JP2505759B2 - Sheet material discharging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention [Field of Industrial Application] The present invention relates to a sheet material discharging device.

More specifically, for example, in an image forming apparatus such as an electronic copying machine having an automatic double-sided copy / automatic multiplex copy function, the sheet material whose image is formed on the first side (front side or back side) is once discharged to an intermediate tray and stocked. When the stocked sheet material is re-fed to the image forming section for image formation on the second side (duplex copying) or for further image formation on the first side (multiple copying) The present invention relates to a sheet material discharging device which is effective and appropriate as a sheet material discharging means.

[Conventional technology]

Recently, the operation of image forming apparatuses such as copying machines has been automated due to systematization, and apparatuses equipped with an automatic double-sided copying mechanism and an automatic multiplex copying mechanism have been developed. And, in constructing the above-mentioned automatic double-sided copying mechanism, etc.,
A stock section generally called an intermediate tray device is used to temporarily stock a desired number of sheets on which the image formation is completed on the first side, and then the sheets are fed again to the image forming section, and the first side image is printed. A method is used in which an image is formed again on the second surface (back surface) or the same surface of the formed sheet, and such a method is extremely effective especially when making a large number of double-sided copies or multiple copies. Has become.

Conventionally, in order to enable double-sided or multiplex copying, the first-side image-formed sheet is passed through a path to store it in an intermediate tray with the image side up during double-sided copy, and the image side down during multiplex copy. A general method is to pass a path to be stored in the intermediate tray, store the sheet in the intermediate tray, and re-feed the sheet to form a double-sided or multiple image.

[Problems to be solved by the invention]

Generally, a sheet having an image formed on the first side thereof easily passes through the fixing device, and thus the heat of the fixing device tends to cause curling, and the sheet may pass through the fixing device after the fixing device (both sides or multiple paths). Cheap. The degree of the curl varies depending on the type of sheet material, the direction of the stitches, the type of toner, the fixing temperature, and the like. If the sheet on which the first surface image is formed and having such a curl is discharged onto the intermediate tray and stacked, a problem easily occurs.

That is, as shown in FIG. 3A, the front surface a and b of the first surface image-formed sheet P ′ discharged and stacked on the intermediate tray 9 by the discharge roller pair 20 face upward. If the curl has a curl, if the curl is considerably large, the leading end a'of the sheet P'which is about to enter the trailing end b of the sheet P already stored in the intermediate tray 9 As a result, a so-called trailing edge pushing phenomenon occurs, and the sheet P that is discharged and stacked before that is not smoothly discharged and stacked, resulting in a stacking failure.

On the contrary, as shown in FIG. 3B, in the case where the front and rear ends a ′ and b ′ of the sheets P ′ stacked on the intermediate tray 9 have downward curl curls directed downward, If the curl is considerably large, the leading edge a ′ of the sheet P ′ that is about to enter the intermediate tray 9 is curled downward and curls up as it is. The curl direction of the sheet on which the first side image is formed is the same as the upper curl and the lower curl in the traveling direction of the sheet shown in FIGS. 3 (a) and 3 (b). There is also an upper curl and a lower curl in the lateral direction of the seat.

That is, as shown in FIG. 4 (a), curls such that both leading ends in the sheet advancing direction face upward, and as shown in FIG. 4 (b), both ends in the sheet advancing direction face downward. Karl is that. When the transverse direction of the sheet in FIG. 4 (a) is curl upward, the so-called front end of the next sheet hits the rear end of the sheet already discharged and stacked on the intermediate tray, as in the case of FIG. 3 (a). A trailing edge pushing phenomenon may occur. When the lateral direction of the sheet in FIG. 4 (b) is curled downward, a so-called rounded edge phenomenon may occur as in the case of FIG. 3 (b).

