Image forming apparatus

Abstract

To provide an image forming apparatus that prevents the generation of an image defect and an unusual sound due to adhesion, to a drive gar, of foreign substances generated in association with fastening to a driving device with screws without increasing the size of the driving device.SOLUTION: A first support 20 is formed with fastening holes 570 to which fastening members are fastened in a projection surface on which a second support part 25a is projected in a rotation axis direction of a drive gear, and a second support 25 is arranged on the upstream side of the first support 20 in a fastening direction to fasten the fastening members. The second support 25 has attachment parts 270a-270c that are extended toward the downstream side in the fastening direction from the second support part 25a to contact a first support part 20a in the projection surface and are formed with attachment holes 27 into which the fastening members are inserted at positions overlapping the fastening holes 570 in contact parts in contact with the first support part 20a.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an image forming apparatus using electrophotographic technology, such as a printer, a copier, a facsimile machine, or a multifunction peripheral.

Background Art

[0002] In image forming apparatuses such as printers, copiers, facsimile machines, and multifunction peripherals that integrally combine them, drive rollers for rotating rotors such as a photosensitive drum, a developing sleeve, and an intermediate transfer belt are provided in the apparatus main body. Conventionally, in order to drive these rotors, a drive device that aggregates a motor and drive gears is attached to the rear side plate of the apparatus main body. As an example, a drive device has been proposed that has two support plates arranged at both ends in the axial direction of the rotation axis of the drive gear and supports the rotation axis of the drive gear, and the drive gear is arranged in a space sandwiched between these support plates (Patent Document 1).

[0003] In the drive device described in Patent Document 1, the two support plates are connected via a cover member that closes the gap between them. That is, if foreign matter such as dust enters the space where the drive gear is arranged from the outside and adheres to the drive gear, rotational fluctuations will occur in the rotor driven by the drive device, and periodic band-shaped density unevenness (referred to as banding, etc.) may occur in the image formed on the recording material. There is also a risk of image defects. Further, if foreign matter adhering to the drive gear is bitten into the drive gear, abnormal noise will occur. Therefore, in order to prevent the intrusion of foreign matter from the outside, a cover member that closes the gap between the two support plates is installed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when connecting two support plates using screws, for example, foreign matter such as metal powder generated during screw fastening may adhere to the drive gear. That is, although fastening holes for screws are pre-drilled in the support plates, metal powder generated when the support plates are cut to make the holes may remain in the fastening holes as shavings. Conventionally, because screws are inserted and fastened from the outside of the support plate toward the inside (space side), the metal powder is pushed inward from the fastening holes by the screws and adheres to the drive gear which is pre-positioned on the inside. Alternatively, if screws are fastened while tapping is performed, the metal powder generated in response to tapping may be pushed inward and adhere to the drive gear. Metal powder adhering to the drive gear, like foreign matter such as dust that enters from the outside, can cause the image defects and abnormal noises mentioned above.

[0006] Therefore, in order to prevent metal powder generated during screw fastening from adhering to the drive gear, it is conceivable to create a fastening region by forming fastening holes on the outer circumference of two support plates when viewed from the direction of the rotation axis of the drive gear, and fasten the screws there. In this way, any metal powder that may be generated during screw fastening will fall to the outside rather than the inside (space side) of the support plates, thus preventing the metal powder from adhering to the drive gear. However, if a new fastening region is to be created on the support plates, the drive device will have to be made larger, which goes against the current demand for miniaturization of image forming machines, making its adoption difficult.

[0007] Therefore, there has been a long-standing desire for a drive system that does not increase the size of the drive unit while suppressing image defects and abnormal noises caused by foreign matter adhering to the drive gears during screw fastening, but no such system has yet been proposed.

[0008] The present invention has been made in view of the above problems, and aims to provide an image forming apparatus that suppresses image defects and the generation of abnormal noise caused by foreign matter adhering to the drive gear during screw fastening in the drive unit, without increasing the size of the drive unit. [Means for solving the problem]

[0009] One aspect of the present invention relates to an image forming apparatus for forming an image on a recording material, comprising a rotating body and a drive device for driving the rotating body, wherein the drive device comprises a drive source, a plurality of drive gears for transmitting the driving force of the drive source to the rotating body, a first support having a first support portion that holds the drive source and supports one end of the rotating shaft of the drive gear in the direction of the rotation axis of the drive gear, and a second support having a second support portion that supports the other end of the rotating shaft and is connected to the first support by a fastening member, wherein the first support has a fastening hole formed in the projection plane obtained by projecting the second support portion in the direction of the rotation axis of the drive gear, the second support is positioned upstream of the first support in the fastening direction for fastening the fastening member, and the second support is front Record number One support part is positioned in front Closing Extends toward the downstream side in the direction of connection. It has a mounting portion. , the above The mounting portion At the contact portion that contacts the first support portion teeth, A mounting hole into which the fastening member is inserted is formed at a position overlapping with the aforementioned fastening hole. It is being done This is an image forming apparatus characterized by the following: [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress image defects and abnormal noise caused by foreign matter adhering to the drive gear during the fastening of fastening members in the drive unit, without increasing the size of the drive unit, using a simple configuration. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic diagram showing the configuration of the image forming apparatus of this embodiment. [Figure 2] A perspective view showing the drive mechanism. [Figure 3] A view of the drive unit from the main support side. [Figure 4] An exploded perspective view showing the drive mechanism. [Figure 5] A view of the drive unit from the sub-support side. [Figure 6] A cross-sectional view showing the drive mechanism. [Figure 7] This diagram illustrates the metal powder generated during screw fastening, showing (a) before inserting the screw into the fastening hole and (b) after inserting the screw into the fastening hole. [Figure 8] (a) A view of a conventional drive unit from the sub-support side, (b) A cross-sectional view showing a conventional drive unit. [Figure 9] This is a schematic diagram illustrating a comparative example, showing (a) when the screw is fastened from the sub-support side to the main support side, and (b) when the screw is fastened from the main support side to the sub-support side. [Modes for carrying out the invention]

