JP2005059966A - Sheet carrying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a conventional sheet carrying device wherein the magnitude of a sheet carrying resistance at a curved reversal part on the upstream side affects largely on a correction capacity in a lateral resister correction means. <P>SOLUTION: This device comprises the lateral resister correction means having a reference plate 24 with a reference plane 24a correcting sheets to a specified lateral position by restricting the side end part of the sheets and a tapered plane 24b continued from the lateral outer side to the reference plane and carrying roller pairs 25 and 26 rotating the sheets by providing them with a carrying force in the specified lateral area on the reference plane side. A curved guide 40 on the upstream side comprises an inside guide 40a inscribing at one inside point with an arc with a radius of 65 to 80 mm and an outside guide 40b circumscribing at two outside points with the arc. By this, the sheet carrying resistance at the curved guide can be optimally maintained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus that conveys a sheet, and is applied to an image forming apparatus capable of forming a double-sided image on a sheet, such as a printer, a facsimile machine, and a copying machine.
[0002]
[Prior art]
In a sheet conveying apparatus applied to a reconveying section of an image forming apparatus capable of forming a double-sided image of a sheet, in order to maintain good printing accuracy on the second side, a sheet generated during conveyance in image formation on the first side Generally, “horizontal registration correcting means” for correcting a shift in the width direction is provided (see, for example, Patent Document 1).
[0003]
10 to 12 will be described as an example of a conventional sheet conveying apparatus having a lateral registration correcting unit.
[0004]
FIG. 10 is a main cross-sectional view of a laser beam printer as an example of a conventional image forming apparatus. FIG. 11 is a plan view of the sheet conveyance path of the sheet re-conveyance unit 103 from the post-fixing roller 117 to the refeed roller 122. It is the figure seen from the top.
The laser beam printer 101 can form images not only on one side of a sheet but also on both sides. The laser beam printer 101 includes an image forming unit 102 that performs image formation and a sheet reconveying unit 103 that serves as a sheet conveying device that performs sheet reversal.
[0005]
When images are formed on both sides of the sheet S, the sheet S is conveyed to the switchback roller 114 after the image is formed by the image forming unit 102. By the reverse rotation of the switchback roller 114, the sheet S is continuously sent to the sheet re-conveying unit 103 with the leading edge and the trailing edge reversed. The sheet re-conveying unit 103 includes, from upstream, a post-fixing roller 117 serving as a nipping and conveying unit, a second roller 119 that faces the post-fixing roller 117, a curve reversing unit 140 that forms a conveyance path by the inner guide 140a and the outer guide 140b, A lateral registration correction unit 123 that corrects the position in the width direction of the sheet to be rotated, a re-feed roller 122 disposed downstream of the lateral registration correction unit 123, and a re-feed roller that abuts against the re-feed roller 122. 130 is the center. The sheet S sent to the sheet re-conveying unit 103 is corrected in position in the width direction by the lateral registration correcting unit 123 and then sent again to the image forming unit 102 by the re-feed roller 122 to perform image formation on the second side. Then, the sheet is discharged from the sheet discharge unit 115 to the outside of the apparatus.
[0006]
Here, the configuration and operation of the lateral registration correcting unit 123 in the sheet re-conveying unit 103 will be described with reference to FIG.
[0007]
The lateral registration correction unit 123 includes a reference plate 124 including a reference surface 124a, a pair of conveyance rollers including a lateral registration correction roller 125 and a skew feeding roller 126 as a lateral registration correction roller, and a conveyance lower guide 127. It is.
[0008]
The reference plate 124 is fixed to the main body of the laser beam printer 101, and includes a lateral registration correction roller 125, a skew feeding roller holding portion 124g, a sheet side end guide 124d including a reference surface 124a and a tapered surface 124b, and a guide on the lower surface of the sheet. It is a member that includes a part 124f, a guide part 124e on the upper surface of the sheet, and the like. The sheet-side end guide 124d has a tapered surface 124b from the intersection 124c on the upstream side of the lateral registration correction roller 125.
[0009]
The lateral registration correction roller 125 is held by the reference plate 124 via a bearing (not shown), and sandwiches the sheet in a predetermined region in the width direction. Further, it is arranged so that its rotation axis is perpendicular to the transport direction.
