JP2016166065A - Sheet conveyance device and image formation apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of sheet jam and abnormal sound in a sheet conveyance device in which a portion of a curved sheet conveyance path is openable and an image formation apparatus having the same.SOLUTION: A double-sided conveyance unit comprises an inversion part 8A, an inner side guide part 801, a body side guide rib 802, and an opening/closing unit side guide rib 811. The conveyance direction of a sheet S is inverted from the lower side toward the upper side in the inversion part 8A. The opening/closing unit side guide rib 811 is arranged so as to form a level difference between the body side guide rib 802 and itself. The opening/closing unit side guide rib 811 is moved so as to separate from the inner side guide part 801 and the body side guide rib 802 to cause the inversion part 8A to be opened to the outside. The opening/closing unit side guide rib 811 is provided with a second rib part 811B inclined downward toward the body side guide rib 802.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet, and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image on a sheet is known as an apparatus equipped with a sheet conveying apparatus that conveys a sheet. Patent Documents 1 and 2 disclose an image forming apparatus provided with a sheet conveying apparatus including a curved sheet conveying path.

JP 2009-173362 A JP 2009-202987 A

  When a sheet jam occurs in the curved sheet conveyance path, a part of the sheet conveyance path is opened to the outside by the opening / closing cover in order to improve the removability of the sheet. In this case, there is a problem that sheet clogging or abnormal noise is likely to occur near the boundary between the main body portion of the sheet conveying apparatus and the opening / closing cover.

  The present invention has been made in order to solve the above-described problems, and in a sheet conveying apparatus capable of opening a part of a curved sheet conveying path and an image forming apparatus including the sheet conveying apparatus, sheet jamming and abnormal noise are provided. The purpose is to prevent the occurrence of

  A sheet conveying apparatus according to an aspect of the present invention includes a main body unit, an opening / closing member that can be opened / closed with respect to the main body unit, an extension between the main body unit and the opening / closing member, and a sheet facing downward. A sheet conveyance path including a curved reversing portion that is reversed and conveyed upward after being conveyed; a curved first guide portion that is fixed to the main body unit and forms one side surface of the reversing portion; A curved second guide portion that is disposed so as to face the first guide portion, forms a downstream side in the sheet conveyance direction on the other side surface of the reversing portion, and guides the sheet upward. The first guide portion is fixed to the opening / closing member so as to face the first guide portion, and is disposed higher than the second guide portion so as to form a step along the transport direction with the second guide portion. ,Previous A third guide portion that forms an upstream side in the conveyance direction of the sheet among the other side surface of the reversing portion, and the third guide portion is along the first guide portion on the upstream side in the conveyance direction. The upstream guide portion is connected downstream of the upstream guide portion in the transport direction so as to form a bent portion between the upstream guide portion and the upstream guide portion, and toward the second guide portion. A downstream guide portion inclined downward, and the downstream end portion in the transport direction of the downstream guide portion of the third guide portion with respect to the upstream end portion in the transport direction of the second guide portion. And facing each other at a predetermined interval.

  According to this configuration, the opening / closing member having the third guide portion is opened / closed with respect to the main body unit having the first guide portion and the second guide portion, thereby opening the sheet conveyance path. For this reason, even when the sheet is jammed in the sheet conveyance path, the sheet is easily removed. Further, a step is formed between the third guide portion and the second guide portion such that the third guide portion is higher. For this reason, it is suppressed that the front-end | tip part of the sheet | seat conveyed in a sheet | seat conveyance path enters into the clearance gap between a 3rd guide part and a 2nd guide part. Further, since the third guide portion is provided with the downstream guide portion that is inclined downward, it is prevented that the rear end portion of the sheet is strongly hit against the second guide portion after being detached from the third guide portion. . As a result, the generation of a hitting sound on the rear end side of the sheet is suppressed.

  In the above configuration, it is preferable that the second guide portion and the third guide portion are a plurality of ribs arranged at intervals in the sheet width direction intersecting the transport direction.

  According to this configuration, the occurrence of sheet jamming and tapping noise is suppressed while the sliding load between the second guide portion and the third guide portion and the sheet is reduced.

  In the above configuration, it is preferable that the downstream guide portion of the third guide portion has a concave curved surface toward the sheet surface of the sheet conveyed through the sheet conveyance path.

