SHEET STORAGE DEVICE

Abstract

A sheet storage device includes a sheet storage movable in an up-and-down direction, to stack and store sheets conveyed in a conveyance direction. The sheet storage moves down according to weight of the sheets stacked in the sheet storage.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119 (a) to Japanese Patent Application No. 2023-076154, filed on May 2, 2023, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

The present disclosure relates to a sheet storage device.

Related Art

Sheet storage devices, such as those used to store sheets (e.g., envelopes ejected from the ejection section of an image forming apparatus), have been used.

In such devices, as sheets pile up in the storage section, the stacking position for the next sheet rises. This causes the drop height from the ejection section to the storage section to change, leading to a variation in the storage position of the sheets within the storage section. This results in the sheets stored in the storage section being misaligned and stored in disarray.

SUMMARY

An embodiment of the present embodiment provides a sheet storage device that includes a sheet storage movable in an up-and-down direction, to stack and store sheets conveyed in a conveyance direction. The sheet storage moves down according to weight of the sheets stacked in the sheet storage.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of an envelope ejection tray according to an embodiment of the present disclosure;

FIG. 2 is a side view of a support frame;

FIG. 3 is a perspective view of a lifting section;

FIG. 4 is a perspective view of a guide roll;

FIG. 5 is a perspective view of a guide;

FIG. 6 is a perspective view of a support frame and springs;

FIG. 7 is a side view of an envelope ejection tray;

FIG. 8 is a perspective view of an ejection section of an image forming apparatus;

FIG. 9 is a sectional view of the ejection section of FIG. 8;

FIG. 10A is a plan view of an envelop;

FIG. 10B is a bottom view of the envelop in FIG. 10A;

FIG. 11 is a side view of the envelope in FIGS. 10A and 10B;

FIG. 12 is a side view of a stack of envelopes;

FIGS. 13A to 13C are plan sectional views of a process in which an envelope falls into a storage box and is arranged at a predetermined position in the storage box;

FIG. 14 is a side sectional view of envelopes stacked in a storage box;

FIG. 15 is a side sectional view of the storage box of FIG. 14 with a tilting jig incorporated therein;

FIG. 16A is a plan view of an envelope in a form different from that of FIG. 10A;

FIG. 16B is a bottom view of the envelope in FIG. 16A;

FIG. 17 is a front sectional view of envelopes of FIGS. 16A and 16B stacked in a storage box;

FIG. 18 is a side sectional view of the storage box of FIG. 17 with a tilting jig incorporated therein;

FIG. 19 is a perspective view of a tilting jig;

FIG. 20 is a plan sectional view of a spacer placed in a storage box;

FIG. 21 is a perspective view of a storage box; and

FIG. 22 is a side sectional view of a storage box in which a bottom plate and a buffer material are placed.

The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

DETAILED DESCRIPTION

In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.

Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

A typical storage device includes a height-adjustable stacking tray on which sheets are stacked and a paper surface detection sensor for detecting a paper surface. In this device, the sensor detects the amount of sheets stacked on the stacking tray. Based on the detected amount of sheets, the device then lowers the stacking tray. This allows for the adjustment of the sheet stacking position of the stacking tray according to the amount of sheets loaded.

This configuration leads to the high costs of the sheet storage device by incorporating the detection sensor.

According to one aspect of the present disclosure, a simple configuration allows for the sheets to be accurately stacked and stored.

Referring to the drawings, embodiments of the present disclosure are described below. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are simplified or omitted as appropriate. As an embodiment of a sheet storage device, an envelope ejection tray for stacking envelopes as sheets ejected from an image forming apparatus is described below.

As illustrated in FIG. 1, an envelope ejection tray 1 includes a support frame 11, a lifting section 12 as a holder, and a storage box 13 as a sheet storage. The directions X, Y, and Z in FIG. 1 are orthogonal to each other. The direction X refers to the width direction of the envelope ejection tray 1 and also to the width direction of an envelope as it enters the storage box 13. The direction Y is both the conveyance direction of the envelope and its opposite direction. The direction Z is also the gravity direction and its opposite direction. However, these directions do not have to be strictly orthogonal to each other. The width direction of the envelope is a direction orthogonal to the conveyance direction and the thickness direction of the envelope.

The support frame 11 is provided with a connecting part 14 that is connected to the image forming apparatus. The support frame 11 includes a guide 15 for lifting the lifting section 12. By connecting the connecting part 14 to the image forming apparatus, the position of the envelope ejection tray 1 relative to the image forming apparatus is fixed. In the present embodiment, the support frame 11 is formed of aluminum.

