Image forming device

Abstract

To improve relative alignment accuracy between rollers.SOLUTION: An image forming apparatus comprises a first roller, a second roller arranged downstream of the first roller, a third roller arranged downstream of the second roller, a first support member that rotatably supports the first roller, a second support member that rotatably supports the third roller, and a bearing member that rotatably supports an end portion of a rotation shaft in a rotational axis direction of the second roller. The bearing member includes a first positioning portion that positions an end portion of the first support member in the rotational axis direction with respect to a direction orthogonal to the rotational axis direction and a second positioning portion that positions an end portion of the second support member in the rotational axis direction with respect to the direction orthogonal to the rotational axis direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms an image on a sheet. [Background technology]

[0002] Image forming apparatuses such as printers and multifunction peripherals form images on sheets used as recording materials by transferring the sheets between a plurality of transfer rollers in sequence. Patent Document 1 describes an image forming apparatus that forms images on sheets by transferring sheets set in a feed tray in sequence through a pickup roller, a feed roller, a registration roller, a transfer roller, and a discharge roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-095802 Summary of the Invention [Problem to be solved by the invention]

[0004] In an image forming apparatus, if the relative alignment accuracy between a plurality of rollers is low, there is a possibility that a sheet may be tilted during conveyance.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that can improve the relative alignment accuracy between rollers. [Means for solving the problem]

[0006] One aspect of the present invention is a sheet conveying device including a first roller for conveying a sheet, a rotation shaft, and a roller body supported by the rotation shaft, the second roller being disposed downstream of the first roller in the sheet conveying direction and conveying the sheet, a third roller being disposed downstream of the second roller in the sheet conveying direction and conveying the sheet, a first support member rotatably supporting the first roller, a second support member rotatably supporting the third roller, and a bearing member rotatably supporting an end of the rotation shaft in the rotation axis direction of the second roller. a frame supporting the bearing member; The bearing member has a first positioning portion that positions an end of the first support member in the rotational axis direction in a direction perpendicular to the rotational axis direction, and a second positioning portion that positions an end of the second support member in the rotational axis direction in a direction perpendicular to the rotational axis direction. At least a portion of the second roller is disposed on one side of the frame in the direction of the rotation axis, and the bearing member is disposed on the other side of the frame in the direction of the rotation axis. The image forming apparatus is characterized by the above. [Effects of the Invention]

[0007] According to the present invention, the relative alignment accuracy between rollers can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view showing a part of an image forming apparatus according to an embodiment. [Figure 3] 5A and 5B are schematic diagrams illustrating a support configuration for a roller and a guide member according to the embodiment. [Figure 4] FIG. 2 is a perspective view showing a support structure for a conveying roller according to the embodiment. [Figure 5] 3A and 3B are perspective views of a first transport guide and a feed roller according to the embodiment. [Figure 6] FIG. 4 is a perspective view showing a support configuration for a first transport guide according to the embodiment. [Figure 7] FIG. 3 is a cross-sectional view showing a part of a first transport guide and a frame according to the embodiment. [Figure 8] 3A and 3B are perspective views of a second transport guide according to the embodiment. [Figure 9] FIG. 4 is a perspective view showing a support configuration for a second transport guide according to the embodiment. [Figure 10] 1A is a perspective view of a third transport guide according to the embodiment, and FIG. 1B is a perspective view showing a support structure thereof. [Figure 11] 3A is a cross-sectional view of the image forming apparatus according to the embodiment, showing a state in which the rear cover is closed, and FIG. 3B is a cross-sectional view of the image forming apparatus according to the embodiment, showing a state in which the rear cover is open. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 is a monochrome printer that forms a monochromatic image on a sheet S as a recording material using an image forming unit while conveying the sheet S. Note that the sheet S can be made of a variety of sheet materials of different sizes and materials, including paper such as plain paper and cardboard, surface-treated sheet materials such as plastic film, cloth, and coated paper, and sheet materials with special shapes such as envelopes and index paper.

[0011] The image forming apparatus 1 includes an electrophotographic image forming section 1B including a process unit 110, a laser scanner unit 500, a transfer roller 201, and a fixing unit 400. The process unit 110 is configured as a cartridge that is detachable from the apparatus main body 1A (housing) of the image forming apparatus 1, and includes a photosensitive drum 111 as an image carrier and one or more process members that act on the photosensitive drum 111.

[0012] The image forming apparatus 1 also includes a mechanism for transporting the sheet S, which includes a pickup roller 311, a feed roller 312, a separation roller 313, a transport roller 321, transport rollers 322 and 323, a discharge roller 403, and a discharge roller 404. A sheet storage section 300 (sheet tray) for stacking and storing the sheets S is provided at the bottom of the apparatus main body 1A. A discharge tray 405 for stacking the sheets S on which images have been formed is provided at the top surface of the apparatus main body 1A.

[0013] When an image formation execution instruction (print job) is input to the image forming apparatus 1, formation of a toner image is initiated in the image forming unit 1B. That is, in the process unit 110, the photosensitive drum 111 rotates, and the charger uniformly charges the surface of the photosensitive drum 111. The laser scanner unit 500 irradiates the photosensitive drum 111 with laser light based on the image information included in the print job. This exposes the charged surface of the photosensitive drum 111, and an electrostatic latent image corresponding to the image information is written onto the surface. The developing device of the process unit 110 supplies a developer containing toner to the photosensitive drum 111, and visualizes (develops) the electrostatic latent image into a toner image. This toner image is transported to a transfer nip Nt, which is a nip portion between the photosensitive drum 111 and the transfer roller 201, by the rotation of the photosensitive drum 111.

[0014] In parallel with the above-described toner image forming process, sheets S are supplied one by one from sheet storage unit 300 to image forming unit 1B. That is, pickup roller 311 rotates while contacting the uppermost sheet of sheets S stacked in sheet storage unit 300, and sends out sheet S from sheet storage unit 300. Sheets S sent out from sheet storage unit 300 are further conveyed in a state where they are separated one by one at a nip portion (separation nip Ns) between feed roller 312 and separation roller 313. Sheets S that have passed through separation nip Ns are nipped in conveyance nip Nc between conveyance roller 321 and conveyance roller 322, and are further conveyed toward transfer nip Nt.

