JP4351947B2 - Paper transport device - Google Patents

Description

  The present invention is used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine that uses an electrophotographic process, and conveys recording paper from a paper feeding device such as a paper feeding cassette to an image forming unit that performs image formation. The present invention relates to a paper transport apparatus.

  In general, in an image forming apparatus, a sheet is conveyed from a sheet feeding device such as a sheet cassette containing recording sheets (hereinafter simply referred to as a sheet) to an image forming unit, and a toner image (visible) is formed on the sheet in the image forming unit. After the image is transferred, the toner image is fixed on the paper by the fixing unit.

  A paper transport device is provided for transporting the paper from the paper feed cassette to the image forming unit. The paper transport device includes a registration roller, a registration roller, and a paper feed cassette disposed in the preceding stage of the image forming unit. It is equipped with a conveyance roller disposed between them, and the sheet fed from the paper feed cassette by the conveyance roller is fed to the registration roller. The registration roller once holds the leading edge of the sheet, and then matches the toner image transfer timing, The paper is sent to the image forming unit.

  The transport rollers described above are deteriorated due to wear, paper dust adhesion, and the like, and the transport force decreases with time. For this reason, a poor arrival may occur in which the sheet does not arrive at the registration roller within a specified time due to slipping or the like. Further, when the conveying force of the conveying roller is reduced, the so-called stiff paper does not bend after hitting the registration roller, and does not bend but passes over the registration roller (through the nip portion of the registration roller). As a result, the toner image transfer In some cases, deviation may occur.

  In order to prevent such inconveniences, there is one in which the amount of bending of the sheet is detected, and the amount of bending is maintained normally to perform a reliable paper feeding operation. Here, it is positioned in front of the registration roller. An elastic member having one end fixed to the upstream side of the registration roller is arranged so as to be deformed along the bending of the paper, and the other end of this elastic member is supported in the bending amount detector so as to be able to advance and retract. The detector detects the amount of bending based on the amount of movement of the other end of the elastic member (see Patent Document 1).

  Further, in order to adjust the amount of paper deflection, while the registration roller is feeding out the paper, the paper feed motor is rotated so that the deflection is maintained, and the intermediate transport roller rotates to assist the paper. Here, the sheet conveyance speed by the intermediate conveyance roller is changed according to the preset sheet type and size so that the sheet bending amount is not excessive and the sheet is not bent. (See Patent Document 2).

Japanese Laid-Open Patent Publication No. 9-235042 (pages 4 to 6, FIGS. 1 to 4) JP 2000-108482 (pages 6 to 30, FIGS. 1 to 30)

  The characteristics of the paper change due to changes in the surrounding environment. For example, in a high humidity environment, the moisture content of the paper increases, so the stiffness (elastic force) of the paper decreases and the amount of deflection also changes. Furthermore, as described above, the amount of deflection also changes due to a change with time of the conveying force of the conveying roller.

  By the way, the sheet is conveyed to the registration roller through the conveyance path. In other words, a guide member for guiding the sheet is arranged in the conveyance path, but the sheet held by the registration roller is bent. If the amount changes, for example, if the amount of deflection of the sheet becomes excessive, a sheet rubbing sound is generated by hitting the sheet or the guide. Although the rubbing sound varies depending on the amount of bending of the paper, the user may feel uncomfortable if the rubbing sound is large.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a paper transport device that can reduce the rubbing noise generated in front of a registration roller regardless of the amount of paper deflection.

Therefore, in order to solve this problem, the present invention provides:
An image forming unit that forms a toner image; and a paper feeding device that stores recording paper conveyed to the image forming unit, and is used in an image forming apparatus that transfers the toner image onto the recording paper. In a paper transport device for transporting the recording paper from a paper feed device to the image forming unit,
A registration roller unit that temporarily holds the leading edge of the recording sheet conveyed from the sheet feeding device via an intermediate conveying roller unit and sends the recording sheet to the image forming unit in accordance with the transfer timing of the toner image;
Arranged on the sheet conveyance surface up to the intermediate conveyance roller section upstream of the registration roller section, extends along the recording sheet conveyance direction, and rotates in the recording sheet conveyance direction in synchronization with the rotation of the registration roller section. A belt rotating body that
The belt rotating body is arranged to be swingable with a rotation shaft of the roller section of the belt rotating body extending in parallel with a rotation shaft of the registration roller section as a swing fulcrum. .

