Sheet conveyance device, image formation device, and image formation system

Abstract

To improve workability of replacement work of a first skew correction roller and a second skew correction roller, and improve accuracy of lateral registration correction.SOLUTION: A sheet conveyance device includes a skew correction part for correcting skew of a sheet, and an attaching / detaching part. The skew correction part includes a roller unit (210B) which has: a first skew correction roller (212L) capable of conveying a sheet; a second skew correction roller (212R) capable of conveying the sheet; a first turning mechanism (217L) for turning the first skew correction roller around a first axis (215L) extending in a crossing direction crossing a sheet conveyance direction and a width direction perpendicular to the conveyance direction; and a second turning mechanism (217R) for turning the second skew correction roller around a second axis (215R) extending in the crossing direction; and a support member (219) for supporting the first skew correction roller, the first turning mechanism, the second skew correction roller, and the second turning mechanism, and is attachable / detachable to / from the attaching / detaching part.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device that corrects skew of a sheet being conveyed, an image forming apparatus, and an image forming system. [Background technology]

[0002] For example, in an image forming apparatus that forms an image on a sheet, a sheet conveying device is provided that corrects skew of the sheet conveyed to the image forming section in order to form an image without tilting the sheet. As a sheet conveying device that performs such skew correction, one that includes multiple skew correction rollers that are arranged in parallel in the width direction of the sheet and can rotate independently has been proposed (see Patent Document 1). The device disclosed in Patent Document 1 corrects skew of the sheet by varying the rotation speeds of the skew correction rollers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-155677 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described method of correcting skew of a sheet by varying the rotation speeds of multiple skew correction rollers, it is difficult to perform so-called lateral registration correction, in which the skew correction rollers move the position of the sheet in the width direction perpendicular to the conveyance direction. This requires providing a separate mechanism, such as a pair of rollers for performing lateral registration correction, in addition to the skew correction rollers, which may result in a longer conveyance path in the sheet conveyance direction. Therefore, it is conceivable to configure the multiple skew correction rollers to be able to skew the sheet by rotating them about an axis in a direction intersecting (perpendicular to) the surface of the sheet while maintaining a parallel state, thereby enabling lateral registration correction of the sheet.

[0005] However, if the skew correction rollers become worn or stained with ink, the skew correction rollers may need to be replaced. After replacing the skew correction rollers, the orientation of the rotation direction (reference position) may shift due to variations in component tolerances, affecting the accuracy of sheet lateral registration correction. To solve this problem, it is conceivable to align the initial position of the skew correction roller in the rotation direction after replacement. However, if alignment is required while the skew correction rollers are still installed in the device, the replacement work becomes less efficient.

[0006] Therefore, an object of the present invention is to provide a sheet conveying device, an image forming device, and an image forming system that can improve the workability of replacing the first skew correction roller and the second skew correction roller and also improve the accuracy of lateral registration correction. [Means for solving the problem]

[0007] One aspect of the present invention is a sheet conveying device comprising a skew correction unit that corrects skew of a sheet, the skew correction unit including a roller unit and a detachable unit to which the roller unit can be attached and detached, the roller unit including a first skew correction roller capable of conveying a sheet, a second skew correction roller capable of conveying a sheet, a first pivoting mechanism that rotates the first skew correction roller around a first axis extending in a transverse direction that intersects the conveying direction of the sheet and a width direction perpendicular to the conveying direction, a second pivoting mechanism that rotates the second skew correction roller around a second axis extending in the transverse direction, and a support member that supports the first skew correction roller, the first pivoting mechanism, the second skew correction roller, and the second pivoting mechanism. [Effects of the Invention]

[0008] According to the present invention, the workability of replacing the first skew correction roller and the second skew correction roller can be improved, and the accuracy of lateral registration correction can also be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a schematic diagram showing the general configuration of an inkjet recording system according to an embodiment of the present invention, and FIG. 1B is a block diagram showing a control unit of a print module. [Figure 2] FIG. 4 is a top view showing a registration section of the print module according to the embodiment. [Figure 3] FIG. 2 is a perspective view showing a registration section of the print module according to the embodiment. [Figure 4] 10A is a perspective view showing the registration unit before and after the registration drive roller is rotated, and FIG. [Figure 5] 1A is a top view showing the registration unit before the sheet is conveyed, FIG. 1B is a top view showing the registration unit in a state where skew correction of the sheet is being performed, and FIG. 1C is a top view showing the registration unit in a state where lateral registration correction of the sheet is being performed. [Figure 6] FIG. 3 is a side cross-sectional view showing a registration section of the print module according to the embodiment. [Figure 7] 1A is a schematic diagram showing an example of measuring the amount of skew, FIG. 1B is a diagram showing an example of a skew correction profile, and FIG. 1C is a schematic diagram showing the skew correction operation. [Figure 8] 1A is a schematic diagram showing an example of measurement of a lateral registration deviation amount, FIG. 1B is a diagram showing an example of a lateral registration deviation correction profile, and FIG. 1C is a schematic diagram showing a lateral registration deviation correction operation. [Figure 9] 6 is a flowchart showing control of a print module according to the embodiment. [Figure 10] 10A and 10B are explanatory diagrams illustrating a case where the parallelism of the registration drive roller according to the embodiment is not good. [Figure 11] FIG. 2 is a perspective view showing a registration drive block according to the embodiment. [Figure 12] FIG. 10 is a top view showing a configuration supported by a registration driving block according to the embodiment. [Figure 13] 10 is a bottom view showing a state during adjustment in an assembly process of the registration drive roller according to the embodiment. FIG. [Figure 14] FIG. 2 is an exploded perspective view showing the registration unit before the registration drive block according to the embodiment is assembled. [Figure 15] FIG. 2 is a perspective view showing the registration unit with the registration drive block attached according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. In this embodiment, an inkjet recording system 1 is used as an image forming system.

[0011] [Inkjet recording system] First, the general configuration of an inkjet recording system 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1(a) is a schematic diagram showing the general configuration of the inkjet recording system 1 according to this embodiment. Fig. 1(b) is a block diagram showing the control unit of a print module.

[0012] The inkjet recording system 1, which serves as an image forming system, is a sheet-fed inkjet recording system that produces a recorded material by forming an ink image on a sheet S using two liquids: a reaction liquid and ink. As shown in FIG. 1(a), the inkjet recording system 1 is composed of a feeding module 100, a printing module 200, a drying module 300, a fixing module 400, a cooling module 500, an inverting module 600, and a discharging module 700. A cut sheet S supplied from the feeding module 100 is transported along a transport path, processed in each module, and discharged by the discharging module 700. In the inkjet recording system 1, an image is formed on the sheet in the printing module 200, which serves as an image forming device, and various processes are performed on the sheet on which the image has been formed downstream of the printing module 200 in the sheet transport direction. Therefore, the drying module 300, the fixing module 400, the cooling module 500, the inverting module 600, the discharging module 700, etc. can also be considered processing devices.

