Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent a fuser from moving in a rotation axis direction.SOLUTION: An image forming apparatus 1 comprises: a body housing 10; a process unit 30 that has rotatable photoconductor drums on which toner images are formed, and transfers the toner images to a sheet; and a fuser 80 that has a heating roller and a pressure roller and fixes the toner images transferred to the sheet to the sheet. The fuser 80 can be mounted in the body housing 10 in a mounting direction orthogonal to a rotation axis direction of the photoconductor drums. The body housing 10 has a reference part 340 that determines a position in the rotation axis direction of the fuser 80 mounted in the body housing 10 with respect to the body housing 10. The fuser 80 has a contact part 140 that is in contact with the reference part 340 in the rotation axis direction when the fuser is mounted in the body housing 10. The image forming apparatus 1 further comprises a pressing mechanism 400 that presses the fuser 80 in the rotation axis direction to push the contact part 140 against the reference part 340.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, there is known an image forming apparatus that includes a main body housing, a photosensitive drum, and a fixing unit that is detachable from the main body housing (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-107852 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional configuration, the fixing unit mounted on the main body may move in the direction of the rotation axis of the photosensitive drum. If the fixing unit moves in the direction of the rotation axis of the photosensitive drum, the sheet may become skewed when the toner image is fixed to the sheet, which may result in a deterioration in image quality. Therefore, it is desirable to be able to suppress the movement of the fixing unit in the direction of the rotation axis. [Means for solving the problem]

[0005] The image forming apparatus includes a main body housing, a process unit, and a fixing unit. The process section has a rotatable photoreceptor on which a toner image is formed and transfers the toner image to a sheet. The fixing unit has a heating rotor and a pressure rotor, and fixes the toner image transferred to the sheet onto the sheet, and can be attached to the main body housing in an attachment direction perpendicular to the rotational axis direction of the photosensitive body. The main body housing has a reference portion for determining the position of the fixing unit in the rotation axis direction relative to the main body housing when the fixing unit is attached to the main body housing. The fixing unit has a contact portion that contacts the reference portion in the direction of the rotation axis when the fixing unit is attached to the main body housing. The image forming apparatus further includes a pressing mechanism that presses the fixing unit in the direction of the rotation axis to press the contact portion against the reference portion.

[0006] The image forming apparatus includes a pressing mechanism that presses the fixing unit in the rotation axis direction to press the contact portion of the fixing unit against the reference portion of the main body housing, thereby making it possible to prevent the fixing unit from moving in the rotation axis direction.

[0007] The contact portion may be provided on one side of the fixing unit in the direction of the rotation axis, and the pressing mechanism may be provided on the other side of the fixing unit in the direction of the rotation axis.

[0008] The contact portion is provided on one side of the fixing unit in the rotational axis direction, and the pressing mechanism is provided on the other side of the fixing unit in the rotational axis direction, so that the pressing mechanism can press the entire fixing unit in the rotational axis direction.

[0009] The fixing unit may have a fixing frame that supports the heating rotor and the pressure rotor. In this case, the pressing mechanism can include a movable member and a spring. The movable member is supported by the fixing frame so as to be movable from an initial position toward one side in the direction of the rotation axis. The spring biases the movable member toward the initial position. The movable member is in contact with the main body housing when the fixing unit is attached to the main body housing and is located at a position closer to one side in the direction of the rotation axis than the initial position.

[0010] When the fixing unit is attached to the main body housing, the movable member comes into contact with the main body housing and is positioned at a position closer to one side in the direction of the rotation axis than the initial position, so that the fixing unit can be pressed in the direction of the rotation axis by the biasing force of the spring that biases the movable member toward the initial position. The fixing unit can be pressed in the direction of the rotation axis with a relatively simple configuration.

[0011] The movable member may be configured to be rotatably supported by the fixing frame.

[0012] The movable member is rotatably supported by the fixing frame, so that the movable member can be moved stably.

[0013] The main body housing may have a recess into which the movable member is inserted when the fixing unit is attached to the main body housing.

[0014] The main body housing has a recess into which the movable member is inserted when the fixing unit is attached to the main body housing, so that the fixing unit can be prevented from moving in the attachment direction.

[0015] The main body housing may have a contact surface with which the movable member comes into contact when the fixing unit is attached to the main body housing. The contact surface is inclined so as to approach a reference portion in the direction of the rotation axis toward the downstream side in the mounting direction.

[0016] The contact surface is inclined so as to approach the reference portion in the direction of the rotation axis as it moves downstream in the installation direction, so that the fixing unit can be gradually pressed in the direction of the rotation axis when the fixing unit is installed. The contact surface can be used as a guide when the fixing unit is installed in the main body housing.

[0017] The contact portion may be configured to protrude from one side in the direction of the rotation axis of the fixing unit.

[0018] By having the contact portion protrude from one side in the direction of the rotation axis of the fixing unit, it is possible to reduce the amount of protrusion of the reference portion of the main body housing in the direction of the rotation axis.

[0019] The portion of the fixing unit that receives the force from the main body housing by the pressing mechanism may be arranged at a position that overlaps with the contact portion when viewed from the direction of the rotation axis.

