JP2005001772A - Sheet conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive sheet conveying device with a small number of parts, capable of realizing miniaturization. <P>SOLUTION: The sheet conveying device is provided with a plurality of driving rollers 21; a first driven roller 22 abutted on a part of the plurality of driving rollers at either one side of an upstream side and a downstream side in a sheet conveying direction to be driven; and a second driven roller 23 abutted on the remainder of the plurality of driving rollers at the other side of the upstream side and the downstream side in the sheet conveying direction to be driven. The device is constituted such that circumferential speed at the abutting part of the driving roller and the driven roller is made different on the upstream side and the downstream side in the sheet conveying direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus that is used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine and conveys a sheet such as a recording sheet or a document.
[0002]
[Prior art]
In general, an image forming apparatus includes a sheet conveying device for conveying a sheet such as a recording sheet or a document. For example, in an automatic document feeder that conveys a document as a sheet, a large number of documents (hereinafter referred to as a document) (Called a document bundle) are separated one by one and fed (conveyed) to an image reading apparatus such as a scanner apparatus.
[0003]
In such a sheet conveying apparatus used for an automatic document feeder, when a document is conveyed with a driving roller and a driven roller as a pair of rollers, two roller pairs are arranged in the document conveying direction, and these roller pairs are arranged. There is a document that conveys a document with a difference in peripheral speed (that is, decelerates or accelerates) (for example, the driving roller diameter of one roller pair is set to be larger than the driving roller diameter of the other roller pair). Or increase the pressure contact force in one roller pair).
[0004]
Further, when the recording paper is transported from the transfer position where the toner image is transferred to the fixing position where the toner image is fixed, a pair of rollers is arranged in the paper transport direction, and a circumferential speed difference is provided between the pair of rollers so that the recording paper is Is controlled (see Patent Document 1).
[0005]
[Patent Document 1]
JP 2002-287560 A (paragraphs (0026) to (0036), FIGS. 1 and 2)
[0006]
[Problems to be solved by the invention]
By the way, when two roller pairs are arranged in the sheet conveying direction as described above and the sheet is conveyed with a difference in peripheral speed between the roller pairs, the two roller pairs are arranged in the sheet conveying direction. There is a problem that not only the number of parts increases, but also the arrangement space is inevitably increased, and as a result, the sheet conveying apparatus itself is increased in size.
[0007]
Furthermore, if the driving roller diameter in one roller pair is larger than the driving roller diameter in the other roller pair, the other driving roller diameter needs to be reduced, and if the roller diameter becomes smaller, the size management becomes difficult.
[0008]
An object of the present invention is to provide an inexpensive and small sheet conveying apparatus.
[0009]
[Means for Solving the Problems]
According to the present invention, there is provided a sheet conveying apparatus that is used when conveying a sheet in a predetermined direction, wherein the plurality of driving rollers and the plurality of drives on either the upstream side or the downstream side in the predetermined direction are provided. A first driven roller that is driven by being in contact with a part of the rollers, and a second driven roller that is driven by being in contact with the rest of the plurality of drive rollers on the other of the upstream side and the downstream side in the predetermined direction. And different peripheral speeds at the contact portions between the driving roller and the first and second driven rollers on the upstream side and the downstream side in the predetermined direction. A sheet conveying apparatus is obtained in which the sheet is conveyed in the predetermined direction by a second driven roller.
[0010]
In this way, if the peripheral speeds at the contact portions of the driving roller and the first and second driven rollers are made different between the upstream side and the downstream side in the sheet conveying direction, the number of parts can be reduced, and By reducing the size of the sheet conveying apparatus itself, the sheet feeding amount can be made different between the upstream side and the downstream side in the sheet conveying direction.
[0011]
For example, the plurality of drive rollers are attached to the same drive shaft, and a part of the plurality of drive rollers has a diameter different from that of the remaining drive rollers.
[0012]
In this way, if a plurality of drive rollers are attached to the same drive shaft and a part of the plurality of drive rollers has a different diameter, the upstream side in the sheet conveying direction is simple. The sheet feed amount can be made different between the downstream side and the downstream side.