[0013] The feeding module 100 has three storage cabinets 110a, 110b, and 110c that store sheets S. Each of the storage cabinets 110a, 110b, and 110c is configured to be able to be pulled out toward the front of the device. The sheets S are fed one by one in each of the storage cabinets 110a, 110b, and 110c by a separation belt and a transport roller (not shown), and are transported to the print module 200. The number of storage cabinets 110a, 110b, and 110c is not limited to three, and the configuration may include one, two, four, or more.

[0014] The print module 200 includes a registration unit 210 (see FIG. 2) as a skew correction unit that performs skew correction and lateral registration correction before image formation, which will be described in detail later, a print belt unit 220, and a recording unit 230. The sheet S conveyed from the feeding module 100 has its skew and position corrected by a plurality of conveying roller pairs 208, 209 (see FIG. 2) and the registration unit 210, and is then conveyed to the print belt unit 220. The recording unit 230 is disposed at a position facing the print belt unit 220 with respect to the conveyance path. The plurality of conveying roller pairs 208, 209 and the registration unit 210 constitute a sheet conveying unit 200A as a sheet conveying device that conveys the sheet to the recording unit 230. The recording unit 230 also constitutes an image forming unit that performs recording (printing) on ​​the conveyed sheet S from above using a plurality of recording heads 230H (see FIG. 2).

[0015] The multiple recording heads 230H are arranged in the sheet transport direction. In this embodiment, in addition to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), a total of five line-type recording heads corresponding to the reaction liquids are provided. Note that the number of colors and recording heads is not limited to five. The inkjet method can be a method using a heating element, a piezoelectric element, an electrostatic element, or a MEMS element. Ink of each color is supplied to the recording head from an ink tank (not shown) via an ink tube. The sheet S printed by the recording unit 230 is adsorbed and transported by the print belt unit 220, thereby ensuring clearance with the recording head. The sheet S printed by the recording unit 230 is subjected to detection of misalignment and color density of the image formed on the sheet S by an inline scanner (not shown) located downstream of the recording unit in the sheet transport direction. The detection results are used to correct the printed image.

[0016] The drying module 300 includes a decoupling unit 320, a drying belt unit 330, and a hot air blowing unit 340. This unit reduces the liquid content of the ink applied to the sheet S by the recording unit 230 of the print module 200, thereby improving the fixation of the ink to the sheet S. The sheet S printed by the recording unit 230 of the print module 200 is transported to the decoupling unit 320, which is located upstream of the drying module 300 in the sheet transport direction. The decoupling unit 320 transports the sheet S from above using air pressure and belt friction. By loosely holding and transporting the sheet S on the belt, the sheet S on the print belt unit 220, where the ink image is formed, is prevented from shifting. The drying belt unit 330 is located below the belt, and the hot air blowing unit 340 is located above the belt, facing each other across the belt. The sheet S transported from the decoupling unit 320 is adsorbed and transported by the drying belt unit 330, and simultaneously receives hot air from the hot air blowing unit 340 to dry the ink-applied surface. The drying method may be a combination of a method of applying hot air, a method of irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.), or a conductive heat transfer method using contact with a heating element.

[0017] The fixing module 400 has a fixing belt section 410. The fixing belt section 410 has an upper belt unit and a lower belt unit, and the sheet S conveyed from the drying module 300 passes between the heated upper belt unit and the lower belt unit, thereby fixing the ink to the sheet S.

[0018] The cooling module 500 has a plurality of cooling sections 510, which cool the high-temperature sheet S transported from the fixing module 400. The cooling sections 510 are configured to cool the sheet S by drawing in outside air into a cooling box with a fan, increasing the pressure inside the cooling box, and blowing air from nozzles formed in the transport guide onto the sheet S. The cooling sections 510 are arranged both above and below the transport path, and cool the sheet S from both sides.

[0019] The cooling module 500 also has a transport path switching unit that can switch the transport path of the sheet S depending on whether the sheet S is transported to the inversion module 600 or to a duplex transport path used for duplex printing. During duplex printing, the sheet S is transported to a transport path below the cooling module 500. In this case, the sheet S is further transported from the cooling module 500 along a duplex transport path through the fixing module 400, drying module 300, print module 200, and feeding module 100. The duplex transport path of the fixing module 400 is provided with a first inversion unit 420 that inverts the sheet S. The sheet S is then transported again from the feeding module 100 to the pre-imaging registration correction unit of the print module 200, the print belt unit 220, and the recording unit 230, where it is printed.

[0020] The reversing module 600 has a second reversing section 640, and can reverse the front and back of the conveyed sheet S, and can change the front and back orientation of the discharged sheet S. The discharge module 700 has a top tray 720 and a stacking section 750, and aligns and stacks the sheets S conveyed from the reversing module 600 on the top tray 720 or the stacking section 750, or discharges them onto an external tray (not shown) or the like.

[0021] As shown in FIG. 1B, the print module 200 includes a control unit 201 as a controller that performs various controls in the inkjet recording system 1 and the print module 200. The control unit 201 includes a CPU 201a, which is an example of a processor, and a RAM 201b, a ROM 201c, and a HDD 201d as storage units. The CPU 201a, RAM 201b, ROM 201c, and HDD 201d are connected by a bus to enable communication of information with each other, and are also connected to the controllers of each module and an operation unit (not shown) via an interface (not shown) to enable communication of information. The control unit 201 is also connected to various motors and sensors of a registration unit 210 (described in detail below) via an interface (not shown). Specifically, the control unit 201 is connected to registration drive motors M1L and M1R, steering motors M2L and M2R, image sensors SN1L and SN1R, tip registration sensors SN2L and SN2R, and home position sensors SN3L and SN3R (described in detail below). The detailed control of the registration unit 210 by the control unit 201 will be described later.

[0022] [Print module registration section and surrounding structure] Next, the registration unit 210 in the print module 200 and its surrounding configuration will be described with reference to Figures 2, 3, and 6. Figure 2 is a top view showing the registration unit of the print module according to this embodiment. Figure 3 is a perspective view showing the registration unit of the print module according to this embodiment. Figure 6 is a side cross-sectional view showing the registration unit of the print module according to this embodiment.

[0023] 2 and 3, in the print module 200, in the sheet conveying section 200A (see FIG. 1), pairs of conveying rollers 208, 209 for conveying a sheet are arranged in this order in the sheet conveying direction V. Note that these pairs of conveying rollers 208, 209 have a lower roller having a roller made of, for example, EPDM and an upper roller being, for example, a rubber roller made of urethane, and the lower roller is biased toward the upper roller by a spring (not shown). Note that the sheet conveying direction V here refers to the direction when the sheet S is not skewed, and does not refer to the conveying direction in the steering operation described below.

