Image forming apparatus

Abstract

To provide an image forming apparatus that has improved the attachment and removal properties and positioning properties of developing devices and an intermediate transfer device to a body frame.SOLUTION: An image forming apparatus comprises: developing devices that are attached to a body frame along a predetermined attachment direction; and an intermediate transfer device that is attached to the body frame after the developing devices are attached to the body frame. The developing devices each include an elastically deformable hook 57. The body frame includes a fall-out prevention part 75 to which the hook 57 is locked after being elastically deformed relative to the body frame. The intermediate transfer device includes a regulation part 69b that prevents separation of the hook 57 from the fall-out prevention part 75.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image forming apparatus including a detachable developing device and an intermediate transfer device.

Background Art

[0002] In an image forming apparatus, the order in which a developing device, a photosensitive drum unit, and an intermediate transfer device are attached to the main body frame is often determined. For example, after the developing device is attached, the photosensitive drum unit is attached, and then the intermediate transfer device is attached.

[0003] The image forming apparatus described in Patent Document 1 individualizes image forming means into a plurality of units and enables preferential replacement of units with a short life. Further, the image forming apparatus described in Patent Document 2 includes a lock lever for positioning an image forming unit with respect to the apparatus main body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the image forming apparatus described in Patent Document 1, each unit is provided with an operation member such as a hook member for fixing to the apparatus main body, and the user operates the operation member to position and fix each unit to the apparatus main body. Also, in the image forming apparatus of Patent Document 2, the user operates the lock lever to position and fix the image forming unit to the apparatus main body.

[0006] Thus, since the user needs to operate the operation member and the lock lever, the number of steps in the mounting operation increases. Further, there is also a problem that the cost increases due to the provision of these members.

[0007] In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that improves the detachability and positionability of a developing device and an intermediate transfer device with respect to a main body frame.

Means for Solving the Problems

[0008] To achieve the above object, an image forming apparatus according to the present invention includes a developing device mounted on a main body frame along a predetermined mounting direction, and an intermediate transfer device mounted on the main body frame after the developing device is mounted on the main body frame. The developing device includes an elastically deformable hook, the main body frame includes a retaining portion that is locked after the hook elastically deforms with respect to the main body frame, and the intermediate transfer device includes a restricting portion that prevents the hook from detaching from the retaining portion.

[0009] In the present invention, it may be characterized in that the mounting direction and the deformation direction of the hook are orthogonal to each other.

[0010] In the present invention, the main body frame may further include a guide groove that guides the developing device along the mounting direction, and the retaining portion may be formed in the guide groove.

[0011] In the present invention, the developing device may have a guided projection that is guided along the guide groove, and the hook and the guided projection may be integrally formed.

[0012] In the present invention, the restricting portion may be a block piece inserted between the hook retained by the retaining portion and a side edge of the guide groove.

Effects of the Invention

[0013] According to the present invention, by mounting the developing device and then mounting the intermediate transfer device, the movement of the developing device in the vertical, horizontal, and front-rear directions is restricted. Therefore, the developing device can be easily positioned without operating a lever member, an operating member, or adding a member.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] First, with reference to FIG. 1, the overall configuration of the image forming apparatus 1 will be described. FIG. 1 is a front view schematically showing the internal configuration of the image forming apparatus 1.

[0017] The image forming apparatus 1 has a substantially rectangular parallelepiped appearance and includes a main body frame 3 that forms a hollow portion inside. The main body frame 3 is composed of four vertical columns arranged at the four corners, a plurality of horizontal columns arranged between adjacent vertical columns, and front and rear side plates and left and right side plates (all are omitted in FIG. 1) that cover the surfaces surrounded by the vertical and horizontal columns. The hollow portion is partitioned by the horizontal columns into a plurality of hollow portions arranged in the vertical direction.

[0018] In the hollow portion of the main body frame 3, a sheet feeding unit 5 for feeding a sheet, an image forming unit 7 for forming a toner image to be transferred onto the sheet, a fixing unit 9 for fixing the toner image onto the sheet, and a discharging unit 11 for discharging the sheet onto which the toner image has been fixed are accommodated. The sheet feeding unit 5 is accommodated in the lower hollow portion. The image forming unit 7 is arranged above the sheet feeding unit 5, the fixing unit 9 is arranged above the image forming unit 7, and the discharging unit 11 is arranged above the fixing unit 9. Further, on the upper surface of the main body frame 3, a discharge tray 13 on which the sheets discharged from the discharging unit 11 are stacked is provided.

