JP7317569B2 - Paper transport device and image forming device - Google Patents

Description

The present invention relates to a paper conveying device that conveys paper along a curved conveying path, and an image forming apparatus having the same.

2. Description of the Related Art An image forming apparatus needs to convey paper in a conveying path during an image forming process, and is equipped with a paper conveying device inside. The sheet conveying device includes a conveying guide for forming a conveying path and conveying rollers arranged along the conveying path.

Generally, a transport path in an image forming apparatus includes a transport path that is at least partially curved (hereinafter referred to as a curved transport path) (Patent Documents 1 and 2). FIG. 8 is a cross-sectional view showing a schematic configuration of a conventional paper conveying device 50 that conveys paper along a curved conveying path.

The paper conveying device 50 has an upstream conveying roller pair 510, a downstream conveying roller pair 520, and a conveying guide pair 530. The conveying guide pair 530 consists of the upstream conveying roller pair 510 and the downstream conveying roller pair 520. forming a curved conveying path between The upstream transport roller pair 510 includes an inner peripheral upstream roller 511 arranged on the curved inner peripheral side and an outer peripheral upstream roller 512 arranged on the curved outer peripheral side. Similarly, the downstream transport roller pair 520 includes an inner peripheral downstream roller 521 and an outer peripheral downstream roller 522, and the transport guide pair 530 includes an inner peripheral guide member 531 and an outer peripheral guide member 532. .

The transport guide pair 530 forms a curved transport path, and both the inner guide member 531 and the outer guide member 532 have curved shapes along the transport direction Y. As shown in FIG. Therefore, in the sheet conveying device 50 , the inner guide member 531 has a portion that protrudes to the curved outer peripheral side from the common outer tangent line L of the inner peripheral upstream roller 511 and the inner peripheral downstream roller 521 . The common outer tangent line refers to a common tangent line that is in contact with both of the two circles and that does not intersect with the line segment connecting the centers of these two circles.

JP 2015-147672 A JP 2010-1127 A

When plain paper is conveyed by the conventional paper conveying apparatus 50 shown in FIG. 8, since plain paper with low stiffness is easily bent along the curved conveying path, it does not receive particularly large conveying resistance even in the curved conveying path. None. However, when conveying stiff paper such as thick paper, the curved conveying path may receive a large conveying resistance.

When thick paper having a strong stiffness is conveyed in the paper conveying device 50, the tip of the thick paper entering the curved conveying path from the upstream conveying roller pair 510 is pushed by the outer guide member 532 as shown in FIG. 9(a). It is conveyed while contacting and rubbing the leading end against the outer peripheral side guide member 532 . Also, the stiff cardboard does not bend greatly even in the curved conveying path, and as it is conveyed, it approaches the inner peripheral side guide member 531 and eventually comes into contact with the inner peripheral side guide member 531 as shown in FIG. 9B. do. At this time, the cardboard comes into contact with a portion of the inner peripheral side guide member 531 that protrudes from the common external tangent line L toward the curved outer peripheral side. The thick paper in contact with the inner guide member 531 in this way receives a large transport resistance due to friction with the inner guide member 531 .
If the circle is on the same side as seen from the line, it is tangent to the line.
When the sheet conveying resistance increases in this way, there is a concern that a conveying slip may occur and a conveying jam may occur. Conventionally, countermeasures have been taken such as arranging another conveying roller pair in the curved conveying path or providing rotating rollers in the inner peripheral side guide member 531 to reduce the conveying resistance. However, these countermeasures have problems such as an increase in cost due to an increase in the number of parts and difficulty in securing space for arranging parts.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus capable of reducing the conveying resistance of a curved conveying path with a simple configuration.

