Euro couplings and imaging equipment

Abstract

The present invention relates to an European coupling and an imaging device. The European coupling has a play in a rotational direction and is capable of transmitting a driving force, and includes: a developing drive gear as a first hub; a driving coupling as a second hub; and an intermediate member that transmits a driving force between the developing drive gear and the driving coupling. The developing drive gear includes a protruding portion that is fitted into a recessed portion of the intermediate member to transmit a driving force between the developing drive gear and the intermediate member. When viewed in the direction of the rotation axis of the European coupling, the shape of the protruding portion is a roughly rhombus shape.

Description

Technical Field

[0001] The present invention relates to an Oldham coupling for transmitting drive from a drive source to a unit as a drive target. Background Art

[0002] In the related art, a configuration has been used in which drive is transmitted from a motor to each unit as a drive target through a drive train using gears, etc. For example, Japanese Patent Application Laid-Open No. 8-234643 describes a configuration in which one motor is used to rotate both a photosensitive drum and a developing sleeve in a developing unit.

[0003] In addition, Japanese Patent Application Publication No. 8-234643 describes a configuration in which a photosensitive drum and a developing sleeve as a plurality of drive targets are selectively rotated. In the configuration of Japanese Patent Application Publication No. 8-234643, in a power transmission mechanism for transmitting a driving force from a driving source to a developing sleeve and a photosensitive drum as drive targets, a coupling having a clearance of a predetermined rotation angle is provided in a driving system. With this configuration, the driving force can be selectively transmitted to the drive target depending on whether the motor rotates forward or reversely.

[0004] On the other hand, in a power transmission mechanism that transmits driving force from a driving source to a unit as a driving target, a configuration in which the unit as a driving target is detachably attached to a device including the driving source may be considered. In this case, the rotation axis of the driving source and the rotation axis of the unit side to be detachably attached may not be aligned with each other.

[0005] In this way, in a configuration in which the rotation axes of the two rotating shafts may not be aligned with each other, a configuration can be used in which an Oldham coupling is provided so that the driving force can be transmitted even in a state in which the rotation axes of the two rotating shafts are not aligned with each other.

[0006] Generally, the European coupling includes a first hub, a second hub, and an intermediate member for transmitting a driving force between the first hub and the second hub. Here, as a configuration of the European coupling, when a configuration having a coupling shape of Japanese Patent Application Publication No. 8-234643 is applied to selectively transmit a driving force to a driving target according to whether the motor rotates forward or reversely, the driving force cannot be transmitted, which is a problem.

[0007] That is, in the two couplings described in Japanese Patent Application Publication No. 8-234643, it is considered that the shape of one of them represents the first hub, and the shape of the other represents the intermediate member. In this case, since the intermediate member cannot move in the radial direction relative to the first hub, when the rotation axis of the first rotating shaft on the drive source side and the rotation axis of the second rotating shaft on the unit side as the drive target are not aligned with each other, the driving force cannot be transmitted, which is a problem. That is, when a configuration having a clearance in the rotation direction as in Japanese Patent Application Publication No. 8-234643 is applied, in a state where the rotation axes of the two rotating shafts are not aligned with each other, the driving force cannot be transmitted, and the European coupling does not work.

[0008] Therefore, in view of such circumstances, it is desirable to provide an Oldham coupling capable of transmitting a driving force even in a configuration having play in the rotational direction. Summary of the invention

[0009] A representative configuration of an Oldham coupling according to the present invention configured to achieve the above-mentioned purpose includes: a first hub; a second hub; an intermediate member, the intermediate member transmitting a driving force between the first hub and the second hub. One of the intermediate member and the first hub includes a first recessed portion, the first recessed portion is formed in an end face in the rotation axis direction of the Oldham coupling, is recessed in the rotation axis direction, and extends in a first direction orthogonal to the rotation axis direction, and the first recessed portion includes a first inner wall and a second inner wall, the first inner wall is on one side in a second direction orthogonal to the first direction and in the rotation axis direction, and the second inner wall is provided on the other side in the second direction and extends parallel to the first inner wall. The other of the intermediate member and the first hub is provided with a protruding portion, which protrudes in the direction of the rotation axis, fits into the first recessed portion, and transmits a driving force between the intermediate member and the first hub, and the protruding portion includes: a first edge portion, which contacts the first inner wall in a state where the Oldham coupling rotates in a first rotation direction; a second edge portion, which contacts the second inner wall in a state where the Oldham coupling rotates in the first rotation direction; a third edge portion, which contacts the first inner wall in a state where the Oldham coupling rotates in a second rotation direction opposite to the first rotation direction; and a fourth edge portion, which contacts the second inner wall in a state where the Oldham coupling rotates in the second rotation direction opposite to the first rotation direction. In a state where the first edge portion contacts the first inner wall and the second edge portion contacts the second inner wall, the third edge portion is separated from the first inner wall and the fourth edge portion is separated from the second inner wall. In a state where 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 separated from the second inner wall. In a state where the Oldham coupling rotates in the second rotation direction as the motor rotates, a portion of the first edge portion farthest from a first rotation center, which is a rotation center of the first hub, in the first direction will be positioned closer to the second inner wall than the first rotation center in the second direction, and a portion of the second edge portion farthest from the first rotation center in the first direction will be positioned closer to the first inner wall than the first rotation center in the second direction.When the European coupling rotates in the first rotation direction as the motor rotates, the portion of the third edge portion farthest from the first rotation center in the first direction will be positioned closer to the second inner wall in the second direction than the first rotation center, and the portion of the fourth edge portion farthest from the first rotation center in the first direction will be positioned closer to the first inner wall in the second direction than the first rotation center.

[0010] Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic cross-sectional view of an imaging device;

[0012] Figure 2 is a perspective view of a process cartridge;

[0013] Figure 3 is a cross-sectional view of the process cartridge;

[0014] Figure 4 is a perspective view of the drum unit;

[0015] FIG. 5A to FIG. 5D is a cross-sectional view of the drum unit;

[0016] Figure 6 is a perspective view of a developing unit;

[0017] Fig. 7A and Figure 7B are the front and rear views of the drive unit;

[0018] Figure 8 is a view showing gears of a drive unit;

[0019] Fig.9A and Fig. 9B is a view showing the configuration of a drive coupling, a drum coupling, and a developing coupling;

[0020] Fig.10 This is an exploded perspective view of a European coupling;

[0021] Fig.11 This is an exploded perspective view of a European coupling;

[0022] Fig. 12A and Fig. 12B is a view showing an assembly portion between a developing drive gear, an intermediate member, and a drive coupling of a European coupling;

[0023] Fig.13 is a timing chart showing the operation timing of each component after the imaging operation ends;

[0024] Fig.14 This is an exploded perspective view of a European coupling;

[0025] Fig.15 is an exploded perspective view of a European coupling; and

[0026] Fig.16A and Fig. 16B It is a view showing an assembly portion between a developing drive gear, an intermediate member, and a driving coupling of an Oldham coupling. DETAILED DESCRIPTION

[0027] (First embodiment)

[0028] <Imaging equipment>

[0029] Hereinafter, the overall configuration of the imaging device including the Oldham coupling according to the present invention will first be described with reference to the accompanying drawings and the operation during imaging. Unless otherwise specified, the scope of the present invention is not intended to be limited to the size, material, shape and relative arrangement of the components to be described below.

[0030] The image forming apparatus A according to the present embodiment is an intermediate tandem type image forming apparatus which transfers four color toners of yellow Y, magenta M, cyan C, and black K as developers onto an intermediate transfer belt, and then transfers the image onto a sheet to form an image. In the following description, Y, M, C, and K are added as suffixes to components using the above color toners, but the configuration and operation of the components are substantially the same except that the colors of the toners are different from each other, so that the suffixes will be appropriately omitted unless there is a need to distinguish.

[0031] Figure 1 is a schematic cross-sectional view of the imaging device A. Figure 1 As shown, the image forming apparatus A includes an image forming portion 61 that forms an image on a sheet S. The image forming portion 61 includes a process cartridge 65 (65Y, 65M, 65C, and 65K), a laser scanner unit 28, primary transfer rollers 31 (31Y, 31M, 31C, and 31K), an intermediate transfer belt 30, a secondary transfer roller 51, and a secondary transfer counter roller 52.

[0032] Each process cartridge 65 (image forming unit) is configured to be detachably attached to the image forming apparatus A. The process cartridge 65 includes a photosensitive drum 26 (26Y, 26M, 26C, and 26K) as a photosensitive member and a charging roller 27 (27Y, 27M, 27C, and 27K). In addition, the process cartridge 65 includes a developing unit 29 (29Y, 29M, 29C, or 29K) including a developing sleeve 71 (71Y, 71M, 71C, and 71K) as a developer carrier and a cleaning blade 45 (45Y, 45M, 45C, and 45K).