[0020] The part of the fixing unit that receives force from the main body housing through the pressing mechanism is positioned at a position that overlaps with the contact portion when viewed from the direction of the rotation axis, thereby making it possible to suppress inclination of the fixing unit relative to the direction of the rotation axis when the fixing unit is pressed by the pressing mechanism.

[0021] A configuration may be adopted in which a plurality of contact portions are provided. In this case, the portion of the fixing unit that receives force from the main body housing by the pressing mechanism can be configured to be located between the multiple contact portions or surrounded by the multiple contact portions when viewed from the direction of the rotation axis.

[0022] The part of the fixing unit that receives force from the main body housing through the pressing mechanism is positioned between multiple contact parts or surrounded by multiple contact parts when viewed from the direction of the rotation axis, thereby suppressing inclination of the fixing unit relative to the direction of the rotation axis when the fixing unit is pressed by the pressing mechanism.

[0023] The main body housing may have a recess, and the fixing unit may have a boss. The recess is recessed in a direction perpendicular to the rotation axis direction and toward one side of a direction intersecting the mounting direction. The boss extends in the direction of the rotation axis and fits into the recess when the fixing unit is attached to the main body housing.

[0024] When the fixing unit is attached to the main body housing, the boss of the fixing unit enters a recess of the main body housing that is recessed toward one side in a direction perpendicular to the rotation axis direction and intersects with the attachment direction, thereby positioning the fixing unit in the attachment direction. Effect of the Invention

[0025] The fixing unit can be prevented from moving in the direction of its rotation axis. [Brief description of the drawings]

[0026] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment. [Diagram 2] 2 is a perspective view of the fixing unit and the main body housing with the rear cover open, as viewed from one side in the direction of the rotation axis. FIG. [Diagram 3] 3A and 3B are diagrams showing a fixing unit, a recessed portion of a main body housing, and a guide surface. [Figure 4]2 is a diagram showing the fixing unit, the reference portion of the main body housing, and the main body side contact surface as viewed from above. FIG. [Diagram 5] FIG. 2 is a perspective view showing one end of the fixing unit in the rotational axis direction. [Figure 6] 1A and 1B are enlarged views of a pressing mechanism, and FIG. 1C is an enlarged view of a contact portion between a reference portion of a main body housing and a fixing unit. [Figure 7] 1A is a perspective view showing the other end of the fixing unit in the rotation axis direction, and FIG. 1B is a view showing the protruding portion of the movable member as viewed from the rotation axis direction. [Figure 8] This figure shows the effect of the first boss when the fixing unit is attached to the main body housing, with (a) showing the first boss being guided by the first guide surface and (b) showing the first boss having reached the second guide surface. [Figure 9] This figure shows the effect of the first boss when the fixing unit is attached to the main body housing, with (a) showing the first boss disengaged from the guide surface and (b) showing the first boss inserted into the first recess. [Figure 10] 1A and 1B are diagrams showing the action of the pressing mechanism when the fixing unit is attached to the main body housing, in which FIG. 1A shows the state before the fixing unit is attached to the main body housing, and FIG. 1B shows the state when the movable member is in contact with the main body housing. [Figure 11] FIG. 13 is a diagram showing a first modified example, in which (a) shows a state in which a movable member contacts an inclined surface, and (b) shows a state in which the movable member enters a recess. [Figure 12] FIG. 13 is a diagram showing a second modified example, in which (a) is a perspective view showing one end of the fixing unit in the rotation axis direction, and (b) is a diagram showing a protruding portion of a movable member as viewed from the rotation axis direction. [Figure 13] FIG. 13 is a diagram showing a third modified example, in which (a) is a perspective view showing one end of the fixing unit in the rotation axis direction, and (b) is a diagram showing a protruding portion of a movable member as viewed from the rotation axis direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Next, an embodiment will be described. As shown in FIG. 1, the image forming apparatus 1 includes a main body housing 10, a sheet supply section 20, a process section 30, a fixing unit 80, and a sheet discharge section 90.

[0028] The main body housing 10 has a front cover 11, a discharge tray 12, and a rear cover 13. The front cover 11 opens and closes an opening on the front side of the main body housing 10. The rear cover 13 opens and closes an opening on the rear side of the main body housing 10.

[0029] The sheet supply unit 20 includes a sheet tray 21 and a supply mechanism 22. The sheet tray 21 stores sheets S such as paper. The supply mechanism 22 supplies the sheets S in the sheet tray 21 to the process unit 30.

[0030] The process section 30 transfers the toner image onto the sheet S. The process section 30 includes an exposure device 40, a drum cartridge 50, a plurality of toner cartridges 60, and a transfer unit .

[0031] The exposure device 40 is located above the drum cartridge 50. The exposure device 40 emits a light beam to expose the surface of the photosensitive drum 51.

[0032] The drum cartridge 50 is located between the sheet tray 21 and the exposure device 40. The drum cartridge 50 is detachable from the main body housing 10 through an opening in the main body housing 10 that is opened by opening the front cover 11.

