Sheet transport device and image forming apparatus

Abstract

To improve the efficiency of jam processing. [Solution] A sheet conveying device comprising: a pair of conveying rollers that form a nip portion and convey a sheet held in the nip portion in the sheet conveying direction; a conveying guide that is movable to a first position that forms at least a part of the sheet conveying path downstream of the pair of conveying rollers in the sheet conveying direction and a second position that opens at least a part of the sheet conveying path; and a moving means configured to perform a moving operation to move the sheet downstream in the sheet conveying direction by the pair of conveying rollers when the conveying of the sheet stops after the leading edge of the sheet has passed the nip portion and before the trailing edge of the sheet has passed the nip portion and the conveying of the sheet has stopped.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device for conveying a sheet and an image forming device for forming an image on the sheet.

Background Art

[0002] Patent Document 1 describes that when a jam is detected while a sheet is sandwiched between the nip portions of a resist roller pair, the resist roller pair is reversed to separate the sheet on the upstream side of the resist roller pair.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In some cases, a conveyance guide that can open and close at least a part of the conveyance path downstream of the conveyance roller pair in the sheet conveyance direction is provided. In this case, it is preferable to improve the workability when performing jam processing with the conveyance guide open.

[0005] Therefore, an object of the present invention is to provide a sheet conveying device and an image forming device that can improve the workability of jam processing.

Means for Solving the Problems

[0006] One aspect of the present invention is a sheet conveying device comprising: a pair of conveying rollers that form a nip portion and convey a sheet held in the nip portion in the sheet conveying direction; a conveying guide that is movable to a first position that forms at least a part of the sheet conveying path downstream of the pair of conveying rollers in the sheet conveying direction and a second position that opens at least a part of the sheet conveying path; and a moving means configured to perform a moving operation to move the sheet downstream in the sheet conveying direction by the pair of conveying rollers when the conveying of the sheet stops after the leading edge of the sheet has passed the nip portion and before the trailing edge of the sheet has passed the nip portion and the conveying of the sheet has stopped, and the conveying guide is moved from the first position to the second position. [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 improve the workability of jam processing. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional views (a, b) showing a part of the image forming apparatus according to the first embodiment. [Figure 2] A perspective view of an image forming apparatus according to the first embodiment. [Figure 3] A schematic diagram of an image forming apparatus according to the first embodiment. [Figure 4] A schematic diagram of an image forming apparatus according to the first embodiment. [Figure 5] A schematic diagram of a pair of regi rollers according to the first embodiment. [Figure 6] An explanatory diagram regarding the cassette drawer. [Figure 7] Diagrams (a-c) illustrating the state of the jam sheet when the cassette is removed. [Figure 8] A control block diagram (a) and a flowchart (b) showing an example of control according to the first embodiment. [Figure 9] Cross-sectional views (a, b) showing a part of the image forming apparatus according to the second embodiment. [Modes for carrying out the invention]

[0009] The embodiments relating to this disclosure will be described below with reference to the drawings.

[0010] 《First Embodiment》 Figure 3 is a schematic diagram showing a printer 1 according to the first embodiment of this disclosure. The printer 1 is an example of an image forming apparatus that forms an image on a sheet S, which is a recording material (recording medium). As the sheet S, a variety of sheet materials of different sizes and materials can be used, such as plain paper and cardboard, sheet materials with surface treatments such as coated paper, sheet materials with special shapes such as envelopes and index paper, plastic film, and cloth. First, an overview of the printer 1 will be described.

[0011] In the following description and drawings, the vertical direction (direction of gravity) when the printer 1 is placed on a horizontal surface is defined as the Z-axis direction. The direction of the rotation axis of the photosensitive drum 9 of the printer 1 is defined as the Y-axis direction. The direction that intersects both the Z-axis direction and the Y-axis direction is defined as the X-axis direction. Preferably, the X-axis direction, Y-axis direction, and Z-axis direction are orthogonal to each other.

[0012] The positive and negative directions along each coordinate axis are indicated by the signs + (plus) or - (minus), as needed. For example, the positive direction of the X-axis (indicated by arrow X) may be called the +X side, and the negative direction of the X-axis (opposite to arrow X) may be called the -X side. In this embodiment, the printer 1 can be accessed by the user primarily from the +X side to replenish the sheets S in the cassette 2 (described later), open and close the door 20 for jamming or cartridge replacement, and remove the output from the output tray 5. For this reason, in this embodiment, the +X side of the printer 1 may be called the front side or front edge.

[0013] As shown in Figure 3, the printer 1 comprises a main body 1A (main frame), a door 20, a cassette 2, an image forming unit 3 as an image forming means, and a fixing unit 4.

[0014] The apparatus main body 1A houses an image forming unit 3 and a fixing unit 4. An opening 1o (Fig. 2) is provided on the end face of the apparatus main body 1A on the +X side. The opening 1o opens toward the downstream in the drawing direction D1 of the cassette 2 described below. The door 20 is an opening / closing member (opening / closing unit, door unit) that can move between a closed position (Fig. 3) for closing the opening 1o and an open position (Figs. 2 and 4) for opening the opening 1o. The apparatus main body 1A and the door 20 constitute the housing of the printer 1 in the present embodiment. A discharge tray 5 as a stacking portion on which the sheet S after image formation is stacked is provided on the upper surface portion of the apparatus main body 1A.

[0015] The cassette 2 is provided with a storage portion 2b (storage space) for storing the sheet S, and is detachably attached to the apparatus main body 1A in the drawing direction D1. The drawing direction D1 of the cassette 2 in the present embodiment is the +X side (front side) in the X-axis direction. The cassette 2 is attached (inserted) to the apparatus main body 1A in the direction opposite to the drawing direction D1. A gripping portion 2a (Fig. 6) that is gripped by the user when pulling out the cassette 2 is provided at the +X side end of the cassette 2. Further, the cassette 2 may have a curved guide 2c that forms a part of the duplex path P2 described later, and a conveyance path inside the cassette for receiving the sheet S from an option feeder connected under the apparatus main body 1A.

[0016] The image forming unit 3 is a so-called four-drum full-color electrophotographic unit including a laser scanner 6 as an exposure unit, four cartridges 7Y, 7M, 7C, 7K, and a transfer unit. The cartridges 7Y, 7M, 7C, 7K are process units that form toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K) by an electrophotographic process, respectively.

