Sheet transport device and image forming device

Abstract

To provide a sheet transport device that enables easy removal of sheets that have stopped moving during transport when an abnormality causing sheet transport stoppage occurs along the transport path.SOLUTION: When a sheet P is being normally conveyed along the conveying path, first and second actuators 91, 92 are controlled so that the nip pressure of fourth and fifth conveying roller pairs 34, 35 becomes a reference value. When an abnormality occurs in the conveying path such that the conveyance of the sheet P stops, the first and second actuators are controlled so that the nip pressure of the fifth conveying roller pair 35, out of the fourth and fifth conveying roller pairs 34, 35, which holds the sheet P and corresponds to one manually operated knob 72 out of the multiple manually operated knobs 71, 72, becomes larger than the reference value. The nip pressure of the fourth conveying roller pair 34, which holds the sheet P and corresponds to one manually operated knob 71 that is not manually operated out of the multiple manually operated knobs 71, 72, becomes equal to or less than the reference value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device that conveys a sheet, and an image forming apparatus including the same. [Background technology]

[0002] Conventionally, in image forming devices such as copiers and printers, a technique has been known in which multiple pairs of conveying rollers are installed at intervals along a conveying path formed by a pair of conveying guide members, and a sheet is conveyed by the multiple pairs of conveying rollers (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technology in which a conveying force of a pair of conveying rollers (a pair of registration rollers) is set to be weak when conveying a sheet so that the sheet is pushed against a registration plate to correct the skew of the sheet, and the conveying force is set to be strong when conveying the sheet toward the transfer nip after the skew correction. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional sheet transport devices, when a sheet stops being transported (jams) along the transport path, a manual operation unit (operation knob) is manually operated to remove the stopped sheet, rotating the pair of transport rollers and moving the sheet to a position where it is no longer sandwiched in the nip. However, this manual operation is not simple, and problems such as the sheet slipping occur.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a sheet conveying device and an image forming device that can easily remove a sheet that has stopped being conveyed when an abnormality occurs in the conveying path, causing the sheet to stop being conveyed. [Means for solving the problem]

[0006] The sheet transport device of this invention comprises a pair of transport guide members arranged opposite each other with a gap therebetween, forming a transport path in the gap along which the sheet is transported; a plurality of transport roller pairs arranged at intervals in the transport direction on the transport path, and rotating along the transport direction to sandwich and transport the sheet; a plurality of manually operated members for manually rotating each of the plurality of transport roller pairs; and a nip pressure variable means capable of separately increasing or decreasing the nip pressure of each of the plurality of transport roller pairs, wherein the nip pressure variable means controls the nip pressure to be a reference value when the sheet is being transported normally on the transport path, and when an abnormality occurs in which the sheet stops being transported on the transport path, the nip pressure of a transport roller pair among the plurality of transport roller pairs that sandwiches the sheet and that corresponds to one manually operated member of the plurality of manually operated members is controlled to be greater than the reference value, and the nip pressure of a transport roller pair that sandwiches the sheet and that corresponds to one manually operated member of the plurality of manually operated members is controlled to be equal to or less than the reference value. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a sheet conveying device and an image forming device that can easily remove a sheet that has stopped being conveyed when an abnormality occurs in the conveying path causing the sheet to stop being conveyed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a configuration of a sheet conveying device. [Figure 3] 10A and 10B are diagrams illustrating a state in which a sheet jam occurs in a conveying path of the sheet conveying device. [Figure 4] 1A is a schematic diagram showing the operation of the sheet conveying device in a normal state, and FIG. 1B is a schematic diagram showing the operation of the sheet conveying device when a jam occurs. [Figure 5] 10A and 10B are schematic diagrams illustrating an operation in which the transport guide member is moved when a jam occurs. [Figure 6] 10 is a flowchart illustrating an example of control when a jam occurs. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. 1, an intermediate transfer belt 8 is installed above the center of the image forming apparatus 1. Photosensitive drums 2Y, 2M, 2C, and 2K (imaging units) corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged side by side facing the intermediate transfer belt 8. Furthermore, the intermediate transfer belt 8 is pressed against a secondary transfer roller 15 (secondary transfer belt 16) below it, forming a secondary transfer nip as an image forming unit.

