JP2010042903A - Paper conveying device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper conveying device capable of removing a wrinkle from a sheet of paper, which is caused by straightening of the sheet. <P>SOLUTION: The paper conveying device 1A includes two drive rollers 20L, 20R arranged in parallel with each other laterally in relation to a conveyance direction of the paper P and paper feed roller pairs 2L, 2R which have follower rollers 21L, 21R facing the drive rollers, exercising: straightening control in which the device controls paper feed motors 3L, 3R to drive the drive rollers 20L, 20R independently so that the amount of conveyance is different between the left and right sides in relation to the conveyance direction of the paper P, thereby correcting the bending of the paper P detected by a detection sensor 5; and unwrinkling control in which the device controls a crimping/separation mechanism 4R to separate the follower roller 21R constituting the paper feed roller pair 2R on one side from the paper P, thereby removing the wrinkle caused by straightening control from the paper P to restore the paper P by means of its restoring force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus including the sheet conveying apparatus. In particular, the present invention can remove wrinkles of a sheet that occur when correcting the bending of the conveyed sheet.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copiers have incorporated a paper transport device having a function of correcting the skew (skew) of the transported paper. A conventional paper transport device includes a pair of rollers called registration rollers arranged in parallel on the left and right with respect to the paper transport direction, and changes the paper transport speed (transport amount) by the left and right roller pairs. The bend is corrected.

  Such a conventional paper transport device includes a mechanism for separating the transport roller pair disposed in front of the roller pair in the paper transport direction from the paper, and the transport roller pair when the transported paper is long. A technique has been proposed in which wrinkles are separated from the paper and wrinkles that occur in the length direction of the paper are prevented (see, for example, Patent Document 1).

JP-A-8-081089

  However, the conventional sheet conveying apparatus has a problem that wrinkles occur in the width direction of the sheet because the sheet conveying speed by the pair of left and right rollers is changed to correct the bending of the sheet.

  SUMMARY An advantage of some aspects of the invention is to provide a sheet conveying apparatus capable of removing wrinkles generated by correcting the bending of the sheet and an image forming apparatus including the sheet conveying apparatus. The purpose is to provide.

  In order to solve the above-described problem, the present invention provides a sheet feeding device having at least two driving rollers arranged in parallel on the left and right sides with respect to the sheet conveyance direction and a driven roller facing each of the driving rollers. The pair of rollers, the paper feed motor that independently drives the drive roller, and the drive roller or the driven roller are moved in a direction to be separated from and contacted with the paper, and at least one paper feed roller pair is A pressure separation mechanism that performs pressure bonding, a detection sensor that detects whether or not the paper is bent, a paper feed motor that controls the paper to be transported by the drive roller, and the transport amount is different on the left and right with respect to the paper transport direction. Bending correction control that corrects the bending of the paper detected by the detection sensor, and one of the paper feed roller pairs is separated from the paper by controlling the pressure-separation separation mechanism. The word, a sheet conveying apparatus and a control unit for performing wrinkle correction control undo by the restoring force of the paper.

  In addition, the present invention includes an image forming unit that forms an image on a sheet, and a sheet conveying device that conveys the sheet to the image forming unit. A sheet feeding roller pair having at least two driving rollers and a driven roller respectively opposed to the driving roller, a sheet feeding motor for independently driving the driving roller, and a driving roller or a driven roller on the sheet. Controls the pressure separation mechanism that moves and separates the at least one paper feed roller pair from and against the paper, the detection sensor that detects whether the paper is bent, and the paper feed motor. Then, the sheet is conveyed by the drive roller, and the amount of conveyance is varied between the right and left with respect to the sheet conveyance direction, and the bending correction control for correcting the bending of the sheet detected by the detection sensor and the pressure separation mechanism are controlled. And by separating the one of the pair of feeding rollers from the sheet, wrinkles of the sheet generated by the correction control bending, an image forming apparatus and a control unit for performing wrinkle correction control undo by the restoring force of the paper.

  In the paper conveying device and the image forming apparatus according to the present invention, when the detection sensor detects the bending (skew) of the paper, the paper feeding motor is controlled based on the paper bending amount detected by the detection sensor, and the driving roller Are independently driven, and the bending correction control for correcting the bending of the sheet is performed by changing the conveyance amount on the right and left with respect to the conveyance direction of the sheet. After the paper bending correction control is performed, the crimping and separation mechanism is controlled to separate one paper feed roller pair from the paper, and the paper wrinkles generated by the bending correction control are restored to the original with the paper restoring force. Control is performed.

  According to the present invention, when paper skew correction is performed by changing the amount of paper transport between the pair of paper feed rollers arranged side by side with respect to the paper transport direction, Wrinkles generated on the paper can be removed.

  Then, by releasing the pressure-bonding of the paper by the pair of left and right paper feed rollers, the wrinkle is removed by utilizing the restoring force of the paper, so that the paper can be reliably removed with a simple configuration.

  Hereinafter, embodiments of a sheet conveying device and an image forming apparatus according to the present invention will be described with reference to the drawings.

<Configuration Example of Paper Conveying Device of First Embodiment>
FIGS. 1 and 2 are configuration diagrams showing an example of the sheet conveying apparatus according to the first embodiment. FIG. 1A is a diagram of the sheet conveying apparatus according to the first embodiment as viewed from the drive roller side. FIG. 1B is a schematic plan view of the sheet conveying apparatus according to the first embodiment viewed from the driven roller side. FIGS. 2A and 2B are schematic side views of the sheet conveying apparatus according to the first embodiment as viewed from one side with respect to the sheet conveying direction. FIG. 3 is a functional block diagram illustrating an example of a control system of the sheet conveying apparatus according to the first embodiment.

  The sheet conveying apparatus 1A according to the first embodiment includes sheet feeding roller pairs 2L and 2R that convey the sheet P and sheet feeding motors 3L and 3R that independently drive the sheet feeding roller pairs 2L and 2R.

  The paper feed roller pair 2L is provided on the left side with respect to the conveyance direction of the paper P, and includes a drive roller 20L driven by the paper feed motor 3L and a driven roller 21L arranged to face the drive roller 20L. The paper feed roller pair 2R includes a drive roller 20R that is disposed on the right side with respect to the conveyance direction of the paper P and is driven by the paper feed motor 3R, and a driven roller 21R that is disposed to face the drive roller 20R.

  The driving roller 20L and the driving roller 20R are supported on independent shafts and arranged coaxially, and the driven roller 21L and the driven roller 21R are supported on independent shafts and arranged coaxially.

  The driving force of the sheet feeding motor 3L is transmitted to the driving roller 20L, the driving force of the sheet feeding motor 3R is transmitted to the driving roller 20R, and the driving roller 20L and the driving roller 20R can be driven independently.

  The sheet conveying apparatus 1A includes a pressure-separating / separating mechanism 4R for pressing and releasing the pressure-bonding of the paper P by the paper-feed roller pair 2R, in this example, the paper-feed roller pair 2L. The pressure separation / separation mechanism 4R is a support that supports one of the driving roller 20R and the driven roller 21R constituting the paper feed roller pair 2R, in this example, the driven roller 21R so as to be movable in the direction of pressure bonding and separation with respect to the paper P. A member 40R is provided. The crimping / separating mechanism 4R includes a drive unit 41R having a solenoid, a spring, and the like that move the driven roller 21R in the direction of crimping and separating from the paper P.

  The sheet conveying apparatus 1A includes a detection sensor 5 that detects the amount of bending of the sheet P and the like. The detection sensor 5 is composed of, for example, a line sensor, and detects the leading end position of the paper P in the transport direction within a predetermined range in the width direction of the paper P. Also. One side end in the width direction of the paper P, in this example, the left end position with respect to the transport direction is detected.

  Thereby, from the output of the detection sensor 5, whether or not the conveyed paper P is bent, the side edge position of the paper P, and the like are detected. When the paper P is bent, the amount of bending and the direction of bending of the paper P are detected from the output of the detection sensor 5. For example, the left or right leading (delayed) amount in the width direction of the paper P and the left or right leading (delayed) amount are detected.

