Sheet conveyance device and image forming apparatus

Abstract

A sheet conveyance device includes a main body frame having an accommodation space, a roller unit that has a roller for conveying a sheet and is insertable into and removable from the accommodation space, and a cover provided at the main body frame so as to be movable between a close position at which the cover covers at least one part of the accommodation space, and an open position at which the cover opens the one part of the accommodation space.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present invention claims priority under 35 U.S.C. § 119 to Japanese patent Application No. 2025-054475 filed on Mar. 27, 2025, of which incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTIONTechnical Field

[0002] The present invention relates to a sheet conveyance device and an image forming apparatus. In particular, the present invention relates to a sheet conveyance device that conveys a sheet and an image forming apparatus that includes the sheet conveyance device.Description of Related Art

[0003] The image forming apparatus includes the sheet conveyance device that contains a plurality of sheets in a stack and forms an image on a sheet supplied one by one from the sheet conveyance device. The sheet conveyance device conveys the plurality of sheets one by one in order starting from the uppermost sheet.

[0004] For example, Japanese Patent No.6676304 describes a sheet conveyance device that is characterized by including a device main body, a rotating body unit that is detachable from the device main body, and a coupling shaft which is provided in the device main body, and to which the rotating body unit can be coupled when the rotating body unit is attached to the device main body, wherein the rotating body unit has a conveyance rotating body that conveys a sheet in a sheet conveyance direction, a guide portion that can guide a sheet, and an engagement portion provided in the guide portion, the guide portion is movable between an engagement position and a movement position with respect to the conveyance rotating body, with the engagement position being a position at which an engaged portion of the device main body and the engagement portion are engaged with each other and the guide portion guides a sheet, and with the movement position being a position to which the guide portion is moved from the engagement position, and arranged at a position at which the guide portion overlaps with the conveyance rotating body as being viewed in the sheet conveyance direction, and in the rotating body unit, the guide portion being located at the movement position is gripped, and the rotating body unit is detached from or attached to the coupling shaft.

[0005] However, in the sheet conveyance device described in Japanese U.S. Pat. No. 6,676,304, the guide portion of the rotating body unit guides a sheet. Therefore, the guide portion must have a shape suitable for guiding a sheet. For this reason, for each of two models having different shapes for guiding a sheet, the shape of a guide portion needs to be suitable for the model. Thus, the same rotating body unit cannot be used for the two models. Further, in a case where a first rotating body unit and a second rotating body unit can be attached to one sheet conveyance device, the same rotating body unit cannot be shared as both the first rotating unit and the second rotating unit.SUMMARY OF THE INVENTION

[0006] According to one aspect of the present invention, a sheet conveyance device includes a main body frame having an accommodation space, a roller unit that has a roller for conveying a sheet and is insertable into and removable from the accommodation space, and a cover provided at the main body frame so as to be movable between a close position at which the cover covers at least one part of the accommodation space, and an open position at which the cover opens the one part of the accommodation space.

[0007] According to yet another aspect of the present invention, an image forming apparatus includes the above-mentioned sheet conveyance device, and an image former that forms an image on a sheet conveyed by the sheet conveyance device.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention.

[0009] FIG. 1 is a perspective view illustrating the appearance of an MFP in one embodiment of the present invention;

[0010] FIG. 2 is a side view schematically illustrating the inner configuration of part of the MFP;

[0011] FIG. 3 is a cross-sectional view illustrating one example of the configuration of a sheet conveyance device;

[0012] FIG. 4 is a first perspective view illustrating part of the MFP;

[0013] FIG. 5 is a second perspective view illustrating part of the MFP;

[0014] FIG. 6 is a perspective view of a sheet feed roller unit;

[0015] FIG. 7 is a front view of an upper cover;

[0016] FIG. 8 is a perspective view of the upper cover;

[0017] FIG. 9 is a front view of a lower cover;

[0018] FIG. 10 is a perspective view of the lower cover;

[0019] FIG. 11 is a perspective view for explaining insertion and removal of the sheet feed roller unit;

[0020] FIG. 12 is a first front view illustrating a fixing mechanism of the sheet feed roller unit;

[0021] FIG. 13 is a side view illustrating the fixing mechanism of the sheet feed roller unit;

[0022] FIG. 14 is a second front view illustrating the fixing mechanism of the sheet feed roller unit; and

[0023] FIG. 15 is a third front view illustrating the fixing mechanism of the sheet feed roller unit.DETAILED DESCRIPTION

[0024] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments.

[0025] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are the same. Therefore, the detailed description thereof will not be repeated.

[0026] FIG. 1 is a perspective view illustrating the appearance of an MFP in one embodiment of the present invention. The Multi Function Peripheral (MFP) 100 is one example of an image forming apparatus. In FIG. 1, an X direction, a Y direction, and a Z direction orthogonal to one another are defined. The X direction and the Y direction are parallel to a horizontal plane. In the following description, the X direction is a direction parallel to the left-right orientation of the MFP 100 and is also referred to as a leftward-and-rightward direction. The direction in which the arrow is directed in the X direction is a rightward direction, and the direction opposite to the direction in which the arrow is directed in the X direction is a leftward direction. The Y direction is parallel to a depth direction of the MFP 100 and is also referred to as a forward-and-rearward direction. The direction opposite to the direction in which the arrow is directed in the Y direction is a forward direction, and the direction in which the arrow is directed in the Y direction is a rearward direction. The Z direction is parallel to the up-down orientation of the MFP 100 and is also referred to as the upward-and-downward direction. The direction in which the arrow is directed in the Z direction is an upward direction, and the direction opposite to the direction in which the arrow is directed in the Z direction is a downward direction.

[0027] With reference to FIG. 1, the MFP 100 has a housing 11 that covers the entire MFP 100. The housing 11 has an inner space, and an image forming section (i.e., image former) 140 that forms an image on a sheet based on image data and a sheet conveyance device 150 that supplies the sheet to the image forming section 140 are arranged in the inner space. The sheet is a recording medium on which an image is formed. The sheet includes a paper, a postcard and an overhead projector (OHP) sheet. Further, in the MFP 100, a side door 11A is arranged at the left side surface of the housing 11. The side door 11A can be opened and closed by rotating about a rotation shaft arranged in the upward-and-downward direction. In an open state where the side door 11A is open, the left part of the inner space of the housing 11 is open to the outside. In a close state where the side door 11A is closed, the inner space of the housing 11 is not opened to the outside.