[0011] 1, a charging unit 3, a developing unit 4, a cleaning unit 5, a discharging unit, etc. are arranged around the photosensitive drum 2K corresponding to black. Then, an image creation process (charging process, exposure process, developing process, transfer process, cleaning process, discharging process) is carried out on the photosensitive drum 2K, and a black image is formed on the surface of the photosensitive drum 2K.

[0012] The other three photosensitive drums 2Y, 2M, and 2C have substantially the same configuration around them, and images corresponding to the respective toner colors are formed on the surfaces of the photosensitive drums 2Y, 2M, and 2C. Below, we will omit the description of the image formation process on the other three photosensitive drums 2Y, 2M, and 2C as appropriate, and will only describe the image formation process corresponding to black.

[0013] The photosensitive drum 2K is rotated by a main motor in the counterclockwise direction in Fig. 1. Then, at the position of the charging unit 3, the surface of the photosensitive drum 2K is uniformly charged (charging step). Thereafter, the surface of the photosensitive drum 2K reaches the irradiation position of the laser light emitted from the exposure unit 7, and an electrostatic latent image corresponding to black is formed by exposure scanning in the width direction (the direction perpendicular to the paper surface of Figure 1, which is the main scanning direction) at this position (this is the exposure process).

[0014] Thereafter, the surface of the photosensitive drum 2K reaches a position facing the developing unit 4, where the electrostatic latent image is developed to form a black toner image (developing step). Thereafter, the surface of the photosensitive drum 2K reaches a position facing the intermediate transfer belt 8 and the primary transfer roller 6, and at this position the toner image formed on the surface of the photosensitive drum 2K is primarily transferred onto the surface of the intermediate transfer belt 8 (the primary transfer step). At this time, a small amount of untransferred toner remains on the photosensitive drum 2K.

[0015] Thereafter, the surface of the photosensitive drum 2K reaches a position facing the cleaning unit 5, and at this position, the untransferred toner remaining on the photosensitive drum 2K is collected into the cleaning unit 5 by a cleaning blade (cleaning process). Finally, the surface of the photosensitive drum 2K reaches a position facing the charge removal unit, where the residual potential on the photosensitive drum 2K is removed. Thus, the series of image forming processes performed on the photosensitive drum 2K is completed.

[0016] The above-described image forming process is performed on the surfaces of the other photosensitive drums 2Y, 2M, and 2C in the same manner as on the black photosensitive drum 2K. Then, the toner images of each color formed on the surface of each photosensitive drum 2Y, 2M, 2C, and 2K are primarily transferred onto the intermediate transfer belt 8 in a superimposed manner. In this way, a color image is formed on the intermediate transfer belt 8.

[0017] Thereafter, the intermediate transfer belt 8, onto which the toner images of each color have been primarily transferred in a superimposed state, reaches a position facing a secondary transfer roller 15 (secondary transfer belt 16). At this position, a secondary transfer nip (image forming portion) is formed between the secondary transfer opposing roller 9 and the secondary transfer roller 15, sandwiching the intermediate transfer belt 8 and the secondary transfer belt 16. The four-color toner images formed on the intermediate transfer belt 8 are then secondarily transferred onto a sheet P, such as paper, that has been transported to the position of this secondary transfer nip (secondary transfer process). At this time, untransferred toner that has not been transferred to the sheet P remains on the intermediate transfer belt 8.

[0018] Thereafter, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning unit, where untransferred toner and other adhering matter adhering to the surface of the intermediate transfer belt 8 is removed. Thus, the series of transfer processes performed on the intermediate transfer belt 8 is completed.

[0019] Referring to Figure 1, the sheet P transported to the position of the secondary transfer nip (image forming section) is transported from a paper feed section 10 arranged below the image forming apparatus 1 via a transport path K1 on which a paper feed roller 11, a registration roller 12, etc. are arranged. More specifically, a plurality of sheets P such as paper are stacked and stored in the paper feed unit 10. When the paper feed roller 11 is rotated counterclockwise in FIG. 1, the topmost sheet P is fed toward the registration rollers 12 via the first and third conveying paths K1 and K3 (or the second and third conveying paths K2 and K3).

