Image forming apparatus

Abstract

To provide an image forming apparatus that can efficiently transport a sheet by suppressing the restriction of the movable range of a guide member.SOLUTION: In an image forming apparatus 1, a movable chute 71 has a sheet transport surface 71A configured to move between a first position and a second position where its downstream end 71a in the first direction is farther from a transport path P1 than in the first position, positioned on the opposite side of a re-transport chute 23 across a re-transport path P2 in the vertical direction, which is the sheet thickness direction, of a sheet S transported along the transport path P1, for guiding the sheet S transported along the transport path P1 toward a fuser 6, and a first re-transport surface 71B facing away from the sheet transport surface 71A in the vertical direction, forming the re-transport path P2.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] As disclosed in Patent Document 1, conventionally, an image forming apparatus is known that includes a transfer unit that transfers a toner image onto a sheet, a fixing unit that fixes the toner image onto the sheet, a guide member that guides the sheet from the transfer unit toward the fixing unit, and a re-conveying tray that guides the sheet that has passed through the fixing unit and is then inverted and conveyed toward the transfer unit.

[0003] In such an image forming apparatus, the guide member is configured to be movable, which allows the sheet to be transported efficiently in response to the bending that occurs in the sheet as it is transported between the transfer unit and the fixing unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-226136 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the image forming apparatus equipped with the above-mentioned guide member and re-feed tray, the re-feed tray is located between the guide member and the re-feed path of the sheet transported from the fixing unit to the transfer unit. Therefore, in order to prevent interference between the re-feed tray and the guide member, the movable range of the guide member is limited, which may result in the sheet not being transported efficiently.

[0006] Therefore, the present invention provides an image forming apparatus that can efficiently transport sheets by suppressing restrictions on the movable range of the guide member. [Means for solving the problem]

[0007] The image forming apparatus that solves the above problem has the following features.

[0008] That is, the image forming apparatus includes a transfer unit that transfers a toner image onto a sheet, a fixing unit having a heating unit that fixes the toner image onto the sheet transported from the transfer unit, a movable chute located downstream of the transfer unit and upstream of the fixing unit in a first direction, which is the sheet transport direction from the transfer unit to the fixing unit, and the movable chute is movable between a first position and a second position, whose downstream end in the first direction is farther from a sheet transport path formed along the first direction than the first position, and a re-conveying chute that guides the sheet that has passed through the fixing unit to the transfer unit, and forms a re-conveying path for the sheet transported from the fixing unit to the transfer unit, and the movable chute has a sheet transport surface that is located on the opposite side of the re-conveying chute across the re-conveying path in the sheet thickness direction of the sheet transported along the sheet transport path, and that guides the sheet transported along the sheet transport path toward the fixing unit, and a first re-conveying surface that faces the opposite side of the sheet transport surface in the sheet thickness direction and forms the re-conveying path.

[0009] Therefore, the movable range of the movable chute is not limited when it is moved to the second position. This ensures a large space for the sheet transport path, allowing for efficient sheet transport. It also reduces the number of parts that make up the image forming apparatus and makes the image forming apparatus smaller in size in the vertical direction.

[0010] Furthermore, the first re-conveying surface forms the re-conveying path when the movable chute is located at the second position.

[0011] This allows the re-conveyance path to be formed by the movable chute while ensuring a large space for the sheet conveyance path.

[0012] The device also includes a drive source for moving the movable chute and a control unit for controlling the operation of the drive source, and the control unit controls the drive source to move the movable chute from the first position toward the second position after the leading edge of the sheet being transported along the sheet transport path has passed through the fixing unit.

[0013] After the leading edge of the sheet passes through the fixing unit, the sheet is conveyed at a speed faster by the transfer unit than by the fixing unit, causing the sheet to bend between the transfer unit and the fixing unit. Therefore, by controlling the control unit to move the movable chute toward the second position, a large space is secured for the sheet conveyance path between the transfer unit and the fixing unit, preventing the bent sheet from interfering with other components of the image forming device.

[0014] The control unit also includes a registration roller located upstream of the transfer unit in the first direction for correcting the inclination of the sheet being transported toward the transfer unit, and after the leading edge of the sheet being transported along the sheet transport path passes through the fixing unit, the control unit controls the drive source to move the movable chute from the first position toward the second position, maintains the movable chute at the second position while the leading edge of the sheet that has passed through the fixing unit passes through the re-conveying path, and after the leading edge of the sheet being transported along the re-conveying path passes through the registration roller, controls the drive source to move the movable chute from the second position toward the first position.

[0015] In this way, by maintaining the movable chute at the second position until the leading edge of the sheet passes through the registration rollers, it is possible to simplify the movement control of the movable chute.

[0016] The control unit also includes a registration roller located upstream of the transfer unit in the first direction for correcting the inclination of the sheet being transported toward the transfer unit, and the control unit controls the drive source to move the movable chute from the first position toward the second position after the leading edge of the sheet being transported along the sheet transport path passes the fixing unit, controls the drive source to move the movable chute from the second position toward the first position after the trailing edge of the sheet being transported along the sheet transport path passes the transfer unit, controls the drive source to move the movable chute from the first position toward the second position before the leading edge of the sheet being transported through the fixing unit and along the re-conveying path reaches the first re-conveying surface of the movable chute, and controls the drive source to move the movable chute from the first position toward the second position after the leading edge of the sheet being transported along the re-conveying path passes the registration roller.

[0017] In a configuration in which the movable chute is moved to the second position by the drive source, the drive source is turned on when the movable chute is moved to the second position. As a result, if the movable chute is continuously maintained in the second position from the time the leading edge of the sheet passes through the fixing unit until it passes through the re-conveyance path, heat is generated from the drive source and the amount of current consumed by the drive source increases. Therefore, by moving the movable chute to the first position when it is no longer necessary to move the movable chute to the second position after the leading edge of the sheet has passed through the fixing unit, the heat generated by the drive source and the amount of current consumed by the drive source can be reduced. This means:

[0018] The device also includes a solenoid actuator for moving the movable chute, and a chute link connected to the solenoid actuator for moving the movable chute from the first position to the second position, and the chute link is driven by the solenoid actuator to press the movable chute from the sheet conveying surface side, thereby moving the movable chute from the first position to the second position.

[0019] This allows the movable chute to be moved quickly and stably from the first position to the second position.

[0020] The device also includes a guide frame that rotatably supports the movable chute, the guide frame being located upstream of the movable chute in the first direction and having a second re-conveying surface that forms the re-conveying path, and a fixing chute being located upstream of the fixing device and downstream of the movable chute in the first direction and having a third re-conveying surface that forms the re-conveying path.

[0021] This eliminates the need to provide a member that forms the upper surface of the re-feed path separately from the guide frame and the fixing chute, thereby reducing the number of parts and the vertical dimension of the image forming apparatus.

[0022] The fixing chute and the movable chute overlap in the sheet transport direction of the sheet transported along the re-transport path.

[0023] This allows the sheet being transported along the re-transport path to be smoothly transferred from the fixing chute to the movable chute.

[0024] Furthermore, the upstream end of the first re-conveying surface of the movable chute in the second direction, which is the sheet conveying direction of the sheet conveyed along the re-conveying path toward the transfer section, is located farther from the re-conveying path than the downstream end of the third re-conveying surface of the fixing chute in the second direction.

[0025] This prevents the sheet being transported along the re-conveying path from getting caught at the boundary between the third re-conveying surface of the fixing chute and the first re-conveying surface of the movable chute, allowing the sheet to be transported smoothly.

[0026] Furthermore, the upstream end of the second re-conveying surface of the guide frame in the second direction, which is the sheet conveying direction of the sheet conveyed along the re-conveying path toward the transfer section, is located farther from the re-conveying path than the downstream end of the first re-conveying surface of the movable chute in the second direction.

[0027] This prevents the sheet being transported along the re-conveying path from getting caught at the boundary between the first re-conveying surface of the movable chute and the second re-conveying surface of the guide frame, allowing the sheet to be transported smoothly.

[0028] Furthermore, the position of the downstream end of the movable chute in the first direction when the movable chute is located at the second position is located lower than the position of the downstream end of the movable chute in the first direction when the movable chute is located at the first position.

[0029] This ensures that when the movable chute moves to the second position, a large space is secured for the sheet transport path between the transfer unit and the fixing unit, thereby preventing the bent sheet from interfering with other parts of the image forming device.

[0030] The sheet thickness direction is the vertical direction, and the movable chute is located above the re-conveying chute and forms the upper surface of the re-conveying path.

[0031] This eliminates the need to provide a member that forms the upper surface of the re-feed path separately from the movable chute, thereby reducing the number of parts and the vertical dimension of the image forming apparatus.

[0032] Moreover, the chute link presses the movable chute from above, thereby moving the movable chute from the first position to the second position.

[0033] This allows the movable chute to be moved stably from the first position to the second position.

[0034] The device also includes a guide frame that rotatably supports the movable chute, is located upstream of the movable chute in the first direction, and has a second re-conveying surface facing the re-conveying path, and a fixing chute that is located upstream of the fixing device and downstream of the movable chute in the first direction, and has a third re-conveying surface facing the re-conveying path, and the second re-conveying surface of the guide frame and the third re-conveying surface of the fixing chute form the upper surface of the re-conveying path.

[0035] This eliminates the need to provide a member that forms the upper surface of the re-feed path separately from the guide frame and the fixing chute, thereby reducing the number of parts and the vertical dimension of the image forming apparatus.

[0036] Moreover, the first re-conveying surface of the movable chute and the third re-conveying surface of the fixing chute overlap with each other when viewed from the left-right direction.

[0037] This allows the sheet being transported along the re-transport path to be smoothly transferred from the fixing chute to the movable chute.