[0028] FIG. 2 is a side view schematically illustrating the inner configuration of part of the MFP. With reference to FIG. 2, a main conveyance route 41 indicated by the thick dotted line is formed to basically extend in the upward-and-downward direction in the MFP 100. The main conveyance route 41 is a route for guiding a sheet conveyed from the sheet conveyance device 150 to a sheet ejection tray 17 through the image forming section 140. In the main conveyance route 41 of the present example, a lower end portion 43 opposite to an upper end portion 13 located upwardly of the image forming section 140 forms an inlet port for receiving the sheet from the sheet conveyance device 150. Further, the upper end portion 13 of the main conveyance route 41 forms a discharge port for discharging the sheet on which an image has been formed to the sheet ejection tray 17. A sheet ejection roller 15 is provided at the upper end portion 13 of the main conveyance route 41. The lower end portion 43 of the main conveyance route 41 is connected to a plurality of sub-conveyance routes 151a, 152a of the below-mentioned sheet conveyance device 150.

[0029] The sheet conveyance device 150 includes an upper sheet feed tray 151 and a lower sheet feed tray 152. The upper sheet feed tray 151 and the lower sheet feed tray 152 are stacked in this order from above to below. As indicated by the thick one dot chain line in FIG. 2, in the sheet conveyance device 150, the sub-conveyance route 151a extending from the upper sheet feed tray 151 to the lower end portion 43 of the main conveyance route 41 is formed. The sub-conveyance route 152a extending from the lower sheet feed tray 152 to the lower end portion 43 of the main conveyance route 41 is formed.

[0030] A pick roller 211, a sheet feed roller 221 and a separation roller 161 are provided to correspond to the upper sheet feed tray 151. A pick roller 211, a sheet feed roller 221 and a separation roller 161 are provided to correspond to the lower sheet feed tray 152. The pick roller 211, the sheet feed roller 221 and the separation roller 161 provided to correspond to the upper sheet feed tray 151 are provided in the sub-conveyance route 151a. The pick roller 211, the sheet feed roller 221 and the separation roller 161 provided to correspond to the lower sheet feed tray 152 are provided in the sub-conveyance route 152a.

[0031] In the MFP 100, when an image is formed, a tray containing a sheet on which the image is to be formed is selected as a subject tray from among the upper sheet feed tray 151 and the lower sheet feed tray 152. The pick roller 211, the sheet feed roller 221 and the separation roller 161 corresponding to the tray selected as the subject tray from among the upper sheet feed tray 151 and the lower sheet feed tray 152 work. Therefore, in a case where the upper sheet feed tray 151 is selected as the subject tray, the sheet is supplied to the main conveyance route 41 through the sub-conveyance route 151a. Further, in a case where the lower sheet feed tray 152 is selected as the subject tray, the sheet is supplied to the main conveyance route 41 through the sub-conveyance route 152a.

[0032] The image forming section 140 includes respective image forming units 21Y, 21M, 21C, 21K for respective yellow, magenta, cyan, and black. An image is formed on a sheet by driving of at least one of the image forming units 21Y, 21M, 21C, 21K. When all of the image forming units 21Y, 21M, 21C, 21K are driven, a full-color image is formed. Printing data pieces for yellow, magenta, cyan, and black are respectively input to the image forming units 21Y, 21M, 21C, 21K. The only difference among the image forming units 21Y, 21M, 21C, 21K is the colors of toner used by the image forming units 21Y, 21M, 21C, 21K. Here, the image forming unit 21Y for forming an image in yellow will be described.

[0033] The image forming unit 21Y includes an exposure head to which printing data for yellow is input, a photosensitive drum, an electric charger, a developing device, and a transfer roller 23Y. The exposure head emits laser light in accordance with the received printing data (electrical signal). A polygon mirror included in the exposure head scans the emitted laser light one-dimensionally to expose the photosensitive drum. The direction in which the laser light one-dimensionally scans the photosensitive drum is a main scanning direction. After being electrically charged by the electric charger, the photosensitive drum is irradiated with the laser light emitted by the exposure head. Therefore, an electrostatic latent image is formed on the photosensitive drum. Subsequently, toner is applied onto the electrostatic latent image by the developing device, so that a toner image is formed. The toner image formed on the photosensitive drum is transferred onto an intermediate transfer belt 27 by the transfer roller 23Y.

[0034] On the other hand, the intermediate transfer belt 27 is suspended by a driving roller 24 and a roller 24A not to loosen. As the driving roller 24 is rotated in a counterclockwise direction in the diagram, the intermediate transfer belt 27 is rotated in the counterclockwise direction in the diagram at a predetermined speed. The roller 24A is rotated in the counterclockwise direction as the intermediate transfer belt 27 is rotated.

[0035] Therefore, the image forming units 21Y, 21M, 21C, 21K sequentially transfer toner images onto the intermediate transfer belt 27. Timing for transferring toner images onto the intermediate transfer belt 27 by the respective image forming units 21Y, 21M, 21C, 21K is adjusted by detection of a reference mark provided on the intermediate transfer belt 27. Thus, toner images in yellow, magenta, cyan and black are superimposed on the intermediate transfer belt 27.

[0036] In the main conveyance route 41, a timing roller 45, a transfer roller 47 and a fixing roller 49 are arranged in this order at intervals from the lower end portion 43 to the upper end portion 13. A sheet supplied from the sheet conveyance device 150 to the main conveyance route 41 is sent to the timing roller 45.

[0037] The timing roller 45 adjusts the conveyance state of the sheet in the main conveyance route 41 such that the sheet arrives at the transfer roller 47 at the time when a toner image formed on the intermediate transfer belt 27 arrives at the transfer roller 47. The sheet conveyed by the timing roller 45 is pressed against the intermediate transfer belt 27 by the transfer roller 47. Because the transfer roller 47 is electrically charged, yellow, magenta, cyan, and black toner images that are formed on the intermediate transfer belt 27 in a superimposed manner are transferred to the sheet. A voltage to be applied to the transfer roller 47 is controlled by a Central Processing Unit (CPU), so that the charge amount of the transfer roller 47 is adjusted to a value suitable for the basis weight of the sheet.

[0038] The sheet to which the toner image has been transferred is conveyed to the fixing roller 49 and heated by the fixing roller 49. Therefore, the toner is fused and fixed to the sheet. Thereafter, the sheet on which the image has been formed is discharged onto the sheet ejection tray 17 from the upper end portion 13 of the main conveyance route 41 by the sheet ejection roller 15. The temperature of the fixing roller 49 is controlled by the CPU to be suitable for the basis weight of the sheet.

