JP2004161390A - Sheet carrier, and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet carrier capable of reducing damages on a sheet or a reference member and reliably carrying the sheet which is short in the length in the sheet carrying direction, and an image forming apparatus having the same. <P>SOLUTION: A rotator 107a to be rotated in the direction to carry the sheet S1 toward a reference member 109 is provided in a re-carrying passage 18, and the carrying force to carry the sheet S1 is generated in the rotator 107a without pressing a driven roller or the like against the rotator 107a by pressing the sheet S1 against the rotator 107a by a carrying force generating means 122A provided on the side of the rotator 107a. The restrictive force in the thrust direction to the sheet S1 of the rotator 107a is reduced by generating the carrying force without pressing the driven roller or the like against the rotator 107a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet conveying apparatus and an image forming apparatus including the same, and more particularly, to a sheet conveying apparatus that forms an image on a second surface opposite to a sheet on which an image is formed on a first surface by an image forming unit. To transport the paper again.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as a copier, a printer, and a facsimile, for example, an image forming unit forms an image on a second surface opposite to a sheet on which an image is formed on a first surface. Some of such image forming apparatuses include a sheet conveying device that conveys a sheet having an image formed on the first surface to the image forming unit again.
[0003]
FIG. 6 is a diagram showing a schematic configuration of a laser beam printer which is an example of a conventional image forming apparatus provided with such a sheet conveying device.
[0004]
In FIG. 1, reference numeral 50 denotes a laser beam printer for forming an image by an electrophotographic method. The laser beam printer 50 separates and feeds an image forming unit 51 for forming an image and a sheet S to the image forming unit 51 one by one. And a feeding section 52 for performing the operation. Also, the laser beam printer 50 feeds the sheet S to the image forming unit 50 again to form an image on the back side after the image is formed on one side so that an image can be formed on both sides of the sheet S. A double-sided unit 10 as a sheet conveying means for carrying out the operation is optionally provided.
[0005]
Here, the image forming unit 51 includes a process cartridge 53, a transfer roller 4, and the like, and the feeding unit 52 includes a sheet feeding cassette 3a for stacking sheets S, a pickup roller 3b, a feed roller 3c1, and a separation roller pair including a retard roller 3c2. 3c. The process cartridge 53 integrally includes the photosensitive drum 7, a charging unit 8 for uniformly charging the surface of the photosensitive drum 7, a developing unit 9 for developing an electrostatic latent image formed on the photosensitive drum 7, and the like. It is detachable from a laser beam printer main body (hereinafter, referred to as an apparatus main body) 54.
[0006]
Further, the duplex unit 10 includes a re-conveyance path 18, a lateral registration correction unit (not shown), a pair of re-feed rollers 11a and 11b, and the like. In FIG. 1, reference numeral 1 denotes a laser scanner unit, 5 denotes a fixing unit, and 6 denotes a discharge tray.
[0007]
Next, an image forming operation of the laser beam printer 50 thus configured will be described.
[0008]
When image information is sent from a personal computer (not shown) to a control unit (not shown) and the control unit performs image forming processing on the image information and a print signal is issued from the control unit, first, the photosensitive drum 7 rotates in the direction of the arrow. Then, the charging roller 8 is uniformly charged to a predetermined polarity and a predetermined potential. Then, the laser beam is radiated from the laser scanner 1 to the photosensitive drum 7 whose surface is charged in this way based on image information, whereby an electrostatic latent image is formed on the photosensitive drum 7. You. Next, this electrostatic latent image is developed by the developing means 9 and visualized as a toner image.
[0009]
On the other hand, the sheets S stacked and stored in the sheet cassette 3a in parallel with the toner image forming operation are sent out by the pickup roller 3b, separated and conveyed by the separation roller pair 3c, and thereafter conveyed. The sheet is conveyed to a transfer section including the photosensitive drum 7 and the transfer roller 4 by the roller pairs 3d and 3e.
[0010]
At this time, the leading end of the sheet S is detected by a registration sensor (not shown) provided upstream of the transfer unit. Based on a detection signal from the registration sensor, the control unit determines the position of the leading end of the sheet S and the light emission timing of the laser scanner 1. To synchronize. Thereby, the toner image formed on the photosensitive drum can be transferred to a predetermined position on the sheet S.
[0011]
Next, the sheet S on which the toner image has been transferred as described above is sent to the fixing unit 5 along the transport belt 3f, and is heated and pressurized when passing through the fixing unit 5, so that the toner image is semi-permanent. Is fixed.
