turbulence. Furthermore, a more rigid sheet can be handled more predictably by a vacuum belt feeder, thereby avoiding sheet jams. The vacuum belt feeder provides a vacuum through its perforated belt such that the top one of the lifted sheets is pressed against the belt, whereby the belt can be operated to move the sheet and feed it out for subsequent processing.

[0007] Each cam can 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) in contact with the cam. Thereby, the friction between the cam and the sheet is limited, and as a result, the sheet feeding device can be used with sheets of various rigidities with a reduced risk of malfunctioning sheet separation or stuck sheets.

[0008] Each cam may include an elongated elastic stem, whereby the cam is attached to the respective side support member. The elongated elastic stem enables the use of a rigid cam portion while allowing for continuous or improved elasticity of the cam as a whole. The stem curves when a force is applied to the cam from the (one or more) sheet edges, thereby restricting the reaction force. The longer the stem, the less the amount of rotation of the cam during movement of the cam. The force spring constant provided by the elastic stem is substantially uniform throughout its range of movement during use, since the stem only needs to deform slightly to allow the required freedom of movement of the cam.

[0009] Each stem may extend vertically downward under each respective cam outside 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 extending the stem under the cam, the upper portion of the cam will open outward when moving outward, which means that the approach angle between the cam and the sheet will not increase but decrease when pressing the cam outward. Further, by extending the stem outside the support member, the stem will not touch the sheet, thereby reducing the risk of sheet jamming.

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

[0011] The cam may be provided with a stepped guide surface. By providing a step, a plurality of cam portions with increased resistance for the sheet to slide along it during lifting are provided, thereby promoting the controlled separation of the lifted sheet.

[0012] The first and second side support members may be movably attached to the sheet feeding device so that their mutual intermediate distance is adjustable to support bundles of different widths. This enables the use of the sheet feeding device with different types of sheets.

[0013] The vertically movable support has a raised central portion extending along the length of the sheet feeding device in the feeding direction of the sheet feeding device. The raised central portion provides a support that rises in the central portion of the bundle of sheets so as to curve all the stacked sheets. This facilitates the lifting and separation of the sheets.

[0014] The vacuum belt feeder comprises opposing outer lower belt portions separated by an intermediate lower belt portion provided higher than the outer portions. The higher position of the intermediate lower belt portion provides extra space for the top lifted sheet so that the central portion of the top lifted sheet curved by the cam can move further upward, where the outer portion of the top lifted sheet is brought closer to the outer belt portion. Thereby, all the belt portions can cooperate to adsorb the top sheet.

Brief Description of the Drawings

[0015] [Figure 1] Figure 1 shows a perspective view of a sheet feeding device according to the first embodiment. [Diagram 2] Figure 2 shows a detailed view A where two right cams are visible. [Figure 3] Figure 3 shows the design of an embodiment of the cam used in the sheet feeding device. [Figure 4] Figure 4 shows the design of an embodiment of the cam used in the sheet feeding device. [Figure 5] Figure 5 shows a top view of the sheet feeding device of FIGS. 1 to 2. [Figure 6] Figure 6 shows a front view of the sheet feeding device shown also in FIGS. 1, 2, and 5 in section B-B shown in FIG. 5. [Figure 7] Figure 7 shows an exploded view of the vacuum belt feeder of the sheet feeding device shown also in FIGS. 1, 2, 5, and 6. [Figure 8] Figure 8 shows a detailed view C as shown in FIG. 1. Specifically, a nozzle of the air supply system is seen together with an optical sensor for measuring the state of the cam and the lifted sheet.

[0016] [Table 1] [Embodiments for Carrying Out the Invention]

[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 FIGS. 1 and 6, the sheet feeding device 1 includes a lifter 2 for a bundle of sheets (not shown), and an air supply system 3 configured to supply and guide one or more air flows toward an upper region 4 of the sheet feeding device 1 in order to lift a plurality of upper sheets of the bundle of sheets. The lifter 2 includes a vertically movable support 5 for supporting the bundle 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 support opposite side surfaces of the bundle of sheets from the side. Further, the sheet feeding device 1 includes a vacuum belt feeder 8 provided above the lifter 2 and configured to catch and feed out the uppermost sheet among the lifted sheets.

[0018] Furthermore, on the upper part of each side support member, two respective cams 9 extending obliquely upward and inward D1, D2 from the respective side support members 6, 7 are provided. This means that the guide surfaces of the cams extend upward and inward D1, D2 from the respective side support members 6, 7. As shown in FIGS. 1 and 2, each side support member 6, 7 includes two spaced cams 9, one in front of the side support member 6, 7 and one behind. The front of each side support member 6, 7 is the one closest to the vacuum belt feeder.

