Image forming apparatus

Abstract

To suppress the occurrence of image defects caused by intrusion of foreign matter.SOLUTION: An image forming apparatus includes: an apparatus main body; a first unit including a photosensitive drum, the first unit including a first wall surface provided at one end portion in a rotation axis direction of the photosensitive drum and being movable between an inside and an outside of the apparatus main body; and a second unit including a belt which can contact with the photosensitive drum, the second unit being movable between the inside and the outside of the apparatus main body. The first unit and the second unit can be coupled to each other and moved integrally to the outside of the apparatus main body. In a state in which the first unit and the second unit are coupled to each other, the first wall surface is located outward of the belt in the rotation axis direction, and a lower end portion of the first wall surface in a vertical direction is located below a contact surface of the belt that comes into contact with the photosensitive drum.SELECTED DRAWING: Figure 11

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Some image forming apparatuses, such as printers, copiers, and multifunction peripherals, have cartridges removably mounted on a tray that moves between the inside and outside of the apparatus body.

[0003] Patent Document 1 discloses an image forming apparatus including a tray to which cartridges are removably attached and a fixing device. The tray is movable to the outside of the main body of the image forming apparatus through a plurality of openings.

[0004] Furthermore, Patent Document 2 discloses an image forming apparatus including a tray to which a cartridge is removably attached, a transfer unit, and a fixing device. In Patent Document 2, the tray and transfer unit are movable from the inside to the outside of the image forming apparatus. Specifically, the fixing device is disposed at one end of the main body of the image forming apparatus, and when the transfer unit moves to the outside of the main body, the transfer unit moves in a direction from the other end of the main body to the one end. On the other hand, when the tray moves to the outside of the main body, the tray moves in a direction from one end of the main body to the other end. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-244018 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-206897 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is a further development of conventional technology, and aims to prevent image defects caused by foreign matter in an image forming apparatus in which the cartridge unit and transfer unit are detachable from the main body of the apparatus. [Means for solving the problem]

[0007] In order to achieve the above object, the image forming apparatus of the present invention comprises: A device body, a first unit including a photosensitive drum, the first unit having a first wall surface provided at one end of the photosensitive drum in a rotation axis direction, and movable between the inside and outside of the device main body; a second unit including a belt capable of coming into contact with the photosensitive drum and movable between the inside and outside of the apparatus main body; Equipped with the first unit and the second unit are connected to each other and can be moved integrally to the outside of the device body, When the first unit and the second unit are connected to each other, the first wall surface is located outside the belt in the direction of the rotation axis, and the lower end of the first wall surface in the vertical direction is located below the contact surface of the belt that contacts the photosensitive drum. [Effects of the Invention]

[0008] According to the present invention, conventional technology is further developed, and it is possible to suppress the occurrence of image defects caused by the inclusion of foreign matter. [Brief explanation of the drawings]

[0009] [Figure 1] A diagram explaining the overall configuration of the printer [Figure 2] Illustration showing the printer with the door open [Figure 3] FIG. 10 shows the printer with the fixing device moved. [Figure 4] Illustration showing the printer with the transfer unit and tray unit pulled out [Figure 5] Illustration showing the printer with the transfer unit pulled out by itself [Figure 6] Diagram explaining the movement of the transfer unit and tray unit [Figure 7] Diagram explaining the movement of the transfer unit and tray unit [Figure 8] FIG. 10 is a diagram showing a connecting member that connects the tray of the tray unit and the transfer unit. [Figure 9] FIG. 10 is a diagram showing a connecting member that connects the tray of the tray unit and the transfer unit. [Figure 10] FIG. 10 is a diagram showing a connecting member that connects the tray of the tray unit and the transfer unit. [Figure 11] A side view of the transfer unit and the tray unit of the first embodiment when they are pulled out [Figure 12] Cross-sectional view of the transfer unit and tray unit of the first embodiment when they are pulled out [Figure 13] A side view of the transfer unit and tray unit of the first modification example when they are pulled out [Figure 14] Cross-sectional view of the transfer unit and tray unit of Modification 1 when they are pulled out [Figure 15] A side view of the transfer unit and tray unit of the second modification example when they are pulled out [Figure 16] Cross-sectional view of the transfer unit and tray unit of Modification 2 when they are pulled out [Figure 17] FIG. 10 is an explanatory diagram of a tray unit according to a third modification example; [Figure 18] A side view of the transfer unit and the tray unit of the second embodiment when they are pulled out [Figure 19] Cross-sectional view of the transfer unit and tray unit of the second embodiment when they are pulled out DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, with reference to the drawings, a detailed description will be given of an illustrative embodiment of the present invention based on examples. The dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the present invention. The components described in the embodiments are merely examples, and are not intended to limit the scope of the present invention to those alone.

[0011] Example 1 [Overall configuration] Fig. 1 is a diagram illustrating the overall configuration of a printer 1 according to this embodiment. The printer 1 as an image forming apparatus will be described using Fig. 1. In this embodiment, the printer 1 is an electrophotographic color laser beam printer that forms an image on a sheet S as a recording material.

[0012] The printer 1 has a device main body 1A, a scanner 2, a control unit 3, and a door 20 that can be opened and closed relative to the device main body 1A. The printer 1 also has a sheet feeding unit 30, a transfer unit 40 as a transfer device, a tray unit 50 as a drawer unit, and a fixing device 80. The part including the device main body 1A and the door 20 can also be called a main frame 100. The main frame 100 includes the exterior of the printer 1.

[0013] The apparatus main body 1A accommodates a scanner 2, a control unit 3, a sheet feeding unit 30, a transfer unit 40, a tray unit 50, and a fixing device 80.

[0014] The sheet feeding section 30 has a stacking tray 31 for stacking sheets S, and a supply roller 32. The stacking tray 31 can be pulled out toward the door 20 to replenish the sheets S. .

[0015] The tray unit 50 as a first unit has a tray 51 as a support member and the cartridges PY, PM, PC, and PK, and the tray 51 has a tray handle 52. The cartridges PY, PM, PC, and PK are removably attached to the tray 51.

[0016] Each of the cartridges PY, PM, PC, and PK is detachably mounted on the tray 51 independently of the others. The cartridges PY, PM, PC, and PK contain yellow (Y), magenta (M), cyan (C), and black (K) toner (developer), respectively. The cartridges PY, PM, PC, and PK have the same configuration except for the toner colors they contain. Therefore, the configuration and operation of only one of the cartridges PY, PM, PC, and PK will be described, and a description of the others will be omitted. Furthermore, when there is no need to distinguish between the cartridges PY, PM, PC, and PK, the cartridges PY, PM, PC, and PK may be simply referred to as cartridges P. The tray unit 50 can be said to have multiple cartridges P and a tray 51 to which the multiple cartridges P are detachably mounted.

[0017] In this embodiment, the tray unit 50 has a plurality of photosensitive drums (image carriers) 61, a plurality of charging rollers 62 (charging members), and a plurality of developing rollers (developer carriers) 71. Specifically, the tray unit 50 has four photosensitive drums 61, four charging rollers 62, and four developing rollers 71. The rotational axis directions of the photosensitive drums 61, the developing rollers 71, and the charging rollers 62 are parallel to each other.

[0018] The portion where a black (K) image is formed is called the black station (first station), the photosensitive drum 61 of the first station is called the first photosensitive drum, the developing roller 71 is called the first developing roller, and the charging roller 62 is called the first charging roller.

[0019] The portion where a cyan (C) image is formed is called a cyan station (second station), the photosensitive drum 61 of the second station is called a second photosensitive drum, the developing roller 71 is called a second developing roller, and the charging roller 62 is called a second charging roller.

[0020] The portion where a magenta (M) image is formed is called the magenta station (third station), the photosensitive drum 61 of the third station is called the third photosensitive drum, the developing roller 71 is called the third developing roller, and the charging roller 62 is called the third charging roller.

[0021] The portion where a yellow (Y) image is formed is called the yellow station (fourth station), the photosensitive drum 61 of the fourth station is called the fourth photosensitive drum, the developing roller 71 is called the fourth developing roller, and the charging roller 62 is called the fourth charging roller.

[0022] The cartridge PK is installed in the black station, the cartridge PC in the cyan station, the cartridge PM in the magenta station, and the cartridge PY in the yellow station. In this embodiment, the cartridge PK is referred to as the first cartridge, the cartridge PC as the second cartridge, the cartridge PM as the third cartridge, and the cartridge PY as the fourth cartridge. Note that the numbers 1, 2, 3, and 4 are used for convenience of explanation.

