Image forming apparatus

Abstract

To reliably locate a heating unit to a reference position when moving the heating unit from a position separate from a fixing unit to the reference position.SOLUTION: A heating unit 5a has a part to be engaged 542. A fixing unit 5b has an engagement part 553. The heating unit 5a or the fixing unit 5b has an engagement guide part 5420. A moving mechanism 7 holds the heating unit 5a in an inclined attitude when moving the heating unit 5a at a position separate from the fixing unit 5b. The engagement guide part 5420 causes the heating unit 5a to swing from the inclined attitude to a reference attitude while guiding the part to be engaged 542 to the engagement part 553. The engagement part 553 is engaged with the part to be engaged 542 to restrict the movement of the heating unit 5a in the vertical direction. Unit urging sections 6 maintain the engagement state of the engagement part 553 and the part to be engaged 542.SELECTED DRAWING: Figure 6

Description

Technical Field

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[0001] The present invention relates to an electrophotographic image forming apparatus including a heating unit and a fixing unit.

Background Art

[0002] An electrophotographic image forming apparatus transfers a toner image from an image carrier to a sheet and fixes the toner image on the sheet by a fixing device.

[0003] The fixing device may be divided into a heating unit having a heater and a fixing unit having a fixing member and a pressure roller. The heater heats the fixing member.

[0004] Also, it is known that the image forming apparatus includes a mechanism that moves the heating unit from a heating position to a retracted position in conjunction with an operation on an operation unit (see, for example, Patent Document 1). When the heating unit is retracted to the retracted position, the fixing unit can be pulled out from the main body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, it is important to arrange the heater at an appropriate position with respect to the fixing member in order to improve the heating efficiency of the fixing member by the heater. When an electromagnetic induction heating type heating device is adopted as the heater, the accuracy of the position of the heater is particularly important.

[0007] Furthermore, in order to enable the fixing unit to be pulled out from the main body, a moving mechanism is required to move the heating unit. The moving mechanism is equipped with a proximity function and a retraction function.

[0008] The proximity function is a function that positions the heating unit at a reference position close to the fixing unit. The retraction function is a function that moves the heating unit to a retracted position away from the fixing unit.

[0009] Therefore, the moving mechanism is required to ensure that the heating unit can be reliably positioned at the reference position when it moves from the retracted position to the reference position.

[0010] The object of the present invention is to provide an image forming apparatus that can reliably position the heating unit at a reference position when moving the heating unit from a position away from the fixing unit to a reference position. [Means for solving the problem]

[0011] An image forming apparatus according to one aspect of the present invention comprises a heating unit, a fixing unit, a moving mechanism, and a unit biasing unit. The heating unit has a heater and is arranged in a first direction within the main body. The fixing unit has a fixing member heated by the heater and a pressing member that biases a sheet toward the fixing member, and is arranged in the main body next to the heating unit and along the first direction. The moving mechanism moves the heating unit along a second direction, which is the direction of arrangement of the heating unit and the fixing unit. The unit biasing unit biases the heating unit toward the fixing unit when the heating unit is in a reference position in the second direction. The heating unit has an engaged portion. The fixing unit has an engaging portion. The heating unit or the fixing unit has an engaging guide portion. The engaging portion engages with the engaged portion when the heating unit is in the reference position. The engaging guide portion guides the engaged portion toward the engaging portion. The heating unit is connected to the moving mechanism so as to be able to swing between a reference position and a tilted position in which it is tilted diagonally downward toward the fixing unit. The moving mechanism holds the heating unit in the tilted position when moving the heating unit to a position further away from the fixing unit than the reference position. The engaging guide guides the engaged portion toward the engaging portion and swings the heating unit from the tilted position to the reference position when the heating unit moves toward the reference position. The engaging portion restricts the movement of the heating unit in the vertical direction intersecting the first direction and the second direction by engaging with the engaged portion. The unit biasing portion maintains the engaged state of the engaging portion and the engaged portion by biasing the heating unit. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an image forming apparatus that can reliably position the heating unit at a reference position when moving the heating unit from a position away from the fixing unit to a reference position. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a configuration diagram of an image forming apparatus according to an embodiment. [Figure 2] Figure 2 shows the configuration of the main part of the fixing device in the image forming apparatus according to the embodiment. [Figure 3] Figure 3 is a perspective view of the main frame of the image forming apparatus according to this embodiment. [Figure 4] Figure 4 is a side view showing the configuration of the heating unit and its surrounding area located at a reference position in the image forming apparatus according to the embodiment. [Figure 5] Figure 5 is a plan view showing the configuration of the heating unit and its surrounding area in an image forming apparatus according to an embodiment. [Figure 6] Figure 6 is a side view showing the configuration of the heating unit and its surrounding area located in the retracted position in the image forming apparatus according to the embodiment. [Figure 7] Figure 7 is a perspective view of the peripheral portion of the fixing unit and cover member in the image forming apparatus according to the embodiment. [Figure 8] Figure 8 shows the rear view and drive mechanism of the fixing unit in the image forming apparatus according to the embodiment. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention.

