Sheet conveying device and image forming system

Abstract

To provide a configuration that is able to suppress reduction in the productivity of a sheet.SOLUTION: A pair of restriction guides 14A, 14B are capable of guiding both edges, in a sheet width direction Y, of a sheet S1 that is conveyed while being sandwiched between a conveyance belt 12 and a spherical body 20. The pair of restriction guides 14A, 14B are capable of moving between a guide position for guiding both edges of a sheet and a retraction position retracted further from both the edges of the sheet than the guide position. The sheet detection sensor 435 is disposed downstream of the conveyance belt 12 in a conveyance direction X and detects the presence or absence of a sheet. When a sheet detection sensor 435 does not detect a sheet even after a lapse of a predetermined time following movement of the pair of restriction guides 14A, 14B from the retraction position to the guide position, a retraction operation is performed in which the pair of restriction guides 14A, 14B are moved from the guide position to the retraction position while the conveyance belt 12 continues driving in a direction in which the sheet is conveyed.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device for conveying a sheet. and an image forming system including a sheet conveying device Regarding. [Background technology]

[0002] In a sheet conveying device that conveys a sheet, there is a risk that the sheet may become misaligned due to various factors while being conveyed. If the sheet is conveyed to an image forming device that forms an image on the sheet while the misalignment remains, problems such as the image being misaligned with respect to the sheet may occur. For this reason, a sheet conveying device that corrects the misalignment of the sheet during conveyance is known (for example, Patent Document 1).

[0003] Patent Document 1 discloses a configuration including a fixed reference guide provided on one side in the width direction intersecting the sheet conveyance direction, a conveyor belt provided at an angle relative to the reference guide, and a sphere. In the sheet conveying device described in Patent Document 1, the sheet is conveyed while being sandwiched between the conveyor belt and the sphere, so that the width direction edge of the sheet abuts against the reference guide. Then, the side registration (positional deviation of the width direction edge of the sheet) and side skew (inclination of the width direction edge of the sheet relative to the sheet conveyance direction) of the sheet are simultaneously corrected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-217096 Summary of the Invention [Problem to be solved by the invention]

[0005] In the sheet conveying device described in Patent Document 1, a sheet is conveyed by an inclined conveyor belt, and the widthwise edge of the sheet is abutted against a reference guide. Therefore, the sheet needs to be conveyed until it abuts against the reference guide, which may result in an increase in the size of the device in order to ensure the length required for sheet conveyance. Therefore, a configuration can be considered in which a pair of regulating guides is provided on both sides of the sheet in the width direction in order to correct the sheet's widthwise misalignment while suppressing the increase in the size of the device. With this configuration, the pair of regulating guides are moved from a retracted position to a guide position, and the widthwise edge of the sheet is guided at the guide position to correct the sheet's widthwise misalignment.

[0006] In a configuration where a sheet is conveyed while being sandwiched between the conveyor belt and the spheres, the force with which the sheet is sandwiched between the conveyor belt and the spheres is weak. Therefore, if the sheet contacts the regulating guide at the guide position during conveyance and the friction between the sheet and the regulating guide is large, the sheet may not be conveyed even if the conveyor belt is driven. Furthermore, if a sensor downstream of the conveyor belt does not detect the sheet for a predetermined period of time, it is determined that the sheet has jammed, causing the device to stop and resulting in reduced productivity.

[0007] An object of the present invention is to provide a configuration that can suppress a decrease in sheet productivity. [Means for solving the problem]

[0008] One aspect of the present invention is a sheet conveying device comprising: a conveyor belt that conveys a sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects the conveying direction and are movable in the sheet width direction when the conveyor belt and the edge of the sheet conveyed by the spheres in the sheet width direction come into contact; a receiving position that receives the pair of regulating guides; This sheet conveying device includes a regulating guide moving mechanism that moves the regulating guides to a regulating position where the skew of the sheet is regulated when the distance between the regulating guides is narrower than the distance at the receiving position and the edge of the sheet abuts against them; a detection means that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; and a control unit that is capable of performing a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to drive in the direction of conveying the sheet if the detection means does not detect the sheet even after a predetermined time has elapsed after the conveying belt receives the sheet and moves the pair of regulating guides from the receiving position to the regulating position.

[0009] Another aspect of the present invention includes a conveyor belt that conveys a sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects the conveying direction and are movable in the sheet width direction when an edge of the sheet conveyed by the conveyor belt and the spheres in the sheet width direction come into contact with each other; and a receiving position where the pair of regulating guides are positioned in front of the sheet, the pair of regulating guides being spaced apart from each other at a receiving position where the distance between the pair of regulating guides is narrower than the distance at the receiving position. The sheet conveying device includes a regulating guide moving mechanism that moves the regulating guides to a regulating position where the skew of the sheet is regulated when the recording edge abuts against the regulating guides; an upstream detection means that detects the presence or absence of a sheet upstream of the conveying belt in the conveying direction; a downstream detection means that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; and a control unit that moves the pair of regulating guides to the regulating position after the trailing end of the sheet passes the upstream detection means, and if the downstream detection means does not detect the sheet even after a predetermined time has elapsed since the trailing end of the sheet passed the upstream detection means, performs a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to drive in the direction of conveying the sheet.

[0010] Another aspect of the present invention is a sheet conveying device including a conveyor belt that conveys a sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects with the conveying direction and are movable in the sheet width direction when an edge in the sheet width direction of the sheet conveyed by the conveyor belt and the spheres abut; and a receiving position for receiving the sheet, the pair of regulating guides being disposed between the pair of regulating guides. a control unit that is capable of performing a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the direction of conveying the sheet, if the detection unit does not detect the sheet after the conveying belt has received the sheet and moved the pair of regulating guides from the receiving position to the regulating position and the conveying belt continues to be driven in the direction of conveying the sheet for a predetermined amount after the conveying belt has received the sheet and moved the pair of regulating guides from the receiving position to the regulating position,

[0011] Another aspect of the present invention includes a conveyor belt that conveys a sheet in a conveyance direction; a plurality of spheres arranged along the conveyance direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects the conveyance direction and are movable in the sheet width direction when an edge in the sheet width direction of the sheet conveyed by the conveyor belt and the spheres abut; and a receiving position where the pair of regulating guides are positioned to receive the sheet, and a distance between the pair of regulating guides at the receiving position. a control unit that performs a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the direction of conveying the sheet if the detection unit does not detect the sheet even after a predetermined time has elapsed after the conveying belt receives the sheet and moves the pair of regulating guides from the receiving position to the regulating position; and an image forming unit that forms an image on the sheet conveyed by the conveying belt.

[0012] Another aspect of the present invention includes a conveyor belt that conveys a sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects the conveying direction and are movable in the sheet width direction when an edge of the sheet conveyed by the conveyor belt and the spheres come into contact with each other; and a receiving position where the pair of regulating guides are positioned to receive the sheet and a receiving position where the distance between the pair of regulating guides is narrower than the distance at the receiving position so that the skew of the sheet is corrected when the edge of the sheet comes into contact with the regulating guides. an upstream detection means for detecting the presence or absence of a sheet upstream of the conveyor belt in the conveying direction; a downstream detection means for detecting the presence or absence of a sheet downstream of the conveyor belt in the conveying direction; a control unit that moves the pair of regulation guides to the regulation position after the trailing edge of the sheet has passed the upstream detection means, and, if the downstream detection means does not detect the sheet even after a predetermined time has elapsed since the trailing edge of the sheet has passed the upstream detection means, executes a retraction operation to move the pair of regulation guides from the regulation position in a direction toward the receiving position while the conveyor belt continues to be driven in the sheet conveying direction; and an image forming unit that forms an image on the sheet conveyed by the conveyor belt. Another aspect of the present invention includes a conveyor belt that conveys a sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the spheres and allows the spheres to rotate in any direction while rubbing against a portion of the surface of the spheres; a pair of regulating guides that are provided on both sides of the conveyor belt in a sheet width direction that intersects with the conveying direction and are movable in the sheet width direction when an edge in the sheet width direction of the sheet conveyed by the conveyor belt and the spheres abut; and a receiving position that receives the sheet and a position where the distance between the pair of regulating guides is narrower than the distance at the receiving position. a control unit that performs a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the direction of conveying the sheet, if the detection unit does not detect the sheet after the conveying belt has received the sheet and moved the pair of regulating guides from the receiving position to the regulating position, and if the detection unit does not detect the sheet even after the conveying belt has continued to be driven in the conveying direction for a predetermined amount, and an image forming unit that forms an image on the sheet conveyed by the conveying belt. [Effects of the Invention]

[0013] According to the present invention, the sheet can be transported stably. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an image forming system according to an embodiment. [Figure 2] FIG. 1 is a perspective view of an intermediary transport device according to an embodiment. [Figure 3] FIG. 2 is a plan view of an intermediary transport device according to the embodiment. [Figure 4] FIG. 2 is a side view of the intermediary transport device according to the embodiment. [Figure 5] FIG. 2 is a cross-sectional view of an intermediary transport device according to the embodiment. [Figure 6] (a) An oblique view of a regulating guide according to an embodiment, (b) a view from the left side of (a), (c) a cross-sectional view cut in a direction along the sheet conveying direction, and (d) a cross-sectional view cut in a direction perpendicular to the sheet conveying direction. [Figure 7] FIG. 2 is a perspective view showing a contact / separation mechanism for a conveying roller according to the embodiment. [Figure 8] 5A and 5B are side views showing a nipped state and a released state of the conveying rollers, respectively, of the conveying roller contact / separation mechanism according to the embodiment. [Figure 9] FIG. 2 is a block diagram relating to sheet conveyance control according to the embodiment. [Figure 10] 10 is a flowchart relating to sheet conveyance control according to the embodiment. [Figure 11] 1A and 1B are diagrams explaining the operation of the regulating guide according to an embodiment, each showing (a) the state in which the sheet is received, (b) the state in which the rear end of the sheet has passed the sheet detection sensor, (c) the state in which the sheet has been caught in the regulating guide and stopped, and (d) the state in which the regulating guide has moved to a retracted position. DETAILED DESCRIPTION OF THE INVENTION

[0015] The embodiment will be described with reference to Figures 1 to 11. First, the image forming system of the present embodiment will be described with reference to Figure 1.

