JP2018016468A - Sheet conveyance device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveyance device and image formation apparatus which can improve the accuracy of positioning between an image and a sheet in the direction intersecting the sheet conveyance direction of the sheet.SOLUTION: A sheet conveyance device includes: guide means which has a reference surface and guides a sheet to the downstream side in the conveyance direction along a reference surface with the side portion on one side in the direction intersecting the conveyance direction of the sheet inserted thereto; width adjustment means which adjusts the width in the direction intersecting the conveyance direction in the state where the sheet is nipped and brings the side end of the sheet into contact with the reference surface; a first conveyance member pair with which the tip of the sheet is brought into contact on the downstream side in the sheet conveyance direction of the guide means, which corrects skew of the sheet, and conveys the sheet by nipping; a second conveyance member pair which conveys the sheet to the downstream side by nipping the sheet on the upstream side in the sheet conveyance direction of the guide means; a third conveyance member pair which conveys the sheet to the downstream side by nipping the sheet on the upstream side in the sheet conveyance direction of the second conveyance member pair; and movement means which moves the guide means in the direction intersecting the sheet conveyance direction on the basis of the sheet length along the conveyance direction of the sheet.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet conveying device and an image forming apparatus.

  A side guide having a side reference plane arranged in parallel to the sheet conveyance direction at one side end of the sheet conveyance path for conveying the sheet, and a predetermined inclination angle with respect to the sheet conveyance direction. Sheet skewing means for skewing the sheet to the side reference surface side while nipping the sheet, angle changing means for changing the inclination angle of the sheet skewing means with respect to the sheet conveying direction, and positional deviation of the sheet in the sheet conveying path In addition, there is known a sheet conveying apparatus including a control unit that controls driving of an angle changing unit based on at least one of pieces of sheet related information related to a sheet to be conveyed (Patent Document 1).

Japanese Patent Laid-Open No. 2002-60097

  The present invention provides a sheet conveying apparatus and an image forming apparatus that can improve the accuracy of alignment between an image and a sheet.

In order to solve the above-described problem, a paper conveying device according to claim 1
A guide unit having a reference surface and having a side portion on one side in a direction intersecting with the sheet conveyance direction inserted therein to guide the sheet to the downstream side in the conveyance direction along the reference surface;
Width-shifting means for width-shifting in a direction intersecting the transport direction in a state where the sheet is nipped, and abutting a side edge of the sheet against the reference surface;
A first conveying member pair for correcting the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guiding unit in the sheet conveying direction, and for conveying the sheet while nipping the sheet;
A second conveying member pair that nips and conveys the sheet to the downstream side in the sheet conveying direction upstream of the guide means;
A third conveying member pair that nips the sheet on the upstream side in the sheet conveying direction of the second conveying member pair and conveys the sheet downstream;
Moving means for moving the guide means in a direction crossing the paper transport direction based on a paper length along the paper transport direction;
It is characterized by that.

The invention according to claim 2 is the paper conveying apparatus according to claim 1,
When the paper length is longer than the distance between the first transport member pair and the second transport member pair in the paper transport direction, the moving means moves the guide means in a state where the nip of the width adjusting means is released. Is moved to a position where the side portion of the sheet is not inserted and retracted, and the width of the sheet is shorter than the distance between the first conveying member pair and the second conveying member pair in the sheet conveying direction. Moving the guide means to a position where the side portion of the paper is inserted in a state where the approach means is nipped;
It is characterized by that.

According to a third aspect of the present invention, in the paper conveying device according to the second aspect,
The moving means includes a link member that holds the guide means, and an insertion position connected to the link member between the insertion position where the side of the paper is inserted and a retreat position where the side of the paper is not inserted. A rotary solenoid moved by
It is characterized by that.

