Image forming apparatus

Abstract

Provided is an image forming apparatus capable of inhibiting the influence of torque variation when a moving mechanism is driven from extending to a gear train capable of transmitting driving force from a motor to a developing roller. The image forming apparatus is provided with a YMC moving mechanism that brings the developing roller into contact with / into separation from a corresponding photosensitive drum, a K moving mechanism that brings the developing roller into contact with / into separation from the photosensitive drum, a developing motor that drives a developing drive gear, a first developing gear train that has a gear directly engaged with the developing drive gear and is capable of transmitting driving force to the developing roller, a second developing gear train that has a gear directly engaged with the developing drive gear and is capable of transmitting driving force to the developing roller, and a second control gear train that has a gear directly engaged with the developing drive gear and is capable of transmitting driving force to the K moving mechanism.

Description

Technical Field

[0001] This invention relates to an image forming apparatus comprising multiple photosensitive drums and multiple developing rollers. Background Technology

[0002] Conventionally, an image forming apparatus is known that comprises multiple photosensitive drums, multiple developing rollers capable of moving between a contact position that contacts a corresponding photosensitive drum and a separation position that leaves the corresponding photosensitive drum, a moving mechanism that moves the developing rollers between the contact position and the separation position, and a motor that provides driving force to the developing rollers and the moving mechanism.

[0003] Furthermore, Patent Document 1 discloses an image forming apparatus comprising: a first developing gear system that transmits a driving force from an electric motor to a color developing roller; a first developing contact separation gear system branching from the first developing gear system that transmits a driving force from an electric motor to a moving mechanism that contacts / separates the color developing roller; a second developing gear system that transmits a driving force from an electric motor to a monochrome developing roller; and a second developing contact separation gear system branching from the second developing gear system that transmits a driving force from an electric motor to the moving mechanism that contacts / separates the monochrome developing roller.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-224418

[0007] The technical problem that the invention aims to solve

[0008] However, in order to extend the lifespan of the developing roller and toner, the inventors of this application proposed a structure in which the developing roller sequentially exits the corresponding photosensitive drum after development, even during the printing process. In such a structure, when a conventional drive force transmission mechanism is used, the torque variation during the driving of the moving mechanism extends to the gear system. For example, uneven rotation of the gears constituting the gear system may cause instability in the rotation of the developing roller during development, thus raising concerns about image defects. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide an image forming apparatus capable of suppressing the influence of torque variation during the driving of the moving mechanism from extending to the gear train capable of transmitting the driving force from the motor to the developing roller.

[0010] Technical means for solving technical problems

[0011] To achieve the above objectives, the image forming apparatus of the present invention includes: a first photosensitive drum; a second photosensitive drum; a first developing roller movable between a contact position in contact with the first photosensitive drum and a separation position away from the first photosensitive drum; a second developing roller movable between a contact position in contact with the second photosensitive drum and a separation position away from the second photosensitive drum; a first moving mechanism that moves the first developing roller between the contact position and the separation position; a second moving mechanism that moves the second developing roller between the contact position and the separation position; a drive gear; a motor that drives the drive gear; a first gear train; a second gear train; and a third gear train.

[0012] The first gear train has a first gear that meshes directly with the drive gear and is capable of transmitting driving force from the motor to the first developing roller.

[0013] The second gear train is set independently of the first gear train, has a second gear that meshes directly with the drive gear, and is able to transmit the driving force from the motor to the second developing roller.

[0014] The third gear train is independently configured from the first and second gear trains, has a third gear that meshes directly with the drive gear, and is capable of transmitting driving force from the motor to at least one of the first moving mechanism and the second mechanism.

[0015] Based on this structure, by independently setting up a gear system that can transmit the driving force from the motor to the developing roller and a gear system that can transmit the driving force from the motor to the moving mechanism, it is possible to suppress the influence of torque variation during the driving of the moving mechanism from spreading to the gear system that can transmit the driving force from the motor to the developing roller.

[0016] In the image forming apparatus described above, the structure can be such that the drive gear is a gear disposed on the output shaft of the motor.

[0017] This reduces the number of gears, enabling miniaturization and cost reduction of the drive force transmission mechanism used to transmit the motor's driving force to the developing roller and moving mechanism. Furthermore, reducing the number of gears also reduces the loss of driving force.

[0018] In the image forming apparatus described above, there is a structure in which a third gear train can transmit driving force from a motor to a first moving mechanism, and the image forming apparatus also has a fourth gear train that is independently provided from the third gear train, has a fourth gear that directly meshes with the gears constituting the second gear train, and is able to transmit driving force from a motor to a second moving mechanism.

[0019] This allows for the suppression of the influence of torque variations during the driving of the first moving mechanism from spreading to the first and second gear trains. Furthermore, it increases the design freedom of the image forming apparatus.

[0020] Furthermore, in the image forming apparatus described above, there is a structure in which the third gear train can transmit the driving force from the motor to both the first moving mechanism and the second moving mechanism.

[0021] Therefore, it is possible to suppress the influence of torque variation when the first and second moving mechanisms are driven from spreading to the first and second gear trains.

[0022] Furthermore, the image forming apparatus described above can have the following structure: the third gear train can transmit the driving force from the motor to the first moving mechanism, and the image forming apparatus also has a fifth gear train, which is independently set apart from the third gear train, has a fifth gear that directly meshes with the drive gear, and can transmit the driving force from the motor to the second moving mechanism.

[0023] Therefore, it is possible to suppress the influence of torque variation when the first and second moving mechanisms are driven from spreading to the first and second gear trains.

[0024] The image forming apparatus described above can also be structured as follows: a third photosensitive drum; a fourth photosensitive drum; a third developing roller that is movable between a contact position in contact with the third photosensitive drum and a separation position away from the third photosensitive drum; and a fourth developing roller that is movable between a contact position in contact with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum, wherein a first gear train can transmit driving force from a motor to the first developing roller and the fourth developing roller, and a second gear train can transmit driving force from a motor to the second developing roller and the third developing roller.

[0025] Therefore, since the torque applied to the first developing gear train and the second developing gear train can be made approximately equal, at least a portion of the gears (parts) between the first and second developing gear trains can be common. This enables miniaturization and cost reduction of the drive force transmission mechanism. Furthermore, because the parts can be common, uneven rotation of the gears constituting the gear train can be suppressed, thereby enabling stable driving of the developing roller.

[0026] Alternatively, the image forming apparatus described above can also have the following structure, comprising: a third photosensitive drum; a fourth photosensitive drum; a third developing roller that is movable between a contact position in contact with the third photosensitive drum and a separation position away from the third photosensitive drum; and a fourth developing roller that is movable between a contact position in contact with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum, wherein a second gear train is capable of transmitting driving force from a motor to the second developing roller, the third developing roller, and the fourth developing roller.

[0027] This allows for greater freedom in the design of image forming devices.