[0010]
The oblique feeding roller 126 is rotatably held by the reference plate 124 and is urged by the lateral registration correction roller 125 by a spring (not shown) to form a nip. Further, the rotation axis of the oblique feeding roller 126 is disposed so as to have an inclination of about 7 ° toward the reference surface 124 a with respect to the rotation axis of the lateral registration correction roller 125.
[0011]
The positions of the lateral registration correction roller 125 and the skew feeding roller 126 in the sheet width direction are closer to the right end as viewed from the front of the apparatus, the same as the reference surface 124a. In this case, the position closer to the right end portion is at least the right end portion side of the sheet width 1/3.
[0012]
On the downstream side of the lateral registration correction unit 123, there is provided a refeeding unit that refeeds the refeed roller 122 and the roller 130 facing the refeed roller 122 to form a nip.
Next, the lateral registration correction operation when the sheet S is conveyed away from the reference surface 124a to the lateral registration correction unit 123 will be described with reference to FIG.
[0013]
The leading edge of the sheet S conveyed to the lateral registration correction unit 123 by the post-fixing roller 117 is guided to the curve reversing unit 140, and eventually the leading edge reaches the lateral registration correction roller 125 and the oblique feeding roller 126. In a state where the trailing edge of the sheet S is sandwiched between the nips of the fixing roller 117 and the second roller 119, only the leading edge of the sheet S approaches the reference surface 124a due to the oblique feeding force of the oblique feeding roller 116 (FIG. 12A )).
[0014]
Thereafter, when the trailing edge of the sheet S passes through the nip between the post-fixing roller 117 and the second roller 119, the sheet S receives the conveyance resistance by the conveyance lower guide 127 and the curve reversing unit 140 so that the sheet S brings the trailing edge closer to the reference surface 124a side. Rotate to. Since the sheet S is tilted by this rotation, the sheet S becomes closer to the reference plane 124a (FIG. 12B).
[0015]
The sheet S abuts on the intersection 124c between the reference surface 124a and the tapered surface 124b, and the reaction force causes reverse rotation to bring the front end of the sheet S closer to the reference surface 124a. The sheet S is aligned at a position along the reference surface 124a. (FIG. 12C).
[0016]
As described above, the sheet conveying apparatus configured to include the lateral registration correction unit using the pair of lateral registration correction rollers can perform lateral registration correction relatively efficiently as compared with other lateral registration correction units.
[0017]
[Patent Document 1]
JP 2000-233850 A
[0018]
[Problems to be solved by the invention]
However, the sheet conveying apparatus including the lateral registration correcting unit that performs lateral registration correction by rotating the sheet by the conveying force of the pair of conveying rollers provided in the predetermined region in the width direction as described in the conventional example is also described below. Such a problem remained.
[0019]
In the above-described conventional lateral registration correction means, the size of the sheet conveyance resistance in the curve reversing portion greatly affects the lateral registration correction capability. That is, the operation shown in FIG. 12B is completed earlier as the sheet conveyance resistance is larger, and conversely, the operation shown in FIG. 12C is completed earlier as the sheet conveyance resistance is smaller. Therefore, in order to reduce the length of the path required for the lateral registration correction as much as possible, it is necessary to configure the guide so that the sheet conveyance resistance in the curved reversal portion is in an appropriate state.
[0020]
However, even though such a sheet conveying apparatus is usually required to be able to cope with conveyance of sheets of various thicknesses, the sheet conveyance resistance in the curved inversion unit depends on the thickness of the sheet, that is, the waist strength. Because of the difference, it has been difficult to construct a guide that achieves appropriate conveyance resistance at the curved reversal part for thick paper and thin paper.
[0021]
The present invention has been made in view of the above-described problems, and the object of the present invention is to configure the guide so as to achieve an appropriate conveyance resistance at the curved inversion portion for the thick paper and the thin paper. It is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus that can perform lateral registration correction efficiently even in a short pass regardless of the thickness.
