JP2004189368A - Paper discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper discharge device capable of preventing a stripe-like image defect by rubbing or slippage caused when discharging a paper. <P>SOLUTION: This paper discharge device comprises a rotating shaft 6 rotating in a predetermined direction, a plurality of discharge rolls 1 pivotally fixed to the rotating shaft and rotating with the rotating shaft, and a plurality of rotatable opposed rolls 2 which make contact with any one of the discharge rolls to form a nip part 8. The rotating shaft 6 is provided with a plurality of driven rolls 5 larger in diameter than the discharge roll 1, which are supported to be rotatable relative to the rotating shaft 1 independently from the discharge rolls 1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paper discharge device used for an image forming apparatus such as a copying machine, a printer, a facsimile, and a printing machine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine, a printer, a facsimile, and a printing machine of an electrophotographic type, an ink type, and the like includes a paper discharge device that discharges a sheet on which an image is formed to a paper discharge tray or the like.
[0003]
FIG. 1 is a diagram illustrating an example of a discharge device in an electrophotographic image forming apparatus.
[0004]
As shown in FIG. 1, the paper discharge device forms a nip portion 8 by a plurality of rotating discharge rolls 1 and a plurality of opposing rolls 2 driven to face the plurality of discharge rolls 1, and an image is formed. The paper 4 formed and sent at a predetermined moving speed is configured to be discharged to the discharge tray 3 with the nip portion 8 interposed therebetween.
[0005]
FIG. 2 is a diagram illustrating a discharge roll and a counter roll that discharge a sheet by sandwiching the sheet in a nip portion.
[0006]
As shown in FIG. 2, the discharge roll 1 is composed of a roll part 1a that is mounted on the rotating shaft 6, and a flange part 1b that has a larger diameter than the roll part 1a and is provided at both ends. At a position facing the discharge roll 1, a counter roll 2 that forms a roll portion 1 a and a nip portion 8 and that rotates freely following the discharge roll 1 is disposed. The paper 4 is sandwiched between the nip portions 8 and sent out according to the rotation of the discharge roll 1. Further, since the diameter of the flange portion 1b is larger than the diameter of the roll portion 1a, the paper 4 comes into contact with the outer periphery 1c of the flange portion and the roll portion 1a, and is forcibly bent in the width direction crossing the paper feed direction. To avoid curling in the paper feed direction when is sent.
[0007]
At this time, in order to kick the rear end of the sheet so that the rear end of the sheet is not left in the sheet discharge port, there is a method of providing a convex shape on the flange portion. However, this method has a problem in that the paper has a mark of a convex shape, and the convex shape causes the opposing roll to move up and down, thereby causing abnormal noise.
[0008]
Therefore, there is a configuration in which an auxiliary member having a larger diameter than the discharge roll and provided with a plurality of grooves on the outer periphery is arranged coaxially with the discharge roll at a position shifted from the nip portion (see Patent Document 1).
[0009]
However, if the auxiliary member having a different outer diameter from the discharge roll or the flange portion is rotated integrally with the discharge roll, the peripheral speed at the nip portion and the outer periphery of the flange portion in contact with the paper is different. Adjust the speed while slipping or rubbing at the part. Therefore, when a fixed image formed by, for example, toner is discharged from the paper discharging device, a streak-like image defect occurs. In addition, if the degree of slip on the outer periphery of the roll portion and the outer periphery of the flange portion, which are plurally attached in the rotation axis direction, is different, skew occurs in the discharged paper.
[0010]
FIG. 3 is a diagram illustrating a mode in which streak-like image defects have occurred in a fixed image of a sheet.
[0011]
In the paper discharge device shown in FIG. 3, four discharge rolls 1 each including a roll portion 1a and flange portions 1b provided at both ends of the roll portion 1a are arranged at equal intervals on a rotating shaft 6, and each roll portion 1a has: The opposing roll 2 abuts to form a nip portion 8. The paper 4 on which the fixed image has been formed and which has been discharged to the discharge tray 3 through each nip portion 8 of the paper discharge device has a streak 100 in the paper feed direction. The streaks 100 on the paper are composed of a thick streak 101 blurred at the center and sharp thin streaks 102 on both sides of the streak, and four sets are formed. The four sets of streaks 100 correspond to the arrangement positions of the four discharge rolls 1 of the paper discharge device. Among the streaks 100 of each set, the thick streaks 101 at the center coincide with the position of the nip portion 8, and the thin streaks 102 on both sides coincide with the position of the outer periphery of the flange portion 1b.
[0012]
FIG. 4 is an enlarged view of a streak generated on a sheet. FIG. 4A is a thin streak on both sides, and FIG. 4B is a thick streak at the center.
