Image forming apparatus

Abstract

To provide an image forming apparatus that can be reduced in size.SOLUTION: An image forming apparatus comprises a member to be driven, a frame body, a driving source, and a drive transmission unit. The drive transmission unit has a gear train including a first gear, and a gear cover covering the gear train. The gear cover has an outside surface extending in an orthogonal direction orthogonal to a rotation axis direction, and a first recess recessed from the outside surface in a first direction parallel to the rotation axis direction. The first gear has a shank penetrating a first hole provided in the first recess and projecting in a second direction opposite to the first direction with respect to the first hole. The outside surface is a surface with the maximum area in the orthogonal direction among surfaces of the gear cover directed in the second direction. A downstream end in the second direction of the shank is the most downstream end of the gear train in the second direction, and is arranged upstream in the second direction of a virtual surface located at a position moved from the outside surface in the second direction by a plate thickness of the gear cover.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet. [Background technology]

[0002] Conventionally, an image forming apparatus has been disclosed that has a drive device including a side plate, a stay fixed to the side plate, a motor fixed to the stay, and an idler gear attached to a support shaft supported by the side plate and the stay (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-57146 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the drive device described in Patent Document 1, the support shaft, idler gear, and stay are disposed outside the side plate in the axial direction of the idler gear, and the motor is disposed outside the stay, which makes the device larger in the direction of the rotation axis.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus that can be made compact. [Means for solving the problem]

[0006] The present invention relates to an image forming apparatus for forming an image on a sheet, the apparatus comprising: a driven member; a frame body supporting the driven member; a drive source generating a drive force; and a drive transmission unit for transmitting the drive force of the drive source to the driven member, the drive transmission unit having a gear train including a first gear rotated by the drive force from the drive source; and a gear cover covering the gear train, the gear cover having an outer side surface extending in a direction perpendicular to a rotation axis direction of the first gear, and a first recess recessed from the outer side surface in a first direction parallel to the rotation axis direction, and a first recess extending in a direction perpendicular to the rotation axis direction of the first gear, the first recess being recessed from the outer side surface in a first direction parallel to the rotation axis direction ... the first gear has an axial portion that penetrates a first hole provided in the first recess and protrudes in a second direction opposite to the first direction relative to the first hole, the outer surface is the surface of the gear cover facing the second direction that has the largest area in the orthogonal direction, the downstream end of the axial portion in the second direction is the downstreammost end of the gear train in the second direction, and is disposed upstream in the second direction of a virtual surface that is moved in the second direction from the outer surface by the thickness of the gear cover and extends in the orthogonal direction.

[0007] The present invention also relates to an image forming apparatus for forming an image on a sheet, the apparatus comprising: a driven member; a frame body supporting the driven member; a drive source generating a drive force; and a drive transmission unit for transmitting the drive force of the drive source to the driven member, the drive transmission unit having a gear train including a gear rotated by the drive force from the drive source, a gear cover covering the gear train, and a bearing member rotatably supporting a shaft portion of the gear, the gear cover having an outer surface extending in a direction perpendicular to a rotation axis direction of the gear, and a bearing member recessed from the outer surface in a first direction parallel to the rotation axis direction. the bearing member has a protruding portion penetrating a hole provided in the recess and protruding in a second direction opposite to the first direction relative to the hole, the outer surface is the surface of the gear cover facing the second direction that has the largest area in the orthogonal direction, and the downstream end of the protruding portion in the second direction is an imaginary surface that is moved in the second direction from the outer surface by the plate thickness of the gear cover, and is disposed upstream in the second direction of an imaginary surface extending in the orthogonal direction. Effect of the Invention

[0008] According to the present invention, the image forming apparatus can be made smaller. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a perspective view showing a motor and a drive transmission unit. [Diagram 3] FIG. 4A is a front view showing the drive transmission unit, and FIG. [Figure 4] 4(a) is a perspective view showing a first driving gear train and a first gear cover, and FIG. 4(b) is a cross-sectional view showing the X1-X1 cross section of FIG. 4(a). [Diagram 5] 5(a) is a perspective view showing a first driving gear train and a first gear cover, and FIG. 5(b) is a cross-sectional view showing the X2-X2 cross section in FIG. 5(a). [Figure 6]6(a) is a perspective view showing a first driving gear train and a first gear cover, and FIG. 6(b) is a cross-sectional view showing the X3-X3 cross section of FIG. 6(a). [Figure 7] FIG. 4A is a cross-sectional view showing the motor, and FIG. 4B is a cross-sectional view showing a solenoid arranged on the side of the second drive gear train. [Figure 8] 8(a) is a perspective view showing a first driving gear train, a first gear cover, and a cable guide, and FIG. 8(b) is a cross-sectional view showing a cross section taken along line X4-X4 in FIG. 8(a). [Figure 9] FIG. 13 is a perspective view showing a screw according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Overall configuration of image forming device] First, a schematic configuration of an image forming apparatus according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of an image forming apparatus 100. The image forming apparatus 100 according to the present embodiment is an electrophotographic laser printer. As shown in Fig. 1, the image forming apparatus 100 has an apparatus main body A and a cartridge B as an image forming section.

[0011] The image forming apparatus includes printers, copiers, facsimiles, and multifunction machines, and refers to an apparatus that forms an image on a sheet used as a recording medium based on image information input from an external PC or image information read from an original. In addition, an image forming apparatus may be connected to an optional feeder, an image reader, a sheet processing device, and other auxiliary devices in addition to a main body having an image forming function, and the entire system to which such auxiliary devices are connected is also a type of image forming apparatus.

[0012] The apparatus main body A includes a laser scanner 101, a sheet transport section 102, a sheet feeding section 103, a transfer roller 104, a fixing section 105, a sheet discharge section 110, etc. The apparatus main body A also includes a removably mounted cartridge B. For this purpose, the apparatus main body A has an opening / closing door 107.

[0013] The cartridge B has a photosensitive drum 11 as an image carrier and a photosensitive member, a charging roller 12 as a charging member, a developing unit 15, and a cleaning blade 17 as a cleaning member. A laser scanner 101 as an exposure device is disposed above the cartridge B.

