Sheet conveyance device, image forming apparatus, image forming system

Abstract

To suppress size-enlargement or to avoid preventing productivity from being improved, even though a first correction control and a second correction control are executed.SOLUTION: A sheet conveyance device comprises: a correction part capable of executing a correction control including skew correction for correcting skewing of a sheet, and width position correction for correcting a width direction position of the sheet in a width direction, while conveying the sheet; a detection part for detecting a skew amount of the sheet passing through the correction part, and the width direction position of the sheet; and a control part for controlling the correction part. The control part that executes a first correction control (S3 to S6) that is the correction control with the correction part executes a second correction control (S7 to S10) that is the correction control with the correction part, after the first correction control.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] For example, an image forming apparatus that forms an image on a sheet is configured to perform skew correction of the sheet conveyed to the image forming section in order to form an image without tilting the sheet. For image forming apparatuses that require particularly high-precision printing, there has been proposed an apparatus that performs such skew correction in two stages, a rough adjustment and a fine adjustment (see Patent Documents 1 and 2).

[0003] In the above-mentioned Patent Document 1, first, in the first skew correction section (110), the sheet is rotated by left and right skew correction rolls to perform skew correction, that is, coarse adjustment of the skew correction. Next, in the second skew correction section (120), the leading edge of the sheet is abutted against the guide section (140) to temporarily stop the sheet, and a loop is generated to perform skew correction, that is, fine adjustment of the skew correction. Then, the receiving roll (150) and the position correction roll (170) are configured to correct the width direction position of the sheet.

[0004] In addition, the system disclosed in Patent Document 2 first hits the leading edge of the sheet against the pair of clamping rollers (31) to temporarily stop the sheet, and then performs a curvature to correct the skew, i.e., performs a rough adjustment of the skew correction. Next, the CIS (36) detects the widthwise position of the sheet, and the pair of clamping rollers (31) corrects the widthwise position of the sheet. Then, the two CISs (36, 37) detect the skew and widthwise position of the sheet, and based on the detection, the clamping rollers (31) convey the sheet while correcting the skew and the positional deviation in the widthwise direction, i.e., performs a fine adjustment of the skew correction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-252918 A [Patent Document 2] JP 2018-19957 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the device disclosed in Patent Document 1, a first skew correction unit that performs rough adjustment of the skew correction of the sheet and a second skew correction unit that performs fine adjustment of the skew correction of the sheet are arranged in the conveying direction, which causes a problem of increasing the size of the device. Also, in the device disclosed in Patent Document 2, rough adjustment of the skew correction is performed by hitting the leading edge of the sheet against a clamping roller and stopping it temporarily, which requires the interval between the sheets to be widened, which causes a problem of preventing improvement of productivity.

[0007] Therefore, an object of the present invention is to provide a sheet conveying device, an image forming apparatus, and an image forming system that can execute first correction control and second correction control while preventing enlargement or hindrance to improvement of productivity. [Means for solving the problem]

[0008] One aspect of the present invention is a sheet conveying device comprising: a correction unit capable of executing correction control including skew correction for correcting skew of a sheet while conveying the sheet, and width position correction for correcting the width position of the sheet in a width direction perpendicular to the sheet conveying direction; a detection unit for detecting the amount of skew and the width position of the sheet passing through the correction unit; and a control unit for controlling the correction unit, wherein the control unit executes a first correction control, which is the correction control, by the correction unit in response to detection by the detection unit, and after the first correction control, executes a second correction control, which is the correction control, by the correction unit. Effect of the Invention

[0009] According to the present invention, while the first correction control and the second correction control are executed, it is possible to prevent an increase in size or to prevent an impediment to improvement in productivity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating a schematic configuration of an inkjet recording system according to a first embodiment. [Diagram 2] FIG. 2 is a top view showing a registration unit of the print module according to the first embodiment. [Diagram 3] FIG. 2 is a perspective view showing a registration unit of the print module according to the first embodiment. [Figure 4] 1A is a perspective view showing the registration unit before and after the registration drive roller is rotated, and FIG. [Diagram 5] 1A is a top view showing the registration unit before a sheet is conveyed, FIG. 1B is a top view showing the registration unit in a state where a skew correction of the sheet is being performed, and FIG. 1C is a top view showing the registration unit in a state where a lateral registration correction of the sheet is being performed. [Figure 6] FIG. 2 is a side cross-sectional view showing a registration unit of the print module according to the first embodiment. [Figure 7] 1A is a schematic diagram showing an example of measurement of 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 a skew correction operation. [Figure 8] 1A is a schematic diagram showing an example of a 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] 5 is a flowchart showing control of a print module according to the first embodiment. [Figure 10] FIG. 2 is a block diagram showing the configuration of a control system according to the first embodiment. [Figure 11](a) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor according to the first embodiment. (b) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor when only one image sensor is used. (c) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor when there is only one image sensor. (d) is a top view showing the arrangement of the image sensor when one image sensor detects the skew and width direction position of the sheet. [Figure 12] 13A and 13B are diagrams illustrating an example of a correction profile when performing lateral registration misalignment correction. [Figure 13] 11A and 11B are diagrams illustrating conversion of speed components and angle components of a registration drive roller when skew correction and lateral registration misalignment correction are performed simultaneously. [Figure 14] 13A and 13B are diagrams illustrating an example of a correction profile when skew correction and lateral registration deviation correction are performed simultaneously. [Figure 15] 10 is a flowchart showing control of a print module according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a case will be described in which an inkjet recording system 1 is applied as an image forming system.