[0024] Furthermore, in the sheet conveying section 200A of the print module 200, a registration section 210 that corrects skew of the sheet conveyed by the conveying roller pair 208, 209 is disposed downstream in the sheet conveying direction V of the conveying roller pair 208, 209. Furthermore, in the print module 200, a print belt section 220 is disposed downstream in the sheet conveying direction V of the registration section 210. The print belt section 220 is configured to include a print belt 25 that rotates so as to adsorb and convey the sheet, and a recording section 230 (plurality of recording heads 230H) (see FIG. 2) that forms an image on the sheet conveyed by the print belt 25.

[0025] (Registration roller pair) As shown in FIG. 6, the registration unit 210 includes a left registration roller pair (hereinafter simply referred to as a "registration roller pair") 240L on the left side of the conveyance center in the sheet conveyance direction V (see FIG. 2). The registration unit 210 also includes a right registration roller pair (hereinafter simply referred to as a "registration roller pair") 240R arranged in parallel on the right side of the conveyance center in the sheet conveyance direction V (see FIG. 2). The registration roller pair 240L includes a registration drive roller 212L as a first skew correction roller, and a registration driven roller 252L that is disposed opposite the registration drive roller 212L and is driven when it comes into contact with the registration drive roller 212L. Similarly, the registration roller pair 240R includes a registration drive roller 212R as a second skew correction roller, and a registration driven roller 252R that is disposed opposite the registration drive roller 212R and is driven when it comes into contact with the registration drive roller 212R. The registration drive rollers 212L and 212R are made of rubber rollers made of polyurethane, for example, and the registration driven rollers 252L and 252R are made of rollers made of EPDM, for example.

[0026] The registration driven rollers 252L, 252R of the registration roller pairs 240L, 240R are configured to be movable by a spacing mechanism (not shown) between a contact position where they are in contact with the registration drive rollers 212L, 212R and a separation position where they are separated.

[0027] (Drive turning mechanism) Next, the drive turning mechanisms 211L, 211R in the registration unit 210 will be described. As shown in Figures 2 and 3, the registration unit 210 has a drive turning mechanism 211L that rotationally drives and turns a registration drive roller 212L serving as a first skew correction roller capable of conveying a sheet. Similarly, the registration unit 210 has a drive turning mechanism 211R that rotationally drives and turns a registration drive roller 212R serving as a second skew correction roller capable of conveying a sheet.

[0028] The drive turning mechanism 211L has a registration drive motor M1L as a first rotation drive motor. The drive turning mechanism 211L also has a steering motor M2L as a first turning drive motor, and a turning transmission mechanism 217L as a first turning mechanism that turns the registration drive roller 212L by the driving rotation of the steering motor M2L. The turning transmission mechanism 217L is configured with a motor gear 213L, a drive input gear 214L, and a steering shaft 215L. That is, the turning transmission mechanism 217L turns the registration drive roller 212L around the steering shaft 215L as a first shaft that extends in an intersecting direction (perpendicular to the sheet conveyance direction and the width direction perpendicular to the sheet conveyance direction, in this embodiment).

[0029] Similarly, the drive turning mechanism 211R has a registration drive motor M1R as a second rotation drive motor. The drive turning mechanism 211R also has a steering motor M2R as a second turning drive motor, and a turning transmission mechanism 217R as a second turning mechanism that turns the registration drive roller 212R by the driving rotation of the steering motor M2R. The turning transmission mechanism 217R is configured with a motor gear 213R, a drive input gear 214R, and a steering shaft 215R. That is, the turning transmission mechanism 217R turns the registration drive roller 212R around the steering shaft 215R as a second shaft that extends in a direction intersecting (perpendicular to) the sheet conveyance direction and the width direction perpendicular to the conveyance direction (in this embodiment, perpendicular to the sheet conveyance direction).

[0030] The rotation shafts of the registration drive motors M1L and M1R are drivingly connected to the registration drive rollers 212L and 212R, respectively. In other words, the rotation of the registration drive motors M1L and M1R rotates the registration drive rollers 212L and 212R so that the rotation speeds of the registration drive rollers 212L and 212R can be changed independently.

[0031] The steering shafts 215L, 215R rotatably support frames 216L, 216R (see FIG. 3) that support the registration drive rollers 212L, 212R and registration drive motors M1L, M1R, respectively. That is, the registration drive rollers 212L, 212R and registration drive motors M1L, M1R are supported rotatably about the steering shafts 215L, 215R whose axial directions are in a direction intersecting (orthogonal to) the sheet conveying direction V and the width direction W orthogonal to the sheet conveying direction V.

[0032] Meanwhile, the steering motors M2L, M2R are arranged along an axial direction parallel to the axial direction of the steering shafts 215L, 215R, and motor gears 213L, 213R are fixed to the respective rotation shafts of the steering motors M2L, M2R. Drive input gears 214L, 214R fixed to the respective steering shafts 215L, 215R are meshed with the respective motor gears 213L, 213R. This allows the control unit 201 to drive the steering motors M2L, M2R to turn (rotate) the registration drive rollers 212L, 212R and the registration drive motors M1L, M1R around the steering shafts 215L, 215R.

[0033] In short, the registration drive rollers 212L, 212R are rotationally driven by the control unit 201 driving the registration drive motors M1L, M1R. Also, the control unit 21 drives the steering motors M2L, M2R to rotate the registration drive rollers 212L, 212R in a direction inclined with respect to the sheet conveying direction V. This allows the conveying speed and conveying direction of the registration roller pairs 240L, 240R to be changed independently of each other.

[0034] A home position sensor SN3L serving as a first reference position detector and a home position sensor SN3R serving as a second reference position detector are disposed near the registration drive rollers 212L and 212R, respectively. As will be described in detail later, the home position sensors SN3L and SN3R detect the sensor home positions (first and second reference positions) and control the registration drive rollers 212L and 212R to their home positions. The home position of the registration drive rollers 212L and 212R is the position (steering initial position) where the registration roller pair 240L and 240R faces straight (without tilt) in the conveyance direction. In other words, the detection results of the home position sensors SN3L and SN3R enable a steering initial setting operation to return the registration roller pair 240L and 240R to a position that is not tilted with respect to the conveyance direction.

[0035] (Configuration of sheet skew detection) Leading edge registration sensors SN2L and SN2R serving as skew detection units, each configured with an optical sensor, are disposed near the nip of each of the registration roller pairs 240L and 240R at the same position in the sheet conveying direction V (i.e., aligned in the width direction W). The control unit 201 (see FIG. 1(b)) calculates the amount of skew of the sheet S conveyed to the registration unit 210 from the difference in timing at which the leading edge of the sheet S is detected by each of the leading edge registration sensors SN2L and SN2R and the conveying speed at which the sheet S is conveyed. Note that, in the present embodiment, the amount of skew of the sheet S is detected by a plurality of leading edge registration sensors SN2L and SN2R. However, the present invention is not limited to this, and other methods may be used, such as detecting the skew of the sheet S by analyzing an image using an image sensor or the like that captures an image.

