JP2014088263A - Transport device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transport device and an image forming apparatus, performing skew correction and lateral registration correction for a record medium with high accuracy without lowering the productivity of the device.SOLUTION: First detection means 35 is installed for detecting the oblique positional deviation amount of a record medium P, and second detection means 36 is installed for detecting the width direction positional deviation amount of the record medium P. A holding roller 31, which is formed to turn in the oblique direction on the basis of the detection result of the first detection means 35, and formed to move in the width direction on the basis of the detection result of the second detection means 36, is installed to correct the oblique positional deviation amount of the record medium P and correct the width direction positional deviation amount of the record medium P while carrying the record medium P in the holding state.

Description

  The present invention relates to a conveyance device that conveys a recording medium, and an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine or an offset printing machine provided with the same, and more particularly to a recording medium in a conveyance path. The present invention relates to a conveyance device that performs lateral registration correction and skew correction, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, after correcting a positional deviation (skew) in a diagonal direction of a recording medium in a conveyance path, the width direction of the recording medium (a direction perpendicular to the conveyance direction). There is known a technique for correcting the deviation of the position (hereinafter referred to as “lateral resist” as appropriate) to a regular position (see, for example, Patent Document 1).

  Specifically, in Patent Document 1, the recording medium conveyed along the conveyance path by a plurality of conveyance roller pairs hits the stopper and is subjected to skew correction (skew correction). After that, the recording medium in contact with the stopper moves in the width direction while being pinched by the pair of horizontal registration rollers disposed on the upstream side of the stopper to correct the horizontal registration. Become. Thereafter, the recording medium in which the lateral registration is corrected is conveyed toward the image forming unit.

  On the other hand, in Patent Document 2, a driving roller connected to a coupler and a nip forming roller that presses against the driving roller are provided at both ends in the width direction, and they are moved in the width direction and driven at both ends. There has been disclosed a technique for simultaneously performing skew correction and lateral registration correction of a recording medium by adjusting the speed of a roller.

In the technique of Patent Document 1, since the recording medium is temporarily stopped so as to abut against the stopper and the skew feeding correction is performed, the lateral registration correction of the recording medium is performed. I was sorry.
On the other hand, since the technique of Patent Document 2 simultaneously performs the skew feeding correction and the lateral registration correction of the recording medium while transporting the recording medium without stopping, the productivity of the apparatus is reduced. Absent. However, when thin paper is passed as the recording medium, the recording medium may be bent by adjusting the speed of the driving rollers at both ends, or the recording medium having a low surface friction coefficient (for example, when printing on both sides) When the image is formed on one side of the recording medium), slip adjustment may occur between the recording medium and the roller by adjusting the speed of the driving roller at both ends. In some cases, the accuracy of the skew correction of the medium is lowered.

  The present invention has been made to solve the above-described problems, and is capable of carrying out skew correction and lateral registration correction of a recording medium with high accuracy without reducing the productivity of the apparatus. Another object is to provide an image forming apparatus.

  A transport apparatus according to a first aspect of the present invention is a transport apparatus that transports a recording medium in a transport path, and detects a positional deviation amount of the recording medium transported in the transport path in an oblique direction. A detection means, a second detection means for detecting the amount of positional deviation in the width direction of the recording medium conveyed in the conveyance path, and a rotation in an oblique direction based on the detection result of the first detection means. In addition, the recording medium is formed so as to be movable in the width direction based on the detection result of the second detection means, and corrects the positional deviation amount of the recording medium in the oblique direction while transporting the recording medium while sandwiching the recording medium. And a sandwiching roller that corrects the positional deviation amount in the width direction.

  The present invention corrects the positional displacement amount of the recording medium in the oblique direction while conveying the recording medium while being sandwiched by the sandwiching roller, corrects the positional displacement amount of the recording medium in the width direction, and records by the first sandwiching roller. The positional deviation amount in the oblique direction of the recording medium is corrected while being conveyed while the medium is sandwiched, and then the positional deviation amount in the width direction of the recording medium is conveyed while being conveyed while being sandwiched by the second clamping roller. It is corrected. Accordingly, it is possible to provide a transport device and an image forming apparatus in which the skew correction and the lateral registration correction of the recording medium are performed with high accuracy without reducing the productivity of the apparatus.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows a conveying apparatus. It is a top view which shows a part of conveying apparatus. It is a perspective view which shows the principal part of a conveying apparatus. It is the schematic which shows operation | movement of a conveying apparatus. FIG. 6 is a schematic diagram illustrating the operation of the conveyance device following FIG. 5. It is the schematic which shows operation | movement of the conveying apparatus as a modification. FIG. 8 is a schematic diagram illustrating an operation of the conveyance device following FIG. 7. It is the schematic which shows operation | movement of the conveying apparatus in Embodiment 2 of this invention. FIG. 10 is a schematic diagram illustrating an operation of the conveyance device following FIG. 9. It is the schematic which shows operation | movement of the conveying apparatus as a modification. FIG. 12 is a schematic diagram illustrating an operation of the transport device following FIG. 11.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
The first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a copying machine as an image forming apparatus, 2 an original reading unit that optically reads image information of an original D, and 3 an exposure light L based on image information read by the original reading unit 2. Is exposed to the photosensitive drum 5, 4 is an image forming unit for forming a toner image (image) on the photosensitive drum 5, and 7 is a toner image formed on the photosensitive drum 5 on the recording medium P. A transfer section (image forming section) for transferring, 10 a document transport section for transporting a set document D to the document reading section 2, and 12 to 14 a paper feed section for storing a recording medium P (sheet) such as transfer paper. (Paper feed cassette), 20 is a fixing device for fixing an unfixed image on the recording medium P, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, and 30 is recording. A transport device 45 for transporting the medium P along the transport path, Part 7 timing roller as conveying rollers for conveying the recording medium P toward the (image forming section) shows.

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus will be described.
First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the conveyance roller of the document conveyance unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). An exposure light L (laser light) based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in the drawing, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed.
Thereafter, the image formed on the photosensitive drum 5 is transferred onto the recording medium P conveyed by the timing roller 45 serving as a conveying roller pair in the transfer unit 7 serving as an image forming unit.

On the other hand, referring to FIGS. 1 and 2, the recording medium P conveyed to the transfer unit 7 (image forming unit) operates as follows.
First, one of the plurality of paper feeding units 12 to 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the paper feeding unit 12 provided in the main body 1 is selected. )
Then, the uppermost sheet of the recording medium P stored in the paper feed unit 12 is directed by the paper feed roller 41 toward the curved conveyance path where the first conveyance roller pair 42 and the second conveyance roller pair 43 are installed. Be fed.