[0013] <Image forming apparatus> The image forming apparatus of this embodiment will be described with reference to Figure 1. The image forming apparatus 101 shown in Figure 1 is an intermediate transfer type full-color printer. The image forming apparatus 101 has image forming units PY, PM, PC, and PK, which form yellow, magenta, cyan, and black toner images, respectively. The image forming apparatus 101 forms a toner image on the recording material S in response to an image signal from an external device (not shown), such as a document reader 102 or a personal computer, which is located above it in the vertical direction. The recording material S can be a sheet material such as paper, plastic film, or cloth. In this specification, the side on which the user stands to operate the control panel (not shown) in order to operate the image forming apparatus 101 is called the "front," and the opposite side is called the "back."

[0014] In the image forming apparatus 101 shown in FIG. 1, the image forming units PY, PM, PC, and PK are arranged side by side along the moving direction of the intermediate transfer belt 116 (direction of arrow R2). The intermediate transfer belt 116 is an endless belt member that carries and conveys the toner images primarily transferred from the photosensitive drums 112Y, 112M, 112C, and 112K of the respective image forming units PY, PM, PC, and PK. The intermediate transfer belt 116 is stretched over the respective rotating bodies of the secondary transfer inner roller 116a, the tension roller 116b, the pre-secondary transfer roller 116c, and the stretching roller 116d. Then, the intermediate transfer belt 116 is moved in the moving direction by the secondary transfer inner roller 116a (rotating body, secondary transfer roller) that is rotationally driven by a driving device 90 (see FIG. 2) described later. That is, in the present embodiment, the secondary transfer inner roller 116a also serves as a driving roller that drives the intermediate transfer belt 116.

[0015] The image forming apparatus 101 has a support frame body 101A that supports units such as the above-described photosensitive drums 112Y to 112K, the secondary transfer inner roller 116a, the tension roller 116b, the pre-secondary transfer roller 116c, and the stretching roller 116d. The support frame body 101A is composed of a plurality of sheet metals such as a front side plate provided on the front side of the image forming apparatus 101, a rear side plate provided on the rear side and supporting each unit together with the front side plate, a stay connecting the front side plate and the rear side plate, and a support column supporting the front side plate, and is covered by an exterior cover (not shown) that constitutes the appearance of the image forming apparatus 101.

[0016] The secondary transfer outer roller 117 is arranged so as to sandwich the secondary transfer inner roller 116a and the intermediate transfer belt 116, and forms a secondary transfer nip portion T2 that transfers the toner image on the intermediate transfer belt 116 to the recording material S. In the secondary transfer nip portion T2, the secondary transfer inner roller 116a and the secondary transfer outer roller 117 rotate and the recording material S is sandwiched and conveyed.

[0017] Below the image forming apparatus 101, one or more cassettes 131 containing the recording material S are arranged. The recording material S contained in the cassette 131 is supplied one by one from the cassette 131 to the conveyance path 60 by the feed roller 151 in accordance with the image forming timing. The recording material S is conveyed to the registration roller 170 arranged in the conveyance path 60, and skew correction and timing correction are performed by the registration roller 170, and then it is conveyed toward the secondary transfer nip portion T2. The cassette 131 is supported so as to be slidable with respect to the support frame 101A. The user can replenish the recording material S in the cassette 131 by pulling out the cassette 131 to the front side of the image forming apparatus 101.

[0018] The four image forming units PY, PM, PC, and PK provided in the image forming apparatus 101 have substantially the same configuration except that the colors of the toner used in the developing devices 114 each have are different. Therefore, here, the yellow image forming unit PY will be described as a representative, and the description of the other image forming units PM, PC, and PK will be omitted.

[0019] In the image forming unit PY, a photosensitive drum 112Y is disposed as one of the rotating bodies. The photosensitive drum 112Y is rotationally driven by a driving device 90 (see FIG. 2) described later. Around the photosensitive drum 112Y, a charging device 113, a developing device 114, and a primary transfer roller 119 are arranged.

[0020] When the image formation operation is started, the surface of the rotating photosensitive drum 112Y is first uniformly charged by the charging device 113. Next, the photosensitive drum 112Y is scanned and exposed by laser light emitted from the exposure device 110, which is shared by the image formation units PY to PK. This forms an electrostatic latent image on the photosensitive drum 112Y corresponding to the image signal. The electrostatic latent image on the photosensitive drum 112Y is developed by toner (developer) in the developing device 114, and a toner image is formed on the photosensitive drum 112Y. The developing device 114 includes a transport screw (not shown) that circulates and transports the developer in the developing container, and a developing sleeve 114a (rotating body) that carries the developer and rotates to develop the toner image on the photosensitive drum 112Y. The developing sleeve 114a is driven by a drive device 90 (see Figure 2), which will be described later.