[0028] The image forming apparatus described above can also be configured to include: a third photosensitive drum; a fourth photosensitive drum; a third developing roller that is movable between a contact position in contact with the third photosensitive drum and a separation position away from the third photosensitive drum; and a fourth developing roller that is movable between a contact position in contact with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum, wherein the second moving mechanism is configured to move the second developing roller, the third developing roller, and the fourth developing roller between the contact position and the separation position.

[0029] In the image forming apparatus described above, the structure can be as follows: the second developing roller, the third developing roller, and the fourth developing roller are arranged in the order of the second developing roller, the third developing roller, and the fourth developing roller from upstream to downstream in the sheet conveying direction, and the first developing roller is arranged upstream of the second developing roller or downstream of the fourth developing roller in the conveying direction.

[0030] This allows for the miniaturization or simplification of the second moving mechanism and the driving force transmission mechanism.

[0031] The effects of the invention

[0032] According to the present invention, it is possible to suppress the influence of torque variation during the driving of the moving mechanism from extending to the gear system capable of transmitting the driving force from the motor to the developing roller. Attached Figure Description

[0033] Figure 1 This is a diagram illustrating the structure of the image forming apparatus according to the embodiment.

[0034] Figure 2 This is a diagram showing the structure of the driving force transmission mechanism involved in the implementation method.

[0035] Figure 3 This is a three-dimensional view of the developing motor and developing gear system viewed from the upper right.

[0036] Figure 4 This is a diagram showing the developing motor and developing gear system viewed from the right.

[0037] Figure 5 This is a three-dimensional view of the developing motor, drive force transmission mechanism, and moving mechanism, viewed from the upper right.

[0038] Figure 6 This is a diagram showing the developing motor, drive force transmission mechanism, and moving mechanism from the right side.

[0039] Figure 7 These are perspective views (a) and side views (b) showing the cam, cam follower, clutch, and limiting components of the developing roller when it is in the contact position.

[0040] Figure 8 These are diagrams (a) and (b) showing the structure around the developing chamber as viewed from above.

[0041] Figure 9 These are exploded perspective views of the clutch viewed from the sun gear side (a) and exploded perspective views of the clutch viewed from the gear carrier side (b).

[0042] Figure 10 These are perspective views (a) and side views (b) showing the cam, cam follower, clutch, and limiting components of the developing roller in the separation position.

[0043] Figure 11 This is a diagram showing the structure of the driving force transmission mechanism involved in the first variation.

[0044] Figure 12 This is a diagram showing the structure of the driving force transmission mechanism involved in the second variation.

[0045] Figure 13 This is a diagram showing the structure of the driving force transmission mechanism involved in the third variation.

[0046] Figure 14 This is a diagram showing the structure of the driving force transmission mechanism involved in the fourth variation.

[0047] Symbol Explanation

[0048] 1 Image forming apparatus

[0049] 3D developing motor

[0050] 5A YMC Mobile Agency

[0051] 5K K Mobile Agency

[0052] 50K K Photosensitive Drum

[0053] 50Y Y Photosensitive Drum

[0054] 61K K developing roller

[0055] 61Y Y developing roller

[0056] 100G developer drive gear

[0057] 100A First Developing Gear System

[0058] 100B Second Developing Gear System

[0059] 100D Second Control Gear System

[0060] 110A Idle Gear

[0061] 110B Idle Gear

[0062] 132A Idle Gear Detailed Implementation

[0063] like Figure 1 As shown, the image forming apparatus 1 according to the embodiment is a color printer, comprising a housing 10, a sheet supply unit 20, an image forming unit 30, and a control unit 2. Furthermore, in this embodiment, Figure 1 The left side is considered front, the right side is considered back, and the top and bottom are directly used as top and bottom, and... Figure 1 The front side of the paper is designated as right, and the inside side of the paper is designated as left.

[0064] The sheet supply unit 20 includes a sheet tray 21 for placing sheets S and a supply mechanism 22. The sheet tray 21 is located below the image forming unit 30 and can be pulled out and removed from the front side of the housing 10. The supply mechanism 22 includes a paper feed roller 23, a separation roller 24, a separation pad 25, a transport roller 26, and a registration roller 27. The sheet S is a medium for forming an image by the image forming apparatus 1, including plain paper, envelopes, postcards, thin paper, thick paper, glossy paper, resin sheets, and stickers, etc.

[0065] After being fed out by the feed roller 23, the sheet S housed in the sheet tray 21 is separated one by one between the separating roller 24 and the separating pad 25, and then conveyed toward the registration roller 27 by the conveying roller 26. Subsequently, after being restricted at the leading edge of the sheet S by the registration roller 27, which is in a stopped state, the sheet S is supplied to the image forming unit 30 by the rotation of the registration roller 27.

[0066] The image forming unit 30 includes an exposure device 40, multiple photosensitive drums 50, multiple developing cartridges 60, a transport device 70, and a fuser 80.

[0067] The exposure apparatus 40 includes a laser diode (not shown), a deflector, a lens, and a mirror. The exposure apparatus 40 is configured to emit multiple light beams (represented by a dashed line) to expose the surfaces of multiple photosensitive drums 50.

[0068] The plurality of photosensitive drums 50 include a Y photosensitive drum 50Y corresponding to yellow, an M photosensitive drum 50M corresponding to magenta, a C photosensitive drum 50C corresponding to cyan, and a K photosensitive drum 50K corresponding to black. In this embodiment, the Y photosensitive drum 50Y is equivalent to the "second photosensitive drum", the M photosensitive drum 50M is equivalent to the "third photosensitive drum", the C photosensitive drum 50C is equivalent to the "fourth photosensitive drum", and the K photosensitive drum 50K is equivalent to the "first photosensitive drum". Furthermore, in this specification and the accompanying drawings, for components provided corresponding to each color, the symbols Y, M, C, and K are used to indicate them when the color is distinguished; otherwise, the symbols Y, M, C, and K are not used for explanation.

[0069] Each developing cartridge 60 is configured in a corresponding manner to one of the multiple photosensitive drums 50. The multiple developing cartridges 60 include a Y developing cartridge 60Y having a Y developing roller 61Y that supplies toner to the Y photosensitive drum 50Y, an M developing cartridge 60M having an M developing roller 61M that supplies toner to the M photosensitive drum 50M, a C developing cartridge 60C having a C developing roller 61C that supplies toner to the C photosensitive drum 50C, and a K developing cartridge 60K having a K developing roller 61K that supplies toner to the K photosensitive drum 50K.

[0070] The Y-developing roller 61Y, M-developing roller 61M, and C-developing roller 61C are arranged in the order of Y-developing roller 61Y, M-developing roller 61M, and C-developing roller 61C, moving from upstream to downstream in the conveying direction of the sheet S. Additionally, the K-developing roller 61K is arranged downstream of the C-developing roller 61C in the conveying direction of the sheet S. In this embodiment, the Y-developing roller 61Y corresponds to the "second developing roller," the M-developing roller 61M corresponds to the "third developing roller," the C-developing roller 61C corresponds to the "fourth developing roller," and the K-developing roller 61K corresponds to the "first developing roller."