The storage box 13 stacks and stores envelopes. The storage box 13 forms a hollow box shape with one side open. However, the storage box 13 may be designed so that its opening can open and close, similar to a cardboard box.

The storage box 13 according to the present embodiment corresponds to, for example, End-opening envelope No. 3 and Western-style envelope No. 3, and has a storage height of approximately 700 millimeters (mm) and can hold about 1000 envelopes. The storage box 13 according to the present embodiment is made of plastic, specifically a polypropylene corrugated box, and is a highly rigid product with a thickness of 5 mm and a basis weight of 1000 grams per square meter (g/m²).

The lifting section 12 holds the storage box 13. The lifting section 12 is disposed to be movable up- and down along the guide 15, following the directions indicated by the double-headed arrow A in FIG. 1. The lifting direction (or up-and-down direction in which the lifting section 12 moves up and down along the guide 15) is tilted relative to the gravity direction and its opposite direction. Specifically, in the present embodiment, as illustrated in FIG. 2, an angle α between the extending direction of the guide 15 and the bottom portion of the support frame 11 is set to 60 degrees. In other words, the angle α of the guide 15 relative to the horizontal plane on which the envelope ejection tray 1 is placed is set to 60 degrees.

The storage box 13 is elevated and lowered (or moved up and down) along the guide 15 by the lifting and lowering of the lifting section 12. In the present embodiment, the vertical travel distance of the lifting section 12 is set to 300 to 500 mm in the direction along the guide 15. The envelope ejection tray 1 is provided with a fixing structure to secure the elevational position of the lifting section 12 relative to the support frame 11.

In other words, the sheet storage (e.g., the storage box 13) is movable in the up-and-down direction tilted relative to the gravity direction.

As illustrated in FIG. 3, the lifting section 12 includes a guided part 16 and a storage box support 17. The guided part 16 is a section that is guided along the guide 15 and contains multiple guide rolls 18 inside, as illustrated in FIG. 4. The guide rolls 18 fit into guide grooves 15a of the guide 15, as illustrated in FIG. 5, allowing the guided part 16 to move up and down along the guide grooves 15a.

As illustrated in FIG. 3, the storage box support 17 holds the storage box, and moves up and down together with the guided part 16. The storage box support 17 holds the storage box 13 in a tilted position (its details will be described later).

As illustrated in FIG. 6, one end of each of multiple springs 19 that serve as biasing members is fixed to a corresponding one of multiple hooks disposed on the upper portion of the support frame 11. The spring 19 extends in the lifting direction of the lifting section 12 (see FIG. 1), and the other end thereof is fixed to the lifting section 12. In other words, the support frame 11 suspends the lifting section 12 by the springs 19. As one example, each of the springs 19 has a natural length of 300 mm, a maximum tensile length of more than 1000 mm, and a spring constant of 0.02 to 0.05 newtons per millimeter (N/mm). An appropriate number of springs 19 may be set as needed. The upper and lower portions of the spring 19 are covered by a cover member that is attached to the support frame 11, preventing the springs 19 from being touched from the outside.

The sheet storage device (e.g., the envelope ejection tray 1) further includes a bias (e.g., a biasing member 19) to bias the sheet storage (e.g., the storage box 13) upward in the up-and-down direction. The amount of descent due to stacking of a single sheet is set to a thickness of the single sheet.

The envelope ejection tray 1 according to the present embodiment is used to stack envelopes that are ejected from the image forming apparatus. In other words, as illustrated in FIG. 7, the storage box 13 is open toward an ejection section 101 of the image forming apparatus 100. The envelope ejected from the image forming apparatus 100 in the direction of arrow B through an ejection outlet is stored in the storage box 13 of the envelope ejection tray 1 via the ejection section 101. When the storage box 13 contains no envelopes, its bottom surface 13c, which is an envelope or sheet stacking surface, is located lower than the ejection section 101. The bottom surface 13c is also the lower side of the storage box 13.

As illustrated in FIG. 8, the ejection section 101 includes a chute 102, a pair of side fences 103, and ball bearing rollers 105. The chute 102 is formed of, for example, a metal plate. The chute 102 is tilted downward in the gravity direction. In other words, the chute 102 is tilted in the direction of arrow B. When the vertical direction is the 6 o'clock position of the clock, the direction of arrow B is tilted between 7 o'clock and 8 o'clock. The envelope ejected from the image forming apparatus falls on the chute 102 toward the envelope ejection tray while having its side end position regulated by the side fences 103. The ball bearing rollers 105 without lubricant are disposed on the chute 102. By providing the ball bearing rollers 105, an envelope 50 can smoothly fall along the chute 102.

