Image forming apparatus

Abstract

The present disclosure provides an image forming apparatus including: a driving source; a first driven member; a second driven member; a first driving force transmission unit configured to transmit the driving force output from the driving source to a first driven member, the first driving force transmission unit including a clutch mechanism; and a second driving force transmission unit configured to transmit the driving force to a second driven member, the second driving force transmission unit including a braking portion. The second driving force transmission unit is connected to the first driving force transmission unit between the clutch mechanism and the first driven member. When the clutch mechanism is in a transmission state, the first driven member is driven by both a first torque transmitted via the first driving force transmission unit and a second torque transmitted via a braking portion of the second driving force transmission unit.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an image forming apparatus that forms an image on a recording material. BACKGROUND

[0002] Japanese Patent Application Publication No. 2018-112661 proposes an image forming apparatus that includes a photosensitive drum and a developing roller that can be driven by a single motor. In a drive force transmission path between the motor and the developing roller, a clutch device is provided. The state of the clutch device can be switched between a transmission state in which the clutch device transmits rotational drive from the motor and a non-transmission state in which the clutch device does not transmit rotational drive from the motor.

[0003] However, in the image forming apparatus described in Japanese Patent Application Publication No. 2018-112661, when the state of the clutch device is switched from the transmission state to the non-transmission state, the torque applied to the developing roller instantaneously becomes zero, resulting in a large change in torque. Therefore, when the state of the clutch device is switched from the transmission state to the non-transmission state, a large impact is caused. SUMMARY

[0004] According to an aspect of the present disclosure, an image forming apparatus configured to form an image on a recording material includes a drive source; a first driven member; a second driven member different from the first driven member; a first drive force transmission unit configured to transmit a drive force output from the drive source to the first driven member, the first drive force transmission unit including a clutch mechanism configured to switch between a transmission state in which the drive force output from the drive source is transmitted to the first driven member and a non-transmission state in which the drive force output from the drive source is not transmitted to the first driven member; and a second drive force transmission unit configured to transmit the drive force output from the drive source to the second driven member and connected to the first drive force transmission unit, the second drive force transmission unit including a braking portion configured to generate a braking force to apply a load to rotation of the second driven member. The second drive force transmission unit is connected to the first drive force transmission unit between the clutch mechanism and the first driven member. In a case where the clutch mechanism is in the transmission state, the first driven member is driven by both a first torque transmitted via the first drive force transmission unit and a second torque transmitted via the braking portion of the second drive force transmission unit.

[0005] Features of the present disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is given by way of example only. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is a general schematic view showing a printer of the present embodiment.

[0007] Figure 2 is a schematic view showing the printer in a state where a door is open.

[0008] Figure 3 is a perspective view showing a cartridge.

[0009] Figure 4 is an enlarged perspective view showing a drum coupling member.

[0010] Figure 5 is a perspective view showing a driving force transmission mechanism.

[0011] Figure 6A is an exploded perspective view showing a clutch unit.

[0012] Figure 6B is another exploded perspective view showing the clutch unit.

[0013] Figure 7A is a sectional view showing the clutch unit in a transmission state.

[0014] Figure 7B is a sectional view showing the clutch unit in a non-transmission state.

[0015] Figure 8A is an exploded perspective view showing a second driving force transmission unit.

[0016] Figure 8B is an exploded perspective view showing a first brake engagement member, a second brake engagement member, and a brake transmission member.

[0017] Figure 9 is a sectional view showing the second driving force transmission unit.

[0018] Figure 10A is a perspective view showing a drum drive coupling member.

[0019] Figure 10B is a perspective view showing the drum drive coupling member and a coupling member engagement portion.

[0020] Figure 10C is a perspective view showing a state where the coupling member engagement portion is rotated in a through-hole.

[0021] Figure 11 is a sectional view showing a state where the drum drive coupling member and the drum coupling member engage with each other.

[0022] Figure 12 is an enlarged sectional view showing a vicinity of a protruding portion of the drum coupling member.

[0023] Figure 13A is a schematic diagram showing a drive force transmission path followed when drive force is transmitted from the motor to the developing coupling in a case where the clutch unit is in a transmission state.

[0024] Figure 13B is a schematic diagram showing a drive force transmission path followed when drive force is transmitted from the motor to the developing coupling in a case where the clutch unit is in a non-transmission state.

[0025] Figure 14A is a graph showing torque applied to the developing coupling in the comparative example.

[0026] Figure 14B is a graph showing torque applied to the developing coupling in the present embodiment. DETAILED DESCRIPTION

[0027] OVERALL CONFIGURATION

[0028] First, the overall configuration of a printer 1 serving as an image forming apparatus of the present embodiment will be described with reference to Figure 1 and Figure 2 Figure 1 is a schematic diagram showing the overall configuration of the printer 1 of the present embodiment. Figure 2 is a schematic diagram showing the printer 1 in a state where a door 20 is open. The printer 1 is an electrophotographic color laser beam printer that forms an image on a sheet S serving as a recording material.

[0029] In the following description and drawings, a vertical direction in a case where the printer 1 is placed on a horizontal plane is defined as a Z-axis direction. A direction of an axis of rotation of a photosensitive drum 61 included in the printer 1 is defined as a Y-axis direction. In addition, a direction intersecting both the Z-axis direction and the Y-axis direction is defined as an X-axis direction. Preferably, the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. In addition, there are cases where one side of the X-axis direction (i.e., a side indicated by an X arrow) is referred to as a +X side or a +X direction and the other side of the X-axis direction is referred to as a -X side or a -X direction. Similarly, there are cases where one side of the Y-axis direction (i.e., a side indicated by a Y arrow) is referred to as a +Y side or a +Y direction and the other side of the Y-axis direction is referred to as a -Y side or a -Y direction. Furthermore, there are cases where one side of the Z-axis direction (i.e., a side indicated by a Z arrow) is referred to as a +Z side or a +Z direction and the other side of the Z-axis direction is referred to as a -Z side or a -Z direction.

[0030] The +X direction can be referred to as a front surface side (front side) of the printer 1. In addition, the +Y side as viewed from the front surface side of the printer 1 can be referred to as a right side, and the -Y side as viewed from the front surface side of the printer 1 can be referred to as a left side.

[0031] As​Figure 1 As shown, the printer 1 includes a device body (housing) 1A, a scanner 2, a control portion 3, and a door 20. In addition, the printer 1 includes a sheet feeding portion 30, a transfer unit 40, a tray unit (removable unit) 50, and a fixing device 80. The portion including the device body 1A and the door 20 can be referred to as a main frame 100 of the printer 1. The main frame 100 includes an external portion of the printer 1. The device body 1A accommodates the scanner 2, the control portion 3, the sheet feeding portion 30, the transfer unit 40, the secondary transfer roller 45, the tray unit 50, and the fixing device 80.

[0032] The sheet feeding portion 30 includes a stack tray 31 that stacks the sheets S and a feeding roller 32 that feeds the sheets S. The stack tray 31 can be pulled out toward the door 20, and the sheets S can be supplied to the stack tray 31. In the present embodiment, the opening direction of the door 20 and the pulling-out direction of the stack tray 31 are the same as each other and are the +X side.

[0033] The tray unit 50 includes a tray (support member, drawer) 51 and cartridges PY, PM, PC, and PK. The tray 51 includes a tray handle (gripping portion) 52. The cartridges PY, PM, PC, and PK are removably (removably) attached to the tray 51.

[0034] The cartridges PY, PM, PC, and PK are capable of being removably attached to the tray 51 independently of each other. The cartridges PY, PM, PC, and PK respectively accommodate toners (developers) of yellow (Y), magenta (M), cyan (C), and black (K). The cartridges PY, PM, PC, and PK have the same configuration as each other except that the colors of the toners accommodated in the cartridges are different from each other. Therefore, the configuration and operation of any one of the cartridges PY, PM, PC, and PK will be described, and the description of the other cartridges can be omitted. In addition, each of the cartridges PY, PM, PC, and PK can be simply referred to as a cartridge P in a case where the cartridges PY, PM, PC, and PK do not need to be distinguished from each other. Therefore, in other words, the tray unit 50 includes a plurality of cartridges P and the tray 51, the plurality of cartridges P being removably attached to the tray 51.

[0035] In the present embodiment, the tray unit 50 includes a plurality of photosensitive drums (image bearing members) 61, a plurality of charging rollers (charging members) 62, and a plurality of developing rollers (developing members, developer bearing members) 71. Specifically, the tray unit 50 includes four photosensitive drums 61, four charging rollers 62, and four developing rollers 71. The rotation axis direction of each photosensitive drum 61, the rotation axis direction of each developing roller 71, and the rotation axis direction of each charging roller 62 are substantially parallel to each other.