[0038] It also includes a sheet metal member supported by the movable chute and a stopper attached to the movable chute from the first re-conveying surface side to fix the sheet metal member and the movable chute, and the stopper and the fixing chute overlap when viewed from the sheet thickness direction.

[0039] This allows the sheet to be smoothly transferred from the fixing chute to the movable chute even when a stopper is attached to the movable chute.

[0040] Furthermore, the first re-conveying surface forms the re-conveying path when the movable chute is located at the first position.

[0041] In this configuration, after the leading edge of the sheet transported from the transfer unit along the sheet transport path passes through the fixing unit, the movable chute can be moved from the first position to the second position, and after the trailing edge of the sheet passes through the transfer unit but before the leading edge of the sheet reaches the first re-transport surface, the movable chute can be moved from the second position to the first position. By moving the movable chute in this manner, the sheet can be transported smoothly and efficiently.

[0042] Furthermore, the movable chute enters the re-conveyance path when located at the second position.

[0043] This ensures that when the movable chute moves to the second position, a large space is secured for the sheet transport path between the transfer unit and the fixing unit, thereby preventing the bent sheet from interfering with other parts of the image forming device. [Effects of the Invention]

[0044] According to the present invention, the movable chute's range of motion is not limited when it is moved to the second position. This ensures a large space for the sheet transport path, allowing for efficient sheet transport. It also reduces the number of components that make up the image forming apparatus and makes the image forming apparatus smaller in size in the vertical direction. [Brief explanation of the drawings]

[0045] [Figure 1] 1 is a schematic central cross-sectional view showing an image forming apparatus. [Figure 2] FIG. 2 is a perspective view showing the image forming apparatus with the front cover in the open position. [Figure 3] FIG. 2 is a left-front perspective view showing the first body frame, the second body frame, the air duct, and the movable chute. [Figure 4] FIG. [Figure 5] FIG. 2 is a perspective view showing a heating unit and a pressure roller of the fixing unit. [Figure 6] FIG. 2 is a central cross-sectional view showing the image forming apparatus. [Figure 7] 10 is a side cross-sectional view showing a region between a transfer unit and a fixing unit in the apparatus main body when the movable chute is in a first position. FIG. [Figure 8] 10 is a side cross-sectional view showing a region between a transfer unit and a fixing unit in the apparatus main body when the movable chute is in a second position. FIG. [Figure 9] FIG. 10 is a perspective view showing a movable chute to which a chute metal plate is fixed. [Figure 10] FIG. 2 is an exploded perspective view showing the chute metal plate, the movable chute, and the chute stopper. [Figure 11] 1A is a plan view showing a movable chute to which a chute metal plate is fixed, and FIG. 1B is a bottom view showing the movable chute to which a chute metal plate is fixed. [Figure 12] FIG. 10 is a side cross-sectional view showing a movable chute to which a chute metal plate is fixed. [Figure 13] FIG. 2 is a perspective view showing a fixing chute, a movable chute, and a guide frame. [Figure 14] FIG. 2 is a bottom view showing the fixing chute, the movable chute, and the guide frame. [Figure 15] 15 is a cross-sectional view taken along the line AA in FIG. 14. [Figure 16] 15 is a cross-sectional view of FIG. 14 taken along the line B-B. [Figure 17] FIG. 2 is a block diagram showing a drive mechanism of the movable chute. [Figure 18] FIG. 10 is a rear cross-sectional view showing the chute link in a state separated from the movable chute. [Figure 19] FIG. 10 is a rear cross-sectional view showing the chute link in a state in which it is pressing the movable chute. [Figure 20] FIG. 10(a) is a perspective view showing a movable chute and a chute metal plate according to a second embodiment, and FIG. 10(b) is a plan view showing the movable chute and a chute metal plate according to the second embodiment. [Figure 21] FIG. 10 is a bottom view showing a fixing chute and a movable chute according to the second embodiment. [Figure 22] 22 is a cross-sectional view taken along CC in FIG. 21. [Figure 23] FIG. 11 is a side cross-sectional view showing the movable chute according to the third embodiment when the movable chute is located at a first position. [Figure 24] FIG. 11 is a side cross-sectional view showing the movable chute according to the third embodiment when the movable chute is located at a second position. DETAILED DESCRIPTION OF THE INVENTION

[0046] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0047] [Image forming equipment] An image forming apparatus 1 shown in FIG. 1 is an embodiment of an image forming apparatus equipped with a sheet conveying device according to the present invention, and is a laser printer that forms an image on a sheet S by electrophotography.

[0048] In the following description, the right side in Fig. 1 is defined as the front side of the image forming apparatus 1, the left side in Fig. 1 is defined as the rear side of the image forming apparatus 1, the front side of the paper in Fig. 1 is defined as the left side of the image forming apparatus 1, and the back side of the paper in Fig. 1 is defined as the right side of the image forming apparatus 1. In addition, the upper and lower sides in Fig. 1 are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0049] The image forming apparatus 1 includes an apparatus main body 2, a paper feed section 3, an image forming section 5, a fixing unit 6, and a paper discharge section 29.

[0050] The device main body 2 houses a paper feed unit 3, an image forming unit 5, a fixing unit 6, and a paper discharge unit 29. An opening 2A is open at the front of the device main body 2, and the device main body 2 has a front cover 21 that can open and close the opening 2A. The front cover 21 is configured to be rotatable around a rotation shaft 21a at the bottom end, and by rotating around the rotation shaft 21a, it can move between a closed position that closes the opening 2A and an open position that opens the opening 2A.

[0051] The paper feed unit 3 includes a paper feed tray 10 that supports the sheet S, a sheet conveying unit 30, a conveying roller pair 34, and a registration roller 35a. The paper feed unit 3 is disposed in the lower part of the apparatus main body 2, and conveys the sheet S supported on the paper feed tray 10 to the image forming unit 5. The image forming apparatus 1 has a conveying path P1 for the sheet S that runs from the paper feed unit 3 to the paper discharge unit 29 via the image forming unit 5. The conveying path P1 is an example of a sheet conveying path.

[0052] The sheet feed tray 10 has a pressure plate 12 and a pressing plate 13. The pressure plate 12 is a plate-shaped member that supports the sheets S from below. The pressure plate 12 is rotatable about a pivot point 12a at its rear end, and by rotating about the pivot point 12a, the pressure plate 12 can be raised and lowered between a lowered position and an upper position. The pressing plate 13 is located below the pressure plate 12, and can raise and lower the pressure plate 12 between the lowered position and the upper position.

[0053] The sheet conveying unit 30 is a conveying mechanism that separates and picks up the sheets S supported on the paper feed tray 10 one by one and conveys them toward the image forming unit 5, and is equipped with a paper feed roller 31, a separation roller 32, and a separation pad 33.

[0054] The paper feed roller 31 is a roller for sending the sheet S supported on the paper feed tray 10 toward the separation roller 32. The separation roller 32 is disposed downstream of the paper feed roller 31 in the sheet conveying direction, and the separation pad 33 is disposed opposite the separation roller 32 and is urged toward the separation roller 32.

[0055] The sheets S sent out by the paper feed roller 31 toward the separation roller 32 are separated one by one between the separation roller 32 and the separation pad 33. The separated sheets S are sent out to a conveying path P1.

[0056] The sheet S sent to the conveying path P1 is conveyed toward the image forming unit 5 by the conveying roller pair 34, the registration roller 35a, and the pinch roller 35b arranged opposite the registration roller 35a. The registration roller 35a regulates the movement of the leading edge of the sheet S conveyed from the paper feed tray 10 toward the image forming unit 5, stops the sheet S temporarily, corrects the skew of the sheet S, and then conveys the sheet S toward the image forming unit 5 at a predetermined timing. The registration roller 35a is a roller for correcting the skew of the sheet S conveyed toward the transfer unit 5A provided in the image forming unit 5.

[0057] The image forming apparatus 1 has a pre-registration sensor 97 located upstream of the registration rollers 35a in the sheet conveying direction, and a post-registration sensor 98 located downstream of the registration rollers 35a in the sheet conveying direction.

[0058] The pre-registration sensor 97 is a sensor for detecting the sheet S being transported along the transport path P1, and is configured to detect the leading edge of the sheet S and turn on when the leading edge of the sheet S passes the pre-registration sensor 97, and to detect the trailing edge of the sheet S and turn off when the trailing edge of the sheet S passes the pre-registration sensor 97.

[0059] The post-registration sensor 98 is a sensor for detecting the sheet S being transported along the transport path P1, and is configured to detect the leading edge of the sheet S and turn on when the leading edge of the sheet S passes the post-registration sensor 98, and to detect the trailing edge of the sheet S and turn off when the trailing edge of the sheet S passes the post-registration sensor 98.

[0060] The image forming unit 5 is disposed downstream of the paper feed unit 3 in the sheet transport direction, and forms an image on the sheet S transported from the paper feed unit 3. The image forming unit 5 includes a process cartridge 50 that transfers an image onto the surface of the sheet S transported from the paper feed unit 3, a transfer roller 55 that is disposed opposite the photosensitive drum 54 of the process cartridge 50, and an exposure unit 56 that exposes the surface of the photosensitive drum 54. The process cartridge 50 is an example of a cartridge that is detachable from the main body of the apparatus.

[0061] The process cartridge 50 is disposed above the paper feed unit 3 in the apparatus main body 2, and includes a developer storage chamber 51, a supply roller 52, a developing roller 53, and a photosensitive drum 54. The process cartridge 50 supports a pinch roller 35b.

[0062] The process cartridge 50 includes a drum cartridge having a photosensitive drum 54 and a developer cartridge that is attached to the drum cartridge and has a developing roller 53, and is detachably attached to the apparatus main body 2. In this case, the process cartridge 50 is attached to the apparatus main body 2 by inserting the drum cartridge and the developer cartridge attached to the drum cartridge into the apparatus main body 2 as a unit, and is detached from the apparatus main body 2 by removing the drum cartridge and the developer cartridge attached to the drum cartridge from the apparatus main body 2 as a unit.