[0012]
Here, in the case of single-sided printing, the sheet S that has passed through the fixing unit 5 is sent to the nip between the transport roller 3g, which can be rotated forward and backward, and the first roller 3m, and then the discharge that can be rotated forward and backward by the transport roller 3g. The sheet is discharged to the discharge tray 6 by the normal rotation of the roller 3h.
[0013]
On the other hand, when performing double-sided printing, the discharge roller 3h conveys the sheet S toward the discharge tray 6 by normal rotation, and then reverses after the trailing edge of the sheet passes through the conveyance roller 3g. Here, when the rear end of the sheet S passes through the conveying roller 3g, the rear end of the sheet S moves toward the second roller 3n due to its stiffness. When the discharge roller 3h further rotates in this state, the rear end of the sheet S is conveyed. It enters the nip between the roller 3g and the second roller 3n, and is nipped by the transport roller 3g and the second roller 3n.
[0014]
When the sheet S is nipped by the second roller 3n in this manner, the transport roller 3g is rotated in the reverse direction, whereby the sheet S passes through the re-transport path 18 of the double-sided unit 10, and is fed to the re-feed roller 11a and The sheet is conveyed by a pair of re-feed rollers 11a and 11b constituted by a driven roller 11b pressed against the re-feed roller 11a and sent to the image forming unit 51 again. Then, the image on the second surface is formed in the image forming section 51, and thereafter, the image is stacked on the discharge tray 6 by the discharge roller 3h.
[0015]
By the way, in the laser beam printer 50 having such a double-sided unit 10, when the sheet S is conveyed again to the image forming unit 51, the sheet S is skewed during conveyance, and the sheet S is formed when forming an image on the second side. And the image may be shifted. This is because, when an image is formed on the second side, the conveyance path until the image is formed on the sheet is longer than that on the first side, so that the eccentricity of various rollers, the difference in pressing force, and the resistance of the conveyance side This is because the sheet is slightly displaced during conveyance due to a difference between the sheets.
[0016]
Therefore, in order to prevent such a shift of the sheet S, after the image is formed on the first side, the position of the sheet S is adjusted until the image is formed on the second side so that the image and the sheet S match. It is necessary to adjust the position of the seat. As a method of performing such positioning, for example, during sheet conveyance, the sheet is conveyed while being pressed against a reference member serving as a positioning reference disposed at one end of the re-conveying path 18. There is a way.
[0017]
FIGS. 7A and 7B are top views showing the configuration of the re-transport passage 18 provided with such a reference member. FIG. 8A is a side sectional view, and FIG. 8B is a front view.
[0018]
7 and 8, reference numerals 13 and 13 denote roller shafts of two refeed rollers 11a. These drive roller shafts 13 and 13 are used as reference members by bearings 14 as shown in FIG. It is held rotatably with respect to a certain reference guide 12.
[0019]
Pulleys 15 are fixed to the ends of the two roller shafts 13, 13, respectively, and the two roller shafts 13, 13 are driven by belts 16 a, 16 b wrapped around the pulley 15. One of the belts 16a and 16b is driven by a drive motor 12 (see FIG. 6) in the double-sided unit 10, and the drive motor 12 drives the re-feed roller 11a.
[0020]
Reference numeral 17 denotes a pin which rotatably holds the driven roller 11b and is held by a transport upper guide 19 which forms the upper surface (top surface) of the re-transport passage 18, and 181 denotes a spring which presses the pin 17 from above. The driven roller 11b is pressed against the re-feed roller 11a with a certain pressure by the spring 181.
[0021]
Here, the re-conveying passage 18 is a so-called one-sided reference which adjusts the position of the side end of the sheet S by pressing one side of the sheet S against the reference guide 12. First and second reference surfaces 12a and 12b are provided. Reference numeral 20 denotes a lower conveyance guide that forms the lower surface of the re-transport passage 18 together with the reference guide 12.
[0022]
In the re-conveying path 18 for adjusting the position of the sheet S based on the one-side reference, the sheet S conveyed by the conveying roller 3g in the direction of the arrow A in FIG. 11b.
[0023]
Here, (the roller shaft 13 of) the re-feed roller 11a and the driven roller 11a are respectively fixed at a fixed angle so that a force in the direction of the reference surface acts on the sheet S in order to abut the sheet S against the reference surfaces 12a and 12b. Leaning. As a result, the sheet S is conveyed while changing its direction to the reference surface side and pressed against the reference surfaces 12a and 12b, whereby the alignment is performed.