Usually, the curl of the sheet as shown in FIGS. 3 and 4 varies depending on the type of sheet, the type of toner, the configuration of the fixing device, the fixing temperature, etc., but the curl direction is the upper curl or the lower curl. In the case of an image forming apparatus that is likely to occur in one direction and has an automatic double-sided copying / multiple copying function,
1st to intermediate tray in duplex copy mode and multiple copy mode
Since the way in which the sheet with the image formed on the surface is inserted is different, it is necessary to discharge various curl-like products as shown in FIGS. 3 (a) and (b) or FIGS. 4 (a) and (b) to the intermediate tray. become. As a result, the first-side image-formed sheets on the intermediate tray 9 are apt to be discharged / stacked poorly, and the discharged / stacked sheets in the intermediate tray 9 are re-supplied to the image forming unit for double-sided or multiple copying. When paper is used, paper is not fed, multi-feeding, wrinkles and the like are likely to occur, and the double-sided / multiplexing function is significantly impaired.

Further, the degree of curl also varies depending on the length of the sheets stored in the intermediate tray 9. Therefore, when the third switching guide 21 in FIG. 3 is at the position shown by the solid line, the long sheet material P
(P ') has a re-feeding roller pair 45.
Long sheet materials are more susceptible to curling than short sheet materials because they have to be stored up to 46, making storage difficult.

Various sheet material discharging devices or methods have been devised in order to prevent the defective storage of the sheet material P in the intermediate tray 9 due to the above-described curl. Some of them are explained.

(1) Curling curl by combining an elastic body and a rigid body.

As shown in FIG. 5, an elastic roller 50a such as rubber or urethane foam, and a rigid roller 50b such as POM or metal.
Is fixed and rotated between the shafts of the rollers 50a and 50b so as to form a nip portion, and a sheet P'having an upper curl curl is passed between the rollers 50a and 50b. As a result, the upper curl is corrected and the flat sheet P is obtained.

(2) Seating with a flanged roller.

As shown in FIG. 6, a driven side roller 51a (for example, rubber) having a flange portion 51f is brought into contact with a driven side roller 51b at a certain pressure, and a plurality of roller pairs 51a and 51b are provided between them. By passing the sheet P, a wavy waist is formed in the lateral direction of the sheet. Third by this waist attachment
The curl behavior shown in FIGS. 4A and 4B and FIGS. 4A and 4B is corrected.

However, the curl straightening method or mechanism of the above (1) is effective only for the curl in one direction, and in the case of the curl in the opposite direction, the curl direction is amplified. Therefore, in the case of the example of FIG. 5, the upper curl curse seam acts in the direction of removing the curl, so it is possible to prevent the so-called rear end pushing as described in FIG. 3 (a). When the lower curl curse sheet is introduced between the pair of rollers 50a and 50b, the lower curl curse sheet acts in a direction in which the curl is further increased. The tip is likely to be rounded. As described above, in the image forming apparatus having the double-sided / multi-copy function, the sheets entering the intermediate tray differ in the double-sided copy mode and the multiple-copy mode, and therefore the curl direction is not constant. It is not possible to completely eliminate defective storage of sheets in the intermediate tray.

Further, since the first-side image-formed sheet that enters the intermediate tray exits the fixing device and passes through a path of a certain distance,
The sheets are quite tight by the time they reach the intermediate tray, and decurling is practically difficult with this configuration. It is effective when the sheet is heated to some extent by the heat of the fixing device, but a large nip and pressure are required to remove the curled sheet, which results in a large roller diameter, which in turn enlarges the device. There is a drawback to

Further, although the above-mentioned method (2) for attaching the sheet is relatively effective, the so-called attachment effect works near the exit of the roller pair, but when the sheet is gradually fed out, the attachment is made. The effect of does not work well up to the tip of the sheet, and it returns to the curl direction of the sheet itself.
The so-called trailing edge pressing and tip rounding phenomenon described in (a) and (b) may occur.

To get a sufficient waisting effect up to the tip of the seat,
The flange diameter of the roller should be made larger to increase the waviness generated on the sheet. However, although this gives the effect of stiffening, there are streaks on the sheet due to the edges that contact the sheet as shown in A and B of FIG. A fold will occur.
Due to this, there is a drawback that transfer omission occurs during double-sided copying on the second side or during multiplex copying.

