JP2613470B2 - Paper stacking device for image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper stacking apparatus provided in an image forming apparatus such as a laser printer or an electrostatographic copier.

[Conventional technology]

For example, as a device for stacking sheets after image formation in a laser printer, as shown in FIGS. 8 and 9, upper and lower discharge rollers 42 and 43 for discharging sheet a after image formation onto a tray 41. At the lower side of the pair and at the lower end of the inclined tray 41, the sheets a stacked on the tray 41
In some cases, a rear end defining member 44 is provided for aligning the rear end of the camera.

In such a paper stacking apparatus, generally, the tray
The number of sheets stacked until the uppermost sheet a stacked on the sheet 41 comes into contact with the lower sheet discharging roller 43 is the maximum number of sheets stacked in the sheet stacking apparatus.

By the way, in a laser printer configured to store a large amount of sheets, a large number of images are continuously recorded, and sheets of the maximum number of sheets or more are stacked on the tray 41.
Are often integrated into

On the other hand, if the rear end defining member 44 is simply provided on the lower side of the lower discharge roller 43, a gap is formed between the upper edge portion of the rear end defining member 44 and the lower discharge roller 43. ,
When the number of sheets a is larger than the maximum number of sheets stacked on the tray 41, the uppermost sheet a in contact with the lower sheet discharge roller 43 receives the conveying force of the lower sheet discharge roller 43, and
However, the inconvenience of being caught in the gap occurs.

Therefore, a concave portion b is provided at the upper edge portion of the rear end defining member 44, the lower paper discharge roller 43 is inserted into the concave portion b, and the paper is wound around the both sides of the concave portion of the rear end defining member 44. To prevent this.

[Problems to be solved by the invention]

However, due to the bending or rotation of the support shaft 45 of the lower discharge roller 43, the amount of the lower discharge roller 43 entering the recessed portion b becomes shallow or escapes,
Particularly, in recent years, when the support shaft 45 is made of a synthetic resin, the above-described bending is remarkable in configuring the lower discharge roller 43 to be lightweight and inexpensive as in recent years. When the amount of entry of the lower discharge roller 43 into the insertion portion b becomes shallow or escapes, a gap is formed between the upper edge portion on both sides of the recess portion b and the lower discharge roller 43 when viewed in the roller axis direction. In some cases, the paper a was entangled in the gap.

The prevention of the paper a from being entangled due to the bending of the support shaft 45 can be achieved by increasing the amount of the lower discharge roller 43 entering the concave portion b. However, the depth of the concave portion b is increased. In addition, if the diameter of the lower discharge roller 43 is increased, the maximum number of stacked sheets becomes extremely small. Alternatively, if the height of the lower discharge roller 43 having the increased diameter with respect to the tray 41 is increased, the maximum When the number of stacked papers is ensured, not only does the apparatus become noble but also the paper discharge height of the pair of paper discharge rollers 42 and 43 with respect to the tray 41 becomes too high, and the paper a is discharged to the tray. In this case, there is a disadvantage that the paper a slightly curled downward is turned upside down, or the discharging posture of the paper a to the tray 41 is disturbed.

Further, if the sheets a are stacked more than the maximum stacking number or the sheets a are stacked in a curled state, the rear end of the sheet a contacts the lower discharge roller 43 and the rear end of the sheet becomes dirty. There was also a problem of getting hurt.

The paper stacking device according to the first aspect of the present invention allows the paper to be rolled up when the sheets are stacked to the maximum stacking number or more without sacrificing the maximum stacking number of sheets or increasing the diameter of the lower discharge roller. The purpose is to be able to prevent it effectively.

The paper stacking apparatus of the second invention achieves the first object and further prevents dirt and damage at the rear end of the paper when the papers of the maximum number or more are stacked on the tray. It is intended to be.

[Means for solving the problem]

In order to achieve the first object, the present invention relates to a method of forming a rear end defining member for sheets stacked on a tray at the lower side of a pair of upper and lower discharge rollers and at the lower end of an inclined tray. In the paper stacking device of the image forming apparatus provided, the upper edge portion and the lower discharge portion of the rear end defining member are attached to a member loosely fitted to the lower discharge roller or a member loosely fitted to the support shaft of the lower discharge roller. The present invention is characterized in that a paper entanglement preventing member for preventing paper from being entangled in a gap created by a paper roller is provided in series.