[0015] [Configuration of the image forming apparatus 10] The image forming apparatus 10 according to this embodiment performs printing using an electrophotographic method. The printing process is the process of forming an image on a sheet 900.

[0016] As shown in FIG. 1, the image forming apparatus 10 includes a sheet storage unit 2, a sheet conveyance device 3, and a printing device 4. The sheet conveyance device 3 and the printing device 4 are housed in the main body 1 which is a housing.

[0017] The sheet storage unit 2 can store a plurality of sheets 900. The sheet conveyance device 3 includes a sheet feeding device 30 and a plurality of sets of conveyance roller pairs 31.

[0018] The sheet feeding device 30 feeds the sheets 900 in the sheet storage unit 2 one by one to the conveyance path 300. The conveyance path 300 is a passage for the sheets 900.

[0019] The plurality of sets of conveyance roller pairs 31 convey the sheets 900 along the conveyance path 300. The plurality of sets of conveyance roller pairs 31 includes a discharge roller pair 3la (see FIG. 1). The discharge roller pair 31a discharges the sheet 900 with an image formed thereon from the conveyance path 300 onto the discharge tray la.

[0020] The printing device 4 performs the printing process on the sheet 900 conveyed along the conveyance path 300. The image formed on the sheet 900 is a toner image.

[0021] The printing device 4 includes an optical scanning unit 40, one or more image forming units 4x, a transfer device 45, and a fixing device 5. The image forming unit 4x includes a photosensitive member 41, a charging device 42, a developing device 43, and a drum cleaning device 44.

[0022] The charging device 42 charges the surface of the photosensitive member 41. The optical scanning unit 40 scans the surface of the charged photosensitive member 41 with a beam of light. Thereby, the optical scanning unit 40 forms an electrostatic latent image on the surface of the photosensitive member 41.

[0023] The developing device 43 develops the electrostatic latent image into a toner image by supplying toner to the surface of the photosensitive member 41. The transfer device 45 transfers the toner image formed on the surface of the photosensitive member 41 to the sheet 900.

[0024] The transfer device 45 transfers the electrostatic latent image to the sheet 900 at the transfer position P1 in the transport path 300.

[0025] In this embodiment, the printing apparatus 4 is a tandem-type color printing apparatus equipped with multiple image forming units 4x. The transfer apparatus 45 includes an intermediate transfer belt 450, multiple primary transfer devices 451, a secondary transfer device 452, and a belt cleaning device 453.

[0026] In the example shown in Figure 1, the printing device 4 comprises four image forming units 4x corresponding to four toner colors: yellow, magenta, cyan, and black. The transfer device 45 comprises four primary transfer units 451 corresponding to the four image forming units 4x.

[0027] The intermediate transfer belt 450 is rotatably supported by a plurality of support rollers 454. One of the support rollers 454 is rotated by a belt drive device (not shown), thereby causing the intermediate transfer belt 450 to rotate.

[0028] Each primary transfer device 451 transfers the toner image formed on the surface of the photoreceptor 41 in each image forming unit 4x to the surface of the intermediate transfer belt 450. As a result, a composite toner image, formed by combining the four toner images, is created on the surface of the intermediate transfer belt 450.

[0029] The intermediate transfer belt 450 rotates while carrying the synthesized toner image. The secondary transfer device 452 transfers the synthesized toner image formed on the surface of the intermediate transfer belt 450 to the sheet 900 at the transfer position P1.

[0030] The drum cleaning device 44 removes primary waste toner from the surface of the photoreceptor 41. The primary waste toner is the toner remaining on the surface of the photoreceptor 41 that has passed through the primary transfer device 451.

[0031] The belt cleaning device 453 removes secondary waste toner from the surface of the intermediate transfer belt 450. The secondary waste toner is the toner remaining on the surface of the intermediate transfer belt 450 that has passed through the secondary transfer device 452.

[0032] The fixing device 5 heats and pressurizes the synthesized toner image on the sheet 900 at the fixing position P2 in the transport path 300. This causes the fixing device 5 to fix the synthesized toner image to the sheet 900. The fixing position P2 is located downstream of the transfer position P1 in the sheet transport direction.

[0033] As shown in Figure 2, the fixing device 5 includes a heater 51, a fixing belt 52, a fixing roller 520, a pressure roller 53, and a sheet separating member 5200.

[0034] The fixing belt 52 is a flexible cylindrical member that encloses the fixing roller 520. The fixing belt 52 is heated by the heater 51.