[0013]
In addition, it is preferable that at least three of the drive rollers are provided so that the drive rollers located on both sides along the drive shaft have different diameters from the remaining drive rollers.
[0014]
In this way, if at least three drive rollers are provided, and the drive rollers located on both sides along the drive shaft are made to have different diameters from the remaining drive rollers, a simple configuration upstream of the sheet conveying direction can be achieved. Not only can the sheet feeding amount be different between the side and the downstream side, but also the sheet conveyance is stable.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example.
[0016]
First, referring to FIG. 1, here, a sheet conveying apparatus used in an automatic document feeder as an example of a sheet conveying apparatus will be described as an example. However, the present invention can be similarly applied to a recording sheet conveying apparatus. .
[0017]
The illustrated automatic document feeder 10 is used together with an image forming apparatus (for example, a copying machine), and is disposed on the upper surface side of the main body of the image forming apparatus (not shown). The automatic document feeder 10 includes a document feed tray 11 and a document feed mechanism 12, and a document bundle is placed on the document feed tray 11. The document feeding mechanism 12 separates the documents one by one from the document bundle placed on the document feeding tray 11 and conveys the document to the image reading position GP by the sheet conveying device 20.
[0018]
Then, after the image on the original is read at the image reading position GP, the original is sent to the discharge roller pair 31 by the sheet conveying device 20, and is lowered to the lower side of the original feed tray 11 by the discharge roller pair 31. The document is discharged to the arranged document discharge tray 13.
[0019]
Although not shown, in the image forming apparatus, an image carrier such as a photosensitive drum is exposed based on image data obtained by reading a document, and an electrostatic latent image is formed on the image carrier. . Then, after the electrostatic latent image is developed by the developing device, the toner image on the image carrier is transferred to the recording paper, the toner image on the recording paper is fixed, and the paper is discharged onto a paper discharge tray.
[0020]
As shown in FIG. 1, the document feeding mechanism 12 is disposed on the rear side (downstream in the document transport direction) of the document feeding tray 11, and the document feeding mechanism 12 includes a document feeding roller unit (hereinafter simply referred to as “sheet feeding roller unit”). The document feed roller unit 14 includes a roller housing 14a, a pickup roller (pickup roller) 14b, a feed roller (feed roller) 14c, and a separation pad 14d. ing. The pickup roller 14b and the feed roller 14c are housed in a roller housing 14a, and the separation pad 14d is provided on the base side of the document feeding mechanism 12 so as to face the feed roller 14c.
[0021]
When reading the original, the pickup roller 14b comes into contact with the upper surface of the original bundle, and the original is picked up by the pickup roller 14b. Then, only one of the documents picked up by the pickup roller 14b by the separation pad 14d is separated and sent to the downstream side by the feed roller 14c.
[0022]
As shown in the drawing, a sheet conveying device 20 is disposed on the downstream side of the feed roller 14c. The sheet conveying device 20 includes a large-diameter driving roller 21 and small-diameter driven rollers 22 and 23. The peripheral surfaces of the driven rollers 22 and 23 are in contact with the peripheral surface of the drive roller 21.
[0023]
In the illustrated example, the driven roller 22 (for example, the first driven roller) is arranged on the upstream side of the document reading position GP, and the driven roller 23 (for example, the second driven roller) is on the downstream side of the document reading position GP. Is arranged. The drive roller 21 has a resin-made cylindrical roller frame 21a and a rubber body 21b, which is a high friction member formed on the peripheral surface of the roller frame 21a. 23 is made of resin.
[0024]
The drive shaft 24 is inserted into the center of the roller frame 21a of the drive roller 21. When the drive shaft 24 is rotationally driven by a drive source such as a motor, the drive roller 21 rotates. The driven rollers 22 and 23 are rotatably supported by support shafts 25 and 26 whose both ends are fixed to the casing of the document feeding mechanism 12, and are rotated and driven as the driving roller 21 rotates. The original is inserted into the nip portion (contact portion) between the roller 21 and the driven rollers 22 and 23, and the original is conveyed.
[0025]
Here, referring to FIG. 2, in the illustrated example, the drive roller 21 is attached to the drive shaft 24 at a predetermined interval (in the following description, the left side in the figure). The first to third driving rollers will be referred to in order from the beginning). As shown in FIG. 2, the second driving roller (the driving roller located in the middle) 21 has a larger diameter than the first and third driving rollers 21, and the first and third driving rollers 21 have the same diameter. It is.