[0071] Each developing cartridge 60 is movable between a position where the developing roller 61 is in contact with the corresponding photosensitive drum 50 (refer to the solid line) and a position where the developing roller 61 is away from the corresponding photosensitive drum 50 (refer to the imaginary line). Specifically, the Y developing roller 61Y relative to the Y photosensitive drum 50Y is movable between the contact and separation positions, the M developing roller 61M relative to the M photosensitive drum 50M is movable between the contact and separation positions, and the C developing roller 61C relative to the C photosensitive drum 50C is movable between the contact and separation positions. Additionally, the K developing roller 61K relative to the K photosensitive drum 50K is movable between the contact and separation positions.

[0072] Multiple photosensitive drums 50 are rotatably supported on a support member 55. A charge switch 52 is provided on the support member 55, which is configured corresponding to each photosensitive drum 50 for energizing the photosensitive drum 50. The support member 55 can be installed and removed from the housing 10 through an opening formed by opening the front cover 11 of the housing 10. Furthermore, the support member 55 supports multiple developing cartridges 60 in a removable manner.

[0073] A conveyor 70 is disposed between the sheet tray 21 and multiple photosensitive drums 50. The conveyor 70 includes a drive roller 71, a driven roller 72, an annular belt (conveyor belt) 73, and four transfer rollers 74. The conveyor belt 73 is tautly disposed between the drive roller 71 and the driven roller 72, with its outer surface in contact with each photosensitive drum 50. Each transfer roller 74 is disposed on the inner side of the conveyor belt 73, clamping the conveyor belt 73 between itself and each photosensitive drum 50.

[0074] The fuser 80 is located behind the plurality of photosensitive drums 50 and the transport device 70. The fuser 80 includes a heating roller 81 and a pressure roller 82 arranged opposite to the heating roller 81. A transport roller 15 and a discharge roller 16 are provided on the downstream side of the fuser 80 in the transport direction of the sheet S.

[0075] In the image forming unit 30, the surface of the photosensitive drum 50 is similarly charged by the charge carrier 52 and then exposed by a light beam irradiated from the exposure device 40. As a result, an electrostatic latent image based on image data is formed on the photosensitive drum 50. Furthermore, toner housed in the developing cartridge 60 is carried on the surface of the developing roller 61 and supplied from the developing roller 61, located at a contact position, to the electrostatic latent image formed on the photosensitive drum 50. Thus, a toner image is formed on the photosensitive drum 50.

[0076] The sheet S supplied to the conveyor belt 73 is conveyed on the conveyor belt 73 and passes between the photosensitive drum 50 and the transfer roller 74, thereby transferring the toner image formed on the photosensitive drum 50 to the sheet S. Furthermore, the sheet S passes between the heating roller 81 and the pressure roller 82, thereby thermally fixing the toner image onto the sheet S. Subsequently, the sheet S is discharged onto the paper discharge tray 13 via the conveyor roller 15 and the discharge roller 16.

[0077] like Figure 2 As shown, the image forming apparatus 1 also includes a developing motor 3D, a YMC moving mechanism 5A, a K moving mechanism 5K, and a driving force transmission mechanism 100.

[0078] The developing motor 3D is a drive source that drives the developing roller 61 and the cams 150 (150Y, 150M, 150C, 150K) of the moving mechanisms 5A and 5K by driving the developing drive gear 100G. In this embodiment, the developing motor 3D is equivalent to a "motor".

[0079] The YMC moving mechanism 5A is configured to move the Y developing roller 61Y, M developing roller 61M, and C developing roller 61C between a contact position and a separation position, and includes a Y cam 150Y, an M cam 150M, and a C cam 150C. The K moving mechanism 5K is configured to move the K developing roller 61K between a contact position and a separation position, and includes a K cam 150K. In this embodiment, the YMC moving mechanism 5A corresponds to the "second moving mechanism," and the K moving mechanism 5K corresponds to the "first moving mechanism."

[0080] The drive force transmission mechanism 100 is configured to transmit the driving force from the developing motor 3D to the developing roller 61 and the cam 150. The drive force transmission mechanism 100 includes a developing drive gear 100G, a first developing gear system 100A, a second developing gear system 100B, a first control gear system 100C, and a second control gear system 100D. Furthermore, in... Figure 2 In the diagram, developing gear systems 100A and 100B are represented by thick dashed lines, and control gear systems 100C and 100D are represented by thick solid lines. In this embodiment, the developing drive gear 100G is equivalent to a "drive gear", the first developing gear system 100A is equivalent to a "second gear system", the second developing gear system 100B is equivalent to a "first gear system", the first control gear system 100C is equivalent to a "fourth gear system", and the second control gear system 100D is equivalent to a "third gear system".

[0081] The first developing gear system 100A is a gear system capable of transmitting driving force from the developing motor 3D to the Y developing roller 61Y and the M developing roller 61M, and the second developing gear system 100B is a gear system capable of transmitting driving force from the developing motor 3D to the C developing roller 61C and the K developing roller 61K. The first developing gear system 100A and the second developing gear system 100B are independently configured.

[0082] The first control gear system 100C is a gear system capable of transmitting driving force from the developing motor 3D to the cams 150Y, 150M, and 150C constituting the YMC moving mechanism 5A. The second control gear system 100D is a gear system capable of transmitting driving force from the developing motor 3D to the K cam 150K constituting the K moving mechanism 5K. The first control gear system 100C and the second control gear system 100D are independently provided. In addition, the first control gear system 100C is provided in a manner that branches from the first developing gear system 100A, and the second control gear system 100D is independently provided from the first developing gear system 100A and the second developing gear system 100B.

[0083] The detailed structure of the drive force transmission mechanism 100 and the moving mechanisms 5A and 5K will be described below. Furthermore, in... Figure 3 and Figure 4 In the text, it mainly refers to the developing gear system 100A and 100B. Figure 5 and Figure 6 In the diagram, the main features are the control gear systems 100C and 100D and the moving mechanisms 5A and 5K, which are located to the right of the developing gear systems 100A and 100B. Additionally, in... Figure 4 and Figure 6 In the diagram, thick solid lines represent the meshing between the gears that make up the gear system.

[0084] like Figure 3 and Figure 4 As shown, the developing drive gear 100G is a gear mounted on the output shaft 3A of the developing motor 3D. The developing drive gear 100G rotates integrally with the output shaft 3A under the drive of the developing motor 3D.

[0085] The first developing gear system 100A includes idle speed gears 110A, 113A, 115Y, 115M, Y clutch 120Y, M clutch 120M, Y connecting gear 117Y, and M connecting gear 117M. In this embodiment, the idle speed gear 110A is equivalent to the "second gear".