[0063] The process cartridge 50 is an example of a cartridge and can include at least one of a photosensitive drum, a developing roller, and a toner container. The process cartridge 50 can be attached to and detached from the apparatus main body 2 when the front cover 21 is in the open position.

[0064] When the process cartridge 50 is attached to the apparatus main body 2, the photosensitive drum 54 is disposed with its axis X aligned in the left-right direction. The photosensitive drum 54 has a metal drum shaft 54a that extends along the axis X. The photosensitive drum 54 rotates around the drum shaft 54a.

[0065] In this embodiment, the process cartridge 50 comprises a drum cartridge having a photosensitive drum 54 and a developing cartridge attached to the drum cartridge and having a developing roller 53, but it can also be configured to comprise a cartridge having the photosensitive drum 54 and the developing roller 53, and a toner box attached to the cartridge and containing toner.

[0066] Furthermore, the image forming apparatus can be configured so that a drum cartridge having a photosensitive drum 54 and a developer cartridge having a developing roller 53 are separately mounted in the apparatus main body 2. In other words, the process cartridge 50 includes at least one of a photosensitive drum, a developing roller, and a toner container, and can be configured to be detachably mounted in the apparatus main body.

[0067] The exposure unit 56 is equipped with a laser diode, a polygon mirror, a lens, a reflecting mirror, etc., and exposes the surface of the photosensitive drum 54 by irradiating the photosensitive drum 54 with laser light based on image data input to the image forming apparatus 1.

[0068] Toner that will become the developer is stored in the developer storage chamber 51. The toner stored in the developer storage chamber 51 is stirred by a stirring member (not shown) and sent to the supply roller 52. The supply roller 52 further supplies the toner sent from the developer storage chamber 51 to the developing roller 53.

[0069] The developing roller 53 is disposed in close contact with the supply roller 52, and carries toner supplied from the supply roller 52 and positively charged by a sliding contact member (not shown). A developing bias is applied to the developing roller 53 by a bias application means (not shown).

[0070] The photosensitive drum 54 is disposed adjacent to the developing roller 53. The surface of the photosensitive drum 54 is uniformly charged by a charger (not shown) and then exposed by the exposure unit 56. The exposed portion of the photosensitive drum 54 has a lower potential than the other portions, and an electrostatic latent image based on the image data is formed on the photosensitive drum 54. Then, positively charged toner is supplied from the developing roller 53 to the surface of the photosensitive drum 54 on which the electrostatic latent image has been formed, thereby visualizing the electrostatic latent image into a toner image.

[0071] The transfer roller 55 is disposed opposite the photosensitive drum 54, and a transfer bias is applied to it by a bias application means (not shown). With the transfer bias applied to the surface of the transfer roller 55, the toner image formed on the surface of the photosensitive drum 54 is transferred to the surface of the sheet S by conveying the sheet S while sandwiching it between the photosensitive drum 54 on which the toner image has been formed and the transfer roller 55.

[0072] The process cartridge 50, the photosensitive drum 54, and the transfer roller 55 constitute a transfer unit 5A that transfers a toner image onto the sheet S. The sheet S onto which the toner image has been transferred is transported from the transfer unit 5A to the fixing unit 6. The sheet transport direction of the sheet S transported along the transport path P1 from the transfer unit 5A toward the fixing unit 6 is the first direction.

[0073] The fixing device 6 includes a heating unit 61 and a pressure roller 62, and fixes the image transferred onto the sheet S by the transfer section 5A. The heating unit 61 is heated by supplying power from a power source (not shown). The heating unit 61 is an example of a heating section. The pressure roller 62 is disposed opposite the heating unit 61. One of the heating unit 61 and the pressure roller 62 is biased toward the other by a biasing mechanism (not shown), and the heating unit 61 and the pressure roller 62 are in close contact with each other.

[0074] When the sheet S onto which the toner image has been transferred is conveyed to the fixing device 6, the sheet S is conveyed while being sandwiched between a heating unit 61 and a pressure roller 62, whereby the sheet S is heated and the toner image is fixed onto the sheet S. In this way, the fixing device 6 fixes the toner image onto the sheet S conveyed from the transfer section 5A. The sheet S onto which the toner image has been fixed by the fixing device 6 is conveyed to the paper discharge section 29 by a post-fixing conveying roller pair 68 disposed downstream of the fixing device 6 in the sheet conveying direction.

[0075] The image forming apparatus 1 has a sheet sensor 99 located between the fixing unit 6 and the post-fixing conveying roller pair 68. The sheet sensor 99 is a sensor for detecting the sheet S conveyed along the conveying path P1, and is configured to detect the leading edge of the sheet S when the leading edge of the sheet S passes the sheet sensor 99 and turn on, and to detect the trailing edge of the sheet S when the trailing edge of the sheet S passes the sheet sensor 99 and turn off.

[0076] The paper discharge section 29 is located downstream of the post-fixing conveying roller pair 68 in the sheet conveying direction, and discharges the sheet S on which an image has been formed in the image forming section 5 to the outside of the image forming apparatus 1, or conveys the sheet S again toward the image forming section 5. The paper discharge section 29 includes a paper discharge roller pair 291 and a paper discharge tray 292. The paper discharge tray 292 is provided in the apparatus main body 2. The printed sheet S on which an image has been formed in the image forming section 5 is discharged to the paper discharge tray 292.

[0077] Of the conveying path P1, the conveying path P1 downstream of the fixing unit 6 is formed as a discharge path P1a. The pair of paper discharge rollers 291 is configured to be able to discharge the sheet S conveyed from the fixing unit 6 along the discharge path P1a towards the outside of the device main body 2. The discharge path P1a is a path that guides the printed sheet S to a paper discharge tray 292. The paper discharge tray 292 is formed on the top surface of the device main body 2, and supports the sheet S discharged to the outside of the main body housing 2 by the pair of paper discharge rollers 291.

[0078] The pair of discharge rollers 291 is configured to be rotatable in a discharge direction, which is a rotation direction when conveying the sheet S toward the discharge tray 292, and in a re-conveyance direction, which is a rotation direction opposite to the discharge direction. The image forming apparatus 1 has a re-conveyance path P2 that guides the sheet S, which has been conveyed along the conveyance path P1 and passed through the fixing unit 6 and has been printed on one side, to the conveyance path P1 upstream of the registration rollers 33a in the sheet conveyance direction.

[0079] The re-conveying path P2 branches off from the discharge path P1a at a branch point Pb located between the post-fixing conveying roller pair 68 and the discharge roller pair 291, then extends forward between the image forming unit 5 and the paper feed tray 10, and merges with the conveying path P1 at a junction point Pa located between the conveying roller pair 34 and the registration roller 35a.

[0080] The sheet S conveyed from the fixing unit 6 to the paper discharge unit 29 can be conveyed again to the image forming unit 5 through a re-conveyance path P2 by rotating the paper discharge roller pair 291 in the re-conveyance direction. The sheet S conveyed to the re-conveyance path P2 by the paper discharge roller pair 291 is conveyed toward the image forming unit 5 by a first re-conveyance roller pair 36 and a second re-conveyance roller pair 37 provided on the re-conveyance path P2.

[0081] The sheet S transported along the re-conveying path P2 passes through the junction Pa and is then transported to the transfer unit 5A of the image forming unit 5. In this way, the re-conveying path P2 is a transport path for the sheet S transported from the fixing unit 6 toward the transfer unit 5A. The sheet transport direction of the sheet S transported along the re-conveying path P2 toward the transfer unit 5A is the second direction.

[0082] The image forming apparatus 1 is capable of double-sided printing, in which a sheet S, on one side of which an image has been formed in the image forming unit 5, is transported again to the image forming unit 5 via a re-transport path P2, and an image is formed on the other side of the sheet S.

[0083] 2 and 3, the device main body 2 includes a first body frame 26 and a second body frame 27 that are spaced apart in the left-right direction. The first body frame 26 is located at the right end of the device main body 2, and the second body frame 27 is located at the left end of the device main body 2. The first body frame 26 extends in the front-rear and up-down directions and is disposed with its plate surface facing left-right. The second body frame 27 extends in the front-rear and up-down directions and is disposed with its plate surface facing left-right.

[0084] The transfer unit 5A including the process cartridge 50 and the fixing unit 6 are disposed between the first body frame 26 and the second body frame 27. The first body frame 26 is disposed to the right of the transfer unit 5A and the fixing unit 6, and the second body frame 27 is disposed to the left of the transfer unit 5A and the fixing unit 6. The process cartridge 50 that constitutes the transfer unit 5A is detachably supported by the first body frame 26 and the second body frame 27.

[0085] The first body frame 26 supports a fan 29 that exhausts air from inside the apparatus body 2 to the outside of the apparatus body 2. The second body frame 27 supports a control board 951 on which electronic components such as a CPU 951a are mounted. The control board 951 constitutes a control unit 95 (see FIG. 17) for controlling the operation of the image forming apparatus 1.

[0086] An air duct 28 extending in the left-right direction is disposed between the first body frame 26 and the second body frame 27. The air duct 28 is provided across the first body frame 26 and the second body frame 27, with the right end of the air duct 28 supported by the first body frame 26 and the left end of the air duct 28 supported by the second body frame 27.

[0087] 6, the air duct 28 is located between the transfer unit 5A and the fixing unit 6 in the front-rear direction. The air duct 28 is disposed at a position overlapping with the fan 29 when viewed from the left-right direction. Air can circulate within the air duct 28. The air duct 28 guides the air within the apparatus main body 2 toward the fan 29.