[0020] The sheet P conveyed to the registration rollers 12 is temporarily stopped at the roller nip of the registration rollers 12, which have stopped rotating. Then, the registration rollers 12 are rotated in synchronization with the color image on the intermediate transfer belt 8, and the sheet P is conveyed toward the secondary transfer nip (image forming unit). In this way, the desired color image is transferred onto the sheet P.

[0021] Thereafter, the sheet P onto which the color image has been transferred at the secondary transfer nip position is conveyed by the secondary transfer belt 16, and after being separated from the secondary transfer belt 16, is conveyed by the conveying belt 18 to the position of the fixing unit 19. Then, at this position, the color image transferred onto the surface is fixed onto the sheet P by the heat and pressure of the fixing belt and pressure roller (the fixing process). Thereafter, the sheet P passes through a fourth transport path K4 and is discharged to the outside of the image forming apparatus 1 by a paper discharge roller 25. In this way, a series of image forming processes (image forming operations) in the image forming apparatus 1 is completed.

[0022] 1, when a "double-sided print mode" is selected in which printing is performed on both sides (front and back sides) of a sheet P, the sheet P, after the fixing process on the front side thereof, is guided to a fifth conveying path K5 (a vertical conveying path) by the operation of a switching claw, without being discharged directly from the image forming apparatus 1 as in the above-described "single-sided print mode." The sheet P guided to the fifth conveying path K5 is then guided to a sixth conveying path K6 by the operation of a switching claw. The sheet P guided to the sixth conveying path K6 then has its conveying direction reversed, and is then guided to an eighth conveying path K8 (double-sided conveying path) by the operation of a switching claw. The sheet P guided to the eighth conveying path K8 is then transported again via the third conveying path K3 toward the position of the secondary transfer nip (image forming unit). Then, an image is formed on the back side of the sheet P at the position of the secondary transfer nip using an image formation process (image formation operation) similar to that described above, and the sheet then undergoes a fixing process in the fixing section 19 and is discharged from the image forming device 1 via the fourth conveying path K4.

[0023] Furthermore, when a "reverse discharge mode" is selected in which the sheet P is discharged with its front and back sides reversed, the sheet P, after the fixing process on its front side (or both sides) has been completed, is guided to the fifth conveying path K5 (vertical conveying path) by the operation of the switching claw, without being discharged directly from the image forming apparatus 1. Then, the leading edge of the sheet P guided to the fifth conveying path K5 is guided to the sixth conveying path K6 by the operation of the switching claw. Then, after the sheet P guided to the sixth conveying path K6 has its conveying direction reversed, the sheet P is guided to the fourth conveying path K4 (discharge conveying path) via the fifth conveying path K5 (vertical conveying path) by the operation of the switching claw. Then, the inverted sheet P is discharged from the image forming apparatus 1 via the fourth conveying path K4. The "single-sided print mode," "double-sided print mode," and "reverse discharge mode" are selected by the user through operation of the operation display panel 95 (installed on the exterior of the image forming apparatus 1).

[0024] In addition, the image forming apparatus 1 in this embodiment is provided with a purge section 60 adjacent to the paper feed section 10 for storing sheets P (sheets that could not be printed or ejected normally) that have become stuck within the image forming apparatus 1. Of the sheets P that are stuck in the transport path within the image forming apparatus 1 due to a jam or the like, all sheets P that can secure a transport path to the purge section 60 will be transported toward the purge section 60 by driving the transport roller pair. After being guided to the fifth transport path K5, such sheets P are stacked in the purge section 60 via the seventh transport path K7 (purge transport path) by the operation of the switching claw. Then, the sheets P stacked in the purge section 60 are removed from the purge section 60 by the user at an appropriate timing.

[0025] The sheet conveying device 30, which is a feature of the image forming apparatus 1 according to the present embodiment, will be described in detail below. Referring to FIG. 1, the image forming apparatus 1 in this embodiment is provided with a sheet conveying device 30 in which first and second conveying paths K1, K2 along which sheets P fed from two paper feed sections 10 are conveyed and an eighth conveying path K8 (double-sided conveying path) converge to form a third conveying path K3 after the merging. 2 to 5, the sheet transport device 30 is provided with transport guide plates 81 and 82 as a pair of transport guide members, a plurality of transport roller pairs 31 to 38, a plurality of sheet detection sensors 41 to 48, and the like.