In order to achieve the second object, the present invention provides a paper stacking apparatus for an image forming apparatus which has attained the first invention, and further comprises at least a tray surface from a downstream side of a nip point of the discharge roller pair. The present invention is characterized in that the loose-fit member is provided with a paper trailing end defining portion that protrudes slightly from the outer peripheral surface of the lower discharge roller in a range extending from a contact point of the lower discharge roller to a parallel surface.

[Action]

According to the paper stacking apparatus of the first aspect of the present invention, under the situation where sheets of the maximum number or more are stacked on the tray,
Even if a gap is formed between the upper edge portion on both sides of the recessed portion and the lower discharge roller due to the bending of the lower discharge roller or the roller support shaft, the lower discharge roller or the roller support By making the function that the entanglement preventing member moving integrally with the shaft always generates the gap,
Entanglement of the paper into the gap is reliably prevented.

According to the sheet stacking device of the second aspect of the present invention, the function of the sheet trailing end defining portion prevents the trailing end of the sheets stacked on the lower stacking roller of the maximum stacking number or more from being brought into contact with the lower sheet discharging roller. Dirt and damage are prevented.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows a laser printer as an example of an image forming apparatus, in which a photoconductor 2 is laid horizontally inside a printer main body 1 and a charging device 3, a developing device 4, a transfer device and the like are provided around the photoconductor 2. 5, the cleaning device 6 is arranged in the rotation direction of the photoconductor 2 in that order, and the optical unit 7 is provided in the upper space of the printer main body 1, and the loading unit 9 of the cassette case 8 is provided in the lower space. Further, a paper feeder 10 for transporting the paper fed from the cassette case 8 toward the transfer device 5 is provided, and a paper discharge transporter 12 for transporting the paper after image transfer to the fixing device 11. And a sheet stacking device 13 for turning over the image-fixed sheet and stacking it on the upper portion of the printer.

The paper stacking device 13 is configured as follows.
That is, a first pair of paper discharge rollers 14 and 15 for feeding out the fixed paper a after forming an image is provided immediately downstream of the fixing device 11 and at a position above the first pair of paper discharge rollers 14 and 15. A pair of upper and lower second paper discharge rollers 16, 17 is disposed, and a path forming member 18 extending between the pair of second paper discharge rollers 14, 15, 16, 17 is provided.
Is provided so as to be rotatable around a horizontal axis 19 near the downstream side of the paper discharge roller pair 15.

As shown by the imaginary line, the path constituting member 18 is
By rotating the apparatus around the outside 19 around the path forming member 18 as a paper discharge tray, the paper a
Can be taken out without turning over.

On the other hand, the upper face plate of the printer body 1 corresponding to the upper part of the fixing device 11 and the optical unit 7 is
Tray 20 and 17
And at the lower end of the inclination of the tray 20 and at the lower side of the second paper discharge rollers 16 and 17, a paper trailing edge defining the trailing edge of the paper a stacked on the tray 20. A member 21 is provided. Reference numeral 22 denotes an auxiliary tray that is pivotally attached to the upper side of the tray 20 so as to be freely foldable.

As shown in FIGS. 2 to 4, the second paper discharge rollers 16, 17 are provided at predetermined intervals on support shafts 23, 24 made of, for example, synthetic resin, while The upper edge of the member 21 is formed with a concave portion b into which a part of the lower paper discharge roller 17 is inserted, and has a shape corresponding to the outline of the paper discharge roller 17 and the support shaft 24. The lower support shaft 24 on the lateral side of the lower discharge roller 17 has a lower discharge roller 17 and a rear end defining member 21 that are generated when the support shaft 24 bends.
And a paper entanglement preventing device 25 for preventing the paper a from being entangled in the gap with the upper edge of the paper.

