JP2009015153A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attach and detach an intermediate transfer unit to and from the predetermined position of a body frame, with a simple configuration and a simple operation. <P>SOLUTION: In an image forming apparatus, when the intermediate transfer unit 31A is attached, a user holds the whole intermediate transfer unit 31A, first moves the first guide bosses 87a and 87b of the intermediate transfer unit 31A along the left and right inclined guides 82a and 82b of the body frame 6, to engage the second guide bosses 93a and 93b of the intermediate transfer unit 31A with the left and right rocking guides 90a and 90b of the body frame 6 and then, rocks and positions the whole intermediate transfer unit 31A, based on the second guide bosses 93a and 93b in the engaged state as a reference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which an intermediate transfer belt is unitized with other members, and is attached to and detached from a main body frame as an intermediate transfer unit.

  In an image forming apparatus such as a printer or a copying machine, a driving roller, a driven roller, an intermediate transfer belt stretched on the driving roller, and an intermediate transfer belt are integrally incorporated into a transfer frame to form a unit, and an intermediate transfer unit is attached to a main body frame (device main body) What was comprised so that attachment or detachment was possible is known (for example, refer patent document 1).

In this apparatus, a plurality of process units each having a photosensitive drum (image carrier) are arranged in parallel in the left-right direction, and each process unit can be attached and detached in the front-rear direction. Further, the intermediate transfer unit having the intermediate transfer belt can be attached / detached in a direction orthogonal to the attachment / detachment direction of the process unit in the front-rear direction, and is positioned below the process cartridge after attachment. It has become.
JP 2003-167411 A

  According to the above-mentioned Patent Document 1, when the intermediate transfer unit is mounted and positioned in a state where the process unit is mounted on the main body frame, the user firstly moves the intermediate transfer unit along the guide rail facing in the left-right direction. Is moved from the outside to the inside of the main body frame, and is mounted below the process unit. Thereafter, the user positions the intermediate transfer unit at a predetermined position by the lifting mechanism. The lifting mechanism has an eccentric cam receiving portion provided on the transfer frame, an eccentric cam provided on the main body frame side, a contact / separation lever, and the like, and the user rotates the contact / separation lever by 180 degrees. Thus, the eccentric cam rotates, and this rotation pushes up the eccentric cam receiving portion, thereby raising the intermediate transfer unit and bringing the intermediate transfer belt into contact with the photosensitive drum. At this time, the positioning convex portion on the intermediate transfer unit side is engaged with the positioning concave portion provided on the main body frame side, so that the intermediate transfer unit is positioned at a predetermined position.

  As described above, Patent Document 1 has a problem in that the structure for positioning the intermediate transfer unit at a predetermined position of the main body frame is complicated, and the user's operation for positioning is complicated. That is, as a structure for positioning the intermediate transfer unit, a guide rail, an elevating mechanism (an eccentric cam receiving portion, an abutting / separating lever, an eccentric cam), a positioning concave portion / a convex portion, and the like are provided. In addition, before the positioning of the intermediate transfer unit with respect to the main body frame is completed, the user first moves the intermediate transfer unit in the left-right direction along the guide rail, attaches it below the process unit, and then makes contact Positioning can be performed by rotating the separation lever 180 degrees, raising the intermediate transfer unit via an eccentric cam or the like, and engaging the positioning convex portion with the positioning concave portion. That is, it is necessary to perform the mounting operation and the positioning operation individually, and the work is complicated. Note that when the intermediate transfer unit positioned at a predetermined position of the main body frame is taken out from the main body frame, the work reverse to the above is followed, and the work is complicated.

  Therefore, the present invention has a simple configuration for mounting and positioning the intermediate transfer unit with respect to a predetermined position of the main body frame, and the operation of attaching and detaching the intermediate transfer unit to the predetermined position by the user is simple and easy. An object of the present invention is to provide an image forming apparatus as described above.

  The invention according to claim 1 comprises: a main body frame having an opening in the upper part; and a removable intermediate transfer unit that is mounted and positioned at a predetermined position of the main body frame from above via the opening, An intermediate transfer unit includes a transfer frame, a first roller and a second roller rotatably supported by the transfer frame, and an intermediate transfer belt stretched endlessly on the first roller and the second roller. The present invention relates to a forming apparatus. In the image forming apparatus according to the present invention, the transfer frame includes a slide boss projecting in the belt width direction of the intermediate transfer belt in the vicinity of the first roller which is the leading end side when mounted, and outward from the transfer frame. And a swing boss disposed coaxially with the first roller, and the body frame is disposed in the vicinity of one end corresponding to the front end side of the body frame after mounting. And the tilt guide is configured such that the downstream side in the mounting direction of the intermediate transfer unit is tilted downward, supports the slide boss from below, and guides the swing boss toward the swing guide. The swing guide is arranged at the predetermined position by guiding the swing operation of the entire intermediate transfer unit with the engaged swing boss as a reference. There.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the inclined guide includes the slide boss before the swing boss of the intermediate transfer unit at the time of mounting is engaged with the swing guide. It has the feature that it has a notch part which permits it to move below.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the intermediate transfer unit urges the intermediate transfer belt from the back side when the intermediate transfer unit is disposed at the predetermined position. It has a primary transfer roller that abuts the surface side with the photosensitive drum disposed on the main body frame side.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the first roller is disposed on the main body frame side when the intermediate transfer unit is disposed at the predetermined position. It is a secondary transfer roller facing roller that sandwiches the intermediate transfer belt with the transfer roller.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the intermediate transfer unit has a first contact that is electrically connected to the primary transfer roller, and the main body frame includes the intermediate transfer unit. A second contact connected to a power source disposed on the main body frame side is disposed at a position where it contacts the first contact when disposed at the predetermined position.

  According to the first aspect of the present invention, the intermediate transfer unit is moved so that the slide boss is along the inclined guide on the main body frame side, and the swing boss is engaged with the swing guide. Thereafter, the intermediate transfer unit is swung with reference to the swing boss while being engaged with the swing guide, so that the intermediate transfer unit can be positioned at a predetermined position. As described above, as a configuration for mounting and positioning the intermediate transfer unit on the main body frame, a slide boss and a swing boss are provided on the intermediate transfer unit side, while an inclination guide and a swing guide are provided on the main body frame side. This can be done with a simple configuration such as In addition, since the swing guide and the swing boss serve as both a guide for mounting and a guide for positioning, unlike the prior art, there is no need to separately provide a member for positioning. Accordingly, the configuration can be simplified. Furthermore, as a mounting / positioning operation by the user or the like, the user holds the entire intermediate transfer unit and first moves the slide boss of the intermediate transfer unit along the slide guide of the main body frame, thereby swinging the main body frame. The swinging boss of the intermediate transfer unit can be engaged with the moving guide, and then the entire intermediate transfer unit is swung with reference to the swinging boss in the engaged state. The positioning operation can be completed. That is, unlike the conventional case where a positioning operation is required after the mounting operation, the mounting operation and the positioning operation can be performed as a series of operations without being distinguished.

  According to the second aspect of the present invention, when the slide boss is moved along the slide guide, the swing boss is moved to the notch portion of the slide guide before the swing boss is engaged with the swing guide (for example, immediately before). Therefore, when the swing boss is engaged with the swing guide, the intermediate transfer unit can naturally swing downward with the swing boss as a reference.

  According to the third aspect of the present invention, the intermediate transfer unit at a predetermined position of the main body frame is disposed, so that the primary transfer roller is disposed at a position where the intermediate transfer belt is sandwiched between the primary transfer roller and the photosensitive drum. Thereby, a nip (primary transfer nip) formed between the intermediate transfer belt and the photosensitive drum can be secured with high accuracy.

  According to the invention of claim 4, the first roller is a secondary transfer counter roller, and the intermediate transfer unit is mounted on the main body frame with reference to the secondary transfer counter roller. A nip (secondary transfer nip) formed between the secondary transfer roller and the secondary transfer roller can be secured with high accuracy.