[0015] The separation roller 313 is an example of a separation member that separates the sheet S by frictional force, and may be, for example, a rubber roller supported via a torque limiter on a shaft fixed to the frame of the apparatus main body 1A. Alternatively, a retard roller to which a driving force in a direction opposite to the direction of movement of the circumferential surface of the feed roller 312 in the separation nip Ns is input via a torque limiter, or a pad-like elastic member that abuts against the feed roller 312 may be used as the separation member.

[0016] In the transfer nip Nt, a predetermined bias voltage (transfer voltage) is applied to the transfer roller 201, thereby transferring a toner image from the photosensitive drum 111 to the sheet S. The sheet S with the transferred toner image undergoes a fixing process in the fixing device 400. The fixing device 400 uses a thermal fixing configuration including a first rotating body and a second rotating body that sandwich and transport the sheet S in the fixing nip Nf, and a heating means that heats the image on the sheet S. The first rotating body is, for example, a flexible cylindrical film or roller. The second rotating body is, for example, a roller with an elastic layer on its outer periphery. The heating means can be a heater substrate in which a pattern of heating resistors is formed on a ceramic substrate, or a halogen lamp that emits radiant heat.

[0017] The sheet S that has passed through the fixing nip Nf is discharged to the outside of the apparatus main body 1A by a pair of discharge rollers consisting of a discharge roller 403 and a discharge roller 404, and is stacked on a discharge tray 405. The path from the sheet storage section 300 to the discharge tray 405 via the multiple rollers is the first conveying path P1 (main conveying path) of the image forming apparatus 1.

[0018] When forming images on both sides of the sheet S, the sheet S, on whose first side an image has been formed by the image forming operation described above, is sent to a second conveying path P2 (double-sided conveying path, re-conveying path) by reverse conveyance by a pair of discharge rollers. The second conveying path P2 branches off from the first conveying path P1 downstream of the fixing nip Nf in the sheet conveying direction of the first conveying path P1 and merges with the first conveying path P1 upstream of the separation nip Ns between the conveying roller 321 and the conveying roller 322. The sheet S sent to the second conveying path P2 is nipped and conveyed between the conveying roller 321 and the conveying roller 323, and then conveyed back to the first conveying path P1. Then, while the sheet S passes through the transfer nip Nt and the fixing nip Nf, an image is formed on the second side, which is opposite to the first side, and the sheet S is then discharged by a pair of discharge rollers.

[0019] (rollers and guide members) The rollers and guide members provided in the image forming apparatus 1 will be described with reference to FIGS.

[0020] In the following description, the rotation axis direction of the photosensitive drum 111 is referred to as the X-axis direction. The vertical direction (opposite to the direction of gravity) when the image forming apparatus 1 is placed on a horizontal surface is referred to as the Z-axis direction. The direction perpendicular to the X-axis direction and the Z-axis direction is referred to as the Y-axis direction. The X-axis direction is preferably perpendicular to the Z-axis direction. The X-axis direction is also the sheet width direction (direction perpendicular to the sheet conveying direction) of the sheet conveyed by the first conveying path P1 and the second conveying path P2.

[0021] 2 is a cross-sectional view of a part of the image forming apparatus 1 taken along a plane perpendicular to the X-axis direction. 2 shows the arrangement of rollers and guide members arranged in the portion of the first conveying path P1 from the sheet storage unit 300 to the transfer roller 201.

[0022] 2, a pickup roller 311, a feed roller 312 and a separation roller 313, a conveying roller 321 and a conveying roller 322, a photosensitive drum 111, and a transfer roller 201 are arranged along the first conveying path P1. With respect to the sheet conveying direction in the first conveying path P1, a separation nip Ns formed by the feed roller 312 and the separation roller 313 is located downstream of the pickup roller 311. A conveying nip Nc formed by the conveying roller 321 and the conveying roller 322 is located downstream of the separation nip Ns. A transfer nip Nt formed by the photosensitive drum 111 and the transfer roller 201 is located downstream of the conveying nip Nc.

[0023] Feed roller 312 is an example of a first roller that conveys a sheet. Conveyance roller 321 has a rotation shaft and a roller body supported by the rotation shaft, is disposed downstream of the first roller in the sheet conveyance direction, and is an example of a second roller that conveys the sheet. Transfer roller 201 is an example of a third roller that is disposed downstream of the second roller in the sheet conveyance direction and conveys the sheet. Conveyance roller 322 is an example of a fourth roller that contacts the second roller and sandwiches and conveys the sheet together with the second roller. Note that the first to fourth rollers are not limited to the examples given here, and may be roller members that convey sheets at other positions in the image forming apparatus.

[0024] The pickup roller 311, the feed roller 312, and the photosensitive drum 111 come into contact with a first side of the sheet S fed from the sheet storage unit 300. The separation roller 313, the conveying roller 321, and the transfer roller 201 come into contact with a second side of the sheet S fed from the sheet storage unit 300.

[0025] The pickup roller 311, feed roller 312, and photosensitive drum 111 are each driven to rotate in a clockwise direction in the drawing by a driving force transmitted from a motor serving as a drive source. The transport roller 321 is driven to rotate in a counterclockwise direction in the drawing by a driving force transmitted from the motor. The transfer roller 201 and transport roller 322 can be configured to rotate following the force received from the opposing roller, but may also be driven to rotate by a driving force transmitted from a drive source.

[0026] 2, a first conveying guide 331, a second conveying guide 332, and a third conveying guide 333 are arranged along the first conveying path P1. The first conveying guide 331 guides the sheet S between the separation nip Ns and the conveying nip Nc and in the vicinity of the conveying roller 322. The second conveying guide 332 guides the sheet S in a part of the second conveying path P2 and in the vicinity of the conveying roller 321. The third conveying guide 333 is arranged downstream of the second conveying guide 332 in the sheet conveying direction on the first conveying path P1, and guides the sheet S between the conveying nip Nc and the transfer nip Nt and in the vicinity of the transfer roller 201.