[0039] FIG. 3 is a cross-sectional view illustrating one example of the configuration of the sheet conveyance device. FIG. 3 illustrates the cross section of the MFP 100 taken along a plane orthogonal to the forward-and-rearward direction. With reference to FIG. 3, a sheet feed roller unit 200 is arranged in an upper accommodation space 160 located above the upper sheet feed tray 151. The sheet feed roller unit 200 is fixed to an upper sheet feed frame 159. The upper sheet feed frame 159 is part of the housing 11.

[0040] The sheet feed roller unit 200 includes a holder 201, the pick roller 211 and the sheet feed roller 221. The pick roller 211 and the sheet feed roller 221 are rotatably attached to the holder 201. The sheet feed roller 221 is attached to a sheet feed shaft 223 while being rotatable about an axis of the sheet feed shaft 223. The sheet feed shaft 223 is rotatably supported by the housing 11. The sheet feed shaft 223 is fixed to the housing 11. The holder 201 is rotatable about the axis of the sheet feed shaft 223. The holder 201 is biased by an elastic member such as a spring in a rotation direction such that the pick roller 211 is moved in the downward direction.

[0041] The upper sheet feed tray 151 has an upper lifting-lowering plate 154 located in a bottom portion of the upper sheet feed tray 151. A plurality of sheets P are stacked on the upper lifting-lowering plate 154. When the upper lifting-lowering plate 154 is lifted, the uppermost surface of the plurality of sheets P abuts against the pick roller 211.

[0042] As the upper lifting-lowering plate 154 is further lifted with the uppermost surface of the plurality of sheets P abutting against the pick roller 211, a force for lifting the upper lifting-lowering plate 154 exceeds an elastic force of the elastic member, and the pick roller 211 is lifted. A sensor for measuring the height of the pick roller 211 is provided. When the pick roller 211 reaches a predetermined height, the upward movement of the upper lifting-lowering plate 154 is stopped. Therefore, with the pick roller 211 abutting against the uppermost surface of the sheets P, the pick roller 211 presses the sheet P in the downward direction with a predetermined force. In this state, as the pick roller 211 is rotated, the uppermost sheet of the sheets P is conveyed toward the sheet feed roller 221 by a frictional force generated between the uppermost sheet and the pick roller 211.

[0043] The separation roller 161 is arranged downwardly of the sheet feed roller 221 and comes into contact with the sheet feed roller 221. The separation roller 161 is rotatable about a separation shaft 165. The separation shaft 165 is rotatably supported by a separation holder. The separation shaft 165 is biased upwardly by an elastic body such as a spring. The separation roller 161 is positioned to be opposite to the sheet feed roller 221. With no sheet P being present between the sheet feed roller 221 and the separation roller 161, the separation roller 161 comes into contact with the sheet feed roller 221 and is rotated as the sheet feed roller 221 is rotated. However, a resistance for restricting rotation of the separation roller 161 is provided in the separation shaft 165 of the separation roller 161.

[0044] Two or more sheets may be picked up from the upper sheet feed tray 151 by the pick roller 211 in a superimposed manner. In this case, a stack of two or more sheets enters between the sheet feed roller 221 and the separation roller 161. An uppermost sheet P of the two or more sheets P comes into contact with the sheet feed roller 221, and a lowermost sheet P of the two or more sheets comes into contact with the separation roller 161. Here, two sheets P1, P2 are superimposed on each other, by way of example. It is defined that the dynamic friction coefficient between the sheet feed roller 221 and the uppermost sheet P1 is μ1, the static friction coefficient between the separation roller 161 and the lowermost sheet P2 is μ2, and the static friction coefficient between the uppermost sheet P1 and the lowermost sheet P2 is μ3. The outer peripheral surface of the sheet feed roller 221 and the outer peripheral surface of the separation roller 161 are formed of a material satisfying the relationship of μ1>μ3 and μ2>μ3 and are subjected to surface treatment.

[0045] When the plurality of sheets P1, P2 enter between the sheet feed roller 221 and the separation roller 161, because the resistance for restricting rotation of the separation roller 161 is provided in the separation shaft 165, a force directed in the direction opposite to the conveyance direction is generated in the sheet P2. Because μ2>μ3, the separation roller 161 is not rotated and is stopped while being in contact with the sheet P2. Further, because μ1>μ3, a frictional force, which the sheet P1 receives from the sheet feed roller 221, exceeds a frictional force, which the sheet P1 receives from the sheet P2, and the sheet P1 is conveyed by the sheet feed roller 42.

[0046] An upper conveyance guide 155 is arranged between the upper sheet feed tray 151 and the side door 11A. The upper conveyance guide 155 has an upper inner route surface 157 facing the sheet feed roller 221 and has an upper outer route surface 158 facing the side door 11A. The side door 11A has a door route surface 12 facing the upper conveyance guide 155. The upper conveyance guide 155 is arranged at a predetermined distance from the side door 11A. The upper outer route surface 158 and the door route surface 12 form part of the sub-conveyance route 152a.

[0047] The upper conveyance guide 155 is exposed in the leftward direction of the housing 11 with the side door 11A opened, and a user can access the upper conveyance guide 155. A lower portion of the upper conveyance guide 155 is rotatably connected to an upper guide shaft 156. The upper guide shaft 156 is fixed to the housing 11 while extending in parallel with the forward-and-rearward direction. The upper conveyance guide 155 rotates about the upper guide shaft 156 to move between a close position and an open position. FIG. 5 illustrates the upper conveyance guide 155 being located at the close position.

[0048] An upper cover 251 is arranged adjacent to, above and rightwardly (in the direction indicated by the arrow X) of the upper conveyance guide 155. With the upper conveyance guide 155 located at the open position, the upper cover 251 is exposed in the leftward direction, and the user can access the upper cover 251.

[0049] The upper cover 251 has an upper cover route surface 254 that faces the upper conveyance guide 155. The upper cover route surface 254 faces the upper inner route surface 157 of the upper conveyance guide 155. The sheet P1 conveyed by the sheet feed roller 221 advances through the space between the upper inner route surface 157 of the upper conveyance guide 155 and the upper cover route surface 254 of the upper cover 251. The upper cover route surface 254 and the upper inner route surface 157 form part of the sub-conveyance route 151a.

[0050] A lower portion of the upper cover 251 is rotatably connected to a cover front shaft 255. The cover front shaft 255 is fixed to the housing 11 while extending in parallel with the forward-and-rearward direction. The upper cover 251 moves between a close position and an open position by rotating about the cover front shaft 255. FIG. 5 illustrates the upper cover 251 being located at the close position. While being located at the close position, the upper cover 251 covers the left part of the upper accommodation space 160.