[0022]
[Means for Solving the Problems]
The present invention provides a lateral registration correction unit that corrects a position in the width direction of a sheet by rotating the sheet with a regulation unit that regulates a side edge portion of the sheet and bringing the sheet into contact with the regulation unit, and the lateral registration correction unit. A sandwiching and conveying unit that sandwiches and conveys the sheet; and a bending guide unit that is disposed between the sandwiching and conveying unit and the lateral registration correcting unit and that guides the sheet by curving the sheet. An inner guide member that is inscribed at one inner point with respect to an arc of ˜80 mm and an outer guide member that is circumscribed at two outer points with respect to the arc.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
The first embodiment of the present invention will be described in detail with reference to FIGS.
[0024]
FIG. 1 is a main sectional view of a laser beam printer as an example of a double-sided image forming apparatus according to the first embodiment. The laser beam printer 1 includes an image forming unit 2 that forms an image on both sides as well as a sheet, and a sheet re-conveying unit 3 that is an example of a sheet conveying device that performs lateral registration correction and performs sheet reversal. .
[0025]
A plurality of sheets S can be stacked on the cassette 4. The feeding unit 5 is a unit that separates and feeds the sheets S stacked on the cassette 4 by the sheet feeding roller 6 or the like one by one. The process cartridge 7 is integrally provided with a photosensitive drum 8 and process means (charging means, developing means, cleaning means) that act on the photosensitive drum 8, and is detachable from the laser beam printer 1 main body.
[0026]
The transfer roller 9 transfers the toner image formed on the opposing photosensitive drum 8. The fixing unit 10 fixes the toner image semi-permanently on the sheet S on which the toner image is transferred.
[0027]
The laser scanner unit 12 irradiates the photosensitive drum 8 with laser light corresponding to the image signal created by the controller board 11 to form a latent image.
[0028]
The controller board 11 also has a function of controlling the main body of the laser beam printer 1 and performing an image forming process on an image signal of a computer (not shown) connected thereto.
[0029]
The post-fixing roller 17 forms a nip with the first roller 18 and conveys the sheet S that has come out of the fixing unit 10 along the discharge guide 20 and the flapper 39.
[0030]
The paper discharge unit 13 includes a discharge roller 14 and a discharge roller 15 facing each other, and constitutes a discharge unit. The discharge stacking table 16 is a table that receives the sheet S discharged by the discharge roller 14 and the discharge roller 15.
[0031]
Next, the operation of the image forming unit 2 will be described.
[0032]
When the image forming unit 2 receives a print command, the sheets S stacked on the cassette 4 are separated and fed one by one by the paper feed roller 6 and between the photosensitive drum 8 and the transfer roller 9 in the process cartridge 7 ( Nip). The print command is generated via the controller board 11 when image information is sent from a personal computer (not shown).
[0033]
Along with this print command, the laser scanner unit 12 irradiates the photosensitive drum 8 with a bit image of the image information (laser light), and a toner image is formed on the photosensitive drum 8 by developing means according to the bit image. The toner image formed on the photosensitive drum 8 is transferred to the sheet S at the nip between the photosensitive drum 8 and the transfer roller 9.
[0034]
Then, the sheet S on which the toner image is transferred is sent to the fixing unit 10 and heated and pressed by the fixing unit 10. As a result, the toner image is fixed on the sheet S semi-permanently. After being fixed by the fixing unit 10, the sheet S is sent to the nip of the first roller 18 facing the post-fixing roller 17, and is sent to the sheet discharge unit 13 through the discharge guide 20 and the flapper 39.
[0035]
At this time, the position of the flapper 39 is the position of the solid line in FIG. When the controller board 11 receives a single-sided image formation signal, the sheet S is nipped and conveyed by the discharge roller 14 and the discharge roller 15 and is discharged to the discharge stacking table 16.
[0036]
Here, the single-sided image formation signal is a signal sent to the controller board 11 from a personal computer (not shown) as in the case of the print signal and the image signal.
[0037]
When the controller board 11 receives a double-sided image formation signal, after the trailing edge of the sheet has passed through the flapper 39, the discharge roller 14 rotates in the reverse direction and the flapper 39 moves to the position of the two-dot chain line in FIG. . Accordingly, the sheet S is continuously sent to the sheet re-conveying unit 3.
[0038]
Next, the configuration of the sheet re-conveying unit 3 will be described with reference to FIGS.