[0017] <SHAPE> The cartridges 7Y to 7K have the same configuration as each other except for the color of the toner used as the developer. Each of the cartridges 7Y to 7K in the present embodiment has a photosensitive drum 9, a charging roller 10 as a charging member, a developing roller 11 as a developing member, and a toner storage portion (developing container) for storing toner.

[0018] The cartridges 7Y to 7K can be attached to and detached from the apparatus main body 1A through the opening 1o. Note that the printer 1 has a tray (cartridge tray) that can be pulled out from the apparatus main body 1A through the opening 1o, and the cartridges 7Y to 7K may be attached to and detached from the apparatus main body 1A by being attached to and detached from the tray.

[0019] The transfer unit includes an intermediate transfer belt 8 as an image carrier (intermediate transfer member), a plurality of rollers (8a, 8b, 8c), primary transfer rollers 8Y, 8M, 8C, 8K, and a transfer roller 12 (secondary transfer roller). The intermediate transfer belt 8 is stretched around a driving roller 8a, an assist roller 8b, and a tension roller 8c. The intermediate transfer belt 8 is disposed below the four cartridges 7Y, 7M, 7C, 7K. The intermediate transfer belt 8 is disposed so as to contact the photosensitive drums 9 of the respective cartridges 7Y, 7M, 7C, 7K, and is rotationally driven in the counterclockwise direction in the figure by the driving roller 8a.

[0020] The primary transfer rollers 8Y, 8M, 8C, 8K are on the inner peripheral side of the intermediate transfer belt 8 and are disposed at positions facing the photosensitive drums 9 of the cartridges 7Y, 7M, 7C, 7K with the intermediate transfer belt 8 interposed therebetween. A primary transfer portion (primary transfer nip) is formed between each of the primary transfer rollers 8Y, 8M, 8C, 8K and the intermediate transfer belt 8.

[0021] The transfer roller 12 is on the outer peripheral side of the intermediate transfer belt 8 and is disposed at a position facing the driving roller 8a (secondary transfer inner roller) with the intermediate transfer belt 8 interposed therebetween. A secondary transfer portion T2 (secondary transfer nip) is formed between the transfer roller 12 and the intermediate transfer belt 8.

[0022] The fixing unit 4 includes a pair of rotating bodies 16 that form a nip section (fixing nip), and a heat source for heating the image on the sheet S in the nip section. Each rotating body constituting the pair of rotating bodies may be a cylindrical roller, a cylindrical thin film, or a belt stretched over a plurality of rollers. As a heat source, for example, a halogen lamp that emits radiant heat, a ceramic heater with a pattern of a heating resistor printed on a ceramic substrate, or a coil unit that generates an alternating magnetic field to heat the conductive layer in the rotating body by induction heating can be used.

[0023] The printer 1 also includes a pickup roller 13, a separation roller pair 14, a registration roller pair (hereinafter referred to as the registration roller pair 15), a discharge roller pair 17, a reversing roller pair 17A, and double-sided roller pairs 201 and 202. In this embodiment, the pickup roller 13, separation roller pair 14, registration roller pair 15, discharge roller pair 17, and reversing roller pair 17A are supported by the device body 1A, and the double-sided roller pairs 201 and 202 are supported by the door 20.

[0024] Furthermore, the printer 1 has a main transport path P1 and a double-sided transport path P2. The main transport path P1 is a transport route from the cassette 2 to the discharge tray 5 via the separation roller pair 14, the register roller pair 15, the secondary transfer section T2, the fixing nip, and the discharge roller pair 17. The double-sided transport path P2 is a transport route that branches off from the main transport path P1 downstream of the fixing section 4 in the sheet transport direction of the main transport path P1 and rejoins the main transport path P1 upstream of the register roller pair 15. The reversing roller pair 17A and the double-sided roller pairs 201 and 202 are located in the double-sided transport path P2.

[0025] At least a portion of the double-sided path P2 is provided on the door 20. In this embodiment, as shown in Figure 4, a portion of the double-sided path P2, including the section between the double-sided roller pairs 201 and 202, is provided on the door 20, and the remaining portion of the double-sided path P2 is provided on the device body 1A. The main transport path P1 or the double-sided path P2 may be formed between a guide portion provided on the device body 1A and a guide portion provided on the door 20.

[0026] The pickup roller 13 is a feeding member that feeds sheets S from the cassette 2. The separation roller pair 14 forms a separation nip and transports the sheets S fed by the pickup roller 13 while separating them one by one at the separation nip. The separation roller pair 14 includes a transport roller that transports the sheets S in the sheet transport direction and a separation roller that contacts the transport roller. The separation roller is supported on a fixed shaft, for example via a torque limiter, and is a separation member that applies a frictional force to the sheets S in the opposite direction to the sheet transport direction at the separation nip. The separation roller is an example of a separation member, and for example, a pad-shaped elastic member (separation pad) may be used as a separation member. Furthermore, the pickup roller 13 and the separation roller pair 14 are examples of a feeding unit (feeding means) that feeds sheets S one by one, and for example, a feeding unit that uses an endless belt member to pick up and transport sheets S one by one may be used.

[0027] The register roller pair 15 is a transport roller pair located upstream of the secondary transfer section T2 and adjacent to the secondary transfer section T2 in the sheet transport direction. In other words, the sheet S sent out from the register roller pair 15 reaches the secondary transfer section T2 directly without passing through other roller pairs. The discharge roller pair 17 is a discharge unit that discharges the sheet S to the outside of the device body 1A. The inversion roller pair 17A is an inversion unit that inverts the sheet S when an image is to be formed on both sides of the sheet S. In this embodiment, the discharge unit and the inversion unit are arranged separately, but a single transport roller pair that serves as both the discharge unit and the inversion unit may also be provided.

[0028] Furthermore, the printer 1 includes a control unit C1 that controls the operation of the printer 1, a door open / close sensor 20S, a register sensor 22, and an operation unit OP (Figure 8(a)). The control unit C1 includes a CPU as an execution means for executing a program, and a storage unit that stores the program and provides a workspace for the CPU. The door open / close sensor 20S is a detection means (open / close detection means) for detecting the opening and closing of the door 20. The door open / close sensor 20S can use, for example, a switch that is pressed and activated by the door 20 when the door 20 is in the closed position. The register sensor 22 will be described later.