[0023] The photosensitive drum 61, the charging roller 62, and the developing roller 71 may be provided in either the cartridge P or the tray 51. In this embodiment, the cartridge P has the photosensitive drum 61, the charging roller 62, and the developing roller 71.

[0024] The transfer unit 40, which serves as a second unit, includes a belt 41, a primary transfer roller 42, a cleaning unit 43, a drive roller 46 serving as a first roller for driving the belt 41, and a tension roller (driven roller) 47 serving as a second roller. The printer 1 in this embodiment is also provided with an optical sensor 44 for detecting the toner image transferred to the belt 41. In this embodiment, the belt 41 is disposed below the photosensitive drum 61 and can contact the photosensitive drum 61 so as to form a primary transfer portion between the belt 41 and the photosensitive drum 61. Multiple primary transfer rollers 42 are provided in positions facing the multiple photosensitive drums 61, respectively, with the belt 41 interposed therebetween. The printer 1 also includes a secondary transfer roller 45 that contacts the belt 41 so as to form a secondary transfer portion. The secondary transfer portion is formed between the belt 41 and the secondary transfer roller 45. The rotational axes of the primary transfer roller 42, drive roller 46, tension roller 47, and secondary transfer roller 45 are parallel to each other. A pair of registration rollers 4 is disposed in front of the secondary transfer portion.

[0025] The fixing device 80 has a fixing section 81 and a flapper 5. When an image forming operation is performed on the sheet S, the fixing device 80 is in the use position. The fixing device 80 is stored inside (inside) the apparatus main body 1A when in the use position. The fixing device 80 is also configured to heat the sheet S when in the use position. In this embodiment, the fixing section 81 includes a heating section (heating roller) including a heater, and a pressure section (pressure roller).

[0026] The movement of the transfer unit 40 and the tray unit 50 will be described using Figures 1, 2, 3, 4, and 5. Figure 2 is a diagram showing the printer 1 with the door 20 open. Figure 3 is a diagram showing the printer 1 with the fixing device 80 moved. Figure 4 is a diagram showing the printer 1 with the transfer unit 40 and the tray unit 50 pulled out. Figure 5 is a diagram showing the printer 1 with the transfer unit 40 pulled out by itself.

[0027] The transfer unit 40 and the tray unit 50 are movable from the inside to the outside of the device main body 1A. In the horizontal direction H, the device main body 1A has a first end 1b1 provided with an opening 1A1 and a second end 1b2 opposite the first end 1b1. The tray unit 50 is movable through the opening 1A1 to a first inner position inside the device main body 1A and a first outer position outside the device main body 1A. The transfer unit 40 is movable through the opening 1A1 to a second inner position inside the device main body 1A and a second outer position outside the device main body 1A. The opening 1A1 may include an opening through which the tray unit 50 passes and an opening through which the transfer unit 40 passes. Note that when the transfer unit 40 moves from the second inner position to the second outer position, at least the belt 41 is moved, and at least a portion of the belt 41 protrudes from the device main body 1A toward the outside of the device main body 1A.

[0028] The direction in which the tray unit 50 moves from the first inner position to the first outer position is called the tray removal direction Dd1 (first removal direction), and the direction opposite to the tray removal direction Dd1 is called the tray attachment direction Da1 (first attachment direction). The tray removal direction Dd1 can be said to be the direction from the second end 1b2 toward the first end 1b1.

[0029] The direction in which the transfer unit 40 moves from the second inner position to the second outer position is called the transfer take-out direction Dd2 (second take-out direction), and the opposite direction to the transfer take-out direction Dd2 is called the transfer attachment direction Da2 (second attachment direction). The transfer take-out direction Dd2 can be said to be the direction from the second end 1b2 toward the first end 1b1.

[0030] The tray removal direction Dd1 and the tray attachment direction Da1 are directions intersecting (preferably perpendicular to) the rotation axis direction of the photosensitive drum 61. The transfer removal direction Dd2 and the transfer attachment direction Da2 are directions intersecting (preferably perpendicular to) the rotation axis direction of the drive roller 46. The rotation axis direction of the drive roller 46 is parallel to the rotation axis direction of the photosensitive drum 61.

[0031] In the horizontal direction H, a fixing device 80 is disposed on one end side of the apparatus main body 1A (the side where the first end 1b1 is disposed).

[0032] Door 20 attached to apparatus main body 1A is movable between a closed position and an open position. As shown in Fig. 1, when door 20 is in the closed position (door 20 closed state), door 20 covers opening 1A1. As shown in Fig. 2, when door 20 is in the open position (door 20 open state), opening 1A1 is exposed.

[0033] 1, when the door 20 is in the closed position, the door 20 covers the fixing device 80 attached to the apparatus main body 1A. More specifically, when the door 20 is in the closed position, the upper cover portion 20b of the door 20 is located above the fixing device 80. The upper cover portion 20b of the door 20 functions as a part of the exterior.

[0034] The door 20 can move between an open position and a closed position while the fixing device 80 is supported by the apparatus main body 1A. In other words, the door 20 moves from the closed position to the open position so as to move away from the fixing device supported by the apparatus main body 1A. Therefore, as shown in FIG. 2, when the door 20 is in the open position, the door 20 is away from the fixing device 80 supported by the apparatus main body 1A.

[0035] As will be described later, the fixing device 80 can be moved from the state shown in Fig. 2 to the state shown in Fig. 3 so that the opening 1A1 is widely exposed. With the door 20 and the fixing device 80 moved (Fig. 3), the transfer unit 40 and the tray unit 50 can be moved from the inside to the outside of the apparatus main body 1A through the opening 1A1, and after the movement, the state shown in Fig. 4 is obtained.

[0036] With the tray unit 50 moved to the outside of the apparatus main body 1A (FIG. 4), it is possible to remove the cartridges PY, PM, PC, and PK from the tray 51 and to attach the cartridges PY, PM, PC, and PK to the tray 51. This allows the cartridges PY, PM, PC, and PK to be replaced with new cartridges PY, PM, PC, and PK. In this embodiment, the cartridge P is detachable from the tray 51 in a direction intersecting (preferably perpendicular to) the rotation axis of the photosensitive drum 61.

[0037] The cartridges PY, PM, PC, and PK are removed from the tray 51 by moving in a direction away from the transfer unit 40 relative to the tray 51. In other words, the cartridges PY, PM, PC, and PK are removed from the tray 51 by moving toward the opposite side of the transfer unit 40 relative to the tray 51. In this embodiment, the transfer unit 40 is disposed below the tray unit 50. Therefore, the cartridges PY, PM, PC, and PK are removed from the tray 51 by moving upward relative to the tray 51.

[0038] Furthermore, the transfer unit 40 can be removed from the apparatus main body 1A independently of the tray unit 50, and can be replaced with a new transfer unit 40.

[0039] [Image formation operation] 1, the image forming operation of the printer 1 will be described. The control unit 3 of the printer 1 starts the image forming operation on the sheet S based on an image signal received from an external host device 400. The external host device 400 is, for example, a personal computer, an image reader, or a facsimile machine.

[0040] When an image is formed on the sheet S, the fixing device 80 is located at the use position, the tray unit 50 is located at the first inner position, the transfer unit 40 is located at the second inner position, and the door 20 is located at the closed position. With the transfer unit 40 located at the second inner position, the belt 41 can contact the photosensitive drum 61. At this time, the tray unit 50 is located above the transfer unit 40.

[0041] A charging voltage is applied to the charging roller 62, and the photosensitive drum 61 rotates. A laser corresponding to image information is irradiated from the scanner 2 onto the photosensitive drum 61, and the surface of the photosensitive drum 61 charged by the charging roller 62 is exposed to the laser. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 61.

[0042] The developing roller 71 carries toner. A developing voltage is applied to the developing roller 71, and the electrostatic latent image formed on the photosensitive drum 61 is developed with toner supplied from the developing roller 71, forming a toner image on the surface of the photosensitive drum 61. In this embodiment, the developing roller 71 develops the electrostatic latent image while in contact with the photosensitive drum 61, but the developing roller 71 may also develop the electrostatic latent image while there is a gap between the developing roller 71 and the photosensitive drum 61.

[0043] When a full-color image is formed, a toner image of each color is formed on each photosensitive drum 61 .

[0044] In this embodiment, when the tray unit 50 is in the first inner position, the developing roller 71 is movable between a contact position where it contacts the photosensitive drum 61 and a spaced position where it is spaced from the photosensitive drum 61. Specifically, a switching device provided in the apparatus main body 1A switches between a state where the developing roller 71 is in the contact position and a state where the developing roller 71 is in the spaced position. This allows the developing roller 71 to be spaced from the photosensitive drum 61 when no image forming operation is being performed.