[0019] It should be understood that the cover plate is not shown in FIGS. 1 and 2 for illustrative purposes. Usually, one cover plate is attached over the opening of the space of each side support member, and the cams are attached within this space. This plate ensures that overpressure can be achieved inside each space so that air can be pushed out from the four arrow-shaped air outlets of each side support member 6, 7. In the lower central part of FIG. 1, one fan is shown for increasing the air pressure within the space of the second side support member 7.

[0020] In this embodiment, all the cams 9 are identical, and FIGS. 3 and 4 show the design of such a cam 9. Each cam 9 is elastic and can thus be pressed outward by the pressure from the sheet. Elasticity can be achieved in many ways. In this embodiment, each cam 9 comprises an elongated elastic stem 10, whereby the cams 9 are attached to the respective side support members 6, 7. The stem 10 is made of spring steel and extends vertically under the head 17 of the cam 9, and this head 17 provides a guide surface 12 along which the sheet moves. The cam head 17 is made of injection-molded 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 screws, but any other suitable means such as riveting or press-fitting can be used as an alternative. Each cam 9 is arranged such that its head 17 extends through the respective openings or recesses 11 in the upper part of the side support members 6, 7. The holes or recesses 11 are formed in the wall plates of the side support members, and these wall plates provide a support surface for the stack of sheets. The cams 9 are attached to the "outside" of the respective side support members 6, 7, where the outside faces away from the stack of sheets, and here, the lower part of the stem 10 is attached to the side support members 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 and thus provide a "vertically stepped" guide surface 12. By providing the steps, a plurality of cam portions with increased resistance for the sheet to slide along during lifting are provided, thereby facilitating the controlled separation of the lifted sheet. In other embodiments, the guide surface 12 of the cam can alternatively be linear / plane or arcuate. Further, instead of geometric steps, in other embodiments, these steps can alternatively be provided in the form of portions of the guide surface provided with means for providing locally increased friction, such as a TPU or rubber layer, a patterned surface structure, or the like.

[0021] The vertical positioning and extension of the cam 9 are such that the cam 9 guides the sheet to a position where the vacuum belt feeder 8 can capture the sheet. Thus, the cam 9 ensures that the top sheet is curved when the vacuum belt feeder 8 captures the top sheet. Curved sheets are more rigid than flat sheets and are therefore more stable and easier to handle.

[0022] In this embodiment, each cam 9 is provided with respective stop means 18 in the form of protrusions provided on the stem 10. The stop means 18 is configured to limit the movement of the cam 9 by engaging with the side support members 6, 7, thereby preventing its unwanted movement by restricting the movement of the cam 9 within a predetermined movement range. In this embodiment, the protrusions of the stop means 18 are provided outside the side support members 6, 7 and extend wider than the openings or recesses 11 of the side support members 6, 7 so that the stop means 18 cannot pass through the openings or recesses 11, thereby defining the innermost position of the cam 9. Thus, the innermost position is the position where the distance between the opposing cams 9 is minimized. From this inner position, the (one or more) sheets press the cams 9 outward to increase the distance between the opposing cams 9. The outward movement of each cam 9 is performed against the reaction force of the elastic deformation of the respective stem 10.

[0023] Generally, the cam 9 can be replaced in other embodiments with cams 9 having other designs, such as, alternatively, being integrated as part of a stem 10 modified to provide a guide surface 12 along which the sheet slides, having a head 17, etc. Further, the number of cams 9 provided on each side support member 6, 7 may be more or less than two as long as at least one cam 9 is provided on each side support member 6, 7.

[0024] The first side support member 6 and the second side support member 7 are movably attached to the sheet feeding device 1 so that their mutual intermediate distance can be adjusted to support bundles of different widths. The first side support member 6 and the second side support member 7 can be biased inwardly, thereby pressing the bundle of sheets, for example, by elastic deformation of the stem 10.

[0025] As shown in FIGS. 1 and 6, the vertically movable support 5 includes a raised central portion 13 that extends along the length of the sheet feeding device 1 in the feeding direction 14 of the uppermost sheet. The raised central portion 13 is defined, as shown, by two ribs / beams and respective left and right support plates that are slightly inclined so as to raise the inner portions of the respective plates. In other embodiments, the raised central portion 13 of the vertically movable support 5 can be achieved in any suitable manner, such as by providing one or more central elongated protrusions that extend above the height of the remaining portion of the vertically movable support 5.

