Sheet conveying device and image forming device

Abstract

The present invention provides a sheet conveying device and an image forming device. The sheet conveying device includes a sheet detection unit and a position adjustment mechanism. The position adjustment mechanism is arranged on the downstream side of the sheet conveying direction relative to the sheet detection unit on the sheet conveying path, and includes an adjustment roller pair, which corrects the skew and position deviation of the sheet while conveying the sheet. The sheet conveying path includes: a first conveying roller pair, which is arranged on the upstream side of the sheet conveying direction relative to the position adjustment mechanism; and a bending portion, which is arranged between the adjustment roller pair and the first conveying roller pair, and is bent in an S shape in a manner of alternately protruding from different positions in the sheet conveying direction toward the front and back directions of the sheet. The adjustment roller pair conveys the sheet in a state of clamping the sheet together with the first conveying roller pair.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device and an image forming device. Background Art

[0002] An image forming apparatus is known that performs the following corrections: skew correction for correcting the inclination of a sheet conveyed along a sheet conveying path relative to the sheet conveying direction; and positional deviation correction for correcting the positional deviation of the sheet in a sheet width direction orthogonal to the sheet conveying direction.

[0003] For example, a conventional image forming apparatus includes: a clamping roller that conveys a sheet along a predetermined conveying path; an upstream detection unit and a downstream detection unit that detect the positional deviation of the sheet upstream and downstream of the clamping roller, respectively; and a roller moving mechanism that moves the clamping roller to correct the positional deviation of the sheet. The control unit of the image forming apparatus controls the roller moving mechanism based on the upstream positional deviation and the downstream positional deviation of the sheet. Thus, the positional deviation correction accuracy of the sheet can be improved.

[0004] When a sheet conveyed along a sheet conveying passage is adjusted to an appropriate position on the sheet conveying passage, the sheet may be stretched / bent or twisted between two conveying roller pairs that pass through the sheet and clamp and hold the sheet at the upstream and downstream portions in the sheet conveying direction, respectively. In order to eliminate the stretching / bending or twisting, a bend needs to be formed on the sheet between the two conveying roller pairs arranged along the sheet conveying direction. Therefore, it is preferable to provide a curved portion that protrudes toward the front and back sides of the sheet in the sheet conveying passage.

[0005] However, in the prior art, no curved portion is provided in the conveying passage between the clamping roller and the conveying roller on the upstream side thereof. As a result, when adjusting the position of the sheet, there is a problem that the sheet cannot be sufficiently bent and the stretching / bending and twisting of the sheet cannot be eliminated. As a result, a large load may be applied to the sheet, causing damage to the sheet. In addition, when only one curved portion is provided in the conveying passage, the stretching / bending and twisting of the sheet may not be sufficiently eliminated. Summary of the invention

[0006] In view of the above problems, an object of the present invention is to provide a sheet conveying device and an image forming apparatus that can adjust the position of a sheet conveyed along a sheet conveying path to an appropriate position on the sheet conveying path without applying a load to the sheet.

[0007] In order to solve the above-mentioned problem, the present invention provides a sheet conveying device, which includes: a sheet detecting unit arranged on a sheet conveying path, for detecting an inclination of the conveyed sheet relative to the sheet conveying direction and an amount of positional deviation of the sheet in a sheet width direction orthogonal to the sheet conveying direction; and a position adjusting mechanism, which is arranged on the sheet conveying path on a downstream side of the sheet conveying direction relative to the sheet detecting unit, for conveying the sheet while performing skew correction and positional deviation correction based on the detection result of the sheet detecting unit, wherein the skew correction is to correct the inclination of the sheet relative to the sheet conveying direction, and the positional deviation correction is to correct the position of the sheet in a sheet width direction orthogonal to the sheet conveying direction. The positional deviation in the width direction of the sheet is corrected, and the position adjustment mechanism comprises: an adjustment roller pair, the adjustment roller pair clamping and conveying the sheet; a skew correction motor to tilt the rotating axis of the adjustment roller pair relative to the sheet conveying direction; and a position deviation correction motor to move the adjustment roller pair along the width direction of the sheet, and the sheet conveying path comprises: a first conveying roller pair, arranged on the upstream side of the sheet conveying direction relative to the position adjustment mechanism; and a bending portion, arranged between the adjustment roller pair and the first conveying roller pair, and bent in an S shape toward the front and back directions of the sheet, and the adjustment roller pair conveys the sheet in a state of clamping the sheet together with the first conveying roller pair.