[0026] The pair of transport guide plates 81, 82 (transport guide members) are arranged to face each other with a gap therebetween, and a transport path along which the sheet P is transported is formed in the gap. Each of the four transport paths K1 to K3 and K4 is formed by a pair of transport guide plates (including a plurality of pairs of transport guide plates connected in the transport direction). Of these pairs of transport guide plates (transport guide members), at least one pair of transport guide plates 81 and 82 forms a curved transport path (see FIG. 5(A)). For simplicity, FIG. 4 illustrates the curved transport path as a straight line.

[0027] The conveying roller pairs 31 to 38 are arranged at intervals in the conveying direction on the conveying paths K1 to K3, K8, and rotate along the conveying directions K1 to K3, K8 to sandwich and convey the sheet P. Each of the conveying roller pairs 31 to 38 has a nip formed by pressure contact between a drive roller (see drive rollers 34a and 35a in FIG. 4) to which a driving force is transmitted from a drive mechanism (not shown) and a driven roller (see driven rollers 34b and 35b in FIG. 4) that rotates in response to the rotation of the drive roller. The conveying rollers rotate while sandwiching the sheet P in the nip, thereby conveying the sheet P.

[0028] The sheet detection sensors 41 to 48 are installed at intervals in the conveying direction on the conveying paths K1 to K3 and K8. The sheet detection sensors 41 to 48 are configured to be able to detect whether or not there is an abnormality in which the sheet P stops being conveyed (jams) on the conveying paths K1 to K3 and K8, and the position where the abnormality occurs (jam position). For example, if the sheet P jams at the position of the eighth transport path K8 shown in Fig. 3A, the sixth sheet detection sensor 46 installed on the eighth transport path K8 will detect this state. Specifically, only the signal of the sixth sheet detection sensor 46 changes from on to off (or from off to on), and the signals of the other sheet detection sensors 41 to 45 remain off (or on). 3B, the second to fifth sheet detection sensors 42 to 45 installed on the second and third transport paths K2 and K3 detect this state. Specifically, the signals of the second to fifth sheet detection sensors 42 to 45 change from on to off (or from off to on), while the signals of the other sheet detection sensors 41 and 46 remain off (or on). As the sheet detection sensors 41 to 48, reflective photosensors that optically detect the presence or absence of the sheet P at that position can be used.

[0029] 1, the sheet conveying device 30 in this embodiment is provided with an opening / closing door 100 that can expose the conveying paths K1 to K3 and K8. When a sheet P jams on the conveying paths K1 to K3 and K8, the user opens the closed door 100 to expose the conveying paths K1 to K3 and K8, and then inserts his / her hand through the door to operate the manual operation knob 72 and guide operation lever 94 described below, and then grasps and removes the sheet P (jam clearance) in order to remove the jammed sheet P from the conveying paths K1 to K3 and K8.

[0030] Here, the sheet conveying device 30 in this embodiment is provided with a plurality of manual operation knobs (see manual operation knobs 71 and 72 in FIG. 4) as manual operation members for manually rotating the plurality of conveying roller pairs 31 to 38, respectively. 4, the manually operated knobs 71 and 72 (manually operated members) are connected to the axial ends of the shafts of the driven rollers 34b and 35b (positions that do not interfere with the conveyance of the sheet P). When a jam occurs, the user can grasp the manually operated knobs 71 and 72 and rotate them clockwise in FIG. 4B to manually convey the sheet P held in the nip of the fifth conveying roller pair 35 in the direction of the arrow in FIG. 4B (to the right), and remove the sheet P with its trailing edge ejected from the nip. Although FIG. 4 shows the state in which the manual operation knobs 71 and 72 are provided on the fourth and fifth conveying roller pairs 34 and 35, the other conveying roller pairs 31 to 33 and 36 to 38 also have manual operation knobs provided thereon.