In order to solve the above-described problems, a first aspect of the present invention provides a sheet conveying apparatus that conveys sheets in a curved conveying path in an image forming apparatus. a pair of upstream conveying rollers arranged on the curved conveying path; a pair of downstream conveying rollers arranged downstream of the curved conveying path; and a curved conveying path between the pair of upstream conveying rollers and the pair of downstream conveying rollers. The upstream transport roller pair includes an inner peripheral upstream roller arranged on the inner peripheral side of the curved transport path and an inner peripheral upstream roller arranged on the outer peripheral side of the curved transport path. The pair of downstream conveying rollers includes an inner downstream roller disposed on the inner circumferential side of the curved conveying path and an outer circumferential side roller disposed on the outer circumferential side of the curved conveying path. The conveying guide pair includes an inner peripheral side guide member arranged on the inner peripheral side of the curved conveying path and an outer peripheral side guide member arranged on the outer peripheral side of the curved conveying path. and the inner guide member does not have a portion projecting to the outer peripheral side of the curved conveying path from a common outer tangent line between the inner upstream roller and the inner downstream roller. Characterized by

According to the above configuration, since the inner guide member does not have a portion protruding to the outer peripheral side from the common outer tangent line of the inner peripheral upstream roller and the inner peripheral downstream roller, it is possible to use thick paper or the like with strong stiffness. When conveying the paper, it is possible to prevent the paper from coming into contact with the inner guide member. As a result, it is possible to prevent the sheet from coming into contact with the inner guide member and receiving a large transport resistance due to friction with the inner guide member.

Further, in the sheet conveying device, the inner peripheral side guide member may have a configuration in which the entire guide surface is a flat portion.

Further, in the sheet conveying device, the inner guide member includes a curved area on the upstream side from the boundary point in the sheet conveying direction and a linear area on the downstream side from the boundary point in the sheet conveying direction. has a curved surface portion at least in part, and the linear area can be configured so that the entirety thereof is formed as a flat surface portion.

According to the above configuration, the sheet entry port of the curved transport path is widened by the curved region of the inner peripheral side guide member, making it easier for the sheet to enter. It can guide you to the transportation route.

Further, in the sheet conveying device, the boundary point is an intersection point where a tangent line passing through the nip portion of the upstream conveying roller pair intersects the guide surface of the outer peripheral guide member when the tangent line extends downstream. The boundary point may be set so as to face the intersection point.

Further, in the sheet conveying device, the curved area of the inner peripheral side guide member has a curved surface portion only near the center in the sheet width direction, and both sides of the curved surface portion in the sheet width direction are flat portions. Further, the curved surface portion may be formed by a curved surface that protrudes toward the inner peripheral side of the curved conveying path.

According to the above configuration, it is possible to smoothly guide a sheet of paper that is wavy near the center of the leading edge to the curved conveying path, and suppress fluttering of the sheet near both ends in the width direction of the sheet. The paper can be smoothly conveyed to the conveying roller pair.

Further, in the sheet conveying device, the guide surface of the inner peripheral side guide member may have a shape without ribs.

Further, in the paper conveying device, in the downstream conveying roller pair, the diameter of the inner peripheral downstream roller is set to be larger than the diameter of the outer peripheral downstream roller, and the inner peripheral downstream roller The driving roller and the outer peripheral downstream roller can be configured as driven rollers.

According to the above configuration, when paper such as thick paper with strong stiffness is conveyed in the paper conveying device, the paper that reaches the pair of downstream conveying rollers first comes into contact with the inner peripheral downstream roller, which is the drive roller. It can receive the conveying force of the inner peripheral side downstream roller. As a result, it is possible to suppress transport failures of thick paper and the like.

Further, in order to solve the above problems, an image forming apparatus according to a second aspect of the present invention is equipped with the sheet conveying device described above.

INDUSTRIAL APPLICABILITY The sheet conveying apparatus and the image forming apparatus of the present invention can prevent the sheet from contacting the inner guide member when conveying stiff sheets such as thick paper. contact with the inner peripheral side guide member, thereby suppressing a large conveyance resistance due to friction with the inner peripheral side guide member.