In order to solve the above-described problem, a paper conveying device according to claim 4 is provided.
A guide unit having a reference surface and having a side portion on one side in a direction intersecting with the sheet conveyance direction inserted therein to guide the sheet to the downstream side in the conveyance direction along the reference surface;
Width-shifting means for width-shifting in a direction intersecting the transport direction in a state where the sheet is nipped, and abutting a side edge of the sheet against the reference surface;
A first conveying member pair for correcting the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guiding unit in the sheet conveying direction, and for conveying the sheet while nipping the sheet;
A second conveying member pair that nips and conveys the sheet to the downstream side in the sheet conveying direction upstream of the guide means;
A third conveyance member pair that nips the sheet on the upstream side in the sheet conveyance direction of the second conveyance member pair and conveys the sheet downstream.
When the sheet length along the sheet conveying direction is longer than the distance between the first conveying member pair and the third conveying member pair in the sheet conveying direction, the width-adjusting means and the second conveying member pair After releasing the nip, the third conveying member pair feeds the paper toward the first conveying member pair to form a loop;
It is characterized by that.

The invention according to claim 5 is the paper conveying apparatus according to claim 4,
When the paper length is longer than the distance between the first transport member pair and the third transport member pair in the paper transport direction, the third transport is performed after the first transport member pair starts transporting the paper. Making the conveying speed of the member pair larger than the conveying speed of the first conveying member pair;
It is characterized by that.

In order to solve the above problem, an image forming apparatus according to claim 6,
A paper conveying device according to any one of claims 1 to 5,
Image forming means for forming an image on a sheet conveyed by the sheet conveying device;
It is characterized by that.

According to the first aspect of the invention, it is possible to improve the accuracy of alignment between the image and the paper.
According to the second aspect of the present invention, it is possible to improve the accuracy of alignment with the image of the long paper fed.
According to the third aspect of the present invention, the guide means can be moved with a simple configuration in accordance with the length of the sheet to be fed.
According to the fourth and fifth aspects of the present invention, it is possible to improve the alignment accuracy of the image and the paper in the direction intersecting the paper conveyance direction of the long paper fed with a simple configuration.

1 is a schematic cross-sectional view illustrating an example of a schematic configuration of an image forming apparatus. FIG. 2A is a schematic plan view showing an outline of the paper conveying apparatus according to the first embodiment, and FIG. It is a schematic diagram which shows the structure of a shift mechanism. (A), (b) is a schematic diagram which shows the moving position of a moving mechanism and a side guide. (A), (b), (c) is a schematic diagram which shows the conveyance process at the time of position alignment of the long paper in the paper conveying apparatus which concerns on 1st Embodiment. 6 is a flowchart illustrating an alignment process in the paper conveying apparatus according to the first embodiment. (A), (b), (c) is a schematic diagram which shows the conveyance process at the time of position alignment of the long paper in the paper conveying apparatus which concerns on 2nd Embodiment. 10 is a flowchart illustrating an alignment process in a paper conveying apparatus according to a second embodiment. (A), (b) is a schematic diagram which shows the conveyance process at the time of position alignment of the long paper in the paper conveying apparatus of a comparative example. 6 is a flowchart illustrating a positioning process in a paper conveying apparatus according to a comparative example.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.

“First Embodiment”
(1) Overall Configuration and Operation of Image Forming Apparatus (1.1) Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view showing an example of a schematic configuration of an image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 is provided at the other end of the image forming unit 100, the paper supply unit 200 attached to one end of the image forming unit 100, and the other end of the image forming unit 100. A paper unit 300, an operation information unit 400, and an image processing unit 500 that generates image information from print information transmitted from a host device are configured.

  The image forming unit 100 includes a system control device 10 (not shown), an exposure device 20, a photosensitive unit 30, a developing device 40, a paper transport device 50, a transfer device 60, and a fixing device 70, and includes an image processing unit. The image information received from 500 is formed as a toner image on the paper P sent from the paper supply unit 200.

  The paper supply unit 200 supplies paper to the image forming unit 100. In other words, a plurality of paper stacking units that store different types of paper P (for example, material, thickness, paper size, and paper size) are provided, and the paper P fed out from any one of the plurality of paper stacking units. Is supplied to the image forming unit 100.