[0016] [Image formation system] FIG. 1 is a cross-sectional view schematically illustrating an example of an image forming system including a multistage feeding device and an image forming apparatus according to this embodiment. In the following description, an electrophotographic laser printer system (hereinafter simply referred to as a printer) will be used as an example of an image forming apparatus having an image forming unit. Note that the image forming apparatus constituting the image forming system may be a copier, facsimile, multifunction peripheral, or the like, in addition to a printer. Furthermore, the image forming apparatus may be configured using other methods, such as an inkjet method, regardless of the electrophotographic method.

[0017] Image forming system 1000 of this embodiment includes image forming apparatus 100, multistage feeding apparatus 200 as a sheet feeding apparatus connected to image forming apparatus 100, and feeding deck 500. As will be described in detail later, multistage feeding apparatus 200 has a plurality of storage cabinets each capable of storing a plurality of sheets, and is capable of feeding sheets from each storage cabinet to image forming apparatus 100. Feeding deck 500 also has storage cabinets capable of storing a plurality of sheets, and is disposed upstream of multistage feeding apparatus 200 in the sheet conveying direction. Sheets fed from feeding deck 500 are conveyed to image forming apparatus 100 via relay conveying apparatus 400 provided in multistage feeding apparatus 200. Examples of sheets include paper such as plain paper, thin paper, and cardboard, and plastic sheets.

[0018] The image forming apparatus 100 forms a toner image (image) on a sheet in response to an image signal from a document reading device 102 connected to the image forming apparatus main body 101 or a host device such as a personal computer connected to the image forming apparatus main body 101 so as to be able to communicate with the image forming apparatus main body 101. In this embodiment, the document reading device 102 is disposed above the image forming apparatus main body 101.

[0019] When reading an original, the original reading device 102 irradiates light from a scanning optical system light source onto the original placed on a platen glass 103, and the reflected light is input to a CCD to read the original image. The original reading device 102 also includes an automatic document feeder (ADF) 104, which can automatically transport an original placed on a tray 105 to a reading unit of the original reading device 102 and read the original image. The read original image is then converted into an electrical signal and transmitted to a laser scanner 113 of an image forming unit 110, which will be described later. Note that the laser scanner 113 may also receive image data transmitted from a personal computer or the like, as described above.

[0020] Image forming apparatus 100 includes an image forming section 110, a plurality of sheet feeding devices 120, a sheet conveying device 130, etc. Each section of image forming apparatus 100 is controlled by a control section 140. Control section 140 has a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU controls each section by reading programs corresponding to control procedures stored in the ROM. In addition, working data and input data are stored in the RAM, and the CPU performs control by referring to the data stored in the RAM based on the aforementioned programs, etc.

[0021] Each of the plurality of sheet feeding devices 120 includes a cassette 121 that stores sheets S, a pickup roller 122, and a separation conveying roller pair 125 that is composed of a feed roller 123 and a retard roller 124. The sheets S stored in the cassette 121 are separated and fed one by one by the pickup roller 122 and the separation conveying roller pair 125 that move up and down and rotate at a predetermined timing.

[0022] The sheet conveying device 130 includes a conveying roller pair 131 and a registration roller pair 133. The sheet S fed from the sheet feeding device 120 is passed through a sheet conveying path 134 by the conveying roller pair 131, and then guided to the registration roller pair 133. Thereafter, the sheet S is sent to the image forming unit 110 by the registration roller pair 133 at a predetermined timing.

[0023] Note that sheets conveyed from a multistage feeding device 200 or a feeding deck 500 (described later) via a pair of conveying rollers 201 are conveyed into the image forming apparatus 100 via a connection path 202 with the image forming apparatus 100. Then, the sheets conveyed from the multistage feeding device 200 or the feeding deck 500 into the image forming apparatus 100 are sent into the image forming unit 110 at a predetermined timing via a pair of registration rollers 133, similar to sheets conveyed from a sheet feeding device 120 in the image forming apparatus 100.

[0024] The image forming unit 110 includes a photosensitive drum 111, a charger 112, a laser scanner 113, a developing device 114, a transfer device 115, a cleaner 117, and the like. During image formation, the photosensitive drum 111 is rotated in the direction of the arrow in the figure, and first, the surface of the photosensitive drum 111 is uniformly charged by the charger 112. Then, the charged photosensitive drum 111 is irradiated with laser light from the laser scanner 113, which is emitted in response to an image signal, thereby forming an electrostatic latent image on the photosensitive drum 111. Furthermore, the electrostatic latent image thus formed on the photosensitive drum 111 is then visualized as a toner image by the developing device 114.

[0025] Thereafter, the toner image on the photosensitive drum 111 is transferred to the sheet S by a transfer device 115 in a transfer section 116. Furthermore, the sheet S onto which the toner image has been transferred in this manner is conveyed to a fixing device 150 where the toner image is fixed, and thereafter the sheet S is discharged by a discharge roller 151 onto a discharge tray 152 outside the apparatus.

[0026] When a toner image is formed on the back side of the sheet S, the sheet S discharged from the fixing device 150 is conveyed to a reversing conveying path 160. Then, the sheet S is turned over by the reversing conveying path 160 and conveyed again to the transfer unit 116 of the image forming unit 110. The sheet S with the toner image transferred to the back side is conveyed to the fixing device 150, where the toner image is fixed, and then the sheet S is discharged to a discharge tray 152 by a discharge roller 151. Note that any residual toner remaining on the photosensitive drum 111 after transfer is removed by a cleaner 117.

[0027] [Multi-stage feeding device] Continuing with the above, an overview of the multistage feeding device 200 will be described with reference to Fig. 1. The multistage feeding device 200 includes a plurality of storage cabinets 210a-210c, an intermediary conveying device 400, etc. In this embodiment, three storage cabinets 210a-210c are arranged vertically in three stages, and the intermediary conveying device 400 is disposed between the bottom storage cabinet 210c and the second-highest storage cabinet 210b.

[0028] A sheet fed from the top storage case 210a is transported to transport path 212, a sheet fed from the second top storage case 210b is transported to transport path 213, and a sheet fed from the bottom storage case 210c is transported to transport path 214. Furthermore, a sheet transported from relay transport device 400 is transported to transport path 215. Transport path 213 merges with transport path 212 midway. Furthermore, transport paths 212, 214, and 215 merge at a junction 216, and the sheet is transported to transport roller pair 201 via transport path 217 and then transported to image forming apparatus 100 via connection path 202.

[0029] Furthermore, a multi-feed detection sensor for detecting multi-feeding of sheets is disposed on each of the conveyance path 212, the relay conveyance device 400, and the conveyance path 214 after merging with the conveyance path 213. A sheet for which a multi-feed is detected by the multi-feed detection sensor is conveyed to the conveyance path 217. A multi-feed sheet storage unit (escape tray) 218 for storing sheets for which a multi-feed is detected is disposed below the conveyance path 217. A sheet for which a multi-feed is detected and conveyed to the conveyance path 217 is conveyed to the multi-feed sheet storage unit by switching the conveyance path by a switching member 219 provided on the conveyance path 217.

[0030] Each unit of the multistage feeding device 200 is controlled by a control unit 203. The control unit 203 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 203 can communicate with the control unit 140 of the image forming apparatus 100, and controls the timing of sheet feeding by communicating with the control unit 140.

[0031] A sheet fed from the upstream feeding deck 500 is conveyed to the relay conveying device 400 through a conveying path 512. The multistage feeding device 200 is also capable of manually feeding a sheet. A manually fed sheet is conveyed to a conveying path 510 that merges with the conveying path 512, and is conveyed to the relay conveying device 400 through the conveying path 512 by a pair of conveying rollers 511.