[0033] Next, the image forming operation will be described. First, when the controller (not shown) receives an image forming job signal, the sheets S stacked and stored in the sheet cassette 22 are conveyed to the registration roller 24 by the feed roller 66. Thereafter, the registration roller 24 conveys the sheets S to the secondary transfer portion formed by the secondary transfer roller 51 and the secondary transfer counter roller 52 at a predetermined timing.

[0034] On the other hand, in the image forming section 61, first, the surface of the photosensitive drum 26Y is charged by the charging roller 27Y. Thereafter, the laser scanner unit 28 irradiates the surface of the photosensitive drum 26Y with laser light according to image data input from an external device (not shown). Thus, an electrostatic latent image according to the image data is formed on the surface of the photosensitive drum 26Y.

[0035] Next, the developing sleeve 71Y included in the developing unit 29Y causes the yellow toner to adhere to the electrostatic latent image formed on the surface of the photosensitive drum 26Y, so that a yellow toner image is formed on the surface of the photosensitive drum 26Y. When a bias is applied to the primary transfer roller 31Y, the toner image formed on the surface of the photosensitive drum 26Y is primarily transferred to the intermediate transfer belt 30. Thereafter, the toner remaining on the surface of the photosensitive drum 26Y is scraped off by the cleaning blade 45Y. The cleaning blade 45Y abuts against the surface of the photosensitive drum 26Y so as to be opposite to the rotation direction of the photosensitive drum 26Y at the time of image formation.

[0036] Magenta, cyan and black toner images are also formed on the photosensitive drums 26M, 26C and 26K by a similar process. Then, when a bias is applied to the primary transfer rollers 31M, 31C and 31K, these toner images are transferred in a superimposed manner onto the yellow toner image on the intermediate transfer belt 30. Thus, a full-color toner image is formed on the surface of the intermediate transfer belt 30. Thereafter, the toner remaining on the surfaces of the photosensitive drums 26M, 26C and 26K is scraped off by the cleaning blades 45M, 45C and 45K.

[0037] The intermediate transfer belt 30 moves on the track according to the rotation of the secondary transfer roller pair 52. When the intermediate transfer belt 30 carrying the full-color toner image moves, the toner image will be sent to the secondary transfer portion. Subsequently, in the secondary transfer portion, when a bias is applied to the secondary transfer roller 51, the toner image on the intermediate transfer belt 30 will be transferred to the sheet S.

[0038] Next, the sheet S on which the toner image is transferred is conveyed to the fixing portion 36, and is subjected to heating and pressurizing in the fixing portion 36. Thus, the toner image on the sheet S is fixed to the sheet S. Thereafter, the sheet S on which the toner image is fixed is discharged to the discharge portion 40 by the discharge rollers 38.

[0039] <Processing cartridge>

[0040] Next, the configuration of the process cartridge 65 will be described.

[0041] Figure 2 is a perspective view of the process cartridge 65. Figure 3 65 is a cross-sectional view of the processing box 65. Figure 2 and Figure 3 As shown, the process cartridge 65 includes the drum unit 42 and the developing unit 29 .

[0042] First, the configuration of the drum unit 42 will be described. Figure 4 is a perspective view of the drum unit 42 . FIG. 5A to FIG. 5D is a cross-sectional view of the periphery of the photosensitive drum 26 in the drum unit 42, and shows that the charging roller 27 will FIG. 5A to FIG. 5D The order of separation from the photosensitive drum 26. Figure 4 and FIG. 5A to FIG. 5D As shown, the drum unit 42 includes the photosensitive drum 26 , the charging roller 27 , and the cleaning blade 45 , and these components are integrally held by the drum container 11 .

[0043] The drum container 11 rotatably holds the photosensitive drum 26. A drum coupling 13 that receives a driving force from a driving unit 90, which will be described later, is provided integrally with the photosensitive drum 26 in the drum container 11 at one end side in the rotation axis direction of the photosensitive drum 26. The drum coupling 13 is provided in the drum container 11 at the rear side of the image forming apparatus A. In addition, a flange gear 14 is provided integrally with the photosensitive drum 26 at both end portions in the rotation axis direction of the photosensitive drum 26.

[0044] In addition, the drum container 11 is provided with a recovery section 16 ( Figure 3 ), the recovery section recovers the toner removed from the surface of the photosensitive drum 26 by the cleaning blade 45. A conveying screw 17 that conveys the toner present in the recovery section 16 to the outside of the drum unit 42 is provided inside the recovery section 16. The driving force will be transmitted from the flange gear 14 to the conveying screw 17 via the idle gear 67, so that the conveying screw 17 rotates and conveys the toner. The toner conveyed to the outside of the drum unit 42 by the conveying screw 17 will be recovered in a container (not shown) provided in the image forming apparatus A.

[0045] In addition, the drum container 11 is provided with a bearing 19 that rotatably holds the charging roller 27. The bearing 19 is held by the drum container 11 so as to be movable in a sliding manner in a direction toward or away from the photosensitive drum 26, and is biased toward the photosensitive drum 26 by the spring 12. The charging roller 27 is pressed against the photosensitive drum 26 by the biasing force of the spring 12, and rotates according to the rotation of the photosensitive drum 26.

[0046] The one-way clutch 21 is provided at both ends of the charging roller 27. When a torque is applied to the one-way clutch 21 in a direction opposite to the rotation direction of the charging roller 27 during image formation, the one-way clutch 21 is locked and rotates integrally with the charging roller 27. In addition, when a predetermined torque or higher torque (idling torque) is applied to the one-way clutch 21 in the same direction as the rotation direction of the charging roller 27 during image formation, the one-way clutch 21 is unlocked and idling without transmitting a driving force between the one-way clutch 21 and the charging roller 27. In the present embodiment, the one-way clutch 21 is configured to use a latch protrusion and a rack.

[0047] In addition, the outer peripheral portion of the one-way clutch 21 is provided with a separation member 32 including a gear portion 32a meshed with the flange gears 14 provided in both end portions of the photosensitive drum 26. The separation 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 according to the rotation of the photosensitive drum 26, the one-way clutch 21 and the separation member 32 rotate with the rotation of the charging roller 27. In order to prevent the charging roller 27 from being pressed against the photosensitive drum 26 for a long time and thus deforming the charging roller 27 to adversely affect the image quality, the separation member 32 separates the charging roller 27 from the photosensitive drum 26 by the following operation.

[0048] That is, Figure 5A As shown, when the imaging device A performs the imaging operation, the gear portion 32a of the separation member 32 and the flange gear 14 are separated from each other and do not mesh with each other. When a predetermined time (eight hours in the present embodiment) has passed after the imaging device A has finished the imaging operation, the photosensitive drum 26 will rotate in the direction opposite to the rotation direction during the imaging. Therefore, the charging roller 27 also rotates in the direction opposite to the rotation direction during the imaging according to the rotation of the photosensitive drum 26, and the one-way clutch 21 or the separation member 32 also rotates. Figure 5B As shown in FIG. 1 , when the separating member 32 rotates, the gear portion 32a of the separating member 32 meshes with the flange gear 14. In this embodiment, when the charging roller 27 rotates 54 degrees, the one-way clutch 21 will be locked. Therefore, 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 of its diameter to the diameter of the photosensitive drum 26 until the gear portion 32a of the separating member 32 meshes with the flange gear 14. In this embodiment, since the diameter of the photosensitive drum 26 is 30 mm and the diameter of the charging roller 27 is 14 mm, so the rotation amount of the photosensitive drum 26 is 25.2 degrees.

[0049] Next, if Figure 5CAs shown, the photosensitive drum 26 or the charging roller 27 continues to rotate in the direction opposite to the rotation direction during image formation, and the one-way clutch 21 or the separating member 32 also rotates further. When the separating member 32 rotates further, because of the shape of the separating member 32, a force will be applied to the charging roller 27 in the direction away from the photosensitive drum 26, and the charging roller 27 will be separated from the photosensitive drum 26 by the biasing force of the spring 12. In the present embodiment, when the charging roller 27 rotates further by 45 degrees after the gear portion 32a of the separating member 32 has been meshed with the flange gear 14, the charging roller 27 will be separated from the photosensitive drum 26. After the gear portion 32a of the separating member 32 and the flange gear 14 have been meshed with each other, 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, since the separation amount between the photosensitive drum 26 and the charging roller 27 is 1 mm, the rotation amount of the photosensitive drum 26 is 24 degrees. At the time of the next image formation, the photosensitive drum 26 rotates in the rotation direction at the time of image formation, so that the charging roller 27 separated from the photosensitive drum 26 performs the operation opposite to the above-described separation operation and contacts the photosensitive drum 26 again.