  The paper discharge unit 300 discharges the paper P on which the image is output by the image forming unit 100. For this purpose, the paper discharge unit 300 includes a paper discharge storage unit in which the paper P after image output is discharged. The paper discharge unit 300 may have a function of performing post-processing such as cutting and stapling (stitch binding) on the sheet bundle output from the image forming unit 100.

  The operation information section 400 is used for inputting various settings and instructions and displaying information. That is, it corresponds to a so-called user interface, and is specifically configured by combining a liquid crystal display panel, various operation buttons, a touch panel, and the like.

(1.2) Configuration and Operation of Image Forming Unit In the image forming apparatus 1 having such a configuration, the tray designated for each sheet printed by the print job in the paper supply unit 200 in accordance with the timing of image formation. Sheets P fed out from 1, 2, and 3 are sent to the image forming unit 100.

  The photoconductor unit 30 includes a photoconductor drum 31 that is provided in parallel below the exposure device 20 and serves as an image carrier that is rotationally driven. A charger 32, an exposure device 20, a developing device 40, a primary transfer roller 62, and a cleaning blade 34 are arranged along the rotation direction of the photosensitive drum 31, and the surface of the rotating photosensitive drum 31 is charged by the charger 32. Then, an electrostatic latent image is formed by the latent image forming light emitted from the exposure device 20.

  The developing device 40 includes a developing housing 41 in which a developer is accommodated. In the developing housing 41, a developing roller 42 is disposed so as to face the photosensitive drum 31. Each developing device 40 is configured in substantially the same manner except for the developer contained in the developing housing 41, and each of them is a developing roller 42 with yellow (Y), magenta (M), cyan (C), and black (K). The toner image is formed.

  The paper transport device 50 controls the posture of the paper P supplied from the paper supply unit 200 and guides and guides it to the transfer device 60, so that the first upstream roller 51 and the second transport member as a third transport member pair Second upstream roller 52 as a pair, side guide 53 as guide means, a plurality of skew rollers 54 as width adjusting means for width-adjusting the paper P conveyed to the side guide 53, and the conveying direction of the conveyed paper P A registration roller (hereinafter referred to as “registration roller”) 55 is provided as a first conveying member pair that aligns the leading end (see arrow A1 in FIG. 2) and sends it to the transfer device 60.

  The transfer device 60 includes an intermediate transfer belt 61 onto which the color toner images formed on the photosensitive drums 31 of the respective photosensitive units 30 are transferred, and the color toner images formed on the photosensitive drums 31 to the intermediate transfer belt. A primary transfer roller 62 that sequentially transfers (primary transfer) to 61, and a secondary transfer belt 63 that collectively transfers (secondary transfer) each color toner image transferred on the intermediate transfer belt 61 onto a sheet P. ing.

  Each color toner image formed on the photosensitive drum 31 of each photosensitive unit 30 is intermediately transferred by a primary transfer roller 62 to which a predetermined transfer voltage is applied from a power supply device (not shown) controlled by the system control device 11. Electrostatic transfer (primary transfer) is sequentially performed on the belt 61 to form a superimposed toner image in which toner of each color is superimposed.

  The superimposed toner image on the intermediate transfer belt 61 is conveyed to the secondary transfer portion TR where the secondary transfer belt 63 is disposed as the intermediate transfer belt 61 moves. When the superimposed toner image is conveyed to the secondary transfer portion TR, the paper P is supplied from the registration roller 55 to the secondary transfer portion TR in accordance with the timing. A predetermined transfer voltage is applied to the backup roller 65 facing the secondary transfer roller 64 via the secondary transfer belt 63 from a power supply device or the like controlled by the system control device 11, and the intermediate transfer belt is applied to the paper P. The multiple toner images on 61 are collectively transferred.

  Residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 34 and collected in a waste toner container (not shown). The surface of the photosensitive drum 31 is recharged by the charger 32.