[0021] The toner image formed on the photosensitive drum 112Y is first transferred from the photosensitive drum 112Y to the intermediate transfer belt 116 in a primary transfer section formed between the photosensitive drum 112Y and the primary transfer roller 119, which are positioned on either side of the intermediate transfer belt 116. At this time, a primary transfer voltage is applied to the rotating primary transfer roller 119. In this way, the intermediate transfer belt 116 rotates carrying the toner image transferred from the photosensitive drum 112Y.

[0022] By sequentially performing the operations described above in the yellow, magenta, cyan, and black image forming units PY to PK, a toner image can be formed on the intermediate transfer belt 116. For example, a single-color toner image can be formed, or some of the four colors can be appropriately superimposed to form a toner image of a desired color. In accordance with the timing of the formation of these toner images, the recording material S supplied from the cassette 131 is transported to the secondary transfer nip unit T2 via the registration roller 170. Then, for example, by applying a secondary transfer voltage to the secondary transfer outer roller 117 using a high-voltage power supply (not shown), the toner image on the intermediate transfer belt 116 is secondary transferred to the recording material S as it passes through the secondary transfer nip unit T2.

[0023] The recording material S onto which the toner image has been transferred from the intermediate transfer belt 116 is transported to the fuser 120. In the fuser 120, the toner image is fixed to the recording material S by applying heat and pressure to the recording material S while holding and transporting it. In the single-sided printing mode, where the toner image is formed on only one side of the recording material S, the recording material S on which the toner image has been fixed by the fuser 120 is discharged to the recording material discharge section 123. On the other hand, in the double-sided printing mode, where the toner image is formed on both sides of the recording material S, after the toner image is fixed to one side by the fuser 120, the recording material S is flipped over by switchback transport and transported through the double-sided transport path 61 toward the registration roller 170. Thereafter, the recording material S undergoes the same process as in the single-sided printing mode, and the fuser 120 forms a toner image on the other side as well, after which it is discharged to the recording material discharge section 123.

[0024] In this embodiment, the intermediate transfer belt 116, secondary transfer inner roller 116a, tension roller 116b, second-turn front roller 116c, tension roller 116d, and multiple primary transfer rollers 119 described above form an intermediate transfer unit 300.

[0025] Furthermore, the image forming apparatus 101 can not only form multicolor images, but can also form monochrome black images using only the image forming unit PK. When forming monochrome black images, the primary transfer rollers 119 other than the black ones are separated from the intermediate transfer belt 116 by a primary transfer roller separation mechanism (not shown) driven by a drive unit 90 (see Figure 2), which will be described later.

[0026] <Overview of the drive system> In the image forming apparatus 101 of this embodiment, a drive device 90 is provided to drive the photosensitive drums 112Y to 112K, the secondary transfer internal roller 116a, the primary transfer roller separation mechanism (not shown), and the developing apparatus 114 (specifically the developing sleeve 114a). The overview of the drive device 90 will be explained using Figures 2 to 4 with reference to Figure 1.

[0027] As will be described in detail later, the drive unit 90 has a main support 20 as a first support, which is formed from, for example, a thin metal plate, and a sub-support 25 as a second support (see Figure 4). In this embodiment, the drive unit 90 is fixed to the outside of the support frame 101A of the image forming apparatus 101, rather than to the inside. Here, the outside of the support frame 101A refers to the side covered by the exterior cover described above. Therefore, the drive unit 90 can be accessed by removing the exterior cover of the image forming apparatus 101, making it easier to maintain than a configuration in which it is fixed to the inside of the support frame 101A.

[0028] As shown in Figures 2 and 3, the drive unit 90 is attached to the rear plate 10 of the support frame 101A (see Figure 1). The drive unit 90 is fixed to the rear plate 10 by screws 41 via a plurality of fixing parts 55a to 55h formed on the outer circumference of the main support 20, with the sub-support 25 facing the rear plate 10. Mounting holes for attaching the screws 41 for fastening the main body are formed in the fixing parts 55a to 55h.

[0029] As shown in Figure 2, the main support 20 has an outer peripheral wall 15 erected toward the rear plate 10 to surround its outer circumference and prevent foreign matter such as dust from entering the drive device 90 where the drive gear (see Figure 4) is located. The fixing parts 55a to 55h described above are formed by bending the outer peripheral wall 15 in an L-shape relative to the wall surface so that the tips of the outer peripheral wall 15 can abut against the rear plate 10 and be fixed to the rear plate 10 by screws 41. In other words, the fixing parts 55a to 55h are flange parts of the main support 20. If it is difficult to provide the outer peripheral wall 15 continuously due to sheet metal processing and an opening is formed, the opening may be covered with sheet material or the like.

