Sheet conveying device

Abstract

The invention provides a sheet conveying device capable of correcting skew of a sheet with high precision with a small structure. A sheet conveyance device (12) is provided with a skew detection device (17) that detects the amount of skew of a conveyed sheet (S) with respect to a conveyance direction (F), and a skew correction device (15) that corrects the skew of the sheet, the skew correction device being provided with guide members (30c, 32c, 28) that support the sheet in the width direction, and correcting the skew of the sheet on the basis of the amount of skew of the sheet. The guide member is displaced so that a region in the width direction of the sheet supported by the guide member is rotated about an axis parallel to the conveyance direction.

Description

Technical Field

[0001] The present invention relates to a sheet material conveying device. Background Art

[0002] An image forming device that forms an image on a single sheet of recording medium (hereinafter referred to as paper) separates the paper sheets one by one and feeds them to an image forming unit, where the image is formed on the paper sheets. The transport mechanism that transports the paper sheets in the image forming device includes a paper feeder that transports the paper sheets before image formation to the image forming unit. When an image formation start instruction is input to the image forming device, the paper feeder separates the paper sheets one by one using a separation and transport unit, and sequentially transports each sheet to the image forming unit.

[0003] When conveying paper to the image forming unit using a paper feeder, if the paper is conveyed skewed relative to the normal conveyance direction, this can lead to problems such as reduced image quality (such as image positional deviation or image overflow) on the paper formed by the image forming unit and poor paper conveyance. As a countermeasure, a skew correction conveyance unit is provided between the separation conveyance unit and the image forming unit in the paper feeder. The skew correction conveyance unit corrects the skew of the paper conveyed from the separation conveyance unit according to the timing of image formation before feeding the paper to the image forming unit.

[0004] For example, the skew-correcting conveying unit disclosed in Patent Document 1 includes a registration roller that can select between a rotating state and a stopped state. Skew is corrected by bringing the leading edge of the paper into contact with the stopped registration roller, causing the paper to slack. The registration roller is rotated at a predetermined timing, and the skew-corrected paper is conveyed to the image forming unit.

[0005] The registration rollers repeat a cycle of rotation and stopping to correct the skew of the paper. Therefore, as the number of sheets conveyed per unit time increases, physical factors such as the effects of rotational inertia make it difficult to meet the required performance requirements. For example, if the registration rollers repeatedly rotate and stop at very short intervals, they may rotate and stop at times that deviate from the actual rotation and stop instructions, resulting in reduced positional accuracy of the image formed on the paper conveyed from the registration rollers to the image forming unit. For this reason, a skew correction conveyor that repeats a cycle of rotation and stopping of the registration rollers has a limit to the speed at which it can maintain conveying accuracy, which is the primary factor that limits the increase in the paper conveying speed (the number of sheets formed per unit time) of the skew correction conveyor.

[0006] In order to eliminate the situation where the skew correction conveying unit becomes a bottleneck in terms of the conveying speed of the paper, a technology for achieving high-speed operation of the paper feeding device has been proposed. For example, in the invention described in Patent Document 2, the structure is such that the conveying roller pair serving as the positioning roller pair can change the angle along the conveying direction (thrust direction) of the paper. In addition, during the conveying process of the paper, the amount of skew is detected by a sensor, and the angle of the conveying roller pair is changed until the roller gap line of the conveying roller pair becomes parallel to the top of the paper. When the paper is clamped by the conveying roller pair, the angle of the conveying roller pair is returned to a right angle relative to the conveying direction. The skew of the paper is corrected by the action of such a conveying roller pair. An invention similar to Patent Document 2 is disclosed in Patent Document 3.

[0007] In the invention described in Patent Document 4, the skew of the paper is corrected by setting two conveying rollers arranged parallel to the conveying direction to different rotational speeds according to the detected skew amount of the paper.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 10-35910

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 6-234441

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 4-153149

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 4-144859 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] As described in Patent Document 2, in a structure that corrects paper skew by varying the angle of a pair of transport rollers along the paper's transport direction, a large space in the transport direction is required to accommodate the skew-correcting transport unit, resulting in a long paper transport path. Consequently, the image forming apparatus becomes larger in the transport direction.

[0016] As described in Patent Document 4, in a structure in which a speed difference is created between two conveyor rollers to correct the skew of the paper, the speed difference between the two conveyor rollers may cause the paper to deform, and there is a problem in that it is difficult to properly control the movement of the conveyor rollers while taking into account the rigidity of the paper, the friction coefficient of the conveyor rollers, etc.

[0017] This problem exists not only in image forming devices that form images on paper, but also in various sheet conveying devices that convey sheet-like objects (hereinafter referred to as sheets). Specifically, conventional sheet conveying devices have difficulty improving conveying speed when correcting skew in the conveying direction of the sheet without increasing the size of the conveying device and causing sheet conveying problems.

[0018] An object of the present invention is to provide a sheet conveying device capable of correcting the skew of a sheet with high accuracy using a compact structure.

[0019] Solutions for solving problems

[0020] One technical solution is a sheet conveying device comprising: a skew detection device for detecting the amount of skew of the conveyed sheet relative to the conveying direction; and a skew correction device for correcting the skew of the sheet, characterized in that the skew correction device comprises a guide member for supporting the sheet along the width direction, and displaces the guide member in accordance with the amount of skew of the sheet detected by the skew detection device so that the area in the width direction of the sheet supported by the guide member rotates around an axis parallel to the conveying direction.

[0021] Effects of the Invention

[0022] According to the above-described technical solution, it is possible to obtain a sheet conveying device capable of correcting the skew of a sheet with high precision in a compact structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a plan view of the image forming apparatus according to the embodiment.

[0024] Figure 2 It is a side view of the image forming apparatus.

[0025] Figure 3 This is a diagram showing a control system of the image forming apparatus.

[0026] Figure 4 This is a perspective view of a skew correction unit included in a sheet conveying device of an image forming apparatus.

[0027] Figure 5 This is a perspective view of the skew correction unit.

[0028] Figure 6 This is a perspective view of a swing unit constituting a skew correction section.

[0029] Figure 7 It is a side view of the skew correction unit in the reference state.

[0030] Figure 8This is a front view of the skew correction unit in the reference state.

[0031] Figure 9 It is a side view showing a state in which the swing unit of the skew correction section is rotated in the first direction.

[0032] Figure 10 This is a front view showing a state in which the swing unit of the skew correction section is rotated in the first direction.

[0033] Figure 11 It is a side view showing a state in which the swing unit of the skew correction section is rotated in the second direction.

[0034] Figure 12 This is a front view showing a state in which the swing unit of the skew correction section is rotated in the second direction.

[0035] Figure 13 This is a diagram illustrating skew correction of a sheet by the skew correction section.

[0036] Figure 14 It is a perspective view showing a skew correction unit according to a different embodiment.

[0037] Figure 15 It is a side view showing a reference state of a skew correction unit according to a different embodiment.

