JP2005024575A - Rotary development device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of image defects by preventing, for instance, the vibration of development units, which is caused by a fitting backlash at a rocking support point on which each development unit is supported so as to freely rock. <P>SOLUTION: The image forming apparatus has a rotary development device including a rotor formed from a rotary frame 6 and a plurality of development units 21 removably loaded along the periphery of the cylinder of the rotor, and selectively rotates and moves the development units 21 to a developing position opposite a photoreceptor 23, thereby developing latent images on the photoreceptor 23. The rotary development device includes: a positioning means for positioning the rotor and the selected development unit 21 by the fitting of a positioning pin 16 in a positioning hole 19; rocking energizing means 17 for energizing the development unit so as to rock it towards the photoreceptor using the positioning pin as the rocking support point; and a one-way moving means 18 for moving the rocking support point of the development unit to the one side of the positioning hole. This eliminates the fitting backlash between the positioning pin 16 at the rocking support point on which the development unit 21 is supported so as to freely rock, and the positioning hole 19 being a fit hole for the pin 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a rotating body composed of a rotary frame and a plurality of developing units that are detachably mounted along the outer circumference of the rotating body, and selectively put the developing unit at a developing position facing the photoconductor. The present invention relates to a rotary developing device and an image forming apparatus that rotate and move to develop a latent image on the photosensitive member.
[0002]
[Prior art]
As an image forming apparatus such as a copying machine, a printer, and a fax machine using electrophotography, an electrostatic latent image of a plurality of colors is sequentially formed on a photosensitive member, and the electrostatic latent image is sequentially developed into each color toner image by a rotary developing device. After that, there is a system in which the respective color toner images are transferred onto the intermediate transfer medium while being transferred, and the full color toner image transferred onto the intermediate transfer medium is transferred to a transfer material and then fixed.
[0003]
The rotary developing device is provided with a rotating body facing the photoreceptor, and a plurality of developing units (yellow, cyan, magenta, black developing units) are mounted in the rotating body, and the rotating body is rotated and moved. The electrostatic latent image is developed with toner by selectively bringing one of the plurality of developing units into contact with the developing position of the photosensitive member, rotating the developing roller in the developing unit and applying a developing bias. Yes.
[0004]
In a color image device equipped with a rotary developing device, the developing device is urged in the direction of the photosensitive member to be coaxial with the developing roller for positioning the photosensitive member and the developing roller to ensure an appropriate gap. There is known a system in which a roller disposed on the surface is abutted against a photoreceptor. In this method, the variation of the developing device mounted on the rotary developing device as a cartridge affects the meshing between the driving input gear and the driving output gear, and the meshing between the driving input gear and the driving output gear by each cartridge and each color developing device. The situation changes. Therefore, an idler gear is provided at a position corresponding to each developing device of the rotary developing device, and the gear train of the developing device is meshed with the idler gear, and the idler gear is meshed with the drive output gear at the developing position. By configuring, an apparatus has been proposed that can stably bias the developing roller in the direction of the photosensitive member at the time of developing drive transmission, and facilitate the securing of the gap between the photosensitive member and the developing roller (for example, Patent Document 1). reference).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-5484
[Problems to be solved by the invention]
In the above conventional apparatus, the developing device is pressed from the back by the elastic body, and in addition, the reaction force generated by the development driving acts in the direction of pressing the developing device against the photosensitive member, and the developing device is rotated around the swing fulcrum. Although it is moved and pressed against the photosensitive member, a positioning hole of the developing cartridge is inserted into the swing fulcrum. Such an elastic body and transmission reaction force are used to press the developing device against the photosensitive member, and by devising the gear material, the gear train of gears that transmits the drive to the developing device is connected to the developing device. On the other hand, the vibration from the drive source can be absorbed. On the other hand, in the fitting portion of the swing fulcrum, in order to allow variation in component accuracy and to allow the developer cartridge to be smoothly attached and detached, there is not a little loose play between the pin of the swing fulcrum and its fitting hole. It will exist. Since the vibration from the driving source generated mainly during the development driving acts on the fitting backlash, there is a problem that the developing device itself is violated or resonates, resulting in image defects such as banding.
[0007]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention solves the above-described problem, and prevents the development device from being ramped up by a fitting backlash at a swinging fulcrum that supports the development device so as to be able to swing, so as not to cause an image defect. It is.
[0008]
To this end, the present invention includes a rotating body composed of a rotary frame and a plurality of developing devices that are detachably mounted along the outer circumference of the rotating body, and selectively develops the developing device so as to face the photoconductor. In a rotary developing device that rotates and moves to a position and develops a latent image on the photosensitive member or an image forming apparatus equipped with the rotary developing device, the rotating member and the developing device are fitted by positioning pins and positioning holes. Positioning means for positioning, swinging biasing means for swinging and biasing the developing device toward the photosensitive member with the positioning pin as a swinging fulcrum, and a piece for bringing the swinging fulcrum of the developing device toward one of the positioning holes It is characterized by providing a shifting means.