[0036] (Configuration for detecting the sheet's width direction position) An image sensor SN1L serving as a width position detection unit is disposed upstream of the pair of registration rollers 240L in the sheet conveying direction V. Furthermore, an image sensor SN1R serving as a width position detection unit is disposed downstream of the pair of registration rollers 240R in the sheet conveying direction V. The image sensor SN1L detects the edge position of the left end of the sheet S, and the image sensor SN1R detects the edge position of the right end of the sheet S. These image sensors SN1L and SN1R may be optical sensors such as CIS sensors. Then, the control unit 201 calculates the width direction position (so-called horizontal registration position) of the sheet S conveyed to the registration unit 210 based on the edge positions of the left and right ends.

[0037] In this embodiment, two image sensors SN1L and SN1R are used to detect both end positions of the sheet S in the width direction W, but this is not limiting and a single image sensor that is longer in the width direction W than the range through which the sheet S passes may be used. Alternatively, the position of one end of the sheet S may be detected by a single image sensor, and the position of the sheet S in the width direction may be calculated from the sheet size input to the control unit 201 (or detected by another part), for example. Furthermore, a configuration may be adopted in which the position of one end of the sheet S is detected by a single image sensor, and the movement of the sheet S in the width direction W (lateral registration) is controlled using this as a reference position.

[0038] [Skew correction operation] Next, the principle of the skew correction operation (active registration operation) will be explained using Figures 4(a), 4(b), 5(a), 5(b), 5(c), 7(a), 7(b), and 7(c). Figure 4(a) is a perspective view showing the registration unit before the registration drive roller is rotated. Figure 4(b) is a perspective view showing the registration unit after the registration drive roller is rotated. Figure 5(a) is a top view showing the registration unit before the sheet is conveyed. Figure 5(b) is a top view showing the registration unit while skew correction is being performed on the sheet. Figure 5(c) is a top view showing the registration unit while lateral registration correction is being performed on the sheet. Figure 7(a) is a schematic diagram showing an example of measuring the amount of skew. Figure 7(b) is a diagram showing an example of a skew correction profile. Figure 7(c) is a schematic diagram showing the skew correction operation. The skew correction is a correction of the angle of the sheet travel direction so that the direction is parallel to the conveyance center, which is the center in the width direction of the conveyance path along which the sheet is conveyed.

[0039] In the registration unit 210, as described above, the registration drive rollers 212L and 212R are independently driven by the registration drive motors M1L and M1R, and their rotation speeds can be changed independently. The control unit 201 (see FIG. 1(b)) determines a skew correction profile for correcting sheet skew based on the sheet skew angle detected by the leading registration sensors SN2L and SN2R. This skew correction profile is a control amount for controlling the speed difference between the registration drive rollers 212L and 212R. Then, the control unit 201 drives the registration drive motors M1L and M1R based on the skew correction profile to rotate the registration drive rollers 212L and 212R.

[0040] Here, the skew correction profile will be described. For example, as shown in FIGS. 4A and 5A, when skew correction is not performed, the registration drive rollers 212L and 212R are oriented in the conveying direction X and rotated to convey the sheet at the same speeds VL and VR. A sheet is conveyed here, and the leading registration sensors SN2L and SN2R detect the amount of skew of the sheet, as shown in FIGS. 4B and 7A. The control unit 201 then creates a skew correction profile as shown in FIG. 7B in accordance with the detected amount of skew. This skew correction profile is created as a speed table so that the amount of skew detected by the leading registration sensors SN2L and SN2R is equal to the difference between the integral value of the speed LVx of the registration drive roller 212L and the integral value of the speed RVx of the registration drive roller 212R. That is, as shown in FIG. 7B, the skew correction profile is set by multiplying it by a coefficient corresponding to the amount of skew. The control unit 201 drives the registration drive motors M1L and M1R according to the skew correction profile created in this way. As a result, as shown in FIGS. 5(b) and 7(c), a speed difference is generated between the registration drive roller 212L, which is driven to rotate by the registration drive motor M1L, and the registration drive roller 212R, which is driven to rotate by the registration drive motor M1R. As a result, the sheet conveyed by the registration drive rollers 212L and 212R rotates, and skew is corrected. Note that although the example of the skew correction profile shown in FIG. 7(b) uses curved drive, triangular drive, trapezoidal drive, etc. may also be used.

[0041] [Horizontal registration misalignment correction operation] Next, the principle of the lateral registration misalignment correction operation (steering operation) will be explained using Figures 8(a), 8(b), 8(c), and 12. Figure 8(a) is a schematic diagram showing an example of measuring the amount of lateral registration misalignment. Figure 8(b) is a diagram showing an example of a lateral registration misalignment correction profile. Figure 8(c) is a schematic diagram showing the lateral registration misalignment correction operation. Figure 12 is a diagram showing an example of a correction profile when performing lateral registration misalignment correction.

[0042] 8(a) is the sheet conveyance direction X, and the left-right direction in FIG. 8 is the width direction Z perpendicular to the conveyance direction X. Horizontal registration misalignment correction is a correction to align the width direction position of the sheet with the width direction position where the image is formed, and in many cases, it is done to align the width direction center of the sheet with the width direction center (reference position) of the conveyance path. This does not apply when the width direction position of the image formed on the sheet by the image forming unit (recording unit 230) does not align with the width direction center of the conveyance path.

[0043] As described above, the registration drive rollers 212L and 212R can change their conveyance direction around the steering shafts 215L and 215R via the drive input gears 214L and 214R by the steering motors M2L and M2R, respectively. For example, when sheet skew correction is not required, the registration drive rollers 212L and 212R are operated so that their speeds VL and VR are the same and in the same conveyance direction. The control unit 201 determines a profile as a control amount for correcting lateral registration misalignment based on the position of the sheet edge detected by the image sensors SN1L and SN1R. That is, the control unit 201 determines the profile of the steering motors M2L and M2R that changes the conveyance direction of the registration drive rollers 212L and 212R.

[0044] Here, the profile of lateral registration misalignment correction will be described. As shown in FIG. 8(a), the image sensors SN1L and SN1R detect the amount of lateral misalignment, which is the positional misalignment in the width direction. Then, the control unit 201 creates a profile of lateral registration misalignment correction (speed of the Z-direction component) as shown in FIG. 8(b) according to the detected amount of lateral misalignment. This profile of lateral registration misalignment correction is created as a speed table so that the detected amount of lateral misalignment is equivalent to the integral value of the roller speed Vz of the width direction Z component in a preset correction section. That is, as shown in FIG. 8(b), the profile of lateral registration misalignment correction is set by multiplying it by a coefficient according to the amount of lateral misalignment.

