Sheet conveyance device and image forming device

Abstract

To provide a sheet conveyance device which achieves high accuracy of positioning in a conveyance roller pair and stabilization of a pressurized state, and can easily perform jam processing of a sheet.SOLUTION: A sheet conveyance device 4 includes a first roller 43A, a second roller 43B, a bush member 44, an energization member 45 and a conveyance guide member 46. The energization member 45 energizes the bush member 44 in a direction in which the second roller 43B approaches the first roller 43A. The conveyance guide member 46 is mounted on a rotary shaft 43Bx of the second roller 43B, is movable between a guide position for guiding a sheet and a retreat position retreated from the guide position, comes into contact with a body frame 2F at the retreat position, and moves the bush member 44 in a direction where the second roller 43B is separated from the first roller 43A against the energization force of the energization member 45.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device and an image forming apparatus. [Background technology]

[0002] Image forming devices such as copiers and printers include a sheet conveying device. The sheet conveying device includes a pair of conveying rollers that conveys sheets. The sheet conveying device conveys sheets one by one from a sheet supply unit that stores and stacks sheets, which are recording media used for printing (recording) images, toward an image forming unit (transfer unit), a fixing unit, and a sheet discharge unit.

[0003] For example, the conventional image forming apparatus disclosed in Patent Document 1 includes a paper transport unit that clamps and transports paper, and an opening / closing unit that opens relative to the device body to expose the paper transport path near the paper transport unit. The pair of registration rollers that constitute the paper transport unit are supported by the device body. In other words, the two rollers that make up the pair of registration rollers are supported by the device body. This prevents the parallelism and pressure balance of the pair of registration rollers from being impaired, regardless of whether the opening / closing unit is open or closed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-290516 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional technology had a problem in that the pair of registration rollers supported by the device body was not provided with a mechanism for separating the pair of rollers, which reduced the user's operability in clearing jammed paper and raised concerns that forcible jam clearance could impair the parallelism and pressure balance of the pair of registration rollers.

[0006] The present invention has been made in consideration of the above points, and aims to provide a sheet conveying device and an image forming device that can achieve high precision positioning of conveying roller pairs, stabilize the pressure state, and easily handle sheet jams. [Means for solving the problem]

[0007] In order to solve the above problems, the sheet conveying device of the present invention includes a first roller, a second roller, a bushing member, an urging member, and a conveying guide member. The first roller is rotatably supported by a main body frame of the device main body. The second roller is disposed opposite the first roller to form a conveying roller pair. The bushing member is supported by the main body frame so as to be movable in the radial direction of the first roller and rotatably supports the second roller. The urging member urges the bushing member in a direction in which the second roller approaches the first roller. The conveying guide member guides a sheet conveyed to a nip portion of the conveying roller pair. The conveying guide member is attached to a rotation shaft of the second roller and is movable between a guide position where it guides the sheet and a retracted position retracted from the guide position. In the retracted position, the conveying guide member contacts the main body frame and moves the bushing member in a direction in which the second roller moves away from the first roller against the urging force of the urging member. [Effects of the Invention]

[0008] According to the configuration of the present invention, both the first roller and the second roller of the conveying roller pair are supported by the device body, which allows for high-precision positioning and stable pressure application. Furthermore, the conveying roller pair can easily bring the first roller and the second roller into contact with and separate from each other by moving the conveying guide member. Therefore, it is possible to easily clear jammed sheets in the sheet conveying device. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a schematic cross-sectional front view of an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of a sheet conveying device of the image forming apparatus of FIG. [Figure 3] 3 is a partial perspective view of the vicinity of a pair of registration rollers of the sheet conveying device of FIG. 2. FIG. [Figure 4] 4 is a cross-sectional front view of the pair of registration rollers and the vicinity thereof in FIG. 3, showing a state in which the transport guide member is at a guide position. FIG. [Figure 5] 4 is a cross-sectional front view of the pair of registration rollers and the vicinity thereof in FIG. 3, showing a state in which the transport guide member is in a retracted position. FIG. [Figure 6] 2 is a perspective view of an opening / closing portion of a sheet conveying device of the image forming apparatus of FIG. 1. [Figure 7] FIG. 7 is a partially enlarged perspective view of the opening / closing section of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following.