[0019] The sheet feeding unit 5 includes a sheet feeding cassette 21 in which sheets are accommodated and a sheet feeding device 23 for feeding out the sheets accommodated in the sheet feeding cassette 21.

[0020] The image forming unit 7 includes four developing devices 31 and photoreceptor drum units 33 corresponding to four colors (yellow, cyan, magenta, black) of toner, an intermediate transfer device 35, a secondary transfer roller 37, and an exposure device 39. Each photoreceptor drum unit 33 includes a rotatable photoreceptor drum 41, a charging device 43 arranged around the photoreceptor drum 41, and a cleaning device 45. The four developing devices 31 are arranged side by side in the left - right direction for each toner color. The four photoreceptor drum units 33 are arranged on the right side of the four developing devices 31. Further, the image forming unit 7 includes a toner container 47 for accommodating the toner supplied to the four developing devices 31. The developing device 31 will be described later.

[0021] The intermediate transfer device 35 is disposed above the four developing devices 31 and the photosensitive drum units 33. A primary transfer nip is formed between the intermediate transfer device 35 and the photosensitive drums 41 of the four photosensitive drum units 33. The secondary transfer roller 37 faces the intermediate transfer device 35 and forms a secondary transfer nip. The intermediate transfer device 35 will be described later.

[0022] The fixing unit 9 includes a heating roller and a pressure roller, and forms a fixing nip between the two rollers. The discharging unit 11 includes a pair of discharging rollers.

[0023] Furthermore, in the hollow portion, a conveyance path 15 for the sheet that travels from the paper feeding device 23 of the paper feeding unit 5 through the secondary transfer nip and the fixing nip to the discharging unit 11 is formed. In the conveyance path 15, a registration roller pair 17 is provided on the upstream side in the sheet conveyance direction from the secondary transfer nip.

[0024] The image forming operation will be briefly described. In each photosensitive drum unit 33 of the image forming unit 7, the charging device 43 charges the photosensitive drum 41 to a predetermined potential. Thereafter, the photosensitive drum 41 is exposed by the exposure device 39 based on the image data to form an electrostatic latent image. The electrostatic latent image is developed into a toner image by the developing device 31. The toner image is transferred from the photosensitive drum 41 to the intermediate transfer device 35 at the primary transfer nip. In the four photosensitive drum units 33, the toner images are respectively transferred to the intermediate transfer device 35, thereby forming a full-color toner image on the intermediate transfer device 35.

[0025] On the other hand, in the sheet feeding unit 5, a sheet is fed from the sheet feeding cassette 21 to the conveyance path 15 by the sheet feeding device 23. The sheet is conveyed along the conveyance path 15, and after the skew is corrected by the registration roller pair 17, it is conveyed to the secondary transfer nip. In the secondary transfer nip, a full-color toner image is transferred from the intermediate transfer device 35 to the sheet. Thereafter, the sheet is conveyed to the fixing unit 9, and the toner image is heated and pressurized at the fixing nip and fixed to the sheet. The sheet is conveyed to the discharge unit 11 and discharged to the discharge tray 13 by the discharge roller pair.

[0026] Next, with reference to FIGS. 2A and 2B, the developing device 31 will be described. FIG. 2A is a perspective view showing the developing device 31, and FIG. 2B is a perspective view showing the guided projections 55 and the hooks 57.

[0027] As shown in FIG. 2A, the developing device 31 includes a developing roller 51, a stirring roller and a supply roller (both not shown), and a housing 53 that houses them.

[0028] The housing 53 is composed of front and rear side plates 53a facing each other in the front-rear direction and an outer peripheral plate 53b, and has a hollow portion in which the developer is housed. An opening 53c is formed along the front-rear direction in a part of the outer peripheral plate 53b. The developing roller 51, the stirring roller, and the supply roller are housed in the hollow portion. Both ends of each roller are rotatably supported by the front and rear side plates 53a. A part of the developing roller 51 is exposed from the opening 53c of the housing 53. The housing 53 is made of, for example, resin.

[0029] As shown in FIG. 2B, front and rear guided projections 55 and hooks 57 are formed on the outer surfaces of the front and rear side plates 53a. Each guided projection 55 has an annular lower portion 55a and an upper portion 55b protruding from the outer surface of each side plate 53a. The lower portion 55a has an elongated oval (rounded rectangle) shape when viewed in the front-rear direction, and the upper portion 55b has a rectangular shape when viewed in the front-rear direction.

