JP2022093265A - Oldham coupling and image forming apparatus - Google Patents

Abstract

To provide an Oldham coupling that has play in a rotation direction and can transmit a driving force.SOLUTION: In an Oldham coupling 1 having a development drive gear 99 being a first hub, a drive coupling 89 being a second hub, and an intermediate member 3 transmitting a driving force between the development drive gear 99 and the drive coupling 89, the development drive gear 99 has a projection 99a fitted to a concave part 3a of the intermediate member 3 and transmitting the driving force between the intermediate member 3 and the projection, and when seen from a rotation axis direction of the Oldham coupling 1, a projection 89a has a substantially diamond shape.SELECTED DRAWING: Figure 12

Description

The present invention relates to an oldham coupling that transmits drive from a drive source to a unit to be driven, and an image forming apparatus including the same.

Conventionally, a configuration has been used in which a drive is transmitted from a motor to each unit to be driven by a drive train using gears or the like. For example, Patent Document 1 describes a configuration in which a single motor is used to rotate both a photosensitive drum and a developing sleeve included in a developing unit.

Further, Patent Document 1 describes a configuration for selectively rotating a plurality of driven objects, a photosensitive drum and a developing sleeve. In the configuration of Patent Document 1, in a power transmission mechanism for transmitting a driving force from a driving source to a developing sleeve and a photosensitive drum to be driven, a coupling having a play of a predetermined rotation angle is provided in the driving row. With such a configuration, it is possible to selectively transmit the driving force to the driving target when the motor is rotated in the forward direction and when the motor is rotated in the reverse direction.

Japanese Unexamined Patent Publication No. 8-234643

On the other hand, in a power transmission mechanism that transmits a driving force from a driving source to a unit to be driven, it is conceivable that the unit to be driven is attached to and detached from a device provided with the driving source. In this case, the rotation axis of the drive source and the rotation axis of the unit to be attached / detached are likely to deviate from each other.

In this way, in a configuration in which the rotation axes of the two rotation axes are easily displaced, a configuration in which the driving force can be transmitted even when the rotation axes of the two rotation axes are displaced by providing an oldham coupling may be used. be.

Generally, the Oldham coupling comprises an intermediate member that transmits driving force between the first hub, the second hub, and the first hub and the second hub. Here, as the configuration of the Oldham coupling, as in the coupling shape of Patent Document 1, in order to selectively transmit the driving force to the driving target in the case where the motor is rotated in the forward direction and the case where the motor is rotated in the reverse direction. When applying the configuration, the driving force may not be transmitted.

That is, in the two couplings described in Patent Document 1, the shape of one is considered as the first hub and the shape of the other is considered as the intermediate member. In this case, since the intermediate member cannot move in the radial direction with respect to the first hub, it is driven when the rotation axis between the first rotation axis on the drive source side and the second rotation axis on the unit to be driven is deviated. There is a risk that force cannot be transmitted. That is, when a configuration having play in the rotation direction as in Patent Document 1 is applied, the driving force cannot be transmitted in a state where the rotation axes of the two rotation axes are deviated, and the old dam coupling does not function.

Therefore, in view of the present situation, it is an object of the present invention to provide an old dam coupling capable of transmitting a driving force even if the configuration has play in the rotation direction.

A typical configuration of an orthogonal coupling according to the present invention for achieving the above object is an intermediate structure in which a driving force is transmitted between a first hub, a second hub, and the first hub and the second hub. In an Oldham coupling having a member, either one of the intermediate member and the first hub is formed on an end surface in the rotation axis direction of the Oldam coupling, is recessed in the rotation axis direction, and is orthogonal to the rotation axis direction. It has a first recess extending in the first direction, and the first recess has a first inner wall on one side in the second direction orthogonal to the rotation axis direction and the first direction, and the other side in the second direction. It has a second inner wall extending in parallel with the first inner wall, and any one of the intermediate member and the first hub projects in the direction of the rotation axis and fits into the first recess. It has a first protruding portion that transmits a driving force between the intermediate member and the first hub, and the first protruding portion is the first inner wall when the orthogonal coupling rotates in the first rotation direction. A first edge portion that comes into contact with, a second edge portion that contacts the second inner wall when the orthogonal coupling rotates in the first rotation direction, and a second edge portion in which the orthogonal coupling is opposite to the first rotation direction. The third edge that contacts the first inner wall when rotating in two rotation directions and the second inner wall when the orthogonal coupling rotates in the second rotation direction opposite to the first rotation direction. When the first edge portion is in contact with the first inner wall and the second edge portion is in contact with the second inner wall, the third edge portion is in contact with the second inner wall. 1 The inner wall is separated from the inner wall, the fourth edge is separated from the second inner wall, the third edge is in contact with the first inner wall, and the fourth edge is in contact with the second inner wall. If so, the first edge is separated from the first inner wall, the second edge is separated from the second inner wall, and the orthogonal coupling is in the second rotation direction of the motor. When rotating with rotation to, the portion farthest from the first rotation center, which is the rotation center of the first hub in the first edge in the first direction, is the first rotation in the second direction. The portion located closer to the second inner wall than the center and farthest from the first rotation center in the second edge portion in the first direction is from the first rotation center in the second direction. Is also located near the first inner wall, and when the orthogonal coupling rotates with the rotation of the motor in the first rotation direction, the first in the first direction. The portion of the three edges farthest from the first rotation center is located closer to the second inner wall than the first rotation center in the second direction, and the fourth edge in the first direction. The portion of the portion farthest from the first rotation center is characterized in that it is located closer to the first inner wall than the first rotation center in the second direction.

According to the present invention, it is possible to provide an Oldham coupling having play in the rotation direction and being able to transmit a driving force.

It is sectional drawing of the image forming apparatus. It is a perspective view of a process cartridge. It is sectional drawing of the process cartridge. It is a perspective view of a drum unit. (A)-(d) is a cross-sectional view of a drum unit. It is a perspective view of a developing unit. (A), (b) is a front view and a rear view of a drive unit. It is a figure which shows the gear of a drive unit. It is a figure which shows the structure of (a), (b) drive coupling, drum coupling, development coupling. It is an exploded perspective view of the Oldham coupling. It is an exploded perspective view of the Oldham coupling. (A), (b) It is a figure which shows the fitting part of the development drive gear of the Oldham coupling, an intermediate member, and a drive coupling. It is a timing chart which shows the operation timing of each member after the image formation operation is completed. It is an exploded perspective view of the Oldham coupling. It is an exploded perspective view of the Oldham coupling. (A), (b) It is a figure which shows the fitting part of the development drive gear of the Oldham coupling, an intermediate member, and a drive coupling.

(First Embodiment)
<Image forming device>
Hereinafter, the overall configuration of the image forming apparatus including the Oldham coupling according to the present invention will be described with reference to the drawings together with the operation at the time of image forming. The dimensions, materials, shapes, relative arrangements, etc. of the components described below are not intended to limit the scope of the present invention to those, unless otherwise specified.

The image forming apparatus A according to the present embodiment transfers the toners of four colors of yellow Y, magenda M, cyan C, and black K as a developer to an intermediate transfer belt, and then transfers the image to a sheet to form an image. It is an intermediate tandem type image forming apparatus. In the following description, Y, M, C, and K are added as subscripts to the members that use the toner of each color, except that the composition and operation of each member are different in the color of the toner used. Since they are substantially the same, the subscripts are omitted as appropriate unless a distinction is required.

FIG. 1 is a schematic cross-sectional view of the image forming apparatus A. As shown in FIG. 1, the image forming apparatus A includes an image forming unit 61 that forms an image on the sheet S. The image forming unit 61 includes a process cartridge 65 (65Y, 65M, 65C, 65K), a laser scanner unit 28, a primary transfer roller 31 (31Y, 31M, 31C, 31K), an intermediate transfer belt 30, a secondary transfer roller 51, and a second. The next transfer facing roller 52 is provided.

Each process cartridge 65 (image forming unit) is configured to be detachably attached to the image forming apparatus A. Each process cartridge 65 includes a photosensitive drum 26 (26Y, 26M, 26C, 26K) and a charging roller 27 (27Y, 27M, 27C, 27K) as photoconductors. Further, each process cartridge 65 has a developing unit 29 (29Y, 29M, 29C, 29K) having a developing sleeve 71 (71Y, 71M, 71C, 71K) as a developing agent carrier, and a cleaning blade 45 (45Y, 45M, 45C). , 45K).

Next, the image forming operation will be described. First, when the control unit (not shown) receives the image forming job signal, the sheet S loaded and stored in the sheet cassette 22 is conveyed to the resist roller 24 by the feeding roller 66. After that, the resist roller 24 conveys the sheet S to the secondary transfer portion formed by the secondary transfer roller 51 and the secondary transfer opposed roller 52 at a predetermined timing.