  In the present invention, for example, the rotating body includes a first roller unit, a second roller unit disposed on the upstream side in the recording paper conveyance direction at a predetermined interval from the first roller unit, A belt body stretched between the first and second roller portions, the first roller portion is driven to rotate, and the rotation shaft of the first roller portion serves as the swing fulcrum. . In addition, a support body that supports the rotation axis of the second roller portion so as to be movable in a direction intersecting the recording paper surface is provided. For example, the support body has a width of the recording paper. A pair of support portions arranged at predetermined intervals in the direction, and each of the support portions is formed with an elongated hole extending in a direction intersecting the recording paper surface, The rotation shaft of the two roller portions is inserted.

  As described above, the sheet conveying apparatus of the present invention arranges the rotating body that extends along the recording sheet conveying direction and follows the bending of the recording sheet on the upstream side of the registration roller unit, and synchronizes with the rotation of the registration roller unit. Since the rotating body is rotated in the recording paper conveyance direction, when the recording paper hits the registration roller portion and the recording paper is bent, the rotating body follows the bending of the recording paper and comes into contact with the recording paper. When the registration roller unit is driven and the recording paper is sent to the image forming unit, the rotating body rotates in synchronization with the rotation of the registration roller unit, and the recording paper is also conveyed by the rotating body during conveyance of the recording paper. Thus, there is an effect that no rubbing sound of the recording paper is generated.

  In the present invention, the rotating body is arranged so as to be able to swing with a fulcrum defined on the registration roller portion side and extending parallel to the rotation axis of the registration roller portion as a swing fulcrum. There is an effect that it can follow.

  In the present invention, since the rotating body has a belt body stretched between the first and second roller portions, when the registration roller portion is driven to rotate, the recording paper that contacts the belt body is removed. There is an effect that it can be easily transported without generating a rubbing sound.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  With reference to FIG. 1, an example of a sheet conveying apparatus 10 according to the present invention is used in an image forming apparatus 20, for example. The illustrated image forming apparatus 20 includes an apparatus housing 21. In the apparatus housing 21, a sheet feeding device 22 including a sheet feeding cassette, an image forming unit 23, a fixing unit 24, and a sheet reversing unit 25. Is disposed, and the sheet conveying device 10 is disposed between the sheet feeding device 22 and the image forming unit 23. The sheet conveying device 10 forms a sheet fed from the sheet feeding device 22 as described later. Transport to unit 23.

  The sheet conveying apparatus 10 includes a plurality of intermediate conveying roller portions 11 and 12 and a registration roller pair 13, and these intermediate conveying roller portions 11 and 12 and the registration roller pair 13 are arranged along the sheet conveying path P1. ing. The intermediate conveyance roller unit 11 includes intermediate conveyance rollers 11a and 11b, and the intermediate conveyance roller unit 12 includes intermediate conveyance rollers 12a to 12c. The intermediate conveyance roller 12b contacts the intermediate conveyance rollers 12a and 12c. ing.

  A sheet detection sensor 31 is disposed between the intermediate conveyance roller unit 11 and the intermediate conveyance roller unit 12, and similarly, a sheet detection sensor 32 is disposed between the intermediate conveyance roller unit 12 and the registration roller pair 13. ing. Further, the sheet conveying apparatus 10 may be provided with an intermediate conveying roller section 14, and the intermediate conveying roller section 14 may transfer sheets set on a manual feed tray 26 provided on the front side of the apparatus casing 21 to a sheet conveying path. The sheet is sent to the sheet conveyance path P1 via P2. A paper detection sensor 33 is disposed in the paper transport path P2. A rotating belt body (not shown in FIG. 1), which will be described later, is disposed on the paper conveyance path P1 between the intermediate conveyance roller unit 12 and the registration roller pair 13.

  Here, when image formation is performed by the image forming apparatus 20, the paper is picked up by the pickup roller 22 a in the paper feeding device 22 and sent out to the paper transport device 10 by the feed roller 22 b and the retard roller 22 c (paper feeding device 22). Is provided with a paper detection sensor 22d). In the paper transport device 10, the front end of the paper is temporarily held by the registration roller pair 13, and the paper is sent from the registration roller pair 13 to the image forming unit 23 in accordance with the transfer timing.

  In FIG. 1, only the photosensitive drum 23a and the transfer roller 23b are shown in the image forming unit 23. However, the image forming unit 23 includes a charger, an exposure device, a developing device, a cleaning unit, and the like. The toner image formed on the photosensitive drum 23a is transferred onto the paper by the transfer roller 23b and sent out to the paper transport path P3. The paper is then sent to the fixing unit 24 where the toner image on the paper is fixed.

  During single-sided printing, the paper is sent to the paper discharge path P4 via the conveying roller pair 27a, and discharged to the paper discharge tray 28 formed on the upper surface of the apparatus housing 21 by the paper discharge roller pair 27b and 27c. The A paper detection sensor 34 is provided between the fixing unit 24 and the transport roller pair 27a, and a paper detection sensor 35 is disposed at the paper discharge port.