[0030] The hook 57 extends upward from one end (the right end in this example) of the upper wall of the upper portion 55b of the guided projection 55. A claw 59 is formed at the upper end of one side surface of the hook 57 (the side surface opposite to the side of the guided projection 55, the right side surface in this example). The claw 59 is triangular when viewed from the front-rear direction. That is, the claw 59 protrudes laterally (rightward in this example) more than the guided projection 55. The hook 57 is elastically deformed in the left-right direction about the lower end portion.

[0031] Next, with reference to FIGS. 3A and 3B, the intermediate transfer device 35 will be described. FIG. 3A is a perspective view showing the intermediate transfer device 35, and FIG. 3B is a perspective view showing the block piece 69.

[0032] As shown in FIG. 3A, the intermediate transfer device 35 includes an endless intermediate transfer belt 61, a driving roller 63 and a driven roller 65 around which the intermediate transfer belt is wound, and front and rear side plates 67 that support the driving roller 63 and the driven roller 65. The front and rear side plates 67 have a rectangular shape that is long in the left-right direction. The driving roller 63 is rotatably supported between the right end portions of the front and rear side plates 67, and the driven roller 65 is rotatably supported between the left end portions of the front and rear side plates 67.

[0033] Four block pieces 69 are fixed to the front and rear side plates 67 at a predetermined interval in the left-right direction. As shown in FIG. 3B, each block piece 69 has a rectangular base portion 69a and a vertically long annular insertion portion 69b. The base portion 69a of each block piece 69 is fixed to the side plate 67 with a screw B, and the insertion portion 69b hangs down from the base portion 69a.

[0034] The developing device 31, the photosensitive drum unit 33, and the intermediate transfer device 35 are accommodated in this order in the hollow portion of the main body frame 3 along the attachment / detachment direction along the vertical direction, and are attached to the front and rear side plates of the main body frame 3.

[0035] Next, with reference to FIG. 4, the front and rear side plates 71 of the main body frame 3 will be described. FIG. 4 is a front view showing the guide grooves 73 formed in the side plates 71. Four guide grooves 73 are formed in the front and rear side plates 71 at a predetermined interval in the left-right direction. Each guide groove 73 extends downward from the upper edge of the side plate 71, and the width of the upper part 73a on the inlet side is wider than the width of the lower part 73b on the bottom side. The step portion 73c between the upper part 73a and the lower part 73b is inclined downward toward the inside of the guide groove 73. The width of the lower part 73b is slightly wider than the width of the guided projection 55 (see FIG. 2B) of the developing device 31.

[0036] Also, on one side edge (the right side edge in this example) of the guide groove 73, a convex portion 75 protruding toward the inside of the upper part 73a is formed. The convex portion 75 has a substantially horizontal upper surface and a lower surface inclined downward, and the corner between the upper surface and the lower surface is rounded. By providing the convex portion 75 in this way, a triangular concave portion 77 is formed between the inner surface of the step portion 73c on the right side of the guide groove 73 and the lower surface of the convex portion 75 when viewed in the front-rear direction.

[0037] In the image forming apparatus 1 having the above configuration, the procedure for mounting the developing device 31, the photosensitive drum unit 33, and the intermediate transfer device 35 on the main body frame 3 will be described with reference to FIG. 5. FIG. 5 is a front view for explaining the mounting process of the developing device 31 and the intermediate transfer device 35 on the main body frame 3. First, four developing devices 31 are accommodated in the hollow portion of the main body frame 3 from above, arranged in the left-right direction, and attached to the front and rear side plates 71.

[0038] At this time, as shown in FIG. 5(a), the front and rear guided projections 55 of the developing device 31 are inserted into the guide grooves 73 of the front and rear side plates 71 from above. When the guided projection 55 is moved downward along the guide groove 73, eventually, the claw 59 of the hook 57 abuts against the upper surface of the convex portion 75 protruding inside the guide groove 73.

[0039] Further, when the guided projection 55 moves downward along the guide groove 73, the claw 59 of the hook 57 is pushed by the convex portion 75, and as shown in FIG. 5(b), the hook 57 is elastically deformed so as to rotate leftward. Thereafter, when the guided projection 55 further moves downward along the guide groove 73, as shown in FIG. 5(c), the guided projection 55 reaches the bottom of the guide groove 73 and the hook 57 separates from the convex portion 75 and elastically returns, and the claw 59 engages with the concave portion 77. At this time, the entire hook 57 enters the guide groove 73. Thereby, the developing device 31 is attached to the front and rear side plates 71. Further, the developing device 31 is prevented from coming out of the guide groove 73 by the convex portion 75. Thus, the convex portion 75 is an example of a retaining portion where the hook 57 is locked in the present invention. Here, as shown in FIG. 5(c), a space is open on the left side of the hook 57.