[0051] A lower conveyance guide 155A is arranged between the lower sheet feed tray 152 and the side door 11A. The lower conveyance guide 155A has a lower inner route surface 157A facing the sheet feed roller 221, and a lower outer route surface 158A facing the side door 11A. The side door 11A has the door route surface 12 facing the lower conveyance guide 155A. The lower conveyance guide 155A is arranged at a predetermined distance from the side door 11A. The lower outer route surface 158A and the door route surface 12 form part of the sub-conveyance route. The sub-conveyance route, part of which is formed of the lower outer route surface 158A and the door route surface 12, is a route through which the sheet P discharged from an additional tray added below the lower sheet feed tray 152 passes.

[0052] The lower conveyance guide 155A is exposed in the leftward direction of the housing 11 with the side door 11A opened, and the user can access the lower conveyance guide 155A. A lower portion of the lower conveyance guide 155A is rotatably connected to a lower guide shaft 156A. The lower guide shaft 156A is fixed to the housing 11 while extending in parallel with the forward-and-rearward direction. The lower conveyance guide 155A moves between a close position and an open position by rotating about the lower guide shaft 156A. FIG. 5 illustrates the lower conveyance guide 155A being located at the close position.

[0053] A lower cover 251A is arranged to be adjacent to, above and rightwardly of the lower conveyance guide 155A. With the lower conveyance guide 155A located at the open position, the lower cover 251A is exposed in the leftward direction, and the user can access the lower cover 251A.

[0054] The lower cover 251A has a lower cover route surface 254A that faces the lower conveyance guide 155A. The lower cover route surface 254A faces the lower inner route surface 157A of the lower conveyance guide 155A. The sheet P1 conveyed by the sheet feed roller 221 advances through the space between the lower inner route surface 157A of the lower conveyance guide 155A and the lower cover route surface 254A of the lower cover 251A. The lower cover route surface 254A and the lower inner route surface 157A form part of an additional sub-conveyance route. Note that the additional sub-conveyance route is a route through which a sheet contained in the additional tray added below the lower sheet feed tray 152 passes.

[0055] A lower portion of the lower cover 251A is rotatably connected to the cover front shaft 255. The cover front shaft 255 is fixed to the housing 11 while extending in parallel with the forward-and-rearward direction. The lower cover 251A moves between a close position and an open position by rotating about the cover front shaft 255. FIG. 5 illustrates the lower cover 251A being located at the close position. While being located at the close position, the lower cover 251A covers the left part of a lower accommodation space 160A.

[0056] The upper cover route surface 254 of the upper cover 251 forms part of the sub-conveyance route 151a. The lower cover route surface 254A of the lower cover 251A forms part of the sub-conveyance route 152a. The sub-conveyance route 151a and the sub-conveyance route 152a have different shapes. Therefore, the upper cover route surface 254 and the lower cover route surface 254A have different shapes, and the upper cover 251 and the lower cover 251A have different shapes.

[0057] FIG. 4 is a first perspective view illustrating part of the MFP. FIG. 4 illustrates the MFP 100 with the side door 11A opened. With the side door 11A opened, the upper conveyance guide 155 and the lower conveyance guide 155A are exposed to the outside of the main body. On the inner surface of the side door 11A, a door route surface 12 forming parts of the sub-conveyance routes 151a, 152a and part of the main conveyance route 41 is formed.

[0058] With the side door 11A opened, the user can rotate the upper conveyance guide 155 about the upper guide shaft 156. Further, the user can rotate the lower conveyance guide 155A about the lower guide shaft 156A.

[0059] FIG. 5 is a second perspective view illustrating part of the MFP. FIG. 5 illustrates the upper conveyance guide 155 and the lower conveyance guide 155A being respectively located at the open positions. In this state, the user can access the upper cover 251 and the lower cover 251A. FIG. 5 illustrates the upper cover 251 and the lower cover 251A being respectively located at the open positions.

[0060] With the upper cover 251 located at the open position, the left part of the upper accommodation space 160 is open to the outside. Thus, the user can insert the sheet feed roller unit 200 into the upper accommodation space 160 and remove the sheet feed roller unit 200 from the upper accommodation space 160.

[0061] With the lower cover 251A located at the open position, the left part of the lower accommodation space 160A is open to the outside. Thus, the user can insert the sheet feed roller unit 200 into the lower accommodation space 160A and remove the sheet feed roller unit 200 from the lower accommodation space 160A.

[0062] FIG. 6 is a perspective view of the sheet feed roller unit. With reference to FIG. 6, the sheet feed roller unit 200 includes the holder 201 and an operation lever 230. The holder 201 includes a coupler 201C, a front holder 201A and a rear holder 201B. The front holder 201A and the rear holder 201B are arranged to be opposite to each other. The coupler 201C has a shape extending in the Y direction. The coupler 201C connects the front holder 201A and the rear holder 201B to each other. The coupler 201C, the front holder 201A and the rear holder 201B may be formed as an integrated holder 201. The front holder 201A has an insertion guide 203 projecting from the front holder 201A in the direction opposite to the direction directed toward the rear holder 201B.

[0063] The front holder 201A and the rear holder 201B respectively support a separating shaft 213. The separating shaft 213 is fixed to the front holder 201A and the rear holder 201B. The separating shaft 213 projects from the rear holder 201B in the direction opposite to the direction in which the rear holder 201B is directed toward the front holder 201A. The pick roller 211 and a separating gear 215 are arranged between a position at which the separating shaft 213 is supported by the front holder 201A and a position at which the separating shaft 213 is rotatably supported by the rear holder 201B. The pick roller 211 and the separating gear 215 are respectively rotatably connected to the separating shaft 213. The pick roller 211 and the separating gear 215 may be respectively connected to the separating shaft 213 via bearings. The pick roller 211 and the separating gear 215 are coupled to each other. Therefore, the pick roller 211 is rotated as the separating gear 215 is rotated.

[0064] In the front holder 201A, a through hole through which the sheet feed shaft 223 extends is provided. In the rear holder 201B, a through hole through which the sheet feed shaft 223 extends is provided. The sheet feed shaft 223 is connected to the front holder 201A and the rear holder 201B while passing through the respective through holes of the front holder 201A and the rear holder 201B. The front holder 201A and the rear holder 201B are respectively rotatably connected to the sheet feed shaft 223. Bearings may be provided in the respective through holes of the front holder 201A and the rear holder 201B. The front holder 201A and the rear holder 201B are respectively connected to the sheet feed shaft 223 via the bearings.

