Image forming apparatus

Abstract

An object of the present invention is to provide an image forming apparatus, which realizes a mechanism for arranging a heating unit and a fixing unit at a target position through a simple mechanism. A heating unit biasing member biases a first support member of the heating unit toward a second support member of the fixing unit by using an elastic force. The heating unit biasing member brings the first support member into contact with the second support member, and brings the second support member into contact with two support columns. A linkage mechanism moves the heating unit along the arrangement direction of the heating unit and the fixing unit in linkage with the movement of an operation unit. When the operation unit moves from a first position to a second position, the linkage mechanism moves the first support member from a reference position in contact with the second support member to a retracted position away from the second support member.

Description

Technical Field

[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 is sometimes divided into a heating unit including a heater and a fixing unit including a fixing member and a pressure roller. The heater heats the fixing member.

[0004] In addition, the image forming apparatus is known to include a mechanism for moving the heating unit from a heating position to a retracted position in conjunction with an operation of an operation portion. When the heating unit is retracted to the retracted position, the fixing unit can be pulled out from the main body.

[0005] However, it is important to arrange the heater at an appropriate position relative to the fixing member in order to improve the heating efficiency of the fixing member by the heater. When an electromagnetic induction heating device is used as the heater, the accuracy of the position of the heater is particularly important.

[0006] On the other hand, it is expected that the unit positioning mechanism for arranging the heating unit and the fixing unit at target positions is an extremely simple mechanism.

[0007] The unit positioning mechanism includes a mechanism for positioning the heating unit at a reference position close to the fixing unit and a mechanism for moving the heating unit to a retreat position away from the fixing unit. Summary of the invention

[0008] An object of the present invention is to provide an image forming apparatus which can realize a mechanism for arranging a heating unit and a fixing unit at target positions by a simple mechanism.

[0009] An image forming apparatus according to one aspect of the present invention includes a main body frame, a heating unit, and a fixing unit. The heating unit is supported by the main body frame. The fixing unit is disposed beside the heating unit and is supported by the main body frame. The main body frame has two column portions and two beam portions. The two column portions are formed to extend longitudinally beside the fixing unit and are arranged at intervals in a first direction. The two beam portions are formed to extend horizontally below the heating unit and the fixing unit and are arranged at intervals in the first direction, and are respectively connected to the two column portions. The fixing unit is disposed between the heating unit and the two column portions. The heating unit has a heater and a first support member. The first support member supports the heater and is placed on the two beam portions in a state of being spanned therebetween. The fixing unit has a fixing member, a pressing member, and a second support member. The fixing member is heated by the heater. The pressing member applies a force to a sheet-like body toward the fixing member. The second support member supports the fixing member and the pressing member and is placed on the two beam portions in a state of being spanned therebetween. The image forming apparatus further includes an elastic heating unit biasing member, an operation unit, and a linkage mechanism. The heating unit biasing member biases the first support member toward the second support member by using an elastic force, causing the first support member to abut against the second support member and causing the second support member to abut against the two column portions. The operation unit is movable between a first position and a second position by being operated. The linkage mechanism moves the heating unit along a second direction, which is the arrangement direction of the heating unit and the fixing unit, in linkage with the movement of the operation unit. When the operation unit moves from the first position to the second position, the linkage mechanism moves the first support member from a reference position where it abuts against the second support member to a retracted position away from the second support member. Further, when the operation unit moves from the second position to the first position, the linkage mechanism moves the first support member from the retracted position to the reference position. When the first support member is in the retracted position, the fixing unit can be pulled out from the main body frame in a removal direction along the first direction.

[0010] According to the present invention, an image forming apparatus can be provided that realizes a mechanism for arranging a heating unit and a fixing unit at a target position through a simple mechanism.

[0011] This specification is introduced by appropriately referring to the accompanying drawings and by simplifying the content that summarizes the concepts described in the following detailed description. The intention of this specification is not to limit the important and essential features of the subject matter recited in the claims, and furthermore, it is not to limit the scope of the subject matter recited in the claims. In addition, the subject matter recited in the claims is not limited to the embodiments that solve some or all of the drawbacks described in any part of the present invention. Description of the Drawings

[0012] Figure 1 It is a configuration diagram of an image forming apparatus according to an embodiment.