In view of the above, the present invention is directed to an image forming apparatus having a double-sided / multiplex copying function, for example, by eliminating curling when storing the first-side image-formed sheet in the intermediate tray to improve stackability and to achieve stable re-copying. It is an object of the present invention to provide a sheet material discharging device for an intermediate tray that allows paper feeding.

B, Configuration of the Invention [Means for Solving the Problems] A configuration of the present invention for achieving the above object is to provide a plurality of first rollers having elasticity and having a plurality of coaxially arranged flanges on at least one side. A plurality of second rollers forming a nip in cooperation with each of the first rollers, the second roller having a curved surface forming a drum shape on the outer circumference, The curved surface is pressed against the first
The outer peripheral surface of the roller is configured to be deformed, and at least one of the first roller and the second roller is rotationally driven so that the sheet material is introduced and passed between the roller pair and discharged. Sheet material discharging device.

[Action]

By adopting a structure in which a roller made of a foamed member having a flange portion is brought into contact with a roller made of a rigid member having a drum shape so as to form a nip, rotated, and a sheet is conveyed between them. In addition, it is possible to bend and curl the sheet without damaging the sheet, and at the discharge port to the intermediate tray, the storability of the sheet can be significantly improved, and a stable re-feeding function can be guaranteed. . Further, at the discharge port to the outside of the machine, it is possible to reliably carry the sheet to a tray, a sorter, a finisher, or the like.

The outer peripheral surface of the first roller does not come into contact with the edge of the second roller and is pressed against the curved surface to be deformed, so that no streaks or folds are left on the sheet.

〔Example〕

FIG. 1 shows an apparatus according to an embodiment of the present invention, and FIG. 1A is a front view of a plurality of roller pairs, showing a state in which a sheet is interposed between the roller pairs. FIG. 7B is a sectional view taken along the line (b)-(b) of FIG. 7A, and FIG.
It is an enlarged view of the arrow (c) part of a figure.

61a, 61b, ... 61n are first rollers having elasticity made of a foamed material (for example, urethane foam or foamed CR rubber),
It is integrated with the shaft 63. The rollers 61a, 61b ... 61n
Has a roller portion having a width L ₁ and a diameter φD ₁ , and a flange f having a width 1 and a diameter φD ₂ at both ends.

A roller-shaped rigid member having a radius of curvature R, a width L ₂ , and a diameter (at the center) φD ₃ so as to come into contact with the rollers 61a, 61b, ... 61n (for example, POM, metal, hard rubber, etc.) )
The second rollers 62a, 62b, ... 62n are arranged and are integrated with the shaft 64.

Here, both ends of the shaft 63 and the shaft 64 are fixedly supported by bearings (not shown) so as to maintain a constant distance H, and therefore the second roller 62a made of a rigid member as shown in FIG.
.62b ... 62n, the first roller made of foam material
61a ・ 61b ・ ・ ・ 61n is designed to bend under the influence of force.

61n and the second roller 62a
・ 62b ・ ・ ・ 62n roller pairs 61a ・ 62a, 61b ・ 62b
... 61n and 62n are arranged with an appropriate mutual interval in consideration of the sheet size and the like. When the sheet P passes between the pair of rollers, the sheet P is subjected to a supporting action as shown in FIG. Here, the flange portion f of each first roller
Is a foam member, the contact portion B with the sheet P has a flange portion f with the sheet P as shown in FIG. 1 (c).
Because of the rigidity of the sheet, it escapes appropriately, and it is difficult for the sheet P to have streaks or creases. Further, the second rollers 62a, 62b, ... 62n, which are rigid members, are drum-shaped and have a radius of curvature R, so that the contact portion A with the sheet P is streaked as shown in FIG. 1 (c). It is hard to leave a mark. Either one of the shaft 63 and the shaft 64 may be on the drive side, or both may be driven.

Experimental example 1st roller 61a ・ 61b ・ ・ ・ 61n: Width L ₁ = 28mm, Flange width l = 2mm Roller diameter φD ₁ = φ20mm, Flange diameter φD ₂ = 25mm Material: urethane foam, hardness 20 ° 2nd roller 62a ・ 62b ・ ・ ・ 62n: Width L ₂ ＝ 20mm, Diameter (center part) φD ₃ ＝ φ18mm Drum barrel curvature R ＝ 15mm Material: CR rubber, hardness 75 ° Axial distance between shafts 63 and 64: i = 17.5 A good result was obtained when the sheet P was discharged experimentally under the condition of mm or more. According to this, it becomes possible to perform sufficient waisting without leaving a streak mark or a protrusion mark on the sheet P.