[0008] According to the present invention, when the position adjustment mechanism is operated to correct the skew and the position deviation, the adjustment roller pair conveys the sheet in a state of clamping the sheet together with the first conveying roller pair. As a result, the sheet clamped by the adjustment roller pair and the first conveying roller pair is bent in an S shape when viewed from the width direction of the sheet. The sheet is bent and flexed in a manner protruding in two directions, so that stretching / bending and twisting can be fully eliminated. Therefore, when the sheet conveyed along the sheet conveying path is adjusted to an appropriate position on the sheet conveying path, the position adjustment can be performed without applying a load to the sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic cross-sectional front view showing the structure of an image forming apparatus according to one embodiment of the present invention.

[0010] Figure 2 It is shown Figure 1 A block diagram showing a simplified structure of an image forming apparatus.

[0011] Figure 3 yes Figure 1 A side view of a position adjustment mechanism of an image forming apparatus.

[0012] Figure 4 yes Figure 3Bottom view of the position adjustment mechanism.

[0013] Figure 5 It is shown Figure 3 A schematic side view of the first stage of the transition of skew correction and position shift correction performed by the position adjustment mechanism.

[0014] Figure 6 It is shown Figure 3 A schematic side view of the second stage of the transition of the skew correction and position shift correction performed by the position adjustment mechanism.

[0015] Figure 7 It is shown Figure 3 A schematic side view of the third stage of the transition of the skew correction and position shift correction performed by the position adjustment mechanism.

[0016] Figure 8 It is shown Figure 3 A schematic side view of the fourth stage of the transition of the skew correction and position shift correction performed by the position adjustment mechanism.

[0017] Fig. 9 yes Figure 1 A schematic front view of a curved portion of a sheet conveying path of an image forming apparatus.

[0018] Fig.10 yes Fig. 9 1 is a schematic front view of a curved portion of a sheet conveying path, and is a view showing a state when the position adjustment mechanism is operated.

[0019] Fig.11 It is a schematic front view of a curved portion of a sheet conveying path according to a modified example. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present invention is not limited to the following contents.

[0021] Figure 1 It is a schematic cross-sectional front view showing the structure of the image forming apparatus 1 according to the embodiment. Figure 2 It is shown Figure 1 1 is a block diagram showing a simplified structure of an image forming apparatus 1. An example of the image forming apparatus 1 of the present embodiment is a tandem color printer that transfers a toner image to a sheet S using an intermediate transfer belt 31. The image forming apparatus 1 may be, for example, a so-called multifunction peripheral having functions such as printing, scanning (image reading), and fax transmission.

[0022] The image forming apparatus 1 is Figure 1 as well as Figure 2As shown, the image forming apparatus includes a sheet supply unit 3 , a sheet conveying device 4 , an exposure unit 5 , an image forming unit 20 , a transfer unit 30 , a fixing unit 6 , a sheet discharge unit 7 , a control unit 8 , and a storage unit 9 .

[0023] The sheet feeding section 3 stores a plurality of sheets S, and separates and feeds the sheets S one by one during printing. The sheet conveying device 4 feeds the sheets S fed from the sheet feeding section 3 toward the secondary transfer section 33 and the fixing section 6, and further includes a sheet conveying path 41, along which the sheets S after fixing are discharged from the sheet discharge port 4a to the sheet discharge section 7. The exposure section 5 irradiates the image forming section 20 with laser light controlled based on image data.

[0024] The image forming unit 20 is arranged below the intermediate transfer belt 31. The image forming unit 20 includes an image forming unit 20Y for yellow, an image forming unit 20M for magenta, an image forming unit 20C for cyan, and an image forming unit 20B for black. The basic structure of the above four image forming units 20 is the same. Therefore, in the following description, the identification marks "Y", "M", "C", and "B" representing each color are omitted except for the case where it is particularly required.

[0025] The image forming unit 20 includes a photosensitive drum (image carrier) 21, and the photosensitive drum 21 is supported so as to be rotatable in a predetermined direction ( Figure 1 The photosensitive drum 21 is arranged with its rotation axis horizontally. The image forming unit 20 also includes a charging unit, a developing unit, and a drum cleaning unit arranged around the photosensitive drum 21 along its rotation direction. In addition, a primary transfer unit 32 is arranged between the developing unit and the drum cleaning unit.