On the other hand, in the image forming unit 61, the surface of the photosensitive drum 26Y is first charged by the charging roller 27Y. After that, the laser scanner unit 28 irradiates the surface of the photosensitive drum 26Y with the laser beam according to the image data input from the external device (not shown). As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 26Y.

Next, the developing sleeve 71Y of the developing unit 29Y adheres the yellow toner to the electrostatic latent image formed on the surface of the photosensitive drum 26Y, and forms the yellow toner image on the surface of the photosensitive drum 26Y. The toner image formed on the surface of the photosensitive drum 26Y is primarily transferred to the intermediate transfer belt 30 by applying a bias to the primary transfer roller 31Y. After that, the toner remaining on the surface of the photosensitive drum 26Y is scraped off by the cleaning blade 45Y. The cleaning blade 45Y abuts on the surface of the photosensitive drum 26Y so as to serve as a counter with respect to the rotation direction of the photosensitive drum 26Y at the time of image formation.

By the same process, magenta, cyan, and black toner images are formed on the photosensitive drums 26M, 26C, and 26K. Then, by applying a bias to the primary transfer rollers 31M, 31C, and 31K, these toner images are transferred superimposed on the yellow toner image on the intermediate transfer belt 30. As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 30. After that, the toner remaining on the surface of the photosensitive drums 26M, 26C, 26K is scraped off by the cleaning blades 45M, 45C, 45K.

The intermediate transfer belt 30 orbits along with the rotation of the secondary transfer facing roller 52. When the intermediate transfer belt 30 carrying the full-color toner image moves, the toner image is sent to the secondary transfer unit. Then, in the secondary transfer unit, a bias is applied to the secondary transfer roller 51, so that the toner image on the intermediate transfer belt 30 is transferred to the sheet S.

Next, the sheet S to which the toner image is transferred is conveyed to the fixing portion 36, and is heated and pressurized in the fixing portion 36, whereby the toner image on the sheet S is fixed to the sheet S. After that, the sheet S on which the toner image is fixed is discharged to the discharge unit 40 by the discharge roller 38.

<Process cartridge>
Next, the configuration of the process cartridge 65 will be described.

FIG. 2 is a perspective view of the process cartridge 65. FIG. 3 is a cross-sectional view of the process cartridge 65. As shown in FIGS. 2 and 3, the process cartridge 65 is composed of a drum unit 42 and a developing unit 29.

First, the configuration of the drum unit 42 will be described. FIG. 4 is a perspective view of the drum unit 42. 5 (a) to 5 (d) are cross-sectional views of the periphery of the photosensitive drum 26 in the drum unit 42. The state in which the charging roller 27 is separated from the photosensitive drum 26 is shown in the order of FIGS. 5 (a) to 5 (d). As shown in FIGS. 4 and 5 (a) to 5 (d), the drum unit 42 has a photosensitive drum 26, a charging roller 27, and a cleaning blade 45 (FIG. 3), and these members are formed by a drum container 11. It is held integrally.

The drum container 11 rotatably holds the photosensitive drum 26. On one end side of the photosensitive drum 26 in the drum container 11 in the direction of the rotation axis, a drum coupling 13 that receives a driving force from a drive unit 90 (FIG. 7) described later is provided integrally with the photosensitive drum 26. The drum coupling 13 is arranged on the back surface side of the image forming apparatus A in the drum container 11. Further, flange gears 14 are provided integrally with the photosensitive drum 26 at both ends of the photosensitive drum 26 in the direction of the rotation axis.

Further, the drum container 11 is provided with a recovery unit 16 (FIG. 3) for recovering the toner removed by the cleaning blade 45 from the surface of the photosensitive drum 26. Inside the recovery unit 16, a transfer screw 17 for transporting the toner in the collection unit 16 to the outside of the drum unit 42 is provided. The transport screw 17 rotates by transmitting a driving force from the flange gear 14 via the idler gear 67 to transport toner. The toner conveyed to the outside of the drum unit 42 by the transfer screw 17 is collected in a container (not shown) provided in the image forming apparatus A.

Further, the drum container 11 is provided with a bearing 19 that rotatably holds the charging roller 27. The bearing 19 is held in the drum container 11 so as to be slidable in the direction of approaching or separating from the photosensitive drum 26, and is urged toward the photosensitive drum 26 by the spring 12. Due to this urging force, the charging roller 27 presses against the photosensitive drum 26 and rotates in accordance with the rotation of the photosensitive drum 26.

One-way clutches 21 are provided at both ends of the charging roller 27. When a torque is applied in the direction opposite to the rotation direction of the charging roller 27 at the time of image formation, the one-way clutch 21 is locked and rotates integrally with the charging roller 27. Further, the one-way clutch 21 is released from the locked state when a predetermined torque (idling torque) or more in the same direction as the rotation direction of the charging roller 27 at the time of image formation is applied, and the driving force is transmitted to and from the charging roller 27. It spins without it. In the present embodiment, the one-way clutch 21 is configured to use a latch claw and a rack.

Further, on the outer peripheral portion of the one-way clutch 21, a separating member 32 having a gear portion 32a that meshes with the flange gear 14 provided at both ends of the photosensitive drum 26 is provided. The separating member 32 and the one-way clutch 21 always rotate integrally regardless of the rotation direction. That is, when the charging roller 27 rotates in the direction opposite to the rotation direction at the time of image formation in accordance with the rotation of the photosensitive drum 26, the one-way clutch 21 and the separating member 32 rotate in conjunction with this. In the separating member 32, the charging roller 27 is pressed against the photosensitive drum 26 for a long time to prevent the charging roller 27 from being deformed and adversely affecting the image quality. Separate from 26.

That is, as shown in FIG. 5A, while the image forming apparatus A is performing the image forming operation, the gear portion 32a of the separating member 32 and the flange gear 14 are separated from each other and do not mesh with each other. When a predetermined time (8 hours in this embodiment) elapses after the image forming apparatus A finishes the image forming operation, the photosensitive drum 26 is rotated in the direction opposite to the rotation direction at the time of image forming. As a result, the charging roller 27 also follows the rotation of the photosensitive drum 26 and rotates in the direction opposite to the rotation direction at the time of image formation, and the one-way clutch 21 and the separating member 32 also rotate. As shown in FIG. 5B, when the separating member 32 rotates, the gear portion 32a of the separating member 32 meshes with the flange gear 14. In the present embodiment, when the charging roller 27 rotates 54 degrees, the one-way clutch 21 is locked. As a result, the gear portion 32a of the separating member 32 that rotates integrally with the one-way clutch 21 meshes with the flange gear 14. The charging roller 27 rotates at a diameter ratio with that of the photosensitive drum 26 until the gear portion 32a of the separating member 32 meshes with the flange gear 14. In the present embodiment, the diameter of the photosensitive drum 26 is φ30 mm and the diameter of the charging roller 27 is φ14 mm, so that the amount of rotation of the photosensitive drum 26 is 25.2 degrees.

Next, as shown in FIG. 5C, when the photosensitive drum 26 and the charging roller 27 continue to rotate in the direction opposite to the rotation direction at the time of image formation, the one-way clutch 21 and the separating member 32 also rotate further. When the separating member 32 further rotates, a force acts on the charging roller 27 in the direction of separating from the photosensitive drum 26 due to the shape of the separating member 32, and the charging roller 27 is exposed to light against the urging force of the spring 12 by this force. Separate from the drum 26. In the present embodiment, when the charging roller 27 further rotates 45 degrees after the gear portion 32a of the separating member 32 meshes with the flange gear 14, the charging roller 27 is separated from the photosensitive drum 26. After meshing with the gear portion 32a of the separating member 32 and the flange gear 14, the charging roller 27 rotates at the gear ratio between the gear portion 32a of the separating member 32 and the flange gear 14. In the present embodiment, the separation amount between the photosensitive drum 26 and the charging roller 27 is 1 mm, so that the rotation amount of the photosensitive drum 26 is 24 degrees. The charging roller 27 separated from the photosensitive drum 26 performs an operation opposite to the above-mentioned separation operation by rotating the photosensitive drum 26 in the rotation direction at the time of image formation at the next image formation, and causes the photosensitive drum 26 to perform an operation opposite to the above-mentioned separation operation. Contact again.

Further, as shown in FIG. 5D, after the charging roller 27 is separated from the photosensitive drum 26, when the photosensitive drum 26 is continuously rotated in the direction opposite to the rotation direction at the time of image formation, the separating member 32 is released. There is a risk of contact with the drum container 11 and causing malfunction. In the present embodiment, when the charging roller 27 and the photosensitive drum 26 are separated from each other and further rotated by 45 degrees (24 degrees by the amount of rotation of the photosensitive drum 26), the separating member 32 and the drum container 11 come into contact with each other. Therefore, in the present embodiment, in order to suppress the contact between the separating member 32 and the drum container 11 while separating the charging roller 27 from the photosensitive drum 26, the photosensitive drum 26 is oriented in the direction opposite to the rotation direction at the time of image formation. The amount of rotation is set to 49.2 degrees to 73.2 degrees.