Further, as shown in FIG. 1 (b), the sheet P has first rollers 61a, 61b ... 61n, and second rollers 62a, 62b.
Since it passes between the nip between and, the effect of decurling as described above can be obtained.

Further, since the first rollers 61a, 61b, ... 61n have the flange portion f having a diameter φD ₂ larger than the diameter φD _{1 of the} roller portion at both ends thereof, the peripheral speed of the flange portion f naturally depends on that of the roller portion. Since the speed is faster than the peripheral speed, the effect of stiffening the sheet P is further increased due to the difference in peripheral speed, and the sheet P can be pushed out sharply. Therefore, when the sheet is stored in the intermediate tray, the tip of the sheet is recharged. It becomes easy to reach the paper roller pair 46/45 (Fig. 3) and the storability is also improved.

Further, the material of the second rollers 62a, 62b ... 62n is made of a material having a high friction coefficient, for example, CR rubber, so that the sheet P
When the sheet is conveyed, the sheet can be surely conveyed without slipping.

FIG. 2 shows an example of an electrophotographic copying machine having a double-sided copying / multiple copying function.

In the copying machine 1 of this example, a drum-type electrophotographic photosensitive member 10 which is rotationally driven in the direction of the arrow, a charger 2, a document scanning projection optical system 6, a developing device 3 or the same 4, a charger 11, a paper feeding unit. 8, transfer charger 5, sheet conveying means 35 and 36, fixing device 7, charger
12, the cooperation operation of process equipment such as cleaning device 13
By the action, an image corresponding to the original image set on the original table 19 is formed on the surface of the sheet P fed from the paper feeding unit 8.

The paper feeding unit 8 is sent from the manual feed tray 26, the first paper cassette 28, or the second paper cassette 29 toward the transfer unit 5 by the paper feeding rollers 27, 30, or 31. Intermediate transport roller 14
And 43, and after the registration roller 32 synchronizes with the image on the photoconductor by the registration roller 32, the formed image on the surface of the photoconductor 10 is transferred to the surface (first surface) of the transfer unit 5. The image-transferred sheet is separated from the surface of the photoconductor 10, is conveyed by the conveyor belt 35, and is guided by the guide 36 to reach the fixing device 7. The formed image is fixed in the fixing device 7, and the sheet reaches the first switching guide 39.

If you want to make the final copy by only one-sided copying, the 1st guide 39
Is held in a switching posture indicated by a chain double-dashed line, and the sheet passes through the upper side of the guide 39 and is sequentially discharged and stacked on the discharge tray 16 outside the apparatus by the discharge roller pair 15. Or, a sheet sorting device (sorter) provided connected to the paper discharge section of the copying machine 1
It is also installed in other processing devices such as a binding and folding device.

In the double-sided copying mode or the multiplex copying mode, the first guide 39 is held in the switching posture shown by the solid line, and the fixing device 7
The first surface image-formed sheet exiting from the sheet is deflected to the lower passage by the guide 39, is intermediately relayed by the relay roller 40, and is directed to the second switching guide 41.

In the double-sided copy mode, the second guide 41 is held in the switching posture shown by the solid line, and the sheet is a relay roller.
Head to 42 and enter switchback aisle 50. The rear end of the sheet reaches the sensor X position slightly before the intermediate roller 42,
When the sensor X detects that it has passed, the relay roller 42 is immediately driven in reverse by the detection signal, whereby the sheet is fed backward and introduced to the first discharge roller 20.

When the sheet is of a small size, the third switching guide 21 is held in the switching posture indicated by the chain double-dashed line, and the sheet passes from the first discharge roller 20 to the upper side of the guide 21 to reach the second sheet.
The sheets are sequentially discharged and stacked from the discharge roller 21 onto the intermediate tray 9 with the image surface facing upward.