[0088] [Fuser] 4 and 5, the heating unit 61 of the fixing device 6 includes a heater 611, a holder 612, a stay 613, and a belt 614. The heater 611 is a flat plate extending in the left-right direction. The heater 611 has a first surface 611A and a second surface 611B opposite to the first surface 611A, and the first surface 611A is supported by the holder 612.

[0089] Holder 612 is made of, for example, a resin member, and has a guide surface 612a and a support wall 612b. Guide surface 612a contacts an inner circumferential surface 614a of belt 614 to guide belt 614. Support wall 612b has a support surface 612A that supports heater 611. Support surface 612A of support wall 612b abuts against first surface 611A of heater 611. Stay 613 is a member that supports holder 612, and is formed by bending a plate material that is more rigid than holder 612, such as a steel plate, into a generally U-shaped cross section.

[0090] The belt 614 is an endless belt that is heat-resistant and flexible, and includes a metal tube made of a metal such as stainless steel and a fluororesin layer covering the metal tube. The heater 611, holder 612, and stay 613 are disposed inside the belt 614. The belt 614 is configured to rotate around the heater 611, holder 612, and stay 613. An inner peripheral surface 614a of the belt 614 contacts the heater 611.

[0091] The pressure roller 62 has a metal shaft 62A and an elastic layer 62B that covers the shaft 62A. The pressure roller 62 is pressed against the heater 611 via a belt 614. The pressure roller 62 sandwiches the belt 614 between itself and the heater 611, thereby forming a nip NP for heating and pressurizing the sheet S. In other words, the pressure roller 62 forms the nip NP with the pressure roller 62, and heats and pressurizes the sheet S together with the heater 611 at the nip NP.

[0092] The pressure roller 62 is configured to be rotationally driven by a driving force transmitted from a motor provided in the image forming apparatus 1. When the pressure roller 62 is rotationally driven, the pressure roller 62 rotates the belt 614 by friction with the belt 614 or the sheet S sandwiched in the nip NP. As a result, the sheet S onto which the toner image has been transferred is transported between the pressure roller 62 and the heated belt 614, whereby the toner image is thermally fixed.

[0093] 1 and 6 to 8, the fixing device 6 has a fixing frame 63 that covers the heating unit 61 and the pressure roller 62. The fixing frame 63 holds the heating unit 61 and the pressure roller 62. The fixing frame 63 covers the peripheries of the heating unit 61 and the pressure roller 62, and has a first opening 63a formed on the upstream side of the heating unit 61 and the pressure roller 62 in the first direction, and a second opening 63b formed on the downstream side of the heating unit 61 and the pressure roller 62 in the first direction.

[0094] The fixing frame 63 has an upper frame 63A and a lower frame 63B. The upper frame 63A is positioned higher than the lower frame 63B. The upper frame 63A covers the heating unit 61, and the lower frame 63B covers the pressure roller 62.

[0095] In this embodiment, the fixing device 6 includes a heating unit 61 having a heater 611 and a belt 614, and a pressure roller 62, but the fixing device 6 can also be configured to include a heating roller with a built-in heater and a pressure roller pressed against the heating roller.Furthermore, the fixing device 6 can also be configured to include a heating roller with a built-in heater and a pressure belt pressed against the heating roller by an elastic member.

[0096] [Re-transport chute] As shown in FIGS. 1 and 6, the apparatus main body 2 is provided with a re-conveying chute 23 that forms the re-conveying path P2. The re-conveying chute 23 is disposed between the paper feed tray 10 and the transfer unit 5A in the vertical direction. The re-conveying chute 23 is located below the re-conveying path P2 and has a lower chute surface 23a that forms the lower surface of the re-conveying path P2. The re-conveying chute 23 guides the sheet S that has passed through the fixing unit 6 along the re-conveying path P2 to the transfer unit 5A.

[0097] The re-conveying chute 23 is detachably attached to the device main body 2. The re-conveying chute 23 is configured to be movable in the front-to-rear direction, and the re-conveying chute 23 attached to the device main body 2 can be removed from the device main body 2 by pulling it out rearward.

[0098] [Fixed Shot] As shown in FIGS. 6 to 8, the image forming apparatus 1 includes a fixing chute 24. The fixing chute 24 is located upstream of the fixing unit 6 in the first direction, and is supported by the lower frame 63B of the fixing frame 63. The fixing chute 24 is located below the conveying path P1, and forms the lower surface of the conveying path P1. The fixing chute 24 has a sheet conveying surface 24A facing upward. The fixing chute 24 forms the lower surface of the conveying path P1 with the sheet conveying surface 24A. The sheet conveying surface 24A guides the lower side of the sheet S conveyed along the conveying path P1.

[0099] The fixing chute 24 is located above the re-conveying path P2 and forms the upper surface of the re-conveying path P2. The fixing chute 24 has a third re-conveying surface 24B that faces downward. The third re-conveying surface 24B is the surface opposite to the sheet conveying surface 24A in the up-down direction and faces the re-conveying path P2. The fixing chute 24 forms the upper surface of the re-conveying path P2 with the third re-conveying surface 24B. The third re-conveying surface 24B guides the upper side of the sheet S conveyed along the re-conveying path P2.

[0100] In this way, by forming the upper surface of the re-conveying path P2 by the third re-conveying surface 24B of the fixing chute 24, it is not necessary to provide a member that forms the upper surface of the re-conveying path P2 separately from the fixing chute 24, which reduces the number of parts. Also, the vertical dimension of the device main body 2 can be reduced.

[0101] [Movable chute] 6 to 8, the image forming apparatus 1 includes a movable chute 71. The movable chute 71 is located between the transfer unit 5A and the fixing unit 6 in the front-rear direction. In other words, the movable chute 71 is located downstream of the transfer unit 5A and upstream of the fixing unit 6 in the first direction. The fixing chute 24 is located downstream of the movable chute 71 in the first direction.

[0102] The movable chute 71 is located on the opposite side of the re-conveying chute 23 across the re-conveying path P2 in the up-down direction, which is the thickness direction of the sheet S conveyed along the conveying path P1. The movable chute 71 is located above the re-conveying chute 23. The movable chute 71 is also located below the conveying path P1. In other words, the movable chute 71 is located between the conveying path P1 and the re-conveying path P2 in the up-down direction.

[0103] The movable chute 71 has a sheet conveying surface 71A facing upward and a first re-conveying surface 71B facing downward on the opposite side of the sheet conveying surface 71A in the vertical direction. The sheet conveying surface 71A guides the sheet S from below as it is conveyed along the conveying path P1 toward the fixing device 6. The first re-conveying surface 71B guides the sheet S from above as it is conveyed along the re-conveying path P2 toward the transfer unit 5A. The first re-conveying surface 71B forms the upper surface of the re-conveying path P2.

[0104] In this way, by forming the upper surface of the re-conveying path P2 by the first re-conveying surface 71B of the movable chute 71 located above the re-conveying chute 23, it is not necessary to provide a member that forms the upper surface of the re-conveying path P2 separately from the movable chute 71, which reduces the number of parts. Also, the vertical dimension of the device main body 2 can be reduced.

[0105] Furthermore, in the image forming apparatus 1, the movable chute 71 is positioned on the opposite side of the re-conveying path P2 from the re-conveying chute 23, and is configured to form the re-conveying path P2, so the movable range of the movable chute 71 is not limited when the movable chute 71 is moved to the second position. This ensures a large space for the conveying path P1, allowing the sheet S to be conveyed efficiently. Furthermore, the number of parts constituting the device main body 2 can be reduced, and the device main body 2 can be made smaller in the vertical direction.

[0106] In particular, the first re-conveying surface 71B forms the re-conveying path P2 when the movable chute 23 is located in the second position, so that the re-conveying path P2 can be formed by the movable chute 71 while ensuring a large space in which the conveying path P1 is located.

[0107] The movable chute 71 is rotatable about a rotation shaft 713 located at the front end. By rotating about the rotation shaft 713, the movable chute 71 is movable between a first position (the position shown in FIG. 7) and a second position (the position shown in FIG. 8) where the downstream end 71a in the first direction is farther from the conveying path P1 than the first position. When the movable chute 71 moves from the first position to the second position, the downstream end 71a in the first direction comes into contact with the sheet conveying surface 24A of the fixing chute 24, thereby positioning the movable chute 71 at the second position.

[0108] When the movable chute 71 is located at the first position, the sheet transport surface 71A of the movable chute 71 guides the sheet S transported from the transfer unit 5A toward the fixing device 6. When the movable chute 71 is located at the second position, the sheet transport surface 71A is located farther from the transport path P1 than when the movable chute 71 is located at the first position.

[0109] When the sheet S is transported by the photosensitive drum 54 and transfer roller 55 of the transfer unit 5A and the fixing unit 6, the transport speed of the sheet S by the transfer unit 5A is faster than the transport speed of the sheet S by the fixing unit 6, and the sheet S is bent between the fixing unit 6 and the transfer unit 5A. When the movable chute 71 is located at the second position, the sheet transport surface 71A guides the bent sheet S toward the sheet transport surface 71A between the fixing unit 6 and the transfer unit 5A.

[0110] In this way, by guiding the sheet S using the movable chute 71 at the first position, which is closer to the conveying path P1 than the second position, the sheet conveyed from the transfer section 5A, which is composed of the photosensitive drum 54 and the transfer roller 55, can be properly guided to the fixing device 6 by the movable chute 71.

[0111] Furthermore, when the movable chute 71 is located at the second position, the position of the downstream end 71a in the first direction of the movable chute 71 is lower than the position of the downstream end 71a in the first direction of the movable chute 71 when the movable chute 71 is located at the first position. This ensures a large space for the conveying path P1 between the transfer unit 5A and the fixing unit 6 when the movable chute 71 moves to the second position, thereby preventing the bent sheet S from interfering with other components of the device main body 2.