  According to the invention of claim 5, by mounting and positioning the intermediate transfer unit at a predetermined position of the main body frame, the first contact on the intermediate transfer unit side can be brought into contact with the second contact on the main body frame side. Thus, an electrical connection between the power supply on the main body frame side and the primary transfer roller on the intermediate transfer unit side can be achieved.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
The image forming apparatus 1 according to the present invention will be described with reference to FIGS. In these drawings, the front, rear, left, right, top and bottom of the image forming apparatus 1 and its constituent elements (each member, apparatus, etc.) are appropriately indicated by arrows. 1 to 34, FIG. 1 is a perspective view of the entire image forming apparatus 1 as viewed from the upper left side of the front side thereof. FIG. 2 is a perspective view of the entire image forming apparatus 1 as viewed from the rear and obliquely upward on the left side. FIG. 3 is a diagram schematically showing the internal structure of the image forming apparatus 1 as viewed from the left side. 4A and 4B are schematic diagrams for explaining the closed positions A1 and B1 and the open positions A2 and B2 of the front cover 3 and the transport unit 73. FIG. 5 to 34 will be described as appropriate.

  Here, examples of the image forming apparatus 1 include a printer, a copier, a facsimile machine, and a multifunction machine of these. In the following description, a case where the image forming apparatus 1 is a printer will be described as an example. An image forming apparatus 1 shown in FIGS. 1 to 4 is a four-color full-color image forming apparatus 1 adopting an electrophotographic system, an intermediate transfer system, and a tandem system.

  The configuration of the entire image forming apparatus 1 viewed from the outside will be described with reference to FIGS. 1 and 2 as appropriate and FIGS. 3 and 4 as appropriate. The image forming apparatus 1 includes a substantially box-shaped (cuboid) image forming apparatus main body 2 and a front cover 3 supported by the image forming apparatus main body 2 so as to be freely opened and closed.

  The image forming apparatus main body 2 has a front surface covered with a front cover 3 and a left side surface and a right side surface covered with a left exterior panel 4 and a right exterior panel 5 made of synthetic resin. On the rear surface of the image forming apparatus main body 2, a rear side plate 7 constituting a part of a main body frame 6 as a structure is exposed. The upper surface of the image forming apparatus main body 2 is covered with a top cover (cover member) 10 that also serves as the paper discharge tray 8.

  The front cover 3 is provided with an operation panel 12 on the upper end side, and an openable and closable manual feed tray 13 on the front side. A touch panel type liquid crystal display unit and various buttons are arranged on the operation panel 12, and the operator stands on the front side of the image forming apparatus 1 and the entire image forming apparatus 1 is operated by the operation panel 12. Can be operated. The manual feed tray 13 is swingably supported at the lower end 13a side by the front cover 3. The upper end 13b side is pulled out toward the front side (in the direction of the arrow R13) from the stowed storage position C1 shown by a solid line in FIG. By disposing the sheet feeding position C2 in the inclined posture shown by the dotted line, the upper surface can be used as the sheet stacking surface 13c of the manual feeding table. The entire front cover 3 is supported by the image forming apparatus main body 2 so that the lower end 3a is swingable. The closed position A1 shown in FIGS. 1 to 3 and 4A and FIG. 4B are shown. It can move between the open position A2. As shown in FIG. 2, release levers 15 with buttons 14 are provided near the left and right ends on the upper end side and the rear side of the front cover 3. A hook member (not shown) is connected to the release lever 15 via a connecting member (not shown). The hook member is disposed on the front cover 3 side. When the front cover 3 is closed, the hook member is engaged with a locking member (not shown) on the image forming apparatus main body 2 side to lock the front cover 3. When opening the front cover 3, when the button 14 is pulled forward, the hook member is swung through the connecting member and released from the locking member, so that the lock is released. In this state, the front cover 3 can be opened by pulling the upper end side toward the near side (in the direction of arrow R3a in FIG. 4).

  The sheet discharge tray 8 is composed of an inclined surface that is gently inclined so that the rear end side is positioned higher, and a plane that continues to the rear end of the inclined surface. The sheet discharged toward the head is supported from below. As shown in FIGS. 1, 2, and 3, the top cover 10 has, on the rear end side, a swing center 10a that is swingably supported by the image forming apparatus body 2, and the front end side can be opened and closed. It has become. In the closed position D1 indicated by the solid line in FIG. 3, the top cover 10 constitutes the paper discharge tray 8 and is opened in the direction of the arrow R10 shown in FIG. 3 and disposed at the open position D2 indicated by the two-dot chain line. In some cases, the image forming apparatus main body 2 has an opening 6a at the upper portion of the main body frame 6 that is opened up substantially in an upright posture. A developing unit 40A, a drum unit 36A, an intermediate transfer unit 31A, and toner containers 47, 48, 49, and 50 for each color, which will be described later, are attached and detached from above through the opening 6a.

  This is the end of the description of the configuration of the entire image forming apparatus 1 viewed from the outside.

  Next, the internal structure of the image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 includes a sheet storage unit 20, a substrate storage unit 21, an image forming unit 22, a toner supply unit 23, and a top cover 10 as a sheet discharge unit in order from the lower side to the upper side of the image forming apparatus main body 2. Is provided. A sheet conveying unit 24 is provided between the front side of the image forming apparatus main body 2 and the front cover 3.

  A sheet cassette 25 is disposed in the sheet storage unit 20. The sheet feeding cassette 25 stores a plurality of sheets in a stacked state, and biases the leading end side (the right side in the figure) of the stacked sheets upward by a lift plate 26 disposed at the bottom. Yes. As a result, the uppermost sheet in the sheet feeding cassette 25 is fed by a pickup roller 27 of a sheet transport unit 24 described later, and further, the feeding roller 28 and the retard roller 30 prevent double feeding, and only one sheet is downstream. To the side. The paper feed cassette 25 can be inserted / removed (detached) from the front side (front side) of the image forming apparatus 1. A substrate storage unit 21 is disposed above the paper feed cassette 25.

  The substrate storage unit 21 is provided with a substrate and electrical components (not shown) that control the entire image forming apparatus 1. An image forming unit 22 is disposed above the substrate storage unit 21.

  The image forming unit 22 includes an intermediate transfer belt 31 and four (four color) image forming stations aligned along the rotation direction of the intermediate transfer belt 31 (arrow R31 direction), that is, magenta (M), Image forming stations 32, 33, 34, and 35 for forming toner images with cyan (C), yellow (Y), and black (K) toners are provided. Since the four-color image forming stations 32 to 35 have the same configuration, the magenta image forming station 32 will be described below, and the description of the remaining three-color image forming stations 33 to 35 will be omitted as appropriate. .

  The intermediate transfer belt 31 is formed in an endless shape, and is stretched between a driving roller (first roller) 43 and a driven roller (second roller) 44. The drive roller 43 is a so-called secondary transfer counter roller that faces the secondary transfer roller 45 described later and plays the intermediate transfer belt 31 between the drive roller 43 and the secondary transfer roller 45. The intermediate transfer belt 31 is rotated in the direction of the arrow R31 by the rotation of the driving roller 43 in the direction of the arrow. The driving roller 43 and the driven roller 44 are rotatably supported by a synthetic resin transfer frame 39 formed in a substantially rectangular plate shape. The upper surface of the transfer frame 39 is formed in a waveform following the shape of the bottom of toner containers 47, 48, 49, and 50 described later. In the present embodiment, a driving roller 43, a driven roller 44, an intermediate transfer belt 31, four primary transfer rollers 41 (to be described later), a belt cleaner 46, and the like are integrally incorporated into the transfer frame 39 as a whole. The intermediate transfer unit 31A is configured. The intermediate transfer unit 31A can be easily attached to and detached from the image forming apparatus main body 2 as described later.

  The magenta image forming station 32 includes a photosensitive drum 36, and a charging device 37, an exposure device 38, a developing device 40, and a primary device that are arranged around the photosensitive drum 36 in the order of rotation (arrow direction). A transfer roller 41, a drum cleaner 42, and the like are included.

  The photosensitive drum 36 is driven to rotate in the direction of the arrow at a predetermined process speed. In this embodiment, an a-Si (amorphous silicon) photosensitive drum is used as the photosensitive drum 36.