The paper entanglement preventing member 25 is made of, for example, a synthetic resin, and has a C-shaped loose fitting member 26 which is loosely fitted to a supporting shaft portion between the annular ribs c, c formed by bulging the supporting shaft 24. The loose fitting member is formed by continuously connecting a pointed
In a state in which 26 is elastically loosely fitted to the support shaft portion between the annular ribs c from outside in the radial direction, the entanglement preventing member 27 is slidable on the rear end defining surface S of the rear end defining member 21. Is in contact with The lower end of the entanglement preventing member 27 is positioned below the bottom surface of the recessed portion b under the maximum bending of the support shaft 24 in consideration of the amount of bending of the support shaft 24 due to rotation. It is configured in.

According to the above configuration, when the sheets a are stacked in a curled state on the tray 20, or in a state where the sheets a of a maximum number or more are stacked, the support shaft 24 is stacked.
The gap between the lower discharge roller 17 and the upper edge portion of the rear end defining member 21 in which the paper a is caught between the lower discharge roller 17 and the upper edge of the rear end defining member 21 due to the bending of the lower discharge roller 17 into or out of the concave portion b due to the bending of the lower discharge roller 17 Occurs, the entanglement preventing member 27 that moves integrally with the support shaft 24 functions so as to always face the gap and close a part of the gap. Even if the lower sheet discharging roller 17 receives the conveying force, the sheet is not conveyed, so that the uppermost sheet a is reliably prevented from being caught.

The lower end of the entanglement preventing member 27 may be formed on a flat surface. However, as shown in FIG. 5 (A), when the trailing edge of the sheet is defined by the entanglement preventing member 27, As shown in FIG. 2B, when the support shaft 24 is bent and the entanglement preventing member 27 moves upward, and at this time, the paper a enters below the entanglement preventing member 27, the entanglement preventing member 27 is moved. When returning to the original posture, there is a concern that the paper a is crushed by the entanglement preventing member 27.

However, if the lower end of the entanglement preventing member 27 is formed to have a pointed shape, the paper a that has entered below the entanglement preventing member 27 is directed in the plane direction by the wedge action when the entanglement preventing member 27 returns to the original posture. And it is possible to prevent the paper a from being crushed.

However, as shown in FIG. 5 (C), a concave portion d is provided in the rear end defining member 21 and
The above inconvenience can be avoided if 27 is inserted.

Next, a first alternative embodiment of the paper entanglement preventing device 25 is shown in FIG.

This is a loose fitting member provided with a continuous prevention member 27
A portion corresponding to the tray 20 relative to 26, which was provided with a paper trailing edge defining portion 28 in a state to yaゝprotrudes from the outer peripheral surface S ₁ of the lower discharge roller 17 in the axial direction as viewed in the support shaft 24 ,
More specifically, the nip point P of the pair of upper and lower discharge rollers 16 and 17 is
₁ also killing thanゝarbitrary point P on the downstream side ₂ (preferably nip point P
_1), wherein the range over the tip of the preventing member 27 trapping the past the contact P ₃ of the lower discharge roller 17, a point of providing the sheet rear end defining portion 28 against the surface S ₃ parallel to the tray plane S ₂ There is a feature.

According to the above-described configuration, it is possible to prevent the above-described paper a from being entangled, and when the papers a of a maximum number or more are sequentially stacked on the tray 20, the uppermost sheet a is set to the arbitrary point P _2. Until the rear end of the sheet a is not brought into contact with the lower discharge roller 17, the rear end of the sheet a exceeding the maximum number of stacked sheets is
Is reliably prevented from being soiled or damaged.

The above paper trailing edge defining portion 28, the lower discharge roller for nipping point P ₁ at least the tray surface S plane parallel S ₃ to ₂ from the downstream side of the upper and lower discharge rollers 16 and 17 pairs
It may be provided in a range over the contact P ₃ of 17.

FIG. 7 shows a sheet entanglement preventing device 25 according to a second alternative embodiment.