  The sheet transport apparatus 1 </ b> A includes a control unit 6 that performs transport control of the sheet P based on the output of the detection sensor 5. The control unit 6 controls the paper feeding motor 3L and the paper feeding motor 3R based on the amount of bending and the direction of bending of the paper P detected from the output of the detection sensor 5, and performs the bending correction control for correcting the bending of the paper P. . Further, the crimping / separating mechanism 4R is controlled to perform wrinkle correction control for removing wrinkles generated on the paper P by the bending correction control.

  The sheet conveying apparatus 1A includes an information setting unit 7 in which the sheet information of the sheet P to be conveyed is set. In the information setting unit 7, paper information such as the size, paper type, basis weight, and paper size of the paper P is set in advance by an operator or the like, and the set paper information is stored in a storage unit (not shown).

  The control unit 6 includes information on a re-compression flag N that indicates whether or not the paper P is re-compressed by the driven roller 21R that is separated from the paper P by the wrinkle correction control, and a wrinkle correction time T that is a separation time when re-compression is performed. This is set based on the paper information set by the setting unit 7.

<Configuration example of image forming apparatus>
FIG. 4 is an overall configuration diagram illustrating an example of the image forming apparatus according to the present embodiment to which the sheet conveying device of the present invention is applied. The image forming apparatus 100A according to the present embodiment includes an image forming apparatus main body GH, an image reading apparatus YS, and the like. The image forming apparatus main body GH is called a tandem type color image forming unit, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer member 16, a secondary transfer unit 17A, and the like.

  An image reading device YS including an automatic document feeder 101 and a scanning exposure device 102 is installed on the upper part of the image forming apparatus main body GH. The document d placed on the document table of the automatic document feeder 101 is conveyed by the conveyance unit 101a, and an image on one or both sides of the document d is scanned and exposed by the optical system 102a of the scanning exposure device 102, and a line image sensor. Read into the CCD.

  The image signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in an image processing unit (not shown), and then exposed to the exposure units 13Y, 13M, 13C, 13K. Sent to.

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 12Y, an exposure unit 13Y, a developing unit 14Y, a primary transfer unit 17Y, and a cleaning unit 18Y around a drum-shaped photoconductor 11Y. An image forming unit 10M that forms a magenta (M) color image includes a charging unit 12M, an exposure unit 13M, a developing unit 14M, a primary transfer unit 17M, and a cleaning unit 18M around a drum-shaped photoconductor 11M.

  An image forming unit 10C for forming a cyan (C) color image includes a charging unit 12C, an exposure unit 13C, a developing unit 14C, a primary transfer unit 17C, and a cleaning unit 18C around a drum-shaped photoconductor 11C. The image forming unit 10K that forms a black (Bk) color image includes a charging unit 12K, an exposure unit 13K, a developing unit 14K, a primary transfer unit 17K, and a cleaning unit 18K around a drum-shaped photoconductor 11K. The charging unit 12Y and the exposure unit 13Y, the charging unit 12M and the exposure unit 13M, the charging unit 12C and the exposure unit 13C, and the charging unit 12K and the exposure unit 13K constitute a latent image forming unit.

  The developing units 14Y, 14M, 14C, and 14K contain a two-component developer composed of yellow (Y), magenta (M), cyan (C), and black (K) toner and a carrier.

  The intermediate transfer member 16 is wound around a plurality of rollers and is rotatably supported. The fixing device 19 includes a fixing roller 93 and a pressure roller 94, and fixes the toner image on the paper P by heating and pressing at a nip portion formed between the fixing roller 93 and the pressure roller 94.

  The toner images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating intermediate transfer member 16 by the primary transfer units 17Y, 17M, 17C, and 17K, and then onto the intermediate transfer member 16. A color toner image is formed by superimposing the toner images of the respective colors.

  The paper P stored in the paper feed tray 200 is separated one by one by the separation feeding roller 202 of the paper feed unit 201, and is transported to the paper transport device 1 </ b> A by the paper feed roller 203. In the image forming apparatus 100A, the pair of feed rollers 2L and 2R described with reference to FIGS. 1 and 2 are referred to as registration rollers.

  The paper P fed to the paper feed roller pair 2L, 2R by the paper feed roller 203 is subjected to bending correction control and wrinkle correction control, which will be described later, if necessary, and then temporarily stopped by the paper feed roller pair 2L, 2R. The The paper feed roller pair 2L, 2R starts to rotate at the timing when the leading edge of the paper P and the toner image on the intermediate transfer body 16 coincide with each other, whereby the paper P is fed to the secondary transfer portion 17A. Then, the color toner image is transferred onto the paper P (secondary transfer).

  The paper P on which the color toner image has been transferred is heated and pressurized by the fixing device 19, and the color toner image is fixed on the paper P. The paper P on which the color toner image has been fixed is conveyed to a paper discharge roller 204 and discharged onto a paper discharge tray 205 outside the apparatus.

  On the other hand, after the color toner image is transferred to the paper P by the secondary transfer unit 17A, the residual toner is removed by the intermediate transfer member cleaning unit 18A from the intermediate transfer member 16 that has separated the curvature of the paper P.

  Although the above is an image forming apparatus that forms a color image, an image forming apparatus that forms a monochrome image may be used.

<Example of Operation of Paper Conveying Device of First Embodiment>
FIG. 5 is a flowchart showing an example of the operation of the sheet conveying apparatus of the first embodiment, and FIG. 6 is an explanation of the operation showing an example of the bending correction control and the wrinkle correction control in the sheet conveying apparatus of the first embodiment. Next, operation examples of the sheet conveying apparatus 1A and the image forming apparatus 100A according to the first embodiment will be described with reference to the drawings. In FIG. 6, the pair of paper feed rollers to which the driven roller is pressed against the paper P is indicated by a solid line, and the pair of paper feed rollers from which the driven roller is separated and the pressure is released is schematically indicated by a broken line. ing.

  As described above, the sheet conveying apparatus 1A is incorporated in the image forming apparatus 100A, and prior to the image forming process, the control unit 6 obtains paper information from the information setting unit 7 in the process of step SA1. Then, the control unit 6 sets the re-compression flag N indicating whether or not the paper P is re-compressed by the driven roller 21R after the wrinkle correction control and the wrinkle correction time T when performing the re-compression in the process of step SA2. .

  FIG. 7 is an explanatory diagram of a table showing an example of the relationship between the paper information, the recompression flag, and the wrinkle correction time. In the table 300, a recompression flag N and a wrinkle correction time T are set in accordance with the paper type and paper size set as the paper information. In FIG. 7, the re-compression flag N = 0 is set so that there is no re-compression, and the re-compression flag N = 1 is set to have re-compression. When the re-compression flag N = 1, the wrinkle correction time T is set. The control unit 6 sets the recompression flag N and the wrinkle correction time T with reference to the table 300 based on the paper information obtained from the information setting unit 7.

  In the sheet conveying apparatus 1A, the sheets P stored in the sheet feeding tray 200 of the image forming apparatus 100A are separated one by one by the separation and feeding roller 202 of the sheet feeding unit 201, and are detected by the sheet feeding roller 203 to the detection sensor 5. Paper is fed.

  In step SA3, the control unit 6 detects whether the conveyed paper P is bent from the output of the detection sensor 5. If the paper P is bent, the control unit 6 detects the amount of bending of the paper P.

  When the control unit 6 detects from the output of the detection sensor 5 that the paper P is bent as shown by a solid line in FIG. 6A, the control unit 6 performs correction control for correcting the bending of the paper P in the process of step SA4. In the bending correction control of the paper P, the control unit 6 determines whether the paper feeding motor 3L and the paper feeding motor 3R are necessary for correcting the bending of the paper P based on the bending amount of the paper P detected by the detection sensor 5. Set the drive time and rotation speed.

  The control unit 6 controls the paper feed motor 3L and the paper feed motor 3R with the drive time and the rotational speed set based on the amount of bending of the paper P, and makes a difference between the rotational speeds of the drive roller 20L and the drive roller 20R. To drive. Accordingly, the conveyance amount is different between the left side in the conveyance direction conveyed by the driving roller 20L on the paper P and the right side conveyed by the driving roller 20R, from the state indicated by the two-dot chain line in FIG. As shown by the solid line in FIG. 6B, the leading edge positions of the leading side and the delayed side of the paper P are aligned.