The fixing device 70 includes an endless fixing belt 71 that rotates in one direction, and a pressure roller 72 that contacts the peripheral surface of the fixing belt 71 and rotates in one direction. The pressure contact between the fixing belt 71 and the pressure roller 72 is performed. A nip portion (fixing region) is formed by the region.
The paper P on which the toner image is transferred by the transfer device 60 is conveyed to the fixing device 70 in a state where the toner image is not fixed. The toner image is fixed on the sheet P conveyed to the fixing device 70 by a pair of fixing belt 71 and pressure roller 72 by the action of heating and pressure bonding.

  The sheet P that has been fixed is sent to the paper discharge unit 300. When performing image output on both sides of the paper P, the front and back of the paper P are reversed and sent again to the secondary transfer unit TR via the paper transport device 50. Then, after the toner image is transferred and the transferred image is fixed, it is sent to the paper discharge unit 300. The paper P sent to the paper discharge unit 300 is subjected to post-processing such as cutting and stapling (needle binding) as necessary, and then discharged to the paper discharge storage unit.

(2) Configuration and Operation of Paper Conveying Device (2.1) Configuration of Paper Conveying Device FIG. 2A is a schematic plan view showing an outline of the paper conveying device 50 according to the present embodiment, and FIG. 3 is a schematic diagram illustrating the configuration of the shift mechanism 80, FIGS. 4A and 4B are schematic diagrams illustrating the moving positions of the moving mechanism 90 and the side guide 53, and FIGS. 5A, 5B, and 5B. FIG. 6C is a schematic diagram illustrating a conveyance process when aligning a long sheet in the sheet conveying apparatus 50, and FIG. 6 is a flowchart illustrating an alignment process in the sheet conveying apparatus.
Hereinafter, the configuration and operation of the sheet conveying device 50 will be described with reference to the drawings.

  As shown in FIG. 2, the sheet conveying device 50 includes a pair of registration rollers 55, a plurality of (three in this example) skew rollers 54, and skew rollers 54 disposed upstream of the registration rollers 55. The first upstream roller 51, the second upstream roller 52 disposed on the upstream side, the side guide 53 disposed so as to be movable in one of the directions intersecting (orthogonal to) the sheet conveying direction, and the side guide 53 as a guide position. And a moving mechanism 90 as a moving means for moving to the retracted position.

The first upstream roller 51 is composed of a drive first upstream roller 51A that is rotationally driven by a drive motor (not shown), and a driven first upstream roller 51B that is disposed in pressure contact with the drive first upstream roller 51A and rotates following the first upstream roller 51A. The paper P supplied from the supply unit 200 is nipped and conveyed downstream in the conveyance direction.
Similarly, the second upstream roller 52 includes a drive second upstream roller 52A that is rotationally driven by a drive motor (not shown), and a driven second upstream roller 52B that is disposed in pressure contact with the drive second upstream roller 52A and rotates following. Then, the sheet P is nipped and conveyed downstream in the conveying direction.

  The skew roller 54 has a driving skew roller 54A that is slightly inclined toward the side guide 53 with respect to the conveyance direction of the paper P, and is driven to rotate by a drive motor (not shown). The driven skew roller 54B is arranged in pressure contact with the roller 54A and rotates following the rotation. The driven skew roller 54B is nipped or nip released from the drive skew roller 54A by a nip releasing motor (not shown). It has become.

The registration roller 55 is driven by a driving motor 85 (shown in FIG. 3) and is driven by a gear 86 at a shaft end, and a driven registration roller 55B that rotates in contact with the driving registration roller 55A. It consists of and.
The registration roller 55 forms a loop (registration loop) in the paper P by feeding the paper P excessively by the second upstream roller 52 in a state where the leading edge of the paper P conveyed from the upstream side is abutted in the stopped state. Positioning in a direction intersecting (orthogonal) with the conveyance direction of P is performed.