[0045] When lateral registration misalignment correction and skew correction are not performed simultaneously, it is desirable that the roller speed Vx, which is the component in the transport direction X, be the same as the transport speed of the print belt unit 220 located downstream in the transport direction X. Once the roller speed Vx, which is the component in the transport direction X, and the roller speed Vz, which is the component in the width direction Z, are determined, the roller angle θ and roller speeds VL and VR can be calculated from the speeds Vx and Vz using trigonometric functions, as shown in FIG. 8(c). By calculating the roller angles θL and θR and speeds VL and VR per unit time, respectively, an operating profile for the steering motors M2L and M2R and the registration drive motors M1L and M1R can be created. The steering motors M2L and M2R and the registration drive motors M1L and M1R are driven according to this profile. As a result, as shown in Figures 4(b), 5(c), and 8(c), the steering motor M2L rotates the registration drive roller 212L, and the steering motor M2R rotates the registration drive roller 212R. As a result, the sheet is conveyed while being skewed by the registration drive rollers 212L and 212R, and lateral registration deviation is corrected. Note that although the example of the speed correction profile shown in Figure 8(b) uses curved drive, triangular drive, trapezoidal drive, etc. may also be used.

[0046] [Print module operation] Next, the operation of the print module 200 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the control of the print module according to this embodiment. Note that, in the control of image formation shown in Fig. 9, an example in which an image is formed on one side of a sheet will be described, but this control is repeated even when images are formed on both sides of a sheet.

[0047] In the print module 200, the control unit 201 receives detection results from the left and right image sensors SN1L and SN1R and the left and right front registration sensors SN2L and SN2R. Based on these detection results, the control unit 201 controls the left and right registration drive motors M1L and M1R and the left and right steering motors M2L and M2R to convey the sheet and perform skew correction and lateral registration correction. Note that skew correction here refers to correcting the inclination with respect to the sheet conveyance direction V, and lateral registration correction refers to correcting the deviation of the sheet from a reference position in the width direction W. However, in this embodiment, the registration unit 210 basically aims to correct sheet skew, and as a result of correcting the sheet skew, it is often necessary to also correct the position in the width direction W. Therefore, both of these corrections are also referred to as skew correction in a broad sense.

[0048] 9 when it receives a print job directly from an operation unit (not shown) or from an external computer connected via a network. The print job received by the control unit 201 includes information such as the number of copies to be printed and the size of the sheets S to be printed, as specified by the user. That is, the control unit 201 determines whether to start printing in accordance with the received print job (S1).

[0049] Next, the control unit 201 selects a sheet S of a size specified by the print job from, for example, one of the storage cabinets 110a, 110b, or 110c, and feeds the sheet S using the feeding module 100. Then, the control unit 201 drives the drive motor and the like to convey the sheet S toward the registration unit 210 using the conveying roller pairs 208 and 209 (see FIG. 2), and causes the sheet S to reach the registration roller pairs 240L and 240R (S2).

[0050] Next, the control unit 201 calculates and determines the attitude (amount of skew) of the sheet S based on the detection results input from the leading edge registration sensors SN2L and SN2R (S3). Note that the attitude (amount of light blocking) of the sheet S here refers to the angle of inclination with respect to the sheet conveyance direction V, more precisely, the angle of inclination with respect to the width direction W at the leading edge of the sheet S. Specifically, as described above, the control unit 201 determines the angle of inclination of the sheet S based on the difference in timing at which the two leading edge registration sensors SN2L and SN2R detect the leading edge of the conveyed sheet S and the conveyance speed of the sheet S.

[0051] Next, the control unit 201 creates a skew correction profile (see FIG. 7(b)) of the pair of registration rollers 240L, 240R for correcting the skew of the sheet S based on the skew angle of the sheet S calculated as described above (S4). Then, the control unit 201 executes the skew correction (active operation) in accordance with the skew correction profile (S5).

[0052] Specifically, the registration drive motors M1L and M1R are driven according to the skew correction profile based on instructions from the control unit 201, thereby independently controlling the rotational speeds of the registration roller pairs 240L and 240R. For example, in the states shown in FIGS. 4A and 5A, the registration drive motors M1L and M1R are controlled so that the registration roller pair 240L rotates at a speed VL and the registration roller pair 240R rotates at a speed VR. As shown in FIG. 5B, the skew angle of the skew-transported sheet S is detected, a skew correction profile is created, and the registration drive motors M1L and M1R are independently controlled according to the skew correction profile. The speed VR of the registration roller pair 240R is then controlled to be greater than the speed VL of the registration roller pair 240L. As a result, the sheet S is rotated as indicated by the arrow ω, and the skew of the sheet S is corrected as indicated by the dashed line in the figure.

[0053] 9, the control unit 201 calculates the lateral registration position (lateral deviation amount) of the sheet S, that is, the positions of both ends of the sheet S in the width direction W, based on the detection of the left and right image sensors SN1L and SN1R (S6). Specifically, the control unit 201 detects the positions of both ends of the sheet S in the width direction W by detecting how much of the image sensors SN1L and SN1R are covered by the sheet S, and calculates the lateral deviation amount of the sheet S from the positions of both ends.

[0054] Next, the control unit 201 creates a lateral registration correction profile (see FIG. 8(b)) of the pair of registration rollers 240L, 240R for correcting the lateral registration (lateral deviation) of the sheet S based on the calculated lateral registration position of the sheet S (S7). Then, the control unit 201 executes the lateral registration correction (steering operation) in accordance with the lateral registration correction profile (S8).

[0055] Specifically, the steering motors M2L and M2R are driven according to a lateral registration correction profile based on instructions from the control unit 201, thereby independently controlling the rotation angles of the registration roller pairs 240L and 240R. In the states shown in FIGS. 4A and 5A, the steering motors M2L and M2R control the angles of the registration drive rollers 212L and 212R to their home positions based on the detection results of the home position sensors SN3L and SN3R. Therefore, the registration roller pairs 240L and 240R are controlled to face straight in the conveyance direction. Here, as shown in FIG. 5C, the lateral registration position of the sheet S conveyed with a lateral deviation is detected, a lateral registration correction profile is created, and the steering motors M2L and M2R are independently controlled and driven according to the lateral registration correction profile. Then, the registration roller pairs 240L and 240R are each rotated, and the sheet S is conveyed in the direction of the rotation by the registration roller pair 240L at a speed VL, and is also conveyed in the direction of the rotation by the registration roller pair 240R at a speed VR. As a result, the sheet S is conveyed while moving in the width direction W as shown by the arrow VB, and the lateral registration position of the sheet S is corrected to a reference position (a position that coincides with the center of conveyance) as shown by the dashed line in the figure. Note that in this lateral registration correction, in normal times when skew correction is not performed, the speeds VL and VR of the registration roller pairs 240L and 240R are controlled to be the same and the rotation angles to be the same.

[0056] 9, after the above-described lateral registration correction is completed, the control unit 201 transfers the sheet S to the print belt 25 (see FIG. 2) (S9). Then, after the sheet S is transferred to the print belt 25, the control unit 201 separates the registration driven rollers 252L, 252R from the registration drive rollers 212L, 212R by a separation mechanism (not shown) (S10).