[0086] The idle speed gear 110A is a gear that directly meshes with the developer drive gear 100G and is located on the front side of the developer drive gear 100G.

[0087] The idle speed gear 113A is located on the lower side of the idle speed gear 110A and directly meshes with the idle speed gear 110A.

[0088] The idle speed gear 115Y is located on the front side of the idle speed gear 113A and meshes directly with the idle speed gear 113A.

[0089] Y-clutch 120Y is located below idle speed gear 115Y and directly meshes with it. Furthermore, the structure of clutches 120 (120Y, 120M, 120C, 120K) will be described later.

[0090] Y-connecting gear 117Y is a gear that outputs the driving force input from the developing motor 3D to the idle speed gear 110A to the Y developing roller 61Y. Y-connecting gear 117Y is positioned in front of the Y clutch 120Y and directly meshes with it. The driving force from the developing motor 3D is transmitted to Y-connecting gear 117Y via the idle speed gears 110A, 113A, 115Y, and the Y clutch 120Y.

[0091] The idle speed gear 115M is located on the rear side of the idle speed gear 113A and meshes directly with the idle speed gear 113A.

[0092] The M clutch 120M is located on the lower side of the idle speed gear 115M and directly meshes with it.

[0093] M-connecting gear 117M is a gear that outputs the driving force input from the developing motor 3D to the idle speed gear 110A to the developing roller 61M. M-connecting gear 117M is positioned in front of the M clutch 120M and directly meshes with it. The driving force from the developing motor 3D is transmitted to M-connecting gear 117M via the idle speed gears 110A, 113A, 115M and the M clutch 120M.

[0094] The second developing gear system 100B includes idle speed gears 110B, 113B, 115C, 113C, 115K, C clutch 120C, K clutch 120K, C connecting gear 117C, and K connecting gear 117K. In this embodiment, the idle speed gear 110B is equivalent to the "first gear".

[0095] The idle speed gear 110B is a gear that directly meshes with the developing drive gear 100G and is located on the rear side of the developing drive gear 100G.

[0096] The idle speed gear 113B is located below the idle speed gear 110B and meshes directly with the idle speed gear 110B.

[0097] The idle speed gear 115C is located on the rear side of the idle speed gear 113B and meshes directly with the idle speed gear 113B.

[0098] Clutch 120C is located on the lower side of idle gear 115C and directly meshes with idle gear 115C.

[0099] C-connecting gear 117C is a gear that outputs the driving force input from the developing motor 3D to the idle speed gear 110B to the developing roller 61C. C-connecting gear 117C is located in front of the C clutch 120C and directly meshes with it. The driving force from the developing motor 3D is transmitted to C-connecting gear 117C via the idle speed gears 110B, 113B, 115C, and the C clutch 120C.

[0100] The idle speed gear 113C is located behind the idle speed gear 115C and meshes directly with the idle speed gear 115C.

[0101] The idle speed gear 115K is located on the rear side of the idle speed gear 113C and meshes directly with the idle speed gear 113C.

[0102] The K clutch 120K is located on the lower side of the idle speed gear 115K and directly meshes with it.

[0103] The K-connecting gear 117K is a gear that outputs the driving force input from the developing motor 3D to the idle speed gear 110B to the K developing roller 61K. The K-connecting gear 117K is located in front of the K clutch 120K and directly meshes with the K clutch 120K. The driving force from the developing motor 3D is transmitted to the K-connecting gear 117K via the idle speed gears 110B, 113B, 115C, 113C, 115K and the K clutch 120K.

[0104] Each connecting gear 117 has a coaxial and integrally rotating connecting shaft 119. The connecting shaft 119 and the front cover 11 (see reference) Figure 1 The opening and closing linkage of the connecting shaft 119 allows it to move axially along the developing roller 61. When the front cover 11 is closed, the connecting shaft 119 engages with a coupling (not shown) of the developing cartridge 60. When the connecting shaft 119 is engaged with the coupling of the developing cartridge 60, the rotating connecting gear 117 transmits the driving force from the developing motor 3D to the developing roller 61, thereby causing the developing roller 61 to rotate.

[0105] like Figure 5 and Figure 6 As shown, the first control gear system 100C includes idle gears 131A and 131B, a YMC electromagnetic clutch 140A, idle gears 133A and 134A, a Y cam 150Y (gear section 150G), an idle gear 135, an M cam 150M (gear section 150G), an idle gear 136, and a C cam 150C (gear section 150G). In this embodiment, the idle gear 131A corresponds to the "fourth gear".

[0106] The idle speed gear 131A is a gear that directly meshes with the idle speed gear 110A, which constitutes the first developing gear system 100A, and is located on the front side of the idle speed gear 110A. The idle speed gear 131A does not directly mesh with the developing drive gear 100G.

[0107] The idle speed gear 131B is located on the front side of the idle speed gear 131A and meshes directly with the idle speed gear 131A.

[0108] The YMC electromagnetic clutch 140A is located on the front side of the idle speed gear 131A. The YMC electromagnetic clutch 140A has a large diameter gear 140L and a small diameter gear 140S, with the large diameter gear 140L directly meshing with the idle speed gear 131B.

[0109] The idle speed gear 133A is located on the lower side of the YMC electromagnetic clutch 140A and directly meshes with the small diameter gear 140S of the YMC electromagnetic clutch 140A.

[0110] The idle speed gear 134A is located behind the idle speed gear 133A and meshes directly with the idle speed gear 133A. In addition, the idle speed gear 134A meshes directly with the gear section 150G of the Y cam 150Y located at the rear.

[0111] The idle speed gear 135 is positioned between the Y cam 150Y and the M cam 150M, and directly meshes with the gear section 150G of the Y cam 150Y and the gear section 150G of the M cam 150M.

[0112] The idle speed gear 136 is disposed between the M cam 150M and the C cam 150C, and directly meshes with the gear section 150G of the M cam 150M and the gear section 150G of the C cam 150C.

[0113] The driving force from the developing motor 3D is transmitted to the Y cam 150Y via idle gears 110A, 131A, 131B, the YMC electromagnetic clutch 140A, and idle gears 133A and 134A. The driving force from the Y cam 150Y is transmitted to the M cam 150M via idle gear 135. The driving force from the M cam 150M is transmitted to the C cam 150C via idle gear 136.

[0114] The second control gear system 100D includes idle speed gears 132A, 132B, 132C, 132D, an electromagnetic clutch 140K, and idle speed gears 133B and 134B. In this embodiment, idle speed gear 132A is equivalent to a "third gear".

[0115] The idle speed gear 132A is a gear that directly meshes with the developing drive gear 100G and is located on the rear side of the developing drive gear 100G. In addition, the idle speed gear 132A is located on the right side of the idle speed gear 110B that constitutes the second developing gear system 100B.