[0050] In addition, if Figure 5D As shown, after the charging roller 27 is separated from the photosensitive drum 26, when the photosensitive drum 26 continues to rotate in the direction opposite to the rotation direction at the time of image formation, the separation member 32 contacts the drum container 11 to cause a malfunction, which is a problem. In the present embodiment, when the charging roller 27 further rotates 45 degrees (24 degrees is the rotation amount of the photosensitive drum 26) after the charging roller 27 and the photosensitive drum 26 are separated from each other, the separation member 32 and the drum container 11 contact each other. Therefore, in the present embodiment, in order to suppress the contact between the separation member 32 and the drum container 11 while separating the charging roller 27 from the photosensitive drum 26, the rotation amount of the photosensitive drum 26 in the direction opposite to the rotation direction at the time of image formation is set to 49.2 degrees to 73.2 degrees.

[0051] Next, the configuration of the developing unit 29 will be described. Figure 6 2 is a perspective view of the developing unit 29. Figure 6 In order to describe the internal configuration of the developing unit 29, the developing container 70 is partially cut away and shown. Figure 6 As shown, the developing unit 29 includes a developing sleeve 71 , a developing blade 72 , and conveying screws 73 and 74 , and these components are integrally held by a developing container 70 .

[0052] The developing container 70 has an opening in a portion facing the photosensitive drum 26, and the developing sleeve 71 is arranged to be partially exposed in the opening. The developing sleeve 71 is arranged to face the photosensitive drum 26 at a predetermined interval (240 μm in the present embodiment) from the photosensitive drum. A developing coupling 75 that receives a driving force from a driving unit 90, which will be described later, is arranged on one end side in the rotation axis direction of the developing sleeve 71. The driving force will be transmitted from the driving unit 90 to the developing sleeve 71 via the developing coupling 75 to rotate the developing sleeve 71.

[0053] The developing coupling 75 is held by the developing container 70 at a position in the developing container 70 located at one end side in the rotation axis direction of the developing sleeve 71 and at the rear side of the image forming apparatus A. A D-shaped notch-shaped engaging portion (not shown) engaged with the developing coupling 75 is formed in the rotating shaft of the developing sleeve 71, and the engaging portion causes the developing sleeve 71 to rotate integrally with the developing coupling 75. In addition, 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.

[0054] In addition, the developing sleeve 71 includes a magnetic roller 76 ( Figure 3 ), the magnetic roller has a plurality of magnetic poles in a non-rotating state. Figure 3 As shown, the magnetic roller 76 has a developing pole S1 in a developing area positioned to face the photosensitive drum 26. In addition, in the rotation direction of the developing sleeve 71 during image formation, the magnetic roller 76 has a conveying pole N1, a scraping pole N2, a drawing pole S2, and a cutting pole N3 in order on the downstream side of the developing pole S1. With respect to the center position of each magnetic pole, when the developing pole S1 is at 0 degrees, along the rotation direction of the developing sleeve 71 during image formation ( Figure 3 In the counterclockwise direction in FIG), the conveying pole N1 is at 60 degrees, the scraping pole N2 is at 180 degrees, the drawing pole S2 is at 230 degrees, and the cutting pole N3 is at 290 degrees. During image formation, the magnetic roller 76 carries the toner by the magnetic force of each magnetic pole and conveys the toner to the developing area.

[0055] That is, first, the toner contained in the developing container 70 will be sucked up by the sucking pole S2, and the magnetic roller 76 will carry the toner onto the developing sleeve 71. Next, the toner carried on the developing sleeve 71 will be raked into a brush shape by the cutting pole N3. Thereafter, the toner in the spike shape will be transported to the developing area by the rotation of the developing sleeve 71, and moved to the photosensitive drum 26 by the developing pole S1. Thereafter, when the toner approaches the center position between the conveying pole N1 and the scraping pole N2, the toner remaining on the developing sleeve 71 is gradually increased by the repulsive magnetic field formed by the conveying pole N1 and the scraping pole N2, and is finally scraped off the developing sleeve 71.

[0056] In addition, the developing scraper 72 is arranged near the developing sleeve 71, and is spaced a predetermined distance from the developing sleeve 71. The developing scraper 72 is adjacent to the toner carried on the developing sleeve 71 to form a toner layer having a predetermined thickness. Specifically, when the developing sleeve 71 rotates, the toner carried on the developing sleeve 71 and raked up by the cutting pole N3 passes between the tip portion of the developing scraper 72 and the surface of the developing sleeve 71, so that the amount of the toner is controlled and a toner layer is formed. In addition, a pressing sheet 77 that suppresses the toner from scattering outside the developing container 70 is fixed to the side of the developing scraper 72 opposite to the side on which the developing sleeve 71 is arranged.

[0057] In addition, the interior of the developing container 70 is partitioned 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. Both end portions of the partition wall 78 in the longitudinal direction are provided with communicating portions (not shown) through which the developing chamber 79 and the stirring chamber 80 communicate with each other.

[0058] The conveying screws 73 and 74 that rotate and convey the toner by the spiral scraper are respectively provided in the developing chamber 79 and the stirring chamber 80. The conveying screws 73 and 74 convey the toner in the longitudinal direction of the partition wall 78 and in the directions opposite to each other. The driving force is transmitted from the sleeve gear 81 provided integrally with the developing sleeve 71 to the conveying screws 73 and 74 to rotate the conveying screws 73 and 74. When the conveying screws 73 and 74 rotate, the toner circulates between the developing chamber 79 and the stirring chamber 80 via the communicating portion (not shown).

[0059] In addition, whenever an image forming operation is performed, toner will be deposited in the space surrounded by the developing sleeve 71, the developing blade 72, and the pressing sheet 77 in the developing container 70. When the amount of deposited toner is excessive, the deposited toner penetrates into the developing area, thereby causing an image defect called a smear image, which is a problem. In order to suppress the occurrence of image defects, at the time of non-image forming after a predetermined number of image forming operations have been performed, the developing sleeve 71 is rotated in a direction opposite to the rotation direction at the time of image forming to move the toner deposited in the space surrounded by the developing sleeve 71, the pressing sheet 77, and the developing blade 72 to the stirring chamber 80 side. Specifically, as the developing sleeve 71 rotates, the toner raised by the repulsive magnetic field formed by the conveying pole N1 and the scraping pole N2 passes through the space surrounded by the developing sleeve 71, the pressing sheet 77, and the developing blade 72 to push the toner deposited in the space to the stirring chamber 80 side. In the present embodiment, every time the image forming operation is performed on 500 sheets of A4 paper, the rotating operation of the developing sleeve 71 in the reverse direction is performed.

[0060] Here, when the rotation amount of the developing sleeve 71 in the direction opposite to the rotation direction during image formation is large, the toner drawn by the drawing pole S2 will not pass through the developing scraper 72, and a large amount of toner will be transferred to the developing area. Therefore, the toner is scattered to the outside of the developing container 70, which is a problem. Therefore, in order to suppress the toner from being scattered to the outside, the rotation amount of the developing sleeve 71 in the direction opposite to the rotation direction during image formation is set to an angle from the conveying pole N1 to the scraping pole N2. That is, in the present embodiment, the rotation amount is set to an angle of 60 degrees to 180 degrees around the rotation axis of the developing sleeve 71.

[0061] <Driver unit>

[0062] Next, the configuration of the driving unit 90 that drives the process cartridge 65 will be described.

[0063] Fig. 7A is a front view of the drive unit 90 . Figure 7B is a rear view of the drive unit 90 . Figure 8 2 is a view showing gears included in the driving unit 90. Fig. 7A , Figure 7B and Figure 8 As shown, the driving unit 90 includes a driving frame 91 having a box shape and formed of a rear frame 91 a and a front frame 91 b.

[0064] A motor 92a as a driving source for the photosensitive drums 26Y, 26M and 26C and the developing sleeves 71Y, 71M and 71C and a motor 92b as a driving source for the photosensitive drum 26K and the developing sleeve 71K are fixed to the driving frame 91. In the present embodiment, the motors 92a and 92b are brushless DC motors.

[0065] The 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. In addition, the drum reduction gear 94a2 meshes with the drum drive gear 95M and the drum drive gear 95Y. The rotation speed of the drum drive gears 95Y, 95M and 95C is reduced with respect to the rotation speed of the motor 92a by the gear ratio of the gear train.

[0066] The 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. The rotation speed of the drum drive gear 95K is reduced relative to the rotation speed of the motor 92b by the gear ratio of the gear train.

[0067] In addition, drive couplings 96Y, 96M, 96C, and 96K engaged with the drum couplings 13 provided in the process cartridges 65Y, 65M, 65C, and 65K are provided coaxially with the drum drive gears 95Y, 95M, 95C, and 95K, respectively. Fig.9A As shown, 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.

[0068] With this 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 and 94a2, the drum drive gears 95Y, 95M and 95C, and the drive couplings 96Y, 96M and 96C. Therefore, the photosensitive drums 26Y, 26M and 26C rotate. In addition, 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. Therefore, the photosensitive drum 26K rotates.