[0057] Next, the control unit 201 causes the recording unit 230 to form an image on the sheet S (S11). After the trailing edge of the sheet S passes through the nip (registration nip) between the pair of registration rollers 240L and 240R, a separation mechanism (not shown) causes the registration driven rollers 252L and 252R to contact the registration driving rollers 212L and 212R (S12). Then, the sheet S is discharged toward the discharge module 700 (see FIG. 1) (S13), which ends the print job and the image forming operation for one sheet.

[0058] In the case of double-sided printing in which images are formed on both sides (front and back) of the sheet S, the control unit 201 reverses the sheet S in the reversing module 600 after the operation of step S13, and conveys it again toward the pair of registration rollers 240L, 240R. Then, the operations from step S2 onwards are similarly performed.

[0059] In addition, in the flowchart shown in FIG. 9, the skew correction (active operation) and the lateral registration correction (steering operation) are performed separately, but the skew correction and the lateral registration correction may be combined and both corrections may be performed simultaneously.

[0060] [Effect of registration drive roller parallelism on lateral registration correction accuracy] Here, the influence on the accuracy of lateral registration correction of a sheet when the parallelism of the registration drive rollers 212L, 212R is not good will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram that explains a case where the parallelism of the registration drive rollers according to this embodiment is not good.

[0061] As shown in FIG. 10, assume that the orientations of the registration drive rollers 212L, 212R—that is, the angles of the registration drive rollers 212L, 212R rotated around the steering shafts 215L, 215R by the steering motors M2L, M2R—are not parallel (see FIG. 2). In this state, when conveyance speeds are imparted to the sheet from the registration drive rollers 212L, 212R in the directions indicated by the arrows VL' and VR in FIG. 10, the sheet experiences a velocity Vx in the conveyance direction X. However, a difference occurs between the velocity Vz', which is the velocity in the width direction Z imparted by the registration drive roller 212L, and the velocity Vz, which is the velocity in the width direction Z imparted by the registration drive roller 212R. In particular, as shown in FIG. 10, when velocity Vz' is smaller than velocity Vz, that is, when the orientation of the registration drive roller 212L is angled more inclined toward the conveyance direction X than the orientation of the registration drive roller 212R, the difference in speeds causes deflection of the leading edge of the sheet in the conveyance direction. If the orientation of the registration drive roller 212R is angled more in the conveying direction X than the orientation of the registration drive roller 212L, the speed difference may cause the sheet to bend on the trailing edge side in the conveying direction.

[0062] When the deflected sheet is conveyed to and delivered to the print belt unit 220, the sheet is released from the nip between the registration drive rollers 212L and 212R (i.e., the pair of registration rollers 240L and 240R (see FIG. 6)), and the deflection is eliminated. When the deflection is eliminated in this manner, the sheet is displaced in the width direction Z by the amount of the deflection in the width direction Z, which means that the positional accuracy of the lateral registration correction deteriorates, which means that the accuracy of the lateral registration correction is adversely affected. Therefore, when the registration drive rollers 212L and 212R are structured to be independently rotatable about the steering shafts 215L and 215R as in this embodiment, there is a problem in that it is necessary to ensure their parallelism.

[0063] As described above, the home position sensors SN3L and SN3R detect the sensor home positions of the registration drive rollers 212L and 212R. Based on the detection by these home position sensors SN3L and SN3R, the steering motors M2L and M2R control the registration drive rollers 212L and 212R to reach their home positions. For example, if the registration drive roller 212R and / or the registration drive roller 212L is replaced, the parallelism of the registration drive rollers 212L and 212R cannot be ensured unless the home position alignment (i.e., adjustment of the reference position) is performed. However, performing the alignment while the registration drive rollers 212L and 212R are installed in the registration unit 210 requires the work to be performed in a narrow space within the housing of the print module 200, which makes the work difficult to perform. This presents a problem of poor workability when replacing the registration drive rollers 212L and 212R. Therefore, this embodiment solves this problem by adopting the configuration described below.

[0064] [Register Drive Block] Next, the registration drive block 210B, which integrates the registration drive rollers 212L, 212R, registration drive motors M1L, M1R, steering motors M2L, M2R, and rotation transmission mechanisms 217L, 217R into a single unit, will be described with reference to FIGS. 11 to 15. FIG. 11 is a perspective view showing the registration drive block according to this embodiment. FIG. 12 is a top view showing the configuration supported by the registration drive block according to this embodiment. FIG. 13 is a bottom view showing the state during adjustment in the assembly process of the registration drive roller according to this embodiment. FIG. 14 is an exploded perspective view showing the registration unit before the registration drive block according to this embodiment is installed. FIG. 15 is a perspective view showing the registration unit with the registration drive block according to this embodiment installed.

[0065] (Configuration of the register drive block) As shown in Figures 11 and 12, the registration drive block 210B serving as a roller unit includes a support stay 219 serving as a support member. The support stay 219 generally includes a stay body 219a and a side plate 219b. The stay body 219a is configured as a plate-shaped frame for the registration drive block 210B, and the side plate 219b is attached to the side of the stay body 219a. The registration drive rollers 212L, 212R, registration drive motors M1L, M1R, steering motors M2L, M2R, and rotation transmission mechanisms 217L, 217R are attached to the stay body 219a so as to be supported by the registration drive rollers 212L, 212R. The rotation transmission mechanisms 217L, 217R include motor gears 213L, 213R, drive input gears 214L, 214R, and steering shafts 215L, 215R. In addition, home position sensors SN3L and SN3R are supported on the side plates 219b. Plate-like protrusions 219c, 219c are formed on both sides of the stay body 219a in the width direction perpendicular to the sheet conveyance direction. Each of the protrusions 219c is formed with a through-hole 219d that fits with a protrusion pin 218a (see FIG. 14) formed on a frame 210F of the registration unit 210 of the print module 200, which will be described later. Furthermore, each of the protrusions 219c is formed with a screw hole 219e, 219e for fastening to the frame 210F with a screw.

[0066] Therefore, the registration drive rollers 212L, 212R, registration drive motors M1L, M1R, steering motors M2L, M2R, turning transmission mechanisms 217L, 217R, and home position sensors SN3L, SN3R are integrated by being supported by the support stay 219. In short, these components are supported by the support stay 219 to form an integrated unit called the registration drive block 210B.

[0067] (Adjusting the initial position of the registration drive roller in the rotation direction of the registration drive block) Next, we will explain how to adjust the initial position of the rotation direction (steering angle) of the registration drive rollers 212L, 212R in the registration drive block 210B. For example, as shown in Figure 12, the registration drive rollers 212L, 212R, registration drive motors M1L, M1R, steering motors M2L, M2R, rotation transmission mechanisms 217L, 217R, and home position sensors SN3L, SN3R are assembled to the support stay 219. In other words, the registration drive block 210B is assembled. Then, the assembled registration drive block 210B is set in a measurement tool (measuring instrument) not shown.

[0068] Next, an external controller (not shown) is connected to the steering motors M2L and M2R and the home position sensors SN3L and SN3R. The external controller then controls and drives the steering motor M2L so that the registration drive roller 212L is at a sensor home position, which is the first reference position of the home position sensor SN3L. Similarly, the external controller controls and drives the steering motor M2R so that the registration drive roller 212R is at a sensor home position, which is the second reference position of the home position sensor SN3R.