Next, the configuration of the developing unit 29 will be described. FIG. 6 is a perspective view of the developing unit 29. In FIG. 6, a part of the developing container 70 is cut out and shown in order to explain the internal configuration of the developing unit 29. As shown in FIG. 6, the developing unit 29 includes a developing sleeve 71, a developing blade 72, and transfer screws 73, 74, and these members are integrally held by a developing container 70.

The developing container 70 has an opening in a portion facing the photosensitive drum 26, and the developing sleeve 71 is arranged so that a part of the developing container 70 is exposed in the opening. The developing sleeve 71 is arranged to face the photosensitive drum 26 with a predetermined interval (240 μm in this embodiment). A developing coupling 75 that receives a driving force from a driving unit 90 (FIG. 7), which will be described later, is provided on one end side of the developing sleeve 71 in the direction of the rotation axis. The developing sleeve 71 rotates by transmitting a driving force from the driving unit 90 via the developing coupling 75.

The development coupling 75 is one end side of the development sleeve 71 in the development container 70 in the direction of the rotation axis, and is held in the development container 70 at a position on the back surface side of the image forming apparatus A. A D-cut shaped engaging portion (not shown) that engages with the developing coupling 75 is formed on the rotating shaft of the developing sleeve 71, whereby the developing sleeve 71 rotates integrally with the developing coupling 75. .. Further, a sleeve gear 81 is provided on one end side of the developing sleeve 71 in the developing container 70. The sleeve gear 81 is connected to the rotating shaft of the developing sleeve 71 by a parallel pin (not shown), and rotates integrally with the developing sleeve 71.

Further, the developing sleeve 71 includes a magnet roller 76 (FIG. 3) having a plurality of magnetic poles in a non-rotating state. As shown in FIG. 3, the magnet roller 76 has a developing electrode S1 in a developing region located at a position facing the photosensitive drum 26. Further, the magnet roller 76 has a transport pole N1, a stripping pole N2, a pumping pole S2, and a cut pole N3 in this order on the downstream side of the developing pole S1 in the rotation direction of the developing sleeve 71 at the time of image formation. When the developing pole S1 is 0 degrees, the center position of each of these magnetic poles is 60 degrees for the transport pole N1 and the stripping pole along the rotation direction (counterclockwise direction in FIG. 3) of the developing sleeve 71 at the time of image formation. N2 is 180 degrees, the pumping pole S2 is 230 degrees, and the cut pole N3 is 290 degrees. At the time of image formation, the magnet roller 76 carries the toner by the magnetic force of each magnetic pole and conveys the toner to the developing region.

That is, the magnet roller 76 first pumps the toner contained in the developing container 70 by the pumping electrode S2, and carries the toner on the developing sleeve 71. Next, the toner supported on the developing sleeve 71 is brushed by the cut electrode N3. After that, the spiked toner is conveyed to the developing region by the rotation of the developing sleeve 71, and is moved onto the photosensitive drum 26 by the developing electrode S1. After that, the toner remaining in the developing sleeve 71 gradually rises toward the central position between the transport electrode N1 and the stripping electrode N2 due to the repulsive magnetic field formed by the transport electrode N1 and the stripping electrode N2, and finally. It is peeled off from the developing sleeve 71.

Further, in the vicinity of the developing sleeve 71, a developing blade 72 is provided at a predetermined distance from the developing sleeve 71. The developing blade 72 abuts on the toner supported on the developing sleeve 71 to form a toner layer having a predetermined thickness. Specifically, as the developing sleeve 71 rotates, the toner supported on the developing sleeve 71 and spiked by the cut electrode N3 passes between the tip of the developing blade 72 and the surface of the developing sleeve 71. As a result, the amount of toner is regulated and the toner layer is formed. Further, on the side of the developing blade 72 opposite to the side on which the developing sleeve 71 is arranged, a squeeze sheet 77 for suppressing the scattering of toner to the outside of the developing container 70 is attached.

Further, the inside of the developing container 70 is divided into a developing chamber 79 and a stirring chamber 80 by a partition wall 78 extending in the rotation axis direction of the developing sleeve 71. At both ends of the partition wall 78 in the longitudinal direction, communication portions (not shown) for communicating the developing chamber 79 and the stirring chamber 80 are provided.

The developing chamber 79 and the stirring chamber 80 are provided with transport screws 73 and 74 that convey toner by rotating blades. The transport screws 73 and 74 transport toner in the longitudinal direction of the partition wall 78 and in opposite directions to each other. The transport screws 73 and 74 rotate by transmitting a driving force from a sleeve gear 81 provided integrally with the developing sleeve 71. When the transfer screws 73 and 74 rotate, toner circulates between the developing chamber 79 and the stirring chamber 80 via a communication portion (not shown).

Further, every time the image forming operation is performed, toner is deposited in the space surrounded by the developing sleeve 71, the developing blade 72, and the squeeze sheet 77 in the developing container 70. If the amount of the accumulated toner is excessive, the accumulated toner may invade the developing area and cause an image defect called a spot image. In order to suppress this, the developing sleeve 71 rotates in the direction opposite to the rotation direction at the time of image formation during non-image forming after the image forming operation is performed a predetermined number of times, and the developing sleeve 71, the squeeze sheet 77, and the developing blade 72 rotate. The toner deposited in the enclosed space is moved to the stirring chamber 80 side. Specifically, the toner raised by the repulsive magnetic field formed by the transport electrode N1 and the stripping electrode N2 passes through the space surrounded by the developing sleeve 71, the squeeze sheet 77, and the developing blade 72 by the rotation of the developing sleeve 71. , The toner accumulated in this space is pushed back to the stirring chamber 80 side. In this embodiment, the development sleeve 71 is rotated in the opposite direction every time 500 images are formed on A4 paper.

Here, when the amount of rotation of the developing sleeve 71 in the direction opposite to the rotation direction at the time of image formation is large, the toner pumped up by the pumping electrode S2 does not pass through the developing blade 72, and a large amount of toner is conveyed to the developing region. It ends up. As a result, the toner may be scattered to the outside of the developing container 70. Therefore, in order to suppress the scattering of the toner to the outside, the amount of rotation of the developing sleeve 71 in the direction opposite to the rotation direction at the time of image formation is set to an angle from the transport electrode N1 to the stripping electrode N2. That is, in the present embodiment, the angle around the rotation axis of the developing sleeve 71 is set to an angle of 60 to 180 degrees.

<Drive unit>
Next, the configuration of the drive unit 90 that drives the process cartridge 65 will be described.

FIG. 7A is a front view of the drive unit 90. FIG. 7B is a rear view of the drive unit 90. FIG. 8 is a diagram showing a gear included in the drive unit 90. As shown in FIGS. 7 (a), 7 (b), and 8, the drive unit 90 includes a box-shaped drive frame 91 formed by the rear frame 91a and the front frame 91b.

The drive frame 91 is fixed to the photosensitive drums 26Y, 26M, 26C, the motor 92a which is the drive source of the developing sleeves 71Y, 71M, 71C, and the motor 92b which is the drive source of the photosensitive drum 26K and the developing sleeve 71K. .. In this embodiment, the motors 92a and 92b are DC brushless motors.

A pinion gear 93a is attached to the shaft of the motor 92a. The drum reduction gear 94a1 meshes with the pinion gear 93a, and the drum drive gears 95M and 95C mesh with the drum reduction gear 94a1. Further, the drum reduction gear 94a2 meshes with the drum drive gear 95M and the drum drive gear 95Y. Due to the gear ratio of these gear trains, the rotation speed of the drum drive gears 95Y, 95M, 95C is reduced with respect to the rotation speed of the motor 92a.

A pinion gear 93b is attached to the shaft of the motor 92b. The drum reduction gear 94b meshes with the pinion gear 93b, and the drum drive gear 95K meshes with the drum reduction gear 94b. Due to the gear ratio of these gear trains, the rotation speed of the drum drive gear 95K is reduced with respect to the rotation speed of the motor 92b.

Further, on the same axis as the drum drive gears 95Y, 95M, 95C, 95K, drive couplings 96Y, 96M, 96C, 96K that engage with the drum coupling 13 provided on the process cartridges 65Y, 65M, 65C, 65K are provided. Has been done. Here, as shown in FIG. 9A, a play α in the rotation direction is provided between the drive coupling 96 of each color and the drum coupling 13. In the present embodiment, the play α is set to 34 degrees at an angle around the rotation axis of the photosensitive drum 26.