[0069] In addition, the developing reduction gear 97a is meshed with the pinion gear 93a. In addition, a plurality of idle gears 98a to 98g are provided to form a gear train between the idle gears 98a to 98g and the developing reduction gear 97a. The idle gears 98a, 98d and 98g are meshed with the developing drive gears 99Y, 99M and 99C, respectively. The rotation speed of the developing sleeves 71Y, 71M and 71C is reduced with respect to the number of revolutions of the motor 92a at the gear ratio of the gear train so as to be 198% of the rotation speed of the photosensitive drums 26Y, 26M and 26C.

[0070] In addition, the pinion gear 93b meshes with the developing drive gear 99K via a gear train formed by the drum reduction gear 94b, the idle gear 98h, the developing reduction gear 97b and the idle gear 98i. The rotation speed of the developing sleeve 71K is reduced relative to the rotation speed of the motor 92b by the gear ratio of the gear train so as to be 198% of the rotation speed of the photosensitive drum 26K.

[0071] In addition, the rotation shafts (not shown) of the developing drive gears 99Y, 99M, 99C and 99K are connected to the rotating shafts provided on the developing drive gears 99Y, 99M, 99C and 99K through the later-described European coupling 1. Fig. 7A The rotating shafts 100Y, 100M, 100C and 100K of the developing couplings 75 in the process cartridges 65Y, 65M, 65C and 65K shown. In addition, the developing couplings 75 are engaged with the driving couplings 89Y, 89M, 89C and 89K forming a part of the European coupling 1. Here, as shown in FIG. Fig. 9BAs shown, the developing coupling 75 includes three protruding parts, and the driving coupling 89 is provided with three fitting grooves, into which the three protruding parts of the developing coupling 75 are fitted. In this way, since three or more protruding parts of one coupling are provided and three or more fitting grooves of another coupling are provided, the drive can be stably transmitted. A clearance β in the rotation direction is provided between the fitting groove of the driving coupling 89 of each color and the protruding part of the developing coupling 75. In the present embodiment, the clearance β is set to 30 degrees at an angle around the rotation axis of the developing sleeve 71.

[0072] With this configuration, the driving force of the motor 92a is transmitted to the developing coupling 75 via the pinion gear 93a, the developing reduction gear 97a, the idle gears 98a to 98g, the developing drive gears 99Y, 99M and 99C, and the driving couplings 89Y, 89M and 89C. As a result, the developing sleeves 71Y, 71M and 71C rotate. In addition, 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 idle gears 98h and 98i, the developing drive gear 99K and the driving coupling 89K. As a result, the developing sleeve 71K rotates.

[0073] As described above, in this 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. In addition, in this embodiment, the diameter of the photosensitive drum 26 is 30 mm, and the diameter of the developing sleeve 71 is 18 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 rotates one turn, the developing sleeve 71 rotates 3.3 turns.

[0074] <European coupling>

[0075] Next, the configuration of the Oldham coupling 1 will be described.

[0076] Fig.10 1 is an exploded perspective view of the Oldham coupling 1 as seen from the front side of the image forming apparatus A. Fig.11 is an exploded perspective view of the Oldham coupling 1 as seen from the rear side of the image forming apparatus A. Fig. 12A 1 is a view showing an assembly portion between the developing drive gear 99 of the Oldham coupling 1 and the intermediate member 3 . Fig. 12B 1 is a view showing an assembled portion between the drive coupling 89 of the Oldham coupling 1 and the intermediate member 3 .

[0077] like Fig.10 and Fig.11As shown, the Oldham coupling 1 includes a developing drive gear 99 (first hub), a driving coupling 89 (second hub), and an intermediate member 3 that transmits driving force between the developing drive gear 99 and the driving coupling 89. The Oldham coupling 1 is rotatably held in a coupling holder 2 provided in the front frame 91b.

[0078] A recessed portion 3a (first recessed portion) having a rectangular cross section is formed in an end surface of one side of the intermediate member 3 in the arrow X direction (which is the rotation axis direction of the European coupling 1), the recessed portion is recessed in the arrow X direction and extends in the arrow Y direction (first direction) orthogonal to the arrow X direction. In addition, a recessed portion 3b (second recessed portion) having a rectangular cross section is formed in an end surface of the other side of the intermediate member 3 in the arrow X direction, the recessed portion is recessed in the arrow X direction and extends in the arrow Z direction (second direction) orthogonal to the arrow X direction and the arrow Y direction. The recessed portions 3a and 3b have the same shape except that the recessed portions 3a and 3b extend in directions orthogonal to each other. The rotation axis direction of the European coupling 1 is the same as each of the rotation axis direction of the development drive gear 99, the rotation axis direction of the drive coupling 89, and the rotation axis direction of the intermediate member 3.

[0079] In addition, a protruding portion 99a (first protruding portion) is formed in one end portion of the development drive gear 99 in the rotation axis direction (arrow X direction) of the Oldham coupling 1, and the protruding portion protrudes in the arrow X direction and fits into the recessed portion 3a of the intermediate member 3. In addition, a protruding portion 89a (second protruding portion) is formed in one end portion of the drive coupling 89 in the rotation axis direction of the Oldham coupling 1, and the protruding portion protrudes in the arrow X direction and fits into the recessed portion 3b of the intermediate member 3.

[0080] When the development drive gear 99 is rotated by the driving force of the motor 92a or the motor 92b, the protruding portion 99a of the development drive gear 99 contacts the inner wall of the recessed portion 3a while sliding relative to the inside of the recessed portion 3a, and transmits the driving force to the intermediate member 3, causing the intermediate member 3 to rotate. Then, when the intermediate member 3 rotates, the inner wall of the recessed portion 3b contacts the protruding portion 89a of the drive coupling 89 while the protruding portion 89a moves relative to the inside of the recessed portion 3b in a sliding manner, and transmits the driving force to the drive coupling 89, causing the drive coupling 89 to rotate. In this way, even when the rotation axis of the rotation shaft (not shown) of the development drive gear 99 and the rotation axis of the rotation shaft 100 of the development coupling 75 are not aligned with each other, the driving force of the motor 92a or the motor 92b will be stably transmitted to the rotation shaft 100 of the development coupling 75 via the Oldham coupling 1.

[0081] Here, if Fig. 12A As shown, the protruding portion 99a includes an edge portion 99a1 (first edge portion), and when the European coupling 1 rotates in the arrow R1 direction (first rotation direction), the first edge portion contacts one inner wall 3a1 (first inner wall) of the recessed portion 3a in the width direction. In addition, the protruding portion 99a includes an edge portion 99a2 (second edge portion), and when the European coupling 1 rotates in the arrow R1 direction, the second edge portion contacts the other inner wall 3a2 (second inner wall) of the recessed portion 3a in the width direction. In addition, the protruding portion 99a includes an edge portion 99a3 (third edge portion) and an edge portion 99a4 (fourth edge portion), and when the European coupling 1 rotates in the arrow R2 direction (second rotation direction), the third edge portion contacts the inner wall 3a1 of the recessed portion 3a, and the fourth edge portion contacts the inner wall 3a2. The edge portions 99a1 to 99a4 make surface contact with the inner wall 3a1 or the inner wall 3a2 of the recessed portion 3a through the surfaces extending in the arrow Y direction and the arrow X direction. The width direction of the recessed portion 3a is orthogonal to the arrow Y direction along which the recessed portion 3a extends, and is the arrow Z direction which is the same as the direction along which the recessed portion 3b extends.

[0082] Here, when the European coupling 1 rotates in the arrow R2 direction, the portion of the edge portion 99a1 that is farthest from the rotation center CT1 (first rotation center) of the developing drive gear 99 in the arrow Y direction will be positioned closer to the inner wall 3a2 in the arrow Z direction than the rotation center CT1. In addition, when the European coupling 1 rotates in the arrow R2 direction, the portion of the edge portion 99a2 that is farthest from the rotation center CT1 in the arrow Y direction will be positioned closer to the inner wall 3a1 in the arrow Z direction than the rotation center CT1. In addition, when the European coupling 1 rotates in the arrow R1 direction, the portion of the edge portion 99a3 that is farthest from the rotation center CT1 in the arrow Y direction will be positioned closer to the inner wall 3a2 in the arrow Z direction than the rotation center CT1. In addition, when the European coupling 1 rotates in the arrow R1 direction, the portion of the edge portion 99a4 that is farthest from the rotation center CT1 in the arrow Y direction will be positioned closer to the inner wall 3a1 in the arrow Z direction than the rotation center CT1.

