Drive Unit and Image Forming Apparatus

Abstract

To suppress vibration of driving frames to reduce noise while maintaining the flatness of the driving frames.SOLUTION: An image forming apparatus includes a driving unit that applies driving force to a rotating body. The image forming apparatus comprises: a driving gear having a shaft joint; a first driving frame having a first through-hole that holds a shaft joint side of the driving gear; a second driving frame disposed to face the first driving frame and having a second through-hole that holds a side opposite to the shaft joint side of the driving gear; a first driving frame wall portion that is provided in a region including a straight line passing through a center of the first through-hole and extends in an axial direction from the first driving frame toward the second driving frame; and a second driving frame wall portion that is provided in the region including the straight line, extends in the axial direction from the second driving frame toward the first driving frame, and is provided to face the first driving frame wall portion with a gap between the driving frame wall portions. An elastic member is compressed and held in a gap between the first driving frame wall portion and the second driving frame wall portion in a region including the straight line.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus having a drive unit that applies a driving force to a rotating body. [Background technology]

[0002] In recent years, there has been a strong demand for quieter image forming devices such as copiers and printers. Image forming devices are equipped with drive units that provide driving force to rotating bodies such as photosensitive drums, and operation noise is generated by the operation of motors, fans, etc. during image formation.

[0003] The operating noise of the drive unit that provides driving force to the photosensitive drum, developing roller, and intermediate transfer belt accounts for a large proportion of the operating noise of the entire image forming apparatus because the motor rotates at a high speed and the gears rotate in mesh. The gears and motor that make up the drive unit are held in a drive frame that constitutes the housing of the drive unit. When making the drive unit quieter, it is important to suppress the vibration of the flat parts that take up a large area of ​​the drive frame.

[0004] In Patent Document 1, the vibrating members, the motor and the drive shaft, are held by separate holding members, so that the vibrations of the motor and the drive shaft do not vibrate synchronously with each holding member, thereby reducing the vibration of both members.

[0005] In Patent Document 2, a heavy object that is a part of the components of the image forming apparatus is fixed to a frame part of the drive unit, thereby increasing the weight and rigidity of the entire drive unit and suppressing vibration. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-116316 A [Patent Document 2] JP 2005-31447 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Document 2, since a heavy object is fixed to the frame part of the drive unit, the flatness of the frame part may deteriorate. If the flatness of the frame part deteriorates, the parallelism (alignment) of the gears held by the frame part may deteriorate, and the operating noise may increase.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to reduce the noise generated by a drive unit by suppressing vibration of the drive frame while maintaining the flatness of the drive frame that constitutes the housing of the drive unit. [Means for solving the problem]

[0009] A representative configuration of the present invention for achieving the above object is an image forming apparatus having a drive unit for applying a driving force to a rotating body, the drive unit including a drive gear having a shaft coupling that engages with the rotating body to transmit the driving force to the rotating body, a first drive frame having a first through hole that holds the shaft coupling side of the drive gear, a second drive frame disposed opposite to the first drive frame and holding the side opposite to the shaft coupling side of the drive gear, the second drive frame having a second through hole positioned coaxially with the first through hole, and a second drive frame extending from an end of a flat portion of the first drive frame having the first through hole toward the second drive frame, the second drive frame being disposed in an area including a straight line in a second direction that passes through the center of the first through hole and is perpendicular to a straight line in a first direction that passes through the center of the first through hole, the second drive frame being extended from the end of the flat portion of the first drive frame having the first through hole toward the second drive frame. and a second drive frame wall portion provided in an area including a straight line in a second direction passing through the center of the first through hole and perpendicular to a straight line in a first direction passing through the center of the first through hole, the second drive frame wall portion extending in the axial direction from an end of the planar portion of the second drive frame in which the second through hole is provided toward the first drive frame, and provided opposite the first drive frame wall portion across a gap in the second direction perpendicular to the axial direction, and an elastic member having a thickness greater than a dimension of the gap is compressed and held in the gap between the first drive frame wall portion and the second drive frame wall portion in the area including the straight line in the second direction passing through the center of the first through hole. Effect of the Invention

[0010] According to the present invention, it is possible to suppress vibration of the drive frame while maintaining the flatness of the drive frame, thereby making the drive unit quieter. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] Diagram showing the relative positions of the base frame and the drive unit [Diagram 3] (a)(b) Diagram showing how the drive unit is held [Figure 4] 1A and 1B are diagrams illustrating insertion and removal of an intermediate transfer unit into and from an image forming apparatus. [Diagram 5] 1A and 1B are diagrams showing insertion and removal of a photosensitive drum into and from an image forming apparatus; [Figure 6] (a)(b)(c) Schematic diagram of the drive unit [Figure 7] FIG. 1 shows a first drive frame. [Figure 8] FIG. 2 shows a second drive frame. [Figure 9] Diagram of the gear train of the drive unit [Figure 10] FIG. 13 is an explanatory diagram of a first drive frame wall portion and a second drive frame wall portion facing each other; [Figure 11] FIG. 1 is a diagram showing an area where an elastic member is provided in a drive unit; [Figure 12] An explanatory diagram of an elastic member provided on a drive frame wall. [Figure 13] A diagram showing the measurement results of the noise reduction effect of elastic members. [Figure 14] FIG. 1 is a diagram showing an area where an elastic member is provided in a drive unit; [Figure 15] FIG. 11 is a cross-sectional view showing a state in which the elastic member is folded back and provided on the drive frame wall portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following embodiments may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention to these alone.

[0013] <Image forming device> The image forming apparatus of this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the general configuration of the image forming apparatus of this embodiment.

[0014] 1 is an intermediate transfer tandem type color image forming apparatus in which image forming units PY, PM, PC, and PK for four colors (yellow, cyan, magenta, and black) are arranged inside the apparatus body to face an intermediate transfer belt 8. Examples of recording materials S that can be used with the image forming apparatus 100 include various types of sheet materials such as plain paper, thick paper, rough paper, textured paper, coated paper, and the like, OHP sheets, plastic films, and cloth. The image forming apparatus 100 is controlled by a control unit 500.

[0015] The image forming apparatus 100 includes image forming sections PY to PK that form toner images on the photosensitive drums 1, an intermediate transfer unit 110 having an intermediate transfer belt 8 that carries the toner images formed on the photosensitive drums 1, and a paper feed section 800 that feeds the recording material S. In this embodiment, the image forming sections PY to PK, the primary transfer rollers 5Y to 5K, the intermediate transfer belt 8, the secondary inner transfer roller 76, and the secondary outer transfer roller 77 constitute an image forming unit 120 that forms a toner image on the recording material S. The intermediate transfer unit 110 is composed of the intermediate transfer belt 8, which is an endless belt, a tension roller 10 that stretches the intermediate transfer belt 8, the secondary inner transfer roller 76, and idler rollers 7a and 7b. The paper feed section 800 is composed of a cassette 72, a paper feed roller 73, a conveying path 74, and a registration roller 75.