[0069] In this state, as shown in FIG. 13, external sensors 901 and 901 are set, and measurement of the angle (parallelism) of the registration drive rollers 212L and 212R is started by the external sensors 901 and 901. Then, an external controller (not shown) drives the steering motors M2L and M2R and controls them so that the angles of the registration drive rollers 212L and 212R detected by the external sensors 901 and 901 are parallel. In other words, an external controller (not shown) drives the steering motors M2L and M2R and controls them to a home position (steering initial position) where the registration drive rollers 212L and 212R are aligned straight in the conveyance direction. The number of drive steps by which the steering motors M2L and M2R are driven at this time, i.e., the angle θiL as the first pivot angle by which the registration drive roller 212L is moved and the angle θiR as the second pivot angle by which the registration drive roller 212R is moved, are recorded on the barcode label. This barcode label is then attached to the register driving block 210B, for example, and managed as a unique value of the register driving block 210B.

[0070] When assembling the registration drive block 210B to the registration unit 210 of the print module 200, for example, for part replacement, the angles θiL and θiR written on the barcode label are input, for example, to the HDD 201d of the control unit 201. The control unit 201 may perform an initial position setting operation to position the registration drive rollers 212L and 212R to their home positions, for example, when powering on the print module 200 or starting sheet transport. When performing this initial position setting operation, the control unit 201 adds the angles θiL and θiR to the sensor home position and rotates the registration drive rollers 212L and 212R using the steering motors M2L and M2R. As a result, even if there is variation in the parallelism of the registration drive rollers 212L and 212R in the registration drive block 210B due to component tolerances, this variation is corrected when the registration drive rollers 212L and 212R are positioned to their home positions during the initial position setting operation. Therefore, in a state where the registration unit 210 performs skew correction (lateral registration correction) on the sheet, the parallelism of the registration drive rollers 212L and 212R can be maintained with high precision.

[0071] In this embodiment, the angles θiL, θiR are recorded on barcode labels and input to the HDD 201d, etc., but the number of drive steps of the steering motors M2L, M2R may be recorded on barcode labels and input to the HDD 201d, etc. In other words, it is sufficient that the difference in position (angle) between the sensor home positions of the home position sensors SN3L, SN3R and the home positions of the registration drive rollers 212L, 212R is recorded in the control unit 201. Furthermore, any sensor that can measure parallelism may be used as the external sensor 901, and it is conceivable to use, for example, a laser displacement meter, a contact-type distance measuring device, etc.

[0072] (Replacing the cash register drive block) Next, we will explain the replacement work of the registration drive block 210B in the print module 200. For example, when the registration drive rollers 212L, 212R need to be replaced because they are worn or contaminated with ink, the replacement work involves removing the old registration drive block 210B from the registration unit 210 and installing a new registration drive block 210B.

[0073] As shown in Fig. 14, the registration unit 210 has a frame 210F that supports each component, and a guide 210G that contacts the underside of a sheet and guides it is supported on the frame 210F. Registration driven rollers 252L and 252R that constitute the pair of registration rollers 240L and 240R are arranged below the guide 210G (see Fig. 6). Also, a removable base 218 that constitutes the removable unit 210S to which the registration drive block 210B can be attached and detached is arranged above the guide 210G. The removable base 218 has a plurality of protruding pins 218a that fit into through holes 219d formed in the support stay 219, and a plurality of screw holes 218b into which screws (not shown) that are arranged to pass through the plurality of screw holes 219e are threadedly engaged. Furthermore, the removable base 218 is formed with a through-hole 218H that allows the registration drive rollers 212L and 212R to come into contact with the registration driven rollers 252L and 252R.

[0074] When removing (detaching) the old register driving block 210B, a plurality of screws (four in this embodiment) not shown are removed from the screw holes 218b and 219e, respectively, and the old register driving block 210B is removed upward from the detachable portion 210S of the detachable base 218. Then, as shown in Fig. 14, when attaching (mounting) the new register driving block 210B, the protruding pin 218a is fitted into the through hole 219d, and a plurality of screws (not shown) are screwed into the screw holes 218b and 219e, respectively. As a result, the support stay 219 of the register driving block 210B is attached to the detachable portion 210S of the detachable base 218, as shown in Fig. 15.

[0075] [Summary of this embodiment] As described above, the registration unit 210 is configured to include a registration drive block 210B that has support stays 219 that support the registration drive rollers 212L, 212R and the rotation transmission mechanisms 217L, 217R and is detachable from the detachable unit 210S. This eliminates the need for alignment work after replacing the registration drive rollers 212L, 212R by adjusting the initial positions of the registration drive rollers 212L, 212R in the rotation direction in the registration drive block 210B. This improves the workability of replacing the registration drive rollers 212L, 212R and also improves the accuracy of lateral registration correction.

[0076] Furthermore, by having the support stay 219 support the home position sensors SN3L and SN3R, the relative positional relationship of the sensor home positions of the home position sensors SN3L and SN3R can be maintained by the support stay 219.

[0077] The control unit 201 also acquires, from a barcode label or the like, the angle θiL at which the rotation direction of the registration drive roller 212L becomes the home position relative to the sensor home position detected by the home position sensor SN3L. Similarly, the control unit 201 acquires, from a barcode label or the like, the angle θiR at which the rotation direction of the registration drive roller 212R becomes the home position relative to the sensor home position detected by the home position sensor SN3R. Then, an initial position setting operation is performed to drive the registration drive roller 212L by the angle θiL from the sensor home position and to drive the registration drive roller 212R by the angle θiR from the sensor home position. In other words, before attaching the registration drive block 210B to the registration unit 210, the angles θiL and θiR are acquired by the external sensor 901. This makes it possible to accurately control the position of the registration drive rollers 212L and 212R to the home positions by performing the initial position setting operation after replacement. Therefore, alignment work for the registration drive rollers 212L, 212R after replacement is not required, workability of the replacement work can be improved, and the registration drive rollers 212L, 212R can be accurately controlled to the home position, thereby improving the accuracy of lateral registration correction.

[0078] [Possibilities for other embodiments] In the above-described embodiment, the external sensor 901 detects the rotational direction deviation of the registration drive rollers 212L and 212R due to component tolerances in the registration drive block 210B before replacement as angles θiL and θiR. In this case, the registration drive rollers 212L and 212R are set to their home positions by performing an initial position setting operation after replacement and correcting the deviations using the angles θiL and θiR. However, this is not limiting. The registration drive block 210B before replacement may measure the rotational direction deviation of the registration drive rollers 212L and 212R due to component tolerances and perform alignment work to mechanically eliminate the deviation. In this case, alignment work is required for the registration drive block 210B before replacement. However, by performing the alignment work before replacement, the alignment work during the replacement work is not required, thereby improving the workability of the replacement work. Furthermore, since there is no need to perform alignment work in a narrow space after installation in the registration unit 210, the workability of the replacement work is improved.