[0029] The control unit OP includes a display means for conveying visual or audio information to the user, and an input means for the user to input setting information or instructions to the printer 1. Examples of display means include an LCD panel and a speaker. Examples of input means include physical buttons such as soft keys and numeric keypads displayed on the LCD panel.

[0030] (Image formation process) Next, we will describe the image formation operation, which is a series of operations in which the printer 1 transports sheets S one by one and forms an image on the sheets S. The control unit C1 of the printer 1 (Figure 8(a)) starts the image formation operation when it receives an image formation instruction (print instruction) along with image data from, for example, an external computer.

[0031] When the image formation operation starts, the photosensitive drums 9 and intermediate transfer belts 8 of cartridges 7Y to 7K are driven to rotate at a predetermined peripheral speed. Each charging roller 10 uniformly charges the surface of the corresponding photosensitive drum 9 to a predetermined polarity and potential. The laser scanner 6 is driven by a video signal generated by the control unit C1 based on the image data, and exposes each photosensitive drum 9 by irradiating it with laser light. As a result, an electrostatic latent image corresponding to the component image obtained by color-separating the image data into yellow, magenta, cyan, and black is formed on the surface of each photosensitive drum 9. These electrostatic latent images are developed into monochromatic toner images of yellow, magenta, cyan, and black by the toner supplied to the photosensitive drum 9 by the developing roller 11.

[0032] The monochrome toner images formed on each photosensitive drum 9 are first transferred to the intermediate transfer belt 8 by the primary transfer rollers 8Y, 8M, 8C, and 8K. At this time, multiple transfers are performed on the intermediate transfer belt 8 so that the monochrome toner images overlap each other, thereby forming a full-color toner image (hereinafter simply referred to as "image") on the intermediate transfer belt 8. The image formed on the intermediate transfer belt 8 is transported toward the secondary transfer section T2 as the intermediate transfer belt 8 is rotated by the drive roller 8a.

[0033] In parallel with the electrophotographic process in the image forming unit 3, sheets S are fed one by one from the cassette 2 to the secondary transfer unit T2. Specifically, the pickup roller 13 contacts the topmost sheet S in the cassette 2 and feeds the topmost sheet S toward the separation roller pair 14. The separation roller pair 14 transports the topmost sheet S and, at the separation nip, applies frictional force to the sheets S other than the topmost sheet S, preventing them from passing through the separation nip. After passing through the separation nip, the sheets S are corrected for skew by the register roller pair 15 and then transported to the secondary transfer unit T2 by the register roller pair 15 in time with the timing when the image on the intermediate transfer belt 8 reaches the secondary transfer unit T2.

[0034] In the secondary transfer section T2, the image is transferred from the intermediate transfer belt 8 to the sheet S by applying voltage to the transfer roller 12. The sheet S that has passed through the secondary transfer section T2 is transported to the fixing section 4, where it undergoes image fixing. Fixing is a process in which a pair of rotating bodies 16 holds the sheet S between fixing nip and transports it while heating and pressurizing the toner image on the sheet S. The sheet S that has passed through the fixing section 4 is guided by a switching member (not shown) to either the discharge roller pair 17 or the reversing roller pair 17A.

[0035] In the case of single-sided printing, the sheet S is guided to the discharge roller pair 17, discharged outside the main unit 1A by the discharge roller pair 17, and loaded onto the discharge tray 5. In the case of double-sided printing, the sheet S passes through the secondary transfer section T2 and the fixing section 4 to form an image on the first surface, and then is guided to the reversal roller pair 17A and transported through the double-sided path P2. The reversal roller pair 17A switches back the sheet S. The double-sided roller pairs 201 and 202 transport the sheet S, which has been switched back by the reversal roller pair 17A, toward the register roller pair 15. Then, while the sheet S is transported again from the register roller pair 15 through the main transport path P1, an image is formed on the second surface of the sheet S. The sheet S with the image formed on the second surface is guided to the discharge roller pair 17, discharged outside the main unit 1A by the discharge roller pair 17, and loaded onto the discharge tray 5.

[0036] (Regilora vs.) The configuration of the register roller pair 15 in this embodiment will be explained using Figure 5. The register roller pair 15 is a pair of conveying rollers that form a nip portion 15n and convey the sheet S held by the nip portion 15n in the sheet conveying direction Dc. The sheet conveying direction Dc is the direction of movement of the sheet S at the nip portion 15n during image formation.

[0037] As shown in Figure 5, the register roller pair 15 consists of a drive roller 15a and a driven roller 15b. The drive roller 15a is connected to a motor M1, which is the drive source, via a gear train, and is rotationally driven by the driving force of the motor M1. The driven roller 15b forms a nip portion 15n together with the drive roller 15a and is capable of rotating in accordance with the drive roller 15a.

[0038] The drive roller 15a and the driven roller 15b are pressurized by the biasing force of the biasing member. In this embodiment, nip pressure springs 151, which serve as biasing members, are attached to both ends of the roller shaft 15c of the driven roller 15b, and the driven roller 15b is pressed against the drive roller 15a.

[0039] A register shutter 18 is positioned near the register roller pair 15. The register shutter 18 is rotatable around the roller axis 15c of the driven roller 15b. The register shutter 18 has a sheet contact portion that can project upstream of the nip portion 15n of the register roller pair 15 in the sheet conveying direction Dc. The register shutter 18 is biased by a shutter spring 19 in a direction (clockwise in the figure) in which the sheet contact portion projects upstream of the nip portion 15n.

[0040] During image formation, the leading edge of the sheet S, which has been conveyed from the separation roller pair 14 or the double-sided roller pair 202 toward the register roller pair 15, comes into contact with the sheet contact portion of the register shutter 18. This causes the sheet S to flex, correcting its skew so that the leading edge of the sheet S conforms to the register shutter 18. When the pressing force from the sheet S exceeds the biasing force of the shutter spring 19, the register shutter 18 rotates so that the sheet contact portion retracts downstream of the nip portion 15n, allowing the sheet S to enter the nip portion 15n. This corrects the skew of the sheet S, such as when the sheet S stored in the cassette 2 is set at an angle or when the sheet S is tilted in the separation roller pair 14.