[0112] When the movable chute 71 is located at the second position, the first re-conveying surface 71B of the movable chute 71 is located closer to the re-conveying path P2 than when the movable chute 71 is located at the first position. The first re-conveying surface 71B forms the upper surface of the re-conveying path P2 when the movable chute 71 is located at the second position. The first re-conveying surface 71B guides the upper side of the sheet S being transported along the re-conveying path P2 when the movable chute 71 is located at the second position.

[0113] 9 to 12, the movable chute 71 has a base portion 711, a plurality of guide ribs 712, and a rotation shaft 713. The movable chute 71 is made of a material containing, for example, polyethylene terephthalate (PET) and glass resin.

[0114] The base portion 711 is formed of a plate-like member that is curved so as to be concave downward when viewed from the left-right direction, and extends in the front-rear and left-right directions. The guide rib 712 protrudes upward from the upper surface of the base portion 711 and extends in the front-rear direction. The multiple guide ribs 712 are arranged at intervals from one another in the left-right direction. The front ends of the guide ribs 712 protrude forward beyond the base portion 711. The rear ends of the guide ribs 712 protrude rearward beyond the base portion 711. The upper surfaces of the guide ribs 712 form the sheet conveying surface 71A of the movable chute 71.

[0115] The lower surface of the base portion 711 forms a first re-conveyance surface 71B of the movable chute 71. The first re-conveyance surface 71B has a rear end 71Ba that is the upstream end in the second direction and a front end 71Bb that is the downstream end in the second direction.

[0116] The rotation shaft 713 is located at the front end of the base portion 711 and is provided at both the left and right ends of the base portion 711 .

[0117] [Chute sheet metal] A chute metal plate 72 is placed on the upper surface of the movable chute 71. The chute metal plate 72 is supported by the movable chute 71. The chute metal plate 72 is formed from a metal member and is grounded. The chute metal plate 72 is an example of a sheet metal member. The chute metal plate 72 has a base portion 721, an upstream flange 722, a downstream flange 723, and a plurality of slits 724.

[0118] Base portion 721 is formed of a plate-like member that is curved to fit along the curved base portion 711 of movable chute 71. Upstream flange 722 extends downward from the front end, which is the upstream end of base portion 721 in the first direction, and then extends forward. Downstream flange 723 extends downward from the rear end, which is the downstream end of base portion 721 in the first direction.

[0119] A plurality of slits 724 are provided, each extending in the front-to-rear direction. The multiple slits 724 are arranged at intervals from one another in the left-to-right direction. The slits 724 are holes through which the guide ribs 712 of the movable chute 71 pass from below. The chute metal plate 72 is superimposed on the upper surface of the movable chute 71 with the guide ribs 712 of the movable chute 71 passing through the slits 724 from below. By superimposing the chute metal plate 72 on the movable chute 71, the rigidity of the movable chute 71 can be increased by the chute metal plate 72.

[0120] Furthermore, by overlapping the grounded chute metal plate 72 with the movable chute 71, when the charged sheet S that has passed through the transfer unit 5A is guided by the movable chute 71, the sheet S is attracted to the chute metal plate 72, which prevents the sheet S from moving wildly as it is conveyed. This allows the sheet S to be conveyed stably.

[0121] The front end of the slit 724 engages with the front end of the guide rib 712, and the rear end of the slit 724 engages with the rear end of the guide rib 712. This prevents the chute metal plate 72, which is placed over the movable chute 71, from moving upward relative to the movable chute 71.

[0122] [Shoot Stopper] The movable chute 71 and the chute metal plate 72 are fixed together by a chute stopper 73. The chute stopper 73 is an example of a stopper. The chute stopper 73 is formed from a plate-like member. The chute stopper 73 is formed from, for example, ABS resin. The chute stopper 73 is attached to the rear end of the movable chute 71 and in the center on the left and right. The chute stopper 73 is attached to the movable chute 71 from the side of the first re-conveyance surface 71B of the movable chute 71.

[0123] 11, the first re-conveying surface 71B of the movable chute 71 has a central re-conveying surface 71BC, a left re-conveying surface 71BL, and a right re-conveying surface 71BR. The central re-conveying surface 71BC is located in the center of the first re-conveying surface 71B in the left-right direction, the left re-conveying surface 71BL is located to the left of the central re-conveying surface 71BC, and the right re-conveying surface 71BR is located to the right of the central re-conveying surface 71BC.

[0124] The rear end 71Ba of the central re-conveyance surface 71BC is recessed further forward than the rear ends 71Ba of the left re-conveyance surface 71BL and the right re-conveyance surface 71BR. A stopper mounting surface 71C is formed on the base portion 711 behind the rear end 71Ba of the central re-conveyance surface 71BC (see FIG. 12). The stopper mounting surface 71C faces downward. The stopper mounting surface 71C is located above the central re-conveyance surface 71BC.

[0125] 11 and 12, the movable chute 71 has a holding portion 715. The holding portion 715 is disposed on the stopper mounting surface 71C of the base portion 711. The holding portion 715 has a first wall 715a that protrudes downward from the stopper mounting surface 71C of the base portion 711, and a second wall 715b that protrudes rearward from the lower end of the first wall 715a. The holding portions 715 are provided at two locations, one on the left and one on the right of the stopper mounting surface 71C, and hold the left and right ends of the chute stopper 73.

[0126] Chute stopper 73 attached to movable chute 71 is sandwiched in the vertical direction between base portion 711 and second wall 715b of holding portion 715. In this way, chute stopper 73 is held by holding portion 715. Chute stopper 73 attached to movable chute 71 covers stopper mounting surface 71C from below.

[0127] The chute stopper 73 attached to the movable chute 71 is sandwiched in the front-to-rear direction between the downstream flange 723 of the chute metal plate 72 and the first wall 715a of the holding portion 715. This restricts the chute metal plate 72 from moving in the front-to-rear direction relative to the movable chute 71, and fixes the chute metal plate 72 to the movable chute 71.

[0128] [Chute spring] Chute springs 74 are engaged with the left and right rotation shafts 713 of the movable chute 71. The chute springs 74 are torsion springs. The chute springs 74 bias the movable chute 71 from the second position toward the first position.

[0129] [Guide frame] As shown in FIGS. 6 to 8, the image forming apparatus 1 includes a guide frame 25. The guide frame 25 is located upstream of the movable chute 71 in the first direction and rotatably supports the movable chute 71. The guide frame 25 is located below the transfer unit 5A. The guide frame 25 rotatably supports the registration roller 35a.

[0130] The guide frame 25 is located above the re-conveying path P2 and forms the upper surface of the re-conveying path P2. The guide frame 25 has a second re-conveying surface 25A facing downward. The second re-conveying surface 25A faces the re-conveying path P2. The guide frame 25 forms the upper surface of the re-conveying path P2 with the second re-conveying surface 25A. The second re-conveying surface 25A guides the upper side of the sheet S being transported along the re-conveying path P2.

[0131] In this way, by forming the upper surface of the re-conveying path P2 by the second re-conveying surface 25A of the guide frame 25, it is not necessary to provide a member that forms the upper surface of the re-conveying path P2 separately from the guide frame 25, and it is possible to reduce the number of parts. Also, it is possible to reduce the vertical dimension of the device main body 2.

[0132] [Positional relationship between the fixed chute, movable chute, and guide frame] 13 to 16, the third re-conveying surface 24B in the fixing chute 24 has a central re-conveying surface 24BC, a left re-conveying surface 24BL, and a right re-conveying surface 24BR. The central re-conveying surface 24BC is located in the center of the third re-conveying surface 24B in the left-right direction, the left re-conveying surface 24BL is located to the left of the central re-conveying surface 24BC, and the right re-conveying surface 24BR is located to the right of the central re-conveying surface 24BC.

[0133] The central re-conveying surface 24BC, the left re-conveying surface 24BL, and the right re-conveying surface 24BR each have a front end 24Ba that is the downstream end of the third re-conveying surface 24B in the fixing chute 24. The front end 24Ba of the central re-conveying surface 24BC protrudes further forward than the front ends 24Ba of the left re-conveying surface 24BL and the right re-conveying surface 24BR.

[0134] The front ends 24Ba of the left re-conveying surface 24BL and the right re-conveying surface 24BR of the third re-conveying surface 24B of the fixing chute 24 are located behind the rear end 71Ba of the first re-conveying surface 71B of the movable chute 71. On the other hand, the front end 24Ba of the central re-conveying surface 24BC of the third re-conveying surface 24B of the fixing chute 24 is located forward of the rear ends 71Ba of the left re-conveying surface 71BL and the right re-conveying surface 71BR of the movable chute 71.

[0135] That is, the portion of the fixing chute 24 where the central re-conveyance surface 24BC is formed overlaps with the portions of the movable chute 71 where the left re-conveyance surface 71BL and the right re-conveyance surface 71BR are formed in the second direction. Therefore, when the sheet S transported along the re-conveyance path P2 is guided by the third re-conveyance surface 24B of the fixing chute 24 and the first re-conveyance surface 71B of the movable chute 71, there is no interruption in the guiding by the fixing chute 24 and the guiding by the movable chute 71. This allows the sheet S transported along the re-conveyance path P2 to be smoothly transferred from the fixing chute 24 to the movable chute 71.

[0136] The front end 24Ba of the central re-conveyance surface 24BC of the fixing chute 24 is located behind the rear end 71Ba of the central re-conveyance surface 71BC of the movable chute 71.

[0137] Furthermore, the front end of the central re-conveyance surface 24BC of the third re-conveyance surface 24B of the fixing chute 24 is located below the stopper attachment surface 71C of the movable chute 71 and covers from below the chute stopper 73 attached to the stopper attachment surface 71C. In other words, the movable chute 71 and the chute stopper 73 overlap when viewed from the top-bottom direction.