[0009]
The biasing means is provided in the vicinity of the positioning means, and biased in the direction perpendicular to the line connecting the rotation axis of the rotating body and the rotation axis of the photosensitive member, in the direction of the positioning pin of the positioning means, and the rotation An elastic member provided between the positioning member and the developing device and biasing in the side-shift direction, or an elastic member provided between the positioning pin and the positioning hole and biasing in the side-shift direction. The positioning pin of the positioning means is provided on the rotation center axis of the idler gear on the rotating body that meshes with the drive output gear at the developing position, and the positioning hole is fitted with the positioning pin of the developing device. It is provided at a position.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a rotary developing device according to the present invention, wherein 1 is a rotary developing device, 2 is a rotary idler gear, 3 is a developing device input gear, 4 is a developing roller gear, 6 is a rotary frame, Reference numeral 16 denotes a positioning pin, 18 denotes a fitting back elastic member, 19 denotes a positioning hole, 21 denotes a developing device, and 22 denotes a developing roller.
[0011]
In FIG. 1, a rotary developing device 1 detachably mounts a plurality of developing units 21 along a cylindrical outer periphery of a rotating body composed of a rotary frame 6, and selectively selects each developing unit 21 by a developing color switching operation. The developing device 21 is rotated and moved to a developing position opposite to a developing position 23 (not shown), and the developing device 21 is oscillated and brought into contact with the photosensitive member 23 to develop a latent image on the photosensitive member. In the case of four full colors, the rotary developing device 1 is detachably mounted with developing devices 21 of developing colors of Y (yellow), M (magenta), C (cyan), and K (black). The rotary idler gear 2 is rotatably arranged in the rotary developing device 1 so as to mesh with a drive output gear 8 (not shown) that is driven and transmitted from the drive motor 8.
[0012]
For positioning of the developing device 21, the positioning pin 16 is provided on the rotation center shaft of the rotary idler gear 2, and the developing device 21 is inserted into the rotary developing device 1 from below as shown in FIG. As shown, the positioning pin 16 is fitted into the positioning hole 19 of the developing device 21. The developing device 21 is configured such that the developing roller 22 can swing opposite to the photosensitive member 23 (not shown) around the rotation center axis provided with the positioning pin 16. As shown in FIG. 1 (B), the fitting back stopper elastic member 18 has the positioning pin 16 and the developing device in a state where the positioning hole 19 of the developing device 21 is fitted to the positioning pin 16 and the developing device 21 is positioned. A fixing backlash is fixed to the positioning hole 19 of the developing device 21 to prevent the developing device 21 from moving up and resonating, and a plate spring is fixed to the rotary frame 6 so that the developing device 21 is moved in one direction. It is composed of a one-sided member.
[0013]
FIG. 2 is a diagram showing a driving wheel train of the developing device and a swinging biasing mechanism of the developing device, where 7 is a driving motor, 8 is a driving output gear, and 17 is a developing device biasing spring. Compared to FIG. 1 in which the fitting positioning portion between the positioning pin 16 and the positioning hole 19 of the developing device 21 is enlarged by a cross section parallel to the rotating shaft of the rotary developing device 1, the rotating developing device 1 has a rotating shaft. FIG. 2 shows the driving wheel train of the developing device and the swinging urging mechanism of the developing device with a right-angle cross section.
[0014]
In FIG. 2, the developing device 21 is positioned on the rotation center axis of the rotary idler gear 2, and the developing roller 22 is configured to be swingable facing the photoconductor 23 around the rotation center axis. . Here, by driving the drive output gear 8 counterclockwise and the rotary idler gear 2 clockwise, the developing device 21 has a wheel train composed of the developing device input gear 3 and the developing roller gear 4 and the rotary idler gear 2. In this wheel train configuration, the driving force generated by the engagement between the rotary idler gear 2 and the developing device input gear 3 causes the developing device 21 to move radially outside the rotary developing device 1, that is, in the center direction of the photosensitive member 23. Rotation direction toward
[0015]
Accordingly, the driving reaction force is applied in the direction in which the developing roller 22 of the developing device 21 is pressed against the photosensitive member 23, and further, the developing roller 22 is fixed to the rotary frame 6 from the rear surface of the developing device 21 by the developing device biasing spring 17. Is pressed against the photosensitive member 23 and the developing device 21 is oscillated. With respect to the swinging urging force of the developing device 21, the fitting back stopper elastic member 18 has a rotating shaft of the rotary developing device 1 in the vicinity of the fitting positioning portion between the positioning pin 16 and the positioning hole 19 of the developing device 21. Is arranged as a one-sided member that moves in a direction x orthogonal to a line φ connecting the rotation axis of the photosensitive member 23. In particular, if the direction of the force that is biased by the fitting backlash elastic member 18 is directed toward the center of the swinging fulcrum, no component force acts on the swinging of the developing device 21, so that the stable developing roller 22 and The applied pressure of the photoconductor 23 can be maintained.