[0036] The portion of the tray unit 50 that forms a black image can be referred to as a black station (first station); and the photosensitive drum 61, the developing roller 71, and the charging roller 62 of the first station can be referred to as a first photosensitive drum, a first developing roller, and a first charging roller, respectively. The portion of the tray unit 50 that forms a cyan image can be referred to as a cyan station (second station); and the photosensitive drum 61, the developing roller 71, and the charging roller 62 of the second station can be referred to as a second photosensitive drum, a second developing roller, and a second charging roller, respectively. The portion of the tray unit 50 that forms a magenta image can be referred to as a magenta station (third station); and the photosensitive drum 61, the developing roller 71, and the charging roller 62 of the third station can be referred to as a third photosensitive drum, a third developing roller, and a third charging roller, respectively. The portion of the tray unit 50 that forms a yellow image can be referred to as a yellow station (fourth station); and the photosensitive drum 61, the developing roller 71, and the charging roller 62 of the fourth station can be referred to as a fourth photosensitive drum, a fourth developing roller, and a fourth charging roller, respectively.

[0037] The cartridge PK attached to the tray 51 constitutes at least a portion of the black station. The cartridge PC attached to the tray 51 constitutes at least a portion of the cyan station. The cartridge PM attached to the tray 51 constitutes at least a portion of the magenta station. The cartridge PY attached to the tray 51 constitutes at least a portion of the yellow station. The cartridges PK, PC, PM, and PY can be referred to as a first cartridge, a second cartridge, a third cartridge, and a fourth cartridge, respectively. Note that ordinal numbers such as first, second, third, and fourth are used for convenience of description.

[0038] The photosensitive drum 61, the charging roller 62, and the developing roller 71 need only be included in either the cartridge P or the tray 51. In the present embodiment, the cartridge P includes the photosensitive drum 61, the charging roller 62, and the developing roller 71.

[0039] The transfer unit 40 includes a belt 41, a primary transfer roller 42, a cleaning portion 43, a drive roller 46 that drives the belt 41, and a tension roller 47. In addition, an optical sensor 44 that detects a toner image transferred to the belt 41 is provided in the printer 1. In the present embodiment, the belt 41 is disposed below the photosensitive drum 61 and in contact with the photosensitive drum 61 so that a primary transfer portion is formed between the belt 41 and the photosensitive drum 61.

[0040] In addition, the printer 1 includes a secondary transfer roller 45 that is in contact with the belt 41 so as to form a secondary transfer portion. The secondary transfer portion is formed between the belt 41 and the secondary transfer roller 45. The rotation axis direction of the primary transfer roller 42, the rotation axis direction of the drive roller 46, the rotation axis direction of the tension roller 47, and the rotation axis direction of the secondary transfer roller 45 are substantially parallel to each other. In addition, the registration roller pair 4 is disposed upstream of the secondary transfer portion in the conveyance direction of the sheet S.

[0041] The fixing device 80 includes a fixing portion 81 and a switching guide 5. The fixing device 80 of the present embodiment is movable with respect to the device body 1A between a use position and a retracted position. The fixing device 80 is in the use position in a case where an image forming operation is performed. In a state where the fixing device 80 is in the use position, the fixing device 80 is accommodated inside (inward) the device body 1A. In addition, in a state where the fixing device 80 is in the use position, the fixing device 80 heats the sheet S. The fixing portion 81 includes a heating portion (heating roller) having a heater (heat source) and a pressurizing portion (pressurizing roller) that forms a fixing nip together with the heating portion.

[0042] As shown in Figure 2 , the device body 1A includes an opening 1A1 in an end portion on the +X side. The door 20 is an opening and closing member (cover member, front cover) that is movable with respect to the device body 1A between a closed position and an open position. As shown in Figure 1 , in a state where the door 20 is in the closed position, the door 20 covers the opening 1A1. As shown in Figure 2 , in a state where the door 20 is in the open position, the opening 1A1 is exposed to the outside. In a state where the door 20 is in the closed position, the printer 1 performs an image forming operation described below. In a state where the door 20 is in the open position, the tray unit 50 and the transfer unit 40 are allowed to be pulled out from the device body 1A through the opening 1A1. Note that the tray unit 50 can be pulled out from the device body 1A by a user pulling a tray handle 52 of the tray 51. In a state where the tray 51 has been pulled out from the device body 1A, the cartridge P can be separated from the tray 51.

[0043] That is, the cartridge P can be considered as a detachable unit that is detachable from the device body 1A. In addition, the tray unit 50 can also be considered as a detachable unit that is detachable from the device body 1A. A drum unit 68 provided in the cartridge P described below is an example of a rotatably provided driven member.

[0044] In order to allow the opening 1A1 to be widely exposed, the fixing device 80 can be moved (retracted) from the use position shown in Figure 1 to a retracted position that is retracted upward from the use position. In a state where the door 20 is moved to the open position and the fixing device 80 is moved to the retracted position, the transfer unit 40 and the tray unit 50 can be moved from the inside of the device body 1A to the outside through the opening 1A1.

[0045] Image forming operation

[0046] Next, a description will be given with reference to Figure 1An image forming operation is described. The image forming operation is a series of operations in which the printer 1 forms an image on the sheet S while conveying the sheet S. The control portion 3 of the printer 1 starts the image forming operation based on image information transmitted from the external host device 90. The external host device 90 is, for example, a personal computer, an image reader, a facsimile machine, or the like.

[0047] If the image forming operation is started, in each station of the tray unit 50, the photosensitive drum 61 is driven and rotated, and the charging roller 21 to which a charging voltage is applied uniformly charges the surface of the photosensitive drum 61. In addition, a laser beam corresponding to the image information is emitted from the scanner 2 to each photosensitive drum 61, so that the surface of the photosensitive drum 61 is exposed. By the exposure, an electrostatic latent image is formed on the surface of the photosensitive drum 61. The electrostatic latent image corresponds to an image obtained by decomposing the image information into respective ones of CMYK components.

[0048] The developing roller 71 rotates while carrying toner. The developing roller 71 is applied with a developing voltage, and develops the electrostatic latent image formed on the photosensitive drum 61 by toner supplied from the developing roller 71. Thereby, a toner image is formed on the surface of the photosensitive drum 61. In the present embodiment, the developing roller 71 develops the electrostatic latent image in a state in which the developing roller 71 is in contact with the photosensitive drum 61 (contact developing system). However, another system can be used. For example, the developing roller 71 can develop the electrostatic latent image in a state in which a gap is formed between the developing roller 71 and the photosensitive drum 61. In a case in which a full-color image is formed, toner images of various colors are formed on the corresponding photosensitive drums 61.

[0049] In the present embodiment, the developing roller 71 can move between an abutting position at which the developing roller 71 is in contact with the photosensitive drum 61 and a separation position at which the developing roller 71 is separated from the photosensitive drum 61. Specifically, the state in which the developing roller 71 is located at the abutting position and the state in which the developing roller 71 is located at the separation position are switched by a switching device included in the device body 1A. Thus, in a state in which the image forming operation is not performed, the developing roller 71 can be separated from the photosensitive drum 61.

[0050] In addition, the printer 1 can perform monochrome printing in a state in which the developing roller 71 and the photosensitive drum 61 of the cartridge PK are in contact with each other and the developing roller 71 and the photosensitive drum 61 of each of the cartridges PY, PM, and PC are not in contact with each other. In addition, the printer 1 can perform full-color printing in a state in which the photosensitive drums 61 of each of the cartridges PY, PM, PC, and PK are in contact with the belt 41.

[0051] In the primary transfer portion, the toner image formed on each photosensitive drum 61 is transferred onto the belt 41 by the corresponding primary transfer roller 42. The toner image is carried by the belt 41 and conveyed toward the secondary transfer portion formed by the belt 41 and the secondary transfer roller 45.