[0011] 1 is a schematic cross-sectional front view of an image forming apparatus 1 according to an embodiment. An example of the image forming apparatus 1 according to this embodiment is a tandem color printer that transfers a toner image onto a sheet S using an intermediate transfer belt 71. The image forming apparatus 1 may be a so-called multifunction peripheral that has functions such as printing, scanning (image reading), and facsimile transmission.

[0012] As shown in FIG. 1, the image forming apparatus 1 includes a sheet supply unit 3, a sheet conveying device 4, an exposure unit 5, an image forming unit 6, a transfer unit 7, a fixing unit 8, a sheet discharge unit 9, and a control unit 10, which are provided in an apparatus main body 2.

[0013] The sheet supply unit 3 is located at the bottom of the device main body 2. The sheet supply unit 3 stores multiple sheets S before printing, and separates and sends out the sheets S one by one during printing. The sheet conveying device 4 extends in the vertical direction along the side wall of the device main body 2. The sheet conveying device 4 conveys the sheet S sent out from the sheet supply unit 3 to the secondary transfer unit 73 and the fixing unit 8, and then discharges the sheet S after fixing from the sheet discharge port 4a to the sheet discharge unit 9. The exposure unit 5 is located above the sheet supply unit 3. The exposure unit 5 irradiates the image forming unit 6 with laser light controlled based on image data.

[0014] The image forming units 6 are disposed above the exposure unit 5 and below the intermediate transfer belt 71. The image forming units 6 include an image forming unit 6Y for yellow, an image forming unit 6C for cyan, an image forming unit 6M for magenta, and an image forming unit 6B for black. These four image forming units 6 have the same basic configuration. Therefore, in the following description, the identification symbols "Y," "C," "M," and "B" representing each color may be omitted unless otherwise specified.

[0015] The image forming unit 6 includes a photosensitive drum that is supported so as to be rotatable in a predetermined direction (clockwise in FIG. 1). The image forming unit 6 also includes a charging unit, a developing unit, and a drum cleaning unit that are arranged around the photosensitive drum along the direction of rotation of the photosensitive drum. A primary transfer unit 72 is arranged between the developing unit and the drum cleaning unit.

[0016] The photosensitive drum has a photosensitive layer formed on its outer circumferential surface. The charging unit charges the outer circumferential surface of the photosensitive drum to a predetermined surface potential. The exposure unit 5 exposes the outer circumferential surface of the photosensitive drum, which has been charged by the charging unit, to light, forming an electrostatic latent image of the original image on the outer circumferential surface of the photosensitive drum, with the charge attenuated. The development unit supplies toner to the electrostatic latent image on the outer circumferential surface of the photosensitive drum, developing it to form a toner image. Each of the four image forming units 6 forms a toner image of a different color. After the toner image is primarily transferred to the outer circumferential surface of the intermediate transfer belt 71, the drum cleaning unit removes and cleans any toner remaining on the outer circumferential surface of the photosensitive drum. In this way, the image forming unit 6 forms an image (toner image) that is later transferred to the sheet S.

[0017] The transfer unit 7 includes an intermediate transfer belt 71, primary transfer units 72Y, 72C, 72M, and 72B, a secondary transfer unit 73, and a belt cleaning unit 74. The intermediate transfer belt 71 is disposed above the four image forming units 6. The intermediate transfer belt 71 is supported so as to be rotatable in a predetermined direction (counterclockwise in FIG. 1), and is an endless intermediate transfer body onto which the toner images formed by each of the four image forming units 6 are sequentially superimposed and primarily transferred. The four image forming units 6 are disposed in a so-called tandem arrangement, lined up in a row from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 71.

[0018] Primary transfer units 72Y, 72C, 72M, and 72B are disposed above image forming units 6Y, 6C, 6M, and 6B of the respective colors, with intermediate transfer belt 71 sandwiched therebetween. Secondary transfer unit 73 is disposed upstream of fixing unit 8 in the sheet conveying direction of sheet conveying device 4, and downstream of four image forming units 6Y, 6C, 6M, and 6B in the rotation direction of intermediate transfer belt 71. Belt cleaning unit 74 is disposed downstream of secondary transfer unit 73 in the rotation direction of intermediate transfer belt 71.