  Thereafter, the recording medium P passes through the curved conveyance path through the position of the merging portion X (the portion where the conveyance paths from the two paper feeding units 13 and 14 installed outside the apparatus main body 1 merge). The third conveying roller pair 44 and the linear conveying path in which the aligning portion 51 is installed are passed to reach the position of the timing roller 45 (fourth conveying roller pair). Then, the recording medium P that has reached the position of the timing roller 45 is conveyed toward the transfer unit 7 (image forming unit) at the same timing in order to align with the image formed on the photosensitive drum 5. The

After the transfer process, the recording medium P passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The recording medium P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. The The recording medium P on which the image has been fixed is delivered from between the fixing roller 21 and the pressure roller 22 (a nip portion) and then discharged from the image forming apparatus main body 1.
Thus, a series of image forming processes is completed.

Here, referring to FIG. 2, the image forming apparatus 1 according to the first embodiment can feed the recording medium P from the three paper feeding units 12 to 14 toward the transfer unit 7 (image forming unit). It is configured.
Further, the conveyance roller pairs 42 to 45 (including a conveyance roller pair that is not attached with a symbol) installed in the conveyance device 30 are all driving rollers (rollers that are rotationally driven by a driving mechanism (not shown)). And a driven roller (a roller that is driven to rotate by frictional resistance with the driving roller), and is configured to be able to convey the recording medium P while being sandwiched between the two rollers.

  Here, the conveyance from the junction X where the conveyance path from the first sheet feeding unit 12 and the conveyance path from the second and third sheet feeding units 13 and 14 merge to the position of the timing roller 45 is performed. As the path, a linear transport path formed in a substantially straight line along the transport direction of the recording medium P is provided. This linear transport path is formed by a linear transport guide plate (not shown) (installed so as to sandwich the front and back surfaces of the transported recording medium P), and the third transport roller pair 44 along the transport direction. The skew detection sensor 35 (first detection means), the clamping roller 31 (horizontal registration / skew correction roller), the CIS 36 (second detection means), the timing roller 45, and the paper detection sensor 37 (third detection means) are installed. Has been. The third transport roller pair 44, the sandwiching roller 31 and the timing roller 45 are all roller pairs composed of a driving roller and a driven roller, and transport the recording medium P while being sandwiched between two rollers. . The sandwiching roller 31 performs an alignment operation between skew correction (correction for a positional deviation in the oblique direction with respect to the conveyance direction) and lateral registration correction (correction for a positional deviation in the width direction). This will also function as the matching unit 51, which will be described in detail later.

Next, with reference to FIG. 2 to FIG. 6, the characteristic transport device 30 in the first embodiment will be described in detail.
Hereinafter, the configuration in the transport path from the junction X to the transfer unit 7 (image forming unit) and the operations performed there will be mainly described.
2 and 3, the conveyance device 30 includes a third conveyance roller pair 44, along a linear conveyance path of the recording medium P (a conveyance path from the merging portion X to the transfer portion 7). A skew detection sensor 35 as a first detection means, a clamping roller 31 (horizontal registration / skew correction roller), a CIS 36 (contact image sensor) as a second detection means, a timing roller 45, and a third detection means A paper detection sensor 37 is installed.

  Here, the sandwiching roller 31 is a roller pair having a roller portion divided into a plurality of parts in the width direction, and includes a driving roller 31a rotated by a driving motor 61 (see FIG. 4), and a driving roller 31a. And a driven roller 31b that rotates following the rotation. Further, the sandwiching roller 31 is configured such that the roller pair can be contacted and separated by a separation mechanism (not shown). That is, the sandwiching roller 31 is formed to be separable so as to be able to switch between a state in which the recording medium P is sandwiched and a state in which the recording medium P is not sandwiched, and is configured to be able to transport the recording medium P by rotating.

Further, the sandwiching roller 31 is formed so as to be able to rotate in an oblique direction (rotation in the direction of the broken line double arrow W in FIG. 3) and in the width direction (in the direction of the broken line arrow S in FIG. 3). It is formed so that it can move to.
Specifically, referring to FIG. 4, the sandwiching roller 31 (the driving roller 31 a and the driven roller 31 b) is rotated by the holding portion 72 that is rotatably held around the shaft portion 71 a with respect to the base portion 71. Supported as possible. A drive motor 61 that rotationally drives the drive roller 31 a is also held by the holding unit 72.
In addition, a rack gear 71 b that meshes with a pinion gear formed on the motor shaft 62 a of the first motor 62 is formed at the bottom of the base portion 71. Thereby, the pinching roller 31 is moved in the width direction (the direction of the double arrow in FIG. 4, the vertical direction in FIG. 2, and the vertical direction in FIG. 3) by the forward and reverse rotation of the first motor 62. Will move.
Further, a second motor 63 is installed on one end side in the width direction of the base portion 71, and a gear formed on the motor shaft 63 a of the second motor 63 is formed on one end side in the width direction of the holding portion 72. It is formed so as to mesh with the gear 72a. As a result, when the second motor 63 is rotated in the forward / reverse direction, the pinching roller 31 is rotated about the shaft portion 71a (rotation in the direction of the double arrow in FIG. 4 and rotation in the W direction in FIG. 3). ). In the first embodiment, the sandwiching roller 31 is configured to rotate about the center position in the width direction. However, the sandwiching roller 31 rotates about the position on the end side in the width direction. It can also be configured as follows.

The sandwiching roller 31 corrects the positional displacement amount of the recording medium in the oblique direction based on the detection result of the skew detection sensor 35 (first detection means) while transporting the recording medium P in the sandwiched state. Become. That is, the sandwiching roller 31 functions as means for performing skew correction (skew correction) of the recording medium P by displacing the recording medium P conveyed in the conveyance path in an oblique direction.
Further, the nipping roller 31 corrects the positional displacement amount in the width direction of the recording medium P based on the detection result of the CIS 36 (second detecting means) while transporting the recording medium P in the nipped state. In other words, the pinching roller 31 also functions as means for correcting the lateral registration of the recording medium P by displacing the recording medium P conveyed in the conveyance path in the width direction.