[0013] Figure 2 It is a diagram showing the configuration of the main part of a fixing device in the image forming apparatus according to the embodiment.

[0014] Figure 3 It is a perspective view of a main body frame in the image forming apparatus according to the embodiment.

[0015] Figure 4 It is a front view of a fixing device and a linkage mechanism in a force application state in the image forming apparatus according to the embodiment.

[0016] Figure 5 It is a front view of a fixing device and a linkage mechanism in a retracted state in the image forming apparatus according to the embodiment.

[0017] Figure 6 It is a perspective view of a fixing unit in the image forming apparatus according to the embodiment.

[0018] Figure 7 It is a top view of a fixing device and a linkage mechanism in a force application state in the image forming apparatus according to the embodiment.

[0019] Figure 8 It is a top view of a fixing device and a linkage mechanism in a retracted state in the image forming apparatus according to the embodiment.

[0020] Figure 9 It is a perspective view of the periphery of a fixing unit and a cover member in the image forming apparatus according to the embodiment.

[0021] Figure 10 It is a diagram showing a cross-section of a support portion and a lateral abutting portion of a fixing unit in the image forming apparatus according to the embodiment.

[0022] Figure 11 It is a diagram showing a cross-section of a beam portion and a lower abutting portion of a fixing unit in the image forming apparatus according to the embodiment.

[0023] Figure 12This is a diagram showing the back of the fixing unit and the drive mechanism in the image forming apparatus according to the embodiment. Detailed Embodiment

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention.

[0025] [Configuration of Image Forming Apparatus 10]

[0026] The image forming apparatus 10 according to the embodiment performs a printing process by an electrophotographic method. The printing process is a process of forming an image on the sheet body 9.

[0027] As Figure 1 shown, the image forming apparatus 10 includes a sheet body storage unit 2, a sheet body conveyance device 3, and a printing device 4. The sheet body conveyance device 3 and the printing device 4 are housed in the main body 1 which is a housing.

[0028] The sheet body storage unit 2 can store a plurality of sheet bodies 9. The sheet body conveyance device 3 includes a sheet body supply device 30 and a plurality of pairs of conveyance rollers 31.

[0029] The sheet body supply device 30 sends out the sheet bodies 9 in the sheet body storage unit 2 one by one to the conveyance path 300. The conveyance path 300 is a path for the sheet bodies 9.

[0030] The plurality of pairs of conveyance rollers 31 convey the sheet bodies 9 along the conveyance path 300. One of the plurality of pairs of conveyance rollers 31 discharges the sheet body 9 on which an image is formed from the conveyance path 300 onto the discharge tray 10a.

[0031] The printing device 4 performs the printing process on the sheet body 9 conveyed along the conveyance path 300. The image formed on the sheet body 9 is a toner image.

[0032] 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 photoreceptor 41, a charging device 42, a developing device 43, and a drum cleaning device 44.

[0033] The charging device 42 charges the surface of the photoreceptor 41. The optical scanning unit 40 scans a light beam on the charged surface of the photoreceptor 41. Thereby, the optical scanning unit 40 forms an electrostatic latent image on the surface of the photoreceptor 41.

[0034] The developing device 43 supplies toner to the surface of the photoreceptor 41 to develop the electrostatic latent image into a toner image. The transfer device 45 transfers the toner image formed on the surface of the photoreceptor 41 to the sheet body 9.

[0035] The transfer device 45 transfers the electrostatic latent image to the sheet body 9 at the transfer position P1 in the conveyance path 300.

[0036] In the present embodiment, the printing device 4 is a tandem color printing device including a plurality of image forming units 4x. Further, the transfer device 45 includes an intermediate transfer belt 450, a plurality of primary transfer devices 451, a secondary transfer device 452, and a belt cleaning device 453.

