Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent a fuser from moving from a mounting position where it is mounted in a body housing.SOLUTION: An image forming apparatus 1 comprises: a body housing 10; and a fuser 80 that has a heating roller 81 and a pressure roller 82. The fuser 80 can be mounted in the body housing 10 from one side toward the other side of a first direction. The body housing 10 has a first recess 320A in a shape recessed toward one side of a second direction intersecting the first direction. The fuser 80 has a first boss 120A that extends in a third direction orthogonal to both the first direction and the second direction, the first boss 120A located in the first recess 320A when the fuser 80 is mounted in the body housing 10. The image forming apparatus 1 further comprises a first spring SP1 that presses the first boss 120A located in the first recess 320A when the fuser 80 is mounted in the body housing 10, toward one side of the first direction and one side of the second direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, there is known an image forming apparatus that includes a main body housing and a fixing unit that is detachable from the main body housing (Patent Document 1). In this technology, the image forming apparatus has a support groove that supports a support shaft of the fixing unit, the support groove extending in the front-rear direction, and a wire spring that urges the support shaft downward to abut against the lower edge of the support groove. [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] Incidentally, in the conventional configuration, there is a possibility that the fixing unit may move back and forth from the mounting position in the main body housing. It is therefore desirable to be able to prevent the fixing unit from moving from the mounting position in the main body housing. [Means for solving the problem]

[0005] The image forming apparatus includes a main body housing and a fixing unit. The fixing unit has a heating rotator and a pressure rotator, and is mountable from one side to the other side in a first direction relative to the main body housing. The main body housing has a first recess that is recessed toward one side in a second direction intersecting the first direction. The fixing unit has a first boss extending in a third direction perpendicular to both the first direction and the second direction, the first boss being located within the first recess when the fixing unit is attached to the main body housing. The image forming apparatus further includes a spring that presses the first boss, located in the first recess, toward one side in the first direction and toward one side in the second direction when the fixing unit is attached to the main body housing.

[0006] By providing a spring that presses the first boss located in the first recess when the fixing unit is attached to the main housing toward one side in the first direction and one side in the second direction, it is possible to prevent the fixing unit from moving from the mounting position where it is attached to the main housing.

[0007] The first recess may be configured so that a distance between a surface on one side in the first direction and a surface on the other side in the first direction is larger than a size of the first boss in a direction perpendicular to the second direction. In this case, the first boss can be configured not to come into contact with the surface of the first recess on the other side in the first direction when pressed by the spring.

[0008] Since the first boss does not come into contact with the surface of the first recess on the other side in the first direction when pressed by the spring, the first boss is less affected by the dimensional accuracy of the first recess, and thus the fixing unit can be positioned with high accuracy relative to the main body housing.

[0009] The first boss may be configured to be in contact with one surface of the first recess in the first direction and one surface of the first recess in the second direction when pressed by the spring.

[0010] When pressed by the spring, the first boss comes into contact with one surface of the first recess in the first direction and one surface of the first recess in the second direction, so that the first boss can be positioned by coming into contact with two surfaces, thereby enabling the fixing unit to be positioned with high accuracy relative to the main body housing.

[0011] In one example, the spring is a torsion coil spring.

[0012] By using a torsion coil spring as the spring, the pressing force and stroke can be appropriately set.

[0013] The main body housing may have a guide surface that guides the first boss toward the first recess when the fixing unit is attached to the main body housing. In this case, the guide surface may have a first guide surface and a second guide surface. The first guide surface extends in a first direction. The second guide surface is located between the first guide surface and the first recess, and is inclined from one side to the other side in the first direction so as to be located on the other side in the second direction.

[0014] The second guide surface located between the first guide surface and the first recess is inclined so as to be located on the other side in the second direction as it moves from one side to the other side in the first direction, so that the positions of the first guide surface and the first recess in the second direction can be made substantially the same, thereby making it possible to make the posture of the fixing unit when it is installed, in which the first boss is guided by the first guide surface, and the posture of the fixing unit after it is installed, in which the first boss enters the first recess, substantially the same.

[0015] The main body housing may have a metal plate including a first portion perpendicular to the third direction, and the first recess may be formed in the first portion.

[0016] By forming the first recess in the metal plate, the fixing unit can be positioned relative to the metal plate having high rigidity.

[0017] The fixing unit may have a side plate that supports at least one of the heating rotator and the pressure rotator, and that is located on one side of the heating rotator and the pressure rotator in the third direction. In this case, the first boss can be fixed to the side plate by crimping, the metal plate can be located on one side of the side plate in the third direction, and the spring can press the first boss from one side of the metal plate in the third direction.

[0018] A metal plate is positioned on one side in the third direction of the side plate to which the first boss is fixed by crimping, and a spring presses the first boss on one side in the third direction of the metal plate, thereby reducing the load on the crimped portion of the first boss.

[0019] The first boss may be configured to be located on the other side in the first direction from a nip position between the heating rotator and the pressure rotator.

[0020] By positioning the first boss on the other side in the first direction from the nip position between the heating rotator and the pressure rotator, the fixing unit can be positioned with respect to the main body housing based on the rear side in the mounting direction of the fixing unit.

[0021] The fixing unit may have a second boss, and the main body housing may have a second recess. The second boss extends in the third direction and is located on one side of the nip position in the first direction. The second recess is a second recess having a shape recessed toward the other side in the first direction, and the second boss is inserted in the second recess when the fixing unit is attached to the main body housing.