[0052] A conveyance path 1c (first conveyance path) is formed in the device main body 1A, and extends from the feed roller 32 toward the fixing device 80 through the secondary transfer portion. A double-sided conveyance path (second conveyance path) 20a is formed in the door 20. The double-sided conveyance path 20a is a path through which the sheet S that has passed through the fixing device 80 has passed. In a state in which the door 20 is closed, the door 20 covers the conveyance path 1c. As shown in FIG. 1, if the door 20 is opened, at least a part of the conveyance path 1c and at least a part of the double-sided conveyance path 20a are exposed to the outside. Figure 2

[0053] In the image forming operation, in parallel with the formation of the toner image described above, the sheets S are fed one by one from the sheet feed portion 30 toward the secondary transfer portion through the conveyance path 1c. Specifically, the uppermost sheet among the sheets S stacked on the stack tray 31 is fed by the feed roller 32 at a predetermined timing. The fed sheet S is separated from the other sheets by a separation member (for example, a friction roller); and skew correction and timing adjustment are performed on the sheet S by the pair of registration rollers 4. Thereafter, the sheet S is fed into the secondary transfer portion. In the secondary transfer portion, the toner image is transferred from the belt 41 to the sheet S by the secondary transfer roller 45 to which a voltage is applied. The toner that has not been transferred to the sheet S is removed from the belt 41 by a cleaning blade (cleaning member) 43A provided in the cleaning portion 43.

[0054] The sheet S on which the toner image has been transferred in the secondary transfer portion is conveyed to the fixing device 80. In the fixing portion 81, the sheet S is heated and pressed, so that the toner image is fixed to the sheet S. The sheet S that has passed through the fixing portion 81 reaches the switching guide 5 that serves as a path switching portion.

[0055] The switching guide 5 is movable between a sheet discharge position and a reverse position. The sheet discharge position is a position at which the switching guide 5 guides the sheet S that has passed through the fixing device 80 toward the discharge path 1d. The reverse position is a position at which the switching guide 5 guides the sheet S that has passed through the fixing device 80 toward the reverse path 1e. In a case in which single-sided printing is performed to form an image on one side of the sheet S, the sheet S is guided to the discharge path 1d by the switching guide 5, and is discharged to the discharge tray 1f formed in the upper portion of the device main body 1A.

[0056] ​On the other hand, in a case where double-sided printing is performed for forming images on one face and the back face of the sheet S, the sheet S is guided to the reversal path le by the switching guide 5. After the sheet S is guided to the reversal path le, the conveyance direction of the sheet S is reversed, and the sheet S is conveyed toward the secondary transfer portion through the double-sided conveyance path 20a formed in the door 20. Thereafter, a toner image is transferred to the back face of the sheet S in the secondary transfer portion. Then, the sheet S is guided to the discharge path Id by the switching guide 5, and discharged to the discharge tray If of the device body 1A through the fixing device 80.

[0057] As described above, in the closed position, the door 20 covers the opening 1A1 and covers at least a part of the conveyance path 1c of the sheet S. The door 20 includes the double-sided conveyance path 20a. If the sheet S is jammed (hereinafter referred to as paper jam), the user of the printer 1 can clear the paper jam by removing the sheet S from the one end side (i.e., the +X side) of the device body 1A. Specifically, by moving the door 20 to the open position, the user can remove the sheet S by reaching the inside of the device body 1A. If a part of the sheet S that has passed through the fixing device 80 is exposed to the outside of the device body 1A, the user can remove the sheet S by pulling out the sheet S from the outside of the device body 1A without opening the door 20.

[0058] Further, the user of the printer 1 can move the transfer unit 40 and the tray unit 50 from the one end side of the device body 1A to the outside of the device body 1A; and thereby can perform various types of jobs (e.g., status check, maintenance, and replacement) on the transfer unit 40 and the cartridge P.

[0059] That is, in the printer 1, the fixing device 80 is provided at the one end side of the device body 1A, and the transfer unit 40 and the tray unit 50 can be moved to the outside and the inside of the device body 1A through the one end side of the device body 1A. Therefore, the user can clear the paper jam, reach the fixing device 80, and operate the transfer unit 40 and the tray unit 50 from one direction.

[0060] In the printer 1 of the present embodiment, the front surface is at the door 20 side (i.e., the +X side). Therefore, only a space for performing various types of jobs (e.g., clearing the paper jam and operating the transfer unit 40 and the tray unit 50) from the front surface side of the printer 1 needs to be secured. Therefore, it is not necessary to secure any space for performing the jobs from the left surface side, the right surface side, the rear surface side, or the top surface side. Thereby, it is possible to install the printer 1 in a space-saving manner.

[0061] If the transfer unit 40 or the tray unit 50 is pulled out from the other end side of the device body 1A, the user has to touch both end sides of the device body 1A in order to clear the jam and pull out the transfer unit 40 or the tray unit 50. In addition, if one of the transfer unit 40 and the tray unit 50 is pulled out from one end side of the device body 1A, and the other of the transfer unit 40 and the tray unit 50 is pulled out from the other end side, the user also has to touch both end sides of the device body 1A. Therefore, not only a space for performing a job from the front surface side of the device body 1A is required, but also a space for performing a job from the rear surface side of the device body 1A is required, thereby increasing an area for installing the printer 1.

[0062] In addition, in the present embodiment, the sheet S can be supplied from one end side of the device body 1A. Therefore, only a space for supplying the sheet S from the front surface side has to be ensured. Thereby, the printer 1 can be installed in a space-saving manner.

[0063] Cartridge

[0064] Next, the configuration of the cartridge P will be described with reference to Figure 3 and Figure 4 Figure 3 is a perspective view showing the cartridge P as a process cartridge. Figure 4 is an enlarged perspective view showing the drum coupling 63.

[0065] As shown in Figure 3 , the cartridge P includes a drum unit 68 and a developing unit 70. In addition, the cartridge P includes a first side cover 66 and a second side cover 67 fixed to both ends of the drum unit 68 and the developing unit 70 in the longitudinal direction LD of the cartridge P. The developing unit 70 is rotatably supported by the first side cover 66 and the second side cover 67.

[0066] The drum unit 68 is constituted by the photosensitive drum 61, the charge roller 62, a drum frame 65, and the like. In addition, the drum coupling 63 (which functions as a second driven member) and a drum flange 64 are fixed to the photosensitive drum 61. The photosensitive drum 61, the drum coupling 63, and the drum flange 64 constitute the drum unit 68. The drum coupling 63 is rotatably supported by the first side cover 66, and the drum flange 64 is rotatably supported by the second side cover 67. That is, the photosensitive drum 61 is rotatably supported by the first side cover 66 and the second side cover 67 via the drum coupling 63 and the drum flange 64.

[0067] Note that, in the present embodiment, a cleaning unit (for example, a cleaning blade) for removing residual toner remaining on the surface of the photosensitive drum 61 is not provided in the drum unit 68. However, the present disclosure is not limited thereto. For example, the above-described cleaning unit can be provided in the drum unit 68.

[0068] ​The developing unit 70 includes a developing roller 71 carrying toner, a toner transfer roller (toner supply roller) (not shown), a developing blade (not shown), a developing connector 72, and a developing frame 73. The developing roller 71 supplies toner stored in a toner storage chamber disposed within the developing frame 73 to a photosensitive drum 61, thereby developing the electrostatic latent image formed on the photosensitive drum 61 into a toner image. The toner transfer roller supplies toner stored in the toner storage chamber to the developing roller 71. The developing blade controls the layer thickness of the toner carried by the developing roller 71. The developing roller 71 and the toner transfer roller are driven by a rotational drive (driving force) applied from the device body 1A to the developing connector 72, which serves as a first driven component. The developing connector 72 is a component distinct from the drum connector 63.

[0069] like Figure 4 As shown, the drum connector 63 includes a circular hole portion 63a and a protrusion portion 63e, which will be described in detail below. Specifically, the two protrusion portions 63e are positioned 180 degrees apart from each other in the circumferential direction around the rotation axis M1. A driving force receiving portion 63b and a braking force receiving portion 63c are formed in each protrusion portion 63e. The circular hole portion 63a can engage with a positioning boss 180i formed in the drum drive connector 180 of the drum drive force transmission unit 203 described below. The circular hole portion 63a and the positioning boss 180i engage with each other such that the axis of the drum drive force transmission unit 203 and the axis of the drum connector 63 are aligned with each other. The driving force receiving portion 63b receives rotational drive from the drum drive force transmission unit 203, and the braking force receiving portion 63c receives braking force from the braking force application unit 260 described below (see Figure 5 The driving force receiving portion 63b is located upstream of the braking force receiving portion 63c in the direction indicated by arrow A, which is the rotation direction of the drum unit 68. In this embodiment, two driving force receiving portions 63b and two braking force receiving portions 63c are formed.