1, showing an embodiment of the present invention, is a schematic cross-sectional view of an image forming apparatus. 1A and 1B are diagrams showing a schematic configuration of a sheet conveying device according to Embodiment 1, FIG. 1A being a cross-sectional view of the sheet conveying device, and FIG. 3A and 3B are cross-sectional views showing a sheet conveying mode when a stiff sheet is conveyed by the sheet conveying apparatus of FIG. 2; FIG. FIG. 5 is a cross-sectional view showing a schematic configuration of a sheet conveying device according to Embodiment 2; FIG. 10 is a cross-sectional view showing a schematic configuration of a sheet conveying device that is a modified example of Embodiment 2; 6A and 6B are diagrams showing the arrangement relationship between an inner peripheral side guide member and a pair of paper feed rollers in the paper conveying device of FIG. It is the top view seen from the guide surface of the circumference side guide member. FIG. 11 is a cross-sectional view showing a schematic configuration of a sheet conveying device according to Embodiment 3; 1 is a cross-sectional view showing a schematic configuration of a conventional sheet conveying device; FIG. 9A and 9B are cross-sectional views showing a sheet conveying mode when a stiff sheet is conveyed by the sheet conveying apparatus of FIG. 8; FIG.

[Embodiment 1]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus 100 to which the present invention is applied. Note that the image forming apparatus 100 shown in FIG. 1 is a color image forming apparatus having a plurality of process units, but the present invention is not limited to this, and may be a monochrome image forming apparatus having a single process unit. can also be applied.

The image forming apparatus 100 includes a main unit 101, a document reading unit 102, a document conveying device 103, and a paper feeding device 104, as shown in FIG. The body portion 101 has an image forming portion for printing an image on a recording sheet. The document reading unit 102 is arranged above the main unit 101 and reads a document when copying the document. The document conveying device 103 sequentially conveys the documents placed on the document set tray toward the document placing table of the document reading unit 102 in the automatic reading mode. The paper feeding device 104 includes at least one paper feeding cassette 104a for stocking recording paper, and the recording paper is separated one by one by a pickup roller 104b provided in the selected paper feeding cassette 104a and picked up. The recording paper is conveyed toward the main body 101 by the conveying roller pair 104c. In the main unit 101, the recording paper fed from the paper feeding device 104 is first transported by the transport roller pair 101c.

The image data handled by the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a single color (for example, black). It corresponds to the monochrome image that was used. Therefore, the image forming apparatus 100 has four process units (image forming units) Pa to Pd associated with black, cyan, magenta, and yellow. Each of the process units Pa to Pd forms a toner image according to image data using electrophotographic technology.

Each toner image formed by each of the process units Pa to Pd is sequentially transferred onto the intermediate transfer belt 61 and superimposed. Thereby, a color toner image is formed on the intermediate transfer belt 61 . The color toner image on the intermediate transfer belt 61 is transferred onto the recording paper, and the fixing device 10 heats and presses the recording paper to fix the color toner image on the recording paper.

Each of the process units Pa to Pd has a configuration in which a charging section, an exposure section, a developing section, a transfer section, a cleaning section, and a neutralizing section are arranged around the photosensitive drum 60 along the rotational direction of the photosensitive drum 60 . Since each of the process units Pa to Pd uses image formation using a known electrophotographic method, detailed description thereof will be omitted.

Next, the sheet conveying device 10 according to the first embodiment will be described in detail with reference to the drawings. 2A and 2B are diagrams showing a schematic configuration of the sheet conveying device 10 according to the first embodiment, in which FIG. 2A is a cross-sectional view of the sheet conveying device 10, and FIG. is a plan view. The sheet conveying device 10 is mounted on the image forming apparatus 100 and conveys the sheet along a curved conveying path inside the image forming apparatus 100 . Here, a case where the sheet conveying device 10 is used for conveying the sheet from the conveying roller pair 104c of the sheet feeding device 104 to the conveying roller pair 101c of the main body 101 is illustrated. However, the location of the sheet conveying device 10 in the image forming apparatus 100 is not particularly limited.