[0022] The fixing unit has the second boss and the main body housing has the second recess, so that rotation of the fixing unit around the first boss can be restricted.

[0023] The fixing unit may have a protrusion, and the main body housing may have a hole. The protruding portion protrudes to the other side in the first direction. The hole is a hole into which the protrusion fits when the fixing unit is attached to the main body housing, and restricts movement of the protrusion in the third direction.

[0024] The fixing unit has a protrusion and the main body housing has a hole that restricts movement of the protrusion in the third direction, so that the movement of the fixing unit in the third direction can be restricted, thereby allowing the fixing unit to be positioned in the third direction.

[0025] The hole may be configured so that a dimension in the second direction is larger than a dimension in the second direction of the protrusion.

[0026] Because the dimension of the hole in the second direction is larger than the dimension of the protrusion in the second direction, interference between the protrusion and the main housing can be prevented even if the fixing unit moves in the second direction when the fixing unit is attached to the main housing. Effect of the Invention

[0027] This can prevent the fixing unit from moving from the mounting position in the main body housing. [Brief description of the drawings]

[0028] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment. [Diagram 2] 11 is a perspective view of the fixing unit and the main body housing with the rear cover open, as viewed from one side in a third direction. FIG. [Diagram 3] 11 is a perspective view of the fixing unit as viewed from the other side in the third direction. FIG. [Figure 4] FIG. 1A is a diagram showing a guide surface on one side of a main body housing, a first recess, a second recess, a first spring, and a fixing unit, and FIG. 1B is an enlarged view of the vicinity of a first boss. [Diagram 5] 4A and 4B are diagrams showing the side plates and bosses of the fixing unit, the metal plate of the main body housing, and the springs. [Figure 6] FIG. 4 is a perspective view showing a first boss and a first side plate. [Figure 7] 11 is a diagram showing a force that the first boss receives from a first spring, and a force that the first input gear of the fixing unit receives from a first drive gear of the main body housing. FIG. [Figure 8] This is a diagram showing one side of the third direction when the fixing unit is attached to the main body housing, in which (a) shows the state in which the first boss is guided by the first guide surface, and (b) shows the state in which the first boss has reached the second guide surface. [Figure 9] This is a diagram showing one side of the third direction when the fixing unit is attached to the main body housing, in which (a) shows the state in which the first boss is disengaged from the one-side guide surface, and (b) shows the state in which the first boss is inserted into the first recess. [Figure 10] This is a figure showing the other side of the third direction when the fixing unit is attached to the main body housing, where (a) is a figure showing the state before the unit connector is connected to the main body connector, and (b) is a figure showing the state when the third boss has reached the second guide surface. [Figure 11]This is a figure showing the other side of the third direction when the fixing unit is attached to the main body housing, in which (a) shows the state in which the third boss is disengaged from the other side guide surface, and (b) shows the state in which the third boss is inserted into the third recess. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 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, an image forming section 30, and a sheet discharge section 90.

[0030] 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.

[0031] 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 image forming unit 30.

[0032] The image forming section 30 includes an exposure device 40, a process unit PU, a transfer unit 70, and a fixing unit 80.

[0033] The exposure device 40 is located above the process unit PU. The exposure device 40 emits a light beam to expose the surface of the photosensitive drum 51.

[0034] The process unit PU is located between the sheet tray 21 and the exposure device 40. The process unit PU is attachable to and 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. The process unit PU includes a drum cartridge 50 and a plurality of toner cartridges 60.

[0035] 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.

[0036] The drum frame 53 supports the photosensitive drum 51 and the charger 52. The drum frame 53 is movably supported by the main body casing 10. A toner cartridge 60 is detachably attached to the drum frame 53.

[0037] 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.

[0038] 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.

[0039] The transfer unit 70 is located between the sheet tray 21 and the process unit PU. 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.

[0040] 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).

[0041] 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.

[0042] 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.

[0043] 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 to which the toner image has been transferred is transported between the heating roller 81 and the pressure roller 82. As a result, the fixing unit 80 thermally fixes the toner image to the sheet S.

[0044] 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.

[0045] 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, when directions are described, a first direction, a second direction, and a third direction shown in FIG. 2 are used.

[0046] The first direction is a direction along the attachment / detachment direction of the fixing unit 80 relative to the main body housing 10. 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 attached to the main body housing 10 from one side toward the other side in the first direction.

[0047] The second direction is a direction that intersects with the first direction. In this embodiment, the second direction is a direction that is perpendicular to 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.

[0048] The third direction is a direction perpendicular to both the first direction and the second direction. In this embodiment, the third direction is a direction along the left-right direction of the image forming apparatus 1. One side of the third direction corresponds to the left side of the image forming apparatus 1, and the other side of the third direction corresponds to the right side of the image forming apparatus 1. Arrows indicating each direction in the drawings point to one side in each direction.

[0049] 2 and 3, the fixing device 80 has a first boss 120A, a second boss 130A, a third boss 120B, a fourth boss 130B, a protrusion 140, and a unit connector 170. The image forming apparatus 1 further includes a main body connector 160.