[0070] Next, refer to Figure 5 The configuration of the drive force transmission mechanism 200 provided in the device body 1A will be described. Figure 5 This is a perspective view showing the driving force transmission mechanism 200. (See image.) Figure 5As shown, the drive force transmission mechanism 200 includes a motor M serving as a drive source, an output portion MP for rotating the output motor M, a first drive force transmission unit 150 serving as a first drive force transmission portion, and a second drive force transmission unit 250 serving as a second drive force transmission portion. The output portion MP may be a gear formed on or attached to the shaft of the motor M, or it may be another gear meshing with the gear. The first drive force transmission unit 150 and the second drive force transmission unit 250 are connected to the output portion MP. In other words, the transmission path of rotating drive of the motor M branches from the output portion MP into the first drive force transmission unit 150 and the second drive force transmission unit 250. Note that additional drive force transmission components, such as gears, may be provided in the drive force transmission path between the output portion MP and the first drive force transmission unit 150, or in the drive force transmission path between the output portion MP and the second drive force transmission unit 250.

[0071] The first drive force transmission unit 150 includes a clutch unit 120 serving as a clutch mechanism, a gear 112, a developing drive gear 111 serving as a rotating body, and a developing drive coupling 72; and transmits the rotational drive output from the motor M to the developing coupling 72. The developing drive gear 111 and the developing drive coupling 72 are located between the clutch unit 120 and the developing coupling 72. Additionally, the developing drive gear 111 is located between the developing drive coupling 110 and the clutch unit 120.

[0072] The second drive force transmission unit 250 includes a drum drive force transmission unit 203, a braking force application unit 260, a braking portion 206, a rotating shaft 215, and a gear 220; and transmits the rotational drive output from the motor M to the drum coupling 63. The second drive force transmission unit 250 is connected to the first drive force transmission unit 150 at a position between the developing coupling 72 and the clutch unit 120. More specifically, the second drive force transmission unit 250 is connected to the first drive force transmission unit 150 at a position between the developing drive coupling 110 and the clutch unit 120. In this embodiment, the gear 220 of the second drive force transmission unit 250 meshes with the developing drive gear 111, such that the second drive force transmission unit 250 is connected to the first drive force transmission unit 150. The braking portion 206 is positioned between the output portion MP and the gear 220. The gear 220 may be referred to as the connection portion connected to the first drive force transmission unit 150.

[0073] The developing drive gear 111 of the first driving force transmission unit 150 is fixed to the drive frame 102 (see...). Figure 9The shaft (not shown) of the developing drive coupling 110 is rotatably supported and drivenly connected to the developing coupling 72. The rotational drive (driving force) output from the motor M is transmitted to the developing drive gear 111 via the output section MP, the clutch unit 120, and the gear 112. The developing drive coupling 110 is supported so as to be movable relative to the developing drive gear 111 in the thrust direction; and is pushed toward the developing coupling 72 by a pushing member (not shown).

[0074] Additionally, the rotational drive (driving force) output from the motor M is transmitted to the drum connector 63 via the drum drive force transmission unit 203, as described below. The drum connector 63, the drum drive force transmission unit 203, and the gear 216 rotate about the rotation axis M1. Note that in Figure 5 For ease of description, the developing connector 72 and developing drive connector 110, which are separate from each other, are shown, as are the drum connector 63 and drum drive connector 180, which are separate from each other. However, in actual use, the developing connector 72 and developing drive connector 110 are engaged with each other, and the drum connector 63 and drum drive connector 180 are engaged with each other to transmit driving force.

[0075] Furthermore, the rotational drive (driving force) output from the motor M is transmitted to the developing drive gear 111 via the output section MP, the drum drive force transmission unit 203, the drum connector 63, the braking force application unit 260, the braking section 206, the rotating shaft 215, and the gear 220. That is, the rotational drive of the motor M is transmitted to the developing drive gear 111 via two paths: a first driving force transmission path via the first driving force transmission unit 150 and a second driving force transmission path via the second driving force transmission unit 250.

[0076] Clutch unit

[0077] Next, we will refer to Figure 6A to Figure 7B The clutch unit 120 of the first driving force transmission unit 150 is described. Figure 6A This is an exploded perspective view showing the clutch unit 120. Figure 6B This is another exploded perspective view showing the clutch unit 120. Figure 7A This is a cross-sectional view showing the clutch unit 120 in the transmission state. Figure 7B This is a cross-sectional view showing the clutch unit 120 in a non-transmission state.

[0078] like Figure 6A and Figure 6BAs shown, the clutch unit 120 includes a clutch drive gear 122, a pushing member 124, a drive-side engagement member 123, a release member 127, a cam retaining member 128, a cam gear member 126, and a clutch driven gear 125. Additionally, a drive frame 101 is disposed within the device body 1A, and a shaft 121 is fixed to the drive frame 101.

[0079] The rotary drive output from the motor M is transmitted to the clutch drive gear 122. The clutch drive gear 122 is rotatably supported by the shaft 121. Additionally, the drive-side engagement member 123 and the clutch driven gear 125 are also rotatably supported by the shaft 121. In the clutch drive gear 122, an inner recess is formed in the gear portion on the outer peripheral surface. The inner peripheral surface of the clutch drive gear 122 serves as a positioning surface for locating the drive-side engagement member 123 and also as a sliding surface.

[0080] The drive-side engagement member 123 includes a ratchet portion 123a, a recessed portion 123b, and a pawl portion 123c. The recessed portion 123b engages with the anti-rotation portion 122a of the clutch drive gear 122. Therefore, the drive-side engagement member 123 and the clutch drive gear 122 rotate integrally about the shaft 121. In addition, the drive-side engagement member 123 is movable relative to the clutch drive gear 122 in the axial direction of the shaft 121.

[0081] A pushing member 124 is disposed between the clutch drive gear 122 and the drive-side engagement member 123. The pushing member 124 pushes the drive-side engagement member 123 in the direction that the drive-side engagement member 123 is disengaged from the clutch drive gear 122 and engaged with the clutch driven gear 125. In this embodiment, the pushing member 124 is composed of a compression spring. Because the drive-side engagement member 123 is pushed by the pushing member 124, the drive-side engagement member 123 is held in a state where it abuts against the abutment surface 127c of the release member 127. The drive-side engagement member 123 and the release member 127 move integrally in the axial direction of the shaft 121 (which is equivalent to the axial direction MD described below).

[0082] The claw portion 123c formed in the outer peripheral surface of the drive-side engagement member 123 is locked to the anti-separation portion 122b formed in the clutch drive gear 122. Therefore, the pushing force of the pushing member 124 prevents the drive-side engagement member 123 from disengaging from the clutch drive gear 122. In other words, the engagement of the claw portion 123c with the anti-separation portion 122b prevents the drive-side engagement member 123 from separating from the clutch drive gear 122.

[0083] The clutch driven gear 125 includes a ratchet portion 125a and a cylindrical portion 125b. The ratchet portion 125a faces the ratchet portion 123a of the drive-side engagement member 123. Additionally, the clutch driven gear 125 abuts against the drive frame 102 (see [link]). Figure 9 This prevents the clutch driven gear 125 from moving in the second direction M1B.

[0084] like Figure 7A As shown, if the ratchet portion 123a of the drive-side engagement member 123 engages with the ratchet portion 125a of the clutch driven gear 125, the clutch unit 120 changes to a transmission state. Additionally, as... Figure 7B As shown, if the ratchet portion 123a of the drive-side engagement member 123 disengages from the ratchet portion 125a of the clutch driven gear 125, the clutch unit 120 becomes a non-transmission state. When the clutch unit 120 is in the transmission state, the rotary drive output from the motor M is transmitted to the developing drive gear 111. On the other hand, when the clutch unit 120 is in the non-transmission state, the rotary drive output from the motor M is not transmitted to the developing drive gear 111. In other words, the state of the clutch unit 120 can switch between a transmission state where the rotary drive output from the motor M is transmitted to the developing coupling 72 and a non-transmission state where the rotary drive output from the motor M is not transmitted to the developing coupling 72.

[0085] The cam retaining member 128 includes an anti-rotation portion 128a and a protrusion 128b, and is supported by the inner peripheral portion 122c of the clutch drive gear 122, which serves as a shaft. Additionally, the anti-rotation portion 128a is connected to the drive frame 102 (see...). Figure 9 The anti-rotation hole (not shown) engages to prevent the cam retaining member 128 from rotating about the shaft 121. The cam gear member 126 includes a plurality of (three in this embodiment) cam portions 126a protruding toward the release member 127 and is rotatably supported by the cylindrical portion 125b of the clutch driven gear 125.