  Here, the third transport roller pair 44 is installed at a position upstream of the sandwiching roller 31 (upstream in the transport direction). The third conveying roller pair 44 is formed so as to be able to convey the recording medium P by rotating in a state in which the recording medium P is sandwiched, and is separated so as to be able to switch between a state in which the recording medium P is sandwiched and a state in which the recording medium P is not sandwiched. It is a pair of conveyance rollers formed so as to be possible. When the recording medium P reaches the position of the sandwiching roller 31 and is sandwiched and transported by the sandwiching roller 31, the third transport roller pair 44 is switched from the state in which the recording medium P is sandwiched to the state in which it is not sandwiched. become.

  In the first embodiment, the clamping roller 31 has a larger frictional force between the recording medium P and the third conveying roller pair 44 when the recording medium P is nipped and conveyed. It is formed to become. Specifically, the friction coefficient (or / and the pressure contact force) of the roller portions of the driving roller 31a and the driven roller 31b in the pinching roller 31 is determined by the driving roller and the driven roller in the third conveying roller pair 44, respectively. It is formed so as to be larger than the friction coefficient (or / and the pressure contact force) of the roller portion. As a result, even if the recording medium P is transported while being sandwiched between the sandwiching roller 31 and the third transporting roller pair 44, the transporting force (holding force) by the sandwiching roller 31 has priority. Therefore, it is possible to suppress a problem that the accuracy of the skew correction and the lateral registration correction of the recording medium P performed by the sandwiching roller 31 is lowered.

The timing roller 45 (fourth conveyance roller pair) is located downstream of the conveyance path with respect to the sandwiching roller 31 (downstream in the conveyance direction) and upstream of the conveyance path with respect to the transfer unit 7 (image forming unit). The pair of transport rollers disposed at the position on the side of the recording medium P is rotated in a state where the recording medium P is nipped, and the recording medium P (the recording medium P after being subjected to the skew correction and the lateral registration correction by the nipping roller 31) Is conveyed toward the image forming unit.
Here, the timing roller 45 is connected to a rotation speed variable drive motor (not shown), and is formed so that the conveyance speed of the recording medium P can be varied. When the timing at which the recording medium P is conveyed to the position of the timing roller 45 is detected by the paper detection sensor 37 (photo sensor) as the third detection means (the recording medium P is conveyed to the position of the timing roller 45). When the state in which the recording medium P is sandwiched by the timing roller 45 is detected), the sandwiching roller 31 is separated so as not to sandwich the recording medium P, and further, based on the detection result (detection timing) of the paper detection sensor 37. Thus, the conveyance speed by the timing roller 45 is varied. That is, the conveyance speed by the timing roller 45 so that the timing at which the recording medium P is conveyed to the transfer unit 7 by the timing roller 45 and the timing at which the image formed on the photosensitive drum 5 reaches the transfer unit 7 are matched. (The conveyance timing of the recording medium P conveyed toward the image forming unit is adjusted). Thereby, the vertical registration correction (position shift correction in the conveyance direction) of the recording medium P can be performed without stopping the conveyance of the recording medium P by the timing roller 45.
Note that the timing roller 45 causes a linear velocity difference with the photosensitive drum 5 immediately after the leading edge of the recording medium P reaches the image forming unit, and thus an image transferred onto the recording medium P is not distorted. Thus, the conveyance speed is varied (the conveyance speed is varied so that the linear velocity ratio with respect to the photosensitive drum 5 is 1).

The skew detection sensor 35 as the first detection means detects the amount of positional deviation (skew amount) in the oblique direction of the recording medium P conveyed in the conveyance path.
Specifically, with reference to FIG. 3, the skew detection sensor 35 is installed on the upstream side of the conveyance path with respect to the sandwiching roller 31 and on the downstream side of the conveyance path with respect to the third conveyance roller pair 44. Yes. The skew detection sensor 35 is two photosensors (consisting of a light emitting element such as an LED and a light receiving element such as a photodiode) installed at positions equidistant from the center position in the width direction. The skew amount β (skew amount) of the recording medium P is detected by detecting the deviation of the timing when the leading end of the recording medium passes. In the first embodiment, based on the detection result of the skew detection sensor 35, skew correction is performed while the recording medium P is sandwiched and conveyed by the sandwiching roller 31.
As a specific example, referring to FIG. 3, the recording medium P is only in the positive direction (the positive direction of the rotation direction) by an angle β with respect to the reference position indicated by the alternate long and short dash line (the normal position without skew). When the skew detection state is detected by the skew detection sensor 35, the control unit sets the positional deviation amount β as a correction amount and moves the sandwiching roller 31 in the reverse direction while sandwiching the recording medium P by the sandwiching roller 31. (The reverse direction of the rotation direction and the clockwise direction in FIG. 3) is rotated by an angle β.

Referring to FIG. 3, the CIS 36 as the second detection means is installed on the downstream side of the conveyance path with respect to the sandwiching roller 31 and on the upstream side of the conveyance path with respect to the timing roller 45. The CIS 36 includes a plurality of photosensors (consisting of a light emitting element such as an LED and a light receiving element such as a photodiode) arranged in the width direction, and is a side end portion on one end side in the width direction of the recording medium P. By detecting the position of Pa (edge portion), the shift amount of the lateral resist is detected. That is, the CIS 36 (second detection means) detects the amount of positional deviation in the width direction of the recording medium P that is transported in the transport path of the transport device 30. Then, based on the detection result of the CIS 36, the lateral registration correction by the sandwiching roller 31 is performed.
In the first embodiment, as shown in FIG. 3, the CIS 36 is installed only on one end in the width direction and the position of the side end Pa on one end in the width direction of the recording medium P is detected. It is also possible to detect the positions of the respective side end portions at both ends in the width direction of the recording medium P by installing over the entire direction.

Based on the detection result of the CIS 36 (second detection means), the recording roller P is moved in the width direction while the recording medium P is sandwiched and transported by the sandwiching roller 31, and the recording medium P transported in the transport path. The positional deviation (lateral registration) in the width direction is corrected.
As a specific example, referring to FIG. 3, the recording medium P is positioned at one end side in the width direction (below the lower side of FIG. When the CIS 36 detects that the position is shifted by the distance α, the control unit sets the position shift amount α as a correction amount, and the recording medium P is sandwiched and conveyed by the sandwiching roller 31. The roller 31 is moved by a distance α to the other end in the width direction (upward in FIG. 3).