[0014] The charging roller 12 is disposed so as to contact the outer peripheral surface of the photosensitive drum 11, and charges the photosensitive drum 11 by application of a voltage from the apparatus main body A. The charging roller 12 rotates in conjunction with the photosensitive drum 11. The developing unit 15 includes a developing roller 16 as a developer carrier that carries and transports toner as a developer. The developing roller 16 is disposed so as to face the photosensitive drum 11.

[0015] The cleaning blade 17 is an elastic member disposed so as to come into contact with the outer peripheral surface of the photosensitive drum 11, and cleans the surface of the photosensitive drum 11. The cleaning blade 17 removes toner remaining on the photosensitive drum 11 after the sheet S passes between the photosensitive drum 11 and the transfer roller 104, by bringing its tip into elastic contact with the photosensitive drum 11. The sheet S includes paper such as paper and envelopes, plastic films such as overhead projector sheets (OHP), cloth, etc.

[0016] The sheet feeding section 103 has a cassette 103a, a pickup roller 103b that feeds the topmost sheet S contained in the cassette 103a, and a separation roller pair 103c that separates the sheets S fed by the pickup roller 103b one by one.

[0017] The sheet conveying section 102 has a conveying roller pair 102a that conveys the sheet S fed from the sheet feeding section 103, and a registration roller pair 102b. The registration roller pair 102b conveys the sheet S to a transfer nip N1 between the photosensitive drum 11 and a transfer roller 104 in synchronization with the toner image formed on the photosensitive drum 11.

[0018] The fixing unit 105 has a fixing roller 105a heated by a heat source such as a heater, and a pressure roller 105b that forms a fixing nip N2 that holds the sheet between the fixing roller 105a and the fixing roller 105a. The sheet S to which the toner image has been transferred at the transfer nip N1 is conveyed to the fixing unit 105, where it is heated and pressurized at the fixing nip N2. This causes the toner image to be fixed onto the sheet S.

[0019] The sheet discharge section 110 has a pair of discharge rollers 110a, and discharges the sheet S on which the toner image has been fixed onto the discharge tray 106 by the pair of discharge rollers 110a.

[0020] [Operation of image forming device] Next, the operation of the image forming apparatus 100 will be described with reference to Fig. 1. The photosensitive drum 11, which is rotationally driven by a drive transmission structure described below, is uniformly charged to a predetermined potential by the charging roller 12. After charging, the surface of the photosensitive drum 11 is exposed to light based on image information by a laser scanner 101, and the charge in the exposed area is removed to form an electrostatic latent image. Toner is supplied from a developing roller 16 to the electrostatic latent image on the photosensitive drum 11, and the image is visualized as a toner image.

[0021] Meanwhile, in parallel with the formation of the toner image, a sheet S is fed from a sheet feeding section 103. The sheet S fed from the sheet feeding section 103 is conveyed to the transfer nip N1 by a pair of registration rollers 102b in time with the formation of a toner image on the photosensitive drum 11. When the sheet S passes through the transfer nip N1, a voltage is applied from the apparatus main body A to the transfer roller 104, and the toner image on the photosensitive drum 11 is transferred to the sheet S as an unfixed image. Thereafter, the sheet S on which the toner image has been transferred is conveyed to a fixing section 105, where the unfixed image is heated and pressurized to be fixed to the surface of the sheet S. The sheet S on which the toner image has been fixed is discharged to a discharge tray 106 by a sheet discharge section 110 and stacked thereon.

[0022] [Drive configuration of image forming apparatus] Next, the drive configuration of the image forming apparatus 100 will be specifically described with reference to Fig. 2 and Fig. 3. Fig. 2 is a perspective view showing the motor 131 and the drive transmission unit 120 provided in the apparatus main body A. Fig. 3(a) is a front view showing the drive transmission unit 120, and Fig. 3(b) is a side view showing the drive transmission unit 120. Note that in Figs. 2 to 3(b), exterior members of the image forming apparatus 100, the cartridge B, etc. are omitted.

[0023] 2 to 3(b), the apparatus main body A has a left side plate 112, a right side plate 121 as a frame, a connecting frame 113, a motor 131 as a drive source supported by the right side plate 121, and a drive transmission unit 120. The left side plate 112, the right side plate 121, and the connecting frame 113 configure the frame of the apparatus main body A, and the connecting frame 113 connects the left side plate 112 and the right side plate 121. There is a space between the left side plate 112 and the right side plate 121, and the cartridge B, various rollers for transporting the sheet S, a guide member for guiding the sheet S, and the like are disposed in the space.

[0024] The drive transmission unit 120 includes a first drive gear train 122, a first gear cover 123, a second drive gear train 124, a second gear cover 125, etc. Although not shown in FIGS. 2 to 3(b), an exterior right cover 126 (see FIG. 4(b)) is disposed on the outside of the drive transmission unit 120 as an exterior member that covers the apparatus main body A. The exterior right cover 126 forms at least a part of the exterior of the image forming apparatus 100. The left side plate 112, the connecting frame 113, the right side plate 121, the first gear cover 123, and the second gear cover 125 are made of sheet metal.

[0025] Each gear provided in the drive transmission unit 120 is configured to be rotatable about an axis extending in the rotation axis direction AD. In the following, the direction of the rotation axis direction AD from the first gear cover 123 and the second gear cover 125 toward the inside of the image forming apparatus 100 is referred to as a first direction AD1, and the direction opposite to the first direction AD1 is referred to as a second direction AD2. Therefore, both the first direction AD1 and the second direction AD2 are parallel to the rotation axis direction AD.