[0065] In the section of the sheet feed roller unit 200 that is located farther advanced, from the rear holder 201B, in the direction opposite to the direction in which the rear holder 201B is directed toward the front holder 201A, a rear bearing 224B and a docking gear 225 are connected to the sheet feed shaft 223. The rear bearing 224B is a bearing, and an inner ring is fixed to the sheet feed shaft 223. The docking gear 225 is fixed to the sheet feed shaft 223. The docking gear 225 is engaged with a gear connected to a motor provided in the MFP 100 with the sheet feed roller unit 200 attached to the MFP 100. In a case where a rotational force of the motor is transmitted to the docking gear 225, the sheet feed shaft 223 is rotated. Here, the motor is controlled such that the sheet feed shaft 223 is rotated in one direction. Here, the direction in which the sheet feed shaft 223 is rotated is referred to as a normal rotation direction.

[0066] The sheet feed roller 221, a first clutch 227 and a second clutch 229 are arranged between a position at which the sheet feed shaft 223 supports the front holder 201A and a position at which the sheet feed shaft 223 supports the rear holder 201B. The sheet feed roller 221 is connected to the sheet feed shaft 223 while being rotatable about the sheet feed shaft 223. The first clutch 227 is a one-way clutch and has a first fixed portion and a first movable portion. The first fixed portion is fixed to the sheet feed shaft 223, and the first movable portion is not fixed to the sheet feed shaft 223. The first movable portion is rotatable about the sheet feed shaft 223. The first movable portion is connected to the sheet feed roller 221. Power is transmitted from the first fixed portion to the first movable portion in a case where the sheet feed shaft 223 is rotated in the normal rotation direction. Power is not transmitted from the first fixed portion to the first movable portion in a case where the sheet feed shaft 223 is rotated in the direction opposite to the normal rotation direction. The first movable portion is rotatable in the normal rotation direction about the sheet feed shaft 223 even in a case where the first fixed portion is stopped.

[0067] The distance between the position at which the front holder 201A supports the separating shaft 213 and the through hole through which the sheet feed shaft 223 passes is equal to the distance between the position at which the rear holder 201B supports the separating shaft 213 and the through hole through which the sheet feed shaft 223 passes. Therefore, the holder 201 supports the separating shaft 213 and the sheet feed shaft 223 extending in parallel with each other.

[0068] The second clutch 229 is a one-way clutch and has a second fixed portion and a second movable portion. The second fixed portion is fixed to the sheet feed shaft 223, and the second movable portion is not fixed to the sheet feed shaft 223. The second movable portion is rotatable about the sheet feed shaft 223. The second movable portion is engaged with a coupling gear 217. Power is transmitted from the second fixed portion to the second movable portion in a case where the sheet feed shaft 223 is rotated in the normal rotation direction. Power is not transmitted from the second fixed portion to the second movable portion in a case where the sheet feed shaft 223 is rotated in the direction opposite to the normal rotation direction. The second movable portion is rotatable in the normal rotation direction about the sheet feed shaft 223 even in a case where the second fixed portion is stopped.

[0069] The coupling gear 217 is rotatably connected to a shaft extending from the rear holder 201B toward the front holder 201A. The coupling gear 217 is engaged with the separating gear 215 and the second movable portion of the second clutch 229. The coupling gear 217 transmits the power transmitted from the second clutch 229 to the separating gear 215.

[0070] In a case where the sheet feed shaft 223 is rotated in the normal rotation direction, the sheet feed roller 221 and the pick roller 211 are rotated in the normal rotation direction. Slippage may occur between the sheet feed roller 221 and a sheet, and slippage may also occur between the pick roller 211 and the sheet. In this case, due to the effect of the first clutch 227 and the second clutch 229, one of the clutches does not rotate. Therefore, even in a case where slippage occurs during the conveyance of the sheet in one of the sheet feed roller 221 and the pick roller 211, the sheet can be efficiently conveyed.

[0071] The operation lever 230 includes a coupling portion 233, a front fixing portion 231, and a rear fixing portion 232. The coupling portion 233 has a shape that is elongated in the Y direction. The coupling portion 233 has an upper surface and a lower surface that intersect with each other in the upward-and-downward direction and face away from each other. The distance between the upper surface and the lower surface is equal to or smaller than a predetermined distance. Thus, the user can grip the coupling portion 233 while holding the upper surface and the lower surface between two fingers of one hand. In the coupling portion 233, a plurality of grooves arranged in the forward-and-rearward direction are formed. Thus, the user can easily press the upper surface of the coupling portion 233 from above with at least one finger.

[0072] In the both ends in the Y direction of the coupling portion 233, a front fixing boss 235 and a rear fixing boss 236 that project outwardly are provided. The front fixing boss 235 and the rear fixing boss 236 are respectively columnar, and rotationally symmetric axes are located on the same straight line extending in parallel with the forward-and-rearward direction.

[0073] The front fixing portion 231 and the rear fixing portion 232 extending in the X direction are respectively connected to both ends in the Y direction of the coupling portion 233. Each of the front fixing portion 231 and the rear fixing portion 232 has a plate shape extending in the X direction from the coupling portion 233. In the front fixing portion 231, a hole through which the sheet feed shaft 223 passes is formed. In the rear fixing portion 232, a hole through which the sheet feed shaft 223 passes is formed. The front fixing portion 231 and the rear fixing portion 232 are respectively rotatably connected to the sheet feed shaft 223. The front fixing portion 231 and the rear fixing portion 232 may be respectively connected to the sheet feed shaft 223 via bearings. Therefore, the operation lever 230 is rotatable about the sheet feed shaft 223. Hence, the front fixing boss 235 and the rear fixing boss 236 are rotatable about the axis of the sheet feed shaft 223.

[0074] FIG. 7 is a front view of the upper cover. FIG. 8 is a perspective view of the upper cover. With reference to FIGS. 7 and 8, the upper cover 251 includes an upper cover main body portion 252, a cover front fixing portion 253, and a cover rear fixing portion 253A. The cover front fixing portion 253 and the cover rear fixing portion 253A have symmetrical shapes with respect to the X-Z plane.

[0075] The upper cover main body portion 252 has a plate shape elongated in the Y direction. The upper cover main body portion 252 has an upper surface and the upper cover route surface 254 which intersect with each other in the upward-and-downward direction and face away from each other.