With such a configuration, the driving force of the motor 92a is transmitted to the drum coupling 13 via the pinion gear 93a, the drum reduction gears 94a1, 94a2, the drum drive gears 95Y, 95M, 95C, and the drive coupling 96Y, 96M, 96C. Will be done. As a result, the photosensitive drums 26Y, 26M, and 26C rotate. The driving force of the motor 92b is transmitted to the drum coupling 13 via the pinion gear 93b, the drum reduction gear 94b, the drum drive gear 95K, and the drive coupling 96K, whereby the photosensitive drum 26K rotates.

Further, the development reduction gear 97a meshes with the pinion gear 93a. Further, the plurality of idler gears 98a to 98g are provided so as to form a gear train with the development reduction gear 97a. The idler gears 98a, 98d, and 98g mesh with the development drive gears 99Y, 99M, and 99C, respectively. Due to the gear ratio of these gear trains, the rotation speed of the developing sleeves 71Y, 71M, 71C is reduced with respect to the rotation speed of the motor 92a so as to be 198% of the rotation speed of the photosensitive drums 26Y, 26M, 26C. ..

Further, the pinion gear 93b meshes with the development drive gear 99K via a gear train formed by the drum reduction gear 94b, the idler gear 98h, the development reduction gear 97b, and the idler gear 98i. Due to the gear ratio of these gear trains, the rotation speed of the developing sleeve 71K is reduced with respect to the rotation speed of the motor 92b so as to be 198% of the rotation speed of the photosensitive drum 26K.

Further, the rotation shafts of the development drive gears 99Y, 99M, 99C, 99K (not shown) are provided on the process cartridges 65Y, 65M, 65C, 65K shown in FIG. 7A by the Oldham coupling 1 (FIG. 10) described later. It is connected to the rotating shafts 100Y, 100M, 100C, 100K of the developing coupling 75. Further, the development coupling 75 engages with the drive couplings 89Y, 89M, 89C, 89K forming a part of the Oldham coupling 1. Here, as shown in FIG. 9B, the developing coupling 75 has three protrusions, and the drive coupling 89 has three fitting grooves into which the three protrusions of the drive coupling 75 are fitted. There are two. As described above, by providing three or more protrusions of one coupling and fitting grooves of the other coupling, the drive can be stably transmitted. A play β in the rotation direction is provided between the fitting groove of the drive coupling 89 of each color and the protrusion of the developing coupling 75. In the present embodiment, the play β is set to 30 degrees at an angle around the rotation axis of the developing sleeve 71.

With such a configuration, the driving force of the motor 92a is a developing cup via a pinion gear 93a, a developing reduction gear 97a, an idler gear 98a to 98g, a developing drive gear 99Y, 99M, 99C, and a drive coupling 89Y, 89M, 89C. It is transmitted to the ring 75. As a result, the developing sleeves 71Y, 71M, and 71C rotate. The driving force of the motor 92b is transmitted to the developing coupling 75 via the pinion gear 93b, the developing reduction gear 97a, the idler gears 98h and 98i, the developing driving gear 99K, and the driving coupling 89K. As a result, the developing sleeve 71K rotates.

As described above, in the present embodiment, the rotation speed of the developing sleeve 71 of each color is 198% of the rotation speed of the photosensitive drum 26 of each color. Further, in the present embodiment, the diameter of the photosensitive drum 26 is φ30 mm, and the diameter of the developing sleeve 71 is φ18 mm. Therefore, the difference in gear ratio between the photosensitive drum 26 and the developing sleeve 71 is 3.3 times. That is, when the photosensitive drum 26 makes one round, the developing sleeve 71 makes 3.3 rounds.

<Oldham Coupling>
Next, the configuration of the Oldham coupling 1 will be described.

FIG. 10 is an exploded perspective view of the Oldham coupling 1 as viewed from the front side of the image forming apparatus A. FIG. 11 is an exploded perspective view of the Oldham coupling 1 as viewed from the back side of the image forming apparatus A. FIG. 12A is a diagram showing a fitting portion between the developing drive gear 99 of the Oldham coupling 1 and the intermediate member 3. FIG. 12B is a diagram showing a fitting portion between the drive coupling 89 of the Oldham coupling 1 and the intermediate member 3.

As shown in FIGS. 10 and 11, the Oldham coupling 1 is formed between the development drive gear 99 (first hub), the drive coupling 89 (second hub), and the development drive gear 99 and the drive coupling 89. It is composed of an intermediate member 3 that transmits a driving force. The Oldham coupling 1 is rotatably held inside a coupling holder 2 provided on the front frame 91b.

In the direction of arrow X, which is the direction of the rotation axis of the old dam coupling 1, the end face on one side of the intermediate member 3 is recessed in the direction of arrow X and extends in the direction of arrow Y (first direction) orthogonal to the direction of arrow X. 3a (first recess) is formed. Further, in the arrow X direction, the other end surface of the intermediate member 3 is recessed in the arrow X direction and has a rectangular cross section recess 3b (second direction) extending in the arrow Z direction (second direction) orthogonal to the arrow X direction and the arrow Y direction. 2 recesses) are formed. The shapes of the recesses 3a and 3b are the same except that they extend in directions orthogonal to each other. The rotation axis direction of the Oldham coupling 1 is the same as the rotation axis direction of the developing drive gear 99, the rotation axis direction of the drive coupling 89, and the rotation axis direction of the intermediate member 3.

Further, in the rotation axis direction of the Oldham coupling 1 (arrow X direction), a convex portion 99a (first protruding portion) that protrudes in the arrow X direction at one end of the development drive gear 99 and fits into the concave portion 3a of the intermediate member 3. ) Is formed. Further, in the rotation axis direction of the Oldham coupling 1, a convex portion 89a (second protruding portion) is formed at one end of the drive coupling 89 so as to project in the arrow X direction and fit into the concave portion 3b of the intermediate member 3. There is.

When the developing drive gear 99 is rotated by the driving force of the motor 92a or the motor 92b, the convex portion 99a of the developing drive gear 99 slides relatively inside the concave portion 3a and comes into contact with the inner wall of the concave portion 3a to contact the intermediate member 3. The driving force is transmitted to the intermediate member 3 to rotate. Then, when the intermediate member 3 rotates, the convex portion 89a of the drive coupling 89 slides relatively inside the concave portion 3b, and the inner wall of the concave portion 3a comes into contact with the convex portion 89a to apply a driving force to the drive coupling 89. It transmits and the drive coupling 89 rotates. In this way, even when the rotation axis of the development drive gear 99 (not shown) and the rotation axis 100 of the development coupling 75 are deviated from each other, the driving force of the motor 92a or the motor 92b is developed via the Oldham coupling 1. It is stably transmitted to the rotating shaft 100 of the coupling 75.

Here, as shown in FIG. 12A, the convex portion 99a has one inner wall 3a1 (first inner wall) in the width direction of the concave portion 3a when the oldham coupling 1 rotates in the arrow R1 direction (first rotation direction). Has an edge 99a1 (first edge) in contact with. Further, the convex portion 99a has an edge portion 99a2 (second edge portion) that contacts the other inner wall 3a2 (second inner wall) in the width direction of the concave portion 3a when the oldham coupling 1 rotates in the direction of the arrow R1. Further, the convex portion 99a has an edge portion 99a3 (third edge portion) that contacts the inner wall 3a1 of the concave portion 3a and an edge portion that contacts the inner wall 3a2 when the oldham coupling 1 rotates in the arrow R2 direction (second rotation direction). It has 99a4 (fourth edge). The edges 99a1 to 99a4 come into surface contact with the inner wall 3a1 or the inner wall 3a2 of the recess 3a by the surfaces extending in the arrow Y direction and the arrow X direction. The width direction of the recess 3a is the arrow Z direction orthogonal to the arrow Y direction in which the recess 3a extends and the same direction as the direction in which the recess 3b extends.

Here, when the Oldham coupling 1 rotates in the direction of arrow R2, the portion farthest from the rotation center CT1 (first rotation center) of the development drive gear 99 in the edge portion 99a1 in the arrow Y direction is the rotation center in the arrow Z direction. It is located closer to the inner wall 3a2 than CT1. When the Oldham coupling 1 rotates in the direction of arrow R2, the portion of the edge 99a2 farthest from the center of rotation CT1 in the direction of arrow Y is located closer to the inner wall 3a1 than the center of rotation CT1 in the direction of arrow Z. When the Oldham coupling 1 rotates in the direction of arrow R1, the portion of the edge 99a3 farthest from the center of rotation CT1 in the direction of arrow Y is located closer to the inner wall 3a2 than the center of rotation CT1 in the direction of arrow Z. When the Oldham coupling 1 rotates in the direction of arrow R1, the portion of the edge 99a4 farthest from the center of rotation CT1 in the direction of arrow Y is located closer to the inner wall 3a1 than the center of rotation CT1 in the direction of arrow Z.