[0016] As shown in Fig. 2, the image forming apparatus 100 includes a base frame 300 as a main body frame. The base frame 300 includes a front base frame 301, a rear base frame 302, a left base frame 303, and a right base frame 304.

[0017] The front base frame 301 is located on the front side in the front-rear direction of the image forming apparatus 100, and the rear base frame 302 is located on the rear side. The rear base frame 302 is disposed so as to face the front base frame 301 in the front-rear direction.

[0018] The left base frame 303 is located on the left side in the left-right direction perpendicular to the front-rear direction of the image forming apparatus 100, and the right base frame 304 is located on the right side. The right base frame 304 is disposed so as to face the left base frame 303 in the left-right direction. The left base frame 303 and the right base frame 304 are attached to the front base frame 301 and the rear base frame 302, respectively.

[0019] In the following description, the base frame front 301 side of the image forming apparatus 100 is defined as the front side (near side or front side), and the base frame rear 302 side is defined as the rear side (rear side or back side). The base frame left 303 side is defined as the left side, and the base frame right 304 side is defined as the right side. In other words, when the image forming unit PK that forms a black toner image is used as a reference, the side where the image forming unit PY that forms a yellow toner image is arranged is defined as the left side. When the image forming unit PY that forms a yellow toner image is used as a reference, the side where the image forming unit PK that forms a black toner image is arranged is defined as the right side. Furthermore, the direction perpendicular to the front-rear and left-right directions defined here and vertically upward is defined as the up direction, and the direction perpendicular to the front-rear and left-right directions defined here and vertically downward is defined as the down direction. The defined front, rear, right, left, up, and down directions are shown in FIG. 4 and FIG. 5.

[0020] Image forming units PY to PK, intermediate transfer unit 110, paper feed unit 800, etc. are arranged in a space formed by base frame 300. An exterior member (not shown) that forms the exterior of image forming apparatus 100 surrounds the outer periphery of base frame 300, and is configured to prevent sound generated when image forming apparatus 100 is operating from reaching the outside of the apparatus.

[0021] The image forming apparatus 100 includes a drive unit 20 that rotates and drives the image forming units PY to PK and the intermediate transfer unit 110. The drive unit 20 is disposed behind the image forming units PY to PK and the intermediate transfer unit 110 via a rear base frame 302. As will be described later, the drive unit 20 is attached to the rear side of the rear base frame 302.

[0022] The conveying process of the recording material S of the image forming apparatus 100 will be described. The recording material S is stored in a cassette 72 in a stacked form, and is fed one by one to a conveying path 74 by a paper feed roller 73 in accordance with the image formation timing. Alternatively, the recording material S loaded on a manual feed tray or a loading device (not shown) may be fed one by one to the conveying path 74. When the recording material S is conveyed to a registration roller 75 arranged in the middle of the conveying path 74, the registration roller 75 corrects the skew and timing of the recording material S, and then the recording material S is sent to a secondary transfer portion T2. ​​The secondary transfer portion T2 is a transfer nip portion formed by an opposing secondary transfer inner roller 76 and secondary transfer outer roller 77. In the secondary transfer portion T2, a toner image is secondarily transferred from the intermediate transfer belt 8 to the recording material S.

[0023] The process of forming an image sent to the secondary transfer portion T2 at the same timing as the process of conveying the recording material S to the secondary transfer portion T2 will be described. First, the image forming portions PY to PK will be described. However, the image forming portions PY to PK are configured almost identically except that the colors of the toner used in the developing devices 4Y, 4M, 4C, and 4K are different, that is, yellow, magenta, cyan, and black. Therefore, the following description will be given by exemplifying the yellow image forming portion PY as a representative, and the description of the other image forming portions PM, PC, and PK will be omitted. For convenience of illustration, the reference numerals are given only to the image forming portion PY with respect to the developing container 41Y and developing roller 42Y described later.

[0024] The image forming section PY is mainly composed of a photosensitive drum 1Y as an image carrier, a charging device 2Y as a process means acting on the photosensitive drum 1Y, a developing device 4Y, a photosensitive drum cleaner 6Y, and the like. During image formation, the photosensitive drum 1Y is rotated in the direction of the arrow R1 at a predetermined process speed (circumferential speed). A charging voltage is applied to the charging device 2Y by a high-voltage power source (not shown), and a current flows between the charging device 2Y (charging roller) and the photosensitive drum 1Y, so that the surface of the photosensitive drum 1Y is uniformly charged to a predetermined polarity and potential. After charging, the photosensitive drum 1Y is exposed by the exposure device 3 based on image information to form an electrostatic latent image. This electrostatic latent image is developed into a toner image by the developing device 4Y, with toner attached thereto. The developing device 4Y has a developing container 41Y containing a developer, and a developing roller 42Y (also called a developing sleeve) that rotates while carrying the developer, and the electrostatic latent image is developed into a toner image by applying a developing voltage to the developing roller 42Y. Thereafter, a predetermined pressure and a primary transfer voltage are applied by a primary transfer roller 5Y disposed opposite the image forming portion PY with the intermediate transfer belt 8 interposed therebetween, and the toner image formed on the photosensitive drum 1Y is primarily transferred onto the intermediate transfer belt 8. A small amount of residual toner remaining on the photosensitive drum 1Y after the primary transfer is removed by a photosensitive drum cleaner 6Y, and the toner image is prepared for the next image forming process.

[0025] The intermediate transfer belt 8 is tensioned by a tension roller 10, a secondary transfer inner roller 76, and idler rollers 7a and 7b as tension rollers, and is driven to move in the direction of the arrow R2 in the figure. In the case of this embodiment, the secondary transfer inner roller 76 also serves as a drive roller (rotating body) that drives the intermediate transfer belt 8. The image forming process of each color processed by the above-mentioned image forming units PY to PK is performed at a timing to sequentially superimpose on the toner image of the color upstream in the movement direction that has been primarily transferred onto the intermediate transfer belt 8. As a result, a full-color toner image is finally formed on the intermediate transfer belt 8 and is transported to the secondary transfer unit T2. Note that the transfer residual toner after passing through the secondary transfer unit T2 is removed from the intermediate transfer belt 8 by a transfer cleaner device 11.

[0026] Through the conveying process and image forming process described above, the timing of the recording material S and the full-color toner image are synchronized at the secondary transfer portion T2, and the toner image is secondarily transferred from the intermediate transfer belt 8 to the recording material S. Thereafter, the recording material S is conveyed to the fixing device 103, and the toner image is melted and fixed onto the recording material S by applying pressure and heat by the fixing device 103. The recording material S with the toner image fixed in this manner is discharged onto the discharge tray 601 by the discharge rollers 78.

[0027] <Inserting and removing the intermediate transfer unit> Next, the insertion and removal of the intermediate transfer unit 110 in this embodiment will be described with reference to Figures 4(a) and 4(b). Figure 4(a) is a schematic perspective view showing the intermediate transfer unit 110. Note that in Figure 4(a), a portion of the front side of the intermediate transfer belt is cut away. Figure 4(b) is a perspective view showing the intermediate transfer unit 110 in a state where it is mounted in an image forming apparatus.