[0037] In Figure 1 the example shown, the printing device 4 includes four image forming units 4x corresponding to toners of four colors: yellow, magenta, cyan, and black. The transfer device 45 includes four primary transfer devices 451 corresponding to the four image forming units 4x.

[0038] The intermediate transfer belt 450 is supported by a plurality of support rollers 454 so as to be rotatable. One of the plurality of support rollers 454 is rotated by a belt driving device (not shown). Thereby, the intermediate transfer belt 450 rotates.

[0039] The primary transfer devices 451 transfer the toner images formed on the surfaces of the photoreceptors 41 to the surface of the intermediate transfer belt 450 in each of the image forming units 4x. Thereby, a composite toner image obtained by synthesizing toner images of four colors is formed on the surface of the intermediate transfer belt 450.

[0040] The intermediate transfer belt 450 rotates while carrying the composite toner image. The secondary transfer device 452 transfers the composite toner image formed on the surface of the intermediate transfer belt 450 to the sheet body 9 at the transfer position P1.

[0041] 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 in the portion that has passed through the primary transfer device 451.

[0042] 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 in the portion that has passed through the secondary transfer device 452.

[0043] The fixing device 5 heats and presses the composite toner image on the sheet body 9 at the fixing position P2 in the conveyance path 300. Thereby, the fixing device 5 fixes the composite toner image to the sheet body 9. The fixing position P2 is a position downstream of the transfer position P1 in the sheet conveyance direction.

[0044] As Figure 2 shown, 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.

[0045] 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 .

[0046] The fixing roller 520 is a cylindrical member that supports the fixing belt 52 inside the fixing belt 52. The fixing roller 520 includes a cylindrical core shaft portion 521 and an elastic portion 522 formed on the outer periphery of the core shaft portion 521.

[0047] The fixing roller 520 is rotatably supported, and the fixing belt 52 is rotatable together with the fixing roller 520 .

[0048] The fixing belt 52 includes 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.

[0049] The heater 51 is disposed facing the outer peripheral surface of the fixing belt 52. In the present embodiment, the heater 51 is an electromagnetic induction heating device. The heater 51 heats the base material of the fixing belt 52 mainly by electromagnetic induction.

[0050] The pressure roller 53 is rotatably supported and has a cylindrical core portion 531 and an elastic portion 532 formed on the outer periphery of the core portion 531 , similarly to the fixing roller 520 .

[0051] The pressure roller 53 is driven to rotate by a driving device (not shown). The fixing belt 52 and the fixing roller 520 rotate in conjunction with the pressure roller 53 .

[0052] The fixing belt 52 heats the toner image formed on the sheet 9 . The pressure roller 53 presses the toner image toward the sheet 9 .

[0053] The fixing belt 52 is an example of a fixing member heated by the heater 51 . The pressure roller 53 is an example of a pressure member that urges the sheet 9 toward the fixing belt 52 .

[0054] When the sheet 9 is attached to the fixing belt 52 , the sheet separation member 5200 peels the sheet 9 from the fixing belt 52 .

[0055] In this embodiment, the fixing device 5 is divided into a heating unit 5a and a fixing unit 5b (see Figure 4 , Figure 5 The heating unit 5a includes a heater 51 and a first support 54. The fixing unit 5b includes a fixing belt 52, a fixing roller 520, a pressure roller 53, and a second support 55.

[0056] The first support member 54 is a member that supports the heater 51. The second support member 55 is a member that supports the fixing belt 52, the fixing roller 520, and the pressure roller 53. The fixing belt 52 is supported by the second support member 55 via the fixing roller 520.

[0057] By moving the heating unit 5a to a position away from the fixing unit 5b, the fixing unit 5b can be pulled out from the main body 1 (see Figure 5 , Figure 8 ).

[0058] However, it is important to arrange the heater 51 at an appropriate position relative to the fixing belt 52 in terms of improving the heating efficiency of the heater 51 for the fixing belt 52. When an electromagnetic induction heating type heating device is used as the heater 51, the accuracy of the position of the heater 51 is particularly important.