[0027] A part of the first conveying guide 331 and a part of the second conveying guide 332 face each other near the conveying nip Nc, sandwiching the first conveying path P1. The first conveying guide 331 and the second conveying guide 332 can guide the sheet S fed from the sheet storage unit 300 to the conveying nip Nc. The third conveying guide 333 can guide the sheet that has passed through the conveying nip Nc to the transfer nip Nt. The first conveying guide 331 guides the first side of the sheet S fed from the sheet storage unit 300. The second conveying guide 332 and the third conveying guide 333 guide the second side of the sheet S fed from the sheet storage unit 300.

[0028] The first transport guide 331 is an example of a first support member that rotatably supports the first roller, and the third transport guide 333 is an example of a second support member that rotatably supports the third roller.

[0029] (Summary of support structure) 3 is a schematic diagram (exploded view) showing the support structure of the first conveying guide 331, the second conveying guide 332, and the third conveying guide 333. In this embodiment, a bearing member 334 that rotatably supports the conveying roller 321 supports the first conveying guide 331, the second conveying guide 332, and the third conveying guide 333. The first conveying guide 331 supports the feed roller 312 and the conveying roller 322. The third conveying guide 33 3 supports the transfer roller 201. As will be described below, the first conveying guide 33 1 The third conveying guide 333 is positioned by the bearing member 334, and thus the positions of the feed roller 312 and the transfer roller 201 relative to the conveying roller 321 are determined.

[0030] In this embodiment, the support configuration of each transport guide and transport roller 321 is substantially the same on both sides in the X-axis direction (the direction of the rotation axis of the transport roller 321). In the following explanation, the support configuration on one side in the X-axis direction will be described, but a corresponding support configuration is also provided on the opposite side in the X-axis direction. For example, in addition to the bearing member 334 and frame 335 shown in FIG. 3, a bearing member and a frame having the same configuration as the bearing member 334 and frame 335 but with a symmetrical shape are arranged on each side in the X-axis direction.

[0031] (Support structure of conveying roller) The support structure of the transport roller 321 will be described with reference to Fig. 4. Fig. 4 is a perspective view showing the support structure of the transport roller 321.

[0032] 4, the bearing member 334 has a first boss 334b, a second boss 334a, a hole 334c, and a connecting portion 334d. The first boss 334b ​​is the first positioning portion of this embodiment, and the second boss 334a is the second positioning portion and the third positioning portion of this embodiment.

[0033] The first boss 334b ​​and the second boss 334a are each protrusions extending in the X-axis direction and have an arcuate surface (cylindrical surface) extending in the X-axis direction. That is, the hole 334c is formed inside the second boss 334a and extends in the X-axis direction. The second boss 334a and the first boss 334b ​​are spaced apart in a direction intersecting the X-axis direction and are integrally formed via a connecting portion 334d. The second boss 334a and the hole 334c are arranged coaxially (on the rotation axis of the conveying roller 321). The bearing member 334 is supported by a frame 335.

[0034] The frame 335 has a hole 335a, a rectangular hole 335b, a first groove 335c, a first rib 335d, a second groove 335e, a second rib 335f, and a third rib 335g. The hole 335a and the rectangular hole 335b are each through-holes that penetrate the frame 335 from the outside to the inside in the X-axis direction. The first groove 335c and the second groove 335e are groove-shaped and provided on the inner side surface of the frame 335 in the X-axis direction. The first rib 335d and the second rib 335f are plate-shaped and extend in a direction intersecting the X-axis direction (preferably in the Y-axis direction and the Z-axis direction). The frame 335 is fixed to the frame of the device main body 1A.

[0035] The frame 335 is an example of a restricting member that restricts the rotation or position of the first support member and the second support member. The first groove 335c is an example of a first rotation restricting portion that restricts the rotation of the first support member. The second groove 335e is an example of a second rotation restricting portion that restricts the rotation of the second support member. The first rib 335d is an example of a first position restricting portion that restricts the position of the first support member in the X-axis direction (the direction of the rotation axis of the second roller). The third rib 335g is an example of a second position restricting portion that restricts the position of the second support member in the X-axis direction.

[0036] The second boss 334a of the bearing member 334 engages (fits) with the hole 335a of the frame 335, and the first boss 334b ​​of the bearing member 334 engages (fits) with the square hole 335b of the frame 335, thereby restricting the position and orientation of the bearing member 334. The hole 335a of the frame 335 is an example of a first engaging portion that engages with the second boss 334a of the bearing member 334, thereby positioning the bearing member 334 in a direction perpendicular to the X-axis direction. The square hole 335b of the frame 335 is an example of a second engaging portion that engages with the first boss 334b ​​of the bearing member 334, thereby restricting rotation of the bearing member 334 when viewed in the X-axis direction.

[0037] In the X-axis direction, first conveying guide 331, second conveying guide 332, third conveying guide 333, feed roller 312, conveying roller 321, and transfer roller 201 are arranged so that at least a portion thereof is located on one side of frame 335. Bearing member 334 is attached to frame 335 from the other side of frame 335, and is arranged so that at least a portion thereof is located on the other side of frame 335. Second boss 334a and first boss 334b ​​of bearing member 334 penetrate frame 335 from the other side to one side of frame 335 via hole 335a and square hole 335b in frame 335.

[0038] In other words, the bearing member 334 is positioned in at least one direction perpendicular to the X-axis direction by the engagement between the second boss 334a and the hole 335a, with the second boss 334a serving as the positioning center (reference). The second boss 334a and the hole 335a are configured to restrict movement of the bearing member 334 relative to the frame 335 in at least one of the Y-axis direction and the Z-axis direction, and preferably in any direction perpendicular to the X-axis direction. The inner diameter of the hole 335a is set to be equal to the outer diameter of the second boss 334a or slightly larger than the outer diameter of the second boss 334a, taking tolerances into consideration.