[0032] As will be described in detail below, the relay conveyance device 400 includes a misalignment correction unit 410 including a conveyance belt 12, a conveyance roller pair 401 located upstream of the misalignment correction unit 410 in the sheet conveyance direction, and a conveyance roller pair 402 located downstream of the misalignment correction unit 410 in the sheet conveyance direction. A sheet conveyed along a conveyance path 512 is sent to the misalignment correction unit 410 by the conveyance roller pair 401. After the side registration (misalignment of the sheet width direction edge) and side skew (inclination of the sheet width direction edge with respect to the sheet conveyance direction) are corrected by the misalignment correction unit 410, the sheet is handed over to the downstream conveyance roller pair 402. The sheet is then conveyed to the conveyance path 215 by the conveyance roller pairs 402 and 403. In this way, the relay conveyance device 400 corrects misalignment of the sheet conveyed from the upstream feeding deck 500 or the like, and hands it over to the downstream image forming apparatus 100.

[0033] [Relay transport device] Next, a relay conveying device 400 serving as a sheet conveying device will be described. First, a schematic configuration of the relay conveying device 400 will be described with reference to Figs. 2 to 5. The relay conveying device 400 includes an upstream conveying roller pair 401, a downstream conveying roller pair 402, the above-mentioned positional deviation correction unit 410, and the like, and conveys a sheet in the conveying direction X. The positional deviation correction unit 410 includes a conveying belt 12, a plurality of spheres 20, a pair of regulating guides 14A and 14B, a guide moving unit 420, and the like.

[0034] The conveyor belt 12 is disposed downstream (downstream in the conveying direction) of a pair of conveying rollers 401, which serves as a conveying member for conveying a sheet, in a conveying direction X (a predetermined conveying direction). The conveyor belt 12 is an endless belt stretched over pulleys 11A and 11B, and has a conveying surface 12A extending along the conveying direction X. A motor M1, which serves as a drive source, is connected to the pulley 11A on one side, and the conveyor belt 12 is rotated by the driving of the motor M1. The conveyor belt 12 conveys, in the conveying direction X, a sheet that has been handed over to the conveying surface 12A from the pair of conveying rollers 401, which is located upstream in the conveying direction X.

[0035] A plurality of spheres 20 are arranged along the conveying direction X at positions facing the conveying surface 12A of the conveyor belt 12. In this embodiment, the plurality of spheres 20 are arranged above the conveyor belt 12. The plurality of spheres 20 are capable of rotating in any direction while sandwiching a sheet between themselves and the conveying surface 12A. For this purpose, the plurality of spheres 20 are supported by holding plates provided above the conveyor belt 12. (holding mechanism) 2 and 3, the holding plate 18 is a long plate arranged above the conveyor belt 12 along the conveying direction X at a position a predetermined distance from the conveying surface 12A, and has a plurality of holding holes 18A spaced apart from one another in the conveying direction X. Each holding hole 18A holds a sphere 20 rotatably in the corresponding one of the holding holes 18A.

[0036] As shown in FIG. 4 , the spheres 20 are exposed from the holding holes 18A, placed on the conveying surface 12A of the conveyor belt 12, and are rotatable in any direction. Each sphere 20 abuts against the conveying surface 12A due to its own weight. The number of spheres 20 may be determined according to the pressing force required for the sheet conveyed on the conveyor belt 12. Furthermore, because the sheet slips on the conveyor belt 12 as described below, the spheres 20 are preferably made of a material with a relatively low coefficient of friction, such as glass or plastic. In this embodiment, a configuration in which multiple spheres 20 are arranged in a single row along the conveying direction X has been described. However, multiple spheres 20 may also be arranged in multiple rows, such as two rows, each aligned in the conveying direction X.

[0037] The pair of regulating guides 14A and 14B are arranged on both sides of the conveyor belt 12 in a sheet width direction Y (a direction perpendicular to the conveying direction in this embodiment) that intersects with the conveying direction X. The pair of regulating guides 14A and 14B can guide both edge portions in the sheet width direction Y of the sheet being conveyed while being sandwiched between the conveyor belt 12 and the spherical bodies 20. That is, the regulating guide 14A arranged on one side (the front side of the device) in the sheet width direction Y can guide one edge portion in the sheet width direction of the sheet being conveyed while being sandwiched between the conveyor belt 12 and the spherical bodies 20. The regulating guide 14B arranged on the other side (the back side of the device) in the sheet width direction Y can guide the other edge portion in the sheet width direction of the sheet being conveyed while being sandwiched between the conveyor belt 12 and the spherical bodies 20. The one side (the front side) in the sheet width direction Y is the side where the image forming system 1000 is operated.

[0038] 5, each of the pair of regulating guides 14A and 14B has a side plate portion 15, a lower plate portion 16, and an upper plate portion 17, and the end portion of the sheet S conveyed by the conveyor belt 12 can enter into the space surrounded by these plate portions 15, 16, and 17. The pair of regulating guides 14A and 14B are moved to the guide positions by a guide moving portion 420, which will be described later. (Restriction position) and the evacuation position (Receiving location) The pair of regulating guides 14A and 14B are supported by support shafts 421A and 421B (see FIG. 3) so as to be movable in the sheet width direction Y. The support shafts 421A and 421B are arranged substantially parallel to the sheet width direction Y, and support the end sides of the pair of regulating guides 14A and 14B in the conveying direction X. The pair of regulating guides 14A and 14B are movable in the sheet width direction Y along the support shafts 421A and 421B.

[0039] At the guide position, the side plate portion 15 has a guide surface 15A that faces the edge in the sheet width direction Y (sheet width direction edge) of the sheet S that is conveyed while being sandwiched between the conveyor belt 12 and the spheres 20. The guide surface 15A is disposed parallel to the conveying direction X. The guide surface 15A is also a surface that is perpendicular to both the conveying direction X and the sheet width direction Y, and in this embodiment, is a surface that is aligned along a substantially vertical direction.

[0040] The lower plate portion 16 is disposed perpendicular to the side plate portions 15, and has a support surface 16A that supports, at the guide position, the edge in the sheet width direction Y of the sheet S that is conveyed while being sandwiched between the conveyor belt 12 and the spheres 20. The support surface 16A extends in a substantially horizontal direction from the vertical lower end of the guide surface 15A. The support surface 16A is also positioned vertically below the conveying surface 12A of the conveyor belt 12.

[0041] Here, let us consider a case where the support surface 16A and the conveying surface 12A are at the same height, or where the support surface 16A is positioned vertically higher than the conveying surface 12A. In this case, if a highly rigid sheet S, such as cardboard, is conveyed between the conveying belt 12 and the spheres 20 in a curled-down state (where both edges in the width direction Y are lower than the center) as shown in FIG. 5, both edges in the width direction Y of the sheet S are supported by the support surface 16A. At this time, the center of the sheet S in the width direction Y is lifted (bridged), pushing up the spheres 20. As a result, the conveying belt 12 and the spheres 20 are separated, and the conveying force of the conveying belt 12 is not transmitted to the sheet S, which may result in conveyance failure. For this reason, in this embodiment, the support surface 16A is positioned vertically lower than the conveying surface 12A of the conveying belt 12.

[0042] The upper plate portion 17 has an opposing surface 17A disposed opposite to the support surface 16A. At the guide position, the opposing surface 17A is located above the edge of the sheet S in the sheet width direction Y, which is conveyed while being sandwiched between the conveyor belt 12 and the spheres 20. The opposing surface 17A is formed substantially parallel to the support surface 16A.

[0043] Guided transportation (Regulatory guide mechanism) 2 and 3, the guide movement unit 420 as a guide guide 14A includes a first movement unit 420A that moves one of the pair of restriction guides 14A, 14B, the restriction guide 14A, and a second movement unit 420B that moves the other restriction guide 14B. The guide movement unit 420 also includes a motor M2 that generates a driving force to move the restriction guide 14A, and a motor M3 that generates a driving force to move the other restriction guide 14B.

[0044] The first moving section 420A has a pair of pulleys 422A and 423A, an endless belt 424A passed over both pulleys 422A and 423A, and a connection section 425A connecting the belt 424A to the regulating guide 14A. Similarly, the second moving section 420B has a pair of pulleys 422B and 423B, an endless belt 424B passed over both pulleys 422B and 423B, and a connection section 425B connecting the belt 424B to the other regulating guide 14B.

[0045] As shown in FIG. 2, the first moving unit 420A is driven by a motor M2 as a drive source, and the second moving unit 420B is driven by a motor M3 as a drive source. In other words, in this embodiment, separate motors are used as drive sources for moving the pair of regulating guides 14A and 14B, and the pair of regulating guides 14A and 14B can move independently. For this purpose, a pulley 422A of the first moving unit 420A is connected to a pulley 427A via a connecting shaft 426A, and a belt 428A is stretched between the pulley 427A and a pulley that is rotationally driven by the motor M2. The rotational drive of the motor M2 is transmitted to the belt 424A via the belt 428A, the pulley 427A, the connecting shaft 426A, and the pulley 422A. As described above, the regulating guide 14A is connected to the belt 424A via the connecting portion 425A, and therefore, when the motor M2 is driven, the regulating guide 14A moves in the sheet width direction Y along the support shafts 421A and 421B.