[0013]
As shown in FIG. 4A, the thin streaks 101 on both sides are streaks that continuously occur in the sheet feeding direction, and are determined to be caused by rubbing. In addition, as shown in FIG. 4B, the central thick streak 102 is a streak that occurs intermittently in a direction intersecting with the sheet feeding direction, and is determined to be caused by slip.
[0014]
[Patent Document 1]
JP 2001-106412 A (paragraph numbers 0024 to 0034, FIGS. 3, 4, and 7)
[0015]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and has as its object to provide a paper discharge device that can prevent streak-like image defects due to rubbing or slippage that occurs when paper is discharged.
[0016]
[Means for Solving the Problems]
A paper ejection device of the present invention that achieves the above object has a rotating shaft that rotates in a predetermined direction, a plurality of ejection rolls that are attached to the rotating shaft and rotates together with the rotating shaft, and each of the plurality of ejection rolls. A discharge device that includes a plurality of rotatable opposed rolls that form a nip portion by contacting any of the discharge rolls, and discharges the conveyed paper with the nip portion interposed therebetween;
The rotary shaft is provided with a plurality of driven rolls having a diameter larger than that of the discharge rolls, which are rotatably supported on the rotary shaft independently of the plurality of discharge rolls.
[0017]
As described above, since there are provided a plurality of driven rolls having a diameter larger than that of the discharge roll, which freely rotate independently of the discharge roll, an image defect due to rubbing or slipping of the paper passing through the nip portion is not generated. It can be smoothly discharged to a predetermined discharge tray.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the paper ejection device of the present invention will be described.
(1st Embodiment)
FIG. 5 is a diagram illustrating an example of an image forming apparatus in which the sheet discharging device according to the first embodiment is used.
[0019]
The image forming apparatus shown in FIG. 5 includes a document reading apparatus 10 that automatically reads a document and obtains image data, an image forming unit 11 that forms a toner image based on the read image data or image data input from the outside. Four paper cassettes 12 for storing paper of a predetermined size, a paper transport path 13 for extracting paper from the paper cassette 12 and transporting the paper to the image forming unit 11, a manual tray 14 for manually feeding paper to the image forming unit 11, and A fixing device 15 for fixing the toner image transferred onto the sheet from the image forming unit 11 onto the sheet to form an image; an image conveying path 16 for conveying the sheet on which the image is formed; And a discharge tray 3 for storing the discharged paper. The discharge tray 3 stores the discharged paper. A solar radiation 18, and a duplex unit 19 for forming images on both sides sent to the image forming unit by reversing the sheet on which the image on one side is formed.
[0020]
The toner image formed by the image forming unit is transferred onto a sheet conveyed from the sheet cassette 12 or the manual feed tray 14 on the sheet conveying path 13 and fixed by the fixing device 15 to form an image. Then, the sheet on which the image is formed is conveyed on the image conveying path 16, discharged from the sheet discharging device 20, and stored in the discharge tray 3. When an image is formed on both sides, the sheet on which the image is formed on one side is sent to the image forming unit 11 after the sheet is inverted by the duplex unit 19. When a plurality of sheets on which images are formed are sorted and stored in respective sheet trays, the sheets are conveyed on the image conveying path 16 and sent to the finisher 18, and after being sorted, the respective discharge devices 20 discharge the respective sheets. It is discharged to the tray 3.
[0021]
FIG. 6 is a diagram illustrating a discharge roll and a counter roll that discharge a sheet by sandwiching the sheet in the nip portion.
[0022]
As shown in FIG. 6, the discharge roll 1 is axially mounted on the rotating shaft 6, and a flange having a larger diameter than the discharge roll 1 is provided on each side of the discharge roll 1 (the driven roll of the present invention). 5) is pivotally supported. Then, an opposing roll 2 that is mounted on a rotating shaft different from the discharge roll 1 abuts on the discharge roll 1 with the sheet 4 interposed therebetween, thereby forming a nip portion 8.
[0023]
The discharge roll 1 rotates integrally with the rotating shaft 6. On the other hand, since the flange 5 of the present embodiment is supported by the same rotating shaft 6 as the discharge roll 1 via a bearing 5a that rotates freely by bearing, the flange 5 can be freely and independently of the discharge roll 1. Rotate. When the paper 4 on which the image is formed is sandwiched between the nip portions 8, the paper 4 is driven by the respective discharge rolls 1 rotating at the peripheral speed S and moves together with the rotating shaft 6. On the other hand, since the flange portion 5 is configured to rotate freely with almost no resistance regardless of the rotation of each discharge roll 1, the flange portion 5 rotates at a peripheral speed substantially equal to the moving speed of the paper 4. Therefore, the moving speed of the paper 4 passing through the nip portion 8 is substantially equal to the peripheral speed S of the discharge roll 1, and the peripheral speed of the flange 5 is substantially equal to the moving speed of the paper 4.