[0026] The photosensitive drum 21 has a photosensitive layer on the outer peripheral surface. The charging unit charges the outer peripheral surface of the photosensitive drum 21 at a predetermined potential. The exposure unit 5 exposes the outer peripheral surface of the photosensitive drum 21 charged by the charging unit, and forms an electrostatic latent image of the original image on the outer peripheral surface of the photosensitive drum 21. The developing unit causes the toner to adhere to the electrostatic latent image and develop it to form a toner image. The four image forming units 20 each form a toner image of a different color. The drum cleaning unit cleans the photosensitive drum 21 by removing the toner remaining on the outer peripheral surface of the intermediate transfer belt 31 after the toner image is transferred to the outer peripheral surface of the intermediate transfer belt 31.

[0027] The transfer unit 30 includes an intermediate transfer belt 31, primary transfer units 32Y, 32M, 32C, and 32B, a secondary transfer unit 33, and a belt cleaning unit 34. The intermediate transfer belt 31 is disposed above the four image forming units 20. The intermediate transfer belt 31 is an intermediate transfer body and is supported so as to be able to move in a predetermined direction ( Figure 1The intermediate transfer belt 31 rotates counterclockwise (in the middle) so that the toner images formed by the four image forming units 20 are overlapped one after another and transferred once. The four image forming units 20 are arranged in a row from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 31 in a so-called tandem arrangement.

[0028] The primary transfer sections 32Y, 32M, 32C, and 32B are arranged above the image forming sections 20Y, 20M, 20C, and 20B of the respective colors with the intermediate transfer belt 31 interposed therebetween. The secondary transfer section 33 is arranged on the upstream side of the fixing section 6 in the sheet conveying direction of the sheet conveying device 4, and on the downstream side of the image forming sections 20Y, 20M, 20C, and 20B of the respective colors in the rotation direction of the intermediate transfer belt 31 of the transfer section 30. The belt cleaning section 34 is arranged on the upstream side of the image forming sections 20Y, 20M, 20C, and 20B of the respective colors in the rotation direction of the intermediate transfer belt 31, for example.

[0029] The toner images are primarily transferred to the outer peripheral surface of the intermediate transfer belt 31 by the primary transfer sections 32Y, 32M, 32C, and 32B of the respective colors. Then, as the intermediate transfer belt 31 rotates, the toner images of the four image forming sections 20 are continuously transferred to the intermediate transfer belt 31 in an overlapping manner at a predetermined timing, thereby forming a color toner image in which the toner images of the four colors of yellow, magenta, cyan, and black are overlapped on the outer peripheral surface of the intermediate transfer belt 31.

[0030] The color toner image on the outer peripheral surface of the intermediate transfer belt 31 is transferred to the sheet S synchronously conveyed by the sheet conveying device 4 at the secondary transfer nip portion formed in the secondary transfer section 33. That is, the transfer section 30 transfers the toner image formed on the surface of the four photosensitive drums 21 to the sheet S via the intermediate transfer belt 31. The belt cleaning section 34 cleans the outer peripheral surface of the intermediate transfer belt 31 by removing the toner remaining on the outer peripheral surface of the intermediate transfer belt 31 after the secondary transfer.

[0031] The fixing unit 6 is disposed in the sheet conveying device 4 downstream of the secondary transfer unit 33 in the sheet conveying direction and above the secondary transfer unit 33. The fixing unit 6 heats and presses the sheet S to which the toner image has been transferred, thereby fixing the toner image on the sheet S.

[0032] The sheet discharge section 7 is disposed above the transfer section 30 . The sheet S on which the toner image has been fixed and printing has been completed is conveyed to the sheet discharge section 7 .

[0033] The control unit 8 includes a CPU, an image processing unit, and other electronic circuits and electronic components (none of which are shown in the figure). The CPU controls the operation of each component provided in the image forming apparatus 1 based on the control program / data stored in the storage unit 9, and performs processing related to the functions of the image forming apparatus 1. The sheet feeding unit 3, the sheet conveying device 4, the exposure unit 5, the image forming unit 20, the transfer unit 30, and the fixing unit 6 each receive instructions from the control unit 8, and perform printing on the sheet S in a linked manner.

[0034] The storage unit 9 is composed of, for example, a combination of a nonvolatile storage device such as a program ROM (Read Only Memory) or a data ROM, and a volatile storage device such as a RAM (Random Access Memory).

