JP6699431B2 - Paper transport device and image forming device - Google Patents

Description

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

  A side guide having a side reference surface arranged parallel to the sheet conveyance direction at one end of the sheet conveyance path along which the sheet is conveyed, and a side guide arranged at 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 a positional deviation state of the sheet in the sheet conveying path. There is also known a sheet conveying device including a control unit that controls the drive of the angle changing unit based on at least one of the sheet-related information related to the sheet to be conveyed (Patent Document 1).

JP-A-2002-60097

  The present invention provides a sheet conveying device and an image forming apparatus capable of improving the accuracy of alignment between an image and a sheet.

In order to solve the above-mentioned problems, the sheet conveying device according to claim 1,
A guide unit having a reference surface, one side of which is inserted in a direction intersecting the sheet conveyance direction, and which guides the sheet to the downstream side in the sheet conveyance direction along the reference surface.
A width-shifting unit that shifts the width of the sheet in a direction intersecting the transport direction while the sheet is nipped, and abuts a side edge of the sheet to the reference surface;
A first conveying member pair configured to correct the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guide unit in the sheet conveying direction and to convey the sheet by nipping the sheet;
A second conveying member pair that nips the sheet on the upstream side of the guide means in the sheet conveying direction and conveys the sheet to the downstream side;
A third conveying member pair that nips and conveys the sheet to the downstream side on the upstream side in the sheet conveying direction of the second conveying member pair;
A moving unit that moves the guiding unit in a direction intersecting the sheet conveying direction based on the sheet length along the sheet conveying direction,
It is characterized by

According to a second aspect of the present invention, in the paper transport apparatus according to the first aspect,
When the sheet length is longer than the distance between the first pair of transport members and the second pair of transport members in the sheet transport direction, the moving unit releases the nip of the width-shifting unit and guides the guiding unit. Is moved to a position where the side portion of the sheet is not inserted and retracted, and when the sheet length is shorter than the distance between the first conveying member pair and the second conveying member pair in the sheet conveying direction, the width The guide means is moved to a position where the side portion of the sheet is inserted in a state where the approach means is nipped,
It is characterized by

According to a third aspect of the present invention, in the paper transport apparatus according to the second aspect,
The moving means is provided between a link member that holds the guide means, an insertion position that is connected to the link member and in which the side portion of the paper is inserted into the guide means, and a retracted position in which the side portion of the paper is not inserted. And a rotary solenoid that is moved by
It is characterized by

In order to solve the above-mentioned problems, the sheet conveying apparatus according to claim 4,
A guide unit having a reference surface, one side of which is inserted in a direction intersecting the sheet conveyance direction, and which guides the sheet to the downstream side in the sheet conveyance direction along the reference surface.
A width-shifting unit that shifts the width of the sheet in a direction intersecting the transport direction while the sheet is nipped, and abuts a side edge of the sheet to the reference surface;
A first conveying member pair configured to correct the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guide unit in the sheet conveying direction and to convey the sheet by nipping the sheet;
A second pair of conveying members that nips the sheet on the upstream side in the sheet conveying direction of the guide means and conveys the sheet to the downstream side;
A third conveying member pair that nips the sheet on the upstream side of the second conveying member pair in the sheet conveying direction and conveys the sheet to the downstream side,
When the sheet length along the sheet transport direction is longer than the distance between the first pair of transport members and the third pair of transport members in the sheet transport direction, the width aligning means and the second pair of transport members are After releasing the nip, the third conveying member pair feeds the sheet toward the first conveying member pair to form a loop,
It is characterized by

According to a fifth aspect of the present invention, in the sheet conveying device according to the fourth aspect,
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 after the first transport member pair starts transporting the paper A conveying speed of the member pair is made higher than a conveying speed of the first conveying member pair,
It is characterized by

In order to solve the above problems, the image forming apparatus according to claim 6,
A sheet 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

According to the invention described in claim 1, it is possible to improve the accuracy of alignment between the image and the sheet.
According to the second aspect of the present invention, it is possible to improve the accuracy of alignment with the image of the long sheet to be fed.
According to the third aspect of the invention, the guide unit can be moved with a simple configuration according to the sheet 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 between the image and the sheet in the direction intersecting the sheet transport direction of the long sheet fed with a simple configuration.