[0033] The drum cartridge 50 includes a plurality of photosensitive drums 51, a plurality of chargers 52 corresponding to the plurality of photosensitive drums 51, and a drum frame 53. The photosensitive drums 51 are an example of a photoconductor.

[0034] The drum frame 53 supports the photosensitive drum 51 and the charger 52. The photosensitive drum 51 is rotatable relative to the drum frame 53. The drum frame 53 is movably supported by the main body housing 10. A toner cartridge 60 is detachably attached to the drum frame 53.

[0035] The plurality of toner cartridges 60 contain toners of different colors. Each toner cartridge 60 includes a developing roller 61, a supply roller 62, a layer thickness regulating blade 63, a toner containing section 64 that contains the toner, and an agitator 65.

[0036] The agitator 65 agitates the toner in the toner storage unit 64. The agitator 65 supplies the toner to the supply roller 62. The supply roller 62 supplies the toner to the development roller 61. The layer thickness regulating blade 63 regulates the toner on the development roller 61 to a constant thickness.

[0037] The transfer unit 70 is located between the sheet tray 21 and the drum cartridge 50. The transfer unit 70 includes a drive roller 71, a driven roller 72, a conveyor belt 73, and a plurality of transfer rollers 74. The conveyor belt 73 is an endless belt for conveying the sheet S. The drive roller 71 and the driven roller 72 rotate the conveyor belt 73. The transfer roller 74 is located inside the conveyor belt 73. The transfer roller 74 sandwiches the conveyor belt 73 between itself and the photosensitive drum 51.

[0038] The fixing unit 80 includes a heating roller 81 as a heating rotator and a pressure roller 82 as a pressure rotator. The heating roller 81 heats the sheet S. Two heaters 81A are disposed inside the heating roller 81. The heating roller 81 rotates by receiving a driving force from a driving source (not shown).

[0039] The pressure roller 82 sandwiches the sheet S between itself and the heating roller 81. The pressure roller 82 rotates in accordance with the heating roller 81.

[0040] The charger 52 charges the surface of the photosensitive drum 51. The exposure device 40 exposes the surface of the photosensitive drum 51. As a result, an electrostatic latent image is formed on the photosensitive drum 51. The development roller 61 supplies toner to the photosensitive drum 51. As a result, a toner image is formed on the photosensitive drum 51.

[0041] The sheet supply unit 20 transports the sheet S between the photosensitive drum 51 and the transfer roller 74. The toner image on the photosensitive drum 51 is transferred to the sheet S. The sheet S with the transferred toner image is transported between the heating roller 81 and the pressure roller 82. As a result, the fixing unit 80 fixes the toner image transferred to the sheet S onto the sheet S.

[0042] The sheet discharge section 90 has a transport roller 91 and a discharge roller 92. The transport roller 91 transports the sheet S to the discharge roller 92. The discharge roller 92 discharges the sheet S onto the discharge tray 12.

[0043] As shown in Fig. 2, the fixing unit 80 is detachable from the main body housing 10. More specifically, the fixing unit 80 is detachable from the main body housing 10 through an opening 10B of the main body housing 10 that is opened by opening the rear cover 13. In the following description, directions are described using the rotation axis direction, first direction, and second direction shown in Fig. 2. The arrows indicating the rotation axis direction, first direction, and second direction in the drawings point to one side in each direction.

[0044] The rotation axis direction is the rotation axis direction of the photosensitive drum 51. Specifically, it is the direction in which the rotation axis of the photosensitive drum 51 extends. In this embodiment, the rotation axis direction is a direction along the left-right direction of the image forming apparatus 1. One side of the rotation axis direction corresponds to the left side of the image forming apparatus 1, and the other side of the rotation axis direction corresponds to the right side of the image forming apparatus 1.

[0045] The first direction corresponds to the mounting direction of the fixing unit 80 relative to the main body housing 10. The first direction is a direction perpendicular to the rotation axis direction. In this embodiment, the first direction is a direction along the front-rear direction of the image forming apparatus 1. One side of the first direction corresponds to the rear side of the image forming apparatus 1, and the other side of the first direction corresponds to the front side of the image forming apparatus 1. The fixing unit 80 can be mounted relative to the main body housing 10 from one side to the other side in the first direction. One side of the first direction corresponds to the upstream side in the mounting direction, and the other side of the first direction corresponds to the downstream side in the mounting direction.

[0046] The second direction is a direction perpendicular to the rotation axis direction and intersects with the first direction. In this embodiment, the second direction is a direction perpendicular to both the rotation axis direction and the first direction. The second direction is a direction along the up-down direction of the image forming apparatus 1. One side of the second direction corresponds to the lower side of the image forming apparatus 1, and the other side of the second direction corresponds to the upper side of the image forming apparatus 1.

[0047] The fixing unit 80 has a first boss 120 and a second boss 130 on both sides in the rotation axis direction. In this embodiment, the structure around the bosses 120, 130 on one side in the rotation axis direction and the structure around the bosses 120, 130 on the other side in the rotation axis direction are substantially symmetrical in the rotation axis direction. Therefore, the structure around the bosses 120, 130 on one side in the rotation axis direction will be illustrated and described below.

