Sheet transport device and image forming apparatus

Abstract

To provide a sheet conveying device capable of stably correcting skew of a sheet regardless of a type of the sheet.SOLUTION: When a sheet to be conveyed is of a first type, a CPU moves a conveying roller pair to a shift section based on a detection result of a lateral registration detection device so that a distance from a contact surface to one end in a width direction of the sheet held between the conveying roller pair is the first distance (S15). When the sheet to be conveyed is of a second type different from the first type, the CPU moves the conveying roller pair to the shift section so that the sheet held between the conveying roller pair moves at a second distance to the other end in the width direction (S16).SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus that forms an image on a sheet. [Background Art]

[0002] In an image forming apparatus, skew of a sheet during conveyance can be corrected (skew correction) by conveying the sheet being conveyed by a skew feeding roller such that an end of the sheet in a width direction perpendicular to the conveyance direction follows a reference guide. In such an image forming apparatus, a configuration has been proposed in which, before correcting the skew of the sheet using the skew feeding roller and the reference guide, the position of an end of the sheet in the width direction is detected by a detection device, and the position of the sheet in the width direction is adjusted using the detection result (see Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-13356 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, in the image forming apparatus described in Patent Document 1, when the sheet is made of transparent paper such as an OHP film and the detection device cannot detect the end of the sheet in the width direction, the position of the sheet in the width direction cannot be adjusted using the detection result before skew correction of the sheet. Therefore, in the image forming apparatus described in Patent Document 1, when the sheet is of a type that cannot be detected by the detection device, variation occurs in the position of the sheet in the width direction before skew correction, and there is a risk that the leading end of the sheet in the conveyance direction collides with the reference guide.

[0005] An object of the present invention is to provide a sheet conveying apparatus capable of stably correcting skew of a sheet regardless of the type of the sheet. [Means for Solving the Problem]

[0006] The present invention comprises: a first rotating body for gripping and conveying a sheet; a first rotating body moving unit for moving the first rotating body, while gripping the sheet, in a width direction perpendicular to the sheet conveying direction; a contact member positioned downstream of the first rotating body in the sheet conveying direction and on one side in the width direction, extending along the sheet conveying direction and having a contact surface capable of contacting the end of the sheet in the width direction; an oblique conveying rotating body for moving the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction; a detection unit for detecting the position of the one end of the sheet in the width direction being conveyed by the first rotating body; and a control unit for controlling the first rotating body moving unit, wherein the control unit A sheet in which the position of the end in the width direction can be detected by the detection unit Transported When Based on the detection result of the detection unit, the first rotating body is moved by the first rotating body moving unit so that the distance from the contact surface to one end of the sheet held between the first rotating body becomes the first distance. The detection unit detects a sheet having transparency that makes it impossible to detect the position of the end in the width direction. Transported When The sheet is sandwiched between the first rotating body. So that the tip does not collide with the contact member, The first rotating body moves The other side in the width direction is the second distance It is characterized by the ability to move.

[0007] Furthermore, the present invention comprises: a first rotating body for gripping and conveying a sheet; a first rotating body moving unit for moving the first rotating body, while gripping a sheet, in a width direction perpendicular to the sheet conveying direction; a contact member positioned downstream of the first rotating body in the sheet conveying direction and on one side in the width direction, extending along the sheet conveying direction and having a contact surface capable of contacting the end of the sheet in the width direction; a contact member moving unit for moving the contact member in the width direction; an oblique conveying rotating body for moving the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction; a detection unit for detecting the position of the one end of the sheet in the width direction being conveyed by the first rotating body; and a control unit for controlling the first rotating body moving unit and the contact member moving unit, wherein the control unit A sheet in which the position of the end in the width direction can be detected by the detection unit Transported When Based on the detection result of the detection unit, the first rotating body is moved by the first rotating body moving unit so that the distance from the contact surface to one end of the sheet held between the first rotating body becomes the first distance. The detection unit detects a sheet having transparency that makes it impossible to detect the position of the end in the width direction. Transported When to, To prevent the tip of the sheet held in the first rotating body from colliding with the contact member, The contact member is moved to the contact member moving part. The first of the above is a second distance It is characterized by the ability to move.

[0008] Furthermore, the present invention comprises: a first rotating body for gripping and conveying a sheet; a contact member positioned downstream of the first rotating body in the sheet conveying direction and on one side in the width direction perpendicular to the sheet conveying direction, extending along the sheet conveying direction and having a contact surface capable of contacting the end of the sheet in the width direction; a contact member moving unit for moving the contact member in the width direction; an oblique conveying rotating body for moving the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction; a detection unit for detecting the position of the one end of the sheet in the width direction being conveyed by the first rotating body; and a control unit for controlling the contact member moving unit, wherein the control unit A sheet in which the position of the end in the width direction can be detected by the detection unit Transported WhenBased on the detection result of the detection unit, the contact member is moved to the contact member moving unit so that the distance from the contact surface to one end of the sheet held in the first rotating body becomes the first distance. The detection unit detects a sheet having transparency that makes it impossible to detect the position of the end in the width direction. Transported When to, To prevent the tip of the sheet held in the first rotating body from colliding with the contact member, The contact member is moved to the contact member moving part. The first of the above is a second distance It is characterized by the ability to move. [Effects of the Invention]

[0009] According to the present invention, sheet skew can be reliably corrected regardless of the type of sheet. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of an image forming apparatus according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram of a sheet conveying device according to the first embodiment of the present invention. [Figure 3] (a) is a cross-sectional view of the sheet conveying section of the first embodiment of the present invention when the conveying roller pair is in a clamping state, and (b) is a cross-sectional view of the conveying roller pair when it is released from clamping. [Figure 4] This is a perspective view showing the drive configuration of a conveyor roller pair according to the first embodiment of the present invention. [Figure 5] (a) is a top view showing the drive configuration of a pair of oblique rollers according to the first embodiment of the present invention, and (b) is a cross-sectional view in the direction of arrow E shown in (a). [Figure 6] (a) is a perspective view showing the pressure contact and separation mechanism of a pair of oblique feed rollers according to a first embodiment of the present invention, and (b) is a side view showing the pressure contact and separation mechanism of a pair of oblique feed rollers. [Figure 7] (a) is a side view showing the pair of oblique feed rollers according to the first embodiment of the present invention in a clamped state, and (b) is a side view showing the pair of oblique feed rollers in a released state. [Figure 8] This is a perspective view showing a sheet transport unit according to the first embodiment of the present invention. [Figure 9]It is a perspective view showing the driving unit of the conveying roller pair according to the first embodiment of the present invention. [Figure 10] It is a perspective view showing the shift unit of the conveying roller pair according to the first embodiment of the present invention. [Figure 11] (a) is a perspective view showing the pressure release mechanism of the conveying roller pair according to the first embodiment of the present invention, and (b) is a cross-sectional view showing the pressure release mechanism of the conveying roller pair. [Figure 12] It is a functional block diagram showing the control configuration of the sheet conveying apparatus according to the first embodiment of the present invention. [Figure 13] (a) is a top view showing a state where a sheet whose side edge can be detected is conveyed by the lateral registration detecting device of the sheet aligning apparatus according to the first embodiment of the present invention, (b) is a cross-sectional view of the state shown in (a). Further, (c) is a top view showing a state where the sheet is conveyed from the state shown in (a) and (b) to a position where the sheet can be conveyed by the conveying roller pair, and (d) is a cross-sectional view of the state shown in (c). [Figure 14] (a) is a top view showing an example of a state where a sheet whose side edge cannot be detected is conveyed by the lateral registration detecting device of the sheet aligning apparatus, and is conveyed to the contact member without registration correction, and (b) is a cross-sectional view of the state shown in (a). [Figure 15] (a) is a top view showing a state where registration correction is executed when a sheet whose side edge cannot be detected is conveyed by the lateral registration detecting device of the sheet aligning apparatus according to the first embodiment of the present invention, and (b) is a cross-sectional view of the state shown in (a). [Figure 16] (a) is a top view showing a state where skew correction is performed in the sheet aligning apparatus according to the first embodiment of the present invention, and (b) is a cross-sectional view of the state shown in (a). [Figure 17] (a) is a top view showing a state where correction by a registration roller pair is performed in the sheet aligning apparatus according to the first embodiment of the present invention, and (b) is a cross-sectional view of the state shown in (a). [Figure 18]This flowchart shows the control process when the CPU of a printing apparatus according to the first embodiment of the present invention performs registration correction and skew correction. [Figure 19] This flowchart shows the control process when the CPU of a printing apparatus according to the first embodiment of the present invention performs registration correction and skew correction. [Figure 20] (a) is a top view showing the state in which registration correction is performed when a sheet whose side edge cannot be detected by the lateral registration detection device of the sheet alignment device according to the second embodiment of the present invention is transported, and (b) is a cross-sectional view of the state shown in (a). [Figure 21] This flowchart shows the control process when the CPU of a printing apparatus according to the second embodiment of the present invention performs registration correction and skew correction. [Figure 22] This flowchart shows the control process when the CPU of a printing apparatus according to the second embodiment of the present invention performs registration correction and skew correction. [Modes for carrying out the invention]

[0011] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described in detail with reference to Figures 1 to 19.

[0012] <Configuration of an image forming apparatus> Full-color image forming machines are classified into two types: the tandem system, in which multiple process cartridges are arranged side-by-side, and the rotary system, in which multiple process cartridges are arranged in a cylindrical shape. Furthermore, image forming machines are classified into two types based on the transfer method: the direct transfer method, in which the toner image is transferred directly from the photoreceptor to the sheet, and the intermediate transfer method, in which the image is first transferred to an intermediate transfer belt before being transferred to the sheet. The intermediate transfer method does not require the sheet to be held on a transfer drum or transfer belt like the direct transfer method, can handle a wide variety of transfer materials such as extra-thick paper and coated paper, and is suitable for achieving high productivity through parallel processing in multiple image forming units and simultaneous transfer of full-color images.