It is a cross-sectional schematic diagram which shows an example of a schematic structure of an image forming apparatus. FIG. 1A is a schematic plan view showing an outline of the sheet conveying device 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 alignment of the long paper in the paper conveyance apparatus which concerns on 1st Embodiment. 6 is a flowchart showing a position alignment process in the sheet transport apparatus according to the first embodiment. (A), (b), (c) is a schematic diagram which shows the conveyance process at the time of alignment of the long paper in the paper conveyance apparatus which concerns on 2nd Embodiment. 8 is a flowchart showing a position alignment process in the sheet transport apparatus according to the second embodiment. (A), (b) is a schematic diagram which shows the conveyance process at the time of alignment of the long paper in the paper conveyance device of a comparative example. 7 is a flowchart showing a position alignment process in a paper transporting device of a comparative example.

Next, with reference to the drawings, the present invention will be described in more detail with reference to embodiments and specific examples, but the present invention is not limited to these embodiments and specific examples.
Further, in the following description using the drawings, it should be noted that the drawings are schematic, and the ratios of the respective dimensions and the like are different from the actual ones. Illustrations other than the members are appropriately omitted.

"First embodiment"
(1) Overall Configuration and Operation of Image Forming Apparatus (1.1) Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic sectional view showing an example of a schematic configuration of an image forming apparatus 1 according to this embodiment.
The image forming apparatus 1 is provided at 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, and ejects printed paper. It is configured to include 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 higher-level device.

  The image forming unit 100 includes a system control device 10 (not shown), an exposure device 20, a photoconductor unit 30, a developing device 40, a sheet conveying device 50, a transfer device 60, and a fixing device 70. 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. That is, it is provided with a plurality of paper stacking units for accommodating papers P of different types (for example, material, thickness, paper size, and grain), 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. Therefore, 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 (stitching) 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 Section In the image forming apparatus 1 having such a configuration, in the sheet supply section 200, the tray specified for each sheet of printing in the print job is synchronized with the timing of image formation. The paper P fed from 1, 2, and 3 is sent to the image forming unit 100.

  The photoconductor unit 30 is provided below the exposure device 20 in parallel, and includes a photoconductor drum 31 as an image holding member 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 has a developing housing 41 in which a developer is contained. In the developing housing 41, a developing roller 42 is arranged so as to face the photosensitive drum 31. Each of the developing devices 40 has substantially the same configuration except for the developer contained in the developing housing 41, and each of the developing rollers 42 has a developing roller 42 for yellow (Y), magenta (M), cyan (C), and black (K). To form a toner image.

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

  The transfer device 60 includes an intermediate transfer belt 61 on which the toner images of the respective colors formed on the photoconductor drums 31 of the respective photoconductor units 30 are multiply transferred, and a toner image of the respective colors formed on the photoconductor drums 31 is transferred 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 (secondarily transfers) the toner images of respective colors superposed and transferred onto the intermediate transfer belt 61 onto the paper P. ing.

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

  The superimposed toner image on the intermediate transfer belt 61 is conveyed to the secondary transfer portion TR on which the secondary transfer belt 63 is arranged 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 at the timing. Then, a predetermined transfer voltage is applied to the backup roller 65, which faces the secondary transfer roller 64 via the secondary transfer belt 63, from a power supply device controlled by the system controller 11, and the intermediate transfer belt P is applied to the paper P. The multiple toner images on 61 are collectively transferred.

  The residual toner on the surface of the photoconductor 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 has 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 that rotates in one direction. The fixing belt 71 and the pressure roller 72 are pressed against each other. The area forms a nip portion (fixing area).
The sheet P to 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. On the sheet P conveyed to the fixing device 70, the toner image is fixed by the action of heating and pressure bonding by the pair of fixing belts 71 and the pressure roller 72.

  The sheet P after the fixing is sent to the sheet discharge unit 300. When images are to be output on both sides of the paper P, the front and back of the paper P are reversed and fed again to the secondary transfer portion TR via the paper transport device 50. Then, after the toner image is transferred and the transferred image is fixed, the toner image is sent to the paper discharge unit 300. The paper P sent to the paper ejection unit 300 is ejected to the paper ejection accommodating unit after undergoing post-processing such as cutting and stapling (needle stitching) as necessary.

(2) Configuration and Action of Paper Conveying Device (2.1) Configuration of Paper Conveying Device FIG. 2A is a schematic plan view showing the outline of the paper conveying device 50 according to the present embodiment, and FIG. 3A and 3B are schematic diagrams showing the configuration of the shift mechanism 80, FIGS. 4A and 4B are schematic diagrams showing the moving positions of the moving mechanism 90 and the side guides 53, FIGS. 5A, 5B, and 5B. FIG. 6C is a schematic diagram showing a conveying process when aligning a long sheet in the sheet conveying device 50, and FIG. 6 is a flowchart showing a position adjusting process in the sheet conveying device.
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. A first upstream roller 51, a second upstream roller 52 disposed on the upstream side of the side guide, a side guide 53 movably disposed in one of the directions intersecting (perpendicular to) the sheet conveying direction, and the side guide 53. And a moving mechanism 90 as moving means for moving to the retracted position.