[0035] The fixing roller 520 is a cylindrical member that supports the fixing belt 52 from the inside. The fixing roller 520 has a cylindrical core portion 521 and an elastic portion 522 formed on the outer circumference of the core portion 521.

[0036] The fixing roller 520 is rotatably supported. The fixing belt 52 is rotatable together with the fixing roller 520.

[0037] The fixing belt 52 has a conductive base material, an elastic layer formed on the outer periphery of the base material, and a release layer formed on the outer periphery of the elastic layer.

[0038] The heater 51 is positioned opposite the outer circumferential surface of the fixing belt 52. In this embodiment, the heater 51 is an electromagnetic induction heating device. The heater 51 primarily heats the base material of the fixing belt 52 by electromagnetic induction.

[0039] The pressure roller 53 is rotatably supported. Like the fixing roller 520, the pressure roller 53 also has a cylindrical core portion 531 and an elastic portion 532 formed on the outer circumference of the core portion 531.

[0040] The pressure roller 53 is driven and rotated by a drive device (not shown). The fixing belt 52 and fixing roller 520 rotate in conjunction with the pressure roller 53.

[0041] The fixing belt 52 heats the toner image formed on the sheet 900. The pressure roller 53 applies pressure to the toner image toward the sheet 900.

[0042] The fixing belt 52 is an example of a fixing member that is heated by the heater 51. The pressure roller 53 is an example of a pressure member that biases the sheet 900 onto the fixing belt 52.

[0043] The sheet separation member 5200 separates the sheet 900 from the fixing belt 52 when the sheet 900 adheres to the fixing belt 52.

[0044] The discharge roller pair 31a can discharge the sheet 900 that has passed between the fixing belt 52 and the pressure roller 53 to the discharge tray 1a (see Figure 1).

[0045] In this embodiment, the fixing device 5 is divided into a heating unit 5a and a fixing unit 5b (see Figures 4 and 5). The heating unit 5a includes a heater 51. The fixing unit 5b includes a fixing roller 520, a fixing belt 52, and a pressure roller 53. The fixing unit 5b is located next to the heating unit 5a.

[0046] Furthermore, the discharge unit 32 is positioned above the fixing unit 5b (see Figure 1). The discharge unit 32 includes a pair of discharge rollers 31a and a sheet guide member. The sheet guide member guides the sheet 900 as it is transported from the fixing device 5 to the pair of discharge rollers 31a.

[0047] The discharge unit 32 is fixed to the main frame 1x. The discharge unit 32 is an example of a fixed unit that is fixed within the main body 1.

[0048] The heating unit 5a is positioned within the main body 1 along the first direction D1. The fixing unit 5b is also positioned within the main body 1 along the first direction D1.

[0049] In this embodiment, the first direction D1 is the depth direction of the image forming apparatus 10. When the fixing unit 5b is mounted on the main body 1, the first direction D1 is the direction along the centerline of rotation of the fixing belt 52 and the pressure roller 53.

[0050] The heating unit 5a and the fixing unit 5b are arranged side by side in the second direction D2. That is, the second direction D2 is the direction in which the heating unit 5a and the fixing unit 5b are arranged. The second direction D2 intersects the first direction D1.

[0051] By moving the heating unit 5a to a position away from the fixing unit 5b, the fixing unit 5b can be pulled out from inside the main body 1.

[0052] The exterior member 100 has an opening 101 and a cover member 102 (see Figure 7). The opening 101 is a portion in which an opening is formed that opens one end of the fixing unit 5b in the first direction D1.

[0053] The cover member 102 is supported by a pivot shaft 102x. This allows the cover member 102 to rotate around the pivot shaft 102x. The cover member 102 is rotatable between a closed position that closes the opening 101 and an open position that opens the opening 101.

[0054] When the fixing unit 5b is pulled out from inside the main body 1, the fixing unit 5b can pass through the opening 101 of the exterior member 100.

[0055] Incidentally, ensuring that the heater 51 is positioned correctly relative to the fixing belt 52 is important for improving the heating efficiency of the fixing belt 52 by the heater 51. When an electromagnetic induction heating device is used as the heater 51, the precision of the heater 51's position is particularly important.

[0056] Furthermore, in order to enable the fixing unit 5b to be pulled out from the main body 1, a moving mechanism 7 is required to move the heating unit 5a (see Figures 4-6). The moving mechanism 7 is equipped with a proximity function and a retraction function.

[0057] The proximity function positions the heating unit 5a at a reference position close to the fixing unit 5b. The retraction function moves the heating unit 5a to a retracted position away from the fixing unit 5b.

[0058] Therefore, in the moving mechanism 7, it is required that the heating unit 5a can be reliably positioned at the reference position when it moves from the retracted position to the reference position.