[0038] Figure 16 It is a side view showing a state in which the swing unit is rotated in the first direction by a skew correcting portion according to a different embodiment.

[0039] Figure 17 It is a side view showing a state in which the swing unit is rotated in the second direction by a skew correcting portion according to a different embodiment.

[0040] Description of Reference Numerals

[0041] 1. Image forming device; 10. Image forming unit; 11. Sheet conveying device; 14. Separating conveying unit; 15. Skew correction unit (skew correction unit); 17. Skew detection sensor (skew detection unit); 20. Conveyor roller; 21. Conveyor roller; 22. Swing unit; 23. Side wall; 24. Connecting unit; 24a. Rotating shaft; 25. Rotating support unit; 26. First support shaft; 27. Second support shaft; 28. Guide roller (guide member); 30. Lower guide; 30b. Cylinder; 30c. Guide arm (guide member, first guide member); 30d. Guide surface; 31. Support shaft; 32 , upper guide; 32b, cylindrical portion; 32c, guide arm (guide member, second guide member); 32d, long hole; 32e, guide surface; 35, motor unit; 40, control portion; 50, skew correction portion; 51, lower guide unit; 52, upper guide unit; 53, first belt member (guide member); 54, second belt member (guide member); 58, swing unit; 59, side wall; 60, connecting portion; 60a, rotating shaft; 61, rotating support portion; 62, shaft member; 63, guide roller; F, conveying direction; S, sheet; Sa, sheet end; Sb, slack portion; T, conveying path. DETAILED DESCRIPTION

[0042] Figure 1 and Figure 2 The schematic structure of an image forming apparatus 1 according to an embodiment of the present invention is shown. The X-axis, Y-axis, and Z-axis directions of the image forming apparatus 1 are mutually perpendicular. The Z-axis direction is vertical, with the +Z direction being upward and the -Z direction being downward.

[0043] The image forming apparatus 1 supplies a sheet S, which is a single image forming medium, to an image forming unit 10 and forms an image on the surface of the sheet S. The image forming unit 10 is, for example, an inkjet print head that ejects ink onto the sheet S to perform printing.

[0044] Figure 3 1 shows a control system of the image forming apparatus 1 . The image forming apparatus 1 includes a control unit 40 , and operations such as conveyance of a sheet S and image formation on the sheet S described below are performed under the control of the control unit 40 .

[0045] The image forming apparatus 1 includes a sheet conveying device 11 for conveying a sheet S. The width direction of the sheet S when conveyed by the sheet conveying device 11 is the X-axis direction. The sheet conveying device 11 conveys the sheet S from a paper feed portion 12 disposed on the -Y direction side of the image forming portion 10 toward a paper discharge portion 13 disposed on the +Y direction side of the image forming portion 10. That is, the sheet conveying device 11 conveys the sheet S along the conveying direction F from the -Y direction side as the upstream side toward the +Y direction side as the downstream side. The path through which the sheet S passes when conveyed by the sheet conveying device 11 is referred to as a conveying path T (refer to FIG. 1 ). Figure 2 and Figure 7 ).

[0046] The sheet conveying device 11 includes a paper feed device that conveys a sheet S before image formation from the paper feed unit 12 to the image forming unit 10 , and a paper discharge device that conveys a sheet S after image formation from the image forming unit 10 to the paper discharge unit 13 .

[0047] The paper feed section 12 includes a paper feed tray and the like that can accommodate a plurality of sheets S stacked in the Z-axis direction. The paper feed device of the sheet conveying apparatus 11 includes a separation conveying section 14 that separates the sheets S stacked in the paper feed section 12 one by one and conveys them toward the image forming section 10; and a skew correction section 15 that corrects skew of the sheets S conveyed from the paper feed section 12 toward the image forming section 10.

[0048] The separation and conveyance unit 14 includes a conveyance roller 16. The conveyance roller 16 is rotatably supported by a shaft member 16a extending in the X-axis direction and is driven by a conveyance motor 41 (see FIG. Figure 3 ) is driven to rotate. By making the conveying roller 16 contact the upper surface of the sheet S stacked on the paper feeding section 12, and moving the conveying roller 16 toward Figure 2 The conveyor rotates counterclockwise to separate the top sheet S and move it along the conveying direction F.

[0049] The sheets S conveyed one by one by the action of the conveying roller 16 are corrected for skew by the skew correction unit 15 as a skew correction device. The skew of the sheet S refers to the skew of the sheet S. Figure 1 In such a planar view, the sheet S is traveling in a state in which its orientation is tilted relative to the conveying direction F. For example, when the sheet end Sa on the leading end side in the conveying direction F is parallel to the X-axis direction (orthogonal to the Y-axis direction), the sheet S is not skewed. The state in which the sheet end Sa is not parallel to the X-axis direction indicates that the sheet S is skewed.

[0050] The skew correction unit 15 includes a skew amount detection sensor 17 as a skew detection device. Figure 1 As shown in FIG. 1 , the skew amount detection sensor 17 is provided at two locations separated in the X-axis direction. Figure 2As shown, each skew amount detection sensor 17 is a photoelectric sensor having a light projecting portion 17a and a light receiving portion 17b that face each other in the Z-axis direction across the conveyance path T. The light receiving portion 17b receives light projected by the light projecting portion 17a. The light projected by the light projecting portion 17a is blocked by the sheet S, thereby detecting the passage of the sheet end Sa of the sheet S.

[0051] When the sheet S is not skewed relative to the conveying direction F, the detection times of the skew amount detection sensors 17 at the two locations coincide. When the sheet S is skewed relative to the conveying direction F, the detection times of the skew amount detection sensors 17 at the two locations differ. Based on the difference in detection times, the control unit 40 calculates the skew amount of the sheet S. The skew amount of the sheet S calculated by the control unit 40 includes information on the direction in which the sheet end Sa is tilted relative to the X-axis direction and information on the tilt angle of the sheet end Sa relative to the X-axis direction. When the skew amount detection sensor 17 detects that the sheet S is skewed, the control unit 40 causes the skew correction unit 15 to correct the skew. Details of the skew correction performed by the skew correction unit 15 will be described later.

[0052] When the sheet S is conveyed to the bottom of the image forming unit 10 by the paper feeding device, the image forming unit 10 is activated at a predetermined timing, and an image is formed on the sheet S by the image forming unit 10. Alternatively, a lower conveying mechanism (not shown) that conveys the sheet S while suction-holding it may be provided at a position on the opposite side (-Z direction side) of the conveyance path T from the image forming unit 10.