The paper conveying device 10 has an upstream conveying roller pair 110, a downstream conveying roller pair 120, and a conveying guide pair 130. The conveying guide pair 130 includes the upstream conveying roller pair 110 and the downstream conveying roller pair 120. forming a curved conveying path between The upstream conveying roller pair 110 includes an inner peripheral upstream roller 111 arranged on the curved inner peripheral side and an outer peripheral upstream roller 112 arranged on the curved outer peripheral side. Similarly, the downstream transport roller pair 120 includes an inner peripheral downstream roller 121 and an outer peripheral downstream roller 122, and the transport guide pair 130 includes an inner peripheral guide member 131 and an outer peripheral guide member 132. . In this example, the upstream transport roller pair 110 corresponds to the transport roller pair 104c of the paper feeding device 104, and the downstream transport roller pair 120 corresponds to the transport roller pair 101c of the main body 101. FIG.

The conveying guide pair 130 forms a curved conveying path, and the outer guide member 132 has a curved shape along the conveying direction Y. As shown in FIG. On the other hand, the inner peripheral side guide member 131 has a linear shape along the transport direction Y. As shown in FIG. More specifically, the inner guide member 131 has a guide surface substantially parallel to the common outer tangent line L<b>1 between the inner upstream roller 111 and the inner downstream roller 121 . In other words, the inner peripheral side guide member 131 according to Embodiment 1 has a flat surface (flat portion) over the entire guide surface. Incidentally, the inner peripheral upstream roller 111 and the inner peripheral downstream roller 121 have two common outer tangents, and the common outer tangent L1 here is the inner peripheral upstream roller 111 and the inner peripheral downstream roller 121. , refers to a common external tangent existing on the outer peripheral side of the curved conveying path.

Further, in the sheet conveying device 10, the inner peripheral side guide member 131 does not have a portion protruding to the outer peripheral side from the common outer tangent line L1. In FIG. 2, the guide surface of the inner guide member 131 is arranged to be on the inner peripheral side of the common outer tangent line L1. may be arranged so as to match the

When plain paper is conveyed by the paper conveying apparatus 10 according to the first embodiment, plain paper with low stiffness is easily bent along the curved conveying path, and therefore receives a particularly large conveying resistance even in the curved conveying path. There is no Furthermore, in the paper conveying device 10, even when a stiff paper such as thick paper is conveyed, it is possible to prevent the conveyed paper from being subjected to a large conveying resistance in the curved conveying path.

When the paper P conveyed by the paper conveying device 10 is thick paper or the like with strong stiffness, the paper P entering the curved conveying path from the upstream conveying roller pair 110 has a leading edge as shown in FIG. It contacts the outer peripheral guide member 132 and is transported while the tip thereof rubs against the outer peripheral guide member 132 . Also, the stiff paper P does not bend greatly even in the curved conveying path, and approaches the inner guide member 131 as it is conveyed.

However, in the paper conveying device 10, the inner guide member 131 does not have a portion that protrudes outward from the common outer tangent line L1. The sheet P can be prevented from contacting the inner guide member 131 . That is, as shown in FIG. 3B , the leading edge of the paper P transported by the upstream transport roller pair 110 reaches the downstream transport roller pair 120 before contacting the inner peripheral guide member 131 . After the leading edge reaches the downstream transport roller pair 120, the paper P transported by the upstream transport roller pair 110 and the downstream transport roller pair 120 does not enter the inner peripheral side of the common outer tangent line L1. P does not come into contact with the inner peripheral side guide member 131 either. As a result, it is possible to prevent the sheet P from coming into contact with the inner guide member 131 and receiving a large transport resistance due to friction with the inner guide member 131 .