[0016]
FIG. 3 is a view showing another embodiment in which a squeezing member is provided as a fitting backlash elastic member, and FIG. 4 is another embodiment in which a fitting backfilling member is provided as a fitting backlash elastic member. FIG.
[0017]
In the above-described embodiment, the fitting backlash elastic member 18 is constituted by a one-sided member that fixes the plate spring to the rotary frame 6 and moves the developing device 21 in one direction. 16 or the positioning hole 19 of the developing device 21 may be fixed with a leaf spring so that the developing device 21 is similarly moved in one direction. FIG. 3 shows an embodiment thereof. . That is, as shown in FIG. 3A, the positioning hole 19 of the developing unit 21 is shaved to secure a space 19a for mounting the leaf spring 18 ', and the positioning pin 16 is fixed to the predetermined position by the leaf spring 18' fixed thereto. You may make it approach to a direction. On the contrary, the positioning pin 16 may be shaved to form a surface on which the leaf spring 18 ″ is attached, and the positioning pin 16 may be moved in a predetermined direction by the leaf spring 18 ″ fixed thereto.
[0018]
In addition, a fitting backfilling member can be provided as a fitting backlash elastic member in the fitting positioning portion where the fitting backlash exists, and FIG. 4 shows an embodiment thereof. That is, an annular groove is provided in the positioning pin 16 as shown in FIG. 4, and the annular elastic member 20 is fitted and fixed in the groove, and the developing device 21 is inserted into the rotary developing device 1 from below as shown in FIG. As shown in FIG. 4B, the positioning hole 19 of the developing device 21 may be fitted to the positioning pin 16 in which the annular elastic member 20 is fitted and fixed.
[0019]
According to the present embodiment, an elastic body is applied to restrict movement such as vibration of the developing device 21 due to a fitting play between the swing fulcrum shaft 16 of the developing device 21 and the positioning hole 19 of the developing device 21. Therefore, the vibration generated during the development driving is not propagated from the rotary frame 6 to the developing device 21, and it is possible to prevent the occurrence of a problem that the developing device 21 itself is violently or resonates. Defects can be eliminated.
[0020]
FIG. 5 is a diagram showing a state in which the developing device is mounted on the rotary developing device, FIG. 6 is a diagram showing an enlarged detail of the developing device cover, and FIG. 7 is a member that realizes positioning and swinging of the developing device in the rotary developing device It is a figure which shows the meshing state of a structure, a rotary idler gear, and a drive output gear. In the figure, 11 is a developing device cover, 12 is a developing device swinging fulcrum, 13 and 16 are developing device positioning pins, 14 and 15 are developing device positioning holes, and 17 is a developing device biasing spring.
[0021]
FIG. 5 shows a state in which the developing device 21 of only one of the four colors is mounted on the rotary developing device 1, and FIG. 6 is an enlarged detailed view of the periphery of the developing device cover 11. The developing device cover 11 has protrusions at two locations on the opposite side of the developing device positioning pin 13 and the developing roller 22, and engages with the developing device positioning hole 14 provided on the end face of the rotary frame 6 facing these. It is like that. The developing device swinging fulcrum 12 is at a portion facing the rotation shaft of the rotary idler gear 2. On the opposite side of the developing device swinging fulcrum 12, a rotary idler gear 2 is provided on the rotary frame 6 so as to show the inside of the rotary developing device 1 from which the developing device 21 is removed. A developing device positioning pin 16 is provided on the rotating shaft, and a developing device positioning hole (not shown) of the developing device 21 is fitted into the rotating shaft to swing the developing device 21 between the developing device swinging fulcrum 12. I try to move it. Further, as shown in FIG. 7, the rotary frame 6 in the rotary developing device 1 is provided with a developing device biasing spring 17 for biasing the developing device 21 toward the photosensitive member.
[0022]
As described above, the developer positioning holes 14 and 15 shown in FIG. 7 are fitted with the developer positioning pin 13 of the developer cover 11 and another developer positioning pin (not shown) shown in FIG. The developing device 21 is positioned by fitting with a developing device positioning hole (not shown) of the developing device 21. On the other hand, the developing device swinging fulcrum 12 and the developing device positioning pin 16 swing. Then, the rotary idler gear 2 meshes with the drive output gear 8 as shown in FIG. 7 and is driven by the drive motor 7.