  Further, as shown in FIG. 3, the registration rollers 55 (55A and 55B) are rotatably supported so as to be movable in a direction intersecting with the conveyance direction of the paper P (see arrows B1 and B2 in the figure), and coupled to one end. A shift mechanism 80 is provided as an example of a displacement unit that moves the registration roller 55 via 84.

  As shown in FIG. 3, the shift mechanism 80 includes a rack 81 provided at the end of the registration roller 55, a pinion gear 82 that meshes with the rack 81, and a motor 83 that rotates the pinion gear 82. In the present embodiment, by rotating the motor 83 forward and backward, the registration roller 55 can move in a direction (see arrows B1 and B2 in the figure) that intersects the transport direction of the paper P.

As shown in FIG. 4, the side guide 53 has a concave cross section that opens on the side of the paper P to be transported, and a reference surface 53a parallel to the transport direction of the paper P is formed at the bottom inside the recess. Is formed.
The paper P that is width-adjusted by each skew roller 54 (54A, 54B) is conveyed toward the registration roller 55 along the reference surface 53a in a state where the side edges are aligned with the reference surface 53a of the side guide 53. The

The side guide 53 is movable between an insertion position where the side portion of the paper P is inserted by the moving mechanism 90 and a retracted position where the side portion of the paper P is not inserted.
Specifically, the side end of the side guide 53 is connected to the rotary solenoid 93 via the first link member 91 and the second link member 92, and the rotary solenoid 93 rotates (see arrow R1 in FIG. 4B). ) To move in a direction intersecting (orthogonal) with the transport direction of the paper P (see arrow B1 in FIG. 4B).

As shown in FIG. 2A, at the upstream side of the registration roller 55 in the conveyance direction of the sheet P, one end of the sheet P that is offset from one side of the conveyance path of the sheet P is a CIS (Contact Image Sensor) as a side detection means. A sensor 88 is arranged.
The CIS sensor 88 is composed of a plurality of light emitting elements (not shown) configured to irradiate the paper P with light and the like, and a plurality of CCDs configured to receive reflected light from the paper P irradiated by the plurality of light emitting elements. Light receiving elements (not shown).
A light beam is irradiated downward from the light emitting element, the light beam is reflected by the transported paper P, the reflected light from the paper P is received by the light receiving element, and the signal obtained by the light receiving element is binarized and 2 The side of the paper P is detected based on the density level change after the digitization.

(2.2) Operation of the Paper Conveying Device FIGS. 9A and 9B are schematic diagrams showing a conveying process when aligning a long paper in the paper conveying device 600 of the comparative example, and FIG. It is a flowchart which shows the position alignment process.
Before describing the alignment operation when the long paper is conveyed by the paper conveyance device 50 according to the present embodiment, the alignment of the long paper is performed in the comparative paper conveyance device 600 that does not include the moving mechanism 90 of the side guide 53. Will be described.

When a long sheet having a long length in the conveyance direction is conveyed and aligned, the nip of the skew roller 54 is released to make the sheet P easy to move (S301).
Then, with the rotational drive of the registration roller 55 stopped, the first upstream roller 51 and the second upstream roller 52 transport the paper P and abut the leading edge of the paper P against the registration roller 55 (S302).

Then, the second upstream roller 52 feeds the paper P toward the registration roller 55 (S303), and forms a loop (registration loop) on the paper P (S304).
The registration roller 55 stopped in a state where the loop is formed is rotated (S305), and the sheet P, in which the direction intersecting (orthogonal) the conveyance direction is aligned, is conveyed toward the secondary transfer unit TR.

As described above, the long paper has a paper length longer than the distance between the registration roller 55 and the second upstream roller 52, and the rear end side of the paper is nipped by the first upstream roller 51 and the second upstream roller 52 during alignment. For this reason, the skew roller 54 does not correct the position by aligning with the side guide 53, and the registration roller 55 forms a loop and aligns in the direction intersecting (orthogonal) with the conveyance direction. Yes.
On the other hand, since one side portion of the paper P is inserted into the concave portion of the side guide 53, there is little space for forming a loop, and a loop amount necessary for alignment cannot be formed. There was a fear.