[0046] Similarly, the pulley 422B of the second moving section 420B is connected to a pulley 427B via a connecting shaft 426B, and a belt 428B is stretched between the pulley 427B and a pulley that is rotationally driven by the motor M3. The rotational drive of the motor M3 is transmitted to the belt 424B via the belt 428B, the pulley 427B, the connecting shaft 426B, and the pulley 422B. As described above, the other side regulating guide 14B is connected to the belt 424B via the connecting portion 425B, and therefore, when the motor M3 is driven, the other side regulating guide 14B moves in the sheet width direction Y along the support shafts 421A and 421B.

[0047] By driving the motors M2 and M3 in this manner, the regulating guides 14A and 14B are moved to the guide position or the retracted position, respectively. In this embodiment, the motors M2 and M3 are pulse motors (stepping motors), and the positions of the regulating guides 14A and 14B are controlled by the number of pulses sent to the motors. Furthermore, the regulating guides 14A and 14B each have a home position, and a sensor is provided at each home position to detect the regulating guides 14A and 14B. Therefore, the positions of the regulating guides 14A and 14B are detected at the home position, and thereafter, the regulating guides 14A and 14B are moved to the guide position or the retracted position depending on the number of pulses sent to the motors.

[0048] In this embodiment, the motor M1 that drives the conveyor belt 12, the motors M2 and M3 that move the regulating guides 14A and 14B, and the motors M5, M7, and M8 described below are arranged on the other regulating guide 14B side. In particular, with respect to the conveying direction X, it is preferable that the motors within the sheet conveying range of the positional deviation correction unit 410 are arranged on the rear side (the other regulating guide 14B side) of the conveyor belt 12. This is because, in this embodiment, a jammed sheet is removed from the front side (the one-side regulating guide 14A side).

[0049] 3 and 4, in this embodiment, a multi-feed detection sensor 430 that detects multi-feeding of sheets is disposed between the upstream conveying roller pair 401 and the conveying belt 12. The multi-feed detection sensor 430 is a sensor that detects that two or more sheets are conveyed overlapping each other, for example, by using ultrasonic waves. When the multi-feed detection sensor 430 detects multi-feeding of sheets, the control unit 203 (FIG. 1) of the multi-stage feeding device 200 conveys the multi-fed sheets to the multi-fed sheet storage unit 218 via the relay conveying device 400 and the conveying paths 215 and 217.

[0050] 4, the relay conveying device 400 of this embodiment has multiple sheet detection sensors 433, 435, and 436 to detect sheet jams. A sheet jam refers to a sheet getting stuck in the conveying path. The sheet detection sensor 433, which serves as an upstream detection means, is disposed upstream of the conveying belt 12 in the conveying direction X (upstream side of the conveying direction) and detects the presence or absence of a sheet. The sheet detection sensor 431 is disposed between the conveying belt 12 and the pair of conveying rollers 401.

[0051] The sheet detection sensor 435 serving as a detection means or a first detection means is arranged downstream in the conveying direction X of the conveyor belt 12 (downstream in the conveying direction) and detects the presence or absence of a sheet. The sheet detection sensor 435 is arranged between the pair of conveying rollers 402 and 403 which are arranged downstream of the conveyor belt 12. The sheet detection sensor 436 serving as a detection means or a second detection means is arranged downstream in the conveying direction X of the sheet detection sensor 435 and detects the presence or absence of a sheet. The sheet detection sensor 436 is arranged downstream of the pair of conveying rollers 403. The sheet detection sensors 435 and 436 correspond to downstream detection means.

[0052] The control unit 203 (FIG. 1) of the multistage feeding device 200 determines whether a sheet has jammed in the conveyance path based on detection signals from various sheet detection sensors such as the sheet detection sensors 433, 435, and 436. If the control unit 203 determines that a sheet has jammed, it stops the conveyance of the sheet and displays the jammed sheet and the location of the jammed sheet on a display unit such as a liquid crystal panel provided in the image forming system 1000. At this time, it prompts an operator such as a user or a service person to open the door at the relevant location.

[0053] 3, in this embodiment, opposing members 450 and 460 that face the lower surface of the sheet conveyed by the conveyor belt 12 are arranged between the conveyor belt 12 and the pair of regulating guides 14A and 14B in the sheet width direction Y. If the edge of the sheet is conveyed without being supported by either of the regulating guides 14A and 14B, the opposing members 450 and 460 support the edge of the sheet.

[0054] In the relay conveyance device 400 configured as described above, a sheet transferred from a pair of conveyance rollers 401 upstream in the conveyance direction X to the conveyance belt 12 is sandwiched between the conveyance belt 12 and the spheres 20. The sheet is then conveyed by the rotation of the conveyance belt 12. At this time, as will be described in detail later, both ends of the sheet in the width direction Y conveyed by the conveyance belt 12 abut against the guide surfaces 15A of the pair of regulating guides 14A and 14B. When the sheet abuts against the guide surfaces 15A, the sheet is conveyed in a direction parallel to the guide surfaces 15A while slipping between the sheet and the conveyance belt 12 with both ends aligned with the guide surfaces 15A. At this time, the sheet is sandwiched between the conveyance belt 12 and the spheres 20, and because the spheres 20 can rotate in any direction, the sheet can move on the conveyance belt 12 while slipping in any direction. This corrects the side registration and side skew of the sheet.

[0055] [Regulatory Guide] Next, the detailed configuration of the first and second restriction guides 14A and 14B will be described with reference to Figures 6(a) to 6(d). Note that while Figures 6(a) to 6(d) only show the restriction guide 14A on one side, the restriction guide 14B on the other side has the same configuration. As shown in Figure 5, the restriction guide 14A has a side plate portion 15 having a guide surface 15A, a lower plate portion 16 having a support surface 16A, and an upper plate portion 17 having an opposing surface 17A.

[0056] 6(a) and 6(b), the lower plate portion 16 and the upper plate portion 17 are provided continuously over almost the entire longitudinal area of the regulating guide 14A. Since the regulating guide 14A is disposed substantially parallel to the conveying direction X as shown in FIG. 2 and the like, the range in which the lower plate portion 16 and the upper plate portion 17 are continuous in the conveying direction X is defined as a predetermined area A. Therefore, in this embodiment, the support surface 16A of the lower plate portion 16 and the opposing surface 17A of the upper plate portion 17 are provided continuously over the predetermined area A in the conveying direction X. The predetermined area A is almost the entire area in which the sheet is conveyed by the positional deviation correction unit 410.

[0057] 6(a) to 6(c), the side plate portion 15 is provided continuously over a guide region B, which is a region shorter than the predetermined region A. In this embodiment, the upstream end B1 of the side plate portion 15 in the conveying direction X (upstream end in the conveying direction) is located downstream of the upstream end A1 of the predetermined region A in the conveying direction X. That is, the upstream end B1 of the guide surface 15A of the side plate portion 15 in the conveying direction X is located downstream of the upstream end A1 of the predetermined region A. The guide surface 15A is also provided continuously up to the downstream end A2 of the predetermined region A in the conveying direction X. Therefore, the position of the downstream end B2 of the side plate portion 15 in the conveying direction X and the position of the downstream end A2 of the predetermined region A in the conveying direction X are substantially the same position in the conveying direction X.

[0058] In this embodiment, a notch 19C is provided upstream of the upstream end B1 of the side plate portion 15. An outer plate portion 19 is disposed in a part of this notch 19C, and is positioned outside the side plate portion 15 in the sheet width direction Y. The outside in the sheet width direction Y refers to the side that is farther away from the conveyor belt 12 in the sheet width direction Y. Therefore, as shown in FIG. 6(c), an inner surface 19A of the outer plate portion 19 is positioned outside in the sheet width direction Y of a guide surface 15A, which is the inner surface of the side plate portion 15. In addition, an inclined plate portion 19B is provided between the outer plate portion 19 and the side plate portion 15 in the conveying direction X, and is inclined so as to approach the side plate portion 15 as it goes downstream.

[0059] The pair of regulating guides 14A, 14B are configured as described above, so that the distance in the width direction Y between the inner surfaces 19A of the outer plate portions 19 on the upstream side in the conveying direction X is wider than the distance in the width direction Y between the guide surfaces 15A of the side plate portions 15. Therefore, as will be described in detail later, both edge portions in the width direction Y of the sheet transferred from the upstream conveying roller pair 401 to the conveying belt 12 are located between the inner surfaces 19A on the upstream side in the conveying direction X, and are located between the guide surfaces 15A when conveyed downstream.

[0060] The outer plate portion 19 and the inclined plate portion 19B may be omitted. However, if the end portion in the width direction Y of a sheet transferred from the upstream conveying roller pair 401 to the conveying belt 12 is positioned within the notch 19C, there is a risk that the end portion of the sheet will get caught on the upstream end B1 of the side plate portion 15 when the sheet is further conveyed. For this reason, in this embodiment, the outer plate portion 19 and the inclined plate portion 19B are provided so that even if the sheet is conveyed deviating from its normal position in the width direction Y, the outer plate portion 19 regulates its position, and the inclined plate portion 19B guides the end portion of the sheet to the guide surface 15A of the side plate portion 15.