[0086] The release member 127 includes a recess 127b, a top surface portion 127a1 capable of engaging with the cam portion 126a, a bottom surface portion 127a2, and an inclined surface portion 127a3. Since the recess 127b engages with the protrusion 128b of the cam retainer 128, the release member 127 and the cam retainer 128 can rotate integrally about the axis 121. Note that the release member 127 can move relative to the cam retainer 128 in the axial direction of the axis 121.

[0087] The cam gear assembly 126 is driven and controlled by applying rotational drive from the motor M to the cam gear assembly 126 via a solenoid and gear train (not shown). Note that in this embodiment, the cam gear assembly 126 is controlled such that it rotates one-third of a turn or 120 degrees when the solenoid operates once. In another case, a different actuator can be used instead of the solenoid.

[0088] If the cam gear assembly 126 rotates, and the cam portion 126a of the cam gear assembly 126 and the top surface portion 127a1 of the release member 127 are in phase with each other, then the top surface portion 127a1 of the release member 127 moves from the cam portion 126a toward... Figure 6A and Figure 6B Pushing to the left in the middle. Through this operation, the release member 127 and the drive-side engagement member 123 move in the direction of disengagement from the clutch driven gear 125, so that the ratchet portion 123a of the drive-side engagement member 123 and the ratchet portion 125a of the clutch driven gear 125 disengage from each other. As a result, the state of the clutch unit 120 becomes Figure 7B The non-transitive state is shown.

[0089] In contrast, if the cam gear assembly 126 rotates, and the cam portion 126a of the cam gear assembly 126 and the top surface portion 127a1 of the release member 127 are out of phase, the drive-side engagement member 123 moves towards the clutch driven gear 125 by the pushing force of the pushing member 124. In this case, the cam portion 126a of the cam gear assembly 126 contacts the bottom surface portion 127a2 of the release member 127. As a result, the ratchet portion 123a of the drive-side engagement member 123 and the ratchet portion 125a of the clutch driven gear 125 engage with each other, causing the clutch unit 120 to change to the following state: Figure 7A The transmission status is shown.

[0090] Second driving force transmission unit

[0091] Next, refer to Figure 8A to Figure 10C The configuration of the second drive force transmission unit 250 provided in the device body 1A will be described. Figure 8A This is an exploded perspective view showing the second driving force transmission unit 250. Figure 8B This is an exploded perspective view showing the first brake engagement member 204, the second brake engagement member 208, and the brake transmission member 207. Figure 9 This is a cross-sectional view showing the second driving force transmission unit 250. Figure 10A This is a perspective view showing the drum drive coupling 180. Figure 10BThis is a perspective view showing the drum drive connector 180 and the connector engagement portions 204b and 208b. Figure 10C This is a perspective view showing the coupling portions 204b and 208b rotating in the through hole 180f.

[0092] like Figure 8A and Figure 9 As shown, the second drive force transmission unit 250 includes a drum drive force transmission unit 203 serving as the drive force transmission part, a brake force application unit 260 serving as the brake force application part, a braking part 206, a rotating shaft 215, and a gear 220. Figure 9 As shown, the device body 1A includes drive frames 101 and 102 as fixed components, and shaft receiving component 202 fixed to drive frame 101.

[0093] Each drive frame 101 and 102 is constructed of a metal plate and extends in a radial direction RD, which is used as an intersecting direction (at right angles) with the axial direction MD. Furthermore, drive frames 101 and 102 are spaced apart from each other in the axial direction MD. Note that the radial direction RD is the radial direction of an imaginary circle C about the rotation axis M1. In this embodiment, the radial direction RD is orthogonal to the axial direction MD. The shaft receiving member 202 is fixed to the drive frame 101 such that the shaft receiving member 202 cannot rotate relative to the drive frame 101 about the rotation axis M1.

[0094] The rotation axis M1 of the drum drive force transmission unit 203 extends in the axial direction MD and is equivalent to the rotation axis of the drum connector 63. Furthermore, the axial direction MD is... Figure 3 The longitudinal direction LD of the box P shown is parallel to the direction. In the following description, the direction extending from the drive frame 101 toward the drive gear 201 of the drum drive force transmission unit 203 in the axial direction MD is referred to as the second direction M1B, and the direction extending from the drive frame 101 toward the gear 216 in the axial direction MD is referred to as the first direction M1A. The first direction M1A and the second direction M1B are opposite to each other.

[0095] The shaft receiving member 202 includes a cylindrical portion 202a formed in a cylindrical shape and extending in the second direction M1B. The drum drive force transmission unit 203 includes a drive gear 201 and a drum drive coupling 180. The drive gear 201 includes a mating portion 201a and a plurality of (three in this embodiment) recesses 201b. The mating portion 201a is recessed in the first direction M1A. The recesses 201b are formed in the mating portion 201a and are recessed in the radial direction RD. The three recesses 201b are formed at equal intervals in the circumferential direction about the rotation axis M1. The drive gear 201 is rotatably supported by the cylindrical portion 202a of the shaft receiving member 202 and rotates by a rotational drive transmitted from the motor M.

[0096] The drum drive coupling 180 includes a cylindrical portion 180c, a flange portion 180a, and a positioning boss 180i. The cylindrical portion 180c is formed in a cylindrical shape and extends in the axial direction MD. The flange portion 180a is formed at an end portion in a first direction M1A of the cylindrical portion 180c, and the positioning boss 180i is formed at an end portion in a second direction M1B of the cylindrical portion 180c. In the flange portion 180a, a plurality of (three in this embodiment) protrusions 180b are formed to protrude in the radial direction RD. The flange portion 180a is fitted into a mating portion 201a of the drive gear 201 along the first direction M1A, and each protrusion 180b engages with a corresponding recess in the recess 201b of the drive gear 202. Therefore, the drum drive coupling 180 and the drive gear 201 rotate integrally about the rotation axis M1. With the box P attached to the device body 1A, the positioning boss 180i and the circular hole portion 63a of the drum connector 63 (see...) Figure 4 ) join.

[0097] like Figure 10A As shown, driving force transmission surfaces 180d and 180d, and through holes 180f and 180f are formed around the positioning boss 180i of the drum drive connector 180. Through holes 180f and 180f penetrate the drum drive connector 180 along the axial direction MD. Driving force transmission surfaces 180d and 180d are separated from each other by 180 degrees in the circumferential direction about the rotation axis M1. Through holes 180f and 180f are also separated from each other by 180 degrees in the circumferential direction about the rotation axis M1. Driving force transmission surfaces 180d and 180d can engage with the driving force receiving portion 63b of the drum connector 63.

[0098] like Figure 8AAs shown, the braking force application unit 260, which serves as the braking force application part, includes gears 216 and 217, a brake transmission shaft 209, a spring retaining member 214, a first brake engagement member 204, and a second brake engagement member 208. Additionally, the braking force application unit 260 also includes a brake transmission member 207, a brake engagement spring 211, and a drum drive coupling spring 210. The spring retaining member 214, the first brake engagement member 204, the second brake engagement member 208, the brake transmission member 207, the brake engagement spring 211, and the drum drive coupling spring 210 are disposed within the internal space of the cylindrical portion 180c of the drum drive coupling 180.

[0099] like Figure 8A and Figure 9 As shown, the brake transmission shaft 209 includes a shaft portion 209c extending in the axial direction MD, an engaging pin 209b fixed to the shaft portion 209c and extending in the radial direction RD, and a recessed portion 209a formed in the shaft portion 209c and extending in the axial direction MD. The shaft portion 209c passes through the cylindrical portion 202a of the shaft receiving member 202 and is rotatably supported by the spring retaining member 214 described below. The engaging pin 209b is provided in the downstream end portion of the brake transmission shaft 209 along the first direction M1A. The recessed portion 209a is formed in the upstream end portion of the brake transmission shaft 209 along the first direction M1A. Therefore, the engaging pin 209b and the recessed portion 209a are disposed opposite each other in the axial direction MD relative to the drive frame 101.

[0100] Engaging pin 209b engages with engagement portion 216a of gear 216, which is supported by brake transmission shaft 209 serving as a shaft. Therefore, gear 216 and brake transmission shaft 209 rotate integrally with each other. Additionally, rotating shaft 215 is fixed to drive frames 101 and 102. Rotating shaft 215 extends along rotation axis M2, which extends parallel to rotation axis M1 and is located at a position different from that of rotation axis M1 in the radial direction RD. Furthermore, the inner ring 206b of brake portion 206 is fixed to rotating shaft 215.

