Image forming device

Abstract

To achieve a mechanism that arranges a heating unit and a fixing unit at target positions with a simple mechanism.SOLUTION: A heating unit urging member 60 urges, by an elastic force, a first support 54 of a heating unit 5a toward a second support 55 of a fixing unit 5b. The heating unit urging member 60 brings the first support 54 into contact with the second support 55 and brings the second support 55 into contact with two column parts 11. An interlocking mechanism 6 moves the heating unit 5a along a second direction that is an arrangement direction of the heating unit 5a and the fixing unit 5b interlocking with the movement of an operating section 102. When the operating section 102 moves from a first position to a second position, the interlocking mechanism 6 moves the first support 54 from a reference position where it is in contact with the second support 55 to a retreat position where it is separated from the second support 55.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic image forming apparatus equipped with a heating unit and a fixing unit. [Background technology]

[0002] An electrophotographic image forming apparatus transfers a toner image from an image carrier to a sheet, and fixes the toner image onto 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] It is also known that the image forming apparatus includes a mechanism that moves the heating unit from a heating position to a retracted position in response to 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] Patent Publication No. 2021-86093 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to improve the heating efficiency of the fixing member, it is important that the heater is positioned appropriately relative to the fixing member. When an electromagnetic induction heating device is used as the heater, the accuracy of the heater position is particularly important.

[0007] On the other hand, it is desirable that the unit positioning mechanism for arranging the heating unit and the fixing unit at the desired positions be as simple as possible.

[0008] 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 retracted position away from the fixing unit.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that uses a simple mechanism to position a heating unit and a fixing unit at desired positions. [Means for solving the problem]

[0010] According to one aspect of the present invention, an image forming apparatus 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 supported by the main body frame. The main body frame has two support columns and two beams. The two support columns are formed to extend vertically beside the fixing unit and are spaced apart in a first direction. The two beams are formed to extend horizontally below the heating unit and the fixing unit, are spaced apart in the first direction, and are connected to the two support columns, respectively. The fixing unit is disposed between the heating unit and the two support columns. The heating unit has a heater and a first support. The first support supports the heater and is placed on the two beams while spanning them. The fixing unit has a fixing member, a pressure member, and a second support. The fixing member is heated by the heater. The pressure member biases the sheet toward the fixing member. The second support supports the fixing member and the pressure member and is placed on the two beam portions while spanning the two beam portions. The image forming apparatus further includes an elastic heating unit biasing member, an operating unit, and an interlocking mechanism. The heating unit biasing member biases the first support toward the second support by elastic force, thereby causing the first support to abut against the second support and the second support to abut against the two support columns. The operating unit is movable between a first position and a second position when operated. The interlocking mechanism moves the heating unit along a second direction, which is the arrangement direction of the heating unit and the fixing unit, in conjunction with movement of the operating unit. When the operating unit moves from the first position to the second position, the interlocking mechanism moves the first support from a reference position where it abuts against the second support to a retracted position spaced apart from the second support. Furthermore, the interlocking mechanism moves the first support from the retracted position to the reference position when the operation portion moves from the second position to the first position.When the first support body is located at the retracted position, the fixing unit can be pulled out from the main body frame in a removal direction along the first direction. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an image forming apparatus that uses a simple mechanism to arrange the heating unit and the fixing unit at the desired positions. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of the main part of the fixing device in the image forming apparatus according to the embodiment. [Figure 3] FIG. 3 is a perspective view of a main body frame of the image forming apparatus according to the embodiment. [Figure 4] FIG. 4 is a front view of the fixing device and the interlocking mechanism in the biased state in the image forming apparatus according to the embodiment. [Figure 5] FIG. 5 is a front view of the fixing device and the interlocking mechanism in the retracted state in the image forming apparatus according to the embodiment. [Figure 6] FIG. 6 is a perspective view of a fixing unit in the image forming apparatus according to the embodiment. [Figure 7] FIG. 7 is a plan view of the fixing device and the interlocking mechanism in the biased state in the image forming apparatus according to the embodiment. [Figure 8] FIG. 8 is a plan view of the fixing device and the interlocking mechanism in the retracted state in the image forming apparatus according to the embodiment. [Figure 9] FIG. 9 is a perspective view of the fixing unit and the surrounding area of ​​the cover member in the image forming apparatus according to the embodiment. [Figure 10] FIG. 10 is a diagram showing a cross section of a support column and a lateral contact portion of a fixing unit in an image forming apparatus according to an embodiment. [Figure 11]FIG. 11 is a diagram showing a cross section of a beam portion and a lower contact portion of a fixing unit in an image forming apparatus according to an embodiment. [Figure 12] FIG. 12 is a diagram showing the rear surface and drive mechanism of the fixing unit in the image forming apparatus according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention.