[0061] [Contact / separate structure of conveying roller pair] Next, referring to FIGS. 1 and 2, and using FIGS. 7, 8(a), and 8(b), the contact / separation configuration of the conveying roller pairs 401 to 403 will be described. As described above, the conveying roller pairs 401 to 403 are respectively arranged upstream and downstream in the conveying direction X of the conveying belt 12. Each of the conveying roller pairs 401 to 403 has a drive roller 32 and a driven roller 33 as a pair of conveying rollers. The drive roller 32 is an elastic roller having an elastic body such as rubber provided around the periphery of a rotation shaft 32a. The driven roller 33 contacts the drive roller 32 to form a nip portion that sandwiches and conveys a sheet. The drive roller 32 of the conveying roller pair 401 can be rotated independently by a motor M4, the drive roller 32 of the conveying roller pair 402 can be rotated independently by a motor M5, and the drive roller 32 of the conveying roller pair 403 can be rotated independently by a motor M6.

[0062] In this embodiment, the pair of conveying rollers 402 and 403, which are arranged on the downstream side of the conveying direction X of the conveyor belt 12 (downstream side in the conveying direction), have a configuration that allows the drive roller 32 and the driven roller 33 to contact and separate from each other. The pair of conveying rollers 402 can independently contact and separate from each other the drive roller 32 and the driven roller 33 by a motor M7, and the pair of conveying rollers 403 can independently contact and separate from each other the drive roller 32 and the driven roller 33 by a motor M8. Since the pairs of conveying rollers 402 and 403 have the same configuration, the contact and separation configuration will be described below using the pair of conveying rollers 402 as an example with reference to FIGS. 7, 8(a) and 8(b).

[0063] The contact / separation mechanism 31, which brings the drive roller 32 and the driven roller 33 into contact with and separates them, has a compression spring 34 as a biasing means, a support member 35, a motor M7, a separation cam 36, and a link member 37. The contact / separation mechanism 31 corresponds to a roller moving means that can move at least one of the pair of conveying rollers, i.e., the driven roller 33, between a nip position where the sheet can be nipped and conveyed, and a nip release position where the pair of conveying rollers are spaced apart from the nip position.

[0064] The compression spring 34 is a spring that urges the driven roller 33 toward the drive roller 32. The support member 35 supports the rotation shaft 33a of the driven roller 33 and is supported so as to be swingable about the swing shaft 37a. The support member 35 is also urged by the compression spring 34 in a direction that presses the driven roller 33 toward the drive roller 32 about the swing shaft 37a. The support member 35 is fixed to the swing shaft 37a and rotates together with the swing shaft 37a, moving the driven roller 33 in a direction toward the drive roller 32 and a direction away from the drive roller 32.

[0065] The motor M7 drives and rotates the spacing cam 36 via pulleys 38a, 38b and a belt 38c. The pulley 38a is fixed to the drive shaft of the motor M7, and the pulley 38b is fixed to the rotation shaft 36a of the spacing cam 36. The belt 38c is an endless belt that is stretched around the pulleys 38a, 38b. The spacing cam 36 is an eccentric cam whose center of the outer circumferential surface is eccentric from the center of the rotation shaft 36a, and rotates together with the rotation shaft 36a when driven by the motor M7.

[0066] The link member 37 is fixed to the swing shaft 37a and is provided so as to be swingable together with the swing shaft 37a. Therefore, the link member 37 rotates in synchronization with the support member 35 via the swing shaft 37a. The link member 37 is disposed so as to come into contact with the separating cam 36 when the support member 35 is biased by the compression spring 34.

[0067] When the separating cam 36 is in the phase shown in FIG. 8(a), the driven roller 33 is pressed against the drive roller 32 by the biasing force of the compression spring 34. The state shown in FIG. 8(a) is the nip position. When the separating cam 36 is rotated, for example, 180° by the motor M7 from this state, the link member 37 is pushed by the separating cam 36 and swings counterclockwise around the swing shaft 37a, as shown in FIG. 8(b). Then, the support member 35, which is connected to the link member 37 via the swing shaft 37a, swings in the same direction around the swing shaft 37a. Because the driven roller 33 is supported by the support member 35 via the rotation shaft 33a, the swing of the support member 35 separates the driven roller 33 from the drive roller 32. In other words, the driven roller 33 is moved to the nip release position.

[0068] To move the driven roller 33 from the nip release position to the nip position, the separating cam 36 is rotated another 180° by the motor M7 from the state shown in Figure 8(b). The contact / separation mechanism that brings the drive roller 32 and the driven roller 33 into and out of contact with each other may be configured to move both the drive roller 32 and the driven roller 33. In the above example, the contact / separation mechanism is driven by a motor, but the pair of conveying rollers may also be contacted and separated by another drive source such as a solenoid.

[0069] In the above example, the pair of conveying rollers 402 and 403 on the downstream side in the conveying direction X of the conveyor belt 12 are capable of contacting and separating, but only the pair of conveying rollers 402 may be capable of contacting and separating. Furthermore, the pair of conveying rollers 401 on the upstream side in the conveying direction X of the conveyor belt 12 may be capable of contacting and separating. In this case, only the pair of conveying rollers 401 on the upstream side may be capable of contacting and separating, or the pair of conveying rollers 402 on the downstream side and even the pair of conveying rollers 403 may be capable of contacting and separating.

[0070] [Sheet transport operation] Next, the sheet conveying operation in the relay conveying device 400 of this embodiment will be described. First, the control configuration of various motors and various sensors in controlling the sheet conveying operation will be described with reference to FIG. 9. The control board of the control unit 203 has a CPU (or ASIC) 230, a motor driver 231, and a sensor input circuit 232. The CPU 230 detects the sheet conveying timing and sheet jams based on output signals from sheet detection sensors 433, 434, and 435. In particular, in this embodiment, the CPU 230 controls the various motors M1 to M6 based on the output signals from the sheet detection sensors 433, 434, and 435. As described above, the motor M1 drives the conveying belt 12, the motors M2 and M3 move the pair of regulating guides 14A and 14B, the motor M4 drives the pair of conveying rollers 401, the motor M5 drives the pair of conveying rollers 402, and the motor M6 drives the pair of conveying rollers 403.

[0071] Next, a specific example of sheet conveyance control will be described using Fig. 9 to Fig. 11(d) with reference to Fig. 2 to Fig. 4 etc. In this embodiment, the control unit 203 controls the motors M2 and M3 according to the conveyance state of the sheet to change the positions of the pair of regulating guides 14A and 14B in the sheet width direction Y. As described above, by controlling the motors M2 and M3, the guide moving unit 420 (Fig. 2) can be driven to move the pair of regulating guides 14A and 14B to the guide position and the retracted position.

[0072] Here, the guide position is a position where the guide surfaces 15A of the pair of regulating guides 14A and 14B can guide the edge in the width direction Y of the sheet being conveyed while being sandwiched between the conveyor belt 12 and the spherical body 20. In this embodiment, the guide position is a position where the distance between the guide surfaces 15A of the pair of regulating guides 14A and 14B (between the guide surfaces) is longer than the length in the sheet width direction Y of the sheet being conveyed while being sandwiched between the conveyor belt 12 and the spherical body 20.

[0073] Specifically, when a sheet is conveyed with the center position of the sheet in the width direction Y aligned with the center position of the guide surfaces 15A on both sides and the edge of the sheet in the width direction Y parallel to the guide surfaces 15A (center reference), the guide position is the position where the edge of the sheet in the width direction Y and the guide surfaces 15A are spaced a predetermined distance apart. This predetermined distance can be set as appropriate by the device, but is set so that even if the sheet shifts within this distance, the misalignment between the sheet and the image formed on the sheet is acceptable. This predetermined distance is, for example, 0.5 mm. That is, at the guide position, the guide surfaces 15A of the pair of regulating guides 14A and 14B are each 0.5 mm away from the edge of the sheet in the width direction Y. The control unit 203 can change this guide position as appropriate depending on the sheet size.

[0074] In this way, the pair of regulating guides 14A and 14B are positioned at a position where the distance between the guide surfaces 15A of the pair of regulating guides 14A and 14B is longer than the length of the sheet in the sheet width direction Y. This reduces the conveying load of the sheet conveyed by the conveyor belt 12. For example, if the distance between the guide surfaces were the same as the length of the sheet in the sheet width direction Y, the sheet would be conveyed while its edge rubbing against the guide surfaces, resulting in increased conveying resistance. In particular, in this embodiment, the sheet is conveyed while being sandwiched between the conveyor belt 12 and the spherical bodies 20, and the nip pressure between the conveyor belt 12 and the spherical bodies 20 is low. Therefore, if the sheet conveying resistance is high, there is a risk of delays in sheet conveyance or conveyance problems such as sheet stoppage. Therefore, in this embodiment, the pair of regulating guides 14A and 14B are positioned at the guide position as described above to reduce the sheet conveying resistance.