As illustrated in FIG. 9, a magnet sheet 104 is attached to the lower surface of the side fence 103. The magnet sheet 104 is attached to the side fence 103 by, for example, a double-sided tape. The side fence 103 can be attached to any desired position on the chute 102 by the magnetic force of the magnet sheet 104. Thus, the side fences 103 can change the regulated position that restricts the widthwise position of the envelopes, allowing for adjustment to match the width of the envelope 50. A fluorine tape 106 is wound around the portions of the side fence 103 and the magnet sheet 104, adjacent to where the envelope 50 passes. This prevents the envelope 50 from being caught by the edge of the side fence 103, and allows the envelope 50 to smoothly fall on the side fence 103.

As illustrated in FIG. 7, the envelopes 50 dropped from the chute 102 are stored and stacked in the storage box 13. In this case, as the envelopes are stacked on the bottom surface 13c, the position of the sheet stacking surface in the storage box 13 on which the next envelope 50 is placed is raised.

When the falling distance of the envelope 50 from the chute 102 to the storage box 13 changes, the position or orientation of the envelopes 50 stacked in the storage box 13 also changes. As a result, the envelopes 50 stacked in the storage box 13 may not be aligned in orientation and be disordered. This will necessitate additional operations by workers, such as periodically aligning the bundles of envelopes loaded in the storage box 13. Further, the variation in the drop height becomes large, and the leading end of the envelope 50 is deformed, for example, is rounded when the drop height is large.

In contrast, in the present embodiment, more envelopes 50 are stacked in the storage box 13, the storage box 13 can be lowered more. In other words, as the envelopes 50 are stacked in the storage box 13, the weight of the storage box 13 increases. This increase in weight causes the spring 19 of FIG. 6 to expand, and the storage box 13 descends together with the lifting section 12 (see FIG. 7). This means that as the envelopes 50 are stacked in the storage box 13, and the storage box 13 is lowered in response to the rising stacking surface (or the upper surface of the stack of envelopes) in the storage box 13. This configuration maintains the position at which envelopes ejected from the image forming apparatus are located above the sheet stacking surface of the storage box 13 (or the bottom surface 13c of the storage box 13 or the sheet stacking surface of a tilting jig). In other words, such a configuration is unlikely to cause a difference in the falling distance from the image forming apparatus to the storage box 13 between the envelopes, and thus prevents damages such as curling of the leading end of the envelope due to the increase in the drop. Further, a simple configuration without any special driving mechanism allows the envelope 50 ejected from the image forming apparatus to be precisely positioned or stacked and stored in the storage box 13.

A sheet storage device (e.g., envelope ejection tray 1) includes a sheet storage (e.g., the storage box 13) movable in an up-and-down direction, to stack and store sheets conveyed in a conveyance direction. The sheet storage moves down according to weight of the sheets stacked in the sheet storage.

Particularly in the present embodiment, the spring constant of the spring 19 is set so that the amount of expansion of the spring 19 due to the stacking of one envelope 50 is equal to the thickness of an upstream portion of one envelope 50 in the conveyance direction. However, a slight deviation is acceptable, the expansion and the thickness do not need to be exactly equal. This arrangement ensures that the falling distance for an envelope 50, i.e., the distance in the direction of gravity from the paper ejection position of the image forming apparatus to the upstream position of the highest envelope of the stacked bundle in the storage box 13 in the conveyance direction (refer to distance L in FIG. 14), can be maintained almost the same, regardless of the amount of envelopes stacked in storage box 13. Thus, the envelopes 50 can be stacked and stored in the storage box 13 with high positional accuracy. However, the distance in the direction of gravity from the paper ejection position of the image forming apparatus to the downstream position of the highest envelope of the stacked bundle in the storage box 13 in the conveyance direction may be constant.

As illustrated in FIGS. 10A and 10B, the envelopes stacked on the envelope ejection tray of the present embodiment have an overlapping portion 50a that serves as a thick portion at one end (or the downstream end in the present embodiment) of the envelope in the conveyance direction, which is the longitudinal direction of the envelope. In other words, the overlapping portion 50a is located at one portion of the envelope 50 in the conveyance direction to form the envelop 50 into a bag shape. This configuration causes an increased thickness at the overlapping portion 50a of the envelope 50, leading to an uneven thickness of the envelope 50, as illustrated in FIG. 11.