  On the other hand, during double-sided printing, the paper is sent to the paper reversing unit 25 via the transport roller pair 27a. The paper reversing unit 25 is provided with a paper reversing roller pair 25a. The paper reversing roller pair 25a temporarily feeds the paper to the reversing path P5. When the front end of the paper is detected by the paper detection sensor 36, the paper reversing roller pair 25a. Is reversed, and the sheet is sent out to the reverse conveyance path P6. Note that paper detection sensors 37 and 38 are disposed in the reverse conveyance path P6.

  Then, the paper is transported by the transport roller pairs 25b to 25d and is sent to the paper transport device 10, that is, the paper transport path P1. Thereafter, as described above, the toner image is transferred to the back side of the sheet by the image forming unit 23, passes through the fixing unit 24, and is discharged to the discharge tray 28 via the discharge path P 4.

  Here, referring to FIG. 2, as described above, the belt rotating body 41 is disposed between the intermediate conveyance roller portion 12 and the registration roller pair 13, and this belt rotating body 41 is located on the registration roller pair 13 side. The first roller portion 41a disposed on the intermediate conveyance roller portion 12 and the second roller portion 41b disposed on the intermediate conveyance roller portion 12 side are made of rubber and are made of rubber between the first and second roller portions 41a and 41b. A belt body 41c is stretched. And the 1st roller part 41a is rotationally driven so that it may mention later, and the belt body 41c rotates as shown by the solid line arrow in FIG.

  3A and 3B, FIG. 3A is a perspective view showing the registration roller pair 13 and the belt rotating body 41 from above, and FIG. 3B is a registration roller pair 13 and belt. It is a figure which shows a rotary body from the lower side. The registration roller pair 13 includes an upper registration roller 13a and a lower registration roller 13b. As shown in FIG. 3A, the rotation shaft 13c of the upper registration roller 13a is rotatably supported by a guide body 42 (this A part of the sheet transport path P1 is defined by the guide body 42).

  The guide body 42 has first and second guide portions 43 and 44, and the first and second guide portions 43 and 44 are provided with flange portions 43a and 44a, respectively. The rotating shaft 13c is inserted into the holes formed in the flange portions 43a and 44a, and the upper registration roller 13a is rotatably supported by the flange portions 43a and 44a. And the gear 45 is mounted | worn with the one end side of the rotating shaft 13c.

  In addition, the first guide portion 43 is formed with a pair of protrusions 46a and 46b protruding upward at a predetermined interval along the sheet conveyance direction. Is formed with a pair of protrusions 47a and 47b protruding upward at a predetermined interval along the sheet conveying direction. The protrusions 46a and 47a face each other, and the protrusions 46b and 47b face each other (here, the protrusions 46b and 47b constitute a support).

  The rotating shaft 41d of the roller portion 41a is inserted through a hole formed in the protrusions 46a and 47a, and is rotatably supported between the protrusions 46a and 47a. As shown in an enlarged view in FIG. 3C, a long hole 48 extending upward is formed in the protrusion 46 b, and the long hole 48 extends to the guide portion 43. Similarly, a long hole 48 is formed in the protrusion 47 b, and the long hole 48 extends to the guide portion 44.

  The rotating shaft 41e of the roller portion 41b is inserted into the elongated hole 48 and is rotatably held between the protrusions 46b and 47b. The rotating shaft 41e is inserted into the elongated hole 48 as shown in FIG. It can move along. That is, the belt rotating body 41 can swing around the rotation shaft 41d as a swing center.

  As shown in FIG. 3A, the rotating shaft 41d is longer than the rotating shaft 41e, and one end of the rotating shaft 41d passes through a hole formed in the flange portion 44a, and a gear 49 is mounted. As shown in FIG. 3B, a gear 50 is attached to one end side of the rotation shaft 13 d of the lower registration roller 13 b, and the gear 45 and the gear 49 are engaged with the gear 50. Although not shown in FIG. 3B, the rotating shaft 13d is rotatably supported by the apparatus housing 11.

  In the illustrated example, when the rotary shaft 13d is driven to rotate by a motor (not shown) (the gear 50 is driven by the motor), the lower registration roller 13b rotates and is connected to the rotary shaft 41d connected via the gear 49. Driving force is transmitted from the gear 50, and the roller portion 41a rotates. Further, the driving force is transmitted from the gear 50 to the gear 45, whereby the driving force is transmitted to the rotating shaft 13c, and the upper registration roller 13a rotates. That is, the belt rotating body 41 rotates in synchronization with the rotation of the registration roller pair 13 (in other words, in synchronization with the registration roller pair 13 by the rotation mechanism constituted by the gear 45, the gear 49, and the gear 50 and the rotation shaft. The belt rotating body 41 rotates).