[0039] Furthermore, the engagement between first boss 334b ​​and square hole 335b restricts rotation (attitude change) of bearing member 334 about second boss 334a. In other words, even if bearing member 334 attempts to rotate about second boss 334a, first boss 334b ​​interferes with the upper or lower surface of square hole 335b, preventing bearing member 334 from rotating. The width of square hole 335b in the Y-axis direction can be set slightly larger than the outer diameter of first boss 334b ​​to allow for the tolerance of frame 335.

[0040] Instead of the hole-shaped engaging portion, a protrusion that fits into a hole-shaped (recessed) portion provided in the bearing member 334 may be provided on the frame 335 and used as the first engaging portion or the second engaging portion.

[0041] The conveying roller 321 has a rotary shaft 321a extending in the X-axis direction, which is the direction of the rotation axis, and a plurality of rubber rollers 321b supported by the rotary shaft 321a. The rubber rollers 321b are roller bodies that come into contact with the sheet S.

[0042] The conveying roller 321 is rotatably supported by the bearing member 334 by engaging (fitting) an end of the rotating shaft 321a in the X-axis direction with a hole 334c of the bearing member 334. A gear (not shown) is provided at one end of the rotating shaft 321a, and is configured to receive a driving force for rotating the conveying roller 321 from a motor provided in the apparatus main body 1A.

[0043] (Supporting structure of first conveying guide and feed roller) The support structure of the first transport guide 331 and the feed roller 312 will be described using Figures 5(a) and 5(b) to 7. Figures 5(a) and 5(b) are perspective views of the first transport guide 331 and the feed roller 312 as viewed from different angles. Figure 6 is a perspective view showing the support structure of the first transport guide 331. Figure 7 is a cross-sectional view of the first transport guide 331 and part of the frame 335 when the first transport guide 331 is assembled to the image forming apparatus 1, cut along a plane perpendicular to the Y-axis direction.

[0044] As shown in FIGS. 5(a) and 5(b), first transport guide 331 has guide portion 331d (see also FIG. 2) that forms first transport path P1, and bearing portion 331e that rotatably supports feed roller 312. First transport guide 331 also supports arm member 310 that rotatably supports pickup roller 311. Arm member 310 is swingable (rotatable) relative to first transport guide 331 so as to raise and lower pickup roller 311. Feed roller 312 and pickup roller 311 are rotationally driven by a driving force transmitted to roller shaft 312a of feed roller 312 from a motor provided in apparatus main body 1A.

[0045] 5(b), first conveying guide 331 rotatably supports a plurality of conveying rollers 322. Each conveying roller 322 is rotatably held by a holder 337. Holder 337 is supported by first conveying guide 331 via a pressure member 338 (elastic member, spring member). Pressure member 338 biases holder 337 so as to press conveying rollers 322 against conveying rollers 321 when first conveying guide 331 is assembled to image forming apparatus 1.

[0046] As shown in FIGS. 5(a) and 5(b) and 6, a rectangular hole 331a, a protrusion 331b, and a slit 331c are provided at the end of the first conveying guide 331 in the X-axis direction. The rectangular hole 331a has a rectangular (preferably square) opening when viewed in the X-axis direction and is a hole-shaped portion formed in the X-axis direction. The protrusion 331b has a convex shape that protrudes in the X-axis direction. When viewed in the X-axis direction, the protrusion 331b in this embodiment has a rectangular shape that is elongated in the Z-axis direction (a plate-like shape with its thickness direction in the Y-axis direction). The slit 331c has a groove-like shape that is formed in a direction intersecting the X-axis direction. The slit 331c in this embodiment has a groove-like shape that opens downward in the Z-axis direction and widens in the Z-axis and Y-axis directions (see FIG. 7).

[0047] The rectangular hole 331a of the first conveying guide 331 engages (fits) with the first boss 334b ​​of the bearing member 334, and the protrusion 331b of the first conveying guide 331 engages (fits) with the first groove portion 335c of the frame 335, thereby regulating the position and posture of the first conveying guide 331.

[0048] In other words, the first transport guide 331 is positioned in at least one direction perpendicular to the X-axis direction, using the first boss 334b ​​(first positioning portion) of the bearing member 334 as the positioning center (reference). The rectangular hole 331a and the first boss 334b ​​are configured to restrict movement of the first transport guide 331 relative to the bearing member 334 in at least one of the Y-axis direction and the Z-axis direction, preferably in any direction perpendicular to the X-axis direction. Note that movement of the first transport guide 331 relative to the bearing member 334 is preferably restricted in a first direction perpendicular to the X-axis direction and a second direction perpendicular to both the X-axis direction and the first direction. In this embodiment, movement of the first transport guide 331 relative to the bearing member 334 is restricted in the Y-axis direction and the Z-axis direction. The width and height (lengths of two sides of the rectangle) of the rectangular hole 331a are set to be equal to the outer diameter of the first boss 334b ​​or slightly larger than the outer diameter of the first boss 334b, taking tolerances into consideration.

[0049] Furthermore, the first transport guide 331 is restricted from rotating (changing its posture) around the first boss 334b ​​due to the engagement between the protrusion 331b and the first groove 335c of the frame 335. In other words, even if the first transport guide 331 tries to rotate around the first boss 334b, the protrusion 331b interferes with the lower or upper surface of the first groove 335c, and the first transport guide 331 does not rotate.

[0050] The first positioning portion may be a recess into which a boss (protrusion) provided on the first transport guide 331 (first support member) fits.

[0051] The positioning configuration of the first transport guide 331 in the X-axis direction will be described using Figure 7. The slit 331c of the first transport guide 331 and the first rib 335d of the frame 335 both extend in a direction intersecting the X-axis direction. The width of the slit 331c in the X-axis direction is set to be equal to the width of the first rib 335d in the X-axis direction or slightly larger than the width of the first rib 335d in consideration of tolerance. Therefore, when the slit 331c is engaged with the first rib 335d, movement of the first transport guide 331 in the X-axis direction relative to the frame 335 is restricted. That is, the first transport guide 331 is positioned in the X-axis direction by the engagement between the slit 331c and the first rib 335d.