Further, the convex portion 99a has a shape in which a substantially rhombus is formed by the virtual line H1 connecting the edge portion 99a1, the edge portion 99a2, the edge portion 99a3, and the edge portion 99a4 when viewed from the rotation axis direction of the Oldham coupling 1. ing. Specifically, when the corner portion is formed by the virtual line in which the edge portion 99a1 and the edge portion 99a4 are extended, the angle of the corner portion is 45 degrees, and the virtual line in which the edge portion 99a2 and the edge portion 99a3 are extended is used. When forming the corners, a rhombus having an angle of 45 degrees is formed. It should be noted that the shape of the substantially rhombus may be a configuration having the above-mentioned corners or a shape in which the above-mentioned corners are chamfered.

With such a configuration, when the Oldham coupling 1 rotates in the direction of the arrow R2, there is play between the edge portion 99a1 and the inner wall 3a1 of the recess 3a, and between the edge portion 99a2 and the inner wall 3a2 of the recess 3a, respectively. γ1 is made. Further, when the Oldham coupling 1 rotates in the direction of the arrow R1, a similar play γ1 is created between the edge portion 99a3 and the inner wall 3a1 of the recess 3a and between the edge portion 99a4 and the inner wall 3a2 of the recess 3a. Will be.

Further, as shown in FIG. 12B, the convex portion 89b has the same shape as the convex portion 99a. That is, the convex portion 89a has an edge portion 89a1 (fifth edge portion) that contacts one inner wall 3b1 (third inner wall) in the width direction of the concave portion 3b when the oldham coupling 1 rotates in the direction of the arrow R1. Further, the convex portion 89a has an edge portion 89a2 (sixth edge portion) that contacts the other inner wall 3b2 (fourth inner wall) in the width direction of the concave portion 3b when the oldham coupling 1 rotates in the direction of the arrow R1. Further, the convex portion 89a has an edge portion 89a3 (seventh edge portion) that contacts the inner wall 3b1 of the concave portion 3b and an edge portion 89a4 (eighth edge portion) that contacts the inner wall 3b2 when the oldham coupling 1 rotates in the direction of the arrow R2. ). The edges 89a1 to 89a4 come into surface contact with the inner wall 3b1 or the inner wall 3b2 of the recess 3b by the surfaces extending in the arrow Z direction and the arrow X direction. The width direction of the recess 3b is the arrow Y direction orthogonal to the arrow Z direction in which the recess 3b extends and the same direction as the direction in which the recess 3a extends.

Here, when the Oldham coupling 1 rotates in the direction of arrow R2, the portion farthest from the rotation center CT2 (second rotation center) of the drive coupling 89 at the edge 89a1 in the arrow Z direction is the rotation center in the arrow Y direction. It is located closer to the inner wall 3b2 than CT2. When the Oldham coupling 1 rotates in the direction of arrow R2, the portion of the edge 89a2 farthest from the center of rotation CT2 in the direction of arrow Z is located closer to the inner wall 3b1 than the center of rotation CT2 in the direction of arrow Y. When the Oldham coupling 1 rotates in the direction of arrow R1, the portion of the edge 99a3 farthest from the center of rotation CT2 in the direction of arrow Z is located closer to the inner wall 3b2 than the center of rotation CT2 in the direction of arrow Y. When the Oldham coupling 1 rotates in the direction of arrow R1, the portion of the edge 89a4 farthest from the center of rotation CT2 in the direction of arrow Z is located closer to the inner wall 3b1 than the center of rotation CT2 in the direction of arrow Y.

Further, the convex portion 89a has a shape in which a substantially rhombus is formed by the virtual line H2 connecting the edge portion 89a1, the edge portion 89a2, the edge portion 89a3, and the edge portion 89a4 when viewed from the rotation axis direction of the Oldham coupling 1. ing. Specifically, when the corner portion is formed by the virtual line in which the edge portion 89a1 and the edge portion 89a4 are extended, the angle of the corner portion is 45 degrees, and the virtual line in which the edge portion 89a2 and the edge portion 89a3 are extended is used. When forming the corners, a rhombus having an angle of 45 degrees is formed. It should be noted that the shape of the substantially rhombus may be a configuration having the above-mentioned corners, or the above-mentioned corners may be chamfered as in the present embodiment.

With such a configuration, when the Oldham coupling 1 rotates in the direction of the arrow R2, there is play between the edge portion 89a1 and the inner wall 3b1 of the recess 3b, and between the edge portion 89a2 and the inner wall 3b2 of the recess 3b, respectively. γ2 is created. Further, when the Oldham coupling 1 rotates in the direction of the arrow R1, a similar play γ2 is created between the edge portion 89a3 and the inner wall 3b1 of the recess 3b, and between the edge portion 89a4 and the inner wall 3b2 of the recess 3b. Be done.

As described above, according to the configuration of the present embodiment, in the Oldham coupling 1, a play γ1 in the rotational direction is provided between the developing drive gear 99 and the intermediate member 3, and between the drive coupling 89 and the intermediate member 3. The driving force can be transmitted while providing the play γ2 in the rotation direction. Further, the edge portions 99a1 to 99a4 are in surface contact with the inner wall 3a1 or the inner wall 3a2 of the recess 3a, and the edge portions 89a1 to 89a4 are in surface contact with the inner wall 3b1 or the inner wall 3b2 of the recess 3b. , 89a can be secured and deformation can be suppressed.

Further, as in the present embodiment, by providing a play in the rotational direction between the development drive gear 99 and the intermediate member 3, and between the drive coupling 89 and the intermediate member 3, the protrusion of the development coupling 75 and the drive cup are provided. It is possible to suppress a decrease in the strength of the coupling itself as compared with the case where the play β (FIG. 9B) provided between the fitting groove of the ring 89 is increased. Further, by increasing the play β, it is possible to prevent stable drive transmission from becoming impossible.

For example, if the length of the fitting groove of the drive coupling 89 in the rotation direction is increased in order to increase the play β, the strength of the drive coupling 89 itself may decrease, and stable drive transmission may not be possible. be. Further, when the length of the fitting groove of the drive coupling 89 in the rotation direction is increased, there is a possibility that three fitting grooves cannot be provided depending on the size of the drive coupling 89. When only two fitting grooves are provided, the number of protrusions of the developing coupling 75 is also two, and the driving force is transmitted by fitting the two protrusions and the two fitting grooves. In this case, stable drive transmission cannot be performed when the fitting force between any of the protrusions and the fitting groove is weak. Further, when the length of the protrusion of the developing coupling 75 in the rotation direction is shortened in order to increase the play β, the strength of the protrusion of the development coupling 75 is lowered by shortening the length in the rotation direction. Therefore, there is a risk of damage during drive transmission.

In this embodiment, instead of increasing the play β between the developing coupling 75 and the driving coupling 89 that are separated when the unit is attached or detached, the developing drive gear 99 and the intermediate member 3 of the Oldham coupling, or / and A play is provided in the drive coupling 89 and the intermediate member 3. As a result, stable drive transmission becomes possible, and the drive force can be selectively transmitted to the drive target depending on whether the motor is rotated in the forward direction or in the reverse direction. Further, although the configuration has play in the rotation direction, it is possible to transmit the driving force even when the rotation axes of the two rotation axes are deviated from each other.

<Operation timing when the motor rotates in the reverse direction>
Next, the operation timing when the photosensitive drum 26, the developing sleeve 71, and the charging roller 27 rotate in the direction opposite to the rotation direction at the time of image formation will be described.

FIG. 13 is a timing chart showing the operation timing when the photosensitive drum 26, the developing sleeve 71, and the charging roller 27 rotate in the direction opposite to the rotation direction at the time of image formation from the state where the driving by the motors 92a and 92b is stopped. be. Here, when the image forming operation is completed, the play α between the drive coupling 96 and the drum coupling 13, the play β between the drive coupling 89 and the development coupling 75, the play γ1 of the Oldham coupling 1, and so on. It is assumed that these members are stopped while γ2 is secured. The play γ1 is a play provided in the rotational direction between the developing drive gear 99 and the intermediate member 3 in the Oldham coupling 1. The play γ2 is a play provided in the rotational direction between the drive coupling 89 and the intermediate member 3 in the Oldham coupling 1.

From this stopped state, the motors 92a and 92b start rotational driving in the direction opposite to the rotational direction at the time of image formation. When the motors 92a and 92b start to rotate, the drum drive gear 95 and the development drive gear 99 start to rotate (timing T1).

Next, when the timing T2 is reached, the play γ1 of the Oldham coupling 1 is clogged by the rotation of the development drive gear 99, and the intermediate member 3 starts rotating. After that, when the timing T3 is reached, the play γ2 of the Oldham coupling 1 is clogged by the rotation of the intermediate member 3, and the drive coupling 89 starts rotating.

Next, when the timing T4 is reached, the play α is clogged by the rotation of the drum drive gear 95, the drum coupling 13 starts to rotate, and the photosensitive drum 26 starts to rotate accordingly. After that, when the timing T5 is reached, the play β is clogged by the rotation of the drive coupling 89, the development coupling 75 starts rotation, and the development sleeve 71 starts rotation accordingly.