[0045] The printer 1 can perform monochrome printing when the developing roller 71 corresponding to the cartridge PK is in contact with the photosensitive drum 61 and the developing rollers 71 corresponding to the cartridges PY, PM, and PC are spaced apart from the photosensitive drum 61. The printer 1 can also perform full-color printing when the photosensitive drums 61 corresponding to the cartridges PY, PM, PC, and PK are in contact with the belt 41.

[0046] The toner images formed on each photosensitive drum 61 are transferred onto the belt 41 by the primary transfer roller 42 at the primary transfer section, and then transported toward the secondary transfer section formed by the belt 41 and the secondary transfer roller 45.

[0047] Meanwhile, the apparatus main body 1A is formed with a conveying path (first route, first conveying path) 1c through which the sheet S passes toward the fixing device 80. The door 20 is also formed with a double-sided conveying path (second route, second conveying path) 20a through which the sheet S passes after passing through the fixing device 80. The door 20 covers the conveying path 1c in the closed state. When the door 20 is opened, the conveying path 1c and the double-sided conveying path 20a are exposed (FIG. 2).

[0048] In the sheet feeding section 30, one sheet S is separated and fed from the sheets S stacked on the stacking tray 31 by the supply roller 32 at a predetermined timing, and is transported through the transport path 1c toward the secondary transfer section and the fixing device 80.

[0049] In the secondary transfer portion, the toner image is transferred from the belt 41 to the sheet S. The toner that has not been transferred to the sheet S is removed from the belt 41 by a cleaning blade (cleaning member) 43A provided in the cleaning portion 43.

[0050] The sheet S onto which the toner image has been transferred in the secondary transfer unit is transported towards a fixing device 80. In the fixing device 80, the sheet S is heated and pressurized in a fixing unit 81, and the toner image is fixed onto the sheet S. The sheet S onto which the toner image has been fixed is transported towards a flapper 5 serving as a path switching unit.

[0051] The flapper 5 is movable between a paper discharge position where the sheet S that has passed through the fixing device 80 is guided toward a paper discharge path 1d and a reversing position where the sheet S is guided toward a reversing path 1e.

[0052] When single-sided printing is performed, in which an image is formed on one side of the sheet S, the sheet S is guided to the paper discharge path 1d by the flapper 5 and discharged onto a discharge tray 1f formed on the top of the apparatus main body 1A.

[0053] On the other hand, when double-sided printing is performed, in which images are printed on both sides of the sheet S, the sheet S is guided to the reversing path 1e by the flapper 5. After the sheet S is guided to the reversing path 1e, the conveying direction of the sheet S is reversed, and the sheet S is conveyed toward the secondary transfer unit through the double-sided conveying path 20a formed in the door 20. After the toner image is transferred to the back side of the sheet S in the secondary transfer unit, the sheet S passes through the fixing device 80, is guided by the flapper 5 to the paper discharge path 1d, and is discharged onto the discharge tray 1f of the apparatus main body 1A.

[0054] [Removing the tray unit and transfer unit and locating the fixing unit] 1, 2, 3, 4 and 5, the removal of the tray unit 50 and the transfer unit 40 from the apparatus main body 1A and the arrangement of the fixing device 80 will be described.

[0055] As described above, the fixing device 80 of the printer 1 is disposed at one end of the device main body 1A in the horizontal direction H. The transfer unit 40 and the tray unit 50 move from one end of the device main body 1A to the outside of the device main body 1A through the opening 1A1.

[0056] In other words, in the horizontal direction H, the fixing device 80 is closer to the first end 1b1 than to the second end 1b2. That is, in the horizontal direction H, the distance between the fixing device 80 and the first end 1b1 is shorter than the distance between the fixing device 80 and the second end 1b2. The fixing device 80 is disposed at a position closer to the first end 1b1 than to the center of the device body 1A in the horizontal direction H, and it can be said that the distance between the first end 1b1 and the fixing device 80 in the horizontal direction H is shorter than the distance between the first end 1b1 and the center of the device body 1A.

[0057] Furthermore, as described above, when the tray unit 50 moves from the first inner position to the first outer position, the movement direction of the tray unit 50 is a direction intersecting the rotation axis of the photosensitive drum 61. At this time, the tray unit 50 moves away from the second end 1b2.

[0058] As described above, when the transfer unit 40 moves from the second inner position to the second outer position, the movement direction of the transfer unit 40 is a direction intersecting the rotation axis of the drive roller 46. At this time, the transfer unit 40 moves away from the second end 1b2.

[0059] As described above, the door 20 of this embodiment covers the opening 1A1 in the closed state and also covers at least a portion of the conveying path 1c for the sheet S. The door 20 also has a double-sided conveying path 20a. If a jam occurs with the sheet S, the user of the printer 1 can remove the sheet S from one end of the device main body 1A and resolve the jam. Specifically, the user can move the door 20 to the open position to access the inside of the device main body 1A and remove the sheet S. Furthermore, if a portion of the sheet S that has passed through the fixing device 80 is exposed to the outside of the device main body 1A, the user can pull the sheet S from the outside of the device main body 1A without opening the door 20. Sheet S can be removed.

[0060] Furthermore, the user of the printer 1 can move the transfer unit 40 and the tray unit 50 from one end of the device main body 1A to the outside of the device main body 1A to check the status of the transfer unit 40 and the cartridge P, perform maintenance, replacement, and other tasks.

[0061] That is, in the printer 1, the fixing device 80 is disposed at one end of the device main body 1A, and the transfer unit 40 and tray unit 50 can be moved in and out of the device main body 1A through that end. As a result, the user can clear jams, access the fixing device 80, and operate the transfer unit 40 and tray unit 50 from one direction.

[0062] In this embodiment, the door 20 side of the printer 1 is defined as the front. Therefore, it is sufficient to secure space for performing tasks such as clearing jams and operating the transfer unit 40 and tray unit 50 from the front of the printer 1. On the other hand, it is not necessary to secure space for performing these tasks from the left, right, back, or top of the printer 1. Therefore, the printer 1 can be installed in a small space.

[0063] If the transfer unit 40 or the tray unit 50 is pulled out from the other end of the device main body 1A, the user will need to access both ends of the device main body 1A to clear the jam and pull out the transfer unit 40 or the tray unit 50. Also, if one of the transfer unit 40 and the tray unit 50 is pulled out from one end of the device main body 1A and the other of the transfer unit 40 and the tray unit 50 is pulled out from the other end, the user will need to access both ends of the device main body 1A. This requires space for accessing both the front and rear of the device main body 1A, increasing the area required to install the printer 1. However, in this embodiment, the transfer unit 40 and the tray unit 50 are operated from the front (door 20 side) of the device main body 1A as described above, allowing the printer 1 to be installed in a smaller space.

[0064] Furthermore, in this embodiment, the sheets S can be replenished from one end of the device main body 1A. Therefore, it is only necessary to secure space for replenishing the sheets S from the front of the printer 1, and the printer 1 can be installed in a space-saving manner.

[0065] [Relationship between the tray unit and the fixing unit] The relationship between the tray unit 50 and the fixing device 80 will be described with reference to Figures 1, 2, 3, 4, 6, and 7. Figures 6 and 7 are diagrams for explaining the movement of the transfer unit 40 and the tray unit 50.

[0066] The tray unit 50 passes through a predetermined space when moving between a first inner position where an image forming operation is performed on the sheet S and a first outer position where replacement of the cartridge P is permitted. In this way, the space through which the tray unit 50 passes when moving from the first inner position to the first outer position is called the first space (movement space of the tray unit 50). The first space can also be called the path or trajectory (first movement path, first movement trajectory) through which the tray unit 50 passes when moving from the first inner position to the first outer position.

[0067] The transfer unit 40 passes through a predetermined space when moving between the second inner position where an image formation operation is performed on the sheet S and the second outer position. In this way, the space through which the transfer unit 40 passes when moving from the second inner position to the second outer position is called the second space (movement space of the transfer unit 40). The second space can also be called the path or trajectory (second movement path, second movement trajectory) through which the transfer unit 40 passes when moving from the second inner position to the second outer position.

[0068] The position (use position) of the fixing device 80 when an image forming operation is performed on the sheet S, and the first and second spaces have the following relationship.

[0069] 6 and 7, at least a portion of the fixing device 80 in the use position overlaps with the first space. In other words, when the fixing device 80 is in the use position, at least a portion of the fixing device 80 is inside the first space.