[0052] As a positioning configuration for the first transport guide 331 in the X-axis direction, a rib (convex portion) may be formed on the first transport guide 331 in a direction intersecting the X-axis direction, and a slit (concave portion) that engages with this rib may be formed on the frame 335.

[0053] (Support structure of second conveying guide) The support structure of the second transport guide 332 will be described with reference to Figures 8(a) and 8(b) and 9. Figure 8(a) is a perspective view of the second transport guide 332. Figure 8(b) is a perspective view showing the support structure of the second transport guide 332.

[0054] 8(a), the second transport guide 332 has a guide portion 332d (see also FIG. 2) that forms the first transport path P1 and the second transport path. The guide portion 332d is provided with an opening 332e that allows the rubber roller 321b of the transport roller 321 to protrude into the first transport path P1.

[0055] As shown in FIG. 8(b), the second transport guide 332 has a hole 332a, a protrusion 332b, and a slit 332c at its end in the X-axis direction. The hole 332a is a through-hole that penetrates the side surface of the second transport guide 332 in the X-axis direction. The protrusion 332b has a convex shape that protrudes outward in the X-axis direction from the side surface of the second transport guide 332 in the X-axis direction. The slit 332c is a groove shape formed in a direction intersecting the X-axis direction. In this embodiment, the slit 332c is a groove shape that opens downward in the Z-axis direction and widens in the Z-axis and Y-axis directions.

[0056] The hole 332a of the second conveying guide 332 engages (fits) with the second boss 334a of the bearing member 334, and the protrusion 332b of the second conveying guide 332 engages (fits) with the second groove 335e of the frame 335, thereby regulating the position and posture of the second conveying guide 332.

[0057] In other words, the second transport guide 332 is positioned with the second boss 334a of the bearing member 334 as the positioning center (reference) in at least one direction perpendicular to the X-axis direction. The hole 332a and the second boss 334a are configured to restrict movement of the second transport guide 332 relative to the bearing member 334 in at least one of the Y-axis direction and the Z-axis direction, preferably in any direction perpendicular to the X-axis direction. Note that movement of the second transport guide 332 relative to the bearing member 334 is preferably restricted in a first direction perpendicular to the X-axis direction and a second direction perpendicular to both the X-axis direction and the first direction. In this embodiment, movement of the second transport guide 332 relative to the bearing member 334 is restricted in both the Y-axis direction and the Z-axis direction. The inner diameter of the hole 332a is set to be equal to the outer diameter of the second boss 334a or slightly larger than the outer diameter of the second boss 334a in consideration of tolerances.

[0058] In addition, the second conveying guide 33 2Rotation (attitude change) around the second boss 334a is restricted by the engagement between the protrusion 332b and the second groove 335e of the frame 335. In other words, even if the second transport guide 332 tries to rotate around the second boss 334a, the protrusion 332b interferes with the side surface of the second groove 335e (either of the side surfaces on both sides in the Y-axis direction), and therefore the second transport guide 332 does not rotate.

[0059] The positioning configuration of the second transport guide 332 in the X-axis direction will be described using Figure 9. The slit 332c of the second transport guide 332 and the second rib 335f of the frame 335 both extend in a direction intersecting the X-axis direction. The width of the slit 332c in the X-axis direction is set to be equal to the width of the second rib 335f in the X-axis direction or slightly larger than the width of the second rib 335f taking tolerance into consideration. Therefore, when the slit 332c is engaged with the second rib 335f, movement of the second transport guide 332 in the X-axis direction relative to the frame 335 is restricted. That is, the second transport guide 332 is positioned in the X-axis direction by the engagement between the slit 332c and the second rib 335f.

[0060] As a positioning configuration for the second transport guide 332 in the X-axis direction, a rib (convex portion) may be formed on the second transport guide 332 in a direction intersecting the X-axis direction, and a slit (concave portion) that engages with this rib may be formed on the frame 335.

[0061] (Supporting structure of the third conveying guide and transfer roller) 10(a) and 10(b) will be used to explain the support structure of the third conveying guide 333 and the transfer roller 201. Fig. 10(a) is a perspective view of the third conveying guide 333. Fig. 10(b) is a perspective view showing the support structure of the third conveying guide 333.

[0062] As shown in FIG. 10(a), the third transport guide 333 has a guide portion 333d (see also FIG. 2) that forms the first transport path P1. The third transport guide 333 also rotatably supports the transfer roller 201. Both ends of the shaft of the transfer roller 201 are rotatably held by holders 201h. The holders 201h are supported by the third transport guide 333 via pressure members 201p (elastic members, spring members; see FIG. 2). Pressure members 201p The third conveying guide 333 is attached to the image forming apparatus 1 so that the transfer roller 201 is pressed against the photosensitive drum 111. 201h is activated.

[0063] As shown in Figures 10(a) and 10(b), a hole 333a and a slit 333b are provided at the end of the third transport guide 333 in the X-axis direction. The hole 333a is a through-hole that penetrates the side surface of the third transport guide 333 in the X-axis direction. The slit 333b is a groove-shaped groove formed in a direction intersecting the X-axis direction. The slit 333 in this embodiment b is a groove shape that opens downward in the Z-axis direction and widens in the Z-axis and Y-axis directions.

[0064] The hole 333a of the third transport guide 333 engages (fits) with the second boss 334a of the bearing member 334, thereby restricting the position of the third transport guide 333.