[0059] The configurations of the heating unit 5a and the fixing unit 5b will be described below.

[0060] [Configuration of heating unit 5a and fixing unit 5b] The heating unit 5a includes a heater 51 and a first support 54 (see Figures 4 and 6). The first support 54 is a member that supports the heater 51.

[0061] The fixing unit 5b includes a fixing belt 52, a fixing roller 520, a pressure roller 53, and a second support 55 (see Figures 4 and 6).

[0062] The second support 55 rotatably supports the fixing roller 520 and the pressure roller 53. The fixing roller 520 supports the fixing belt 52. That is, the fixing belt 52 is supported by the second support 55 via the fixing roller 520.

[0063] [Mechanism for positioning the heating unit 5a and the fixing unit 5b] The image forming apparatus 10 comprises a main frame 1x and an exterior member 100 (see Figures 3 and 7). The main frame 1x forms the skeleton of the main body 1. The exterior member 100 forms the exterior of the main body 1.

[0064] The main frame 1x is composed of a combination of multiple metal pipes (see Figure 3). The heating unit 5a and the fixing unit 5b are supported by the main frame 1x.

[0065] The exterior component 100 is attached to the main frame 1x (see Figure 7). The exterior component 100 forms the exterior of the image forming apparatus 10.

[0066] The multiple metal pipes that make up the main frame 1x have two support columns 11 and two beam columns 12 (see Figure 3).

[0067] The two support columns 11 are formed extending in the vertical direction D3 and are spaced apart in the first direction D1 (see Figure 3). The vertical direction D3 is the up and down direction.

[0068] The two support columns 11 are formed extending in the vertical direction D3 next to the anchoring unit 5b (see Figures 4 and 9).

[0069] The two support columns 11 include a first support column 11a located on the front side of the image forming apparatus 10 and a second support column 11b located on the rear side of the image forming apparatus 10 (see Figure 3).

[0070] The two beam sections 12 are formed extending laterally below the heating unit 5a and the fixing unit 5b, and are spaced apart in the first direction D1 (see Figures 3 and 5). The lateral direction is the width direction of the image forming apparatus 10.

[0071] Each of the two beam sections 12 is connected to two support sections 11 (see Figure 3). For example, each of the two beam sections 12 is connected to two support sections 11 by welding.

[0072] The two beam sections 12 include a first beam section 12a located on the front side of the image forming apparatus 10 and a second beam section 12b located on the rear side of the image forming apparatus 10 (see Figure 3).

[0073] The fixing unit 5b is positioned between the heating unit 5a and the two support columns 11 (see Figure 3).

[0074] The first support 54 of the heating unit 5a is supported on the two beams 12, with the support spanning across them. Similarly, the second support 55 of the fixing unit 5b is supported on the two beams 12, with the support spanning across them.

[0075] In other words, neither the heating unit 5a nor the fixing unit 5b is fixed to the main frame 1x by screws or other fasteners.

[0076] The heating unit 5a and the fixing unit 5b are each mounted on two beam sections 12 with their longitudinal directions aligned with the first direction D1 (see Figures 7 and 8).

[0077] The image forming apparatus 10 further includes a unit biasing unit 6 (see Figures 4 and 6). The unit biasing unit 6 and the moving mechanism 7 are located within the main body 1.

[0078] The unit biasing section 6 includes a first spring section 61 and a second spring section 62 (see Figures 4 and 6). The moving mechanism 7 includes an operating member 70 and an interlocking mechanism 71 (see Figures 4 and 5). The operating member 70 is positioned on the opposite side of the heating unit 5a from the fixing unit 5b. The operating member 70 is connected to the first support 54.

[0079] The first support 54 of the heating unit 5a has a plurality of first engaged portions 542 and second engaged portions 544 (see Figures 4 and 5). Furthermore, the first support 54 has a plurality of unit contact portions 543 (see Figure 4).

[0080] The second support 55 of the fixing unit 5b has a plurality of first engaging portions 553 corresponding to a plurality of first engaged portions 542 (see Figure 4). Furthermore, the second support 55 has a plurality of contact portions 554 corresponding to a plurality of unit contact portions 543 (see Figure 4).

[0081] In this embodiment, the first support 54 has a pair of first engaging portions 542 formed at two locations spaced apart in the first direction D1. Furthermore, the first support 54 has a pair of unit contact portions 543 formed at two locations spaced apart in the first direction D1.

[0082] The pair of unit contact portions 543 are formed at a distance from the first engaged portion 542 in the vertical direction D3.

[0083] The second support 55 has a pair of first engaging portions 553 formed at two locations corresponding to the pair of first engaged portions 542. Furthermore, the second support 55 has a pair of contact portions 554 formed at two locations corresponding to the pair of unit contact portions 543.