[0070] In this embodiment, at least a portion of the fixing device 80 overlaps with the space through which the cartridge P passes when the tray unit 50 moves from the first inner position to the first outer position, but it may also be arranged so as to overlap with the space through which the tray 51 passes.

[0071] This allows the apparatus main body 1A to be made smaller in size than in a configuration in which the fixing device 80 in the use position is located outside the first space.

[0072] 6, in this embodiment, when the door 20 is in the closed state, at least a portion of the double-sided conveying path 20a overlaps with the first space. That is, when the door 20 is in the closed state, at least a portion of the double-sided conveying path 20a is inside the first space.

[0073] As described above, at least a portion of the fixing device 80 in the use position is located inside the first space. Therefore, when the fixing device 80 is in the use position, movement of the tray unit 50 from the first inner position to the first outer position is restricted. On the other hand, the fixing device 80 is configured to be retractable from the use position. When the fixing device 80 is retracted from the use position, movement of the tray unit 50 from the first inner position to the first outer position is permitted. When the tray unit 50 moves from the first inner position to the first outer position, the tray unit 50 passes below the fixing device 80. Note that the fixing device 80 is located outside the second space in both the use position and the retracted position. Therefore, when the fixing device 80 is in the use position and when the fixing device 80 is in the retracted position, the transfer unit 40 can move from the second inner position to the second outer position. When the transfer unit 40 moves from the second inner position to the second outer position, the transfer unit 40 passes below the fixing device 80.

[0074] The fixing device 80 has a fixing frame 80a that supports a fixing portion 81. When the fixing device 80 retreats from the use position, the fixing frame 80a displaces relative to the apparatus main body 1A while supporting the fixing portion 81.

[0075] When the tray unit 50 is pulled out to the outside of the apparatus main body 1A, the door 20 is first moved to the open position as shown in Fig. 2. In this embodiment, the door 20 can be moved to the open position and the closed position while the fixing device 80 is positioned in the use position. Then, while the door 20 is in the open position, the fixing device 80 is moved from the use position to the retracted position so as to move outside the first space as shown in Fig. 3.

[0076] In the printer 1 of this embodiment, the fixing device 80 is movable between a use position and a retracted position when attached to the device main body 1A. In this embodiment, when the fixing device 80 is in the retracted position, the entire fixing device 80 is located outside the first space.

[0077] The fixing device 80 is lifted from the use position and moved to the retracted position above the use position. In other words, the fixing device 80 moves to the retracted position which is higher than the use position. As shown in FIG. 7, when the fixing device 80 is in the retracted position, at least a part of the fixing device 80 is in a position protruding from the device main body 1A toward the outside of the device main body 1A. Furthermore, the fixing When the fixing device 80 is in the retracted position, the position of at least a portion of the fixing device 80 is higher than the position of the upper cover portion 20b of the door 20 in the closed position. This allows the size of the printer 1 to be kept small in the vertical direction V when the fixing device 80 is in the use position, while ensuring space for movement of the tray unit 50 by moving the fixing device 80 to the retracted position. Note that when the fixing device 80 is in the retracted position, the door 20 is restricted from taking the closed position.

[0078] Specifically, the printer 1 has a connecting member (fixing connecting member, fixing link, arm) 85 movably connected to the apparatus main body 1A. The fixing device 80 is connected to the apparatus main body 1A via the connecting member 85.

[0079] The connecting member 85 is rotatable around a rotation center 85A, and when the tray unit 50 is pulled out to the outside of the device main body 1A, the connecting member 85 moves to the outside of the first space. The fixing device 80 is rotatably connected to one end of the connecting member 85, and the other end of the connecting member 85 is rotatably connected to the device main body 1A around the rotation center 85A. The fixing device 80, while supported by the connecting member 85 (connected to the device main body 1A via the connecting member 85), is movable from the use position to the retracted position and from the retracted position to the use position. The connecting member 85 is configured to be movable (swingable) relative to the device main body 1A and the fixing device 80. In other words, the fixing device 80 is connected to the device main body 1A via the connecting member 85. As a result, the movement amount of the fixing device 80 when moving between the retracted position and the use position can be increased compared to a configuration in which the fixing device 80 is directly connected to the device main body 1A.

[0080] 7, when the tray unit 50 moves from the first inner position to the first outer position, the angle between the movement direction of the tray unit 50 and the horizontal direction H is smaller than the angle between the movement direction of the tray unit 50 and the vertical direction V. Furthermore, when the fixing device 80 moves from the use position to the retracted position, the movement amount of the fixing device 80 in the vertical direction V is larger than the movement amount of the fixing device 80 in the horizontal direction H. In other words, when the fixing device 80 moves from the use position to the retracted position, the movement amount of the fixing device 80 in the direction perpendicular to the movement direction of the tray unit 50 is larger than the movement amount of the fixing device 80 in the direction parallel to the movement direction of the tray unit 50.

[0081] Furthermore, fixing device 80 may be configured to move between the use position and the retracted position while attached to apparatus main body 1A via a guide fixed to apparatus main body 1A. In this case, the shape of the guide is arbitrary.

[0082] However, the method for moving the fixing device 80 to the outside of the first space is not limited to this. For example, the fixing device 80 may be detachable from the apparatus main body 1A so as to retreat from the use position, and moved to the outside of the first space. That is, the fixing device 80 may be positioned outside the first space by separating it from the apparatus main body 1A and the door 20 (separating it from the main frame 100). Alternatively, the fixing device 80 may be connected to the door 20, and the fixing device 80 may be moved to the outside of the first space by opening the door 20.

[0083] [Relationship between the tray unit and the transfer unit] The relationship between the tray unit 50 and the transfer unit 40 will be described with reference to FIGS. 1, 2, 3, 4, 5, 6, and 7. FIG.

[0084] As shown in FIG. 3, with the fixing device 80 positioned outside the first space, the user grasps the tray handle 52 and moves the tray unit 50 toward the outside of the apparatus main body 1A.

[0085] As shown in FIGS. 6 and 7, the position of the transfer unit 40 when an image forming operation is performed on the sheet S and the first space have the following relationship.

[0086] That is, when an image forming operation is performed on the sheet S, the transfer unit 40 is in the second inner position. As shown in Figures 6 and 7, at least a portion of the transfer unit 40 in the second inner position overlaps with the first space. In other words, when the transfer unit 40 is in the second inner position, at least a portion of the transfer unit 40 is inside the first space.

[0087] In this embodiment, at least a portion of the transfer unit 40 overlaps with the space through which the tray 51 passes when the tray unit 50 moves from the first inner position to the first outer position, but it may also be positioned so as to overlap with the space through which the cartridge P passes.

[0088] This allows the apparatus main body 1A to be made smaller in size than in a configuration in which the transfer unit 40 at the second inner position is positioned outside the first space.

[0089] In the printer 1 of this embodiment, the part of the transfer unit 40 that overlaps with the first space is the cleaning section 43 that houses the cleaning member 43A. However, other parts of the transfer unit 40 may overlap with the first space. In this embodiment, the cleaning member 43A of the transfer unit 40 that is in the second inner position also overlaps with the first space.

[0090] It can be said that the tray unit 50 and the transfer unit 40 satisfy the following relationship: With the tray unit 50 in the first inner position and the transfer unit 40 in the second inner position, in the movement direction in which the tray unit 50 moves from the first inner position to the first outer position, a part of the transfer unit 40 (cleaning unit 43) is downstream of the tray unit 50. In addition, in the vertical direction V, the area (range) in which the part of the transfer unit 40 (cleaning unit 43) is arranged at least partially overlaps with the area (range) in which the tray unit 50 is arranged.

[0091] In this embodiment, when the door 20 is in the closed state, at least a part of the duplex conveying path 20a overlaps with the second space through which the transfer unit 40 passes when moving from the second inner position to the second outer position. In other words, when the door 20 is in the closed state, at least a part of the duplex conveying path 20a is inside the second space.

[0092] As described above, when the transfer unit 40 is in the second inner position, at least a portion of the transfer unit 40 is located inside the first space. Therefore, in this embodiment, when the user moves the tray unit 50 from the first inner position to the first outer position relative to the device main body 1A, the transfer unit 40 also moves from the second inner position to the second outer position relative to the device main body 1A. In other words, when the transfer unit 40 and the tray unit 50 are integrated, the tray unit moves from the first inner position, which is inside the device main body, to the first outer position, which is outside the device main body. At that time, the transfer unit 40 also moves from the second inner position, which is inside the device main body, to the second outer position, which is outside the device main body.