[0059] On the other hand, it is preferable that the unit positioning mechanism for arranging the heating unit 5a and the fixing unit 5b at the target positions is an extremely simple mechanism.

[0060] The unit positioning mechanism includes a mechanism for positioning the heating unit 5a at a reference position close to the fixing unit 5b and a mechanism for moving the heating unit 5a to a retracted position away from the fixing unit 5b.

[0061] The image forming apparatus 10 realizes a mechanism for arranging the heating unit 5a and the fixing unit 5b at the target positions through a simple mechanism. Hereinafter, the mechanism for positioning the heating unit 5a and the fixing unit 5b will be described.

[0062] [Mechanism for positioning the heating unit 5a and the fixing unit 5b]

[0063] The main body 1 of the image forming apparatus 10 includes a main body frame 1x and an exterior member 100 that covers the main body frame 1x (see Figure 3 , Figure 9 ).

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

[0065] The exterior member 100 is mounted on the main body frame 1x (see Figure 9 ). The exterior member 100 forms the exterior of the image forming apparatus 10.

[0066] The plurality of metal tubes constituting the main body frame 1x have two support portions 11 and two beam portions 12 (see Figure 3 ).

[0067] Two support portions 11 are formed to extend along the longitudinal direction D3 and are arranged at intervals in the first direction D1 (see Figure 3 ). The longitudinal direction D3 is the vertical direction.

[0068] Two support portions 11 are formed to extend along the longitudinal direction D3 beside the fixing unit 5b (see Figure 4 、 Figure 9 ).

[0069] The first direction D1 is also the direction along the center lines of rotation of the fixing belt 52 and the pressure roller 53. In the present embodiment, the first direction D1 is the depth direction of the image forming apparatus 10.

[0070] The exterior member 100 has an opening portion 101 and a cover member 102 (see Figure 9 ). The opening portion 101 is a portion where an opening is formed to open one end in the first direction D1 in the fixing unit 5b.

[0071] The cover member 102 is supported by the first support shaft 102x. Thus, the cover member 102 can rotate about the first support shaft 102x. The cover member 102 can rotate between a closed position where the opening portion 101 is closed and an open position where the opening portion 101 is opened.

[0072] Figure 4 、 Figure 7 Shows the fixing device 5 when the cover member 102 is in the closed position. Figure 5 、 Figure 8 Shows the fixing device 5 when the cover member 102 is in the open position.

[0073] When the cover member 102 is in the closed position, the cover member 102 is held in the closed position by a locking mechanism (not shown). By releasing the locking of the locking mechanism, the cover member 102 can rotate from the closed position to the open position.

[0074] The two support portions 11 include a first support portion 11a disposed on the front side of the image forming apparatus 10 and a second support portion 11b disposed on the back side of the image forming apparatus 10 (see Figure 3 ).

[0075] Two beam portions 12 are formed to extend along the lateral direction below the heating unit 5a and the fixing unit 5b and are arranged at intervals in the first direction D1 (see Figure 3 、 Figure 4 ). The lateral direction is the width direction of the image forming apparatus 10.

[0076] The two beam portions 12 are respectively connected to the two support portions 11 (see Figure 3 ). For example, the two beam portions 12 are respectively connected to the two support portions 11 by welding.

[0077] The two beam portions 12 include a first beam portion 12a disposed on the front side of the image forming apparatus 10 and a second beam portion 12b disposed on the back side of the image forming apparatus 10 (see Figure 3 ).

[0078] The fixing unit 5b is disposed between the heating unit 5a and the two support pillars 11 (see Figure 4 ).

[0079] The first support member 54 of the heating unit 5a is placed on the two beam portions 12 in a state of being spanned across the two beam portions 12. Similarly, the second support member 55 of the fixing unit 5b is also placed on the two beam portions 12 in a state of being spanned across the two beam portions 12.

[0080] That is, neither the heating unit 5a nor the fixing unit 5b is fixed to the main body frame 1x by fixing members such as small screws.

[0081] The heating unit 5a and the fixing unit 5b are respectively placed on the two beam portions 12 in a state where the long side direction is along the first direction D1 (see Figure 7 , Figure 8 ).