[0024]
As described above, since the peripheral speed S of the discharge roll 1, the moving speed of the sheet 4, and the peripheral speed of the flange 5 are substantially equal to each other, the discharge rubbing and slipping do not occur with the movement of the sheet 4.
[0025]
7 and 8 are views showing the paper discharge device of the present embodiment, FIG. 7 is a plan view, and FIG. 8 is a front view.
[0026]
As shown in FIGS. 7 and 8, the sheet discharging device includes a rotating shaft 6, four discharging rolls 1 having the same outer diameter, and the bearings bearings. Four flanges, each having the same outer diameter, are disposed on both sides of each of the discharge rolls 1 and are rotatably supported independently of the discharge rolls 1 by being rotatably supported by the rotation shaft 6 via the bearings. 5 and four opposing rolls 2 that abut on each discharge roll 1 and form a nip 8 with the paper 4 interposed therebetween. The four discharge rolls 1 are configured to rotate integrally with the rotating shaft 6, and have a uniform and the same circumferential length at each position in the rotating shaft direction. When the rotating shaft 6 rotates at a predetermined speed, each discharging roll 1 is rotated. The roll 1 rotates at the same peripheral speed S. Accordingly, the paper 4 sandwiched between the nip portions 8 formed by the discharge roll 1 and the opposing roll 2 is fed at a moving speed S in a predetermined paper feed direction A.
[0027]
At this time, since the flanges 5 provided on both sides of each of the discharge rolls 1 are configured to rotate with almost no resistance by the bearings independently of the discharge rolls 1, the flanges 5 follow the moving speed S of the paper 4. Rotate.
[0028]
Further, since the outer diameter of each flange 5 is larger than the outer diameter of each discharge roll 1, the paper sandwiched between the nip portions 8 is bent to the valley side at the four nip portions 8, and Since the paper is bent at three places on the peak side between each other, the paper has rigidity in the feeding direction A and can be prevented from curling.
[0029]
As described above, the sheet 4 passing through the sheet discharging device is sent through the respective nip portions 8 at the same moving speed S, and receives no frictional force at the contacting flange outer periphery 5b, so that the nip portion 8 and the flange outer periphery 5b Both move without rubbing or slipping. Further, since the sheet has rigidity in the feeding direction A, the sheet is smoothly discharged to the discharge tray.
[0030]
Here, the discharge device of the present embodiment is provided with four discharge rolls 1 and is attached to the rotating shaft 6 at equal intervals. However, the number of discharge rolls 1 need not be limited to four. It is not always necessary to arrange them at equal intervals. However, in order to prevent the skew of the paper 4, it is preferable that the paper 4 is disposed so that a force acts evenly on the paper 4 sandwiched between the nip portions 8. The outer diameter of each flange 5 is larger than that of the discharge roll 1 and has the same diameter. However, it is not always necessary to make the same diameter.
[0031]
Although the discharge roll of the present embodiment is formed so that the circumferential length in the rotation axis direction is uniform, it is not necessarily required to be uniform, as long as the outer diameter in each nip portion is the same.
[0032]
Next, a second embodiment will be described.
(Second embodiment)
In the first embodiment, independently rotating flanges are provided on both sides of the discharge roll, whereas the second embodiment replaces the flanges with each other between the discharge rolls and a plurality of discharge rolls. It differs in that it has a driven roll that rotates independently of the discharge roll on the outside. However, since other points are common, only the differences will be described.
[0033]
FIG. 9 is a diagram illustrating the front of the sheet discharging device.
[0034]
As shown in FIG. 9, the sheet discharging device includes a rotating shaft 6, four discharging rollers 1 having the same outer diameter, and the bearings not shown in the figure. The same outer diameter is disposed between the discharge rolls 1 and outside the discharge rolls 1, and is rotatably supported independently of the discharge rolls 1 by being supported by the rotating shaft 6 via the bearings. And five opposing rolls 2 that abut on each of the discharge rolls 1 and form a nip portion 8 with the paper 4 interposed therebetween. The four discharge rolls 1 rotate integrally with the rotation shaft 6 and have the same circumference at each position in the rotation axis direction. Therefore, when the rotation shaft 6 rotates at a predetermined speed, each discharge roll 1 becomes the same. At a peripheral speed S of. Therefore, the paper 4 sandwiched between the nip portions 8 formed by the discharge roll 1 and the opposing roll 2 is fed at a moving speed S in a predetermined paper feed direction.