[0050] The first boss 120A and the third boss 120B are parts that come 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 with respect to the main body housing 10. The second boss 130A and the fourth boss 130B are parts that come into contact with the main body housing 10 when the fixing unit 80 is attached to the main body housing 10, thereby stopping the rotation of the fixing unit 80 about the bosses 120A and 120B.

[0051] The first boss 120A has a columnar shape. The second boss 130A has a cylindrical shape. The second boss 130A is located on one side of the first boss 120A in the first direction. The second boss 130A is located on one side of the first boss 120A in the second direction. The first boss 120A and the second boss 130A extend in the third direction. The first boss 120A and the second boss 130A are located on one side of the fixing device 80 in the third direction. The first boss 120A and the second boss 130A protrude from a surface of the fixing device 80 on one side in the third direction to one side in the third direction.

[0052] The third boss 120B has a structure symmetrical to the first boss 120A in the third direction. The fourth boss 130B has a structure symmetrical to the second boss 130A in the third direction. The third boss 120B and the fourth boss 130B are located on the other side of the fixing unit 80 in the third direction. The third boss 120B and the fourth boss 130B protrude from the surface on the other side of the fixing unit 80 in the third direction to the other side in the third direction.

[0053] The protruding portion 140 is located on the surface of the fixing unit 80 on the other side in the first direction. The protruding portion 140 is located on one side in the third direction and protrudes toward the other side in the first direction. The cross section of the protruding portion 140 perpendicular to the first direction has a cross shape. The tip portion of the protruding portion 140 on the other side in the first direction is thinner than the base portion on one side in the first direction.

[0054] The unit connector 170 is a connector that is connected to the main body connector 160 when the fixing unit 80 is attached to the main body housing 10. The unit connector 170 is located on the other side of the fixing unit 80 in the third direction. The main body connector 160 is a floating connector that is held by the main body housing 10 so as to be movable relative to the main body housing 10. When the main body connector 160 and the unit connector 170 are connected, power can be supplied to the heater 81A of the heating roller 81.

[0055] As shown in FIG. 10( a ), the main body connector 160 has a main body housing 161 , a first guide pin 163 , and a second guide pin 164 .

[0056] Main body housing 161 is a portion that holds the terminals. Main body housing 161 is located between first guide pin 163 and second guide pin 164 in the second direction. First guide pin 163 and second guide pin 164 extend in the first direction. The tips of first guide pin 163 and second guide pin 164 are each located on one side of main body housing 161 in the first direction.

[0057] The unit connector 170 has a unit housing 171 , a first guide hole 173 , and a second guide hole 174 .

[0058] Unit housing 171 is a part that holds terminals and fits into main body housing 161. The terminals of unit connector 170 and the terminals of main body connector 160 are connected by fitting unit housing 171 into main body housing 161. Unit housing 171 is located between first guide hole 173 and second guide hole 174 in the second direction.

[0059] The first guide hole 173 is a hole that receives the first guide pin 163. The second guide hole 174 is a hole that receives the second guide pin 164. The unit housing 171, the first guide hole 173, and the second guide hole 174 are open toward the other side in the first direction.

[0060] 4(a), the main body housing 10 has a one-side guide surface 310A as a guide surface, a first recess 320A, and a second recess 330A. The one-side guide surface 310A, the first recess 320A, and the second recess 330A are located on one side of the main body housing 10 in the third direction.

[0061] The first recess 320A is a recess shaped to be recessed toward one side in the second direction. The first boss 120A of the fixing device 80 is located in the first recess 320A when the fixing device 80 is attached to the main body housing 10. The first boss 120A 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. The main body housing 10 has a first metal plate 300A as a metal plate. The first metal plate 300A includes a first portion 301 that is perpendicular to the third direction. The first recess 320A is formed in the first portion 301 of the first metal plate 300A.

[0062] The first recess 320A 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 320A. The first reference surface 321 is perpendicular to the second direction.

[0063] The second reference surface 322 is a surface on one side in the first direction of the first recess 320A. 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.

[0064] The stopper surface 323 is a surface on the other side in the first direction of the first recess 320A. 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 120A 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.

[0065] 4(b), in the first recess 320A, the distance D1 between the second reference surface 322 and the stopper surface 323 is larger than the size D2 of the first boss 120A in the direction perpendicular to the second direction. Specifically, in the first recess 320A, the distance D1 between the second reference surface 322 and the stopper surface 323 is larger than the diameter D2 of the first boss 120A.

[0066] 4(a), the one-side guide surface 310A is a surface that guides the first boss 120A toward the first recess 320A when the fixing unit 80 is attached to the main body housing 10. The one-side guide surface 310A has a first guide surface 311, a second guide surface 312, and a third guide surface 313.

[0067] The first guide surface 311 extends in the first direction. The first guide surface 311 is formed on the first side frame 14 located on one side of the main body housing 10 in the third direction.

[0068] The second guide surface 312 and the third guide surface 313 are formed on the first portion 301 of the first metal plate 300A. The second guide surface 312 is located between the first guide surface 311 and the first recess 320A. More specifically, 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 in the first direction to the other side so as to be located on the other side in the second direction.

[0069] The third guide surface 313 is located between the second guide surface 312 and the first recess 320A. 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 320A on the other side in the second direction.