[0035] The sheet conveying device 4 includes a sheet detection unit 10 and a position adjustment mechanism 50 in addition to a sheet conveying path 41. The sheet conveying path 41 extends substantially in the vertical direction from the upstream side of the sheet conveying direction of the sheet detection unit 10 to the downstream side of the sheet conveying direction of the position adjustment mechanism 50. The sheet conveying path 41 includes a plurality of conveying roller pairs, including a first conveying roller pair 42 and a second conveying roller pair 43 disposed on the upstream side of the position adjustment mechanism 50 in the sheet conveying direction.

[0036] The sheet detection section 10 is disposed on the sheet conveying path 41 and is located on the upstream side (at the top of the sheet conveying path) of the secondary transfer section 33 of the transfer section 30 in the sheet conveying direction. Figure 1 The sheet detection unit 10 includes, for example, a contact image sensor (CIS) 101 and a light source unit 102 (see FIG. Figure 2 The contact image sensor 101 extends over the sheet width direction ( ) which is orthogonal to the sheet conveying direction of the sheet conveying path 41. Figure 1 The entire area (in the depth direction of the paper).

[0037] The contact image sensor 101 detects the sheet conveying direction (in the sheet conveying direction) of the sheet S based on the light intensity difference between the portion where the light from the light source unit 102 is incident and the portion where the light is shielded by the sheet S. Figure 1 The vertical direction), and the width direction of the sheet body ( Figure 1 Thus, the sheet detection unit 10 detects the inclination of the sheet S conveyed on the sheet conveying path 41 with respect to the sheet conveying direction Dc and the positional deviation of the sheet S in the sheet width direction Dw.

[0038] The position adjustment mechanism 50 is arranged on the upstream side (in the sheet conveying direction) of the secondary transfer section 33 of the transfer section 30 on the sheet conveying path 41. Figure 1 The lower side of the secondary transfer unit 33 in the sheet conveying direction) and the downstream side of the sheet detection unit 10 in the sheet conveying direction ( Figure 1 The position adjustment mechanism 50 has the functions of conveying the sheet S and correcting the conveying position of the sheet S. Specifically, the position adjustment mechanism 50 conveys the sheet S while performing skew correction and position shift correction based on the detection result of the sheet detection unit 10. The skew correction refers to correcting the inclination of the sheet S relative to the sheet conveying direction, and the position shift correction refers to correcting the position shift of the sheet S in the sheet width direction. The control unit 8 controls the position adjustment mechanism 50.

[0039] Next, in addition to combining Figure 1 as well as Figure 2 In addition, Figure 3 as well as Figure 4 The configuration of the position adjustment mechanism 50 will be described. Figure 3 yes Figure 1 FIG. 1 is a side view of a position adjustment mechanism 50 of the image forming apparatus 1 . Figure 4 yes Figure 3 A bottom view of the position adjustment mechanism 50. Figure 3 The following drawings show the sheet conveying direction Dc and the sheet width direction Dw.

[0040] Position adjustment mechanism 50 Figure 3 as well as Figure 4 The device shown in the figure includes an adjustment roller pair 51 , a roller holder 52 , a carriage 53 , a roller drive motor 54 , a skew correction motor 55 , a position deviation correction motor 56 , and a reference position detection unit 57 .

[0041] The adjustment roller pair 51 is arranged in a plurality of pairs in the sheet width direction Dw, for example, four pairs in the present embodiment. The adjustment roller pair 51 includes a driving roller 511 and a driven roller 512. The driving roller 511 is fixed to a rotating shaft 513 and is driven to rotate by a roller driving motor 54 via the rotating shaft 513. The driven roller 512 rotates as the driving roller 511 rotates because its circumferential surface contacts the circumferential surface of the driving roller 511. The adjustment roller pair 51 clamps and conveys the sheet S.

[0042] The roller holder 52 rotatably supports the rotation shaft 513 of the driving roller 511 and the rotation shaft 514 of the driven roller 512. Figure 3 , Figure 4A swing support shaft 521 is provided on the left end side and the support end of the sheet S. The swing support shaft 521 is rotatable relative to the conveying surface of the sheet S in the normal direction ( Figure 3 The paper depth direction, Figure 4 The roller bracket 52 can make the other end side ( Figure 3 , Figure 4 The right end side, the swing end) swings in the sheet conveying direction Dc relative to the carriage 53 about the swing support shaft 521.