[0065] In other words, the third transport guide 333 is positioned with respect to at least one direction perpendicular to the X-axis direction, using the second boss 334a (second positioning portion) of the bearing member 334 as the positioning center (reference). The hole 333a and the second boss 334a are configured to restrict movement of the third transport guide 333 relative to the bearing member 334 in at least one of the Y-axis direction and the Z-axis direction, preferably in any direction perpendicular to the X-axis direction. Note that movement of the third transport guide 333 relative to the bearing member 334 is preferably restricted in a first direction perpendicular to the X-axis direction and a second direction perpendicular to both the X-axis direction and the first direction. In this embodiment, movement of the third transport guide 333 relative to the bearing member 334 is restricted in the Y-axis direction and the Z-axis direction. The inner diameter of the hole 333a is set to be equal to the outer diameter of the second boss 334a or slightly larger than the outer diameter of the second boss 334a in consideration of tolerances.

[0066] The second positioning portion may be a recess into which a boss (protrusion) provided on the third transport guide 333 (second support member) fits.

[0067] Here, the hole 332a of the second transport guide 332 and the hole 333a of the third transport guide 333 are engaged with the second boss 334a of the bearing member 334 at mutually different positions in the X-axis direction. That is, in this embodiment, a part of the second boss 334a is a second positioning portion that positions the second support member (third transport guide), and another part of the second boss 334a is a third positioning portion that positions the guide member (second transport guide 332). Therefore, the length L1 ( FIG. 9 ) by which the second boss 334a of the bearing member 334 protrudes in the X-axis direction from the hole 335a of the frame 335 is at least greater than the sum of the lengths in the X-axis direction of the holes 332a and 333a of the second transport guide 332 and the third transport guide 333.

[0068] The positioning configuration of the third transport guide 333 in the X-axis direction will be described using FIG. 10(b). The slit 333b of the third transport guide 333 and the third rib 335g of the frame 335 both extend in a direction intersecting the X-axis direction. The width of the slit 333b in the X-axis direction is set to be equal to the width of the third rib 335g in the X-axis direction or slightly larger than the width of the third rib 335g taking tolerance into account. Therefore, when the slit 333b is engaged with the third rib 335g, movement of the third transport guide 333 in the X-axis direction relative to the frame 335 is restricted. That is, the third transport guide 333 is positioned in the X-axis direction by the engagement between the slit 333b and the third rib 335g.

[0069] Incidentally, although the third transport guide 333 of this embodiment is positioned in the X, Y, and Z axis directions as described above, rotation (attitude change) of the bearing member 334 about the second boss 334a is not restricted by the bearing member 334 or the frame 335. In other words, the third transport guide 333 is supported by the bearing member 334 so as to be rotatable about the second boss 334a. Making the third transport guide 333 rotatable facilitates attachment and detachment of the process unit 110 (or other detachable unit), as will be described below.

[0070] The transfer roller 201 and the guide portion 333d that guides the sheet around it are located downstream in the sheet conveying direction (above in the Z-axis direction) of the conveying roller 321. Therefore, the hole 333a and the slit 333b of the third conveying guide 333 are provided at the tip of an arm portion that protrudes upstream (downward) from the upstream end (lower end) of the guide portion 333d in the sheet conveying direction.

[0071] (Opening and closing of the third transport guide) 11(a) and 11(b), this embodiment employs a configuration in which the process unit 110 is detachable from the rear side (one side in the Y-axis direction) of the apparatus main body 1A. Fig. 11(a) shows a state in which the rear cover 340 is closed, and Fig. 11(b) shows a state in which the rear cover 340 is open.

[0072] As shown in FIGS. 1 and 11(a) and 11(b), the image forming apparatus 1 has a rear cover 340 as an opening / closing member. The apparatus main body 1A is provided with an opening OP that opens in the Y-axis direction. The rear cover 340 is rotatably supported by the apparatus main body 1A. The rear cover 340 is movable (openable and closable) between a closed position (FIG. 11(a)) that covers the opening OP of the apparatus main body 1A as viewed in the Y-axis direction, and an open position (FIG. 11(b)) that exposes the opening OP of the apparatus main body 1A as viewed in the Y-axis direction. When positioned in the closed position, the rear cover 340 forms the side surface of the apparatus main body 1A in the Y-axis direction.

[0073] As shown in FIG. 11(a), the rear cover 340 and the third conveying guide 333 have guide portions 340a and 333e that face each other when the rear cover 340 is in the closed position. When the rear cover 340 is in the closed position, a second conveying path P2 is formed between the guide portions 340a and 333e. As shown in FIG. 11(b), when the rear cover 340 moves to the open position, the guide portion 340a of the rear cover 340 moves away from the guide portion 333e of the third conveying guide 333. This opens the second conveying path P2, allowing the user to easily remove a sheet that has become jammed in the second conveying path P2.

[0074] After opening the rear cover 340, the user can rotate (open) the third transport guide 333 by grasping the third transport guide 333 and pulling it in the direction of the arrow in Figure 11(a). At this time, the third transport guide 333 rotates around the second boss 334a (Figure 10) that is coaxial with the rotation shaft 321a of the transport roller 321. In other words, the third transport guide 333 and the transport roller 321 are configured to rotate around a single rotation axis.

[0075] By opening the third conveying guide 333, a portion of the first conveying path P1 is opened, making it possible to easily remove a sheet jammed in the first conveying path P1. Furthermore, when the third conveying guide 333 is opened, the process unit 110 is exposed when viewed from the outside of the image forming apparatus 1 in the Y-axis direction (FIG. 11(b)). This allows the user to grasp the process unit 110 and remove or install it through the opening OP of the apparatus main body 1A.

[0076] As described above, the third conveying guide 333 is supported rotatably around the second boss 334a of the bearing member 334, i.e., around the rotation axis 321a of the conveying roller 321. This configuration makes it possible to reduce the size of the image forming apparatus.

[0077] If the rotation center of the third conveying guide 333 is located above the rotation axis 321a of the conveying roller 321, the rotation center may interfere with the attachment / detachment trajectory (the area indicated by the dotted line in FIG. 11(b)) of the process unit 110 as viewed in the X-axis direction. If the support portion that rotatably supports the third conveying guide 333 is located outside the attachment / detachment trajectory of the process unit 110 in the X-axis direction to avoid interference, the size of the image forming apparatus in the X-axis direction will increase.