  When the sheet P to be transported is a long sheet, the sheet transport apparatus 50 according to the present embodiment intersects the transport direction in a state where the side guide 53 is moved to a retracted position where the side portion of the sheet P is not inserted ( Align in the direction of (orthogonal).

As shown in the flowchart of FIG. 6, the image forming apparatus 1 receives paper attribute information such as the material, thickness, size, and the like of the paper P via the operation information unit 400 (S101), and the transported paper P is long. It is determined whether or not the sheet is a sheet (S102).
When the sheet P is a long sheet (S102: Yes), the nip of the skew roller 54 is released (S103) (see arrow C1 in FIG. 5B), the rotary solenoid 93 is turned on, and the side guide 53 is moved. The side of the paper P is moved to the retracted position where it is not inserted (S104: see arrow B2 in FIG. 5A).

  Then, the first upstream roller 51 and the second upstream roller 52 are rotated to feed the leading end of the paper P to the registration roller 55 (S105), and a registration loop is formed by the registration roller 55 (S106). At this time, since the side guide 53 is retracted to a position where the side portion of the paper P is not inserted, the upper surface of the paper P comes into contact with the top surface 53b of the concave portion of the side guide 53 and the loop formation is inhibited. There is no. Therefore, a sufficient loop amount necessary for alignment of the long paper can be ensured.

  Thereafter, the registration roller 55 is rotated, and the sheet P is conveyed to the secondary transfer unit TR in a state where the leading end is aligned and the skew is corrected (S112).

  When the paper P is not a long paper (S102: No), the side guide 53 is moved to the initial position where the side portion of the paper P is inserted (S107). Then, the transported paper P is shifted toward the reference surface 53a of the side guide 53 by the skew roller 54 (S108) and transported while aligning the side edge of the paper P along the side guide 53.

Then, the side edge of the paper P is detected by the CIS sensor 88 (S109), and when the nip of the skew roller 54 is released (S110: Yes), the paper is based on the position of the side of the paper P. P moves the registration roller 55 in a direction intersecting the conveyance direction while being nipped by the registration roller 55 (S111).
By the movement of the registration roller 55, the side of the paper P being conveyed by the registration roller 55 is aligned with the position in the width direction of the image formed on the photosensitive drum 31.

  Thereafter, the registration roller 55 is rotated, and the paper P is conveyed to the secondary transfer portion TR in a state where the side end portions are aligned and the skew is corrected (S112).

  When the paper P to be transported is a long paper, the paper transport device 50 according to the present embodiment performs the loop formation in a state where the side guide 53 is moved to the retracted position where the side portion of the paper P is not inserted. Therefore, the registration loop can be formed in a state in which the necessary upper space is ensured, and the alignment accuracy between the image in the direction intersecting the conveyance direction of the long sheet and the sheet can be improved.

“Second Embodiment”
FIGS. 7A, 7B, and 7C are schematic views showing a conveyance process when aligning a long sheet in the sheet conveying apparatus 50A according to the present embodiment, and FIG. 8 is an alignment process in the sheet conveying apparatus 50A. It is a flowchart which shows.
Hereinafter, the configuration of the sheet conveying apparatus 50A according to the present embodiment and the alignment operation when conveying a long sheet will be described with reference to the drawings. The same components as those of the sheet conveying apparatus 50 according to the first embodiment are described below. The same reference numerals are given, and detailed descriptions thereof are omitted.

  The sheet conveying device 50A includes a registration roller 55, a plurality of (three in this example) skew rollers 54 disposed upstream of the registration rollers 55, and a first upstream disposed upstream of the skew rollers 54. A roller 51, a second upstream roller 52, and a side guide 53 disposed on one side in a direction intersecting (orthogonal to) the sheet conveyance direction.