[0076] The cover front fixing portion 253 and the cover rear fixing portion 253A are connected to the upper cover main body portion 252 at positions spaced apart from each other by a predetermined distance in the Y direction. The cover front fixing portion 253 and the cover rear fixing portion 253A respectively have shapes extending in the X direction from the upper cover main body portion 252.

[0077] The cover front fixing portion 253 has a cover front shaft 255 projecting forwardly. In the cover front fixing portion 253, a front through hole 257 is formed at a position spaced apart from the cover front shaft 255 by a predetermined distance. The cover front fixing portion 253 has a front fixing surface 259 facing upwardly.

[0078] The cover rear fixing portion 253A has a cover rear shaft 255A projecting rearwardly. The cover front shaft 255 and the cover rear shaft 255A are columnar, and their respective rotationally symmetric axes are arranged on the same straight line extending in parallel with the Y direction.

[0079] A rear through hole 257A is formed at a position spaced apart from the cover rear shaft 255A by a predetermined distance. The distance between the cover rear shaft 255A and the rear through hole 257A is equal to the distance between the cover front shaft 255 and the front through hole 257. The cover rear fixing portion 253A has a rear fixing surface 259A facing upwardly.

[0080] The cover front shaft 255 and the cover rear shaft 255A are rotatably connected to the housing 11. Therefore, the upper cover 251 is rotated about the respective axes of the cover front shaft 255 and the cover rear shaft 255A and is movable between the open position and the close position.

[0081] FIG. 9 is a front view of the lower cover. FIG. 10 is a perspective view of the lower cover. With reference to FIGS. 9 and 10, the lower cover 251A includes a lower cover main body portion 252A, a cover front fixing portion 253 and a cover rear fixing portion 253A. The cover front fixing portion 253 and the cover rear fixing portion 253A respectively have the same shapes as those of the cover front fixing portion 253 and the cover rear fixing portion 253A of the upper cover 251. Therefore, a description thereof will not be repeated.

[0082] The lower cover main body portion 252A has a plate shape elongated in the Y direction. The lower cover main body portion 252A has an upper surface and the lower cover route surface 254A which intersect with each other in the upward-and-downward direction and face away from each other.

[0083] The lower cover route surface 254A has a different shape from that of the upper cover route surface 254 of the upper cover 251.

[0084] The cover front shaft 255 and the cover rear shaft 255A of the lower cover 251A are rotatably connected to the housing 11. Therefore, the lower cover 251A is rotated about the respective axes of the cover front shaft 255 and the cover rear shaft 255A, and is movable between the open position and the close position.

[0085] FIG. 11 is a perspective view for illustrating insertion and removal of the sheet feed roller unit. FIG. 11 illustrates the upper cover 251 being located at the open position. FIG. 11 also illustrates the sheet feed roller unit 200 being accommodated in the upper accommodation space 160 located below the upper sheet feed frame 159.

[0086] A front guide portion 271 and a rear guide portion 272 are fixed to the upper sheet feed frame 159. The front guide portion 271 and the rear guide portion 272 are arranged side by side in the Y direction and have symmetrical shapes with respect to the X-Z plane. The front guide portion 271 has, on its surface facing the rear guide portion 272, a front fixing pin 273 projecting toward the rear guide portion 272. The rear guide portion 272 has on its surface facing the front guide portion 271, a rear fixing pin 274 projecting toward the front guide portion 271. The front fixing pin 273 and the rear fixing pin 274 are columnar, and their respective rotationally symmetric axis are located on the same straight line extending in parallel with the Y direction.

[0087] In this state, as the upper cover 251 moves to the close position, the front fixing pin 273 is elastically deformed and enters the front through hole 257, and the rear fixing pin 274 is elastically deformed and enters the rear through hole 257A. Therefore, the upper cover 251 is positioned with respect to the front guide portion 271 and is located at the close position.

[0088] In a period during which the upper cover 251 moves from the open position to the close position, the front fixing boss 235 of the operation lever 230 is elastically deformed and enters the front through hole 257, and the rear fixing boss 236 is elastically deformed and enters the rear through hole 257A. Thus, the operation lever 230 moves together with the upper cover 251 to move from a grip position to a retracted position. The operation lever 230 is rotated about the sheet feed shaft 223, and the upper cover 251 is rotated about the cover front shaft 255 and the cover rear shaft 255A. For this reason, the outer diameter of the front fixing boss 235 and the outer diameter of the rear fixing boss 236 are smaller than the inner diameter of the front through hole 257 and the inner diameter of the rear through hole 257A.

[0089] FIG. 12 is a first front view illustrating a fixing mechanism of the sheet feed roller unit. FIG. 12 is a diagram illustrating the upper accommodation space 160 as viewed in the rearward direction (the direction in which the arrow is directed in the Y direction). FIG. 13 is a side view illustrating the fixing mechanism of the sheet feed roller unit. FIG. 13 is a diagram of the upper accommodation space 160 as viewed in the leftward direction (the direction in which the arrow is directed in the X direction). FIGS. 12 and 13 illustrate, as one example of the fixing mechanism, a front bearing 224A of the sheet feed roller unit 200 being fixed by the front guide portion 271 and the cover front fixing portion 253. The same applies to a case where the rear bearing 224B of the sheet feed roller unit 200 is fixed by the rear guide portion 272 and the cover rear fixing portion 253A.

[0090] The front guide portion 271, the cover front fixing portion 253 and the front fixing portion 231 partially overlap with one another in the rearward direction (the direction in which the arrow is directed in the Y direction). The front guide portion 271, the cover front fixing portion 253 and the front fixing portion 231 are arranged in this order in the rearward direction (the direction in which the arrow is directed in the Y direction). The front guide portion 271 is fixed to the upper sheet feed frame 159. The cover front shaft 255 of the cover front fixing portion 253 is rotatably supported by a front cover bearing 277 formed at the front guide portion 271. The front guide portion 271 is rotatable about the cover front shaft 255. The front guide portion 271 includes a stopper 279 that projects rearwardly (in the direction in which the arrow is directed in the Y direction). The rotation range of the cover front fixing portion 253 is restricted by the stopper 279, and the cover front fixing portion 253 is positioned at an open position. When the upper cover 251 is located at the open position, the front cover bearing 277 and the front through hole 257 are substantially horizontal. With the upper cover 251 located at the open position, the upper surface of the upper cover main body portion 252 of the upper cover 251 is substantially horizontal. Therefore, while being located at the open position, the upper cover 251 guides the sheet feed roller unit 200 to be inserted into and removed from the upper accommodation space 160.