  According to this configuration, the rear end portion of the sheet is guided more smoothly from the third guide portion toward the second guide portion. For this reason, generation | occurrence | production of a tapping sound is suppressed further.

  In the above configuration, it is preferable that the opening / closing member is opened / closed with respect to the main body unit by being rotated around a fulcrum portion disposed below the reversing portion.

  According to this configuration, the sheet conveyance path can be opened as the opening / closing member rotates.

  In the above configuration, it is preferable that the opening / closing member is opened / closed with respect to the main body unit by slidingly moving in a horizontal direction.

  According to this configuration, the sheet conveyance path can be opened as the opening / closing member slides.

  An image forming apparatus according to another aspect of the present invention includes an image forming unit that forms an image on a sheet and the sheet conveying apparatus described above.

  According to this configuration, an image forming apparatus in which occurrence of sheet jamming and tapping noise is suppressed is provided.

  In the above configuration, it is preferable that the sheet conveying device is a double-sided conveyance unit that conveys the sheet, on which an image is formed on one sheet surface in the image forming unit, toward the image forming unit again.

  According to this configuration, even when an image is formed on one sheet surface and a sheet that is easily curled is conveyed toward the image forming unit again, occurrence of sheet jamming and tapping noise is suppressed.

  According to the present invention, in a sheet conveyance device that can open a part of a curved sheet conveyance path and an image forming apparatus including the sheet conveyance device, occurrence of sheet jamming and abnormal noise is suppressed.

1 is a cross-sectional view showing an internal structure of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing of the sheet conveying apparatus which concerns on one Embodiment of this invention. It is an expanded sectional view of the sheet conveying apparatus concerning one embodiment of the present invention. It is an expanded sectional view of the sheet conveying apparatus concerning one embodiment of the present invention. It is an expanded sectional view of the sheet conveying apparatus concerning one embodiment of the present invention. It is an expanded sectional view of the sheet conveying apparatus concerning one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. Here, as the image forming apparatus 1, a multi-function machine having a printer function and a copying function is illustrated, but the image forming apparatus may be a printer, a copier, or a facsimile machine.

<Description of Image Forming Apparatus>
The image forming apparatus 1 includes an apparatus main body 10 having a substantially rectangular parallelepiped housing structure, and an automatic document feeder 20 disposed on the apparatus main body 10. In the apparatus main body 10, a reading unit 25 that optically reads a document image to be copied, an image forming unit 30 that forms a toner image on a sheet, a fixing unit 60 that fixes the toner image on a sheet, and image formation A sheet feeding unit 40 that stores sheets conveyed to the unit 30, and a conveyance path 50 that conveys the sheet from the sheet feeding unit 40 or the sheet feeding tray 46 to the discharge space 10S via the image forming unit 30 and the fixing unit 60. , Is housed. The sheet S discharged to the discharge space 10S is stacked on the paper discharge unit 101.

  An automatic document feeder (ADF) 20 automatically feeds a document sheet to be copied toward a predetermined document reading position in the apparatus body 10. On the other hand, when the user manually places the document sheet on a predetermined document reading position, the ADF 20 is opened upward. The reading unit 25 optically reads an image of a document sheet automatically fed from the ADF 20 on the upper surface of the apparatus main body 10 or a manually placed document sheet.

  The image forming unit 30 generates a full-color toner image and transfers it onto the sheet to form an image on the sheet. Yellow (Y), magenta (M), cyan ( An image forming unit 32 including four units 32Y, 32M, 32C, and 32Bk that form toner images of C) and black (Bk), and an intermediate transfer unit 33 disposed adjacent to the image forming unit 32. And a toner replenishing section 34 disposed on the intermediate transfer unit 33.

  Each of the image forming units 32Y, 32M, 32C, and 32Bk includes a photosensitive drum 321 and a charger 322, an exposure device 323, a developing device 324, a primary transfer roller 325, and a cleaning device disposed around the photosensitive drum 321. 326.

  The photosensitive drum 321 rotates about its axis, and an electrostatic latent image and a toner image are formed on its peripheral surface. The charger 322 uniformly charges the surface of the photosensitive drum 321. The exposure device 323 includes a laser light source and optical system devices such as a mirror and a lens, and forms an electrostatic latent image by irradiating the peripheral surface of the photosensitive drum 321 with light based on image data of a document image. .