[0041] The method using the register shutter 18 is just one example of a skew correction method. Alternatively, skew correction may be performed by bringing the leading edge of the sheet S against the nip portion 15n of the stopped register roller pair 15 without using the register shutter 18.

[0042] Furthermore, a register sensor 22 is positioned near the register roller pair 15 as a detection means for detecting the sheet S. In this embodiment, the register sensor 22 is configured to emit a signal corresponding to the position of the register shutter 18. Specifically, the register sensor 22 is a transmissive optical sensor (photointerrupter) that is obliquely moved by a flag 18a provided at the end of the register shutter 18.

[0043] The register sensor 22 can detect when the register shutter 18 is rotated by the sheet S. In other words, the register sensor 22 outputs a first signal (detection state) from the time the leading edge of the sheet S reaches the nip portion 15n of the register roller pair 15 until the trailing edge of the sheet S leaves the nip portion 15n. Before the leading edge of the sheet S reaches the nip portion 15n of the register roller pair 15, and after the trailing edge of the sheet S leaves the nip portion 15n, the register sensor 22 outputs a second signal (non-detection state).

[0044] During image formation, the rotation speed of the motor M1 is controlled based on the signal from the registration sensor 22 so that the timing of the image on the intermediate transfer belt 8 reaching the secondary transfer section T2 coincides with the timing of the sheet S entering the secondary transfer section T2. ​​This allows for image registration relative to the sheet S.

[0045] (Jam processing) This section describes the configuration related to jamming. Jamming refers to the process by which the user removes the jammed sheet S (which may be referred to as a jammed sheet) that remains inside the printer 1 when a jam (transportation error) occurs during image formation.

[0046] The control unit C1 of printer 1 (Figure 8(a)) monitors the transport of the sheet S based on detection signals from sensors arranged along the sheet S transport path (P1, P2), and detects jam occurrences when delays exceeding an acceptable range occur compared to the scheduled schedule. For example, if the register sensor 22 does not return to the non-detection state even after a predetermined time has elapsed since the time the register sensor 22 changed from a non-detection state to a detection state, the control unit C1 determines that a jam in which the sheet S is stuck has occurred either in the register roller pair 15 or downstream of the register roller pair 15.

[0047] If a jam occurs, the control unit C1 interrupts the image formation operation and stops the transport of the sheet S, and also notifies the user of the jam through a screen display or voice message on the operation unit OP. The notification may include the location of the jammed sheet and the procedure for removing the jammed sheet.

[0048] As shown in Figures 2 and 4, the printer 1 has a transfer guide 21. The transfer guide 21 includes a guide section that forms part of the main transport path P1. The transfer guide 21 and the transfer roller 12 are part of a transfer guide unit 21U that is rotatably supported on the device body 1A via a pivot point 21a.

[0049] The transfer guide 21 is movable between a closed position (first position) and an open position (second position). The closed position of the transfer guide 21 is a position that forms at least a portion of the sheet transport path (main transport path P1) downstream of the register roller pair 15 in the sheet transport direction Dc of the register roller pair 15, as shown in Figure 3. The open position of the transfer guide 21 is a position that opens at least a portion of the sheet transport path (main transport path P1) downstream of the register roller pair 15, as shown in Figures 2 and 4. In this embodiment, when the transfer guide 21 is opened, the section of the main transport path P1 from the register roller pair 15 to just before the fixing section 4 is opened. With the nip portion 15n of the register roller pair 15 formed, the transfer guide 21 is movable between the closed position and the open position.

[0050] Hereinafter, the closed and open positions of the door 20 will be referred to as the first closed position and the first open position, and the closed and open positions of the transfer guide 21 will be referred to as the second closed position and the second open position to distinguish them.

[0051] The door 20 and the transfer guide 21 can be opened when the user performs jamming, etc. The door 20 rotates around the pivot point 20a from a first closed position to a first open position. The transfer guide 21 rotates around the pivot point 21a from a second closed position to a second open position.

[0052] When the door 20 is opened, at least a portion of the duplex path P2 is exposed to the outside of the printer 1. This allows the user to easily remove any jam sheets remaining in the duplex path P2.

[0053] When the door 20 and the transfer guide 21 are opened, at least a portion of the main transport path P1 is exposed to the outside of the printer 1. In this embodiment, when the door 20 and the transfer guide 21 are opened, the section of the main transport path P1 from the register roller pair 15 to the vicinity of the upstream side of the fuser unit 4 is exposed to the outside of the printer 1. This allows the user to easily remove any jam sheets remaining on the main transport path P1. In other words, when the door 20 and the transfer guide 21 are opened, the opening of the device body 1A is exposed in order to access the jam sheets.

[0054] In particular, in this embodiment, when the door 20 is opened and the transfer guide 21 is opened, the nip portion 15n of the register roller pair 15 becomes visible from outside the printer 1 (Figure 2). Therefore, if a jam occurs with the leading edge of the sheet S protruding downstream of the nip portion 15n, the user can remove the jam by grasping the leading edge of the jammed sheet and pulling it off the register roller pair 15.

[0055] In this embodiment, the transfer guide 21 is configured to move from the second closed position to the second open position in conjunction with the movement of the door 20 from the first closed position to the first open position. For example, when the door 20 is opened, the transfer guide 21 moves from the second closed position to the second open position by its own weight, and when the door 20 is closed, it is held in the second closed position by being pressed against by the door 20. However, the configuration may be such that the door 20 and the transfer guide 21 are connected by a link member, and the transfer guide 21 moves in conjunction with the opening and closing of the door 20 by the transmission of force through the link member. Alternatively, the transfer guide 21 may not be linked to the opening and closing of the door 20, and the user may manually move the transfer guide 21 from the second closed position to the second open position after the door 20 is opened.

[0056] (Handling jammed sheets that have stopped near the register roller) Incidentally, as shown in Figure 1(a), if jam occurs when the leading edge of the sheet S is located downstream and near the register roller pair 15, jam removal may become difficult. That is, when the leading edge of the jam sheet is located downstream and near the register roller pair 15, the register roller pair 15 may obstruct the user from picking up the jam sheet. In addition, the presence of the intermediate transfer belt 8 near the leading edge of the jam sheet restricts the working space, which may make jam removal even more difficult.