  When the control unit 6 controls the paper feed motor 3L and the paper feed motor 3R based on the bending amount of the paper P detected by the detection sensor 5 to correct the paper P bending, the paper feed motor 3L and the paper feed motor are controlled. 3R is controlled to stop driving of the driving roller 20L and the driving roller 20R.

  In the bending correction control of the paper P, the paper P is transported with a difference in the transport amount by the driving roller 20L and the driving roller 20R arranged on both the left and right sides in the width direction of the paper P, thereby FIG. As shown, the paper P has wrinkles Pe in the width direction. Therefore, correction control for correcting wrinkles of the paper P is performed in the process of step SA5.

  In the wrinkle correction control of the paper P, the control unit 6 controls the pressure-bonding / separating mechanism 4R to separate the driven roller 21R from the paper P as shown in FIG. As a result, the sheet P is held between the driving roller 20L and the driven roller 21L and is pressed on the paper feed roller pair 2L side, and is held on the paper feed roller pair 2R side. And the pressure bonding by the driven roller 21R is released.

  The wrinkle Pe generated on the paper P by the bending correction control causes the driven roller 21R to be separated from the paper P, and the pinching of the paper P by the driving roller 20R and the driven roller 21R is released. As shown in FIG. 6C, the sheet P is returned to a flat state without wrinkles.

  In step SA6, the control unit 6 determines whether the recompression flag N is set to have recompression by the driven roller 21R or not to recompress.

  When the re-compression flag N is set to be re-compressed by the driven roller 21R, the control unit 6 performs the crimping separation mechanism after the wrinkle correction time T set in advance based on the paper information has elapsed in the process of step SA7. 4R is controlled, and the paper P is pressure-bonded to the driving roller 20R by the driven roller 21R.

  In step SA8, the controller 6 controls the paper feed motor 3L in a state where the paper P is sandwiched between the drive rollers 20L and 20R and the driven rollers 21L and 21R by both the paper feed roller pair 2L and the paper feed roller pair 2R. The sheet feeding motor 3R is controlled to drive the driving roller 20L and the driving roller 20R at the same speed, thereby conveying the sheet P.

  When the re-compression flag N is set so that the re-compression by the driven roller 21R is not performed, the control unit 6 maintains the state in which the press-contact by the paper feed roller pair 2R is released. In a state where the paper P is sandwiched between the driving roller 20L and the driven roller 21L, the paper feeding motor 3L is controlled to drive the driving roller 20L and transport the paper P.

  In general, when the paper size is small, even if the paper is transported by only one pair of paper feed rollers, the paper is unlikely to be bent. On the other hand, if the paper size is large, the paper may be bent when the paper is transported only by the pair of paper feed rollers on one side, and the paper must be transported by the pair of paper feed rollers on both sides. Therefore, as the paper information set by the information setting unit 7, as shown in FIG. 7, the paper size can be set. For example, if the paper size is A4, the recompression flag N is used for the recompression. If the paper size is set to A3 or more, the re-compression flag N is set to indicate that there is re-compression. Further, if the surface of the paper is slippery, the paper may be bent when the paper is conveyed only by the pair of paper feed rollers on one side, and the paper needs to be conveyed by the pair of paper feed rollers on both sides. Accordingly, as the paper information set by the information setting unit 7, as shown in FIG. 7, the paper type of the paper can be set. For example, if the paper type is coated paper, the paper size is A4. Even if it exists, it is set by the recompression flag N that recompression is present.

  In this way, for the driven roller separated from the paper by the wrinkle correction control, the presence / absence of re-compression is set according to the paper size and paper type, so that the bend and wrinkle are corrected by the bending correction control and the wrinkle correction control. It is possible to prevent the used paper from being bent and conveyed again. Further, the processing time can be shortened by omitting the re-compression operation for the paper that does not require re-compression. In addition, the setting as to whether or not the re-pressing of the driven roller after the wrinkle correction control may be set using a table as shown in FIG. 7, or a correction amount may be determined and used. Further, the presence / absence of re-pressurization of the driven roller after the wrinkle correction control may be fixed to either one regardless of the paper type or the like.

  In the image forming apparatus 100A described with reference to FIG. 4, the driving roller 20L or the driving rollers 20L and 20R starts to rotate based on the recompression flag N at the timing when the position of the toner image on the intermediate transfer body 16 coincides. Thus, the paper P is fed to the secondary transfer portion 17A.

<Example of Configuration of Paper Conveying Device of Second Embodiment>
FIGS. 8 and 9 are configuration diagrams showing an example of the sheet conveying apparatus according to the second embodiment. FIG. 8A shows the sheet conveying apparatus according to the second embodiment as viewed from the drive roller side. FIG. 8B is a schematic plan view of the sheet conveying apparatus according to the second embodiment viewed from the driven roller side. FIGS. 9A and 9B are schematic side views of the sheet conveying apparatus according to the second embodiment as viewed from one side with respect to the sheet conveying direction. FIG. 10 is a functional block diagram illustrating an example of a control system of the sheet conveying apparatus according to the second embodiment.

  The sheet conveying apparatus 1B according to the second embodiment includes sheet feeding roller pairs 2L and 2R that convey the sheet P and sheet feeding motors 3L and 3R that independently drive the sheet feeding roller pairs 2L and 2R.

  The paper feed roller pair 2L is provided on the left side with respect to the conveyance direction of the paper P, and includes a drive roller 20L driven by the paper feed motor 3L and a driven roller 21L arranged to face the drive roller 20L. The paper feed roller pair 2R includes a drive roller 20R that is disposed on the right side with respect to the conveyance direction of the paper P and is driven by the paper feed motor 3R, and a driven roller 21R that is disposed to face the drive roller 20R.

  The driving roller 20L and the driving roller 20R are supported on independent shafts and arranged coaxially, and the driven roller 21L and the driven roller 21R are supported on independent shafts and arranged coaxially.

  The driving force of the sheet feeding motor 3L is transmitted to the driving roller 20L, the driving force of the sheet feeding motor 3R is transmitted to the driving roller 20R, and the driving roller 20L and the driving roller 20R can be driven independently.

  The sheet transport apparatus 1B includes pressure-bonding / separating mechanisms 4L and 4R that perform pressure-bonding and release of the pressure-bonding of the paper P by the pair of paper feed rollers 2L and 2R. The pressure separation / separation mechanism 4L supports one of the driving roller 20L and the driven roller 21L constituting the paper feed roller pair 2L, in this example, the driven roller 21L so as to be movable in the direction of pressure bonding and separation with respect to the paper P. A member 40L is provided. The crimping / separating mechanism 4L includes a drive unit 41L having a solenoid, a spring, and the like that move the driven roller 21L in the direction of crimping and separating from the paper P.

  The pressure separation / separation mechanism 4R supports one of the driving roller 20R and the driven roller 21R constituting the paper feed roller pair 2R, in this example, the driven roller 21R so as to be movable in the direction of pressure bonding and separation with respect to the paper P. A member 40R is provided. The crimping / separating mechanism 4R includes a drive unit 41R having a solenoid, a spring, and the like that move the driven roller 21R in the direction of crimping and separating from the paper P.

  The sheet transport apparatus 1B includes a detection sensor 5 that detects the amount of bending of the sheet P and the like. The detection sensor 5 is composed of, for example, a line sensor, and detects from the output of the detection sensor 5 whether or not the conveyed paper P is bent, the side edge position of the paper P, and the like. When the paper P is bent, the amount of bending and the direction of bending of the paper P are detected from the output of the detection sensor 5. For example, the left or right leading (delayed) amount in the width direction of the paper P and the left or right leading (delayed) amount are detected.

  The sheet transport apparatus 1B includes a control unit 6 that performs transport control of the sheet P based on the output of the detection sensor 5. The control unit 6 controls the paper feeding motor 3L and the paper feeding motor 3R based on the amount of bending and the direction of bending of the paper P detected from the output of the detection sensor 5, and performs the bending correction control for correcting the bending of the paper P. . Further, the crimping / separating mechanism 4L or the crimping / separating mechanism 4R is controlled based on the bending direction of the paper P detected from the output of the detection sensor 5, and the wrinkle correction control for removing the wrinkles generated on the paper P by the bending correction control is performed. .