[0093] By moving the tray unit 50 and the transfer unit 40 together, the photosensitive drum 61 is prevented from being exposed when the tray unit 50 moves to the first outer position, and scratches and dirt on the photosensitive drum 61 can be prevented.

[0094] As shown in FIG. 7, when the door 20 is open, the tray unit 50 is in the first outer position, and the transfer unit 40 is in the second outer position, the transfer unit 40 supports the tray unit 50 from below the tray unit 50. Furthermore, in this embodiment, the door 20 supports the transfer unit 40. In other words, the transfer unit 40 supported by the door 20 supports the tray unit 50. In this state, the door 20 supports the tray unit 50 via the transfer unit 40. It can also be said that he supports Ray Unit 50.

[0095] The configuration for integrally moving the tray unit 50 and the transfer unit 40 will be described with reference to Figures 8, 9, and 10. Figures 8, 9, and 10 are diagrams illustrating a connecting member (lever, stopper, locking member) 53 that connects the tray 51 of the tray unit 50 and the transfer unit 40.

[0096] The printer 1 according to this embodiment has a locking member 53. In this embodiment, the locking member 53 is provided on the tray 51 of the tray unit 50. The locking member 53 has a transfer locking portion 53A and is rotatable around a rotation center 53B.

[0097] The tray 51 has a transfer connection portion 51A. The transfer unit 40 has a transfer frame 48 that supports a drive roller 46, a tension roller 47, and a primary transfer roller 42. The transfer frame 48 has a tray connection groove 48A and a lock connection portion 48B.

[0098] The locking member 53 rotates around the rotation center 53B, whereby the transfer locking portion 53A engages with the lock connecting portion 48B, and the locking member 53 can move to a connecting position where the transfer unit 40 and the tray unit 50 are connected, and to a release position where the transfer unit 40 is retracted from the connecting position.

[0099] By engaging the transfer connecting portion 51A with the tray connecting groove 48A, the tray unit 50 is restricted from moving in the tray removal direction Dd1 and in a direction perpendicular to the tray removal direction Dd1 relative to the transfer unit 40. On the other hand, the transfer unit 40 is restricted from moving in the transfer attachment direction Da2 and in a direction perpendicular to the transfer attachment direction Da2 relative to the tray unit 50.

[0100] Similar structures are provided at four locations in total: near both ends of the tension roller 47 in the direction of its rotation axis, and near both ends of the drive roller 46 in the direction of its rotation axis.

[0101] When the transfer lock portion 53A of the lock member 53 in the coupled position engages with the lock coupling portion 48B, the tray unit 50 is restricted from moving in the tray attachment direction Da1 relative to the transfer unit 40. On the other hand, the transfer unit 40 is restricted from moving in the transfer removal direction Dd2 relative to the tray unit 50.

[0102] The locking member 53 and the locking connecting portion 48B may also be provided at both ends of the transfer unit 40 in the direction of the rotation axis of the tension roller 47.

[0103] In other words, when the transfer connecting portion 51A engages with the tray connecting groove 48A and the locking member 53 in the connecting position engages with the lock connecting portion 48B, the transfer unit 40 and the tray unit 50 are restricted from moving relative to each other. Note that in this state, there may be play between the transfer unit 40 and the tray unit 50.

[0104] In other words, the transfer connecting portion 51A and the locking member 53 function as a tray-side connecting device, and the tray connecting groove 48A and the lock connecting portion 48B function as a transfer-side connecting device. By connecting the tray-side connecting device and the transfer-side connecting device, the tray unit 50 and the transfer unit 40 are connected to each other, and the tray unit 50 and the transfer unit 40 move integrally.

[0105] 10, the apparatus main body 1A has an unlocking section 1B. When the tray unit 50 is in the first inner position and the transfer unit 40 is in the second inner position, The lock member 53 is in contact with the lock release portion 1B and is in the release position. In this state, the transfer lock portion 53A is separated from the lock connection portion 48B.

[0106] When the tray unit 50 is moved in the tray removal direction Dd1 with the locking member 53 in the release position, the transfer unit 40 is pushed in the transfer removal direction Dd2 by the transfer coupling portion 51A. As a result, the transfer unit 40 is also moved integrally with the tray unit 50 in the transfer removal direction Dd2. When the tray unit 50 moves a predetermined distance in the tray removal direction Dd1, the locking member 53 separates from the locking member 1B, moves to the coupled position, and engages with the lock coupling portion 48B. With the locking member 53 in the coupled position and engaged with the lock coupling portion 48B, the tray unit 50 is moved to the first outer position, and the transfer unit 40 is moved to the second outer position. In other words, the tray unit 50 and the transfer unit 40 are coupled to each other and move integrally to the outside of the apparatus main body 1A.

[0107] When the tray unit 50 is moved in the tray attachment direction Da1 with the locking member 53 engaged with the lock connecting portion 48B, the transfer unit 40 is pushed in the transfer attachment direction Da2 by the locking member 53. As a result, the transfer unit 40 is also moved integrally with the tray unit 50 in the transfer attachment direction Da2.

[0108] When the transfer unit 40 is moved in the transfer attachment direction Da2 with the lock member 53 engaged with the lock connecting portion 48B, the transfer unit 40 pushes the transfer connecting portion 51A, and the tray unit 50 is pushed in the tray attachment direction Da1. As a result, the tray unit 50 is also moved integrally with the transfer unit 40 in the tray attachment direction Da1.

[0109] When the tray unit 50 and the transfer unit 40 are moved together toward the inside of the apparatus main body 1A, the lock member 53 is moved to the unlocked position by the lock release section 1B. In this state, even if the tray unit 50 is moved in the tray attachment direction Da1, the transfer unit 40 does not move. Therefore, in the process of closing the door 20, the force of the secondary transfer roller 45 contacting the transfer unit 40 pushes the transfer unit 40 toward the transfer attachment direction Da2 and to the back of the apparatus main body 1A (to the second inner position). In other words, the door 20 can push the transfer unit 40 so that the transfer unit 40 is located at the second inner position. Alternatively, the door 20 may push the tray unit 50 so that the tray unit 50 is located at the first inner position.

[0110] On the other hand, with the locking member 53 in the release position and the tray unit 50 in the first inner position, the transfer unit 40 is moved in the transfer removal direction Dd2. The transfer unit 40 can be moved from the second inner position to the second outer position independently of the tray unit 50. In the printer 1 of this embodiment, as shown in FIG. 5, with the tray unit 50 positioned inside the device main body 1A (first inner position), the transfer unit 40 can be moved to the outside of the device main body 1A (second outer position). The transfer unit 40 is removable from the device main body 1A and can be replaced with a new transfer unit 40.

[0111] In this embodiment, when the tray unit 50 is in the first inner position, the tray unit 50 is positioned relative to the device main body 1A independently of the transfer unit 40. Furthermore, when the transfer unit 40 is in the second inner position, the transfer unit 40 is positioned relative to the device main body 1A independently of the tray unit 50. This is because priority is given to accurately positioning each of the transfer unit 40 and the tray unit 50 relative to the device main body 1A. Therefore, when the tray unit 50 is in the first inner position and the transfer unit 40 is in the second inner position, a slight clearance is provided between the tray connecting groove 48A and the transfer connecting portion 51A.

[0112] The clearance between the tray connecting groove 48A and the transfer connecting portion 51A may be eliminated so that the tray unit 50 and the transfer unit 40 can be positioned relative to each other when the tray unit 50 is in the first inner position and the transfer unit 40 is in the second inner position. In this case, the transfer unit 40 and the tray unit 50 can be positioned relative to each other with high precision.

[0113] [Moving the tray unit and transfer unit] As shown in FIGS. 1, 6 and 7, the tray unit 50 and the transfer unit 40 are inclined with respect to the horizontal direction H when they are attached to the apparatus main body 1A.

[0114] More specifically, when the tray unit 50 is in the first inner position, the rotation axis of the photosensitive drum 61 closer to the first end 1b1 is positioned higher in the vertical direction V than the rotation axis of the photosensitive drum 61 farther from the first end 1b1.

[0115] That is, when the tray unit 50 is in the first inner position, the second photosensitive drum is closer to the first end 1b1 than the first photosensitive drum, and the rotation axis of the second photosensitive drum is located higher in the vertical direction V than the rotation axis of the first photosensitive drum. Similarly, the third photosensitive drum is closer to the first end 1b1 than the second photosensitive drum, and the rotation axis of the third photosensitive drum is located higher in the vertical direction V than the rotation axis of the second photosensitive drum. The fourth photosensitive drum is closer to the first end 1b1 than the third photosensitive drum, and the rotation axis of the fourth photosensitive drum is located higher in the vertical direction V than the rotation axis of the third photosensitive drum.