[0030] As shown in Figures 2 and 3, one side of the main support 20 holds multiple motors (30CL, 30K, 30S, 30Ga~30Gd) as drive sources for driving a rotating body rotatably supported on the rear plate 10. Here, one motor 30CL is held to drive the yellow, magenta, and cyan photosensitive drums 112Y, 112M, and 112C, and one motor 30K is held to drive the black photosensitive drum 112K and the secondary transfer internal roller 116a. In addition, one motor 30S is held to drive the primary transfer roller separation mechanism (not shown) described above, and four motors 30Ga, 30Gb, 30Gc, and 30Gd are held to individually drive the yellow, magenta, cyan, and black developing devices 114 (specifically the developing sleeves 114a).

[0031] On the other hand, on the two sides of the main support 20 opposite to the aforementioned one side, drive gears (35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd) are provided, as shown in Figure 4, to transmit the driving force of the motors (30CL, 30K, 30S, 30Ga~30Gd, see Figure 3) to the rotating body of the support frame 101A.

[0032] Drive gears 35Cla and 35CLb are rotated by the drive of motor 30CL, which is transmitted by gear 350a that engages with the rotating shaft 30CLj of motor 30CL. On the other hand, drive gear 35CLc engages with gear 350b, which engages with drive gear 35CLb, and is rotated by the drive of motor 30CL, which is transmitted via drive gears 35CLb and 350b.

[0033] Furthermore, drive gear 35Ka engages with drive gear 35Ke, which rotates in engagement with the drive shaft 30Kj of motor 30K, and rotates through the drive of motor 30K transmitted via drive gear 35Ke. Drive gear 35Kb rotates through drive gear 35Kd, which rotates in engagement with the drive shaft 30Kj of motor 30K, and through drive gear 35Kc, which engages with drive gear 35Kd, and rotates through the drive of motor 30K transmitted via drive gear 35Kc.

[0034] Furthermore, the drive gear 35Sc rotates due to the drive of the motor 30S, which is transmitted via the drive gear 35Sa, which engages with the rotation shaft 30Sj of the motor 30S, and the drive gear 35Sb, which engages with the drive gear 35Sa.

[0035] The drive gear 35Ga rotates by directly engaging with the rotation shaft 30Gaj of the motor 30Ga, thereby transmitting the drive of the motor 30Ga. The drive gear 35Gb rotates by directly engaging with the rotation shaft 30Gbj of the motor 30Gb, thereby transmitting the drive of the motor 30Gb. The drive gear 35Gc rotates by directly engaging with the rotation shaft 30Gcj of the motor 30Gc, thereby transmitting the drive of the motor 30Gc. The drive gear 35Gd rotates by directly engaging with the rotation shaft 30Gdj of the motor 30Gd, thereby transmitting the drive of the motor 30Gd.

[0036] The drive gears 35CLa to 35CLc transmit the driving force of the motor 30CL to the yellow, magenta, and cyan photosensitive drums 112Y, 112M, and 112C. More specifically, drive gear 35CLa transmits the driving force to the cyan photosensitive drum 112C, drive gear 35CLb transmits the driving force to the magenta photosensitive drum 112M, and drive gear 35CLc transmits the driving force to the yellow photosensitive drum 112Y. Drive gears 35Ka and 35Ke transmit the driving force of the motor 30K to the black photosensitive drum 112K. Drive gears 35Kb to 35Kd transmit the driving force of the motor 30K to the secondary transfer roller 216a. Furthermore, drive gears 35Sa to 35Sc transmit the driving force of motor 30S to the primary transfer roller separation mechanism (not shown), and drive gears 35Ga to 35Gd are provided to transmit the driving force of four motors 30Ga to 30Gd to the yellow, magenta, cyan, and black developing units 114 (specifically the developing sleeve 114a). The gear tooth surfaces of these drive gears (35CLa to 35CLc, 35Ka to 35Ke, 35Sa to 35Sc, 35Ga to 35Gd) are coated with viscous grease to ensure lubrication and quiet operation during rotation.

[0037] The drive gears 35CLa to 35CLc have couplings 36a to 36d that transmit power to the yellow, magenta, and cyan photosensitive drums 112Y to 112C. The drive gear 35Ka has a coupling 36d that transmits power to the black photosensitive drum 112K, and the drive gear 35Kb has a coupling 36e that transmits power to the secondary transfer roller 216a. Each of these couplings is exposed through through holes 258a to 258e provided in the second support portion 25a of the sub-support 25, and is capable of transmitting driving force to its respective unit. On the other hand, the toothed surfaces of the drive gears 35CLa to 35CLc and drive gears 35Ka to 35Ke that transmit power are located in a space enclosed by the main support 20 and the sub-support 25. The drive gears 35Ga to 35Gd are arranged in a space covered by the main support 20 and the sub-support 25 (i.e., in the drive gear housing space formed by the main support 20 and the sub-support 25). Drive force is transmitted to the four developing devices 114 by providing other gears to which drive force is transmitted from the drive gears 35Ga to 35Gd, and couplings to which drive force is transmitted from these other gears, on the outside of the sub-support 25. These couplings protrude inward from through holes provided in the rear plate 10 of the support frame 101A, thereby enabling the transmission of drive force to each unit supported by the support frame 101A.