  The charging device 37 uniformly (uniformly) charges the surface of the photosensitive drum 36 to a predetermined polarity and potential.

  The exposure device 38 is constituted by, for example, a laser scanner. The exposure apparatus 38 includes a laser oscillator (not shown), a polygon mirror 38a, lenses 38b and 38c, reflection mirrors 38d, 38e, and 38f, and these are integrally incorporated to constitute an exposure unit 38A. . The exposure device 38 reflects a laser beam L emitted from a laser oscillator (not shown) based on image information sent from a personal computer (not shown) or the like by a polygon mirror 38a that rotates at high speed, and lenses 38b, Then, the light is guided to the surface of the photosensitive drum 36 after uniform charging via a mirror 38c, reflecting mirrors 38d, 38e, 38f and the like. The surface of the photosensitive drum 36 is exposed to the laser beam L to remove the charge on the exposed portion, thereby forming an electrostatic latent image.

  The developing device 40 develops the electrostatic latent image. The developing device 40 includes a developing container 40a in which a developer is accommodated, a developing sleeve 40b, developer agitating members 40c and 40d, and the like, which constitute a developing unit 40A. The developer carried on the surface of the developing sleeve 40 b is selectively attached to the electrostatic latent image on the surface of the photosensitive drum 36 by applying a developing bias between the developing sleeve 40 b and the photosensitive drum 36. This is developed as a toner image. In the present embodiment, a two-component developer mainly composed of toner and carrier is used as the developer.

  The primary transfer roller 41 transfers the toner image formed on the surface of the photosensitive drum 36 to the intermediate transfer belt 31. The primary transfer roller 41 presses the back side of the intermediate transfer belt 31 to bring the surface of the intermediate transfer belt 31 into contact with the surface of the photosensitive drum 36. As a result, a primary transfer nip T <b> 1 is formed between the surface of the intermediate transfer belt 31 and the surface of the photosensitive drum 36. The toner image formed on the surface of the photosensitive drum 36 is conveyed to the primary transfer nip T1 as the photosensitive drum 36 rotates in the arrow direction. At this time, by applying a primary transfer bias to the primary transfer roller 31, the magenta toner image on the surface of the photosensitive drum 36 is primarily transferred onto the surface of the intermediate transfer belt 31.

  The drum cleaner 42 removes toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 36 without being transferred to the intermediate transfer belt 31 in the above-described primary transfer. In the present embodiment, the photosensitive drum 36, the charging device 37, the drum cleaner 42, and the like are integrally configured to constitute the drum unit 36A.

  As described above, in the magenta image forming station 32, the magenta toner image formed on the surface of the photosensitive drum 36 is primarily transferred onto the surface of the intermediate transfer belt 31. Similarly, in the remaining three color (cyan, yellow and black) image forming stations 33, 34 and 35, toner images of cyan, yellow and black are formed on the surface of each photosensitive drum 36, respectively. The toner images are sequentially primary-transferred onto the intermediate transfer belt 31 by the primary transfer roller 41 and superimposed. As will be described later, these four color toner images are secondarily transferred onto the sheet all at once by applying a secondary transfer bias to the secondary transfer roller 45 at the secondary transfer nip T2. Toner remaining on the surface of the intermediate transfer belt 31 after the secondary transfer of the toner image (secondary transfer residual toner) is removed by a belt cleaner 46 disposed in the vicinity of the driven roller 44. A toner replenishing unit 23 is provided above the image forming unit 22.

  The toner replenishing unit 23 is provided with four toner containers (toner containers) each containing toner of each color, that is, magenta, cyan, yellow, and black toner containers 47, 48, 49, and 50. . Of these, the black toner container 50 is generally formed in a large size so as to have a larger capacity than the other color toner containers 47 to 49 because the black toner consumes a larger amount of toner than the other color toners. Has been. The developing devices 40 of the color image forming stations 32 to 35 described above are provided with a remaining amount sensor (not shown) for detecting the remaining amount of the developer. When it is detected that the amount of the developer is less than a predetermined value, toner is supplied to the developing device 40 of each color from the toner containers 47 to 50 of each color. Above the toner replenishing portion 23, the above-described top cover 10 that can be opened and closed with respect to the swing center 10a on the rear end side is provided.

  In the present embodiment, the sheet conveyance unit 24 is provided between the front side of the image forming apparatus main body 2 and the front cover 3, and a sheet conveyance path 52 that guides a sheet from below to above, and the sheet conveyance unit. It has a sheet re-conveying path 53 that is disposed on the front side of the path 52 and guides the sheet from the upper side to the lower side, and further has a manual feeding unit 54.

  The sheet conveyance path 52 rises upward from the vicinity of the above-described feeding roller 28, extends upward while gently curving backward, and extends upward in the vicinity of the secondary transfer nip T2 by changing the bending direction to the front. The sheet extends obliquely upward toward the rear and reaches the sheet discharge port 55. The sheet conveyance path 52 includes a rear guide 52a and a front guide 52b facing each other, and a part of the front guide 52b is formed in a conveyance unit 73 described later. In the sheet conveyance path 52, the pickup roller 27, the feeding roller 28, the retard roller 30, the conveyance roller pair 56, the registration roller pair 57, and the intermediate transfer belt 31 are sandwiched between the driving roller 43 in order from the bottom. A transfer roller 45, a fixing device (fixing unit) 58, a conveyance roller pair 60, a switching flapper 61, a paper discharge roller pair 62, and the like are provided. The above-described fixing device 58 includes a fixing roller (fixing member) 63 including a heating member (not shown), and a pressure roller (pressure member) 64 that forms a fixing nip N in pressure contact therewith. .

  The sheet fed by the pickup roller 27, the feeding roller 28, and the retard roller 30 from the sheet feeding cassette 25 is conveyed by the conveying roller pair 56 and the registration roller pair 57, and in the secondary transfer nip T2. The four color toner images on the surface of the intermediate transfer belt 31 are secondarily transferred at once, and heated and pressurized when passing through the fixing nip N to fix the four color toner images on the surface. The sheet on which the toner image has been fixed is guided to the lower surface of the switching flapper 61 by the conveying roller pair 60 and conveyed to the sheet discharging roller pair 62, and the sheet discharging roller pair 62 moves backward from the sheet discharge port 11 facing the back side. Then, the paper is discharged and stacked on the paper discharge tray 8. In the figure, the sensor flag 65 of the paper discharge sensor disposed immediately downstream of the paper discharge roller pair 62 is operating with the sheet P being discharged.

  The sheet re-conveying path 53 extends obliquely from the upper side to the front side of the above-described sheet discharge port 11, is gently curved and extends to the rear side with a steep slope, and protrudes downward at the lower end portion. Then, the sheet merges with the sheet conveyance path 52 described above. The sheet re-conveying path 53 includes a rear guide 53a and a front guide 53b that face each other. A part of the rear guide 53a is formed in a transport unit 73 described later. Further, most of the front guide 53b is incorporated inside (rear end side) of the front cover 3. In the sheet re-conveying path 53, the reverse roller pair 66, the switching flapper 61, the first, second, third and fourth re-conveying roller pairs 67, 68, 70 and 71 are arranged.

  When images are formed on both sides of the sheet, the switching flapper 61 is switched to the position indicated by the two-dot chain line, and the sheet on which the toner image is fixed is conveyed to the conveying roller pair 60 and the switching flapper 61 It is conveyed along the upper surface and further conveyed rearward by the reverse roller pair 66. Then, the rear end of the sheet passes through the conveying roller pair 60, and the reverse roller pair 66 is reversely rotated before passing through the reverse roller pair 66, and the first to fourth re-conveying roller pairs 67, 68, 70, 71 The sheet is conveyed downward and conveyed to the sheet conveyance path 52. Then, the toner image is transferred and fixed on the rear surface of the sheet in the same manner as on the front surface, and is discharged backward from the sheet discharge port 11 and stacked on the discharge tray 8. A manual feed roller 72 is disposed immediately in front of the conveyance roller pair 56 in the sheet conveyance unit 24. The manual feed roller 72 feeds the sheet set on the sheet stacking surface 13c of the manual feed tray 13 disposed at the paper feed position C2 in FIG. 3 toward the conveyance roller pair 56 side.