[0024]
By the way, the reference surfaces 12a and 12b with which the side ends of the sheet S abut in this way are determined by the length of the sheet S in the width direction. For example, the first reference surface 12a is a letter size and A4 size, and the second reference surface 12b is a side end reference of the executive size and B5 size sheet S.
[0025]
FIG. 9 shows a re-conveying path 18 that can convey a sheet S1 of a size smaller than these sheets S, for example, an A5 size sheet. The re-conveying path 18 has an A5 size sheet S1. The reference guide 12 having the third reference surface 12c is provided to convey the sheet S, that is, to accommodate the sheet S1 having a narrow sheet width.
[0026]
Here, when re-feeding such a small-sized sheet S1, since the length of the sheet S1 in the sheet transport direction is short, the transport roller 3g shown in FIG. 6 and the pair of re-feed rollers 11a and 11b on the upstream side are used. The length of the sheet S1 becomes shorter than the distance from the sheet S, and it becomes difficult to convey the small-sized sheet S1.
[0027]
Therefore, when such a small-sized sheet S1 is transported, the small-sized sheet S1 can be transported between the transport roller 3g and the pair of re-feed rollers 11a and 11b on the upstream side as shown in FIG. As shown in FIG. 7, a pair of re-feed rollers 11a 'and 11b' is added. By adding such a pair of re-feed rollers 11 'and 11b', the belt 16c is also added, and the three roller shafts 13 can be driven.
[0028]
[Problems to be solved by the invention]
By the way, in a conventional double-sided unit (sheet conveying apparatus) having such a configuration and a laser beam printer (image forming apparatus) including the same, as shown in FIG. 9, upstream of the first to third reference planes 12a to 12c. Are provided with guide surfaces 12d for guiding the sheet S toward the first to third reference surfaces 12a to 12c, respectively. The sheet S conveyed by the conveyance roller 3g is oriented along the guide surface 12d in the first to third directions. The paper is conveyed while changing to the third reference plane side.
[0029]
Then, the sheet S conveyed while changing the direction in this way is thereafter fed obliquely by the pair of re-feed rollers 11a ', 11b', 11a, 11b, and thereby the first to third reference surfaces 12a to 12b. 12c, whereby alignment is performed.
[0030]
However, in the case of the duplex unit 10 that conveys a sheet S1 of A5 size from the letter size to the minimum paper size, when the conveyed sheet S1 reaches the pair of re-feed rollers 11a 'and 11b' as shown in FIG. S1 is moved to the reference guide side by the restraining force in the thrust direction of the pair of sheet re-feed rollers 11 'and 11b'.
[0031]
When the sheet S1 moves in this manner, the corner of the sheet tip comes into contact with the guide surface 12d, and there is a concern that the guide surface 12d of the reference guide 12 and the corner of the sheet tip may be damaged. This is true not only for the A5 size sheet S1 but also for other large size sheets.
[0032]
Therefore, the present invention has been made in view of such a situation, and it is possible to reduce damage to a sheet or a reference guide (reference member) and to surely convey a sheet having a short length in a sheet conveying direction. It is an object of the present invention to provide a sheet conveying apparatus capable of performing the above-described operations and an image forming apparatus including the same.
[0033]
[Means for Solving the Problems]
The present invention provides a sheet conveying apparatus for conveying a sheet again to the image forming unit so as to form an image on a second surface opposite to a sheet on which an image is formed on a first surface by an image forming unit, A re-conveying passage through which a sheet conveyed again passes through, and one end of the re-conveying passage in a width direction orthogonal to the sheet conveying direction, and abutting on a side end of the sheet passing through the re-conveying passage. A reference member extending in a sheet conveying direction for performing position adjustment in the width direction of the sheet, a rotating body provided in the re-conveying path, and rotating in a direction for conveying the sheet toward the reference member, And a conveying force generating means for pressing a sheet against the rotating body and generating a conveying force for conveying the sheet to the rotating body.
[0034]
Further, according to the present invention, the reference member has a guide space provided with a contact portion through which a side end of a sheet passing through the re-conveying passage passes and which comes into contact with a side end of the sheet. The generating means is an upper guide member that is arranged so that the upper surface of the guide space is lower than the upper end surface of the rotating body, and forms an upper surface of the guide space.
[0035]
Further, the invention is characterized in that the conveying force generating means is a push-down member provided on a side of the rotating body opposite to the reference member, and pushing down the sheet so as to be lower than an upper end surface of the rotating body. It is assumed that.