[0101] The braking portion 206 includes an outer ring 206a serving as a first rotating member and an inner ring 206b housed within the outer ring 206a and serving as a second rotating member. That is, the braking portion 206 is positioned at a location displaced radially from the rotation axis M1 along the radial direction RD. The inner ring 206b includes a engagement hole 206c that engages with an engagement pin 215a fixed to the rotation shaft 215. Because the engagement pin 215a engages with the engagement hole 206c, the inner ring 206b is attached to the rotation shaft 215 in a manner that does not rotate relative to the rotation shaft 215. That is, the inner ring 206b and the rotation shaft 215 rotate integrally about the rotation axis M2. Furthermore, the inner ring 206b is drivably connected to the developing drive gear 111 via the rotation shaft 215 and the gear 220 (see [link to gear description]). Figure 5 If a torque equal to or greater than a predetermined value is applied to the outer ring 206a, the outer ring 206a rotates relative to the inner ring 206b.

[0102] When the outer ring 206a rotates relative to the inner ring 206b, the outer ring 206a rotates simultaneously while receiving a braking force (load) in the direction of rotation from the inner ring 206b. The method for generating the braking force can be suitably selected from methods utilizing friction, methods utilizing viscosity, etc. In this embodiment, a torque limiter is used in the braking section 206. For example, the torque limiter utilizes the frictional force between the built-in spring and the inner ring, thereby limiting the torque transmitted from the input side to the output side to a predetermined limit value. If the torque applied to the outer ring 206a has a value equal to or lower than the predetermined limit value, the outer ring 206a rotates integrally with the inner ring 206b. In another case, a rotational damper can be used in the braking section 206. The rotational damper utilizes the braking force generated by the viscous resistance of oil.

[0103] The outer ring 206a includes a protrusion 206d. The protrusion 206d engages with a mating portion 217a formed in the gear 217, causing the outer ring 206a to rotate integrally with the gear 217. That is, the outer ring 206a and the gear 217 rotate integrally about the axis of rotation M2. For example, the protrusion 206d and the mating portion 217a are splined together.

[0104] Gear 217 includes a gear portion 217c and a receiving portion 217d that accommodates the braking portion 206. Gear portion 217c meshes with gear portion 216c of gear 216. Receiving portion 217d is disposed inside gear portion 217c in the radial direction RD. That is, receiving portion 217d is disposed closer to the axis of rotation M2 than gear portion 217c.

[0105] The groove portion 209a formed in the brake transmission shaft 209 is formed by spline machining on the shaft portion 209c. The groove portion 209a can be a plurality of groove portions formed in the circumferential direction around the rotation axis M1. However, the groove portion 209a can be a single groove portion. Furthermore, the groove portion 209a and the protrusion 207c of the brake transmission member 207 are splined together. The protrusion 207c protrudes inward from the inner circumferential surface of the brake transmission member 207 in the radial direction RD. The protrusion 207c can be a plurality of protrusions, the same number as the groove portions 209a. Because the groove portion 209a and the protrusion 207c are splined together, the brake transmission member 207 and the brake transmission shaft 209 rotate integrally about the rotation axis M1. Additionally, the brake transmission member 207 can move relative to the brake transmission shaft 209 in the axial direction MD.

[0106] like Figure 8B As shown, the brake transmission component 207 includes a shaft portion 207b and a flange portion 207a. The shaft portion 207b extends in the axial direction MD. The flange portion 207a extends radially RD from the downstream end of the shaft portion 207b in the second direction M1B. The flange portion 207a includes a plurality of protrusions 207e projecting in the first direction M1A (four in this embodiment). The plurality of protrusions 207e are formed at equal intervals in the circumferential direction about the rotation axis M1.

[0107] like Figure 8A , Figure 8B and Figure 9 As shown, the drum drive coupling spring 210, which is a compression spring, is provided contractively between the end surface 207d of the brake transmission member 207 along the first direction M1A and the spring holding member 214. The drum drive coupling spring 210 applies a repulsive force (pushing force, elastic force) to the spring holding member 214 and the brake transmission member 207 in the direction in which the spring holding member 214 and the brake transmission member 207 are separated from each other.

[0108] like Figure 8B As shown, the first brake engagement component 204 includes a flange portion 204a and a connecting member engagement portion 204b. The connecting member engagement portion 204b protrudes in a claw shape from the flange portion 204a along the second direction M1B.

[0109] The flange portion 204a includes a recess 204c and a protrusion 204e that engages with the protrusion 207e of the brake transmission member 207. In this embodiment, four protrusions 204e and two recesses 204c are formed. However, the number of protrusions 204e and the number of recesses 204c are not limited to a specific number. Since the protrusions 204e of the first brake engagement member 204 engage with the protrusions 207e of the brake transmission member 207, the first brake engagement member 204 and the brake transmission member 207 rotate integrally about the rotation axis M1.

[0110] The second brake engagement member 208 includes a flange portion 208a and a connecting member engagement portion 208b. The connecting member engagement portion 208b protrudes in a claw-like shape from the flange portion 208a along a second direction M1B. The connecting member engagement portion 208b is disposed inside the connecting member engagement portion 204b of the first brake engagement member 204 in the radial direction RD. In this embodiment, the second brake engagement member 208 includes two connecting member engagement portions 208b. However, the number of connecting member engagement portions 208b is not limited to a specific number. In the flange portion 208a, a protrusion 208c is formed to protrude in the first direction M1A. Since the protrusion 208c of the second brake engagement member 208 engages with the recess 204c of the first brake engagement member 204, the second brake engagement member 208 and the first brake engagement member 204 rotate integrally about the rotation axis M1. Furthermore, the first brake engagement component 204 and the second brake engagement component 208 are connected to each other, such that the first brake engagement component 204 and the second brake engagement component 208 also move integrally in the axial direction MD. Therefore, the first brake engagement component 204 and the second brake engagement component 208 can be collectively referred to as brake engagement components (204, 208).

[0111] like Figure 9 As shown, the flange portion 207a of the brake transmission component 207 is disposed between the flange portion 204a of the first brake engagement component 204 and the flange portion 208a of the second brake engagement component 208 in the axial direction MD. Furthermore, the flange portion 207a is located between the flange portion 204a and the flange portion 208a in the axial direction MD, wherein a gap G is formed between the flange portion 204a and the flange portion 208a.

[0112] like Figure 8A and Figure 9As shown, a brake engagement spring 211, acting as a compression spring, is constricted between the spring retaining member 214 and the flange portion 204a of the first brake engagement member 204. The brake engagement spring 211 applies a repulsive force (pushing force, elastic force) to the spring retaining member 214 and the first brake engagement member 204 in the direction separating them from each other. Because the spring retaining member 214 is pressed against the end surface of the cylindrical portion 202a of the shaft receiving member 202 in the first direction M1A by the brake engagement spring 211 and the drum drive coupling spring 210, the spring retaining member 214 abuts against the end surface of the cylindrical portion 202a of the shaft receiving member 202.

[0113] In addition, such as Figure 8B and Figure 9 As shown, the brake transmission component 207 includes a boss portion 207f protruding in the second direction M1B. The brake transmission component 207 receives the pushing force of the brake engagement spring 211 via the flange portion 204a of the first brake engagement component 204, and directly receives the pushing force of the drum drive coupling spring 210. Therefore, the boss portion 207f of the brake transmission component 207 abuts against the abutment surface 180g of the drum drive coupling 180.

[0114] The drum drive coupling 180 also receives the pushing force of the brake engagement spring 211 and the drum drive coupling spring 210 via the brake transmission member 207, and is pushed in the second direction M1B. For example... Figure 9 As shown, the flange portion 180a of the drum drive coupling 180 abuts against and is fixed to the control portion 212 of the drive frame 102, thereby preventing the drum drive coupling 180 from moving in the second direction M1B. Therefore, the drum drive coupling 180 will not detach from the drive gear 201. In addition, if the drum drive coupling 180 receives a force from the outside in the first direction M1A, the drum drive coupling 180 overcomes the pushing force of the brake engagement spring 211 and the drum drive coupling spring 210 and moves along the first direction M1A within the range of the aforementioned gap G.

[0115] like Figure 10B As shown, the connecting engagement portion 204b of the first brake engagement member 204 and the connecting engagement portion 208b of the second brake engagement member 208 are exposed through the through hole 180f of the drum drive connector 180. With the housing P attached to the device body 1A, the connecting engagement portions 204b and 208b face the drum connector 63 via the through hole 180f.