The first upstream roller 51 is composed of a drive first upstream roller 51A that is rotationally driven by a drive motor (not shown), and a driven first upstream roller 51B that is disposed in pressure contact with the drive first upstream roller 51A and rotates following the first upstream roller 51A. The paper P supplied from the supply unit 200 is nipped and conveyed downstream in the conveyance direction.
Further, the driving first upstream roller 51A is a driving motor (not shown) controlled by the system control device 10, and the first conveying speed V1 and the first conveying speed, which are the same conveying speed as the driving registration roller 55A of the registration roller 55. It is driven to rotate at any one of the second transport speeds V2 that is faster than V1.

The second upstream roller 52 is composed of a drive second upstream roller 52A that is rotationally driven by a drive motor (not shown), and a driven second upstream roller 52B that is arranged in pressure contact with the drive second upstream roller 52A and rotates following the roller. P is nipped and conveyed downstream in the conveying direction.
Further, the driven second upstream roller 52B is nipped or nipped from the driving second upstream roller 52A by a nip release motor (not shown).

  The side guide 53 is erected in a fixed manner in one of the directions intersecting (orthogonal) with the conveyance direction of the paper P, and the reference surface 53a inside the recess is used as an initial position in the width direction where the side edges of the paper P are initially aligned. It has been set.

In the paper transport apparatus 50A configured as described above, when positioning the transported paper P, first, paper attribute information such as the material, thickness, size, and the like of the paper P is obtained via the operation information unit 400. Upon receipt (S201), it is determined whether or not the sheet P to be conveyed is a long sheet (S202).
When the paper P is a long paper (S202: Yes), the paper P to be transported is shifted toward the reference surface 53a of the side guide 53 by the skew roller 54 (S203), and the side edge of the paper P is moved to the side. It is conveyed along the guide 53 while being aligned.

  Then, the nip between the skew roller 54 and the second upstream roller 52 is released (S204) so that the paper P is easily moved. In this state, the first upstream roller 51 is rotated to feed the leading end of the paper P to the registration roller 55 (S205), and a registration loop is formed by the registration roller 55 (S206).

At this time, the side guide 53 may not be sufficiently loop-formed with the side portion of the paper P inserted, but the second upstream roller 52 disposed on the upstream side of the side guide 53 is driven. Since the second upstream roller 52B is released from the nip, a loop is formed between the one end 93c of the side guide 53 and the first upstream roller 51 (see the section S in FIGS. 7B and 7C). Space to do is secured.
Therefore, a sufficient loop amount necessary for alignment of the long paper can be ensured.

Then, the side edge of the paper P is detected by the CIS sensor 88 (S207), and based on the position of the side of the paper P, the direction in which the registration roller 55 crosses the transport direction in a state where the paper P is nipped by the registration roller 55. (S208).
By the movement of the registration roller 55, the side of the paper P being conveyed by the registration roller 55 is aligned with the position in the width direction of the image formed on the photosensitive drum 31.

Thereafter, the registration roller 55 is rotated in a state where the side end portions are aligned and the skew is corrected, and the conveyance of the sheet P toward the secondary transfer unit TR is started, and the first upstream roller 51 is conveyed to the second conveyance direction. The speed is increased to the speed V2 (S210), and the sheet P is conveyed toward the secondary transfer unit TR while eliminating the twist of the sheet P due to the movement in the width direction in a state where the sheet P is slackened.
For this reason, it is possible to improve the accuracy of alignment between the image and the paper P in the direction intersecting the paper conveyance direction of the long paper with a simple configuration.

  When the sheet P is not a long sheet (S202: No), the sheet P to be conveyed is shifted toward the reference surface 53a of the side guide 53 by the skew roller 54 (S211), and the side edge of the sheet P is moved to the side. It is conveyed along the guide 53 while being aligned.