Next, when the timing T6 is reached, the gear portion 32a of the separating member 32 meshes with the flange gear 14 as the photosensitive drum 26 rotates, and the charging roller 27 begins to separate from the photosensitive drum 26. Then, when the timing T7 is reached, the charging roller 27 is separated to a predetermined position, and the separation is completed. After that, when the timing T8 is reached, the developing sleeve 71 rotates to a predetermined rotation angle, and the driving of the motors 92a and 92b is stopped.

In this way, by providing the Oldham coupling 1 of the present embodiment, the development sleeve 71 rotates in the opposite direction to the rotation drive in the direction opposite to the rotation direction at the time of image formation of the motors 92a and 92b, and the charging roller. The separation operation with respect to the photosensitive drum 26 of 27 can be executed at different timings. That is, when the motor is rotated in the direction opposite to the rotation direction at the time of image formation, only the development sleeve 71 is moved in the direction opposite to the rotation direction at the time of image formation without separating the charging roller 27 from the photosensitive drum 26. Can be rotated.

As a result, it is possible to suppress defects caused by the simultaneous separation operation of the charging roller 27 and the reverse rotation of the developing sleeve 71. For example, when the image forming apparatus continuously performs the image forming process on the recording material, the reverse rotation operation of the developing sleeve 71 is executed every time the image forming operation of 500 sheets is performed on A4 paper, but continuously. Since the image forming process is performed, the charging roller 27 does not need to be separated from the photosensitive drum 26. Therefore, by providing the Oldham coupling 1 of the present embodiment, it is possible to rotate only the developing sleeve 71 in the direction opposite to the rotation direction at the time of image formation without separating the charging roller 27 from the photosensitive drum 26. Therefore, it is possible to suppress an unnecessary separation operation of the charging roller 27.

Further, by providing the Oldham coupling 1 of the present embodiment, the separating member 32 and the developing sleeve 71 are rotated in the same reverse direction when the motor is rotated in the reverse direction opposite to the rotation direction at the time of image formation. It is possible to suppress defects caused by storage. For example, by starting the separating operation of the charging roller 27 at the same timing as the developing sleeve 71 and ending the rotational operation of the separating member 32 in accordance with the end of the reverse rotation operation of the developing sleeve 71, the separating member 32 is the drum container 11. It is possible to suppress malfunction due to contact with. Further, the developing sleeve 71, the squeeze sheet 77, and the developing sleeve 71 are developed by starting the separating operation of the charging roller 27 at the same timing as the developing sleeve 71 and ending the reverse rotation of the developing sleeve 71 in accordance with the end of the separating operation of the charging roller 27. It is possible to prevent the amount of the toner deposited in the space surrounded by the blade 72 from being pushed back to the stirring chamber 80 side from being insufficient.

(Second Embodiment)
Next, a second embodiment of the Oldham coupling according to the present invention will be described with reference to the drawings. The parts that overlap with those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The configuration of the Oldham coupling 1 according to the present embodiment differs from the configuration of the first embodiment in the shapes of the convex portion 99a of the developing drive gear 99 and the convex portion 89a of the drive coupling 89. Other configurations are the same as those of the first embodiment, including the overall configuration of the image forming apparatus A.

FIG. 14 is a perspective view of the Oldham coupling 1 according to the present embodiment as viewed from the front side of the image forming apparatus A. FIG. 15 is a perspective view of the Oldham coupling 1 according to the present embodiment as viewed from the back side of the image forming apparatus A. FIG. 16A is a diagram showing a fitting portion between the developing drive gear 99 of the Oldham coupling 1 and the intermediate member 3. FIG. 16B is a diagram showing a fitting portion between the drive coupling 89 of the Oldham coupling 1 and the intermediate member 3.

As shown in FIGS. 14 and 15, the convex portion 99a of the developing drive gear 99 according to the present embodiment is composed of a cylindrical portion 99x1 and cylindrical portions 99x2 and 99x3 having a diameter smaller than that of the cylindrical portion 99x1. The cylindrical portion 99x2 and the cylindrical portion 99x3 have the same shape, and the distance between the cylindrical portion 99x1 is also set to be the same.

Further, the convex portion 89a of the drive coupling 89 is composed of a cylindrical portion 89x1 and cylindrical portions 89x2 and 89x3 having a diameter smaller than that of the cylindrical portion 89x1. The cylindrical portion 89x2 and the cylindrical portion 89x3 have the same shape, and the distance between the cylindrical portion 89x1 and the cylindrical portion 89x1 is also set to be the same.

When the developing drive gear 99 is rotated by the driving force of the motor 92a or the motor 92b, the convex portion 99a of the developing drive gear 99 slides relatively inside the concave portion 3a and comes into contact with the inner wall of the concave portion 3a to contact the intermediate member 3. The driving force is transmitted to the intermediate member 3 to rotate. Then, when the intermediate member 3 rotates, the convex portion 89a of the drive coupling 89 slides relatively inside the concave portion 3b, and the inner wall of the concave portion 3a comes into contact with the convex portion 89a to apply a driving force to the drive coupling 89. It transmits and the drive coupling 89 rotates. In this way, even when the rotation axis of the development drive gear 99 (not shown) and the rotation axis 100 of the development coupling 75 are deviated from each other, the driving force of the motor 92a or the motor 92b is developed via the Oldham coupling 1. It is stably transmitted to the rotating shaft 100 of the coupling 75.

Here, as shown in FIG. 16A, the cylindrical portion 99x1 has one inner wall 3a1 (first inner wall) in the width direction of the recess 3a when the Oldham coupling 1 rotates in the arrow R1 direction (first rotation direction). It has an edge portion 99x1a (first edge portion) in contact with the other inner wall 3a2 (second inner wall) and an edge portion 99x1b (second edge portion) in contact with the other inner wall 3a2 (second inner wall). Further, the cylindrical portion 99x2 has an edge portion 99x2a (first edge portion) that contacts the inner wall 3a1 of the recess 3a when the oldham coupling 1 rotates in the direction of the arrow R1. Further, the cylindrical portion 99x3 has an edge portion 99x3a (second edge portion) that contacts the inner wall 3a2 of the recess 3a when the oldham coupling 1 rotates in the direction of the arrow R1. These edges 99x1a, 99x1b, 99x2a, 99x3a make line contact with the inner wall 3a1 or the inner wall 3a2 of the recess 3a by a line extending in the rotation axis direction of the Oldham coupling 1.

Further, the cylindrical portion 99x1 has an edge portion 99x1a (third edge portion) that contacts the inner wall 3a1 of the recess 3a and an edge portion that contacts the inner wall 3a2 when the oldham coupling 1 rotates in the arrow R2 direction (second rotation direction). It has 99x1b (fourth edge). Further, the cylindrical portion 99x3 has an edge portion 99x3b (third edge portion) that contacts the inner wall 3a1 of the recess 3a when the oldham coupling 1 rotates in the direction of the arrow R2. Further, the cylindrical portion 99x2 has an edge portion 99x2b (fourth edge portion) that contacts the inner wall 3a2 of the recess 3a when the oldham coupling 1 rotates in the direction of the arrow R2. These edges 99x1a, 99x1b, 99x2b, 99x3b make line contact with the inner wall 3a1 or the inner wall 3a2 of the recess 3a by a line extending in the rotation axis direction of the Oldham coupling 1.

Here, when the Oldham coupling 1 rotates in the direction of arrow R2, the edge portion 99x2a of the cylindrical portion 99x2 is located closer to the inner wall 3a2 than the rotation center CT1 (first rotation center) of the development drive gear 99 in the arrow Z direction. To position. The edge portion 99x2a of the cylindrical portion 99x2 is the farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that come into contact with the inner wall 3a1 of the recess 3a when the oldham coupling 1 rotates in the arrow R1 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R2, the edge portion 99x3a of the cylindrical portion 99x3 is located closer to the inner wall 3a1 than the rotation center CT1 of the development drive gear 99 in the direction of arrow Z. The edge portion 99x3a of the cylindrical portion 99x3 is the farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that come into contact with the inner wall 3a2 of the recess 3a when the oldham coupling 1 rotates in the arrow R1 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 99x2b of the cylindrical portion 99x2 is located closer to the inner wall 3a1 than the rotation center CT1 of the development drive gear 99 in the direction of arrow Z. The edge portion 99x2b of the cylindrical portion 99x2 is the farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that come into contact with the inner wall 3a2 of the recess 3a when the oldham coupling 1 rotates in the arrow R2 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 99x3b of the cylindrical portion 99x3 is located closer to the inner wall 3a2 than the rotation center CT1 of the development drive gear 99 in the direction of arrow Z. The edge portion 99x3b of the cylindrical portion 99x3 is the farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that come into contact with the inner wall 3a1 of the recess 3a when the oldham coupling 1 rotates in the arrow R2 direction. This is the part.