[0028] The intermediate transfer unit 110 is supported so as to be insertable and removable from the image forming apparatus 100. The intermediate transfer unit 110 is provided with a coupling 121, which is a shaft joint, at the rear side of the secondary transfer inner roller (drive roller) 76 in order to connect and disconnect the driving force from the drive unit 20 when the intermediate transfer unit 110 is inserted and removed. In this embodiment, the coupling 121 is manufactured by injection molding a resin material. In addition, a release member 150, which will be described in detail later, is provided near the coupling 121 and which is capable of retracting a drive gear 253 (see FIG. 9) from the drive unit 20 in the thrust direction.

[0029] The image forming apparatus 100 is provided with a right door 13 that opens and closes the right side of the image forming apparatus 100 so as to divide the conveyance path of the recording material S from the paper feed roller 73 to the fixing device 103. The right door 13 is opened to insert and remove the intermediate transfer unit 110. When removing the intermediate transfer unit 110 from the image forming apparatus 100, the release member 150 is operated to retract the drive gear 253 of the drive unit 20, and the intermediate transfer unit 110 is pulled out to the right side of the image forming apparatus 100. Conversely, the intermediate transfer unit 110 can be attached to the image forming apparatus 100 by pushing the intermediate transfer unit 110 to the left side of the image forming apparatus 100. A rail 14 that supports the intermediate transfer unit 110 is attached to the image forming apparatus 100. The intermediate transfer unit 110 is guided by rails 14 and can be inserted into and removed from the image forming apparatus 100 by moving in a left-right direction (substantially horizontal direction) perpendicular to the front-rear direction of the image forming apparatus 100 .

[0030] <Inserting and removing the photosensitive drum> Next, the insertion and removal of the photosensitive drum in this embodiment will be described with reference to Fig. 5(a) and Fig. 5(b). Fig. 5(a) is a schematic perspective view showing the photosensitive drum 1. Fig. 5(b) is a schematic perspective view showing the photosensitive drum 1 in a state where it is mounted in the image forming apparatus 100.

[0031] Like the intermediate transfer unit 110, the photosensitive drum 1 is supported so as to be insertable and removable from the image forming apparatus 100. To connect and disconnect the driving force from the drive unit 20 when the photosensitive drum 1 is inserted and removed, a drum coupling 122, which is a shaft coupling on the driven side, is provided on the rear side of the photosensitive drum 1. In this embodiment, the drum coupling 122 is manufactured by injection molding a resin material.

[0032] The photosensitive drum 1 is inserted or removed by opening a front cover 15 provided on the front side of the image forming apparatus 100. When removing the photosensitive drum 1 from the image forming apparatus 100, the photosensitive drum 1 is pulled out to the front side of the image forming apparatus 100. Conversely, the photosensitive drum 1 can be attached to the image forming apparatus 100 by pushing the photosensitive drum 1 toward the back side of the image forming apparatus 100. Note that a drum rail 16 that supports the photosensitive drum 1 is attached to the image forming apparatus 100. The photosensitive drum 1 is guided by the drum rail 16 and moves in the front-to-rear direction (approximately horizontal direction) of the image forming apparatus 100, making it possible to insert or remove the photosensitive drum 1 from the image forming apparatus 100.

[0033] <Drive unit installation configuration> Next, how the drive unit 20 is attached to the base frame 300 will be described with reference to FIGS.

[0034] 2 is a schematic diagram of the base frame 300 to which the drive unit 20 is attached, as seen from above. Other units attached to the base frame 300 are not shown. The front base frame 301 is located on the front side in the front-rear direction of the image forming apparatus 100, and the rear base frame 302 is located on the rear side. The rear base frame 302 is disposed so as to face the front base frame 301, and the left base frame 303 and the right base frame 304 are attached to the front base frame 301 and the rear base frame 302, respectively. The drive unit 20 is located behind the image forming unit 120, and a second drive frame 202, which will be described later, is attached to the rear base frame 302 of the apparatus main body.

[0035] FIG. 3(a) is a view of the base frame 300 to which the drive unit 20 is attached, seen from the rear. In FIG. 3(a), units other than the drive unit are omitted, as in FIG. 2. FIG. 3(b) is a view of the vicinity of the drive unit 20 seen from the rear of the base frame 300. As shown in FIG. 3(a) and FIG. 3(b), the second drive frame 202 of the drive unit 20 faces the rear base frame 302, and has drive unit fixing screw holes 203, which are mounting holes for screws for fixing the drive unit 20. Here, the second drive frame 202 has two drive unit fixing screw holes 203 on each of the top, bottom, left and right. The drive unit 20 is fixed to the rear base frame 302 by mounting screws in the drive unit fixing screw holes 203.

[0036] <Drive unit configuration> Next, the configuration of the drive unit 20 according to this embodiment will be described with reference to Fig. 6. Fig. 6(a) is a perspective view of the drive unit as seen from the front. Fig. 6(b) is a view of the drive unit as seen from the rear. Fig. 6(c) is a cross-sectional view of the drive unit 20.

[0037] The drive unit 20 is a drive unit that applies a driving force to a rotating body. Here, the rotating body is exemplified as the photosensitive drums 1 (1Y, 1M, 1C, and 1K).

[0038] 6(a) and 6(b), the drive unit 20 includes a first drive frame 201 made of steel plate and a second drive frame 202 also made of steel plate. The first drive frame 201 and the second drive frame 202 are fastened to each other by screws at a drive frame fastening portion 280. In other words, the first drive frame 201 and the second drive frame 202 form a housing of the drive unit 20.

[0039] Also, as shown in FIG. 6(c), the first drive frame 201 is positioned forward of the second drive frame 202 in the front-to-rear direction, and the first drive frame 201 is positioned opposite the second drive frame 202.

[0040] The first drive frame 201 is shown in FIG. 7. FIG. 7 is a view of the first drive frame 201 as seen from the rear of the image forming apparatus. The first drive frame 201 has a plurality of first through holes 206k, 206c, 206m, 206y that hold the shaft coupling sides of the drum drive gears 222, 232c, 232m, 232y that are drive gears for driving the photosensitive drums. Here, the shaft couplings of the drum drive gears 222, 232c, 232m, 232y are main body side drum couplings 222a, 232ac, 232am, 232ay that engage with the photosensitive drum 1 that is a rotating body and transmit driving force to each photosensitive drum 1. The first through holes 206y, 206m, 206c, 206k for the drum drive gears are provided at equal intervals in the left-right direction on the flat surface portion 201a of the first drive frame 201. Similarly, the first drive frame 201 has first developing gear through holes 208y, 208m, 208c, and 208k that hold developing coupling side gears 244y, 244m, 244c, and 244k that are driving gears for driving the developing roller. The first developing gear through holes 208y, 208m, 208c, and 208k are provided at equal intervals in the left-right direction on the flat surface portion 201a of the first drive frame 201. Furthermore, the first drive frame 201 has a first intermediate transfer belt gear through hole 210 that holds the shaft coupling side of the intermediate transfer belt drive gear 253 that is a drive gear for driving the intermediate transfer belt. One first intermediate transfer belt gear through hole 210 is provided on the flat surface portion 201a of the first drive frame 201. Here, the shaft coupling of the intermediate transfer belt drive gear 253 is an intermediate transfer belt coupling 252a which engages with the drive roller (secondary transfer inner roller 76) of the intermediate transfer belt 8 and transmits a drive force to the intermediate transfer belt 8.