In other words, at the overlapping portion 50a, the paper forming the envelope is triple-layered and provided with adhesive, resulting in a thickness more than 1.5 times that of areas where only two layers overlap. Thus, as illustrated in FIG. 12, stacking multiple envelopes 50 horizontally leads to tilting and collapsing of the stack of the envelopes 50 toward the opposite side of the overlapping portion 50a due to the difference in thickness. To prevent air from being trapped inside the envelope 50 during the image formation in the image forming apparatus, the overlapping portion 50a is positioned on the downstream portion of the envelope 50 in the conveyance direction.

The following describes how the envelopes 50 are stored in the storage box 13 of the envelope ejection tray 1 and the configuration of the present embodiment for reducing or preventing the above-described tilting of the stacked envelopes 50.

The envelope 50 dropped from the chute 102 (see FIG. 8) of the image forming apparatus enters the storage box 13 from the opening of the storage box 13 in the direction of arrow B as illustrated in FIG. 13A. This direction corresponds to the conveyance direction of the envelope 50. The storage box 13 having a rectangular cross section is disposed to be tilted on the X-Y plane. More specifically, the storage box 13 has a bottom surface 13b that serves as a sheet contact surface at the downstream end of the storage box 13 in the conveyance direction indicated by arrow B. The bottom surface 13b is tilted from one side to the other side in the width direction of the bottom surface 13b, tilting toward the left side, i.e., in the downstream direction in the conveyance direction. In this configuration, the envelope 50 has a corner 50b that is an end portion located at the downstream end of the envelope 50 in the conveyance direction and adjacent to a side surface 13a of the storage box 13. This corner 50b first contacts the side surface 13a of the storage box 13. The side surface 13a is a side surface of the storage box 13 that continues from the other end portion of the bottom surface 13b in the width direction. As described above, in the present embodiment, the position and tilt of the storage box 13 are adjusted so that the corner 50b of the envelop 50 ejected from the chute 102 of the image forming apparatus first contacts the side surface 13a of the storage box 13. Furthermore, the envelope ejection tray 1 is connected to the image forming apparatus 100 by the connecting part 14 (see FIG. 7).

The sheet storage has a shape of a hollow box having: an opening at a side opposite the contact surface; and a side surface on each side of the contact surface in the width direction and orthogonal to the width direction and tilted relative to the conveyance direction.

The storage box 13, particularly the bottom surface 13c of the storage box 13, is tilted downward in the direction of gravity relative to the downstream direction in the conveyance direction of the envelope 50 indicated by arrow B (see FIG. 7). In this arrangement, the envelope 50 with the corner 50b contacting the side surface 13a slides along the side surface 13a on the bottom surface 13b and falls in the direction of arrow B. Then, the corner 50c, which is located on the other side downstream in the conveyance direction of the envelope 50, contacts the bottom surface 13b of the storage box 13. In this state, with the force acting in the direction in which the envelope 50 falls, as illustrated in FIG. 13C, the envelope 50 rotates around the corner 50c as a pivot point along the arrow C. Thus, the envelope 50 is stored in the storage box 13 with its edges aligned with the bottom surface 13b and the side surface 13a.

The sheet storage has a stacking surface (e.g., the bottom surface 13c) that is disposed at a bottom of the sheet storage, tilted downward toward downstream in the conveyance direction; and orthogonal to the up-and-down direction. The sheet storage also has a contact surface (e.g., the bottom surface 13b) that is disposed at a downstream end of the sheet storage in the conveyance direction and arranged in a width direction tilted relative to a direction orthogonal to the conveyance direction. The contact surface is contactable a leading edge of each of the sheets.

Thus, the envelope 50 ejected from the image forming apparatus is stored in alignment with the surface of the storage box 13. Subsequent envelopes 50 are stored in the storage box 13 each time they fall into it, as illustrated in FIGS. 13A to 13C, and the envelopes 50 are progressively stacked inside the storage box 13. In the present embodiment, without the need for any special driving mechanism, envelopes can be ejected from the image forming apparatus and precisely aligned and stacked in the storage box 13.

In the present embodiment, as illustrated in FIG. 14, the left side of the storage box 13 (or the downstream end in the conveyance direction of the envelope) where the overlapping portion 50a is located, is tilted downward in the direction of gravity. This tilting reduces or prevents the tilting of an envelope bundle 500 stored in the storage box 13. This allows the storage box 13 to store a larger number of envelopes 50. In FIGS. 14, 15, 17, and 18, which will be described later, the thickness of the envelope 50 is exaggerated for convenience.

In FIG. 14, the inclination of the envelope bundle 500 is not sufficiently eliminated. Specifically, the overlapping portion 50a of the envelope bundle 500 (or its left side in FIG. 14) is positioned higher in the Z-direction than its opposite side. In such a state, the envelope 50 stacked on the top of the envelope bundle 500 slides off the top of the bundle and falls, as indicated by the arrow in FIG. 14. Further, a newly stacked envelope 50 fails to overcome the tilt of the envelope bundle 500, and the envelope 50 is not properly stacked in the storage box 13.