[0031] Furthermore, the sheet conveying device 30 in this embodiment is provided with a plurality of actuators (see first and second actuators 91 and 92 in FIG. 4) as nip pressure varying means that can increase or decrease the nip pressure of each of the plurality of conveying roller pairs 31 to 38 separately. More specifically, the multiple actuators (nip pressure varying means) are configured to be able to separately move multiple driven rollers (see driven rollers 34b, 35b in FIG. 4) provided in each of the multiple conveying roller pairs 31 to 38. The actuators 91, 92 are capable of moving the driven rollers 34b, 35b in directions toward and away from the drive rollers 34a, 35a (the up and down directions in FIG. 4), and may be, for example, those using a solenoid mechanism or a rack and pinion mechanism. Note that while Figure 4 illustrates first and second actuators 91 and 92 that move the driven rollers 34b and 35b of the fourth and fifth conveying roller pairs 34 and 35, respectively, actuators are also installed that move the driven rollers of the other conveying roller pairs 31 to 33 and 36 to 38, respectively.

[0032] Referring to FIG. 4(A), when the sheet P is being transported normally in the transport path without jamming, the multiple actuators 91, 92 (nip pressure variable means) are controlled by the control unit 90 so that the nip pressures of the multiple transport roller pairs 34, 35 (the contact pressures of the driven rollers 34b, 35b against the drive rollers 34a, 35a) each become a reference value A.

[0033] In contrast, when an abnormality occurs in which sheet P stops being conveyed (jams) in the conveying path, the multiple actuators 91, 92 (nip pressure variable means) are controlled by the control unit 90 so that the nip pressure of the conveying roller pair 35, among the multiple conveying roller pairs 34, 35, which holds the jammed sheet P and corresponds to one manually operated knob 72, among the multiple manually operated knobs 71, 72 (manually operated members), becomes larger than a reference value A, and the control unit 90 controls so that the nip pressure A of the conveying roller pair 34, which holds the sheet P and corresponds to one manually operated knob 71, 72, among the multiple manually operated knobs 71, 72, which is not manually operated, becomes equal to or less than the reference value. In detail, in this embodiment, the conveying roller pair 34 corresponding to the manual operation knob 71 that is not manually operated has the drive roller 34a and driven roller 34b that constitute the conveying roller pair separated by the first actuator 91 so that the nip pressure becomes zero (the driven roller 34b is separated from the drive roller 34a in the direction of the arrow in Figure 4).

[0034] More specifically, based on the detection results of the multiple sheet detection sensors 41 to 45, one of the multiple manually operated knobs (manually operated members) is determined to be manually operated (in the example of Figure 4, this is the manually operated knob 72 of the fifth conveying roller pair 35), and the first and second actuators 91, 92 (nip pressure variable means) are controlled. In this embodiment, the opening operation of the door 100 (see FIG. 1) is used as a trigger to control a plurality of actuators (nip pressure varying means). In the example of Fig. 4, when the control unit 90 determines that a jammed sheet P is sandwiched between the fourth and fifth conveyor roller pairs 34, 35 based on the detection results of the multiple sheet detection sensors 41 to 45, the control unit 90 selects a procedure for manually operating the manual operation knob 72 of the fifth conveyor roller pair 35 to remove the jammed sheet P. Then, when the door detection sensor 93 optically detects that the opening of the opening / closing door 100 is open, the second actuator 92 moves the driven roller 35b corresponding to the manually operated manual operation knob 72 in a direction (upward in Fig. 4) that increases the nip pressure with the drive roller 35a. This increases the sheet conveying force (grip force) of the fifth conveyor roller pair 35 when the manual operation knob 72 is manually rotated. In response to this, the driven roller 34b corresponding to the manually operated knob 71 that is not manually operated is moved in a direction (downward in FIG. 4) away from the drive roller 35a by the first actuator 91. This reduces the resistance generated at the nip of the fourth conveying roller pair 34 when the manually operated knob 72 is manually rotated (reducing the resistance to almost zero).