[0082] The heating unit 5a and the fixing unit 5b are arranged side by side in the second direction D2.

[0083] That is, the second direction D2 is the arrangement direction of the heating unit 5a and the fixing unit 5b. The second direction D2 is a direction intersecting the first direction D1.

[0084] The image forming apparatus 10 further includes a first spring 60 and a linkage mechanism 6 (see Figure 4 , Figure 5 , Figure 7 , Figure 8 ). For example, the first spring 60 is supported by a protrusion 544 of the first support member 54.

[0085] The first spring 60 applies a force to the first support member 54 toward the second support member 55 by its elastic force (see Figure 4 ). The first spring 60 is an example of an elastic heating unit biasing member.

[0086] The acting force F1 of the first spring 60 on the first support member 54 is greater than the static friction force of the heating unit 5a and the fixing unit 5b with respect to the two beam portions 12.

[0087] The first support member 54 has a plurality of ribs 541 that contact the upper surfaces of the two beam portions 12. Similarly, the second support member 55 has a plurality of ribs 551 that contact the upper surfaces of the two beam portions 12. The ribs 541 of the first support member 54 and the ribs 551 of the second support member 55 are provided to reduce the static friction force.

[0088] The first spring 60 abuts the first support member 54 against the second support member 55 by applying a force to the first support member 54. In addition, the first spring 60 abuts the second support member 55 against the two support pillar portions 11 by applying a force to the first support member 54. That is, the first spring 60 applies a force to the second support member 55 via the first support member 54.

[0089] The first support member 54 has a plurality of concave first fitting portions 542 that open laterally (see Figure 4 , Figure 5 ). The first support member 54 has four first fitting portions 542 formed at intervals in the first direction D1 and the longitudinal direction D3.

[0090] The second support member 55 has a plurality of convex second fitting portions 553, and the plurality of second fitting portions 553 can be respectively inserted into the plurality of first fitting portions 542. The second support member 55 has four second fitting portions 553 corresponding to the four first fitting portions 542.

[0091] By applying a force to the first support member 54 with the first spring 60, the inner surfaces of the concave portions of the four first fitting portions 542 abut against the four second fitting portions 553 (see Figure 4 ).

[0092] In addition, by inserting the second fitting portion 553 into the first fitting portion 542, relative movement of the first support member 54 and the second support member 55 in the longitudinal direction D3 is restricted.

[0093] Alternatively, the second support member 55 may be provided with the first fitting portion 542, and the first support member 54 may be provided with the second fitting portion 553.

[0094] In addition, the second support member 55 has a plurality of column abutting portions 552 that protrude toward the two support pillar portions 11 (see Figure 4 , Figure 6 ). The plurality of column abutting portions 552 abut against the sides of the two support pillar portions 11.

[0095] The linkage mechanism 6 moves the heating unit 5a along the second direction D2 in linkage with the movement of the lid member 102.

[0096] When the lid member 102 moves from the closed position to the open position, the linkage mechanism 6 moves the first support member 54 of the heating unit 5a from the reference position to the retracted position (see Figure 4 ,Figure 5 )。

[0097] The reference position is the position of the first support member 54 when the first support member 54 abuts against the second support member 55. The retracted position is the position of the first support member 54 when the first support member 54 moves away from the second support member 55.

[0098] When the first support member 54 moves from the reference position to the retracted position, the four second fitting portions 553 are separated from the four first fitting portions 542 (see Figure 5 )。

[0099] In addition, the first support member 54 being located at the reference position has the same meaning as the heating unit 5a being located at the reference position. In addition, the first support member 54 being located at the retracted position has the same meaning as the heating unit 5a being located at the retracted position.

[0100] When the first support member 54 is located at the retracted position, the fixing unit 5b can be pulled out from the main body frame 1x in the removal direction D11 along the first direction D1 (see Figure 8 )。

[0101] When the fixing unit 5b is pulled out from the main body frame 1x, the fixing unit 5b can pass through the opening 101 of the exterior member 100.