[0053] The sheet conveying device 11 is arranged on the +Y direction side of the image forming unit 10 and includes a pair of conveying rollers 18 and 19 arranged on the -Z direction side and the +Z direction side across the conveying path T. The conveying rollers 18 and 19 are rotatably supported by shaft members 18a and 19a extending in the X-axis direction, respectively. The conveying rollers 18 are driven by a conveying motor 42 (see FIG. Figure 3 ) is driven to rotate. The shaft member 19a supporting the conveying roller 19 is supported so as to be movable in the Z-axis direction, and the conveying roller 19 is urged in the direction of contact with the conveying roller 18. In a state where the sheet S is clamped between the conveying roller 18 and the conveying roller 19, the conveying roller 18 is urged in the direction of contact with the conveying roller 18. Figure 2 The sheet S on which the image has been formed is moved in the conveying direction F and reaches the paper discharge section 13 by the clockwise rotation of the sheet conveyor.

[0054] Next, the details of the skew correction unit 15 will be described. Figures 4 to 12The structure and operation of the skew correction unit 15 are shown. The skew correction unit 15 includes a pair of conveying rollers 20 and 21 arranged on the -Z direction side and the +Z direction side across the conveying path T. The conveying rollers 20 and 21 are rotatably supported by shaft members 20a and 21a extending in the X-axis direction, respectively. The conveying rollers 20 are driven by a conveying motor 43 (see FIG. 4 ). Figure 3 ) is driven to rotate. The shaft member 21a supporting the conveying roller 21 is supported so as to be movable in the Z-axis direction, and the conveying roller 21 is urged in a direction to make it contact with the conveying roller 20. In a state where the sheet S is clamped between the conveying roller 20 and the conveying roller 21, the conveying roller 20 is moved in a direction to Figure 2 and Figure 7 The clockwise rotation of the sheet S moves along the conveying direction F.

[0055] like Figure 4 and Figure 5 As shown, a plurality of conveying rollers 20 and a plurality of conveying rollers 21 are arranged at predetermined intervals in the X-axis direction. The plurality of conveying rollers 20 and the plurality of conveying rollers 21 are arranged in the same region in the X-axis direction, and each conveying roller 20 and the conveying roller 21 form a pair to sandwich the sheet S.

[0056] A swing unit 22 is provided on the +Y direction side of the conveying roller 20 and the conveying roller 21. Figure 1 and Figure 2 As shown, the swing unit 22 is arranged on the +Y direction side relative to the skew amount detection sensor 17 , and the skew of the sheet S detected by the skew amount detection sensor 17 can be corrected by the operation of the swing unit 22 .

[0057] like Figure 6 As shown, the swing unit 22 includes a pair of side walls 23 that are spaced apart in the X-axis direction and a connecting portion 24 that connects the pair of side walls 23. The connecting portion 24 extends in the X-axis direction, and a rotation shaft 24a that extends in the Y-axis direction is provided substantially in the center of the longitudinal direction of the connecting portion 24. The rotation shaft 24a is inserted into a rotation support portion 25 (see FIG. 1 ) that is fixedly supported inside the image forming apparatus 1. Figure 4 and Figure 5 ) formed in the shaft hole of the rotation support portion 25. The swing unit 22 is supported by the shaft hole of the rotation support portion 25 and the rotation shaft 24a so as to be rotatable about an axis parallel to the conveying direction F (an axis extending in the Y-axis direction). The rotation shaft 24a is provided so as to extend substantially across the center of the longitudinal direction of the first support shaft 26 when viewed from above.

[0058] The swing unit 22 further includes a first support shaft 26 and a second support shaft 27 that are substantially parallel to each other. The first support shaft 26 is positioned on the -Z direction side of the transport path T, and the second support shaft 27 is positioned on the +Z direction side of the transport path T. The first support shaft 26 and the second support shaft 27 are each axles having a circular cross-section extending in the X-axis direction, and are supported at both ends by a pair of side walls 23.

[0059] The plurality of cylindrical guide rollers 28 are rotatably supported by the first support shaft 26. The plurality of guide rollers 28 are arranged at predetermined intervals in the axial direction (X-axis direction) of the first support shaft 26.

[0060] In addition to the above-mentioned conveying rollers 20, a plurality of lower guides 30 are also supported on the shaft member 20a. The plurality of lower guides 30 are arranged at different positions in the X-axis direction and are located between the plurality of conveying rollers 20 in the X-axis direction (alternating with the plurality of conveying rollers 20). Figure 7 As shown, each lower guide 30 includes a cylindrical portion 30 b having a shaft hole 30 a at its center through which the shaft member 20 a passes, and a guide arm 30 c protruding toward the +Y direction side relative to the cylindrical portion 30 b.

[0061] The shaft hole 30a is not fixed relative to the shaft member 20a in the rotational direction, and the plurality of lower guide members 30 are supported so as to be independently rotatable relative to the shaft member 20a via the shaft hole 30a. The cylindrical portion 30b is a cylindrical shape having a diameter approximately the same as that of the conveying roller 21. The guide arm 30c is arranged between the plurality of guide rollers 28 in the X-axis direction, and the lower surface near the top of the guide arm 30c is supported by the first support shaft 26 (see FIG. Figure 7 A guide surface 30d is formed on the upper surface of the guide arm 30c. The guide surface 30d is convex toward the +Z direction when the guide arm 30c is supported by the first support shaft 26. The guide surface 30d has a shape that follows a portion of the outer peripheral surface of the guide roller 28.

[0062] A support shaft 31 extending in the X-axis direction is provided on the +Y direction side of the swing unit 22. A plurality of upper guides 32 are supported on the support shaft 31 at predetermined intervals in the axial direction (X-axis direction). The plurality of upper guides 32 are arranged at substantially the same intervals and lengths as the plurality of lower guides 30 in the X-axis direction. Figure 7 As shown, each upper guide 32 includes a cylindrical portion 32 b having a shaft hole 32 a at the center thereof through which the support shaft 31 passes, and a guide arm 32 c protruding toward the −Y direction relative to the cylindrical portion 32 b.

[0063] The shaft hole 32a is not fixed relative to the support shaft 31 in the rotation direction, and the plurality of upper guide members 32 are supported so as to be individually rotatable relative to the support shaft 31 via the shaft hole 32a. Figure 7As shown, the guide arm 32c has an elongated hole 32d formed therein, its longitudinal direction oriented in a radial direction centered on the shaft hole 32a. The second support shaft 27 extends through the elongated hole 32d, supporting the guide arm 32c via the second support shaft 27. A guide surface 32e is formed on the lower surface of the guide arm 32c. The guide surface 32e is an arc-shaped valley-shaped surface that is recessed toward the +Z direction when the guide arm 32c is supported by the second support shaft 27.

[0064] In the skew correction section 15, at the swing unit 22, the guide arms 30c of the plurality of lower guides 30, spaced apart in the width direction of the sheet S, i.e., the X-axis direction, constitute a first guide member, whose guide surfaces 30d support the lower surface of the sheet S. Furthermore, the guide arms 32c of the plurality of upper guides 32, spaced apart in the X-axis direction, constitute a second guide member, whose guide surfaces 32e support the upper surface of the sheet S. The guide surfaces 30d and 32e of the plurality of guide arms 30c and 32c face each other in the Z-axis direction across the conveyance path T, and the sheet S passes between the guide surfaces 30d and 32e. Furthermore, the plurality of guide rollers 28, spaced apart in the X-axis direction between the plurality of guide arms 30c, constitute an auxiliary guide member, supporting the lower surface of the sheet S together with the guide arms 30c.