[0040] Thereafter, the four photoreceptor drum units 33 are accommodated in the hollow portion from above and attached to the front and rear side plates 71 on the right side of the four developing devices 31. At this time, the developing roller 51 exposed from the opening 53c of the housing 53 of the developing device 31 faces the photoreceptor drum 41 of the photoreceptor drum unit 33. The description of the attachment of the photoreceptor drum unit 33 to the side plate 71 is omitted.

[0041] Thereafter, the intermediate transfer device 35 is accommodated in the hollow portion from above and attached to the front and rear side plates 71 above the four developing devices 31 and the four photoreceptor drum units 33. At this time, the lower surface of the intermediate transfer belt 61 of the intermediate transfer device 35 faces the photoreceptor drum 41.

[0042] Further, as shown in FIG. 5(d), the insertion portions 69b of the front and rear block pieces 69 of the intermediate transfer device 35 are inserted into the guide grooves 73 of the front and rear side plates 71 from above. As shown in FIG. 5(e), the insertion portion 69b of the block piece 69 is inserted into the space on the left side of the hook 57 in the guide groove 73. As a result, the leftward rotation of the hook 57 is restricted by the insertion portion 69b. Thus, the insertion portion 69b is an example of a restricting portion that prevents the hook 57 from detaching from the retaining portion (convex portion 75) in the present invention.

[0043] As described above, according to the present invention, by mounting the developing device 31 on the front and rear side plates 71 and then mounting the intermediate transfer device 35 on the front and rear side plates 71, the movement of the developing device 31 in the vertical, horizontal, and front-rear directions is restricted. In this way, the developing device 31 can be positioned by mounting the intermediate transfer device 35 without operating the lever member or the operation member. Further, since the lever member and the operation member are not required, the cost can be reduced.

[0044] Furthermore, by mounting the intermediate transfer device 35, the deformation of the hook 57 of the developing device 31 is restricted. That is, it is possible to prevent the hook 57 from being inadvertently deformed in the direction in which the claw 59 detaches from the concave portion 77. Therefore, even when the image forming apparatus 1 is dropped or vibrated during transportation or the like, fluctuations of the developing device 31 can be prevented. In addition, since a clicking feeling due to the elastic deformation of the hook 57 is given to the operator, the developing device 31 can be reliably attached and detached.

[0045] Also, the direction in which the claw 59 of the hook 57 is locked to the concave portion 77, that is, the deformation direction of the hook 57, is orthogonal to the mounting direction of the developing device 31. Therefore, it becomes difficult for the claw 59 of the hook 57 to come out of the concave portion 77.

[0046] In addition, the guided projection 55 and the hook 57 are integrally formed, and a convex portion 75 is formed on the side edge of the guide groove 73 in which the guided projection 55 is guided. Therefore, by guiding the guided projection 55 along the guide groove 73 and mounting the developing device 31 on the main body frame 3, the hook 57 can be automatically prevented from coming off by the convex portion 75.

[0047] Although the present invention has been described with respect to specific embodiments, the present invention is not limited to the above embodiments. Those skilled in the art can modify the above embodiments without departing from the scope and gist of the present invention.

Explanation of Reference Numerals

[0048] 1 Image forming apparatus 3 Main body frame 31 Developing device 35 Intermediate transfer device 55 Guided projection 57 Hook 69 Block piece (restriction part) 73 Guide groove 75 Protrusion (anti - detachment part)

Claims

1. A developing device mounted on a main body frame along a predetermined mounting direction, and An intermediate transfer device mounted on the main body frame after the developing device is mounted on the main body frame, the image forming apparatus comprising: The developing device includes an elastically deformable hook, The main body frame includes a retaining portion that is locked after the hook elastically deforms with respect to the main body frame, The intermediate transfer device includes a restricting portion that prevents the hook from detaching from the retaining portion. The image forming apparatus is characterized in that.

2. The image forming apparatus according to claim 1, wherein the mounting direction and the deformation direction of the hook are orthogonal to each other.

3. The main body frame further includes a guide groove for guiding the developing device along the mounting direction, The image forming apparatus according to claim 1, wherein the retaining portion is formed in the guide groove.

4. The developing device has a guided projection guided along the guide groove, The image forming apparatus according to claim 3, wherein the hook and the guided projection are integrally formed.

5. The image forming apparatus according to claim 3, wherein the restricting portion is a block piece inserted between the hook retained by the retaining portion and a side edge of the guide groove.

Images