The first upstream roller 51 is composed of a driving first upstream roller 51A which is rotationally driven by a driving motor (not shown) and a driven first upstream roller 51B which is arranged in pressure contact with the driving first upstream roller 51A and rotates following the paper. The paper P supplied from the supply unit 200 is nipped and conveyed to the downstream side in the conveyance direction.
The second upstream roller 52 is composed of a driving second upstream roller 52A, which is also rotationally driven by a driving motor (not shown), and a driven second upstream roller 52B, which is arranged in pressure contact with the driving second upstream roller 52A and follows and rotates. , The paper P is nipped and conveyed to the downstream side in the conveying direction.

  The skew roller 54 has a front skew side slightly inclined toward the side guide 53 with respect to the conveyance direction of the paper P, and a drive skew roller 54A that is driven to rotate by a drive motor (not shown) and a drive skew roller. 54A and a driven skew feed roll 54B which is arranged in pressure contact with and rotates following the driven skew feed roll 54B. It has become.

The registration roller 55 is geared to a drive registration roller 55A that is rotationally driven by a drive motor 85 (shown in FIG. 3) by a gear 86 at the shaft end, and is a follower registration roller 55B that rotates in contact with the drive registration roller 55A while being pressed against it. It consists of and.
The registration roller 55 further feeds the paper P by the second upstream roller 52 in a state where the leading end of the paper P conveyed from the upstream side is abutted in the stopped state, and forms a loop (registration loop) on the paper P to form the paper. Positioning is performed in a direction intersecting (orthogonal to) the conveyance direction of P.

  Further, as shown in FIG. 3, the registration rollers 55 (55A, 55B) are rotatably supported so as to be movable in a direction intersecting the conveyance direction of the paper P (see arrows B1 and B2 in the figure), and a coupling is provided at 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, the registration roller 55 can be moved in the direction intersecting the conveyance direction of the paper P (see arrows B1 and B2 in the figure) by rotating the motor 83 in the forward and reverse directions.

As shown in FIG. 4, the side guide 53 has a concave cross section that is open on the side of the sheet P to be conveyed, and has a reference surface 53a parallel to the conveyance direction of the sheet P at the bottom inside the concave portion. Are formed.
The paper P width-shifted by the skew rollers 54 (54A, 54B) is conveyed toward the registration rollers 55 along the reference surface 53a with the side edges thereof aligned with the reference surface 53a of the side guide 53. It

The side guide 53 is movable between the insertion position where the side portion of the paper P is inserted by the moving mechanism 90 and the 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). Therefore, the sheet P can be moved in a direction intersecting (orthogonal to) the conveying direction of the sheet P (see arrow B1 in FIG. 4B).

As shown in FIG. 2A, one end of the registration roller 55 upstream of the sheet P in the sheet P conveyance direction is offset to one side of the sheet P conveyance path by a CIS (Contact Image Sensor) serving as a side detection unit. A sensor 88 is arranged.
The CIS sensor 88 includes a plurality of light emitting elements (not shown) including LEDs that irradiate the paper P with light, and a plurality of CCDs that receive reflected light from the paper P emitted by the plurality of light emitting elements. Light receiving element (not shown).
A light beam is emitted downward from the light emitting element, the light beam is reflected by the conveyed 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 by the change in the density level after the binarization.

(2.2) Operation of Paper Conveying Device FIGS. 9A and 9B are schematic views showing a conveying process at the time of aligning long sheets in the paper conveying device 600 of the comparative example, and FIG. 5 is a flowchart showing a positioning process in FIG.
Before describing the alignment operation of the sheet transporting device 50 according to the present embodiment when transporting a long sheet, the long sheet alignment in the sheet transporting device 600 of the comparative example, which does not have the moving mechanism 90 of the side guide 53, is described. Will be described.

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

Then, the sheet P is fed toward the registration roller 55 by the second upstream roller 52 (S303), and a loop (registration loop) is formed on the sheet P (S304).
The registration roller 55 that is stopped in the state where the loop is formed is rotated (S305), and the sheet P aligned in the direction intersecting (perpendicular to) the conveying direction is conveyed toward the secondary transfer portion TR.