[0116] The idle speed gear 132B is located behind the idle speed gear 132A and meshes directly with the idle speed gear 132A.

[0117] The idle speed gear 132C is located behind the idle speed gear 132B and meshes directly with the idle speed gear 132B.

[0118] The idle speed gear 132D is located behind the idle speed gear 132C and meshes directly with the idle speed gear 132C.

[0119] The K electromagnetic clutch 140K is located behind the idle speed gear 132D. The K electromagnetic clutch 140K has a large diameter gear 140L and a small diameter gear 140S, with the large diameter gear 140L directly meshing with the idle speed gear 132D.

[0120] The idle speed gear 133B is located on the rear side of the K electromagnetic clutch 140K and directly meshes with the small diameter gear 140S of the K electromagnetic clutch 140K.

[0121] The idle speed gear 134B is located on the rear lower side of the idle speed gear 133B and directly meshes with the idle speed gear 133B. In addition, the idle speed gear 134B directly meshes with the gear portion 150G of the K cam 150K located on the lower side.

[0122] The driving force from the developing motor 3D is transmitted to the cam 150K via the idle gears 132A-132D, the electromagnetic clutch 140K, and the idle gears 133B and 134B.

[0123] Electromagnetic clutches 140A and 140K switch the rotation and stop of the corresponding cam 150 by switching the transmission and disengagement of driving force. Specifically, when electromagnetic clutches 140A and 140K are energized, the large-diameter gear 140L and the small-diameter gear 140S rotate as a unit. This transmits driving force, causing the corresponding cam 150 to rotate. Conversely, when electromagnetic clutches 140A and 140K are de-energized and disengaged, the large-diameter gear 140L idles relative to the loaded small-diameter gear 140S, while the small-diameter gear 140S does not rotate. This disconnects the transmission of driving force, causing the corresponding cam 150 to stop. The engagement / disengagement of electromagnetic clutches 140A and 140K is independently controlled by the control unit 2.

[0124] The YMC moving mechanism 5A has cams 150Y, 150M, and 150C and multiple cam followers 170 corresponding to each cam 150. The K moving mechanism 5K has a K cam 150K and cam followers 170 corresponding to the K cam 150K.

[0125] The cam 150 is a component that moves the corresponding developing roller 61 between a contact position and a separation position by rotating it. For example... Figure 7 As shown, each cam 150 has a circular plate portion 151, a gear portion 150G formed on the outer periphery of the circular plate portion 151, a first cam portion 152, and a second cam portion 153.

[0126] The first cam portion 152 is the portion that moves the developing roller 61 between a contact position and a separation position, and protrudes axially from the side of the circular plate portion 151 toward the developing roller 61. The first cam portion 152 has a cam surface 152F on its axial end face. The cam surface 152F has a first holding surface F1, a second holding surface F2, a first guide surface F3, and a second guide surface F4.

[0127] The first holding surface F1 is the surface that holds the cam follower 170 in the standby position (described later), and the second holding surface F2 is the surface that holds the cam follower 170 in the protruding position (described later). Figure 7 In the diagram, the dotted section line marked on the first cam portion 152 represents the second retaining surface F2. The first guide surface F3 is a surface that connects the first retaining surface F1 and the second retaining surface F2 and is inclined relative to the first retaining surface F1. The second guide surface F4 is a surface that connects the second retaining surface F2 and the first retaining surface F1 and is inclined relative to the first retaining surface F1.

[0128] The second cam portion 153 is the part that cooperates with the limiting member 160 (described later) to switch the state of the clutch 120, and it protrudes axially toward the developing roller 61 from the side of the circular plate portion 151 opposite to the side where the first cam portion 152 is disposed. Viewed axially, the second cam portion 153 extends in a generally arcuate shape.

[0129] The cam follower 170 has a sliding shaft portion 171, a contact portion 172, and a spring hook portion 174.

[0130] The sliding shaft portion 171 is slidably supported on the support shaft 179 provided in the housing 10 (see reference 179) in the axial direction of the developing roller 61. Figure 8 (b) Thus, the cam follower 170 is able to slide axially.

[0131] The contact portion 172 is a portion capable of contacting the cam surface 152F of the first cam portion 152, and extends from the sliding shaft portion 171. The cam follower 170 is capable of... Figure 8 The prominent position shown in (b) is the same as Figure 8 The developing roller 61 moves between the standby positions shown in (a), the protruding position is the position where the contact part 172 contacts the second holding surface F2 and the developing roller 61 is in the separation position, and the standby position is the position where the contact part 172 contacts the first holding surface F1 and the developing roller 61 is in the contact position.

[0132] Return to Figure 7 The spring hook portion 174 is a portion for hooking one end of the spring 176, and extends from the sliding shaft portion 171 in a direction different from the contact portion 172. The spring 176 is a tension spring, and the other end of the spring 176 is hooked to the spring hook portion (not shown), which is located on the outer casing 10 below and to the left of the spring hook portion 174. The spring 176 exerts force on the cam follower 170 from the protruding position toward the standby position.

[0133] like Figure 8As shown, the developing cartridge 60 is movably supported on the support member 55. The support member 55 has an abutting portion 55A and a pressing member 55B. The abutting portion 55A is the portion that abuts against the sliding member 66 described later, and is composed of a roller that can rotate about an axis along the vertical axis. The pressing member 55B is forced rearward by a spring 55C, and when the developing cartridge 60 is assembled on the support member 55, pressing the developing cartridge 60 causes the developing roller 61 to move towards a contact position that contacts the corresponding photosensitive drum 50.

[0134] The developing cartridge 60 has a housing 65 for containing toner and a sliding member 66. The sliding member 66 is a component that can slide relative to the housing 65 in the axial direction of the developing roller 61, and is axially slidable by being pressed by the cam follower 170. The sliding member 66 has a shaft 66A that is slidably supported on the housing 65, a first abutting member 66B provided at one end of the shaft 66A, and a second abutting member 66C provided at the other end of the shaft 66A.

[0135] The first abutting member 66B has a pressing surface 66D and an inclined surface 66E that is inclined relative to the axial direction. The second abutting member 66C has an inclined surface 66F that is inclined in the same direction as the inclined surface 66E. The pressing surface 66D is pressed by the cam follower 170. When the sliding member 66 is pressed by the cam follower 170, the inclined surfaces 66E and 66F abut against the abutted portion 55A, exerting force on the developing cartridge 60 in a direction orthogonal to the axial direction, and moving the developing roller 61 toward a separation position away from the corresponding photosensitive drum 50. A spring 67 is disposed between the first abutting member 66B and the housing 65 to exert force on the sliding member 66 toward the left.