As described above, in the first embodiment, the sandwiching roller 31 does not stop the conveyance of the recording medium P, and the detection result of the skew detection sensor 35 (first detection means) in the state of sandwiching the recording medium P. By rotating in the oblique direction based on this, the positional displacement amount in the oblique direction of the recording medium P is corrected, and the width of the recording medium P is moved by moving in the width direction based on the detection result of the CIS 36 (second detection means). This corrects the amount of positional deviation in the direction. That is, in the first embodiment, the skew amount of the recording medium P is detected by the skew detection sensor 35 in a state where the pinching roller 31 is rotated so that the recording medium P can be conveyed, and the recording medium P is detected based on the detection result. Next, the lateral registration correction of the recording medium P is detected by the CIS 36, and the lateral registration correction of the recording medium P is performed based on the detection result.
As a result, the productivity of the apparatus can be significantly improved as compared with the case where the conveyance of the recording medium P is stopped and the skew feeding correction or the lateral registration correction is performed. Further, when skew correction or lateral registration correction is performed, there is no difference in linear velocity between a plurality of roller portions installed in the width direction in the pinching roller 31, so that the recording medium P having a low friction coefficient on thin paper or the surface. Even when the paper is passed, the recording medium P is not bent or slipped.

Further, in the first embodiment, after the skew feeding correction / lateral registration correction described above is performed, when the recording medium P is clamped by the timing roller 45, the clamping roller 31 does not clamp the recording medium P. Are spaced apart.
As a result, the conveyance process toward the image forming unit by the timing roller 45 is surely performed, and the operation of the alignment unit 51 for the recording medium P to be conveyed next is quickly prepared.

Hereinafter, an example of the operation of the transport apparatus 30 configured as described above will be described in detail with reference to FIGS. 5 and 6.
5 (A1) to (D1) and FIGS. 6 (A1) to (C1) are top views showing the operation of the conveying device 30 in that order, and FIG. 5 (A2) to (D2). FIGS. 6A2 to 6C2 are side views of the transfer device 30 corresponding to the operations of FIGS. 5A1 to 5D1 and 6A1 to 6C1, respectively.
First, as shown in FIGS. 5A1 and 5A2, the recording medium P fed from the paper feed unit 12 is nipped and conveyed toward the position of the nipping roller 31 by the third conveying roller pair 44. (Conveyance in the direction of white arrow). When the recording medium P reaches the position of the skew detection sensor 35 (first detection means), the skew detection sensor 35 detects the skew amount β of the recording medium P.

  Thereafter, as shown in FIGS. 5B1 and 5B2, immediately before the leading end of the recording medium P reaches the sandwiching roller 31, the rotational drive of the sandwiching roller 31 (rotation drive in the direction of the arrow in the figure) is started. Then, when the recording medium P is nipped and conveyed by the nipping roller 31, the third conveying roller pair 44 moves away from the conveying path so that the recording medium P is not nipped (indicated by the solid arrow). The timing at which the leading end of the recording medium P reaches the pinching roller 31 is determined by the timing at which the leading end of the recording medium P is detected by the skew detection sensor 35, the conveyance speed of the recording medium P, and the position of the skew detection sensor 35. Is calculated by a calculation unit (control unit) based on the distance from the position to the position of the pinching roller 31.

Then, as shown in FIGS. 5C1 and 5C2, the sandwiching roller 31 has a shaft portion so as to cancel the skew amount β detected by the skew detection sensor 35 while sandwiching and transporting the recording medium P. It rotates around 71a. Thus, the skew of the recording medium P is corrected.
Thereafter, as shown in FIGS. 5D1 and 5D2, the recording medium P (which has been skew-corrected) is sandwiched and conveyed by the sandwiching roller 31 and the leading end thereof is CIS 36 (second The position of the detecting means) is reached, and the position shift amount α of the lateral resist is detected at that position.

And as shown to FIG. 6 (A1) and (A2), the clamping roller 31 moves to the width direction based on the detection result of CIS36. That is, the displacement amount of the lateral registration of the recording medium P is detected by the CIS 36, and the sandwiching roller 31 moves in the width direction so as to cancel the displacement amount. Thus, the recording medium P is conveyed toward the timing roller 45 while performing lateral registration correction.
After that, as shown in FIGS. 6B1 and 6B2, when the paper detection sensor 37 detects that the recording medium P has reached the position of the timing roller 45, the recording medium P is sandwiched and conveyed. The clamping roller 31 moves away in a direction (a solid arrow direction) in which the conveyance path is opened and the recording medium P is not clamped.

Thereafter, as shown in FIGS. 6C1 and 6C2, the rotational speed of the timing roller 45 (the conveyance speed of the recording medium P until reaching the transfer unit 7 is adjusted so as to be synchronized with the image on the photosensitive drum 5). ) Is changed, and the recording medium P is conveyed toward the transfer unit 7 (image transfer unit). Thus, the image is transferred to a desired position on the recording medium P.
At this time, the clamping roller 31 that has been rotated in the oblique direction and moved in the width direction in order to perform the skew correction and the lateral registration correction is provided for the recording medium P to be transported next, and serves as a reference as a home position. It is rotated and moved to the position (the position shown in FIG. 5A1). Further, after the rear end of the recording medium P passes the position of the sandwiching roller 31, the sandwiching roller 31 that has been separated is returned to the contact state (the state of FIG. 5 (A2)).

In the first embodiment, the sandwiching roller 31 rotates in an oblique direction based on the detection result of the skew detection sensor 35 (first detection means) while sandwiching the recording medium P, thereby recording the recording medium. In addition to correcting the positional deviation amount of P in the oblique direction, it operates to correct the positional deviation amount of the recording medium P in the width direction by moving in the width direction based on the detection result of the CIS 36 (second detection means). .
On the other hand, as a modification, the clamping roller 31 rotates in an oblique direction from the first reference position based on the detection result of the skew detection sensor 35 (first detection means) before the recording medium P is clamped. At the same time, after moving in the width direction from the second reference position based on the detection result of the CIS 36 (second detection means), it is rotated in an oblique direction so as to return to the first reference position with the recording medium P being sandwiched. The correction of the positional displacement amount in the oblique direction of the recording medium P and the operation of correcting the positional displacement amount in the width direction of the recording medium P by moving in the width direction so as to return to the second reference position. Good.