[0019] The primary transfer unit 72 transfers the toner image formed on the outer circumferential surface of the photosensitive drum onto the intermediate transfer belt 71. In other words, the toner image is primarily transferred onto the outer circumferential surface of the intermediate transfer belt 71 at the primary transfer units 72Y, 72C, 72M, and 72B for each color. Then, as the intermediate transfer belt 71 rotates, the toner images of the four image forming units 6 are successively superimposed and transferred onto the intermediate transfer belt 71 at a predetermined timing, thereby forming a color toner image on the outer circumferential surface of the intermediate transfer belt 71 in which toner images of four colors, yellow, cyan, magenta, and black, are superimposed.

[0020] The color toner image on the outer circumferential surface of the intermediate transfer belt 71 is transferred to the sheet S, which is fed synchronously by the sheet conveying device 4, at a secondary transfer nip formed in the secondary transfer unit 73. The belt cleaning unit 74 cleans the outer circumferential surface of the intermediate transfer belt 71 by removing toner and other adhering matter remaining on the outer circumferential surface of the intermediate transfer belt 71 after the secondary transfer. In this way, the transfer unit 7 transfers (records) the toner image formed on the outer circumferential surface of the photosensitive drum onto the sheet S.

[0021] The fixing unit 8 is disposed above the secondary transfer unit 73. The fixing unit 8 fixes the toner image to the sheet S by applying heat and pressure to the sheet S onto which the toner image has been transferred.

[0022] The sheet discharge section 9 is disposed above the transfer section 7. The sheet S on which the toner image has been fixed and printing has been completed is transported to the sheet discharge section 9. The sheet discharge section 9 takes out the printed sheet (printed material) from above.

[0023] The control unit 10 includes a CPU, an image processing unit, a memory unit, and other electronic circuits and electronic components (all not shown). The CPU controls the operation of each component provided in the image forming apparatus 1 based on control programs and data stored in the memory unit to perform processing related to the functions of the image forming apparatus 1. The sheet supply unit 3, the sheet conveying device 4, the exposure unit 5, the image forming unit 6, the transfer unit 7, and the fixing unit 8 each receive individual commands from the control unit 10 and work together to print on the sheet S. The memory unit is configured by a combination of a non-volatile storage device (not shown) such as a program ROM (Read Only Memory) or a data ROM, and a volatile storage device (not shown) such as a RAM (Random Access Memory).

[0024] Next, the configuration of the sheet conveying device 4 will be described using FIG. 2 in addition to FIG. 1. FIG. 2 is a perspective view of the sheet conveying device 4 of the image forming apparatus 1 of FIG. 1. Note that FIG. 2 does not depict components other than the main parts related to the detailed description. The sheet conveying device 4 includes a sheet conveying path 41, an opening / closing section 42 (see FIG. 6), and a pair of registration rollers 43.

[0025] The sheet transport path 41 extends in a substantially vertical direction from the downstream side of the sheet supply unit 3 in the sheet transport direction, through the secondary transfer unit 73 and the fixing unit 8, to the upstream side of the sheet discharge unit 9 in the sheet transport direction. The sheet transport path 41 includes a plurality of pairs of transport rollers including a registration roller pair 43. The sheet transport path 41 transports the sheet S sent out from the sheet supply unit 3 to the secondary transfer unit 73 and the fixing unit 8 by the plurality of transport roller pairs, and further discharges the fixed sheet S from the sheet discharge port 4a to the sheet discharge unit 9.

[0026] The opening / closing unit 42 extends in the vertical direction along the side wall of the device body 2. The opening / closing unit 42 is supported by the device body 2 so as to be swingable around a rotation axis disposed at the lower end and extending in the front-to-rear direction of the device body 2 (the depth direction in the plane of FIG. 1 ), with its upper end as a free end. The opening / closing unit 42 can expose the sheet conveying path 41 including the periphery of the registration roller pair 43 by tilting its upper end sideways away from the device body 2. In other words, the opening / closing unit 42 is attached to the device body 2 so as to be openable and closable.