[0057] Therefore, in this embodiment, when the transfer guide 21 is opened while the register roller pair 15 has detected that there is a sheet S on it, the control unit C1 drives the register roller pair 15 to move the sheet S downstream in the sheet transport direction Dc.

[0058] The printer 1 of this embodiment has a door opening / closing sensor 20S for detecting the opening and closing of the door 20, and the transfer guide 21 opens and closes in conjunction with the opening and closing of the door 20. Therefore, the control unit C1 of this embodiment determines that the transfer guide 21 has been opened based on the signal from the door opening / closing sensor 20S and executes a movement operation. In other words, the door opening / closing sensor 20S is an example of a detection means that outputs different signals depending on whether the transfer guide 21 is in the closed position (first position) or in the open position (second position). The detection means may also be a sensor that directly detects the position of the transfer guide 21, such as a switch that is activated when pressed by the transfer guide 21.

[0059] Figure 8(b) is a flowchart showing the procedure for processing related to movement. The control unit C1 monitors for jamming during the execution of the image forming operation (S101). If jamming occurs (S101:Yes), the control unit C1 stops the rotation of the motor M1 and stops the transport of the sheet S, and also determines the position of the jammed sheet (S102). If the register sensor 22 is in a detection state at the time of jamming, that is, if the register sensor 22 has already detected the passage of the leading edge of the sheet S but has not yet detected the passage of the trailing edge of the sheet S (S102:Yes), the control unit C1 determines that movement is necessary. In this case, the control unit C1 maintains the stopped state of the motor M1 until the door 20 is opened, and when it detects the opening of the door 20 based on the signal from the door opening / closing sensor 20S (S103:Yes), it starts the motor M1 and performs the movement operation (S104).

[0060] On the other hand, if the register sensor 22 is not detecting anything at the time of jam formation, that is, if the register sensor 22 has not detected the passage of the leading edge of the sheet S or has detected the passage of the trailing edge of the sheet S (S102: No), the control unit C1 determines that there is no need for movement and terminates the process.

[0061] During the movement operation in S104, the control unit C1 drives the register roller pair 15 in the same rotational direction as during image formation, moving the jam sheet downstream in the sheet transport direction Dc (Figure 1(b)). This makes it easier to remove the jam sheet. Furthermore, when the control unit C1 determines that the jam sheet has moved a predetermined distance from the position where the jam occurred, it stops the motor M1 and ends the movement operation. The predetermined distance is determined by the amount of rotation of the register roller pair 15 during the movement operation (the distance traveled by the circumferential surface of the drive roller 15a).

[0062] In this embodiment, the predetermined distance is set to a value (for example, 50 mm) that is longer than the distance from the nip portion 15n of the register roller pair 15 to the upper end of the drive roller 8a. In other words, the predetermined distance is longer than the distance from the nip portion to the end position of the opposing roller (drive roller 8a) facing the transfer roller 12 in the sheet transport direction Dc. Therefore, for example, when the movement operation is performed with the leading edge of the jam sheet located within the nip portion 15n of the register roller pair 15, the leading edge of the jam sheet protrudes downstream in the sheet transport direction Dc beyond the portion of the intermediate transfer belt 8 supported by the drive roller 8a. By setting the predetermined distance in this way, the user can perform jam processing in a wide workspace without being obstructed by the intermediate transfer belt 8.

[0063] In this embodiment, the motor M1 remains stopped until the door 20 and the transfer guide 21 are opened. By maintaining the motor M1 stopped until the door 20 is opened, it is possible to prevent damage to the intermediate transfer belt 8, etc., caused by the jam sheet being forcibly moved by the movement operation while the door 20 and the transfer guide 21 are closed.

[0064] The register roller pair 15 is configured to transport the sheet S upward. Therefore, when the register roller pair 15 transports the jam sheet with the transfer guide 21 in the open position, the jam sheet bends under its own weight, making it difficult for the leading edge of the jam sheet to reach the intermediate transfer belt 8. The intermediate transfer belt 8 is inclined with respect to the horizontal direction and has an inclined surface that faces downward in the vertical direction. The inclined surface of the intermediate transfer belt 8 faces outward from the device body 1A and is exposed to the outside of the device body 1A when the door 20 and the transfer guide 21 are open. In this embodiment, the inclined surface is located between the drive roller 8a and the roller adjacent to the drive roller 8a (assist roller 8b). The inclined surface is also located directly above the nip portion 15n of the register roller pair 15. The register roller pair 15 transports the sheet S so that the sheet S contacts the inclined surface of the intermediate transfer belt 8. Even if the guide 21 is in the open position and the register roller pair 15 conveys the jam sheet, and the leading edge of the jam sheet comes into contact with the inclined surface of the intermediate transfer belt 8, the leading edge of the jam sheet S is guided toward the outside of the main body 1A of the device.

[0065] As described above, in this embodiment, when a jam occurs while the sheet S is held between the reseal roller pair 15, the transfer guide 21 is moved from the closed position (first position) to the open position (second position), and the transfer operation (S104) is performed. The motor M1 (drive source) and control unit C1 in this embodiment are examples of moving means configured to perform the moving operation. In other words, the image forming apparatus of this embodiment has moving means configured to perform a moving operation to move the sheet downstream in the sheet transport direction by the transport roller pair when the transport guide is moved from the first position to the second position while the transport of the sheet has stopped after the leading edge of the sheet has passed the nip and before the trailing edge of the sheet has passed the nip.

[0066] As the jam sheet moves downstream of the register roller pair 15 due to the movement motion, it becomes easier to grasp the leading edge of the jam sheet. Therefore, in a configuration in which a transport guide (transfer guide 21) that can open and close at least a portion of the transport path downstream of the transport roller pair is provided, the workability of jam processing can be improved.

[0067] In other words, according to this embodiment, it is possible to provide a sheet conveying device and an image forming device that can improve the workability of jam processing.

[0068] (Relationship with cassette ejection direction) In particular, in this embodiment, the printer 1 uses a pickup roller 13 (feeding means) to feed the sheet S downstream in the withdrawal direction D1 of the cassette 2 (Figure 3). In this configuration, for example, if the register roller pair 15 is reversed during the movement operation to push the jammed sheet back upstream in the sheet transport direction Dc, the workability of jam processing is not improved.