[0043] The carriage 53 supports the roller holder 52. The carriage 53 is supported by the front side frame 1a and the back side frame 1b of the image forming apparatus 1 and is movable in the sheet width direction Dw.

[0044] The roller drive motor 54 is provided on the supporting end side of the roller holder 52 in the sheet width direction Dw ( Figure 3 , Figure 4 The roller drive motor 54 is connected to the rotating shaft 513 of the driving roller 511 via a plurality of gears. The roller drive motor 54 rotates and stops the rotating shaft 513. That is, the roller drive motor 54 rotates and stops the driving roller 511.

[0045] The skew correction motor 55 is connected to the roller holder 52 at the swing end side ( 100 ) in the sheet width direction Dw via a plurality of gears. Figure 3 , Figure 4 The rack 522 is provided on the right end side of the roller bracket 52. The skew correction motor 55 causes the swing end side of the roller bracket 52 in the sheet width direction Dw to swing in the sheet conveying direction Dc around the swing support shaft 521. That is, the skew correction motor 55 can change the inclination of the roller bracket 52 with respect to the sheet conveying direction Dc. In other words, the skew correction motor 55 can cause the rotating shafts 513 and 514 of the adjustment roller pair 51 to tilt with respect to the sheet conveying direction Dc.

[0046] The position deviation correction motor 56 is connected to a rack tooth (not shown) formed at one end edge 53a of the carriage 53 in the sheet conveying direction Dc via a gear 56a. The position deviation correction motor 56 moves the carriage 53 in the sheet width direction Dw. That is, the position deviation correction motor 56 can move the adjustment roller pair 51 in the sheet width direction Dw.

[0047] Further, as the roller drive motor 54 , the skew correction motor 55 , and the position deviation correction motor 56 , for example, a stepping motor whose rotation direction and rotation amount (rotation angle) can be controlled with high accuracy by pulse control is used.

[0048] The reference position detection unit 57 is provided on the front frame 1a of the image forming apparatus 1. The reference position detection unit 57 includes, for example, a light sensor disposed on the front frame 1a and having a light emitting unit and a light receiving unit, and a light shielding plate disposed on the roller bracket 52 and entering and exiting the optical path of the light sensor. The reference position detection unit 57 detects the reference position of the roller bracket 52. The reference position of the roller bracket 52 is a position at which the inclination with respect to the sheet conveying direction Dc is 0 (at right angles with respect to the sheet conveying direction Dc) and is the center position in the sheet width direction Dw on the sheet conveying path 41.

[0049] The position adjustment mechanism 50 of the above-mentioned structure can perform skew correction for correcting the inclination of the sheet S with respect to the sheet conveying direction Dc and position deviation correction for correcting the position deviation of the sheet S in the sheet width direction Dw by the adjustment roller pair 51 while conveying the sheet S. In the skew correction of the sheet S, the position adjustment mechanism 50 causes the roller holder 52 (adjustment roller pair 51) to incline with respect to the sheet conveying direction Dc by the skew correction motor 55. In the position deviation correction of the sheet S, the position adjustment mechanism 50 causes the roller holder 52 (adjustment roller pair 51) to move along the sheet width direction Dw by the position deviation correction motor 56.

[0050] Next, an operation example of skew correction and positional deviation correction of the sheet S performed by the position adjustment mechanism 50 will be described. Figures 5 to 8 1 is a schematic side view showing the transition from the first stage to the fourth stage of the skew correction and positional deviation correction performed by the position adjustment mechanism 50. Figures 5 to 8 In the figure, the second transport roller pair 43 is omitted.

[0051] like Figure 5 As shown in FIG. 1 , the roller holder 52 of the position adjustment mechanism 50 is located at the reference position Pm0 before the sheet S conveyed toward the secondary transfer portion 33 of the transfer portion 30 reaches the position of the sheet detection portion 10. That is, the roller holder 52 is located at a position where the inclination with respect to the sheet conveying direction Dc is 0 (at right angles with respect to the sheet conveying direction Dc) and the roller holder 52 is located at the center of the sheet conveying path 41 in the sheet width direction Dw.

[0052] For example, Figure 5 As shown, when the sheet S is inclined at an angle α relative to a reference position Ps0 (the inclination relative to the sheet conveying direction Dc is 0 and is located at the center of the sheet width direction Dw on the sheet conveying path 41) and a positional deviation of a distance β occurs, the above-mentioned inclination and positional deviation of the sheet S are detected by the sheet detection unit 10.