[0026] A first gear cover 123 and a second gear cover 125 are attached to the right side plate 121 on the outer side in the rotation axis direction AD of the right side plate 121 with screws 141 and 142. A first drive gear train 122 as a gear train is supported by the right side plate 121 and the first gear cover 123 and is covered by the first gear cover 123. A second drive gear train 124 is supported by the right side plate 121 and the second gear cover 125 and is covered by the second gear cover 125. A motor 131 is attached to the inner side in the rotation axis direction AD of the right side plate 121. The motor 131 generates a drive force. The first drive gear train 122 receives the drive force of the motor 131 and transmits the drive force to the photosensitive drum 11, the fixing unit 105, and the sheet discharge unit 110. The second driving gear train 124 receives driving force from the motor 131 via the first driving gear train 122, and transmits the driving force to the sheet conveying section 102 and the sheet feeding section 103. In other words, the photosensitive drum 11, the fixing section 105, the sheet discharge section 110, the sheet conveying section 102, and the sheet feeding section 103 are examples of driven members driven by the driving force of the motor 131. In other words, the driven members include rollers that convey the sheet S. The first driving gear train 122 and the second driving gear train 124 each have a plurality of gears.

[0027] 2, the drive transmission unit 120 includes a shaft member 132 that rotatably supports gears, a bearing member 133, an actuator 134, and a cable guide 135. Note that, in the following, the shaft member 132, bearing member 133, actuator 134, and cable guide 135 provided on the first driving gear train 122 side will be described as an example, but similar shaft members, bearing members, actuators, and cable guides are provided on the second driving gear train 124 side.

[0028] The shaft member 132 is attached by crimping to a first gear cover 123 serving as a gear cover, and is disposed so as to support the gears of the first driving gear train 122. The bearing member 133 is attached to the first gear cover 123, and is disposed so as to support the gears of the first driving gear train 122.

[0029] The actuator 134 includes an electromagnetic clutch 134a and a solenoid 134b, and the electromagnetic clutch 134a and the solenoid 134b are disposed downstream of the first driving gear train 122 and the second driving gear train 124 in the drive transmission direction. The actuator 134 transmits the driving force of the motor 131 to a driven member (such as the photosensitive drum 11) when energized, and operates not to transmit the driving force of the motor 131 to the driven member when energized. The cable guide 135 guides a cable 138 (see FIG. 8(a)) that connects the electromagnetic clutch 134a and the solenoid 134b to an electric board (not shown), and is attached to the first gear cover 123. The actuator 134 and the cable guide 135 are disposed upstream of the first gear cover 123 in the second direction AD2, that is, on the inside in the rotation axis direction AD.

[0030] In the present embodiment, the right side plate 121, the first gear cover 123, and the second gear cover 125 are made of sheet metal, but the present invention is not limited to this. These members may be made of resin.

[0031] [Gear support structure] Next, a support configuration for gears 122a, 122b, and 122c among the multiple gears provided in the first drive gear train 122 will be described. The gear 122a is an example of a type in which the gear 122a itself has a gear shaft portion 122a1, that is, a gear that is not supported by the shaft member 132 or the bearing member 133. The gear 122b is an example of a type of gear that is rotatably supported by the shaft member 132 that penetrates the gear 122b. The gear 122c is an example of a type of gear that is rotatably supported by the bearing member 133. [Gear shaft support structure]

[0032] First, the support structure of the gear 122a as a first gear having a gear shaft portion 122a1 will be described with reference to Fig. 4(a) and (b). Fig. 4(a) is a perspective view showing the first driving gear train 122 and the first gear cover 123, and Fig. 4(b) is a cross-sectional view showing the X1-X1 cross section of Fig. 4(a). Note that the exterior right cover 126 is not shown in Fig. 4(a), but is shown on the outside of the first gear cover 123 in Fig. 4(b).

[0033] 4(a) and 4(b), the gear 122a has a gear shaft portion 122a1 as a shaft portion extending in the rotation axis direction AD, and a gear portion 122a5 extending from the gear shaft portion 122a1 in a perpendicular direction PD perpendicular to the rotation axis direction AD and having a plurality of teeth. The gear shaft portion 122a1 has a first end portion 122a11 which is a downstream end portion in the second direction AD2, and a second end portion 122a12 which is a downstream end portion in the first direction AD1.

[0034] The first gear cover 123 has an outer side surface 123Z extending in the orthogonal direction PD and a recess 123a as a first recess recessed from the outer side surface 123Z in the first direction AD1, and is disposed upstream of the right side plate 121 in the first direction AD1. The outer side surface 123Z is a flat surface. The outer side surface 123Z is the surface having the largest area in the orthogonal direction PD among the surfaces of the first gear cover 123 facing the second direction AD2, and is the surface of the downstream end of the first gear cover 123 in the second direction AD2. In other words, the first gear cover 123 has a plurality of surfaces facing the second direction AD2. The outer side surface 123Z is the surface having the largest area in the orthogonal direction PD among the plurality of surfaces. The outer side surface 123Z does not necessarily have to be the surface of the downstream end of the first gear cover 123 in the second direction AD2. In this embodiment, the outer side surface 123Z is the surface having the largest area in the orthogonal direction PD among all the surfaces of the first gear cover 123. Also, in this embodiment, the outer side surface 123Z is the surface having the largest area among all the surfaces of the first gear cover 123. As shown in FIG. 4(b), the outer side surface 123Z faces the exterior right cover 126. Also, the exterior right cover 126 is disposed downstream of the outer side surface 123Z in the second direction AD2.

[0035] The recess 123a is formed by drawing. The gear shaft portion 122a1 including the first end portion 122a11 and the second end portion 122a12 is disposed in an area AR1 in which the recess 123a is formed, as viewed in the first direction AD1.

[0036] As shown in FIG. 4(b), the first gear cover 123 has a burring portion 123a1 formed by burring, and the burring portion 123a1 is provided in the recess 123a. Similarly, the right side plate 121 has a burring portion 121a1 formed by burring, and the burring portion 121a1 is provided at a position facing the burring portion 123a1 in the rotation axis direction AD. The first end 122a11 of the gear shaft portion 122a1 is rotatably supported by the burring portion 123a1 of the first gear cover 123. Also, the second end 122a12 of the gear shaft portion 122a1 is rotatably supported by the burring portion 121a1 of the right side plate 121. In other words, the recess 123a has a hole 123a6 as a first hole formed by the burring portion 123a1, and the right side plate 121 has a hole 123a7 formed by the burring portion 121a1. The first end 122a11 of the gear shaft portion 122a1 passes through the hole 123a6 provided in the recess 123a, and the second end 122a12 of the gear shaft portion 122a1 passes through the hole 123a7 provided in the right side plate 121.