[0083] In addition, when viewed in the direction of the rotation axis of the European coupling 1, the protruding portion 99a has a substantially rhombus shape formed by a virtual line H1 connecting the edge portion 99a1, the edge portion 99a2, the edge portion 99a3, and the edge portion 99a4. Specifically, a rhombus shape is formed in which the angle of the corner is 45 degrees when the corner is formed by a virtual line obtained by extending the edge portion 99a1 and the edge portion 99a4, and the angle of the corner is 45 degrees when the corner is formed by a virtual line obtained by extending the edge portion 99a2 and the edge portion 99a3. The substantially rhombus shape may be configured to have the above-mentioned corners, or may be a shape in which the above-mentioned corners are chamfered.

[0084] With this configuration, when the Oldham coupling 1 rotates in the arrow R2 direction, a clearance γ1 is formed between the edge portion 99a1 and the inner wall 3a1 of the recessed portion 3a, and between the edge portion 99a2 and the inner wall 3a2 of the recessed portion 3a. In addition, when the Oldham coupling 1 rotates in the arrow R1 direction, the same clearance γ1 is formed between the edge portion 99a3 and the inner wall 3a1 of the recessed portion 3a, and between the edge portion 99a4 and the inner wall 3a2 of the recessed portion 3a.

[0085] In addition, if Fig. 12B As shown, the protruding portion 89a has the same shape as the protruding portion 99a. That is, the protruding portion 89a includes an edge portion 89a1 (fifth edge portion), and when the European coupling 1 rotates in the direction of the arrow R1, the fifth edge portion contacts one inner wall 3b1 (third inner wall) of the recessed portion 3b in the width direction. In addition, the protruding portion 89a includes an edge portion 89a2 (sixth edge portion), and when the European coupling 1 rotates in the direction of the arrow R1, the sixth edge portion contacts the other inner wall 3b2 (fourth inner wall) of the recessed portion 3b in the width direction. In addition, the protruding portion 89a includes an edge portion 89a3 (seventh edge portion) and an edge portion 89a4 (eighth edge portion), and when the European coupling 1 rotates in the direction of the arrow R2, the seventh edge portion contacts the inner wall 3b1 of the recessed portion 3b, and the eighth edge portion contacts the inner wall 3b2. The edge portions 89a1 to 89a4 make surface contact with the inner wall 3b1 or the inner wall 3b2 of the recessed portion 3b through the surfaces extending in the arrow Z direction and the arrow X direction. The width direction of the recessed portion 3b is orthogonal to the arrow Z direction along which the recessed portion 3b extends, and is the arrow Y direction which is the same as the direction along which the recessed portion 3a extends.

[0086] Here, when the European coupling 1 rotates in the direction of arrow R2, the portion of the edge portion 89a1 that is farthest from the rotation center CT2 (second rotation center) of the drive coupling 89 in the direction of arrow Z will be positioned closer to the inner wall 3b2 in the direction of arrow Y than the rotation center CT2. In addition, when the European coupling 1 rotates in the direction of arrow R2, the portion of the edge portion 89a2 that is farthest from the rotation center CT2 in the direction of arrow Z will be positioned closer to the inner wall 3b1 in the direction of arrow Y than the rotation center CT2. In addition, when the European coupling 1 rotates in the direction of arrow R1, the portion of the edge portion 89a3 that is farthest from the rotation center CT2 in the direction of arrow Z will be positioned closer to the inner wall 3b2 in the direction of arrow Y than the rotation center CT2. In addition, when the European coupling 1 rotates in the direction of arrow R1, the portion of the edge portion 89a4 that is farthest from the rotation center CT2 in the direction of arrow Z will be positioned closer to the inner wall 3b1 in the direction of arrow Y than the rotation center CT2.

[0087] In addition, when viewed in the direction of the rotation axis of the European coupling 1, the protruding portion 89a has a substantially rhombus shape formed by a virtual line H2 connecting the edge portion 89a1, the edge portion 89a2, the edge portion 89a3, and the edge portion 89a4. Specifically, a rhombus shape is formed in which the angle of the corner is 45 degrees when the corner is formed by a virtual line obtained by extending the edge portion 89a1 and the edge portion 89a4, and the angle of the corner is 45 degrees when the corner is formed by a virtual line obtained by extending the edge portion 89a2 and the edge portion 89a3. As in the present embodiment, the substantially rhombus shape may be configured to have the above-mentioned corners, or may be a shape in which the above-mentioned corners are chamfered.

[0088] With this configuration, when the Oldham coupling 1 rotates in the direction of arrow R2, a clearance γ2 is formed between the edge portion 89a1 and the inner wall 3b1 of the recessed portion 3b, and between the edge portion 89a2 and the inner wall 3b2 of the recessed portion 3b. In addition, when the Oldham coupling 1 rotates in the direction of arrow R1, the same clearance γ2 is formed between the edge portion 89a3 and the inner wall 3b1 of the recessed portion 3b, and between the edge portion 89a4 and the inner wall 3b2 of the recessed portion 3b.

[0089] In this way, according to the present embodiment, in the Oldham coupling 1, the driving force can be transmitted while the play γ1 in the rotation direction is provided between the developing drive gear 99 and the intermediate member 3 and the play γ2 in the rotation direction is provided between the driving coupling 89 and the intermediate member 3. In addition, since the edge portions 99a1 to 99a4 make surface contact with the inner wall 3a1 or the inner wall 3a2 of the recessed portion 3a, and the edge portions 89a1 to 89a4 make surface contact with the inner wall 3b1 or the inner wall 3b2 of the recessed portion 3b, when the driving force is transmitted, the strength of the protruding portions 99a and 89a can be ensured and the deformation thereof can be suppressed.

[0090] In addition, as in the present embodiment, when the play in the rotational direction is provided between the developing drive gear 99 and the intermediate member 3 and between the driving coupling 89 and the intermediate member 3, it is possible to suppress the reduction in the strength of the coupling itself more than when the play β provided between the protruding portion of the developing coupling 75 and the fitting groove of the driving coupling 89 is increased. In addition, it is possible to suppress the event that the drive cannot be stably transmitted due to the increase in the play β.

[0091] For example, when the length of the assembly groove of the drive coupling 89 in the rotation direction increases so as to increase the clearance β, the strength of the drive coupling 89 itself decreases and the drive cannot be stably transmitted, which is a problem. In addition, when the length of the assembly groove of the drive coupling 89 in the rotation direction increases, three assembly grooves cannot be provided depending on the size of the drive coupling 89, which is a problem. When only two assembly grooves are provided, two protruding portions of the developing coupling 75 are also provided, and the two protruding portions and the two assembly grooves are assembled with each other to transmit the driving force. In this case, when the assembly force between one pair of protruding portions and the assembly groove is weak, the drive cannot be stably transmitted. In addition, when the length of the protruding portion of the developing coupling 75 in the rotation direction is reduced to increase the clearance β, the protruding portion of the developing coupling 75 is reduced in strength due to the reduction in length in the rotation direction, and is damaged when the drive is transmitted, which is a problem.

[0092] In the present embodiment, a configuration is adopted in which not only the clearance β between the developing coupling 75 and the driving coupling 89 to be separated when the unit is attached and detached is provided, but also the clearance between the developing drive gear 99 and the intermediate member 3 of the European coupling and / or the clearance between the driving coupling 89 and the intermediate member 3 is provided. Therefore, the drive can be stably transmitted, and the driving force can be selectively transmitted to the driving target depending on whether the motor rotates forward or reversely. In addition, in the configuration in which the clearance in the rotation direction is provided, the driving force can be transmitted even in a state in which the rotation axes of the two rotating shafts are not aligned with each other.

[0093] <Operation Timing When the Motor Rotates in Reverse Direction>

[0094] 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 in image formation will be described.

[0095] Fig.13 1 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 during image formation from the state where the driving of the motors 92a and 92b is stopped. Here, when the image forming operation is finished, it is assumed that these components are stopped in a state where the clearance α between the driving coupling 96 and the drum coupling 13, the clearance β between the driving coupling 89 and the developing coupling 75, and the clearances γ1 and γ2 of the Oldham coupling 1 are ensured.

[0096] From this state, the motors 92a and 92b are driven to rotate in the direction opposite to the rotation direction during image formation. When the motors 92a and 92b start rotating, the drum drive gear 95 and the development drive gear 99 start rotating (timing T1).

[0097] Next, when the timing T2 is reached, the play γ1 of the Oldham coupling 1 is returned to zero by the rotation of the development drive gear 99, and the intermediate member 3 starts to rotate. Thereafter, when the timing T3 is reached, the play γ2 of the Oldham coupling 1 is returned to zero by the rotation of the intermediate member 3, and the drive coupling 89 starts to rotate.

[0098] Next, when the timing T4 is reached, the backlash α is returned to zero by the rotation of the drum driving gear 95 , the drum coupling 13 starts to rotate, and thus the photosensitive drum 26 starts to rotate.

[0099] Thereafter, when the timing T5 is reached, the play β is returned to zero by the rotation of the drive coupling 89, the development coupling 75 starts to rotate, and thus the development sleeve 71 starts to rotate.