[0026] As shown in FIG. 7 , the vacuum belt feeder 8 includes 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 and three on the right. The two innermost belts are positioned with their lower belt portions 1 mm above the lower belt portions of the outer belts. The other two intermediate belts are positioned 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 as follows: [0 mm, 0.5 mm, 1 mm, 1 mm, 0.5 mm, 0 mm]. The upper portion of each belt can extend to 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, i.e., 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 alleviate 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 the arcuate vertically movable support 5, such as with a planar support surface for the vertically movable support 5. Also, the cam 9 may be used without the 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 device 1 is also typically provided with a control device (not shown) configured to control the vertical position of the vertically movable support 5, control the air supply system 3, and control the vacuum belt feeder 8. The control device operates the vertically movable support 5 as necessary in consideration of the sheet sent out from the sheet feeding device 1. Further, the control device operates the air supply system 3 so as to provide proper floating with good separation of the floating sheet. Also, the control device operates the vacuum belt feeder 8 to catch the topmost floating sheet and move it away so as to be sent out from the sheet feeding device 1. Details regarding the control logic of the operations 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 thus omitted from this disclosure. The inventions described in the original claims of this application are set forth below. [1] A sheet feeding device (1), an elevator (2) for the stack of sheets; an air supply system (3) configured to supply and direct one or more air streams toward an upper region (4) of the sheet feeding device (1) to lift upper sheets of the stack of sheets; The elevator (2) includes 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 support opposite sides of the stack of sheets from the sides; the sheet feeding device (1) further includes a vacuum belt feeder (8) provided above the elevator (2) and configured to catch and feed the uppermost 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 each of the side support members (6, 7) is provided on the upper portion of each of the side support members (6, 7). [2] The sheet feeding device (1) according to [1], wherein each cam (9) is elastic. [3] The sheet feeding device (1) described in [1], wherein each cam (9) has an elongated elastic stem (10) by which the cam (9) is attached to the respective side support member (6, 7). [4] A sheet feeding device (1) as described in [3], wherein the stem (10) of each cam (9) extends vertically below the cam (9) on the outside 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] The sheet feeding device (1) described in [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 to the inside of each of the side support members (6, 7). [6] The sheet feeding device (1) according to any one of [1] to [5], wherein the cam (9) is provided with a stepped guide surface (12). [7] The first side support member (6) and the second side support member (7) are movably attached to the sheet feeding device (1) such that the intermediate distance therebetween is adjustable in order to support sheets of different widths, the sheet feeding device (1) according to any one of [1] to [6]. [8] The vertically movable support (5) comprises a raised central portion (13) extending along the length of the sheet feeding device (1) in the feeding direction (14) of the sheet feeding device (1), the sheet feeding device (1) according to any one of [1] to [7]. [9] The vacuum belt feeder (8) comprises the opposing outer lower belt portions (15) separated by an intermediate lower belt portion (16) provided higher than the outer lower belt portions (15), the sheet feeding device (1) according to any one of [1] to [8].

Claims

1. A sheet feeding device (1), comprising: a lifter (2) for a stack of sheets; 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 lift a plurality of upper sheets of the stack of sheets. The lifter (2) includes 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 support respective opposing side surfaces of the stack of sheets from the side. Each of the first side support member (6) and the second side support member (7) includes an air outlet of the air supply system (3). The sheet feeding device (1) further includes a vacuum belt feeder (8) provided above the lifter (2) and configured to capture and feed out the topmost sheet of the lifted sheets. The sheet feeding device (1), wherein at least one respective cam (9) having a respective guide surface extending obliquely upward inward (D1, D2) from each of the side support members (6, 7) is provided at an upper portion of each side support member (6, 7).

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

3. The sheet feeding device (1) according to claim 1, wherein each cam (9) includes an elongated elastic stem (10), whereby the cam (9) is attached to each of the side support members (6, 7).

4. The sheet feeding device (1) according to claim 3, wherein the stem (10) of each cam (9) extends vertically downward below the cam (9) outside each of the side support members (6, 7) facing away from the stack of sheets, and a lower portion of the stem (10) is attached to each of the side support members (6, 7).

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 cam (9) extends from outside each of the side support members (6, 7) to the inside thereof through the openings or recesses (11).

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 first side support member (6) and the second side support member (7) are movably attached to the sheet feeding device (1) such that the intermediate distance therebetween is adjustable in order to support sheets of different widths, the sheet feeding device (1) according to any one of claims 1 to 6.

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

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

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