[0012] [Inkjet recording system] First, the schematic configuration of the inkjet recording system 1 according to the first embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the schematic configuration of the inkjet recording system 1 according to the first embodiment. The inkjet recording system 1 as an image forming system is a sheet-fed inkjet recording system that produces a recorded matter by forming an ink image on a sheet S using two liquids, a reaction liquid and an ink. As shown in FIG. 1, the inkjet recording system 1 is composed of a feeding module 100, a print module 200, a drying module 300, a fixing module 400, a cooling module 500, an inversion module 600, and a discharge module 700. The cut-paper-like sheet S supplied from the feeding module 100 is conveyed along a conveying path, processed in each module, and discharged by a discharge module 700 as a sheet stacking device. In addition, in the inkjet recording system 1, an image is formed on a sheet by a print module 200 as an image forming device, and various processes are performed on the sheet on which the image has been formed downstream of the print module 200 in the sheet conveying direction. Therefore, the drying module 300, the fixing module 400, the cooling module 500, the reversing module 600, the discharge module 700, etc. can also be called processing devices.

[0013] The feeding module 100 has three storage chambers 110a, 110b, and 110c that store sheets S. Each of the storage chambers 110a, 110b, and 110c is configured to be able to be pulled out to the front side of the apparatus. The sheets S are fed one by one in each of the storage chambers 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 chambers 110a, 110b, and 110c is not limited to three, and the configuration may have one, two, or 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 the skew and position of the sheet corrected by a plurality of conveying roller pairs 208, 209 (see FIG. 2) as a conveying unit and the registration unit 210, and is 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 conveying 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 constitutes an image forming unit that performs recording processing (printing) on ​​the conveyed sheet S from above using a plurality of recording heads 230H (see FIG. 2) to form an image on the sheet S.

[0015] The recording heads 230H are arranged in a line along the sheet conveying direction (hereinafter, simply referred to as the "conveying 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 liquid are provided. The number of colors and the number of recording heads are not limited to five. The inkjet method can employ a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, or the like. Ink of each color is supplied to the recording head from an ink tank (not shown) through an ink tube. The sheet S printed by the recording unit 230 is conveyed while securing a clearance with the recording head by being adsorbed and conveyed by the print belt unit 220. The sheet S printed by the recording unit 230 is detected for misalignment and color density of the image formed on the sheet S by an in-line scanner (not shown) arranged downstream of the recording unit in the conveying direction. The detection result is used to correct the printed image.

[0016] The drying module 300 has a decoupling section 320, a drying belt unit 330, and a hot air blowing section 340, and reduces the liquid content contained in the ink applied to the sheet S by the recording section 230 of the print module 200, thereby improving the fixation of the sheet S and the ink. The sheet S printed by the recording section 230 of the print module 200 is transported to the decoupling section 320 arranged on the upstream side of the drying module 300 in the transport direction. In the decoupling section 320, the sheet S can be transported from above by air pressure and friction of the belt, and by weakly holding and transporting the sheet S on the belt, the sheet S on the print belt unit 220 on which the ink image is formed is prevented from shifting. The drying belt unit 330 is arranged below the belt, and the hot air blowing section 340 is arranged above the belt, facing each other with the belt in between. The sheet S transported from the decoupling section 320 is adsorbed and transported by the drying belt unit 330, and at the same time, the ink application surface is dried by receiving hot air from the hot air blowing section 340. In addition to the method of applying hot air, the drying method may be a combination of a method of irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.) and a conductive heat transfer method using contact with a heating element.

[0017] The fixing module 400 has a fixing belt unit 410. The fixing belt unit 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, and cools the high-temperature sheet S transported from the fixing module 400. The cooling sections 510 are configured to take in outside air into a cooling box with a fan, increase the pressure inside the cooling box, and cool the sheet S by blowing air from nozzles formed in a transport guide onto the sheet S. The cooling sections 510 are disposed 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, and 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 double-sided transport path used for double-sided printing. During double-sided 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 double-sided transport path of the fixing module 400, the drying module 300, the print module 200, and the feeding module 100. The double-sided transport path of the fixing module 400 is provided with a first inversion unit 420 that inverts the sheet S. Then, the sheet S is 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 sheet S conveyed from the reversing module 600 on the top tray 720 or the stacking section 750, or discharges the sheet S to an external tray (not shown) or the like.

[0021] [Print module registration unit 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 the first embodiment. Figure 3 is a perspective view showing the registration unit of the print module according to the first embodiment. Figure 6 is a side cross-sectional view showing the registration unit of the print module according to the first embodiment.

[0022] 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 order in the conveying direction X. Each pair of conveying rollers 208, 209 has 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 against the upper roller by a spring (not shown). Note that the conveying direction X referred to here refers to the direction in which the sheet S is not skewed, and does not refer to the conveying direction in the steering operation described later.

[0023] In addition, in the sheet conveying section 200A of the print module 200, a registration unit 210 is disposed downstream in the conveying direction X of the conveying roller pair 208, 209 as a correction section. That is, the registration unit 210 corrects the posture of the sheet conveyed by the conveying roller pair 208, 209. In addition, in the print module 200, a print belt unit 220 is disposed downstream in the conveying direction X of the registration unit 210. The print belt unit 220 is configured to include a print belt 25 that rotates so as to adsorb and convey the sheet, and a recording section 230 (multiple recording heads 230H) (see FIG. 2) that forms an image on the sheet conveyed by the print belt 25.

[0024] [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 conveyance direction X of the sheet (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 conveyance direction X (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, 212R are made of rubber rollers made of polyurethane, for example, and the registration driven rollers 252L, 252R are made of rollers made of EPDM, for example. The registration driven rollers 252L, 252R of the registration roller pair 240L, 240R are configured to be movable by a spacing mechanism 270 (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 from the registration drive rollers 212L, 212R.

[0025] [Drive rotation mechanism] Next, the driving and turning mechanisms 211L and 211R in the registration unit 210 will be described. As shown in Fig. 2 and Fig. 3, the registration unit 210 has driving and turning mechanisms 211L and 211R that rotate and turn the registration driving rollers 212L and 212R, respectively. Each of the driving and turning mechanisms 211L and 211R has a registration driving motor M1L as a first rotation driving motor and a registration driving motor M1R as a second rotation driving motor. Each of the driving and turning mechanisms 211L and 211R has a steering motor M2L as a first rotation driving motor and a steering motor M2R as a second rotation driving motor. Furthermore, the drive turning mechanisms 211L, 211R each have a motor gear 213L, 213R that transmits the rotation of the steering motor M2L, M2R, a drive input gear 214L, 214R, and a steering shaft 215L, 215R.