[0037] The first end 122a11 of the gear shaft portion 122a1 penetrates the recess 123a and protrudes in the second direction AD2 relative to the recess 123a. More specifically, the first end 122a11 of the gear shaft portion 122a1 penetrates a hole 123a6 provided in the recess 123a and protrudes in the second direction AD2 relative to the hole 123a6. Furthermore, the downstream end 122aE of the first end 122a11 in the second direction AD2 is disposed upstream of the outer surface 123Z in the second direction AD2. That is, the downstream end 122aE of the gear shaft portion 122a1 in the second direction AD2 is disposed inside the outer surface 123Z in the rotation axis direction AD. In addition, the downstream end 122aE is the most downstream end of the first drive gear train 122 in the second direction AD2. That is, the multiple gears constituting the first drive gear train 122 are present within a predetermined area in the second direction AD2. The most downstream end of the first driving gear train 122 in the second direction AD2 is the same as the downstream end of the region in which the multiple gears exist in the second direction AD2. In other words, if the multiple gears exist in the region between the first position and the second position in the second direction AD, the most downstream end of the first driving gear train 122 is the same as the second position.

[0038] Therefore, it is possible to minimize the clearance L1, which is the distance between the outer surface 123Z of the first gear cover 123 and the exterior right cover 126 in the rotational axis direction AD, and the image forming apparatus 100 can be made smaller in size in the rotational axis direction AD.

[0039] 4(b), consider a virtual surface 200 located at a position shifted in the second direction AD2 from the outer surface 123Z by the plate thickness d1 of the first gear cover 123. The virtual surface (virtual plane) 200 extends in the orthogonal direction PD. As described above, the downstream end 122aE of the gear shaft portion 122a1 is located upstream of the outer surface 123Z in the second direction AD2, and is therefore located upstream of the virtual surface 200.

[0040] The gear 122a has a clearance L2 between itself and the first gear cover 123 in the rotation axis direction AD. That is, the gear shaft portion 122a1 of the gear 122a is configured to be movable in the rotation axis direction AD by a predetermined distance, that is, the clearance L2, by the burring portion 123a1 of the first gear cover 123 and the burring portion 121a1 of the right side plate 121.

[0041] In Fig. 4(b), the gear 122a is pressed downstream in the first direction AD1 against the right side plate 121. However, when the gear 122a is pressed downstream in the second direction AD2 against the first gear cover 123, the downstream end 122aE of the gear shaft portion 122a1 may protrude downstream in the second direction AD2 beyond the outer surface 123Z. In that case, if the downstream end 122aE of the gear shaft portion 122a1 is pressed in the first direction AD1, the gear 122a moves inward, so that the downstream end 122aE can be prevented from protruding outward beyond the outer surface 123Z, and the clearance L1 can be minimized.

[0042] In this embodiment, the clearance L2 is set to be smaller than the plate thickness d1 of the first gear cover 123. For this reason, even if the gear 122a is pressed downstream in the second direction AD2 against the first gear cover 123, the downstream end 122aE of the gear shaft portion 122a1 does not protrude downstream in the second direction AD2 beyond the imaginary plane 200.

[0043] As described above, in this embodiment, the clearance L2 is set to be smaller than the plate thickness d1, but is not limited to this. In other words, if the downstream end 122aE of the gear shaft portion 122a1 does not protrude downstream in the second direction AD2 beyond the imaginary plane 200 when the gear 122a is pressed against the first gear cover 123, the clearance L2 may be larger than the plate thickness d1.

[0044] Furthermore, due to dimensional tolerances of parts, the clearance L1 between the outer surface 123Z of the first gear cover 123 and the exterior right cover 126 is equal to or larger than the plate thickness d1 of the first gear cover 123. Therefore, even if the gear 122a is pressed downstream in the second direction AD2 against the first gear cover 123, the downstream end 122aE of the gear shaft portion 122a1 will not interfere with the exterior right cover 126.

[0045] In this embodiment, the support structure of the gear 122a of the first driving gear train 122 has been described, but the gear 124a of the second driving gear train 124 may have a support structure similar to that of the gear 122a. That is, as shown in Fig. 3(a), the second gear cover 125 has an outer surface 125Z and a recess 125a, and the gear shaft portion 124a1 of the gear 124a penetrates the recess 125a and protrudes in the second direction AD2. The downstream end of the gear shaft portion 124a1 in the second direction AD2 is disposed upstream of the imaginary plane 200 and the outer surface 125Z in the second direction AD2.

[0046] [Support structure of shaft member] Next, the support structure of the shaft member 132 that rotatably supports the gear 122b will be described with reference to Fig. 5. Fig. 5(a) is a perspective view showing the first driving gear train 122 and the first gear cover 123, and Fig. 5(b) is a cross-sectional view showing the X2-X2 cross section of Fig. 5(a). In addition, the exterior right cover 126 is not shown in Fig. 5(a), but is shown in Fig. 5(b) on the outside of the first gear cover 123.

[0047] 5(a) and 5(b), the gear 122b of the first drive gear train 122 is rotatably supported by a shaft member 132 extending in the rotation axis direction AD. The shaft member 132 has a first end 132a which is a downstream end in the second direction AD2, and a second end 132b which is a downstream end in the first direction AD1. The second end 132b of the shaft member 132 is supported in a hole 121b of the right side plate 121.

[0048] A first end 132a of the shaft member 132 is supported in a hole 123b of the first gear cover 123, and is swaged to the first gear cover 123 to restrict movement in the rotation axis direction AD. The first end 132a protrudes slightly in the second direction AD2 beyond an outer surface 123Z of the first gear cover 123.

[0049] Crimping of the first end 132a is a method of crushing and plastically deforming the portion of the first end 132a that protrudes downstream in the second direction AD2 from the hole 123b of the first gear cover 123, and joining it to the first gear cover 123.