Further, the convex portion 99a has a shape in which a substantially rhombus is formed by the virtual line H3 connecting the edge portions 99x1a, 99x1b, 99x2a, 99x2b, 99x3a, and 99x3b when viewed from the rotation axis direction of the Oldham coupling 1. .. Specifically, when the virtual line connecting the edge portion 99x1a and the edge portion 99x2a and the virtual line connecting the edge portion 99x1b and the edge portion 99x2b are extended, respectively, and the corner portion is formed by both, the angle of the corner portion is formed. Is 45 degrees, and when the virtual line connecting the edge portion 99x1a and the edge portion 99x3b and the virtual line connecting the edge portion 99x1b and the edge portion 99x3a are extended to form a corner portion, the corner portion is formed. A rhombus with an angle of 45 degrees is formed. The shape of the substantially rhombus may be a structure having corners as described above or a shape in which the corners are chamfered as described above.

With such a configuration, when the Oldham coupling 1 rotates in the direction of the arrow R2, there is play between the edge portion 99x2a and the inner wall 3a1 of the recess 3a, and between the edge portion 99x3a and the inner wall 3a2 of the recess 3a, respectively. γ3 is made. Further, when the Oldham coupling 1 rotates in the direction of the arrow R1, a similar play γ3 is created between the edge portion 99x2b and the inner wall 3a2 of the recess 3a, and between the edge portion 99x3b and the inner wall 3a1 of the recess 3a. Will be.

Further, as shown in FIG. 16B, the cylindrical portion 89x1 has an edge portion 89x1a (3rd inner wall) in contact with one inner wall 3b1 (third inner wall) in the width direction of the recess 3b when the oldham coupling 1 rotates in the arrow R1 direction. It has a fifth edge) and an edge 89x1b (sixth edge) that contacts the other inner wall 3b2 (fourth inner wall). Further, the cylindrical portion 89x2 has an edge portion 89x2a (fifth edge portion) that contacts the inner wall 3b1 of the recess 3b when the oldham coupling 1 rotates in the direction of the arrow R1. Further, the cylindrical portion 89x3 has an edge portion 89x3a (sixth edge portion) that comes into contact with the inner wall 3b2 of the recess 3b when the oldham coupling 1 rotates in the direction of the arrow R1. These edges 89x1a, 89x1b, 89x2a, 89x3a make line contact with the inner wall 3b1 or the inner wall 3b2 of the recess 3b by a line extending in the rotation axis direction of the Oldham coupling 1.

Further, the cylindrical portion 89x1 has an edge portion 89x1a (fifth edge portion) that contacts the inner wall 3b1 of the recess 3b and an edge portion 89x1b (sixth edge portion) that contacts the inner wall 3b2 when the oldham coupling 1 rotates in the direction of the arrow R2. ). Further, the cylindrical portion 89x3 has an edge portion 89x3b (fifth edge portion) that contacts the inner wall 3b1 of the recess 3b when the oldham coupling 1 rotates in the direction of the arrow R2. Further, the cylindrical portion 89x2 has an edge portion 89x2b (sixth edge portion) that contacts the inner wall 3b2 of the recess 3b when the oldham coupling 1 rotates in the direction of the arrow R2. These edges 89x1a, 89x1b, 89x2b, 89x3b make line contact with the inner wall 3b1 or the inner wall 3b2 of the recess 3b by a line extending in the rotation axis direction of the Oldham coupling 1.

Here, when the Oldham coupling 1 rotates in the direction of arrow R2, the edge portion 89x2a of the cylindrical portion 89x2 is located closer to the inner wall 3b2 than the rotation center CT2 (second rotation center) of the drive coupling 89 in the arrow Y direction. To position. The edge portion 89x2a of the cylindrical portion 89x2 is the farthest from the rotation center CT2 of the drive coupling 89 in the arrow Z direction among the edge portions that come into contact with the inner wall 3b1 of the recess 3b when the oldham coupling 1 rotates in the arrow R1 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R2, the edge portion 89x3a of the cylindrical portion 89x3 is located closer to the inner wall 3b1 than the rotation center CT2 of the drive coupling 89 in the direction of arrow Y. The edge portion 89x3a of the cylindrical portion 89x3 is the farthest from the rotation center CT2 of the drive coupling 89 in the arrow Z direction among the edge portions that come into contact with the inner wall 3b2 of the recess 3b when the oldham coupling 1 rotates in the arrow R1 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 89x2b of the cylindrical portion 89x2 is located closer to the inner wall 3b1 than the rotation center CT2 of the drive coupling 89 in the direction of arrow Y. The edge portion 89x2b of the cylindrical portion 89x2 is the farthest from the rotation center CT2 of the drive coupling 89 in the arrow Z direction among the edge portions that come into contact with the inner wall 3b2 of the recess 3b when the oldham coupling 1 rotates in the arrow R2 direction. This is the part.

When the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 89x3b of the cylindrical portion 89x3 is located closer to the inner wall 3b2 than the rotation center CT2 of the drive coupling 89 in the direction of arrow Y. The edge portion 89x3b of the cylindrical portion 89x3 is the farthest from the rotation center CT2 of the drive coupling 89 in the arrow Z direction among the edge portions that come into contact with the inner wall 3b1 of the recess 3b when the oldham coupling 1 rotates in the arrow R2 direction. This is the part.

Further, the convex portion 89a has a shape in which a substantially rhombus is formed by the virtual line H4 connecting the edge portions 89x1a, 89x1b, 89x2a, 89x2b, 89x3a, 89x3b when viewed from the rotation axis direction of the Oldham coupling 1. .. Specifically, when the virtual line connecting the edge portion 89x1a and the edge portion 89x2a and the virtual line connecting the edge portion 89x1b and the edge portion 89x2b are extended, and the corner portion is formed by both, the angle of the corner portion is formed. Is 45 degrees, and when the virtual line connecting the edge portion 89x1a and the edge portion 89x3b and the virtual line connecting the edge portion 89x1b and the edge portion 89x3a are extended to form a corner portion, the corner portion is formed. A rhombus with an angle of 45 degrees is formed. The shape of the substantially rhombus may be a structure having corners as described above or a shape in which the corners are chamfered as described above.

With such a configuration, when the Oldham coupling 1 rotates in the direction of the arrow R2, there is play between the edge portion 89x2a and the inner wall 3b1 of the recess 3b, and between the edge portion 89x3a and the inner wall 3b2 of the recess 3b, respectively. γ4 is made. Further, when the Oldham coupling 1 rotates in the direction of the arrow R1, a similar play γ4 is created between the edge portion 89x2b and the inner wall 3b2 of the recess 3b, and between the edge portion 89x3b and the inner wall 3b1 of the recess 3b. Be done.

As described above, according to the configuration of the present embodiment, in the Oldham coupling 1, a play γ3 in the rotational direction is provided between the developing drive gear 99 and the intermediate member 3, and between the drive coupling 89 and the intermediate member 3. The driving force can be transmitted while providing the play γ4 in the rotation direction. In addition, it is possible to selectively transmit the driving force to the driving target when the motor is rotated in the forward direction and when the motor is rotated in the reverse direction, and even when the rotation axes of the two rotation axes are displaced. The driving force can be transmitted.

In the first embodiment and the second embodiment, the configuration in which the Oldham coupling 1 is provided in the drive train for transmitting the driving force to the developing sleeve 71 in the drive unit 90 has been described, but the present invention is limited to this. It's not a thing. That is, the same effect as described above can be obtained even if the Oldham coupling 1 is provided in another portion for transmitting the driving force, such as in the driving train for transmitting the driving force to the photosensitive drum 26.

Further, in the first embodiment and the second embodiment, in the drive unit 90, both the photosensitive drum 26 and the developing sleeve 71 are configured to be rotatable in a direction opposite to the rotation direction at the time of image formation. Only one of the 26 or the developing sleeve 71 may be rotated in the direction opposite to the rotation direction at the time of image formation. In this case, by providing the above-mentioned Oldham coupling 1, the amount of rotation of either the photosensitive drum 26 or the developing sleeve 71 in the opposite direction can be increased. This makes it possible to selectively transmit the driving force to the drive target when the motor is rotated in the forward direction and when the motor is rotated in the reverse direction, and the rotation axes of the two rotation axes are displaced. However, it is possible to transmit the driving force.

Further, in a device other than the image forming device, the same effect as described above can be obtained even if the Oldham coupling 1 is provided as a means for transmitting the driving force from the driving source to the target unit.