To avoid such a situation, the tilt θ of the storage box 13 is increased to prevent tilting of the envelope bundle 500. Specifically, when t (mm) indicates the thickness deviation of the envelope 50 as illustrated in FIG. 11, y (mm) indicates the length of the envelope 50 in the conveyance direction, and N (sheets) indicates the maximum number of envelopes that can be stacked in the storage box 13, θ is set to satisfy the following formula (2) to prevent tilting of the envelope bundle 500 toward the overlapping portion. For example, in the present embodiment, N is 1000, and θ is set to 30 degrees. However, the following formula does not need to be strictly satisfied, and the envelope bundle 500 may be tilted to such an extent that the envelope does not fall down. Accordingly, a margin of error can be allowed in the lower limit of θ by that amount.

$\begin{array}{cc}\theta \ge {\tan }^{-1}\left(\mathrm{tN}/y\right)& \left(2\right)\end{array}$

In other words, the sheet storage has a stacking surface tilted relative to a horizontal plane with a tilt angle. The sheet storage stores the sheets each having a first portion having a first thickness; and a second portion having a second thickness thinner than the first thickness, in a state in which formula below is satisfied:

θ≥tan⁻¹(tN/y)

• • where
  • θ indicates the tilt angle of the stacking surface,
  • t (mm) indicates a difference in thickness between the first portion and the second portion of each of the sheets,
  • y (mm) indicates a length of each of the sheets in the conveyance direction, and
  • N indicates maximum number of sheets stackable in the sheet storage.

However, as the angle θ increases, the storage box 13 tilts further away from the image forming apparatus, which may reduce the accuracy of placing the envelope 50 at a specified position within the storage box 13 (see FIG. 13C). In the present embodiment, the envelope 50 is dropped into the storage box 13 by free fall from the image forming apparatus via elements such as sheet ejection rollers and a chute. In such a configuration, if the falling distance is too large, the envelope 50 may not drop to the storage box 13.

In view of such circumstances, as illustrated in FIG. 15, a tilting jig 20 as a sheet stacking tray may be attached to the bottom surface 13c of the storage box 13, which is its lower surface in the direction of gravity. The tilting jig 20 has an envelope stacking surface 20a as a sheet stacking surface on which the envelopes 50 are stacked. The tilting jig 20 increases in thickness on the thinner end of the envelope 50 and has a tilt angle θ′ in the direction X relative to the lower surface 13c of the storage box 13. Thus, the tilting of the envelope bundle 500 can be prevented without increasing the tilt angle θ of the storage box 13. In particular, by setting θ′ so as to satisfy the following formula (3), the tilting of the envelope bundle 500 toward the overlapping portion can be prevented. The tilting jig 20 can be formed of, for example, a resin material. However, instead of the tilting jig 20, the shape of the bottom surface 13c of the storage box 13 may be processed like the envelope stacking surface 20a of the tilting jig 20.

$\begin{array}{cc}\theta +{\theta }^{\prime }\ge {\tan }^{-1}\left(\mathrm{tN}/y\right)& \left(3\right)\end{array}$

The sheet storage device (e.g., the envelope ejection tray 1) further includes a sheet stacking tray (e.g., the tilting jig 20) at a bottom end of the sheet storage in the gravity direction. The sheet stacking tray has different thicknesses between one end and the another end in the conveyance direction; and a stacking surface on which the sheets are stacked.

Further, although the case where the envelope 50 has the overlapping portion 50a on one end portion in the conveyance direction (see FIG. 10) is described above, the envelope 50 may have an overlapping portion 50a on one end in its width direction as illustrated in FIGS. 16A and 16B.