  As shown in FIG. 3, the above-described sheet conveyance unit 24 is provided with a conveyance unit 73 that can be freely opened and closed. The transport unit 73 is disposed between the sheet transport path 52 and the sheet re-transport path 53, and a part of the front guide 52 b in the sheet transport path 52 and a part of the rear guide 53 a in the sheet re-transport path 53. And the first roller 57a of the registration roller pair 57, the secondary transfer roller 45, and the first and second rollers 70a and 71a of the third and fourth re-conveying roller pairs 70 and 71, respectively. Yes. As shown in FIGS. 4A and 4B, the transport unit 73 has a swing center on the lower end 73a side, and is supported by the image forming apparatus body 2 so as to be swingable (openable and closable). Yes.

  The transport unit 73 is opened and closed in conjunction with the opening and closing operation of the front cover 3. As shown in FIGS. 4A and 4B, the front cover 3 has a swing center 76 at the lower end, and the swing center 76 is swingably supported by the image forming apparatus main body 2. Yes. The image forming apparatus main body 2 includes a left side plate (side plate) 74 and a right side plate 75 (side plate) of the main body frame 6 that extend to the front side and a part of the left side surface and the right side surface of the front cover 3 and a conveyance unit. The left side surface and the right side surface of 73 are covered. A shaft 77 protrudes inwardly from the lower ends of the front end side of the left side plate 74 and the right side plate 75, and the swing center 76 of the front cover 3 is supported by the shaft 77 so as to be swingable. ing. Thereby, the front cover 3 can take the closed position A1 shown to Fig.4 (a), and the open position A2 shown to FIG.4 (b). The above-described transport unit 73 also has a swing center (not shown) on the lower end 73a side, and has a shaft (not shown) protruding inward from the left side plate 74 and the right side plate 75 on the image forming apparatus main body 2 side. It is supported so as to be able to swing. Thereby, the conveyance unit 73 can take the closed position B1 shown to Fig.4 (a), and the open position B2 shown to FIG.4 (b). The transport unit 73 is opened and closed in conjunction with the opening and closing operation of the front cover 3 without the operator intentionally opening and closing. Further, the front cover 3 and the transport unit 73 are held at the open positions A2 and B2 shown in FIG. 4B by stoppers (not shown) such as chains and links when opened.

  In the image forming apparatus 1 described above, at the time of image formation, the hook member on the front cover 3 side is engaged with the locking member on the image forming apparatus main body 2 side, whereby the front cover 3 and the transport unit 73 are respectively shown in FIG. It arrange | positions in closed position A1, B1 shown to a). Thus, the sheet conveyance path 52 and the sheet re-conveyance path 53 are configured, and a nip is formed between each pair of rollers, so that the sheet can be conveyed.

  Here, when a jam or the like occurs during image formation, the button on the back side (see FIG. 2) at the top of the front cover 3 is operated to move the front cover 3 in the direction of arrow R3a in FIG. When opened, the transport unit 73 is also opened in conjunction with this. Thereby, as shown in FIG.4 (b), the front cover 3 and the conveyance unit 73 are each arrange | positioned in open position A2, B2. In this state, since the sheet conveyance path 52 and the sheet re-conveyance path 53 are largely opened and exposed, it is possible to easily find and remove jammed paper. After the jam processing, when the front cover 3 is moved in the direction of arrow R3b in FIG. 4B, the transport unit 73 is also moved in the same direction in conjunction with this, and the front cover 3 and the transport unit 73 are in the closed position. Arranged at A1 and B1. Thereby, it is possible to resume image formation.

  This completes the description of the internal structure of the image forming apparatus 1.

  In the image forming apparatus described above, the developing unit 40A, the drum unit 36A, the intermediate transfer unit 31A, and the toner containers 47 to 50 shown in FIG. 3 are disposed upward via the opening 6a on the upper part of the main body frame 6 of the image forming apparatus main body 2. It can be attached to and removed from. Hereinafter, this point will be described in detail.

  9 shows a state where the front frame 3, the left exterior panel 4, the right exterior panel 5, the top cover 10 and the like are removed from the image forming apparatus main body 2 shown in FIGS. It is the perspective view seen from the left diagonal upper direction. In the drawing, a state in which the developing unit 40A for magenta on the rear end side is being mounted from above is shown. As shown in the figure, the main body frame 6 includes four wall-shaped members disposed on the front, rear, left, and right sides, that is, the rear guide 52a, the rear plate 7, the left plate 74, and the right plate 75, respectively. A rectangular parallelepiped storage empty section 80 is formed on the inner side surrounded by these. An exposure unit 38A shown in FIG. 3 is disposed in a portion corresponding to the bottom of the storage space 80. On the other hand, a rectangular opening 6 a is formed at the upper end of the storage space 80, that is, at the top of the main body frame 6.

  FIG. 5 is a perspective view of the left side plate 74 viewed from the inside, and FIG. 6 is a view of the left side plate 74 viewed straight from the inside. 7 is a perspective view of the right side plate 75 viewed from the inside, and FIG. 8 is a view of the right side plate 75 viewed straight from the inside. In these drawings, the lower portion including the portion corresponding to the substrate storage portion 21 shown in FIG. 3 is not shown. As shown in these drawings, the left side plate 74 and the right side plate 75 are divided into a lower portion 74a, 75a, an intermediate portion 74b, 75b, and an upper portion 74c, 75c in order from the lower side, and the lower portion 74a, 75a corresponds to the exposure unit 38a. The intermediate portions 74b and 75b are development / drum corresponding portions corresponding to the developing unit 40A and the drum unit 36a, and the upper portions 74c and 75c are intermediate transfer unit corresponding portions and containers corresponding to the intermediate transfer unit 31A and the toner containers 47 to 50. It is a corresponding part. Further, step portions 74d and 75d are formed between the lower portions 74a and 75a and the intermediate portions 74b and 75b, and step portions 74e and 75e are formed between the intermediate portions 74b and 75b and the upper portions 74c and 75c. Yes. By these step portions, the intermediate portions 74b and 75b are located outside the lower portions 74a and 75a, and the upper portions 74c and 75c are located outside the intermediate portions 74b and 75b. Yes. That is, the width between the inner surface of the upper portion 74c and the inner surface of the upper portion 75c is set wider than the width between the inner surface of the intermediate portion 74b and the inner surface of the intermediate portion 75, and the developing unit 40A and the drum unit 36A. These can be easily passed between the upper parts 74c and 75c when mounting.

  Here, the lower portions 74a and 75a and the intermediate portions 74b and 75b are formed of a sheet metal, and the sheet metal requires a relatively simple shape such as a through-hole or a groove penetrating in the front and back direction and high accuracy. Processing to be performed is given. On the other hand, the upper parts 74c and 75c are made of a synthetic resin, and are formed in a complicated shape such as a concavo-convex shape and a guide groove, which is relatively loose.

  Of the above-described lower portions 74a and 75a, as shown in FIG. 7, the lower portion 75a of the right side plate 75 is provided with another step portion 75f at a position lower than the above-described step portion 75d. In addition, four rectangular through holes a1 in which connectors for electrically connecting the developing unit 40A and the image forming apparatus main body 2 are disposed, and similarly the drum unit 36A and the image forming apparatus main body 2 are electrically connected. There are four rectangular through holes a2 in which connectors for connection are connected.

  As shown in FIGS. 5 and 6, four long guide grooves (development guides) b1 extending downward from the stepped portion 74e are formed in the intermediate portion 74b of the left side plate 74, and the respective guides are provided. Similarly, a short guide groove (drum guide) b2 extending downward from the step 74e is formed on the front side of the groove b1. In addition, a large window portion b3 extending from the step portion 74e and extending obliquely downward to the front side is formed on the front side of each guide groove b2. The guide groove b1 guides the left end side of the developing unit 40A, the guide groove b2 guides the left end side of the drum unit 36A, and the window part b3 exposes the left end side of the drum unit 36A. Is for.