[0026] 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 registration drive motors M1L and M1R rotate the registration drive rollers 212L and 212R so that their rotation speeds can be changed independently.

[0027] The steering shafts 215L, 215R rotatably support frames 216L, 216R (see FIG. 3) which respectively support the registration drive rollers 212L, 212R and the registration drive motors M1L, M1R. That is, the registration drive rollers 212L, 212R and the registration drive motors M1L, M1R are supported rotatably (pivotably) around the steering shafts 215L, 215R whose axial directions are in a direction intersecting (orthogonal to) the conveying direction X and the width direction W orthogonal to the conveying direction X.

[0028] 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 rotating shafts. Drive input gears 214L, 214R fixed to the respective steering shafts 215L, 215R mesh with the respective motor gears 213L, 213R. This makes it possible to turn (rotate) the registration drive rollers 212L, 212R and the registration drive motors M1L, M1R around the steering shafts 215L, 215R by controlling the rotation of the steering motors M2L, M2R.

[0029] In short, the registration drive rollers 212L, 212R are configured to be rotated by the registration drive motors M1L, M1R, and turned by the steering motors M2L, M2R in a direction inclined with respect to the conveying direction X. This allows the pair of registration rollers 240L, 240R to change the conveying speed independently of each other, and also to change the conveying direction independently of each other.

[0030] In addition, a home position sensor (not shown) is disposed near each of the registration drive rollers 212L, 212R, and the home position sensor detects the home position of the registration drive rollers 212L, 212R. The home position of the registration drive rollers 212L, 212R is a position where the registration roller pair 240L, 240R faces straight (without inclination) in the conveying direction. In other words, the registration roller pair 240L, 240R is configured to be able to return to a position that is not inclined with respect to the conveying direction by the detection of the home position sensor.

[0031] [Configuration of sheet skew detection] Leading registration sensors SN2L and SN2R serving as a detection unit or a first skew amount detection unit, each of which is constituted by, for example, an optical sensor, are disposed near each nip of the pair of registration rollers 240L and 240R at the same position in the conveying direction X (i.e., aligned in the width direction W). That is, these leading registration sensors SN2L and SN2R are disposed immediately downstream of the pair of registration rollers 240L and 240R in the conveying direction X. A controller 260 (see FIG. 10) serving as a control unit described later calculates the amount of skew of the sheet S from the difference in timing at which each of the leading registration sensors SN2L and SN2R detects the leading edge of the sheet S and the conveying speed at which the sheet S is conveyed.

[0032] Similarly, downstream of the leading edge registration sensors SN2L and SN2R in the conveying direction X, leading edge registration sensors SN3L and SN3R are arranged as a detection unit or a second skew amount detection unit, which are constituted by, for example, an optical sensor. Similarly, the controller 260 (see FIG. 10) calculates the skew amount of the sheet S from the difference in timing at which the leading edge registration sensors SN3L and SN3R detect the leading edge of the sheet S and the conveying speed at which the sheet S is conveyed. That is, the leading edge registration sensors SN3L and SN3R detect the skew amount of the sheet at the second position conveyed downstream in the conveying direction X from the first position of the sheet at which the skew amount is detected by the leading edge registration sensors SN2L and SN2R. The section from the leading edge of the sheet from the leading edge registration sensors SN2L and SN2R to the leading edge registration sensors SN3L and SN3R is the first correction section CS1 in which the first correction control, which will be described later in detail, is performed. Further, the section from the leading edge of the sheet reaching the print belt 25 from the leading edge registration sensors SN3L and SN3R corresponds to a second correction section CS2 in which a second correction control, which will be described later in detail, is performed.

[0033] [Configuration for detecting sheet width direction position] Image sensors SN1L and SN1R are disposed upstream of the pair of registration rollers 240L and 240R in the conveying direction X as a detection unit or a width position detection unit. 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 a CIS sensor. These image sensors SN1L and SN1R detect the width direction position of the sheet S based on the edge positions of the left end and right end of the sheet, and the controller 260 (see FIG. 10) calculates the amount of deviation in the width direction position (so-called lateral registration deviation position) based on the detection result.

[0034] These image sensors SN1L and SN1R are arranged at positions where the widthwise position of a sheet of the smallest size that can be conveyed by the print module 200 can be detected when the leading edge of the sheet reaches the leading edge registration sensors SN3L and SN3R. In other words, the amount of deviation in the widthwise position can be detected when the amount of skew is detected when the sheet is in the first position and when the amount of skew is detected when the sheet is in the second position. This makes it possible to detect the amount of skew and the widthwise position of the sheet at the first position and the amount of skew and the widthwise position of the sheet at the second position regardless of the size of the sheet that is conveyed.

[0035] [Modification of sheet skew detection and width direction position detection] Here, modified examples of the configuration for detecting the skew of a sheet and the configuration for detecting the width direction position of a sheet will be described with reference to Figs. 11(a), 11(b), 11(c), and 11(d). Fig. 11(a) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor according to the first embodiment. Fig. 11(b) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor when only one image sensor is used. Fig. 11(c) is a top view showing the arrangement of the image sensor, the first registration sensor, and the second registration sensor when one image sensor is used. Fig. 11(d) is a top view showing the arrangement of the image sensor when one image sensor detects the skew and width direction position of a sheet.

[0036] 11(a), in the first embodiment, the leading registration sensors SN2L, SN2R are disposed downstream of the pair of registration rollers 240L, 240R in the transport direction X. The leading registration sensors SN3L, SN3R are disposed downstream of the pair of registration rollers 240L, 240R in the transport direction X. Furthermore, the image sensors SN1L, SN1R are disposed upstream of the pair of registration rollers 240L, 240R in the transport direction X.