[0013] Figure 1 is a cross-sectional view of an intermediate transfer tandem type image forming apparatus 1, in which image forming units 513 that form four-color toner images are arranged side by side on an intermediate transfer belt 506. As shown in Figure 1, the sheets S are stored by being stacked on a lift-up device 52 of a sheet feeding device 51, and are fed by a sheet feeding means 53 in accordance with the image forming timing of the image forming apparatus 1.

[0014] The sheet feeding means 53 can utilize methods such as frictional separation using paper feed rollers or methods such as separation and adsorption using air. The sheet feeding means 53 in the image forming apparatus 1 shown in Figure 1 uses an air-based sheet feeding method.

[0015] The sheet S, fed by the sheet feeding means 53, passes through the transport path 54a and transport roller section 50 of the transport unit 54, and is transported to the skew correction section 55. After skew correction and timing correction are performed in the skew correction section 55, the sheet S is transported to the secondary transfer section 40. The secondary transfer section 40 is a toner image transfer and clamping section for the sheet, formed by substantially opposing secondary transfer inner rollers 503 and secondary transfer outer rollers 56. By applying a predetermined pressure and electrostatic load bias to the sheet S, a toner image is transferred to the sheet S.

[0016] Next, we will describe the image formation process for the image that is sent to the secondary transfer unit 40 at a similar timing to the sheet S transport process described above. The image forming unit 513 is equipped with four process cartridges 513Y, 513M, 513C, and 513Bk that form toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (Bk). The image forming apparatus 1 also has an intermediate transfer belt 506 that is wrapped around a tension roller 505, a drive roller 504, and a secondary transfer internal roller 503, and rotated in the direction of arrow B by the drive roller 504. The four process cartridges 513Y, 513M, 513C, and 513Bk have the same configuration except for the color of the image they form. Therefore, only the configuration and image formation process of process cartridge 513Y will be described, and the descriptions of process cartridges 513M, 513C, and 513Bk will be omitted.

[0017] The process cartridge 513Y consists of a photosensitive drum 508, an exposure unit 511, a developer unit 510, a primary transfer unit 507, and a cleaner 509, etc. The photosensitive drum 508 is constructed by coating the outer circumference of an aluminum cylinder with an organic photoconductive layer and rotates in the direction of arrow A by a drive motor. When an image signal is input to the exposure unit 511 from a personal computer or the like, the exposure unit 511 irradiates the photosensitive drum 508 of the process cartridge 513Y with laser light corresponding to the image signal.

[0018] At this time, the surface of the photosensitive drum 508 is uniformly charged to a predetermined polarity and potential by a charging roller, and an electrostatic latent image is formed on the surface when laser light is irradiated from the exposure device 511 via the diffraction means 512, etc. The electrostatic latent image formed on the photosensitive drum 508 is developed by the developer 510, and a yellow (Y) toner image is formed on the photosensitive drum 508.

[0019] After a toner image is formed on the photosensitive drum 508, a predetermined pressure and electrostatic load bias are applied by the primary transfer device 507, and the toner image is transferred onto the intermediate transfer belt 506. Subsequently, in the process cartridge 513Y, any remaining toner on the photosensitive drum 508 is collected by the cleaner 509, and the cartridge is prepared again for the next image formation.

[0020] Similarly, laser light is irradiated from each exposure device onto the photosensitive drums of process cartridges 513M, 513C, and 513Bk, and magenta (M), cyan (C), and black (Bk) toner images are formed on each photosensitive drum. The toner images of each color formed on each photosensitive drum are transferred to the intermediate transfer belt 506 by each primary transfer device. The image formation process for each color, which is processed in parallel by the image forming unit 513, is performed at a timing that overlaps with the upstream toner image that has been primary transferred onto the intermediate transfer belt 506, and a full-color toner image is formed on the intermediate transfer belt 506 and transported to the secondary transfer unit 40.

[0021] Through this sheet S transport process and image forming process, the image forming apparatus 1 secondarily transfers a full-color toner image onto the sheet S in the secondary transfer section 40. The sheet S on which the toner image has been secondarily transferred is transported to the fixing apparatus 58 by the pre-fixing sheet transport device 57.

[0022] The fixing device 58 melts and fixes toner onto the sheet S by applying a predetermined pressure using substantially opposing rollers or belts, and by heating with a heat source such as a heater. When an image is formed on one side of the sheet S having the fixed image obtained in this way, the sheet S is transported to the discharge tray 500 by the branching transport device 59. When an image is formed on both sides of the sheet S, the branching transport device 59 transports the sheet S to the reversing transport device 501 and switches it back. The switched back sheet S is transported from the reversing transport device 501 to the double-sided transport unit 502 and guided to the transport unit 54. After this, an image is formed on the second sheet surface (back side) in the secondary transfer section 40 and the sheet S is transported to the discharge tray 500.

[0023] <Sheet Alignment Device> The sheet alignment device 10, which is a sheet transport device provided in the image forming apparatus 1, incorporates a skew correction unit 55 for correcting misalignment of the sheet S during transport. The skew correction unit 55 uses a side registration method to correct misalignment of the sheet S based on the position of the edge (side edge) in the width direction perpendicular to the transport direction of the sheet S during transport. In the first embodiment, the skew correction unit 55 is located upstream of the secondary transfer unit 40 in the transport direction of the sheet S. Note that the skew correction unit 55 using the side registration method is not limited to being located upstream of the secondary transfer unit 40 in the transport direction, but may also be installed in the sheet post-processing device when the sheet post-processing device is located downstream of the fixing device 58 in the transport direction.

[0024] Figure 2 is a top view showing a sheet alignment device 10 having a conveyor roller section 50, a skew correction section 55, and a pair of registration rollers 7. As shown in Figure 2, the conveyor roller section 50 of the sheet alignment device 10 has four pairs of conveyor rollers 34a to 34d that convey the sheet S, and a lateral registration detection device 60 that detects the position of the side edge of the sheet S. The conveyor roller section 50 also has a pre-registration sensor 35 that detects the timing of the sheet S's passage.

[0025] Furthermore, the skew correction unit 55 of the sheet alignment device 10 includes a contact member 31 that corrects the skew of the sheet S by contacting the side edge of the sheet S, and three pairs of skew rollers 32a to 32c that have a conveying force corresponding to the conveying direction component of the sheet S and the width direction component of the sheet S. The skew correction unit 55 also includes a pre-cash register sensor 36 that detects the timing of the sheet S's passage.

[0026] The contact member 31 is positioned downstream of the conveyor roller pair 34d in the sheet conveying direction and on one side in the width direction perpendicular to the sheet conveying direction. The contact member 31 has a contact surface 31a that serves as a reference surface capable of contacting the edge of the sheet in the width direction.

[0027] The registration roller pair 7 is rotationally driven by a drive motor and transmission gear (not shown), and is configured to press against and separate from the sheet S by a separation drive motor and transmission gear (not shown), allowing switching between a clamped state and a release state of the sheet S. Similarly, the transport roller pairs 34a to 34d and the oblique transport roller pairs 32a to 32c are also rotationally driven and configured to press against and separate from the sheet S, allowing switching between a clamped state and a release state of the sheet S. Details of the rotation mechanism and the pressing and separating mechanisms of the transport roller pairs 34a to 34d and the oblique transport roller pairs 32a to 32c will be described later.

[0028] The registration roller pair 7 is shiftable in the W1 direction, parallel to the width direction of the sheet S shown in Figure 2, by a shift drive motor and transmission gear (not shown). The transport roller pairs 34a to 34d are arranged side by side in the transport direction. The transport roller pairs 34a to 34c have similar configurations, and the transport roller pair 34d, which is located furthest downstream in the transport direction, has a shift section 600 that allows it to move in the W2 direction, parallel to the width direction of the sheet S. Details of the shift section 600 will be described later.

[0029] The lateral register detection device 60, which acts as the detection unit, is composed of a CIS (Contact Image Sensor) and is positioned on the upstream side in the transport direction of the transport roller pair 34c, on the side where the contact member 31 is positioned relative to the center in the width direction. In other words, since the lateral register detection device 60 only needs to detect the position of one side edge of the sheet S in order to correct the position of the sheet S, it is positioned on one side in the width direction perpendicular to the sheet transport direction. The lateral register detection device 60 is configured to be able to detect the positions of the side edges of the smallest and largest sheets within the sheet sizes permitted for use in the image forming apparatus 1.

[0030] The pre-resist sensor 35 is positioned approximately in the center of the width direction, downstream of the transport roller pair 34d and upstream of the oblique transport roller pair 32a in the transport direction. The pre-resist sensor 35 is a photosensor having a light-emitting part and a light-receiving part, and detects the timing of the sheet S's passage by receiving light emitted from the light-emitting part and reflected by the sheet S with the light-receiving part.

[0031] The inclined roller pairs 32a to 32c, acting as inclined rotating bodies, are arranged side by side in the conveying direction and have similar configurations. Each of the inclined roller pairs 32a to 32c is set up so that the conveying force can be obtained from the conveying direction component of the sheet S and the width direction component which is the direction in which it abuts against the contact surface 31a, by having the rotation axis of each inclined roller pair 32a to 32c at an angle θ with respect to the contact surface 31a. The inclination of the sheet S is corrected when its side edges abut against the contact surface 31a. In other words, the inclined roller pairs 32a to 32c move the sheet S in a direction inclined with respect to the sheet conveying direction so that as it moves downstream in the sheet conveying direction, it approaches the contact surface 31a of the contact member 31 in the width direction.

[0032] The pre-register sensor 36 is positioned approximately in the center in the width direction, downstream of the oblique conveying roller pair 32c and upstream of the registration roller pair 7 in the conveying direction. The pre-register sensor 36 is a photosensor similar to the pre-register sensor 35, and detects the timing of the sheet S's passage by receiving light emitted from the light-emitting part and reflected by the sheet S with the light-receiving part.

[0033] The registration roller pair 7 has a drive roller and a driven roller, and moves in the W1 direction parallel to the width direction of the sheet S while nipping the sheet S, thereby aligning the width direction position of the toner image formed on the intermediate transfer belt 506 with that of the sheet S. After aligning the width direction position of the sheet S, the registration roller pair 7 transports the sheet S.