  The developing device 324 supplies toner to the peripheral surface of the photosensitive drum 321 in order to develop the electrostatic latent image formed on the photosensitive drum 321. The primary transfer roller 325 primarily transfers the toner image on the photosensitive drum 321 onto the intermediate transfer belt 331. The cleaning device 326 cleans the peripheral surface of the photosensitive drum 321 after the toner image is transferred.

  The intermediate transfer unit 33 includes an intermediate transfer belt 331, a belt driving roller 332, and a driven roller 333. On the outer peripheral surface of the intermediate transfer belt 331, toner images are transferred from a plurality of photosensitive drums 321 to be overlapped at the same location. The intermediate transfer belt 331 is rotated counterclockwise in FIG.

  A secondary transfer roller 35 is disposed to face the peripheral surface of the belt driving roller 332. The nip portion between the belt driving roller 332 and the secondary transfer roller 35 is a secondary transfer portion that transfers a full-color toner image overcoated on the intermediate transfer belt 331 onto a sheet.

  The toner replenishing section 34 includes a yellow toner container 34Y, a magenta toner container 34M, a cyan toner container 34C, and a black toner container 34Bk. The developing devices of the image forming units 32Y, 32M, 32C, and 32Bk corresponding to the respective colors. To 324, the toner of each color is supplied from the discharge screw 341 through a supply path (not shown).

  The paper feed unit 40 includes two-stage paper feed cassettes 40A and 40B that accommodate sheets S subjected to image forming processing. These paper feed cassettes 40A and 40B can be pulled out from the front of the apparatus body 10 toward the front.

  The sheet feeding cassette 40A (40B) includes a sheet storage portion 41 that stores a sheet bundle formed by stacking sheets S, and a lift plate 42 that lifts the sheet bundle for feeding. A pickup roller 43 and a roller pair of a paper feed roller 44 and a retard roller 45 are arranged on the upper right side of the paper feed cassette 40A (40B). By driving the pickup roller 43 and the paper feed roller 44, the uppermost sheet S of the sheet bundle in the paper feed cassette 40A is fed out one by one and carried into the upstream end of the transport path 50.

  The conveyance path 50 is printed on one side when performing double-sided printing on the sheet S and a main conveyance path 50A that conveys the sheet S from the paper feeding unit 40 to the exit of the fixing unit 60 via the image forming unit 30. A double-sided conveyance path 50B for returning the sheet to the image forming unit 30 and an upper discharge path 50C and a lower discharge path 50D for directing the sheet S from the downstream end of the main conveyance path 50A to the discharge space 10S are included.

  A registration roller pair 51 is disposed on the upstream side of the main transfer path 50A from the secondary transfer portion 35A. The sheet S is temporarily stopped by the stopped registration roller pair 51, and skew correction is performed. After that, the registration roller pair 51 is rotationally driven by a drive motor (not shown) at a predetermined timing for image transfer, whereby the sheet S is sent out to the secondary transfer roller 35.

  The fixing unit 60 is an induction heating type fixing device that performs a fixing process for fixing the toner image on the sheet S, and has a fixing nip portion formed therein. As the sheet S passes through the fixing nip portion, the toner image transferred to the sheet S is fixed to the sheet.

  A switching guide (not shown) is swingably provided in the main conveyance path 50A above the fixing unit 60. When the switching guide is swung in one posture, the sheet S is carried into the lower discharge path 50D from the main conveyance path 50A. Then, the sheet S is discharged to the paper discharge unit 101 by the first discharge roller pair 7 </ b> A including the first discharge roller 71 and the first driven roller 72.

  On the other hand, when the switching guide is swung to another posture, the sheet S is carried into the upper discharge path 50C from the main conveyance path 50A. Then, the sheet S is discharged to the paper discharge unit 101 by the second discharge roller pair 7 </ b> B including the second discharge roller 73 and the second driven roller 74. When a paper discharge tray (not shown) is mounted above the discharge unit 101, the sheet S is discharged to the paper discharge tray by the second discharge roller pair 7B.