[0014] [Configuration of image forming apparatus 10] The image forming apparatus 10 according to the embodiment performs a print process by electrophotography. The print process is a process of forming an image on a sheet 9.

[0015] 1, an image forming apparatus 10 includes a sheet storage unit 2, a sheet transport device 3, and a printing device 4. The sheet transport device 3 and the printing device 4 are housed in a main body 1, which is a housing.

[0016] The sheet storage section 2 can store a plurality of sheets 9. The sheet transport device 3 includes a sheet feeding device 30 and a plurality of pairs of transport rollers 31.

[0017] The sheet feeding device 30 sends out the sheets 9 in the sheet storage unit 2 one by one to the conveying path 300. The conveying path 300 is a passage for the sheets 9.

[0018] The plurality of pairs of transport rollers 31 transport the sheet 9 along the transport path 300. One of the plurality of pairs of transport rollers 31 discharges the sheet 9 on which an image has been formed from the transport path 300 onto the discharge tray 10a.

[0019] The printing device 4 performs the printing process on the sheet 9 conveyed along the conveying path 300. The image formed on the sheet 9 is a toner image.

[0020] 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 photoconductor 41, a charging device 42, a developing device 43, and a drum cleaning device 44.

[0021] The charging device 42 charges the surface of the photoconductor 41. The optical scanning unit 40 scans a light beam over the charged surface of the photoconductor 41. As a result, the optical scanning unit 40 forms an electrostatic latent image on the surface of the photoconductor 41.

[0022] The developing device 43 develops the electrostatic latent image into a toner image by supplying toner to the surface of the photoreceptor 41. The transfer device 45 transfers the toner image formed on the surface of the photoreceptor 41 to a sheet 9.

[0023] The transfer device 45 transfers the electrostatic latent image onto the sheet 9 at a transfer position P1 on the transport path 300.

[0024] In this embodiment, the printing device 4 is a tandem color printing device having a plurality of image forming units 4x. The transfer device 45 also has an intermediate transfer belt 450, a plurality of primary transfer devices 451, a secondary transfer device 452, and a belt cleaning device 453.

[0025] 1, the printing device 4 includes four image forming units 4x corresponding to the four colors of toner: yellow, magenta, cyan, and black. The transfer device 45 includes four primary transfer devices 451 corresponding to the four image forming units 4x.

[0026] The intermediate transfer belt 450 is rotatably supported by a plurality of support rollers 454. One of the plurality of support rollers 454 is rotated by being driven by a belt driving device (not shown), thereby rotating the intermediate transfer belt 450.

[0027] Each primary transfer device 451 transfers the toner image formed on the surface of the photoconductor 41 in each image forming unit 4x onto the surface of the intermediate transfer belt 450. As a result, a composite toner image, in which the four color toner images are combined, is formed on the surface of the intermediate transfer belt 450.

[0028] The intermediate transfer belt 450 rotates while carrying the composite toner image. A secondary transfer device 452 transfers the composite toner image formed on the surface of the intermediate transfer belt 450 onto a sheet 9 at a transfer position P1.

[0029] The drum cleaning device 44 removes the 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 after passing through the primary transfer device 451.

[0030] The belt cleaning device 453 removes secondary waste toner from the surface of the intermediate transfer belt 450. The secondary waste toner is toner remaining on the surface of the intermediate transfer belt 450 after passing through the secondary transfer device 452.