[0034] Next, we will describe the mechanism by which the conveyor roller pairs 34a to 34c are released from their gripping state and the nips formed on each conveyor roller pair are released. Figure 3(a) shows a cross-sectional view of the conveyor roller section 50 when the conveyor roller pairs 34a to 34c are in a gripping state, and Figure 3(b) shows a cross-sectional view of the conveyor roller section 50 when the conveyor roller pairs 34a to 34c are released from their gripping state. Note that the conveyor roller pair 34d, which is located at the downstream end of the conveying direction among the conveyor roller pairs 34a to 34c, has the shift section 600 (see Figure 2) described above, and its details will be described later. Also, as mentioned above, the conveyor roller pairs 34a to 34c have similar configurations, so we will describe the configuration of conveyor roller pair 34a and omit the explanation of the configuration common to conveyor roller pair 34a.

[0035] As shown in Figure 3(a), the transport roller pair 34a is supported by an arm member 101 that supports the driven shaft 20 when the nip is pressurized, and the arm member 101 is positioned on the stay member 18 via a pivot shaft 102 so that it can pivot. In the transport roller section 50, when switching from a clamped state to a released state, the eccentric roller 103 is rotated to press the end of the arm member 101 and rotate the nip in the release direction around the pivot shaft 102.

[0036] As shown in Figure 3(b), the conveyor roller section 50 has an eccentric roller 103, a conveyor pressure motor 104, and gear trains 105 and 106 as pressing means for pressing the arm member 101. In the conveyor roller section 50, the conveyor pressure motor 104, which acts as a stepping motor, is driven to rotate the eccentric roller 103 via the gear trains 105 and 106, thereby pressing the arm member 101. The conveyor roller section 50 uses these pressing means to separate the driven roller 14 from the driven roller 13 according to a predetermined release timing, switching to a pinch release state that releases the nip between the driven roller 13 and the driven roller 14.

[0037] Figure 4 is a perspective view of the drive unit 300a that drives the drive roller 13 of the transport roller pair 34a of the transport roller section 50. As shown in Figure 4, the drive unit 300a is driven from the pre-resist motor Mp via a pulley 302a and a belt 302b to a shaft that is integrally formed with the drive roller 13. The pre-resist motor Mp is a stepping motor, and its stopping timing and transport speed are variable in accordance with the timing at which the pre-resist sensor 35 detects the sheet S.

[0038] Figure 5(a) is a top view of the drive unit 300b that drives the drive roller 320a of the oblique feed roller pair 32a of the oblique correction unit 55. The drive roller 320a of the oblique feed roller pair 32a is positioned at an angle θ with respect to the contact surface 31a of the contact member 31, and is driven by the oblique feed drive motor Ms1 via the universal joint 321, pulley 322, and conveyor belt 323. The oblique feed drive motor Ms1 is a stepping motor, and its conveying speed and timing are variable.

[0039] Figure 5(b) is a cross-sectional view of the contact member 31 as seen from the direction of arrow E in Figure 5(a). The contact member 31 is formed from a contact surface 31a against which the side edge of the sheet S abuts, and an upper guide 31b and a lower guide 31c that restrict the vertical movement of the sheet S. The contact member 31 is made of die-cast aluminum, and the contact surface 31a is formed by machining to achieve high precision. Furthermore, the contact member 31 is subjected to Teflon® electroless nickel plating. By being formed in this way, the contact member 31 has a highly precise contact surface 31a, and the sliding properties of the contact surface 31a, the upper guide 31b, and the lower guide 31c are improved, enabling high-precision alignment of the sheet S.

[0040] Figure 6(a) is a perspective view of the pressure-contact-separation mechanism 300c of the driven roller 331a facing the driven roller 320a of the inclined roller pair 32a, and Figure 6(b) is a side view of the pressure-contact-separation mechanism 300c of the driven roller 331a. As described above, the inclined roller pairs 32a to 32c have similar configurations, so the configuration of the inclined roller pair 32a will be explained, and the configuration common to the inclined roller pair 32a will be omitted from the explanation.

[0041] As shown in Figures 6(a) and (b), the driven roller 331a is supported by a link 332 that rotatably supports the driven roller 331a, a pressure spring 335, and a pressure gear 334, and the clamping pressure (clamping pressure of the sheet S) is set by the rotation angle of the inclined pressurizing motor Mk.

[0042] Figure 7(a) shows the clamped state (nip pressurization) where the drive roller 320a and the driven roller 331a are pressed against each other. As shown in Figure 7(a), in the oblique feed roller pair 32a, the pressurization gear 334 stops rotating in the direction of arrow F in the figure, and by pulling the pressurization spring 335, the link 332 rotates around the axis 336 in the direction of arrow G in the figure. As a result, the driven roller 331a rotates in a direction that presses against the drive roller 320a, and nip pressurization is applied to the drive roller 320a.

[0043] Figure 7(b) shows the state when the drive roller 320a and the driven roller 331a are separated (nip release). As shown in Figure 7(b), the pressurizing gear 334 stops rotating in the direction of arrow H in the figure, and by pushing in link 333, link 332, which supports the driven roller 331a, rotates around axis 336 in the direction of arrow I in the figure. As a result, the driven roller 331a rotates away from the drive roller 320a, and the nip is released.

[0044] The oblique pressure motor Mka is a stepping motor, and the amount of pressure can be changed by setting the step angle. The driven rollers 331a to 331c of the oblique correction unit 55 each have their own independent oblique pressure motors Mka to Mkc. Therefore, the oblique correction unit 55 can independently set the clamping pressure of the driven rollers 331a to 331c. In addition, the oblique correction unit 55 can independently separate the driven rollers 331a to 331c from the drive rollers 320a to 320c.

[0045] <Horizontal register detection device> Next, the lateral register detection device 60 will be described using Figure 8. Figure 8 is a perspective view of the transport roller section 50 including the lateral register detection device 60. As shown in Figure 8, the lateral register detection device 60 is positioned offset from the center of the sheet S in the width direction relative to the transport direction V, which is the sheet transport direction, in the same direction as the contact member 31. The lateral register detection device 60 detects the position of the side edge of the sheet S that abuts against the contact member 31, that is, one side edge in the width direction. As a result, the lateral register detection device 60 can stably measure the relative distance between the position of the sheet S before skew correction and the position of the contact surface 31a of the contact member 31, regardless of variations in cutting in the width direction of the sheet S.

[0046] <Details of the conveyor roller 34d> Next, using Figures 9 to 11, we will describe the transport roller pair 34d located at the downstream end of the transport roller section 50 in the transport direction, and the shift section 600 that shifts the transport roller pair 34d. The transport roller pair 34d, as the first rotating body, has a drive section 800 that drives the drive roller 402 of the transport roller pair 34d, and a shift section 600 that makes the transport roller pair 34d movable in a direction W2 parallel to the width direction. The transport roller pair 34d also has a pressure release mechanism 700 that separates the driven roller 401 from the drive roller 402.

[0047] Figure 9 is a perspective view of the drive unit 800. As shown in Figure 9, in the drive unit 800, the driving force of the motor 801 fixed to the frame 201 is transmitted to the transport roller gear 412 via drive gears 801a, 802, and 803. The drive gear 803 has a tooth surface length L that is longer than the reciprocating width of the transport roller gear 412 so that the meshing does not disengage even when the transport roller gear 412 is moved back and forth by the shift unit 600.

[0048] The motor 801 in the first embodiment is composed of a stepping motor. The drive gear 801a is mounted on the motor 801 and rotates in the direction of arrow J in the figure. The drive gear 802 is rotatably mounted on the fixed shaft 201b of the frame 201 via a bearing. The drive gear 803 is rotatably mounted on the fixed shaft 201c of the frame 201 via a bearing.

[0049] Figure 10 is a perspective view of the shift unit 600. As shown in Figure 10, the shift unit 600 has a slide motor 601 that is fixed to a motor base 602 and screwed to a motor support plate 603. A pulley support plate 604 is screwed above the motor support plate 603 via the slide motor 601. Pulley bases 605 and 606 are fixed to the pulley support plate 604. A pulley shaft 607 is rotatably fixed to pulley base 605, and a pulley shaft 608 is rotatably fixed to pulley base 606. Pulleys 609 and 610 are fixed to pulley shaft 607, and a pulley 611 is fixed to pulley shaft 608. In addition, a pulley 612 is fixed to the tip of the output shaft of the slide motor 601. A timing belt 613 (see Figure 9) is stretched between pulley 609 and pulley 612, and a timing belt 614 is stretched between pulley 610 and pulley 611.

[0050] A holder 415 is rotatably supported by a bearing at the end of the drive roller 402 on the transport roller gear 412 side. A sensor flag 416 is attached to the holder 415 to detect the home position in the width direction of the driven roller 401 and drive roller 402 of the transport roller pair 34d. When the driven roller 401 and drive roller 402 of the transport roller pair 34d are in the home position, the sensor flag 416 is detected by a sensor 615 provided on the pulley support plate 604. The holder 415 is also fixed to the timing belt 614 by a stopper 616 and screws (not shown).

[0051] In this configuration, the timing belt 614 rotates when driven by the slide motor 601, and the drive roller 402 of the conveyor roller pair 34d reciprocates in a width direction perpendicular to the sheet conveying direction as the timing belt 614 rotates. In addition, the driven roller 401 of the conveyor roller pair 34d is engaged with the drive roller 402 by an engaging member (not shown), and reciprocates together with the drive roller 402 in a width direction perpendicular to the sheet conveying direction.

[0052] In the first embodiment, if the side edge of the sheet S can be detected by the horizontal register detection device 60, the slide motor 601 is driven based on the detected position of the side edge of the sheet S in the width direction, causing the transport roller pair 34d to move in the width direction. If the sheet S is transparent paper and the side edge cannot be detected by the horizontal register detection device 60, the slide motor 601 is driven based on a preset shift amount, causing the transport roller pair 34d to move in the width direction.

[0053] Thus, the shift unit 600, which acts as the first rotating body movement unit, is configured to move the pair of transport rollers 34d, which are holding the sheet, in a width direction perpendicular to the sheet transport direction. Details of the control related to the operation of the shift unit 600 will be described later.

