JPH0798616B2 - Image forming device - Google Patents

Description

The present invention relates to a sheet feeding device of an image forming apparatus such as a copying machine and a laser beam printer, and more specifically, to a sheet that has been once image-formed again. The present invention relates to a sheet feeding device that re-feeds a sheet for printing.

(B) Conventional technology Conventionally, a double-sided mode in which images are formed on both sides of one sheet,
Alternatively, there is an image forming apparatus such as a copying machine provided with a multiple mode in which a plurality of images are formed on the same surface in an overlapping manner. And the fourth
FIG. 1 is a side view showing the outline of the image forming apparatus. As shown in FIG. 4, the image forming apparatus M includes an image forming section 1 and a sheet feeding unit for feeding a sheet to the image forming section 1. A feeding unit 2, a fixing unit 3 that fixes the image of the sheet formed by the image forming unit 1, a sheet discharging unit 5 that discharges the image-formed sheet, and an image is formed once and then fed to the image forming unit 1 again. The intermediate tray 6 that temporarily stores the sheets to be fed, the re-feed sheet guide portion 7 that guides the sheets to be re-fed to the intermediate tray 6, and the sheets that are stored in the intermediate tray 6 are fed to the image forming portion 1 again. The sheet re-feeding unit 9 to be fed is arranged, and when the double-sided mode or the multiple motor is selected, the sheet on which the image is formed by the image forming unit 1 once has the image fixed by the fixing unit 3. Then, immediately without being discharged to the sheet discharge section 5, Loaded & accommodated in the intermediate tray 6 by feeding the sheet guiding unit 7, where that is a predetermined number of stored, and is feeding back to the image forming section 1 by the sheet refeed section 9. However, the sheets that start from the sheet feeding unit 2 and are stacked / stored in the intermediate tray 6 are often skewed because they have passed through a long transport path, and are also stacked / stored in the intermediate tray 6. Since the sheet also skews at this time, there are variations in the orientation and position on the intermediate tray 6 (variations in the horizontal direction with the sheet traveling direction as the vertical direction). Therefore, the sheets stacked / stored on the intermediate tray 6 are in a state of being stacked separately, and if they are re-fed as they are, they may cause skewing, or improper feeding, and jams. Further, particularly in the multiplex mode, when the position of the re-feed sheet shifts in the horizontal direction, a shift occurs in the superimposed images (horizontal registration shift). Therefore, in order to prevent this, the regulation side plates 10 and 10 which are moved by the driving force of a motor or the like are arranged on the intermediate tray 6, and the regulation side plates 10 and 10 are located at both side ends of the sheet entering the intermediate tray 6. To adjust the sheet orientation and lateral position (width adjustment). Further, the intermediate tray 6 is provided with a half-moon-shaped sheet feeding roller 11, and the sheet re-feeding section 9 is provided with a sheet re-feeding roller 12 and a separation roller 13. The lower part of the sheets stacked / stored on the sheet 6 is joined to the re-feed roller 12 and the separation roller 13 along the sheet guide 15 by rotating the half-moon-shaped sheet feeding roller 11 once or twice. (Nip part) A'is fed. And these refeed rollers
As shown in FIG. 5, the sheets S fed into the nip portion A ′ between the sheet 12 and the separating roller 13 are rotated one by one by the rotation of the sheet re-feeding roller 12 and the separating roller 13 one by one from the lowest sheet. And is re-fed to the image forming unit 1.

(C) Problems to be Solved by the Invention By the way, when the sheets are stacked / stored on the intermediate feed tray 6 from the re-feed sheet guide portion 7, the leading edge of the sheet is directly fed by the sheet re-feed portion 9. The sheet may enter the nip portion A'between the paper roller 12 and the separation roller 13 and be caught in the nip portion A'before the width of the regulation side plates 10, 10 is adjusted. Even if the width is adjusted in such a state, a sufficient effect cannot be obtained.

(D) Means for Solving the Problem The present invention is intended to solve the above problems, and an intermediate tray for stacking image-formed sheets for re-imaging, and the intermediate tray. A re-feeding member that gives a feeding force to the upper sheet from the lowest sheet, a separating member that separates other sheets from the sheet sent by the re-feeding member, and to stack the image-formed sheets A conveying means for sequentially feeding the sheets to the intermediate tray from the side opposite to the re-feeding member; and a position for closing the path of the sheets fed to the intermediate tray by the conveying means to the re-feeding member. A sheet stopper that is displaced to an open position, and a direction in which the sheet is stacked on the intermediate tray and the leading end thereof comes in contact with and separates from a side end portion of the sheet whose position is regulated by the sheet stopper. A regulating side plate that moves and aligns the stacked sheets, and gradually approaches the intermediate tray toward the re-feeding member above the intermediate tray, and its tip is located upstream of the closed position by the sheet stopper. The sheet is extended so as to be positioned, and a gap is formed between the intermediate tray and the intermediate tray to limit the amount of the sheet that can advance to the sheet stopper, and the sheet fed by the conveying unit is located on the upstream side of the previously stacked sheets. A first sheet guide that guides the leading edge of the sheet so that the sheets are stacked in a shifted manner, and the leading edge is disposed downstream of the closing position by the sheet stopper, and the sheet is displaced upstream of the previously stacked sheets. An image including a second sheet guide that guides the leading edge of the sheet to the nip between the re-feed member and the separating member so as to be stacked. In the adult system.