[0136] like Figure 9 As shown, clutch 120 is a component capable of switching between a transmission state and a disengagement state. In the transmission state, it inputs to idle gears 110A and 110B (see reference). Figure 4 The driving force of the clutch 120 is transmitted to the corresponding developing roller 61. In the cut-off state, the driving force input to the idle gears 110A and 110B is transmitted to the corresponding developing roller 61. The clutch 120 has a planetary gear mechanism. Specifically, the clutch 120 has a sun gear 121, a ring gear 122, a gear carrier 123, and a planetary gear 124 supported on the gear carrier 123, which are elements capable of rotating about a central axis.

[0137] The sun gear 121 has a gear portion 121A, a rotating plate 121B that rotates integrally with the gear portion 121A, and a claw portion 121C disposed on the outer periphery of the rotating plate 121B.

[0138] The gear ring 122 has an internal gear 122A disposed on its inner circumferential surface and an input gear 122B disposed on its outer circumferential surface. The input gear 122B and the idle speed gears 115 (115Y, 115M, 115C, 115K) (see reference) Figure 4 Direct meshing.

[0139] The gear carrier 123 has four shaft portions 123A that rotatably support the planetary gear 124 and an output gear 123B disposed on its outer peripheral surface. The output gear 123B and the connecting gears 117 (117Y, 117M, 117C, 117K) (see reference) Figure 4 Direct meshing.

[0140] The gear set includes four planetary gears 124, each of which is rotatably supported on the shaft portion 123A of the gear carrier 123. The planetary gears 124 mesh with the gear portion 121A of the sun gear 121 and with the internal gear 122A of the gear ring 122.

[0141] When the rotation of the sun gear 121 is restricted, the clutch 120 is in a state where it can transmit the driving force input to the input gear 122B to the output gear 123B. On the other hand, when the sun gear 121 can rotate, the clutch 120 is in a disengaged state where it cannot transmit the driving force input to the input gear 122B to the output gear 123B. When the clutch 120 is in the disengaged state and the output gear 123B is under load, and driving force is input to the input gear 122B, the output gear 123B does not rotate and the sun gear 121 idles.

[0142] like Figure 7 As shown, the drive force transmission mechanism 100 also includes a limiting member 160. Multiple limiting members 160 are provided corresponding to each clutch 120. Each limiting member 160 has a rotary support portion 162A, a first arm 161C extending from the rotary support portion 162A, and a second arm 162C extending from the rotary support portion 162A in a direction different from the first arm 161C.

[0143] The rotatable support 162A is rotatably supported on a support shaft (not shown) provided in the housing 10.

[0144] The top of the second arm 162C extends toward the outer peripheral surface of the sun gear 121. A spring hook portion 162E is provided on the second arm 162C, and one end of a spring 169 is hooked onto the spring hook portion 162E. The spring 169 is a tension spring, and its other end is hooked onto a spring hook portion (not shown) located on the housing 10, positioned forward of the spring hook portion 162E. Thus, the spring 169 exerts force on the restraining member 160 in a clockwise direction as shown in the figure, from the disengaged position toward the engaged position.

[0145] The limiting member 160 can swing between an engaged position and a disengaged position. The engaged position is when the tip of the second arm 162C engages with the pawl 121C of the sun gear 121, thus limiting the rotation of the sun gear 121. The disengaged position is when the tip of the second arm 162C disengages from the pawl 121C, thus no longer limiting the rotation of the sun gear 121 (see reference). Figure 10 ).

[0146] Furthermore, the tip of the first arm 161C of the limiting member 160 can contact the second cam portion 153. When the tip of the first arm 161C disengages from the second cam portion 153, the limiting member 160 is in the engaged position due to the force applied by the spring 169. When the tip of the first arm 161C contacts the second cam portion 153 (see reference...), the limiting member 160 is in the engaged position. Figure 10 The limiting member 160 swings against the force applied by the spring 169, thereby being in the disengaged position.

[0147] The second cam portion 153 is configured such that before the developing roller 61, moving from the separation position toward the contact position, contacts the corresponding photosensitive drum 50, the limiting member 160 is in the engaged position, thereby putting the clutch 120 into a transmission state; and after the developing roller 61, moving from the contact position toward the separation position, leaves the photosensitive drum 50, the limiting member 160 is in the disengaged position, thereby putting the clutch 120 into a disengaged state. Thus, the developing roller 61 rotates when in the contact position and stops when in the separation position.

[0148] The control unit 2 is a device that controls the operation of the image forming apparatus 1. The control unit 2 includes a CPU, ROM, RAM, and input / output unit, and executes various processes by executing pre-stored programs. The control unit 2 controls the drive of the developing motor 3D, and controls the movement of the cam 150 by controlling the engagement / disengagement of the electromagnetic clutches 140A and 140K, thereby controlling the drive / stop of the developing roller 61 and the contact / separation of the developing roller 61 relative to the corresponding photosensitive drum 50.

[0149] Here, an example of the processing of control unit 2 will be explained.

[0150] In the standby state before the image forming apparatus 1 performs image forming, all display rollers 61 are in the separated position. At this time, as... Figure 10 As shown, the cam follower 170 is located at the protruding position of the second retaining surface F2 of the contact portion 172 that contacts the cam 150.

[0151] When a printing job is input and image formation is performed, the control unit 2 drives the developing motor 3D and engages the YMC electromagnetic clutches 140A and 140K according to the color of the toner used for image formation, thereby causing the cam 150 to rotate clockwise as shown in the figure. As a result, the contact portion 172 of the cam follower 170 is guided from the second holding surface F2 to the second guide surface F4, making sliding contact on the second guide surface F4, and so on... Figure 7 As shown, it contacts the first retaining surface F1. Therefore, the cam follower 170, under the force applied by the spring 176, moves from... Figure 8 The prominent position shown in (b) is towards Figure 8 The standby position shown in (a) is slidably moved, and the developing roller 61 moves from the separation position to the contact position. When the display roller 61 moves to the contact position, the control unit 2 disengages the YMC electromagnetic clutch 140A and the K electromagnetic clutch 140K, thereby stopping the cam 150.

[0152] When development based on display roller 61 is completed, control unit 2 engages YMC electromagnetic clutch 140A and K electromagnetic clutch 140K, causing cam 150 to rotate. Figure 7 The contact portion 172 is then rotated clockwise again. As a result, the contact portion 172 is guided from the first holding surface F1 to the first guiding surface F3, slides on the first guiding surface F3, and... Figure 10 As shown, it contacts the second retaining surface F2. Therefore, the cam follower 170 moves from... Figure 8 The standby position shown in (a) is towards Figure 8 As shown in (b), the developing roller 61 slides from the contact position to the separation position. When the developing roller 61 moves to the separation position, the control unit 2 disengages the YMC electromagnetic clutch 140A and the K electromagnetic clutch 140K, thereby stopping the cam 150.

[0153] According to the above-described embodiment, by independently providing developing gear systems 100A and 100B capable of transmitting driving force from developing motor 3D to developing roller 61 and a second control gear system 100D capable of transmitting driving force from developing motor 3D to K moving mechanism 5K, the influence of torque variation when driving K moving mechanism 5K can be suppressed from spreading to developing gear systems 100A and 100B.