[0036]
Further, according to the present invention, the reference member has a guide space provided with a contact portion through which a side end of a sheet passing through the re-conveying passage passes and which comes into contact with a side end of the sheet. The upper guide member forming the upper surface of the rotating member is arranged so that the upper surface of the guide space is higher than the upper end surface of the rotating body.
[0037]
Also, in the present invention, the reference member is provided on the upstream side of the contact surface in the sheet conveying direction, and contacts the corner of the leading end of the conveyed sheet to change the direction of the sheet to face the contact surface. It is characterized in that it has an introduction section for changing over.
[0038]
According to another aspect of the invention, an image forming apparatus includes an image forming unit and any one of the above-described sheet conveying apparatuses.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0040]
FIG. 2 is a diagram illustrating a configuration of a laser beam printer as an example of an image forming apparatus including the sheet conveying device according to the embodiment of the present invention. 6, the same reference numerals as those in FIG. 6 indicate the same or corresponding parts.
[0041]
In FIG. 2, reference numeral 102 denotes a sheet re-feeding unit which is a sheet conveying device provided with a sheet re-feeding path 18. The sheet re-feeding path 18 of the sheet re-feeding unit 102 includes first to third sheet re-feeding rollers 107a to 107c. Is provided. In the present embodiment, the driven rollers 108b and 108c are in pressure contact with the second and third re-feed rollers 107b and 107c on the downstream side in the sheet conveying direction with a certain pressure.
[0042]
Note that no driven roller is provided on the first re-feed roller 107a on the upstream side in the transport direction, which is a rotating body that rotates in the direction in which the sheet S is transported toward the reference member described later. The first re-feed roller 107a has almost no binding force in the thrust direction of the sheet S.
[0043]
Here, the distance between the transport roller 3g on the apparatus main body side that finally transports the sheet S to the re-feed unit 102 and the second transport roller pair 107b, 108b in the re-feed unit is determined by the transport direction in which the sheet is transported. Are arranged so as to be longer than the length of the shortest sheet, here, the sheet of A5 size.
[0044]
The distance between the transport roller 3g and the first re-feed roller 107a and the distance between the first re-feed roller 107a and the pair of second transport rollers 107b and 108b are longer than the length of the A5 size sheet S in the transport direction. It is arranged to be shorter.
[0045]
By providing the first re-feed roller 107a at such a position, the A5 size sheet S can be reliably conveyed. Note that the distance between the transport roller 3g and the second transport roller pair 107b, 108b is shorter than the length of the larger size sheet S other than the A5 size sheet S.
[0046]
FIG. 1 is a view for explaining the configuration of a re-conveying passage portion of the re-feeding unit 102 thus configured. In FIG. 1, reference numeral 109 denotes a contact portion which comes into contact with a letter size sheet and an A4 size sheet. A reference including a certain first reference surface 109a, a second reference surface 109b that is a contact portion that contacts the executive size sheet and the B5 size sheet, and a third reference surface 109c that is a contact portion that contacts the A5 size sheet S1. This is a reference guide which is a member, and when the A5 size sheet S1 is conveyed, the positioning is performed by the third reference surface 109c.
[0047]
Reference numerals 120 to 122 denote first to third guide spaces formed in the reference guide 109. The first to third guide spaces 120 to 122 include bottom surfaces 120a to 122a on which the sheet S slides, It has upper surfaces 120b to 122b that regulate upward movement of S, and first to third reference surfaces 109a to 109c that are formed by inner side wall surfaces.
[0048]
As shown in FIG. 3, a guide surface 109d, which is an introduction portion for guiding the sheet S toward the first to third reference surfaces 109a to 109c, is provided upstream of the first to third reference surfaces 109a to 109c. The sheet S conveyed by the conveying roller 3g is conveyed while changing the direction along the guide surface 109d to the first to third reference surface sides by contacting a corner portion of the sheet tip with the guide surface 109d. It has become.
[0049]
By the way, when the positioning of the A5 size sheet S1 is performed by the third reference surface 109c, the A5 size sheet S1 passes through the conveying roller pair 3g, and then passes through the second conveying roller pair 107b, 107b in the re-feeding unit. Until the sheet 108 is nipped, the sheet is conveyed only by the first sheet re-feed roller 107a and enters the third guide space 122 as shown in FIG.
[0050]
Here, the height of the upper surface (top surface) 122b of the third guide space 122 is a predetermined height y higher than the outer peripheral surface 107d which is the upper end surface of the first re-feed roller 107a as shown in FIG. It is lower.