[0039]
FIG. 2 is a plan view of the sheet conveyance path of the sheet re-conveyance unit 3 from the post-fixing roller 17 to the re-feed roller 22 as viewed from above, and FIG. 3 is a configuration in the vicinity of the curve reversal unit 40 in FIG. It is an enlarged view for demonstrating.
[0040]
Here, the sheet re-conveying unit 3 starts from the pair of discharge rollers 14, passes through the curve reversing unit 40 and the lateral registration correcting unit 23, and focuses on the conveyance path from the cassette 4 to the junction 21 with the conveyance path. Composed.
[0041]
In addition to the first roller 18, the second roller 19 faces the post-fixing roller 17 and is biased toward the post-fixing roller 17. After the discharge roller 14 rotates in the reverse direction, the sheet S is fed into the nip N1 formed by the second roller 19 and is nipped and conveyed.
[0042]
In the present embodiment, the same conveyance path as that of the first discharge conveyance path is used for the conveyance path from the pair of discharge rollers 14 to the nip N1 between the post-fixing roller 17 and the second roller 19.
[0043]
Here, two or more post-fixing rollers 17 are arranged in the sheet width direction in order to suppress the rotational movement of the sheet S during conveyance. Further, two or more first rollers 18 and second rollers 19 are arranged in the same manner as the post-fixing roller 17.
[0044]
In the conveyance path from the post-fixing roller 17 to the lateral registration correction unit 23, a curve reversing unit 40 is provided as a guide unit for changing the sheet conveyance direction from the vertical direction to the horizontal direction. The curve reversing unit 40 is composed of an inner guide 40a and an outer guide 40b that are located on the inner side and the outer side, respectively, with respect to the curvature of the conveyance path.
[0045]
The horizontal registration correction unit 23 as a horizontal registration correction means includes a reference plate 24 including a reference surface 24a, a pair of conveyance rollers including a horizontal registration correction roller 25 and a skew feeding roller 26 as a horizontal registration correction roller, And a guide 27.
[0046]
The reference surface 24a is a surface that coincides with the right end position (as viewed from the front of the apparatus) of the maximum width sheet conveyed to the sheet reconveying unit 3. For example, when the size of the sheet S conveyed to the sheet reconveying unit 3 is limited to A4 / LTR / LGL, the reference surface 24a is at the same position as the right end of the LTR or LGL size.
[0047]
The lateral registration correction unit 23 is provided for the purpose of correcting the position of the sheet S that has been shifted during conveyance to a predetermined position in the width direction along the reference surface 24a before forming the second image.
[0048]
In the present embodiment, since the reference of the first surface is the center reference, the A4 size sheet side end and the reference surface 24a (LTR / LGL end) are different by 3 mm. Accordingly, the lateral registration correction unit 23 always has a role of moving an A4 size sheet by 3 mm in the sheet width direction.
[0049]
The reference plate 24 is fixed to the main body of the laser printer 1, and includes a lateral registration correction roller 25, a skew feeding roller holding portion 24g, a sheet side end guide 24d including a reference surface 24a and a tapered surface 24b, and a guide on the lower surface of the sheet. This is a member configured to include a portion 24f, a guide portion 24e on the upper surface of the sheet, and the like.
[0050]
The lateral registration correction roller 25 is held by the reference plate 24 via a bearing (not shown), and sandwiches the sheet in a predetermined region in the width direction. Further, it is arranged so that its rotation axis is perpendicular to the transport direction.
[0051]
The oblique feeding roller 26 is rotatably held by the reference plate 24 and is urged by the lateral registration correction roller 25 by a spring (not shown) to form a nip N2. Further, the rotation axis of the oblique feeding roller 26 is disposed so as to have an inclination of about 7 ° toward the reference surface 24a with respect to the rotation axis of the lateral registration correction roller 25.
[0052]
The positions of the lateral registration correction roller 25 and the skew feeding roller 26 in the sheet width direction are close to the right end when viewed from the same front of the apparatus as the reference surface 24a. In this case, the position closer to the right end portion is at least the right end portion side of the sheet width 1/3. In this embodiment, the reference plate 24 is on the right side when viewed from the front of the apparatus. However, the reference plate 24 may be disposed on the left side when viewed from the front of the apparatus together with the lateral registration correction roller 25 and the oblique feeding roller 26.