[0154] Furthermore, since the developing drive gear 100G is a gear located on the output shaft 3A of the developing motor 3D, the number of gears can be reduced compared to situations where there are other gears between the developing drive gear and the gear located on the output shaft of the developing motor. This allows for miniaturization and cost reduction of the drive force transmission mechanism 100, which transmits the driving force of the developing motor 3D to the developing roller 61, the moving mechanisms 5A and 5K. Additionally, by reducing the number of gears, friction acting on the shafts on which the gears are located, friction between the gears and the shafts supporting those gear shafts, and friction between the teeth of the meshing gears can be reduced, thus reducing the loss of driving force.

[0155] Furthermore, since the first control gear system 100C, which can transmit the driving force from the developing motor 3D to the YMC moving mechanism 5A, is configured to branch off from the first developing gear system 100A, the independent configuration of the first control gear system and the first developing gear system 100A, compared to the case where the driving force is directly input from the developing drive gear 100G, allows for greater freedom in the arrangement of the developing drive gear 100G and the developing motor 3D. This, in turn, increases the design freedom of the image forming apparatus 1.

[0156] Furthermore, since the first developing gear system 100A can transmit the driving force from the developing motor 3D to the two developing rollers 61Y and 61M, and the second developing gear system 100B can similarly transmit the driving force from the developing motor 3D to the two developing rollers 61C and 61K, the torque applied to the idler gears 110A and 110B can be suppressed from increasing compared to a structure where one developing gear system can transmit the driving force to three of the four developing rollers. Therefore, gear tooth deformation can be suppressed without increasing the tooth width of the idler gears 110A and 110B. In addition, since the torque applied to the first developing gear system 100A and the second developing gear system 100B can be made approximately equal, at least a portion of the gears (parts) between the first developing gear system 100A and the second developing gear system 100B can be common. This enables miniaturization and cost reduction of the driving force transmission mechanism 100. Furthermore, since the parts can be made common, uneven rotation of the gears constituting the developing gear system 100A and 100B can be suppressed, thereby enabling the developing roller 61 to be driven stably.

[0157] Furthermore, since the YMC moving mechanism 5A is a structure that moves three developing rollers 61Y, 61M, and 61C, and the four developing rollers 61Y, 61M, 61C, and 61K are arranged in this order from upstream to downstream in the conveying direction of the sheet S, for example, compared to the case where the K developing roller 61K is arranged between the Y developing roller 61Y and the M developing roller 61M, and between the M developing roller 61M and the C developing roller 61C, the YMC moving mechanism 5A and the drive force transmission mechanism 100 can be miniaturized, resulting in a simpler structure.

[0158] Although the embodiments have been described above, the present invention is not limited to the above embodiments and can be implemented by appropriate modifications as illustrated below. Furthermore, in the following description, the same reference numerals are used for the same constituent elements as previously described, and their descriptions are omitted.

[0159] In the above embodiments, such as Figure 2 As shown, the first control gear system 100C for color is configured to branch from the first developing gear system 100A. The first control gear system 100C can transmit the driving force from the developing motor 3D to the YMC moving mechanism 5A. The second control gear system 100D for monochrome is configured independently from the first developing gear system 100A and the second developing gear system 100B. The second control gear system 100D can transmit the driving force from the developing motor 3D to the K moving mechanism 5K, but is not limited to this.

[0160] For example, such as Figure 1 As shown, alternatively, the first control gear system 100C for color processing can be independently configured with the first developing gear system 100A and the second developing gear system 100B, and the second control gear system 100D for monochrome processing can be configured to branch off from the second developing gear system 100B. In this case, the first control gear system 100C has an idle gear 130A that directly meshes with the developing drive gear 100G, and the second control gear system 100D has an idle gear 130B that directly meshes with, for example, an idle gear 110B constituting the second developing gear system 100B.

[0161] In this configuration, the Y-type photosensitive drum 50Y corresponds to the "first photosensitive drum," the K-type photosensitive drum 50K corresponds to the "second photosensitive drum," the Y-type developing roller 61Y corresponds to the "first developing roller," the K-type developing roller 61K corresponds to the "second developing roller," the YMC moving mechanism 5A corresponds to the "first moving mechanism," and the K-type moving mechanism 5K corresponds to the "second moving mechanism." Additionally, the first developing gear system 100A corresponds to the "first gear system," the idle speed gear 110A corresponds to the "first gear," the second developing gear system 100B corresponds to the "second gear system," the idle speed gear 110B corresponds to the "second gear," the first control gear system 100C corresponds to the "third gear system," the idle speed gear 130A corresponds to the "third gear," the second control gear system 100D corresponds to the "fourth gear system," and the idle speed gear 130B corresponds to the "fourth gear."

[0162] In addition, such as Figure 12 , Figure 13 As shown, the first control gear system 100C for color and the second control gear system 100D for monochrome can also be set independently from the first developing gear system 100A and the second developing gear system 100B.

[0163] For example, in Figure 12 In the illustrated configuration, the first control gear system 100C for color applications is a gear system capable of transmitting driving force from the developing motor 3D to the YMC moving mechanism 5A, and the second control gear system 100D for monochrome applications is a gear system capable of transmitting driving force from the developing motor 3D to the K moving mechanism 5K. The first control gear system 100C and the second control gear system 100D are independently configured. The first control gear system 100C has an idle gear 130A that directly meshes with the developing drive gear 100G. In this configuration, the first control gear system 100C is equivalent to a "fifth gear system," and the idle gear 130A is equivalent to a "fifth gear."

[0164] Based on this structure, it is possible to suppress the influence of torque variation during the driving of YMC moving mechanism 5A and K moving mechanism 5K from spreading to the developing gear system 100A and 100B.

[0165] In addition, Figure 13In the illustrated configuration, the first control gear system 100C for color and the second control gear system 100D for monochrome share the idle gear 132A as a gear that directly meshes with the developing drive gear 100G. The first control gear system 100C, the second control gear system 100D, and the idle gear 132A constitute the control gear system 100E. That is, the drive force transmission mechanism 100 includes the developing drive gear 100G, the first developing gear system 100A, the second developing gear system 100B, and the control gear system 100E. The control gear system 100E is a gear system capable of transmitting the driving force from the developing motor 3D to both the YMC moving mechanism 5A and the K moving mechanism 5K. In this configuration, the control gear system 100E is equivalent to a "third gear system," and the idle gear 132A is equivalent to a "third gear."

[0166] With this structure, it is possible to suppress the influence of torque variation during the driving of moving mechanisms 5A and 5K from spreading to the developing gear system 100A and 100B.