  The paper transport apparatus 1B includes an information setting unit 7 in which paper information of the paper P to be transported is set. In the information setting unit 7, paper information such as the size, paper type, basis weight, and paper size of the paper P is set in advance by an operator or the like, and the set paper information is stored in a storage unit (not shown).

  The control unit 6 includes a re-compression flag N that indicates whether or not the paper P is re-compressed by the driven roller 21L or the driven roller 21R that is separated from the paper P by the wrinkle correction control, and a wrinkle correction time that is a separation time when the re-compression is performed. T is set based on the paper information set by the information setting unit 7.

<Example of Operation of Paper Conveying Device of Second Embodiment>
FIG. 11 is a flowchart showing an example of the operation of the sheet conveying apparatus according to the second embodiment. FIGS. 12 and 13 are examples of the bending correction control and the wrinkle correction control in the sheet conveying apparatus according to the second embodiment. Next, operation examples of the sheet conveying apparatus 1B and the image forming apparatus 100A according to the second embodiment will be described with reference to the drawings. 12 and 13, the pair of paper feed rollers to which the driven roller is pressed against the paper P is indicated by a solid line, and the pair of paper feed rollers from which the driven roller is separated and the pressure is released is schematically illustrated. It is indicated by a broken line.

  The paper transport apparatus 1B is incorporated in the image forming apparatus 100A described with reference to FIG. 4, and prior to the image forming process, the control unit 6 obtains paper information from the information setting unit 7 in the process of step SB1. Then, the control unit 6 sets the re-compression flag N and the wrinkle correction time T with reference to the table 300 shown in FIG. 7 based on the paper information obtained from the information setting unit 7 in the process of step SB2.

  In the sheet conveying apparatus 1B, the sheets P stored in the sheet feeding tray 200 of the image forming apparatus 100A are separated one by one by the separation feeding roller 202 of the sheet feeding unit 201, and are detected by the sheet feeding roller 203 to the detection sensor 5. Paper is fed.

  In step SB3, the control unit 6 detects whether or not the conveyed paper P is bent from the output of the detection sensor 5. If the paper P is bent, the control unit 6 determines the amount and direction of bending of the paper P. Detect.

  The control unit 6 uses the detection sensor 5 to determine whether the driven roller 21L or the driven roller 21R is separated from the paper P by the wrinkle correction control in step SB4 to release the pressure bonding to the paper P by the pair of paper feed rollers. Selection is made based on the detected bending direction of the paper P.

  For example, when the bending direction of the paper P detected by the detection sensor 5 is the right leading that precedes the right side of the transport direction of the paper P as shown in FIG. The driven roller 21 </ b> R is selected as the driven roller that releases the pressure bonding with respect to the roller. On the other hand, when the bending direction of the paper P is the left leading position as shown in FIG. 13A, the driven roller 21L is selected as the driven roller for releasing the pressure bonding to the paper P by the wrinkle correction control.

  When the control unit 6 detects from the output of the detection sensor 5 that the paper P is bent, the control unit 6 performs the bending correction control of the paper P in the process of step SB5. In the bending correction control of the paper P, the controller 6 controls the paper feeding motor 3L and the paper feeding required to correct the bending of the paper P based on the bending amount and the bending direction of the paper P detected by the detection sensor 5. The drive time and rotation speed of the motor 3R are set.

  The control unit 6 controls the paper feed motor 3L and the paper feed motor 3R with the driving time and the rotational speed set based on the bending amount and the bending direction of the paper P, and the difference between the rotational speeds of the driving roller 20L and the driving roller 20R is controlled. To drive. As a result, the amount of conveyance differs between the left side of the sheet P with respect to the conveyance direction conveyed by the driving roller 20L and the right side of the sheet P conveyed by the driving roller 20R, so that the preceding side and the delayed side of the sheet P are delayed. Align the tip position.

  For example, when the bending direction of the paper P detected by the detection sensor 5 is right leading as shown in FIG. 12A, the driving of the driving roller 20R on the leading side of the paper P is stopped, and the paper The driving roller 20L on the delayed side of P is driven. Alternatively, the drive roller 20R is driven at a lower speed than the drive roller 20L. As a result, the transport amount by the drive roller 20L and the drive roller 20R is differentiated, and the leading edge of the paper P is advanced from the state indicated by the two-dot chain line in FIG. 12B, as indicated by the solid line in FIG. Align the left tip position that is delayed with the right tip position.

  On the other hand, when the bending direction of the paper P detected by the detection sensor 5 is the left leading as shown in FIG. 13A, the driving of the driving roller 20L on the leading side of the paper P is stopped, and the paper The driving roller 20R on the delayed side of P is driven. Alternatively, the drive roller 20L is driven at a lower speed than the drive roller 20R. As a result, the transport amount by the driving roller 20L and the driving roller 20R is differentiated, and the leading edge of the sheet P is changed from the state indicated by the two-dot chain line in FIG. 13B to the solid line in FIG. 13B. Align the right tip position that is delayed with the left tip position.

  When the control unit 6 controls the sheet feeding motor 3L and the sheet feeding motor 3R based on the amount of bending and the direction of bending of the sheet P detected by the detection sensor 5, and corrects the bending of the sheet P, the control unit 6 The paper feed motor 3R is controlled to stop driving of the drive roller 20L and the drive roller 20R.

  In the bending correction control of the paper P, the paper P is transported with a difference in the transport amount by the driving roller 20L and the driving roller 20R disposed on both the left and right sides in the width direction of the paper P, and FIG. As shown in FIG. 13B, the paper P has wrinkles Pe in the width direction. Therefore, correction control for correcting wrinkles of the paper P is performed in the process of step SB6.

  In the wrinkle correction control of the paper P, the control unit 6 separates the driven roller selected in the process of step SB4 described above from the paper P based on the bending direction of the paper P detected by the detection sensor 5, and the bending correction control. Thus, the crimping to the paper P by the driven roller on the wrinkled side is released.

  For example, when the bending direction of the paper P detected by the detection sensor 5 is right leading, the control unit 6 controls the pressure-separation separation mechanism 4R as shown in FIG. Separate from. As a result, the sheet P is held between the driving roller 20L and the driven roller 21L and is pressed on the paper feed roller pair 2L side, and is held on the paper feed roller pair 2R side. And the pressure bonding by the driven roller 21R is released.

  The wrinkle Pe generated on the paper P by the bending correction control causes the driven roller 21R to be separated from the paper P, and the pinching of the paper P by the driving roller 20R and the driven roller 21R is released. As shown in FIG. 12C, the sheet P is returned to a flat state without wrinkles.

  On the other hand, if the bending direction of the paper P detected by the detection sensor 5 is the left leading, the control unit 6 controls the pressure separating / separating mechanism 4L as shown in FIG. Separate from. As a result, the sheet P is held between the driving roller 20R and the driven roller 21R and pressed on the sheet feeding roller pair 2R side, and is held on the sheet feeding roller pair 2L side, and the driving roller 20L on the sheet feeding roller pair 2L side. Then, the pressure bonding by the driven roller 21L is released.

  The wrinkle Pe generated on the paper P by the bending correction control is caused by the restoring force due to the stiffness of the paper P by separating the driven roller 21L from the paper P and releasing the holding of the paper P by the driving roller 20L and the driven roller 21L. As shown in FIG. 13C, the sheet P is returned to a flat state without wrinkles.

  Depending on the bending direction of the paper P and the conveyance method of the paper P in the bending correction control, it may be desirable that the left and right driven roller pairs be separated from the paper P. Therefore, in the paper conveyance device 1B according to the second embodiment, by selecting a driven roller pair that is separated from the paper P in accordance with the bending direction of the paper P, the bending correction is performed in response to various forms of paper bending. In addition, wrinkles can be removed.

  In step SB7, the control unit 6 determines whether the recompression flag N is set to have recompression by the driven roller 21L or the driven roller 21R or not to recompress.

  If the re-compression flag N is set to have re-compression, the control unit 6 controls the crimping separation mechanism after the wrinkle correction time T set in advance based on the paper information has elapsed in the process of step SB8. Then, the paper P is pressed against the paper feed roller by the driven roller.