Many of the transport guides in conventional paper transport devices are provided with ribs extending along the paper transport direction on the guide surface in order to reduce friction with the transported paper and reduce transport resistance. . In the sheet conveying device 10 as well, it is preferable that the guide surface of the outer guide member 132 is provided with ribs. On the other hand, the guide surface of the inner peripheral side guide member 131 may be provided with ribs, but it is more preferable that no ribs be provided. This is because the inner guide member 131 of the sheet conveying device 10 is arranged on the inner circumference side of the common outer tangent line L1 to reduce the conveying resistance, and there is no need to provide a rib to reduce the conveying resistance. because it is low. If the inner peripheral side guide member 131 has no ribs, it is possible to prevent the sheet P to be conveyed from having rib streaks.

[Embodiment 2]
In the sheet conveying device 10 according to the first embodiment, the inner guide member 131 has a linear shape along the conveying direction Y. As shown in FIG. That is, the guide surface of the inner peripheral side guide member 131 is a flat surface as a whole. However, in the sheet conveying device of the present invention, the shape of the guide surface of the inner guide member is not limited to a flat surface, and may have a curved surface at least partially. In the second embodiment, a sheet conveying device including an inner guide member having a partially curved surface will be described. FIG. 4 is a cross-sectional view showing a schematic configuration of the sheet conveying device 20 according to the second embodiment.

The sheet conveying device 20 has a configuration similar to that of the sheet conveying device 10 shown in FIG. Instead, it has an inner peripheral side guide member 231 . Therefore, in the sheet conveying device 20, the downstream conveying roller pair 120 (the inner peripheral downstream roller 121 and the outer peripheral downstream roller 122) and the outer peripheral guide member 132 basically have the same configuration as the paper conveying device 10. . Only the parts different from the sheet conveying device 10 will be described below.

The paper feed roller pair 210 includes a paper feed roller 211 arranged on the inner side of the curve and a separation roller 212 arranged on the outer side of the curve. The pair of paper feed rollers 210 feeds and conveys sheets picked up one by one from a stack of paper stored in the paper feeding section of the image forming apparatus in which the paper conveying device 20 is mounted. . In the paper feed roller pair 210, the transport speed of the separation roller 212 is set to be lower than the transport speed of the paper feed roller 211 in order to prevent double feeding of sheets. In the paper conveying device 20, the paper feeding roller pair 210 corresponds to the upstream side conveying roller pair described in the claims, the paper feeding roller 211 corresponds to the inner peripheral side upstream roller, and the separation roller 212 corresponds to the outer peripheral side. Corresponds to the upstream roller.

The inner peripheral guide member 231 has a curved region 231a on the upstream side of the boundary point A and a linear region 231b on the downstream side of the boundary point A. As shown in FIG. In the curved region 231 a , the guide surface of the inner guide member 231 is curved in the same direction as the guide surface of the outer guide member 132 . In the linear region 231b, the guide surface of the inner peripheral side guide member 231 is a flat surface having a linear shape along the transport direction Y. As shown in FIG. In this configuration, the sheet inlet (upstream opening) of the curved transport path formed by the inner guide member 231 and the outer guide member 132 is widened by the curved region 231a, so that the sheet P can easily enter. ing.

The leading edge of the paper P conveyed by the paper feed roller pair 210 and entering the curved conveying path is wavy in the paper width direction due to the difference in conveying speed between the paper feed roller 211 and the separation roller 212 . In the paper conveying device 20, since the paper entry port of the curved conveying path is widened to facilitate entry of the paper P, even the paper P having a wavy edge is smoothly guided to the curved conveying path. .