7 and 8 show an example of the operation of the transport apparatus 30 as such a modification.
7 (A1) to (C1) and FIGS. 8 (A1) to (B1) are top views showing the operation of the conveying device 30 in that order, and FIG. 7 (A2) to (C2). FIGS. 8A2 to 8B2 are side views of the transfer device 30 corresponding to the operations of FIGS. 7A1 to 7C1 and 8A1 to 8B1, respectively.
Referring to FIGS. 7A1 and 7A2 and the like, in the transport apparatus 30 as a modified example, the CIS 36 as the second detection means is on the upstream side of the skew detection sensor 35 and the third transport roller pair 44 Except for the point installed on the downstream side, the configuration is almost the same as that of the transfer device 30 in the first embodiment.

First, as shown in FIGS. 7A1 and 7A2, the recording medium P fed from the paper feeding unit 12 is nipped and conveyed toward the position of the nipping roller 31 by the third conveying roller pair 44. (Conveyance in the direction of white arrow). At this time, the sandwiching roller 31 has a rotation direction position at a first reference position (a normal position corresponding to the recording medium P without skew), and a width direction position at a second reference position (horizontal). It is a normal position corresponding to the recording medium P with no registration position misalignment).
Then, when the recording medium P reaches the position of the CIS 36 (second detection means), the lateral registration positional displacement amount α of the recording medium P is detected by the CIS 36. Further, when the recording medium P reaches the position of the skew detection sensor 35 (first detection means), the skew detection sensor 35 detects the skew amount β of the recording medium P. Note that the amount of positional deviation detected directly by the CIS 36 is in a state where the recording medium P is skewed, so that the positional deviation is detected from the detection result detected by the skew detection sensor 35 and the position of the CIS 36. Based on the distance to the position of the row detection sensor 35, etc., the position registration amount α of the lateral registration when there is no skew is obtained by the calculation unit (control unit).

Thereafter, as shown in FIGS. 7B1 and 7B2, the sandwiching roller 31 is shifted by the angle β around the shaft portion 71a in the same inclination direction in accordance with the skew amount β detected by the skew detection sensor 35. While rotating from the first reference position, it shifts from the second reference position by the distance α in the same width direction in accordance with the positional deviation amount α detected by the CIS 36.
Then, as shown in FIGS. 7C1 and 7C2, the rotation driving of the nipping roller 31 (rotation driving in the direction of the arrow in the figure) is started immediately before the leading end of the recording medium P reaches the nipping roller 31. Then, when the recording medium P is nipped and conveyed by the nipping roller 31, the third conveying roller pair 44 moves away from the conveying path so that the recording medium P is not nipped (indicated by the solid arrow). Note that the timing at which the leading end of the recording medium P reaches the pinching roller 31 is the timing at which the leading end of the recording medium P is detected by the skew detection sensor 35 or the CIS 36, the conveyance speed of the recording medium P, and the skew detection sensor 35. Or the distance from the position of the CIS 36 to the position of the pinching roller 31, etc.

As shown in FIGS. 8A1 and 8A2, the sandwiching roller 31 has a shaft portion so as to cancel the skew amount β detected by the skew detection sensor 35 while sandwiching and transporting the recording medium P. While rotating so as to return to the first reference position around 71a, it moves in the width direction so as to return to the second reference position so as to cancel out the positional shift amount α detected by the CIS 36. In this way, the recording medium P is conveyed toward the timing roller 45 while performing skew feeding correction and lateral registration correction.
Thereafter, as shown in FIGS. 8B1 and 8B2, when the paper detection sensor 37 detects that the recording medium P has reached the position of the timing roller 45, the recording medium P is held and conveyed. The clamping roller 31 moves away in a direction (a solid arrow direction) in which the conveyance path is opened and the recording medium P is not clamped.

Thereafter, the rotational speed of the timing roller 45 (the conveyance speed of the recording medium P until reaching the transfer unit 7) is varied so that the timing is synchronized with the image on the photosensitive drum 5, and the recording medium P is transferred to the transfer unit 7 ( It is conveyed toward the image transfer unit. Thus, the image is transferred to a desired position on the recording medium P.
At this time, the nipping roller 31 is positioned at the first reference position and the second reference position in preparation for the skew correction and the lateral registration correction of the recording medium P to be conveyed next. Then, after the rear end of the recording medium P passes through the position of the sandwiching roller 31, the sandwiching roller 31 that has been separated is returned to the contact state (the state of FIG. 7 (A2)).
Also in the transfer apparatus 30 as such a modification, the same effect as that of the first embodiment can be obtained.

  As described above, in the first embodiment, while the recording medium P is transported in a state of being sandwiched by the sandwiching roller 31, the positional displacement amount of the recording medium P in the oblique direction is corrected and the width of the recording medium P is corrected. The amount of misalignment is corrected. As a result, the skew correction and the lateral registration correction of the recording medium P can be performed with high accuracy without reducing the productivity of the transport device 30 (image forming apparatus 1).

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 9 is a schematic diagram showing the operation of the transport apparatus in the second embodiment, and FIG. 10 is a schematic diagram showing the operation of the transport apparatus following FIG. FIG. 11 is a schematic view showing the operation of the transfer apparatus as a modified example, and FIG. 12 is a schematic view showing the operation of the transfer apparatus following FIG.
The conveyance device according to the second embodiment is provided with a first clamping roller 32 that performs skew correction and a second sandwiching roller 33 that performs lateral registration correction, which are separately provided with skew correction and lateral registration correction. This is different from that of the first embodiment in which this is performed by one clamping roller 31.

Referring to FIGS. 9A1 and 9A2 and the like, the conveying device 30 according to the second embodiment is arranged in the conveying path from the position of the skew detection sensor 35 to the position of the CIS 36 in place of the nipping roller 31. Except for the point that the first clamping roller 32 and the second clamping roller 33 are installed, the configuration is almost the same as the conveying device 30 in the first embodiment.
The first clamping roller 32 and the second clamping roller 33 are a pair of rollers each having a roller portion divided into a plurality of parts in the width direction, and are driving rollers that are rotationally driven by a driving motor (not shown). And a driven roller that rotates following the rotation of the driving roller. In addition, the two sandwiching rollers 32 and 33 are configured such that the roller pair can be contacted and separated by a separation mechanism (not shown). That is, the two sandwiching rollers 32 and 33 are formed to be separable so as to be able to switch between a state in which the recording medium P is sandwiched and a state in which the recording medium P is not sandwiched, and is formed so as to be able to transport the recording medium P by rotating. Has been.