[0084] In this embodiment, each of the first engaged portions 542 is concave, opening in the second direction D2 (see Figure 4). Each of the first engaged portions 553 is convex, fitting into each of the first engaged portions 542.

[0085] Each of the first engaged portions 542 may be convex. In this case, each of the first engaged portions 553 is concave, opening in the second direction D2.

[0086] Furthermore, the discharge unit 32 has a second engaging portion 321 that corresponds to the second engaged portion 544 (see Figures 4 and 5). The discharge unit 32 is an example of a fixed unit fixed to the main body 1.

[0087] The pair of first engaging portions 553 engage with the pair of first engaged portions 542 when the heating unit 5a is in the reference position. By engaging with the pair of first engaged portions 542, the pair of first engaging portions 553 restrict the movement of the heating unit 5a in the vertical direction D3. The vertical direction D3 is an example of a third direction that intersects the first direction D1 and the second direction D2.

[0088] The second engaging portion 321 of the discharge unit 32 engages with the second engaged portion 544, thereby restricting the movement of the heating unit 5a in the first direction D1.

[0089] In this embodiment, the second engaging portion 321 is convex along the second direction D2 (see Figures 4 and 5). The second engaged portion 544 is a pair of upright portions facing each other in the first direction D1 (see Figure 5). The second engaging portion 321 is inserted between the pair of upright portions in the second engaged portion 544. As a result, the second engaging portion 321 engages with the second engaged portion 544.

[0090] The unit biasing unit 6 is located within the main body 1 on the side opposite to the fixing unit 5b relative to the heating unit 5a (see Figures 4 and 6). The unit biasing unit 6 biases the first support 54, thereby bringing the first support 54 into contact with the second support 55.

[0091] In this embodiment, the first spring portion 61 includes a pair of first compression springs spaced apart in the first direction D1. Similarly, the second spring portion 62 includes a pair of second compression springs spaced apart in the first direction D1. The pair of first compression springs and the pair of second compression springs are examples of elastic members.

[0092] For example, the pair of first compression springs and the pair of second compression springs are each supported by four protrusions 546 of the first support 54.

[0093] The working member 70 has a unit biasing section 6 sandwiched between it and the heating unit 5a (see Figure 4). The unit biasing section 6 biases the first support 54 toward the second support 55 by elastic force (see Figure 4).

[0094] In the following description, the biasing force of the first spring portion 61 on the first support 54 will be referred to as the first biasing force F1 (see Figure 4). The biasing force of the second spring portion 62 on the first support 54 will be referred to as the second biasing force F2.

[0095] The combined force of the first biasing force F1 and the second biasing force F2 is greater than the static frictional force between the heating unit 5a and the anchoring unit 5b on the two beam sections 12 (see Figure 4).

[0096] The first support 54 has slidable ribs 541 on the upper surfaces of the two beam sections 12. Similarly, the second support 55 has a plurality of slidable ribs 551 on the upper surfaces of the two beam sections 12. The ribs 541 of the first support 54 and the ribs 551 of the second support 55 are provided to reduce the static friction force.

[0097] The pair of unit contact portions 543 are formed below the pair of first engaged portions 542 in the heating unit 5a (see Figures 4 and 6).

[0098] The first spring portion 61 elastically biases the heating unit 5a toward the fixing unit 5b at a position corresponding to the position of the first engaged portion 542 in the vertical direction D3. The first spring portion 61 is an example of the first elastic portion.

[0099] The second spring portion 62 elastically biases the heating unit 5a toward the fixing unit 5b at a position corresponding to the position of the unit contact portion 543 in the vertical direction D3. The second spring portion 62 is an example of a second elastic portion.

[0100] The first support 54 of the heating unit 5a further has a pair of engagement guides 5420 corresponding to a pair of first engaged portions 542 (see Figures 4 and 6). The pair of engagement guides 5420 guide the pair of first engaged portions 542 to the first engagement portion 553.

[0101] Furthermore, if each of the first engaged portions 542 is convex and each of the first engaged portions 553 is concave, each of the engaging guide portions 5420 is formed on the second support 55 of the fixing unit 5b.

[0102] The interlocking mechanism 71 moves the working member 70 along the second direction D2. The heating unit 5a moves along the second direction D2 in conjunction with the working member 70. That is, the moving mechanism 7 moves the heating unit 5a along the second direction D2.

[0103] The interlocking mechanism 71 moves the operating member 70 along the second direction D2 in response to an operation on a predetermined operating part. For example, the cover member 102 also serves as the operating part.

[0104] The interlocking mechanism 71 moves the operating member 70 from one of the first position and the second position to the other in conjunction with the movement of the operating unit.