In the inner peripheral side guide member 231 of the sheet conveying device 20, the position of the boundary point A, which is the boundary between the curved region 231a and the straight region 231b, is preferably set as follows. First, a tangent line L2 (a tangent line (common inner tangent line) between the paper feed roller 211 and the separation roller 212) passing through the nip portion of the paper feed roller pair 210 is extended downstream, and the tangent line L2 is aligned with the guide surface of the outer peripheral guide member 132. The point where they intersect is point B. It is preferable that boundary point A is positioned to face point B. Here, "boundary point A faces point B" means that the outer peripheral side guide passing through point B Assuming a tangent line L3 to the guide surface of the member 132, a straight line connecting the boundary points A and B is almost orthogonal to the tangent line L3.By setting the position of the boundary point A in this way, The upstream end of the curved region 231a of the inner guide member 231 can be positioned higher than the central axis of the paper feed roller 211. This widens the paper entrance of the curved transport path, allowing the paper P In addition, even if the paper edge in the direction perpendicular to the paper transport direction (paper edge in the paper width direction) is curled inward, the paper P If the area until the tip reaches point B is set as the curved area, it is possible to prevent the generation of noise due to folding of the paper edge and friction with the guide.

FIG. 5 is a cross-sectional view showing a schematic configuration of a sheet conveying device 21 that is a modification of the second embodiment. The sheet conveying device 21 has a configuration similar to that of the sheet conveying device 20 shown in FIG. Only the parts different from the sheet conveying device 20 will be described below.

6A and 6B are views showing the arrangement relationship between the inner guide member 233 and the paper feed roller pair 210 (the paper feed roller 211 and the separation roller 212). 3B is a plan view seen from the guide surface of the inner peripheral side guide member 233. FIG.

As with the inner guide member 231, the inner guide member 233 has a curved region 233a on the upstream side of the boundary point A and a linear region 233b on the downstream side of the boundary point A. As shown in FIG. However, the curved region 233a does not have a curved surface as a whole, but has a curved surface portion 233c only near the center in the paper width direction, and flat portions 233d are formed on both sides of the curved surface portion 233c in the paper width direction. ing. The curved surface portion 233c of the inner peripheral side guide member 233 is formed with a curved surface that is convex toward the inner peripheral side of the curved conveying path (that is, the outer side of the conveying path). It can be said that the linear region 233b is entirely formed as a plane portion.

That is, the inner peripheral side guide member 233 has a curved surface portion 233c at a location facing the paper feed roller pair 210 in the paper transport direction Y, and the curved surface portion 233c widens the paper entrance of the curved transport path at this location. It is For this reason, even the paper P that is wavy near the center of the leading end thereof can be smoothly guided to the curved conveying path by the paper feed roller pair 210 .

Also, in the paper P, there is little waviness near both ends in the paper width direction where the paper feed roller pair 210 is not present. For this reason, in the paper conveying device 21, the vicinity of both ends of the inner peripheral guide member 233 in the paper width direction is a flat portion 233d, and the paper entrance of the curved conveying path is not widened at this portion. As a result, fluttering of the paper P is suppressed near both ends in the paper width direction, and the paper P can be smoothly conveyed to the downstream-side conveying roller pair 120 .

In the inner peripheral guide member 233, the width W1 at the upstream end of the curved surface portion 233c is preferably larger than the roller width W2 of the paper feed roller pair 210, and the width W1 is at least twice the roller width W2. is more preferable.

[Embodiment 3]
FIG. 7 is a cross-sectional view showing a schematic configuration of a sheet conveying device 30 that is a modification of the third embodiment. The sheet conveying device 30 has a configuration similar to that of the sheet conveying device 10 shown in FIG. Only the parts different from the sheet conveying device 10 will be described below.

The downstream conveying roller pair 320 includes an inner peripheral downstream roller 321 arranged on the curved inner peripheral side and an outer peripheral downstream roller 322 arranged on the curved outer peripheral side. In the downstream conveying roller pair 320 , the diameter of the inner peripheral downstream roller 321 is set to be larger than the diameter of the outer peripheral downstream roller 322 . Further, in the downstream conveying roller pair 320, the inner peripheral downstream roller 321 is a driving roller driven by a driving means such as a motor, and the outer peripheral downstream roller 322 is a driven roller.