[0054] The pressure release mechanism 700, which presses the driven roller 401 and the drive roller 402 of the transport roller pair 34d into and apart, has a pressure release shaft 701 positioned on the frame 201, as shown in Figure 11(a). The pressure release mechanism 700 also includes cams 702 and 703 (see Figure 11(b)) fixed to the pressure release shaft 701. Deep groove ball bearings 702a and 703a are press-fitted into the cams 702 and 703 at positions eccentric to their respective centers of rotation, as shown in Figure 11(b). Furthermore, as shown in Figure 11(a), a gear 702b is formed on the cam 702, and the drive of the pressure release motor 704 is transmitted via the cam 702, causing the pressure release shaft 70 to rotate.

[0055] Furthermore, the deep groove ball bearing 702a is positioned so as to be able to contact the pressure arm 405, and when the pressure release shaft 701 is rotated once, the deep groove ball bearing 702a causes the pressure arm 405 to oscillate against the biasing force of the spring 407. By oscillating the pressure arm 405 in this way, the driven roller 401 and the drive roller 402 can be brought into contact with and separated from each other once each. In addition, a pressure arm (not shown) is also provided on the side of the pressure release shaft 701 where the deep groove ball bearing 703a is provided in the axial direction. Furthermore, a sensor flag 703b is formed on the cam 703 (see Figure 11(b)). The sensor flag 703b is detected by a sensor 706 fixed to a sensor support plate 705 fixed to the frame 201, which determines the phase of the pressure release shaft 701, and the rotation of the pressure release motor 704 is controlled according to the phase of the pressure release shaft 701. Furthermore, the phases of the cams 702 and 703 are determined so that the sensor flag 703b is shielded from the sensor 706 when the driven roller 401 and the drive roller 402 of the transport roller pair 34d are in contact.

[0056] <Control configuration of the sheet matching device> Next, the control configuration of the sheet alignment device 10 will be described with reference to Figure 12. As shown in Figure 12, the operation of the sheet alignment device 10 is controlled by a controller 900 mounted on the image forming apparatus 1. The controller 900, which is an example of the control means of the first embodiment, includes a CPU 901 as a calculation means, RAM 902 and ROM 903 as storage means, and an interface (I / O) 904 for external devices or networks.

[0057] The CPU 901 performs control based on information input via the user interface, the operation unit 920, and detection signals from the pre-register sensor 35 and the pre-register sensor 36. The detection signals from the pre-register sensor 35 and the pre-register sensor 36 are input to the CPU 901 via the AD conversion units 905 and 910, respectively. The detection signal from the side register detection device 60 is also input to the CPU 901 via the AD conversion unit 60C. The CPU 901 loads and executes a program stored in the ROM 903, etc. The CPU 901 drives and controls the motor group (Ms1, Mp, 104, Mka~Mkc, 601), which are actuators of the seat alignment device 10, via drivers 906, 907, 908, 909a~909c. In other words, the CPU 901, as the control unit, is configured to control the shift unit 600 by controlling the drive of the slide motor 601.

[0058] <Registration correction by sheet alignment device> Next, we will describe the registration correction performed before the skew correction by the sheet alignment device 10.

[0059] First, we will explain the registration correction for sheets whose side edges can be detected by the lateral registration detection device 60. Figure 13(a) is a top view showing a sheet S whose side edges can be detected by the lateral registration detection device 60 being transported to the sheet alignment device 10, and (b) is a cross-sectional view of the sheet alignment device 10 in the state shown in Figure 13(a). As shown in Figures 13(a) and (b), in the sheet alignment device 10, when a sheet S being transported in the transport direction V enters the lateral registration detection device 60, the lateral registration detection device 60 detects the position of the side edge of the sheet S (side edge position). The CPU 901 (see Figure 12) calculates the amount of deviation of the detected side edge position from the detection result of the lateral registration detection device 60, based on the side edge position when the center in the width direction perpendicular to the sheet transport direction in the transport path of the sheet S coincides with the center in the width direction of the sheet S.

[0060] Figure 13(c) is a top view showing the state in which the sheet S has been transported by the transport roller pair 34d from the state shown in Figures 13(a) and (b), and (d) is a cross-sectional view of the sheet alignment device 10 in the state shown in Figure 13(c). As shown in Figures 13(c) and (d), in the sheet alignment device 10, after the sheet S reaches the transport roller pair 34d, the transport roller pair 34a to 34c separate. Based on the amount of displacement calculated above, the CPU 901 shifts the transport roller pair 34d to the shift unit 600 so that the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet S held between the transport roller pair 34d becomes a first distance (for example, 4 mm).

[0061] In this way, the sheet matching device 10 performs registration correction by shifting the sheet S in the direction of arrow W2a while transporting it in the transport direction V using the transport roller pair 34d when the type of sheet S is a type of sheet that can be detected by the lateral registration detection device 60. The type of sheet that can be detected by the lateral registration detection device 60, which is composed of CIS, constitutes the first type. In addition, the transport roller pair 34c, which is adjacent to the transport roller pair 34d and positioned upstream of the transport roller pair 34d in the sheet transport direction, constitutes the second rotating body.

[0062] Next, registration correction for sheets whose side edges cannot be detected by the lateral registration detection device 60 will be explained. As mentioned above, the lateral registration detection device 60 is composed of CIS and is configured in such a way that it cannot detect the side edges of a sheet when the sheet type is transparent paper such as OHP film.

[0063] Therefore, if the sheet alignment device 10 is configured to perform registration correction using the detection results of the horizontal registration detection device 60 even if the sheet S is transparent paper, the amount of displacement will not be calculated even when the sheet S reaches the transport roller pair 34d, and it will not be able to shift. As a result, as shown in Figure 14, if the sheet S is transported while positioned closer to the contact member 31 than the center in the width direction, there is a risk that the leading edge of the sheet S will collide with the contact member 31.

[0064] Based on these considerations, the sheet alignment device 10 of the first embodiment is configured to shift in the direction of arrow W2a by a predetermined shift amount X (for example, 6 mm) as shown in Figure 15 when information indicating that it is transparent paper is input from the operation unit 920 (see Figure 12).

[0065] The sheet alignment device 10 performs registration correction by shifting by a predetermined shift amount X in the direction of arrow W2a, regardless of the detection result of the lateral registration detection device 60, after the pre-registration sensor 35 detects the sheet S and the transport roller pair 34a to 34c separate. In other words, the CPU 901 causes the shift unit 600 to shift the transport roller pair 34d so that the sheet S, which is held between the transport roller pair 34d, moves by a predetermined shift amount X as a second distance to the other side, away from the contact member 31 located on one side in the width direction.

[0066] Thus, when the sheet alignment device 10 is a sheet of a type that has a transparency that cannot be detected by the horizontal registration detection device 60, it performs registration correction by shifting the sheet S in the direction of arrow W2a while transporting it in the transport direction V using the transport roller pair 34d. This type of sheet that has a transparency that cannot be detected by the horizontal registration detection device 60, which is composed of CIS, constitutes the second type.

[0067] In the sheet alignment device 10, when the type of sheet S is detectable by the lateral registration detection device 60, the distance from the contact surface 31a to the side edge of sheet S is corrected to a first distance by registration correction. Also, in the sheet alignment device 10, when the type of sheet S is not detectable by the lateral registration detection device 60, the sheet S is corrected by registration correction to move to a second distance in the other direction in the width direction away from the contact member 31. In the sheet alignment device 10 of the first embodiment, the second distance is longer than the first distance.

[0068] With this configuration, the sheet matching device 10 can more reliably avoid collisions between the leading edge of the sheet S in the transport direction and the contact member 31 by performing registration correction when the type of sheet S is one that cannot be detected by the lateral registration detection device 60.

[0069] The second distance is set based on the minimum widthwise size of the sheet that the image forming apparatus 1 can transport and the configuration from paper feeding to registration correction. Specifically, even when the sheet is shifted by the second distance in the most scattered state within the transportable range of the image forming apparatus 1, the distance is such that the sheet is not positioned on the other side in the widthwise direction beyond the nip of the oblique feed roller pair 32a to 32c.

[0070] Therefore, even if the sheet alignment device 10 performs registration correction by shifting the sheet S by a second distance in the direction away from the contact member 31 when the type of sheet S is a type that cannot be detected by the lateral registration detection device 60, it can still perform oblique correction by the oblique feed roller pair 32a to 32c.

[0071] Furthermore, in the sheet alignment device 10, registration correction is performed by the transport roller pair 34d after the transport roller pair 34a to 34c have separated, so that registration correction can be performed without interference from the transport roller pair 34a to 34c.

[0072] <Sclique correction by sheet alignment device> Figure 16(a) is a top view showing the sheet alignment device 10 when performing skew correction on a registration-corrected sheet S, and (b) is a cross-sectional view of the sheet alignment device 10 in the state shown in Figure 16(a). As shown in Figures 16(a) and (b), in the sheet alignment device 10, the sheet S is conveyed in the direction of arrow K in the figure by the skew conveying roller pair 32a to 32c, and the side edge of the sheet S is brought into contact with the contact surface 31a of the contact member 31. In the sheet alignment device 10, when skew correction is performed, the skew conveying roller pair 32a to 32c are pressed together, and the conveying roller pair 34a to 34d are separated.

[0073] Therefore, in the sheet alignment device 10, after the transport roller pair 34a to 34d separates, the diagonal correction is performed by the diagonal transport roller pair 32a to 32c, so that the diagonal correction can be performed without interference from the transport roller pair 34a to 34d.

[0074] <Shifting by registration roller pairs> Figure 17(a) is a top view showing the sheet alignment device 10 when the skew-corrected sheet S is transported to the secondary transfer section, and (b) is a cross-sectional view of the sheet alignment device 10 in the state shown in Figure 17(a). As shown in Figures 17(a) and (b), in the sheet alignment device 10, the sheet S is shifted in the direction of arrow W1a in the figure by the registration roller pair 7 so that the widthwise position of the sheet S matches the widthwise position of the image to be transferred in the secondary transfer section. In other words, the registration roller pair 7 shifts the sheet S in the direction of arrow W1a while transporting it in the transport direction V so that it matches the widthwise position of the image formed in the image forming section 513 (see Figure 1).