[0167] Furthermore, in the above embodiments, such as Figure 2 As shown, the first developing gear system 100A can transmit the driving force from the developing motor 3D to the two developing rollers 61Y and 61M, and the second developing gear system 100B can transmit the driving force from the developing motor 3D to the two developing rollers 61C and 61K, but is not limited thereto. For example, as Figure 14 As shown, alternatively, the first developing gear system 100A can transmit the driving force from the developing motor 3D to the three developing rollers 61 (61Y, 61M, 61C), while the second developing gear system 100B can transmit the driving force from the developing motor 3D to only one developing roller 61 (61K). With such a structure, for example, the freedom of arrangement of the developing drive gear 100G and the developing motor 3D can be increased, thereby increasing the freedom of design for the image forming apparatus 1.

[0168] Furthermore, in the above embodiment, the K developing roller 61K (first developing roller) is disposed downstream of the C developing roller 61C (fourth developing roller) in the sheet material transport direction S, but this is not a limitation. For example, it is also possible to have the second developing roller, the third developing roller, and the fourth developing roller arranged in such an order from upstream to downstream in the sheet material transport direction, with the first developing roller disposed upstream of the second developing roller in the sheet material transport direction S. That is, the first developing roller, the second developing roller, the third developing roller, and the fourth developing roller can also be arranged in such an order from upstream to downstream in the sheet material transport direction.

[0169] Furthermore, in the above embodiment, the developing drive gear 100G, which serves as the drive gear, is a gear provided on the output shaft 3A of the developing motor 3D, but it is not limited to this. For example, the drive gear may be a gear that directly meshes with a gear provided on the output shaft of the motor, or it may be a gear that meshes with a gear provided on the output shaft of the motor via one or more idle gears.

[0170] Furthermore, in the above embodiment, the idle gear 131A, which serves as the fourth gear, directly meshes with the idle gear 110A in the gears constituting the first developing gear system 100A (the second gear system). This idle gear 110A also directly meshes with the developing drive gear 100G, but it is not limited to this. That is, the gear that directly meshes with the fourth gear can be any gear that constitutes the second gear system.

[0171] Furthermore, the structure of the moving mechanisms 5A and 5K described in the above embodiments is one example. For example, the moving mechanism may also have a structure with a linearly moving cam instead of a rotating cam 150. In addition, although the developing roller 61 moves back and forth between the contact position and the separation position in the above embodiments, it is not limited to this, for example, it may also move up and down.

[0172] Furthermore, in the above embodiment, the image forming apparatus 1 includes four photosensitive drums 50 and a developing roller 61, but it is not limited to this; there may be two, three, or more photosensitive drums and developing rollers. Additionally, the image forming apparatus is not limited to a printer; it may also be a copier, a multifunction printer, or the like.

[0173] Furthermore, the elements described in the above-described embodiments and variations can be appropriately combined and implemented.

Claims

1. An image forming apparatus, characterized in that, have: First photosensitive drum; Second photosensitive drum; A first developing roller is movable between a contact position that is in contact with the first photosensitive drum and a separation position that is away from the first photosensitive drum. The second developing roller is movable between a contact position that is in contact with the second photosensitive drum and a separation position that is away from the second photosensitive drum; A first moving mechanism moves the first developing roller between a contact position in contact with the first photosensitive drum and a separation position away from the first photosensitive drum. A second moving mechanism that moves the second developing roller between a contact position in contact with the second photosensitive drum and a separation position away from the second photosensitive drum; Drive gears; An electric motor that drives the drive gear; A first gear train having a first gear that meshes directly with the drive gear and capable of transmitting driving force from the motor to the first developing roller; The second gear train, which is independently configured from the first gear train, has a second gear that directly meshes with the drive gear and is capable of transmitting the driving force from the motor to the second developing roller; as well as A third gear train, independently configured from the first and second gear trains, has a third gear that directly meshes with the drive gear and is capable of transmitting driving force from the motor to at least one of the first and second moving mechanisms. The drive gear is a gear located on the output shaft of the motor and rotates integrally with the output shaft through the drive of the motor.

2. The image forming apparatus as claimed in claim 1, characterized in that, The third gear train can transmit the driving force from the motor to the first moving mechanism. The image forming apparatus also includes a fourth gear train, which is independently configured from the third gear train, has a fourth gear that directly meshes with the gears constituting the second gear train, and is capable of transmitting driving force from the motor to the second moving mechanism.

3. The image forming apparatus as claimed in claim 1, characterized in that, The third gear system is capable of transmitting the driving force from the motor to both the first moving mechanism and the second moving mechanism.

4. The image forming apparatus as claimed in claim 1, characterized in that, The third gear train can transmit the driving force from the motor to the first moving mechanism. The image forming apparatus also includes a fifth gear train, which is independently configured from the third gear train, has a fifth gear that directly meshes with the drive gear, and is capable of transmitting driving force from the motor to the second moving mechanism.

5. The image forming apparatus according to any one of claims 1 to 4, characterized in that, have: Third photosensitive drum; Fourth photosensitive drum; The third developing roller is movable between a contact position that is in contact with the third photosensitive drum and a separation position that is away from the third photosensitive drum; as well as The fourth developing roller is movable between a contact position with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum. The first gear train is capable of transmitting driving force from the motor to the first developing roller and the fourth developing roller. The second gear train is capable of transmitting driving force from the motor to the second developing roller and the third developing roller.

6. The image forming apparatus according to any one of claims 1 to 4, characterized in that, have: Third photosensitive drum; Fourth photosensitive drum; The third developing roller is movable between a contact position that is in contact with the third photosensitive drum and a separation position that is away from the third photosensitive drum; as well as The fourth developing roller is movable between a contact position with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum. The second gear train is capable of transmitting driving force from the motor to the second developing roller, the third developing roller, and the fourth developing roller.

7. The image forming apparatus according to any one of claims 1 to 4, characterized in that, have: Third photosensitive drum; Fourth photosensitive drum; The third developing roller is movable between a contact position that is in contact with the third photosensitive drum and a separation position that is away from the third photosensitive drum; as well as The fourth developing roller is movable between a contact position with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum. The second moving mechanism is configured to move the third developing roller between a contact position in contact with the third photosensitive drum and a separation position away from the third photosensitive drum, and to move the fourth developing roller between a contact position in contact with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum.

8. The image forming apparatus as claimed in claim 5, characterized in that, The second moving mechanism is configured to move the third developing roller between a contact position in contact with the third photosensitive drum and a separation position away from the third photosensitive drum, and to move the fourth developing roller between a contact position in contact with the fourth photosensitive drum and a separation position away from the fourth photosensitive drum.

9. The image forming apparatus as claimed in claim 7, characterized in that, The second developing roller, the third developing roller, and the fourth developing roller are arranged in the order of the second developing roller, the third developing roller, and the fourth developing roller, from upstream to downstream in the sheet conveying direction. The first developing roller is positioned upstream of the second developing roller or downstream of the fourth developing roller in the conveying direction.

Images