[0038] The main support 20 and the sub-support 25 are positioned at both ends in the direction of the rotation axis of the drive gears (35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd), and each rotatably supports the rotation axis of the drive gear. The main support 20 has a first support portion 20a that supports one end of the rotation axis of the drive gear, and the sub-support 25 has a second support portion 25a that supports the other end of the rotation axis of the drive gear. The first support portion 20a only needs to support the portion on one end side of the portion where the teeth of the drive gear are formed, and the second support portion 25a only needs to support the portion on the other end side of the portion where the teeth of the drive gear are formed. In this way, the drive gears 35CLa~35CLc,35Ka of the four color photosensitive drums 112Y, 112M, 112C,112K (yellow, magenta, cyan, and black) are supported by the main support 20 and the sub-support 25. This configuration makes it less likely for the inter-axis distance of each color photosensitive drum 112Y, 112M, 112C, and 112K to shift. Therefore, it is possible to suppress the occurrence of color shift when superimposing the images formed on each photosensitive drum onto the intermediate transfer belt 116. In this embodiment, one of the photosensitive drums 112Y, 112M, 112C, and 112K constitutes the first photosensitive drum, and one of the remaining photosensitive drums constitutes the second photosensitive drum. Furthermore, the developing sleeve 114a corresponding to the first photosensitive drum constitutes the first developing sleeve, and the developing sleeve 114a corresponding to the second photosensitive drum constitutes the second developing sleeve.

[0039] In this embodiment, the surfaces supporting the drive gears (35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd) in the first support portion 20a and the second support portion 25a are on the same plane. However, either one or both of the first support portion 20a and the second support portion 25a may have irregularities or steps.

[0040] These main support 20 and sub-support 25 are arranged and connected so as to sandwich the drive gears (35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd). In this embodiment, the main support 20 has a larger area and higher rigidity than the sub-support 25. Therefore, in this embodiment, in order to connect the main support 20 and the sub-support 25, the sub-support 25 is fastened to the main support 20 by screws 40 (distinguished from screws 41 for fastening the main body, see Figure 5) as fastening members. The sub-support 25 is positioned upstream of the main support 20 in the fastening direction (insertion direction, arrow X direction in Figure 4) from which the screws 40 are fastened.

[0041] The main support 20 has out-of-plane fastening holes 560 and in-plane fastening holes 570 formed in the first support portion 20a for fastening screws 40. On the other hand, the sub-support 25 has out-of-plane mounting portions 260a to 260d and in-plane mounting portions 270a to 270c formed for inserting and attaching screws 40. The out-of-plane fastening holes 560 and in-plane fastening holes 570 of the main support 20, and the out-of-plane mounting portions 260a to 260d and in-plane mounting portions 270a to 270c of the sub-support 25 will be described later (see Figures 5 and 6).

[0042] <About metal powders> By the way, when connecting components such as the main support 20 and sub-support 25 mentioned above using screws, metal powder (foreign matter) generated during screw fastening may fall into the drive unit. In conventional drive units, the fallen metal powder adheres to the drive gears (35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd) located inside the drive unit, causing image defects such as banding and abnormal noises from the drive gears. Here, the metal powder generated during screw fastening will be explained using Figures 7(a) and 7(b). Figure 7(a) shows the screw 40 before insertion into the fastening hole 579, and Figure 7(b) shows the screw 40 after insertion into the fastening hole 579.

[0043] Generally, when fastening and connecting members with a screw 40, there are two methods: one in which the screw 40 is inserted into a pre-tapped fastening hole 579 and fastened, and another in which the screw 40 itself taps the hole while fastening. When the fastening hole 579 is pre-tapped, as shown in Figure 7(a), metal powder (e.g., aluminum powder or iron powder) generated as shavings when tapping may remain in the fastening hole 579. In that case, as shown in Figure 7(b), when the screw 40 is inserted into the fastening hole 579 formed in the other member through the mounting hole 279 formed in one member, the metal powder remaining in the fastening hole 579 is pushed out by the screw 40 and falls downward in the direction of gravity. On the other hand, when the screw 40 itself taps the hole while connecting members, some of the metal powder generated as shavings when tapping is pushed out from the fastening hole 579 through which the screw 40 has penetrated and falls downward in the direction of gravity. As described above, in any of the cases, metal powder (foreign matter) may be generated in the fastening hole 579 when the screw 40 is fastened, and this is moved downstream by the screw 40 in the fastening direction (intrusion direction) and eventually pushed out of the fastening hole 579.

[0044] <Conventional Example> As previously mentioned, in conventional drive systems, metal powder pushed out from the fastening hole 579 adheres to the drive gear, causing image defects and abnormal noise. Figures 8(a) and 8(b) show a conventional drive system 90A. Figure 8(a) is a view of the conventional drive system 90A from the sub-support 250 side, and Figure 8(b) is a cross-sectional view of the conventional drive system 90A.

[0045] As shown in Figure 8(a), in the case of the conventional drive unit 90A, a screw 40 for connecting the sub-support 250 to the main support 210 is attached to the second support portion 251. To do this, the sub-support 250 has a mounting hole 271 for attaching the screw 40 to the second support portion 251.

[0046] On the other hand, as shown in Figure 8(b), the main support 210 has a mounting portion 222 extending from the first support portion 211 toward the upstream side in the direction of fastening the screw 40 (arrow X direction) so as to abut against the second support portion 251. The mounting portion 222 has a fastening hole 571 for fastening the screw 40 at a position that overlaps with the mounting hole 271 in the abutment portion that abuts against the second support portion 251.