[0100] Next, when the timing T6 is reached, as the photosensitive drum 26 rotates, the gear portion 32a of the separation member 32 meshes with the flange gear 14, and the charging roller 27 starts to separate from the photosensitive drum 26. Then, when the timing T7 is reached, the charging roller 27 is separated to a predetermined distance, and the separation is completed. Thereafter, 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.

[0101] In this way, when the Oldham coupling 1 of the present embodiment is provided, the rotation of the developing sleeve 71 in the opposite direction as the motors 92a and 92b are rotationally driven in the direction opposite to the rotation direction at the time of image formation, and the separation operation of the charging roller 27 from the photosensitive drum 26 can be performed at different timings. That is, when the motor rotates in the direction opposite to the rotation direction at the time of image formation, only the developing sleeve 71 can be rotated 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.

[0102] Therefore, it is possible to suppress defects that occur when the separation operation of the charging roller 27 and the reverse rotation of the developing sleeve 71 are simultaneously performed. For example, when the image forming apparatus continuously performs an image forming process on a recording material, the reverse rotation operation of the developing sleeve 71 is performed every time an image forming process is performed on 500 sheets of A4 paper; however, since the image forming process is continuously performed, the separation operation of the charging roller 27 from the photosensitive drum 26 is not required. Therefore, the Oldham coupling 1 of the present embodiment is provided so that only the developing sleeve 71 can rotate in the direction opposite to the rotation direction at the time of image forming without the separation of the charging roller 27 from the photosensitive drum 26. Therefore, it is possible to suppress unnecessary separation operation of the charging roller 27.

[0103] In addition, since the Oldham coupling 1 of the present embodiment is provided, defects caused by the reverse rotation operation of the separation member 32 and the developing sleeve 71 by the same amount can be suppressed. For example, when the separation operation of the charging roller 27 starts at the same time as the reverse rotation of the developing sleeve 71, and the rotation operation of the separation member 32 ends according to the end of the reverse rotation operation of the developing sleeve 71, it is possible to suppress a malfunction that occurs when the separation member 32 contacts the drum container 11. In addition, when the separation operation of the charging roller 27 starts at the same time as the reverse rotation of the developing sleeve 71, and the reverse rotation of the developing sleeve 71 ends according to the end of the separation operation of the charging roller 27, it is possible to suppress the insufficient amount of pushing of the toner deposited in the space surrounded by the developing sleeve 71, the pressing sheet 77, and the developing blade 72 toward the stirring chamber 80 side.

[0104] (Second embodiment)

[0105] Next, a second embodiment of the Oldham coupling according to the present invention will be described with reference to the drawings. Portions that are duplicated as those described in the first embodiment are denoted by the same reference numerals, and thus description thereof will be omitted.

[0106] The configuration of the Oldham coupling 1 according to this embodiment is different from that of the first embodiment in the shape of the protruding portion 99a of the developing drive gear 99 and the shape of the protruding portion 89a of the driving coupling 89. Other configurations including the overall configuration of the image forming apparatus A are the same as those of the first embodiment.

[0107] Fig.14 : is a perspective view of the Oldham coupling 1 according to the present embodiment as seen 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 seen from the rear side of the image forming apparatus A. Fig.16A 1 is a view showing an assembled portion between the developing drive gear 99 of the Oldham coupling 1 and the intermediate member 3 . Fig. 16B 1 is a view showing an assembled portion between the drive coupling 89 of the Oldham coupling 1 and the intermediate member 3 .

[0108] like Fig.14 and Fig.15 As shown, the protruding portion 99a of the developing drive gear 99 according to the present embodiment includes 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 99x2 and the cylindrical portion 99x1 and the distance between the cylindrical portion 99x3 and the cylindrical portion 99x1 are also set to be the same.

[0109] In addition, the protruding portion 89a of the drive coupling 89 includes 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 89x2 and the cylindrical portion 89x1 and the distance between the cylindrical portion 89x3 and the cylindrical portion 89x1 are also set to be the same.

[0110] When the development drive gear 99 is rotated by the driving force of the motor 92a or the motor 92b, the protruding portion 99a of the development drive gear 99 contacts the inner wall of the recessed portion 3a while sliding relative to the inside of the recessed portion 3a, and transmits the driving force to the intermediate member 3, causing the intermediate member 3 to rotate. Then, when the intermediate member 3 rotates, the inner wall of the recessed portion 3b contacts the protruding portion 89a of the drive coupling 89 while the protruding portion 89a moves relative to the inside of the recessed portion 3b in a sliding manner, and transmits the driving force to the drive coupling 89, causing the drive coupling 89 to rotate. In this way, even when the rotation axis of the rotation shaft (not shown) of the development drive gear 99 and the rotation axis of the rotation shaft 100 of the development coupling 75 are not aligned with each other, the driving force of the motor 92a or the motor 92b will be stably transmitted to the rotation shaft 100 of the development coupling 75 via the Oldham coupling 1.

[0111] Here, if Fig.16AAs shown, the cylindrical portion 99x1 includes an edge portion 99x1a (first edge portion) and an edge portion 99x1b (second edge portion), and when the European coupling 1 rotates in the arrow R1 direction (first rotation direction), the first edge portion contacts one inner wall 3a1 (first inner wall) of the recessed portion 3a in the width direction, and the second edge portion contacts the other inner wall 3a2 (second inner wall). In addition, the cylindrical portion 99x2 includes an edge portion 99x2a (first edge portion), and when the European coupling 1 rotates in the arrow R1 direction, the first edge portion contacts the inner wall 3a1 of the recessed portion 3a. In addition, the cylindrical portion 99x3 includes an edge portion 99x3a (second edge portion), and when the European coupling 1 rotates in the arrow R1 direction, the second edge portion contacts the inner wall 3a2 of the recessed portion 3a. The edge portions 99x1a, 99x1b, 99x2a, and 99x3a make line contact with the inner wall 3a1 or the inner wall 3a2 of the recessed portion 3a through a line extending in the rotation axis direction of the Oldham coupling 1.

[0112] In addition, the cylindrical portion 99x1 includes an edge portion 99x1a (third edge portion) and an edge portion 99x1b (fourth edge portion), and when the European coupling 1 rotates in the arrow R2 direction (second rotation direction), the third edge portion contacts the inner wall 3a1 of the recessed portion 3a, and the fourth edge portion contacts the inner wall 3a2. In addition, the cylindrical portion 99x2 includes an edge portion 99x2b (third edge portion), and when the European coupling 1 rotates in the arrow R2 direction, the third edge portion contacts the inner wall 3a1 of the recessed portion 3a. In addition, the cylindrical portion 99x3 includes an edge portion 99x3b (fourth edge portion), and when the European coupling 1 rotates in the arrow R2 direction, the fourth edge portion contacts the inner wall 3a2 of the recessed portion 3a. The edge portions 99x1a, 99x1b, 99x2b, and 99x3b make line contact with the inner wall 3a1 or the inner wall 3a2 of the recessed portion 3a through a line extending in the rotation axis direction of the Oldham coupling 1.

[0113] Here, when the Oldham coupling 1 rotates in the arrow R2 direction, the edge portion 99x2a of the cylindrical portion 99x2 will be positioned closer to the inner wall 3a2 in the arrow Z direction than the rotation center CT1 (first rotation center) of the developing drive gear 99. The edge portion 99x2a of the cylindrical portion 99x2 is a portion 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 recessed portion 3a when the Oldham coupling 1 rotates in the arrow R1 direction.

[0114] In addition, when the Oldham coupling 1 rotates in the arrow R2 direction, the edge portion 99x3a of the cylindrical portion 99x3 will be positioned closer to the inner wall 3a1 in the arrow Z direction than the rotation center CT1 of the developing drive gear 99. The edge portion 99x3a of the cylindrical portion 99x3 is a portion farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that contact the inner wall 3a2 of the recessed portion 3a when the Oldham coupling 1 rotates in the arrow R1 direction.

[0115] In addition, when the Oldham coupling 1 rotates in the arrow R1 direction, the edge portion 99x2b of the cylindrical portion 99x2 will be positioned closer to the inner wall 3a1 in the arrow Z direction than the rotation center CT1 of the developing drive gear 99. The edge portion 99x2b of the cylindrical portion 99x2 is a portion farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that contact the inner wall 3a2 of the recessed portion 3a when the Oldham coupling 1 rotates in the arrow R2 direction.

[0116] In addition, when the Oldham coupling 1 rotates in the arrow R1 direction, the edge portion 99x3b of the cylindrical portion 99x3 will be positioned closer to the inner wall 3a2 in the arrow Z direction than the rotation center CT1 of the developing drive gear 99. The edge portion 99x3b of the cylindrical portion 99x3 is a portion farthest from the rotation center CT1 of the developing drive gear 99 in the arrow Y direction among the edge portions that contact the inner wall 3a1 of the recessed portion 3a when the Oldham coupling 1 rotates in the arrow R2 direction.