[0053]
The conveyance lower guide 27 guides most of the lower side of the sheet conveyance surface as shown in FIG. In addition, as shown in FIG. 3, the arrangement of the lower conveyance guide 27, the inner guide 40a, and the outer guide 40b is such that the arc Q having a radius of 73 mm is circumscribed by the outer guide 40b and the lower conveyance guide 27 at P1 and P3, respectively. The guide 40a establishes an inscribed relationship at P2.
[0054]
Further, on the downstream side of the lateral registration correcting unit 23, there is provided a refeeding unit that refeeds the refeed roller 22 and the roller 30 facing the refeed roller 22 to form a nip.
[0055]
Two or more re-feed rollers 22 are arranged in the sheet width direction so that the sheet S subjected to the lateral registration correction is not skewed again. The position of the refeed roller 22 in the conveyance direction is within the range of the minimum sheet length from the lateral registration correction roller 25. A junction 21 with the first cassette feed path is located downstream of the refeed roller 22.
[0056]
Next, the operation of the sheet re-conveying unit 3 will be described. When the double-sided image formation signal is received, after the trailing edge of the sheet S on which the single-sided image has been formed is removed from the flapper 39, the position of the flapper 39 moves to the position of the two-dot chain line in FIG. The discharge roller 15 rotates in the reverse direction.
[0057]
The sheet S is nipped and conveyed by the post-fixing roller 17 and the second roller 19 with the leading and trailing ends reversed, and is conveyed to the lateral registration correcting unit 23 via the curve reversing unit 40. The operation of the lateral registration correction will be described in detail later.
[0058]
The sheet S that has been subjected to the lateral registration correction is sent again to the image forming unit 2 by the refeed roller 22, and a second image whose write-out position has been adjusted based on the reference surface 24 a is formed and sent to the sheet discharge unit 13. Then, the sheet is loaded on the sheet discharge table 16.
[0059]
Next, the operation of correcting the lateral registration of the sheet S will be described below with reference to FIG. FIG. 4 is a diagram for explaining a series of operations in lateral registration correction when viewed from the same viewpoint as FIG.
[0060]
The leading edge of the sheet S conveyed to the lateral registration correction unit 23 by the post-fixing roller 17 is guided by the curve reversing unit 40 to the inner guide 40a and the outer guide 40b. To reach. In the state where the trailing edge of the sheet S is nipped by the nip N1 of the post-fixing roller 17 and the second roller 19, only the leading edge of the sheet S approaches the reference surface 24a due to the oblique feeding force of the oblique feeding roller 26 (FIG. 4). (A)).
[0061]
After the sheet trailing edge has passed through the nip N1 between the post-fixing roller 17 and the second roller 19, the sheet S receives the conveyance resistance FA by the inner guide 40a, the outer guide 40b, and the lower conveyance guide 27. Rotate to get closer. Since the sheet S is tilted by this rotation, the sheet S becomes closer to the reference surface 24a (FIG. 4B).
[0062]
Eventually, the sheet S comes into contact with the intersection 24c of the reference surface 24a and the taper surface 24b, and the reaction force FC causes reverse rotation to bring the front end of the sheet S closer to the reference surface 24a side, and the sheet S is positioned along the reference surface 24a. (FIG. 4C).
[0063]
Hereinafter, the curve reversal unit 40 that is a feature of the present embodiment will be described in detail.
[0064]
In the present embodiment, the A4 size sheet is shifted to the left side by a maximum of 2.5 mm from the reference of the first surface and is conveyed to the sheet reconveying unit 3 to the reference position of the second surface. . The graphs of FIGS. 5 to 7 to be described later are thick sheets of A4 size sheet S (130 g / m ² ) And thin paper (60 g / m ² ) Is about 2.5 mm to the left, and all are based on the results obtained from the experiment.
[0065]
The resistance that the sheet S receives from the inner guide 40a, the outer guide 40b, and the lower conveyance guide 27 in the curved reversing unit 40 is affected by the reaction force against the force that the sheet S tries to straighten by the rigidity of the sheet S itself. The thicker the sheet and the higher the rigidity, the greater the conveyance resistance at the curved inversion unit 40. Further, since the reaction force described above increases as the sheet S is bent by the bending reversal unit 40, the conveyance resistance increases as the radius of the arc Q in FIG. 3 decreases.