[0116] Here, a straight line LD is defined as a line connecting the centers of the photosensitive drums 61. In this embodiment, when the tray unit 50 is in the first inner position, the straight line LD is inclined upward with respect to the horizontal direction H from the side farther from the first end 1b1 to the side closer to the first end 1b1.

[0117] Furthermore, the contact surfaces of the belt 41 that contact the first, second, third, and fourth photosensitive drums are inclined upward from the side farther from the first end 1b1 to the side closer to the first end 1b1.

[0118] When the tray unit 50 moves from the first inner position to the first outer position, the tray unit 50 moves in a direction inclined with respect to the horizontal direction H (in this embodiment, a direction inclined upward with respect to the horizontal direction H). In other words, when the tray unit 50 moves from the first inner position to the first outer position, the tray unit 50 moves diagonally upward.

[0119] When the tray unit 50 moves from the first inner position to the first outer position, the movement direction of the tray unit 50 changes so that it moves diagonally upward and then downward. The movement direction of the tray unit 50 may include a direction parallel to the horizontal direction H or a diagonal downward direction relative to the horizontal direction H.

[0120] The angle between the straight line LD and the horizontal direction H is smaller when the tray unit 50 is in the first outer position than when the tray unit 50 is in the first inner position. In this embodiment, when the tray unit 50 is in the first outer position, the straight line LD and the horizontal direction H are parallel, but the straight line LD may be inclined downward or upward with respect to the horizontal direction H.

[0121] Similarly, when the transfer unit 40 moves from the second inner position to the second outer position, the movement direction of the transfer unit 40 also changes so that it moves diagonally upward and then downward. The movement direction of the transfer unit 40 may include a direction parallel to the horizontal direction H or a diagonal downward direction relative to the horizontal direction H.

[0122] The angle between the contact surface of the belt 41 and the horizontal direction H is The difference is smaller when the transfer unit 40 is in the second outer position than when the transfer unit 40 is in the second outer position. In this embodiment, when the transfer unit 40 is in the second outer position, the contact surface of the belt 41 is parallel to the horizontal direction H, but the contact surface of the belt 41 may be inclined downward or upward with respect to the horizontal direction H.

[0123] When the tray unit 50 is moved from the first outer position to the first inner position, the tray unit 50 moves in the horizontal direction H, and then moves diagonally downward from the middle. When the transfer unit 40 is moved from the second outer position to the second inner position, the transfer unit 40 moves in the horizontal direction H, and then moves diagonally downward from the middle. With this configuration, the weights of the tray unit 50 and the transfer unit 40 can be used when inserting the tray unit 50 and the transfer unit 40 into the apparatus main body 1A.

[0124] [Positional relationship between the tray unit side wall and the belt side edge] The positional relationship between the side wall of the tray unit and the side edge of the belt will be described with reference to FIGS.

[0125] FIG. 11(a) is a side view of the transfer unit 40 when it is in the second outer position. Here, the side view refers to a view from a direction perpendicular to the horizontal direction H and the vertical direction V (hereinafter referred to as the left-right direction D), and is a view of the transfer unit 40 seen from the side. The left-right direction D is parallel to the rotational axis direction of the photosensitive drum 61. Note that in FIG. 11(a), dotted lines are used to indicate the relative positions of components and to represent the shapes of some components that are not visible. This method of depicting figures is also used in the following embodiments. The transfer unit 40 includes a transfer frame side wall 48C as a second side wall. Hereinafter, the portion of the upper end of the transfer frame side wall 48C that is located in the area where the primary transfer roller 42 is located in the direction in which the belt 41 moves while contacting the photosensitive drum 61 will be simply referred to as the upper end of the transfer frame side wall 48C. In FIG. 11(a), a dash-dotted line LC indicates the position of the upper end of the transfer frame side wall 48C. A portion of the side edge of the belt 41 is located above the upper edge of the transfer frame side wall 48 C. A portion of the side edge of the belt 41 is exposed from the transfer frame side wall 48 C. Of the side edge of the belt 41, the portion located above the upper edge of the transfer frame side wall 48 C is hereinafter referred to as the upper side edge.

[0126] FIG. 11B is a side view of the integrated tray unit 50 and transfer unit 40, respectively, in the first outer position and the second outer position. As shown in FIG. 11B, the tray unit 50 has a tray sidewall 51B as a first wall surface. More specifically, the tray 51 has the tray sidewall 51B. The tray sidewall 51B is provided at each end of the tray unit 50 in the direction of the rotation axis of the photosensitive drum 61 (one end and the other end of the tray unit 50). The tray sidewall 51B is disposed so as to overlap with a portion of the multiple primary transfer rollers 42 and cover the side surface of the transfer unit 40. Here, the contact position between the belt 41 and the photosensitive drum 61 in the vertical direction V (the position of the contact surface (first tension surface) where the belt 41 contacts the photosensitive drum 61) is indicated by a dashed dotted line LA. The position of the lower end of the tray sidewall 51B is indicated by a dashed dotted line LB. In this embodiment, when the tray unit 50 and the transfer unit 40 are connected to each other, the dashed-dotted line LB is located below the dashed-dotted line LA in the vertical direction V. In other words, the position of the lower end of the tray side wall 51B is located below the position of the contact surface where the belt 41 contacts the photosensitive drum 61.

[0127] The lower end of the tray sidewall 51B is positioned higher than the upper end of the transfer frame sidewall 48C. Here, the direction in which the belt 41 moves while in contact with the photosensitive drum 61 is referred to as the belt movement direction. In the region in which the primary transfer roller 42 is disposed in the belt movement direction, the upper end of the transfer frame sidewall 48C is positioned higher than the lower end of the tray sidewall 51B.

[0128] FIG. 12 is a cross-sectional view of the integrated tray unit 50 and transfer unit 40 shown in FIG. 11(b) taken along the two-dot chain line A, illustrating the positional relationship of each component in the left-right direction D. Note that FIG. 12 is a cross-sectional view taken along the arrow HA in the horizontal direction H of FIG. 11(b), and shows enlarged views of both ends. In the left-right direction D, the tray sidewall 51B is positioned outside the belt 41, and in the vertical direction V, the lower end of the tray sidewall 51B (dotted chain line LB) is positioned below the belt surface (contact surface) (dotted chain line LA). At this time, the lower end of the primary transfer roller 42 is positioned below the lower end of the tray sidewall 51B. By positioning the tray sidewall 51B in this manner, the upper end of the belt 41 can be protected by the tray sidewall 51B.

[0129] Of the side edges of the belt 41, the portion located below the dashed-dotted line LC will be referred to as the lower edge. In this embodiment, as shown in Figures 11 and 12, the lower edge of the belt 41 is protected by being covered by the transfer frame side walls 48C, which are second walls. In the left-right direction D, the transfer frame side walls 48C are disposed on both ends of the belt 41 and further outward than the belt 41. In the vertical direction V, the upper edge of the transfer frame side walls 48C is disposed below the contact surface of the belt 41, and the lower edge of the transfer frame side walls 48C is disposed below the surface opposite the contact surface of the belt 41.

[0130] As described above, according to this embodiment, the upper side end of the belt 41 can be protected by the tray side wall 51B. This prevents the transfer unit 40, which moves integrally with the tray unit 50, from coming into contact with the belt side end when the user pulls out the tray unit 50 to replace a cartridge, and prevents dust and other foreign matter from entering the inside of the transfer unit 40 from the belt side end. As a result, contamination and damage to the belt 41 can be prevented.

[0131] (Variation 1) The position of the upper end of the transfer frame side wall 48C (dotted line LC) may be higher than the contact position between the belt 41 and the photosensitive drum 61 (dotted line LA).

[0132] 13 is a side view showing the state after the tray unit 50 and the transfer unit 40 are integrated and moved to the first outer position and the second outer position of the apparatus main body 1A in Modification 1 of this embodiment. The position of the upper end of the transfer frame side wall 48C, indicated by the dashed-dotted line LC, is higher in the vertical direction V than the contact position, indicated by the dashed-dotted line LA, between the belt 41 and the photosensitive drum 61. In other words, the upper end of the transfer frame side wall 48C is located above the contact surface where the belt 41 contacts the photosensitive drum 61.