[0117] In addition, when viewed in the direction of the rotation axis of the European coupling 1, the protruding portion 99a has a substantially rhombus shape formed by a virtual line H3 connecting edge portions 99x1a, 99x1b, 99x2a, 99x2b, 99x3a, and 99x3b. Specifically, a rhombus shape is formed in which the angle of the corner is 45 degrees when the corner is formed by two lines obtained by extending the virtual line connecting edge portion 99x1a and edge portion 99x2a and the virtual line connecting edge portion 99x1b and edge portion 99x2b, and the angle of the corner is 45 degrees when the corner is formed by two lines obtained by extending the virtual line connecting edge portion 99x1a and edge portion 99x3b and the virtual line connecting edge portion 99x1b and edge portion 99x3a. The substantially rhombus shape may be configured to have the above-mentioned corners, or may be a shape in which the above-mentioned corners are chamfered.

[0118] With this configuration, when the European coupling 1 rotates in the direction of arrow R2, a clearance γ3 is formed between the edge portion 99x2a and the inner wall 3a1 of the recessed portion 3a, and between the edge portion 99x3a and the inner wall 3a2 of the recessed portion 3a. In addition, when the European coupling 1 rotates in the direction of arrow R1, the same clearance γ3 is formed between the edge portion 99x2b and the inner wall 3a2 of the recessed portion 3a, and between the edge portion 99x3b and the inner wall 3a1 of the recessed portion 3a.

[0119] In addition, if Fig. 16B As shown, the cylindrical portion 89x1 includes an edge portion 89x1a (fifth edge portion) and an edge portion 89x1b (sixth edge portion), and when the European coupling 1 rotates in the direction of arrow R1, the fifth edge portion contacts one inner wall 3b1 (third inner wall) of the recessed portion 3b in the width direction, and the sixth edge portion contacts the other inner wall 3b2 (fourth inner wall). In addition, the cylindrical portion 89x2 includes an edge portion 89x2a (fifth edge portion), and when the European coupling 1 rotates in the direction of arrow R1, the fifth edge portion contacts the inner wall 3b1 of the recessed portion 3b. In addition, the cylindrical portion 89x3 includes an edge portion 89x3a (sixth edge portion), and when the European coupling 1 rotates in the direction of arrow R1, the sixth edge portion contacts the inner wall 3b2 of the recessed portion 3b. The edge portions 89x1a, 89x1b, 89x2a, and 89x3a make line contact with the inner wall 3b1 or the inner wall 3b2 of the recessed portion 3b through a line extending in the rotation axis direction of the Oldham coupling 1.

[0120] In addition, the cylindrical portion 89x1 includes an edge portion 89x1a (fifth edge portion) and an edge portion 89x1b (sixth edge portion), and when the European coupling 1 rotates in the direction of arrow R2, the fifth edge portion contacts the inner wall 3b1 of the recessed portion 3b, and the sixth edge portion contacts the inner wall 3b2. In addition, the cylindrical portion 89x2 includes an edge portion 89x2b (fifth edge portion), and when the European coupling 1 rotates in the direction of arrow R2, the fifth edge portion contacts the inner wall 3b1 of the recessed portion 3b. In addition, the cylindrical portion 89x3 includes an edge portion 89x3b (sixth edge portion), and when the European coupling 1 rotates in the direction of arrow R2, the sixth edge portion contacts the inner wall 3b2 of the recessed portion 3b. The edge portions 89x1a, 89x1b, 89x2b, and 89x3b make line contact with the inner wall 3b1 or the inner wall 3b2 of the recessed portion 3b through a line extending in the rotation axis direction of the Oldham coupling 1.

[0121] Here, when the Oldham coupling 1 rotates in the arrow R2 direction, the edge portion 89x2a of the cylindrical portion 89x2 will be positioned closer to the inner wall 3b2 in the arrow Y direction than the rotation center CT2 (second rotation center) of the drive coupling 89. The edge portion 89x2a of the cylindrical portion 89x2 is a portion 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 recessed portion 3b when the Oldham coupling 1 rotates in the arrow R1 direction.

[0122] In addition, when the Oldham coupling 1 rotates in the arrow R2 direction, the edge portion 89x3a of the cylindrical portion 89x3 will be positioned closer to the inner wall 3b1 in the arrow Y direction than the rotation center CT2 of the drive coupling 89. The edge portion 89x3a of the cylindrical portion 89x3 is a portion farthest from the rotation center CT2 of the drive coupling 89 in the arrow Z direction among the edge portions that contact the inner wall 3b2 of the recessed portion 3b when the Oldham coupling 1 rotates in the arrow R1 direction.

[0123] In addition, when the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 89x2b of the cylindrical portion 89x2 will be positioned closer to the inner wall 3b1 in the direction of arrow Y than the rotation center CT2 of the drive coupling 89. The edge portion 89x2b of the cylindrical portion 89x2 is a portion farthest from the rotation center CT2 of the drive coupling 89 in the direction of arrow Z among the edge portions that contact the inner wall 3b2 of the recessed portion 3b when the Oldham coupling 1 rotates in the direction of arrow R2.

[0124] In addition, when the Oldham coupling 1 rotates in the direction of arrow R1, the edge portion 89x3b of the cylindrical portion 89x3 will be positioned closer to the inner wall 3b2 in the direction of arrow Y than the rotation center CT2 of the drive coupling 89. The edge portion 89x3b of the cylindrical portion 89x3 is a portion farthest from the rotation center CT2 of the drive coupling 89 in the direction of arrow Z among the edge portions that contact the inner wall 3b1 of the recessed portion 3b when the Oldham coupling 1 rotates in the direction of arrow R2.

[0125] In addition, when viewed in the direction of the rotation axis of the European coupling 1, the protruding portion 89a has a substantially rhombus shape formed by a virtual line H4 connecting edge portions 89x1a, 89x1b, 89x2a, 89x2b, 89x3a, and 89x3b. Specifically, a rhombus shape is formed in which the angle of the corner is 45 degrees when the corner is formed by two lines obtained by extending the virtual line connecting edge portion 89x1a and edge portion 89x2a and the virtual line connecting edge portion 89x1b and edge portion 89x2b, and the angle of the corner is 45 degrees when the corner is formed by two lines obtained by extending the virtual line connecting edge portion 89x1a and edge portion 89x3b and the virtual line connecting edge portion 89x1b and edge portion 89x3a. The substantially rhombus shape may be configured to have the above-mentioned corners, or may be a shape in which the above-mentioned corners are chamfered.

[0126] With this configuration, when the European coupling 1 rotates in the direction of arrow R2, a clearance γ4 is formed between the edge portion 89x2a and the inner wall 3b1 of the recessed portion 3b, and between the edge portion 89x3a and the inner wall 3b2 of the recessed portion 3b. In addition, when the European coupling 1 rotates in the direction of arrow R1, the same clearance γ4 is formed between the edge portion 89x2b and the inner wall 3b2 of the recessed portion 3b, and between the edge portion 89x3b and the inner wall 3b1 of the recessed portion 3b.

[0127] In this way, according to the present embodiment, in the Oldham coupling 1, the driving force can be transmitted while the play γ3 in the rotation direction is provided between the developing drive gear 99 and the intermediate member 3 and the play γ4 in the rotation direction is provided between the driving coupling 89 and the intermediate member 3. In addition, the driving force can be selectively transmitted to the driving target depending on whether the motor rotates forward or reversely, and the driving force can be transmitted even in a state where the rotation axes of the two rotating shafts are not aligned with each other.

[0128] In the first and second embodiments, in the drive unit 90, the configuration has been described in which the Oldham coupling 1 is provided in the drive system that transmits the driving force to the developing sleeve 71, but the present invention is not limited to the configuration. That is, the same effect can be obtained even with a configuration in which the Oldham coupling 1 is provided in another portion that transmits the driving force (for example, in the drive system that transmits the driving force to the photosensitive drum 26).

[0129] In addition, 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 the direction opposite to the rotation direction at the time of image formation, but a configuration may be adopted in which only one of the photosensitive drum 26 and the developing sleeve 71 will rotate in the direction opposite to the rotation direction at the time of image formation. In this case, when the above-described European coupling 1 is provided, the amount of rotation of one of the photosensitive drum 26 and the developing sleeve 71 in the opposite direction can be increased. Therefore, depending on whether the motor rotates forward or reversely, the driving force can be selectively transmitted to the driving target, and the driving force can be transmitted even in a state where the rotation axes of the two rotating shafts are not aligned with each other.

[0130] In addition, in apparatuses other than the image forming apparatus, the same effect can be obtained even with a configuration in which the Oldham coupling 1 is provided as a portion that transmits a driving force from a driving source to a unit as a target.