[0051]
Therefore, when the sheet S1 enters the third guide space 122 in this manner, the A5 size sheet S1 is lowered due to the difference between the outer peripheral surface 107d of the first re-feed roller 107a and the height of the upper surface 122b of the third guide space 122. The sheet S1 is pressed against the guide member side end of the first re-feed roller 107a indicated by the arrow B due to the rigidity of the sheet S1. A pressing force C is generated at the end.
[0052]
When the pressing force C is generated as described above, the pressing force C acts as a conveying force for conveying the sheet S1 due to friction between the sheet S1 and the first re-feed roller 107a.
[0053]
In order to generate such a conveyance force, the upper surface 122b of the third guide space 122 is formed, and the sheet S1 is bent and pressed against the first re-feed roller 107a, thereby causing the first re-feed roller The distance x between the end of the upper guide member 122A constituting the conveying force generating means for generating the conveying force for conveying the sheet S1 to the first sheet re-feed roller 107a and the first sheet re-feeding roller 107a may be about 5 to 20 mm. Desirably, the difference y between the outer peripheral surface 107d of the first re-feed roller 107a and the height of the upper surface 122b of the third guide space 122 is desirably about 0.1 to 3 mm. Further, it is desirable that the edge of the first re-feed roller 107a be provided with a C surface or an R in order to increase the contact area with the sheet S1 indicated by the arrow B.
[0054]
As described above, the sheet S1 is bent and pressed against the first re-feed roller 107a by the upper guide member 122A provided on the side of the first re-feed roller 107a. A conveying force can be generated without bringing the driven rollers into pressure contact.
[0055]
That is, by overlapping the first re-feed roller 107a in contact with the sheet S with the upper guide member 122A in the up-down direction, the first re-feed roller 107a having almost no restraining force in the thrust direction is applied to the sheet S1. The conveyance force can be generated using the rigidity of the sheet.
[0056]
By generating a conveying force without pressing the driven roller in the first re-feed roller 107a, the sheet holding force of the first re-feed roller 107a is reduced as compared with a case in which the driven roller is pressed. can do. Accordingly, the restraining force of the first re-feed roller 107a on the sheet S in the thrust direction can be weakened, and as a result, the sheet S or the reference guide 109 (the guide surface 109d thereof) can be transported while reducing the damage to the guide S. The sheet S1 of a short size in the direction length can be reliably conveyed.
[0057]
Next, a second embodiment of the present invention will be described.
[0058]
FIG. 4 is a diagram illustrating a configuration of a sheet re-feeding unit that is the sheet conveying device according to the present embodiment. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.
[0059]
In FIG. 1, reference numeral 110 denotes an upper conveyance guide that forms the upper surface of the re-conveyance passage 18 of the re-feed unit 102. The upper conveyance conveyance guide 110 is used to push down the sheet S conveyed to the re-conveyance passage 18 downward. A rib 110a serving as a pressing member protrudes downward. Here, the rib 110a is formed such that its tip position is lower by a predetermined height z than the outer peripheral surface 107d which is the upper end surface of the first re-feed roller 107a.
[0060]
With this configuration, when the A5 size sheet S1 enters the third guide space 122, the A5 size sheet S1 is transferred to the outer peripheral surface 107d of the first re-feed roller 107a and the tip of the rib 110a. Due to the difference in height between the first sheet re-feed roller 107a and the sheet S1, the pressing force E is generated at the rib-side end of the first sheet re-feed roller 107a due to the rigidity of the sheet S1.
[0061]
Note that, in the present embodiment, even if the sheet S1 bends upward as described above, the third guide space 122 is inserted into the third guide space 122 as shown in FIG. Is higher than the outer peripheral surface 107d of the first re-feed roller 107a by a predetermined height y1.
[0062]
When the pressing force E is generated as described above, the pressing force E acts as a conveying force for conveying the sheet S due to friction between the sheet S1 and the first re-feed roller 107a. Here, as in the first embodiment, the first re-feed roller 107a generates the conveyance force without pressing the driven roller, so that the first re-feed roller 107a performs the first re-rolling as compared with the case where the driven roller is pressed. The holding force of the sheet feeding roller 107a on the sheet S1 can be reduced.
[0063]
Accordingly, the restraining force of the first re-feed roller 107a on the sheet S in the thrust direction can be weakened, and as a result, the sheet S or the reference guide 109 (the guide surface 109d thereof) can be transported while reducing the damage to the guide S. The sheet S1 of a short size in the direction length can be reliably conveyed.