[0048] The first boss 120 is a portion that comes into contact with the main body housing 10 when the fixing unit 80 is attached to the main body housing 10, thereby positioning the fixing unit 80 in the first direction and the second direction relative to the main body housing 10. The second boss 130 is a portion that comes into contact with the main body housing 10 when the fixing unit 80 is attached to the main body housing 10, thereby stopping rotation of the fixing unit 80 around the first boss 120.

[0049] The first boss 120 has a columnar shape. The second boss 130 has a cylindrical shape. The second boss 130 is located on one side of the first boss 120 in the first direction. The second boss 130 is located on one side of the first boss 120 in the second direction. The first boss 120 and the second boss 130 extend in the rotational axis direction. The first boss 120 and the second boss 130 protrude from the side surface of the fixing unit 80 in the rotational axis direction toward the outside in the rotational axis direction.

[0050] As shown in FIG. 3, the main body housing 10 has a guide surface 310, a first recess 320, and a second recess 330.

[0051] The first recess 320 is a recess shaped to be recessed toward one side in the second direction. The first boss 120 of the fixing unit 80 enters the first recess 320 when the fixing unit 80 is attached to the main body housing 10. The first boss 120 is located on the other side in the first direction of the nip position NP between the heating roller 81 and the pressure roller 82.

[0052] The first recess 320 has a first reference surface 321, a second reference surface 322, and a stopper surface 323. The first reference surface 321 is a surface on one side in the second direction of the first recess 320. The first reference surface 321 is perpendicular to the second direction.

[0053] The second reference surface 322 is a surface on one side in the first direction of the first recess 320. The second reference surface 322 extends from an end on one side in the first direction of the first reference surface 321 toward the other side in the second direction. The second reference surface 322 intersects with the first direction. In this embodiment, the second reference surface 322 is perpendicular to the first direction.

[0054] The stopper surface 323 is a surface on the other side in the first direction of the first recess 320. The stopper surface 323 extends from an end on the other side in the first direction of the first reference surface 321 toward the other side in the second direction. The stopper surface 323 intersects with the first direction. In this embodiment, the stopper surface 323 is perpendicular to the first direction. When the first boss 120 of the fixing unit 80 attached to the main body housing 10 comes into contact with the stopper surface 323, the stopper surface 323 prevents the fixing unit 80 from moving further to the other side in the first direction.

[0055] The guide surface 310 is a surface that guides the first boss 120 toward the first recess 320 when the fixing unit 80 is attached to the main body housing 10. The guide surface 310 has a first guide surface 311, a second guide surface 312, and a third guide surface 313. The first guide surface 311 extends in a first direction.

[0056] The second guide surface 312 is located between the first guide surface 311 and the third guide surface 313. The second guide surface 312 is inclined obliquely upward from one side to the other side in the first direction so as to be located on the other side in the second direction.

[0057] The third guide surface 313 is located between the second guide surface 312 and the first recess 320. The third guide surface 313 extends from an end of the second guide surface 312 on the other side in the first direction toward the other side in the first direction. The end of the third guide surface 313 on the other side in the first direction is connected to an end of the second reference surface 322 of the first recess 320 on the other side in the second direction.

[0058] The second recess 330 is a recess shaped to be recessed toward the other side in the first direction. The second boss 130 fits into the second recess 330 when the fixing device 80 is attached to the main body housing 10. The second boss 130 is located on one side in the first direction of the nip position NP between the heating roller 81 and the pressure roller 82. The second recess 330 is open toward one side in the first direction. The second recess 330 has a bottom surface 331, a first regulating surface 332, and a second regulating surface 333.

[0059] The bottom surface 331 is the surface of the second recess 330 on the other side in the first direction. The first regulating surface 332 and the second regulating surface 333 are surfaces for stopping the rotation of the fixing device 80 around the first boss 120. The first regulating surface 332 extends from one end of the bottom surface 331 in the second direction toward one side in the first direction. The second regulating surface 333 extends from the other end of the bottom surface 331 in the second direction toward one side in the first direction. The second boss 130 that enters the second recess 330 is disposed between the first regulating surface 332 and the second regulating surface 333.

[0060] The image forming apparatus 1 further includes a spring SP. As an example, the spring SP is a torsion coil spring. The spring SP has a pressing arm AR. When the fixing unit 80 is attached to the main body housing 10, the pressing arm AR presses the first boss 120 located in the first recess 320 toward one side in the first direction and toward one side in the second direction. This causes the first boss 120 to contact the first reference surface 321 and the second reference surface 322.

[0061] 4, the main body housing 10 has a reference portion 340 and a main body-side contact surface 350 as a contact surface. The fixing unit 80 has a contact portion 140. The image forming apparatus 1 further includes a pressing mechanism 400.

[0062] The reference portion 340 is a portion that determines the position of the fixing unit 80 attached to the main body housing 10 in the direction of the rotation axis with respect to the main body housing 10. The main body side contact surface 350 is a surface that comes into contact with the movable member 410 of the pressing mechanism 400 when the fixing unit 80 is attached to the main body housing 10 and when the fixing unit 80 is attached to the main body housing 10.