[0026]
The document is transported in the direction indicated by the thick arrow in the figure, and a pair of driven rollers 22 are disposed on the upstream side of the transport direction, that is, on the support shaft body 25, and are in contact with the first and third drive rollers 21, respectively. Yes. On the other hand, one driven roller 23 is disposed on the downstream side in the transport direction, that is, on the support shaft body 26, and is in contact with the second drive roller 21.
[0027]
Now, when the drive shaft 24 is rotationally driven by a motor or the like, the first to third drive rollers 21 rotate in the directions indicated by the broken line arrows, and the driven rollers 22 and 23 are accompanied by the directions indicated by the one-dot chain line arrows. Rotate to. Since the diameter of the second drive roller 21 is larger than the diameters of the first and third drive rollers 21, the peripheral speed of the second drive roller 21 is the first because of being attached to the same drive shaft 24. And it is faster than the peripheral speed of the second drive roller 21.
[0028]
In other words, at the nip portion between the first and third drive rollers 21 and the driven roller 22 located on the upstream side in the transport direction, the nip between the second drive roller 21 and the driven roller 23 located on the downstream side in the transport direction. The peripheral speed is slower than the peripheral speed in the section, and a peripheral speed difference occurs between the upstream side in the transport direction and the downstream side in the transport direction.
[0029]
Accordingly, the document feed amount is small at the nip portion located upstream in the transport direction, and the document feed amount is large at the downstream side in the transport direction. As a result, the document is pulled and transported downstream in the transport direction. Will be. As a result, at the document reading position GP, the document can be conveyed and satisfactorily read without sagging.
[0030]
In this way, the driving roller 21 and the driven rollers 22 and 23 have different peripheral speeds in the nip portion between the upstream side in the transport direction and the downstream side in the transport direction (that is, have a peripheral speed difference). )), It is not necessary to arrange two roller pairs composed of a driving roller and a driven roller in the document conveying direction, the number of parts of the sheet conveying device is reduced, and the size is reduced, and a peripheral speed difference is provided. Will be able to.
[0031]
When the sheet is conveyed in the direction opposite to the direction indicated by the thick arrow, the sheet can be conveyed loosely. For example, the recording paper can be loosened at the registration position arranged on the upstream side of the image carrier. become.
[0032]
In the example shown in FIG. 1, the distance from the document setting position AP to the position BP of the timing SW (switch for detecting the driving timing of the driving roller 21) 32 is 84 mm, and the first and third distances from the position BP. The distance from the driving roller 21 to the driven roller 22 to the nip position CP is 10 mm, the distance from the nip position CP to the image reading position GP is 40 mm, and the distance from the image reading position GP to the position DP of the paper discharge roller pair 31 is 80 mm. is there.
[0033]
In the above-described example, the case where three drive rollers 21 are provided has been described. However, it is sufficient that a plurality of drive rollers 21 are provided, and at least one of the plurality of drive rollers 21 has a diameter different from that of the other drive rollers. The driven roller having a larger diameter is brought into contact with one of the upstream side and the downstream side in the conveying direction, and the driven roller having a smaller diameter is set on the other side in the upstream side and the downstream side in the conveying direction. If the circumferential speed is made different between the upstream side and the downstream side in the conveyance direction, it is possible to reduce the number of parts of the sheet conveying apparatus and to reduce the size and to provide a circumferential speed difference. It will be possible.
[0034]
In addition, from the stability of document conveyance, it is provided with three or more driving rollers, for example, the driving rollers located on both sides are made different in diameter from the driving rollers located on both sides, It is desirable that the driven roller is brought into contact with one of the upstream side and the downstream side in the conveying direction and the driven roller is brought into contact with the other driving roller on the other side in the upstream and downstream sides in the conveying direction.