  Four guide grooves c1, c2, and c3 are formed at positions corresponding to the guide grooves b1 and b2 and the window part b3, respectively, in the lower half of the upper portion 74c of the left side plate 74. Each guide groove c1 is formed in the vertical direction, and the lower end thereof is connected to the upper end of the above-described guide groove b1. Of the four guide grooves c2, the one located on the foremost side has a straight portion that continues to the above-mentioned guide groove b2 and a gently inclined portion that extends continuously obliquely rearward from the upper end of the straight portion. is doing. The second and third guide grooves c2 from the front are straightly connected to the above-described guide groove b2 in the vertical direction. The fourth guide groove c2 from the front has a linear portion that continues to the above-described guide groove b2 and an inclined portion that extends continuously and obliquely forward to the upper end of the linear portion. Of the four guide grooves c3, the one located on the foremost side has a linear portion that continues to the window portion b3 described above and a gently inclined portion that extends continuously obliquely rearward from the upper end of the linear portion. is doing. The guide grooves c3 located at the second and third positions from the front are straightly connected to the above-described window portion b3 in the vertical direction. The fourth guide groove c3 from the front has an inclined portion that extends obliquely forward to the above-described guide groove b2. In the upper half of the upper portion 74c of the left side plate 74, four bifurcated guide grooves (container guides) c4 are formed to guide two locations on the left end side of the toner containers 47 to 50 in the vertical direction.

  The guide grooves b1, b2, and the window part b3 formed in the intermediate part 74b of the left side plate 74 are all located inside the guide grooves c1, c2, c3 formed in the upper part 74c. These are all formed so as to go from the top to the bottom including the inclined portion.

  As shown in FIGS. 7 and 8, the right side plate 75 is formed with guide grooves b5, b6 and through holes b7 at positions corresponding to the guide grooves b1, b2 and the window portion b3 of the left side plate 74, respectively. A guide groove c6 is formed at a position corresponding to the guide groove c2. That is, four long guide grooves (development guides) b5 extending downward from the step portion 75e are formed in the middle portion 75b of the right side plate 75, and the front sides of the respective guide grooves 5 are similarly provided. A short guide groove (drum guide) b6 extending downward from the stepped portion 75e is formed. A circular through hole b7 is formed in front of each guide groove b6. The guide groove b5 described above guides the right end side of the developing unit 40A, the guide groove b6 guides the right end side of the drum unit 36A, and the through hole b7 exposes the right end side of the drum unit 36A. Is for.

  Guide grooves c6 are formed at positions corresponding to the above-described respective guide grooves b6 in substantially the lower half of the upper portion 75c of the right side plate 75. Of the four guide grooves c6, the one located on the foremost side is a straight line that continues to the above-described guide groove b6 and the upper end of the straight line, and extends obliquely rearward with a gentle slope, with a slope in the middle. It has a tightly inclined portion and a straight portion extending upward from the upper end of the inclined portion. The guide groove c6 located second from the front is straightly connected to the above-described guide groove b6 in the vertical direction. The third guide groove c6 from the front has a long straight portion that continues to the guide groove b6, an inclined portion that extends obliquely forward from the upper end of the straight portion, and a straight portion that extends straight up from the inclined portion. . The fourth guide groove c6 from the front has a short straight line portion that continues to the guide groove b6, an inclined portion that extends obliquely forward from the upper end of the straight portion, and a straight portion that extends straight up from the inclined portion. . A pedestal c7 is provided in the vicinity of each guide groove c6. A motor (not shown) for driving a conveying screw (not shown) of the toner containers 47 to 50 (see FIG. 3) is attached to the pedestal c7 on the outer surface. Further, a guide groove (container guide) c8 for guiding the right end side of the toner containers 47, 48, 49, 50 is provided immediately behind each base c7.

  The guide grooves b5, b6, and the through hole b7 formed in the intermediate portion 75b of the right side plate 75 are all located on the inner side of the guide groove c6 formed in the upper portion 75c. It is formed so as to go downward from above including the inclined portion.

  The operation of mounting the magenta developing unit 40A on the rear end side at a predetermined position of the image forming apparatus main body 2 will be described with reference to FIGS. As shown in FIG. 9, the developing unit 40 </ b> A is mounted in the horizontal posture with the longitudinal direction being in the left-right direction from below the opening 6 a of the main body frame 6 through the opening 6 a. As shown in FIG. 10, the distance between the upper portion 74c of the left side plate 74 and the upper portion 75c of the right side plate 75 of the main body frame 6 is set to be larger than the horizontal dimension of the developing unit 40A. When passing between the upper parts 74c and 75c, it can pass without interfering anywhere. When the developing unit 40A is further lowered, the left end of the developing unit 40A is guided by the guide groove b1 of the lower portion 74a of the left side plate 74, while the right end is lowered while being guided by the guide groove b5 of the lower portion 75a of the right side plate 75. To do. The developing unit 40A is positioned in the vertical direction by contacting the lower ends of the guide grooves b1 and b5, and a positioning convex portion (not shown) disposed at the bottom is positioned on the lower portion 75a of the right side plate 75. A connector (not shown) in which an electrode (not shown) protruding from the bottom is arranged in the through hole a1 while being positioned in a predetermined position by being engaged with the recess a3 and flowing in the front-rear and left-right directions. ) To be conducted. The developing units 40A for other colors can be positioned and arranged at predetermined positions in the same manner as the developing unit 40A for magenta. When removing the developing unit 40A from the predetermined position, contrary to the above, the developing unit 40A positioned and arranged at the predetermined position of the image forming apparatus main body 2 is lifted upward as it is, and the guide grooves b1, b5 are removed. It is only necessary to lift it up, further lift it up, pass the upper parts 74c and 75c, and take it out through the opening 6a.

  Next, the operation of mounting the magenta drum unit 36A on the rear end side at a predetermined position of the image forming apparatus main body 2 will be described with reference to FIGS. In the case of the drum unit 36A, the developing unit 40A is already mounted at a predetermined position, and is mounted on the front side of the developing unit 40A. Therefore, unlike the case of the developing unit 40A described above, the guide is started from the guide grooves c2 and c6 of the left side plate 74 and the right side plate 75 so as not to contact the developing unit 40A unnecessarily. That is, after the drum unit 36A that has passed through the opening 6a of the main body frame 6 from above, the left end side and the right end side thereof have passed without being guided through the upper half portions 74c and 75c of the left side plate 74 and the right side plate 75. Then, it descends while being guided by the guide grooves c2 and c6 formed in the lower half part, and then descends straightly guided by the guide grooves b2 and b6 formed in the intermediate parts 74b and 75b. The drum unit 36A is positioned in the vertical direction by contacting the lower ends of the guide grooves b2 and b6, and the positioning projection (not shown) arranged at the bottom is a positioning recess in the lower portion 75a of the right plate 75. It is engaged with a4 and positioned in the front-rear and left-right directions, and is arranged at a predetermined position. At this time, the drum unit 36A is electrically connected by inserting an electrode (not shown) protruding from the bottom into a connector (not shown) disposed in the through hole a2. The other color drum units 36A can be positioned and arranged at predetermined positions in the same manner as the magenta drum unit 36A. When removing the drum unit 36A from the predetermined position, contrary to the above, the drum unit 36A positioned and arranged at the predetermined position of the image forming apparatus main body 2 is lifted upward and removed from the guide grooves b2 and b6. Further, it may be lifted up and passed through the upper parts 74c and 75c and taken out upward through the opening 6a.

  Next, the intermediate transfer unit 31 </ b> A is mounted and positioned at a predetermined position of the image forming apparatus main body 2. 16, FIG. 17, FIG. 18 and FIG. 19 show the overall operation (posture) of the intermediate transfer unit 31A when mounted. 20, 21, 22, and 23, (a) shows a guide state on the left end side of the front end portion of the intermediate transfer unit 31 </ b> A when attached, and FIGS. 20, 21, 22, and 23. Each (b) of FIG. 23 shows the guide state on the right end side of the tip portion.