[0070] The second recess 330A is a recess shaped to be recessed toward the other side in the first direction. The second recess 330A is formed in the first side frame 14 of the main body housing 10. The second boss 130A is inserted into the second recess 330A when the fixing device 80 is attached to the main body housing 10. The second boss 130A 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 330A is open toward one side in the first direction. The second recess 330A has a bottom surface 331, a first regulating surface 332, and a second regulating surface 333.

[0071] The bottom surface 331 is the surface on the other side in the first direction of the second recess 330A. The first and second regulating surfaces 332 and 333 are surfaces for stopping the rotation of the fixing device 80 around the first boss 120A. 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 130A that enters the second recess 330A is disposed between the first regulating surface 332 and the second regulating surface 333.

[0072] The image forming apparatus 1 further includes a first spring SP1 as a spring. As an example, the first spring SP1 is a torsion coil spring. The first spring SP1 has a pressing arm AR. When the fixing unit 80 is attached to the main body housing 10, the pressing arm AR of the first spring SP1 presses the first boss 120A located in the first recess 320A toward one side in the first direction and toward one side in the second direction.

[0073] When pressed by the first spring SP1, the first boss 120A contacts the first reference surface 321 of the first recess 320A and the second reference surface 322 of the first recess 320A. On the other hand, when pressed by the first spring SP1, the first boss 120A does not contact the stopper surface 323 of the first recess 320A. In other words, when pressed by the first spring SP1, the first boss 120A has a gap between it and the stopper surface 323.

[0074] As shown in FIG. 11(b), the main body housing 10 has the other side guide surface 310B, the third recess 320B, and the fourth recess 330B. The other side guide surface 310B, the third recess 320B, and the fourth recess 330B are located on the other side of the main body housing 10 in the third direction. In this embodiment, the third recess 320B has a structure symmetrical to the first recess 320A in the third direction. The other side guide surface 310B has a structure symmetrical to the one side guide surface 310A in the third direction. The fourth recess 330B has a structure symmetrical to the second recess 330A in the third direction. Therefore, the same reference numerals are used in the specification and drawings for parts having the same functions, and the description thereof is omitted.

[0075] The third boss 120B of the fixing device 80 is located in the third recess 320B when the fixing device 80 is attached to the main body housing 10. The main body housing 10 has a second metal plate 300B. In this embodiment, the second metal plate 300B has a structure symmetrical to the first metal plate 300A in the third direction. The third recess 320B is formed in the first portion 301 of the second metal plate 300B. When the third boss 120B of the fixing device 80 attached to the main body housing 10 comes into contact with the stopper surface 323 of the third recess 320B, the stopper surface 323 prevents the fixing device 80 from moving further to the other side in the first direction.

[0076] The other-side guide surface 310B is a surface that guides the third boss 120B toward the third recess 320B when the fixing unit 80 is attached to the main body housing 10. A first guide surface 311 of the other-side guide surface 310B is formed on the second side frame 15 located on the other side in the third direction of the main body housing 10. A second guide surface 312 and a third guide surface 313 of the other-side guide surface 310B are formed on the first portion 301 of the second metal plate 300B.

[0077] The fourth recess 330B is formed in the second side frame 15 of the main body housing 10. The fourth boss 130B fits into the fourth recess 330B when the fixing unit 80 is attached to the main body housing 10. The first restriction surface 332 and the second restriction surface 333 of the fourth recess 330B are surfaces for stopping the fixing unit 80 from rotating around the third boss 120B. The fourth boss 130B that fits into the fourth recess 330B is disposed between the first restriction surface 332 and the second restriction surface 333.

[0078] The image forming apparatus 1 further includes a second spring SP2. As an example, the second spring SP2 is a torsion coil spring. When the fixing unit 80 is attached to the main body housing 10, the pressing arm AR of the second spring SP2 presses the third boss 120B located in the third recess 320B toward one side in the first direction and toward one side in the second direction.

[0079] When pressed by the second spring SP2, the third boss 120B comes into contact with a first reference surface 321 of the third recess 320B and a second reference surface 322 of the third recess 320B. On the other hand, when pressed by the second spring SP2, the third boss 120B does not come into contact with a stopper surface 323 of the third recess 320B.

[0080] As shown in FIG. 4(a) and FIG. 5, the main body housing 10 has a long hole 340 as a hole. The long hole 340 is a hole with a bottom that is long in the second direction. The long hole 340 has a shape that is recessed toward the other side in the first direction. The long hole 340 opens toward one side in the first direction. The protrusion 140 fits into the long hole 340 when the fixing device 80 is attached to the main body housing 10. The fixing device 80 is positioned in the third direction by the protrusion 140 fitting into the long hole 340.

[0081] The dimension of the long hole 340 in the third direction is approximately the same as the dimension of the protruding portion 140 in the third direction. The protruding portion 140 fits into the long hole 340 in the third direction. The long hole 340 restricts the movement of the protruding portion 140 in the third direction. As a result, the long hole 340 restricts the movement of the fixing unit 80 in the third direction. The dimension of the long hole 340 in the second direction is larger than the dimension of the protruding portion 140 in the second direction.

[0082] 5, the fixing unit 80 has a first side plate 110A and a second side plate 110B as side plates. The first side plate 110A and the second side plate 110B are members that support the heating roller 81. The first side plate 110A and the second side plate 110B have a circular through hole 111 (see FIG. 6) that supports the heating roller 81.