[0027] The pair of registration rollers 43 is disposed upstream in the sheet conveying direction of the secondary transfer unit 73. The sheet S sent out from the sheet supply unit 3 passes through the sheet conveying path 41 and reaches the position of the pair of registration rollers 43. The control unit 10 corrects skewed feeding of the sheet S using the pair of registration rollers 43, and also adjusts the timing of the toner image formation in the image forming unit 6 and the primary transfer in the transfer unit 7, and sends the sheet S towards the secondary transfer nip portion of the secondary transfer unit 73.

[0028] Next, a detailed configuration of the vicinity of the registration roller pair 43 will be described with reference to FIGS. 3 to 6. FIG. 3 is a partial perspective view of the vicinity of the registration roller pair 43 of the sheet conveying device 4 of FIG. 2. FIGS. 4 and 5 are cross-sectional front views of the vicinity of the registration roller pair 43 of FIG. 3, showing a state in which the conveying guide member is in the guide position and a state in which the conveying guide member is in the retracted position. Note that FIG. 3 depicts an area of ​​the registration roller pair 43 near one end in the sheet width direction perpendicular to the sheet conveying direction. Also, FIGS. 4 and 5 are cross-sectional front views closer to the center in the sheet width direction than the area shown in FIG. 3.

[0029] The pair of registration rollers 43 constitutes a transport roller pair by a first roller 43A and a second roller 43B. The first roller 43A and the second roller 43B are disposed opposite each other. The first roller 43A is rotatably supported by the main body frame 2F of the apparatus main body 2. More specifically, the rotation shaft 43Ax of the first roller 43A is rotatably supported via a bearing (not shown) attached to the main body frame 2F. A bush member 44, a biasing member 45, and a transport guide member 46 are disposed near the pair of registration rollers 43.

[0030] The bushing members 44 are disposed at both ends of the pair of registration rollers 43 in the sheet width direction. The bushing members 44 are formed in a generally rectangular parallelepiped shape extending in the opposing direction of the first roller 43A and the second roller 43B, and are supported by the main frame 2F so as to be movable in the radial direction of the first roller 43A. The bushing members 44 have a hole 44a and a bearing 44b.

[0031] The hole 44a is disposed at a location where the rotation shaft 43Ax of the first roller 43A is located, and penetrates the bushing member 44 in the axial direction of the rotation shaft 43Ax (the sheet width direction). The hole 44a is formed in a substantially cylindrical shape, and the rotation shaft 43Ax is inserted into the hole 44a. Within the range of movement of the bushing member 44 that moves in the radial direction of the first roller 43A, the rotation shaft 43Ax does not come into contact with the inner periphery of the hole 44a.

[0032] The bearing 44b is disposed at a location where the rotation shaft 43Bx of the second roller 43B is located. The bearing 44b is fixed to the bushing member 44 and rotatably supports the rotation shaft 43Bx. In other words, the bushing member 44 rotatably supports the second roller 43B. That is, the second roller 43B is supported by the device body 2 via the bushing member 44. Furthermore, as the bushing member 44 moves in the radial direction of the first roller 43A, the second roller 43B moves in the radial direction of the first roller 43A.

[0033] The biasing member 45 is disposed adjacent to the bushing member 44, on the opposite side of the first roller 43A from the second roller 43B. The biasing member 45 is formed, for example, from a compression coil spring disposed so as to expand and contract in the radial direction of the first roller 43A. One end of the biasing member 45 in the expansion and contraction direction is supported by the main frame 2F, and the other end is supported by the bushing member 44.

[0034] The biasing member 45 biases the bushing member 44, which is movable in the radial direction of the first roller 43A, relative to the main body frame 2F. Specifically, the biasing member 45 biases the bushing member 44 in a direction in which the second roller 43B approaches the first roller 43A, i.e., in the left direction in FIG. 3.

[0035] The transport guide member 46 is attached to the rotation shaft 43Bx of the second roller 43B. The transport guide member 46 has a guide portion 46a and a pair of bearing portions 46b.

[0036] The guide portion 46a extends over the entire area in the sheet width direction of the registration roller pair 43. Furthermore, a region of the guide portion 46a located upstream of the nip portion N of the registration roller pair 43 in the sheet conveying direction extends along the sheet conveying direction toward the nip portion N. The guide portion 46a guides the sheet S being conveyed to the nip portion N of the registration roller pair 43.