[0105] When the working member 70 is in the first position, the heating unit 5a is positioned in the reference position in the second direction D2 by the biasing force of the unit biasing unit 6. That is, the unit biasing unit 6 biases the heating unit 5a toward the fixing unit 5b when the heating unit 5a is in the reference position. The second position is a position further away from the fixing unit 5b than the first position.

[0106] The interlocking mechanism 71 moves the operating member 70 from the first position to the second position in response to a first operation on the operating unit. For example, the first operation is to move the cover member 102 from the closed position to the open position.

[0107] Furthermore, the interlocking mechanism 71 moves the operating member 70 from the second position to the first position in response to a second operation on the operating unit. For example, the second operation is to move the cover member 102 from the open position to the closed position.

[0108] The first support 54 of the heating unit 5a has a third engaged portion 545 that engages with a part of the working member 70 (see Figure 4).

[0109] The operating member 70 has a third engaging portion 701 that can engage with the third engaged portion 545 (see Figures 4 and 6). As the operating member 70 moves from the first position to the second position, the third engaging portion 701 engages with the third engaged portion 545.

[0110] When the working member 70 moves from the first position to the second position, the heating unit 5a receives a force from the working member 70 through the third engaging portion 701 and moves from the reference position to the retracted position. The retracted position is a position further away from the fixing unit 5b than the reference position.

[0111] When the heating unit 5a is in the retracted position, the fixing unit 5b can be pulled out from inside the main body 1 in the removal direction D11 (see Figure 5). The fixing unit 5b is pulled out from inside the main body 1 without coming into contact with the heating unit 5a. The removal direction D11 is the direction along the first direction D1.

[0112] The heating unit 5a is connected to the operating member 70 in a state that allows it to swing between a reference position and a tilted position. Figure 4 shows the heating unit 5a in the reference position. Figure 6 shows the heating unit 5a in the tilted position.

[0113] The reference position is the position of the heating unit 5a when the pair of first engaging portions 553 are engaged with the pair of first engaged portions 542 (see Figure 4). The tilted position is a position in which the unit is tilted diagonally downward toward the fixing unit 5b (see Figure 6). The tilted position is a position in which the unit is tilted diagonally downward relative to the reference position.

[0114] When the heating unit 5a is in the reference position, the pair of first engaged portions 542 come into contact with the pair of first engaged portions 553 due to the biasing force of the first spring portion 61. Specifically, the inner surfaces of the concave portions of each of the pair of first engaged portions 542 come into contact with each of the pair of first engaged portions 553 (see Figure 4).

[0115] Furthermore, when the heating unit 5a is in the reference position, the pair of unit contact portions 543 contact the pair of contacted portions 554 due to the biasing force of the second spring portion 62. In this embodiment, each of the pair of unit contact portions 543 is a curved surface. Each of the pair of contacted portions 554 is convex along the first direction D1.

[0116] That is, when the heating unit 5a is in the reference position, the unit biasing unit 6 holds the heating unit 5a in the reference position. Note that when the heating unit 5a is in the reference position, the engagement between the third engaging portion 701 and the third engaged portion 545 is disengaged.

[0117] The pair of first engaged portions 542 and the pair of unit contact portions 543 contact the fixing unit 5b at four locations. As a result, the heating unit 5a is positioned at the desired location in the second direction D2.

[0118] Furthermore, the unit biasing unit 6 biases the first support 54, thereby bringing the second support 55 into contact with the two support columns 11. In other words, the unit biasing unit 6 biases the second support 55 via the first support 54.

[0119] Furthermore, the second support 55 has a plurality of column contact portions 552 that protrude toward the two support columns 11 (see Figures 4-6). The plurality of column contact portions 552 abut against the sides of the two support columns 11.

[0120] When the heating unit 5a moves to a position further away from the fixing unit 5b than the reference position, the rib 541 slides on the upper surface of the two beam portions 12 (see Figure 6). In the following description, the movement of the heating unit 5a to a position further away from the fixing unit 5b than the reference position is referred to as sliding movement.

[0121] The two beam sections 12 are examples of lower support structures. These lower support structures support the heating unit 5a from below so that it can move along the second direction D2. The rib 541 is an example of a unit sliding section.

[0122] When the heating unit 5a slides, the third engaging portion 701 engages with the third engaged portion 545 (see Figure 6). The tilted position of the heating unit 5a when the third engaging portion 701 is engaged with the third engaged portion 545 is the tilted position. When the heating unit 5a is in the tilted position, the rib 541 contacts the upper surfaces of the two beam portions 12.

[0123] In this embodiment, when the heating unit 5a slides, the unit biasing portion 6 maintains the engaged state between the third engaging portion 701 and the third engaged portion 545.

[0124] When the heating unit 5a slides, the unit biasing portion 6 and the third engaging portion 701 hold the heating unit 5a in the tilted position. When the heating unit 5a slides, the unit biasing portion 6 constitutes part of the movement mechanism 7.