In this apparatus, members 29 having substantially the same shape as the paper entanglement preventing member 25 shown in FIG. 6 are provided on both sides of the plate-shaped member 30 and a surface of the plate-shaped member 30 corresponding to the tray 20 is made of, for example, fluorine. Paper trailing edge defining part made of low friction material such as resin sheet
28 stuck to, and made by hanging below the plate member 30 of the lower side of the paper rear end defining portion 28 covers the outer peripheral surface S ₁ of the lower discharge roller 17 in plate member 30 So that the member
29 is loosely fitted to the support shaft portions on both sides of the lower sheet discharge roller 17, and is functionally the same as the sheet entanglement prevention device 25 shown in FIG.

Although the entanglement preventing member 27 is arranged so as to correspond to the recessed portion b, the entanglement preventing portion 27 may be arranged at a position outside the recessed portion b. Although it is configured to be provided, it may be wide and may be configured as one unit.
It is important that at least the sheet be within the minimum sheet width to be collected.

The lower discharge roller 17 has a roller structure in which the lower discharge roller 17 is provided on the support shaft 24. However, the lower discharge roller 17 has a single roller structure, and an annular concave groove is provided in the peripheral portion thereof. A configuration in which the entanglement preventing device 25 is loosely fitted may be adopted.

Further, although the paper stacking device 13 is placed on the tray 20 of a laser printer, the tray and sorter of an electrostatographic copier and a facsimile machine, the tray of an automatic document feeding and discharging device, and the front and back inside a duplex copying machine. It goes without saying that various objects such as an inverting intermediate tray can be targeted for the sheet stacking device 13.

〔The invention's effect〕

As described above, according to the paper stacking apparatus of the first aspect of the present invention, the paper can be reliably prevented from being entangled without increasing the diameter of the lower discharge roller or sacrificing the number of stacked papers. According to the present invention, furthermore, it is possible to reliably prevent dirt and damage caused by the lower discharge roller at the rear end of the sheets stacked more than the maximum number of sheets to be stacked. It could be resolved.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional side view of a laser printer as an example of an image forming apparatus, FIG. 2 is a cross-sectional view of a main part of the paper stacking apparatus, and FIG. FIG. 4 is a front view of a main part of the sheet stacking apparatus, and FIGS. 5 (A) to (C) are function explanatory diagrams. 6 and 7 show another embodiment of the paper entanglement preventing device, respectively. FIG. 6 is a sectional view of a main part of the paper stacking device, and FIG.
The figure is a perspective view of the paper entanglement preventing device. 8 and 9 show a conventional paper stacking device, FIG. 8 is a perspective view, and FIG. 9 is a sectional view. 16, 17 ... paper discharge roller, 20 ... tray, 21 ... rear end defining member, 24 ... support shaft, 26 ... loose fitting member, 27 ... entanglement prevention member, 28 ... paper rear end defining portion , A… paper, P ₁ … nip point, P ₃ … contact point, S… rear end specified surface, S ₁ … outer peripheral surface of lower discharge roller, S ₂ … tray surface, S ₃ … Surface parallel to the tray surface.

Claims (2)

(57) [Claims] A sheet stacking device for an image forming apparatus, wherein a rear end defining member for sheets stacked on the tray is provided at a lower side of a pair of upper and lower discharge rollers and at a lower end of an inclined tray. The paper is caught in a gap formed by the upper edge portion of the rear end defining member and the lower discharge roller on a member loosely fitted on the lower discharge roller or a member loosely fitted on the support shaft of the lower discharge roller. A sheet stacking device for an image forming apparatus, wherein a sheet wrap preventing member for preventing the sheet from being rolled up is continuously provided. 2. A sheet stacking device for an image forming apparatus, wherein a rear end defining member for sheets stacked on the tray is provided below the upper and lower discharge rollers and at the lower end of the inclined tray. The paper is caught in a gap formed by the upper edge portion of the rear end defining member and the lower discharge roller on a member loosely fitted on the lower discharge roller or a member loosely fitted on the support shaft of the lower discharge roller. And a lower paper discharge roller extending from a downstream side of the nip point of the paper discharge roller pair to at least a contact point of the lower paper discharge roller with respect to a surface parallel to the tray surface. A sheet stacking device for an image forming apparatus, wherein a sheet rear end defining portion projecting slightly from the outer peripheral surface of the sheet is provided on the loose fitting member.