[0050] Therefore, the amount of protrusion of the first end 132a in the second direction AD2 from the outer surface 123Z of the first gear cover 123 is small and is equal to or smaller than the plate thickness d1 of the first gear cover 123. That is, the first end 132a is disposed upstream of the above-mentioned imaginary plane 200 in the second direction AD2.

[0051] A clearance L1, which is a distance between the outer surface 123Z of the first gear cover 123 and the exterior right cover 126 in the rotation axis direction AD, is larger than a plate thickness d1 of the first gear cover 123, so there is no interference between the first end 132a of the shaft member 132 and the exterior right cover 126. Therefore, it is possible to minimize the clearance L1, and the image forming apparatus 100 can be made smaller in size in the rotation axis direction AD.

[0052] [Support structure of bearing members] Next, the support structure of the bearing member 133 that rotatably supports the gear 122c of the first driving gear train 122 will be described with reference to Fig. 6. Fig. 6(a) is a perspective view showing the first driving gear train 122 and the first gear cover 123, and Fig. 6(b) is a cross-sectional view showing the X3-X3 cross section of Fig. 6(a). In addition, the exterior right cover 126 is not shown in Fig. 6(a), but Fig. 6(b) shows the exterior right cover 126 on the outer side of the first gear cover 123.

[0053] As shown in Fig. 6(a) and (b), the gear 122c as the second gear has a gear shaft portion 122c1 extending in the rotation axis direction AD, a coupling portion 122c2 provided at the downstream end of the gear shaft portion 122c1 in the first direction AD1, and a gear portion 122c3. The coupling portion 122c2 as the second coupling portion engages with a coupling portion (not shown) as the first coupling portion to transmit driving force between these coupling portions. The gear portion 122c3 extends from the gear shaft portion 122c1 in the orthogonal direction PD and has a plurality of teeth formed thereon.

[0054] The gear shaft portion 122c1 of the gear 122c is rotatably supported by the bearing member 133, and the bearing member 133 is supported by a hole in the first gear cover 123 and a hole portion 123c1 as a second hole. Furthermore, a biasing member 136, for example, a coil spring, is compressed between the bearing member 133 and the gear 122c in the rotation axis direction AD. The biasing member 136 biases the gear 122c and the bearing member 133 in a direction away from each other in the rotation axis direction AD. That is, the biasing member 136 biases the coupling portion 122c2 in the first direction AD1 to engage with another coupling portion facing the coupling portion 122c2. The biasing member 136 is not limited to a coil spring, and other elastic members such as a disc spring or a torsion bar may be used, and sponge, elastic rubber, etc. may also be used.

[0055] The first gear cover 123 has a recess 123c as a second recess recessed from the outer surface 123Z in the first direction AD1. The hole 123c1 is provided in the recess 123c. The recess 123c is formed by drawing. The bearing member 133 and the gear shaft portion 122c1 are disposed in an area AR2 in which the recess 123c is formed, as viewed in the first direction AD1.

[0056] The bearing member 133 has a protruding portion 133a that penetrates the recess 123c and protrudes in the second direction AD2 relative to the recess 123c. More specifically, the protruding portion 133a of the bearing member 133 penetrates a hole 123c1 provided in the recess 123c and protrudes in the second direction AD2 relative to the hole 123c1. A downstream end 133aE of the protruding portion 133a in the second direction AD2 protrudes slightly in the second direction AD2 beyond the outer surface 123Z of the first gear cover 123. The bearing member 133 is configured to be movable in the first direction AD1 against the biasing force of the biasing member 136.

[0057] In FIG. 6(b), the gear 122c is pressed downstream in the second direction AD2 relative to the first gear cover 123 by the biasing force of the biasing member 136. At this time, the downstream end 133aE of the protruding portion 133a is disposed between the outer surface 123Z of the first gear cover 123 and the imaginary surface 200 in the rotation axis direction AD. That is, the downstream end 133aE is disposed upstream of the imaginary surface 200 in the second direction AD2. In other words, the protruding amount of the downstream end 133aE in the second direction AD2 relative to the outer surface 123Z of the first gear cover 123 is equal to or less than the plate thickness d1 of the first gear cover 123.

[0058] A clearance L1, which is a distance between the outer surface 123Z of the first gear cover 123 and the exterior right cover 126 in the rotation axis direction AD, is larger than a plate thickness d1 of the first gear cover 123, so that the downstream end 133aE of the protrusion 133a does not interfere with the exterior right cover 126. Therefore, it is possible to minimize the clearance L1, and the image forming apparatus 100 can be made smaller in size in the rotation axis direction AD.

[0059] Furthermore, by pressing the bearing member 133 in the first direction AD1 against the biasing force of the biasing member 136, the downstream end 133aE can be prevented from protruding outward beyond the outer surface 123Z, and the clearance L1 can be minimized.

[0060] In this embodiment, the height L3 of the recess 123c, i.e., the distance from the bottom surface of the recess 123c to the outer surface 123Z, is approximately the same as the protrusion amount L4 of the protrusion 133a from the recess 123c. The protrusion amount L4 is preferably smaller than the length obtained by adding the plate thickness d1 to the height L3, and the clearance L1 can be reduced by changing the height L3 according to the protrusion amount L4. For example, when the protrusion amount L4 is larger than the clearance L1, it is preferable that the height L3 is also larger than the clearance L1.

[0061] [Motor and actuator configuration] Next, the configurations of the motor 131 and the actuator 134 will be described with reference to Figures 7(a) and 7(b). Figure 7(a) is a cross-sectional view showing the motor 131, and Figure 7(b) is a cross-sectional view showing the solenoid 134b arranged on the second drive gear train 124 side.

[0062] As shown in FIG. 7(a), the motor 131 is disposed downstream of the right side plate 121 in the first direction AD1 and is fixed to the right side plate 121 with a screw 130. The motor 131 has a rotationally driven shaft portion 131a, and a pinion gear 137 is attached to the shaft portion 131a. The pinion gear 137 is disposed so as to overlap at least some of the gears of the first driving gear train 122 and the second driving gear train 124 in the rotation axis direction AD. The gears that overlap the pinion gear 137 in the rotation axis direction AD include the gears 122a, 122b, and 122c. The pinion gear 137 is disposed upstream of the outer surface 123Z of the first gear cover 123 in the second direction AD2.