[0083] The first side plate 110A and the second side plate 110B are each made of a metal plate. The first side plate 110A is located on one side in the third direction of the heating roller 81 and the pressure roller 82. The second side plate 110B is located on the other side in the third direction of the heating roller 81 and the pressure roller 82. The protruding portion 140 is provided on one side in the third direction of a portion of the first side plate 110A that is perpendicular to the third direction.

[0084] As shown in Figures 5 and 6, the first boss 120A and the third boss 120B are each made of a metal rod. The first boss 120A has an end on the other side in the third direction fixed to the first side plate 110A by crimping. The third boss 120B has an end on one side in the third direction fixed to the second side plate 110B by crimping. Note that Figure 6 shows the first boss 120A and the first side plate 110A as representatives.

[0085] 5, the first metal plate 300A of the main body housing 10 is located on one side of the first side plate 110A in the third direction when the fixing unit 80 is attached to the main body housing 10. The first spring SP1 presses the first boss 120A on one side of the first metal plate 300A in the third direction. The first spring SP1 presses the tip of the first boss 120A, which is a portion of the first boss 120A farther from the first side plate 110A than the first metal plate 300A, rather than a portion of the first boss 120A located between the first metal plate 300A and the first side plate 110A.

[0086] Furthermore, the second metal plate 300B of the main body housing 10 is located on the other side in the third direction of the second side plate 110B when the fixing unit 80 is attached to the main body housing 10. The second spring SP2 presses the third boss 120B on the other side in the third direction of the second metal plate 300B. The second spring SP2 presses the tip of the third boss 120B, which is a portion of the third boss 120B farther from the second side plate 110B than the second metal plate 300B, rather than a portion of the third boss 120B located between the second metal plate 300B and the second side plate 110B.

[0087] 7, the image forming apparatus 1 further includes a first drive gear R1 and a second drive gear R3. The fixing unit 80 further includes a first input gear R2 and a second input gear R4.

[0088] The first drive gear R1 and the second drive gear R3 are supported by the main body housing 10. The first drive gear R1 is rotatable about a first axis 1X extending in the third direction. The second drive gear R3 is rotatable about a third axis 3X extending in the third direction.

[0089] The first input gear R2 and the second input gear R4 are located on one side of the fixing device 80 in the third direction. The first input gear R2 is rotatable around a second shaft 2X extending in the third direction. The first input gear R2 meshes with the first drive gear R1 when the fixing device 80 is attached to the main body housing 10. When the first drive gear R1 receives a driving force from a driving source (not shown) and rotates counterclockwise in FIG. 7, the first input gear R2 rotates clockwise. This causes the heating roller 81 to rotate clockwise. The pressure roller 82 rotates following the heating roller 81.

[0090] The first input gear R2 is disposed on the other side in the third direction relative to the protruding portion 140 (see FIG. 3). In other words, the protruding portion 140 is provided on one side in the third direction relative to the first input gear R2.

[0091] The second input gear R4 is rotatable about a fourth shaft 4X extending in the third direction. The second input gear R4 meshes with the second drive gear R3 when the fixing unit 80 is attached to the main body housing 10. The fixing unit 80 further has a cam 86. The cam 86 rotates to move at least one of the heating roller 81 and the pressure roller 82, thereby changing the nip pressure that nips the sheet S. The cam 86 is rotatable about the fourth shaft 4X.

[0092] When the second driving gear R3 receives a driving force and rotates counterclockwise, the second input gear R4 rotates clockwise. This causes the cam 86 to rotate clockwise. When the second driving gear R3 receives a driving force and rotates clockwise, the second input gear R4 rotates counterclockwise. This causes the cam 86 to rotate counterclockwise.

[0093] In this embodiment, the second boss 130A is located on a straight line L1 passing through the first axis 1X and the second axis 2X when viewed from the third direction. The second boss 130A is located on a straight line L2 passing through the third axis 3X and the fourth axis 4X when viewed from the third direction. The first axis 1X and the second axis 2X are located on the other side in the first direction of the straight line L2.

[0094] The first boss 120A is located on the other side of the second shaft 2X in the first direction. The first boss 120A is located on one side of the second shaft 2X in the second direction. The first input gear R2 meshes with the first driving gear R1 at a position on the other side of the second shaft 2X in the first direction. The first input gear R2 meshes with the first driving gear R1 at a position on the other side of the second shaft 2X in the second direction.

[0095] When the first driving gear R1 receives a driving force and rotates counterclockwise, it presses the first input gear R2 with a force F3 toward the other side in the first direction and toward one side in the second direction. The first spring SP1 presses the first boss 120A located in the first recess 320A with a force F1 toward one side in the first direction and toward one side in the second direction. A force F11, which is a first-direction component of the force F1 with which the first spring SP1 presses the first boss 120A, is greater than a force F31, which is a first-direction component of the force F3 with which the first driving gear R1 presses the first input gear R2.

[0096] The other side of the fixing unit 80 in the third direction does not receive a force from the gear supported by the main body housing 10. Therefore, in this embodiment, the force F2 with which the second spring SP2 (see FIG. 11(b)) presses the third boss 120B located in the third recess 320B is smaller than the force F1 with which the first spring SP1 presses the first boss 120A located in the first recess 320A. The biasing force of the second spring SP2 is smaller than the biasing force of the first spring SP1.