[0035] As described above, in the sheet conveying device 30 of this embodiment, when a jam occurs, the manual operation knob 72 is manually operated to remove the jammed sheet P, and the conveying roller pairs 35 are rotated to move the sheet P to a position where it is not sandwiched in the nip. In this case, the nip pressure of the conveying roller pair 35 corresponding to the one manually operated manual operation knob 72 is made higher than normal, and the other conveying roller pairs 34 are placed in a separated state. Therefore, compared to manually operating one manual operation knob 72 to move the sheet P sandwiched between all the conveying roller pairs 34, 35 to a position where it is not sandwiched in the nip, this manual operation can be performed easily with little resistance. This reduces problems such as the sheet P slipping during manual operation, making jam clearance easier. In particular, in the sheet conveying device 30 of this embodiment, three conveying paths K1, K2, and K8 merge into one conveying path K3, forming a curved conveying path, so jams are more likely to occur than in a device consisting of only one linear conveying path. For this reason, the configuration of the present invention is useful.

[0036] Referring to Figure 5, in this embodiment, a pair of transport guide plates 81, 82 (transport guide members) are configured to be movable approximately parallel to one transport guide plate 82 in a direction in which the other transport guide plate 81 widens the gap. More specifically, a guide operating lever 94 is connected to the other conveying guide plate 81, which is movable in a direction away from the one conveying guide plate 82 (the direction of the arrow in FIG. 8(B)). When a user removes a jammed sheet P in this curved conveying path, the user manually operates the guide operating lever 94 to move the conveying guide plate 81, which is in the reference position in FIG. 5(A), to the separated position shown in FIG. 5(B). Then, in the widened gap, the user manually operates the manual operation knob 72, which was previously described in FIG. 4(B), to easily remove the jammed sheet P. The guide operating lever 94 may be, for example, one that uses a hinge mechanism.

[0037] An example of control when a jam occurs will be described with reference to FIG. First, whether or not a jam has occurred in the sheet conveying device 30 is determined based on the detection results of the plurality of sheet detection sensors 41 to 45 (step S1). As a result, if a jam occurs, the location of the jam is identified, and one manually operated knob (in the example of Figure 4, the manually operated knob 72 for the fifth conveying roller pair 35) to be manually operated when clearing the jam is determined (step S2). Thereafter, the jam clearance procedure (including how to open the opening / closing door 100, the guide operation lever and 94 manual operation knobs to be manually operated thereafter, and how to operate them) is displayed on the operation display panel 95 (see FIG. 1) (step S3).The user then performs jam clearance based on this display. Thereafter, it is determined whether the door 100 is open (the door detection sensor 93 (see FIG. 4) has an ON signal) (step S4), and when it is determined that the door 100 is open, the actuator is controlled to be driven (step S5). In the example of FIG. 4, the second actuator 92 increases the nip pressure of the fifth conveying roller pair 35, and the first actuator 91 separates the fourth conveying roller pair 34. Furthermore, the transport guide plate 81 (guide operation lever 94) is moved away (step S6), and once the completion of jam clearance is confirmed (step S7), this flow ends. Whether or not the guide operating lever 94 has been operated to separate can be detected by providing a sensor that optically detects the transport guide plate 81 in the separated position. Furthermore, whether or not jam clearance has been completed can be determined from changes in the signals of the plurality of sheet detection sensors 41-45.

[0038] As described above, the sheet conveying device 30 in this embodiment is provided with a pair of conveying guide plates 81, 82 that are arranged facing each other with a gap therebetween and that form a conveying path in the gap along which the sheet P is conveyed. Also, a plurality of conveying roller pairs 31-38 that rotate along the conveying direction in the conveying paths K1-K3, K8 to sandwich and convey the sheet P are arranged at intervals in the conveying direction. Also provided are a plurality of manual operation knobs 71, 72 (manual operation members) that manually rotate the plurality of conveying roller pairs 34, 35, respectively, and first and second actuators 91, 92 (nip pressure varying means) that can separately increase or decrease the nip pressure of each of the plurality of conveying roller pairs 34, 35. When the sheet P is being transported normally along the transport path, the first and second actuators 91, 92 are controlled so that the nip pressure becomes a reference value, and when an abnormality occurs in the transport path that causes the sheet P to stop being transported, the nip pressure of the fifth transport roller pair 35, among the multiple transport roller pairs 34, 35, which holds the sheet P and corresponds to one manually operated knob 72 among the multiple manually operated knobs 71, 72, is controlled to be greater than the reference value, and the nip pressure of the transport roller pair 34, which holds the sheet P and corresponds to one manually operated knob 71 among the multiple manually operated knobs 71, 72, which is not manually operated, is controlled to be equal to or less than the reference value. This allows easy removal of the stopped sheet P when an abnormality occurs in which the sheet P stops being conveyed (jams) on the conveying paths K1 to K3 and K8.