[0078] Furthermore, if the rotation center of the third conveying guide 333 is located below the rotation shaft 321a of the conveying roller 321, the rotation locus of the third conveying guide 333 may interfere with the rotation shaft 321a of the conveying roller 321. If a support portion that rotatably supports the third conveying guide 333 is located outside the conveying roller 321 in the X axis direction to avoid the interference, the size of the image forming apparatus in the X axis direction will increase. If a support portion that rotatably supports the third conveying guide 333 is located below and behind the conveying roller 321 (on the left side in FIG. 11A) to avoid the interference, the size of the image forming apparatus in the Y axis direction will increase.

[0079] In contrast to this, in this embodiment, in a configuration in which the third conveying guide 333 can be opened, the rotation center of the third conveying guide 333 is coaxial with the rotation axis 321a of the conveying roller 321. This makes it possible to reduce the size of the image forming apparatus while improving the operability of jam clearance and attachment / detachment of the process unit.

[0080] (Advantages of this embodiment) According to this embodiment, the first support member supporting the first roller and the second support member supporting the third roller are positioned by the bearing member supporting the second roller. That is, the end of first conveyance guide 331 (first support member) supporting feed roller 312 (first roller) is positioned in a direction perpendicular to the X-axis direction (the direction of the rotation axis of the second roller) by first boss 334b ​​(first positioning portion) of bearing member 334. Also, the end of third conveyance guide 333 (second support member) supporting transfer roller 201 (third roller) is positioned in a direction perpendicular to the X-axis direction by second boss 334a (second positioning portion) of bearing member 334.

[0081] This makes it easier to ensure the accuracy of the relative position between the rotation axis of the second roller and the rotation axis of the first roller, compared to, for example, when the first support member and the second support member are positioned by a member separate from the bearing member of the second roller. Also, compared to when the first support member and the second support member are positioned by a member separate from the bearing member 334, it makes it easier to ensure the accuracy of the relative position between the rotation axis of the second roller and the rotation axis of the third roller. Therefore, the configuration of this embodiment can improve the accuracy of the relative alignment between the rollers. By improving the accuracy of the relative alignment between the rollers, tilting and rotation of the sheet during transport is suppressed, thereby reducing misalignment and deformation of the image formed on the sheet.

[0082] Furthermore, the bearing member 334 rotatably supports the rotation shaft 321a of the conveying roller 321 (second roller) in a hole 334c of the second boss 334a. Furthermore, the bearing member 334 positions the second support member (third conveying guide 333) that supports the third roller (transfer roller 201) by means of the second boss 334a (second positioning portion) that is coaxial with the hole 334c and is provided on the outer periphery of the hole 334c. This further improves the relative positional accuracy of the second roller and the third roller.

[0083] The first support member (first conveying guide 331) that supports the first roller (feed roller 312) may also be positioned by the second boss 334a (second positioning portion) of the bearing member 334. That is, it is preferable that the bearing member has a hole that rotatably supports the rotation shaft of the second roller, and that at least one of the first positioning portion and the second positioning portion is provided coaxially with the hole and on the outer periphery of the hole. This can improve the accuracy of the relative position between the second roller and at least one of the first roller and third roller.

[0084] In this embodiment, the first conveying guide 331 as the first support member and the third conveying guide 333 as the second support member are guide members having guide portions 331d and 333d for guiding sheets, respectively. Since the first support member and the second support member, which are two guide members, are positioned by the same bearing member, the relative positional accuracy of the guide members can be improved, and stable sheet conveyance can be achieved.

[0085] Furthermore, in this embodiment, the first conveying guide 331 (first support member) and the second conveying guide 332 (guide member) facing the guide portion 331d of the first conveying guide 331 are positioned by the bearing member 334. In addition, the second conveying guide 332 (guide member) and the third conveying guide 333 (second support member) located on the same side of the conveying path as the second conveying guide 332 and downstream of the second conveying guide 332 in the sheet conveying direction are positioned by the bearing member 334. This improves the accuracy of the width of the gap between the first conveying guide 331 and the second conveying guide 332 (the width of the conveying path in the sheet thickness direction), and reduces the step between the second conveying guide 332 and the third conveying guide 333. This allows for more stable sheet conveyance.

[0086] Furthermore, frame 335 as a regulating member has first rib 335d (first position regulating portion) that regulates the position of first transport guide 331 in the X axis direction, and third rib 335g (second position regulating portion) that regulates the position of third transport guide 333 in the X axis direction. In other words, the positions of first transport guide 331 as the first support member and third transport guide 333 as the second support member in the X axis direction (the rotational axis direction of the second roller) are regulated by the same member, frame 335. This makes it possible to position the first support member and second support member with respect to the rotational axis direction of the second roller with a simple configuration.

[0087] Furthermore, frame 335 as a restricting member has first groove 335c that restricts rotation of first transport guide 331 around first boss 334b ​​(first positioning portion). Frame 335 further has second groove 335e that restricts rotation of third transport guide 333 around second boss 334a (second positioning portion). In other words, the rotation of first transport guide 331 as a first support member and third transport guide 333 as a second support member are restricted by the same member, frame 335. This makes it possible to stabilize the angles of the first support member and second support member with a simple configuration.

[0088] (Variation) In the present embodiment, the first support member that supports the first roller and the second support member that supports the third roller are both guide members that guide the sheet. However, the present invention is not limited to this, and the first support member and the second support member may have a configuration that does not have a function of guiding the sheet.

[0089] (Other embodiments) In the present embodiment, a configuration has been described in which the process unit 110 is detachable from the rear side of the apparatus main body 1A as an example of a detachable unit. However, the present technology is not limited to this. For example, the present technology may be applied to a configuration in which an intermediate transfer belt unit is detachable from the rear side of the apparatus main body 1A in an image forming apparatus using an intermediate transfer belt.