[0079] Furthermore, in this embodiment, the registration driving block 210B is attached to the frame 210F via the detachable base 218, but this is not limiting, and the registration driving block 210B may be attached directly to the frame 210F.

[0080] Furthermore, in this embodiment, the support stay 219 of the registration drive block 210B is detachably attached to the detachable base 218. However, the present invention is not limited to this, and may be configured such that, for example, parts of the registration drive motors M1L, M1R or the turning transmission mechanisms 217L, 217R are directly fastened to the detachable base 218 or the frame 210F.

[0081] Furthermore, in this embodiment, the registration drive motors M1L, M1R are supported by the support stay 219 of the registration drive block 210B. However, this is not limiting, and the registration drive motors M1L, M1R may be located in a location separate from the registration drive block 210B. In other words, when the registration drive block 210B is attached to the detachable section 210S, the registration drive motors M1L, M1R may be drivingly connected to the registration drive rollers 212L, 212R.

[0082] Furthermore, in this embodiment, the steering motors M2L, M2R are supported on the support stay 219 of the registration drive block 210B. However, this is not limiting, and the steering motors M2L, M2R may be located in a location separate from the registration drive block 210B. In other words, when the registration drive block 210B is attached to the detachable section 210S, the steering motors M2L, M2R may be drivingly connected to the turning transmission mechanisms 217L, 217R.

[0083] Also, in this embodiment, the registration drive block 210B is configured to be detachably attached to the detachable portion 210S formed on the detachable base 218. However, the present invention is not limited to this, and the detachable portion 210S may be formed on, for example, the guide 210G. Furthermore, if there is a unit in which the registration driven rollers 252L, 252R are arranged, the detachable portion 210S may be formed on that unit. In other words, it is sufficient that the detachable portion 210S is positioned relative to the frame 210F and is detachably attached to the registration unit 210.

[0084] In the present embodiment, the registration unit 210 performs skew correction upstream in the sheet conveyance direction of the recording unit 230 as an image forming unit. However, the present invention is not limited to this, and skew correction may be performed upstream in the sheet conveyance direction of, for example, an image reading unit that reads an image on a sheet, a punching unit that punches holes in a sheet, a folding unit that folds a sheet, or the like. In short, the sheet conveying device that performs skew correction may be any device or may be incorporated into any device. [Explanation of symbols]

[0085] 1...inkjet recording system (image forming system) / 200...print module (image forming apparatus) / 200A...sheet conveying section (sheet conveying device) / 201...control section / 210...registration section (skew correction section) / 210B...registration drive block (roller unit) / 210S...detachable section / 212L...registration drive roller (first skew correction roller) / 212R...registration drive roller (second skew correction roller) / 215L...steering shaft (first shaft) / 215R...steering shaft (second shaft) / 217L...turning transmission mechanism (first turning mechanism) / 217R...turning transmission mechanism (second turning mechanism) / 219...support stay (support member) / 230H...recording head (image forming section) / 300...drying module (processing device) / 400...fixing module (processing device) processing device) / 500... cooling module (processing device) / 600... inversion module (processing device) / 700... discharge module (processing device) / M1L... registration drive motor (first rotation drive motor) / M1R... registration drive motor (second rotation drive motor) / M2L... steering motor (first swivel drive motor) / M2R... steering motor (second swivel drive motor) / SN1L... image sensor (width position detection unit) / SN1R... image sensor (width position detection unit) / SN2L... leading registration sensor (skew detection unit) / SN2R... leading registration sensor (skew detection unit) / SN3L... home position sensor (first reference position detection unit) / SN3R... home position sensor (second reference position detection unit) / θiL... angle (first swivel angle) / θiR... angle (second swivel angle)

Claims

1. a skew correction unit for correcting skew of the sheet; The skew correction unit A roller unit; a detachable portion to which the roller unit can be attached, The roller unit includes: a first skew correction roller capable of conveying a sheet; a second skew correction roller capable of conveying a sheet; a first pivoting mechanism that pivots the first skew correction roller about a first axis extending in a direction intersecting a sheet conveying direction and a width direction perpendicular to the sheet conveying direction; a second pivoting mechanism that pivots the second skew correction roller about a second axis extending in the intersecting direction; a support member that supports the first skew correction roller, the first turning mechanism, the second skew correction roller, and the second turning mechanism, A sheet conveying device characterized by:

2. The detachable portion is capable of attaching and detaching the support member.

2. The sheet transport device according to claim 1.

3. The roller unit includes: a first reference position detection unit that detects a first reference position in a rotation direction of the first skew correction roller; a second reference position detection unit that detects a second reference position in a rotation direction of the second skew correction roller, the support member supports the first reference position detection unit and the second reference position detection unit.

2. The sheet transport device according to claim 1.

4. a control unit that acquires information about a first turning angle at which a turning direction of the first skew correction roller becomes an initial position relative to the first reference position detected by the first reference position detection unit, acquires information about a second turning angle at which a turning direction of the second skew correction roller becomes an initial position relative to the second reference position detected by the second reference position detection unit, and performs an initial position setting operation to drive the first skew correction roller at the first turning angle from the first reference position and drive the second skew correction roller at the second turning angle from the second reference position.

4. The sheet transport device according to claim 3.

5. The roller unit includes: a first turning drive motor that drives the first turning mechanism to turn the first skew correction roller; a second turning drive motor that drives the second turning mechanism to turn the second skew correction roller, the support member supports the first swing drive motor and the second swing drive motor.

2. The sheet transport device according to claim 1.

6. a width position detection unit that detects a position in the width direction of the sheet conveyed to the skew correction unit; a control unit that corrects the position of the sheet in the width direction by rotating the first skew correction roller with the first turning drive motor and rotating the second skew correction roller with the second turning drive motor based on a detection result of the width position detection unit; 6. The sheet transport device according to claim 5.

7. The roller unit includes: a first rotation drive motor that rotates and drives the first skew correction roller; a second rotation drive motor that rotates and drives the second skew correction roller, the support member supports the first rotary drive motor and the second rotary drive motor; 2. The sheet transport device according to claim 1.

8. a skew detection unit that detects the amount of skew of the sheet conveyed to the skew correction unit; a control unit that corrects skew of the sheet by generating a speed difference between the first skew correction roller that is rotationally driven by the first rotary drive motor and the second skew correction roller that is rotationally driven by the second rotary drive motor based on the detection result of the skew detection unit; 8. The sheet transport device according to claim 7, wherein the sheet transport device is a sheet conveying device.

9. A sheet conveying device according to any one of claims 1 to 8; an image forming unit that forms an image on the sheet conveyed by the sheet conveying device, An image forming apparatus characterized by:

10. The image forming apparatus according to claim 9 ; a processing device that processes the sheet on which the image is formed by the image forming device, An image forming system comprising:

Images