[0053] like Figure 6As shown in FIG. 1 , when the sheet S reaches the position of the sheet detection unit 10, the sheet detection unit 10 detects the inclination amount of the sheet S conveyed toward the secondary transfer unit 33 of the transfer unit 30 with respect to the sheet conveying direction Dc and the positional deviation amount of the sheet S in the sheet width direction Dw using the contact image sensor 101. Detection information of the sheet S detected by the sheet detection unit 10 is sent to the control unit 8.

[0054] The control unit 8 controls the position adjustment mechanism 50 based on the detection information of the sheet S detected by the sheet detection unit 10 . Specifically, the control unit 8 derives a control signal for the position adjustment mechanism 50 based on the detection information of the sheet S detected by the sheet detection unit 10 and transmits the control signal to the position adjustment mechanism 50 .

[0055] The control unit 8 moves the roller bracket 52. Specifically, in the position adjustment mechanism 50, the skew correction motor 55 is controlled to tilt the roller bracket 52 at an angle α relative to the sheet conveying direction Dc, and the position deviation correction motor 56 is controlled to move the roller bracket 52 by a distance β along the sheet width direction Dw. The skew correction motor 55 and the position deviation correction motor 56 are, for example, stepping motors, and the rotation direction and rotation amount (rotation angle) are controlled by pulse control.

[0056] like Figure 7 As shown in FIG. 1 , when the sheet S reaches the position of the position adjustment mechanism 50, the control unit 8 performs skew correction and position deviation correction. In addition, at this time, the sheet conveying path 41 holds and conveys the sheet S through the first conveying roller pair 42 and the adjustment roller pair 51 disposed on the upstream side of the adjustment roller pair 51 in the sheet conveying direction.

[0057] Thus, the position adjustment mechanism 50 is as follows. Figure 8 As shown, the roller holder 52 is returned to the reference position Pm0 while the sheet S is conveyed by the adjustment roller pair 51. As a result, the area of ​​the sheet S held by the adjustment roller pair 51 moves to the reference position Ps0. Then, the control unit 8 conveys the sheet S adjusted to the appropriate position on the sheet conveying path 41 by the position adjustment mechanism 50 to the secondary transfer unit 33 of the transfer unit 30. As a result, the entire sheet S moves to the reference position Ps0.

[0058] Next, combine Fig. 9 as well as Fig.10 The configuration of the sheet conveyance path 41 on the upstream side of the position adjustment mechanism 50 in the sheet conveyance direction will be described. Fig. 9 yes Figure 1 FIG. 4 is a schematic front view of a curved portion 44 of a sheet conveying path 41 of the image forming apparatus 1 . Fig.10 yes Fig. 91 is a schematic front view of the curved portion 44 of the sheet conveying path 41 , and is a diagram showing a state when the position adjustment mechanism 50 is operated.

[0059] The sheet conveyance path 41 includes a first conveyance roller pair 42 , a bending portion 44 , a second conveyance roller pair 43 , and an approaching or separating mechanism 45 on the upstream side of the position adjustment mechanism 50 in the sheet conveyance direction Dc.

[0060] The first conveying roller pair 42 is arranged on the upstream side of the sheet conveying direction Dc with respect to the position adjustment mechanism 50. The first conveying roller pair 42 is composed of, for example, a driving roller 421 and a driven roller 422. The driving roller 421 is rotated by a motor (not shown). The driven roller 422 rotates as the driving roller 421 rotates by contacting the circumference of the driving roller 421. The first conveying roller pair 42 holds the sheet S in the conveying nip formed by the contact between the driving roller 421 and the driven roller 422 and conveys the sheet S.

[0061] The curved portion 44 is disposed between the adjustment roller pair 51 and the first conveying roller pair 42. The curved portion 44 is curved in an S-shape toward the front and back surfaces of the sheet S. Specifically, the curved portion 44 is curved in an S-shape so as to alternately protrude from different positions in the sheet conveying direction Dc toward the front and back surfaces of the sheet S. More specifically, the downstream portion of the curved portion 44 in the sheet conveying direction Dc is formed at a position corresponding to the length of the curved portion 44. Fig. 9 The curved portion 44 is curved in a manner protruding to the left, and the upstream portion of the curved portion 44 in the sheet conveying direction Dc is formed in a manner protruding to the left. Fig. 9 That is, the curved portion 44 has a curved portion 44a substantially in the center of the sheet conveying direction Dc. Fig. 9 As shown in FIG. 1 , a region of the sheet conveyance path 41 on the upstream side of the adjustment roller pair 51 in the sheet conveyance direction Dc is configured in an S shape when viewed in the sheet width direction.