[0138] Therefore, even if the chute stopper 73 is attached to the movable chute 71, the sheet S transported along the re-conveyance path P2 does not interfere with the chute stopper 73 when transferring from the third re-conveyance surface 24B to the first re-conveyance surface 71B. This allows the sheet S to be smoothly transferred from the fixing chute 24 to the movable chute 71.

[0139] Further, the central re-conveying surface 24BC of the third re-conveying surface 24B of the fixing chute 24 and the left re-conveying surface 71BL and the right re-conveying surface 71BR of the first re-conveying surface 71B of the movable chute 71 overlap with each other when viewed from the left-right direction.

[0140] Therefore, when the sheet S transported along the re-conveying path P2 is guided by the third re-conveying surface 24B and the first re-conveying surface 71B, the sheet S can be guided by both the third re-conveying surface 24B and the first re-conveying surface 71B at the boundary between the third re-conveying surface 24B and the first re-conveying surface 71B. This makes it possible to smoothly transfer the sheet S transported along the re-conveying path P2 from the fixing chute 24 to the movable chute 71.

[0141] 15 and 16, when the movable chute 71 is in the second position, a rear end 71Ba, which is the upstream end in the second direction of the first re-conveying surface 71B of the movable chute 71, is located farther from the re-conveying path P2 than a front end 24Ba, which is the downstream end in the second direction of the third re-conveying surface 24B of the fixing chute 24. In other words, the rear end 71Ba of the first re-conveying surface 71B is located higher than the front end 24Ba of the third re-conveying surface 24B.

[0142] As a result, a step is formed at the boundary between the third re-conveying surface 24B and the first re-conveying surface 71B, where the first re-conveying surface 71B is further away from the re-conveying path P2 than the third re-conveying surface 24B. Therefore, the sheet S being transported along the re-conveying path P2 does not get caught at the boundary between the third re-conveying surface 24B of the fixing chute 24 and the first re-conveying surface 71B of the movable chute 71, and the sheet S can be transported smoothly.

[0143] Furthermore, when the movable chute 71 is located at the second position, a rear end 25Aa, which is the upstream end in the second direction of the second re-conveying surface 25A of the guide frame 25, is located farther from the re-conveying path P2 than a front end 71Bb, which is the downstream end in the second direction of the first re-conveying surface 71B of the movable chute 71. In other words, the rear end 25Aa of the second re-conveying surface 25A is located higher than the front end 71Bb of the first re-conveying surface 71B.

[0144] As a result, a step is formed at the boundary between the first re-conveying surface 71B and the second re-conveying surface 25A, where the second re-conveying surface 25A is further away from the re-conveying path P2 than the first re-conveying surface 71B. Therefore, the sheet S being transported along the re-conveying path P2 does not get caught at the boundary between the first re-conveying surface 71B of the movable chute 71 and the second re-conveying surface 25A of the guide frame 25, and the sheet S can be transported smoothly.

[0145] [Movement control of the movable chute] 17, image forming apparatus 1 has solenoid 92, which is a drive source for moving movable chute 71. Solenoid 92 is a solenoid actuator for moving movable chute 71, which is biased toward the first position by chute spring 74, from the first position to the second position. Solenoid 92 is connected to control unit 95, which controls the operation of solenoid 92. Control unit 95 controls the operation of solenoid 92, thereby controlling the movement of movable chute 71. A pre-registration sensor 97, a post-registration sensor 98, and a sheet sensor 99 are connected to control unit 95.

[0146] After the leading edge of the sheet S conveyed along the conveying path P1 passes through the fixing device 6, the control unit 95 controls the solenoid 92 to move the movable chute 71 from the first position to the second position. The solenoid 92 is configured to move the movable chute 71 via the chute link 75, for example.

[0147] In this case, the control unit 95 can determine that the leading edge of the sheet S has passed through the fixing unit 6, for example, when a predetermined time has elapsed since the post-registration sensor 98 detected the leading edge of the sheet S, and can control the solenoid 92 to move the movable chute 71 from the first position to the second position. For example, when the solenoid 92 is driven by the control unit 95 to turn on, the movable chute 71 is pressed against the chute link 75 and moves from the first position to the second position against the biasing force of the chute spring 74.

[0148] After the leading edge of the sheet S passes through the fixing unit 6, the speed at which the sheet S is conveyed by the transfer unit 5A is greater than the speed at which the sheet S is conveyed by the fixing unit 6, and therefore the sheet S bends between the transfer unit 5A and the fixing unit 6. Therefore, by moving the movable chute 71 toward the second position under the control of the control unit 95, a large space is secured for the conveying path P1 between the transfer unit 5A and the fixing unit 6, and it is possible to prevent the bent sheet S from interfering with other components of the device main body 2.

[0149] After the movable chute 71 is moved from the first position toward the second position under the control of the control unit 95, the movable chute 71 is maintained at the second position while the leading edge of the sheet S that has passed through the fixing unit 6 passes through the re-conveyance path P2. Furthermore, after the leading edge of the sheet S being conveyed along the re-conveyance path P2 passes through the registration rollers 35a, the solenoid 92 is controlled to move the movable chute 71 from the second position toward the first position.

[0150] In this case, for example, when a predetermined time has elapsed since the pre-registration sensor 97 detected the leading edge of the sheet S, the control unit 95 can determine that the leading edge of the sheet S has passed the registration rollers 35a and control the solenoid 92 to move the movable chute 71 from the second position toward the first position. For example, when the control unit 95 stops driving the solenoid 92 and turns it off, the pressure from the solenoid 92 is released and the movable chute 71 moves from the first position toward the second position due to the biasing force of the chute spring 74.

[0151] When the movable chute 71 is moved from the first position toward the second position after the leading edge of the sheet S has passed through the fixing unit 6, the deflection of the sheet S is eliminated when the state in which the sheet S is conveyed by both the fixing unit 6 and the transfer unit 5A is released. Therefore, during the period from when the state in which the sheet S is conveyed by the fixing unit 6 and the transfer unit 5A is released until the leading edge of the sheet S reaches the first re-conveyance surface 71B of the movable chute 71, it is possible to move the movable chute 71 to the first position.

[0152] However, when the movable chute 71 moves to the second position, a re-conveyance path P2 is formed by the first re-conveyance surface 71B of the movable chute 71. Therefore, after the movable chute 71 moves to the second position, the sheet S is conveyed along the re-conveyance path P2, and the movable chute can be maintained at the second position until the leading edge of the sheet S passes through the registration rollers 35a. In this way, by maintaining the movable chute at the second position until the leading edge of the sheet S passes through the registration rollers 35a, movement control of the movable chute 71 can be simplified.

[0153] [Modification of the movement control of the movable chute] The control unit 95 can also control the movement of the movable chute 71 as follows.

[0154] After the leading edge of the sheet S being conveyed along the conveying path P1 passes through the fixing device 6, the control unit 95 controls the solenoid 92 to move the movable chute 71 from the first position to the second position.

[0155] In this case, the control unit 95 can determine that the leading edge of the sheet S has passed through the fixing unit 6, for example, when a predetermined time has elapsed since the post-registration sensor 98 detected the leading edge of the sheet S, and can control the solenoid 92 to move the movable chute 71 from the first position to the second position.

[0156] Next, after the trailing edge of the sheet S being conveyed along the conveying path P1 passes through the transfer unit 5A, the control unit 95 controls the solenoid 92 to move the movable chute 71 from the second position toward the first position.

[0157] In this case, the control unit 95 determines that the rear end of the sheet S has passed through the transfer unit 5A, for example, when a predetermined time has elapsed since the post-registration sensor 98 detected the rear end of the sheet S, and can control the solenoid 92 to move the movable chute 71 from the second position toward the first position.

[0158] Furthermore, the control unit 95 controls the solenoid 92 to move the movable chute 71 from the first position toward the second position before the leading edge of the sheet S, which has passed through the fixing unit 6 and is being transported along the re-transport path P2, reaches the first re-transport surface 71B of the movable chute 71.

[0159] In this case, the control unit 95 determines that the leading edge of the sheet S will reach the first re-conveying surface 71B when a predetermined time has elapsed since the sheet sensor 99 detected the leading edge of the sheet S, and controls the solenoid 92 to move the movable chute 71 from the first position toward the second position before the predetermined time has elapsed since the sheet sensor 99 detected the leading edge of the sheet S.

[0160] Thereafter, after the leading edge of the sheet S being transported along the re-transport path P2 has passed the registration roller 35a, the control unit 95 controls the solenoid 92 to move the movable chute 71 from the second position toward the first position.

[0161] In this case, the control unit 95 determines that the leading edge of the sheet S has passed the registration roller 35a, for example, when a predetermined time has elapsed since the pre-registration sensor 97 detected the leading edge of the sheet S, and controls the solenoid 92 to move the movable chute 71 from the second position toward the first position.

[0162] In a configuration in which the movable chute 71 is moved to the second position by the solenoid 92, the solenoid 92 is turned on when the movable chute 71 is moved to the second position. As a result, if the movable chute 71 is continuously maintained at the second position from the time the leading edge of the sheet S passes through the fixing unit 6 until it passes through the re-conveyance path P2, heat is generated from the solenoid 92 and the amount of current consumed by the solenoid 92 increases.

[0163] Therefore, when there is no need to move the movable chute 71 to the second position after the leading edge of the sheet S has passed through the fixing device 6, the movable chute 71 can be moved to the first position, thereby suppressing heat generation from the solenoid 92 and current consumption by the solenoid 92.

[0164] [Shoot Link] 17 to 19, the chute link 75 is connected to a solenoid 92. The chute link 75 is driven by the solenoid 92 to press the movable chute 71, thereby moving the movable chute 71 from the first position to the second position.