  When the bending direction of the paper P is right leading, after the wrinkle correction time T has elapsed, the pressure separation mechanism 4R is controlled so that the paper P is pressure-bonded to the driving roller 20R by the driven roller 21R. On the other hand, when the bending direction of the paper P is the left leading, after the wrinkle correction time T elapses, the pressure separation mechanism 4L is controlled, and the paper P is pressure-bonded to the driving roller 20L by the driven roller 21L.

  Then, in the process of step SB9, the controller 6 feeds the paper feed motor 3L in a state where the paper P is sandwiched between the drive rollers 20L and 20R and the driven rollers 21L and 21R by both the paper feed roller pair 2L and the paper feed roller pair 2R. The sheet feeding motor 3R is controlled to drive the driving roller 20L and the driving roller 20R at the same speed, thereby conveying the sheet P.

  When the re-compression flag N is set so that the re-compression by the driven roller is not performed, the control unit 6 conveys the paper P by the pair of paper feed rollers that are not released from the crimp by the wrinkle correction control.

  When the curving direction of the paper P is right-leading, the re-crimping operation of the driven roller 21R that has been crimped by the wrinkle correction control is not performed, and the feed roller pair 2L and the driving roller 20L are not processed in step SB9. In a state where the paper P is sandwiched by the driven roller 21L, the paper feed motor 3L is controlled to drive the driving roller 20L, and the paper P is conveyed. On the other hand, when the bending direction of the paper P is the left leading, the re-crimping operation of the driven roller 21L whose pressure is released by the wrinkle correction control is not performed, and the driving roller is driven by the paper feed roller pair 2R in the process of step SB9. The sheet feeding motor 3R is controlled to drive the driving roller 20R in a state where the sheet P is sandwiched between the 20R and the driven roller 21R, and the sheet P is conveyed.

  In the image forming apparatus 100A, the driving roller 20L or the driving roller 20R, or both the driving roller 20L and the driving roller 20R are rotated based on the recompression flag N at the timing when the position of the toner image on the intermediate transfer body 16 coincides. Is started, the paper P is fed to the secondary transfer portion 17A.

<Configuration Example of Paper Conveying Device of Third Embodiment>
FIGS. 14 and 15 are configuration diagrams showing an example of the sheet conveying apparatus according to the third embodiment. FIG. 14A is a diagram illustrating the sheet conveying apparatus according to the third embodiment as viewed from the drive roller side. FIG. 14B is a schematic plan view of the sheet conveying apparatus according to the third embodiment viewed from the driven roller side. FIGS. 15A and 15B are schematic side views of the sheet conveying apparatus according to the third embodiment as viewed from one side with respect to the sheet conveying direction. FIG. 16 is a functional block diagram illustrating an example of a control system of the sheet conveying apparatus according to the third embodiment.

  The sheet conveying apparatus 1C according to the third embodiment includes a pressing roller pair 8 capable of releasing the pressure bonding to the sheet P between the sheet feeding roller pairs 2L and 2R in the sheet conveying apparatus 1A according to the first embodiment. Prepare. Note that the sheet conveying apparatus 1C according to the third embodiment has the same configuration as the sheet conveying apparatus 1A according to the first embodiment except for the configuration related to the pressing roller pair 8 and the pressing roller pair 8, and thus the same. A number is attached and detailed explanation is omitted.

  The pair of pressing rollers 8 includes a non-driving roller 80 disposed in the center with respect to the conveyance direction of the paper P and a pressing roller 81 disposed to face the non-driving roller 80. The non-driving roller 80 is supported on a shaft independent of the driving roller 20L and the driving roller 20R and is arranged coaxially. The pressing roller 81 is supported on a shaft independent of the driven roller 21L and the driven roller 21R, and is arranged coaxially.

  The sheet conveying apparatus 1 </ b> C includes a pressure separation / separation mechanism 9 that performs nipping and releasing nipping of the sheet P by the pressing roller pair 8. The pressure separation / separation mechanism 9 supports either the non-driving roller 80 or the pressure roller 81 constituting the pressure roller pair 8, in this example, the pressure roller 81 movably supported with respect to the paper P in the direction of pressure bonding and separation. A member 90 is provided. Further, the press-separating / separating mechanism 9 includes a drive unit 91 having a solenoid, a spring, and the like that move the pressing roller 81 in a direction in which the pressing roller 81 is pressed and separated from the paper P.

<Example of Operation of Paper Conveying Device of Third Embodiment>
FIG. 17 is a flowchart showing an example of the operation of the sheet conveying apparatus of the third embodiment, and FIG. 18 is an explanation of the operation showing an example of the bending correction control and the wrinkle correction control in the sheet conveying apparatus of the third embodiment. Next, operation examples of the sheet conveying apparatus 1C and the image forming apparatus 100A according to the third embodiment will be described with reference to the drawings. In FIG. 18, the pair of paper feed rollers to which the driven roller is pressure-bonded to the paper P and the pair of pressure rollers to which the pressure roller is pressure-bonded are indicated by solid lines, and the pressure is released after the driven roller is separated. A pair of pressing rollers, in which the pair of pressing rollers and the pressing rollers are separated and the pressure bonding is released, is schematically indicated by broken lines.

  The paper conveying apparatus 1C is incorporated in the image forming apparatus 100A described with reference to FIG. 4, and the control unit 6 obtains paper information from the information setting unit 7 in the process of step SC1 prior to the image forming process. Then, the control unit 6 sets the recompression flag N and the wrinkle correction time T with reference to the table 300 shown in FIG. 7 based on the paper information obtained from the information setting unit 7 in the process of step SC2.

  In the sheet conveying apparatus 1C, the sheets P stored in the sheet feeding tray 200 of the image forming apparatus 100A are separated one by one by the separation and feeding roller 202 of the sheet feeding unit 201, and are detected by the sheet feeding roller 203 to the detection sensor 5. Paper is fed. Here, in the step of feeding the paper P from the paper feed tray 200 of the image forming apparatus 100A, the pressure separation mechanism 9 is controlled to retract the pressure roller 81 to a position away from the paper P, and the pressure roller pair 8 Then, it is assumed that the paper P is not pinched.

  In step SC3, the control unit 6 detects whether the conveyed paper P is bent from the output of the detection sensor 5. If the paper P is bent, the control unit 6 detects the amount of bending of the paper P.

  When detecting that the paper P is bent as shown in FIG. 18A from the output of the detection sensor 5, the control unit 6 performs correction control for correcting the bending of the paper P in the process of step SC4. In the bending correction control of the paper P, the control unit 6 determines whether the paper feeding motor 3L and the paper feeding motor 3R are necessary for correcting the bending of the paper P based on the bending amount of the paper P detected by the detection sensor 5. Set the drive time and rotation speed.

  The control unit 6 controls the paper feed motor 3L and the paper feed motor 3R with the drive time and the rotational speed set based on the amount of bending of the paper P, and makes a difference between the rotational speeds of the drive roller 20L and the drive roller 20R. To drive. As a result, the conveyance amount on the left side of the sheet P with respect to the conveyance direction conveyed by the driving roller 20L and the right side conveyed by the driving roller 20R are different from the state indicated by the two-dot chain line in FIG. As shown by a solid line in FIG. 18B, the leading edge positions of the leading side and the delayed side of the paper P are aligned.

  When the control unit 6 controls the paper feed motor 3L and the paper feed motor 3R based on the bending amount of the paper P detected by the detection sensor 5 to correct the paper P bending, the paper feed motor 3L and the paper feed motor are controlled. 3R is controlled to stop driving of the driving roller 20L and the driving roller 20R.

  In the bending correction control of the paper P, the paper P is transported with a difference in the transport amount by the driving roller 20L and the driving roller 20R arranged on both the left and right sides in the width direction of the paper P, so that FIG. As shown, the paper P has wrinkles Pe in the width direction. Therefore, correction control for correcting the wrinkles of the paper P is performed in the process of step SC5.

  In the wrinkle correction control for the paper P, the control unit 6 controls the pressure-bonding / separating mechanism 4R to separate the driven roller 21R from the paper P. As a result, the sheet P is held between the driving roller 20L and the driven roller 21L and is pressed on the paper feed roller pair 2L side, and is held on the paper feed roller pair 2R side. And the pressure bonding by the driven roller 21R is released.