[0063] The contact portion 140 is a portion that comes into contact with the reference portion 340 in the direction of the rotation axis when the fixing unit 80 is attached to the main body housing 10 . The pressing mechanism 400 is a mechanism for pressing the fixing unit 80 in the direction of the rotation axis to press the contact portion 140 against the reference portion 340 .

[0064] The reference portion 340 is located on one side in the direction of the rotation axis of the fixing unit 80 when the fixing unit 80 is attached to the main body housing 10. The reference portion 340 has a reference surface 341 with which the contact portion 140 of the fixing unit 80 comes into contact. The reference surface 341 is a plane perpendicular to the direction of the rotation axis.

[0065] The main body side contact surface 350 is located on the other side in the rotation axis direction of the fixing unit 80 when it is attached to the main body housing 10. In this embodiment, the main body side contact surface 350 is a plane perpendicular to the rotation axis direction.

[0066] The main body housing 10 has a first side frame 14 and a second side frame 15. The first side frame 14 is located on one side of the main body housing 10 in the direction of the rotation axis. The second side frame 15 is located on the other side of the main body housing 10 in the direction of the rotation axis. The fixing unit 80 is disposed between the first side frame 14 and the second side frame 15 in a state where it is attached to the main body housing 10. In this embodiment, the reference portion 340 is provided on the first side frame 14. Also, the main body side contact surface 350 is provided on the second side frame 15.

[0067] The contact portion 140 is provided on one side in the rotational axis direction of the fixing device 80. As shown in an enlarged view in Fig. 6(c), the contact portion 140 protrudes from one side in the rotational axis direction of the fixing device 80. Specifically, the fixing device 80 has a fixing frame 83 that supports the heating roller 81 and the pressure roller 82. The contact portion 140 protrudes to one side in the rotational axis direction from a side surface on one side in the rotational axis direction of the fixing frame 83.

[0068] 5, the contact portion 140 has a rib shape extending in the first direction. The contact portion 140 has a fixing side contact surface 141 that contacts a reference surface 341 of the reference portion 340. The fixing side contact surface 141 is a plane perpendicular to the rotation axis direction.

[0069] As shown in Fig. 4, the pressing mechanism 400 is provided on the other side of the fixing device 80 in the rotational axis direction. In this embodiment, the fixing device 80 includes the pressing mechanism 400. Specifically, the pressing mechanism 400 is provided at an end portion on the other side of the rotational axis direction of the fixing device 80. As shown in Figs. 6(a) and (b), the pressing mechanism 400 has a movable member 410 and a spring 420.

[0070] The movable member 410 is movably supported by the fixing frame 83. Specifically, the movable member 410 is supported by the fixing frame 83 so as to be movable from an initial position shown in Fig. 6(a) toward one side in the direction of the rotation axis as shown in Fig. 6(b). More specifically, the movable member 410 is supported by the fixing frame 83 so as to be rotatable toward one side in the direction of the rotation axis from the initial position.

[0071] The movable member 410 has a pivotal support portion 411 , an arm 412 , and a protrusion portion 413 . The shaft support portion 411 is a portion rotatably supported by a shaft portion 83A formed on the fixing frame 83. The movable member 410 is supported by the fixing frame 83 to be rotatable about an axis extending in a direction perpendicular to both the rotation axis direction and the first direction.

[0072] The arm 412 extends from the pivot portion 411 towards one side in the first direction. The protruding portion 413 protrudes from one end of the arm 412 in the first direction toward the other side in the direction of the rotation axis.

[0073] 6(a), the spring 420 is a spring that biases the movable member 410 toward the initial position. As an example, the spring 420 is a compression coil spring. The spring 420 is disposed between the protruding portion 413 and the fixing frame 83 in the rotation axis direction, with one end of the spring 420 in the rotation axis direction engaging with the spring engaging portion 83B of the fixing frame 83 and the other end of the spring 420 in the rotation axis direction engaging with the spring engaging portion 413B of the protruding portion 413.

[0074] 6(b), when the tip of the protrusion 413 comes into contact with the main body contact surface 350 of the main body housing 10 while the fixing unit 80 is attached to the main body housing 10, the movable member 410 is located at a position closer to one side in the direction of the rotation axis than the initial position (see FIG. 6(a)). At this time, the spring 420 is compressed more than when the movable member 410 is located at the initial position.

[0075] 7(a), the fixing frame 83 has an opening 83C on the other side in the direction of the rotation axis. The tip of the protruding portion 413 of the movable member 410 protrudes from the opening 83C to the outside of the fixing frame 83. The remaining portion of the movable member 410 and the spring 420 are disposed inside the fixing frame 83.

[0076] 6A, the movable member 410 further has a stopper 414. The stopper 414 extends from one end of the protruding portion 413 in the first direction toward the opposite side to the arm 412. When the fixing unit 80 is not attached to the main body housing 10, the stopper 414 abuts against and gets caught on a portion around the opening 83C of the fixing frame 83 from the inside in the rotation axis direction due to the biasing force of the spring 420, thereby restricting the movable member 410 to an initial position.