[0041] As shown in FIG. 6(b), the drive unit 20 includes a motor that is a drive source that provides a drive force to the drive gear. Specifically, the drive unit 20 includes a black drum motor 220, a color drum motor 230, yellow, magenta, cyan, and black development motors 240y, 240m, 240c, and 240k, and an intermediate transfer belt motor 250. The black drum motor 220 is a drive source that provides a drive force to the black drum drive gear 222. The color drum motor 230 is a drive source that provides a drive force to the yellow drum drive gear 232y, the magenta drum drive gear 232m, and the cyan drum drive gear 232c. The yellow, magenta, cyan, and black development motors 240y, 240m, 240c, and 240k are drive sources that provide a drive force to the development coupling side gears 244y, 244m, 244c, and 244k, respectively. The intermediate transfer belt motor 250 is a drive source that provides a driving force to the intermediate transfer belt drive gear 253. The motors 220, 230, 240y, 240m, 240c, 240k, and 250 that are drive sources are attached to a second drive frame 202 of the drive unit 20.

[0042] The second drive frame 202 is shown in FIG. 8. FIG. 8 is a view of the second drive frame 202 as seen from the rear of the image forming apparatus. The second drive frame 202 has a plurality of second through holes 207k, 207c, 207c, 207y that hold the opposite side of the shaft coupling side of the drum drive gears 222, 232c, 232m, 232y that are drive gears for driving the photosensitive drums. The second through holes 207y, 207m, 207c, 207k for the drum drive gears are provided so as to be positioned coaxially with the first through holes 206y, 206m, 206c, 206k, respectively. The second through holes 207y, 207m, 207c, 207k are provided at equal intervals in the left-right direction on the flat surface portion 202a of the second drive frame 202. Furthermore, the second drive frame 202 has a second intermediate transfer belt gear through hole 211 that holds the side opposite to the shaft coupling side of an intermediate transfer belt drive gear 253, which is a drive gear for driving the intermediate transfer belt. One second intermediate transfer belt gear through hole 211 is provided in the flat surface portion 202a of the second drive frame 202. The second intermediate transfer belt gear through hole 211 is provided so as to be positioned coaxially with the first intermediate transfer belt gear through hole 210.

[0043] <Photosensitive drum driving method> Next, a method for driving the photosensitive drum will be described with reference to Fig. 9. Fig. 9 is a layout diagram of drive gears for driving the photosensitive drum, the developing roller, and the intermediate transfer belt.

[0044] First, a method for driving the black photosensitive drum 1K will be described.

[0045] The drive unit 20 includes a black drum motor 220, a drum motor gear 221, and a drum drive gear 222 to drive the black photosensitive drum 1K. The black drum drive gear 222 has a black main body side drum coupling 222a at the front gear shaft tip. The black main body side drum coupling 222a is formed so as to mesh with the drum coupling 122 (see FIG. 5(a)) provided at the rear end of the photosensitive drum 1K when the black photosensitive drum 1K is mounted on the image forming apparatus 100. The second drive frame 202 holds a black drum gear holding member 223 (FIG. 6(b)). The black drum drive gear 222 is held by the black drum gear holding member 223 so as to be positioned coaxially with the black drum gear holding member 223. A black motor gear 221 is attached to the shaft of the black drum motor 220. The black motor gear 221 is arranged so as to mesh with the black drum drive gear 222. A black drum motor 220 rotates and drives the black photosensitive drum 1K via a black drum motor gear 221, a drum drive gear 222, and a main body side drum coupling 222a.

[0046] Next, a method of driving the color photosensitive drums 1Y, 1M, and 1C will be described.

[0047] The drive unit 20 includes the following motors and gears to drive the photosensitive drums 1Y, 1M, and 1C for yellow, magenta, and cyan. That is, the drive unit 20 includes a color drum motor 230, a color drum motor gear 231, drum drive gears 232y, 232m, and 232c for yellow, magenta, and cyan, and a yellow drum intermediate gear 233. The drum drive gears 232y, 232m, and 232c for yellow, magenta, and cyan have main body side drum couplings 232ay, 232am, and 232ac for yellow, magenta, and cyan at the front gear shaft tips. When the photosensitive drums 1Y, 1M, and 1C for yellow, magenta, and cyan are mounted on the image forming apparatus 100, the main body side drum couplings 232ay, 232am, and 232ac are formed to mesh with the drum couplings 122 (see FIG. 5(a)) provided at the rear ends of the photosensitive drums 1Y, 1M, and 1C for yellow, magenta, and cyan. The second drive frame 202 holds the drum gear holding members 234y, 234m, and 234c for yellow, magenta, and cyan (FIG. 6(b)). The drum drive gears 232y, 232m, and 232c for yellow, magenta, and cyan are held by the drum gear holding members 234y, 234m, and 234c so as to be positioned coaxially with the drum gear holding members 234y, 234m, and 234c for yellow, magenta, and cyan. A color motor gear 231 is attached to the shaft of the color drum motor 230. The color motor gear 231 is disposed so as to mesh with both the magenta drum drive gear 232m and the cyan drum drive gear 232c. The yellow drum intermediate gear 233 is disposed so as to mesh with both the yellow drum drive gear 232y and the magenta drum drive gear 232m. The color drum motor 230 drives and rotates the photosensitive drums 1Y, 1M, and 1C for each color via the color motor gear 231, the drum intermediate gear 233, and the yellow, magenta, and cyan drum drive gears 232y, 232m, and 232c.

[0048] <Developing Roller Driving Method> Next, a method for driving the developing roller will be described, using the yellow developing roller 42Y.

[0049] In order to drive the yellow developing roller 42Y, the drive unit 20 includes a yellow developing motor 240y shown in FIG. 6(b), a yellow developing motor side gear 241y, a developing intermediate first gear 242y, a developing intermediate second gear 243y, and a developing coupling side gear 244y shown in FIG. 9. The yellow coupling side gear 244y has a yellow main body side developing coupling 244ay at the tip of the front gear shaft. The main body side developing coupling 244ay is formed to mesh with a coupling (not shown) provided at the rear end of the yellow developing roller 42Y.