[0066]
In the operation of FIG. 4B described above, the operation is completed with a shorter conveyance distance as the conveyance resistance in the bending reversing unit 40 is larger, and the operation proceeds to the operation of FIG. Therefore, in the operation of FIG. 4B, the operation is completed at a shorter distance as the conveyed sheet is thicker (the rigidity is higher) and the radius of the arc Q is smaller. FIG. 5 is a graph showing the relationship between the conveyance distance of the sheet S required from the start to the completion of the operation of FIG.
[0067]
Further, the operation of FIG. 4C is an operation reverse to that of FIG. 4B, and the lateral registration correction tends to be completed with a shorter conveyance distance as the conveyance resistance in the curve reversing unit 40 is smaller. It is in. Therefore, in the operation of FIG. 4C, the operation is completed at a shorter distance as the conveyed sheet is thinner (less rigid) and the radius of the arc Q is larger. FIG. 6 is a graph showing the relationship between the conveyance distance of the sheet S required from the start of the operation of FIG. 4C to the completion of the lateral registration correction and the radius of the arc Q.
[0068]
The operation of FIG. 4A is almost the same regardless of the thickness (rigidity) of the sheet and the radius of the arc Q, and the transport distance of the sheet S until the start of the operation of FIG. The length obtained by subtracting the distance between the nip N1 and the nip N2 from the directional length (15 mm in the present embodiment).
[0069]
From the above, the relationship between the conveyance distance and the radius of the arc Q required after the leading edge of the sheet S reaches the lateral registration correction roller 25 and the lateral registration correction is started until the correction is completed is shown in FIG. It shows a trend like a graph.
[0070]
In the present embodiment, since the radius of the arc Q is 73 mm, the sheet S is thick paper (130 g / m as shown in the graph of FIG. 7). ² ), Thin paper (60 g / m ² In any case, the transport distance required for the lateral registration correction is 125 mm. Therefore, even if the distance between the nip N1 and the nip N2 is shortened to 125 mm, it is possible to achieve both the lateral registration correction capability for thick paper and thin paper.
[0071]
By adopting such a configuration, the sheet conveyance resistance in the curved reversal portion can be reduced by thin paper (about 60 g / m ² ) To cardboard (about 130 g / m ² ), The lateral registration correction can be completed efficiently in a short pass regardless of the sheet thickness.
[0072]
(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a main cross-sectional view of a laser beam printer as an example of a double-sided image forming apparatus according to the second embodiment, and FIG. 9 is an enlarged view of the vicinity of the curve reversing unit 50. The laser beam printer 101 is configured such that the position of the inner guide 40a in the laser beam printer in the first embodiment described above can be switched between two positions. The same or corresponding components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted.
[0073]
In FIG. 8, the curved reversing unit 50 includes a fixed outer guide 52 (same as the first embodiment 40b) and an inner guide 51 provided to be rotatable around a rotation fulcrum 53. Road.
[0074]
The inner guide 51 can be switched to the positions 51a and 51b shown in FIG. 9 when the user arbitrarily turns it from the outside with a lever (not shown). The entrance of the reference plate 54 is provided with a guide-shaped taper 54a so that the inner guide 51 can be guided in either position.
[0075]
When the inner guide 51 is at the position 51a (FIG. 9a), the radius of the arc Q1 circumscribing, inscribed, and circumscribed to the outer guide 52, the inner guide 51a, and the lower conveying guide 27 is 62 mm. When the inner guide 51 is at the position 51b (FIG. 9b), the radius of the arc Q2 circumscribing, inscribed, and circumscribed to the outer guide 52, the inner guide 51b, and the lower conveyance guide 27 is 78 mm.
[0076]
Therefore, as is apparent from the graph of FIG. 7, the sheet S is thin paper (60 g / m ² ), Move the inner guide 51 to the 51a position and place the thick paper (130 g / m ² ), The conveyance distance required for lateral registration correction can be reduced to 115 mm by switching the inner guide 51 to the position 51b.