[0035]
At this time, since the five driven rolls 7 are configured to rotate with almost no resistance by bearings independently of the respective discharge rolls 1, the five driven rolls 7 are driven at the peripheral speed S in accordance with the moving speed S of the paper 4. Rotate.
[0036]
Further, since the outer diameter of each driven roll 7 is larger than the outer diameter of each discharge roll 1, the paper 4 sandwiched between the nip portions 8 is bent at four nip portions 8 into a valley shape. Since the five driven rolls 7 are bent into a mountain shape, rigidity is generated in the sheet feeding direction. Therefore, it is possible to avoid curling of the sheet.
[0037]
As described above, the paper 4 passing through the paper discharge device is fed at the same speed in each nip portion 8, and the driven roll 7 that comes into contact with the mountain portion of the paper 4 bent into a mountain shape moves the paper 4. Since it rotates freely according to the speed S, it does not receive frictional force. Therefore, the nip portion 8 with which the sheet 4 contacts and the sheet 4 with which the driven roll 7 contacts move without rubbing or slipping. Further, since the paper has rigidity, the paper is smoothly discharged to the discharge tray.
[0038]
Here, the discharge device of the present embodiment is provided with four discharge rolls 1 and is attached to the rotating shaft 6 at equal intervals. However, the number of discharge rolls 1 need not be limited to four. It is not always necessary to arrange them at equal intervals. However, in order to prevent the skew of the paper 4, it is preferable that the paper 4 is disposed so that a force acts evenly on the paper 4 sandwiched between the nip portions 8. Further, the outer diameter of each driven roll 7 is larger than that of the discharge roll 1 and has the same diameter. However, the driven roll 7 does not necessarily have to have the same diameter.
[0039]
【The invention's effect】
As described above, according to the paper ejection device of the present invention, since the paper ejection device is provided with the flange portion that rotates freely and independently of the ejection roll or the driven roll, the paper is rubbed or slipped when the paper is ejected. Image defects can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a discharge device in an electrophotographic image forming apparatus.
FIG. 2 is a diagram illustrating a discharge roll and a counter roll that discharge a sheet in a nip portion and discharge the sheet.
FIG. 3 is a diagram illustrating a mode in which streak-like image defects have occurred in a fixed image of a sheet.
FIG. 4 is an enlarged view of a streak generated on a sheet.
FIG. 5 is a diagram illustrating an example of an image forming apparatus in which the paper discharge device according to the first embodiment is used.
FIG. 6 is a diagram illustrating a discharge roll and a counter roll that discharge a sheet in a nip portion and discharge the sheet.
FIG. 7 is a diagram illustrating a paper discharge device according to the present embodiment.
FIG. 8 is a diagram illustrating a paper discharge device according to the present embodiment.
FIG. 9 is a diagram illustrating the front of the paper discharge device.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 discharge roll 1 a roll portion 1 b flange portion 1 c flange portion outer periphery 2 opposed roll 3 discharge tray 4 paper 5 flange 5 a bearing 5 b flange outer periphery 6 rotation shaft 7 driven roll 8 nip 10 document reading device 11 image forming unit 12 paper cassette 13 paper Conveying path 14 Manual feed tray 15 Fixing device 16 Image conveying path 18 Finisher 19 Double-sided unit 20 Paper discharge device

Claims (5)

A rotation shaft that rotates in a predetermined direction, a plurality of discharge rolls that are mounted on the rotation shaft and rotate together with the rotation shaft, and forms a nip portion by contacting any one of the plurality of discharge rolls. A plurality of rotatable opposing rolls, and discharges the conveyed paper sandwiched between the nip portions.
The discharge shaft is provided with a plurality of driven rolls having a larger diameter than the discharge rolls and rotatably supported on the rotary shaft independently of the plurality of discharge rolls. Paper equipment. 2. The sheet discharging device according to claim 1, wherein the plurality of driven rolls are each supported by the rotating shaft one at a time between two adjacent discharge rolls. 3. 2. The sheet discharging device according to claim 1, wherein the plurality of driven rollers are each supported on the rotating shaft, one on each side of each discharging roll. 3. 2. The discharging device according to claim 1, wherein the plurality of driven rollers are rotatably supported by the rotating shaft via a bearing, and rotate freely independently of the discharging roller. 3. Paper equipment. The paper discharge device according to claim 1, wherein the plurality of discharge rolls have outer diameters equal to each other.

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