As described above, the long sheet has a sheet length longer than the distance between the registration roller 55 and the second upstream roller 52, and the trailing edge side of the sheet is nipped by the first upstream roller 51 and the second upstream roller 52 during alignment. Therefore, the skew roller 54 does not perform the correction for aligning the side guide 53 with the width, but the registration roller 55 forms a loop to perform the alignment in the direction intersecting (perpendicular to) the conveying direction. There is.
On the other hand, since one side portion of the paper P is inserted inside the concave portion of the side guide 53, the upper space for forming the loop is small, and the loop amount required for the alignment cannot be formed. I was afraid.

  When the conveyed paper P is a long paper, the paper conveyance device 50 according to the present embodiment intersects the conveyance direction while moving the side guide 53 to the retreat position where the side portion of the paper P is not inserted. Position in the (orthogonal) direction.

As shown in the flowchart of FIG. 6, the image forming apparatus 1 receives the paper attribute information such as the material, thickness, and size of the paper P via the operation information unit 400 (S101), and the paper P conveyed is long. It is determined whether the sheet is paper (S102).
When the paper P is a long paper (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 turned on. 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 edge of the paper P into the registration roller 55 (S105), and the registration roller 55 forms a registration loop (S106). At this time, since the side guide 53 is retracted to the position where the side portion of the paper P is not inserted, the upper surface of the paper P contacts the top surface 53b of the concave portion of the side guide 53, and the loop formation is disturbed. There is no. Therefore, it is possible to secure a sufficient loop amount necessary for aligning the long paper.

  After that, the registration roller 55 is rotated, and the sheet P is conveyed to the secondary transfer portion TR in a state in which the leading end portion is aligned and the skew feeding is corrected (S112).

  When the paper P is not the 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 conveyed sheet P is width-shifted by the skew roller 54 toward the reference surface 53a of the side guide 53 (S108), and the side edge of the sheet P is conveyed while being aligned with the side guide 53.

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

  After that, the registration roller 55 is rotated, and the sheet P is conveyed to the secondary transfer portion TR in a state where the side edges are aligned and skew is corrected (S112).

  When the conveyed paper P is a long paper, the paper conveyance device 50 according to the present embodiment moves the side guide 53 to a retracted position where the side portion of the paper P is not inserted and forms a loop. The registration loop is formed in a state in which a necessary upper space for securing the necessary space is secured, and the accuracy of alignment between the image and the sheet in the direction intersecting the transport direction of the long sheet can be improved.

"Second embodiment"
7A, 7B, and 7C are schematic views showing a conveyance process at the time of 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 showing.
Hereinafter, the configuration of the sheet transporting device 50A according to the present embodiment and the alignment operation when transporting a long sheet will be described with reference to the drawings. However, the same components as the sheet transporting device 50 according to the first embodiment will be described. The same reference numerals are given and detailed description thereof is omitted.

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

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

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

  The side guide 53 is fixedly erected on one side in a direction intersecting (orthogonal to) the conveyance direction of the paper P, and the reference surface 53a inside the recess is set as a width direction initial position where the side edges of the paper P are initially aligned. It is supposed to be set.

When aligning the conveyed sheet P in the sheet conveying apparatus 50A configured as described above, first, sheet attribute information such as the material, thickness, and size of the sheet P is obtained via the operation information unit 400. Upon receipt (S201), it is determined whether the conveyed paper P is a long paper (S202).
When the sheet P is a long sheet (S202: Yes), the conveyed sheet P is width-shifted toward the reference surface 53a of the side guide 53 by the skew roller 54 (S203) and the side edge of the sheet P is set to the side. It is conveyed while being aligned along the guide 53.

  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 edge of the sheet P into the registration roller 55 (S205), and the registration roller 55 forms a registration loop (S206).

At this time, loop formation may not be sufficiently performed in the state where the side portion of the paper P is inserted into the side guide 53, but the second upstream roller 52 disposed upstream 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 section S in FIGS. 7B and 7C). The space to do is secured.
Therefore, it is possible to secure a sufficient loop amount necessary for aligning the long paper.

Then, the CIS sensor 88 detects the side edge of the sheet P (S207), and based on the position of the side edge of the sheet P, the direction in which the sheet P is nipped by the resist roller 55 and the registration roller 55 intersects the conveyance direction. (S208).
By this movement of the registration roller 55, the side edge of the sheet 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.