[0077] 7(b), the tip of the protruding portion 413 of the movable member 410 is disposed at a position overlapping the contact portion 140 when viewed from the other side of the rotation axis direction. In other words, the contact portion 140 is disposed at a position overlapping the tip of the protruding portion 413 of the movable member 410 when viewed from one side of the rotation axis direction. The tip of the protruding portion 413 corresponds to a portion of the fixing unit 80 that receives a force (reaction force) from the main body housing 10 by the pressing mechanism 400.

[0078] Next, the operation of each part when the fixing unit 80 is attached to the main body housing 10 will be described. As shown in FIG. 8(a), when the fixing unit 80 is inserted into the main housing 10 from one side to the other side in the first direction, the first boss 120 comes into contact with the first guide surface 311 of the guide surface 310 and is guided by the first guide surface 311.

[0079] 8(b), the second boss 130 comes into contact with the first restriction surface 332 and is guided by the first restriction surface 332. When the first boss 120 comes into contact with the second guide surface 312, the first boss 120 moves obliquely upward from one side to the other side in the first direction while being guided by the second guide surface 312.

[0080] 9(a), the fixing unit 80 is inserted into the main housing 10 with the surface on the other side in the first direction facing diagonally upward. The first boss 120 is guided by the second guide surface 312, and then guided by the third guide surface 313 in the direction along the first direction.

[0081] 9(b), the first boss 120 enters the first recess 320 due to the biasing force of the spring SP. In detail, the first boss 120 guided by the third guide surface 313 presses the pressing arm AR of the spring SP, causing the pressing arm AR to elastically deform to the other side in the first direction.

[0082] Thereafter, when the first boss 120 comes off the third guide surface 313, the first boss 120 is pressed to one side in the first direction and one side in the second direction by the restoring force of the spring SP, and enters the first recess 320. At this time, the second boss 130 is in the second recess 330.

[0083] When the fixing unit 80 is attached to the main body housing 10, the first boss 120 is pressed against the first reference surface 321 of the first recess 320 by the biasing force of the spring SP, and is also pressed against the second reference surface 322 of the first recess 320 by gravity and the biasing force of the spring SP. By pressing the first boss 120 against the first reference surface 321 and the second reference surface 322 in this manner, the fixing unit 80 is positioned in the first and second directions.

[0084] 10(a), when the fixing unit 80 is inserted into the main body housing 10 from one side to the other side in the first direction, the movable member 410 of the pressing mechanism 400 comes into contact with the second side frame 15 of the main body housing 10, as shown in Fig. 10(b). When the fixing unit 80 is further inserted into the main body housing 10, the protruding portion 413 of the movable member 410 is pressed against the second side frame 15, and the movable member 410 rotates from the initial position toward one side in the direction of the rotation axis while compressing the spring 420.

[0085] Thereafter, the tip of the protruding portion 413 of the movable member 410 comes into contact with the main body contact surface 350 of the main body housing 10. Then, as shown in Fig. 4, when the fixing unit 80 is attached to the main body housing 10, the fixing unit 80 is pressed toward one side in the direction of the rotation axis by the biasing force of the spring 420.

[0086] As a result, in the fixing device 80, the fixing-side contact surface 141 of the contact portion 140 is pressed against the reference surface 341 of the reference portion 340 of the main body housing 10. By pressing the fixing-side contact surface 141 against the reference surface 341 in this manner, the fixing device 80 is positioned in the direction of the rotation axis.

[0087] Next, the effects of the image forming apparatus 1 will be described. The image forming apparatus 1 includes the pressing mechanism 400 that presses the fixing unit 80 in the rotation axis direction to press the fixing-side contact surface 141 of the contact portion 140 of the fixing unit 80 against the reference surface 341 of the reference portion 340 of the main body housing 10, thereby making it possible to suppress movement of the fixing unit 80 in the rotation axis direction. Furthermore, it is possible to suppress movement of the fixing unit 80 in the rotation axis direction when fixing the toner image to the sheet S.

[0088] Since the contact portion 140 is provided on one side of the fixing device 80 in the direction of the rotation axis, and the pressing mechanism 400 is provided on the other side of the fixing device 80 in the direction of the rotation axis, the pressing mechanism 400 can press the entire fixing device 80 in the direction of the rotation axis.

[0089] When the fixing device 80 is attached to the main body housing 10, the movable member 410 comes into contact with the main body housing 10 and is positioned at a position closer to one side in the rotation axis direction than the initial position, so that the fixing device 80 can be pressed in the rotation axis direction by the biasing force of the spring 420 that biases the movable member 410 toward the initial position. The pressing mechanism 400 can press the fixing device 80 in the rotation axis direction with a relatively simple configuration having the movable member 410 and the spring 420.

[0090] The movable member 410 is rotatably supported by the fixing frame 83, so that the movable member 410 can be moved stably.

[0091] Since the contact portion 140 protrudes from one side in the rotation axis direction of the fixing device 80, it is possible to reduce the amount of protrusion in the rotation axis direction of the reference portion 340 of the main body housing 10. This makes it difficult for the fixing device 80 to collide with or get caught on the reference portion 340 when the fixing device 80 is attached.

[0092] Since the contact portion 140 has a rib shape extending in a first direction as the mounting direction, the frictional resistance caused by contact between the fixing side contact surface 141 and the main body housing 10 when the fixing unit 80 is mounted in the main body housing 10 can be reduced.