[0063] 7(a), the motor 131 including the shaft portion 131a and the pinion gear 137 are disposed downstream of the outer surface 123Z of the first gear cover 123 in the first direction AD1. In this manner, the motor 131 and the pinion gear 137 do not protrude outward from the outer surface 123Z of the first gear cover 123 in the rotation axis direction AD. This makes it possible to minimize the clearance L1 between the outer surface 123Z and the exterior right cover 126.

[0064] As shown in FIG. 7(b), the solenoid 134b is disposed upstream of the right side plate 121 in the first direction AD1 and is fixed to the right side plate 121 with a screw 140. The second drive gear train 124 disposed adjacent to the solenoid 134b is supported by the second gear cover 125. The second gear cover 125 has an outer surface 125Z extending in the perpendicular direction PD. The outer surface 125Z of the second gear cover 125 is flush with the outer surface 123Z of the first gear cover 123. The outer surface 125Z is the surface of the second gear cover 125 that has the largest area extending parallel to the perpendicular direction PD, and is the surface of the downstream end of the second gear cover 125 in the second direction AD2. The outer surface 125Z does not necessarily have to be the surface of the downstream end of the second gear cover 125 in the second direction AD2.

[0065] The solenoid 134b shown in FIG. 7(b) is disposed on the inside of the outer surface 125Z. In this manner, the solenoid 134b does not protrude outward from the outer surface 125Z of the second gear cover 125 in the rotation axis direction, and the outer surface 125Z is flush with the outer surface 123Z. In addition, the plate thickness of the second gear cover 125 is the same as the plate thickness d1 of the first gear cover 123. Therefore, it is possible to minimize the clearance L1 between the outer surface 125Z of the second gear cover 125 and the outer surface 123Z of the first gear cover 123 and the exterior right cover 126.

[0066] 7(a) and 7(b), the configuration and arrangement of the motor and solenoid as actuators are described, but are not limited thereto. For example, the electromagnetic clutch 134a (see FIG. 2) is also arranged so as not to protrude outward from the outer surface 123Z of the first gear cover 123 in the rotation axis direction AD, and the same is true for the other actuators.

[0067] [Structure of the bundle guide] Next, the configuration of the cable guide 135 will be described with reference to Figures 8(a) and 8(b). Figure 8(a) is a perspective view showing the first driving gear train 122, the first gear cover 123, and the cable guide 135, and Figure 8(b) is a cross-sectional view showing the X4-X4 cross section of Figure 8(a). Although the exterior right cover 126 is not shown in Figure 8(a), the exterior right cover 126 is shown on the outside of the first gear cover 123 in Figure 8(b).

[0068] The cable guide 135 is attached to the first gear cover 123 as a component for guiding a cable 138 that connects the electromagnetic clutch 134a and the solenoid 134b to an electric board (not shown), and is disposed between the gears of the first driving gear train 122. The cable 138 as a cable supplies power to the electromagnetic clutch 134a and the solenoid 134b, which are actuators. As shown in FIGS. 8(a) and 8(b), the cable guide 135 is disposed between the right side plate 121 and the first gear cover 123 in the rotation axis direction AD, and is attached to the inside of the first gear cover 123. The cable 138 is surrounded by the cable guide 135 and the first gear cover 123, and is disposed so as to pass between the gears of the first driving gear train 122.

[0069] 8(b), the cable guide 135 is disposed inward of the outer surface 123Z of the first gear cover 123 in the rotation axis direction AD. In this manner, since the cable guide 135 does not protrude from the outer surface 123Z of the first gear cover in the rotation axis direction AD, it is possible to minimize the clearance L1 between the outer surface 123Z and the exterior right cover 126.

[0070] As described above, the motor 131, the pinion gear 137, the solenoid 134b and the cable guide 135 are disposed upstream of the outer surface 123Z in the second direction AD2, and therefore, naturally, are disposed upstream of the imaginary surface 200.

[0071] [Service configuration] In this embodiment, the screws 130, 140, 141, and 142 are fastened to the right side plate 121 and are therefore disposed inward in the rotation axis direction AD from the outer surface 123Z of the first gear cover 123. This makes it possible to minimize the clearance L1 between the outer surface 123Z and the exterior right cover 126.

[0072] <Modification> Next, a modified configuration of the screw 150 will be described. However, depending on the drive configuration, there may be cases where it is desired to fasten the screw to the first gear cover 123, rather than to the right side plate 121. The modified screw 150 is fastened to the first gear cover 123.

[0073] 9, the first gear cover 123 has an outer surface 123Z and a recess 123d recessed from the outer surface 123Z in the first direction AD1. The recess 123d is formed by drawing. The screw 150 is disposed in an area AR3 in which the recess 123d is formed, as viewed in the first direction AD1.

[0074] That is, the screw 150 is fastened to the recess 123d of the first gear cover 123, and is disposed upstream of the outer surface 123Z in the second direction AD2. The screw 150 is also disposed upstream of the imaginary plane 200 (see FIG. 4(b)) in the second direction AD2. This makes it possible to minimize the clearance L1, which is the distance between the outer surface 123Z and the exterior right cover 126, and thus makes it possible to reduce the size of the image forming apparatus 100 in the rotation axis direction AD.

[0075] As described above, in the present embodiment, the gear shaft portion 122a1, the shaft member 132, the bearing member 133, the actuator 134, the cable guide 135, and the screws are all disposed upstream of the virtual surface 200 in the second direction AD2. That is, none of the gear shaft portion 122a1, the shaft member 132, the bearing member 133, the actuator 134, the cable guide 135, and the screws protrudes outside the virtual surface 200 in the rotation axis direction AD. The virtual surface 200 is located at a position shifted by the plate thickness d1 in the second direction AD2 from the outer surface 123Z of the first gear cover 123 and the outer surface 123Z of the second gear cover 125.