[0097] 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 in the first direction to the other side, the first boss 120A contacts the first guide surface 311 of the one-side guide surface 310A on one side of the fixing unit 80 in the third direction and is guided by the first guide surface 311.

[0098] 8(b), the second boss 130A comes into contact with the first restriction surface 332 of the second recess 330A and is guided by the first restriction surface 332. When the first boss 120A comes into contact with the second guide surface 312, the first boss 120A moves obliquely upward from one side to the other side in the first direction while being guided by the second guide surface 312.

[0099] 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 120A is guided by the second guide surface 312, and then guided in the direction along the first direction by the third guide surface 313. The protrusion 140 is inserted into the elongated hole 340 while the first boss 120A is being guided by the one-side guide surface 310A.

[0100] 9(b), the first boss 120A enters the first recess 320A due to the biasing force of the first spring SP1. In detail, the first boss 120A guided by the third guide surface 313 presses the pressing arm AR of the first spring SP1, causing the pressing arm AR to elastically deform to the other side in the first direction.

[0101] Thereafter, when the first boss 120A comes off the third guide surface 313, the first boss 120A is pressed to one side in the first direction and one side in the second direction by the restoring force of the first spring SP1, and enters the first recess 320A. At this time, the second boss 130A is in the second recess 330A.

[0102] On the other hand, as shown in FIG. 10(a), when the fixing unit 80 is inserted into the main housing 10, on the other side of the fixing unit 80 in the third direction, the third boss 120B comes into contact with the first guide surface 311 of the other side guide surface 310B and is guided by the first guide surface 311.

[0103] 10(b), the fourth boss 130B comes into contact with the first restriction surface 332 of the fourth recess 330B and is guided by the first restriction surface 332. The first guide hole 173 of the unit connector 170 receives the first guide pin 163 of the main body connector 160, and the second guide hole 174 receives the second guide pin 164. When the third boss 120B comes into contact with the second guide surface 312, the third boss 120B is guided by the second guide surface 312 to move obliquely upward from one side to the other side in the first direction.

[0104] 11(a), after being guided by second guide surface 312, third boss 120B is guided in the direction along the first direction by third guide surface 313. Furthermore, unit housing 171 of unit connector 170 fits into main body housing 161 of main body connector 160, and terminals of unit connector 170 and terminals of main body connector 160 come into contact with each other.

[0105] 11(b), the third boss 120B enters the third recess 320B due to the biasing force of the second spring SP2. In detail, the third boss 120B guided by the third guide surface 313 presses the pressing arm AR of the second spring SP2, causing the pressing arm AR to elastically deform to the other side in the first direction.

[0106] Thereafter, when the third boss 120B comes off the third guide surface 313, the third boss 120B is pressed to one side in the first direction and one side in the second direction by the restoring force of the second spring SP2, and enters the third recess 320B. At this time, the fourth boss 130B enters the fourth recess 330B. In addition, the unit housing 171 fits into the main body housing 161, so that the unit connector 170 is connected to the main body connector 160.

[0107] When the fixing unit 80 is attached to the main body housing 10, the bosses 120A, 120B are pressed against the first reference surface 321 of the recesses 320A, 320B by the biasing forces of the springs SP1, SP2, and are pressed against the second reference surface 322 of the recesses 320A, 320B by gravity and the biasing forces of the springs SP1, SP2. By pressing the bosses 120A, 120B 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.

[0108] In this embodiment, when the fixing unit 80 is attached to the main body housing 10, a load is applied to the other end of the fixing unit 80 in the third direction due to frictional resistance when connecting the unit connector 170 and the main body connector 160. Therefore, the biasing force of the second spring SP2 is smaller than the biasing force of the first spring SP1 (see FIG. 7).

[0109] This reduces the difference between the first load required to mount the fuser 80 to the main body housing 10 at one end of the fuser 80 in the third direction and the second load required to mount the fuser 80 to the main body housing 10 at the other end of the fuser 80 in the third direction. The first load is mainly a load received from the first spring SP1 when the first boss 120A enters the first recess 320A. The second load is mainly a sum of a load received from the second spring SP2 when the third boss 120B enters the third recess 320B and a load due to frictional resistance when the unit connector 170 and the main body connector 160 are connected. It is desirable that the first load and the second load are substantially the same.

[0110] In other words, the second spring SP2 needs a certain degree of biasing force to determine the position of the third boss 120B (the fixing device 80) in the first and second directions. Meanwhile, since a load is applied to the other end of the fixing device 80 in the third direction due to frictional resistance when connecting the unit connector 170 and the main body connector 160, in this embodiment, in order to reduce the difference between the first load and the second load, the biasing force of the first spring SP1 is made larger than the biasing force of the second spring SP2.

[0111] Furthermore, since one side of the fixing unit 80 in the third direction receives a force from the first driving gear R1 supported by the main body housing 10, the biasing force of the first spring SP1 is made larger than the biasing force of the second spring SP2.

[0112] As shown in FIG. 5, the protrusion 140 is inserted into the elongated hole 340, so that the fixing unit 80 is positioned in the third direction.

[0113] Next, the effects of the image forming apparatus 1 will be described. By providing the first spring SP1 that presses the first boss 120A located in the first recess 320A toward one side in the first direction and toward one side in the second direction when the fixing unit 80 is attached to the main body housing 10, the first boss 120A is less likely to come off the first recess 320A. This makes it possible to prevent the fixing unit 80 from moving from the attachment position where it is attached to the main body housing 10.