[0075] As a result, the sheet alignment device 10 can correct the position of the skew-corrected sheet S in the width direction to match the position of the image formed by the image forming unit 513 in the width direction, and form an image on the sheet S.

[0076] Furthermore, in the sheet alignment device 10, the widthwise position of the sheet S is corrected by the registration roller pair 7 after the diagonal feed roller pair 32a to 32c have separated, thereby correcting the widthwise position without interference from the diagonal feed roller pair 32a to 32c.

[0077] This registration roller pair 7 is positioned downstream of the oblique feed roller pair 32a to 32c in the sheet transport direction, is movable in the width direction while holding the sheet S, and constitutes a position-changing section that can change the position of the end of the sheet S in the width direction.

[0078] <Control processing in sheet matching device> Next, we will describe the control processing performed by the CPU 901 when the sheet alignment device 10 performs registration correction and skew correction. Figures 18 and 19 are flowcharts showing the control processing related to registration correction and skew correction by the sheet alignment device 10. Based on the input of sheet information from the operation unit 920 and the start of the job, the CPU 901 starts the control processing related to registration correction and skew correction by the sheet alignment device 10.

[0079] First, the CPU 901 acquires sheet information (sheet information) input from the operation unit 920 (S1). In this process, the CPU 901 acquires sheet information such as basis weight, size, number of sheets, and type of sheet input from the operation unit 920. Among the sheet information, the type information includes information indicating whether it is plain office paper, coated paper, transparent paper such as OHP film, etc. The CPU 901 also acquires the number of sheets to be fed into the sheet alignment device 10 in the started job from the number of sheets information included in the sheet information, and sets this as the initial value of the stored value, which is the value stored in the paper feed counter.

[0080] Next, the CPU 901 determines the clamping pressure of the diagonal feed roller pairs 32a to 32c (S2). In this process, the CPU 901 obtains table data from the ROM 903 that associates the clamping pressure with each pre-set sheet type based on the sheet information obtained in step S1, and determines the clamping pressure of the diagonal feed roller pairs 32a to 32c.

[0081] Next, the image forming apparatus 1 starts forming an image using the image forming unit 513 (S3). The CPU 901 starts counting the paper feed start delay based on the timing when the processing in step S3 begins (S4). The paper feed start delay is the difference between the time elapsed from when the paper is formed on the intermediate transfer belt 506 until it is transported to the secondary transfer unit 40, and the time elapsed from when the sheet is transported from the sheet feeding device 51 to the secondary transfer unit 40. The CPU 901 sets a value to be counted as the paper feed start delay corresponding to the image formed in the processing of step S3 by the image forming apparatus 1, and starts counting.

[0082] When the count for the paper feed start delay reaches the set value, the CPU 901 starts feeding sheets from the sheet feeder 51 (S5). Next, the CPU 901 determines whether the sheet being fed from the sheet feeder 51 is a sheet whose side edge position can be detected by the side register detection device 60 (S6). In this process, the CPU 901 determines from the sheet information obtained in step S1 whether the sheet being fed is transparent paper such as an OHP sheet.

[0083] In step S6, if it is determined that the sheet is opaque paper and can be detected by the horizontal register detection device 60 (Yes), the CPU 901 causes the horizontal register detection device 60 to detect the side edge position of the sheet when the sheet reaches the horizontal register detection device 60 (S7). In this process, the CPU 901 causes the horizontal register detection device 60 to detect the side edge position of the sheet. Next, the CPU 901 calculates the amount of sheet shift (S8). In this process, the CPU 901 calculates the amount of deviation of the detected side edge position from the detection result of the horizontal register detection device 60, relative to the side edge position when the center in the width direction perpendicular to the sheet transport direction in the sheet transport path coincides with the center in the width direction of the sheet S. Then, the CPU 901 determines the calculated amount of deviation as the amount of shift to shift the transport roller pair 34d so that the center in the width direction of the sheet S coincides with the center in the width direction of the sheet transport path.

[0084] In the process of step S6, if it is determined that the sheet is transparent paper and cannot be detected by the side register detection device 60 (No), the CPU 901 decides not to perform side edge detection of the sheet by the side register detection device 60 (S9).

[0085] After executing steps S8 and S9, the CPU 901 determines whether the pre-registration sensor 35 has been turned ON (S10). In this process, the CPU 901 determines from the signal of the pre-registration sensor 35 whether the sheet whose side edge position has been detected by the lateral registration detection device 60 has reached the pre-registration sensor 35.

[0086] In step S10, if it is determined that the pre-registration sensor 35 is not ON (No), the CPU 901 determines that a paper jam has occurred because the sheet was not transported to the pre-registration sensor 35 at the time it should have been transported. The CPU 901 displays on the operation unit 920 that a paper jam has occurred (S11) and terminates the control processing related to registration correction and skew correction.

[0087] On the other hand, if the CPU 901 determines that the pre-registration sensor 35 is ON (Yes), the CPU 901 starts counting the release delay of the transport roller pair 34a to 34c (S12). At the time when the process in step S12 is executed, the sheet alignment device 10 has reached the pre-registration sensor 35, which is located downstream in the transport direction from the transport roller pair 34d, and registration correction by the transport roller pair 34d is possible. Therefore, in the process of step S12, the CPU 901 sets a release delay value, which is the time that elapses from the gripped state to the released state of the transport roller pair 34a to 34c, and starts counting.

[0088] At the time the process in step S12 is executed, the CPU 901 separates the drive roller 13 and driven roller 14 of the transport roller pair 34a to 34c (S13). As a result, in the sheet alignment device 10, the sheet is held between the transport roller pair 34d and not between the transport roller pair 34a to 34c.

[0089] When the process in step S13 is executed and the release delay count reaches the set value, the CPU 901 determines whether the sheet fed from the sheet feeder 51 is a sheet whose side edge position can be detected by the side register detection device 60 (S14). In this process, the CPU 901 performs a process that is substantially the same as the process in step S6.

[0090] In step S14, if it is determined that the sheet is opaque paper and can be detected by the horizontal registration detection device 60 (Yes), the CPU 901 shifts the transport roller pair 34d by a shift amount corresponding to the detection result of the horizontal registration detection device 60 (S15). In this process, the CPU 901 shifts the transport roller pair 34d by the shift amount calculated in step S8 and performs registration correction to correct the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet to a position where the distance is a first distance.

[0091] With this configuration, when the sheet alignment device 10 of the first embodiment is transporting a sheet of a type detectable by the lateral registration detection device 60, it can reduce the distance between the side edge of the sheet and the contact surface 31a of the contact member 31 to a first distance by registration correction. As a result, the sheet alignment device 10 can reduce variations in the sheet transport speed during the skew correction performed after registration correction, and reduce the impact of skew correction on productivity.

[0092] On the other hand, in step S14, if it is determined that the sheet is transparent paper and cannot be detected by the horizontal register detection device 60 (No), the CPU 901 shifts the transport roller pair 34d by a predetermined shift amount X (see Figure 15) (S16). In this process, the CPU 901 shifts the transport roller pair 34d by a predetermined shift amount X that does not depend on the detection result of the horizontal register detection device 60, and performs registration correction to correct so that the sheet moves a second distance away from the contact member 31.

[0093] With this configuration, the sheet alignment device 10 of the first embodiment can avoid collision between the leading edge of the sheet in the transport direction and the contact member 31 by registration correction when transporting a type of sheet that cannot be detected by the lateral registration detection device 60. Furthermore, the sheet alignment device 10 can correct the skew of the sheet by performing registration correction not only for sheets that can be detected by the lateral registration detection device 60, but also for sheets that cannot be detected, thus stably correcting the skew of the sheet regardless of the type of sheet.

[0094] After executing steps S15 and S16, the CPU 901 starts counting the pressure delay of the diagonal feed roller pair 32a to 32c (S17). At the time step S17 is executed, the sheet alignment device 10 has completed the sheet registration correction. Also, in the sheet alignment device 10, the diagonal feed roller pair 32a to 32c is in a released grip state to avoid interference between the diagonal feed roller pair 32a to 32c and the registration correction by the transport roller pair 34d. Therefore, in step S17, the CPU 901 sets a value for the pressure delay, which is the time elapsed from the released grip state to the grip state of the diagonal feed roller pair 32a to 32c, and starts counting.

[0095] At the time that step S17 is executed, the CPU 901 presses the drive rollers 320a to 320c and the driven rollers 331a to 331c of the oblique conveying roller pair 32a to 32c together (S18). Next, the CPU 901 starts counting the release delay, which is the time it takes for the conveying roller pair 34d to go from being gripped to being released (S19), and separates the drive roller 402 and the driven roller 401 of the conveying roller pair 34d (S20).

[0096] As a result of the execution of steps S17 to S20, the sheet alignment device 10 is in a state where the sheet is not gripped by the transport roller pair 34d, and the sheet can be gripped and transported by the oblique transport roller pair 32a to 32c. The sheet alignment device 10 corrects the skew of the sheet as it is transported by gripping and transporting the sheet with the oblique transport roller pair 32a to 32c, while bringing the side edge of the sheet into contact with the contact surface 31a of the contact member 31.

[0097] Next, the CPU 901 determines whether the pre-cash register sensor 36 has been turned ON (S21). In this process, the CPU 901 determines from the signal of the pre-cash register sensor 36 whether the sheet, which has been corrected for skew by the skew feed roller pairs 32a to 32c, has reached the pre-cash register sensor 36.

[0098] In step S21, if it is determined that the pre-register sensor 36 is not ON (No), the CPU 901 determines that a paper jam has occurred because the sheet was not transported to the pre-register sensor 36 at the time it should have been transported. The CPU 901 displays on the operation unit 920 that a paper jam has occurred (S11) and terminates the control processing related to registration correction and skew correction.