  As described above, the leading edge of the sheet fed from the sheet feeding device 22 is temporarily held by the registration roller pair 13. At this time, the sheet is bent by the conveying force of the intermediate conveying roller unit 12. Become. A belt rotating body 41 is disposed on the upstream side of the registration roller pair 13, and the belt rotating body 41 swings about the rotation shaft 41d as a swing center according to the amount of bending of the paper. That is, as indicated by the broken line in FIG. 2, when the sheet is bent, the belt rotating body 41 swings upward about the rotation shaft 41d. Then, the belt body 41c comes into contact with the sheet by the bending of the sheet (in other words, the belt rotating body 41 swings following the bending of the sheet).

  Thereafter, when the registration roller pair 13 is driven and the sheet is fed to the image forming unit 23, the belt rotating body 41 rotates in synchronization with the rotation of the registration roller pair 13, so that the belt rotation is performed during sheet conveyance. The paper is also transported by the body 41, so that no paper rubbing noise is generated.

  A rotating body that extends along the recording sheet conveyance direction and follows the bending of the recording sheet is disposed upstream of the registration roller section, and the rotation body rotates in the recording sheet conveyance direction in synchronization with the rotation of the registration roller section. Therefore, when the recording paper is bent against the registration roller portion, the rotating body follows the bending of the recording paper and comes into contact with the recording paper, and the registration roller portion is driven to bring the recording paper into the image forming unit. When the sheet is fed, the rotating member rotates in synchronization with the rotation of the registration roller unit, and the rubbing sound of the recording sheet does not occur. As a result, the sheet conveying device in the image forming apparatus such as a copying machine, a printer, or a facsimile machine Applicable to.

1 is a diagram schematically illustrating an example of an image forming apparatus in which a paper conveyance device according to the present invention is used. It is a figure which shows roughly an example of the belt rotary body used with the paper conveying apparatus by this invention. FIG. 3 is a diagram illustrating the configuration of the belt rotating body illustrated in FIG. 2 together with a pair of registration rollers, where (a) is a perspective view seen from the upper side, (b) is a perspective view seen from the lower side, and (c) is a protrusion shown in (a). The figure which expands and shows a body, (d) is a figure which shows the movement range of a rotating shaft when a belt rotary body rock | fluctuates.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Paper conveying apparatus 20 Image forming apparatus 21 Apparatus housing 22 Paper feeding apparatus 23 Image forming unit 24 Fixing unit 25 Paper reversing unit 11, 12 Intermediate conveyance roller part 13 Registration roller pair 41 Belt rotating body 41a, 41b Roller part 41c Belt body 42 Guide bodies 43a, 44a Flange portions 46a, 46b, 47a, 47b Projections

Claims (4)

An image forming unit that forms a toner image; and a paper feeding device that stores recording paper conveyed to the image forming unit, and is used in an image forming apparatus that transfers the toner image onto the recording paper. In a paper transport device for transporting the recording paper from a paper feed device to the image forming unit,
A registration roller unit that temporarily holds the leading edge of the recording sheet conveyed from the sheet feeding device via an intermediate conveying roller unit and sends the recording sheet to the image forming unit in accordance with the transfer timing of the toner image;
Arranged on the sheet conveyance surface up to the intermediate conveyance roller section upstream of the registration roller section, extends along the recording sheet conveyance direction, and rotates in the recording sheet conveyance direction in synchronization with the rotation of the registration roller section. A belt rotating body that
The sheet conveying device, wherein the belt rotating body is disposed so as to be swingable with a rotation shaft of the roller section of the belt rotating body extending in parallel with a rotation shaft of the registration roller section as a swing fulcrum. . The belt rotating body includes a first roller unit, a second roller unit disposed upstream of the first roller unit at a predetermined interval in the recording paper transport direction, the first and the A belt body stretched between the second roller portions,
The sheet conveying apparatus according to claim 1, wherein the first roller unit is driven to rotate, and a rotation shaft of the first roller unit serves as the swing fulcrum.   3. The paper transporting apparatus according to claim 2, further comprising a support body that supports the rotation shaft of the second roller portion so as to be movable in a direction intersecting the recording paper surface. The support has a pair of support portions arranged at a predetermined interval in the width direction of the recording paper,
4. A long hole extending in a direction intersecting the recording sheet surface is formed in each of the support portions, and the rotation shaft of the second roller portion is inserted into the long hole. Paper transport device.

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