[0047] As can be seen from Figure 8(b), in the case of the conventional drive unit 90A, the tip of the screw 40 (more specifically, the tip of the threaded portion) protrudes from the downstream side of the fastening hole 571 in the fastening direction. This is because, with the main support 210 and the sub-support 250 connected, when viewed from the direction of gravity, the downstream end of the fastening hole 571 in the fastening direction (the back side of the fastening portion) is in a position that overlaps with the drive gear (for example, 35Ka) located between the first support portion 211 and the second support portion 251.

[0048] Therefore, when the screw 40 is fastened, the metal powder is pushed out from the fastening hole 571 as it moves downstream in the fastening direction, and the metal powder falls onto the drive gear 35Ka and adheres to the gear tooth surface of the drive gear 35Ka. Then, when the drive gear 35Ka rotates and meshes, the metal powder gets stuck. When this happens, the metal powder causes rotational fluctuations in the drive gear 35Ka, which in turn causes rotational fluctuations in the black photosensitive drum 112K (see Figure 2) driven via the drive gear 35Ka, resulting in the image defects and abnormal noises described above.

[0049] Therefore, to prevent metal powder pushed out from the fastening hole 571 during fastening with the screw 40 from adhering to the drive gear, it is conceivable to change the fastening position between the main support 210 and the sub-support 250. Figures 9(a) and 9(b) show a comparative example drive device 90B. The drive device 90B shown in Figures 9(a) and 9(b) is the same as the main support device 90B except for the fastening direction (insertion direction) of the screw 40. Figure 9(a) shows the case where the screw 40 is fastened from the sub-support 250 side toward the main support 210 side (fastening direction is arrow X), and Figure 9(b) shows the case where the screw 40 is fastened from the main support 210 side toward the sub-support 250 side (fastening direction is arrow Y).

[0050] In the comparative example shown in Figures 9(a) and 9(b), the main support 210 and the sub-support 250 are connected by a screw 40, with the sub-support 250 acting as a lid over the main support 210. To achieve this, the main support 210 has a fastening portion 500 that is bent outward at a position outside the projection plane of the second support portion 251, which is obtained by projecting the first support portion 211 in the direction of the rotation axis of the drive gear (not shown) (outside the outer circumference of the first support portion 211). In this case, even if metal powder is pushed out from the fastening hole 571 when fastening with the screw 40, the metal powder does not enter the drive device 90B and therefore does not adhere to the drive gear.

[0051] However, in the comparative example, in addition to the fixing portion 55 (see Figure 2) for fixing the drive unit 90B to the rear plate 10, a fastening portion 500 is formed on the outer circumference of the main support 210, which makes the drive unit 90B larger. Furthermore, in order to avoid the screws 40 fastened to the fastening portion 500, the rear plate 10 needs to have a retraction hole 255 to avoid the screws 40, in addition to the fastening hole for fastening the screws 41 that are attached via the fixing portion 55. In other words, the rear plate 10 needs to have space to form the retraction hole 255 to avoid the screws 40, and also needs to have sufficient strength, which makes the drive unit 90B larger and increases the cost.

[0052] Furthermore, when the support on the side having the fastening hole is made of thin sheet metal, the fastening hole 571 is generally formed in a burring shape as shown in Figure 7(a). In this case, a sufficient distance must be maintained between the fastening hole 571 and the bending position of the fastening portion 500 of the main support 210. This is because if the burring-shaped fastening hole 571 is close to the bending position, the positional accuracy will decrease due to the pulling caused by the bending when the fastening portion 500 is bent to form the fastening portion 500. If it is to be placed close to the bending position, it is necessary to provide a hole called a bend relief at the base of the bend. Therefore, if the fastening hole 571 is placed far enough away from the bending position, the drive device 90B will become larger, but if it is placed close, a hole will be made at the base of the bend, and metal powder generated during fastening by the screw 40 may enter the drive device 90B from there.

[0053] To prevent metal powder from entering the drive unit 90B through the hole drilled at the base of the bend, it is conceivable to fasten the screw 40 from the main support 210 side toward the sub-support 250 side, as shown in Figure 9(b). However, as in the case of Figure 9(a), in order to avoid the screw 40 fastened to the fastening part 500, it is necessary to form a retraction hole 255 in the rear plate 10 to avoid the screw 40, which may result in a larger drive unit 90B and higher costs. Furthermore, when an operator removes the drive unit 90B, there is a risk of mistakenly removing the screw 40 connecting the main support 210 and the sub-support 250 instead of the screw 41 (see Figure 3) that attaches the drive unit 90B to the rear plate 10 via the fixing part 55. In other words, it is difficult for an operator to know which screw to remove in order to remove the drive unit 90B from the rear plate 10, resulting in poor workability during maintenance.

[0054] <Regarding the fastening configuration in this embodiment> Next, considering the problems of the conventional and comparative examples described above, the fastening configuration of the main support 20 and the sub-support 25 using screws 40 in this embodiment will be explained with reference to Figures 4 to 6.