Further, in the first embodiment and the second embodiment, although the configuration in which both the convex portion 99a of the developing drive gear 99 and the convex portion 89a of the drive coupling 89 are substantially rhombic in the Oldham coupling 1, the present invention has been described. Is not limited to this. That is, either one of the convex portion 99a of the developing drive gear 99 and the convex portion 89a of the drive coupling 89 may have a rectangular shape substantially the same as the concave portion 3a or the concave portion 3b of the intermediate member 3. That is, the configuration may be such that only one of the play γ1 between the development drive gear 99 and the intermediate member 3 or the play γ2 between the drive coupling 89 and the intermediate member 3 is provided. Further, the rotation angles of the play γ1 to γ4 are not limited to the angles described in the first embodiment and the second embodiment, and can be set to any angle.

Further, in the first embodiment and the second embodiment, in the Oldham coupling 1, the convex portions 99a and 89a are provided for the developing drive gear 99 and the drive coupling 89, and the concave portions 3a and 3b are provided in the intermediate member 3. Although described, the invention is not limited to this. That is, convex portions corresponding to the convex portions 99a and 89a are provided at one end and the other end of the Oldham coupling 1 in the intermediate member 3 in the rotation axis direction, and the convex portion of the intermediate member 3 is provided on the developing drive gear 99 and the drive coupling 89. The same effect as described above can be obtained even with a configuration in which a concave portion to be fitted to the portion is provided.

1 ... Oldham coupling 3 ... Intermediate member 3a ... Recess (first recess)
3b ... Recess (second recess)
26 ... Photosensitive drum (photoreceptor)
65 ... Process cartridge (image forming unit)
71 ... Development sleeve (developer carrier)
89 ... Drive coupling (2nd hub)
89a ... Convex part (second protruding part)
92a, 92b ... Motor 99 ... Development drive gear (1st hub)
99a ... Convex part (first protruding part)
A ... Image forming device

Claims (12)

In an Oldham coupling having a first hub, a second hub, and an intermediate member that transmits a driving force between the first hub and the second hub.
One of the intermediate member and the first hub is formed on the end surface of the Oldham coupling in the rotation axis direction, is recessed in the rotation axis direction, and is a first recess extending in the first direction orthogonal to the rotation axis direction. The first concave portion is provided on one side of the first inner wall in the second direction orthogonal to the rotation axis direction and the first direction, and on the other side in the second direction, and is provided with the first inner wall. It has a second inner wall that extends in parallel,
One of the intermediate member and the first hub projects in the direction of the rotation axis, fits into the first recess, and transmits a driving force between the intermediate member and the first hub. Has a part,
The first protrusion is
A first edge portion that comes into contact with the first inner wall when the Oldham coupling rotates in the first rotation direction,
A second edge that contacts the second inner wall when the Oldham coupling rotates in the first rotation direction,
When the Oldham coupling rotates in the second rotation direction opposite to the first rotation direction, the third edge portion that comes into contact with the first inner wall and
It has a fourth edge that comes into contact with the second inner wall when the Oldham coupling rotates in a second rotation direction opposite to the first rotation direction.
When the first edge portion is in contact with the first inner wall and the second edge portion is in contact with the second inner wall, the third edge portion is separated from the first inner wall and the fourth. The edge is separated from the second inner wall and
When the third edge portion is in contact with the first inner wall and the fourth edge portion is in contact with the second inner wall, the first edge portion is separated from the first inner wall and the second edge portion is in contact with the second inner wall. The edge is separated from the second inner wall and
When the Oldham coupling rotates with the rotation of the motor in the second rotation direction, it is most from the first rotation center which is the rotation center of the first hub at the first edge portion in the first direction. The distant portion is located closer to the second inner wall than the first rotation center in the second direction, and is farthest from the first rotation center at the second edge in the first direction. The portion is located closer to the first inner wall than the first rotation center in the second direction.
When the Oldham coupling rotates with the rotation of the motor in the first rotation direction, the portion of the third edge portion of the third edge portion farthest from the first rotation center in the first direction is the second direction. The portion of the fourth edge portion located closer to the second inner wall than the first rotation center and farthest from the first rotation center in the first direction is the second direction. An oldham coupling characterized in that it is located closer to the first inner wall than the first rotation center. When viewed from the rotation axis direction, the first protruding portion is formed into a substantially rhombus by a virtual line connecting the first edge portion, the second edge portion, the third edge portion, and the fourth edge portion. The old dam coupling according to claim 1, wherein the shape is a shape. In the first protruding portion, the first edge portion and the third edge portion are in surface contact with the first inner wall by a surface extending in the rotation axis direction and the first direction, and the second edge portion and the third edge portion are in surface contact with each other. The Oldham coupling according to claim 1 or 2, wherein the fourth edge portion is in surface contact with the second inner wall by a surface extending in the rotation axis direction and the first direction. In the first protruding portion, the first edge portion and the third edge portion are in line contact with the first inner wall by a line extending in the direction of the rotation axis, and the second edge portion and the fourth edge portion are in contact with each other. The Oldham coupling according to claim 1 or 2, wherein the second inner wall is in line contact with the second inner wall by a line extending in the direction of the rotation axis. One of the intermediate member and the second hub is formed on the end face in the rotation axis direction, has a second recess that is recessed in the rotation axis direction, and extends in the second direction, and the second recess is. It has a third inner wall on one side in the first direction and a fourth inner wall provided on the other side in the first direction and extending in parallel with the first inner wall.
The other of the intermediate member and the second hub projects in the direction of the rotation axis, fits into the second recess, and transmits a driving force between the intermediate member and the second hub. Has a part,
The second protrusion is
A fifth edge portion that comes into contact with the third inner wall when the Oldham coupling rotates with the rotation of the motor in the first rotation direction.
With the sixth edge portion that comes into contact with the fourth inner wall when the Oldham coupling rotates with the rotation of the motor in the first rotation direction.
A seventh edge portion that comes into contact with the third inner wall when the Oldham coupling rotates with the rotation of the motor in the second rotation direction.
It has an eighth edge portion that comes into contact with the fourth inner wall when the Oldham coupling rotates with the rotation of the motor in the second rotation direction.
When the fifth edge is in contact with the third inner wall and the sixth edge is in contact with the fourth inner wall, the seventh edge is separated from the third inner wall and the eighth. The edge is separated from the fourth inner wall,
When the 7th edge portion is in contact with the 3rd inner wall and the 8th edge portion is in contact with the 4th inner wall, the 5th edge portion is separated from the 3rd inner wall and the 8th edge portion is in contact with the third inner wall. The edge is separated from the fourth inner wall,
When the Oldham coupling rotates with the rotation of the motor in the second rotation direction, it is farthest from the second rotation center which is the rotation center of the second hub at the fifth edge in the second direction. The portion is located closer to the fourth inner wall than the second rotation center in the first direction, and is the farthest part from the second rotation center at the sixth edge portion in the second direction. Is located closer to the third inner wall than the second center of rotation in the first direction.
When the Oldham coupling rotates with the rotation of the motor in the first rotation direction, the portion of the seventh edge portion farthest from the second rotation center in the second direction is the first direction. The portion of the eighth edge portion located closer to the fourth inner wall than the second rotation center and farthest from the second rotation center in the second direction is said in the first direction. The Oldham coupling according to any one of claims 1 to 4, wherein the Aldam coupling is located closer to the third inner wall than the second rotation center. When viewed from the rotation axis direction, the second protruding portion is formed into a substantially rhombus by a virtual line connecting the fifth edge portion, the sixth edge portion, the seventh edge portion, and the eighth edge portion. The old dam coupling according to claim 5, which is characterized by having a shape. In the second protruding portion, the fifth edge portion and the seventh edge portion are in surface contact with the third inner wall by a surface extending in the rotation axis direction and the second direction, and the sixth edge portion and the seventh edge portion are in surface contact with each other. The Oldham coupling according to claim 5 or 6, wherein the eighth edge portion is in surface contact with the fourth inner wall by a surface extending in the rotation axis direction and the second direction. In the second protruding portion, the fifth edge portion and the seventh edge portion are in line contact with the third inner wall by a line extending in the direction of the rotation axis, and the sixth edge portion and the eighth edge portion are in contact with each other. The Oldham coupling according to claim 5 or 6, wherein the fourth inner wall is in line contact with the fourth inner wall by a line extending in the direction of the rotation axis. With the motor
The Oldham coupling according to any one of claims 1 to 8.
An image forming unit that is driven by the driving force of the motor transmitted via the Oldham coupling to form an image on the seat, and an image forming unit.
An image forming apparatus comprising. The image forming unit includes a photoconductor and a developer carrier that carries a developer and adheres the developer to the surface of the photoconductor.
The image forming apparatus according to claim 9, wherein the developer carrier is rotated by a driving force of the motor transmitted via the Oldham coupling. The image forming apparatus according to claim 10, wherein the photoconductor is rotated by a driving force of the motor. The image forming apparatus according to any one of claims 9 to 11, wherein the image forming unit is configured to be detachably attached to the image forming apparatus.

Images