  When the controller 6 cancels the pressure bonding of the paper P by the driven roller 21R, the control roller 81 controls the pressure separating / separating mechanism 9 to press the pressure roller 81 that is separated from the paper P in the process of step SC6. P is sandwiched between the non-driving roller 80 and the pressing roller 81.

  As a result, the wrinkle Pe generated on the paper P by the bending correction control is stretched by pressing the restoring force due to the stiffness of the paper P and the vicinity of the center of the paper P where the wrinkle is easily generated by the bending correction control with the pressing roller pair 8. As shown in FIG. 18C, the paper P is returned to a flat state without wrinkles.

  In step SC7, the controller 6 determines whether the recompression flag N is set to have recompression by the driven roller 21R or not to recompress.

  If the re-compression flag N is set to be re-compressed by the driven roller 21R, the control unit 6 performs the process of step SC8 after the wrinkle correction time T set in advance based on the paper information has elapsed, 4R is controlled, and the paper P is pressure-bonded to the driving roller 20R by the driven roller 21R.

  Then, in the process of step SC9, the controller 6 controls the paper feed motor 3L in a state where the paper P is sandwiched between the drive rollers 20L and 20R and the driven rollers 21L and 21R by both the paper feed roller pair 2L and the paper feed roller pair 2R. The sheet feeding motor 3R is controlled to drive the driving roller 20L and the driving roller 20R at the same speed, thereby conveying the sheet P.

  When the re-compression flag N is set so that the re-compression is not performed by the driven roller 21R, the control unit 6 holds the sheet P between the driving roller 20L and the driven roller 21L by the feed roller pair 2L in the process of step SC9. Then, the sheet feeding motor 3L is controlled to drive the driving roller 20L, and the sheet P is conveyed. In the step of transporting the paper P after the wrinkle correction control, the pressure-bonding / separating mechanism 9 may be controlled to separate the pressing roller 81 from the paper P, and the nipping between the non-driving roller 80 and the pressing roller 81 may be released.

  In the image forming apparatus 100A, the driving roller 20L or the driving rollers 20L and 20R starts to rotate based on the re-compression flag N at the timing when the position of the toner image on the intermediate transfer body 16 coincides, so that the sheet P is rotated. The paper is fed to the secondary transfer unit 17A.

<Another example of operation of the sheet conveying apparatus according to the third embodiment>
FIG. 19 is a flowchart illustrating another example of the operation of the sheet conveying apparatus according to the third embodiment. Next, with reference to the drawings, the sheet conveying apparatus 1C and the image forming apparatus 100A according to the third embodiment are described. Another operation example will be described.

  In the sheet conveying apparatus 1C, the sheets P stored in the sheet feeding tray 200 of the image forming apparatus 100A are separated one by one by the separation and feeding roller 202 of the sheet feeding unit 201, and are detected by the sheet feeding roller 203 to the detection sensor 5. Paper is fed. Here, in the step of feeding the paper P from the paper feed tray 200 of the image forming apparatus 100A, the pressure separation mechanism 9 is controlled to retract the pressure roller 81 to a position away from the paper P, and the pressure roller pair 8 Then, it is assumed that the paper P is not pinched.

  In step SD1, the control unit 6 detects whether or not the conveyed paper P is bent from the output of the detection sensor 5. If the paper P is bent, the control unit 6 detects the amount of bending of the paper P.

  When the control unit 6 detects from the output of the detection sensor 5 that the paper P is bent, the control unit 6 performs correction control for correcting the bending of the paper P in the process of step SD2. In the bending correction control of the paper P, the control unit 6 determines whether the paper feeding motor 3L and the paper feeding motor 3R are necessary for correcting the bending of the paper P based on the bending amount of the paper P detected by the detection sensor 5. Set the drive time and rotation speed.

  The control unit 6 controls the paper feed motor 3L and the paper feed motor 3R with the drive time and the rotational speed set based on the amount of bending of the paper P, and makes a difference between the rotational speeds of the drive roller 20L and the drive roller 20R. To drive. As a result, the amount of conveyance differs between the left side of the sheet P with respect to the conveyance direction conveyed by the driving roller 20L and the right side of the sheet P conveyed by the driving roller 20R, so that the preceding side and the delayed side of the sheet P are delayed. Align the tip position.

  When the control unit 6 controls the paper feed motor 3L and the paper feed motor 3R based on the bending amount of the paper P detected by the detection sensor 5 to correct the paper P bending, the paper feed motor 3L and the paper feed motor are controlled. 3R is controlled to stop driving of the driving roller 20L and the driving roller 20R.

  In the bending correction control of the paper P, the paper P is transported in the width direction by transporting the paper P with a difference in the transport amount by the driving roller 20L and the driving roller 20R arranged on the left and right sides in the width direction of the paper P. Wrinkles occur. Therefore, correction control for correcting the wrinkles of the paper P is performed in the process of step SD3.

  In the wrinkle correction control for the paper P, the control unit 6 controls the pressure-bonding / separating mechanism 4R to separate the driven roller 21R from the paper P. Accordingly, the sheet P is held between the driving roller 20L and the driven roller 21L on the paper feed roller pair 2L side, and the driving roller 20R and the driven roller are held on the paper feed roller pair 2R side. The clamping by 21R is released.

  When the controller 6 releases the pressure bonding of the paper P by the driven roller 21R, the pressing roller 81 separated from the paper P is pressed against the paper P by controlling the pressure separation mechanism 9 in the process of step SD4. P is sandwiched between the non-driving roller 80 and the pressing roller 81.

  Thus, the wrinkles generated on the paper P by the bending correction control are stretched by pressing the restoring force due to the stiffness of the paper P and the vicinity of the center of the paper P where the wrinkles are easily generated by the bending correction control with the pressing roller pair 8. The paper P is returned to a flat state without wrinkles.

  When the sheet P is nipped by the pair of pressing rollers 8 in the wrinkle correction control, the control unit 6 controls the sheet feeding motor 3L while the sheet P is nipped by the driving roller 20L and the driven roller 21L by the pair of sheet feeding rollers 2L. The driving roller 20L is driven and the paper P is conveyed. By separating the driven roller 21R from the paper P by the wrinkle correction control, the paper P is clamped by the driving roller 20L and the driven roller 21R on the paper feed roller pair 2R side in the paper P transport process after the wrinkle correction control. Not. However, the paper P can be stably conveyed by holding the paper P between the non-driving roller 80 and the pressure roller 81 by the pressure roller pair 8.

  In the image forming apparatus 100A, when the position of the toner image on the intermediate transfer body 16 coincides, the driving roller 20L starts to rotate based on the recompression flag N, whereby the paper P is transferred to the secondary transfer unit 17A. Paper is fed.

<Configuration Example of Paper Conveying Device of Fourth Embodiment>
20 and 21 are configuration diagrams showing an example of the sheet conveying apparatus of the fourth embodiment. FIG. 20A shows the sheet conveying apparatus of the fourth embodiment as viewed from the drive roller side. FIG. 20B is a schematic plan view of the paper conveying device according to the fourth embodiment as viewed from the driven roller side. FIGS. 21A and 21B are schematic side views of the sheet conveying apparatus according to the fourth embodiment as viewed from one side with respect to the sheet conveying direction. FIG. 22 is a functional block diagram illustrating an example of a control system of the sheet conveying apparatus according to the fourth embodiment.

  In the sheet conveying apparatus 1D of the fourth embodiment, in the sheet conveying apparatus 1B of the second embodiment, a pressing roller pair 8 capable of releasing the pressure bonding to the sheet P is provided between the sheet feeding roller pair 2L and 2R. Prepare. Note that the sheet conveying apparatus 1D according to the fourth embodiment has the same configuration as the sheet conveying apparatus 1B according to the second embodiment except for the configuration related to the pressing roller pair 8 and the pressing roller pair 8, and therefore the same. A number is attached and detailed explanation is omitted.

  The pair of pressing rollers 8 includes a non-driving roller 80 disposed in the center with respect to the conveyance direction of the paper P and a pressing roller 81 disposed to face the non-driving roller 80. The non-driving roller 80 is supported on a shaft independent of the driving roller 20L and the driving roller 20R and is arranged coaxially. The pressing roller 81 is supported on a shaft independent of the driven roller 21L and the driven roller 21R, and is arranged coaxially.