[0165] The solenoid 92 has a main body 921 supported by the second main body frame 27, and a plunger 922 that is movable left and right relative to the main body 921. The plunger 922 is urged rightward from the main body 921 by a urging member, and in an OFF state in which the solenoid 92 is not driven by the control unit 95, the plunger 922 moves rightward and protrudes from the main body 921. On the other hand, in a state in which the solenoid 92 is driven by the control unit 95, the plunger 922 is retracted into the main body 921 and moved leftward, becoming an ON state.

[0166] Chute link 75 has a first link 751, a second link 752, and a third link 753. First link 751 and second link 752 are located inside air duct 28, and third link 753 protrudes downward from the inside of air duct 28. A holder 77 for supporting chute link 75 is attached inside air duct 28.

[0167] The first link 751 is a long member extending in the left-right direction and is supported by the holder 77 so as to be movable in the left-right direction. The first link 751 has a first end 751a which is the left end and a second end 751b which is the right end. The first end 751a is connected to the plunger 922 of the solenoid 92. The second end 751b abuts against the second link 752.

[0168] The second link 752 is a long member extending in the left-right direction and is located below the first link 751. The second link 752 has a rotation shaft 752a located at the right end, a contact portion 752b extending upward from the rotation shaft 752a, a tip portion 752c at the left end, and an engagement portion 752d extending diagonally upward and to the right from the rotation shaft 752a. The second link 752 is supported by the holder 77 so as to be rotatable about the rotation shaft 752a.

[0169] The image forming apparatus 1 has a link spring 76 that biases the second link 752. The link spring 76 is attached to a holder 77. One end of the link spring 76 engages with a hook 771 of the holder 77, and the other end of the link spring 76 engages with an engaging portion 752d of the second link 752. The second link 752 is biased by the link spring 76 so as to rotate in a direction in which a tip portion 752c moves upward. The abutting portion 752b abuts against a second end portion 751b of the first link 751, and when the first link 751 moves leftward, the abutting portion 752b is pressed leftward by the second end portion 751b, causing the second link 752 to rotate in a direction in which the tip portion 752c moves downward.

[0170] The third link 753 is a long member that extends vertically and is arranged to be movable in the vertical direction. The third link 753 has a connecting portion 753a located at the upper end and a pressing portion 753b located at the lower end. The connecting portion 753a is connected to the tip end 752c of the second link 752, and the pressing portion 753b can press the pressed portion 714 of the movable chute 71.

[0171] 9, 18, and 19, the pressed portion 714 of the movable chute 71 is formed on the sheet conveying surface 71A side and faces upward. The sheet conveying surface 71A of the movable chute 71 is formed in an area through which the sheet S passes in the left-right direction, and the pressed portion 714 is located outside the area where the sheet conveying surface 71A is formed in the left-right direction. In this embodiment, the pressed portion 714 is located to the left of the area where the sheet conveying surface 71A is formed.

[0172] The pressing portion 753b of the third link 753 and the pressed portion 714 of the movable chute 71 face each other in the vertical direction, and when the third link 753 moves downward, the pressing portion 753b presses the pressed portion 714 from above.

[0173] In the chute link 75 configured in this manner, when the solenoid 92 is in an off state where it is not driven by the control unit 95, the first link 751 connected to the plunger 922 is moved to the right, and the second link 752 is rotated by the force of the link spring 76 in a direction in which the tip end 752c moves upward.

[0174] Third link 753 is in a state of being moved upward by second link 752, and pressing portion 753b of third link 753 is separated from pressed portion 714 of movable chute 71. Movable chute 71 is moved to the first position by the biasing force of chute spring 74.

[0175] On the other hand, when the solenoid 92 is in an on state driven by the control unit 95, the first link 751 moves to the left by the plunger 922 attracted by the main body 921. When the first link 751 moves to the left, the second end portion 751b of the first link 751 presses the abutment portion 752b of the second link 752, and the second link 752 rotates in a direction in which the tip portion 752c moves downward against the biasing force of the link spring 76.

[0176] As the second link 752 rotates, the third link 753 moves downward, and the pressing portion 753b of the third link 753 presses the pressed portion 714 of the movable chute 71 downward, causing the movable chute 71 to move from the first position to the second position against the spring force of the chute spring 74.

[0177] In this way, the chute link 75 is driven by the solenoid 92 in the ON state to press the movable chute 71 from above, on the side of the sheet conveying surface 71A, thereby moving the movable chute 71 from the first position to the second position. This makes it possible to move the movable chute 71 quickly and stably from the first position to the second position.

[0178] Conversely, when the solenoid 92 is switched from the ON state to the OFF state, the chute link 75 moves away from the movable chute 71, and the biasing force of the chute spring 74 moves the movable chute 71 from the second position to the first position.

[0179] [Second embodiment of the movable chute, chute metal plate, and fixed chute] The movable chute 71, the chute metal plate 72, and the fixing chute 24 can also be configured as a movable chute 171, a chute metal plate 172, and a fixing chute 124 shown in FIGS.

[0180] The movable chute 171 and the chute metal plate 172 are fixed to each other without using a chute stopper, which differs from the movable chute 71 and the chute metal plate 72 that are fixed to each other using a chute stopper 73.

[0181] The movable chute 171 has a base 1711, a guide rib 1712, a rotation shaft 1713, a pressed portion 1714, and a hook 1715. The hook 1715 is formed on the upper surface of the base 1711.

[0182] Base 1711 differs from base 711 in that it has a hook 1715 formed on its upper surface and is not designed to mount chute stopper 71, but is otherwise similar in configuration to base 711.

[0183] The guide rib 1712, the pivot shaft 1713, and the pressed portion 1714 are formed in the same manner as the guide rib 712, the pivot shaft 713, and the pressed portion 714 of the movable chute 71. The upper surface of the guide rib 1712 forms the sheet conveying surface 171A of the movable chute 171. The lower surface of the base portion 1711 forms the first re-conveying surface 171B of the movable chute 171.

[0184] Chute metal plate 172 has a base portion 1721, an upstream flange 1722, a downstream flange 1723, a slit 1724, and an engagement hole 1725. Base portion 1721, upstream flange 1722, downstream flange 1723, and slit 1724 are formed in the same manner as base portion 721, upstream flange 722, downstream flange 723, and slit 724 of chute metal plate 72, respectively. Engagement hole 1725 is formed in base portion 1721 and is engageable with hook 1715 of movable chute 171.

[0185] With the chute metal plate 172 placed on the upper surface of the movable chute 171 , the hooks 1715 engage with the engagement holes 1725 , thereby fixing the chute metal plate 172 to the movable chute 171 .

[0186] The first re-conveying surface 171B has a rear end 171Ba that is the upstream end in the second direction and a front end 171Bb that is the downstream end in the second direction. Because no chute stopper is provided on the first re-conveying surface 171B of the movable chute 171, the rear end 171Ba of the first re-conveying surface 171B is located at the same front-to-rear position throughout the entire range in the left-to-right direction.

[0187] The fixing chute 124 has a sheet conveying surface 124A and a third re-conveying surface 124B. The fixing chute 124 differs from the fixing chute 24 in that the front end 24Ba of the central re-conveying surface 24BC protrudes further forward than the front ends 24Ba of the left re-conveying surface 24BL and the right re-conveying surface 24BR in that the front end 24Ba of the third re-conveying surface 124B is the same across the entire length in the left-right direction. The other configurations of the fixing chute 124 are the same as those of the fixing chute 24.

[0188] A front end 124Ba of the third re-conveying surface 124B of the fixing chute 124 is located behind a rear end 171Ba of the first re-conveying surface 171B, and the fixing chute 124 and the movable chute 171 do not overlap in the front-rear direction.

[0189] No chute stopper is attached to the third re-conveying surface 124B of the movable chute 171, and there is no need to cover the area below the third re-conveying surface 124B with the fixing chute 124, so the sheet S can be transported smoothly even if the fixing chute 124 and the movable chute 171 do not overlap in the front-to-rear direction.

[0190] Furthermore, by forming the movable chute 171 so that the front-rear position of the front end 124Ba of the third re-conveying surface 124B is the same across the entire range in the left-right direction, the shape of the movable chute 171 can be simplified.

[0191] In the movable chute 171 and the fixing chute 124, the rear end 171Ba of the first re-conveyance surface 171B in the movable chute 171 is positioned farther from the re-conveyance path P2 than the front end 124Ba of the third re-conveyance surface 124B in the fixing chute 124. This allows the sheet S to be smoothly transported between the fixing chute 124 and the movable chute 171.

[0192] Also, in the guide frame 25 and the movable chute 171, the rear end 25Aa of the second re-conveying surface 25A in the guide frame 25 is positioned farther from the re-conveying path P2 than the front end 171Bb of the first re-conveying surface 171B in the movable chute 171. This allows the sheet S to be smoothly conveyed between the movable chute 171 and the guide frame 25.

[0193] [Third embodiment of movable chute] The movable chute 71 can also be formed like a movable chute 271 shown in FIGS.

[0194] The movable chute 271 has a sheet conveying surface 271A facing upward, and a first re-conveying surface 271B facing downward on the opposite side of the sheet conveying surface 271A in the vertical direction. The sheet conveying surface 271A guides the sheet S from below as it is conveyed along the conveying path P1 toward the fixing device 6. The first re-conveying surface 271B guides the sheet S from above as it is conveyed along the re-conveying path P2 toward the transfer unit 5A. The first re-conveying surface 271B forms the upper surface of the re-conveying path P2.

[0195] The movable chute 271 is rotatable about a rotation shaft 2713 located at the front end. By rotating about the rotation shaft 2713, the movable chute 271 is movable between a first position (the position shown in FIG. 23) and a second position (the position shown in FIG. 24) where the downstream end 271a in the first direction is farther from the conveying path P1 than the first position.