[0131] In addition, in the first embodiment and the second embodiment, in the European coupling 1, a configuration has been described in which both the protruding portion 99a of the developing drive gear 99 and the protruding portion 89a of the driving coupling 89 have a substantially rhombus shape, but the present invention is not limited to the configuration. That is, one of the protruding portion 99a of the developing drive gear 99 and the protruding portion 89a of the driving coupling 89 may have a rectangular shape substantially the same as the shape of the recessed portion 3a or the recessed portion 3b of the intermediate member 3. That is, a configuration in which only one of the clearance γ1 between the developing drive gear 99 and the intermediate member 3 and the clearance γ2 between the driving coupling 89 and the intermediate member 3 is provided may be adopted. In addition, the rotation angles of the clearances γ1 to γ4 are not limited to the angles described in the first embodiment and the second embodiment, and may be set to any angle.

[0132] In addition, in the first and second embodiments, in the Oldham coupling 1, a configuration has been described in which the protruding portions 99a and 89a are respectively provided in the developing drive gear 99 and the driving coupling 89 and the recessed portions 3a and 3b are provided in the intermediate member 3, but the present invention is not limited to the configuration.

[0133] That is, the same effect can be obtained even using such a configuration, in which the intermediate member 3 is provided with protrusions corresponding to the protrusions 99a and 89a at one end and the other end in the direction of the rotation axis of the European coupling 1, and the developing drive gear 99 and the driving coupling 89 are provided with recessed portions that are assembled to the protrusions of the intermediate member 3.

[0134] According to the present invention, an Oldham coupling having play in the rotational direction and capable of transmitting a driving force can be provided.

[0135] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0136] This application claims the benefit of Japanese Patent Application No. 2020-206318, filed December 11, 2020, which is hereby incorporated by reference herein in its entirety.

Claims

1. A European coupling, comprising: First Hub; Second hub; an intermediate member configured to transmit a driving force at a position between the first hub and the second hub; a recessed portion, the recessed portion being provided in one of the end faces of the first hub in the direction of the rotation axis of the Oldham coupling and the end faces of the intermediate member in the direction of the rotation axis of the Oldham coupling, being recessed in the direction of the rotation axis, and extending in a first direction orthogonal to the direction of the rotation axis, and the recessed portion comprising a first inner wall and a second inner wall, the first inner wall being located on one side in a second direction orthogonal to the direction of the rotation axis and the first direction, the second inner wall being provided on the other side in the second direction and extending parallel to the first inner wall, a protruding portion, the protruding portion being provided in the other of the end surface of the first hub in the rotation axis direction of the Older's coupling and the end surface of the intermediate member in the rotation axis direction of the Older's coupling, the protruding portion protruding in the rotation axis direction, being fitted to the recessed portion, and being configured to transmit a driving force between the intermediate member and the first hub, and the protruding portion comprising: a first edge portion, the first edge portion being configured to contact the first inner wall when the Oldham coupling is rotated in a first rotational direction, a second edge portion configured to contact the second inner wall when the Oldham coupling is rotated in the first rotation direction, a third edge portion configured to contact the first inner wall in a state where the Oldham coupling is rotated in a second rotation direction opposite to the first rotation direction, and a fourth edge portion configured to contact the second inner wall when the Oldham coupling is rotated in the second rotation direction, wherein, in a state where 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 edge portion is separated from the second inner wall, wherein, in a state where 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 separated from the second inner wall, wherein, in a state where the Oldham coupling rotates in the second rotation direction as the motor rotates, a portion of the first edge portion that is farthest from a first rotation center that is a rotation center of the first hub in the first direction will be positioned closer to the second inner wall than the first rotation center in the second direction, and a portion of the second edge portion that is farthest from the first rotation center in the first direction will be positioned closer to the first inner wall than the first rotation center in the second direction, and In which, when the European coupling rotates in the first rotation direction as the motor rotates, the part of the third edge portion farthest from the first rotation center in the first direction will be positioned closer to the second inner wall in the second direction than the first rotation center, and the part of the fourth edge portion farthest from the first rotation center in the first direction will be positioned closer to the first inner wall in the second direction than the first rotation center.

2. The European coupling according to claim 1, wherein: The protruding portion has a rhombus shape formed by a virtual line connecting the first edge portion, the second edge portion, the third edge portion, and the fourth edge portion in a state viewed in the rotation axis direction.

3. The European coupling according to claim 1, wherein: In the protruding portion, the first edge portion and the third edge portion make surface contact with the first inner wall through surfaces extending in the rotation axis direction and in the first direction, and the second edge portion and the fourth edge portion make surface contact with the second inner wall through surfaces extending in the rotation axis direction and in the first direction.

4. The European coupling according to claim 1, wherein: In the protruding portion, the first edge portion and the third edge portion make line contact with the first inner wall through a line extending in the rotation axis direction, and the second edge portion and the fourth edge portion make line contact with the second inner wall through a line extending in the rotation axis direction.

5. The European coupling according to claim 1, in, the recessed portion is a first recessed portion, and the protruding portion is a first protruding portion, wherein one of the intermediate member and the second hub is provided with a second recessed portion, the second recessed portion is formed in an end surface in the direction of the rotation axis, is recessed in the direction of the rotation axis, and extends in the second direction, and the second recessed portion includes a third inner wall and a fourth inner wall, the third inner wall is located on one side in the first direction, and the fourth inner wall is provided on the other side in the first direction and extends parallel to the first inner wall, The other of the intermediate member and the second hub is provided with a second protruding portion protruding in the rotation axis direction, the second protruding portion is fitted into the second recessed portion, is configured to transmit a driving force between the intermediate member and the second hub, and the second protruding portion includes: a fifth edge portion configured to contact the third inner wall in a state where the Oldham coupling rotates in the first rotation direction as the motor rotates, a sixth edge portion configured to contact the fourth inner wall in a state where the Oldham coupling rotates in the first rotation direction as the motor rotates, a seventh edge portion configured to contact the third inner wall in a state where the Oldham coupling rotates in the second rotation direction as the motor rotates, and an eighth edge portion configured to contact the fourth inner wall in a state where the Oldham coupling rotates in the second rotation direction as the motor rotates, In a state where the fifth edge portion is in contact with the third inner wall and the sixth edge portion is in contact with the fourth inner wall, the seventh edge portion is separated from the third inner wall and the eighth edge portion is separated from the fourth inner wall, In a state where the seventh edge portion is in contact with the third inner wall and the eighth edge portion is in contact with the fourth inner wall, the fifth edge portion is separated from the third inner wall and the sixth edge portion is separated from the fourth inner wall, In a state where the Oldham coupling rotates in the second rotation direction as the motor rotates, a portion of the fifth edge portion farthest from the second rotation center, which is the rotation center of the second hub, in the second direction will be positioned closer to the fourth inner wall than the second rotation center in the first direction, and a portion of the sixth edge portion farthest from the second rotation center in the second direction will be positioned closer to the third inner wall than the second rotation center in the first direction, and When the European coupling rotates in the first rotation direction as the motor rotates, the portion of the seventh edge portion farthest from the second rotation center in the second direction will be positioned closer to the fourth inner wall than the second rotation center in the first direction, and the portion of the eighth edge portion farthest from the second rotation center in the second direction will be positioned closer to the third inner wall than the second rotation center in the first direction.

6. The European coupling according to claim 5, wherein: The second protruding portion has a rhombus shape formed by a virtual line connecting the fifth edge portion, the sixth edge portion, the seventh edge portion, and the eighth edge portion in a state viewed in the rotation axis direction.

7. The European coupling according to claim 5, wherein: In the second protruding portion, the fifth edge portion and the seventh edge portion make surface contact with the third inner wall through surfaces extending in the direction of the rotation axis and in the second direction, and the sixth edge portion and the eighth edge portion make surface contact with the fourth inner wall through surfaces extending in the direction of the rotation axis and in the second direction.

8. The European coupling according to claim 5, wherein: In the second protruding portion, the fifth edge portion and the seventh edge portion make line contact with the third inner wall through a line extending in the rotation axis direction, and the sixth edge portion and the eighth edge portion make line contact with the fourth inner wall through a line extending in the rotation axis direction.

9. An imaging device comprising: motor; The European coupling according to claim 1; as well as An image forming unit is driven by the driving force of the motor transmitted via the Oldham coupling to form an image on a sheet.

10. The imaging device according to claim 9, wherein The image forming unit includes a photosensitive member and a developer carrier configured to carry a developer and attach the developer to a surface of the photosensitive member, and The developer carrier is to be rotated by the driving force of the motor transmitted via the Oldham coupling.

11. The imaging device according to claim 10, wherein The photosensitive member will be rotated by the driving force of the motor. 12 . The imaging device according to claim 9 , wherein the imaging unit is configured to be detachably attachable to the imaging device.

Images