  The sheet conveying apparatus 1D includes a pressure-bonding / separating mechanism 9 that holds and releases the sheet P by the pressing roller pair 8. The pressure separation / separation mechanism 9 supports either the non-driving roller 80 or the pressure roller 81 constituting the pressure roller pair 8, in this example, the pressure roller 81 movably supported with respect to the paper P in the direction of pressure bonding and separation. A member 90 is provided. Further, the press-separating / separating mechanism 9 includes a drive unit 91 having a solenoid, a spring, and the like that move the pressing roller 81 in a direction in which the pressing roller 81 is pressed and separated from the paper P.

<Operation Example of Paper Conveying Device of Fourth Embodiment>
FIG. 23 is a flowchart showing an example of the operation of the sheet conveying apparatus of the fourth embodiment. FIGS. 24 and 25 are examples of the bending correction control and the wrinkle correction control in the sheet conveying apparatus of the fourth embodiment. Next, operation examples of the sheet conveying apparatus 1D and the image forming apparatus 100A according to the fourth embodiment will be described with reference to the drawings. In FIGS. 24 and 25, the pair of paper feed rollers to which the driven roller is pressure-bonded to the paper P and the pair of pressure rollers to which the pressure roller is pressure-bonded are indicated by solid lines, and the pressure is released when the driven roller is separated. The pair of sheet feeding rollers and the pair of pressure rollers that are separated from each other and the pressure bonding is released are schematically shown by broken lines.

  In the sheet conveying apparatus 1D, the sheets P stored in the sheet feeding tray 200 of the image forming apparatus 100A are separated one by one by the separation and feeding roller 202 of the sheet feeding unit 201, and are detected by the sheet feeding roller 203 to the detection sensor 5. Paper is fed. Here, in the step of feeding the paper P from the paper feed tray 200 of the image forming apparatus 100A, the pressure separation mechanism 9 is controlled to retract the pressure roller 81 to a position away from the paper P, and the pressure roller pair 8 Then, it is assumed that the paper P is not pinched.

  In the process of step SE1, the control unit 6 detects whether or not the conveyed paper P is bent from the output of the detection sensor 5. If the paper P is bent, the control unit 6 determines the amount and direction of bending of the paper P. Detect.

  In the process of step SE2, the control unit 6 determines whether the driven roller 21L or the driven roller 21R is separated from the paper P by the wrinkle correction control to release the pressure bonding to the paper P, or the paper P detected by the detection sensor 5. Select based on the direction of the turn.

  For example, when the bending direction of the paper P detected by the detection sensor 5 is a right leading preceding the right side with respect to the conveyance direction of the paper P as shown in FIG. The driven roller 21 </ b> R is selected as the driven roller that releases the pressure bonding with respect to the roller. On the other hand, when the bending direction of the sheet P is the left leading position as shown in FIG. 25A, the driven roller 21L is selected as the driven roller for releasing the pressure bonding to the sheet P by the wrinkle correction control.

  When the control unit 6 detects that the paper P is bent from the output of the detection sensor 5, the control unit 6 performs the bending correction control of the paper P in the process of step SE3. In the bending correction control of the paper P, the controller 6 controls the paper feeding motor 3L and the paper feeding required to correct the bending of the paper P based on the bending amount and the bending direction of the paper P detected by the detection sensor 5. The drive time and rotation speed of the motor 3R are set.

  The control unit 6 controls the paper feed motor 3L and the paper feed motor 3R with the driving time and the rotational speed set based on the bending amount and the bending direction of the paper P, and the difference between the rotational speeds of the driving roller 20L and the driving roller 20R is controlled. To drive. As a result, the amount of conveyance differs between the left side of the sheet P with respect to the conveyance direction conveyed by the driving roller 20L and the right side of the sheet P conveyed by the driving roller 20R, so that the preceding side and the delayed side of the sheet P are delayed. Align the tip position.

  For example, when the bending direction of the paper P detected by the detection sensor 5 is right leading as shown in FIG. 24A, the driving of the driving roller 20R on the leading side of the paper P is stopped, and the paper The driving roller 20L on the delayed side of P is driven. Alternatively, the drive roller 20R is driven at a lower speed than the drive roller 20L. As a result, the transport amount by the drive roller 20L and the drive roller 20R is differentiated, and the leading edge of the sheet P is changed from the state indicated by the two-dot chain line in FIG. 24B to the solid line in FIG. Align the left tip position that is delayed with the right tip position.

  On the other hand, when the bending direction of the paper P detected by the detection sensor 5 is the left leading as shown in FIG. 25A, the driving of the driving roller 20L on the leading side of the paper P is stopped, and the paper The driving roller 20R on the delayed side of P is driven. Alternatively, the drive roller 20L is driven at a lower speed than the drive roller 20R. As a result, the transport amount by the driving roller 20L and the driving roller 20R is differentiated, and the leading edge of the sheet P is advanced from the state indicated by the two-dot chain line in FIG. 25B, as indicated by the solid line in FIG. Align the right tip position that is delayed with the left tip position.

  When the control unit 6 controls the sheet feeding motor 3L and the sheet feeding motor 3R based on the amount of bending and the direction of bending of the sheet P detected by the detection sensor 5, and corrects the bending of the sheet P, the control unit 6 The paper feed motor 3R is controlled to stop driving of the drive roller 20L and the drive roller 20R.

  In the bending correction control of the paper P, the paper P is transported with a difference in the transport amount by the driving roller 20L and the driving roller 20R arranged on both the left and right sides in the width direction of the paper P, and FIG. As shown in FIG. 25B, the paper P has wrinkles Pe in the width direction. Therefore, correction control for correcting the wrinkles of the paper P is performed in the process of step SE4.

  In the wrinkle correction control of the paper P, the control unit 6 separates the driven roller selected in the process of step SE2 described above from the paper P based on the bending direction of the paper P detected by the detection sensor 5, and performs the bending correction control. Thus, the crimping to the paper P by the driven roller on the wrinkled side is released.

  For example, if the bending direction of the paper P detected by the detection sensor 5 is right leading, the control unit 6 controls the pressure-separation separation mechanism 4R as shown in FIG. Separate from. As a result, the sheet P is held between the driving roller 20L and the driven roller 21L and is pressed on the paper feed roller pair 2L side, and is held on the paper feed roller pair 2R side. And the pressure bonding by the driven roller 21R is released.

  On the other hand, if the bending direction of the paper P detected by the detection sensor 5 is the left leading, the control unit 6 controls the pressure separation / separation mechanism 4L to move the driven roller 21L to the paper P as shown in FIG. Separate from. As a result, the sheet P is held between the driving roller 20R and the driven roller 21R and pressed on the sheet feeding roller pair 2R side, and is held on the sheet feeding roller pair 2L side, and the driving roller 20L on the sheet feeding roller pair 2L side. Then, the pressure bonding by the driven roller 21L is released.

  When the controller 6 cancels the pressure bonding of the paper P by the driven roller 21L or the driven roller 21R based on the bending direction of the paper P, the pressing roller 81 that is separated from the paper P is pressed against the pressure separating mechanism 9 in the process of step SE5. Is controlled to be pressed against the paper P, and the paper P is sandwiched between the non-driving roller 80 and the pressing roller 81.

  As a result, the wrinkle Pe generated on the paper P by the bending correction control is stretched by pressing the restoring force due to the stiffness of the paper P and the vicinity of the center of the paper P where the wrinkle is easily generated by the bending correction control with the pressing roller pair 8. 24 (c) and 25 (c), the paper P is returned to a flat state without wrinkles.

  When the sheet P is held by the pressing roller pair 8 by the wrinkle correction control, the control unit 6 holds the sheet P by the driving roller and the driven roller by the sheet feeding roller pair 2L or the sheet feeding roller pair 2R in the process of step SE6. Then, the sheet feeding motor 3L or the sheet feeding motor 3R is controlled to drive the driving roller 20L or the driving roller 20R, and the sheet P is conveyed. By separating the driven roller 21L or the driven roller 21R from the paper P by the wrinkle correction control, in the transport process of the paper P after the wrinkle correction control, the paper P is driven by the driving roller and the driven roller on one paper feed roller pair side. Is not pinched. However, the paper P can be stably conveyed by holding the paper P between the non-driving roller 80 and the pressure roller 81 by the pressure roller pair 8.