[0196] When the movable chute 21 is located at the first position, the sheet conveying surface 271A of the movable chute 271 guides the sheet S conveyed from the transfer unit 5A toward the fixing device 6. In addition, when the movable chute 21 is located at the first position, the first re-conveying surface 271B of the movable chute 271 forms a re-conveying path P2.

[0197] When the movable chute 271 is located at the second position, the sheet conveying surface 271A is located farther from the conveying path P1 than when the movable chute 271 is located at the first position. When the movable chute 271 is located at the second position, the sheet conveying surface 271A guides the sheet S that is bent toward the sheet conveying surface 271A between the fixing unit 6 and the transfer unit 5A.

[0198] When the movable chute 271 is located at the second position, the position of the downstream end 271a in the first direction of the movable chute 271 is located lower than the position of the downstream end 271a in the first direction of the movable chute 271 when the movable chute 271 is located at the first position. This ensures a large space for the conveying path P1 between the transfer unit 5A and the fixing unit 6 when the movable chute 271 moves to the second position, thereby preventing the bent sheet S from interfering with other components of the device main body 2.

[0199] Furthermore, when the movable chute 271 is located at the second position, the first re-conveying surface 271B enters the re-conveying path P2. In this way, by configuring the first re-conveying surface 271B to enter the re-conveying path P2 when the movable chute 271 is located at the second position, the sheet conveying surface 271A can be moved to a position far away from the conveying path P1 when the movable chute 271 is moved to the second position. This makes it possible to secure as large a space as possible for the conveying path P1 in a limited space, and to effectively absorb the flex of the sheet S.

[0200] Furthermore, the movable chute 271 is configured such that the first re-conveying surface 271B forms the re-conveying path P2 when the movable chute 271 is located at the first position.

[0201] In this configuration, after the leading edge of the sheet S conveyed from the transfer unit 5A along the conveying path P1 passes through the fixing unit 6, the movable chute 271 can be moved from the first position to the second position, and after the trailing edge of the sheet S passes through the transfer unit 5A and before the leading edge of the sheet S reaches the first re-conveying surface 271B, the movable chute 271 can be moved from the second position to the first position. By moving the movable chute 271 in this manner, the sheet S can be conveyed smoothly and efficiently.

[0202] Furthermore, in this configuration, the movable chute 271 can be moved without using the solenoid 92 and the chute link 72. In this case, the movable chute 271 can be moved from the first position to the second position by utilizing the force pressing against the movable chute 271 when the sheet S is bent as it is transported from the transfer unit 5A along the transport path P1. Furthermore, as the trailing end of the sheet S passes through the transfer unit 5A, the bending of the sheet S is eliminated, and the pressing force of the sheet S against the movable chute 271 is eliminated, allowing the movable chute 271 to be moved from the second position to the first position by the force of the chute spring 74. This allows the sheet S to be transported smoothly and efficiently without controlling the movement of the movable chute 71. [Explanation of symbols]

[0203] 1. Image forming device 2. Device body 5. Image forming unit 5A Transfer section 6 Fixing unit 23 Re-transport chute 24 Fixation Shot 24B 3rd re-transport surface 24Ba (downstream end of the third re-conveying surface in the second direction) 25 Guide Frame 25A Second re-transport surface 25Aa (upstream end of second re-conveying surface in second direction) 35a Registration roller 61 Heating unit 71, 171 Movable chute 71a, 171a (downstream end of the movable chute in the first direction) 71A, 171A sheet transport surface 71B, 171B First re-transport surface 71Ba, 171Ba (upstream end of the first re-conveying surface in the second direction) 71Bb, 171Bb (downstream end of the first re-conveying surface in the second direction) 72, 172 chute sheet metal 73 Shot Stopper 92 Solenoid 75 Shoot Link 95 Control Unit P1 transport route P2 Re-transportation route S seat

Claims

1. a transfer unit that transfers a toner image onto a sheet; a fixing unit having a heating unit and fixing the toner image onto the sheet conveyed from the transfer unit; a movable chute located downstream of the transfer unit and upstream of the fixing unit in a first direction, which is a sheet transport direction from the transfer unit to the fixing unit, the movable chute being movable between a first position and a second position, an end portion of which downstream in the first direction is farther from a sheet transport path formed along the first direction than the first position; a re-conveyance chute that guides the sheet that has passed through the fixing unit to the transfer unit, the re-conveyance chute forming a re-conveyance path for the sheet that is conveyed from the fixing unit toward the transfer unit; Equipped with The movable chute is a re-conveying chute positioned on an opposite side of the re-conveying path in a sheet thickness direction of the sheet conveyed along the sheet conveying path; An image forming apparatus having a sheet transport surface that guides a sheet transported along the sheet transport path toward the fixing device, and a first re-transport surface that faces the opposite side of the sheet transport surface in the sheet thickness direction and forms the re-transport path.

2. 2. The image forming apparatus according to claim 1, wherein the first re-conveying surface forms the re-conveying path when the movable chute is located at the second position.

3. a drive source for moving the movable chute; a control unit that controls the operation of the drive source, 3. The image forming apparatus according to claim 2, wherein the control unit controls the drive source to move the movable chute from the first position toward the second position after the leading edge of the sheet being transported along the sheet transport path has passed the fixing unit.

4. a registration roller positioned upstream of the transfer unit in the first direction and configured to correct a skew of the sheet being conveyed toward the transfer unit; The control unit After a leading edge of the sheet being transported along the sheet transport path has passed through the fixing unit, the drive source is controlled to move the movable chute from the first position toward the second position; maintaining the movable chute at the second position while the leading edge of the sheet that has passed through the fixing unit passes through the re-conveying path; 4. The image forming apparatus according to claim 3, wherein the driving source is controlled to move the movable chute from the second position toward the first position after the leading edge of the sheet being transported along the re-transport path has passed the registration roller.

5. a registration roller positioned upstream of the transfer unit in the first direction and configured to correct a skew of the sheet being conveyed toward the transfer unit; The control unit After a leading edge of the sheet being transported along the sheet transport path has passed through the fixing unit, the drive source is controlled to move the movable chute from the first position toward the second position; After the trailing edge of the sheet being transported along the sheet transport path has passed through the transfer unit, the drive source is controlled to move the movable chute from the second position toward the first position; before a leading edge of the sheet that has passed through the fixing unit and is transported along the re-transport path reaches the first re-transport surface of the movable chute, the drive source is controlled to move the movable chute from the first position toward the second position; 4. The image forming apparatus according to claim 3, wherein the driving source is controlled to move the movable chute from the second position toward the first position after the leading edge of the sheet being transported along the re-transport path has passed the registration roller.

6. a solenoid actuator for moving the movable chute; a chute link connected to the solenoid actuator for moving the movable chute from the first position to the second position; 3. The image forming apparatus according to claim 1, wherein the chute link is driven by the solenoid actuator to press the movable chute from the sheet transport surface side, thereby moving the movable chute from the first position to the second position.

7. a guide frame that rotatably supports the movable chute, the guide frame being located upstream of the movable chute in the first direction and having a second re-conveyance surface that forms the re-conveyance path; 3. The image forming apparatus according to claim 1, further comprising: a fixing chute located upstream of the fixing unit and downstream of the movable chute in the first direction, the fixing chute having a third re-conveying surface that forms the re-conveying path.

8. 8. The image forming apparatus according to claim 7, wherein the fixing chute and the movable chute overlap in the sheet transport direction of the sheet transported along the re-transport path.

9. An image forming apparatus as described in claim 7, wherein the upstream end of the first re-conveying surface of the movable chute in a second direction, which is the sheet conveying direction of the sheet conveyed along the re-conveying path toward the transfer section, is located farther from the re-conveying path than the downstream end of the third re-conveying surface of the fixing chute in the second direction.

10. An image forming apparatus as described in claim 7, wherein the upstream end of the second re-conveying surface of the guide frame in a second direction, which is the sheet conveying direction of the sheet conveyed along the re-conveying path toward the transfer section, is located farther from the re-conveying path than the downstream end of the first re-conveying surface of the movable chute in the second direction.

11. 2. An image forming apparatus as described in claim 1, wherein the position of the downstream end of the movable chute in the first direction when the movable chute is located at the second position is located lower than the position of the downstream end of the movable chute in the first direction when the movable chute is located at the first position.

12. The sheet thickness direction is the vertical direction, 12. The image forming apparatus according to claim 11, wherein the movable chute is located above the re-feeding chute and forms an upper surface of the re-feeding path.

13. The chute link presses the movable chute from above, 7. The image forming apparatus according to claim 6, wherein the movable chute is moved from the first position to the second position.

14. a guide frame that rotatably supports the movable chute, is located upstream of the movable chute in the first direction, and has a second re-conveyance surface that faces the re-conveyance path; a fixing chute located upstream of the fixing unit and downstream of the movable chute in the first direction, the fixing chute having a third re-conveying surface facing the re-conveying path; The image forming apparatus according to claim 12 , wherein the second re-conveying surface of the guide frame and the third re-conveying surface of the fixing chute form an upper surface of the re-conveying path.

15. 15. The image forming apparatus according to claim 14, wherein the first re-conveying surface of the movable chute and the third re-conveying surface of the fixing chute overlap each other when viewed from the left-right direction.

16. a sheet metal member supported by the movable chute; a stopper attached to the movable chute from the first re-transport surface side to fix the sheet metal member and the movable chute together; 8. The image forming apparatus according to claim 7, wherein the stopper and the fixing chute overlap each other when viewed in the thickness direction of the sheet.

17. 2. The image forming apparatus according to claim 1, wherein the first re-conveying surface forms the re-conveying path when the movable chute is located at the first position.

18. 18. The image forming apparatus according to claim 17, wherein the movable chute enters the re-feed path when the movable chute is located at the second position.

Images