When such envelopes 50 are stacked in the storage box 13, the envelope bundle 500 is tilted due to the overlapping portions 50a as illustrated in FIG. 17. As a result, the end face (the left end face in FIG. 17) of the envelope 50 tilted downward is folded. In contrast, as illustrated in FIG. 18, the tilting jig 20 having different thicknesses on one end portion and the other end portion in the direction X can be placed on the bottom surface 13c of the storage box 13. More specifically, the tilting jig 20 is placed so that the thinner portion of the tilting jig 20 is on the right side in FIG. 18 where the overlapping portion 50a is located. The tilting jig 20 has a tilt angle θ″ in the direction Y relative to the lower surface 13c of the storage box 13. This prevents the tilting of the envelope bundle 500. In particular, when x (mm) indicates the direction orthogonal to the conveyance direction of the envelope 50, by setting θ″ so as to satisfy the following formula (4), the tilting of the envelope bundle 500 toward the overlapping portion can be prevented. The direction orthogonal to the conveyance direction of the envelope 50, also orthogonal to the thickness direction, is referred to as direction X in FIG. 18. When the image forming apparatus performs double-sided printing on the envelops 50, the arrangement of the tilting jig 20 is reversed from that in FIG. 18 because the front and back sides are reversed and the arrangement of the overlapping portions 50a is also reversed. In other words, the tilting jig 20 is placed with its thicker portion on the right side in FIG. 18. Thus, the tilted jig 20 is made attachable to and detachable from the storage box 13, thus coping with double-sided printing.

$\begin{array}{cc}{\theta }^{″}\ge {\tan }^{-1}\left(\mathrm{tN}/x\right)& \left(4\right)\end{array}$

FIG. 19 is a diagram of a tilting jig 20 incorporating multiple tilts of the tilting jigs 20 as illustrated in FIGS. 15 and 18. Specifically, the tilting jig 20 has a greater thickness at both its upstream portion in the conveyance direction and one end in the width direction, and has a smaller thickness at both its downstream portion in the conveyance direction and the other end in the width direction. By placing the tilting jig 20 in the storage box 13, tilting of the envelope bundle 500 can be prevented in any of the cases of FIGS. 10 and 16. However, the tilting jig 20 may have only one of the tilts as illustrated in FIGS. 15 and 18.

Considering the case of removal of the envelope 50 from the storage box 13, the width of the storage box 13 is made larger than the width of the envelope 50 as illustrated in FIG. 3C. Preferably, the width of the storage box 13 is larger than the width of the envelope 50 by 10 mm or more. As illustrated in FIG. 20, a spacer 21 that serves as a restricting member or a restrictor may be placed on the opposite side to the side where the envelope 50 is stored in the width direction of the storage box 13.

The spacer 21 is placed to cover a portion of the internal width of the storage box 13. This achieves the above-described case of taking out the envelope 50, and allows the envelope 50 automatically stored in the storage box 13 to be precisely positioned as illustrated in FIG. 13C. Thus, the envelopes 50 that make up the envelope bundle can be aligned and stacked. Particularly in the present embodiment, the spacer 21 has a tilted surface 21a, and the widthwise position of the envelope 50 can be reduced in a direction from upstream to downstream in the conveyance direction of the envelope 50 indicated by arrow B. Thus, as the envelope 50 is conveyed, the envelope 50 can be stored in a predetermined position in the storage box 13.

The sheet storage (e.g., the storage box 13) includes a restrictor to restrict a widthwise position of each of the sheets in the sheet storage in a width direction tilted relative to a direction orthogonal to the conveyance direction.

The restrictor (e.g., the spacer 21) has a tilted surface (e.g., the tilted surface 21a) to gradually reduce a width of the sheet storage in the width direction toward downstream in the conveyance direction.

The spacer 21 may be formed of the same material as that of, for example, the storage box 13 to reduce the weight. The spacer 21 may be formed of an appropriate material such as a resin material or a metal material. Preferably, the spacer 21 is attachable to and detachable from the storage box 13, and is attached to the storage box 13 by, for example, Velcro (registered trademark). As a result, for example, the spacer 21 can be removed to accommodate a long No. 3 envelope 50 with a width of 120 mm, and attached to accommodate a short No. 4 envelope 50 with a width of 90 mm. This allows for flexible usage based on the size of the envelopes. The spacer 21 may have a thickness in the Z-direction.

The storage box 13 is detachably attached onto the storage box support 17 (see FIG. 3) of the lifting section 12. This arrangement shortens the time until the next operation after placing another storage box 13 when the current storage box 13 becomes full.

As illustrated in FIG. 21, the storage box 13 has handles 13dl and 13d2 on the upper and lower portions thereof. With the handles 13dl and 13d2, the operator can easily lift the storage box 13, and the operation of attaching and detaching the storage box 13 to and from the lifting section is facilitated. The handles 13dl and 13d2 of the present embodiment are formed by holes penetrating a part of the wall surface of the storage box 13, but are not limited thereto. For example, by forming the lower handle 13d2 in a non-through bag shape opened downward, the load of the storage box 13 can be easily supported by the portion of the handle 13d2.