  Further, the image forming apparatus 1 includes a duplex conveying unit 8 (sheet conveying device). As shown in FIG. 1, the double-sided conveyance unit 8 is provided at the right end of the apparatus main body 10 and includes the above-described double-sided conveyance path 50 </ b> B (sheet conveyance path). When double-sided printing is performed on the sheet S, the leading end of the sheet S on which an image is formed on one surface is exposed to the discharge space 10S from the upper discharge path 50C, and the second discharge roller pair 7B. The rotation direction is reversed and the sheet S is switched back. Then, the trailing edge of the sheet S that has stopped near the boundary between the upper discharge path 50C and the double-sided conveyance path 50B is carried into the double-sided conveyance path 50B as a new leading edge.

  FIG. 2 is an enlarged cross-sectional view of the duplex conveying unit 8 according to the present embodiment. 3 to 6 are enlarged cross-sectional views in which a part of the duplex conveying unit 8 is enlarged. Referring to FIG. 2, the duplex conveyance unit 8 includes a conveyance guide unit 80 (main body unit) and an opening / closing unit 81 (an opening / closing member). The image forming apparatus also includes a first transport roller pair 82, a second transport roller pair 83, and a third transport roller pair 84.

  The conveyance guide unit 80 is a unit disposed in the apparatus main body 10. As shown in FIG. 2, the conveyance guide unit 80 defines a part of the double-side conveyance path 50B and the main conveyance path 50A. One roller of the secondary transfer roller 35 and the registration roller pair 51 described above is rotatably supported by the conveyance guide unit 80. The opening / closing unit 81 is a unit arranged on the right side of the transport guide unit 80 and constitutes a part of the right side surface portion 10 </ b> R of the apparatus main body 10. The opening / closing unit 81 includes an opening / closing fulcrum 81S (fulcrum part). The opening / closing fulcrum 81 </ b> S is a fulcrum provided at the lower end of the opening / closing unit 81. The opening / closing unit 81 is rotatable about the opening / closing fulcrum 81S in the direction of the arrow DS in FIG. When the opening / closing unit 81 is opened, the double-sided conveyance path 50 </ b> B is opened to the outside of the apparatus main body 10. The opening / closing fulcrum 81S is disposed below the reversing portion 8A (FIG. 2) described later. Further, the conveyance guide unit 80 is rotatable with respect to the apparatus main body 10 around a fulcrum (not shown) arranged on the lower end side. As described above, when the opening / closing unit 81 is opened, the double-sided conveyance path 50B is opened, and in this state, when the conveyance guide unit 80 is further rotated, the main conveyance path 50A is opened to the outside of the apparatus main body 10. The

  The above-described double-sided conveyance path 50 </ b> B extends between the conveyance guide unit 80 and the opening / closing unit 81. The double-sided conveyance path 50B has a predetermined width in the thickness direction of the sheet S, like the other conveyance paths. The sheet S carried into the double-sided conveyance path 50B from the upper discharge path 50C is conveyed downward and then reversed and conveyed upward. Thereafter, the sheet S reaches the registration roller pair 51 and is conveyed again to the secondary transfer unit of the image forming unit 30.

  A reversing portion 8A is formed at the lower end of the double-sided conveyance path 50B. The reversing unit 8A is a curved conveyance path in which the conveyance direction of the sheet S is reversed from below to above. The first conveyance roller pair 82 is a roller pair disposed at the upper end portion (upstream end portion in the sheet conveyance direction) of the double-side conveyance path 50B. One of the first transport roller pair 82 is rotatably supported by the opening / closing unit 81, and the other of the first transport roller pair 82 is rotatably supported by the fixing unit 60.

  The 2nd conveyance roller pair 83 is a roller pair arrange | positioned in the approximate center part of the up-down direction of the double-sided conveyance path 50B. The second transport roller pair 83 is disposed at substantially the same height as the intermediate transfer unit 33. One of the second transport roller pair 83 is rotatably supported by the opening / closing unit 81, and the other of the second transport roller pair 83 is rotatably supported by the transport guide unit 80. Similarly, the 3rd conveyance roller pair 84 is a lower end part of the double-sided conveyance path 50B, and is a roller pair arrange | positioned in the vicinity of the entrance of the inversion part 8A. One of the third transport roller pair 84 is rotatably supported by the opening / closing unit 81, and the other of the third transport roller pair 84 is rotatably supported by the transport guide unit 80.

  The conveyance guide unit 80 includes an inner guide part 801 (first guide part) and a main body side guide rib 802 (second guide part).