[0093] The tip of the protrusion 413 of the movable member 410 is disposed at a position overlapping the contact portion 140 when viewed from the rotation axis direction, so that when the pressing mechanism 400 presses the fixing device 80, the fixing device 80 can be pressed straight along the rotation axis direction. This makes it possible to suppress inclination of the fixing device 80 with respect to the rotation axis direction.

[0094] When the fixing unit 80 is attached to the main housing 10, the first boss 120 of the fixing unit 80 enters a first recess 320 of the main housing 10, which is recessed toward one side in the second direction, thereby allowing the fixing unit 80 to be positioned in the first direction (attachment direction) and the second direction.

[0095] Although the embodiment has been described above, the image forming apparatus can be modified as appropriate as shown in the following examples. The following description will focus on the differences from the above embodiment. Members and parts having the same functions as the above embodiment will be given the same reference numerals and will not be described.

[0096] 11(a) and (b), the main body housing 10 may have a recess 351 on the main body contact surface 350. The recess 351 is a recess into which the tip of the protrusion 413 of the movable member 410 fits when the fixing unit 80 shown in FIG. 11(b) is attached to the main body housing 10.

[0097] In the first modified example, the tip of the protruding portion 413 of the movable member 410 is also located at a position closer to one side in the direction of the rotation axis than the initial position when the fixing unit 80 is attached to the main body housing 10. At this time, the spring 420 is compressed more than when the movable member 410 is located at the initial position. As a result, the fixing side contact surface 141 of the contact portion 140 of the fixing unit 80 is pressed against the reference surface 341 of the reference portion 340.

[0098] The main body housing 10 has the recess 351 into which the movable member 410 fits when the fixing unit 80 is attached to the main body housing 10, so that the fixing unit 80 can be prevented from moving in the first direction (attaching direction).

[0099] Furthermore, main body side contact surface 350 is inclined so that the surface with which movable member 410 comes into contact when fixing unit 80 is attached to main body housing 10 approaches reference portion 340 in the rotation axis direction toward the other side in the first direction. Specifically, main body side contact surface 350 has inclined surface 352 on one side in the first direction of recess 351. Inclined surface 352 is inclined so as to approach one side in the rotation axis direction toward the other side in the first direction.

[0100] Since the main body side contact surface 350 has the inclined surface 352, the movable member 410 can be gradually rotated from the initial position toward one side in the direction of the rotation axis when the fixing unit 80 is attached to the main body housing 10. This allows the fixing unit 80 to be gradually pressed in the direction of the rotation axis when the fixing unit 80 is attached to the main body housing 10. In addition, the main body side contact surface 350 can be used as a guide when the fixing unit 80 is attached to the main body housing 10.

[0101] As shown in FIGS. 12 and 13, a plurality of contact portions 150, 160 protruding from one side of the fixing unit 80 in the rotation axis direction may be provided. For example, in a second modified example shown in Fig. 12(a), the contact portion 150 is composed of a first rib 151 and a second rib 152. The first rib 151 and the second rib 152 each extend in a first direction. The first rib 151 and the second rib 152 are disposed at an interval in the second direction.

[0102] 12(b), in the second modified example, the tip of the protruding portion 413 of the movable member 410 is disposed between the multiple contact portions 150 when viewed from the rotation axis direction. Specifically, the tip of the protruding portion 413 is disposed between the first rib 151 and the second rib 152 when viewed from the rotation axis direction.

[0103] Since the tip of the protrusion 413 of the movable member 410 is positioned between the multiple contact portions 150 when viewed from the direction of the rotation axis, when the fixing device 80 is pressed by the pressing mechanism 400, the inclination of the fixing device 80 with respect to the direction of the rotation axis can be suppressed.

[0104] 13(a), the contact portion 160 includes a first protrusion 161, a second protrusion 162, and a third protrusion 163. As an example, the first protrusion 161 and the second protrusion 162 are arranged at an interval in the first direction. The third protrusion 163 is located on one side in the second direction relative to the first protrusion 161 and the second protrusion 162. The third protrusion 163 is located between the first protrusion 161 and the second protrusion 162 in the first direction.

[0105] 13(b), in the third modified example, the tip of the protrusion 413 of the movable member 410 is disposed at a position surrounded by a plurality of contact portions 160 when viewed from the rotation axis direction. Specifically, the tip of the protrusion 413 is disposed at a position inside a triangle indicated by imaginary lines connecting the first protrusion 161, the second protrusion 162, and the third protrusion 163 when viewed from the rotation axis direction.

[0106] Since the tip of the protrusion 413 of the movable member 410 is positioned at a position surrounded by multiple contact portions 160 when viewed from the direction of the rotation axis, when the fixing device 80 is pressed by the pressing mechanism 400, the inclination of the fixing device 80 with respect to the direction of the rotation axis can be suppressed.

[0107] In the above embodiment, the movable member 410 was rotatably supported by the fixing frame 83. However, for example, the movable member may be supported by the fixing frame so as to be linearly movable along the rotation axis direction.