[0055] As shown in Figure 5, the first support portion 20a of the main support 20 has an in-plane fastening hole 570 for fastening a screw 40, and the sub-support 25 has in-plane mounting portions 270a to 270c for inserting and attaching the screw 40. The in-plane fastening hole 570 of the main support 20 is formed in the projection plane obtained by projecting the second support portion 25a of the sub-support 25 in the direction of the rotation axis of the drive gear (35CLa to 35CLc, 35Ka to 35Ke, 35Sa to 35Sc, 35Ga to 35Gd, see Figure 4) onto the first support portion 20a. The projection plane of the second support portion 25a is the projection plane obtained by projecting the outer circumference, which is represented by connecting the outermost edges of the surface of the second support portion 25a that supports the drive gear (35CLa to 35CLc, 35Ka to 35Ke, 35Sa to 35Sc, 35Ga to 35Gd), and is the region shown by the dashed line in Figures 4 and 5.

[0056] On the other hand, as shown in Figure 6, the in-plane mounting portion of the sub-support 25 (represented here as 270b) extends from the second support portion 25a downstream in the direction of fastening the screw 40 (towards the first support portion 20a) so as to abut the first support portion 20a in the projection plane. The in-plane mounting portion 270b has an in-plane mounting hole 27 formed at a position that overlaps with the in-plane fastening hole 570 of the main support 20 in the abutment portion 220 that abuts the first support portion 20a, for inserting and attaching the screw 40. These in-plane mounting portions 270a to 270c are flange portions formed by cutting a part of the second support portion 25a and bending it toward the main support 20 side (first support side), as shown in Figure 4.

[0057] As shown in Figure 6, the main support 20 is fixed to the rear plate 10 (support frame) of the support frame 101A (see Figure 1) with the sub-support 25 facing the rear plate 10 (support frame). When the main support 20 and the sub-support 25 are connected, the tip of the screw 40 (more specifically, the tip of the threaded portion) protrudes from the downstream side of the in-plane fastening hole 570 in the fastening direction. However, in this embodiment, when the main support 20 and the sub-support 25 are connected, the downstream end of the in-plane fastening hole 570 in the fastening direction (the back side of the fastening portion) is located in a position that does not overlap with the space 37 sandwiched between the first support portion 20a and the second support portion 25a, as viewed from the direction of gravity. That is, it is located outside the drive device 90, and does not overlap with each drive gear (for example, drive gear 35CLb) located between the first support portion 20a and the second support portion 25a. Therefore, as described above, even if metal powder is pushed out from the in-plane fastening hole 570 as it moves downstream in the fastening direction due to fastening with the screw 40, the metal powder does not fall onto the drive gear 35CLb. Consequently, the metal powder generated as a result of fastening with the screw 40 cannot adhere to the drive gear 35CLb, and thus the image defects and abnormal noises described above do not occur. Furthermore, in this embodiment, since it is not necessary to secure a new space on the main support 20 for contacting and fixing the in-plane mounting portions 270a to 270c of the sub-support 25 in the direction of gravity, this can be achieved without increasing the size of the drive device 90.

[0058] Furthermore, in this embodiment, the main support 20 has an out-of-plane fastening hole 560 formed outside the projection plane of the first support portion 20a for fastening a screw 40, as shown in Figures 4 and 5. On the other hand, the sub-support 25 has out-of-plane mounting portions 260a to 260d extending from the second support portion 25a toward the downstream side (first support portion 20a side) in the direction of fastening the screw 40, so as to abut the first support portion 20a outside the projection plane. The out-of-plane mounting portions 260a to 260d have out-of-plane mounting holes 261 formed therein for inserting and attaching the screw 40. In other words, in this embodiment, in order to fix the sub-support 25 more firmly to the main support 20, it can also be fixed by the out-of-plane mounting portions 260a to 260d which are provided in a different location from the in-plane mounting portions 270a to 270c. These out-of-plane mounting portions 260a to 260d and in-plane mounting portions 270a to 270c are positioned inward from the outer circumference of the first support portion 20a so as to abut the first support portion 20a of the main support 20.

[0059] In this embodiment, the relative positioning of the main support 20 and the sub-support 25 is performed by the in-plane mounting portions 270 provided at three locations, thereby suppressing misalignment that occurs when the screws 40 are fastened. In this embodiment, as an example, as shown in Figures 4 and 5, the left-right positioning is performed at one location and the up-down positioning is performed at two locations. However, this is not limited to this, and in-plane mounting portions 270 may be formed at a total of two locations: one location for up-down and left-right positioning and one location for rotation prevention. Furthermore, if the sub-support 25 can be firmly fixed to the main support 20, additional in-plane mounting portions (270) may be provided instead of the out-of-plane mounting portions 260a to 260d. In such a case, it is not necessary to secure new space in the width direction intersecting the direction of gravity to fix the sub-support 25 to the main support 20, so the drive device 90 can be made smaller.

[0060] Furthermore, as shown in Figure 6, the back side of the fastening portion of the fixing part 55 for fixing to the rear plate 10 is located on the opposite side of the rear plate 10 from the drive device 90, so metal powder generated by fastening with the screw 41 does not adhere to the drive gear.

[0061] As described above, in this embodiment, the in-plane mounting portions 270a to 270c extending from the sub-support 25 are brought into contact with the main support 20 and fastened with screws 40 from the sub-support 25 side toward the main support 20 side. In this way, as described above, the downstream end (back side of the fastening portion) of the in-plane fastening hole 570 is located outside the drive device 90, so metal powder generated by fastening with screws 40 cannot adhere to the drive gear, and the image defects and abnormal noises described above do not occur.