[0102] On the other hand, when the cover member 102 moves from the open position to the closed position, the linkage mechanism 6 moves the first support member 54 from the retracted position to the reference position (see Figure 7 、 Figure 8 )。

[0103] When the first support member 54 moves from the retracted position to the reference position, the four second fitting portions 553 are inserted into the four first fitting portions 542 (see Figure 4 )。

[0104] The cover member 102 also serves as an operation portion that can be moved between a first position and a second position by being operated. The closed position of the cover member 102 is the first position of the operation portion. The open position of the cover member 102 is the second position of the operation portion.

[0105] For example, the linkage mechanism 6 includes an acting member 61, two first link members 62, a second link member 63, and a third link member 64 (see Figure 7 、 Figure 8 )。

[0106] The acting member 61 is configured to be movable along the second direction D2. Two first link members 62 are connected to the acting member 61 by two first connecting shafts 611. The second link member 63 is connected to the two first link members 62 by two second connecting shafts 621.

[0107] The third link member 64 is supported by a second support shaft 640. The third link member 64 is rotatable about the second support shaft 640. The third link member 64 is connected to the second link member 63 by a third connecting shaft 631. The cover member 102 is connected to the third link member 64 by a fourth connecting shaft 641.

[0108] Figure 7 , Figure 8 The linkage mechanism 6 shown converts the rotational movement of the cover member 102 into the movement of the acting member 61 along the second direction D2.

[0109] When the cover member 102 rotates, the second link member 63 moves along the first direction D1 by the action of the third link member 64.

[0110] When the second link member 63 moves along the first direction D1, the acting member 61 moves along the second direction D2 by the action of the first link member 62.

[0111] When the cover member 102 moves from the closed position to the open position, the linkage mechanism 6 moves the acting member 61 in a direction away from the fixing unit 5b. When the cover member 102 moves from the open position to the closed position, the linkage mechanism 6 moves the acting member 61 in a direction approaching the fixing unit 5b.

[0112] The first spring 60 is disposed between the acting member 61 and the first support member 54 of the heating unit 5a (see Figure 4 , Figure 5 ). When the acting member 61 approaches the first support member 54 along the second direction D2, the acting member 61 presses the first spring 60 toward the first support member 54 (see Figure 4 ).

[0113] By the acting member 61 pressing the first spring 60 toward the first support member 54, the first spring 60 biases the first support member 54 toward the reference position.

[0114] The acting member 61 has an engaging portion 612 that can engage with the engaged portion 543 of the first support member 54 (see Figure 4 ). When the acting member 61 moves along the second direction D2 in a direction away from the first support member 54, the engaging portion 612 engages with the engaged portion 543.

[0115] When the action member 61 moves in the direction away from the first support member 54 along the second direction D2, the first support member 54 receives force from the action member 61 through the engaging portion 612 and moves from the reference position to the retreat position (see Figure 5 ).

[0116] On the other hand, when the action member 61 moves in the direction approaching the first support member 54 along the second direction D2, the first support member 54 receives force from the action member 61 through the first spring 60 and moves from the retreat position to the reference position (see Figure 4 ).

[0117] The heating unit 5 a and the fixing unit 5 b are positioned in the second direction D2 by being interposed between the first spring 60 and the two support pillars 11 .

[0118] In addition, the interlocking mechanism 6 may include a gear mechanism such as a rack and pinion mechanism. In this case, the interlocking mechanism 6 converts the rotation of the cover member 102 into the movement of the action member 61 along the second direction D2.

[0119] The heating unit 5a and the fixing unit 5b are positioned in the longitudinal direction D3 by being placed on the two beams 12. The loads of the heating unit 5a and the fixing unit 5b restrict the upward movement of the heating unit 5a and the fixing unit 5b.

[0120] like Figure 12 As shown in FIG. 1 , the image forming apparatus 10 includes a driving mechanism 7 having a driving gear 70 . The driving mechanism 7 includes a motor (not shown). The driving mechanism 7 transmits a rotational force to the fixing unit 5 b via the driving gear 70 .