[0099] On the other hand, if the CPU 901 determines that the pre-register sensor 36 is ON (Yes), the CPU 901 starts counting the release delay for the diagonal feed roller pair 32a to 32c (S22). At the time the processing in step S22 is executed, the sheet alignment device 10 has reached the pre-register sensor 36, which is located downstream in the transport direction from the diagonal feed roller pair 32a to 32c, and the sheet can be transported and shifted by the registration roller pair 7. Therefore, in the processing in step S22, the CPU 901 sets a release delay value, which is the time that elapses from the gripped state to the released state of the diagonal feed roller pair 32a to 32c, and starts counting.

[0100] At the time the process in step S22 is executed, the CPU 901 separates the drive rollers 320a to 320c and the driven rollers 331a to 331c of the oblique feed roller pair 32a to 32c (S23). As a result, in the sheet alignment device 10, the sheet is held between the registration roller pair 7 and not between the oblique feed roller pair 32a to 32c.

[0101] Next, the CPU 901 shifts the widthwise position of the sheet using the registration roller pair 7 so that the widthwise position of the sheet matches the widthwise position of the image transferred in the secondary transfer section (S24). In this process, the CPU 901 shifts the widthwise position of the sheet held by the registration roller pair 7 to a position corresponding to the center position in the widthwise direction of the image formed by the image forming section 513.

[0102] Next, the CPU 901 subtracts 1 from the number of sheets counted by the paper feed counter (S25). In this process, the CPU 901 subtracts "1", the value corresponding to one sheet, from the stored value of the paper feed counter, because registration correction, skew correction, and widthwise position shift by the registration roller pair 7 for one sheet have been completed.

[0103] Next, the CPU 901 determines whether the stored value of the paper feed counter is 0 (S26). If it determines that the stored value of the paper feed counter is not 0 (No), the CPU 901 returns to step S3 to perform registration correction and skew correction on the next sheet to be transported in the current job. On the other hand, if it determines that the stored value of the paper feed counter is 0 (Yes), the CPU 901 determines that the registration correction and skew correction on the sheet in the current job have been completed and terminates the control processing related to registration correction and skew correction.

[0104] <Summary of the First Embodiment> As described above, the sheet alignment device 10 of the first embodiment performs registration correction based on the detection result of the lateral registration detection device 60 when the sheet being conveyed is of a type that can be detected by the lateral registration detection device 60. The sheet alignment device 10 shifts the conveying roller pair 34d by a shift amount based on the detection result and performs registration correction to correct the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet to a position where the distance is a first distance.

[0105] With this configuration, the sheet alignment device 10 of the first embodiment can sufficiently reduce the distance between the side edge of the sheet and the contact surface 31a of the contact member 31 by registration correction when transporting sheets of a type detectable by the lateral registration detection device 60. As a result, the sheet alignment device 10 can reduce variations in the sheet transport speed during skew correction performed after registration correction, and reduce the impact of skew correction on productivity.

[0106] Furthermore, the sheet alignment device 10 performs registration correction by shifting the transport roller pair 34d by a predetermined shift amount X when the transported sheet is of a type that cannot be detected by the lateral registration detection device 60. The sheet alignment device 10 shifts the transport roller pair 34d by a predetermined shift amount X and performs registration correction to correct it to move a second distance in the other direction in the width direction away from the contact member 31. After performing registration correction, the sheet alignment device 10 transports the sheet by the oblique transport roller pairs 32a to 32c so that the side edge of the sheet follows the contact surface 31a of the contact member 31, and performs sheet skew correction.

[0107] With this configuration, the sheet alignment device 10 of the first embodiment can avoid collision between the leading edge of the sheet in the transport direction and the contact member 31 by registration correction when transporting a type of sheet that cannot be detected by the lateral registration detection device 60. Furthermore, the sheet alignment device 10 can correct the skew of the sheet by performing registration correction not only for sheets that can be detected by the lateral registration detection device 60, but also for sheets that cannot be detected, thus stably correcting the skew of the sheet regardless of the type of sheet.

[0108] [Second Embodiment] Next, the sheet alignment device 10 of the second embodiment will be described. The sheet alignment device 10 of the second embodiment is configured to shift the contact member 31 in the width direction by a predetermined shift amount when performing registration correction for sheets whose side edges cannot be detected by the lateral registration detection device 60. In this respect, the sheet alignment device 10 of the second embodiment differs from the first embodiment described above. The other configurations are the same as those of the first embodiment, so components common to the first embodiment are denoted by the same reference numerals, and control processes common to the first embodiment are denoted by the same step numbers and their descriptions are omitted.

[0109] <Registration correction by sheet alignment device> Figure 20 is a top view showing the state in the sheet alignment device 10 of the second embodiment, where transparent paper whose side edge position cannot be detected by the lateral registration detection device 60 is transported as a sheet, and registration correction is performed. As shown in Figure 20, the sheet alignment device 10 has a shift unit 650 that shifts the contact member 31 in the width direction perpendicular to the sheet transport direction. The shift unit 650, which is the contact member moving part, is configured to be shiftable in a direction W3 parallel to the width direction shown in Figure 20 by a shift drive motor and transmission gear (not shown).

[0110] The CPU 901 performs registration correction using the transport roller pair 34d, similar to the first embodiment, when the type of sheet being transported is a type of sheet detectable by the lateral registration detection device 60. In the sheet alignment device 10, the transport roller pair 34d is shifted by the shift unit 600 so that the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet S that can be detected by the lateral registration detection device 60, which is held between the transport roller pair 34d, becomes a first distance (for example, 4 mm).

[0111] Next, registration correction for sheets whose side edges cannot be detected by the lateral registration detection device 60 will be described. The sheet alignment device 10 of the second embodiment is configured to shift the contact member 31 in the direction of arrow W3a by a predetermined shift amount Y (for example, 6 mm) when information indicating that it is transparent paper is input from the operation unit 920 (see Figure 12).

[0112] The sheet alignment device 10 performs registration correction by shifting the contact member 31 by a predetermined shift amount Y in the direction of arrow W3a, regardless of the detection result of the lateral registration detection device 60, while the transport roller pair 34a to 34d are gripping the sheet. In other words, the CPU 901 shifts the contact member 31 in the shift section 650 so that it moves by a predetermined shift amount Y as a second distance in one direction in the width direction away from the sheet S gripped by the transport roller pair 34a to 34d.

[0113] The sheet alignment device 10 performs registration correction to shift the sheet S in the direction of arrow W3a before it reaches the contact member 31 when the sheet S is of a type that has transparency that cannot be detected by the horizontal registration detection device 60.

[0114] With this configuration, the sheet alignment device 10 can perform registration correction without performing control to release the gripping of the transport roller pairs 34a to 34d before registration correction, even when the type of sheet S is one that cannot be detected by the lateral registration detection device 60. As a result, when the type of sheet S is one that cannot be detected by the lateral registration detection device 60, the sheet alignment device 10 can avoid collision between the leading edge of the sheet S in the transport direction and the contact member 31 by performing registration correction consisting of a simple sequence.

[0115] <Control processing in sheet matching device> Next, we will describe the control processing performed by the CPU 901 when the sheet alignment device 10 performs registration correction and skew correction. Figures 21 and 22 are flowcharts showing the control processing related to registration correction and skew correction by the sheet alignment device 10. Based on the input of sheet information from the operation unit 920 and the start of the job, the CPU 901 starts the control processing related to registration correction and skew correction by the sheet alignment device 10.

[0116] After executing the process in step S5, the CPU 901 determines whether the sheet fed from the sheet feeding device 51 is a sheet whose side edge position can be detected by the side register detection device 60 (S6). In this process, the CPU 901 determines from the sheet information obtained in the process in step S1 whether the sheet to be fed is transparent paper such as an OHP sheet.

[0117] In step S6, it is determined that the sheet is opaque paper and can be detected by the side register detection device 60 (Yes). After executing steps S7 and S8, the CPU 901 determines whether the pre-register sensor 35 has been turned ON or not (S10). In this process, the CPU 901 determines from the signal of the pre-register sensor 35 whether the sheet whose side edge position has been detected by the side register detection device 60 has reached the pre-register sensor 35.

[0118] In step S10, if it is determined that the pre-registration sensor 35 is not ON (No), the CPU 901 determines that a paper jam has occurred because the sheet was not transported to the pre-registration sensor 35 at the time it should have been transported. The CPU 901 displays on the operation unit 920 that a paper jam has occurred (S11) and terminates the control processing related to registration correction and skew correction.

[0119] On the other hand, if it is determined that the pre-registration sensor 35 is ON (Yes), the CPU 901 executes the processes in steps S12 and S13, so that the sheet is held by the transport roller pair 34d and not held by the transport roller pairs 34a to 34c. After executing the process in step S13, the CPU 901 of the second embodiment shifts the transport roller pair 34d by a shift amount corresponding to the detection result of the horizontal register detection device 60 (S15). In other words, after executing the process in step S13, the CPU 901 of the second embodiment executes the process in step S15 without executing the process in step S14, which determines whether or not the sheet being fed is a sheet whose side edge position can be detected by the horizontal register detection device 60.

[0120] In step S15, the CPU 901 shifts the transport roller pair 34d by the shift amount calculated in step S8 and performs registration correction to correct the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet to a position where the distance is a first distance. In the second embodiment, the CPU 901 shifts the transport roller pair 34d to the shift section 600 so that the first distance is, for example, 4 mm.

[0121] With this configuration, the sheet alignment device 10 of the second embodiment can, when transporting a sheet of a type detectable by the lateral registration detection device 60, reduce the distance between the side edge of the sheet and the contact surface 31a of the contact member 31 to a first distance by registration correction. As a result, the sheet alignment device 10 can reduce variations in the sheet transport speed during the skew correction performed after registration correction, and reduce the impact of skew correction on productivity.

[0122] After executing the process in step S15, the CPU 901 executes the processes in steps S17 to S20, gripping and conveying the sheet with the diagonal conveying roller pairs 32a to 32c, and correcting the sheet's skew by bringing the side edge of the sheet into contact with the contact surface 31a of the contact member 31.