[0064]
In the above description, a case has been described in which a roller (first re-feed roller 107a) is used as a rotating body that rotates in the direction in which the sheet S1 is conveyed toward the reference guide 109. However, the same effect can be obtained by using a conveyor belt 112 as shown in FIG.
[0065]
【The invention's effect】
As described above, according to the present invention, the sheet is rotated by the conveying force generating means provided on the side of the rotator to the rotator rotating in the direction of conveying the sheet toward the reference member provided in the re-conveying path. By pressing, a conveying force for conveying a sheet to the rotating body can be generated without causing the driven roller or the like to press against the rotating body.
[0066]
In addition, by making it possible to generate the conveying force without pressing the driven roller or the like against the rotating body, the restraining force of the rotating body on the sheet in the thrust direction can be reduced. Damage to the reference member can be reduced, and a sheet having a short length in the sheet conveying direction can be reliably conveyed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a re-conveying path provided in a re-feeding unit that is a sheet conveying device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus including the refeed unit.
FIG. 3 is a top view of the re-transport passage.
FIG. 4 is a diagram illustrating a configuration of a re-conveying path provided in a re-feeding unit which is a sheet conveying device according to a second embodiment of the present invention.
FIG. 5 is a diagram illustrating a configuration of a re-conveying path provided in a re-feeding unit which is a sheet conveying apparatus according to another embodiment of the present invention.
FIG. 6 is a diagram illustrating a schematic configuration of a laser beam printer as an example of a conventional image forming apparatus.
FIG. 7 is a top view illustrating the configuration of a re-transport passage of a re-feed unit provided in the conventional laser beam printer.
FIG. 8 is a side cross-sectional view and a front view illustrating a configuration of a re-transport passage of the conventional re-feed unit.
FIG. 9 is a top view and a side cross-sectional view illustrating a configuration of another re-conveying path of the re-feeding unit provided in the conventional laser beam printer.
[Explanation of symbols]
18 Re-conveyance path 50 Laser beam printer 51 Image forming unit 102 Re-feed unit 107a First re-feed roller 109 Reference guide 109a First reference surface 109b Second reference surface 109c Third reference surface 109d Guide surface 110 Upper conveyance guide 110a Rib 112 Transport belt 120 First guide space 121 Second guide space 122 Third guide space 122b Upper surface 122A of third guide space Upper guide member S Sheet S1 A5 size sheet

Claims (6)

In a sheet conveying device for conveying the sheet again to the image forming unit so as to form an image on a second surface opposite to the sheet on which the image is formed on the first surface by the image forming unit,
A re-conveying passage through which a sheet conveyed again to the image forming unit passes;
The re-conveying passage is provided at one end in the width direction orthogonal to the sheet conveying direction, and extends in the sheet conveying direction for abutting with a side end of the sheet passing through the re-conveying passage to perform alignment in the width direction of the sheet. Reference member,
A rotating body that is provided in the re-conveying path and that rotates in a direction to convey a sheet toward the reference member;
A sheet conveying device, comprising: a conveying force generating unit provided on a side of the rotating body to press a sheet against the rotating body and generate a conveying force for conveying the sheet to the rotating body. The reference member has a guide space provided with a contact portion through which a side end of a sheet passing through the re-conveying path passes, and which abuts on a side end of the sheet.
The said conveyance force generation means is arrange | positioned so that the upper surface of the said guide space may become lower than the upper end surface of the said rotating body, and is an upper guide member which forms the upper surface of the said guide space, The said 1st aspect. Sheet transport device. 2. The conveying force generating means is a pressing member provided on a side of the rotating body opposite to the reference member, and pressing down the sheet so as to be lower than an upper end surface of the rotating body. The sheet conveying device as described in the above. The reference member has a guide space provided with a contact portion through which a side end of a sheet passing through the re-conveying path passes, and which abuts on a side end of the sheet.
The sheet conveying device according to claim 3, wherein an upper guide member that forms an upper surface of the guide space is disposed such that an upper surface of the guide space is higher than an upper end surface of the rotating body. The reference member is provided on the upstream side of the contact surface in the sheet conveying direction, and includes an introduction unit that contacts a corner of the leading end of the conveyed sheet to change the direction of the sheet and face the contact surface. The sheet conveying device according to claim 2, wherein An image forming apparatus, comprising: an image forming unit; and the sheet conveying device according to claim 1.

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