[0077]
Therefore, even if the distance between the nips N1 and N2 is shortened to 115 mm, it is possible to achieve both the lateral registration correction capability for thick paper and thin paper.
[0078]
As described above, by providing the guide position switching means for switching the position of the inner guide member or the outer guide member to at least two or more locations, the resistance in the curve reversal portion is adjusted to the optimum state according to the thickness of the sheet to be conveyed. This makes it possible to perform lateral registration correction with a shorter path.
[0079]
In the present embodiment, the position of the inner guide 51 can be switched. However, the same effect can be obtained even if the position of the outer guide 52 can be switched.
[0080]
【The invention's effect】
As described above, according to the present invention, the sheet conveyance resistance in the curved reversal portion can be maintained in an appropriate state regardless of the thickness of the sheet, and the lateral registration correction can be performed efficiently even in a short conveyance path. It becomes. Therefore, it is possible to further reduce the size and improve the throughput of the sheet conveying apparatus and the image forming apparatus provided with the lateral registration correcting means.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a lateral registration correction unit of the image forming apparatus according to the first embodiment of the present invention.
FIG. 3 is an enlarged view for explaining a configuration of a curve reversing unit according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a lateral registration correction operation by the image forming apparatus according to the first embodiment of the present invention.
FIG. 5 is a graph of experimental data showing the relationship between the guide shape of the curved reversal part and the transport distance required for lateral registration correction.
FIG. 6 is a graph of experimental data showing the relationship between the guide shape of the curve reversal part and the transport distance required for lateral registration correction.
FIG. 7 is a graph of experimental data showing the relationship between the guide shape of the curved reversal part and the transport distance required for lateral registration correction.
FIG. 8 is a cross-sectional view illustrating a configuration of an image forming apparatus according to a second embodiment of the present invention.
FIG. 9 is an enlarged view for explaining a configuration of a bending reversing unit according to the second embodiment of the present invention.
FIG. 10 is a cross-sectional view illustrating a configuration of a conventional image forming apparatus.
FIG. 11 is a schematic configuration diagram of a lateral registration correction unit of a conventional image forming apparatus.
FIG. 12 is a diagram illustrating a lateral registration correction operation by a conventional image forming apparatus.
[Explanation of symbols]
3 Sheet re-conveying section
17 Roller after fixing
19 Second roller
23 Horizontal registration correction unit
24, 54 Reference plate
24a Reference plane
25 Horizontal registration correction roller
26 Rolling roller
27 Transport guide
40, 50 Curve reversal part
40a, 51 Inner guide
40b, 52 outer guide

Claims (6)

A lateral registration correction unit that corrects the position in the width direction of the sheet by rotating and bringing the sheet into contact with a regulating unit that regulates the side edge of the sheet;
Nipping and conveying means for nipping and conveying the sheet to the lateral registration correcting means;
A curved guide means that is disposed between the nipping and conveying means and the lateral registration correcting means, and guides the sheet by curving it;
With
2. The sheet conveying apparatus according to claim 1, wherein the curved guide means includes an inner guide member that is inscribed at one inner point with respect to an arc having a radius of 65 to 80 mm, and an outer guide member that is circumscribed at two outer points with respect to the arc. The lateral registration correcting means regulates the side edge of the sheet and corrects the sheet to a predetermined position in the width direction, and is arranged on the upstream side in the sheet conveying direction of the reference surface, and the reference surface from outside in the width direction A reference surface having a tapered surface continuous to
The sheet conveying apparatus according to claim 1, further comprising: a pair of conveying rollers configured to apply a conveying force to the sheet and rotate the sheet in a predetermined region in the width direction on the reference surface side. The sheet conveying apparatus according to claim 2, wherein the outer guide member is composed of two members circumscribing each outer point with respect to the arc. 4. The sheet conveying apparatus according to claim 1, further comprising a guide position switching unit configured to switch the position of the inner guide member or the outer guide member to at least two or more positions. 5. . A sheet conveying device according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet conveyed by the sheet conveying apparatus. 6. The sheet feeding device according to claim 5, wherein the sheet feeding device is provided in a sheet refeeding conveyance unit that conveys the sheet formed on the first surface again to the image forming unit in order to form an image on both sides of the sheet. Image forming apparatus.

Images