[0050] The yellow developing motor 240y is held by the second drive frame 202, and a yellow developing motor side gear 241y is attached to the drive shaft of the yellow developing motor 240y. The yellow developing intermediate first gear 242y is disposed between the first drive frame 201 and the second drive frame 202, and is disposed so as to mesh with the yellow developing motor side gear 241y. The yellow developing intermediate second gear 243y and the developing coupling side gear 244y are held by a yellow developing coupling holding member 245y on the front side of the first drive frame 201. The yellow developing intermediate second gear 243y is disposed so as to mesh with the yellow developing intermediate first gear 242y, and the yellow developing coupling side gear 244y is disposed so as to mesh with the yellow developing intermediate second gear 243y. The yellow developing motor 240y rotates and drives the yellow developing roller 42Y via a yellow developing motor side gear 241y, a developing intermediate first gear 242y, a developing intermediate second gear 243y, a developing coupling side gear 244y, and a main body side developing coupling 244ay.

[0051] The configurations for driving the magenta developing roller 42M, the cyan developing roller 42C, and the black developing roller 42K are similar to the configuration for driving the yellow developing roller 42Y, and therefore description thereof will be omitted.

[0052] <Driving method of intermediate transfer belt> A method of driving the intermediate transfer belt 8 will be described. The drive unit 20 includes a motor 250 for the intermediate transfer belt shown in FIG. 6(b), a motor gear 251, an intermediate gear 252, and a drive gear 253 for the intermediate transfer belt shown in FIG. 9 in order to drive the intermediate transfer belt 8. The drive gear 253 for the intermediate transfer belt has a coupling 253a for the intermediate transfer belt at the tip of the front gear shaft. The coupling 253a for the intermediate transfer belt is formed so as to mesh with the coupling 121 (FIG. 4(a)) provided at the rear end of the secondary transfer inner roller 76, which is the drive roller of the intermediate transfer belt 8, when the intermediate transfer unit 110 is mounted on the image forming apparatus 100. The second drive frame 202 holds a drive gear holding member 255 for the intermediate transfer belt (FIG. 6(b)). The drive gear 253 for the intermediate transfer belt is held by the drive gear holding member 255 for the intermediate transfer belt so as to be positioned coaxially with the drive gear holding member 255 for the intermediate transfer belt. A motor gear 251 for the intermediate transfer belt is attached to the shaft of the motor 250 for the intermediate transfer belt. The motor gear 251 for the intermediate transfer belt is disposed so as to mesh with an intermediate gear 252 for the intermediate transfer belt. The intermediate gear 252 for the intermediate transfer belt is disposed between the first drive frame 201 and the second drive frame 202, and disposed so as to mesh with a drive gear 253 for the intermediate transfer belt. The drive gear 253 for the intermediate transfer belt is disposed between the first drive frame 201 and the second drive frame 202. The motor 250 for the intermediate transfer belt drives and rotates the intermediate transfer belt 8 via the motor gear 251 for the intermediate transfer belt, the intermediate gear 252, the drive gear 253, and the coupling 253a for the intermediate transfer belt.

[0053] The frequency of the sound generated from the drive unit composed of gears and a motor is the meshing frequency, which is the product of the number of gear teeth and the rotation speed of the gears. The meshing frequency of the drive unit 20 of this embodiment is 314 Hz.

[0054] <Drive unit housing configuration> Next, the configuration of the housing of the drive unit 20, which is framed by the first drive frame 201 and the second drive frame 202, will be described.

[0055] The drum drive gears 222, 232y, 232m, and 232c of each color provided in the drive unit 20 are pressed in the axial direction toward the photosensitive drum 1 by a pressing member (not shown) such as a spring provided between the drum drive gear and a drum gear holding member that holds the drum drive gear. As a result, the drum drive gears 222, 232y, 232m, and 232c of each color provided in the drive unit 20 are reliably joined (engaged) with the photosensitive drum 1 provided in the image forming portion P of each color at their respective coupling portions. At that time, if the rigidity of the first drive frame 201 and the second drive frame 202 is low, the flatness of both drive frames 201 and 202 is deteriorated by the pressing force of the pressing member, and the alignment of the gear shaft between the drum drive gear and the gear that meshes with it is deteriorated. If the alignment is deteriorated, the meshing accuracy of the drum drive gear is also deteriorated, so vibration increases, and as a result, there is a risk of image defects occurring due to the gear tooth pitch of the drum drive gear.

[0056] In order to prevent such image defects, drive frame wall portions 271, 272 shown in FIG. 10 are provided at the ends of the flat portions 201a, 202a of the drive frames 201, 202, respectively, to increase the rigidity of the holding portions of the drum drive gears of the drive frames 201, 202.

[0057] The first drive frame wall portion 271 is formed in a shape in which the first drive frame 201 extends from an end 201b of the flat portion 201a thereof toward the second drive frame 202 in the axial direction of the drive gear. The second drive frame wall portion 272 is formed in a shape in which the second drive frame 202 extends from an end 202b of the flat portion 202a thereof toward the first drive frame 201 in the axial direction. Here, the axial direction of the drive gear is a direction that coincides with the front-rear direction of the image forming apparatus 100.

[0058] The drive frame wall portions 271, 272 are provided at locations other than the fastening portions that fasten the first drive frame 201 and the second drive frame 202. In this embodiment, as shown in Figures 6(a) and 6(b), the first drive frame 201 and the second drive frame 202 are fastened to each other at fastening portions 280 with screws. The drive frame wall portions 271, 272 are provided at locations other than the fastening portions 280.

[0059] It is preferable that the drive frame wall portions 271, 272 are provided over the entire outer periphery of the ends 201b, 202b of the flat portions 201a, 202a of both drive frames 201, 202. However, in reality, there are various restrictions, and the drive frame wall portions 271, 272 are provided on parts of the ends 201b, 202b of the flat portions 201a, 202a. Therefore, the drive frame wall portions 271, 272 are provided at least near the through holes 206, 207 for the drum gear that holds the drum drive gear.

[0060] <Drive frame wall> The drive frame wall portions 271, 272 will be described with reference to Fig. 10. Fig. 10 is a partial cross-sectional view of the first drive frame 201 and the second drive frame 202 in this embodiment in a fastened state. In Fig. 10, gears and the like are omitted in order to explain the drive frame wall portions 271, 272, and only the drive frames 201, 202 are shown.

[0061] The wall portion includes a first drive frame wall portion 271 provided at an end 201b of the flat portion 201a of the first drive frame 201, and a second drive frame wall portion 272 provided at an end 202b of the flat portion 202a of the second drive frame 202. In this embodiment, the first drive frame wall portion 271 is provided in a region 273 including a straight line L in a second direction passing through the center of each first through hole 206, which is perpendicular to a straight line C in a first direction passing through the center of the first through holes 206. The second drive frame wall portion 272 is provided opposite the first drive frame wall portion 271 across a gap H in a second direction perpendicular to the axial direction. The second drive frame wall portion 272 is provided in a region 273 including a straight line L in a second direction passing through the center of each first through hole 206, which is perpendicular to a straight line C in a first direction passing through the center of the first through holes 206.