The first clamping roller 32 is formed to be rotatable in an oblique direction based on the detection result of the skew detection sensor 35 (first detection means), and performs recording while conveying the recording medium P in a sandwiched state. It functions as a skew correction roller that corrects the positional deviation amount of the medium P in the oblique direction. On the other hand, the second clamping roller 33 is disposed at a position downstream of the first clamping roller 32 in the transport path, and moves in the width direction based on the detection result of the CIS 36 (second detection means). A lateral direction that is formed so as to correct the positional displacement amount in the width direction of the recording medium P while being transported in a state where the recording medium P is sandwiched after the positional displacement amount in the oblique direction is corrected by the first clamping roller 32. It functions as a registration correction roller.
In particular, in the second embodiment, the first sandwiching roller 32 rotates in an oblique direction based on the detection result of the skew detection sensor 35 while the recording medium P is sandwiched, so that the oblique direction of the recording medium P is reached. Correct the amount of misalignment. Further, the second sandwiching roller 33 moves in the width direction based on the detection result of the CIS 36 in a state where the recording medium P that has been nipped by the first sandwiching roller 32 is sandwiched, thereby moving the second sandwiching roller 33 in the width direction of the recording medium P. Correct the displacement.
The mechanism for rotating the first sandwiching roller 32 around the shaft portion 32a and the mechanism for shifting the second sandwiching roller 33 in the width direction are the same as in the first embodiment. Since a mechanism that rotates around the center and a mechanism that shifts in the width direction can be referred to, a detailed description thereof will be omitted.

  In the second embodiment, the first sandwiching roller 32 has a frictional force generated between the first sandwiching roller 32 and the recording medium P when the recording medium P is sandwiched and transported compared to that of the third transporting roller pair 44. It is formed to be large. Specifically, the friction coefficient (or / and the pressure contact force) of the respective roller portions of the driving roller 31a and the driven roller 31b in the first clamping roller 32 is determined by the driving roller and the driven roller in the third conveying roller pair 44. It is formed so as to be larger than the friction coefficient (or / and the pressure contact force) of each roller part. As a result, even if the recording medium P is transported in a state of being sandwiched between the first sandwiching roller 32 and the third transporting roller pair 44, the transport force (sandwiching) by the first sandwiching roller 32 occurs. Therefore, the problem that the accuracy of the skew correction of the recording medium P performed by the first clamping roller 32 is reduced can be suppressed.

9 and 10 show an example of the operation of the transport device 30 in the second embodiment.
FIGS. 9A1 to 9C1 and FIGS. 10A1 to 10C1 are top views showing the operation of the conveying device 30 in the order shown in FIGS. 9A2 to 9C2. FIGS. 10A2 to 10C2 are side views of the transfer device 30 corresponding to the operations of FIGS. 9A1 to 9C1 and 10A1 to 10C1, respectively.

  First, as shown in FIGS. 9A1 and 9A2, the recording medium P fed from the paper feeding unit 12 is nipped and conveyed toward the position of the first nipping roller 32 by the third conveying roller pair 44. Is done. When the recording medium P reaches the position of the skew detection sensor 35 (first detection means), the skew detection sensor 35 detects the skew amount β of the recording medium P.

  Thereafter, as shown in FIGS. 9B1 and 9B2, the first nipping roller 32 is driven to rotate immediately before the leading end of the recording medium P reaches the nipping roller 31 (rotation driving in the direction of the arrow in the figure). Is started, and when the recording medium P is nipped and conveyed by the first nipping roller 32, the third conveying roller pair 44 opens away from the conveying path and moves away in the direction not nipping the recording medium P.

9 (C1) and 9 (C2), the first sandwiching roller 32 cancels the skew amount β detected by the skew detection sensor 35 while sandwiching and transporting the recording medium P. It rotates around the shaft portion 32a. Thus, the recording medium P is sandwiched and conveyed toward the position of the second sandwiching roller 33 while skew correction is performed by the first sandwiching roller 32.
Then, as shown in FIGS. 10A1 and 10A2, the rotation of the second nipping roller 33 (rotation driving in the direction of the arrow in the figure) is performed immediately before the leading end of the recording medium P reaches the second nipping roller 33. .) Is started. The recording medium P (which has been skew-corrected) is nipped and conveyed by the first nipping roller 32 and the second nipping roller 33, and the leading end thereof is the position of the CIS 36 (second detecting means). Is reached, and the positional deviation amount α of the lateral resist is detected at that position.

Then, as shown in FIGS. 10B1 and 10B2, the second clamping roller 33 moves in the width direction based on the detection result of the CIS 36. That is, the displacement amount of the lateral registration of the recording medium P is detected by the CIS 36, and the second clamping roller 33 moves in the width direction so as to cancel the displacement amount. Thus, the recording medium P is conveyed toward the timing roller 45 while performing lateral registration correction.
At this time, the first clamping roller 32 moves away in a direction not to pinch the recording medium P by opening the conveyance path so as not to prevent the lateral registration correction by the second clamping roller 33. Further, the first clamping roller 32 that has been rotated in the oblique direction to perform the skew correction is provided in the recording medium P to be transported next, and the reference position (the position of FIG. 9 (A1)) that is the home position. ).

Thereafter, as shown in FIGS. 10C1 and 10C2, when the paper detection sensor 37 detects that the recording medium P has reached the position of the timing roller 45, the recording medium P is sandwiched and conveyed. The second clamping roller 33 moves away in a direction not to clamp the recording medium P by opening the conveyance path.
Thereafter, the rotational speed of the timing roller 45 (the conveyance speed of the recording medium P until reaching the transfer unit 7) is varied so that the timing is synchronized with the image on the photosensitive drum 5, and the recording medium P is transferred to the transfer unit 7 ( It is conveyed toward the image transfer unit. Thus, the image is transferred to a desired position on the recording medium P.
At this time, the second nipping roller 33 that has moved in the width direction in order to perform lateral registration correction is provided for the recording medium P to be transported next, and the reference position (the position of FIG. 9 (A1)) as the home position. ). Further, after the rear end of the recording medium P passes through the positions of the first and second clamping rollers 32 and 33, the respective clamping rollers 32 and 33 that are in the separated state are in contact with each other (FIG. 9A2). It is returned to the state.