[0114] In this embodiment, the first spring SP1 presses the first boss 120A in the first recess 320A toward one side in the first direction and toward one side in the second direction, and the second spring SP2 presses the third boss 120B in the third recess 320B toward one side in the first direction and toward one side in the second direction, so that the bosses 120A and 120B are less likely to come off the corresponding recesses 320A and 320B. This makes it possible to further prevent the fixing unit 80 from moving from the mounting position.

[0115] Since the bosses 120A, 120B do not come into contact with the stopper surfaces 323 of the recesses 320A, 320B when pressed by the springs SP1, SP2, the fixing unit 80 can be positioned with high accuracy relative to the main body housing 10.

[0116] When the bosses 120A and 120B are pressed by the springs SP1 and SP2, they come into contact with the first reference surface 321 and the second reference surface 322 of the recesses 320A and 320B, so that the bosses 120A and 120B can be positioned by contacting the two surfaces. This allows the fixing unit 80 to be positioned with respect to the main body housing 10 with high accuracy.

[0117] The springs SP1 and SP2 are torsion coil springs, so that the pressing force and stroke can be set appropriately.

[0118] By inclining second guide surface 312 so as to be positioned on the other side in the second direction as it moves from one side to the other side in the first direction, the positions of first guide surface 311 and recesses 320A, 320B in the second direction can be made substantially the same. This makes it possible to make the posture of fuser 80 when bosses 120A, 120B are guided by first guide surface 311 during attachment substantially the same as the posture of fuser 80 after attachment when bosses 120A, 120B enter recesses 320A, 320B.

[0119] By forming the recesses 320A and 320B in the metal plates 300A and 300B provided in the main body housing 10, the fixing unit 80 can be positioned with respect to the highly rigid metal plates 300A and 300B.

[0120] The first metal plate 300A is positioned on one side in the third direction of the first side plate 110A to which the first boss 120A is fixed by crimping, and the first spring SP1 presses the first boss 120A on one side in the third direction of the first metal plate 300A, thereby reducing the load on the crimped portion of the first boss 120A compared to when the spring presses the first boss 120A between the first metal plate 300A and the first side plate 110A.

[0121] Similarly, the second metal plate 300B is positioned on the other side in the third direction of the second side plate 110B to which the third boss 120B is fixed by crimping, and the second spring SP2 presses the third boss 120B on the other side in the third direction of the second metal plate 300B, thereby reducing the load on the crimped portion of the third boss 120B.

[0122] By positioning bosses 120A, 120B on the other side in the first direction of nip position NP between heating roller 81 and pressure roller 82, fixing device 80 can be positioned relative to main body housing 10 based on the rear side of fixing device 80 in the mounting direction.

[0123] Since the fixing device 80 has the bosses 130A, 130B and the main housing 10 has the recesses 330A, 330B, rotation of the fixing device 80 around the bosses 120A, 120B can be restricted when the bosses 130A, 130B are inserted into the recesses 330A, 330B.

[0124] Since the fixing unit 80 has the protruding portion 140 and the main body housing 10 has the elongated hole 340 that restricts the movement of the protruding portion 140 in the third direction, the movement of the fixing unit 80 in the third direction can be restricted. This allows the fixing unit 80 to be positioned in the third direction. Also, since the protruding portion 140 is disposed on one side in the third direction, the fixing unit 80 can be positioned in the third direction at a position close to the first input gear R2.

[0125] Since the dimension of the long hole 340 in the second direction is larger than the dimension of the protruding portion 140 in the second direction, even if the fixing unit 80 moves in the second direction when the fixing unit 80 is attached to the main body housing 10, interference between the protruding portion 140 and the main body housing 10 can be suppressed. In addition, since the tip of the protruding portion 140 is narrowed, the protruding portion 140 can be guided into the long hole 340 when the fixing unit 80 is attached to the main body housing 10, and the fixing unit 80 can be prevented from being significantly shifted in the second direction.

[0126] Because the first direction component force F11 of the force F1 with which the first spring SP1 presses on the first boss 120A is greater than the first direction component force F31 of the force F3 with which the first drive gear R1 presses on the first input gear R2, the first boss 120A can be prevented from moving to the other side in the first direction when the first drive gear R1 rotates.

[0127] Since the difference between the first load required to mount the fixing unit 80 in the main body housing 10 at one end of the fixing unit 80 in the third direction and the second load required to mount the fixing unit 80 in the main body housing 10 at the other end of the fixing unit 80 in the third direction is small, it is possible to suppress tilt of the fixing unit 80 when mounting the fixing unit 80 in the main body housing 10. This makes it easy to mount the fixing unit 80 in the main body housing 10.

[0128] Although the embodiment has been described above, the image forming apparatus can be modified as appropriate as exemplified below.

[0129] In the above embodiment, the first spring SP1 is a torsion coil spring, but for example, the spring that presses the boss may be a leaf spring, a compression coil spring, etc. The same applies to the second spring.

[0130] In the above embodiment, the first side plate 110A of the fixing device 80 is a member that supports the heating roller 81 (heating rotator), but for example, the first side plate may be a member that supports a pressure roller (pressure rotator). The first side plate may also be a member that supports both the heating rotator and the pressure rotator. The same applies to the second side plate.