[0090] In addition, in this embodiment, an image forming apparatus equipped with an electrophotographic image forming unit 1B is exemplified, but the present technology may also be applied to an image forming apparatus equipped with an inkjet image forming unit or an offset printing mechanism as the image forming unit.

[0091] Furthermore, the present technology is not limited to being applied to an image forming apparatus main body that houses an image forming unit, but may also be applied to devices used together with the image forming apparatus main body in an image forming apparatus. Examples of such devices include an image reading device that reads image information from original sheets and transmits it to the image forming apparatus main body, and a sheet processing device (finisher) that performs processing such as binding on sheets on which images have been formed by the image forming apparatus main body. [Explanation of symbols]

[0092] 110... unit (process unit) / 111... image carrier (photosensitive drum) / 201... third roller (transfer roller) / 300... sheet storage section / 312... first roller (feed roller) / 331... first support member (first transport guide) / 331d... guide section / 321... second roller (transport roller) / 321a... rotation shaft / 321b... roller body (rubber roller) / 322... fourth roller (transport roller) / 332... guide member (second transport guide) / 333... second support member (third transport guide) / 33 3d...guide portion / 334...bearing member / 334a...second positioning portion, third positioning portion (second boss) / 334b...first positioning portion (first boss) / 334c...hole portion / 335...regulating member (frame) / 335a...first engagement portion (hole portion) / 335b...second engagement portion (square hole) / 335c...first rotation regulating portion (first groove portion) / 335d...first position regulating portion (first rib) / 335e...second rotation regulating portion (second groove portion) / 335g...second position regulating portion (third rib) / 340...opening / closing member (rear cover) / P1...transport path

Claims

1. a first roller for conveying a sheet; a second roller having a rotation shaft and a roller body supported by the rotation shaft, the second roller being disposed downstream of the first roller in a sheet conveying direction and configured to convey the sheet; a third roller disposed downstream of the second roller in the sheet conveying direction and configured to convey the sheet; a first support member that rotatably supports the first roller; a second support member that rotatably supports the third roller; a bearing member that rotatably supports an end of the rotation shaft in the rotation axis direction of the second roller; a frame supporting the bearing member; Equipped with the bearing member has a first positioning portion that positions an end of the first support member in the rotational axis direction with respect to a direction perpendicular to the rotational axis direction, and a second positioning portion that positions an end of the second support member in the rotational axis direction with respect to the direction perpendicular to the rotational axis direction, At least a portion of the second roller is disposed on one side of the frame in the direction of the rotation axis, and the bearing member is disposed on the other side of the frame in the direction of the rotation axis. An image forming apparatus characterized by:

2. The second positioning portion has a hole portion, the rotation shaft of the second roller is rotatably supported by the hole of the second positioning portion; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The second positioning portion and the hole portion are arranged coaxially.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the first support member has a first guide portion that guides the sheet, The second support member has a second guide portion that guides the sheet.

4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. Further provided is a guide member for guiding the sheet, The bearing member further includes a third positioning portion that positions an end portion of the guide member in the rotation axis direction in a direction perpendicular to the rotation axis direction.

5. The image forming apparatus according to claim 4.

6. The first guide portion and the guide member are opposed to each other across the sheet conveying path, the second guide portion is disposed on the same side as the guide member with respect to the sheet conveyance path and downstream of the guide member in the sheet conveyance direction.

6. The image forming apparatus according to claim 5,

7. the second support member is rotatable about the rotation axis of the second roller between a position where the second support member forms a conveyance path for the sheet and a position where the second support member opens the conveyance path for the sheet.

7. The image forming apparatus according to claim 4, wherein the image forming apparatus is a recording medium.

8. a device body having an opening; an opening / closing member movable relative to the device body between a closed position that covers the opening and an open position that exposes the opening; a unit detachable from the device body; Further provided with the second support member is rotatable to a position where the unit can be attached or detached through the opening when the opening / closing member is open.

8. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. The unit has an image carrier and at least one process member acting on the image carrier.

9. The image forming apparatus according to claim 8,

10. a first rotation restricting portion that restricts rotation of the first support member around the first positioning portion; a second rotation restricting portion that restricts rotation of the second support member around the second positioning portion; Further comprising:

9. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

11. The first rotation regulating unit and the second rotation regulating unit are provided on the frame.

11. The image forming apparatus according to claim 10.

12. The frame has a first engagement portion arranged coaxially with the second roller, and a second engagement portion arranged at a position different from the first engagement portion when viewed in the direction of the rotation axis, When the first engaging portion engages with the bearing member, the bearing member is positioned in a direction perpendicular to the rotation axis direction, When the second engaging portion is engaged with the bearing member, rotation of the bearing member is restricted when viewed in the direction of the rotation axis.

12. The image forming apparatus according to claim 11.

13. a first position restricting portion that restricts the position of the first support member in the rotational axis direction; a second position restricting portion that restricts the position of the second support member in the rotational axis direction; Further comprising:

10. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

14. The first position regulating portion and the second position regulating portion are provided on the frame.

14. The image forming apparatus according to claim 13.

15. The frame has a first engagement portion arranged coaxially with the second roller, and a second engagement portion arranged at a position different from the first engagement portion when viewed in the direction of the rotation axis, When the first engaging portion engages with the bearing member, the bearing member is positioned in a direction perpendicular to the rotation axis direction, When the second engaging portion is engaged with the bearing member, rotation of the bearing member is restricted when viewed in the direction of the rotation axis.

15. The image forming apparatus according to claim 14.

16. an image carrier; a sheet storage section for storing sheets; Further provided with the first roller is a feed roller that feeds the sheet from the sheet storage unit, the third roller is a transfer roller that transfers a toner image from the image carrier to the sheet, the second roller is a conveying roller that conveys the sheet conveyed from the feed roller toward a nip portion between the image carrier and the transfer roller; 9. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

17. The sheet conveying device further includes a fourth roller that contacts the second roller and clamps and conveys the sheet together with the second roller, the first support member rotatably supports the fourth roller; 13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

18. The first positioning portion and the second positioning portion are engaged with the frame.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images