[0076] Therefore, it is possible to minimize the clearance L1 between the outer surface 123Z and the exterior right cover 126, thereby making it possible to reduce the size of the image forming apparatus 100 in the rotation axis direction AD. For example, the clearance L1 may be determined by ensuring the plate thickness d1.

[0077] <Other embodiments> In the present embodiment, the motor 131 and the drive transmission unit 120 are provided on the right side plate 121 side, but the present invention is not limited to this. For example, the motor 131 and the drive transmission unit 120 may be provided on the left side plate 112 side.

[0078] The disclosure of the present embodiment also includes the following configuration examples and method examples. (Configuration 1) In an image forming apparatus for forming an image on a sheet, A driven member; A frame supporting the driven member; A driving source that generates a driving force; a drive transmission unit for transmitting a driving force of the drive source to the driven member, the drive transmission unit having a gear train including a first gear that rotates by the driving force from the drive source, and a gear cover that covers the gear train; the gear cover has an outer surface extending in a direction perpendicular to a rotational axis direction of the first gear, and a first recess recessed from the outer surface in a first direction parallel to the rotational axis direction, and is disposed upstream of the frame body in the first direction; the first gear has a shaft portion that passes through a first hole provided in the first recess and protrudes in a second direction opposite to the first direction with respect to the first hole, The outer surface is a surface of the gear cover facing the second direction that has the largest area in the orthogonal direction, The downstream end of the shaft portion in the second direction is the most downstream end of the gear train in the second direction, and is disposed upstream in the second direction of a virtual plane that is located at a position shifted in the second direction from the outer surface by a plate thickness of the gear cover and extends in the perpendicular direction. 1. An image forming apparatus comprising: (Configuration 2) The shaft portion is rotatably supported by the frame and the gear cover, The downstream end of the shaft portion is disposed upstream of the outer surface in the second direction with the shaft portion pressed downstream in the first direction against the frame body. 2. The image forming apparatus according to claim 1, (Configuration 3) The shaft portion is movable in the direction of the rotation axis by a predetermined distance, The predetermined distance is smaller than the plate thickness of the gear cover. 3. The image forming apparatus according to claim 1, wherein the first and second components are arranged in a same plane. (Configuration 4) the gear train includes a second gear; the drive transmission unit includes a bearing member that rotatably supports a shaft portion of the second gear, the gear cover has a second recess recessed from the outer surface in the first direction, the bearing member has a protruding portion that penetrates a second hole provided in the second recess and protrudes in the second direction relative to the second hole, A downstream end of the protrusion in the second direction is disposed upstream of the virtual plane in the second direction. 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. (Configuration 5) The gear cover is formed from sheet metal. 5. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction and a second direction. (Configuration 6) The first recess is formed by drawing. 6. The image forming apparatus according to claim 5, (Configuration 7) In an image forming apparatus for forming an image on a sheet, A driven member; A frame supporting the driven member; A driving source that generates a driving force; a drive transmission unit for transmitting a driving force of the drive source to the driven member, the drive transmission unit including a gear train including a gear rotated by the driving force from the drive source, a gear cover for covering the gear train, and a bearing member for rotatably supporting a shaft portion of the gear, the gear cover has an outer surface extending in a direction perpendicular to a rotational axis direction of the gear and a recess recessed from the outer surface in a first direction parallel to the rotational axis direction, and is disposed upstream of the frame body in the first direction; the bearing member has a protruding portion that penetrates a hole provided in the recess and protrudes in a second direction opposite to the first direction with respect to the hole, The outer surface is a surface of the gear cover facing the second direction that has the largest area in the orthogonal direction, The downstream end of the protrusion in the second direction is disposed upstream in the second direction of a virtual surface that is a virtual surface that is moved in the second direction from the outer surface by the plate thickness of the gear cover and extends in the perpendicular direction. 1. An image forming apparatus comprising: (Configuration 8) the drive transmission unit includes a biasing member that is disposed between the gear and the bearing member and biases the gear and the bearing member in directions away from each other in the rotation axis direction, The downstream end of the protrusion is located between the outer surface of the gear cover and the imaginary plane in a state in which the bearing member is pressed downstream in the second direction against the gear cover by the biasing force of the biasing member. 8. The image forming apparatus according to claim 7, (Configuration 9) A second coupling portion is provided at a downstream end portion of the gear in the first direction, the second coupling portion being engaged with the first coupling portion to transmit driving force between the first coupling portion and the second coupling portion. 9. The image forming apparatus according to claim 7 or 8. (Configuration 10) The gear cover is formed from sheet metal. 10. The image forming apparatus according to any one of configurations 7 to 9. (Configuration 11) The recess is formed by drawing. 11. The image forming apparatus according to claim 10, (Configuration 12) Further, an exterior member is provided that is disposed downstream of the outer surface in the second direction and faces the outer surface, A distance between the outer surface of the gear cover and the exterior member in the rotation axis direction is greater than the plate thickness. 12. The image forming apparatus according to any one of configurations 1 to 11. (Configuration 13) the drive transmission unit includes an actuator, a cable for supplying power to the actuator, and a cable guide for guiding the cable, the actuator, the cable, and the cable guide are disposed upstream of the imaginary plane in the second direction. 13. The image forming apparatus according to any one of configurations 1 to 12. (Configuration 14) the drive transmission unit has a screw fixed to the gear cover, The screw is disposed upstream of the virtual plane in the second direction. 14. The image forming apparatus according to any one of configurations 1 to 13. (Configuration 15) The outer surface is a surface of a downstream end of the gear cover in the second direction. 15. The image forming apparatus according to any one of configurations 1 to 14. (Configuration 16) The driving device further includes a pinion gear attached to the driving source, The pinion gear is disposed so as to overlap the gear in the rotation axis direction and is disposed upstream of the outer surface in the second direction. 16. The image forming apparatus according to any one of configurations 1 to 15. (Configuration 17) the driven member includes an image carrier that carries a toner image; 17. The image forming apparatus according to any one of configurations 1 to 16. (Configuration 18) The driven member includes a roller that conveys a sheet. 18. The image forming apparatus according to any one of configurations 1 to 17. (Configuration 19) The driving source is disposed downstream of the outer surface in the first direction. 19. The image forming apparatus according to any one of configurations 1 to 18. [Explanation of symbols]