[0065] like Figure 7 As shown, the conveying path T of the sheet S traveling along the conveying direction F in the skew correction section 15 passes between the conveying roller 20 and the conveying roller 21 located on the -Y direction side, passes through the supporting position of the guide member (guide arm 30c, guide arm 32c, guide roller 28) of the swing unit 22, and follows the outer peripheral surface of the cylindrical portion 32b of the upper guide 32 on the +Y direction side. The supporting position of the guide member of the swing unit 22 for the sheet S is located closer to the +Z direction side than the clamping position of the sheet S by the conveying roller 20 and the conveying roller 21 and the supporting position of the cylindrical portion 32b of the upper guide 32. Therefore, at the portion of the swing unit 22, the sheet S is partially pushed up and becomes a shape protruding to the +Z direction side, forming a mountain-shaped slack portion Sb (see FIG. 1 ) that is slack in a direction perpendicular to the conveying direction F. Figure 2 、 Figure 7 as well as Figure 13 ).

[0066] like Figure 7As shown, a pair of conveyor rollers 33 and 34 are provided on the +Y side of the swing unit 22, positioned on the -Z and +Z sides across the conveyance path T. The conveyor rollers 33 and 34 are rotatably supported by shaft members 33a and 34a, respectively, extending in the X-axis direction. A sheet S that has passed through the swing unit 22 travels along the cylindrical portion 32b of the upper guide 32, passing between the conveyor rollers 33 and 34, and then in the conveyance direction F.

[0067] like Figure 4 As shown, the skew correction unit 15 includes a motor unit 35 that applies a force to the swing unit 22, causing it to rotate about the rotation axis 24a. The motor unit 35 is located adjacent to the side wall 23 on the +X side of the swing unit 22. When the motor included in the motor unit 35 is driven, the driving force is transmitted via a transmission mechanism (not shown), causing the position of the side wall 23 to change in the Z-axis direction. This causes the swing unit 22 to rotate (oscillate) about the axis of the rotation axis 24a. By switching the driving direction of the motor in the motor unit 35, the rotation direction of the swing unit 22 changes, and the rotation angle of the swing unit 22 changes in accordance with the amount of driving force of the motor in the motor unit 35.

[0068] When the swing unit 22 rotates about the rotation shaft 24 a , the angles of the first support shaft 26 and the second support shaft 27 with respect to the X-axis direction change along a plane perpendicular to the conveying direction F. Figure 7 and Figure 8 The skew correction unit 15 is shown in a reference state in which the first support shaft 26 and the second support shaft 27 are parallel to the X-axis direction. Figure 9 and Figure 10 The skew correction section 15 is shown in a state where the swing unit 22 is rotated in the first direction such that the side wall 23 on the +X direction side is displaced to the −Z direction side and the side wall 23 on the −X direction side is displaced to the +Z direction side. Figure 11 and Figure 12 The skew correction section 15 is shown in a state where the swing unit 22 is rotated in the second direction in which the side wall 23 on the +X direction side is displaced in the +Z direction and the side wall 23 on the −X direction side is displaced in the −Z direction.

[0069] like Figures 9 to 12 As shown, when the angle of the first support shaft 26 with respect to the X-axis direction changes, the height position in the Z-axis direction of the guide surface 30d of the guide arm 30c supported by the first support shaft 26 of each of the plurality of lower guides 30 changes to follow the first support shaft 26. Furthermore, when the angle of the first support shaft 26 with respect to the X-axis direction changes, the inclination (height position in the Z-axis direction) of the outer peripheral surface of the plurality of guide rollers 28 supported by the first support shaft 26 changes.

[0070] In the multiple lower guides 30, the height position of the guide arms 30c varies in stages according to the inclination of the first support shaft 26. The guide surface 30d of the guide arm 30c positioned farther away from the rotation axis 24a in the X-axis direction exhibits a greater displacement in the Z-axis direction. Furthermore, the height position of the outer circumference of the multiple guide rollers 28 varies in stages according to the inclination of the first support shaft 26. The outer circumference of the guide rollers 28 positioned farther away from the rotation axis 24a in the X-axis direction exhibits a greater displacement in the Z-axis direction. Therefore, as the swing unit 22 rotates, the inclination of the lower guide surface formed by the multiple guide surfaces 30d and the multiple guide rollers 28 changes.

[0071] like Figures 9 to 12 As shown, if the angle of the second support shaft 27 changes, force is transmitted to the upper guide 32 via the elongated hole 32d through which the second support shaft 27 passes, and the height position of the guide surface 32e of each guide arm 32c of the plurality of upper guides 32 in the Z-axis direction changes in accordance with the second support shaft 27. At this time, the position of the second support shaft 27 in the guide arm 32c changes in the longitudinal direction of the elongated hole 32d, thereby absorbing the difference in the inclination angle of each guide arm 32c and allowing the plurality of upper guides 32 to operate smoothly.

[0072] The multiple upper guides 32 have their guide arms 32c positioned at different heights in stages according to the inclination of the second support shaft 27. The further away in the X-axis direction the guide surface 32e of the guide arm 32c is from the rotation axis 24a, the greater its displacement in the Z-axis direction. Therefore, as the swing unit 22 rotates, the inclination of the upper guide surface formed by the multiple guide surfaces 32e changes.

[0073] In this manner, the skew correction unit 15 changes the inclination of the guide members (upper and lower guide surfaces) supporting the two sides of the sheet S relative to the X-axis direction through the rotation of the swing unit 22. The first support shaft 26 and the second support shaft 27 of the swing unit 22 extend toward both sides of the X-axis relative to the axis of the rotation axis 24a, which serves as the center of rotation. Therefore, the Z-axis displacement of the guide members is opposite in the region on the +X side and the region on the -X side across the rotation axis 24a. Furthermore, as the distance from the rotation axis 24a in the X-axis direction increases, the amount of Z-axis displacement of the guide members increases during the rotation of the swing unit 22. Consequently, the sheet S is displaced in accordance with the displacement of the guide members.

[0074] Specifically, in the region where the guide member of the swing unit 22 is displaced toward the +Z direction, the guide arm 30 c and the guide roller 28, which are arranged on the −Z direction side of the conveyance path T, as guide members, push the sheet S upward toward the +Z direction, thereby displacing the sheet S toward the +Z direction. In the region where the guide member of the swing unit 22 is displaced toward the −Z direction, the guide arm 32 c, which is arranged on the +Z direction side of the conveyance path T, as guide members, presses the sheet S downward toward the −Z direction, thereby displacing the sheet S.