[0037] In contrast, a modified example shown in Fig. 11(b) has only the image sensor SN1L arranged, and does not include the image sensor SN1R. That is, when the controller 260 (see Fig. 10) recognizes the size of the sheet, if the edge position of the left end of the sheet can be detected by only one image sensor SN1L, the width direction position of the sheet can be calculated. Note that it is also possible to detect the edge position of the right end of the sheet by only the image sensor SN1R, and calculate the width direction position of the sheet.

[0038] 11(c) shows a modified example in which the image sensor SN1 is arranged across the entire conveying area in which the sheet can be conveyed in the width direction, that is, the image sensor SN1 is longer in the width direction than the image sensors SN1L and SN1R. This image sensor SN1 can scan both ends of the sheet in the width direction and detect the edge positions of the left and right ends of the sheet.

[0039] 11(d) is a modified example that includes only the image sensor SN1 and does not include the leading edge registration sensors SN2L, SN2R and SN3L, SN3R. Even with this configuration, if the image sensor SN1 continuously detects the positions of both ends of the sheet in the width direction, the position and movement (skew) of the end of the sheet can be calculated. In other words, if the position of the end of the sheet detected by the image sensor SN1 is monitored for a certain period of time when the sheet reaches the first position or the second position, the amount of skew of the sheet can be calculated, and the width direction position of the sheet can also be calculated at the same time.

[0040] Although modified examples have been described using Figures 11(b), 11(c), and 11(d), the present invention is not limited to these, and the sensor may have any configuration or arrangement as long as it can detect the amount of skew and the width direction position when the sheet is in the first position, and the amount of skew and the width direction position when the sheet is in the second position.

[0041] [Print module control system configuration] Next, the configuration of a control system in the print module 200 will be described with reference to Fig. 10. Fig. 10 is a block diagram showing the configuration of the control system according to the first embodiment.

[0042] 10, controller 260 functioning as a control unit is connected to CPU 261, ROM 262, and RAM 263, and executes programs stored in ROM 262 etc. by CPU 261 using the storage area of ​​RAM 263. Controller 260 is also connected to operation unit 290 such as an operation panel not shown in FIG. 1, or an external computer via an interface not shown, and receives various input operations or displays the results.

[0043] Furthermore, the controller 260 is connected to various sensors such as the image sensors SN1L and SN1R, the first registration sensors SN2L and SN2R, and the second registration sensors SN3L and SN3R described above. The controller 260 is also connected to various motors such as the registration drive motors M1L and M1R and the steering motors M2L and M2R described above, and the conveying motor M3 that drives the conveying roller pair 208 and 209. The controller 260 controls the driving of various motors based on the detection results of these various sensors to convey the sheet, while executing correction control including both skew correction, which will be described in detail later, and lateral registration deviation correction as a width position correction.

[0044] [Skew correction operation] Next, the principle of the skew correction operation (active registration operation) will be described with reference to Figs. 4(a), 4(b), 5(a), 5(b), 5(c), 7(a), 7(b), and 7(c). Fig. 4(a) is a perspective view showing the registration unit before the registration drive roller is rotated. Fig. 4(b) is a perspective view showing the registration unit after the registration drive roller is rotated. Fig. 5(a) is a top view showing the registration unit before the sheet is conveyed. Fig. 5(b) is a top view showing the registration unit in a state where the skew correction of the sheet is being performed. Fig. 5(c) is a top view showing the registration unit in a state where the lateral registration correction of the sheet is being performed. Fig. 7(a) is a schematic diagram showing an example of the measurement of the skew amount. Fig. 7(b) is a diagram showing an example of a skew correction profile. Fig. 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.

[0045] In the registration unit 210, as described above, the registration drive rollers 212L, 212R are independently driven by the registration drive motors M1L, M1R, and the rotation speeds can be changed independently. The controller 260 determines a skew correction profile for correcting the skew of the sheet based on the skew angle of the sheet detected by the leading registration sensors SN2L, SN2R or the leading registration sensors SN3L, SN3R. The skew correction profile is a control amount for controlling the speed difference of the registration drive rollers 212L, 212R. Then, the controller 260 drives the registration drive motors M1L, M1R based on the skew correction profile to rotate the registration drive rollers 212L, 212R.

[0046] Here, the skew correction profile will be described. For example, as shown in FIG. 4(a) and FIG. 5(a), 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 speed VL and VR. Here, the sheet is conveyed, and the amount of skew of the sheet is detected by the leading registration sensors SN2L and SN2R, as shown in FIG. 4(b) and FIG. 7(a). Then, the controller 260 creates a skew correction profile as shown in FIG. 7(b) according to 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. 7(b), the skew correction profile is set by multiplying by a coefficient according to the amount of skew. The controller 260 drives the registration drive motors M1L and M1R according to the skew correction profile thus created. As a result, as shown in FIG. 7(c), a speed difference is generated between the registration drive roller 212L rotated by the registration drive motor M1L and the registration drive roller 212R rotated by the registration drive motor M1R. As a result, the sheet conveyed by the registration drive rollers 212L and 212R rotates, and the skew is corrected. Note that, although the example of the skew correction profile shown in FIG. 7(b) uses a curved drive, a triangular drive, a trapezoidal drive, or the like may also be used.

[0047] [Horizontal registration misalignment correction operation] Next, the principle of the lateral registration deviation correction operation (steering operation) will be described with reference to Figs. 8(a), 8(b), 8(c) and 12. Fig. 8(a) is a schematic diagram showing an example of a measurement of the lateral registration deviation amount. Fig. 8(b) is a diagram showing an example of a lateral registration deviation correction profile. Fig. 8(c) is a schematic diagram showing the lateral registration deviation correction operation. Fig. 12 is a diagram showing an example of a correction profile when performing lateral registration deviation correction.

[0048] 8(a) is the sheet conveying direction X, and the left-right direction in FIG. 8 is the width direction Z perpendicular to the conveying 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, the width direction center of the sheet is aligned with the width direction center (reference position) of the conveying 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 match the width direction center of the conveying path.