When the paper P such as thick paper with strong stiffness is conveyed in the paper conveying device 30 , the paper P guided by the outer peripheral guide member 132 and reaching the downstream conveying roller pair 320 first reaches the inner peripheral downstream roller 321 . easier to contact. Then, the paper P in contact with the inner peripheral downstream roller 321 can receive the conveying force of the inner peripheral downstream roller 321, which is a driving roller. As a result, in the paper conveying device 30, it is possible to suppress conveyance defects such as thick paper.

The embodiments disclosed this time are exemplifications in all respects and are not grounds for restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, all changes within the meaning and range of equivalents to the scope of claims are included.

10, 20, 30 Paper transport device 110 Upstream transport roller pair 111 Inner peripheral upstream roller 112 Outer peripheral upstream rollers 120, 320 Downstream transport roller pair 121, 321 Inner peripheral downstream rollers 122, 322 Outer peripheral downstream roller 130 Transport Guide pairs 131, 231, 233 Inner peripheral side guide members 231a, 233a Curved regions 231b, 233b Straight region 233c Curved surface portion 233d Plane portion 210 Paper feed roller pair (upstream transport roller pair)
211 Paper feed roller (inner circumference side upstream roller)
212 separation roller (peripheral upstream roller)

Claims (6)

A sheet conveying device for conveying a sheet on a curved conveying path in an image forming apparatus,
an upstream transport roller pair arranged upstream of the curved transport path;
a pair of downstream conveying rollers arranged downstream of the curved conveying path;
a conveying guide pair forming a curved conveying path between the upstream conveying roller pair and the downstream conveying roller pair;
The upstream transport roller pair includes an inner peripheral upstream roller arranged on the inner peripheral side of the curved transport path and an outer peripheral upstream roller arranged on the outer peripheral side of the curved transport path,
The downstream transport roller pair includes an inner peripheral downstream roller arranged on the inner peripheral side of the curved transport path and an outer peripheral downstream roller arranged on the outer peripheral side of the curved transport path,
The transport guide pair includes an inner peripheral guide member arranged on the inner peripheral side of the curved transport path and an outer peripheral guide member arranged on the outer peripheral side of the curved transport path,
The inner guide member does not have a portion that protrudes to the outer peripheral side of the curved conveying path from a common outer tangent line between the inner upstream roller and the inner downstream roller,
The inner guide member is composed of a curved region on the upstream side from the boundary point in the paper conveying direction and a linear region on the downstream side from the boundary point in the paper conveying direction,
At least a part of the curved region has a curved surface portion, and the linear region is entirely formed as a flat portion,
The curved region of the inner guide member has a curved surface portion only near the center in the paper width direction so as to face the pair of upstream transport rollers provided only near the center in the paper width direction in the paper transport direction. , both sides of the curved surface portion in the paper width direction are flat portions,
The sheet conveying device , wherein the curved surface portion is formed with a curved surface that protrudes toward the inner peripheral side of the curved conveying path . The paper conveying device according to claim 1,
The sheet conveying device, wherein the guide surface of the inner peripheral side guide member is entirely flat. The paper conveying device according to claim 1 ,
The boundary point is opposed to an intersection point where a tangent line passing through the nip portion of the upstream conveying roller pair intersects the guide surface of the outer peripheral guide member when the tangent line extends downstream. A sheet conveying device characterized in that it is set to The sheet conveying device according to any one of claims 1 to 3 ,
A sheet conveying device, wherein the guide surface of the inner guide member has a shape without ribs. The sheet conveying device according to any one of claims 1 to 4 ,
In the downstream conveying roller pair, the diameter of the inner downstream roller is set to be larger than the diameter of the outer downstream roller, and the inner downstream roller is the driving roller and the outer downstream roller is the driving roller. A sheet conveying device characterized by being a driven roller. An image forming apparatus comprising the sheet conveying device according to any one of claims 1 to 5 .

Images