[0031] The fixing device 5 applies heat and pressure to the composite toner image on the sheet 9 at a fixing position P2 on the conveying path 300. In this way, the fixing device 5 fixes the composite toner image to the sheet 9. The fixing position P2 is a position downstream of the transfer position P1 in the sheet conveying direction.

[0032] As shown in FIG. 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.

[0033] The fixing belt 52 is a flexible cylindrical member that encloses a fixing roller 520. The fixing belt 52 is heated by a heater 51.

[0034] Fixing roller 520 is a cylindrical member that supports fixing belt 52 on its inside. Fixing roller 520 has cylindrical core metal portion 521 and elastic portion 522 formed on the outer periphery of core metal portion 521.

[0035] The fixing roller 520 is rotatably supported, and the fixing belt 52 is rotatable together with the fixing roller 520.

[0036] The fixing belt 52 has a conductive substrate, an elastic layer formed on the outer periphery of the substrate, and a release layer formed on the outer periphery of the elastic layer.

[0037] The heater 51 is disposed opposite the outer peripheral surface of the fixing belt 52. In this embodiment, the heater 51 is an electromagnetic induction heating device. The heater 51 mainly heats the base material of the fixing belt 52 by electromagnetic induction.

[0038] Pressure roller 53 is rotatably supported. Similar to fixing roller 520, pressure roller 53 also has a cylindrical core metal portion 531 and an elastic portion 532 formed on the outer periphery of core metal portion 531.

[0039] The pressure roller 53 is driven to rotate by a drive unit (not shown). The fixing belt 52 and the fixing roller 520 rotate in conjunction with the pressure roller 53.

[0040] 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.

[0041] 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 presses the sheet 9 against the fixing belt 52.

[0042] When the sheet 9 adheres to the fixing belt 52, the sheet separating member 5200 separates the sheet 9 from the fixing belt 52.

[0043] In this embodiment, the fixing device 5 is divided into a heating unit 5a and a fixing unit 5b (see FIGS. 4 and 5). The heating unit 5a has a heater 51 and a first support 54. The fixing unit 5b has a fixing belt 52, a fixing roller 520, a pressure roller 53, and a second support 55.

[0044] First support 54 is a member that supports heater 51. Second support 55 is a member that supports fixing belt 52, fixing roller 520, and pressure roller 53. Fixing belt 52 is supported by second support 55 via fixing roller 520.

[0045] 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 FIGS. 5 and 8).

[0046] Incidentally, it is important to position the heater 51 appropriately relative to the fixing belt 52 in order to improve 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 accuracy of the position of the heater 51 is particularly important.

[0047] On the other hand, it is desirable that the unit positioning mechanism for positioning the heating unit 5a and the fixing unit 5b at the desired positions be as simple as possible.

[0048] 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.

[0049] Image forming apparatus 10 uses a simple mechanism to position heating unit 5a and fixing unit 5b at desired positions. The mechanism for positioning heating unit 5a and fixing unit 5b will be described below.

[0050] [Mechanism for positioning heating unit 5a and fixing unit 5b] 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 FIGS. 3 and 9).

[0051] The main body frame 1x is made up of a combination of multiple metal pipes (see FIG. 3). The heating unit 5a and the fixing unit 5b are supported by the main body frame 1x. The fixing unit 5b is disposed next to the heating unit 5a.

[0052] The exterior member 100 is attached to the main body frame 1x (see FIG. 9). The exterior member 100 forms the exterior of the image forming apparatus 10.

[0053] The plurality of metal pipes that make up the main body frame 1x have two support columns 11 and two beams 12 (see FIG. 3).

[0054] The two support columns 11 are formed to extend in a vertical direction D3 and are arranged at an interval in the first direction D1 (see FIG. 3). The vertical direction D3 is the up-down direction.

[0055] The two support pillars 11 are formed to the sides of the fixing unit 5b and extend in the vertical direction D3 (see FIGS. 4 and 9).

[0056] The first direction D1 is also a direction along the center line of rotation of the fixing belt 52 and the pressure roller 53. In this embodiment, the first direction D1 is the depth direction of the image forming apparatus 10.