[0091] The operation lever 230 is rotatable about the sheet feed shaft 223. In the operation lever 230, a sliding groove 237 is formed in part of a portion that comes into contact with the sheet feed shaft 223. A lever stopper 228 fixed to the front bearing 224A is arranged in the sliding groove 237. Therefore, the range in which the operation lever 230 is rotated is restricted by the lever stopper 228 and the sliding groove 237. The lever stopper 228 and the sliding groove 237 define the grip position of the operation lever 230. With the operation lever 230 located at the grip position, the coupling portion 233 of the operation lever 230 is substantially horizontal. Thus, the user can easily grip the coupling portion 233.

[0092] FIG. 14 is a second front view illustrating the fixing mechanism of the sheet feed roller unit. FIG. 14 illustrates the upper cover 251 that has moved from the open position to the close position. Further, as the upper cover 251 moves from the open position toward the close position, the front fixing boss 235 is fitted to the front through hole 257. Thus, the upper cover 251 is fitted to the operation lever 230. Thereafter, the operation lever 230 is moved as the upper cover 251 is rotated. Then, the upper cover 251 reaches the close position.

[0093] FIG. 15 is a third front view illustrating the fixing mechanism of the sheet feed roller unit. FIG. 15 illustrates the upper cover 251 being located at the close position. With the upper cover 251 being located at the close position, the front fixing pin 273 enters the front fixing boss 235. Thus, the upper cover 251 is fitted to the front guide portion 271. At this stage, the upper cover 251 is positioned at the close position, and the operation lever 230 is positioned at the retracted position.

[0094] Further, the front fixing surface 259 of the upper cover 251 abuts against the front bearing 224A. With the upper cover 251 located at the close position, the front fixing surface 259 is located to face a front fixing surface 275 of the front guide portion 271. The front fixing surface 259 faces in an insertion direction in which the sheet feed roller unit 200 is inserted into the upper accommodation space 160. Therefore, the front fixing surface 259 of the upper cover 251 abuts against the front bearing 224A, and the upper cover 251 restricts movement of the sheet feed roller unit 200 in the direction opposite to the insertion direction. The front bearing 224A is supported while being interposed between the front guide portion 271 and the upper cover 251. Therefore, the front bearing 224A is positioned, which causes the sheet feed roller unit 200 to be positioned with respect to the upper sheet feed frame 159.

[0095] In a period during which the upper cover 251 moves from the close position to the open position, the operation lever 230 is moved as the upper cover 251 is moved. When the operation lever 230 reaches the grip position, the rotation of the operation lever 230 is restricted. At this stage, the operation lever 230 is positioned at the grip position. As the upper cover 251 is further moved toward the open position, the fitting of the operation lever 230 to the upper cover 251 is released, and the upper cover 251 is rotated alone until it reaches the open position.Modification Examples(1) In the above-mentioned embodiment, the MFP 100 is described as one example of an image forming apparatus. The image forming apparatus is only required to be an apparatus capable of forming an image. For example, the image forming apparatus may be a printer or a facsimile machine. Further, the printer may be an apparatus that forms an image using toner or may be an inkjet printer that forms an image using ink.

[0097] (2) While being described as part of the MFP 100, the sheet conveyance device 150 may be a device separate from the MFP 100.Overview of Embodiment(Item 1) A sheet conveyance device includes a main body frame having an accommodation space, a roller unit that has a roller for conveying a sheet and is insertable into and removable from the accommodation space, and a cover provided at the main body frame so as to be movable between a close position at which the cover covers at least one part of the accommodation space, and an open position at which the cover opens the one part of the accommodation space.

[0099] According to this aspect, the roller unit is insertable into and removable from the accommodation space of the main body frame. The cover that is movable between the close position at which the cover covers at least part of the accommodation space and the open position at which the accommodation space is opened is provided at the main body frame. The roller unit can be removed from the accommodation space with the cover located at the open position. The roller unit can be accommodated in the accommodation space with the cover located at the close position. Because being provided at the main body frame, the cover can be formed in a shape corresponding to the shape of the main body frame. The shape of the roller unit is defined regardless of the shape of the cover. Therefore, the roller unit can be also used in the sheet conveyance device of another type. As a result, it is possible to provide the sheet conveyance device with the standardized roller unit. The housing 11 corresponds to the main body frame, the upper accommodation space 160 and the lower accommodation space 160A correspond to the accommodation space, and the sheet feed roller unit 200 corresponds to the roller unit. The upper cover 251 and the lower cover 251A correspond to the cover.

[0100] (Item 2) The sheet conveyance device according to item 1, wherein the roller unit includes a first roller unit and a second roller unit that have a same shape, the accommodation space includes a first accommodation space in which the first roller unit is accommodatable and a second accommodation space in which the second roller unit is accommodatable, the cover includes a first cover covering the first accommodation space and a second cover covering the second accommodation space, and the first cover and the second cover have different shapes.

[0101] According to this aspect, the first cover opens and closes the first accommodation space capable of accommodating the first roller unit, and the second cover opens and closes the second accommodation space capable of accommodating the second roller unit having the same shape as the first roller unit. The first cover and the second cover have different shapes. Therefore, it is not necessary to distinguish between the first roller unit and the second roller unit. It facilitates the replacement work performed by the user. The upper accommodation space 160 corresponds to the first accommodation space, and the lower accommodation space 160A corresponds to the second accommodation space. The sheet feed roller unit 200 accommodated in the upper accommodation space 160 corresponds to the first roller unit, and the sheet feed roller unit 200 accommodated in the lower accommodation space 160A corresponds to the second roller unit. The upper cover 251 corresponds to the first cover, and the lower cover 251A corresponds to the second cover.

[0102] (Item 3) The sheet conveyance device according to item 1 or 2, wherein the cover has a conveyance surface forming part of a conveyance route through which a sheet conveyed by the roller passes.

[0103] According to this aspect, the cover has the conveyance surface that forms part of the conveyance route. For this reason, the shape of the roller unit does not need to match the shape of the conveyance route. Therefore, standardization of the roller unit is easy. The upper cover route surface 254 of the upper cover 251 and the lower cover route surface 254A of the lower cover 251A respectively correspond to the conveyance surface.

[0104] (Item 4) The sheet conveyance device according to any one of items 1 to 3, wherein the cover has a fixing portion that fixes the roller unit accommodated in the accommodation space to the main body frame with the cover located at the close position.