[0069] This will be explained in detail using Figures 7(a) to 7(c). Figure 7(a) is a schematic diagram showing the printer 1 when a jam occurs while the sheet S is held between the register roller pair 15. Figure 7(b) is a schematic diagram showing the state in which the register roller pair 15 is reversed from the state in Figure 7(a) and the cassette 2 is pulled out from the main body 1A of the device. Figure 7(c) is a schematic diagram showing the state in which the register roller pair 15 is rotated in the same direction as during image formation from the state in Figure 7(a) and the door 20 and transfer guide 21 are open.

[0070] As shown in Figure 7(b), when the cassette 2 is pulled out of the device body 1A with the jam sheet S1 pushed back towards the cassette 2 side by the reversal of the register roller pair 15, the rear end of the jam sheet S1 may be pushed by the cassette 2 and buckle. Furthermore, even if the cassette 2 is pulled out to the limit position from the device body 1A, or if the cassette 2 is removed from the device body 1A, the jam sheet S1 remains inside the device body 1A, making it difficult to see and access. Therefore, in a configuration where the sheet S is fed downstream in the withdrawal direction D1 of the cassette 2, pushing the jam sheet S1 upstream of the register roller pair 15 by the movement operation does not improve the workability of jam processing.

[0071] In contrast, as shown in Figure 7(c), according to this embodiment, the sheet S is fed downstream in the withdrawal direction D1 of the cassette 2, and the transfer guide 21 located downstream of the register roller pair 15 can be opened and closed. In this case, by moving the jam sheet S1 downstream of the register roller pair 15 by the movement operation, the visibility and accessibility of the jam sheet S1 when the transfer guide 21 is open can be improved. Therefore, the movement operation in this embodiment is particularly effective in the configuration in which the sheet is fed downstream in the withdrawal direction D1 of the cassette 2.

[0072] (modified version) In the first embodiment, it was explained that the door 20 and the transfer guide 21 rotate around separate pivot points 20a and 21a, and that the transfer guide 21 opens and closes in conjunction with the opening and closing of the door 20. However, the transfer guide 21 (conveyor guide) may be provided on the door 20. In other words, the "conveyor guide" may be part of an opening and closing member that can open and close the opening 1o of the device body 1A.

[0073] Furthermore, in the first embodiment, the predetermined distance, which is the set value for the travel distance of the jam sheet during the moving operation (S104), was described as being set to 50 mm, but the predetermined distance may be changed depending on the specific configuration of the printer 1. Alternatively, the travel distance of the jam sheet during the moving operation (S104) may not be set, and the driving of the register roller pair 15 may be continued, for example, until the rear end of the jam sheet is discharged from the register roller pair 15 during the moving operation (S104).

[0074] 《Second Embodiment》 A second embodiment of the present disclosure will now be described. This embodiment differs from the first embodiment in that it uses an interlocking mechanism to rotate the register roller pair 15 in conjunction with the opening of the transfer guide 21. Hereinafter, elements denoted by reference numerals common to the first embodiment will have basically the same configuration and operation as those described in the first embodiment unless otherwise specified, and the differences from the first embodiment will be mainly described.

[0075] Figures 9(a) and 9(b) are schematic diagrams showing the interlocking mechanism 30 according to this embodiment. Figure 9(a) shows the state in which the transfer guide 21 is in the closed position, and Figure 9(b) shows the state in which the transfer guide 21 is in the open position.

[0076] As shown in Figures 9(a) and 9(b), the interlocking mechanism 30 is connected to the transfer guide 21 (conveyor guide) and the reseal roller pair 15 (conveyor roller pair). The interlocking mechanism 30 is capable of transmitting force from the transfer guide 21 to the reseal roller pair 15 so as to rotate the reseal roller pair 15 in conjunction with the movement of the transfer guide 21 from the closed position (first position) to the open position (second position). The interlocking mechanism 30 in this embodiment includes a roller gear 23, a step gear 24, and a transfer guide gear 25.

[0077] The roller gear 23 is attached to the end of the roller shaft of the drive roller 15a and rotates integrally with the drive roller 15a. The stepped gear 24 has a large gear 24a that meshes with the roller gear 23 and a small gear 24b that has a smaller diameter than the large gear 24a. The transfer guide gear 25 meshes with the small gear 24b and rotates integrally with the transfer guide 21 around the pivot point 21a. When the transfer guide 21 is moved from the closed position to the open position, the transfer guide gear 25 rotates clockwise in the figure, and when the transfer guide 21 is moved from the open position to the closed position, the transfer guide gear 25 rotates counterclockwise in the figure.

[0078] The stepped gear 24 incorporates a one-way clutch as a disconnecting mechanism. The one-way clutch rotates the large gear 24a integrally with the small gear 24b when the small gear 24b rotates in the predetermined direction indicated by arrow R in Figure 9(b). The one-way clutch also slips when the small gear 24b rotates in the opposite direction to the predetermined direction, and does not transmit force from the small gear 24b to the large gear 24a. The predetermined direction is the direction of rotation of the small gear 24b when the transfer guide 21 is moved from the open position to the closed position.

[0079] In other words, the stepped gear 24 incorporating a one-way clutch is an example of a blocking mechanism that interrupts the transmission of force from the transfer guide 21 (conveyor guide) to the regi roller pair 15 (conveyor roller pair) when the transfer guide 21 (conveyor guide) moves from the open position (second position) to the closed position (first position). An electromagnetic clutch may also be used as the blocking mechanism.

[0080] The operation of the interlocking mechanism 30 during jam processing will now be explained. Assume that a jam occurs when the sheet S is held between the register roller pair 15, as shown in Figure 9(a). In this case, when the user opens the door 20 to process the jam, the transfer guide 21 rotates clockwise in the figure in conjunction with the door 20, moving from the closed position to the open position (Figure 9(b)). As the transfer guide 21 rotates, the transfer guide gear 25 rotates, and the transfer guide gear 25 rotates the small gear 24b of the stepped gear 24. Furthermore, the large gear 24a rotates together with the small gear 24b, and the large gear 24a rotates the roller gear 23 clockwise in the figure. Then, the drive roller 15a rotates together with the roller gear 23. As a result, the register roller pair 15 rotates in the same direction as during image formation in conjunction with the movement of the transfer guide 21 from the closed position to the open position, and the jammed sheet is moved downstream of the register roller pair 15.