[0062] Here, the first direction is a direction that coincides with the left-right direction of the image forming apparatus 100. The second direction perpendicular to the first direction is a direction that coincides with the up-down direction of the image forming apparatus 100. The axial direction is the axial direction of the drum drive gear 222 and the like, and is a direction that coincides with the front-rear direction of the image forming apparatus 100 perpendicular to the first direction and the second direction. FIG. 11 also shows a straight line C in the first direction that passes through the centers of the first through holes 206. Similarly, FIG. 11 shows a straight line L in the second direction that passes through the centers of the first through holes 206 and is perpendicular to the straight line C. The straight line L shows straight lines LY, LM, LC, and LK for each color.

[0063] In the drive unit 20 that drives four photosensitive drums as in this embodiment, the first drive frame 201 and the second drive frame 202 hold four drum drive gears 222, 232c, 232m, and 232y. Each of the drum drive gears 222, 232c, 232m, and 232y is held by through holes 206k, 206c, 206m, and 206y for the four drum gears and through holes 207k, 207c, 207m, and 207y for the four drum gears that are positioned coaxially therewith. The pair of the first drive frame wall portion 271 and the second drive frame wall portion 272 facing each other across the gap H is disposed in the region 273 including the straight lines LK, LC, LM, and LY passing through the centers of the through holes 206k, 206c, 206m, and 206y that hold the drum drive gears 222, 232c, 232m, and 232y, so as to face each other through the drum drive gears 222, 232c, 232m, and 232y. In this embodiment, the pair of the first drive frame wall portion 271 and the second drive frame wall portion 272 is disposed in eight regions 273 indicated by broken lines in FIG. 11. The height (length in the front-rear direction) of each of the drive frame walls 271 and 272 is 20 mm. By disposing in this manner, the rigidity of the holding portions of the drum drive gears of both the drive frames 201 and 202 is efficiently increased.

[0064] Note that here, the first drive frame wall portion 271 and the second drive frame wall portion 272 are not provided between a region 273 including the straight line L and a region 273 including the straight line L adjacent to the region 273 in the left-right direction. Specifically, the first drive frame wall portion 271 and the second drive frame wall portion 272 are not provided between the region 273 including the straight line LY and the region 273 including the straight line LM, between the region 273 including the straight line LM and the region 273 including the straight line LC, and between the region 273 including the straight line LC and the region 273 including the straight line LK. In other words, the first drive frame wall portion 271 and the second drive frame wall portion 272 are provided at intervals at multiple locations in the left-right direction.

[0065] A gap H of several millimeters is provided between the opposing first drive frame wall portion 271 and second drive frame wall portion 272 to prevent them from contacting each other. If the two drive frame walls 271, 272 come into contact with each other, the contact may cause distortion in the first drive frame 201 and the second drive frame 202, deteriorating the flatness of the drive frames and causing the alignment of the drum drive gears to deteriorate. For this reason, the gap H is provided between the opposing first drive frame wall portion 271 and second drive frame wall portion 272 to maintain the flatness of the drive frames 201, 202.

[0066] Specifically, the shape of each mass-produced part has a dimensional error due to the variation in material lot and processing accuracy. For example, the shape of a straight line, a flat surface, or a bend angle has a dimensional error of several tens of μm to several hundreds of μm depending on the part. In a configuration in which the opposing drive frame walls are in contact with each other, the local position of actual contact may differ for each part. In other words, the displacement of the shape of the drive frame differs for each part, which may cause variation in the individual drive units, such as good and bad alignment of the drum drive gears. In order to prevent such variation and stabilize the quality of the drive unit, a gap H is provided between the opposing first drive frame wall 271 and second drive frame wall 272.

[0067] <Elastic material> Next, the elastic member 400 will be described with reference to Figures 11 and 12. Figure 11 is a diagram showing an area in which the elastic member is provided in the drive unit. Figure 12 is an explanatory diagram of the elastic member provided on the wall of the drive frame.

[0068] The drive unit 20 compresses and holds an elastic member 400 having a thickness greater than the dimension of the gap H in the gap H between the first drive frame wall portion 271 and the second drive frame wall portion 272 in an area 273 including the straight line L passing through the center of each first through hole 206.

[0069] In this embodiment, the first drive frame 201 and the second drive frame 202 are steel plates with a thickness of 1 mm. The elastic member 400 is an EPDM foam material (EPTSealer EC-100 manufactured by Nitto Denko Corporation, with a compression hardness of 0.28 N / cm at 50%). 2 ) was used. The length of the elastic member 400 in the outer circumferential direction of the drive frames 201, 202 (length in the left-right direction) was 20 mm. The thickness of the elastic member 400 was 3 mm, and the gap H between the opposing first drive frame wall portion 271 and second drive frame wall portion 272 was 1 mm. Therefore, the amount of compression of the elastic member 400 was 2 mm.

[0070] The dimensions of the gaps H between the drive frame wall portions 271, 272 provided at multiple locations do not all need to be the same. The dimensions of the gaps H may easily differ due to configuration constraints, etc. In that case, the thickness of the elastic member provided is changed to be larger relative to the dimension of the gap H. According to the results of experiments conducted by the inventors, the amount of compression of the elastic member is preferably 50 to 70% of the thickness of the elastic member.

[0071] Further, the elastic member 400 is attached to either the wall surface 271a of the first drive frame wall portion 271 or the wall surface 272a of the second drive frame wall portion 272 that faces the wall surface 271a of the first drive frame wall portion 271 across the gap H. Here, as shown in Fig. 12, the elastic member 400 is attached to the wall surface 272a of the second drive frame wall portion 272 with double-sided tape (not shown).

[0072] The elastic members 400 are provided in eight regions 273 in which the first drive frame wall portion 271 and the second drive frame wall portion 272 facing each other with a gap H therebetween are provided. That is, in the region 273, the elastic members 400 are provided in all of the gaps H between the first drive frame wall portion 271 and the second drive frame wall portion 272 on one side, which are arranged to face each other via the drum drive gears 222, 232c, 232m, and 232y, and the gaps H between the first drive frame wall portion 271 and the second drive frame wall portion 272 on the other side. Note that the compression hardness of the elastic member 400 according to the present embodiment, which is determined by the amount of squeezing, does not affect the flatness of both drive frames 201 and 202.

[0073] As a result of the above configuration, the noise reduction effect of the drive unit obtained by providing elastic member 400 in gap H of the wall portion will be described. With drive unit 20 of this embodiment incorporated in image forming apparatus 100, the sound pressure levels (unit: dB) of the operating sounds when black drum motor 220, color drum motor 230, development motor 240, and intermediate transfer belt motor 250 were rotated and driven were measured.