[0133] 14 is a cross-sectional view of the cross section taken along dashed double-dashed line B in FIG. 13 as viewed from the direction of arrow HA, with both ends enlarged. In the left-right direction D, the transfer frame side wall 48C is disposed more inward than the tray side wall 51B. In the vertical direction V, the upper end of the transfer frame side wall 48C (dash-dotted line LC) is located above the contact position (dash-dotted line LA) between the belt 41 and the photosensitive drum 61. The lower end of the tray side wall 51B (dash-dotted line LB) is located below the contact position (dash-dotted line LA) between the belt 41 and the photosensitive drum 61. In other words, the side ends of the belt 41 are protected by being doubly covered by the transfer frame side wall 48C and the tray side wall 51B at their outer portions in the left-right direction D.

[0134] As shown in Figure 14, a small gap G may occur between the tray side wall 51B and the transfer frame side wall 48C. Therefore, foreign matter such as dust may enter through the gap G, and further, this foreign matter may enter the inside of the transfer unit 40 from the upper side end of the transfer unit 40. In contrast, in this modified example, the side end of the belt 41 is doubly protected by the transfer frame side wall 48C and the tray side wall 51B. As a result, the transfer frame side wall 48C and Even if a gap G occurs between the tray sidewalls 51B, it is possible to more effectively prevent foreign matter from entering from the upper end of the transfer unit 40.

[0135] (Variation 2) Further, the tray side wall 51B may be extended downward in the vertical direction V to protect the lower end of the belt 41.

[0136] 15(a) is a side view of the transfer unit 40 in the second modified example of this embodiment when it is in the second outer position. Here, the position of the lower end of the belt 41 in the vertical direction V is indicated by the dashed-dotted line LF, and the position of the upper end of the transfer frame side wall 48C is indicated by the dashed-dotted line LG. As in this modified example, the upper and lower end of the belt 41 may be exposed from the transfer frame side wall 48C. In other words, the side end of the belt 41 may include a portion above the dashed-dotted line LC and a portion below the dashed-dotted line LG in the vertical direction V, and these portions may be exposed from the transfer frame side wall 48C.

[0137] 15B is a side view of the integrated tray unit 50 and transfer unit 40 in the second modified example of this embodiment, when they are in the first outer position and the second outer position, respectively. As shown in FIG. 15B, the tray sidewall 51B is disposed so as to cover the upper and lower ends of the belt 41 exposed from the transfer frame sidewall 48C. That is, in the vertical direction V, the tray sidewall 51B is disposed so as to cover from the contact surface of the belt 41 with the photosensitive drum 61 to the opposite surface opposite the contact surface. The position of the lower end of the tray sidewall 51B, indicated by the dashed dotted line LB, is lower than the lower end of the belt 41, indicated by the dashed dotted line LF, and is below the opposite surface of the belt 41.

[0138] 16 is a cross-sectional view of the integrated tray unit 50 and transfer unit 40 shown in FIG. 15(b) taken along dash-dot line C, illustrating the positional relationship of each component in the left-right direction D. The tray sidewall 51B is disposed outboard of the belt 41 in the left-right direction D. In addition, in the vertical direction V, the position of the lower end of the tray sidewall 51B (dash-dot line LB) is lower than the position of the lower end of the belt 41 (dash-dot line LF). By arranging the tray sidewall 51B in this manner, it becomes possible to protect the side end of the belt 41 only by the tray sidewall 51B.

[0139] In this modification, as shown in Fig. 15(a), when the transfer unit 40 is used alone, the side edge of the belt 41 is exposed from the transfer frame side wall 48C. However, by integrating the transfer unit 40 with the tray unit 50 as shown in Fig. 15(b) and Fig. 16, the side edge of the belt 41 can be protected by the tray side wall 51B.

[0140] In a configuration in which the tray unit 50 and transfer unit 40 are integrated and moved outside the apparatus main body 1A, as in the present invention, a gap G can occur between the tray side wall 51B and the transfer frame side wall 48C, as described above. Therefore, there is a possibility that foreign matter entering through the gap G could enter the transfer unit 40, causing image defects. To address this, in the configuration of Modification 2, the tray side wall 51B is extended downward, protecting the entire side edge of the transfer unit 40 and preventing foreign matter from entering through the side edge of the transfer unit 40. Therefore, it is possible to prevent image defects caused by the entry of foreign matter.

[0141] (Variation 3) As described above, the photosensitive drum 61, the charging roller 62, and the developing roller 71 may be provided on either the cartridge P or the tray 51. This will be explained with reference to FIG. 17. FIGS. 17(a) to 17(d) are diagrams showing a tray unit 50 according to a modified example. be.

[0142] For example, as shown in FIG. 17(a), the tray 51 may have the photosensitive drum 61 and the charging roller 62, and the cartridge P may have the developing roller 71.

[0143] Here, the drum cartridge having the photosensitive drum 61 and the charging roller 62 is referred to as P1, and the developer cartridge having the developing roller 71 is referred to as P2. As shown in FIG. 17(b), the cartridge P may include the drum cartridge P1 and the developer cartridge P2. In other words, the cartridge P may be separable into the drum cartridge P1 and the developer cartridge P2. In this case, it is preferable that the drum cartridge P1 and the developer cartridge P2 be attachable to and detachable from the tray 51 independently of each other.

[0144] In addition, in Figure 17(c), a cartridge having a photosensitive drum 61, a charging roller 62, and a developing roller 71 is referred to as PR, and a cartridge having toner to be replenished to the cartridge PR is referred to as PT. As shown in Figure 17(c), the cartridge P may include the cartridge PR and the cartridge PT. Furthermore, the cartridge P may be separable into the cartridge PR and the cartridge PT.

[0145] 17(d), the cartridge P may include a drum cartridge P1, a developer cartridge P2, and a cartridge PT having toner for replenishing the developer cartridge P2. Similarly to FIG. 17(c), the cartridge P may be separable into the drum cartridge P1, the developer cartridge P2, and the cartridge PT.

[0146] Example 2 Next, another embodiment of the image forming apparatus according to the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, elements having the same or equivalent functions and configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals, and detailed explanations are omitted, and only the characteristic points of this embodiment will be described.

[0147] This embodiment differs from the first embodiment in that the primary transfer roller 42 is movable between a contact position and a separation position. Specifically, in this embodiment, the contact position is a position where the primary transfer roller 42 presses the belt 41 to form a primary transfer portion where the photosensitive drum 61 and the belt 41 are in contact with each other. The separation position is a position where the primary transfer roller 42 releases the pressure on the belt 41 to place the photosensitive drum 61 and the belt 41 in a separated state. The primary transfer roller 42 in this embodiment moves between the contact position and the separation position. A switching device provided in the apparatus main body 1A switches between a state where the primary transfer roller 42 is in the contact position and a state where the primary transfer roller 42 is in the separation position. This allows the belt 41 to be separated from the photosensitive drum 61 when no image formation operation is being performed.

[0148] In this embodiment, when the user moves the tray unit 50 and transfer unit 40, as an integrated unit, from the inside to the outside of the apparatus main body 1A, such as when replacing the cartridge P, the primary transfer roller 42 is in the separated position. Therefore, the belt 41 and the photosensitive drum 61 remain separated from each other. Even after the unit 40 is moved to the outside, the primary transfer roller 42 remains in the separated position, and the belt 41 and the photosensitive drum 61 remain separated from each other. When the photosensitive drum 61 rubs against the belt 41, scratches may occur on the surfaces of the photosensitive drum 61 and the belt 41, or the surface of the photosensitive drum 61 may become charged by the friction, resulting in image defects. In order to prevent scratches and image defects caused by the photosensitive drum 61 rubbing against the belt 41, this embodiment is configured to separate the belt 41 and the photosensitive drum 61.

[0149] If there is play between the tray unit 50 and the transfer unit 40 when they are connected, the tray unit 50 and the transfer unit 40 will move slightly relative to each other due to vibrations during movement when they are moved outside the apparatus main body 1A. At this time, if the primary transfer roller 42 is in the abutting position, the belt 41 and the photosensitive drum 61 are in contact with each other, causing friction between the photosensitive drum 61 and the belt 41. This may cause scratches on the surfaces of the photosensitive drum 61 and the belt 41, or the surface of the photosensitive drum 61 may become charged by friction. If this effect is significant, the scratches may appear as image defects, or the friction-charged portion of the photosensitive drum 61 may become unevenly charged, resulting in band-like image defects at the photosensitive drum's rotational speed.

[0150] In this embodiment, in order to prevent such image defects from occurring, the primary transfer roller 42 is moved to a separated position when the tray unit 50 and the transfer unit 40 are integrated and moved from the inside to the outside of the device main body 1A.