[0081] In other words, the interlocking mechanism 30 transmits force from the transfer guide 21 to the pair of register rollers 15 so as to rotate the pair of register rollers 15 in conjunction with the movement of the transfer guide 21 from the closed position (first position) to the open position (second position).

[0082] When the user closes the door 20 after jamming, the transfer guide 21 moves from the open position to the closed position in conjunction with the door 20 (Figure 9(a)). In this case, the small gear 24b of the transfer guide gear 25 and the step gear 24 rotate together with the transfer guide 21, but the large gear 24a does not rotate due to the free rotation of the one-way clutch. Therefore, the door 20 and the transfer guide 21 can be closed without rotating the register roller pair 15, thus avoiding increased operating load on the door 20 due to resistance from the register roller pair 15 and inconveniences such as roller wear caused by unnecessary rotation of the register roller pair 15.

[0083] The interlocking mechanism 30 is an example of a moving means configured to move the sheet downstream in the sheet transport direction by the transport roller pair when a jam occurs while the sheet is held between the transport roller pair and the transport guide moves from the first position to the second position.

[0084] As the jam sheet moves downstream of the register roller pair 15 due to the movement motion, it becomes easier to grasp the leading edge of the jam sheet. Therefore, in a configuration in which a transport guide (transfer guide 21) that can open and close at least a portion of the transport path downstream of the transport roller pair is provided, the workability of jam processing can be improved.

[0085] In other words, according to this embodiment, it is possible to provide a sheet conveying device and an image forming device that can improve the workability of jam processing.

[0086] Furthermore, in a configuration where the sheet S is fed downstream in the withdrawal direction D1 of the cassette 2, the workability of jam processing can be particularly improved.

[0087] Furthermore, in the first embodiment, it is preferable that the motor M1 drives only the register roller pair 15 during jam processing, so that other drive members are not driven when the register roller pair 15 is driven during the movement operation of jam processing. In other words, it is preferable to have a separate drive source for drive members other than the register roller pair 15 in the printer 1 (e.g., the fuser unit 4 and the drive roller 8a) from the motor M1, or to have a configuration in which the transmission of drive from the motor M1 to drive members other than the register roller pair 15 can be cut off by a clutch. In contrast, according to this embodiment, it is not necessary to separate the drive source for the register roller pair 15 and drive members other than the register roller pair 15, or to provide a clutch to cut off the transmission of drive to drive members other than the register roller pair 15. Therefore, for example, in a configuration in which a single motor drives the register roller pair 15 and drive members other than the register roller pair 15, the workability of jam processing can be improved at low cost without adding motors or the like.

[0088] The gear train-based interlocking mechanism 30 described in this embodiment is merely an example; for example, a belt drive or a cam mechanism may also be used as the interlocking mechanism. The interlocking mechanism only needs to transmit force from the transfer guide 21 (conveyor guide) to the reel roller pair 15 (conveyor roller pair) and rotate the reel roller pair 15 in conjunction with the opening of the transfer guide 21.

[0089] (modified version) The image forming unit 3 in each of the embodiments described above is merely an example of an image forming means for forming an image on the sheet S. The image forming means may also be a direct transfer type electrophotographic unit that directly transfers an image from the photosensitive drum 9, which acts as an image carrier, to the sheet S without going through an intermediate transfer body. Furthermore, the image forming means may be of a type other than electrophotography, for example, an inkjet type image forming unit.

[0090] In the embodiments described above, examples of applying this technology to a register roller pair 15, which is an example of a conveying roller pair, were explained, but the same technology as in the embodiments may be applied to other conveying roller pairs. For example, in a configuration in which a sheet S fed from a cassette 2 is passed sequentially through one or more intermediate roller pairs to the register roller pair 15, suppose a jam occurs when the sheet S is held between the intermediate roller pairs. In this case, when the conveying guide that forms at least a part of the sheet conveying path downstream of the intermediate roller pair is opened, a movement operation is performed to rotate the intermediate roller pair and move the jammed sheet downstream in the sheet conveying direction.

[0091] Furthermore, although the above-described embodiments described a sheet transport device incorporated into the printer 1 (image forming apparatus), the sheet transport device may be a separate device from the printer 1 (image forming apparatus). For example, the sheet transport device may be a high-capacity feeder (optional feeder) connected to the image forming apparatus that feeds sheets S toward the image forming apparatus.