  The inner guide portion 801 is a curved guide surface fixed to the conveyance guide unit 80. The inner guide portion 801 defines the upper surface portion (one side surface) of the reversing portion 8A. The inner guide portion 801 has a substantially arc shape that is convex downward. The inner guide part 801 includes an arcuate vertex 801T.

  The main body side guide rib 802 is a guide part disposed below the inner guide part 801. The main body side guide rib 802 is fixed to the apparatus main body 10 so as to face the inner guide portion 801. The main body side guide rib 802 guides the sheet S toward the upper registration roller pair 51. In the present embodiment, the main body side guide rib 802 is composed of a plurality of ribs arranged at intervals in the sheet width direction (front-rear direction, direction orthogonal to the paper surface of FIG. 2). The main body side guide rib 802 defines the downstream side in the sheet conveying direction of the lower surface portion (the other side surface) of the reversing portion 8A. The main body side guide rib 802 has a curved shape having a substantially arc shape, and the upstream end portion in the transport direction of the main body side guide rib 802 extends further to the upstream side in the transport direction than the vertex 801T of the inner guide portion 801. The upstream side portion of the main body side guide rib 802 in the sheet conveying direction is disposed below the inner guide portion 801 with a first interval.

  The opening / closing unit 81 includes a guide base 810 and an opening / closing unit side guide rib 811 (third guide portion). The guide base 810 is a guide portion fixed to the opening / closing unit 81 so as to face the inner guide portion 801. The open / close unit side guide ribs 811 are a plurality of ribs that are provided upright from the guide base 810 and are spaced apart from each other in the sheet width direction.

  The opening / closing unit side guide rib 811 is arranged on the upstream side of the main body side guide rib 802 in the sheet conveying direction so as to form a step along the sheet conveying direction with the main body side guide rib 802. That is, the opening / closing unit side guide rib 811 is disposed higher than the main body side guide rib 802 by being disposed below the inner guide portion 801 with a second interval smaller than the first interval. The open / close unit side guide rib 811 defines the upstream side in the sheet conveying direction of the lower surface portion of the reversing portion 8A, and guides the sheet S toward the main body side guide rib 802.

  The opening / closing unit 81 defines a right side portion of an area extending in the vertical direction in the double-sided conveyance path 50B. The opening / closing unit side guide rib 811 is provided on the lower end side of the opening / closing unit 81. As described above, the opening / closing unit 81 can be opened / closed with respect to the transport guide unit 80. As the opening / closing unit 81 is opened / closed, the opening / closing unit side guide rib 811 is moved to the right so as to be separated from the inner side guide portion 801 and the main body side guide rib 802, so Opened to the outside of the apparatus body 10. Therefore, even when the sheet S is jammed in the duplex conveyance path 50B, the user of the image forming apparatus 1 can easily remove the sheet S.

  A separation portion 8B corresponding to the opening / closing boundary of the opening / closing unit 81 is formed between the downstream end of the opening / closing unit side guide rib 811 in the conveying direction and the upstream end of the main body side guide rib 802 in the conveying direction. (FIG. 2). In the present embodiment, in the closed state of the opening / closing unit 81, a slight gap (predetermined interval) is formed in the separation portion 8B. For this reason, even when position variation occurs in the assembly of the opening / closing unit 81 to the apparatus main body 10, the opening / closing unit 81 collides with the conveyance guide unit 80, that is, the opening / closing unit side guide rib 811 collides with the body side guide rib 802. It is prevented. When the opening / closing unit 81 is fixed to the apparatus main body 10 by a latch (not shown), the opening / closing unit 81 is pushed slightly from the normal fixing position, and then the spring shown in FIGS. It is fixed at the fixed position by the urging force of the member 10RS. Even in such a case, the opening / closing unit side guide rib 811 is prevented from colliding with the main body side guide rib 802.

  Referring to FIG. 3, the opening / closing unit side guide rib 811 includes a first rib portion 811A (upstream side guide portion) and a second rib portion 811B (downstream side guide portion). The first rib portion 811A is an upstream portion of the opening / closing unit side guide rib 811 in the sheet conveying direction. As shown in FIG. 3, the first rib portion 811 </ b> A extends along the opposing inner guide portion 801 so that the interval between the inversion portions 8 </ b> A is partially constant. The second rib portion 811B is connected to the downstream side in the transport direction of the first rib portion 811A so that a bent portion is formed between the second rib portion 811B and the first rib portion 811A.