[0049] As described above, the registration drive rollers 212L, 212R can change the conveying direction of the rollers by the steering motors M2L, M2R via the drive input gears 214L, 214R, with the steering shafts 215L, 215R as the fulcrums. For example, when the sheet skew correction is not performed, the registration drive rollers 212L, 212R are operated so that their speeds VL, VR are the same and the conveying direction is the same. The controller 260 determines a profile as a control amount for correcting lateral registration deviation based on the position of the edge of the sheet detected by the image sensors SN1L, SN1R. That is, the controller 260 determines the profile of the steering motors M2L, M2R that change the conveying direction of the registration drive rollers 212L, 212R.

[0050] Here, the profile of the lateral registration deviation correction will be described. As shown in FIG. 8(a), the image sensors SN1L and SN1R detect the amount of lateral deviation, which is the positional deviation in the width direction. Then, the controller 260 creates a profile of the lateral registration deviation correction (speed of the Z direction component) as shown in FIG. 8(b) according to the detected amount of lateral deviation. This profile of the lateral registration deviation correction is created as a speed table so that the detected amount of lateral deviation is equal 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 the lateral registration deviation correction is set by multiplying it by a coefficient according to the amount of lateral deviation.

[0051] When the lateral registration misalignment correction and the skew correction are not performed simultaneously, it is desirable that the roller speed Vx as a component of the transport direction X is the same as the transport speed of the print belt unit 220 arranged downstream in the transport direction X. Since the roller speed Vx as a component of the transport direction X and the roller speed Vz as a component of the width direction Z are determined, the roller angle θ and the roller speed V can be calculated from the speeds Vx and Vz using trigonometric functions as shown in FIG. 8(c). By respectively determining the roller angles θL, θR and the speeds VL, VR per unit time, the operation profile of the steering motors M2L, M2R and the registration drive motors M1L, M1R can be created as shown in FIG. 12. The steering motors M2L, M2R and the registration drive motors M1L, M1R are driven according to this profile. As a result, as shown in Fig. 4(b), Fig. 5(c), and Fig. 8(c), the steering motor M2L rotates the registration drive roller 212L, and the steering motor M2R rotates the registration drive roller 212R. Therefore, the sheet is conveyed while being skewed by the registration drive rollers 212L and 212R, and the lateral registration deviation is corrected. Note that although the example of the speed correction profile shown in Fig. 8(b) shows an example using the curved drive, it is also possible to use a triangular drive, a trapezoidal drive, or the like.

[0052] [Simultaneous correction of skew and lateral misalignment] Next, simultaneous correction of skew and lateral registration misalignment will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a diagram for explaining conversion of the speed component and angle component of the registration drive roller when skew and lateral registration misalignment are performed simultaneously. Fig. 14 is a diagram showing an example of a correction profile when skew and lateral registration misalignment are performed simultaneously.

[0053] As described above, the skew of the sheet is corrected by the speed difference between the registration drive motors M1L and M1R, and the skew can be corrected. Also, the lateral registration deviation of the sheet is corrected by rotating the registration drive rollers 212L and 212R by the steering motors M2L and M2R, and the lateral registration deviation can be corrected.

[0054] In these explanations, the skew correction operation and the lateral registration deviation correction operation are described separately, but they can be performed simultaneously. As shown in FIG. 13, by combining the component of the lateral registration deviation in the width direction Z (Z correction component) and the component of the skew amount (skew angle) (θ correction component), it can be converted into the speeds VL and VR and angles (steering angles) of the registration drive rollers 212L and 212R. In short, as shown in FIG. 14, the speeds LVz and RVz of the registration drive rollers 212L and 212R in the lateral registration deviation correction profile and the speeds LVx and RVx of the registration drive rollers 212L and 212R in the skew correction profile are combined. Then, the roller angles Lθ and Rθ per unit time and the speeds VL and VR are obtained, and a simultaneous correction profile for simultaneously performing the skew correction and the lateral registration deviation correction is created. Then, the registration drive motors M1L and M1R and the steering motors M2L and M2R are driven according to the created simultaneous correction profile. This makes it possible to simultaneously perform skew correction and lateral registration deviation correction.

[0055] [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 the first 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.

[0056] For example, if the accuracy of the above-mentioned skew correction and lateral registration deviation correction is not good, the image formed on the sheet may be tilted, misaligned, or distorted. In particular, when forming images on both sides of a sheet, if the accuracy of the above-mentioned skew correction and lateral registration deviation correction is not good, there is a problem that the image on the front side of the sheet and the image on the back side of the sheet may be significantly misaligned. In this control, the accuracy of the skew correction and lateral registration deviation correction is improved by executing a first correction control and a second correction control that perform the skew correction and lateral registration deviation correction, as will be described in detail later.

[0057] (Printing begins) 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 controller 260 includes information such as the number of copies to be printed and the size of the sheet S to be printed, which are specified by the user. That is, the controller 260 determines whether to start printing in accordance with the received print job (S1).

[0058] Next, the controller 260 selects a sheet S of a size specified by the print job from, for example, one of the storages 110a, 110b, or 110c, and feeds the sheet S using the feeding module 100. Then, the controller 260 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).

[0059] (First correction control) Next, the controller 260 proceeds to a series of processes of steps S3 to S6 as a first correction control, which is a first correction control. First, when the sheet S reaches the leading edge registration sensors SN2L and SN2R, the amount of skew of the sheet S is calculated based on the detection results input from the leading edge registration sensors SN2L and SN2R (S3). That is, when the leading edge of the sheet S reaches both the leading edge registration sensors SN2L and SN2R, the detection operation of the first correction control is started. Note that the amount of skew of the sheet S referred to here is the angle of inclination with respect to the conveying direction X, more precisely, the angle of inclination with respect to the width direction Z at the leading edge of the sheet S. Specifically, as described above, the controller 260 determines the amount of skew of the sheet S based on the difference in timing at which the leading edge of the conveyed sheet S is detected by each of the two leading edge registration sensors SN2L and SN2R and the speed V (conveying speed) of the sheet S.