[0074] For the measurements, a microphone was used that detects the emitted sound waves and converts them into an electrical signal. A preamplifier that amplifies the electrical signal and a calculation device that converts the amplified electrical signal into a sound pressure level and frequency are connected to the microphone. The detection surface of the microphone was placed facing the center of the front side of the image forming apparatus 100, 1 m away from the exterior surface of the image forming apparatus 100 and 1.5 m above the floor.

[0075] FIG. 13 is a diagram showing the measurement results of the sound pressure level of an image forming apparatus including a drive unit. FIG. 13 shows the results of a comparative example in which the elastic member 400 is not provided in the gap H between the wall parts 271 and 272 of the drive unit 20 (without elastic member) and the present embodiment in which the elastic member 400 is provided (with elastic member). As shown in FIG. 13, in the comparative example in which the elastic member 400 is not provided in the gap H between the wall parts 271 and 272 of the drive unit 20, the sound pressure level was 27.8 dB. On the other hand, in the configuration of the present embodiment in which the elastic member 400 is provided in the gap H between the wall parts 271 and 272 of the drive unit 20, the sound pressure level was 17.8 dB. By providing the elastic member 400 in the gap H between the wall parts 271 and 272, the operating sound of the drive unit 20 of the present embodiment was reduced compared to the configuration in which the elastic member 400 is not provided, and a reduction effect of 10 dB was obtained at 314 Hz, which is the gear meshing frequency.

[0076] The reason for this reduction effect is that the elastic member 400 compressed and held by the first drive frame wall portion 271 and the second drive frame wall portion 272 damps the vibration of the first drive frame 201 and the second drive frame 202, thereby attenuating the vibration of both drive frames.

[0077] Incidentally, the first drive frame 201 and the second drive frame 202 have a plurality of through holes that are used for purposes other than driving the photosensitive drum, the developing roller, and the intermediate transfer belt. For example, as shown in Fig. 11, the first drive frame 201 has a positioning hole 281 for positioning the drive unit 20 on a jig when assembling the drive unit 20, and a confirmation hole 282 for confirming the presence or absence of components such as gears after assembling the drive unit 20. In addition, a gap is provided between the outer circumferential end of the first drive frame 201 and the outer circumferential end of the second drive frame 202, except for the fastening portion between the drive frames.

[0078] A typical configuration for achieving a noise reduction effect would be to block these through holes and gaps with separate parts, elastic members, or the like, thereby blocking the operating sounds emitted from inside the drive unit 20. In contrast, the present embodiment does not achieve a noise reduction effect by blocking all through holes and gaps leading to the inside of the drive unit 20 with elastic members, but rather achieves a noise reduction effect by damping the vibration of the frame that constitutes the drive unit with elastic members.

[0079] As described above, according to this embodiment, the flatness of each of the drive frames 201, 202 can be maintained by providing the gap H between the opposing first drive frame wall portion 271 and second drive frame wall portion 272. Furthermore, by compressing and holding the elastic member 400 between the first drive frame wall portion 271 and the second drive frame wall portion 272, vibration of the drive frames 201, 202 can be suppressed, and the drive unit 20 can be made quieter.

[0080] The present invention is not limited to the configuration of the above-described embodiment, but may be configured as follows.

[0081] In the above-described embodiment, the present invention is applied to a drive unit in a color image forming apparatus having photosensitive drums for four colors, but the present invention is not limited to this. For example, in a drive unit 0 in a monochrome image forming apparatus having one black photosensitive drum, the elastic member may not be provided on the wall portion corresponding to the through hole for the color drum gear, and the elastic member may be provided only on the wall portion corresponding to the through hole for the black drum gear. A specific description will be given with reference to FIG. 14.

[0082] 14, at least one first through hole 206k and one second through hole 207k located coaxially therewith hold one drum drive gear 222. In an area 273 including a straight line L passing through the center of the through hole 206k holding one drum drive gear 222, an elastic member 400 is compressed and held in a gap H between one wall portion 271, 272 and a gap H between the other wall portion 271, 272 arranged to face each other via the one drum drive gear 222.

[0083] Even with this configuration, similarly to the above-described embodiment, the flatness of each of the drive frames 201, 202 can be maintained while suppressing vibration of the drive frames 201, 202, thereby making the drive unit 20 quieter.

[0084] In the above-described embodiment, the elastic member 400 is provided in all eight regions, which are the gaps between the upper and lower wall portions of each drum drive gear, in the drive unit of a color image forming device having four photosensitive drums, but the present invention is not limited to this. The elastic member 400 is not required to be provided between all the walls 271, 272 of the four colors, but the silencing effect due to the vibration damping of the drive frame can be obtained. For example, in the drive unit of a color image forming device having four photosensitive drums, the elastic member may be provided between only one wall portion of the four colors, or a combination of walls of any color, such as yellow and cyan walls. In this case, the silencing effect obtained is reduced compared to when the elastic member is provided on all the walls of the four colors, but the silencing effect can be obtained compared to when the elastic member is not provided.

[0085] In other words, in the above-described embodiment, the configuration was exemplified in which the target locations of the gap between the wall portions 271, 272 that hold the elastic member 400 are equal to or greater than the number of drum drive gears held by the first drive frame and the second drive frame, but the present invention is not limited to this. The target locations of the gap between the wall portions 271, 272 that hold the elastic member 400 may be configured to be less than the number of drum drive gears held by the first drive frame and the second drive frame. Even with this configuration, the silencing effect can be obtained by damping the vibration of the drive frame by the elastic member.

[0086] In the above-described embodiment, the drive frame wall portions 271, 272 are provided on a part of the outer periphery of the drive frames 201, 202, but the present invention is not limited to this. The drive frame wall portions 271, 272 may be provided on the entire outer periphery of the drive frames 201, 202. In this case, the target portion of the drive frame wall portions 271, 272 that hold the elastic member 400 can obtain a silencing effect only by the wall portions 271, 272 in the vicinity of the through hole for the drum gear, which corresponds to the area 273 including the straight line L described above. However, the target portion of the drive frame wall portions 271, 272 that hold the elastic member 400 is not limited to only the wall portions 271, 272 in the vicinity of the through hole for the drum gear, but may be the wall portions 271, 272 on the entire periphery of the drive frame.

[0087] In the above-described embodiment, the pair of drive frame walls 271, 272 corresponding to the drum drive gears of each color is provided in the region 273 including the straight line L. However, depending on the constraints of the shapes of the surrounding parts, a plurality of pairs of drive frame walls 271, 272 corresponding to the drum drive gears of each color may be provided in the region 273, and an elastic member may be provided in each pair of walls. In addition, the pair of drive frame walls 271, 272 is provided in each region 273 including the straight line L, but this is not limited to this. The pair of drive frame walls 271, 272 may be provided as one pair so as to straddle two regions 273 adjacent to each other in the left-right direction. In this case, the elastic member 400 held between the drive frame walls 271, 272 may be provided as one so as to straddle the two regions 273, or may be divided and provided for each region 273, or may be provided in one of the regions 273.