[0116] The through hole 180f is formed to be wider than the width of each of the connecting portions 204b and 208b in the circumferential direction around the rotation axis M1. Therefore, as... Figure 10CAs shown, the coupling portions 204b and 208b can rotate relative to the drum drive coupling 180 within the range of the through hole 180f.

[0117] Connection between drum drive connector and drum connector

[0118] Next, the connection between the drum drive connector 180 and the drum connector 63 will be described. Figure 11 This is a cross-sectional view showing the drum drive connector 180 and the drum connector 63 engaged with each other. Figure 12 This is an enlarged cross-sectional view showing the area near the protrusion 63e of the drum connector 63.

[0119] like Figure 11 As shown, if the box P is attached to the device body 1A, the positioning boss 180i of the drum drive connector 180 and the circular hole portion 63a of the drum connector 63 engage with each other. In this state, the drum drive connector 180 receives a force from the drum connector 63 in the first direction M1A. Therefore, the drum drive connector 180 moves in the first direction M1A against the pushing force of the brake engagement spring 211 and the drum drive connector spring 210. Since the boss portion 207f of the brake transmission member 207 abuts against the abutment surface 180g of the drum drive connector 180, the brake transmission member 207 moves integrally with the drum drive connector 180 in the first direction M1A.

[0120] Because the brake transmission component 207 is in the aforementioned gap G (see...) Figure 9 The brake transmission member 207 moves in the decreasing direction, so the protrusion 207e of the brake transmission member 207 engages with the convex portion 204e of the first brake engagement member 204, as shown. Figure 11 As shown. Thus, the brake transmission component 207, the first brake engagement component 204, the second brake engagement component 208, and the brake transmission shaft 209 constituting the brake force application unit 260 rotate integrally with each other around the rotation axis M1. Furthermore, the inner ring 206b of the brake portion 206 rotates integrally with the brake transmission shaft 209.

[0121] If the drive gear 201 is driven by the motor M in the direction indicated by arrow A in Figure 8(a), then the drum drive coupling 180 assembled in the drive gear 201 also rotates in the direction indicated by arrow A. Therefore, as Figure 12As shown, the driving force transmission surface 180d of the drum drive coupling 180 engages with the driving force receiving portion 63b in the direction indicated by arrow A, and pushes the driving force receiving portion 63b in the direction indicated by arrow A. That is, the drum drive coupling 180 is an example of a coupling member capable of engaging with the driving force receiving portion 63b of the drum unit 68. The driving force receiving portion 63b is subjected to rotational drive (rotational force) in the direction indicated by arrow A, causing the drum unit 68, including the photosensitive drum 61 and the drum coupling 63, to rotate in the direction indicated by arrow A, as shown. Figure 4 As shown. The direction indicated by arrow A is used as the first rotation direction.

[0122] On the other hand, since the photosensitive drum 61 and the drum connector 63 rotate in the direction indicated by arrow A, the braking force receiving portion 63c of the drum connector 63 engages with the connector engagement portions 204b and 208b. In other words, the first brake engagement member 204 and the second brake engagement member 208 engage with the braking force receiving portion 63c of the drum unit 68 in the direction indicated by arrow B, which is opposite to the direction indicated by arrow A. The direction indicated by arrow B serves as the second rotation direction. That is, the first brake engagement member 204 and the second brake engagement member 208 are examples of brake engagement members that engage with the drum unit 68. The rotational drive from the motor M is transmitted from the drum drive connector 180 to the drum connector 63, and from the drum connector 63 to the brake engagement members (204, 208). As described above, the first brake engagement member 204, the second brake engagement member 208, the brake transmission member 207, the brake transmission shaft 209, and the inner ring 206b of the brake portion 206 are drivenly connected to each other to rotate in the rotation direction. Additionally, while rotating relative to the outer ring 206a about the rotation axis M2, the inner ring 206b generates a braking force to apply a load to the rotation of the photosensitive drum 61. The braking force is applied to the braking force receiving portion 63c via a braking force application unit 260, which includes a first braking engagement member 204 and a second braking engagement member 208.

[0123] Therefore, while receiving an appropriate load (braking force) from the first brake engagement member 204 and the second brake engagement member 208, the drum connector 63 rotates in the direction indicated by arrow A via the rotational drive received from the drum drive connector 180. That is, the torque required to rotate the drum connector 63 increases due to the load (braking force) generated by the brake section 206. Consequently, the torque required by the drum drive connector 180 to rotate the drum unit 68 is not too low but appropriate, thereby stabilizing the rotation of the drum unit 68. In other words, unstable rotation of the drum unit 68, such as sudden rapid rotation of the drum unit 68 caused by changes in the rotational drive received from the drum drive connector 180, can be prevented.

[0124] Drive force transmission for developing connectors

[0125] Next, we will refer to Figure 13A to Figure 14B Describes the transmission of driving force from motor M to developing connector 72. Figure 13A This is a schematic diagram showing the driving force transmission path followed when the clutch unit 120 is in the transmission state, as the driving force is transmitted from the motor M to the developing coupling 72. Figure 13B This is a schematic diagram showing the driving force transmission path followed when the clutch unit 120 is in a non-transmission state, as the driving force is transmitted from the motor M to the developing coupling 72. Figure 14A This is a graph showing the torque applied to the developing connector 72 in the comparative example. Figure 14B This is a graph showing the torque applied to the developing coupling 72 in this embodiment.

[0126] like Figure 13A As shown, in this embodiment, the rotational drive of the motor M is transmitted to the developing connector 72 via two paths: a first driving force transmission path via the first driving force transmission unit 150 and a second driving force transmission path via the second driving force transmission unit 250. More specifically, the first driving force transmission path is the path followed by the rotational drive output from the motor M, which is transmitted to the developing connector 72 via the clutch unit 120, the developing drive gear 111, etc. The second driving force transmission path is the path followed by the rotational drive output from the motor M, which is transmitted to the developing connector 72 via the drum driving force transmission unit 203, the drum connector 63, the braking force application unit 260, the braking part 206, the developing drive gear 111, etc.

[0127] The torque transmitted to the developing drive gear 111 via the first driving force transmission unit 150 instead of the second driving force transmission unit 250 (i.e., the torque transmitted to the developing coupling 72 via the first driving force transmission path) is referred to as the first torque TCL. Furthermore, the torque transmitted to the developing drive gear 111 via the second driving force transmission unit 250 (i.e., the torque transmitted to the developing coupling 72 via the aforementioned second driving force transmission path) is referred to as the second torque TB. The second torque TB is transmitted to the developing coupling 72 via the braking portion 206.

[0128] Furthermore, the torque required to drive the developing connector 72 (i.e., the torque required to drive the developing unit 70) is referred to as the third torque TD. That is, the developing connector 72 is driven when a torque equal to or greater than the third torque TD is applied to it. The value of the second torque TB is determined by the performance of the braking section 206 constituted by the torque limiter, and the value of the first torque TCL is determined by the performance of the motor M. Additionally, the rotational speed of the outer ring 206a of the braking section 206 is represented by V1, and the rotational speed of the inner ring 206b of the braking section 206 is represented by V2.

[0129] like Figure 13A As shown, when the clutch unit 120 is in the transmission state, both the first torque TCL and the second torque TB are transmitted to the developing drive gear 111. In this case, the first torque TCL, the second torque TB, and the third torque TD satisfy the following formula.

[0130] TCL+TB≥TD (1)

[0131] That is, the sum of the first torque TCL and the second torque TB is equal to or greater than the third torque TD, and the developing coupling 72 is driven by both the first torque TCL and the second torque TB. Note that in the description of this embodiment, the reduction ratio (speed ratio) between the developing drive gear 111 and the developing coupling 72 is considered to be 1.

[0132] In addition, in this embodiment, the velocities V1 and V2 satisfy the following formula.

[0133] V1>V2 (2)

[0134] Therefore, the specifications of each gear in the drive force transmission mechanism 200 are set to satisfy the above formula (2). Thus, while receiving braking force from the inner ring 206b, the outer ring 206a of the braking section 206 rotates at a higher speed than the inner ring 206b. In other words, the rotational speed of the inner ring 206b is lower than that of the outer ring 206a, and the inner ring 206b rotates at a speed V2 higher than 0. Therefore, the inner ring 206b can apply braking force to the drum unit 68, thereby stabilizing the rotation of the drum unit 68.

[0135] In comparison, such as Figure 13B As shown, when the clutch unit 120 is in a non-transmission state, only the second torque TB is applied to the developing drive gear 111. In this embodiment, the braking portion 206, which is composed of a torque limiter, is selected such that the second torque TB and the third torque TD satisfy the following formula.