[0123] On the other hand, in the process of step S6, if it is determined that the sheet is transparent paper and cannot be detected by the horizontal registration detection device 60 (No), the CPU 901 decides not to perform detection of the side edge position of the sheet by the horizontal registration detection device 60 (S9). Next, the CPU 901 shifts the contact member 31 by a predetermined shift amount Y (see Figure 20) (S41). In this process, the CPU 901 shifts the contact member 31 in the width direction away from the sheet by a predetermined shift amount Y, which is independent of the detection result of the horizontal registration detection device 60. By shifting the contact member 31, the CPU 901 corrects the relative position of the sheet and the contact member 31 in the width direction and performs registration correction to avoid collision between the leading edge of the sheet and the contact member 31. In the second embodiment, the predetermined shift amount Y is set to, for example, 6 mm, and by being shifted by the predetermined shift amount Y, the contact member 31 moves a second distance (for example, 6 mm).

[0124] In other words, in the sheet alignment device 10 of the second embodiment, when the sheet is transparent paper and cannot be detected by the horizontal register detection device 60, the contact member 31 is configured to shift by a second distance while the transport roller pair 34a to 34d are gripping and transporting the sheet.

[0125] With this configuration, the sheet alignment device 10 of the second embodiment can perform registration correction without performing a process to release the gripping of the transport roller pairs 34a to 34d before registration correction when the sheet is transparent paper. As a result, the sheet alignment device 10 can avoid collision between the leading edge of the sheet S in the transport direction and the contact member 31 by performing registration correction consisting of a simple sequence when the type of sheet S is a type that cannot be detected by the horizontal registration detection device 60.

[0126] After executing the process in step S42, the CPU 901 determines whether the pre-registration sensor 35 has been turned ON or not (S43). In this process, the CPU 901 determines, in substantially the same manner as in the process in step S10, whether the sheet whose side edge position has been detected by the lateral registration detection device 60 has reached the pre-registration sensor 35 based on the signal from the pre-registration sensor 35.

[0127] In step S43, if it is determined that the pre-registration sensor 35 is not ON (No), the CPU 901 determines that a paper jam has occurred because the sheet has not been transported to the pre-registration sensor 35 at the time it should have been transported. The CPU 901 displays on the operation unit 920 that a paper jam has occurred (S11) and terminates the control processing related to registration correction and skew correction.

[0128] On the other hand, if the pre-registration sensor 35 is determined to be ON (Yes), the CPU 901 starts counting the pressure delay of the diagonal feed roller pair 32a to 32c (S43). At the time the processing in step S43 is executed, the sheet alignment device 10 has completed the sheet registration correction. Also, in the sheet alignment device 10, the diagonal feed roller pair 32a to 32c is in a released grip state in order to avoid interference between the diagonal feed roller pair 32a to 32c and the sheet gripping and transport by the transport roller pair 34a to 34d. Therefore, in the processing in step S43, the CPU 901 sets a value for the pressure delay, which is the time that elapses from the released grip state to the gripped state of the diagonal feed roller pair 32a to 32c, and starts counting.

[0129] At the time the process in step S43 is executed, the CPU 901 presses the drive rollers 320a to 320c and the driven rollers 331a to 331c of the oblique conveying roller pair 32a to 32c together (S44). Next, the CPU 901 starts counting the release delay, which is the time it takes for the conveying roller pair 34a to 34d to go from being gripped to being released (S45). Then, the CPU 901 separates the drive roller 13 and driven roller 14 of the conveying roller pair 34a to 34c from the drive roller 402 and driven roller 401 of the conveying roller pair 34d (S46).

[0130] As a result of the processing in steps S43 to S46, the sheet alignment device 10 is in a state where the sheet is not gripped by the transport roller pair 34a to 34d, and the sheet can be gripped and transported by the oblique transport roller pair 32a to 32c. The sheet alignment device 10 corrects the skew of the sheet as it is transported by gripping and transporting the sheet with the oblique transport roller pair 32a to 32c, while bringing the side edge of the sheet into contact with the contact surface 31a of the contact member 31.

[0131] After executing the processes in steps S20 and S46, the CPU 901 executes the processes in steps S21 to S26, similar to the control processes when performing registration correction and skew correction in the first embodiment. In the process of step S26, if the CPU 901 determines that the stored value of the paper feed counter is not 0 (No), it returns to step S3 to perform registration correction and skew correction on the next sheet to be transported in the current job. On the other hand, if the CPU 901 determines that the stored value of the paper feed counter is 0 (Yes), it determines that the registration correction and skew correction on the sheet in the current job has been completed and terminates the control processes related to registration correction and skew correction.

[0132] <Summary of the second embodiment> As described above, the sheet alignment device 10 of the second embodiment performs registration correction based on the detection result of the lateral registration detection device 60 when the sheet being conveyed is of a type that can be detected by the lateral registration detection device 60. The sheet alignment device 10 shifts the conveying roller pair 34d by a shift amount based on the detection result and performs registration correction to correct the distance from the contact surface 31a of the contact member 31 to the side edge of the sheet to a position where the distance is a first distance.

[0133] With this configuration, the sheet alignment device 10 of the second embodiment can sufficiently reduce the distance between the side edge of the sheet and the contact surface 31a of the contact member 31 by registration correction when transporting a sheet of a type detectable by the lateral registration detection device 60. As a result, the sheet alignment device 10 can reduce variations in the sheet transport speed during the skew correction performed after registration correction, and reduce the impact of skew correction on productivity.

[0134] Furthermore, the sheet alignment device 10 performs registration correction by shifting the contact member 31 by a predetermined shift amount Y when the sheet being transported is of a type that cannot be detected by the lateral registration detection device 60. The sheet alignment device 10 shifts the contact member 31 by a predetermined shift amount Y and performs registration correction to correct it to move a second distance in one direction in the width direction away from the sheet S held between the transport roller pair 34a to 34d.

[0135] With this configuration, the sheet alignment device 10 of the second embodiment can perform registration correction without performing a process to release the gripping of the transport roller pairs 34a to 34d before registration correction when the sheet is transparent paper. As a result, the sheet alignment device 10 can avoid collision between the leading edge of the sheet S in the transport direction and the contact member 31 by performing registration correction consisting of a simple sequence when the type of sheet S is a type that cannot be detected by the horizontal registration detection device 60.

[0136] After performing registration correction, the sheet alignment device 10 conveys the sheet using the oblique feed roller pair 32a to 32c so that the side edge of the sheet conforms to the contact surface 31a of the contact member 31, thereby performing sheet skew correction.

[0137] Thus, the sheet alignment device 10 can correct the skew of sheets by performing registration correction not only on sheets of a type that can be detected by the horizontal registration detection device 60, but also on sheets of a type that cannot be detected, and can stably correct the skew of sheets regardless of the type of sheet.

[0138] [Other embodiments] In the second embodiment, the sheet alignment device 10 performs registration correction using the transport roller pair 34d when the sheet type is a sheet of a type detectable by the lateral registration detection device 60, but is not limited to this. The sheet alignment device 10 may be configured to perform registration correction by shifting the contact member 31 when the sheet type is a sheet of a type detectable by the lateral registration detection device 60. Based on the detection result of the lateral registration detection device 60, the sheet alignment device 10 moves the contact member 31 to the shift unit 650 so that the distance from the contact surface 31a to one end in the width direction of the sheet held between the transport roller pair 34a to 34d becomes a first distance.

[0139] With this configuration, the sheet alignment device 10 can perform registration correction regardless of the sheet type by moving the contact member 31 using the shift unit 650, without providing a configuration for registration correction on the transport roller pair 34d. As a result, the sheet alignment device 10 can reduce the number of parts used for registration correction and can stably correct the sheet's skew regardless of the sheet type.

[0140] Furthermore, in the first and second embodiments, the oblique correction unit 55 has oblique feed roller pairs 32a to 32c that are each inclined at an angle θ with respect to the contact surface 31a, but is not limited thereto. The oblique correction unit 55 may be configured such that each of the multiple oblique feed roller pairs is inclined at a different angle with respect to the contact surface 31a. Specifically, the oblique correction unit 55 may be configured such that the first oblique feed roller pair is inclined at an angle α with respect to the contact surface, and the second oblique feed roller pair is inclined at an angle β with respect to the contact surface. Alternatively, the oblique correction unit 55 may be configured such that the third oblique feed roller pair is inclined at an angle γ with respect to the contact surface.

[0141] Furthermore, in the first and second embodiments, the diagonal correction unit 55 rotates each drive roller of the diagonal roller pair 32a to 32c by transmitting the driving force of the diagonal drive motor Ms1 via the pulley 322 and the conveyor belt 323, but is not limited to this. The diagonal correction unit 55 may be configured to supply driving force to each drive roller of the diagonal roller pair 32a to 32c from different drive motors.

[0142] Furthermore, in the first and second embodiments, the sheet alignment device 10 is provided with four pairs of conveying rollers in the conveying roller section 50 and three pairs of oblique conveying rollers in the oblique correction section 55, but the number of these roller pairs is not limited.

[0143] Furthermore, in the first and second embodiments, the sheet alignment device 10 is configured to use a sheet of a type that has a transparency that prevents the horizontal register detection device 60 from detecting the position of the sheet's edge in the width direction, as the second type of sheet, but it is not limited to this. The sheet alignment device 10 may be configured to use pre-set options for the first type and the second type, respectively. In other words, when the sheet is of the second type, the sheet alignment device 10 may be configured to shift the transport roller pair 34d or the contact member 31 by a pre-set shift amount regardless of the sheet's transparency.

[0144] Furthermore, in the first and second embodiments, the sheet alignment device 10 is configured to determine that the sheet is of type 2 by acquiring information indicating that it is transparent paper input from the operation unit 920, but it is not limited to this. The sheet alignment device 10 may be configured to determine that the sheet is of type 2 when, for example, the leading edge of the sheet is detected by the pre-registration sensor 35 and the position of the side edge of the sheet is not detected by the side-registration detection device 60.

[0145] Furthermore, although the sheet alignment device 10 is configured such that the first distance in the first embodiment and the first distance in the second embodiment are both 4 mm, it is not limited to this, and the first distance may be determined from any distance that is predetermined.