[0060] Next, the controller 260 calculates the width direction position of the sheet S, that is, the lateral deviation position, based on the detection results input from the image sensors SN1L and SN1R (S4). That is, the controller 260 detects how much of the image sensors SN1L and SN1R are covered by the sheet S, and calculates the amount of lateral deviation between the conveyance center and the sheet center from the positions of both ends of the sheet S in the width direction Z perpendicular to the conveyance direction X.

[0061] Next, the controller 260 creates a skew correction profile as a first control amount for correcting the skew of the sheet S based on the skew amount of the sheet S obtained as described above. Also, the controller 260 creates a lateral registration deviation correction profile as a first control amount for correcting the lateral deviation of the sheet S based on the lateral deviation amount of the sheet S obtained as described above. Then, the controller 260 creates a correction profile by combining the skew correction profile and the lateral registration deviation correction profile (S5). That is, a profile creation operation of the first correction control is executed.

[0062] Next, the controller 260 controls the registration drive motors M1L, M1R and the steering motors M2L, M2R according to the created correction profile. That is, the controller 260 executes a first correction control correction operation including skew correction and lateral registration deviation correction as a correction operation of the first correction control based on the detection results of the front registration sensors SN2L, SN2R and the detection results of the image sensors SN1L, SN1R (S6). This correction operation of the first correction control is executed so as to be completed in the first correction section CS1 (see FIG. 2 and FIG. 3). As a result, the skew and lateral deviation of the sheet are roughly adjusted.

[0063] (Second correction control) Next, the controller 260 proceeds to a series of processes of steps S7 to S10 as the second correction control, which is the second correction control. First, the amount of skew of the sheet S is calculated based on the detection results input from the leading edge registration sensors SN3L and SN3R (S7). That is, when the leading edge of the sheet S reaches both the leading edge registration sensors SN3L and SN3R, the detection operation of the second correction control is started. Similarly, the controller 260 calculates the width direction position of the sheet S, that is, the lateral deviation position, based on the detection results input from the image sensors SN1L and SN1R (S8). The amount of skew and the lateral deviation position of the sheet S obtained here can be obtained by the same calculation method as in the first correction control.

[0064] Next, the controller 260 creates a skew correction profile as a second control amount for correcting the skew of the sheet S based on the skew amount of the sheet S obtained as described above. Also, the controller 260 creates a lateral registration deviation correction profile as a second control amount for correcting the lateral deviation of the sheet S based on the lateral deviation amount of the sheet S obtained as described above. Then, the controller 260 creates a correction profile by combining the skew correction profile and the lateral registration deviation correction profile (S9). That is, a profile creation operation of the second correction control is executed.

[0065] Next, the controller 260 controls the registration drive motors M1L, M1R and the steering motors M2L, M2R according to the created correction profile. That is, the controller 260 executes a second correction control correction operation including skew correction and lateral registration deviation correction as a second correction control correction operation based on the detection results of the front registration sensors SN3L, SN3R and the detection results of the image sensors SN1L, SN1R (S10). This second correction control correction operation is executed so as to be completed in the second correction section CS2 (see FIG. 2 and FIG. 3). As a result, the skew and lateral deviation of the sheet are further finely adjusted for the sheet roughly adjusted by the first correction control.

[0066] (Image processing) Next, after the second correction control is completed, the controller 260 transfers the sheet S to the print belt 25 (see FIG. 2) (S11). Next, the controller 260 causes the recording unit 230 to form an image on the sheet S (S12). Then, the controller 260 ejects the sheet S toward the ejection module 700 (see FIG. 1) (S13), thus completing the print job and completing the image forming operation on one sheet.

[0067] In the case of double-sided printing in which images are formed on both sides (front and back) of the sheet S, the controller 260 inverts the sheet S in the inversion 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.

[0068] [Summary of the first embodiment] As described above, in this embodiment, the controller 260 executes the first correction control by the registration unit 210, and executes the second correction control by the same registration unit 210 after the first correction control. This eliminates the need to arrange two or more mechanisms for correcting skew and lateral registration deviation in the conveying direction, and can prevent the device from becoming larger. In addition, since the registration unit 210 performs skew correction (active registration operation) and lateral registration deviation correction (steering operation) while conveying the sheet, it is not necessary to stop the sheet once, and it is possible to prevent the productivity from being hindered. Therefore, in the sheet conveying section 200A of this embodiment, it is possible to prevent the device from becoming larger or the productivity from being hindered, while executing the first correction control (coarse adjustment) and the second correction control (fine adjustment).

[0069] In this embodiment, the front registration sensor SN2L, SN2R detects the amount of skew of the sheet, and the front registration sensor SN2L, SN2R is disposed downstream of the front registration sensor SN2L, SN2R in the conveying direction X and detects the amount of skew of the sheet. Furthermore, the image sensor SN1L, SN1R detects the width direction position of the sheet. This allows the first correction control to be performed according to the amount of skew of the sheet detected by the front registration sensor SN2L, SN2R and the amount of lateral deviation detected by the image sensor SN1L, SN1R. Also, the second correction control can be performed according to the amount of skew of the sheet detected by the front registration sensor SN3L, SN3R and the amount of lateral deviation detected by the image sensor SN1L, SN1R.

[0070] Furthermore, in this embodiment, by executing the second correction control before the trailing edge of the sheet passes through the registration drive rollers 212L and 212R, it is possible to perform fine adjustments to the skew correction and lateral registration misalignment correction of the sheet.

[0071] <Second embodiment> Next, a second embodiment, which is a partial modification of the first embodiment, will be described with reference to Fig. 15. Fig. 15 is a flow chart showing control of a print module according to the second embodiment. In the description of the second embodiment, the same reference numerals are used for the same parts as those in the first embodiment, and the description thereof will be omitted.

[0072] In the second embodiment, unlike the first embodiment, it is determined whether or not the skew amount or lateral deviation amount detected in the first correction control or the second correction control can be corrected by the registration unit 210. If the skew amount or lateral deviation amount cannot be corrected by the registration unit 210, the registration unit 210 performs correction using the upper limit value that can be corrected.