After that, the registration roller 55 is rotated in a state where the side edges are aligned and skew is corrected, and the sheet P is started to be conveyed toward the secondary transfer portion TR, and the first upstream roller 51 is secondly conveyed. The speed is increased to the speed V2 (S210), and while the slack is applied to the paper P, the paper P is conveyed toward the secondary transfer portion TR while eliminating the twist of the paper P due to the movement in the width direction.
Therefore, with a simple configuration, it is possible to improve the alignment accuracy of the image and the paper P in the direction intersecting the paper transport direction of the long paper.

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

Then, when the side edge of the sheet P is detected by the CIS sensor 88 (S212) and the nip of the skew roller 54 is released (S213: Yes), the sheet is detected based on the position of the side edge of the sheet P. The resist roller 55 is moved in a direction intersecting the conveying direction while P is nipped by the resist roller 55 (S214).
Due to the movement of the registration rollers 55, the paper P conveyed by the registration rollers 55 is transferred to the secondary transfer portion TR in a state where the width direction of the paper P is aligned with the position of the image formed on the photosensitive drum 31 in the width direction. Be transported.

1... Image forming apparatus 100... Image forming unit 10... System control device 20... Exposure device 30... Photosensitive unit 40... Developing device 50, 50A, 600... Paper transport Device 51... First upstream roller 52... Second upstream roller 53... Side guide 54... Oblique 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...Paper ejection unit 400... Operation information section 500... Image processing section

Claims (6)

A guide unit having a reference surface, one side of which is inserted in a direction intersecting the sheet conveyance direction, and which guides the sheet to the downstream side in the sheet conveyance direction along the reference surface.
A width-shifting unit that shifts the width of the sheet in a direction intersecting the transport direction while the sheet is nipped, and abuts a side edge of the sheet to the reference surface;
A first conveying member pair configured to correct the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guide unit in the sheet conveying direction and to convey the sheet by nipping the sheet;
A second conveying member pair that nips the sheet on the upstream side of the guide means in the sheet conveying direction and conveys the sheet to the downstream side;
A third conveying member pair that nips and conveys the sheet to the downstream side on the upstream side in the sheet conveying direction of the second conveying member pair;
A moving unit that moves the guiding unit in a direction intersecting the sheet conveying direction based on the sheet length along the sheet conveying direction,
A paper conveyance device characterized by the above. When the sheet length is longer than the distance between the first pair of transport members and the second pair of transport members in the sheet transport direction, the moving unit releases the nip of the width-shifting unit and guides the guiding unit. Is moved to a position where the side portion of the sheet is not inserted and retracted, and when the sheet length is shorter than the distance between the first conveying member pair and the second conveying member pair in the sheet conveying direction, the width The guide means is moved to a position where the side portion of the sheet is inserted in a state where the approach means is nipped,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The moving means is provided between a link member that holds the guide means, an insertion position that is connected to the link member and in which the side portion of the paper is inserted into the guide means, and a retracted position in which the side portion of the paper is not inserted. And a rotary solenoid that is moved by
The sheet conveying apparatus according to claim 2, wherein the sheet conveying apparatus is a sheet conveying apparatus. A guide unit having a reference surface, one side of which is inserted in a direction intersecting the sheet conveyance direction, and which guides the sheet to the downstream side in the sheet conveyance direction along the reference surface.
A width-shifting unit that shifts the width of the sheet in a direction intersecting the transport direction while the sheet is nipped, and abuts a side edge of the sheet to the reference surface;
A first conveying member pair configured to correct the skew of the sheet by abutting the leading end of the sheet on the downstream side of the guide unit in the sheet conveying direction and to convey the sheet by nipping the sheet;
A second pair of conveying members that nips the sheet on the upstream side in the sheet conveying direction of the guide means and conveys the sheet to the downstream side;
A third conveying member pair that nips the sheet on the upstream side of the second conveying member pair in the sheet conveying direction and conveys the sheet to the downstream side,
When the sheet length along the sheet transport direction is longer than the distance between the first pair of transport members and the third pair of transport members in the sheet transport direction, the width aligning means and the second pair of transport members are After releasing the nip, the third conveying member pair feeds the sheet toward the first conveying member pair to form a loop,
A paper transport device 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 after the first transport member pair starts transporting the paper A conveying speed of the member pair is made higher than a conveying speed of the first conveying member pair,
The sheet conveying apparatus according to claim 4, wherein the sheet conveying apparatus is a sheet conveying apparatus. A sheet 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 characterized by the above.

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