[0062] The second conveying roller pair 43 is arranged at the curved portion 44a of the curved portion 44. The second conveying roller pair 43 is composed of, for example, a driving roller 431 and a driven roller 432. The driving roller 431 is rotated by a motor (not shown). The driven roller 432 is in contact with the circumferential surface of the driving roller 431 through its circumferential surface, and thus rotates with the rotation of the driving roller 431. The second conveying roller pair 43 holds the sheet S in the conveying nip formed by the contact between the driving roller 431 and the driven roller 432, and conveys the sheet S.

[0063] The approaching or separating mechanism 45 is arranged adjacent to the driven roller 432 of the second conveying roller pair 43. The approaching or separating mechanism 45 includes, for example, a biasing member 451 and a cam 452. The biasing member 451 is composed of, for example, a compression spring, and is connected between the shaft portion 432x of the driven roller 432 and the frame member of the main body 2. The biasing member 451 presses the shaft portion 432x in a direction in which the driven roller 432 approaches the driving roller 431.

[0064] The cam 452 contacts, for example, the shaft portion 432x of the driven roller 432. The cam 452 rotates against the pressing force of the force applying member 451, and can move the shaft portion 432x in a direction to separate the driven roller 432 from the driving roller 431. Thus, the approaching or separating mechanism 45 approaches or separates the driving roller 431 and the driven roller 432 constituting the second conveying roller pair 43. In other words, the approaching or separating mechanism 45 moves one of the conveying rollers, that is, the driven roller 432, of the driving roller 431 and the driven roller 432 constituting the second conveying roller pair 43, toward the front and back sides of the sheet S. The approaching or separating mechanism 45 is controlled by the control unit 8.

[0065] When the sheet S is conveyed without the skew correction or positional deviation correction of the sheet S by the position adjustment mechanism 50, the approaching or separating mechanism 45 brings the driving roller 431 and the driven roller 432 into contact (see Fig. 9 ). In addition, when the skew correction or positional deviation correction of the sheet S is performed by the position adjustment mechanism 50, the approaching or separating mechanism 45 separates the driving roller 431 and the driven roller 432 (see Fig.10 ).

[0066] According to the above-mentioned structure, when the position adjustment mechanism 50 is operated to correct the skew and the position deviation, the adjustment roller pair 51 conveys the sheet S in a state of clamping the sheet S together with the first conveying roller pair 42. As a result, the sheet S clamped by the adjustment roller pair 51 and the first conveying roller pair 42 is bent in an S shape when viewed from the width direction of the sheet. The sheet S is bent and flexed in a manner protruding in two directions, so that stretching / bending and twisting can be fully eliminated. Therefore, when the sheet S conveyed along the sheet conveying path 41 is adjusted to an appropriate position on the sheet conveying path 41, the position adjustment can be performed without applying a load to the sheet S.

[0067] In addition, the sheet conveying device 4 includes the second conveying roller pair 43 and the approaching or separating mechanism 45 of the above-mentioned structure. According to this structure, even in the sheet conveying path 41 corresponding to the conveying of small-sized sheets S, the drive roller 431 and the driven roller 432 can be separated by the approaching or separating mechanism 45 to perform skew correction and positional deviation correction. Therefore, in the sheet conveying device 4 having various structures, when the sheet S is adjusted to an appropriate position on the sheet conveying path 41, the position adjustment can be performed without applying a load to the sheet S.

[0068] Fig.11 1 is a schematic front view of a curved portion 44 of a sheet conveying path 41 according to a modified example. The sheet conveying path 41 according to the modified example includes an approaching or separating mechanism 46. The approaching or separating mechanism 46 is disposed adjacent to the driven roller 432 of the second conveying roller pair 43.

[0069] The approaching or separating mechanism 46 moves at least one of the driving roller 431 and the driven roller 432 of the second conveying roller pair 43 in the sheet conveying direction Dc to separate them. In the present embodiment, the approaching or separating mechanism 46 moves the driven roller 432 to the downstream side in the sheet conveying direction Dc to separate the driving roller 431 and the driven roller 432. The separated driving roller 431 and the driven roller 432 contact the sheet S at different positions in the sheet conveying direction Dc in the curved portion 44.