[0121] The fixing unit 5b includes a driven gear 530 meshing with the driving gear 70. The driven gear 530 transmits the rotational force received from the driving gear 70 to the fixing roller 520. As a result, the fixing belt 52 rotates. That is, the driven gear 530 transmits the rotational force to the fixing belt 52 via the fixing roller 520.

[0122] The pressure roller 53 rotates in conjunction with the rotating fixing belt 52. The driven gear 530 is also a gear that transmits the rotational force to the pressure roller 53 via the fixing roller 520 and the fixing belt 52.

[0123] The direction of the pressure F2 that the teeth of the driven gear 530 receive from the teeth of the driving gear 70 is diagonally downward on the side of the two support portions 11. Therefore, the pressure F2 that the teeth of the driven gear 530 receive from the teeth of the driving gear 70 acts as a force that urges the fixing unit 5b toward the two support portions 11 and the two beam portions 12.

[0124] The fixing unit 5b is more firmly positioned in the second direction D2 and the longitudinal direction D3 by the pressure F2 received from the drive gear 70. Further, by the action of the first engaging portion 542 and the second engaging portion 553, the heating unit 5a is also firmly positioned in the longitudinal direction D3 together with the fixing unit 5b.

[0125] In the present embodiment, the drive mechanism 7 also serves as a downward biasing mechanism that biases the fixing unit 5b downward.

[0126] Further, the image forming apparatus 10 further includes a cover biasing mechanism 8 attached to the inner surface of the cover member 102 (see Figure 7 , Figure 8 ). Further, the second support member 55 of the fixing unit 5b has a beam contact portion 554 that protrudes downward from the lower surface (see Figure 4 , Figure 5 , Figure 6 , Figure 9 ).

[0127] The cover biasing mechanism 8 includes a second spring 80, a spring housing 81, and a cover body portion 82 (see Figure 7 ).

[0128] The spring housing 81 houses the second spring 80. The cover body portion 82 is attached so as to be movable relative to the spring housing 81. The second spring 80 is an example of an elastic fixing unit biasing member.

[0129] The second spring 80 is sandwiched between the cover member 102 and the second support member 55 of the fixing unit 5b when the cover member 102 is in the closed position. In the present embodiment, the second spring 80 and the cover body portion 82 are sandwiched between the cover member 102 and the second support member 55.

[0130] The second spring 80 is sandwiched between the cover member 102 and the second support member 55, and biases the second support member 55 in the mounting direction D12 by its elastic force (see Figure 7 ). The mounting direction D12 is the opposite direction of the removal direction D11.

[0131] Further, when the cover member 102 is in the closed position, the beam contact portion 554 contacts the side surface of one of the two beam portions 12 by the force received by the second support member 55 from the second spring 80. In the present embodiment, the beam contact portion 554 contacts the side surface of the second beam portion 12b.

[0132] The fixing unit 5b is positioned in the first direction D1 by the action of the second spring 80 and the beam contact portion 554.

[0133] Further, the cover biasing mechanism 8 may be attached to the second support member 55 of the fixing unit 5b.

[0134] In addition, the support portions 11 each have sides on four sides. Each of the four sides of the support portions 11 has two raised portions 1p, and the raised portions 1p form ridge lines along the long side direction of the support portions 11 (see Figure 10 ).

[0135] The plurality of column abutting portions 552 of the second support member 55 abut against the two raised portions 1p of the two support portions 11 respectively. Thereby, the fixing unit 5b is stably positioned in the second direction D2.

[0136] Similarly, the beam portions 12 each have sides on four sides. Each of the four sides of the beam portions 12 has two raised portions 1p, and the raised portions 1p respectively form ridge lines along the long side direction of the beam portions 12 (see Figure 11 ).

[0137] The plurality of ribs 551 of the second support member 55 abut against the two raised portions 1p of the two beam portions 12 respectively. Thereby, the fixing unit 5b is stably positioned in the longitudinal direction D3.

[0138] By adopting the image forming apparatus 10, the positioning mechanism for arranging the heating unit 5a and the fixing unit 5b at the target positions is realized by a simple mechanism.