[0075] It is preferable to transport the sheet with the center reference as described above and correct the side registration and side skew of the sheet (perform an alignment operation) as described below. This is because, in this embodiment, the sheet is caused to slip between the conveyor belt 12 and the spheres 20, and the side skew is corrected while the sheet is rotated. That is, by starting the alignment operation at a position where the center of gravity of the sheet S and the center of the restriction guides 14A and 14B approximately coincide (center reference), damage to the sheet during the alignment operation can be reduced.

[0076] On the other hand, the retracted position is a position where the guide surfaces 15A of the pair of regulating guides 14A, 14B are retracted from the edge of the sheet in the width direction Y relative to the guide position. In other words, the distance in the width direction Y between the guide surfaces 15A of the pair of regulating guides 14A, 14B at the retracted position is wider than the distance in the width direction Y between the guide surfaces 15A of the pair of regulating guides 14A, 14B at the guide position.

[0077] In this embodiment, the retracted position is a position where the distance between the edge of the sheet in the width direction Y and the regulating guides 14A and 14B is 5 mm, based on the above-mentioned center reference. The sheet S is delivered to the conveyor belt 12 with the regulating guides 14A and 14B in the retracted position, and in this state, the vertical movement of the sheet S is regulated by the support surface 16A and the opposing surface 17A. As a result, even if the sheet S is curled, both end edges of the sheet S can be contained within the area surrounded by the guide surface 15A, the support surface 16A, and the opposing surface 17A when the regulating guides 14A and 14B move from the retracted position to the guide position.

[0078] In this embodiment, before a sheet is handed over to the conveyor belt 12, the pair of regulating guides 14A and 14B are positioned at the retracted positions. Then, after the leading edge of the sheet is handed over to the conveyor belt 12 and the trailing edge of the sheet passes through the pair of upstream conveyor rollers, the pair of regulating guides 14A and 14B are moved from the retracted positions to the guide positions. Specifically, when the trailing edge of the sheet passes through a sheet detection sensor 433 disposed between the conveyor belt 12 and the pair of conveyor rollers 401, the pair of regulating guides start moving from the retracted positions to the guide positions. Then, the pair of regulating guides 14A and 14B guide the sheet at the guide positions, thereby correcting the side registration and side skew of the sheet.

[0079] At this time, the sheet is conveyed while being sandwiched between the conveyor belt 12 and the spherical bodies 20. The force (nipping force) that sandwiches the sheet between the conveyor belt 12 and the spherical bodies 20 is set to be weak to correct side registration and side skew of the sheet. Therefore, if the sheet abuts against at least one of the regulating guides 14A and 14B and the friction between the sheet and the regulating guide is large, the sheet may not be conveyed even when the conveyor belt 12 is driven, or the conveying speed may become extremely slow. If the sheet detection sensor 435 downstream of the conveyor belt 12 does not detect the sheet for a predetermined period of time, the control unit 203 determines that a sheet jam has occurred and stops the device. If the device stops due to the sheet abutting against the regulating guide and becoming difficult to convey, productivity will decrease.

[0080] Therefore, in this embodiment, when a sheet abuts against the regulating guide and becomes difficult to convey, the pair of regulating guides 14A and 14B are moved toward the outer position while continuing to drive the conveyor belt 12. That is, the control unit 203 performs a retraction operation if the sheet detection sensor 435 downstream of the conveyor belt 12 does not detect a sheet even after a first predetermined time has elapsed since the pair of regulating guides 14A and 14B moved from the retracted position to the guide position. The retraction operation is an operation of moving the pair of regulating guides 14A and 14B from the guide position toward the retracted position while continuing to drive the conveyor belt 12 in the sheet conveying direction. The first predetermined time (predetermined time) is, for example, 500 ms.

[0081] As a result, the regulating guide that had been in contact with the sheet is released from the sheet, and the sheet is conveyed by the conveyor belt 12. Then, the control unit 203 does not determine that a jam has occurred, and sheet conveyance continues, thereby suppressing a decrease in productivity. Note that if the sheet detection sensor 435 does not detect the sheet even after a second predetermined time has elapsed after the above-mentioned retraction operation has been performed, the control unit 203 determines that the sheet has jammed, and stops driving the conveyor belt 12. The second predetermined time may be shorter or longer than the first predetermined time, or may be the same as the first predetermined time, but is preferably set to be shorter than the first predetermined time. For example, the second predetermined time is 100 ms.

[0082] In the present embodiment, the retraction operation is performed when the sheet detection sensor 435 downstream of the conveyor belt 12 does not detect a sheet even after a first predetermined time has elapsed since the pair of regulating guides 14A and 14B moved from the retraction position to the guide position. However, the drive amount of the conveyor belt 12 may be counted instead of time. In this case, the first predetermined drive amount corresponding to the first predetermined time is 1910 pulses, and the second predetermined drive amount corresponding to the second predetermined time is 382 pulses. That is, the retraction operation is performed when the sheet detection sensor 435 downstream of the conveyor belt 12 does not detect a sheet even after the pair of regulating guides 14A and 14B moved from the retraction position to the guide position and the sheet detection sensor 435 does not detect a sheet even after the pair of regulating guides 14A and 14B moved from the retraction position to the guide position. If the sheet detection sensor 435 does not detect a sheet even after the pair of regulating guides 14A and 14B moved from the retraction position to the guide position and the second predetermined drive amount is 382 pulses, the control unit 203 determines that a sheet has jammed and stops driving the conveyor belt 12. The first predetermined drive amount and the second predetermined drive amount may be the same drive amount.

[0083] This control will be described with reference to the flowchart in Fig. 10. First, when the trailing edge of the sheet passes the upstream sheet detection sensor 433 (Yes in S1), the control unit 203 starts moving the pair of regulating guides 14A and 14B from their retracted positions to their guide positions (S2). Then, when the downstream sheet detection sensor 435 detects the sheet (Yes in S3), the control unit 203 continues driving the device (S4).

[0084] On the other hand, if the downstream sheet detection sensor 435 does not detect a sheet in S3 (No in S3), the control unit 203 determines whether a first predetermined time has elapsed since the pair of regulating guides 14A and 14B moved to the guide position (S5). If the first predetermined time has not elapsed (No in S5), the control unit 203 returns to S3. If the first predetermined time has elapsed (Yes in S5), the control unit 203 moves the pair of regulating guides 14A and 14B to the retracted position (S6). At this time, the conveyor belt 12 continues to rotate.

[0085] Next, the control unit 203 again determines whether the downstream sheet detection sensor 435 has detected a sheet (S7). If the downstream sheet detection sensor 435 has detected a sheet (Yes in S7), the control unit 203 continues driving the device (S4). On the other hand, if the downstream sheet detection sensor 435 has not detected a sheet in S7 (No in S7), the control unit 203 determines whether a second predetermined time has elapsed since the pair of regulating guides 14A and 14B moved to the retracted position (S8). If the second predetermined time has not elapsed (No in S8), the control unit 203 returns to S7. If the second predetermined time has elapsed (Yes in S8), the control unit 203 determines that a sheet jam has occurred, and stops driving all of the device, including the conveyor belt 12 and the pairs of conveyor rollers 401, 402, and 403 (S9).

[0086] The control unit 203 may also perform the following control. That is, if the downstream sheet detection sensor 435 does not detect a sheet even after a predetermined time has elapsed since the trailing edge of the sheet passed through the upstream sheet detection sensor 433, the control unit 203 may perform the retraction operation. In other words, regardless of whether the pair of regulating guides 14A and 14B have moved to the guide position, the control unit 203 may determine whether to perform the retraction operation based on the detection result of the upstream sheet detection sensor 433, depending on whether the downstream sheet detection sensor 435 detects a sheet when a predetermined time has elapsed since the trailing edge of the sheet passed through the sheet detection sensor 433. In particular, if the pair of regulating guides 14A and 14B remain in the guide position when the second or subsequent sheets are conveyed, the regulating guides 14A and 14B do not move from the retraction position to the guide position when the sheet is received by the conveyor belt 12. Therefore, in this case, the control unit 203 preferably performs the control as described above.

[0087] 11(a) to 11(d), a specific example of the operation of the pair of regulating guides 14A and 14B and the conveyance belt 12 of this embodiment when two sheets S1 and S2 are successively conveyed to the relay conveyance device 400 will be described. First, as shown in FIG. 11(a), when the first sheet S1 is conveyed from the upstream conveyance roller pair 401 to the conveyance belt 12, the control unit 203 moves the pair of regulating guides 14A and 14B to the retracted positions. This is because if the pair of regulating guides 14A and 14B are in the guide positions when the sheet S1 is delivered to the conveyance belt 12 and the sheet S1 is skewed or misaligned in the width direction Y, an edge of the sheet S1 may interfere with one of the regulating guides 14A and 14B, causing a conveyance failure of the sheet S1.