[0079] 11: driven member, image carrier (photosensitive drum) / 100: image forming apparatus / 120: drive transmission unit / 121: frame (right side plate) / 122: gear train (first drive gear train) / 122a: first gear (gear) / 122c: gear, second gear / 122a1: shaft portion (gear shaft portion) / 122aE: downstream end / 122c2: second coupling portion (coupling portion) / 123: gear cover (first gear cover) / 123a: first recess / 123a6: first hole (hole) / 123c: recess, second recess / 123c1: hole, Second hole (hole portion) / 123Z: outer surface / 126: exterior member (exterior right cover) / 131: driving source (motor) / 132a: downstream end (first end) / 133: bearing member / 133a: protrusion / 134: actuator / 135: cable guide / 136: biasing member / 137: pinion gear / 138: cable (cable) / 150: screw / 200: imaginary surface / AD: rotation axis direction / AD1: first direction / AD2: second direction / d1: plate thickness / L2: specified distance (clearance) / PD: perpendicular direction / S: sheet

Claims

1. In an image forming apparatus for forming an image on a sheet, A driven member; A frame supporting the driven member; A driving source that generates a driving force; a drive transmission unit for transmitting a driving force of the drive source to the driven member, the drive transmission unit including a gear train including a first gear that rotates by the driving force from the drive source, and a gear cover that covers the gear train; the gear cover has an outer surface extending in a direction perpendicular to a rotational axis direction of the first gear, and a first recessed portion recessed from the outer surface in a first direction parallel to the rotational axis direction, and is disposed upstream of the frame body in the first direction; the first gear has a shaft portion that passes through a first hole provided in the first recess and protrudes in a second direction opposite to the first direction with respect to the first hole, The outer surface is a surface of the gear cover facing the second direction that has a maximum area in the orthogonal direction, The downstream end of the shaft portion in the second direction is a most downstream end of the gear train in the second direction, and is disposed upstream in the second direction of a virtual plane that is located at a position shifted in the second direction from the outer surface by a plate thickness of the gear cover and extends in the perpendicular direction.

1. An image forming apparatus comprising:

2. The shaft portion is rotatably supported by the frame and the gear cover, The downstream end of the shaft portion is disposed upstream of the outer surface in the second direction in a state in which the shaft portion is pressed downstream in the first direction against the frame body.

2. The image forming apparatus according to claim 1,

3. The shaft portion is movable in the direction of the rotation axis by a predetermined distance, The predetermined distance is smaller than the plate thickness of the gear cover.

3. The image forming apparatus according to claim 2,

4. the gear train includes a second gear; the drive transmission unit includes a bearing member that rotatably supports a shaft portion of the second gear, the gear cover has a second recess recessed from the outer surface in the first direction, the bearing member has a protruding portion that penetrates a second hole provided in the second recess and protrudes in the second direction relative to the second hole, A downstream end of the protruding portion in the second direction is disposed upstream of the imaginary plane in the second direction.

2. The image forming apparatus according to claim 1,

5. The gear cover is formed from sheet metal.

2. The image forming apparatus according to claim 1,

6. The first recess is formed by drawing.

6. The image forming apparatus according to claim 5,

7. In an image forming apparatus for forming an image on a sheet, A driven member; A frame supporting the driven member; A driving source that generates a driving force; a drive transmission unit for transmitting a driving force of the drive source to the driven member, the drive transmission unit including a gear train including a gear rotated by the driving force from the drive source, a gear cover for covering the gear train, and a bearing member for rotatably supporting a shaft portion of the gear, the gear cover has an outer surface extending in a direction perpendicular to a rotational axis direction of the gear and a recess recessed from the outer surface in a first direction parallel to the rotational axis direction, and is disposed upstream of the frame body in the first direction; the bearing member has a protruding portion that penetrates a hole provided in the recess and protrudes in a second direction opposite to the first direction with respect to the hole, The outer surface is a surface of the gear cover facing the second direction that has a maximum area in the orthogonal direction, A downstream end of the protrusion in the second direction is disposed upstream in the second direction of a virtual surface that is a virtual surface that is moved in the second direction from the outer surface by a plate thickness of the gear cover and extends in the perpendicular direction.

1. An image forming apparatus comprising:

8. the drive transmission unit includes a biasing member that is disposed between the gear and the bearing member and biases the gear and the bearing member in directions away from each other in the rotation axis direction, the downstream end of the protrusion is located between the outer surface of the gear cover and the imaginary plane in a state in which the bearing member is pressed downstream in the second direction against the gear cover by the biasing force of the biasing member; 8. The image forming apparatus according to claim 7,

9. A second coupling portion is provided at a downstream end portion of the gear in the first direction, the second coupling portion being engaged with the first coupling portion to transmit driving force between the first coupling portion and the second coupling portion.

8. The image forming apparatus according to claim 7,

10. The gear cover is formed from sheet metal.

8. The image forming apparatus according to claim 7,

11. The recess is formed by drawing.

11. The image forming apparatus according to claim 10.

12. an exterior member disposed downstream of the outer surface in the second direction and facing the outer surface; A distance between the outer surface of the gear cover and the exterior member in the rotation axis direction is greater than the plate thickness.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

13. the drive transmission unit includes an actuator, a cable for supplying power to the actuator, and a cable guide for guiding the cable, the actuator, the cable, and the cable guide are disposed upstream of the imaginary plane in the second direction.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

14. the drive transmission unit has a screw fixed to the gear cover, The screw is disposed upstream of the virtual plane in the second direction.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

15. The outer surface is a surface of a downstream end of the gear cover in the second direction.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

16. The driving device further includes a pinion gear attached to the driving source, The pinion gear is disposed so as to overlap the gear in the rotation axis direction, and is disposed upstream of the outer surface in the second direction.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

17. the driven member includes an image carrier that carries a toner image; 12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

18. The driven member includes a roller that conveys a sheet.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

19. The drive source is disposed downstream of the outer surface in the first direction.

12. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

Images