The storage box 13 includes reinforcing portions 13e at its opening end. In the present embodiment, the reinforcing portions are particularly formed around the entire perimeter of the opening. The reinforcing portions 13e of the present embodiment are formed by fixing resin members to the opening end of the storage box 13 with, for example, an adhesive. By providing the reinforcing portions 13e, the strength of the opening end of the storage box 13 is increased, and the deformation of the storage box 13 is prevented. This prevents disarray and misalignment of envelopes loaded inside the storage box 13 due to the deformation of the storage box 13.

The bottom surface 13b of the storage box 13 is designed such that the corrugation of the cardboard extends vertically. If the corrugation of the cardboard is oriented horizontally, envelopes may become snagged on the grooves of the corrugation and not fall properly. However, the configuration of the present embodiment is intended to prevent such difficulty.

As illustrated in FIG. 22, the storage box 13 may include a bottom plate 22 that serves as a sheet contact section on the bottom surface 13b. The surface 22a of the bottom plate 22 forms an envelope contact surface or a sheet contact surface that contacts the leading edge of the envelope in the storage box 13. A buffer material 23 that serves as a shock absorber is disposed between the bottom plate 22 and the bottom surface 13b. The buffer material 23 is placed in contact with the back side of the bottom plate 22, which corresponds to areas other than the range where envelopes contact an envelope contact surface (or the surface 22a). The buffer material 23 is formed of, for example, sponge. With such a configuration, the impact when the envelope falls into the storage box 13 is absorbed, the envelope can be accurately arranged at a predetermined position in the storage box 13, and the envelopes loaded or stacked in the storage box 13 can be accurately aligned. The bottom plate 22 can be formed of, for example, the same material as that of the storage box 13. In this case, by arranging the corrugation of the bottom plate 22 to extend vertically, envelopes are prevented from becoming snagged on the corrugation as they fall.

The sheet storage device (e.g., the envelope ejection tray 1) further includes a shock absorber (e.g., the buffer material 23) on a downstream end of the sheet storage in the conveyance direction; and a sheet contact section (e.g., the bottom plate 22) on the shock absorber, the sheet contact section having a contact surface (e.g., the surface 22a) contactable a leading edge of each of the sheets in the conveyance direction. The shock absorber contacts a back face opposite to the contact surface of the sheet contact section.

This disclosure has been described above with reference to specific embodiments. It is to be noted that this disclosure is not limited to the details of the embodiments described above, but various modifications and enhancements are possible without departing from the scope of the invention. It is therefore to be understood that this disclosure may be practiced otherwise than as specifically described herein. For example, elements and/or features of different embodiments may be combined with each other and/or substituted for each other within the scope of this invention. The number of constituent elements and their locations, shapes, and so forth are not limited to any of the structure for performing the methodology illustrated in the drawings.

In the above description, the envelope is exemplified as an example of the sheet, but the sheet stored in the sheet storage device of the present disclosure is not limited thereto. The “sheet” includes the sheet P (plain papers), thick papers, postcards, thin papers, coated papers (coated papers, art papers, etc.), tracing papers, OHP sheets, plastic films, prepreg, and copper foil, in addition to envelopes.

In the above description, the sheet storage device for stacking and storing the sheets ejected from the image forming apparatus has been exemplified, but the present disclosure is not limited thereto.

Now, a description is given of some aspects of the present disclosure.

<1>

A sheet storage device includes: a sheet storage movable up and down, the sheet storage to stack and store sheets. The sheet storage moves down according to weight of the sheets stacked in the sheet storage.

<2>

In the sheet storage device according to <1>, the sheet storage moves up and down in an up-and-down movement direction that is tilted relative to a direction of gravity and an opposite direction of the direction of gravity.

<3>

In the sheet storage device according to <2>, the sheet storage has: a sheet stacking surface tilted downward in the direction of gravity, relative to a direction from upstream to downstream in a conveyance direction of the sheets; and a sheet contact surface located at a downstream end of the sheet storage in the conveyance direction and tilted downstream in the conveyance direction and in a direction from one end to the other end in a width direction of the sheet contact surface, the sheet contact surface to contact a leading edge of each of the sheets.

<4>

In the sheet storage device according to <3>, the sheet storage has: a hollow box shape; and an opening at a side opposite the sheet contact surface; and a side surface continuous from the other end of the sheet contact surface and tilted to allow a corner, closest to the side surface, of a downstream end of a sheet entered through the opening in the conveyance direction to first contact the side surface.