[0088] Next, as shown in FIG. 11B, the control unit 203 moves the pair of regulating guides 14A and 14B from the retracted positions to the guide positions after the trailing edge (upstream edge) of the first sheet S1 delivered from the conveying roller pair 401 to the conveying belt 12 passes through the sheet detection sensor 433. In this embodiment, the control unit 203 moves the pair of regulating guides 14A and 14B from the retracted positions to the guide positions when the sheet S1 delivered to the conveying belt 12 is within the predetermined area A (within the predetermined area in FIG. 6B). This corrects (aligns) the side registration and side skew of the sheet S1.

[0089] That is, when the sheet S1 is located upstream in the conveying direction X, the regulating guides 14A and 14B are positioned in the retracted positions, and both edge portions of the sheet S1 are separated from the guide surface 15A. Then, the sheet S1 is conveyed further downstream, and after the trailing edge of the sheet S1 passes through the pair of conveying rollers 401, the regulating guides 14A and 14B move to their guide positions. Then, the guide surface 15A is brought into contact with both edge portions of the sheet S1 in the width direction Y. When the sheet S1 abuts against the guide surface 15A, the sheet S1 is conveyed in a direction parallel to the guide surface 15A while slipping between the sheet S1 and the conveying belt 12, with its edge aligned with the guide surface 15A. This corrects the side registration and side skew of the sheet S1.

[0090] In this embodiment, the control unit 203 moves the pair of regulating guides 14A and 14B from the retracted position to the guide position while the sheet is being conveyed while being sandwiched between the conveyor belt 12 and the spheres 20. This allows correction of sheet side registration, side skew, and the like without stopping the sheet conveyance, thereby improving productivity. However, it is also possible to perform an alignment operation in which the pair of regulating guides 14A and 14B are moved from the retracted position to the guide position after temporarily stopping the sheet conveyance. In this case, although productivity decreases, it is possible to more reliably correct misalignment and the like.

[0091] 11(c), it is assumed that the sheet S1 comes into contact with and gets caught on at least one of the pair of regulating guides 14A and 14B, and the sheet is not conveyed even though the conveyor belt 12 is being driven. If the downstream sheet detection sensor 435 does not detect the sheet even after a first predetermined time has elapsed since the pair of regulating guides 14A and 14B moved to the guide position, the control unit 203 stops driving the pair of conveyor rollers 401 and 511 on the upstream side while continuing to drive the conveyor belt 12.

[0092] At this time, the leading edge of the second sheet S2 is transferred from the pair of conveying rollers 401 to the conveying belt 12, but since the sheet S2 is sandwiched between the pair of conveying rollers 401 and 511, even if the conveying belt 12 is driven, conveyance is stopped when the pair of conveying rollers 401 and 511 are stopped. Here, the pair of regulating guides 14A and 14B are positioned at the guide positions, but the sheet S2 stops at a position where it fits into a notch 19C (FIG. 6(a)) formed on the upstream side of the pair of regulating guides 14A and 14B. In other words, the first predetermined time is set to a time such that the succeeding sheet S2 stops within the notch 19C of the pair of regulating guides 14A and 14B.

[0093] That is, in this embodiment, while the first sheet S1 is being guided by the pair of regulating guides 14A and 14B, the second sheet S2 begins to enter the predetermined area A. Therefore, even when the preceding sheet S1 is caught and not being conveyed, the succeeding sheet S2 enters the predetermined area A. For this reason, even if the conveyance of sheet S1 stops or slows down, sheet S2 is made to stop within notch 19C.

[0094] As described above with reference to FIGS. 6(a) to 6(d), the cutout 19C has an inner surface 19A located outside the guide surface 15A. Therefore, even when the pair of regulating guides 14A and 14B are in the guide position, the distance between the inner surfaces 19A is wider than the distance between the guide surfaces 15A. Therefore, even if the second sheet S2 enters the predetermined area A while being skewed or displaced in the width direction Y, the edge of the sheet S2 is unlikely to interfere with the pair of regulating guides 14A and 14B. Therefore, in this embodiment, even when the second sheet S2 is conveyed at the above-described timing, sheet conveyance problems are unlikely to occur, and productivity can be improved.

[0095] On the other hand, if the downstream sheet detection sensor 435 does not detect a sheet even after a first predetermined time has elapsed since the pair of regulating guides 14A and 14B moved to the guide position, the control unit 203 moves the pair of regulating guides 14A and 14B from the guide position to the retracted position while continuing to drive the conveyor belt 12. As a result, the sheet S1 separates from the regulating guides and is conveyed by the conveyor belt 12, as shown in FIG. 11(d). Then, when the downstream sheet detection sensor 435 detects the sheet S1, the control unit 203 continues conveying the sheet as is and starts driving the pair of conveyor rollers 401 and 511 to resume conveying the sheet S2.

[0096] If the sheet detection sensor 435 does not detect a sheet even after a second predetermined time has elapsed since the pair of regulating guides 14A and 14B moved to the retracted position, it determines that the sheet is jammed, and stops driving the conveying belt 12 and other sheet conveying-related drives.

[0097] In this embodiment, even if a sheet delivered to the conveyor belt 12 comes into contact with and gets stuck on one of the pair of regulating guides 14A and 14B at the guide position, the sheet can be released by moving the pair of regulating guides 14A and 14B to the retracted position. Since the conveyor belt 12 continues to be driven, the sheet that has been released from the jam is conveyed downstream. This allows the control unit 203 to continue conveying the sheet without determining that a jam has occurred, thereby preventing a decrease in productivity.

[0098] It should be noted that sheets of different lengths may be conveyed to the relay conveying device 400. In particular, in the case of a long sheet, if it is determined whether or not to perform the evacuation operation based on the detection result of the sheet detection sensor 435 downstream of the conveying belt 12, the evacuation operation may not be performed even though the sheet is actually caught. For this reason, in this embodiment, when a long sheet such as a long sheet is conveyed, it is determined whether or not to perform the evacuation operation based on the detection result of the sheet detection sensor 436 arranged further downstream of the sheet detection sensor 435.

[0099] That is, when the length of the sheet in the conveying direction X is a first length, the control unit 203 performs the retraction operation based on the detection result of the sheet detection sensor 435 as a first detection unit. On the other hand, when the length of the sheet in the conveying direction X is a second length that is longer than the first length, the control unit 203 performs the retraction operation based on the detection result of the sheet detection sensor 436 as a second detection unit. This allows the retraction operation to be performed appropriately according to the length of the sheet.

[0100] In the above description, the pair of regulating guides 14A, 14B are moved from the guide position to the retracted position when performing the retraction operation. However, the position to which they are moved from the guide position when performing the retraction operation does not have to be the retracted position. For example, they may be moved to a position between the retracted position and the guide position, or to a position further retracted from the guide position than the retracted position.

[0101] Here, the above-mentioned retracted position is referred to as a first retracted position, and the position to which the guide guides 14A and 14B are moved during the retracting operation is referred to as a second retracted position. In this case, the guide moving unit 420 can move the pair of regulating guides 14A and 14B between the guide position and a first retracted position or a second retracted position retracted from both end edges of the sheet in the sheet width direction Y from the guide position. Furthermore, the pair of regulating guides 14A and 14B are positioned at the first retracted position before the sheet is handed over to the conveyor belt 12. Then, if the sheet detection sensor 435 does not detect a sheet even after a first predetermined time has elapsed after the pair of regulating guides 14A and 14B have moved from the first retracted position to the guide position, the control unit 203 performs a retracting operation to move the pair of regulating guides 14A and 14B from the guide position to the second retracted position while continuing to drive the conveyor belt 12 in the sheet conveying direction. In the case of a long sheet such as a long sheet, the retracting operation may be performed based on the detection result of the sheet detection sensor 436, as described above.

[0102] <Other embodiments> In the above embodiment, the control unit 203 for controlling the relay conveying device 400 is provided in the multistage feeding device 200, but these controls may also be performed by the control unit 140 of the image forming apparatus 100. Also, the relay conveying device 400 may be provided with a control unit for controlling each unit of the relay conveying device 400. Furthermore, the sheet conveying device may have a different configuration as long as it is a sheet conveying device that can shift the position of a sheet, regardless of the above-mentioned relay conveying device.

[0103] In the above-described embodiment, the pair of regulating guides 14A, 14B are moved toward the retracted position if the sheet detection sensor 435 does not detect a sheet for a first predetermined time after the pair of regulating guides 14A, 14B are moved from the retracted position to the guide position. However, the trigger for moving the pair of regulating guides 14A, 14B from the guide position to the retracted position may be the lapse of a predetermined time (first predetermined time) regardless of the detection result of the sheet detection sensor 435. In other words, once the predetermined time has elapsed since the pair of regulating guides 14A, 14B were moved to the guide position, the pair of regulating guides 14A, 14B may be moved from the guide position toward the retracted position regardless of whether the sheet detection sensor 435 detects a sheet.