[0136] TB <TD (3)

[0137] In other words, the second torque TB is lower than the third torque TD. Therefore, when the clutch unit 120 is in the non-transmission state, the second drive force transmission unit 250 cannot drive the developing coupling 72. Furthermore, in this state, the inner ring 206b of the braking section 206 stops together with the developing coupling 72 and the developing drive gear 111, and the speed V2 of the inner ring 206b is zero. Similarly, in this state, to satisfy the formula V1>V2, the outer ring 206a rotates at a higher speed than the inner ring 206b while receiving braking force from the inner ring 206b. Regardless of whether the clutch unit 120 is in the transmission state or the non-transmission state, the drum coupling 63 is driven when the motor M is driven. Therefore, braking force can be applied to the drum unit 68, stabilizing the rotation of the drum unit 68.

[0138] exist Figure 14A In the comparative example shown, the second driving force transmission path described above is not formed, and the rotary drive is transmitted from the motor M to the developing coupling 72 only via the first driving force transmission path. That is, the developing coupling 72 is driven only by the first torque TCL. In this case, if the state of the clutch unit 120 switches from the transmission state to the non-transmission state, the torque applied to the developing coupling 72 immediately changes from the first torque TCL, which is higher than the third torque TD required to drive the developing coupling 72, to zero.

[0139] In contrast, in this embodiment, the developing coupling 72 is driven by both a first torque TCL and a second torque TB. That is, in this embodiment, the first torque TCL can be lower than the first torque TCL of the comparative example. In this embodiment, as... Figure 14B As shown, if the state of the clutch unit 120 switches from the transmission state to the non-transmission state, the torque applied to the developing coupling 72 changes from the sum of the first torque TCL and the second torque TB to a single second torque TB.

[0140] Therefore, in this embodiment, even if the state of the clutch unit 120 is switched to the non-transmission state, the second torque TB is still applied to the developing coupling 72. This reduces the torque change caused when the state of the clutch unit 120 switches from the transmission state to the non-transmission state. Consequently, the impact caused when the state of the clutch unit 120 switches from the transmission state to the non-transmission state can be reduced, thereby preventing deformation of the clutch unit 120 and reducing noise generated from the clutch unit 120.

[0141] Furthermore, since the change in torque (applied to the developing unit 70) caused by the switching of the clutch unit 120 from the transmitting state to the non-transmitting state can be reduced, the risk of frame deformation of cartridge P can be lowered. Additionally, since the required stiffness of cartridge P's frame can be reduced, the weight of cartridge P can be reduced, and the amount of toner that can be stored in cartridge P can be increased. Moreover, since the second torque TB is always applied to the developing coupling 72 regardless of the state of the clutch unit 120, the position of cartridge P can be stabilized, and the positional accuracy of cartridge P can be improved.

[0142] Other embodiments

[0143] Furthermore, in the above embodiments, the developing drive gear 111, which transmits rotational drive to the first driving force transmission unit 150 and the second driving force transmission unit 250, is a gear component. However, this disclosure is not limited thereto. For example, in addition to the developing drive gear 111, this disclosure can be applied to other rotating components, which may be pulleys that transmit driving force to the developing drive gear, or may be a component composed of a gear portion and a pulley portion combined with each other.

[0144] One or more embodiments of this disclosure can also be implemented by a computer of a system or device reading and executing computer-executable instructions (e.g., one or more programs) recorded on a storage medium (also more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above embodiments and / or including one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more of the above embodiments; and by a method performed by a computer of a system or device, for example, reading and executing computer-executable instructions from a storage medium to perform the functions of one or more of the above embodiments and / or controlling one or more circuits to perform the functions of one or more of the above embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessor unit (MPU)) and may include a network of individual computers or individual processors to read and execute the computer-executable instructions. The computer-executable instructions may, for example, be provided to the computer from a network or a storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), the memory of a distributed computing system, an optical disk (e.g., a compact optical disk (CD), a digital versatile optical disk (DVD), or a Blu-ray disc (BD)). TM One or more of the following: flash memory devices, memory cards, etc.

[0145] Other embodiments

[0146] Embodiments of the present invention can also be implemented by providing software (including computer program products of computer programs) that performs the functions of the above embodiments to a system or device via a network or various storage media, and the computer (central processing unit (CPU) or microprocessor unit (MPU) of the system or device) reads and executes the computer program.

[0147] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the following claims should be given the broadest interpretation in order to cover all such variations and equivalent structures and functions.

Claims

1. An image forming apparatus configured to form an image on a recording material, the image forming apparatus comprising: a drive source; a first driven member; a second driven member different from the first driven member; a first drive force transmission unit configured to transmit a drive force output from the drive source to the first driven member, the first drive force transmission unit including a clutch mechanism configured to switch between a transmission state and a non-transmission state, the transmission state being a state in which the drive force output from the drive source is transmitted to the first driven member, the non-transmission state being a state in which the drive force output from the drive source is not transmitted to the first driven member; and a second drive force transmission unit configured to transmit the drive force output from the drive source to the second driven member and connected to the first drive force transmission unit, the second drive force transmission unit including a braking portion configured to generate a braking force to apply a load to a rotation of the second driven member, wherein the second drive force transmission unit is connected to the first drive force transmission unit between the clutch mechanism and the first driven member, and wherein, with the clutch mechanism in the transmission state, the first driven member is driven by both a first torque transmitted via the first drive force transmission unit and a second torque transmitted via the braking portion of the second drive force transmission unit.

2. The image forming apparatus according to claim 1, wherein the first driven member is configured to be driven with a torque equal to or higher than a third torque applied to the first driven member, wherein a sum of the first torque and the second torque is equal to or higher than the third torque, and wherein the second torque is lower than the third torque.

3. The image forming apparatus according to claim 1, wherein the second driven member is driven when the drive source is driven regardless of whether the clutch mechanism is in the transmission state or in the non-transmission state.

4. The image forming apparatus according to claim 1, wherein the first driven member is a developing link configured to drive a developing roller, the developing roller being configured to carry toner.

5. The image forming apparatus according to claim 1, wherein the second driven member is a drum link configured to drive a photosensitive drum, the photosensitive drum being configured to carry a toner image.

6. The image forming apparatus according to claim 1, further comprising: an apparatus body including the drive source, the first drive force transmission unit, and the second drive force transmission unit; and a detachable unit including the first driven member and the second driven member, the detachable unit being configured to be detachably attached to the apparatus body.

7. The image forming apparatus according to claim 1, further comprising an actuator configured to switch a state of the clutch mechanism between the transmission state and the non-transmission state. ​ ​ 8. The image forming apparatus according to claim 1, wherein the braking portion includes a torque limiter.

9. The image forming apparatus according to claim 1, wherein the first drive force transmission unit includes a rotating body configured to rotate, the drive force output from the drive source is transmitted to the rotating body in a case where the clutch mechanism is in the transmission state, and the drive force output from the drive source is not transmitted to the rotating body in a case where the clutch mechanism is in the non-transmission state, wherein the braking portion includes: a first rotating member to which the drive force output from the drive source is transmitted; and a second rotating member that is drivingly connected to the rotating body, wherein the first rotating member is configured to rotate with respect to the second rotating member while receiving a braking force, and wherein the second rotating member rotates at a lower speed than the first rotating member in a case where the clutch mechanism is in the transmission state, and stops together with the first driven member and the rotating body in a case where the clutch mechanism is in the non-transmission state.

10. The image forming apparatus according to any one of claims 1 to 9, wherein the second drive force transmission unit includes a braking force application portion configured to apply a braking force to the second driven member.

11. The image forming apparatus according to claim 10, wherein the second drive force transmission unit includes an engaging member configured to engage with the second driven member, and wherein the braking force application portion includes a braking engaging member configured to engage with the second driven member.

12. The image forming apparatus according to claim 11, wherein the second driven member is configured to rotate in a first rotation direction when a drive force is transmitted to the second driven member via the second drive force transmission unit, wherein the engaging member is configured to engage with the second driven member in the first rotation direction, and wherein the braking engaging member is configured to engage with the second driven member in a second rotation direction opposite to the first rotation direction.

13. The image forming apparatus according to claim 10, wherein the second drive force transmission unit includes a drive force transmission portion configured to transmit the drive force output from the drive source to the second driven member, and wherein the second torque is transmitted from the drive source to the second driven member via the drive force transmission portion, the second driven member, the braking force application portion, and the braking portion. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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