  As a modification of the configuration of the conveying device 30 in the second embodiment, the first clamping roller 32 is based on the detection result of the skew detection sensor 35 (first detection means) before the recording medium P is clamped. After the recording medium P is rotated obliquely from the first reference position, the recording medium P is rotated in an oblique direction so as to return to the first reference position with the recording medium P being sandwiched, thereby correcting the positional displacement amount of the recording medium P in the oblique direction. can do. Furthermore, the second clamping roller 33 is clamped by the first clamping roller 32 after moving in the width direction from the second reference position based on the detection result of the CIS 36 (second detection means) before clamping the recording medium P. By moving the recording medium P in the width direction so as to return to the second reference position with the released recording medium P being sandwiched, the positional deviation amount in the width direction of the recording medium P can be corrected.

11 and 12 show an example of the operation of the transport apparatus 30 as such a modification.
11 (A1) to (C1) and FIGS. 12 (A1) to (C1) are top views showing the operation of the conveying device 30 in that order, and FIGS. 11 (A2) to (C2). FIGS. 12A2 to 12C2 are side views of the transfer device 30 corresponding to the operations of FIGS. 11A1 to 11C1 and 12A1 to 12C1, respectively.
Referring to FIGS. 11A1 and 11A2 and the like, in the transport apparatus 30 as a modification, the CIS 36 as the second detection means is on the upstream side of the skew detection sensor 35 and the third transport roller pair 44 Except for the point installed downstream, it is configured in substantially the same manner as the transfer device 30 in the second embodiment.

First, as shown in FIGS. 11A1 and 11A2, the recording medium P fed from the paper feeding unit 12 is nipped and conveyed toward the position of the first nipping roller 32 by the third conveying roller pair 44. Is done. At this time, the position of the first clamping roller 32 in the rotation direction is at the first reference position. Moreover, the position of the 2nd clamping roller 33 in the width direction exists in a 2nd reference position.
Then, when the recording medium P reaches the position of the CIS 36 (second detection means), the lateral registration positional displacement amount α of the recording medium P is detected by the CIS 36. Further, when the recording medium P reaches the position of the skew detection sensor 35 (first detection means), the skew detection sensor 35 detects the skew amount β of the recording medium P.
Thereafter, as shown in FIGS. 11B1 and 11B2, the first sandwiching roller 32 has an angle β around the shaft portion 71a in the same inclination direction according to the skew amount β detected by the skew detection sensor 35. Only from the first reference position. Furthermore, the second clamping roller 33 shifts from the second reference position by the distance α in the same width direction in accordance with the positional deviation amount α detected by the CIS 36.

  Then, as shown in FIGS. 11C1 and 11C2, the rotational driving of the first clamping roller 32 is started immediately before the leading end of the recording medium P reaches the first clamping roller 32, and the recording medium P is in the first state. When sandwiched and transported by the sandwiching roller 32, the third transport roller pair 44 opens the transport path and moves away in a direction not sandwiching the recording medium P. The first clamping roller 32 returns to the first reference position with the shaft portion 32a as the center so as to cancel the skew amount β detected by the skew detection sensor 35 while clamping and transporting the recording medium P. Rotate. Thus, the recording medium P is conveyed toward the second nipping roller 33 while skew correction is performed.

Thereafter, as shown in FIGS. 12A1 and 12A2, the rotational driving of the second clamping roller 33 is started immediately before the leading end of the recording medium P reaches the second clamping roller 33.
Then, as shown in FIGS. 12B1 and 12B2, the second clamping roller 33 moves in the width direction so as to return to the second reference position so as to cancel the positional deviation amount α detected by the CIS 36. . Thus, the recording medium P is conveyed toward the timing roller 45 while performing lateral registration correction. At this time, the first clamping roller 32 moves away in a direction not to pinch the recording medium P by opening the conveyance path so as not to prevent the lateral registration correction by the second clamping roller 33.

After that, as shown in FIGS. 12C1 and 12C2, when the paper detection sensor 37 detects that the recording medium P has reached the position of the timing roller 45, the recording medium P is sandwiched and conveyed. The second clamping roller 33 moves away in a direction not to clamp the recording medium P by opening the conveyance path.
Thereafter, the rotational speed of the timing roller 45 (the conveyance speed of the recording medium P until reaching the transfer unit 7) is varied so that the timing is synchronized with the image on the photosensitive drum 5, and the recording medium P is transferred to the transfer unit 7 ( It is conveyed toward the image transfer unit. Thus, the image is transferred to a desired position on the recording medium P.
At this time, the two sandwiching rollers 32 and 33 are positioned at the first reference position or the second reference position, respectively, in preparation for the skew correction or the lateral registration correction of the next transported recording medium P. Become. Then, after the rear end of the recording medium P passes through the positions of the two sandwiching rollers 32 and 33, the two sandwiching rollers 32 and 33 that are in the separated state are in contact with each other (in the state of FIG. 11 (A2)). Yes).
Also in the transfer apparatus 30 as such a modification, the same effect as that of the second embodiment can be obtained.

  As described above, in the second embodiment, the positional displacement amount of the recording medium P in the oblique direction is corrected while being transported while the recording medium P is sandwiched by the first sandwiching roller 32, and then the second The positional deviation amount in the width direction of the recording medium P is corrected while being conveyed while the recording medium P is sandwiched by the sandwiching rollers 33. As a result, the skew correction and the lateral registration correction of the recording medium P can be performed with high accuracy without reducing the productivity of the transport device 30 (image forming apparatus 1).

In each of the above-described embodiments, the present invention is applied to the conveyance device 30 installed in the monochrome image forming apparatus 1. However, the present invention is naturally applied to the conveyance device installed in the color image forming apparatus. The invention can be applied.
In each of the above embodiments, the present invention is applied to the conveyance device 30 installed in the electrophotographic image forming apparatus 1. However, the application of the present invention is not limited to this, and other methods. Even if it is a transport apparatus installed in the image forming apparatus (for example, an inkjet image forming apparatus or an offset printing machine), if it is a transport apparatus that performs skew correction and lateral registration correction, Of course, the present invention can also be applied to all of these transport apparatuses.
Even in those cases, the same effects as those of the above-described embodiments can be obtained.

Further, in each of the above embodiments, the present invention is applied to the transport device 30 disposed at a position upstream of the timing roller 45 in the transport direction, but the application of the present invention is limited to this. Of course, the present invention can be applied to all of the transfer devices as long as the transfer device is installed in other positions as long as it performs skew feeding correction and lateral registration correction. Can do.
Moreover, in each said embodiment, although this invention was applied with respect to the conveying apparatus 30 in which two conveyance paths merge in the junction part X, the conveyance apparatus in which three or more conveyance paths merge in the junction part X, Naturally, the present invention can also be applied to a transport apparatus that is formed of only one transport path without the junction X.
Further, in each of the above embodiments, the present invention is applied to the conveyance device 30 in which the three paper feeding units 12 to 14 are installed, but the conveyance in which two or less or four or more paper feeding units are installed. Of course, the present invention can also be applied to an apparatus.
Even in those cases, the same effects as those of the above-described embodiments can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

  In the present application, the “width direction” is defined as a direction orthogonal to the conveyance direction of the recording medium.