[0070] In addition, the driving roller 431 may be moved along the sheet conveying direction Dc, or the driving roller 431 and the driven roller 432 may be moved in different directions in the sheet conveying direction Dc. For example, the driving roller 431 may be moved to the downstream side of the sheet conveying direction Dc, and the driven roller 432 may be moved to the upstream side of the sheet conveying direction Dc.

[0071] According to the configuration of the modified example, the driven roller 432 moved to the downstream side in the sheet conveying direction Dc can enhance the effect of bending the sheet S in the curved portion 44 so as to protrude in the front and back directions. Therefore, when the sheet S is adjusted to an appropriate position on the sheet conveying path 41, the effect of eliminating stretching / bending and twisting can be enhanced.

[0072] In addition, the image forming apparatus 1 includes the sheet conveying device 4 of the above-described structure for conveying the sheet S to the transfer unit 30. According to this structure, the image forming apparatus 1 can adjust the position of the sheet S without applying a load to the sheet S when adjusting the sheet S to an appropriate position on the sheet conveying path 41 before transferring the image to the sheet S. Therefore, the optimal transfer of the image to the sheet S can be achieved.

[0073] As mentioned above, although embodiment of this invention was described, the scope of this invention is not limited to this, Various changes can be implemented in the range which does not deviate from the subject matter of this invention.

[0074] For example, in the above-mentioned embodiment, the image forming apparatus 1 is a so-called tandem color printing image forming apparatus that sequentially overlaps images of multiple colors, but the image forming apparatus is not limited to such a model. The image forming apparatus may also be a non-tandem color printing image forming apparatus or a black-and-white printing image forming apparatus.

[0075] The sheet conveying device 4 may be mounted on an image forming apparatus using an inkjet recording method, or on a sheet post-processing apparatus that performs post-processing on sheets after image formation.

Claims

1. A sheet conveying device, characterized in that: include: a sheet detecting unit disposed on the sheet conveying path and detecting an inclination amount of the conveyed sheet relative to the sheet conveying direction and a positional deviation amount of the sheet in a sheet width direction orthogonal to the sheet conveying direction; and The position adjustment mechanism is arranged on the downstream side of the sheet conveying direction relative to the sheet detecting unit on the sheet conveying path, and performs skew correction and position shift correction based on the detection result of the sheet detecting unit while conveying the sheet, wherein the skew correction is to correct the inclination of the sheet with respect to the sheet conveying direction, and the position shift correction is to correct the position shift of the sheet in the sheet width direction. The position adjustment mechanism comprises: an adjusting roller pair, the adjusting roller pair clamping and conveying the sheet; a skew correction motor that tilts the rotation axis of the adjustment roller pair relative to the sheet conveying direction; and A position deviation correction motor moves the adjustment roller pair along the width direction of the sheet. The sheet conveying passage comprises: a first conveying roller pair disposed on an upstream side of the position adjustment mechanism in the sheet conveying direction; and The bending portion is arranged between the adjustment roller pair and the first conveying roller pair and is bent in an S shape toward the front and back surfaces of the sheet. The adjustment roller pair conveys the sheet while sandwiching the sheet together with the first conveying roller pair. The sheet conveying passage comprises: a second pair of conveying rollers disposed at a bending portion of the curved portion; and The approaching or separating mechanism brings the two conveying rollers constituting the second conveying roller pair into contact with or away from each other. The approaching or separating mechanism brings the two conveying rollers into contact when the sheet is conveyed without the skew correction or the positional deviation correction of the sheet by the position adjusting mechanism, and separates the two conveying rollers when the skew correction or the positional deviation correction of the sheet is performed by the position adjusting mechanism. The approaching or separating mechanism moves at least one of the two conveying rollers in the sheet conveying direction to separate the two conveying rollers. The two separated conveying rollers come into contact with the sheet at different positions in the curved portion in the conveying direction of the sheet.

2. The sheet conveying device according to claim 1, wherein: The two conveying rollers include a driving roller and a driven roller driven by the driving roller. The approaching or separating mechanism moves the driven roller in the sheet conveying direction.

3. An image forming device, characterized in that: include: An image forming unit that forms an image; A transfer unit, transferring the image to a sheet; as well as The sheet conveying device according to claim 1, wherein the sheet is conveyed to the transfer section.

Images