[0146] Furthermore, the sheet alignment device 10 is configured such that the first distance in the first embodiment and the first distance in the second embodiment are both 4 mm, but it is not limited to this, and the first distance may be set from any predetermined distance. Also, the sheet alignment device 10 is configured such that the second distance in the first embodiment and the second distance in the second embodiment are both 6 mm, but it is not limited to this, and the second distance may be set from any predetermined distance.

[0147] Furthermore, in the first and second embodiments, the seat alignment device 10 is set so that the second distance is longer than the first distance, but it is not limited to this, and the second distance and the first distance may be the same, or the second distance may be shorter than the first distance.

[0148] The disclosures of the first and second embodiments include the following configurations.

[0149] (Composition 1) A first rotating body that grips and transports the sheet, A first rotating body moving unit moves the first rotating body, which is holding the sheet, in a width direction perpendicular to the sheet transport direction, A contact member is positioned downstream of the first rotating body in the sheet transport direction and on one side in the width direction, extending along the sheet transport direction and having a contact surface capable of contacting the end of the sheet in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system comprises a control unit for controlling the first rotating body movement unit, The control unit, When the sheet being transported is of type 1, the first rotating body is moved to the first rotating body moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When the sheet being transported is of a second type different from the first type, the first rotating body is moved to the first rotating body moving unit such that the sheet held by the first rotating body moves a second distance in the other direction in the width direction. A sheet conveying device characterized by the following features.

[0150] (Configuration 2) The first type of sheet is a sheet capable of detecting the position of the end in the width direction of the sheet being transported by the detection unit, The second type of sheet is a sheet having transparency that makes it impossible to detect the position of the end of the sheet in the width direction when it is transported by the detection unit. A sheet conveying device according to configuration 1, characterized by the features described above.

[0151] (Composition 3) The second distance is longer than the first distance. A sheet conveying device according to configuration 1 or 2, characterized by the above.

[0152] (Composition 4) The sheet conveying direction includes a second rotating body which is adjacent to the first rotating body and positioned upstream of the first rotating body, When the control unit moves the first rotating body to the first rotating body moving unit, the second rotating body is separated from the seat. A sheet conveying device according to any one of configurations 1 to 3, characterized by the above.

[0153] (Composition 5) When the sheet is being transported by the aforementioned inclined rotating body, the first rotating body is in a state separated from the sheet. A sheet conveying device according to any one of configurations 1 to 4, characterized by the above.

[0154] (Composition 6) Displaced downstream of the inclined rotating body in the sheet transport direction, it is movable in the width direction while holding the sheet, and has a position changing part that can change the position of the end of the sheet in the width direction, When the position-changing unit changes the position of the end of the sheet in the width direction, the oblique rotating body is in a state separated from the sheet. A sheet conveying device according to any one of configurations 1 to 5, characterized by the above.

[0155] (Composition 7) A first rotating body that grips and transports the sheet, A first rotating body moving unit moves the first rotating body, which is holding the sheet, in a width direction perpendicular to the sheet transport direction, A contact member is positioned downstream of the first rotating body in the sheet transport direction and on one side in the width direction, extending along the sheet transport direction and having a contact surface capable of contacting the end of the sheet in the width direction, A contact member moving unit that moves the contact member in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system comprises the first rotating body moving part and the control unit that controls the contact member moving part, The control unit, When the sheet being transported is of type 1, the first rotating body is moved to the first rotating body moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When the sheet being transported is of a second type different from the first type, the contact member is moved to the contact member moving part so that the contact member moves a second distance to one side. A sheet conveying device characterized by the following features.

[0156] (Composition 8) The sheet conveying direction includes a second rotating body which is adjacent to the first rotating body and positioned upstream of the first rotating body, When the control unit moves the first rotating body to the first rotating body moving unit, the second rotating body is separated from the seat. When the control unit moves the contact member to the contact member moving unit, the second rotating body is in a state of gripping the sheet. A sheet conveying device according to configuration 7, characterized by the features described above.

[0157] (Composition 9) A first rotating body that grips and transports the sheet, A contact member is positioned downstream of the first rotating body in the sheet conveying direction and on one side in the width direction perpendicular to the sheet conveying direction, extending along the sheet conveying direction and having a contact surface capable of contacting the end of the sheet in the width direction, A contact member moving unit that moves the contact member in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system includes a control unit that controls the contact member movement part, The control unit, When the sheet being transported is of type 1, the contact member is moved to the contact member moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When the sheet being transported is of a second type different from the first type, the contact member is moved to the contact member moving part so that the contact member moves a second distance to one side. A sheet conveying device characterized by the following features.

[0158] (Composition 10) A sheet transport device according to any one of configurations 1 to 9, The system includes an image forming unit that forms an image on a sheet conveyed by the aforementioned sheet conveying device. An image forming apparatus characterized by the following features.

[0159] (Composition 11) Displaced downstream of the inclined rotating body in the sheet transport direction, it is movable in the width direction while holding the sheet, and has a position changing part that can change the position of the end of the sheet in the width direction, The position changing unit moves the position in the width direction of the sheet, which has been moved along the contact surface by the oblique rotating body, so that it matches the position in the width direction of the image formed by the image forming unit. The image forming apparatus according to configuration 10, characterized in that... [Explanation of symbols]

[0160] 1…Image forming apparatus: 10…Sheet transport device (sheet alignment device): 31…Contact member: 31a…Contact surface: 32a~32c…Inclined rotating body (inclined roller pair): 34c…Second rotating body (transport roller pair): 34d…First rotating body (transport roller pair): 60…Detection unit (lateral register detection device): 513…Image forming unit: 600…First rotating body movement unit (shift unit): 650…Contact member movement unit (shift unit): 901…Control unit (CPU): S…Sheet: V…Sheet transport direction (transport direction)

Claims

1. A first rotating body that grips and transports the sheet, A first rotating body moving unit moves the first rotating body, which is holding the sheet, in a width direction perpendicular to the sheet transport direction, A contact member is positioned downstream of the first rotating body in the sheet transport direction and on one side in the width direction, extending along the sheet transport direction and having a contact surface capable of contacting the end of the sheet in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system comprises a control unit for controlling the first rotating body movement unit, The control unit, When a sheet whose widthwise end position can be detected by the detection unit is being transported, the first rotating body is moved to the first rotating body moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When a sheet having transparency that prevents the detection unit from detecting the position of its end in the width direction is being transported, the first rotating body moving unit moves the first rotating body a second distance to the other side in the width direction so that the leading edge of the sheet being held by the first rotating body does not collide with the contact member. A sheet conveying device characterized by the following features.

2. The second distance is longer than the first distance. The sheet conveying device according to feature 1.

3. The sheet conveying direction includes a second rotating body positioned adjacent to and upstream of the first rotating body, When the control unit moves the first rotating body to the first rotating body moving unit, the second rotating body is separated from the seat. The sheet conveying device according to feature 1.

4. When the sheet is being transported by the aforementioned inclined rotating body, the first rotating body is in a state separated from the sheet. The sheet conveying device according to feature 1.

5. Displaced downstream of the inclined rotating body in the sheet transport direction, it is movable in the width direction while holding the sheet, and has a position changing part that can change the position of the end of the sheet in the width direction, When the position-changing unit changes the position of the end of the sheet in the width direction, the oblique rotating body is in a state separated from the sheet. The sheet conveying device according to feature 1.

6. A first rotating body that grips and transports the sheet, A first rotating body moving unit moves the first rotating body, which is holding the sheet, in a width direction perpendicular to the sheet transport direction, A contact member is positioned downstream of the first rotating body in the sheet transport direction and on one side in the width direction, extending along the sheet transport direction and having a contact surface capable of contacting the end of the sheet in the width direction, A contact member moving unit that moves the contact member in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system comprises the first rotating body moving part and the control unit that controls the contact member moving part, The control unit, When a sheet whose widthwise end position can be detected by the detection unit is being transported, the first rotating body is moved to the first rotating body moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When a sheet having transparency that prevents the detection of the position of the end in the width direction by the detection unit is being transported, the contact member moving unit moves the contact member a second distance to one side so that the leading edge of the sheet being held by the first rotating body does not collide with the contact member. A sheet conveying device characterized by the following features.

7. The sheet conveying direction includes a second rotating body which is adjacent to the first rotating body and positioned upstream of the first rotating body, When the control unit moves the first rotating body to the first rotating body moving unit, the second rotating body is separated from the seat. When the control unit moves the contact member to the contact member moving unit, the second rotating body is in a state of gripping the sheet. The sheet conveying device according to feature 6.

8. A first rotating body that grips and transports the sheet, A contact member is positioned downstream of the first rotating body in the sheet conveying direction and on one side in the width direction perpendicular to the sheet conveying direction, extending along the sheet conveying direction and having a contact surface capable of contacting the end of the sheet in the width direction, A contact member moving unit that moves the contact member in the width direction, A rotating oblique conveying body moves the sheet in a direction inclined with respect to the sheet conveying direction such that it approaches the contact surface in the width direction as it moves downstream in the sheet conveying direction, A detection unit for detecting the position of one end of the sheet being conveyed by the first rotating body in the width direction, The system includes a control unit that controls the contact member movement part, The control unit, When a sheet whose widthwise end position can be detected by the detection unit is being transported, the contact member is moved to the contact member moving unit based on the detection result of the detection unit so that the distance from the contact surface to one end of the sheet held by the first rotating body becomes a first distance. When a sheet having transparency that prevents the detection of the position of the end in the width direction by the detection unit is being transported, the contact member moving unit moves the contact member a second distance to one side so that the leading edge of the sheet being held by the first rotating body does not collide with the contact member. A sheet conveying device characterized by the following features.

9. A sheet conveying device according to any one of claims 1 to 8, The system includes an image forming unit that forms an image on a sheet transported by the aforementioned sheet transport device. An image forming apparatus characterized by the following features.

10. Displaced downstream of the inclined rotating body in the sheet transport direction, it is movable in the width direction while holding the sheet, and has a position changing part that can change the position of the end of the sheet in the width direction, The position changing unit moves the position in the width direction of the sheet, which has been moved along the contact surface by the oblique rotating body, so that it matches the position in the width direction of the image formed by the image forming unit. The image forming apparatus according to feature 9.

Images