[0057] The exterior member 100 has an opening 101 and a cover member 102 (see FIG. 9). The opening 101 is a portion where an opening that opens one end of the fixing unit 5b in the first direction D1 is formed.

[0058] The cover member 102 is supported by a first support shaft 102x. This allows the cover member 102 to rotate about the first support shaft 102x. The cover member 102 is rotatable between a closed position where the opening 101 is closed and an open position where the opening 101 is open.

[0059] 4 and 7 show the fixing device 5 when the cover member 102 is in the closed position, and FIGS. 5 and 8 show the fixing device 5 when the cover member 102 is in the open position.

[0060] 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). When the locking mechanism is released, the cover member 102 can be rotated from the closed position to the open position.

[0061] The two support columns 11 include a first support column 11a disposed on the front side of the image forming apparatus 10 and a second support column 11b disposed on the rear side of the image forming apparatus 10 (see FIG. 3).

[0062] The two beams 12 are formed below the heating unit 5a and the fixing unit 5b, extending in the horizontal direction, and are spaced apart in the first direction D1 (see FIGS. 3 and 4). The horizontal direction is the width direction of the image forming apparatus 10.

[0063] The two beams 12 are respectively connected to the two support columns 11 (see FIG. 3). For example, the two beams 12 are respectively connected to the two support columns 11 by welding.

[0064] 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 rear side of the image forming apparatus 10 (see FIG. 3).

[0065] The fixing unit 5b is disposed between the heating unit 5a and the two support pillars 11 (see FIG. 3).

[0066] The first support 54 of the heating unit 5a is placed on the two beams 12 while being bridged across the two beams 12. Similarly, the second support 55 of the fixing unit 5b is placed on the two beams 12 while being bridged across the two beams 12.

[0067] That is, neither the heating unit 5a nor the fixing unit 5b is fixed to the main body frame 1x by fasteners such as screws.

[0068] The heating unit 5a and the fixing unit 5b are placed on two beams 12 with their longitudinal directions aligned with the first direction D1 (see FIGS. 7 and 8).

[0069] 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 arrangement direction of the heating unit 5a and the fixing unit 5b. The second direction D2 is a direction that intersects with the first direction D1.

[0070] The image forming apparatus 10 further includes a first spring 60 and an interlocking mechanism 6 (see FIGS. 4, 5, 7, and 8). For example, the first spring 60 is supported by a protrusion 544 of the first support 54.

[0071] The first spring 60 urges the first support 54 toward the second support 55 by elastic force (see FIG. 4). The first spring 60 is an example of an elastic heating unit urging member.

[0072] The biasing force F1 of the first spring 60 against the first support 54 is greater than the static friction force of the heating unit 5a and the fixing unit 5b against the two beam portions 12.

[0073] The first support 54 has a plurality of ribs 541 in contact with the upper surfaces of the two beam portions 12. Similarly, the second support 55 has a plurality of ribs 551 in contact with the upper surfaces of the two beam portions 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.

[0074] The first spring 60 biases the first support 54, thereby causing the first support 54 to abut against the second support 55. Furthermore, the first spring 60 biases the first support 54, thereby causing the second support 55 to abut against the two support columns 11. In other words, the first spring 60 biases the second support 55 via the first support 54.

[0075] The first support body 54 has a plurality of first fitting portions 542 each having a concave shape that opens in the horizontal direction (see FIGS. 4 and 5). The first support body 54 has four first fitting portions 542 formed at intervals in the first direction D1 and the vertical direction D3.

[0076] The second support body 55 has a plurality of convex second fitting portions 553 that can be fitted into the plurality of first fitting portions 542. The second support body 55 has four second fitting portions 553 that correspond to the four first fitting portions 542.

[0077] The first springs 60 bias the first support 54, so that the inner surfaces of the recessed portions of the four first fitting portions 542 come into contact with the four second fitting portions 553 (see FIG. 4).

[0078] Furthermore, the second fitting portion 553 fits into the first fitting portion 542, thereby restricting the relative movement of the first support body 54 and the second support body 55 in the vertical direction D3.

[0079] Alternatively, the second support 55 may include the first fitting portion 542 and the first support 54 may include the second fitting portion 553.