  In the image forming apparatus 100A, the driving roller 20L or the driving roller 20R, or both the driving roller 20L and the driving roller 20R are rotated based on the recompression flag N at the timing when the position of the toner image on the intermediate transfer body 16 coincides. Is started, the paper P is fed to the secondary transfer portion 17A.

  The present invention is applied to an image forming apparatus having a function of correcting skew of a sheet.

It is a block diagram which shows an example of the paper conveying apparatus of 1st Embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 1st Embodiment. FIG. 3 is a functional block diagram illustrating an example of a control system of the sheet conveying device according to the first embodiment. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. 4 is a flowchart illustrating an example of an operation of the sheet conveying apparatus according to the first embodiment. FIG. 6 is an operation explanatory diagram illustrating an example of a bending correction control and a wrinkle correction control in the paper conveyance device according to the first embodiment. It is explanatory drawing of the table which shows an example of the relationship between paper information, a re-bonding flag, and a wrinkle correction time. It is a block diagram which shows an example of the paper conveying apparatus of 2nd Embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 2nd Embodiment. FIG. 10 is a functional block diagram illustrating an example of a control system of a sheet conveying device according to a second embodiment. 10 is a flowchart illustrating an example of the operation of the sheet conveying apparatus according to the second embodiment. FIG. 10 is an operation explanatory diagram illustrating an example of bending correction control and wrinkle correction control in the paper conveyance device according to the second embodiment. FIG. 10 is an operation explanatory diagram illustrating an example of bending correction control and wrinkle correction control in the paper conveyance device according to the second embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 3rd Embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 3rd Embodiment. FIG. 10 is a functional block diagram illustrating an example of a control system of a sheet conveying device according to a third embodiment. 10 is a flowchart illustrating an example of an operation of the sheet conveying apparatus according to the third embodiment. FIG. 10 is an operation explanatory diagram illustrating an example of a bending correction control and a wrinkle correction control in the paper conveyance device according to the third embodiment. 10 is a flowchart illustrating another example of the operation of the sheet conveying apparatus according to the third embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 4th Embodiment. It is a block diagram which shows an example of the paper conveying apparatus of 4th Embodiment. FIG. 10 is a functional block diagram illustrating an example of a control system of a sheet conveying device according to a fourth embodiment. 10 is a flowchart illustrating an example of an operation of a sheet conveying apparatus according to a fourth embodiment. FIG. 15 is an operation explanatory diagram illustrating an example of a bending correction control and a wrinkle correction control in the paper conveyance device according to the fourth embodiment. FIG. 15 is an operation explanatory diagram illustrating an example of a bending correction control and a wrinkle correction control in the paper conveyance device according to the fourth embodiment.

Explanation of symbols

  1A to 1D: Paper transport device, 2L, 2R: Paper feed roller pair, 20L, 20R: Drive roller, 21L, 21R: Driven roller, 3L, 3R: Paper feed motor, 4L , 4R: pressure separation mechanism, 5: detection sensor, 6: control unit, 7: information setting unit, 8: press roller pair, 80: non-driving roller, 81.・ Pressing roller, 9 ... Pressing and separating mechanism

Claims (7)

A pair of paper feed rollers having at least two drive rollers arranged in parallel on the left and right with respect to the paper conveyance direction and driven rollers respectively facing the drive rollers;
A paper feed motor for independently driving the drive roller;
A pressure-separation separation mechanism that moves the driving roller or the driven roller in a direction in which the driving roller or the driven roller is separated from or contacted with the paper, and separates and presses at least one of the paper feeding roller pairs with respect to the paper;
A detection sensor for detecting whether the paper is bent,
Bending correction control for controlling the sheet feeding motor to convey the sheet with the driving roller, and varying the amount of conveyance on the right and left with respect to the sheet conveying direction to correct the bending of the sheet detected by the detection sensor; A control unit that controls the pressure-separation mechanism to separate one of the pair of paper feed rollers from the paper, and performs wrinkle correction control that restores the wrinkle of the paper generated by the bending correction control to the original by the restoring force of the paper. A sheet conveying apparatus characterized by the above. The pair of paper feed rollers arranged side by side with respect to the paper transport direction are each provided with the pressure-bonding separation mechanism.
The control unit selects the paper feed roller pair to be separated from the paper by the wrinkle correction control based on the paper bending direction detected by the detection sensor and controls the pressure-bonding separation mechanism, and according to the paper bending direction. The sheet conveying apparatus according to claim 1, wherein wrinkle correction control is performed by separating the other pair of sheet feeding rollers from the sheet. The control unit holds one of the paper feed roller pairs separated from the sheet by the wrinkle correction control in a state of being separated from the sheet and the other of the other of the two of the paper rollers held in a state of being crimped to the sheet by the wrinkle correction control. The sheet conveying apparatus according to claim 1, wherein the sheet that has undergone the bending correction control and the wrinkle correction control is conveyed by the pair of sheet feeding rollers. The control unit re-compresses one of the paper feed roller pairs separated from the paper by the wrinkle correction control, and the one paper feed roller pair re-compressed to the paper after the wrinkle correction control and the wrinkle correction control. 3. The paper conveying apparatus according to claim 1, wherein the paper having undergone the bending correction control and the wrinkle correction control is conveyed by the other pair of paper feed rollers held in a state of being pressed against the paper. . It has an information setting section that sets the paper type information of the paper,
The control unit determines whether or not re-compression is performed by the one pair of paper feed rollers separated from the paper by the wrinkle correction control, and when re-compression is performed by the pair of paper feed rollers separated from the paper. Is determined based on the paper type information set in the information setting unit,
If it is determined that re-crimping will not be performed, the pair of paper feed rollers separated from the paper by wrinkle correction control is held in a state of being separated from the paper, and held in a state of being crimped to the paper by wrinkle correction control. The other pair of paper feed rollers is used to transport the paper subjected to the bending correction control and the wrinkle correction control,
If it is determined that re-crimping is performed, the pair of paper feed rollers separated from the paper by the wrinkle correction control is re-press-bonded to the paper in accordance with a preset correction time, and is re-press-bonded to the paper after the wrinkle correction control. One of the pair of paper feed rollers and the other pair of paper feed rollers held in a state of being pressed against the paper by the wrinkle correction control convey the paper subjected to the bending correction control and the wrinkle correction control. The sheet conveying apparatus according to claim 1 or 2. A pair of pressing rollers disposed between the pair of paper feed rollers juxtaposed in the right and left of the sheet conveying direction, having a non-driving roller coaxially with the driving roller, and having a pressing roller coaxial with the driven roller. When,
A non-driving roller or the pressing roller is moved in a direction in which the non-driving roller is separated from or contacted with the paper, and the pressing roller pair is separated and pressed against the paper;
6. The control unit according to any one of claims 1 to 5, wherein the control unit causes the pair of pressing rollers separated from the sheet to be pressed against the sheet when the one sheet feeding roller pair is separated from the sheet by wrinkle correction control. Or a paper conveying device. An image forming unit for forming an image on paper;
A paper transport device for transporting paper to the image forming unit;
The paper conveying device is
A pair of paper feed rollers having at least two drive rollers arranged in parallel on the left and right with respect to the paper conveyance direction and driven rollers respectively facing the drive rollers;
A paper feed motor for independently driving the drive roller;
A pressure-separation separation mechanism that moves the driving roller or the driven roller in a direction in which the driving roller or the driven roller is separated from or contacted with the paper, and separates and presses at least one of the paper feeding roller pairs with respect to the paper;
A detection sensor for detecting whether the paper is bent,
Bending correction control for controlling the sheet feeding motor to convey the sheet with the driving roller, and varying the amount of conveyance on the right and left with respect to the sheet conveying direction to correct the bending of the sheet detected by the detection sensor; A control unit that controls the crimping separation mechanism to separate one of the pair of paper feed rollers from the paper, and performs wrinkle correction control that restores the wrinkles of the paper generated by the bending correction control to the original by the restoring force of the paper. An image forming apparatus.

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