[0125] In other words, when the moving mechanism 7 moves the heating unit 5a to a position further away from the fixing unit 5b than the reference position, the moving mechanism 7 holds the heating unit 5a in the tilted position.

[0126] When the heating unit 5a moves from the retracted position to the reference position by the action of the moving mechanism 7, the engagement guide portion 5420 guides the first engaged portion 542 to the first engaging portion 553, and the second engaged portion 544 engages with the second engaging portion 321.

[0127] As the heating unit 5a moves toward the fixing unit 5b, the heating unit 5a is held in the tilted position. This stabilizes the positional relationship between the first engaged portion 542 and the first engaging portion 553 when the engaging guide portion 5420 contacts the first engaged portion 542. As a result, the first engaged portion 542 is reliably guided to the first engaging portion 553 by the engaging guide portion 5420.

[0128] When the second engaging portion 321 engages with the second engaged portion 544, the heating unit 5a is positioned at the desired position in the first direction D1.

[0129] Furthermore, as the heating unit 5a moves toward the reference position, the engagement guide portion 5420 guides the first engaged portion 542 to the first engaging portion 553. The engagement guide portion 5420 also guides the first engaged portion 542 to the first engaging portion 553 while swinging the heating unit 5a from the tilted position to the reference position. At this time, the heating unit 5a swings around the contact point between the rib 541 and the upper surfaces of the two beam portions 12. Furthermore, the rib 541 moves upward away from the two beam portions 12 (see Figure 4).

[0130] With the rib 541 separated from the two beam sections 12, the first engaging section 553 engages with the first engaged section 542, and the unit contact section 543 contacts the contacted section 554.

[0131] The unit biasing unit 6 biases the heating unit 5a, which is located at the reference position. As a result, the unit biasing unit 6 maintains the engaged state of the first engaging portion 553 and the first engaged portion 542, and maintains the contact state of the unit contact portion 543 and the contact portion 554. The heating unit 5a is held in the reference position by the biasing force of the unit biasing unit 6.

[0132] The heating unit 5a is positioned at the desired location in the vertical direction D3 by the engagement of a pair of first engaging portions 553 with a pair of first engaged portions 542.

[0133] In this embodiment, the first biasing force F1 is stronger than the second biasing force F2. That is, the first spring portion 61 biases the heating unit 5a with a stronger force than the second spring portion 62.

[0134] The first biasing force F1 of the first spring portion 61 acts as a force that lifts the heating unit 5a from the tilted position to the reference position. On the other hand, the second biasing force F2 of the second spring portion 62 acts mainly as a force that maintains the contact state between the unit contact portion 543 and the contacted portion 554.

[0135] The heating unit 5a and the fixing unit 5b are positioned at the desired location in the second direction D2 by being sandwiched between the unit biasing section 6 and the two support columns 11.

[0136] With the adoption of the image forming apparatus 10, when the moving mechanism 7 moves the heating unit 5a from a position away from the fixing unit 5b to the reference position, the heating unit 5a is reliably positioned at the reference position.

[0137] As shown in Figure 8, the image forming apparatus 10 includes a drive mechanism 9 having a drive gear 90. The drive mechanism 9 includes a motor (not shown). The drive mechanism 9 transmits rotational force to the fixing unit 5b through the drive gear 90.

[0138] The fixing unit 5b includes a driven gear 530 that meshes with the drive gear 90. The driven gear 530 transmits the rotational force it receives from the drive gear 90 to the fixing roller 520. This causes the fixing belt 52 to rotate. In other words, the driven gear 530 transmits the rotational force to the fixing belt 52 via the fixing roller 520.

[0139] The pressure roller 53 rotates in conjunction with the rotating fixing belt 52. The driven gear 530 also transmits the rotational force to the pressure roller 53 via the fixing roller 520 and the fixing belt 52.

[0140] The direction of the pressure F3 that the teeth of the driven gear 530 receive from the teeth of the drive gear 90 is diagonally downward towards the two support columns 11 (see Figure 8). Therefore, the pressure F3 that the teeth of the driven gear 530 receive from the teeth of the drive gear 90 acts as a force that biases the anchoring unit 5b toward the two support columns 11 and the two beam columns 12.

[0141] The fixing unit 5b is more firmly positioned in the second direction D2 and the longitudinal direction D3 by the pressure F3 received from the drive gear 90.

[0142] Furthermore, the image forming apparatus 10 is further equipped with a cover biasing mechanism 8 attached to the inner surface of the cover member 102 (see Figure 5). In addition, the second support 55 of the fixing unit 5b has a beam contact portion 555 that protrudes downward from the bottom surface (see Figures 4 and 7).

[0143] The cover biasing mechanism 8 comprises a third spring 80, a spring case 81, and a cap portion 82 (see Figure 7).