[0075] exist Figure 7 and Figure 8 In the illustrated reference state of the swing unit 22, the first support shaft 26 and the second support shaft 27 are not tilted relative to the X-axis direction, and the height position of the guide member at the swing unit 22 is uniform across the entire X-axis direction. Consequently, the sheet S forms a uniformly shaped slack portion Sb across its entire width, and the sheet S travels along a uniformly long conveyance path across its entire width. In this state, the skew correction unit 15 does not correct the skew of the sheet S, but rather conveys the sheet S in the conveyance direction F at a uniform conveyance distance across its entire width.

[0076] Figure 13 The change in the conveyance path of the sheet S when the swing unit 22 is displaced so as to rotate the region in the width direction (X-axis direction) of the sheet S about an axis parallel to the conveyance direction F is shown. Figure 13 The AA line is a position in the width direction of the sheet S corresponding to the rotation center of the swing unit 22 (the axis line of the rotation shaft 24 a ). Figure 13 Line BB indicates a position in the width direction of the sheet S where the guide member of the swing unit 22 is displaced in the +Z direction compared to the reference state, and particularly shows a position close to one side edge of the sheet S where the displacement in the +Z direction is the largest. Figure 13 The CC line is a portion in the width direction of the sheet S where the guide member of the swing unit 22 is displaced in the −Z direction compared to the reference state, and particularly shows a position close to the other side edge of the sheet S where the displacement in the −Z direction is the largest.

[0077] As Figure 13 As is known, in the region where the guide member of the swing unit 22 is displaced toward the +Z direction (at the position of line BB), the slack amount of the slack portion Sb increases, and the conveyance path of the sheet S becomes longer compared to the reference state. On the other hand, in the region where the guide member of the swing unit 22 is displaced toward the -Z direction (at the position of line CC), the slack amount of the slack portion Sb decreases, and the conveyance path of the sheet S becomes shorter compared to the reference state. The skew correction unit 15 utilizes this change in the conveyance path length on both sides of the width direction of the sheet S to correct the skew of the sheet S.

[0078] For example, Figure 9 and Figure 10 As shown, if the swing unit 22 is rotated in the first direction, the widthwise region of the sheet S supported by the guide member of the swing unit 22 rotates in the first direction about an axis parallel to the conveying direction F, so that the height of the region on the -X direction side is displaced toward the +Z direction side, and the height of the region on the +X direction side is displaced toward the -Z direction side. As a result, a slack portion Sb is formed in the region on the -X direction side of the sheet S, which protrudes more toward the +Z direction side than in the reference state (see FIG. Figure 13 The conveying path of the sheet S is longer than that of the reference state. In the +X direction side area of ​​the sheet S, a slack portion Sb is formed (see FIG. 1 ) with a shape in which the amount of protrusion toward the +Z direction is reduced compared to the reference state. Figure 13 As a result, the area on the -X direction side of the sheet S, where the conveyance path is longer, reaches the image forming unit 10 later than the area on the +X direction side where the conveyance path is shorter.

[0079] like Figure 11 and Figure 12 As shown in FIG. 1 , if the swing unit 22 is rotated in the second direction, the widthwise region of the sheet S supported by the guide member of the swing unit 22 rotates in the second direction about an axis parallel to the conveying direction F, causing the height of the region on the +X direction side to shift toward the +Z direction, and the height of the region on the -X direction side to shift toward the -Z direction. Thus, a slack portion Sb is formed in the region on the +X direction side of the sheet S, which protrudes more toward the +Z direction than in the reference state (see FIG. 1 ). Figure 13 The conveying path of the sheet S is longer than that of the reference state. In the area on the -X direction side of the sheet S, a slack portion Sb is formed (see FIG. 1 ) with a shape in which the amount of protrusion toward the +Z direction is reduced compared to the reference state. Figure 13 As a result, the sheet S in the +X direction, where the conveyance path is longer, reaches the image forming unit 10 later than the sheet S in the -X direction, where the conveyance path is shorter.

[0080] As described above, the timing at which the areas on the +X direction side and the -X direction side of the sheet S arrive at the image forming unit 10 can be changed by tilting the swing unit 22 relative to the X-axis direction. Therefore, if the sheet S is skewed, the swing unit 22 can be operated to displace the guide member toward the +Z direction in the area on the X-axis side where the sheet end Sa is positioned ahead in the conveyance direction F. This can reduce the degree of skew in the sheet S and allow the sheet end Sa, after passing through the swing unit 22, to be oriented closer to parallel with the X-axis direction.

[0081] The greater the inclination of the swing unit 22 with respect to the X-axis direction, the greater the difference in the length of the conveyance path between the region on the +X-direction side and the region on the -X-direction side of the swing unit 22. Therefore, by appropriately adjusting the inclination angle of the swing unit 22 according to the amount of skew of the sheet S, the skew of the sheet S can be corrected so that the orientation of the sheet end Sa is completely parallel to the X-axis direction.

[0082] When the sheet conveying device 11 conveys the sheet S, the control unit 40 uses the skew amount detection sensors 17 at two locations to detect whether the sheet S is skewed. When the sheet S is not skewed, the control unit 40 maintains the swing unit 22 in the reference state ( Figure 7 and Figure 8 ).

[0083] If the sheet S is skewed, the control unit 40 calculates the amount of skew and, based on the amount of skew, determines the direction and amount of rotation of the swing unit 22 to correct the skew. The control unit 40's storage unit stores calculation data and table data used to determine the direction and amount of rotation of the swing unit 22 based on the amount of skew detected by the skew detection sensor 17. The control unit 40 transmits a drive signal corresponding to the determined direction and amount of rotation of the swing unit 22 to the motor unit 35. Upon receiving the drive signal, the motor unit 35 operates to rotate the swing unit 22.

[0084] By performing the above control for each sheet S, the sheet conveying device 11 can correct the skew of the sheet S and convey the sheet S to the image forming unit 10 .

[0085] Furthermore, as a result of rotating the swing unit 22, when the conveyance path of the sheet S becomes flat and free of unevenness in the Z-axis direction at either the +X-direction end or the -X-direction end (the mountain-shaped slack portion Sb present in the reference state disappears), the difference in the length of the conveyance path between the two ends in the X-axis direction is maximized. This state corresponds to the maximum amount of skew that can be corrected by the skew correction unit 15. The greater the length of the slack portion Sb in the reference state, the greater the amount of skew that can be corrected by the skew correction unit 15. However, if the length of the slack portion Sb is excessively increased by the skew correction unit 15, bending, catching, or excessive load may occur during conveyance of the sheet S. Therefore, the slack portion Sb in the reference state is set within a range that allows for smooth conveyance of the sheet S.

[0086] As described above, in the sheet conveying device 11 of this embodiment, the skew correction portion 15 serving as a skew correction device includes a guide member (a guide arm 30c, a guide arm 32c, a guide roller 28) that supports the sheet S along the width direction. The guide member is displaced in accordance with the skew amount of the sheet S detected by the skew amount detection sensor 17 so that the width-direction area of ​​the sheet S supported by the guide member is rotated around an axis parallel to the conveying direction F.