[0105] According to this aspect, the fixing portion fixes the roller unit to the main body frame with the cover located at the close position. Thus, the user can insert the roller unit by performing an operation of opening and closing the cover. This facilitates replacement of the roller unit performed by the user. The front fixing surface 259 and the rear fixing surface 259A of the upper cover 251 correspond to the fixing portion, and the front fixing surface 259 and the rear fixing surface 259A of the lower cover 251A correspond to the fixing portion.

[0106] (Item 5) The sheet conveyance device according to item 4, wherein the fixing portion is provided on a surface facing in an insertion direction in which the roller unit is inserted into the accommodation space.

[0107] According to this aspect, fixing portion is provided on the surface facing in the insertion direction in which the roller unit is inserted, so that the fixing portion abuts against the roller unit in the direction opposite to the insertion direction in which the roller unit is inserted. Therefore, the roller unit can be easily fixed to the main body frame.

[0108] (Item 6) The sheet conveyance device according to item 4 or 5, wherein the main body frame has a first fixing surface that faces in a direction opposite to an insertion direction in which the roller unit is inserted into the accommodation space, and the cover has a second fixing surface that is located at a position opposite to the first fixing surface and faces in the insertion direction with the cover located at the close position.

[0109] According to this aspect, movement of the roller unit in the insertion direction is restricted by the first fixing surface of the main body frame, and movement of the roller unit in the direction opposite to the insertion direction is restricted by the second fixing surface of the cover located at the close position. For this reason, with the cover member located at the close position, the movement of the roller unit in the direction parallel to the insertion direction is restricted. Thus, the user can fix the roller unit to the main body frame by performing an operation of opening and closing the cover. The front fixing surface 275 of the front guide portion 271 corresponds to the first fixing surface, and the front fixing surface 259 of the upper cover 251 corresponds to the second fixing surface.

[0110] (Item 7) The sheet conveyance device according to any one of items 4to 6, wherein the main body frames has a first engagement portion, and the cover has a first engaged portion engaged with the first engagement portion with the cover located at the close position.

[0111] According to this aspect, the first engaged portion is engaged with the first engagement portion of the main body frame with the cover located at the close position. Therefore, the cover located at the close position can be positioned with respect to the main body frame. The front fixing pin 273 of the front guide portion 271 corresponds to the first engagement portion, and the front through hole 257 of the upper cover 251 corresponds to the first engaged portion.

[0112] (Item 8) The sheet conveyance device according to any one of items 1 to 7, wherein the roller unit further has a grip portion provided on a side surface facing in a direction opposite to an insertion direction in which the roller unit is inserted into the accommodation space.

[0113] According to this aspect, because in the roller unit, the grip portion is provided on the side surface facing in the direction opposite to the insertion direction, the user can insert the roller unit into the accommodation space while gripping the grip portion. The coupling portion 233 of the operation lever 230 corresponds to the grip portion.

[0114] (Item 9) The sheet conveyance device according to item 8, wherein the grip portion is movable between a retracted position and a grip position that are defined with respect to the roller, and moves between the retracted position and the grip position in conjunction with movement of the cover between the open position and the close position.

[0115] According to this aspect, the grip portion moves between the retracted position and the grip position in conjunction with the movement of the cover between the open position and the close position. Therefore, the grip portion moves in conjunction with the opening and closing of the cover, which enables movement of the grip portion to the grip position at which the user can easily grip the grip portion with the cover located at the open position.

[0116] (Item 10) The sheet conveyance device according to item 8 or 9, wherein the cover has a second engagement portion, and the grip portion has a second engaged portion engaged with the second engagement portion.

[0117] According to this aspect, because the second engaged portion of the grip portion is engaged with the second engagement portion of the cover, the grip portion can be moved in conjunction with the opening and closing of the cover. The front through hole 257 of the upper cover 251 corresponds to the second engagement portion, and the front fixing boss 235 of the coupling portion 233 corresponds to the second engaged portion.

[0118] (Item 11) An image forming apparatus includes the sheet conveyance device according to any one of items 1 to 10, and an image former that forms an image on a sheet conveyed by the sheet conveyance device.

[0119] According to this aspect, it is possible to provide the image forming apparatus with the standardized roller unit.

[0120] It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined not by the above description but by the appended claims and is intended to include any modifications within the scope and meaning equivalent to the appended claims.

[0121] Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purpose of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.

Claims

1. A sheet conveyance device comprising:a main body frame having an accommodation space;a roller unit that has a roller for conveying a sheet and is insertable into and removable from the accommodation space; anda cover provided at the main body frame so as to be movable between a close position at which the cover covers at least one part of the accommodation space, and an open position at which the cover opens the one part of the accommodation space.

2. The sheet conveyance device according to claim 1, whereinthe roller unit includes a first roller unit and a second roller unit that have a same shape,the accommodation space includes a first accommodation space in which the first roller unit is accommodatable and a second accommodation space in which the second roller unit is accommodatable,the cover includes a first cover covering the first accommodation space and a second cover covering the second accommodation space, andthe first cover and the second cover have different shapes.

3. The sheet conveyance device according to claim 1, whereinthe cover has a conveyance surface forming part of a conveyance route through which a sheet conveyed by the roller passes.

4. The sheet conveyance device according to claim 1, whereinthe cover has a fixing portion that fixes the roller unit accommodated in the accommodation space to the main body frame with the cover located at the close position.

5. The sheet conveyance device according to claim 4, whereinthe fixing portion is provided on a surface facing in an insertion direction in which the roller unit is inserted into the accommodation space.

6. The sheet conveyance device according to claim 4, whereinthe main body frame has a first fixing surface that faces in a direction opposite to an insertion direction in which the roller unit is inserted into the accommodation space, andthe cover has a second fixing surface that is located at a position opposite to the first fixing surface and faces in the insertion direction with the cover located at the close position.

7. The sheet conveyance device according to claim 4, whereinthe main body frames has a first engagement portion, andthe cover has a first engaged portion engaged with the first engagement portion with the cover located at the close position.

8. The sheet conveyance device according to claim 1, whereinthe roller unit further has a grip portion provided on a side surface facing in a direction opposite to an insertion direction in which the roller unit is inserted into the accommodation space.

9. The sheet conveyance device according to claim 8, whereinthe grip portion is movable between a retracted position and a grip position that are defined with respect to the roller, and moves between the retracted position and the grip position in conjunction with movement of the cover between the open position and the close position.

10. The sheet conveyance device according to claim 8, whereinthe cover has a second engagement portion, andthe grip portion has a second engaged portion engaged with the second engagement portion.

11. An image forming apparatus comprising:the sheet conveyance device according to claim 1; andan image former that forms an image on a sheet conveyed by the sheet conveyance device.

Images