[0092] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0093] Summary of this disclosure This disclosure includes at least the following: (Composition 1) A pair of conveying rollers that form a nip portion and convey the sheet held in the nip portion in the sheet conveying direction, A conveying guide that is movable to a first position that forms at least a portion of the sheet conveying path downstream of the pair of conveying rollers in the sheet conveying direction, and to a second position that opens at least a portion of the sheet conveying path, When the sheet transport stops after the leading edge of the sheet has passed the nip portion and before the trailing edge of the sheet has passed the nip portion, and the transport guide is moved from the first position to the second position, the transport roller pair is configured to perform a moving operation to move the sheet downstream in the sheet transport direction, A sheet conveying device characterized by comprising the following features. (Configuration 2) The moving means includes a drive source for driving the transport roller pair and a control unit for controlling the drive source. A sheet conveying device according to configuration 1, characterized by the features described above. (Composition 3) The system further includes detection means that outputs different signals depending on whether the transport guide is in the first position or in the second position. The control unit executes the movement operation based on the signal. A sheet conveying device according to configuration 2, characterized in that it is a sheet conveying device. (Composition 4) The moving means is an interlocking mechanism connected to the transport guide and the transport roller pair, which transmits force from the transport guide to the transport roller pair so as to rotate the transport roller pair in conjunction with the movement of the transport guide from a first position to a second position. A sheet conveying device according to any one of configurations 1 to 3, characterized by the above. (Composition 5) The interlocking mechanism includes a blocking section that blocks the transmission of force from the transport guide to the transport roller pair when the transport guide is moved from the second position to the first position. The sheet conveying device according to configuration 4, characterized by the features described above. (Composition 6) The device body that supports the aforementioned pair of conveying rollers, A cassette for storing a sheet is mounted on the main body of the device so as to be retractable in the retraction direction, A feeding means for feeding the sheet from the cassette downstream in the withdrawal direction, Furthermore, The aforementioned pair of conveying rollers conveys the sheet that has been fed by the feeding means. A sheet conveying device according to any one of configurations 1 to 5, characterized by the above. (Composition 7) The main body of the device is provided with an opening that opens toward the downstream direction in the withdrawal direction, The system further includes an opening / closing member that is movable between a closed position that closes the opening and an open position that opens the opening. When the opening / closing member is in the open position and the transport guide is in the second position, the nip portion of the transport roller pair is visible from outside the sheet transport device. A sheet conveying device according to configuration 6, characterized by the features described above. (Composition 8) A device body that supports the aforementioned pair of conveying rollers, comprising a device body having an opening, An opening / closing member that can move between a closed position that closes the opening and an open position that opens the opening, Furthermore, The transport guide is configured to move from the first position to the second position in conjunction with the movement of the opening / closing member from the closed position to the open position. A sheet conveying device according to any one of configurations 1 to 7, characterized by the above. (Composition 9) The moving means rotates the transport roller pair so that the sheet moves a predetermined distance, and then stops the transport roller pair. A sheet conveying device according to any one of configurations 1 to 8, characterized by the above. (Composition 10) The transport roller pair is positioned in the sheet transport direction upstream of the transfer section where an image is transferred from the image carrier to the sheet, and adjacent to the transfer section. A sheet transport device according to any one of configurations 1 to 9, characterized by the above. (Composition 11) The device body that supports the aforementioned pair of conveying rollers, A transfer roller that forms the transfer portion between itself and the image carrier, Furthermore, The transport guide and the transfer roller are part of a unit that can rotate relative to the main body of the device. A sheet conveying device according to configuration 10, characterized by the features described above. (Composition 12) The moving means rotates the transport roller pair so that the sheet moves a predetermined distance, and then stops the transport roller pair. The image carrier is an intermediate transfer belt stretched over a plurality of rollers, including a counter roller facing the transfer roller. The predetermined distance is longer than the distance from the nip portion to the end position of the opposing roller in the sheet conveying direction. A sheet conveying device according to configuration 11, characterized by the features described above. (Composition 13) A sheet transport device according to any one of configurations 1 to 12, Image forming means for forming an image on a sheet conveyed by the sheet conveying device, An image forming apparatus characterized by comprising: [Explanation of Symbols]

[0094] 15...Conveyor roller pair (register roller pair) / 21...Conveyor guide (transfer guide) / C1, M1, 30...Moving means (control unit, motor, interlocking mechanism)

Claims

1. A pair of conveying rollers that form a nip portion and convey the sheet held in the nip portion in the sheet conveying direction, A conveying guide that is movable to a first position that forms at least a portion of the sheet conveying path downstream of the pair of conveying rollers in the sheet conveying direction, and to a second position that opens at least a portion of the sheet conveying path, When the sheet transport stops after the leading edge of the sheet has passed the nip portion and before the trailing edge of the sheet has passed the nip portion, the transport guide is moved from the first position to the second position, and the transport roller pair is configured to perform a moving operation to move the sheet downstream in the sheet transport direction, A sheet conveying device characterized by comprising the following features.

2. The moving means includes a drive source for driving the transport roller pair and a control unit for controlling the drive source. The sheet conveying device according to feature 1.

3. The system further includes detection means that outputs different signals depending on whether the transport guide is in the first position or in the second position. The control unit executes the movement operation based on the signal. The sheet conveying device according to feature 2.

4. The moving means is an interlocking mechanism connected to the transport guide and the transport roller pair, which transmits force from the transport guide to the transport roller pair so as to rotate the transport roller pair in conjunction with the movement of the transport guide from a first position to a second position. The sheet conveying device according to feature 1.

5. The interlocking mechanism includes a blocking section that blocks the transmission of force from the transport guide to the transport roller pair when the transport guide is moved from the second position to the first position. The sheet conveying device according to feature 4.

6. The device body that supports the aforementioned pair of conveying rollers, A cassette for storing a sheet is mounted on the main body of the device so as to be retractable in the retraction direction, A feeding means for feeding the sheet from the cassette downstream in the withdrawal direction, Furthermore, The aforementioned pair of conveying rollers conveys the sheet that has been fed by the feeding means. The sheet conveying device according to feature 1.

7. The main body of the device is provided with an opening that opens toward the downstream direction in the withdrawal direction, The system further includes an opening / closing member that is movable between a closed position that closes the opening and an open position that opens the opening. When the opening / closing member is in the open position and the transport guide is in the second position, the nip portion of the transport roller pair is visible from outside the sheet transport device. The sheet conveying device according to feature 6.

8. A device body that supports the aforementioned pair of conveying rollers, the device body having an opening, An opening / closing member that can move between a closed position that closes the opening and an open position that opens the opening, Furthermore, The transport guide is configured to move from the first position to the second position in conjunction with the movement of the opening / closing member from the closed position to the open position. The sheet conveying device according to feature 1.

9. The moving means rotates the transport roller pair so that the sheet moves a predetermined distance, and then stops the transport roller pair. The sheet conveying device according to feature 1.

10. The transport roller pair is positioned in the sheet transport direction upstream of the transfer section where an image is transferred from the image carrier to the sheet, and adjacent to the transfer section. The sheet conveying device according to feature 1.

11. The device body that supports the aforementioned pair of conveying rollers, A transfer roller that forms the transfer portion between itself and the image carrier, Furthermore, The transport guide and the transfer roller are part of a unit that can rotate relative to the main body of the device. The sheet conveying device according to feature 10.

12. The moving means rotates the transport roller pair so that the sheet moves a predetermined distance, and then stops the transport roller pair. The image carrier is an intermediate transfer belt stretched over a plurality of rollers, including a counter roller facing the transfer roller. The predetermined distance is longer than the distance from the nip portion to the end position of the opposing roller in the sheet conveying direction. The sheet conveying device according to feature 11.

13. A sheet conveying device according to any one of claims 1 to 12, Image forming means for forming an image on a sheet conveyed by the sheet conveying device, An image forming apparatus characterized by comprising:

Images