[0037] The pair of bearings 46b are disposed at both ends of the guide portion 46a in the sheet width direction. The pair of bearings 46b are rotatably attached to both ends of the rotation shaft 43Bx of the second roller 43B. That is, the conveying guide member 46 rotates around the axis of the rotation shaft 43Bx. By rotating around the axis of the rotation shaft 43Bx, the conveying guide member 46 can move between a guide position (see FIG. 4) where it guides the sheet S on the sheet conveying path 41 and a retracted position (see FIG. 5) where it is retracted from the guide position.

[0038] The main frame 2F also has contacted portions 2Fc that come into contact with and are spaced apart from the pair of bearing portions 46b. The contacted portions 2Fc are disposed radially outward of the second roller 43B and opposed to the bearing portions 46b in the radial direction.

[0039] 4, when the conveying guide member 46 is disposed in the guide position, each of the pair of bearing portions 46b is spaced apart from the contacted portion 2Fc of the main body frame 2F. At this time, the second roller 43B is pressed against the first roller 43A by the biasing force of the biasing member 45, forming a nip portion N for conveying the sheet S.

[0040] 5, when the transport guide member 46 is disposed in the retracted position, each of the pair of bearing portions 46b comes into contact with the contacted portion 2Fc of the main body frame 2F. As a result, the bearing portions 46b of the transport guide member 46 move the bush member 44 against the biasing force of the biasing member 45 in a direction in which the second roller 43B moves away from the first roller 43A.

[0041] According to the above configuration, both the first roller 43A and the second roller 43B of the registration roller pair 43 are supported by the device body 2, which allows for high-precision positioning and stable pressure application. Furthermore, the registration roller pair 43 can easily bring the first roller 43A and the second roller 43B into contact with and separate from each other by moving the conveyance guide member 46. Therefore, jammed sheets S can be easily removed in the sheet conveyance device 4.

[0042] More specifically, each of the pair of bearing portions 46b has an eccentric cam shape having a small diameter portion 46c and a large diameter portion 46d on the outer periphery thereof.

[0043] The length from the central axis of the rotation shaft 43Bx of the second roller 43B to the radial outer edge of the small diameter portion 46c is shorter than the radius of the second roller 43B. Furthermore, when the transport guide member 46 is positioned at the guide position, the small diameter portion 46c faces the contacted portion 2Fc of the main body frame 2F in the radial direction of the second roller 43B. That is, when the transport guide member 46 is positioned at the guide position, the small diameter portion 46c approaches the main body frame 2F, and the bearing portion 46b brings the second roller 43B into contact with the first roller 43A due to the biasing force of the biasing member 45.

[0044] The length from the central axis of the rotation shaft 43Bx of the second roller 43B to the radial outer edge of the large diameter portion 46d is longer than the radius of the second roller 43B. Furthermore, the large diameter portion 46d faces the contacted portion 2Fc of the main body frame 2F in the radial direction of the second roller 43B when the transport guide member 46 is positioned in the retracted position. That is, when the transport guide member 46 is in the retracted position, the large diameter portion 46d comes into contact with the main body frame 2F, and the bearing portion 46b separates the second roller 43B from the first roller 43A against the biasing force of the biasing member 45.

[0045] According to the above configuration, the first roller 43A and the second roller 43B can be easily brought into contact with or separated from each other by simply rotating the conveying guide member 46 around the axis of the second roller 43B. Therefore, in the sheet conveying device 4, it is possible to easily clear a jammed sheet S.

[0046] Furthermore, when the sheet S is sandwiched in the nip portion N of the registration roller pair 43, the sheet S is grasped from the upstream side of the nip portion N in the sheet conveying direction and lifted up, causing the conveying guide member 46 to move from the guide position to the retracted position. More specifically, the conveying guide member 46 rotates counterclockwise from the guide position shown in Fig. 4 to the retracted position shown in Fig. 5. As a result, the second roller 43B moves away from the first roller 43A.

[0047] According to this configuration, when clearing a jam at nip portion N of registration roller pair 43, first roller 43A and second roller 43B can be easily separated simply by removing sheet S. In other words, the operability for the user to clear a jam at nip portion N of registration roller pair 43 can be improved.