Then, the side edge of the paper P is detected by the CIS sensor 88 (S212), and when the nip of the skew roller 54 is released (S213: Yes), based on the position of the side of the paper P, the paper In a state where P is nipped by the registration rollers 55, the registration rollers 55 are moved in a direction crossing the conveyance direction (S214).
By the movement of the registration roller 55, the width of the sheet P conveyed by the registration roller 55 is adjusted to the position in the width direction of the image formed on the photosensitive drum 31 to the secondary transfer portion TR. Be transported.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 100 ... Image forming part 10 ... System control apparatus 20 ... Exposure apparatus 30 ... Photoconductor unit 40 ... Developing apparatus 50, 50A, 600 ... Paper conveyance Device 51: First upstream roller 52 ... Second upstream roller 53 ... Side guide 54 ... Skew roller 55 ... Registration roller 60 ... Transfer device 70 ... Fixing device 80 ..Shift mechanism 90 ... Movement mechanism 91 ... First link member 92 ... Second link member 93 ... Rotary solenoid 200 ... Paper supply unit 300 ... Discharge unit 400 ... Operation information unit 500... Image processing unit

Claims (6)

A guide unit having a reference surface and having a side portion on one side in a direction intersecting with the sheet conveyance direction inserted therein to guide the sheet to the downstream side in the conveyance direction along the reference surface;
Width-shifting means for width-shifting in a direction intersecting the transport direction in a state where the sheet is nipped, and abutting a side edge of the sheet against the reference surface;
A first conveying member pair for correcting the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guiding unit in the sheet conveying direction, and for conveying the sheet while nipping the sheet;
A second conveying member pair that nips and conveys the sheet to the downstream side in the sheet conveying direction upstream of the guide means;
A third conveying member pair that nips the sheet on the upstream side in the sheet conveying direction of the second conveying member pair and conveys the sheet downstream;
Moving means for moving the guide means in a direction crossing the paper transport direction based on a paper length along the paper transport direction;
A sheet conveying apparatus characterized by the above. When the paper length is longer than the distance between the first transport member pair and the second transport member pair in the paper transport direction, the moving means moves the guide means in a state where the nip of the width adjusting means is released. Is moved to a position where the side portion of the sheet is not inserted and retracted, and the width of the sheet is shorter than the distance between the first conveying member pair and the second conveying member pair in the sheet conveying direction. Moving the guide means to a position where the side portion of the paper is inserted in a state where the approach means is nipped;
The sheet conveying apparatus according to claim 1. The moving means includes a link member that holds the guide means, and an insertion position connected to the link member between the insertion position where the side of the paper is inserted and a retreat position where the side of the paper is not inserted. A rotary solenoid moved by
The sheet conveying apparatus according to claim 2. A guide unit having a reference surface and having a side portion on one side in a direction intersecting with the sheet conveyance direction inserted therein to guide the sheet to the downstream side in the conveyance direction along the reference surface;
Width-shifting means for width-shifting in a direction intersecting the transport direction in a state where the sheet is nipped, and abutting a side edge of the sheet against the reference surface;
A first conveying member pair for correcting the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guiding unit in the sheet conveying direction, and for conveying the sheet while nipping the sheet;
A second conveying member pair that nips and conveys the sheet to the downstream side in the sheet conveying direction upstream of the guide means;
A third conveyance member pair that nips the sheet on the upstream side in the sheet conveyance direction of the second conveyance member pair and conveys the sheet downstream.
When the sheet length along the sheet conveying direction is longer than the distance between the first conveying member pair and the third conveying member pair in the sheet conveying direction, the width-adjusting means and the second conveying member pair After releasing the nip, the third conveying member pair feeds the paper toward the first conveying member pair to form a loop;
A sheet conveying apparatus characterized by the above. When the paper length is longer than the distance between the first transport member pair and the third transport member pair in the paper transport direction, the third transport is performed after the first transport member pair starts transporting the paper. Making the conveying speed of the member pair larger than the conveying speed of the first conveying member pair;
The sheet conveying apparatus according to claim 4. A paper conveying device according to any one of claims 1 to 5,
Image forming means for forming an image on a sheet conveyed by the sheet conveying device;
An image forming apparatus.

Images