[0035]
Referring to FIG. 3, in the illustrated example, the same components as those shown in FIG. As illustrated, auxiliary rollers 33 are rotatably attached to the support shafts 25 and 26, respectively. The auxiliary roller 33 in contact with the second drive roller 21 on the upstream side in the transport direction (indicated by a solid arrow) has a diameter larger than that of the auxiliary roller 33 in contact with the first and third drive rollers 21 on the downstream side in the transport direction. Thus, the conveyance force on the upstream side and the downstream side in the conveyance direction is adjusted.
[0036]
Specifically, the auxiliary roller 33 is used to stabilize sheet conveyance and has a function as a kind of guide member. For this reason, it is desirable that the conveyance force be close to zero at each nip portion between the driving roller 21 and the auxiliary roller 33 (that is, no nip pressure is applied to the auxiliary roller 33). Therefore, a resin material (eg, bomb) having a weak grip force is used as the auxiliary roller 33, and a rubber elastic material (eg, EPDM (ethylene propylene diene) having a strong grip force is used as the driving roller 21 and the driven rollers 22 and 23. (That is, a nip pressure is applied to the driving roller 21 and the driven rollers 22 and 23). Further, the axial length (width) of the auxiliary roller 33 is equal to that of the driving roller 21, and the auxiliary roller 33 and the driving roller 21 are brought into contact with each other in the length direction (longitudinal direction). If contact is made, the sheet conveyance becomes more stable. The driven rollers 22 and 23 are not necessarily formed of a rubber elastic material such as EPDM. For example, the driven rollers 22 and 23 are formed of a resin material such as a bomb, and the driven rollers 22 and 23 are formed by a biasing member. And the nip pressure with the drive roller 21 may be set.
[0037]
【The invention's effect】
As described above, according to the present invention, a plurality of drive rollers and a part of the drive rollers are in contact with a part of the plurality of drive rollers on either the upstream side or the downstream side in the sheet conveying direction. A first driven roller that is driven, and a second driven roller that is driven in contact with the rest of the plurality of driving rollers on the other side of the upstream and downstream sides in the sheet conveying direction, Since the peripheral speed at the contact portion between the driving roller and the first and second driven rollers is made different on the downstream side, the number of parts is reduced, and the sheet conveying device itself is downsized to the upstream in the sheet conveying direction. There is an effect that the sheet feeding amount can be made different between the side and the downstream side.
[0038]
In the present invention, a plurality of drive rollers are attached to the same drive shaft, and the diameters of some of the plurality of drive rollers are made different from those of the remaining drive rollers. There is an effect that the sheet feeding amount can be made different between the downstream side and the downstream side.
[0039]
In the present invention, at least three drive rollers are provided, and the drive rollers located on both sides along the drive shaft are made to have different diameters from the remaining drive rollers. In addition to making it possible to make the sheet feed amount different between the downstream side and the downstream side, there is an effect that the conveyance of the sheet is stabilized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an automatic document feeder in which an example of a sheet conveying device according to the present invention is used.
FIG. 2 is a perspective view for explaining an example of a sheet conveying apparatus according to the present invention.
FIG. 3 is a perspective view for explaining another example of the sheet conveying apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Document automatic feeding apparatus 11 Document feeding tray 12 Document feeding mechanism 20 Sheet conveying apparatus 21 Drive roller 22, 23 Drive roller 24 Drive shaft 25, 26 Support shaft body

Claims (3)

A sheet conveying apparatus used when conveying a sheet in a predetermined direction,
A plurality of drive rollers;
A first driven roller that is driven in contact with a part of the plurality of driving rollers on either the upstream side or the downstream side in the predetermined direction;
A second driven roller that is driven in contact with the rest of the plurality of drive rollers on the other of the upstream side and the downstream side in the predetermined direction;
The drive roller and the first and second driven rollers are made different in peripheral speed at the contact portion between the drive roller and the first and second driven rollers on the upstream side and the downstream side in the predetermined direction. The sheet conveying apparatus according to claim 1, wherein the sheet is conveyed in the predetermined direction. The plurality of drive rollers are attached to the same drive shaft,
The sheet conveying apparatus according to claim 1, wherein a part of the plurality of driving rollers has a diameter different from that of the remaining driving rollers. There are at least three drive rollers,
The sheet conveying apparatus according to claim 2, wherein the driving rollers located on both sides along the driving shaft have different diameters from the remaining driving rollers.

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