When the sheet is of a large size, the third switching guide 21 is held in the switching posture shown by the solid line, and the sheet passes from the first discharge roller 20 below the guide 21 to the image surface on the intermediate tray 9. They are discharged and loaded in an upward direction.

The first-side image-formed sheet stored in the intermediate tray 9 with the image side facing upward is sent out one by one from the lower side by the re-feeding rollers 45 and 46, and passes through the intermediate roller 47, the same 43, and the registration roller 32. The image is retransmitted to the transfer unit 5, and the image is transferred to the second surface (back surface). The sheet having undergone this image transfer is ejected out of the machine as a double-sided copy along the path of the conveyor belt 35 → guide 36 → fixing device 7 → first guide 37 switched to the posture shown by the chain double-dashed line → ejecting roller 15. It

On the other hand, in the multiple copy mode, the second guide 41 is held in the switching posture indicated by the chain double-dashed line, and the sheet on which the first side image has been formed is guided by the guide 41 from the first discharge roller 20 or the third guide 21. Via the second discharge rollers 22, the sheets are sequentially discharged and stacked on the intermediate tray 9 with the image surface facing downward. Thereafter, as in the case of the double-sided copy mode, the sheets in the outer intermediate tray 9 are re-fed to the transfer section 5, the image is formed on the first side again, and the sheets are ejected to the outside as a multiple copy.

The sheet discharge roller device 61 of the present invention described in FIG.
The numeral 62 is effective and appropriate as the first and second sheet discharge rollers 20 and 22 for discharging the sheet to the intermediate tray 9 of the copying machine.

It is also effective and appropriate as the discharge roller 15 to the outside of the machine. In recent years, with the spread of systemization and automation, a sorter and a finisher (a stapler, a half-folder, a Z-folder, or a stacker) are often attached to an image forming apparatus, if necessary, in addition to the discharge tray 16. The decurling of the sheet has been indispensable for the reliable operation of these devices. The curl causes curling in the sheet ejection tray 16 and the sheets stacked on the tray drop, or the sorter catches and jams the curl at the delivery part at the entrance, and the finisher folds or folds the paper. When Z-folding, if the curl is large, jams and wrinkles are likely to occur. The present invention also has the effect of eliminating such inconvenience.

C. Effect of the Invention As described above, according to the sheet discharging apparatus of the present invention, curling of sheets to be sequentially discharged and stacked is eliminated, stackability is improved, and stable re-feeding is performed. The desired object is often achieved by a device that is effective and suitable as a sheet discharging device for an intermediate tray of an image forming apparatus having a double-sided / multiple copying function.

The outer peripheral surface of the first roller does not come into contact with the edge of the second roller and is pressed against the curved surface to be deformed, so that no streaks or folds are left on the sheet.

[Brief description of drawings]

1 (a) is a front view of a part of the apparatus of one embodiment, FIG. 1 (b) is a sectional view taken along line (b)-(b) of FIG. 1 (a), and FIG. 2 is an enlarged view of the portion indicated by the arrow (c), FIG. 2 is a schematic configuration diagram of an image forming apparatus having a double-sided / multi-copy function, and FIGS. 3 (a) and 3 (b) are sheet curl-like stacking devices. FIGS. 4 (a) and 4 (b) are perspective views showing other curl curling states, FIG. 5 is a sectional view of a conventional curl curling roller means, and FIG. 6 is a conventional sheet. FIG. 61n, 62a, 62b, ..., 62n are first and second rollers forming a sheet discharge roller device, P and P'are sheets, and 9 is an intermediate tray.

Claims (1)

(57) [Claims] 1. A plurality of elastic first rollers arranged coaxially and having a flange on at least one side thereof,
A plurality of second rollers forming a nip in cooperation with each of the first rollers, the second roller having a curved surface forming a drum shape on the outer periphery, It is configured to press the curved surface into contact with each other to deform a portion of the outer peripheral surface of the first roller which is not the flange, and rotationally drives at least one of the first roller and the second roller to form a sheet material between the pair of rollers. A sheet material discharging device, characterized in that the sheet material is introduced and discharged.