(E) Operation Based on the above configuration, the sheets discharged to the intermediate tray are sequentially aligned and stacked on the intermediate tray. At this time, the sheet comes into contact with the sheet contact surface of the sheet stopper that closes the path of the sheet to the nip portion of the re-feeding means, and is held in this position without being gripped by the nip portion of the re-feeding means. The side edge of the sheet is aligned by the regulation side plate. The first sheet guide disposed upstream of the sheet stopper forms a gap between the sheet stopper and the intermediate tray to limit the amount of the sheet that can advance to the sheet stopper, and the sheet fed by the conveying unit is first. The leading edge of the sheet is guided so as to be shifted (wedge-shaped) toward the upstream side of the sheet stacked on the sheet. Further, since the second sheet guide disposed on the downstream side of the sheet stopper makes the leading edge of the sheet into the wedge shape and guides it to the nip portion of the re-feeding member and the separating portion, it is guided by the first sheet guide described above. A limited amount of sheets that have been conveyed and that are conveyed by opening the sheet stopper are accurately guided from the lowest position to the nip for reliable re-feeding.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

The image forming apparatus according to the present exemplary embodiment has a function of forming an image on both surfaces of a sheet or on the same surface, and like the image forming apparatus M, an image forming unit, a sheet feeding unit, and a fixing unit. Unit, sheet discharge unit, re-feed sheet guide unit, intermediate tray unit, sheet re-feed unit, and the like. FIG. 1 is a side view showing the intermediate tray portion 21 and the sheet refeeding portion 22 of the image forming apparatus according to this embodiment. The intermediate tray portion 21 and the sheet refeeding portion 22 are the above-mentioned image forming apparatus M. Like the above, the sheet is arranged downstream of the re-feed sheet guide section, the intermediate tray section 21 is provided with a bottom plate 23 for stacking sheets to be re-fed, and the bottom plate 23 is moved by a driving force of a motor or the like. The regulating side plates 25, 25 are arranged, and the both side edges in the width direction of the sheets stacked on the bottom plate 23 are aligned to align the sheets.
Further, a half-moon-shaped sheet feeding roller 26 is arranged below the bottom plate 23, and a sponge roller 27 is arranged so as to face the sheet feeding roller 26.
Are arranged, the sheets are stacked on the bottom plate 23, and the stacked sheets are conveyed toward the sheet refeed unit 22. Further, a re-feeding roller 29 and a separating roller 30 are arranged in the sheet re-feeding section 22, and a bottom plate 23 of the intermediate tray 21 is provided at a nip portion A between the re-feeding roller 29 and the separating roller 30.
When the upper sheet is fed, the sheets are separated one by one and re-fed to the image forming unit.

On the other hand, a stopper support pin 31 is provided near the refeed roller 29.
A seat stopper 32 is rotatably supported by the seat stopper 32, a stopper spring 33 is attached to the seat stopper 32, and a solenoid 36 arranged below the bottom plate 23 is connected via a link 35. The leading end 32a of the sheet stopper 32 stands up against the urging force of the stopper spring 33 due to the excitation of the solenoid 36, and the re-feed roller 29
And the separating roller 30 so as to project toward the nip portion A to close the path of the sheet to the nip portion A, restrict the sheet from entering, and when the excitation of the solenoid 36 is released, the stopper spring 33 Retracts by the tension of and releases the path of the seat. A guide plate (first sheet guide) 37 that is inclined with respect to the bottom plate 23 is provided above the bottom plate 23, and the guide plate 37 has a tip portion 37a of which a tip end of a sheet stopper 32 stands. When the sheets discharged onto the bottom plate 23 are stacked on the bottom plate 23 so as to face the upstream side 32a in the sheet conveying direction, the leading ends of the sheets are as shown in FIG. 7 (a). It is arranged so as to be guided in a wedge shape, and limits the amount of the sheet advancing to the vicinity of the nip portion A between the re-feeding roller 29 and the separating roller 30. Further, the leading end 32a of the standing sheet stopper 32 is located between the leading end portion 37a of the guide plate 37 and the nip portion A of the re-feed roller 29 and the separation roller 30. When the leading end 32a of the sheet retracts to open the path of the sheet, the leading edge of the wedge-shaped sheet formed on the bottom plate 23 is not damaged. It is preferable that the distance between the front end portion 37a of the guide plate 37 and the bottom plate 23 is narrow enough not to prevent the sheet from entering the nip portion A of the re-feed roller 29 and the separation roller 30. Further, a separation roller front guide plate (second sheet guide) 39 is provided between the guide plate 37 and the separation roller 30 such that a tip end portion 39a thereof is located on the downstream side of the sheet stopper 32 and close to the nip portion A. It is arranged and the above guide plate
When the double guide is constituted by 37 and the separation roller front guide plate 39, when the sheet to be re-fed is fed into the nip portion A of the re-feed roller 29 and the separation roller 30 to be separated and re-fed In addition, the resistance of the upper sheet is further reduced, and the separation and re-feeding of the sheets from the lowermost sheet are surely performed.