[0073] Specifically, as shown in Fig. 15, similarly to the first embodiment (see Fig. 9), the first correction control is started, the leading registration sensors SN2L and SN2R detect the amount of skew of the sheet (S3), and the image sensors SN1L and SN1R detect the amount of lateral deviation of the sheet (S4). Here, it is determined whether the detected amount of skew and the amount of lateral deviation can be corrected by the registration unit 210 (S14). If the amount of deviation can be corrected (YES in S14), a correction profile is created according to the detected amount of skew and the amount of lateral deviation (S5), and the first correction control (coarse adjustment) is executed (S6), similarly to the first embodiment.

[0074] On the other hand, it is determined that the detected skew amount cannot be corrected even if the registration unit 210 performs skew correction, or that the detected lateral deviation amount cannot be corrected even if the registration unit 210 performs lateral registration deviation correction (NO in S14). In other words, it is determined that at least one of the skew amount and the lateral deviation amount cannot be corrected by the first correction control. In this case, the uncorrectable amount or both are set to an upper limit value that can be corrected by the registration unit 210. Next, a correction profile is created by combining the skew correction profile created with at least one of them at the upper limit value and the lateral registration deviation correction profile (S15). Then, the registration drive motors M1L, M1R and the steering motors M2L, M2R are controlled according to the correction profile created in this way, thereby performing the first correction control (coarse adjustment) (S6).

[0075] In other words, when the first correction control is executed, it is assumed that at least one of the detected amount of skew of the sheet and the width direction position of the sheet is a value that cannot be corrected even if the registration unit 210 is controlled with the correctable upper limit control amount. In this case, the correction profile as the first control amount is set to a correction profile set with the upper limit value as the upper limit control amount.

[0076] Therefore, when a correction profile is created with the upper limit value in this way, the registration unit 210 performs the maximum skew correction or lateral misalignment correction, but the amount of skew or lateral misalignment that exceeds the maximum amount cannot be corrected. However, in a state where only the first correction control is performed, there is a possibility that the correction can be performed normally by the second correction control that is performed subsequently.

[0077] Next, the second correction control is started, the skew amount of the sheet is detected by the front registration sensors SN3L and SN3R (S7), and the lateral deviation amount of the sheet is detected by the image sensors SN1L and SN1R (S8). Here, it is determined whether the detected skew amount and lateral deviation amount can be corrected by the skew correction and lateral deviation correction by the registration unit 210 (S16). If the correction is possible (YES in S16), a correction profile is created according to the detected skew amount and lateral deviation amount (S9), as in the first embodiment, and the first correction control (coarse adjustment) is executed (S10).

[0078] On the other hand, if it is determined that at least one of the skew amount and the lateral deviation amount cannot be corrected by the second correction control (NO in S16), then the uncorrectable amount or both are set to the upper limit value correctable by the registration unit 210. Next, a correction profile is created by combining the skew correction profile created with at least one of them set to the upper limit value and the lateral deviation correction profile (S17).

[0079] In other words, when the second correction control is executed, it is assumed that at least one of the detected amount of skew of the sheet and the width direction position of the sheet is a value that cannot be corrected even if the registration unit 210 is controlled with the correctable upper limit control amount. In this case, the correction profile as the second control amount is set to a correction profile set with the upper limit value as the upper limit control amount.

[0080] In this case, since the second correction control cannot perform normal correction, the image formed on the sheet is inclined or shifted laterally, resulting in poor image formation. Therefore, the controller 260 treats the sheet as a sheet in which an error has occurred. First, in step S17, the controller 260 outputs a signal to notify the error to, for example, the operation unit 290 or an external computer (not shown), that is, executes notification of the error.

[0081] Then, the second correction control is executed by controlling the register drive motors M1L, M1R and the steering motors M2L, M2R according to the correction profile created with the upper limit value in this way, even though the error notification is executed (S10). This makes it possible to correct the skew and lateral deviation (i.e., the posture) of the sheet as much as possible, and the occurrence of jams and the like can be reduced. If a jam does not occur, for example, the sheet can be conveyed to the top tray 720 or the stacking unit 750 and discharged without the need for an emergency stop of the inkjet recording system 1. In particular, by setting the top tray 720 as an error tray for discharging sheets with errors, only sheets with defective image formation can be easily removed. By controlling in this manner, the workload of jam disposal can be reduced, and productivity can be improved without the need for an emergency stop of the inkjet recording system 1.

[0082] In the above-mentioned first correction control, when a correction profile is created with an upper limit value (see S15), it is not treated as an error, but the sheet may be treated as an error-occurring sheet as in step S17. In particular, in the second correction control, since the sheet is being conveyed toward the recording unit 230, the skew correction and lateral registration deviation correction are fine adjustments, and the upper limit of correction possible may be smaller than that in the first correction control, which is a rough adjustment. Therefore, if the skew or lateral deviation of the sheet cannot be corrected in the first correction control, it may not be possible to correct it in the second correction control either, so it may be treated as an error at the stage of the first correction control.

[0083] Other configurations, operations, and effects of the second embodiment described above are similar to those of the first embodiment, and therefore description thereof will be omitted.

[0084] [Possible alternative embodiments] In the above-described embodiment, the registration unit 210 performs skew correction upstream in the transport 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 transport 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, etc. In short, the sheet transport device that performs skew correction may be any device or may be incorporated into any device.

[0085] In the first and second embodiments, the detection unit detects the amount of skew and the width direction position of the sheet using the image sensors SN1L and SN1R, the leading edge registration sensors SN2L and SN2R, and the leading edge registration sensors SN3L and SN3R. As other configurations of the detection unit, the configurations shown in Fig. 11(b), Fig. 11(c), and Fig. 11(d) have also been described. However, the present invention is not limited to these, and any configuration may be used as long as it can detect the amount of skew and the width direction position of the sheet, such as a configuration that captures and analyzes an image.