[0039] In this embodiment, the present invention is applied to a sheet conveying device 30 installed in a color image forming apparatus 1, but the present invention can naturally also be applied to a sheet conveying device installed in a monochrome image forming apparatus. Furthermore, in this embodiment, the present invention is applied to a sheet conveying device 30 installed in an electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and the present invention can naturally also be applied to a sheet conveying device installed in other types of image forming apparatus (for example, an inkjet type image forming apparatus, a stencil printing apparatus, etc.). Furthermore, in this embodiment, the present invention is applied to a sheet conveying device 30 in which four conveying paths K1 to K3, K8 are provided near the paper feed section 10, but the present invention can naturally also be applied to other sheet conveying devices. Furthermore, in the sheet conveying device 30 of this embodiment, the number and positions of the conveying guide plates 81, 82 as a pair of conveying guide members, the plurality of pairs of conveying rollers 31 to 38, and the plurality of sheet detection sensors 41 to 48 are not limited to those shown in Figure 2, and can be set to various numbers and positions. Furthermore, in this embodiment, when a jam occurs, the actuator (nip pressure variable means) is configured to change the pair of conveying rollers corresponding to the manual operation knob (manual operation member) that is not manually operated from a contact state to a separated state, but it is also possible to configure the pair of conveying rollers corresponding to the manual operation knob (manual operation member) that is not manually operated to reduce the nip pressure rather than completely separating them. 4, the present embodiment has been described with reference to the example in which the sheet P is sandwiched between two pairs of conveying rollers 34 and 35 when a jam occurs, but the present invention can also be applied to cases in which the sheet P is sandwiched between three or more pairs of conveying rollers when a jam occurs (for example, the case shown in FIG. 3(B)). In such cases, the nip pressure of one pair of conveying rollers is increased by the nip pressure varying means, and the nip pressures of the other two or more pairs of conveying rollers are reduced (including when they are separated). Even in such cases, the same effects as those of this embodiment can be obtained.

[0040] It is to be noted that the present invention is not limited to the present embodiment, and it is clear that the present embodiment can be appropriately modified within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components can be any number, position, shape, etc. that is suitable for implementing the present invention.

[0041] In this specification, the term "sheet" is not limited to paper, but is defined to include all sheet-like recording media, such as coated paper, label paper, and OHP sheets.

[0042] The present invention can also be embodied in a combination of Supplementary Notes 1 to 8, as follows. (Appendix 1) a pair of conveying guide members arranged to face each other with a gap therebetween, and forming a conveying path in the gap along which the sheet is conveyed; a plurality of pairs of conveying rollers that are arranged at intervals in the conveying direction on the conveying path and rotate along the conveying direction to sandwich and convey the sheet; a plurality of manual operation members for manually rotating the plurality of conveying roller pairs, respectively; a nip pressure varying means for separately increasing or decreasing the nip pressure of each of the plurality of conveying roller pairs; Equipped with The nip pressure varying means is When the sheet is normally conveyed through the conveying path, the nip pressure is controlled to be a reference value, When an abnormality occurs in the conveying path that causes the sheet to stop being conveyed, the nip pressure of the conveying roller pair among the plurality of conveying roller pairs that holds the sheet and that corresponds to one manually operated member among the plurality of manually operated members is controlled to be greater than the reference value, and the nip pressure of the conveying roller pair that holds the sheet and that corresponds to one manually operated member among the plurality of manually operated members is controlled to be equal to or less than the reference value. (Appendix 2) a plurality of sheet detection sensors capable of detecting the presence or absence of the abnormality and the position where the abnormality has occurred are installed on the conveyance path; The sheet conveying device described in Appendix 1, characterized in that one manually operated member among the plurality of manually operated members is determined based on the detection results of the plurality of sheet detection sensors, and the nip pressure variable means is controlled. (Appendix 3) The sheet conveying device described in Appendix 1 or Appendix 2, characterized in that the conveying roller pair corresponding to the manual operation member that is not manually operated has a drive roller and a driven roller that constitute the conveying roller pair separated so that the nip pressure is zero. (Appendix 4) a door that can open and close to expose the transport path; 4. The sheet conveying device according to claim 1, wherein the nip pressure varying means is controlled by using an opening operation of the door as a trigger. (Appendix 5) Each of the plurality of conveying roller pairs includes a drive roller and a driven roller, 5. The sheet conveying device according to claim 1, wherein the nip pressure varying means is a plurality of actuators capable of moving the plurality of driven rollers separately. (Appendix 6) 6. The sheet transport device according to claim 1, wherein the pair of transport guide members form a curved transport path. (Appendix 7) The sheet conveying device according to any one of Supplementary Notes 1 to 6, wherein the pair of conveying guide members are configured so that one conveying guide member can move relative to the other conveying guide member in a direction that widens the gap. (Appendix 8) An image forming apparatus comprising the sheet conveying device according to any one of Supplementary Notes 1 to 7. [Explanation of symbols]