[0139] The scope of the present invention is not limited to the above content, but is defined by the claims. Therefore, it can be considered that the embodiments described in this specification are only illustrative examples and not restrictive. Accordingly, all changes that do not depart from the scope and boundary of the claims, and content equivalent to the scope and boundary of the claims, are included within the scope of the claims.

Claims

1. An image forming apparatus, characterized in that, comprising: a main body frame; a heating unit supported by the main body frame; and a fixing unit disposed beside the heating unit and supported by the main body frame, wherein the main body frame has: two pillar portions extending longitudinally beside the fixing unit and disposed at intervals in a first direction, which is the depth direction of the image forming apparatus; and two beam portions extending in a second direction below the heating unit and the fixing unit and disposed at intervals in the first direction, respectively connected to the two pillar portions, the second direction being the width direction of the image forming apparatus and the arrangement direction of the heating unit and the fixing unit, the fixing unit is disposed between the heating unit and the two pillar portions, the heating unit has: a heater; and a first support member supporting the heater and placed on the two beam portions in a state of being bridged over the two beam portions, the fixing unit has: a fixing member heated by the heater; a pressing member applying force to the fixing member for a sheet body; and a second support member supporting the fixing member and the pressing member and placed on the two beam portions in a state of being bridged over the two beam portions, the image forming apparatus further includes: an elastic heating unit biasing member that biases the first support member toward the second support member by using elastic force, causing the first support member to abut against the second support member and causing the second support member to abut against the two pillar portions; an operation unit that can move between a first position and a second position by being operated; and a linkage mechanism that moves the heating unit along the second direction in linkage with the movement of the operation unit, wherein when the operation unit moves from the first position to the second position, the linkage mechanism moves the first support member from a reference position where it abuts against the second support member to a retracted position away from the second support member, furthermore, when the operation unit moves from the second position to the first position, the linkage mechanism moves the first support member from the retracted position to the reference position, when the first support member is in the retracted position, the fixing unit can be pulled out from the main body frame in a removal direction along the first direction.

2. The image forming apparatus according to claim 1, characterized in that, one of the first support member and the second support member has a concave first fitting portion opening laterally, the other of the first support member and the second support member has a convex second fitting portion, and when the first support member moves from the retracted position to the reference position, the second fitting portion is inserted into the first fitting portion, by inserting the second fitting portion into the first fitting portion, relative movement of the first support member and the second support member in the longitudinal direction is restricted.

3. The image forming apparatus according to claim 1 or 2, characterized in that, the image forming apparatus further includes an exterior member covering the main body frame, the exterior member has: An opening through which the fixing unit pulled out from the main body frame can pass; and A cover portion that is rotatable between a closed position for closing the opening and an open position for opening the opening, The cover portion also serves as the operation portion, The closed position of the cover portion is the first position of the operation portion, The open position of the cover portion is the second position of the operation portion.

4. The image forming apparatus according to claim 3, Characterized in that, The image forming apparatus further includes an elastic fixing unit biasing member, which is supported by the cover portion or the fixing unit, and is sandwiched between the cover portion and the fixing unit when the cover portion is in the closed position, thereby biasing the second support member in the mounting direction opposite to the removal direction by an elastic force, The second support member has a beam contact portion, and when the cover portion is in the closed position, the beam contact portion contacts the side surface of one of the two beam portions by the force received from the fixing unit biasing member.

5. The image forming apparatus according to claim 1 or 2, Characterized in that, The image forming apparatus further includes a downward biasing mechanism that biases the fixing unit downward.

6. The image forming apparatus according to claim 5, Characterized in that, The image forming apparatus further includes a drive mechanism having a drive gear for transmitting a rotational force to the fixing unit through the drive gear, The fixing unit is provided with a driven gear that meshes with the drive gear and transmits the rotational force received from the drive gear to the fixing member or the pressing member, The drive mechanism also serves as the downward biasing mechanism.

7. The image forming apparatus according to claim 1 or 2, Characterized in that, The heater is an electromagnetic induction heating type heating device.

Images