[0087] Thus, the skew correcting unit 15 can correct skew while continuously conveying the sheet S without temporarily stopping the conveyance of the sheet S. Therefore, compared with a configuration in which skew correction is performed while stopping the registration rollers, the conveyance speed per unit time can be increased, enabling efficient sheet conveyance.

[0088] Since the skew correcting unit 15 displaces the guide member in a plane perpendicular to the conveying direction F, a long space along the conveying direction F is not required, and miniaturization in the Y-axis direction can be achieved.

[0089] In addition, the skew correction section 15 corrects the skew by rotating the width direction area of ​​the sheet S supported by the guide member around an axis parallel to the conveying direction F. Therefore, compared with the skew correction structure that relatively changes the operation speed of multiple conveying devices arranged at different positions in the conveying direction F, the sheet S is less likely to be deformed and the sheet S can be conveyed with high precision.

[0090] The skew correction unit 15 slackly supports the sheet S in a direction perpendicular to the conveyance direction F (forming a slack portion Sb). By displacing the guide member, the amount of slack on either side of the sheet S in the width direction relatively changes, thereby altering the conveyance path length. Consequently, even if areas on either side of the sheet S in the width direction are skewed in the conveyance direction F, the skew can be corrected by switching the direction of rotation of the guide member. Furthermore, the gently curved slack portion Sb forms the conveyance path for the sheet S in the skew correction unit 15, allowing the sheet S to pass smoothly through the skew correction unit 15 without imposing a significant load on the sheet S.

[0091] The skew correction unit 15 includes a first support shaft 26 and a second support shaft 27, which are arranged on one side and the other side of the conveyance path T of the sheet S in a direction perpendicular to the conveyance direction F of the sheet S (the Z-axis direction) and extend in the width direction (the X-axis direction) of the sheet S, respectively. The first support shaft 26 and the second support shaft 27 are integrally rotated about axes parallel to the conveyance direction F according to the amount of skew of the sheet S. Furthermore, the two side surfaces of the sheet S are supported by a first guide member, namely a guide arm 30c, which moves in accordance with the first support shaft 26, and a second guide member, namely a guide arm 32c, which moves in accordance with the second support shaft 27.

[0092] This allows the guide members to support both sides of the sheet S using a space-saving structure in which the guide arms 30c and 32c are integrated near the first support shaft 26 and the second support shaft 27, which are arranged at a predetermined interval in the Z-axis direction. Furthermore, by integrally rotating the first support shaft 26 and the second support shaft 27 as the swing unit 22, the guide arms 30c and 32c, which are arranged on either side of the conveyance path T in the Z-axis direction, can be driven in a coordinated manner using a simple structure. Consequently, the movement of the first support shaft 26 and the second support shaft 27 can be transmitted to the sheet S without delay via the guide arms 30c and 32c, achieving highly responsive skew correction.

[0093] The lower guide 30 having the guide arm 30c is supported by the shaft member 20a, which supports the conveyor roller 20 disposed adjacent to the swing unit 22 on the -Y direction side of the swing unit 22. In this manner, the lower guide 30 is supported astride the shaft member 20a supporting the conveyor roller 20 and the first support shaft 26 supporting the guide arm 30c and the guide roller 28. This allows the lower guide 30 to be provided with a highly space-efficient structure.

[0094] The upper guide 32 having the guide arm 32c is supported by the support shaft 31 disposed adjacent to the swing unit 22 on the +Y direction side of the swing unit 22. Figure 7 As shown, the cylindrical portion 32b of the upper guide 32, which is supported by the support shaft 31, has the function of guiding the conveyance of the sheet S after passing through the swing unit 22. Specifically, in the upper guide 32, not only the guide arm 32c but also the cylindrical portion 32b contributes to the formation of the conveyance path T of the sheet S, including the slack portion Sb. Thus, the upper guide 32 has a combined function achieved by the cylindrical portion 32b and the guide arm 32c, enabling the efficient configuration of the skew correcting unit 15 with a reduced number of components.

[0095] The skew correction section 15 includes a plurality of guide rollers 28 in addition to a plurality of guide arms 30c as a guide member for supporting the lower side (-Z direction side) of the sheet S. The plurality of guide arms 30c are arranged at intervals in the width direction of the sheet S, and a plurality of guide rollers 28 are arranged between the plurality of guide arms 30c. The plurality of guide rollers 28 are provided in a manner that fills the gaps between the plurality of guide arms 30c in the width direction of the sheet S, thereby supporting the lower surface side of the sheet S over a larger range in the width direction, thereby improving the stability of the sheet S and reliably displacing the sheet S in the +Z axis direction when correcting the skew. The guide rollers 28 are supported by the first support shaft 26 together with the guide arms 30c. Therefore, there is no need for a dedicated drive source for operating the guide rollers 28, and the guide rollers 28 can be displaced together with the guide arms 30c using a simple structure.

[0096] In addition, a guide roller similar to the guide roller 28 may be provided as a guide member supporting the upper side (+Z direction side) of the sheet S. Specifically, a plurality of guide rollers supported so as to be rotatable by the second support shaft 27 may be provided between a plurality of guide arms 32c arranged at intervals in the width direction of the sheet S. Therefore, it is preferred that a guide roller (including the guide roller 28) located between the plurality of guide arms 30c and between the plurality of guide arms 32c in the width direction of the sheet S be supported on at least one of the first support shaft 26 and the second support shaft 27 as a member supplementing either the guide arm 30c or the guide arm 32c.

[0097] The guide member for skew correction is not limited to the structure of the guide arm 30 c , the guide arm 32 c , and the guide roller 28 in the above-mentioned embodiment. Figures 14 to 17 The skew correction unit 50 of a different embodiment is shown. Figures 14 to 17 In the sheet conveying apparatus, the configuration other than the skew correcting portion 50 is omitted from the illustration, and the sheet conveying apparatus includes a configuration equivalent to that of the sheet conveying apparatus 11 of the above-described embodiment except for the skew correcting portion 50 .

[0098] The skew correction unit 50 includes a lower guide unit 51 disposed on the -Z direction side and an upper guide unit 52 disposed on the +Z direction side. The guide member of the skew correction unit 50 is constituted by an annular (ring-shaped) first belt member 53 of the lower guide unit 51 and an annular second belt member 54 of the upper guide unit 52. Figure 14 In the figure, the second belt member 54 is omitted.

[0099] The lower guide unit 51 includes an upstream roller 55 positioned on the -Y side and a downstream roller 56 positioned on the +Y side. The upstream roller 55 and the downstream roller 56 are rotatably supported by shaft members 55a and 56a, respectively, extending in the X-axis direction. At least one of the upstream roller 55 and the downstream roller 56 is driven for rotation by a conveying motor (not shown). An annular first belt member 53 is stretched across the upstream roller 55 and the downstream roller 56. A rod-shaped tensioner 57 extending in the X-axis direction is positioned between the upstream roller 55 and the downstream roller 56. The tensioner 57 applies a predetermined tension to the first belt member 53 by pressing the first belt member 53 toward the -Z side.