[0151] 18 is a side view showing the state after the tray unit 50 and the transfer unit 40 are integrated and moved to the first outer position and the second outer position of the apparatus main body 1A in this embodiment, and shows the state in which the primary transfer roller 42 is in the separated position. The dashed-dotted line LE indicates the position of the tension surface of the belt 41 when the belt 41 is stretched between the drive roller 46 and the tension roller 47, which serves as the first tension surface. The position of the lower end of the tray side wall 51B (dashed-dotted line LB) is below the position of the dashed-dotted line LE in the vertical direction V. That is, even when the belt 41 is separated from the photosensitive drum 61, the lower end of the tray side wall 51B is positioned below the contact surface of the belt 41.

[0152] 19 is a cross-sectional view of the integrated tray unit 50 and transfer unit 40 shown in FIG. 18, taken along dash-dot line E and viewed from the direction of arrow HA, with both ends enlarged. In the left-right direction D, the tray sidewall 51B is disposed outside the belt 41, and in the vertical direction V, the position of the lower end of the tray sidewall 51B (dash-dot line LB) is lower than the position of the tension surface of the belt 41 (dash-dot line LE). In this embodiment, by disposing the tray sidewall 51B in this manner, the upper end of the belt 41 is protected.

[0153] As described above, according to this embodiment, even when the primary transfer roller 42 is in the separated position, the upper end of the belt 41 can be protected by the tray side wall 51B.

[0154] In the above-described embodiment of the present invention, as shown in FIG. 4, when a portion of the belt 41 is pulled out to the outside of the apparatus main body 1A, the entire side edge of the belt 41 is protected by the tray side wall 51B or the transfer frame side wall 48C. However, this embodiment is not limited to this. That is, it is also possible to configure the belt 41 so that only the area of ​​the entire side edge that is pulled out to the outside of the apparatus main body 1A is partially protected by the tray side wall 51B or the transfer frame side wall 48C.

[0155] The disclosure of this embodiment includes the following configuration. (Configuration 1) A device body, a first unit including a photosensitive drum, the first unit having a first wall surface provided at one end of the photosensitive drum in a rotation axis direction, and movable between the inside and outside of the device main body; a second unit including a belt capable of coming into contact with the photosensitive drum and movable between the inside and outside of the apparatus main body; Equipped with The first unit and the second unit are connected to each other and integrally form the main body of the device. It is movable to the outside, An image forming apparatus characterized in that, when the first unit and the second unit are connected to each other, the first wall surface is located outside the belt in the direction of the rotation axis, and the lower end of the first wall surface in the vertical direction is located below the contact surface of the belt that contacts the photosensitive drum. (Configuration 2) the second unit further includes a primary transfer roller; The image forming apparatus according to configuration 1, characterized in that, when the first unit and the second unit are connected to each other, the first wall surface overlaps with at least a portion of the primary transfer roller when viewed in the direction of the rotation axis. (Configuration 3) The image forming apparatus according to Configuration 2, characterized in that, when viewed in the direction of the rotation axis, the lower end of the primary transfer roller in the vertical direction is located below the lower end of the first wall surface when the first unit and the second unit are connected to each other (Configuration 4). the second unit is configured so that the primary transfer roller is movable so that the belt is spaced apart from the photosensitive drum; The image forming apparatus according to configuration 2 or 3, characterized in that when the first unit and the second unit are connected to each other and the belt is spaced apart from the photosensitive drum, the lower end of the first wall surface is located below the contact surface. (Configuration 5) the second unit has a second wall surface that covers an end of the belt in the rotation axis direction, An image forming apparatus according to any one of configurations 1 to 4, characterized in that when the first unit and the second unit are connected to each other, the upper end of the second wall surface in the vertical direction is located above the lower end of the first wall surface. (Configuration 6) The image forming apparatus of configuration 5, characterized in that, when the first unit and the second unit are connected to each other, the second wall surface is located between the first wall surface and the belt in the rotation axis direction, and the upper end of the second wall surface in the vertical direction is located above the contact surface of the belt. (Configuration 7) The image forming apparatus according to configuration 5 or 6, characterized in that when the first unit and the second unit are connected to each other, the upper end of the second wall surface in the vertical direction is located below the contact surface of the belt. (Configuration 8) the belt has an opposite surface opposite the contact surface, The image forming apparatus according to configuration 1 or 2, characterized in that when the first unit and the second unit are connected to each other, the lower end of the first wall surface is located below the opposite surface in the vertical direction. (Configuration 9) the first wall surfaces are provided on both end sides of the photosensitive drum in the direction of the rotation axis, 6. The image forming apparatus according to configuration 5, wherein the second wall surfaces are provided on both ends of the belt in the direction of the rotation axis. (Configuration 10) the first unit is a tray unit that includes a cartridge and a tray to which the cartridge is detachably attached, and is movable between the inside and the outside of the apparatus main body; The photosensitive drum is provided in either the cartridge or the tray. 11. The image forming apparatus according to any one of configurations 1 to 10. (Configuration 11) 12. The image forming apparatus according to any one of configurations 1 to 11, wherein when the first unit moves from inside to outside the apparatus main body, the second unit also moves from inside to outside the apparatus main body. [Explanation of symbols]

[0156] 1....Printer, 1A....Device body (housing), 40....Transfer unit, 41....Belt, 48C....Transfer frame side wall, 50....Tray unit (tray unit, moving unit, support unit), 51B....Tray side wall, 61....Photosensitive drum (image carrier)

Claims

1. A device body, a first unit including a photosensitive drum, the first unit having a first wall surface provided at one end of the photosensitive drum in a rotation axis direction, the first unit being movable between the inside and outside of the device main body; a second unit including a belt capable of coming into contact with the photosensitive drum and movable between the inside and outside of the apparatus main body; Equipped with the first unit and the second unit are connected to each other and can be moved integrally to the outside of the device body, An image forming apparatus characterized in that, when the first unit and the second unit are connected to each other, the first wall surface is located outside the belt in the direction of the rotation axis, and the lower end of the first wall surface in the vertical direction is located below the contact surface of the belt that contacts the photosensitive drum.

2. the second unit further includes a primary transfer roller; 2. The image forming apparatus according to claim 1, wherein, when the first unit and the second unit are connected to each other, the first wall surface overlaps with at least a portion of the primary transfer roller when viewed in the direction of the rotation axis.

3. 3. The image forming apparatus according to claim 2, wherein when the first unit and the second unit are connected to each other, the lower end of the primary transfer roller in the vertical direction is located below the lower end of the first wall surface when viewed in the direction of the rotation axis.

4. the second unit is configured so that the primary transfer roller is movable so that the belt is spaced apart from the photosensitive drum; 4. The image forming apparatus according to claim 2, wherein the first unit and the second unit are connected to each other, and when the belt is spaced apart from the photosensitive drum, the lower end of the first wall surface is positioned below the contact surface.

5. the second unit has a second wall surface that covers an end of the belt in the direction of the rotation axis, 3. The image forming apparatus according to claim 1, wherein when the first unit and the second unit are connected to each other, the upper end of the second wall surface in the vertical direction is located above the lower end of the first wall surface.

6. 6. The image forming apparatus according to claim 5, wherein, when the first unit and the second unit are connected to each other, the second wall surface is located between the first wall surface and the belt in the direction of the rotation axis, and the upper end of the second wall surface in the vertical direction is located above the contact surface of the belt.

7. 6. The image forming apparatus according to claim 5, wherein when the first unit and the second unit are connected to each other, the upper end of the second wall surface in the vertical direction is located below the contact surface of the belt.

8. the belt has an opposite surface opposite the contact surface, When the first unit and the second unit are connected to each other, the lower end of the first wall surface is located below the opposite surface in the vertical direction.

3. The image forming apparatus according to claim 1, wherein:

9. the first wall surfaces are provided on both end sides of the photosensitive drum in the direction of the rotation axis, 6. The image forming apparatus according to claim 5, wherein the second wall surfaces are provided on both ends of the belt in the direction of the rotation axis.

10. the first unit is a tray unit that includes a cartridge and a tray to which the cartridge is detachably attached, and is movable between the inside and the outside of the apparatus main body; 3. The image forming apparatus according to claim 1, wherein the photosensitive drum is provided in either the cartridge or the tray.

11. 3. The image forming apparatus according to claim 1, wherein when the first unit moves from inside to outside the apparatus body, the second unit also moves from inside to outside the apparatus body.

Images