  As shown in FIG. 16, the main body frame 6 has the rear guide 52a, the rear side plate 7, the left side plate 74, and the right side plate 75 on the front, rear, left and right sides as described above. A paper discharge frame 81 that is long in the left-right direction is provided above the side guide 52a. The paper discharge frame 81 is provided with a pair of paper discharge rollers 62 shown in FIG. The paper discharge frame 81 includes a left support portion 81a, a right support portion 81b, and a connecting portion 81c disposed between the left support portion 81a and the right support portion 81b.

  As shown in FIG. 20A, a left inclined guide (inclined guide) 82a is formed at the lower end of the left support portion 81a. The left inclined guide 82a is formed by a pair of upper and lower inclined plates 83a and 84a whose front side is inclined downward. Of these, the lower inclined plate 84a is formed with a shorter tip than the upper inclined plate 83a, and the first guide boss (slide boss) 87a of the intermediate transfer unit 31A moves downward, as will be described later. This is a notch portion 85a that permits this. The left inclined guide 82a guides the movement of the first guide boss 87a projecting inward (right) from the projecting plate 86a projecting upward on the front end side and the left end side of the intermediate transfer unit 31A. It is. A left swing guide (swing guide) 90a is formed slightly below the left inclined guide 82a. The left swing guide 90a is formed on the front end side of the left side plate 74 and a convex portion 74g, which is a portion where an intermediate portion 74b made of sheet metal projects from an upper portion 74c made of resin. . The left swing guide 90a has a substantially semicircular arc portion 91a on the front end side, and has an opening 92a on the rear end side that has a lower end edge that is substantially horizontal and an upper end edge that is inclined to the front. The left swing guide 90a guides a second guide boss (swing boss) 93a that protrudes from the left end side to the outside (left side) of the intermediate transfer unit 31A. The second guide boss 93a is disposed coaxially with the drive roller 43 described above. The left swing guide 90a is slightly outside the left inclined guide 82a (corresponding to the fact that the second guide boss 93a on the intermediate transfer unit 31A side is disposed outside (left side) than the first guide boss 87a. On the left).

  The left inclined guide 82a, the left swinging guide 90a, and the first guide boss 87a and the second guide boss 90a corresponding to the left inclined guide 82a and the left swing guide 90a, which are arranged in the vicinity of the lower end of the left support portion 81a described above, are supported by the right support. It is provided near the lower end of the part 81b. That is, as shown in FIG. 20B, a right inclined guide (inclined guide) 82b is formed at the lower end of the right support portion 81b. The right inclined guide 82b is formed by a pair of upper and lower inclined plates 83b and 84b whose front side is inclined downward. Of these, the lower inclined plate 84b is formed to have a shorter tip than the upper inclined plate 83b, and the first guide boss (slide boss) 87b of the intermediate transfer unit 31A moves downward as will be described later. This is a notch 85b that allows The right inclined guide 82b guides the movement of the first guide boss 87b that protrudes inward (leftward) from a protrusion 86b that protrudes upward on the leading end side and the right end side of the intermediate transfer unit 31A. Is. A right swing guide (swing guide) 90b is formed slightly below the front side of the right inclined guide 82b. The right swing guide 90b is formed on the front end side of the right side plate 75 and a convex portion 75g, which is a portion in which an intermediate portion 75b made of sheet metal projects from an upper portion 75c made of resin. . The convex portion 75g has a front plate 75h positioned on the inner side and a rear plate 75i positioned slightly outside thereof by a stepped portion, and the right swing guide 90b is formed so as to straddle the stepped portion. ing. The right swing guide 90b has a substantially semicircular arc portion 91b on the front end side, and the rear end side is disposed outside the arc portion 91b. Of the right swing guide 90b, the portion formed on the front plate 75h is inclined such that the lower end edge is substantially horizontal and the upper end edge is higher at the rear. The right swing guide 90b guides a second guide boss (swing boss) 93b that protrudes from the right end side to the outside (right side) of the intermediate transfer unit 31A. The second guide boss 93b is arranged coaxially with the drive roller 43 and the left second boss 93a. The right swing guide 90b is slightly outside the right inclined guide 82b (corresponding to the second guide boss 93b on the intermediate transfer unit 31A side being disposed outside (right side) than the first guide boss 87b. On the right).

  As described above, the main body frame 6 on the image forming apparatus main body 2 side is provided with the left inclined guide 82a and the left swing guide 90a on the left side on the front end side, and on the right side with the right inclined guide 82b at a position corresponding thereto. A right swing guide 90b is disposed. On the other hand, on the intermediate transfer unit 31A side, a first guide boss 87a and a second guide boss 90a are arranged on the left side on the front end side, and a first guide boss 87b and a second guide boss 90b are arranged on the right side. As a result, the intermediate transfer unit 31A is guided to slide in an inclined state as will be described below, and then guided to swing.

  In order to attach the intermediate transfer unit 31A to the image forming apparatus main body 2, as shown in FIG. 16, the front end side is held low and the rear end side is held in a highly inclined posture, as shown in FIGS. As shown in (b), the first guide bosses 87a and 87b of the intermediate transfer unit 31A are placed on the rear end sides of the inclined plates 84a and 84b of the left inclined guide 82a and the right inclined guide 82b, respectively. As shown in FIGS. 21A and 21B, while maintaining the inclined posture, the intermediate transfer unit 31A is pushed forward to move the first guide bosses 87a and 87b along the left inclined guide 82a and the right inclined guide 82b. Let When the intermediate transfer unit 31A is continuously pressed, the second guide bosses 90a and 90b enter the left swing guide 90a and the right swing guide 90b, and as shown in FIGS. 18, 22 (a) and 22 (b), Immediately before the second guide bosses 90a and 90b come into contact with the arc portions 91a and 92b, the first guide bosses 87a and 87b are detached from the inclined plates 84a and 84b and reach the notches 85a and 85b. As a result, the rear end side of the intermediate transfer unit 31A can be swung downward. Further, the intermediate transfer unit 31A is pushed to bring the second guide bosses 90a and 90b into contact with the arc portions 91a and 91b, and the rear end side of the intermediate transfer unit 31A is swung downward with the second guide bosses 90a and 90b as a reference. Then, as shown in FIGS. 19, 23 (a), (b), the rear end side of the intermediate transfer unit 31 comes into contact with a part of the main body frame 6 so that the whole is substantially horizontal.

  As described above, the configuration for mounting and positioning the intermediate transfer unit 31A on the main body frame 6 can be simplified as compared with the conventional case. That is, the first guide bosses 87a and 87b and the second guide bosses 93a and 93b are provided on the intermediate transfer unit 31A side, while the left inclined guide 82a, the right inclined guide 82b, and the left swing guide 90a are provided on the main body frame 6 side. It is possible to adopt a simple configuration such as providing a right swing guide 90b. Further, since the left swing guide 90a, the right swing guide 90b, and the second guide bosses 93a and 93b serve both as a guide for mounting the intermediate transfer unit 31A and a guide for positioning, Unlike the technology, there is no need to provide a separate positioning member, and the configuration can be simplified accordingly. Further, as a mounting / positioning operation by the user or the like, the user holds the entire intermediate transfer unit 31A, and first attaches the first guide bosses 87a and 87b of the intermediate transfer unit 31A to the left inclined guide 82a and right of the main body frame 6. By moving along the inclined guide 82b, the second guide bosses 93a, 93b of the intermediate transfer unit 31A can be engaged with the left swing guide 90a and the right swing guide 90b of the main body frame 6, and subsequently. By swinging the entire intermediate transfer unit 31A with the second guide bosses 93a and 93b in the combined state as a reference, the positioning operation can be completed simultaneously with the completion of the mounting operation. That is, unlike the conventional case where the positioning operation is required after the mounting operation, the mounting operation and the positioning operation can be performed as a series of operations without being distinguished.