[0100] The lower guide unit 51 further includes a swing unit 58. The swing unit 58 is disposed between the upstream roller 55 and the downstream roller 56 in the Y-axis direction, and the tensioner 57 is disposed on the -Z direction side of the swing unit 58.

[0101] like Figure 14 As shown, the swing unit 58 includes a pair of side walls 59 spaced apart in the X-axis direction and a connecting portion 60 connecting the pair of side walls 59. The connecting portion 60 extends in the X-axis direction, and a rotation shaft 60a extending in the Y-axis direction is provided approximately at the center of the longitudinal direction of the connecting portion 60. The rotation shaft 60a is inserted into an axial hole formed in a fixedly supported rotation support portion 61. A shaft member 62 extending parallel to the connecting portion 60 is supported at both ends by the pair of side walls 59.

[0102] The shaft member 62 rotatably supports a plurality of guide rollers 63. The guide rollers 63 are arranged at predetermined intervals in the longitudinal direction (X-axis direction) of the shaft member 62. The outer circumferential surfaces of the guide rollers 63 contact the lower surface of the first belt member 53 along a linear region extending in the X-axis direction, between the upstream roller 55 and the downstream roller 56 in the Y-axis direction.

[0103] The swing unit 58 having a plurality of guide rollers 63 is supported rotatably about an axis (axis in the Y-axis direction) parallel to the conveying direction F via the shaft hole of the rotation support portion 61 and the rotation shaft 60a. The swing unit 58 is subjected to a force to rotate about the rotation shaft 60a by a motor unit (not shown).

[0104] When the swing unit 58 rotates about the rotation axis 60a, the angle of the shaft member 62 relative to the X-axis direction changes along a plane perpendicular to the conveying direction F. As the angle of the shaft member 62 changes, the inclination (height position in the Z-axis direction) of the outer peripheral surface of the plurality of guide rollers 63 supported by the shaft member 62 changes. As a result, the area of ​​the first belt member 53 supported by the outer peripheral surface of the plurality of guide rollers 63 displaces along a plane perpendicular to the conveying direction F, causing the inclination relative to the X-axis direction to change.

[0105] The upper guide unit 52 includes an upstream roller 65 disposed on the -Y direction side and a downstream roller 66 disposed on the +Y direction side. The upstream roller 65 and the downstream roller 66 are rotatably supported by shaft members 65a and 66a, respectively, extending in the X-axis direction. At least one of the upstream roller 65 and the downstream roller 66 is driven for rotation by a conveying motor (not shown). An annular second belt member 54 is stretched between the upstream roller 65 and the downstream roller 66. A rod-shaped tensioner 67 extending in the X-axis direction is disposed between the upstream roller 65 and the downstream roller 66. The tensioner 67 applies a predetermined tension to the second belt member 54 by pressing the second belt member 54 toward the +Z direction.

[0106] like Figures 15 to 17 As shown, the conveyance path T of the sheet S in the skew correction section 50 is formed in the portion where the first belt member 53 of the lower guide unit 51 and the second belt member 54 of the upper guide unit 52 face each other. The first belt member 53 and the second belt member 54 have supporting surfaces in this facing portion for supporting the sheet S. Furthermore, a slack portion Sb is formed in the sheet S, with the first belt member 53 serving as a lower guide member and the second belt member 54 serving as an upper guide member.

[0107] When the swing unit 58 rotates around the rotation axis 60a, the shapes of the supporting surfaces of the first and second belt members 53 and 54 supporting the sheet S change, so that the widthwise regions of the supported sheet S are displaced in a rotational manner around an axis parallel to the conveying direction F. Figures 15 to 17 An example of displacement of the sheet S at the end portion on the +X direction side of the skew correcting section 50 is shown.

[0108] exist Figure 15 In the illustrated reference state of the swing unit 58, the shaft member 62 is not tilted relative to the X-axis direction, and the entire widthwise region of the sheet S forms a uniformly shaped slack portion Sb, allowing the entire widthwise region of the sheet S to travel along a uniformly long conveyance path. In this state, the skew correction unit 50 does not correct the skew of the sheet S but rather conveys the entire widthwise region of the sheet S in the conveyance direction F at a uniform conveyance amount.

[0109] Figure 16The skew correction section 50 is shown in a state where the swing unit 58 is rotated in the first direction in which the end of the shaft member 62 on the +X direction side is displaced to the -Z direction side and the end of the shaft member 62 on the -X direction side is displaced to the +Z direction side. When the swing unit 58 is rotated in the first direction, the first belt member 53 supported by a plurality of guide rollers 63 displaces the height of the area on the -X direction side to the +Z direction side and the height of the area on the +X direction side to the -Z direction side with the rotation axis 60a as the center within a plane perpendicular to the conveying direction F. The second belt member 54 of the upper guide unit 52 is displaced following the displacement of the first belt member 53. As a result, a slack portion Sb is formed in the area on the +X direction side of the sheet S in a shape in which the amount of protrusion to the +Z direction side is reduced compared to the reference state, and the conveying path of the sheet S becomes shorter than that of the reference state. Although not in Figure 16 However, in the region on the -X direction side of the sheet S, a slack portion Sb is formed that protrudes more toward the +Z direction side than in the reference state, and the conveyance path of the sheet S becomes longer than in the reference state.

[0110] Figure 17 The skew correction section 50 is shown in a state where the swing unit 58 is rotated in the second direction in which the end of the shaft member 62 on the +X direction side is displaced to the +Z direction side and the end of the shaft member 62 on the -X direction side is displaced to the -Z direction side. When the swing unit 58 is rotated in the second direction, the first belt member 53 supported by a plurality of guide rollers 63 displaces the height of the area on the +X direction side to the +Z direction side and the height of the area on the -X direction side to the -Z direction side with the rotation axis 60a as the center within a plane perpendicular to the conveying direction F. The second belt member 54 of the upper guide unit 52 is displaced following the displacement of the first belt member 53. As a result, a slack portion Sb is formed in the area on the +X direction side of the sheet S in a shape in which the amount of protrusion to the +Z direction side is increased compared to the reference state, and the conveying path of the sheet S becomes longer than the reference state. Although not in Figure 17 However, in the region on the -X direction side of the sheet S, a slack portion Sb is formed in a shape where the protrusion amount toward the +Z direction side is reduced compared to the reference state, and the conveyance path of the sheet S becomes shorter than that in the reference state.

[0111] As described above, the skew correction section 50 includes a first belt member 53 and a second belt member 54, which are arranged on one side and the other side of the conveyance path T in a direction perpendicular to the conveyance direction F of the sheet S (the Z-axis direction) and support surfaces sandwiching both sides of the sheet S. Furthermore, the swing unit 58 is rotated according to the amount of skew of the sheet S to change the shapes of the supporting surfaces of the first belt member 53 and the second belt member 54. This changes the relative lengths of the conveyance paths between the -X direction side and the +X direction side of the sheet S, thereby performing skew correction on the sheet S.