[0080] The second support 55 also has a plurality of pillar contact portions 552 that protrude toward the two support pillars 11 (see FIGS. 4 and 6). The plurality of pillar contact portions 552 come into contact with the side surfaces of the two support pillars 11.

[0081] The interlocking mechanism 6 moves the heating unit 5a in the second direction D2 in conjunction with the movement of the cover member 102.

[0082] When the cover member 102 moves from the closed position to the open position, the interlocking mechanism 6 moves the first support 54 of the heating unit 5a from the reference position to the retracted position (see FIGS. 4 and 5).

[0083] The reference position is the position of the first support 54 when the first support 54 is in contact with the second support 55. The retracted position is the position of the first support 54 when the first support 54 is separated from the second support 55.

[0084] When the first support 54 moves from the reference position to the retracted position, the four second fitting portions 553 move away from the four first fitting portions 542 (see FIG. 5).

[0085] Note that the first support 54 being located at the reference position is synonymous with the heating unit 5a being located at the reference position, and the first support 54 being located at the retracted position is synonymous with the heating unit 5a being located at the retracted position.

[0086] When the first support body 54 is located at the retracted position, the fixing unit 5b can be pulled out from the main body frame 1x in a removal direction D11 along the first direction D1 (see FIG. 8).

[0087] 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.

[0088] On the other hand, when the cover member 102 moves from the open position to the closed position, the interlocking mechanism 6 moves the first support 54 from the retracted position to the reference position (see FIGS. 7 and 8).

[0089] When the first support 54 moves from the retracted position to the reference position, the four second fitting portions 553 fit into the four first fitting portions 542 (see FIG. 4).

[0090] The cover member 102 also serves as an operating unit that can be moved between a first position and a second position by being operated. The closed position of the cover member 102 corresponds to the first position of the operating unit. The open position of the cover member 102 corresponds to the second position of the operating unit.

[0091] For example, the interlocking mechanism 6 includes an action member 61, two first link members 62, a second link member 63, and a third link member 64 (see FIGS. 7 and 8).

[0092] The acting member 61 is disposed so as to be movable along the second direction D2. The 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.

[0093] The third link member 64 is supported by a second support shaft 640. The third link member 64 is rotatable around 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.

[0094] The interlocking mechanism 6 shown in FIGS. 7 and 8 is a link mechanism that converts the rotational movement of the cover member 102 into the movement of the action member 61 along the second direction D2.

[0095] When the cover member 102 rotates, the second link member 63 moves along the first direction D1 due to the action of the third link member 64.

[0096] When the second link member 63 moves along the first direction D1, the action member 61 moves along the second direction D2 due to the action of the first link member 62.

[0097] When the cover member 102 moves from the closed position to the open position, the interlocking 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 interlocking mechanism 6 moves the acting member 61 in a direction approaching the fixing unit 5b.

[0098] The first spring 60 is disposed between the acting member 61 and the first support 54 of the heating unit 5a (see FIGS. 4 and 5). When the acting member 61 approaches the first support 54 along the second direction D2, the acting member 61 pushes the first spring 60 toward the first support 54 (see FIG. 4).

[0099] The acting member 61 presses the first spring 60 toward the first support 54, and the first spring 60 urges the first support 54 toward the reference position.

[0100] The acting member 61 has an engaging portion 612 that can engage with the engaged portion 543 of the first support body 54 (see FIG. 4). When the acting member 61 moves in the second direction D2 in a direction away from the first support body 54, the engaging portion 612 engages with the engaged portion 543.

[0101] When the acting member 61 moves in the second direction D2 away from the first support 54, the first support 54 receives a force from the acting member 61 through the engagement portion 612 and moves from the reference position to the retracted position (see Figure 5).

[0102] On the other hand, when the acting member 61 moves in the direction approaching the first support 54 along the second direction D2, the first support 54 receives force from the acting member 61 through the first spring 60 and moves from the retracted position to the reference position (see Figure 4).

[0103] The heating unit 5a and the fixing unit 5b are sandwiched between the first spring 60 and the two support pillars 11, and are thereby positioned in the second direction D2.