  As described above, the intermediate transfer unit 31A can be easily mounted and positioned at a predetermined position with high accuracy with respect to the image forming apparatus main body 2. In this state, the intermediate transfer unit 31A sandwiches the intermediate transfer belt 31 between the photosensitive drum 36 and the primary transfer roller 41 with an appropriate clamping pressure. If the rear end side of the transfer frame 39 of the intermediate transfer unit 31A is screwed to a part of the main body frame 6, the intermediate transfer unit 31A after positioning will not move unnecessarily.

  Next, with reference to FIG. 24, FIG. 25, and FIG. 26, an operation of mounting the magenta toner container 47 on the rear end side at a predetermined position of the image forming apparatus main body 2 will be described. The toner container 47 is lowered from the opening 6a toward the storage space 80 so that the longitudinal direction thereof is directed to the left and right. The left end side of the toner container 47 is guided by the guide groove c4 of the left side plate 74, and the right end side thereof is guided by the guide groove c8 of the right side plate 75, and is positioned and arranged at a predetermined position. Similarly, cyan, yellow, and black toner containers 48, 49, and 50 are attached to predetermined positions of the image forming apparatus main body 2.

  According to the present embodiment, as described above, the developing unit 40A, the drum unit 36A, the intermediate transfer unit 31A, and the toner containers 47 to 50 are opened in this order, the top cover 10 is opened, and the opening 6a at the upper end of the main body frame 6 is moved upward. The image forming apparatus main body 2 can be positioned and mounted from above through the opening 6a, and can be taken out in reverse. Further, since the sheet conveying unit 24 is not configured in the storage space 80 in which these are mounted, for example, it is not necessary to take them out to remove jammed paper. The removal of the jammed paper can be performed from the front side of the image forming apparatus 1 by opening the front cover 3 as described above. That is, in the present embodiment, the portion for forming an image on the sheet and the portion for transporting the sheet are clearly separated, and each can be processed individually.

  The above-described intermediate transfer unit 31A is provided with four primary transfer rollers 41. The primary transfer rollers 41 receive toner images of respective colors formed on the respective photosensitive drums 36 on the intermediate transfer belt 31. In primary transfer, it is necessary to apply a high-pressure primary transfer bias. Therefore, in the present embodiment, when the intermediate transfer unit 31A is positioned and arranged at a predetermined position on the image forming apparatus main body 2, a high voltage power source (not shown) on the image forming apparatus main body 2 side and a primary on the intermediate transfer unit 31A side are arranged. The transfer roller 41 is electrically connected. This point will be described below.

  As shown in FIG. 27, in the right side plate 75 of the main body frame 6, a part of the contact spring (second contact) 94 protrudes inward in the shape of a triangle in the vicinity of the four bases c7. Actually, when the substrate holding member 110 is disposed at the retracted position shown in FIG. 27, the contact spring 94 is also retracted in conjunction with this, but in FIG. The state which protruded inside is shown in figure. As shown in FIG. 28, when the substrate holding member 110 is disposed at the operating position shown in FIG. 28, the contact spring 94 protrudes as shown in FIG. The height positions of these contact springs 94 correspond to the intermediate transfer unit 31A that is mounted at a predetermined position.

  At the positions corresponding to the four contact springs 94 on the main body frame 6 side on the intermediate transfer unit 31A side, torsion coil springs 95 to be described later are disposed. The torsion coil spring 95 will be described with reference to FIGS. 29 to 34. 29 is a perspective view of the transfer frame 39 of the intermediate transfer unit 31A as viewed obliquely from below. FIG. 30 is a perspective view showing the primary transfer roller 41 disposed on the lower surface of the transfer frame 39. FIG. 31 is a perspective view showing the vicinity of the bearing guide 101 with the primary transfer roller 39 removed. 32 is a perspective view showing a state in which the bearing 102 is removed from the state of FIG. FIG. 33 is a perspective view of the same state as FIG. 32 as seen from a different angle. FIG. 34 is a perspective view showing the torsion coil spring 95 with the pressing spring 103 further removed from the state of FIG.

  As shown in FIG. 29, on the back side of the transfer frame 39, wall portions 96 and 97 that are long in the front-rear direction are formed on the left end side and the right end side. Four bearing guides 100 are formed on the left wall 96 at different positions in the front-rear direction, and bearing guides 101 are formed on the right wall 97 at positions corresponding to the respective bearing guides 100. Has been. As shown in FIG. 30, a primary transfer roller 41 is disposed on the back surface of the transfer frame 39, and a metal shaft 41a is penetrated in the longitudinal direction at the center thereof. The left and right ends of the shaft 41a are rotatably supported by similar bearings 102 disposed on the bearing guides 100 and 101, respectively. As shown in FIG. 31, the bearing guide 101 is provided with a bearing 102, a pressing spring 103, a pedestal 104, a coil spring 95, and the like. A T-groove 101a for guiding the vertical movement of the bearing 102 is formed inside the bearing guide 101, and a pedestal 104 is disposed at the upper end of the T-groove 101a. In the center of the pedestal 104, a through hole 104a is penetrated in the vertical direction, and a rod portion 102b of the bearing 102 described later is penetrated through the through hole 104a. On the back surface of the pedestal 104, a pair of convex portions 104b are formed that sandwich and position a base end portion 95b of a torsion coil spring 95 described later.

  As shown in FIG. 31, the bearing 102 is inserted into the bearing portion 102a that rotatably supports the shaft 41a of the primary transfer roller 41 and the through hole 104a of the pedestal 104 extending upward from the upper surface of the bearing portion 102a. It has a rod portion 102b and a locking portion 102c that prevents the bearing 102 from falling off the bearing guide 101 by engaging with a part 101b of the bearing guide 101. A compression spring 103 is interposed between the pedestal 104 and the bearing portion 102 a, and the above-described rod portion 102 b passes through the inside of the compression spring 103. As described above, the primary transfer roller 41 rotatably supported by the bearing 102 is urged by the compression spring 103 to press the back surface of the intermediate transfer belt 31, and the surface of the intermediate transfer belt 31 is applied to the photosensitive drum 36. It is in contact. The bearing 102 formed of the above-described bearing portion 102a, rod portion 102b, and engaging portion 102c, and the compression spring 103 are all formed of a conductive member. On the other hand, the bearing guide 101 and the pedestal 104 are formed of insulating members.

  The torsion coil spring 95 is made of spring steel and is disposed on the right bearing guide 101. The coil spring 95 includes a cylindrical spring main body 95a, a base end portion 95b, and a front end portion 95c (see FIG. 33). The spring main body 95a has a through-hole (pierced in the bearing guide 101 in the middle). The base end portion 95 b is disposed on the T groove 101 a side of the bearing guide 101, and the distal end portion 95 c is disposed so as to protrude to the outside of the bearing guide 101. As shown in FIG. 34, the base end portion 95 b of the torsion coil spring 95 is engaged with a pair of convex portions 104 protruding from the back surface of the pedestal 104 so as to contact the peripheral edge portion of the through hole 104 a of the pedestal 104. Is arranged. The base end portion 95 b of the torsion coil spring 95 is sandwiched between the upper end of the compression spring 103 and the back surface of the pedestal 104 as shown in FIGS. 31 and 32. The tip 95c of the coil spring 95 is disposed outside the right wall 97 as shown in FIG. The distal end portion 95c extends rearward along the outer surface of the wall portion 97 from the portion of the spring body 95a located on the wall portion 97, then changes the direction to extend outward, and further changes the direction to extend rearward. The portion extending rearward is a contact portion (first contact) 95d. The holding member 105 extending outward from the wall portion 97 has a pair of columnar portions 105a extending outward from the outer surface side of the wall portion 97 and a plate-like connecting portion 105b connecting them. A holding groove 105c is formed at the front end of the columnar part 105 in the front-rear direction, and the contact part 95d of the coil spring 95 described above is held in the holding groove 105c. The contact portion 95d is disposed at a portion corresponding to the tip of the back surface of the connecting portion 105b, and is prevented from being unnecessarily deformed when coming into contact with another member or the like. A portion located in the middle, that is, a portion that substantially contacts the contact spring 94 (see FIGS. 27 and 28) on the image forming apparatus main body 2 side corresponds to the wiping portion 105d formed at the tip of the connecting portion 105b. Thus, the contact spring 94 is easy to contact.