[0062] <Other Embodiments> In the above-described embodiment, an intermediate transfer type image forming apparatus 101 was explained as an example, in which toner images are first transferred from each color photosensitive drum 112Y to 112K to an intermediate transfer belt 116, and then the toner images are secondarily transferred from the intermediate transfer belt 116 to the recording material S. However, the embodiment is not limited to this. The above-described embodiment is also applicable to a direct transfer type image forming apparatus in which toner images are directly transferred from each color photosensitive drum 112Y to 112K, which carry and rotate the toner images, to the recording material S. [Explanation of Symbols]

[0063] 10...Support frame (rear side plate), 20...First support (main support), 20a...First support part, 25...Second support (sub support), 25a...Second support part, 27...Mounting hole (in-plane mounting hole), 30CL, 30K, 30S, 30Ga~30Gd...Drive source (motor), 35CLa~35CLc, 35Ka~35Ke, 35Sa~35Sc, 35Ga~35Gd...Drive gear, 40 ...Fastening member (screw), 101...Image forming apparatus, 112...Rotating body (photosensitive drum), 114a...Rotating body (developing sleeve), 116a...Rotating body (double turn roller, secondary transfer inner roller), 260...Other mounting part (out-of-plane mounting part), 261...Other mounting hole (out-of-plane mounting hole), 270...Mounting part (in-plane mounting part), 560...Other fastening hole (out-of-plane fastening hole), 570...Fastening hole (in-plane fastening hole), S...Recording material

Claims

1. In an image forming apparatus that forms an image on a recording material, A solid of rotation and The system includes a drive device for driving the rotating body, The drive device is Power source and A plurality of drive gears that transmit the driving force of the drive source to the rotating body, A first support body having a first support portion that holds the drive source and supports one end of the rotation shaft of the drive gear in the direction of the rotation axis of the drive gear, The second support has a second support portion that supports the other end of the rotating shaft and is connected to the first support by a fastening member, The first support has fastening holes formed in a projection plane obtained by projecting the second support portion in the direction of the rotation axis of the drive gear, into which the fastening member is fastened. The second support is positioned upstream of the first support in the fastening direction for fastening the fastening member, The second support has a mounting portion that extends downstream in the fastening direction so as to abut against the first support portion, In the contact portion of the mounting portion that abuts against the first support portion, a mounting hole is formed at a position overlapping with the fastening hole into which the fastening member is inserted. An image forming apparatus characterized by the following:

2. The mounting portion is formed by cutting out a part of the second support portion and bending it toward the first support portion. The image forming apparatus according to feature 1.

3. The system further comprises a support frame that supports the aforementioned rotating body, The first support is fixed to the support frame with the second support facing the support frame. The image forming apparatus according to claim 1 or 2.

4. The first support has higher rigidity than the second support. The image forming apparatus according to any one of claims 1 to 3.

5. The first support has other fastening holes provided outside the projection plane into which fastening members are fastened. The second support extends downstream from the second support in the fastening direction so as to abut the first support outside the projection plane, and has another mounting portion provided at a position overlapping with other fastening holes of the first support, and having another mounting hole formed therein into which the fastening member is fastened. The image forming apparatus according to any one of claims 1 to 4.

6. The drive source drives one or more of the rotating bodies via the drive gear. The image forming apparatus according to any one of claims 1 to 5.

7. The rotating body is a photosensitive drum that rotates while carrying a toner image. The image forming apparatus according to any one of claims 1 to 6.

8. The rotating body is a developing sleeve that carries toner and rotates in order to develop a toner image on the photosensitive drum. The image forming apparatus according to any one of claims 1 to 6.

9. The rotating body is a two-transfer roller that forms a nip section for secondary transfer of the toner image from the intermediate transfer belt, which has primary transferred the toner image formed on the photosensitive drum, to the recording material. The image forming apparatus according to any one of claims 1 to 6.

10. The rotating body is a first photosensitive drum that carries and rotates a toner image. The drive gear has a coupling that transmits the driving force from the drive source to the first photosensitive drum. A first developing sleeve for developing the electrostatic latent image formed on the first photosensitive drum using toner, A second photosensitive drum, which is different from the first photosensitive drum, A second developing sleeve that develops the electrostatic latent image formed on the second photosensitive drum using a toner of a different color than that of the first developing sleeve, The second photosensitive drum further comprises another drive gear having a coupling for transmitting driving force from the drive source, The other drive gear is supported by the first support and the second support. The image forming apparatus according to any one of claims 1 to 9.

11. The rotating body is a first photosensitive drum that carries and rotates a toner image. The drive gear has a coupling that transmits the driving force from the drive source to the first photosensitive drum. A first developing sleeve for developing the electrostatic latent image formed on the first photosensitive drum using toner, A second photosensitive drum, which is different from the first photosensitive drum, A second developing sleeve that develops the electrostatic latent image formed on the second photosensitive drum using a toner of a different color than that of the first developing sleeve, A different drive source from the aforementioned drive source, The second photosensitive drum further comprises another drive gear having a coupling for transmitting driving force from the other drive source, The other drive gear is supported by the first support and the second support. The image forming apparatus according to any one of claims 1 to 9.

12. The drive source is fixed to the outside of the drive gear housing space formed by the first support and the second support. The image forming apparatus according to any one of claims 1 to 11.

Images