[0104] The interlocking mechanism 6 may include a gear mechanism such as a rack-and-pinion mechanism. In that case, the interlocking mechanism 6 also converts the rotational movement of the cover member 102 into the movement of the acting member 61 along the second direction D2.

[0105] Furthermore, heating unit 5a and fixing unit 5b are positioned in vertical direction D3 by being placed on two beams 12. The loads of heating unit 5a and fixing unit 5b limit the upward movement of heating unit 5a and fixing unit 5b.

[0106] 12, the image forming apparatus 10 includes a drive mechanism 7 having a drive gear 70. The drive mechanism 7 includes a motor (not shown). The drive mechanism 7 transmits a rotational force to the fixing unit 5b through the drive gear 70.

[0107] The fixing unit 5b includes a driven gear 530 that meshes with the driving gear 70. The driven gear 530 transmits the rotational force received from the driving gear 70 to the fixing roller 520. This causes the fixing belt 52 to rotate. That is, the driven gear 530 transmits the rotational force to the fixing belt 52 via the fixing roller 520.

[0108] 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.

[0109] The direction of pressure F2 that the teeth of the driven gear 530 receive from the teeth of the driving gear 70 is diagonally downward toward the two support columns 11. Therefore, 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 columns 11 and the two beams 12.

[0110] The fixing unit 5b is more firmly positioned in the second direction D2 and the vertical direction D3 by the pressure F2 received from the drive gear 70. Furthermore, the heating unit 5a, together with the fixing unit 5b, is also firmly positioned in the vertical direction D3 by the action of the first fitting portion 542 and the second fitting portion 553.

[0111] In this embodiment, the drive mechanism 7 also serves as a downward biasing mechanism that biases the fixing unit 5b downward.

[0112] The image forming apparatus 10 further includes a cover biasing mechanism 8 attached to the inner surface of the cover member 102 (see FIGS. 7 and 8). The second support 55 of the fixing unit 5b also has a beam abutment portion 554 that protrudes downward from the bottom surface (see FIGS. 4, 5, 6 and 9).

[0113] The cover biasing mechanism 8 includes a second spring 80, a spring case 81, and a cap portion 82 (see FIG. 7).

[0114] The spring case 81 houses the second spring 80. The cap portion 82 is attached so as to be movable relative to the spring case 81. The second spring 80 is an example of an elastic fixing unit biasing member.

[0115] When the cover member 102 is located at the closed position, the second spring 80 is sandwiched between the cover member 102 and the second support body 55 of the fixing unit 5b. In this embodiment, the second spring 80 and the cap portion 82 are sandwiched between the cover member 102 and the second support body 55.

[0116] The second spring 80 is sandwiched between the cover member 102 and the second support body 55, and thereby urges the second support body 55 by its elastic force in the mounting direction D12 (see FIG. 7). The mounting direction D12 is the opposite direction to the removal direction D11.

[0117] Furthermore, when the cover member 102 is located at the closed position, the force that the second support 55 receives from the second spring 80 causes the beam abutment portion 554 to abut against the side surface of one of the two beam portions 12. In this embodiment, the beam abutment portion 554 abuts against the side surface of the second beam portion 12b.

[0118] 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.

[0119] The cover biasing mechanism 8 may be attached to the second support 55 of the fixing unit 5b.

[0120] Each support column 11 has four side surfaces, each of which has two raised portions 1p that form a ridge along the longitudinal direction of the support column 11 (see FIG. 10).

[0121] The plurality of pillar contact portions 552 of the second support body 55 come into contact with the two raised portions 1p of each of the two support pillars 11. This allows the fixing unit 5b to be stably positioned in the second direction D2.

[0122] Similarly, each beam portion 12 also has side surfaces on all four sides. Each of the four side surfaces of each beam portion 12 has two raised portions 1p that form ridges along the longitudinal direction of the beam portion 12 (see FIG. 11).

[0123] The plurality of ribs 551 of the second support body 55 come into contact with the two raised portions 1p of each of the two beam portions 12. This allows the fixing unit 5b to be stably positioned in the vertical direction D3.