1 image forming apparatus (apparatus body),
30 transport device,
31 Nipping roller (horizontal registration / skew correction roller),
31a Driving roller,
31b driven roller,
32 1st clamping roller (skew correction roller),
33 Second clamping roller (horizontal registration correction roller),
35 Skew detection sensor (first detection means),
36 CIS (second detection means),
37 Paper detection sensor (third detection means),
44 Third conveying roller pair,
45 Timing roller (conveying roller pair),
51 alignment section,
P Recording medium (sheet).

JP 2008-50069 A JP 2008-239348 A

Claims (11)

A transport device for transporting a recording medium in a transport path,
First detection means for detecting the amount of positional deviation in the oblique direction of the recording medium conveyed in the conveyance path;
Second detection means for detecting the amount of positional deviation in the width direction of the recording medium conveyed in the conveyance path;
A state in which the recording medium is sandwiched while being formed so as to be rotatable in an oblique direction based on the detection result of the first detection means and movable in the width direction based on the detection result of the second detection means. A sandwiching roller that corrects the positional displacement amount of the recording medium in the oblique direction and corrects the positional displacement amount of the recording medium in the width direction while being conveyed by
A conveying apparatus comprising:   The sandwiching roller rotates in an oblique direction based on the detection result of the first detection means while sandwiching the recording medium, thereby correcting the positional displacement amount of the recording medium in the oblique direction, and the second The transport apparatus according to claim 1, wherein the positional deviation amount in the width direction of the recording medium is corrected by moving in the width direction based on a detection result of the detection unit.   The sandwiching roller rotates in an oblique direction from the first reference position based on the detection result of the first detection means before sandwiching the recording medium, and at the second reference position based on the detection result of the second detection means. After moving in the width direction, the recording medium is sandwiched and rotated in an oblique direction so as to return to the first reference position, thereby correcting the positional displacement amount of the recording medium in the oblique direction and the second medium. The transport apparatus according to claim 1, wherein the displacement in the width direction of the recording medium is corrected by moving in the width direction so as to return to the reference position. The recording medium is disposed at a position downstream of the conveyance path with respect to the nipping roller, and rotates in a state where the recording medium is nipped, thereby conveying the recording medium toward the image forming unit and increasing the conveyance speed of the recording medium. A pair of transport rollers formed to be variable;
Third detection means for detecting the timing at which the recording medium is conveyed to the position of the conveyance roller pair;
With
The clamping roller corrects the positional deviation in the oblique direction and the width direction of the recording medium conveyed in the conveyance path, and when the recording medium is nipped between the conveyance roller pair, So as not to be pinched,
The transport apparatus according to claim 1, wherein the transport speed of the transport roller pair is variable based on a detection result of the third detection unit. A transport roller pair disposed at a position upstream of the transport path with respect to the sandwiching roller and transporting the recording medium toward the sandwiching roller by rotating in a state of sandwiching the recording medium;
The nipping roller is formed so that a frictional force generated between the nipping roller and the recording medium when nipping and conveying the recording medium is larger than that of the conveying roller pair. The conveying apparatus in any one of Claims 1-4. A transport device for transporting a recording medium in a transport path,
First detection means for detecting the amount of positional deviation in the oblique direction of the recording medium conveyed in the conveyance path;
A first clamping roller that is formed so as to be rotatable in an oblique direction based on the detection result of the first detection means and that corrects the positional displacement amount of the recording medium in the oblique direction while transporting the recording medium in a sandwiched state. When,
Second detection means for detecting the amount of positional deviation in the width direction of the recording medium conveyed in the conveyance path;
The first clamping roller is disposed at a position downstream of the conveyance path, and is formed to be movable in the width direction based on the detection result of the second detection means, and by the first clamping roller A second clamping roller for correcting the positional deviation amount in the width direction of the recording medium while conveying the recording medium after the positional deviation amount in the oblique direction is corrected;
A conveying apparatus comprising: The first clamping roller corrects a positional displacement amount of the recording medium in an oblique direction by rotating in an oblique direction based on a detection result of the first detection unit in a state where the recording medium is sandwiched.
The second clamping roller moves in the width direction based on the detection result of the second detection means in a state in which the recording medium released from the clamping by the first clamping roller is clamped, so that the width of the recording medium is increased. The transport apparatus according to claim 6, wherein the amount of positional deviation is corrected. The first clamping roller rotates in an oblique direction from the first reference position based on the detection result of the first detection unit before clamping the recording medium, and then holds the recording medium in the state of clamping the recording medium. By correcting the displacement of the recording medium in the oblique direction by rotating in the oblique direction so as to return to the position,
The second nipping roller moves in the width direction from the second reference position based on the detection result of the second detection means before nipping the recording medium, and then the recording by which the nipping by the first nipping roller is released The transport apparatus according to claim 6, wherein the shift amount in the width direction of the recording medium is corrected by moving in the width direction so as to return to the second reference position in a state where the medium is sandwiched. The recording medium is transported toward the image forming unit by being rotated in a state where the recording medium is sandwiched and disposed at a position downstream of the transport path with respect to the second sandwiching roller. A pair of conveying rollers formed so that the speed can be varied;
Third detection means for detecting the timing at which the recording medium is conveyed to the position of the conveyance roller pair;
With
The second clamping roller clamps the recording medium after correcting the positional deviation in the width direction of the recording medium conveyed in the conveyance path and when the recording medium is clamped between the pair of conveyance rollers. Not to be separated,
The transport apparatus according to claim 6, wherein the transport speed of the transport roller pair is varied based on a detection result of the third detection unit. A conveyance roller that is disposed at a position upstream of the conveyance path with respect to the first clamping roller and conveys the recording medium toward the position of the first clamping roller by rotating in a state where the recording medium is clamped. With a pair
The first clamping roller is formed so that a frictional force generated between the first clamping roller and the recording medium when the recording medium is clamped and conveyed is larger than that of the pair of conveying rollers. The conveyance apparatus in any one of Claims 6-9.   An image forming apparatus comprising the conveying device according to claim 1.

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