Since the present embodiment is configured as described above, when the double-sided mode or the multiplex mode is selected, the sheet fed from the sheet feeding section is image-formed by the image forming section and further fixed by the fixing section. Then, the sheet is not ejected to the sheet ejecting section immediately, and is fed to the intermediate tray section 21 by the re-feed sheet guiding section.
Be guided to. Then, the re-fed sheets guided to the intermediate tray portion 21 are discharged onto the bottom plate 23, and the leading ends of these sheets are directed to the nip portion A between the re-feed roller 29 and the separation roller 30 along the guide plate 37. The sheets are sequentially stacked so as to form a wedge shape as shown in FIG. At this time, the sheet passes between the bottom plate 32 and the guide plate 37, and the re-feed roller 29 and the separation roller
Even when the sheet advances toward the nip portion A of the sheet 30, the sheet is not caught in the nip portion A of the re-feed roller 32a and the separation roller 30 by coming into contact with the tip 32a of the protruding sheet stopper 32. Since the sheet on the bottom plate 23 can move freely without being held in the nip portion A between the re-feeding roller 29 and the separating roller 30, it is easily width-shifted by the regulating side plates 25, 25 to align both side ends. When a predetermined number of re-feed sheets are aligned and stacked on the bottom plate 23, as shown in FIG.
The excitation of the solenoid 36 is released, and the tip 32a of the sheet stopper 32 is retracted by the tension of the stopper spring 33, and the path of the sheet to the nip portion A between the refeed roller 29 and the separation roller 30 is opened. Therefore, when the half-moon-shaped feed roller 26 starts to rotate, some lower sheets of the sheets S stacked on the bottom plate 23 are guided by the separation roller front guide plate 39 to be sequentially separated from the re-feed roller 29. Transported to the nip A of the roller 30,
Further, these sheets S are provided with a re-feed roller 29 and a separation roller 30
The sheets are separated and fed one by one from the lowest sheet toward the image forming unit in order to form an image again without causing misalignment, skew, or feeding failure.

Next, a partially modified reference example will be described with reference to FIG.

In the above-described embodiment, the guide plate 37 and the front guide plate 39 for the separation roller, which form the sheet guide, form a double guide, but instead of this, as shown in FIG. The leading end 32a 'is at the nip portion A between the re-feeding roller 29 and the separating roller 30, and the leading end portion 39a' of the separating roller front guide plate 39 'constituting the sheet guide in this embodiment.
It is arranged so as to stand upright between them and the guide plate 37 is not provided. In this case, when the leading ends of the stacked sheets are misaligned for some reason, the resistance of the sheet to be re-fed becomes larger than that in the above-described embodiment, and the certainty of re-feeding the sheet is slightly reduced. .

Further, as shown in FIG. 6, a stopper 16 or the like is arranged in the vicinity of the nip portion A'between the re-feeding roller 12 and the separating roller 13, and the leading end of the sheet is brought into contact with the stopper 16 to bring the sheet into the nip portion A '. It is conceivable to prevent the leading edge of the sheet from directly entering. In this case, the ideal shape for re-feeding the sheets S stacked on the intermediate tray 6 is a wedge shape as shown in FIG. 7A, and sheets having such a shape are re-fed. On the other hand, as described above, the stopper 16 is arranged in the vicinity of the nip portion A ', and when the sheet is discharged to the intermediate tray 6, the leading end of the sheet is brought into contact with the stopper 16 and stacked, and there, When the stopper 16 is retracted in order to re-feed the sheet, the stacked state of the sheet S becomes a shape different from the wedge shape as shown in FIG. 7 (b). When the half-moon-shaped feed roller 11 is rotated in this state, the stacked sheets S
In some cases, the lower sheet of the sheet is strongly affected by the resistance of the upper sheet and is difficult to be fed to the nip portion A ′ between the re-feed roller 12 and the separation roller 13.