[0144] The spring case 81 houses the third spring 80. The cap portion 82 is movably attached to the spring case 81. The third spring 80 is an example of an elastic fixing unit biasing member.

[0145] The third spring 80 is sandwiched between the cover member 102 and the second support 55 of the fixing unit 5b when the cover member 102 is in the closed position. In this embodiment, the third spring 80 and the cap portion 82 are sandwiched between the cover member 102 and the second support 55.

[0146] The third spring 80 is sandwiched between the cover member 102 and the second support 55, thereby elastically biasing the second support 55 in the mounting direction D12 (see Figure 5). The mounting direction D12 is the opposite direction to the removal direction D11.

[0147] Furthermore, when the cover member 102 is in the closed position, the force received by the second support 55 from the third spring 80 causes the beam contact portion 555 to contact one side of the two beam portions 12. In this embodiment, the beam contact portion 555 contacts the side of the second beam portion 12b.

[0148] The anchoring unit 5b is positioned in the first direction D1 by the action of the third spring 80 and the beam contact portion 555.

[0149] The cover biasing mechanism 8 may also be attached to the second support 55 of the fixing unit 5b. [Explanation of symbols]

[0150] 4x: Image forming section 5: Fixing device 5a: Heating unit 5b: Fixing unit 6: Unit biasing section 7: Movement mechanism 8: Cover biasing mechanism 9: Drive mechanism 10: Image forming apparatus 11: Support section 12:Beam part 45: Transfer device 51: Heater 52: Fixing belt (fixing member) 53: Pressure roller (pressure component) 54: 1st support 55:Second support 61: First spring section 62: Second spring section 70: Working Member 71: Interlocking mechanism 80: Third spring 81: Spring case 82: Cap part 90: Drive gear 100: Exterior components 101: Opening 102: Cover component 321: Second engaging part 541: Rib (unit sliding part) 542: First engaged part 543: Unit contact part 544: Second engaged part 545: Third engaged part 551: Rib 553: First engaging part 701: Third engaging part 5420: Engagement guide part

Claims

1. A heating unit having a heater and arranged along a first direction within the main body, A fixing unit having a fixing member heated by the heater and a pressurizing member that biases the sheet onto the fixing member, and positioned within the main body alongside the heating unit and along the first direction, A moving mechanism for moving the heating unit along a second direction which is the arrangement direction of the heating unit and the fixing unit, The unit includes a unit biasing unit that biases the heating unit toward the fixing unit when the heating unit is in a reference position in the second direction, The heating unit has an engaged portion, The fixing unit has an engaging portion that engages with the engaged portion when the heating unit is in the reference position, The heating unit or the fixing unit has an engagement guide portion that guides the engaged portion to the engagement portion, The heating unit is connected to the moving mechanism so as to be able to swing between a reference position and a tilted position in which it is tilted diagonally downward toward the fixing unit. The moving mechanism holds the heating unit in the tilted position when moving the heating unit to a position further away from the fixing unit than the reference position. The engagement guide guide, when the heating unit moves toward the reference position, guides the engaged portion toward the engagement guide while causing the heating unit to swing from the tilted position to the reference position. The engaging portion, by engaging with the engaged portion, restricts the movement of the heating unit in the vertical direction intersecting the first direction and the second direction. The unit biasing unit maintains the engaged state of the engaging portion and the engaged portion by biasing the heating unit, in an image forming apparatus.

2. The heating unit further comprises a lower support that supports it from below so as to be movable along the second direction, The heating unit has a unit sliding portion that slides on the upper surface of the lower support when the heating unit moves to a position further away from the fixing unit than the reference position. The image forming apparatus according to claim 1, wherein when the engaging guide guides the engaged portion to the engaging portion, the heating unit swings around the contact point between the unit sliding portion and the upper surface of the lower support, and the unit sliding portion moves upward away from the lower support.

3. The heating unit has a unit contact portion formed at a position spaced apart in the vertical direction from the engaged portion, The image forming apparatus according to claim 1 or claim 2, wherein when the heating unit is in the reference position, the unit contact portion contacts the fixing unit due to the biasing force of the unit biasing portion.

4. The unit contact portion is formed below the engaged portion in the heating unit. The aforementioned unit biasing unit is A first elastic part elastically biases the heating unit toward the fixing unit at a position corresponding to the position of the engaged part in the vertical direction, It includes a second elastic portion that elastically biases the heating unit toward the fixing unit at a position corresponding to the position of the unit contact portion in the vertical direction, The image forming apparatus according to claim 3, wherein the first elastic portion biases the heating unit with a stronger force than the second elastic portion.

5. The image forming apparatus according to any one of claims 1 to 4, wherein the heater is an electromagnetic induction heating device.

Images