  The second rib portion 811B is disposed to face the main body side guide rib 802 at the end portion on the downstream side in the sheet conveying direction. The second rib portion 811B is inclined forward and downward along the sheet conveying direction. For this reason, the interval of the reversing portion 8A is expanded from the second interval to the first interval from the first rib portion 811A to the main body side guide rib 802. In the cross-sectional view shown in FIG. 3, the second rib portion 811B is formed of a concave curved surface toward the sheet surface of the sheet S conveyed through the reversing portion 8A.

  Next, with reference to FIG. 2 thru | or FIG. 6, the effect | action of the opening-and-closing unit side guide rib 811 which concerns on this embodiment is demonstrated. With reference to FIG. 2, the sheet S carried into the double-sided conveyance path 50 </ b> B is conveyed vertically downward by the first conveyance roller pair 82, the second conveyance roller pair 83, and the third conveyance roller pair 84. Eventually, when the leading end SS of the sheet S reaches the reversing portion 8A, the leading end SS is conveyed leftward and downward while being guided by the first rib portion 811A of the opening / closing unit side guide rib 811 (FIG. 3). ). Thereafter, the distal end portion SS is separated from the boundary point between the first rib portion 811A and the second rib portion 811B, and reaches the arcuate guide surface 802A of the main body side guide rib 802 as shown in FIG.

  In the present embodiment, as described above, the opening / closing unit 81 can be opened and closed with respect to the transport guide unit 80. Therefore, a separation portion 8B (gap) (FIG. 2) is formed between the opening / closing unit side guide rib 811 and the main body side guide rib 802. If the opening / closing unit side guide rib 811 and the main body side guide rib 802 do not have a step (height difference) along the conveyance direction and are formed at the same height, the leading end portion SS of the sheet S enters the separation portion 8B. In addition, the sheet S is likely to be clogged. In particular, in the image forming unit 30 and the fixing unit 60, when an image is formed on one sheet surface of the sheet S, the sheet S is likely to be curled. When the leading end portion SS of the sheet S is curled, the leading end portion SS further easily enters the separation portion 8B. On the other hand, in the present embodiment, a step is formed between the opening / closing unit side guide rib 811 and the main body side guide rib 802. For this reason, the front end portion SS of the sheet S is prevented from entering the separation portion 8B.

  When the sheet S is further conveyed by the third conveyance roller pair 84 from the state shown in FIG. 4, the leading end portion SS of the sheet S is conveyed upward along the main body side guide rib 802 and eventually reaches the registration roller pair 51. The tip SS is temporarily brought into contact with the resist roller pair 51 whose rotation has been stopped, and then conveyed toward the upper image forming unit 30 (FIG. 1) as the resist roller pair 51 rotates (FIG. 5). ).

  In the present embodiment, as described above, the opening / closing unit side guide rib 811 includes the second rib portion 811B. The second rib portion 811B is inclined downwardly from the first rib portion 811A toward the main body side guide rib 802. For this reason, as shown in FIG. 6, after the rear end portion ST of the sheet S is guided by the first rib portion 811A, it is conveyed in the sheet conveying direction while being guided by the second rib portion 811B. Accordingly, the rear end portion ST of the sheet S is smoothly transferred from the first rib portion 811A to the main body side guide rib 802.

  If the second rib portion 811B has no inclination and extends along the vertical direction, a steep step is formed between the first rib portion 811A and the main body side guide rib 802. In this case, since the rear end portion ST of the sheet S is strongly struck against the left end portion of the main body side guide rib 802, a large hitting sound is likely to be generated. In particular, when the sheet S is a stiff cardboard, such a hitting sound becomes prominent. Further, when the rear end portion ST of the sheet S is curled, the generation of the hitting sound is likely to be remarkable. On the other hand, in the present embodiment, as described above, since the rear end portion ST of the sheet S is guided by the second rib portion 811B, the occurrence of such a hitting sound is suppressed. Further, the second rib portion 811B is formed of a concave curved surface toward the sheet surface of the sheet S conveyed through the reversing portion 8A. For this reason, the rear end portion ST of the sheet S is guided more smoothly.