(G) Effect of the Invention As described above, according to the present invention, the regulating side plate performs the sheet aligning operation in the state where the sheet stopper prevents the leading edge of the sheet from being gripped by the nip portion of the re-feeding unit. Since this is performed, the width direction of the sheets stacked on the intermediate tray can be reliably and accurately aligned.

Further, the first sheet guide disposed upstream of the sheet stopper forms a gap between the first sheet guide and the intermediate tray to limit the amount of the sheet that can advance to the sheet stopper, and the sheet fed by the conveying means is first. Since the leading edge of the sheet is guided so as to be shifted to the upstream side of the sheet stacked on the (wedge-shaped) sheet, the sheet stopper has a limited amount of the lower portion of the sheet whose leading edge is guided in the wedge shape. Is reliably regulated, and when the sheet stopper is released, the lower portion sheet guided in the wedge shape is accurately fed to the refeeding member and refeeded from the jam and the sheet other than the lowest sheet. It is possible to prevent the occurrence of refeed failure.

Further, since the second sheet guide disposed on the downstream side of the sheet stopper makes the leading edge of the sheet into the wedge shape and guides it to the nip portion of the re-feeding member and the separating portion, it is guided by the first sheet guide described above. The limited amount of the sheet that has been conveyed and that is conveyed by opening the sheet stopper can be accurately guided from the lowest position to the nip, and reliable re-feeding can be performed.

Therefore, it is possible to provide a highly accurate image forming apparatus that prevents misalignment of sheets, skewing, feeding failure, and the like.

[Brief description of drawings]

FIG. 1 is a side view showing an intermediate tray portion and a sheet re-feeding portion of an image forming device according to an embodiment of the present invention, and FIG. 2 is an enlarged side view showing the re-feeding of the sheet. FIG. 3 is a side view showing an intermediate tray section and a sheet re-feeding section of a reference example with a partially modified configuration, FIG. 4 is a schematic side view of a conventional image forming apparatus, and FIG. 5 is a re-feeding section thereof. FIG. 6 is a side view showing a case where a stopper is arranged in the re-feed unit,
FIG. 7 is a diagram showing a stacking state of sheets to be re-fed on the intermediate tray. FIG. 7A is a diagram showing an ideal type, and FIG. 7B is a diagram showing a stacking state different from the ideal type. 6,23 …… Intermediate tray (bottom plate), 10,25 …… Regulator side plate, 29
...... Re-feeding member (re-feeding roller), 30 …… Separating member (separating roller), 32, 32 '…… Sheet stopper, 32a, 32a'…
… Sheet contact surface of sheet stopper (tip of sheet stopper), 37 …… First sheet guide (guide plate), 39 ……
Second sheet guide (separation roller front guide plate), 37a ...
… Sheet guide tip (tip of guide plate), 39a …… Sheet guide tip (tip of separation roller front guide), A
...... Nip part, S ... sheet.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication G03G 15/00 510

Claims (1)

[Claims] 1. An intermediate tray on which image-formed sheets are stacked for re-imaging, a re-feeding member that applies a feeding force to the sheets on the intermediate tray from the lowest sheet, and the re-feeding unit. A separating member that separates other sheets from the sheets sent by the feeding member, and a conveying unit that sequentially feeds the sheets from the side opposite to the re-feeding member to the intermediate tray to stack the image-formed sheets, A sheet stopper that displaces a sheet sent to the intermediate tray by the conveying unit between a position where the path to the re-feed member is closed and a position where the sheet is opened, and a leading end of the sheet stacked on the intermediate tray by the sheet stopper. A regulation side plate that moves in a direction toward and away from the side edge of the sheet whose position is regulated to align the stacked sheets, and the re-alignment plate above the intermediate tray. The sheet gradually approaches the intermediate tray toward the feeding member and extends so that its tip is located upstream of the closed position by the sheet stopper, and forms a gap between the intermediate tray and the sheet stopper. A first sheet guide that guides the leading edge of the sheet so as to limit the amount of sheets that can be formed and to be stacked such that the sheet that is fed by the conveying unit is displaced upstream of the previously stacked sheets, and the sheet stopper. A leading end of the sheet is arranged on the downstream side of the closed position, and the leading end of the sheet is guided to the nip between the re-feeding member and the separating member so that the sheets are stacked upstream of the previously stacked sheets. An image forming apparatus comprising: two sheet guides.