[0043] 1. Image forming device, 30 sheet transport device, 31 to 38 conveying roller pairs, 34a, 35a drive rollers, 34b, 35b driven rollers, 41 to 46 sheet detection sensors (detection means), 71, 72 manual operation knob (manual operation member), 81, 82 transport guide plates (transport guide members), 91 first actuator (nip pressure variable means), 92 second actuator (nip pressure variable means), 100 opening and closing doors, K1~K8 transport route, P seat. [Prior art documents] [Patent documents]

[0044] [Patent Document 1] Japanese Patent Application Publication No. 5-319617

Claims

1. a pair of conveying guide members arranged to face each other with a gap therebetween, and forming a conveying path in the gap along which the sheet is conveyed; a plurality of pairs of conveying rollers that are arranged at intervals in the conveying direction on the conveying path and rotate along the conveying direction to sandwich and convey the sheet; a plurality of manual operation members for manually rotating the plurality of conveying roller pairs, respectively; a nip pressure varying means for separately increasing or decreasing the nip pressure of each of the plurality of conveying roller pairs; Equipped with The nip pressure varying means is When the sheet is normally conveyed through the conveying path, the nip pressure is controlled to be a reference value, When an abnormality occurs in the conveying path that causes the sheet to stop being conveyed, the nip pressure of the conveying roller pair among the plurality of conveying roller pairs that is holding the sheet and that corresponds to one of the plurality of manually operated members that is manually operated is controlled to be greater than the reference value, and the nip pressure of the conveying roller pair that is holding the sheet and that corresponds to one of the plurality of manually operated members that is not manually operated is controlled to be equal to or less than the reference value.

2. a plurality of sheet detection sensors capable of detecting the presence or absence of the abnormality and the position where the abnormality has occurred are installed on the conveyance path; 2. The sheet conveying device according to claim 1, wherein one of the plurality of manually operated members is determined based on the detection results of the plurality of sheet detection sensors, and the nip pressure varying means is controlled by the manually operated member.

3. 3. The sheet conveying device according to claim 1, wherein the pair of conveying rollers corresponding to the manual operation member that is not manually operated has a drive roller and a driven roller that constitute the pair of conveying rollers spaced apart so that the nip pressure is zero.

4. a door that can open and close to expose the transport path; 3. The sheet conveying device according to claim 1, wherein the nip pressure varying means is controlled by using an opening operation of the door as a trigger.

5. Each of the plurality of conveying roller pairs includes a drive roller and a driven roller, 3. The sheet conveying device according to claim 1, wherein the nip pressure varying means comprises a plurality of actuators capable of moving the plurality of driven rollers separately.

6. 3. The sheet transport device according to claim 1, wherein the pair of transport guide members form a curved transport path.

7. 3. The sheet transport device according to claim 1, wherein the pair of transport guide members are configured so that one transport guide member is movable relative to the other transport guide member in a direction to widen the gap.

8. 3. An image forming apparatus comprising the sheet conveying device according to claim 1.

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