[0108] In the above embodiment, the spring 420 is a compression coil spring. However, for example, the spring that biases the movable member toward the initial position may be a torsion coil spring, a leaf spring, or the like.

[0109] In the above embodiment, the contact portion 140 is configured to protrude in the direction of the rotation axis, but the contact portion may not protrude. For example, the contact portion may be a side surface of the fixing frame in the direction of the rotation axis. Also, the reference portion of the main body housing may protrude in the direction of the rotation axis.

[0110] In the above embodiment, the contact portion 140 and the reference portion 340 are provided on one side of the fixing device 80 in the rotational axis direction, and the pressing mechanism 400 is provided on the other side of the fixing device 80 in the rotational axis direction, but this is not limited to the above. For example, the contact portion and the reference portion may be provided at a position between one end and the other end of the fixing device in the rotational axis direction. The same applies to the pressing mechanism.

[0111] In the above embodiment, the pressing mechanism 400 is provided in the fixing unit 80, but for example, the pressing mechanism may be provided in the main body housing of the image forming apparatus.

[0112] In the above embodiment, the photosensitive drum 51 is exemplified as the photosensitive member, but the photosensitive member may be, for example, a photosensitive belt. When the photosensitive member is a photosensitive belt, the rotation axis direction of the photosensitive member corresponds to a direction parallel to the rotation axis direction of the roller around which the photosensitive belt is stretched.

[0113] In the above embodiment, the heating roller 81 is exemplified as the heating rotator, but the heating rotator may be, for example, a heating belt, a heating film, etc. Also, in the above embodiment, the pressure roller 82 is exemplified as the pressure rotator, but the pressure rotator may be, for example, an endless belt sandwiched between the heating rotator and an elastic pad.

[0114] In the above embodiment, the image forming device 1 is a printer capable of forming color images, but for example, the image forming device may be a printer capable of forming only monochrome images. The image forming device may also be a copier, a multifunction device, or the like.

[0115] The elements described in the above embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0116] 1. Image forming device 10 Main unit housing 30 Process Section 51 Photosensitive drum 80 Fixing unit 81 Heating roller 82 Pressure roller 140 Contact part 340 Reference section 400 Pressing mechanism S Seat

Claims

1. A main body housing; a process section having a rotatable photoreceptor on which a toner image is formed and transferring the toner image to a sheet; An image forming apparatus including a fixing unit having a heating rotator and a pressure rotator, and fixing a toner image transferred onto a sheet onto the sheet, the fixing unit being mountable in a mounting direction perpendicular to a rotation axis direction of the photosensitive member with respect to the main body housing, the main body housing has a reference portion for determining a position of the fixing unit in a rotation axis direction with respect to the main body housing when the fixing unit is attached to the main body housing, the fixing unit has a contact portion that contacts the reference portion in the direction of the rotation axis when the fixing unit is attached to the main body housing, The image forming apparatus further comprises a pressing mechanism that presses the fixing unit in the direction of the rotation axis to press the contact portion against the reference portion.

2. the contact portion is provided on one side of the fixing unit in the rotational axis direction, 2. The image forming apparatus according to claim 1, wherein the pressing mechanism is provided on the other side of the fixing unit in the direction of the rotation axis.

3. the fixing unit has a fixing frame supporting the heating rotator and the pressure rotator, The pressing mechanism includes: a movable member supported by the fixing frame so as to be movable from an initial position toward one side in the direction of the rotation axis; a spring that biases the movable member toward the initial position, 3. The image forming apparatus according to claim 2, wherein the movable member is in contact with the main body housing when the fixing unit is attached to the main body housing and is positioned at a position closer to one side of the rotation axis direction than the initial position.

4. 4. The image forming apparatus according to claim 3, wherein the movable member is rotatably supported by the fixing frame.

5. 4. The image forming apparatus according to claim 3, wherein the main body housing has a recess into which the movable member is inserted when the fixing unit is attached to the main body housing.

6. the main body housing has a contact surface with which the movable member comes into contact when the fixing unit is attached to the main body housing, 4. The image forming apparatus according to claim 3, wherein the contact surface is inclined so as to approach the reference portion in the direction of the rotation axis toward the downstream side in the mounting direction.

7. 2. The image forming apparatus according to claim 1, wherein the contact portion protrudes from one side of the fixing unit in the direction of the rotation axis.

8. 8. The image forming apparatus according to claim 7, wherein a portion of the fixing unit receiving a force from the main body housing by the pressing mechanism is disposed at a position overlapping the contact portion when viewed from the direction of the rotation axis.

9. The contact portion is provided in plurality, 8. The image forming apparatus according to claim 7, wherein a portion of the fixing unit that receives a force from the main body housing by the pressing mechanism is located between the plurality of contact portions or surrounded by the plurality of contact portions when viewed from the direction of the rotation axis.

10. the main body housing has a recess that is recessed toward one side in a direction perpendicular to the rotation axis direction and intersecting with the mounting direction, 2. The image forming apparatus according to claim 1, wherein the fixing unit has a boss extending in the direction of the rotation axis, the boss being fitted into the recess when the fixing unit is attached to the main body housing.

Images