[0131] In the above embodiment, the first input gear R2 drives the heating roller 81 (heating rotor), and the pressure roller 82 (pressure rotor) rotates in conjunction with the heating roller 81. However, for example, the first input gear may drive the pressure rotor, and the heating rotor may rotate in conjunction with the pressure rotor.

[0132] In the above embodiment, the second direction is a direction perpendicular to the first direction, but for example, the second direction does not have to be perpendicular to the first direction. In other words, in the above embodiment, the first recess 320A is shaped to be recessed toward the lower side of the image forming apparatus 1, but for example, the first recess may be shaped to be recessed diagonally downward toward the front. The same applies to the third recess. Furthermore, in the above embodiment, the first direction, which is the attachment / detachment direction of the fixing unit 80, is a direction along the front-rear direction of the image forming apparatus 1, but for example, the first direction may be a direction inclined with respect to the horizontal direction.

[0133] In the above embodiment, the first side plate 110A is made of metal, but the first side plate may be made of resin, for example. Also, in the above embodiment, the first boss 120A is made of metal, but the first boss may be made of resin, for example. Also, the first boss may be molded integrally with the first side plate. Also, the fixing unit does not have a first side plate, and the first boss may be provided on, for example, the frame of the fixing unit. The same applies to the second side plate and the third boss.

[0134] In the above embodiment, the first metal plate 300A is configured to have the first portion 301 perpendicular to the third direction, but for example, the first metal plate may have a first portion and a second portion extending from the first portion in the third direction. The same applies to the second metal plate.

[0135] In the above embodiment, the first boss 120A is in contact with the first reference surface 321 and the second reference surface 322 of the first recess 320A, but is not in contact with the stopper surface 323. However, for example, the first boss may be in contact with three surfaces of the first recess. The first boss may be fitted into the first recess. The same applies to the third boss and the third recess.

[0136] In the above embodiment, the slot 340 (hole) is a bottomed hole, but for example, the hole into which the protruding portion of the fixing unit fits may be a hole penetrating in the first direction.

[0137] 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.

[0138] 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. Also, the image forming device may be a copier, a multifunction device, etc.

[0139] The elements described in the above embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0140] 1. Image forming device 10 Main unit housing 80 Fixing unit 81 Heating roller 82 Pressure roller 120A 1st Boss 320A First recess 321 1st reference plane 322 2nd reference plane SP1 First spring

Claims

1. A main body housing; An image forming apparatus including a fixing unit having a heating rotator and a pressure rotator, the fixing unit being mountable from one side to the other side in a first direction relative to the main body housing, the main body housing has a first recess having a shape recessed toward one side in a second direction intersecting the first direction, the fixing unit has a first boss extending in a third direction perpendicular to both the first direction and the second direction, the first boss being located within the first recess when the fixing unit is attached to the main body housing; The image forming apparatus further comprises a spring that presses the first boss located in the first recess when the fixing unit is attached to the main body housing toward one side in the first direction and one side in the second direction.

2. a distance between a surface of the first recess on one side in the first direction and a surface of the first recess on the other side in the first direction is larger than a size of the first boss in a direction perpendicular to the second direction, 2 . The image forming apparatus according to claim 1 , wherein the first boss does not come into contact with a surface of the first recess on the other side in the first direction when the first boss is pressed by the spring.

3. 2. The image forming apparatus according to claim 1, wherein the first boss contacts a surface of the first recess on one side in the first direction and a surface of the first recess on one side in the second direction when pressed by the spring.

4. 2. The image forming apparatus according to claim 1, wherein the spring is a torsion coil spring.

5. the main body housing has a guide surface that guides the first boss toward the first recess when the fixing unit is attached to the main body housing, The guide surface is A first guide surface extending in the first direction; 2. The image forming apparatus according to claim 1, further comprising: a second guide surface located between the first guide surface and the first recess, the second guide surface inclining from one side in the first direction to the other side in the second direction.

6. the main body housing has a metal plate including a first portion perpendicular to the third direction, The image forming apparatus according to claim 1 , wherein the first recess is formed in the first portion.

7. the fixing unit has a side plate supporting at least one of the heating rotator and the pressure rotator, the side plate being located on one side of the heating rotator and the pressure rotator in the third direction; the first boss is fixed to the side plate by caulking, the metal plate is located on one side of the side plate in the third direction, 7. The image forming apparatus according to claim 6, wherein the spring presses the first boss on one side of the metal plate in the third direction.

8. 2. The image forming apparatus according to claim 1, wherein the first boss is located on the other side in the first direction from a nip position between the heating rotator and the pressure rotator.

9. the fixing unit has a second boss extending in the third direction and located on one side of the nip position in the first direction, 9. The image forming apparatus according to claim 8, wherein the main body housing has a second recess that is recessed toward the other side in the first direction, and into which the second boss fits when the fixing unit is attached to the main body housing.

10. the fixing unit has a protruding portion protruding to the other side in the first direction, 2. The image forming apparatus according to claim 1, wherein the main body housing has a hole into which the protrusion fits when the fixing unit is attached to the main body housing, the hole restricting movement of the protrusion in the third direction.

11. 11. The image forming apparatus according to claim 10, wherein the dimension of the hole in the second direction is larger than the dimension of the protrusion in the second direction.

Images