[0088] In the above-described embodiment, the drive frames 201, 202 are made of steel plate, but the drive frames may be made of resin. In this case, the elastic member 400 provided between the drive frame walls 271, 272 is the same as in the above-described embodiment. In addition, the drive frames 201, 202 are made of steel plate, but the drive frames may be made of resin. Alternatively, the drive frames may be made of resin. One drive frame is made of steel plate and the other is made of resin.

[0089] The shape of the elastic member 400 attached to the drive frame wall portions 271, 272 is not limited to the shape shown in Fig. 12, and is preferably the shape shown in Fig. 15. The elastic member 400 shown in Fig. 12 is attached to one wall surface 272a of the opposing drive frame wall portions 271, 272 with double-sided tape (not shown). The elastic member 400 shown in Fig. 15 is further folded back from the one wall surface 272a to a wall surface 272c opposite to the wall surface 272a across the tip 272b of the wall surface 272a and attached with double-sided tape (not shown). This folded back shape can prevent damage such as peeling off of the elastic member 400 even if the first drive frame wall portion 271 to which the elastic member 400 is not attached comes into contact with the elastic member 400 when the drive frames 201, 202 are assembled. Although the configuration in which the elastic member 400 is attached to one of the second drive frame wall portions 272 has been exemplified here, the wall portion to which the elastic member 400 is attached may be either of the drive frames.

[0090] In the above embodiment, a printer is exemplified as an image forming apparatus, but the present invention is not limited thereto, and may be other image forming apparatuses such as a copier or facsimile machine, or other image forming apparatuses such as a multifunction machine combining the functions of these. Also, an image forming apparatus that uses an intermediate transfer body, transfers toner images of each color to the intermediate transfer body in a sequentially overlapping manner, and transfers the toner images carried on the intermediate transfer body to a recording material all at once is exemplified, but is not limited thereto. An image forming apparatus that uses a recording material carrier, and transfers toner images of each color to the recording material carried on the recording material carrier in a sequentially overlapping manner may also be used. Similar effects can be obtained by applying the present invention to the drive units in these image forming apparatuses. [Explanation of symbols]

[0091] H...Gap L(LY,LM,LC,LK),S…Straight line P … Recording material PY,PM,PC,PK...Image forming section 20 ... Drive unit 100 ... Image forming device 120 ... Image forming unit 122 ... Drum coupling 201 ... First drive frame 201a...Plane part 201b...end 202 ... Second drive frame 202a...Plane part 202b...end 206k, 206c, 206m, 206y ... First through hole 207k, 207c, 207c, 207y ... second through hole 220,230 … Drum motor 221,231 …Motor gear 222, 232c, 232m, 232y ... Drum drive gear 222a, 232ay, 232am, 232ac ... Main body drum coupling 233 ... Drum intermediate gear 234y, 234m, 234c ... Drum gear retaining member 240y, 240m, 240c, 240k ... Development motor 271 ... First drive frame wall 271a …Wall 272 ... Second drive frame wall 272a …Wall 273 …area 281 ... Positioning hole 282 ... Check hole 300...Base frame 301 ... In front of base frame 302 ... After base frame 303 ... Base frame left 304 … Base frame right 400 ... Elastic member 500 ... Control unit

Claims

1. A drive gear having a shaft coupling that engages with a rotating body and transmits a driving force to the rotating body, a first frame having a first holding portion that holds the shaft coupling side of the drive gear, a second frame having a second holding portion that is located coaxially with the first holding portion and holds the side opposite to the shaft coupling side of the drive gear, and an elastic member, wherein the first frame has a first portion including the surface on which the first holding portion is provided, and a first wall portion extending from an end of the first portion toward the second frame along the axial direction of the drive gear, the second frame has a second portion including the surface on which the second holding portion is provided, and a second wall portion extending from an end of the second portion toward the first frame along the axial direction of the drive gear, the first portion of the first frame and the second portion of the second frame are arranged to face each other with the drive gear interposed therebetween, and the first wall portion of the first frame and the second wall portion of the second frame are arranged to face each other so as to sandwich the elastic member in a compressed state. A drive unit characterized by this.

2. Comprising a plurality of drive gears including the drive gear, the first frame has a plurality of the first holding portions provided in the first portion corresponding to the plurality of drive gears, and the second frame has a plurality of the second holding portions provided in the second portion corresponding to the plurality of drive gears. The drive unit according to claim 1, characterized by this.

3. The elastic member includes a first elastic member and a second elastic member that are respectively compressed by the first wall portion of the first frame and the second wall portion of the second frame, the plurality of drive gears are arranged along a first direction that is orthogonal to the axial direction of one of the plurality of drive gears and along the surface, and in a second direction that is orthogonal to the axial direction and the first direction of the one drive gear, the first elastic member and the second elastic member are arranged to face each other via the one drive gear. The drive unit according to claim 2, characterized by this.

4. When viewed along a line of sight along the axial direction of the one drive gear, a straight line passing through the first holding portion corresponding to the one drive gear and extending in the second direction passes through the first elastic member and the second elastic member. The drive unit according to claim 3, characterized by this.

5. When viewed along the line of sight in the axial direction of the one driving gear, a straight line passing through the first holding portion corresponding to the one driving gear and extending in the second direction passes through the first elastic member and the second elastic member. The drive unit according to claim 3, wherein when viewed along the line of sight in the axial direction of the one driving gear, a straight line passing through the first holding portion corresponding to a driving gear different from the one driving gear and extending in the second direction is arranged so as not to pass through the elastic member.

6. Among the plurality of driving gears, the plurality of driving gears are arranged along a first direction that is orthogonal to the axial direction of one of the driving gears and along the surface. Each of the first wall portion and the second wall portion has a first partial wall portion and a second partial wall portion that are spaced apart in the first direction. When viewed along the line of sight in the axial direction of the one driving gear, a straight line passing through the first holding portion corresponding to the one driving gear and extending in a second direction that is orthogonal to the axial direction of the one driving gear and the first direction passes through the first partial wall portion. When viewed along the line of sight in the axial direction of the one driving gear, a straight line passing through the first holding portion corresponding to a driving gear different from the one driving gear and extending in the second direction passes through the second partial wall portion. The elastic member is an elastic member disposed between the first partial wall portion of the first wall portion and the first partial wall portion of the second wall portion, and an elastic member disposed between the second partial wall portion of the first wall portion and the second partial wall portion of the second wall portion. The drive unit according to claim 2, characterized by having.

7. The drive unit according to claim 3, wherein the second direction is a vertical direction.

8. The drive unit according to claim 1, wherein the first wall portion and the second wall portion are provided at locations other than the fastening portion that fastens the first frame and the second frame.

9. The drive unit according to any one of claims 1 to 8, a rotating body driven by the drive unit, and a main body frame to which the rotating body and the drive unit are attached. An image forming apparatus characterized by that.

10. The image forming apparatus according to claim 9, wherein the rotating body includes a photosensitive drum.

11. The rotating body includes a developing roller, and the image forming apparatus according to claim 9 is characterized by this.

Images