[0086] In the first and second embodiments, the image sensors SN1L and SN1R are configured to detect the width direction position of the sheet when the leading edge of the sheet reaches the leading edge sensors SN3L and SN3R, regardless of the size of the sheet that can be conveyed. However, the present invention is not limited to this. For example, the image sensors SN1L and SN1R may be configured to execute only the first correction control for the smallest size of sheet that can be conveyed, and execute both the first and second correction controls for other sizes. In other words, the image sensors SN1L and SN1R may be configured in any way as long as the image sensors SN1L and SN1R are configured to execute both the first and second correction controls for at least one size.

[0087] In the first and second embodiments, the registration drive rollers 212L, 212R and the drive pivot mechanisms 211L, 211R for driving the rollers 212L, 212R are used to perform both skew correction and lateral registration misalignment correction. However, the present invention is not limited to this, and any configuration may be used as long as it is possible to perform both skew correction and lateral registration misalignment correction while transporting a sheet. In particular, a mechanism for performing skew correction and lateral registration misalignment correction may be provided upstream or downstream of the transport direction of the registration drive rollers 212L, 212R, and skew correction may be performed three or more times in total, or lateral registration misalignment correction may be performed three or more times in total.

[0088] The present disclosure can also be realized by a process in which a program for implementing one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more functions. [Explanation of symbols]

[0089] 1...inkjet recording system (image forming system) / 200...print module (image forming device) / 200A...sheet conveying section (sheet conveying device) / 210...registration unit (correction section) / 212L...registration drive roller (first skew correction roller) / 212R...registration drive roller (second skew correction roller) / 260...controller (control section) / 300...drying module (processing device) / 400...fixing module (processing device) / 500...cooling module (processing device) / 600...reversal 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) / S...Sheet / SN1L, SN1R...Image sensor (detection unit, width position detection unit) / SN2L, SN2R...Front registration sensor (detection unit, first skew amount detection unit) / SN3L, SN3R...Front registration sensor (detection unit, second skew amount detection unit) / X...Conveyance direction / Z...Width direction

Claims

1. a correction unit capable of executing correction control including a skew correction for correcting a skew of the sheet while conveying the sheet, and a width position correction for correcting a width direction position of the sheet in a width direction perpendicular to a conveying direction of the sheet; a detection unit that detects an amount of skew of a sheet passing through the correction unit and a width direction position of the sheet; A control unit that controls the correction unit, The control unit executes a first correction control, which is the correction control, by the correction unit in response to detection by the detection unit, and executes a second correction control, which is the correction control, by the correction unit after the first correction control. A sheet conveying device comprising:

2. The detection unit is a first skew amount detection unit that detects a skew amount of a sheet passing through the correction unit; a second skew amount detection unit disposed downstream of the first skew amount detection unit in the conveying direction and configured to detect a skew amount of the sheet passing through the correction unit; a widthwise position detection unit that detects a widthwise position of a sheet passing through the correction unit, The control unit is executes a first correction control by the correction unit according to a width direction position of the sheet detected by the width position detection unit and a skew amount of the sheet detected by the first skew amount detection unit; a second correction control is executed by the correction unit in response to the width direction position of the sheet detected by the width position detection unit and the skew amount of the sheet detected by the second skew amount detection unit; 2. The sheet transport device according to claim 1.

3. the width position detection unit is disposed at a position where the width position of the sheet can be detected when the leading edge of the sheet of the smallest size that can be conveyed reaches the second skew amount detection unit.

3. The sheet transport device according to claim 2.

4. The correction unit is a first skew correction roller that is rotatable about an axis in a direction intersecting the conveying direction and the width direction and is capable of conveying a sheet; a first rotary drive motor that rotates the first skew correction roller; a first rotation drive motor that rotates the first skew correction roller; a second skew correction roller that can be rotated around an axis in the cross direction by the first rotation drive motor and can convey a sheet; a second rotation drive motor that rotates the second skew correction roller; a second rotation drive motor that rotates the second skew correction roller, The control unit is The skew correction is performed by generating a speed difference between the first skew correction roller, which is rotationally driven by the first rotary drive motor, and the second skew correction roller, which is rotationally driven by the second rotary drive motor; the first skewing correction roller is rotated by the first turning drive motor, and the second skewing correction roller is rotated by the second turning drive motor, thereby performing the widthwise position correction.

2. The sheet transport device according to claim 1.

5. the control unit executes the second correction control after the first correction control and before the trailing edge of the sheet passes through the first skew correction roller and the second skew correction roller.

5. The sheet transport device according to claim 4.

6. The control unit is setting a first control amount of the correction unit when performing the first correction control based on the skew amount of the sheet detected by the detection unit and the width direction position of the sheet; When performing the first correction control, if at least one of the skew amount of the sheet and the width direction position of the sheet detected by the detection unit is a value that cannot be corrected even if the correction unit is controlled with an upper limit control amount that can be corrected by the correction unit, the first control amount is set to the upper limit control amount.

2. The sheet transport device according to claim 1.

7. The control unit is When the first control amount is set to the upper limit control amount, an error is notified.

7. The sheet transport device according to claim 6.

8. The control unit is setting a second control amount of the correction unit when performing the second correction control based on the skew amount of the sheet detected by the detection unit and the width direction position of the sheet; When performing the second correction control, if at least one of the skew amount of the sheet and the width direction position of the sheet detected by the detection unit is a value that cannot be corrected even if the correction unit is controlled with an upper limit control amount that can be corrected by the correction unit, the second control amount is set to the upper limit control amount.

7. The sheet transport device according to claim 6.

9. The control unit is When the second control amount is set to the upper limit control amount, an error is notified.

9. The sheet transport device according to claim 8.

10. A sheet conveying device according to any one of claims 1 to 9, an image forming unit that forms an image on the sheet transported by the sheet transport device, 1. An image forming apparatus comprising:

11. The image forming apparatus according to claim 10 ; a processing device that processes a sheet on which an image has been formed by the image forming device, 1. An image forming system comprising:

Images