[0104] Specifically, similar to the above-described embodiment, a sheet is transferred from the conveyor belt 12 with the pair of regulating guides 14A and 14B positioned at the retracted position. Then, while the sheet is being conveyed using the conveyor belt 12 and the spheres 20, the pair of regulating guides 14A and 14B are moved from the retracted position to the guide position. Next, unlike the above-described embodiment, after a first predetermined time has elapsed since the pair of regulating guides 14A and 14B were moved to the guide position, a retraction operation is performed in which the pair of regulating guides 14A and 14B move from the guide position to the retracted position while the conveyor belt 12 continues to be driven in the sheet conveying direction. This allows the sheet to continue being conveyed, thereby suppressing a decrease in productivity, even in a configuration in which the sheet detection sensor 435 is omitted.

[0105] However, even when such control is performed, it is preferable to provide a sheet detection sensor 435. Then, after a first predetermined time has elapsed since the pair of regulating guides 14A, 14B were moved to the guide position, a retraction operation is performed to move the pair of regulating guides 14A, 14B from the guide position to the retracted position, and if a sheet is not detected by the sheet detection sensor 435 even after a second predetermined time has elapsed, it is determined that a jam has occurred and the drive of the conveyor belt is stopped.

[0106] Note that if the sheet detection sensor 435 detects a sheet before the first predetermined time has elapsed since the pair of regulating guides 14A and 14B were moved to the guide position, the retraction operation may not be performed. The first and second predetermined times are the same as those described above, but may be the same as those in the example described in the above embodiment (the first predetermined time is, for example, 500 ms, and the second predetermined time is, for example, 100 ms), or may be set longer or shorter than those in this example. Similarly to the above-described case, the movement of the pair of regulating guides 14A and 14B from the guide position to the retraction position and the jam detection may be performed by counting the drive amount of the conveyor belt 12 instead of by time.

[0107] In the above embodiment, the pair of regulating guides 14A and 14B start moving to their guide positions when the trailing edge of the sheet passes the upstream sheet detection sensor 433. However, the pair of regulating guides 14A and 14B may also start moving to their guide positions when the trailing edge of the sheet passes through the pair of conveying rollers 401. For example, if the sheet detection sensor 433 is omitted or if the sheet conveying position can be determined based on the detection result of a sensor that detects the presence or absence of a sheet and is provided upstream of the pair of conveying rollers 401, the movement of the regulating guides 14A and 14B may start at this timing.

[0108] Furthermore, if the upstream conveying roller pair 401 is configured to be capable of contacting and separating, the conveying roller pair 401 may be separated after the leading edge of the sheet is transferred to the conveying belt 12 and before the trailing edge of the sheet passes through the conveying roller pair 401. That is, the contact / separation mechanism (conveying roller pair moving means) 31 described above in FIGS. 7 and 8 can also be applied to the conveying roller pair 401. The contact / separation mechanism 31 not only contacts and separates the conveying roller pair, but also moves the conveying roller pair between a nip position where a conveying force is applied to the sheet and a nip release position where the nip pressure is weaker than at the nip position. Therefore, after the leading edge of the sheet S is transferred to the conveying belt 12 and before the trailing edge of the sheet S passes through the conveying roller pair 401, the conveying roller pair 401 may be moved to the nip release position where the nip pressure is weaker.

[0109] In this case, the pair of regulating guides 14A and 14B start moving to their guide positions when the pair of conveying rollers 401 is separated by the contact / separation mechanism 31 (when the sheet moves from the nip position to the nip release position). In short, the timing at which the pair of regulating guides 14A and 14B start moving can be set appropriately as long as the pair of regulating guides 14A and 14B can reach their guide positions after the sheet is no longer in contact with the pair of conveying rollers 401. Note that the nip release position corresponds to a state in which the pair of conveying rollers are separated, and a state in which the pair of conveying rollers are in contact with each other but the nip pressure is lower than when the sheet is being conveyed. [Explanation of symbols]

[0110] 12... conveyor belt / 12A... conveying surface / 14A, 14B... regulating guide / 20... sphere / 200... multi-stage feeding device / 203... control unit / 400... relay conveying device (sheet conveying device) / 401... conveying roller pair (conveying member) / 420... guide moving unit (guide moving means) / 433... sheet detection sensor (upstream side detection means) / 435... sheet detection sensor (detection means, first detection means, downstream side detection means) / 436... sheet detection sensor (detection means, second detection means, downstream side detection means)

Claims

1. a conveyor belt that conveys the sheet in a conveyance direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, and regulating skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; a detection unit that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; a control unit that is capable of performing a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to drive in the direction of conveying the sheet, if the detection means does not detect the sheet even after a predetermined time has elapsed after the conveying belt has received the sheet and moved the pair of regulating guides from the receiving position to the regulating position.

2. the predetermined time is a first predetermined time, the control unit stops driving the conveyor belt when the detection unit does not detect a sheet even after a second predetermined time has elapsed after the retraction operation.

2. The sheet transport device according to claim 1.

3. the detecting means is a first detecting means, a second detection means for detecting the presence or absence of a sheet downstream of the first detection means in the conveying direction, The control unit When the length of the sheet in the conveying direction is a first length, the retracting operation is performed based on the detection result of the first detection means; When the length of the sheet in the conveying direction is a second length that is longer than the first length, the retracting operation is performed based on the detection result of the second detection means.

3. The sheet conveying device according to claim 1, wherein the sheet conveying device is a sheet conveying device.

4. further comprising an upstream detection means for detecting the presence or absence of a sheet on the upstream side of the conveying belt in the conveying direction, the control unit moves the pair of regulating guides to the regulating position after the trailing edge of the sheet has passed the upstream detection unit.

4. The sheet transport device according to claim 1, wherein the sheet transport device is a sheet conveying device.

5. a conveyor belt that conveys the sheet in a conveyance direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, the regulating guides correcting skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; an upstream detection means for detecting the presence or absence of a sheet on the upstream side of the conveying belt in the conveying direction; a downstream detection means for detecting the presence or absence of a sheet downstream of the conveying belt in the conveying direction; a control unit that moves the pair of regulating guides to the regulating position after the trailing end of the sheet has passed the upstream detection means, and if the downstream detection means does not detect the sheet even after a predetermined time has elapsed since the trailing end of the sheet has passed the upstream detection means, performs a retraction operation to move the pair of regulating guides from the regulating position in a direction toward the receiving position while the conveying belt continues to drive in the direction of conveying the sheet.

6. a conveyor belt that conveys the sheet in a conveyance direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, and regulating skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; a detection unit that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; a control unit that is capable of performing a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the direction of conveying the sheet, when the detection means does not detect the sheet even after the conveying belt continues to be driven in the conveying direction for a predetermined amount after the conveying belt has received the sheet and moved the pair of regulating guides from the receiving position to the regulating position.

7. A conveyor belt that conveys the sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, and regulating skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; a detection unit that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; a control unit that can execute a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the sheet conveying direction, when the detection unit does not detect the sheet even after a predetermined time has elapsed after the conveying belt receives the sheet and moves the pair of regulating guides from the receiving position to the regulating position; an image forming unit that forms an image on the sheet conveyed by the conveyor belt; An image forming system comprising:

8. A conveyor belt that conveys the sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, the regulating guides correcting skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; an upstream detection means for detecting the presence or absence of a sheet on the upstream side of the conveying belt in the conveying direction; a downstream side detection means for detecting the presence or absence of a sheet downstream of the conveying belt in the conveying direction; and a control unit for moving the pair of regulating guides to the regulating position after the trailing edge of the sheet has passed the upstream side detection means, and for executing a retraction operation for moving the pair of regulating guides from the regulating position in a direction toward the receiving position while the conveying belt continues to be driven in the sheet conveying direction if the downstream side detection means does not detect the sheet even after a predetermined time has elapsed since the trailing edge of the sheet has passed the upstream side detection means. an image forming unit that forms an image on the sheet conveyed by the conveyor belt; An image forming system comprising:

9. A conveyor belt that conveys the sheet in a conveying direction; a plurality of spheres arranged along the conveying direction and rotatable together with the sheet conveyed by the conveyor belt; a holding mechanism that holds the sphere and allows the sphere to rotate in any direction while rubbing against a portion of the surface of the sphere; a pair of regulating guides provided on both sides of the conveying belt in a sheet width direction intersecting the conveying direction and movable in the sheet width direction, and regulating skew of the sheet when an edge in the sheet width direction of the sheet conveyed by the conveying belt and the spherical body abuts against each other; a restriction guide moving mechanism that moves the pair of restriction guides between a receiving position that receives a sheet and a restriction position where the distance between the pair of restriction guides is narrower than the distance between the pair of restriction guides at the receiving position and where the skew of the sheet is restricted when the edge of the sheet abuts against the guides; a detection unit that detects the presence or absence of a sheet downstream of the conveying belt in the conveying direction; a control unit that is capable of executing a retraction operation to move the pair of regulating guides from the regulating position toward the receiving position while the conveying belt continues to be driven in the sheet conveying direction, when the detection unit does not detect the sheet even if the conveying belt continues to be driven in the sheet conveying direction for a predetermined amount after the conveying belt receives the sheet and moves the pair of regulating guides from the receiving position to the regulating position; an image forming unit that forms an image on the sheet conveyed by the conveyor belt; An image forming system comprising:

Images