  Further, the main body side guide rib 802 and the opening / closing unit side guide rib 811 are composed of a plurality of ribs arranged at intervals in the sheet width direction intersecting the sheet S conveyance direction. For this reason, while the sliding load between the opening-and-closing unit side guide rib 811 and the sheet | seat S is reduced, generation | occurrence | production of sheet | seat clogging and a tapping sound is suppressed.

  The double-sided conveyance unit 8 and the image forming apparatus 1 including the duplex conveyance unit 8 according to the embodiment of the present invention have been described above. However, the present invention is not limited to this, and for example, the following modified embodiment is adopted. Can do.

  (1) In the above-described embodiment, the reversing unit 8A (double-sided conveyance path 50B) is opened to the outside by rotating the opening / closing unit 81 about the opening / closing fulcrum 81S. Is not limited to this. That is, the reversing unit 8A (double-sided conveyance path 50B) may be opened by sliding the opening / closing unit 81 to the right (horizontal direction) along a rail (not shown).

  (2) In the above embodiment, the double-sided conveyance path 50B is described as the conveyance path including the reversing unit 8A, but the present invention is not limited to this. The present invention may be applied to other conveyance paths including the reversing unit 8A and the sheet S being conveyed.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Apparatus main body 10R Right side part 30 Image forming part 50A Main conveyance path 50B Double-sided conveyance path (sheet conveyance path)
50C Upper discharge path 50D Lower discharge path 51 Registration roller pair 8 Double-sided conveyance unit (sheet conveyance device)
8A Inversion part (curved part)
8B Separator 80 Transport guide unit (main unit)
801 Inner guide (first guide)
802 Main body side guide rib (second guide portion)
81 Opening / closing unit (opening / closing member)
810 Guide base 811 Opening / closing unit side guide rib (third guide part)
811A 1st rib part (upstream side guide part)
811B 2nd rib part (downstream side guide part)
81S Open / close fulcrum (fulcrum)
82 First transport roller pair 83 Second transport roller pair 84 Third transport roller pair

Claims (7)

The main unit,
An opening and closing member that can be opened and closed with respect to the main unit;
A sheet conveying path that includes a curved reversing portion that extends between the main unit and the opening and closing member, and is reversed and conveyed upward after the sheet is conveyed downward;
A curved first guide portion fixed to the main unit and forming one side surface of the reversing portion;
A curved second guide portion that is disposed so as to face the first guide portion, forms a downstream side in the sheet conveyance direction among the other side surfaces of the reversing portion, and guides the sheet upward;
It is fixed to the opening / closing member so as to face the first guide part, and is arranged higher than the second guide part so as to form a step along the transport direction with the second guide part, A third guide portion that forms an upstream side in the sheet conveyance direction among the other side surface of the reversing portion;
Have
The upstream guide portion is formed such that a bent portion is formed between the upstream guide portion extending along the first guide portion on the upstream side in the transport direction and the upstream guide portion. A downstream guide portion that is connected to the downstream side in the transport direction and is inclined downward toward the second guide portion,
The downstream end portion in the transport direction of the downstream guide portion of the third guide portion is opposed to the upstream end portion in the transport direction of the second guide portion with a predetermined interval. Sheet transport device.   The sheet conveying apparatus according to claim 1, wherein the second guide unit and the third guide unit are a plurality of ribs arranged at intervals in a sheet width direction intersecting the conveying direction.   3. The sheet according to claim 1, wherein the downstream guide portion of the third guide portion has a concave curved surface toward a sheet surface of the sheet conveyed through the sheet conveyance path. Conveying device.   4. The open / close member according to claim 1, wherein the open / close member is opened / closed with respect to the main body unit by rotating around a fulcrum portion disposed below the reversing portion. 5. The sheet conveying apparatus according to item.   4. The sheet conveying apparatus according to claim 1, wherein the opening / closing member is opened / closed with respect to the main body unit by being slid in a horizontal direction. 5. An image forming unit for forming an image on a sheet;
A sheet conveying device according to any one of claims 1 to 5,
An image forming apparatus comprising:   The said sheet conveying apparatus is a double-sided conveyance unit which conveys the said sheet | seat in which the image was formed in one sheet surface in the said image forming part toward the said image forming part again. Image forming apparatus.

Images