[0124] By employing the image forming apparatus 10, the positioning mechanism for positioning the heating unit 5a and the fixing unit 5b at the desired positions can be realized by a simple mechanism. [Explanation of symbols]

[0125] 1: Main body 1p: Protuberance 1x: Main frame 2: Sheet storage area 3: Sheet transport device 4: Printing device 4x: Image forming section 5: Fixing device 5a: Heating unit 5b: Fixing unit 6: Interlocking mechanism 7: Drive mechanism 8: Cover biasing mechanism 10: Image forming device 11: Support section 11a: 1st pillar part 11b:Second pillar part 12:Beam part 12a: 1st beam part 12b: 2nd beam part 45: Transcription device 51: Heater 52: Fixing belt 53: Pressure roller 54: 1st support 55:Second support 60: First spring 70: Drive gear 80: Second spring 100: Exterior material 101: Opening 102: Cover member 520: Fuser roller 530: Driven gear 541: Rib 542: First fitting part 551: Rib 552: Column contact part 553: Second fitting part 554: Beam contact part

Claims

1. The body frame and a heating unit supported by the main body frame; a fixing unit disposed beside the heating unit and supported by the main body frame, The main body frame is two support pillars formed beside the fixing unit and extending in a vertical direction and spaced apart in a first direction; two beam portions formed below the heating unit and the fixing unit and extending in a horizontal direction, spaced apart in the first direction, and connected to the two support columns, respectively; the fixing unit is disposed between the heating unit and the two support columns, The heating unit comprises: A heater and a first support member that supports the heater and is placed on the two beam portions in a state of being bridged across the two beam portions, The fixing unit includes: a fixing member heated by the heater; a pressure member that presses the sheet against the fixing member; a second support member that supports the fixing member and the pressure member and is placed on the two beam portions in a spanning state across the two beam portions, the image forming apparatus, an elastic heating unit biasing member that biases the first support toward the second support by elastic force, thereby causing the first support to abut against the second support and causing the second support to abut against the two support columns; an operating unit that is movable between a first position and a second position when operated; a linkage mechanism that moves the heating unit along a second direction, which is an arrangement direction of the heating unit and the fixing unit, in conjunction with movement of the operation unit, the interlocking mechanism moves the first support from a reference position in which the first support abuts against the second support to a retracted position spaced apart from the second support when the operation unit moves from the first position to the second position, Furthermore, the interlocking mechanism moves the first support from the retracted position to the reference position when the operation unit moves from the second position to the first position, When the first support member is located at the retracted position, the fixing unit can be pulled out from the main body frame in a removal direction along the first direction.

2. one of the first support body and the second support body has a first fitting portion having a concave shape that opens in a lateral direction; the other of the first support body and the second support body has a convex second fitting portion that fits into the first fitting portion when the first support body moves from the retracted position to the reference position, The image forming apparatus according to claim 1 , wherein the second fitting portion fits into the first fitting portion, thereby restricting relative movement of the first support and the second support in the vertical direction.

3. further comprising an exterior member covering the main body frame, The exterior member is an opening through which the fixing unit can pass when pulled out from the main body frame; a cover portion that is rotatable between a closed position that closes the opening and an open position that opens 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, 3. The image forming apparatus according to claim 1, wherein the open position of the cover portion is the second position of the operation portion.

4. a fixing unit biasing member that is supported by the cover portion or the fixing unit and that is sandwiched between the cover portion and the fixing unit when the cover portion is located at the closed position, thereby biasing the second support member by elastic force in an attachment direction opposite to the removal direction; 4. The image forming apparatus according to claim 3, wherein the second support member has a beam abutment portion that abuts against one side of the two beam portions due to a force received from the fixing unit biasing member when the cover portion is located in the closed position.

5. The image forming apparatus according to claim 1 , further comprising a downward biasing mechanism that biases the fixing unit downward.

6. a drive mechanism having a drive gear and transmitting a rotational force to the fixing unit through the drive gear; the fixing unit includes 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 pressure member; 6. The image forming apparatus according to claim 5, wherein the drive mechanism also serves as the downward biasing mechanism.

7. 7. The image forming apparatus according to claim 1, wherein the heater is an electromagnetic induction heating type heating device.

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