<5>

In sheet storage device according to any one of <2> to <4>, each of the sheets has a first portion and a second portion, the first portion thicker than the second portion, formula below is satisfied:

$\begin{array}{cc}\theta \ge {\tan }^{-1}\left(\mathrm{tN}/y\right)& \left(1\right)\end{array}$

• • where
  • θ indicates a tilt angle of a horizontal plane of a sheet stacking surface of the sheet storage,
  • t (mm) indicates a difference in thickness between the first portion of each of the sheets and the second portion,
  • y (mm) indicates a length of each of the sheets in the conveyance direction, and
  • N indicates maximum number of sheets to be stacked in the sheet storage.

<6>

The sheet storage device, further includes a biasing member to bias the sheet storage in an upward direction. An amount of descent due to stacking of a single sheet is set to the same as a thickness of the single sheet.

<7>

The sheet storage device, further includes a holder holding the sheet storage. The sheet storage is attachable to and detachable from the holder.

<8>

The sheet storage device, further includes: a shock absorber on a downstream end of the storage sheet; and a sheet contact section on the shock absorber, the sheet contact section having a sheet contact surface to contact a leading edge of each of the sheets. The shock absorber contacts a backside of the sheet contact surface.

<9>

The sheet storage device according to any one of <1> to <8>, further includes a sheet stacking tray at a downstream end of the sheet storage in the direction of gravity, the sheet stacking tray: having different thicknesses between one end and the other end; and forming a sheet stacking surface of the sheet storage.

<10>

In the sheet storage device according to any one of <1> to <9>, the sheet storage includes a restrictor to restrict a widthwise position of each of the sheets in the sheet storage in a width direction of the sheet storage.

<11>

The sheet storage device according to <10>, the restrictor has a tilted surface to gradually reduces the widthwise position in a direction from upstream to downstream in a conveyance direction of the sheets.

The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present invention.

Claims

1. A sheet storage device comprising:

a sheet storage movable in an up-and-down direction, to stack and store sheets conveyed in a conveyance direction,

wherein the sheet storage moves down according to weight of the sheets stacked in the sheet storage.

2. The sheet storage device according to claim 1,

wherein the sheet storage is movable in the up-and-down direction tilted relative to a gravity direction.

3. The sheet storage device according to claim 2,

wherein the sheet storage has:

a stacking surface: disposed at a bottom of the sheet storage; tilted downward toward downstream in the conveyance direction; and orthogonal to the up-and-down direction; and

a contact surface: disposed at a downstream end of the sheet storage in the conveyance direction; and arranged in a width direction tilted relative to a direction orthogonal to the conveyance direction, and the contact surface contactable a leading edge of each of the sheets.

4. The sheet storage device according to claim 3,

wherein the sheet storage has a shape of a hollow box having:

an opening at a side opposite the contact surface; and

a side surface:

on each side of the contact surface in the width direction; and

orthogonal to the width direction and tilted relative to the conveyance direction.

5. The sheet storage device according to claim 2,

wherein the sheet storage has a stacking surface tilted relative to a horizontal plane with a tilt angle,

the sheet storage stores the sheets each having:

a first portion having a first thickness; and

a second portion having a second thickness thinner than the first thickness,

in a state in which formula below is satisfied: θ≥tan−1(tN/y)

where

θ indicates the tilt angle of the stacking surface,

t (mm) indicates a difference in thickness between the first portion and the second portion of each of the sheets,

y (mm) indicates a length of each of the sheets in the conveyance direction, and

N indicates maximum number of sheets stackable in the sheet storage.

6. The sheet storage device according to claim 1, further comprising a bias to bias the sheet storage upward in the up-and-down direction,

wherein an amount of descent due to stacking of a single sheet is set to a thickness of the single sheet.

7. The sheet storage device according to claim 1, further comprising a holder holding the sheet storage,

wherein the sheet storage is detachably attachable to the holder.

8. The sheet storage device according to claim 1, further comprising:

a shock absorber on a downstream end of the sheet storage in the conveyance direction; and

a sheet contact section on the shock absorber, the sheet contact section having a contact surface contactable a leading edge of each of the sheets in the conveyance direction,

wherein the shock absorber contacts a back face opposite to the contact surface of the sheet contact section.

9. The sheet storage device according to claim 1, further comprising a sheet stacking tray at a bottom end of the sheet storage in a gravity direction,

wherein the sheet stacking tray has:

different thicknesses between one end and another end in the conveyance direction; and

a stacking surface on which the sheets are stacked.

10. The sheet storage device according to claim 1,

wherein the sheet storage includes a restrictor to restrict a widthwise position of each of the sheets in the sheet storage in a width direction tilted relative to a direction orthogonal to the conveyance direction.

11. The sheet storage device according to claim 10,

wherein the restrictor has a tilted surface to gradually reduce a width of the sheet storage in the width direction toward downstream in the conveyance direction.