[0048] Fig. 6 is a perspective view of the opening / closing unit 42 of the sheet conveying device 4 of the image forming apparatus 1 in Fig. 1. Fig. 7 is a partially enlarged perspective view of the opening / closing unit 42 in Fig. 6. The opening / closing unit 42 is disposed on the opposite side of the first roller 43A across the second roller 43B (see Fig. 1).

[0049] The opening / closing unit 42 has a positioning portion 42a. The positioning portions 42a are arranged on both sides of the center portion in the sheet width direction. The positioning portions 42a are arranged in positions adjacent to the pair of registration rollers 43 when the opening / closing unit 42 is closed. More specifically, when the opening / closing unit 42 is closed, the positioning portion 42a comes into contact with the conveyance guide member 46 arranged at the guide position, and positions the conveyance guide member 46.

[0050] That is, for example, when the opening / closing unit 42 is opened, the conveying guide member 46 disposed in the retracted position comes into contact with the positioning portion 42a of the opening / closing unit 42 as the opening / closing unit 42 is closed. As a result, the conveying guide member 46 rotates clockwise from the retracted position shown in Fig. 5 to move and position itself at the guide position shown in Fig. 4. Then, the second roller 43B comes into contact with the first roller 43A.

[0051] According to this configuration, when the first roller 43A and the second roller 43B are separated from each other, simply closing the opening / closing part 42 makes it possible to easily bring the first roller 43A and the second roller 43B into contact with each other to form the nip part N. In other words, it is possible to improve the operability for the user in clearing a jam at the nip part N of the registration roller pair 43.

[0052] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and various modifications can be made without departing from the spirit of the invention.

[0053] For example, in the above embodiment, the image forming apparatus 1 is a so-called tandem type image forming apparatus for color printing that forms images of multiple colors by sequentially overlapping them, but the image forming apparatus is not limited to this type. The image forming apparatus may be a non-tandem type image forming apparatus for color printing or a monochrome image forming apparatus. [Industrial Applicability]

[0054] The present invention can be used in a sheet transport device and an image forming apparatus. [Explanation of symbols]

[0055] 1. Image forming device 2. Device body 2F Main frame 2Fc Contacted part 3 Sheet supply unit 4 Sheet transport device 41 Sheet transport path 42 Opening and closing section 42a Positioning part 43 Registration roller pair (transport roller pair) 43A First Roller 43Ax Rotating shaft 43B 2nd roller 43Bx Rotating Axis 44 Bush member 45 biasing member 46 Conveyor guide member 46a Guide part 46b Bearing section 46c Small diameter section 46d Large diameter section N Nip S seat

Claims

1. a first roller rotatably supported on a main body frame of the device main body; a second roller disposed opposite the first roller to form a conveying roller pair; a bushing member supported by the main body frame so as to be movable in a radial direction of the first roller and which rotatably supports the second roller; a biasing member that biases the bushing member in a direction in which the second roller approaches the first roller; a conveying guide member that guides the sheet conveyed to the nip portion of the conveying roller pair; Equipped with The sheet conveying device is characterized in that the conveying guide member is attached to the rotation axis of the second roller, is movable between a guide position where it guides the sheet and a retracted position where it is retracted from the guide position, and in the retracted position it contacts the main frame and moves the bush member in a direction where the second roller moves away from the first roller against the biasing force of the biasing member.

2. the transport guide member has a pair of bearings rotatably attached to both ends of the rotation shaft of the second roller, The sheet conveying device described in claim 1, characterized in that the bearing portion has an eccentric cam shape having a small diameter portion and a large diameter portion on its outer periphery, and when the small diameter portion approaches the main body frame at the guide position, the second roller is brought into contact with the first roller by the biasing force of the biasing member, and when the large diameter portion contacts the main body frame at the retracted position, the second roller is separated from the first roller against the biasing force of the biasing member.

3. an opening / closing unit attached to the device body so as to be openable and closable on the opposite side of the first roller across the second roller; 2. The sheet transport device according to claim 1, wherein the opening / closing unit has a positioning portion that, when closed, contacts the transport guide member disposed at the guide position to position the transport guide member.

4. The sheet conveying device according to claim 1, characterized in that by lifting the sheet held in the nip portion of the pair of conveying rollers, the conveying guide member moves from the guide position to the retracted position and the second roller moves away from the first roller.

5. An image forming apparatus comprising the sheet conveying device according to any one of claims 1 to 4.

Images