  When the intermediate transfer unit 31A is mounted at a predetermined position of the image forming apparatus main body 2 as described above, the intermediate transfer unit 94 is moved to the contact spring 94 protruding inward from the inner surface of the right side plate 75 of the main body frame 6 shown in FIG. The contact portion 95d of the torsion coil spring 95 on the unit 31 side comes into contact. As a result, the primary transfer bias generated by the high-voltage power supply (not shown) on the image forming apparatus main body 2 side is pressed from the contact spring 94 on the image forming apparatus main body 2 side to the torsion coil spring 95 on the intermediate transfer unit 31 side. It is applied to the primary transfer roller 41 via a spring 103, a bearing 102, and a shaft 41a.

  In the above embodiment, the case where the drum unit 36A is mounted after the development unit 40A is mounted at a predetermined position of the main body frame 6 has been described as an example. However, the drum unit 36A is mounted first, and then the development unit 40A. It can also be applied to the case of wearing.

  In the above embodiment, the case where the developing unit 40A and the drum unit 36A are separately configured has been described. However, the same applies even when the developing unit 40A and the drum unit 36a are integrally configured. Can do.

  In the above embodiment, the case where the intermediate transfer belt 31 is stretched between the two rollers of the drive roller 43 and the driven roller 44 in the intermediate transfer unit 31A has been described as an example. For example, the present invention can be applied in a similar manner to a case where two rollers are added to a tension roller (not shown) and are stretched by three or more rollers. In this case, the same effect can be obtained. You can do that.

  The present invention is not limited to an image forming apparatus, and can also be applied to a general apparatus in which an object having the same shape as an intermediate transfer unit is mounted and positioned inside a box-shaped main body frame. .

FIG. 2 is a perspective view of the entire image forming apparatus as viewed from the diagonally upper left side on the front side. FIG. 2 is a perspective view of the entire image forming apparatus as viewed from the rear and obliquely upward on the left side thereof. FIG. 2 is a diagram schematically showing an internal structure of the image forming apparatus as viewed from the left side. (A), (b) is a schematic diagram explaining the closed position of a front cover and a conveyance unit, and an open position. It is the perspective view which looked at the left side plate from the inside. It is the figure which looked at the left board straight from the inside It is the perspective view which looked at the right side board from the inner side. It is the figure which looked at the right side board straight from the inside. FIG. 10 is a perspective view illustrating a mounting operation of the developing unit. FIG. 10 is a perspective view illustrating a mounting operation of the developing unit. FIG. 10 is a perspective view illustrating a mounting operation of the developing unit. It is a perspective view explaining the mounting | wearing operation | movement of a drum unit. It is a perspective view explaining the mounting | wearing operation | movement of a drum unit. It is a perspective view explaining the mounting | wearing operation | movement of a drum unit. It is a perspective view explaining the mounting | wearing operation | movement of a drum unit. FIG. 10 is a perspective view for explaining an operation of mounting the intermediate transfer unit. FIG. 10 is a perspective view for explaining an operation of mounting the intermediate transfer unit. FIG. 10 is a perspective view for explaining an operation of mounting the intermediate transfer unit. FIG. 10 is a perspective view for explaining an operation of mounting the intermediate transfer unit. (A) is a perspective view explaining the movement of the left end side of the front end portion in the intermediate transfer unit at the time of mounting, and (b) is a perspective view explaining the movement of the right end side of the front end portion in the intermediate transfer unit at the time of mounting. FIG. (A) is a perspective view explaining the movement of the left end side of the front end portion in the intermediate transfer unit at the time of mounting, and (b) is a perspective view explaining the movement of the right end side of the front end portion in the intermediate transfer unit at the time of mounting. FIG. (A) is a perspective view explaining the movement of the left end side of the front end portion in the intermediate transfer unit at the time of mounting, and (b) is a perspective view explaining the movement of the right end side of the front end portion in the intermediate transfer unit at the time of mounting. FIG. (A) is a perspective view explaining the movement of the left end side of the front end portion in the intermediate transfer unit at the time of mounting, and (b) is a perspective view explaining the movement of the right end side of the front end portion in the intermediate transfer unit at the time of mounting. FIG. FIG. 9 is a perspective view for explaining a toner container mounting operation. FIG. 9 is a perspective view for explaining a toner container mounting operation. FIG. 9 is a perspective view for explaining a toner container mounting operation. It is a perspective view explaining the state by which the board | substrate holding member was arrange | positioned in the retracted position, and the contact spring protruded inward from the inner surface side of the right side board. It is a perspective view explaining the state by which the board | substrate holding member was arrange | positioned in the operation position, and the contact spring protruded inward from the inner surface side of the right side board. It is the perspective view which looked at the transfer frame of the intermediate transfer unit from diagonally below. It is a perspective view which shows the primary transfer roller arrange | positioned by the lower surface of the transfer frame. FIG. 6 is a perspective view showing the vicinity of a bearing guide in a state where a primary transfer roller is removed. It is a perspective view which shows the state which removed the bearing from the state of FIG. It is the perspective view which looked at the same state as FIG. 32 from a different angle. FIG. 33 is a perspective view showing a torsion coil spring 95 by further removing the pressing spring from the state of FIG. 32.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 6 ... Main body frame, 6a ... Opening part, 10 ... Top cover (cover member), 31 ... Intermediate transfer belt, 31A ... Intermediate transfer unit , 36... Photosensitive drum, 39... Transfer frame, 41... Primary transfer roller, 43... Driving roller (first roller, secondary transfer counter roller), 44 .. driven roller (second roller), 82 a ...... Left guide (tilt guide), 82b ... Right tilt guide (tilt guide), 85a, 85b ... Notch, 87a, 87b ... First guide boss (slide boss), 90a ... Left swing guide (Swing guide), 90b... Right swing guide (swing guide), 93a, 93b... Second guide boss (swing boss), 94... Contact spring (second contact), 95d. (First contact)

Claims (5)

A main body frame having an opening in the upper portion; and a removable intermediate transfer unit that is mounted and positioned at a predetermined position of the main body frame from above through the opening, and the intermediate transfer unit includes the transfer frame and the In an image forming apparatus having a first roller and a second roller rotatably supported by a transfer frame, and an intermediate transfer belt stretched endlessly on the first roller and the second roller,
The transfer frame includes a slide boss projecting in the belt width direction of the intermediate transfer belt in the vicinity of the first roller, which is the front end side when mounted, and the first roller projecting outward from the transfer frame. And a rocking boss arranged on the same axis,
The main body frame has an inclination guide and a swing guide arranged in the vicinity of one end corresponding to the front end side of the main body frame after mounting,
The inclined guide is inclined downward in the mounting direction downstream of the intermediate transfer unit, supports the slide boss from below, guides and engages the swing boss toward the swing guide,
The swing guide guides the swing operation of the entire intermediate transfer unit with the engaged swing boss as a reference, and is disposed at the predetermined position.
An image forming apparatus. The inclined guide has a cutout portion that allows the slide boss to move downward before the swing boss of the intermediate transfer unit when mounted is engaged with the swing guide.
The image forming apparatus according to claim 1. When the intermediate transfer unit is disposed at the predetermined position, the intermediate transfer belt is urged from the back surface side so that the front surface side of the intermediate transfer belt is brought into contact with the photosensitive drum disposed on the main body frame side. Having a primary transfer roller;
The image forming apparatus according to claim 2. The first roller is opposed to a secondary transfer roller that sandwiches the intermediate transfer belt between the intermediate transfer unit and the secondary transfer roller disposed on the main body frame side when the intermediate transfer unit is disposed at the predetermined position. Laura,
The image forming apparatus according to claim 3. The intermediate transfer unit has a first contact that is electrically connected to the primary transfer roller;
The main body frame has a second contact connected to a power source disposed on the main body frame side at a position where the intermediate transfer unit contacts the first contact when the intermediate transfer unit is disposed at the predetermined position. ,
The image forming apparatus according to claim 4.

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