[0112] The skew correction section 50 utilizes the first belt member 53 and the second belt member 54 as guiding members to clamp the two side surfaces of the sheet S while conveying the sheet S. Therefore, when correcting the skew, the sheet S has excellent tracking performance relative to the displacement of the first belt member 53 and the second belt member 54, which can prevent the position of the sheet S from being offset and improve the accuracy of the skew correction.

[0113] In the lower guide unit 51, when the first belt member 53 rotates between the upstream roller 55 and the downstream roller 56, the guide roller 63 rotates following the first belt member 53, thereby enabling the first belt member 53 to move smoothly. Therefore, when correcting skew, it is preferable to displace the first belt member 53 with the help of the guide roller 63. However, it is also possible to displace the first belt member 53 by bringing a rod-shaped member such as the shaft member 62 into contact with the first belt member 53 without using the guide roller 63.

[0114] The above embodiments are examples of sheet conveying devices that are applied to an image forming apparatus. By being applied to sheet conveying in an image forming apparatus, the skew of the sheet can be corrected with high precision using a compact structure, thereby improving the quality of the image formed. However, the sheet conveying device of the present invention can be applied to devices other than image forming apparatuses as long as the sheet is conveyed, regardless of the type or purpose of the sheet. For example, in a processing device that performs processing such as cutting on a sheet, it can also be applied to a situation where the skew of the sheet is corrected and the sheet is conveyed to the position of a processing tool. When conveying a sheet while the sheet is skewed relative to the processing tool, the processing position of the sheet by the processing tool is offset relative to the pre-set processing position. Therefore, the sheet conveying device of the present invention is useful in order to prevent the positional offset of the sheet caused by the skew.

[0115] The skew detection device for detecting the skew amount of the sheet relative to the conveying direction is not limited to a photoelectric sensor such as the skew amount detection sensor 17 of the above embodiment. For example, an ultrasonic sensor that detects the passage of the sheet by oscillating ultrasonic waves and receiving reflected waves may also be used.

[0116] In addition, the present invention is not limited to the above-mentioned embodiments as they are, and the structural elements can be deformed and concretized in the implementation stage without departing from the scope of its main purpose. In addition, it is possible to form various technical solutions by using appropriate combinations of multiple structural elements disclosed in the above-mentioned embodiments. For example, all the structural elements shown in the embodiments can also be appropriately combined. Of course, various modifications and applications can be made within the scope of such a scope without departing from the main purpose of the invention. Below, a part of the technical solutions recorded in the specification of this application is appended.

[0117] [Note 1]

[0118] A sheet conveying device comprising: a skew detection device for detecting the amount of skew of a conveyed sheet relative to a conveying direction; and a skew correction device for correcting the skew of the sheet, characterized in that:

[0119] The skew correction device includes a guide member that supports the sheet along the width direction, and displaces the guide member in accordance with the skew amount of the sheet detected by the skew detection device so that the width direction area of ​​the sheet supported by the guide member rotates around an axis parallel to the conveying direction.

[0120] [Note 2]

[0121] The sheet conveying device according to Supplementary Note 1 is characterized in that:

[0122] The guide member loosely supports the sheet in a direction perpendicular to the conveying direction.

[0123] The displacement of the guide member relatively changes the slack amounts on both sides of the sheet in the width direction, thereby changing the conveyance path length.

[0124] [Note 3]

[0125] The sheet conveying device according to Supplementary Note 1 or 2 is characterized in that:

[0126] The skew correction device includes a first support shaft and a second support shaft, each of which is arranged on one side and the other side of the sheet conveying path in a direction perpendicular to the sheet conveying direction and extends in the width direction of the sheet, respectively. The first support shaft and the second support shaft are rotated integrally around an axis parallel to the conveying direction according to the skew amount of the sheet.

[0127] The guide member includes a first guide member that moves following the first support shaft and a second guide member that moves following the second support shaft, and the first guide member and the second guide member support both sides of the sheet.

[0128] [Note 4]

[0129] The sheet conveying device according to Supplementary Note 3 is characterized in that:

[0130] A plurality of the first guide members and a plurality of the second guide members are provided at intervals in the width direction of the sheet.

[0131] The first support shaft supports a plurality of rotatable rollers located between the plurality of first guide members in the width direction of the sheet, and / or the second support shaft supports a plurality of rotatable rollers located between the plurality of second guide members in the width direction of the sheet.

[0132] [Note 5]

[0133] The sheet conveying device according to Supplementary Note 1 or 2 is characterized in that:

[0134] The guide member includes a first belt member and a second belt member that are arranged on one side and the other side of the sheet conveyance path in a direction perpendicular to the sheet conveyance direction and support surfaces sandwiching both sides of the sheet.

[0135] The skew correction device changes the shape of each supporting surface of the first belt member and the second belt member according to the skew amount of the sheet.

Claims

1. A sheet conveying device comprising: a skew detection device for detecting an amount of skew of a conveyed sheet relative to a conveying direction; and a skew correction device for correcting the skew of the sheet, characterized in that: The skew correction device includes a guide member that supports the sheet along the width direction, and displaces the guide member in accordance with the skew amount of the sheet detected by the skew detection device so that the width direction area of ​​the sheet supported by the guide member rotates around an axis parallel to the conveying direction.

2. The sheet material conveying device according to claim 1, wherein: The guide member loosely supports the sheet in a direction perpendicular to the conveying direction. The displacement of the guide member relatively changes the slack amounts on both sides of the sheet in the width direction, thereby changing the conveyance path length.

3. The sheet material conveying device according to claim 1 or 2, characterized in that: The skew correction device includes a first support shaft and a second support shaft, each of which is arranged on one side and the other side of the sheet conveying path in a direction perpendicular to the sheet conveying direction and extends in the width direction of the sheet, respectively. The first support shaft and the second support shaft are rotated integrally around an axis parallel to the conveying direction according to the skew amount of the sheet. The guide member includes a first guide member that moves following the first support shaft and a second guide member that moves following the second support shaft, and the first guide member and the second guide member support both sides of the sheet.

4. The sheet material conveying device according to claim 3, wherein: A plurality of the first guide members and a plurality of the second guide members are provided at intervals in the width direction of the sheet. The first support shaft supports a plurality of rotatable rollers located between the plurality of first guide members in the width direction of the sheet, and / or the second support shaft supports a plurality of rotatable rollers located between the plurality of second guide members in the width direction of the sheet.

5. The sheet material conveying device according to claim 1 or 2, characterized in that: The guide member includes a first belt member and a second belt member that are arranged on one side and the other side of the sheet conveyance path in a direction perpendicular to the sheet conveyance direction and support surfaces sandwiching both sides of the sheet. The skew correction device changes the shape of each supporting surface of the first belt member and the second belt member according to the skew amount of the sheet.

Images