[0023]
Therefore, the developing device 21 can be positioned with high accuracy in a swingable manner on the rotary developing device 1 by the positioning mechanism. In addition, the engagement and disengagement of the train wheel during the attachment / detachment is performed between the rotary idler gear 2 disposed on the rotary frame 6 and the developing device input gear 3, and at the tip of the rotary shaft of the rotary idler gear 2. Since positioning is performed using the provided developer positioning pins 16, play and backlash can be reduced, and engagement and disengagement can be performed smoothly. When the rotary developing device 1 is rotated so that the developing device 21 corresponding to the color of the developing process is located at the developing position, the drive output gear 8 is a rotary idler gear disposed on the rotary frame 6 of the rotary developing device 1. 2 is engaged.
[0024]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 8 is a diagram showing an embodiment of an image forming apparatus according to the present invention, in which 34 is an intermediate transfer medium, 35 is an exposure device, 36 is a process unit, 37 is a primary transfer device, and 38 is a secondary transfer device. A transfer device, 39 is a paper feed tray, 40 is a paper feed roller, 41 is a registration roller, 42 is a paper transport unit, 43 is a fixing unit, 44 is a paper discharge tray, and 45 is a door.
[0025]
As shown in FIG. 8, the image forming apparatus of the present embodiment includes a paper discharge tray 44 formed at the top of the housing, and a door body 45 that can be opened and closed on the front surface of the housing. In the housing, a rotary developing device 1 equipped with a plurality of developing devices, a photosensitive member 23 on which an electrostatic latent image is formed and developed to form a toner image, and the photosensitive member 23 is exposed to form an electrostatic latent image. An exposure device 35, an intermediate transfer medium 34 comprising an endless belt to which a toner image is transferred, a process unit 36 for controlling the formation of an electrostatic latent image by the exposure device 35, and a toner image on the photoconductor 23 as an intermediate transfer medium. A primary transfer device 37 for primary transfer to 34, a secondary transfer device 38 for secondary transfer of the toner image of the intermediate transfer medium 34 to a recording medium (such as paper), a paper feed tray 39 for accommodating the recording medium, and a recording medium A fixing unit 43 for fixing the toner image, a control unit for controlling each drive motor and bias, and the like are provided. Further, a paper transport unit 42 for transporting a recording medium from the paper feed tray 39 to the fixing unit 43 through the secondary transfer device 38 is disposed in the door body 45. Each unit is configured to be detachable from the main body, and can be removed and repaired or replaced integrally during maintenance or the like.
[0026]
The photoreceptor 23 as an image carrier has a thin cylindrical conductive substrate and a photosensitive layer formed on the surface thereof. On the outer periphery of the photoconductor 23, a charging device (not shown) for uniformly charging the photoconductor 23 along the rotation direction, and an exposure device 35 for forming an electrostatic latent image on the photoconductor 23. A rotary developing device 1 for developing the electrostatic latent image, an intermediate transfer medium 34 to which the toner image on the photosensitive member 23 is transferred, and a primary transfer device 37 for primary transfer of the toner image to the intermediate transfer medium 34, A cleaner (not shown) for cleaning the surface of the photoconductor 23 after the primary transfer is disposed. Then, the electrostatic latent image formed on the photosensitive member 23 by the exposure device 35 is developed by the rotary developing device 1 to form a toner image, and the formed toner image is formed on the intermediate transfer medium 34 by the primary transfer device 37. Then, the image is further transferred to a recording medium (paper or the like) by the secondary transfer device 38.
[0027]
In the image forming apparatus configured as described above, when an image forming signal is input from the process unit 36 to the exposure device 35, the photosensitive member 23, the developing roller of the rotary developing device 1, The intermediate transfer medium 34 is rotationally driven, and first, the outer peripheral surface of the photoconductor 23 is uniformly charged by a charging device. Thereafter, in the four-color full color with N = 4, the exposure device 35 selectively exposes the surface of the photoreceptor 23 in accordance with image information of the first color, for example, yellow Y, and the yellow Y electrostatic latent image. Is formed. At this time, the rotary developing device 1 rotates and moves so that the developing roller of the developing device 21 for yellow comes into contact with the photosensitive member 23. As a result, a yellow Y electrostatic latent image toner image is formed on the photoreceptor 23.
[0028]
Thereafter, a primary transfer voltage having a polarity opposite to the toner charging polarity is applied to the primary transfer device 37, and the toner image formed on the photoreceptor 23 is transferred onto the intermediate transfer medium 34. During this time, the secondary transfer device 38 is separated from the intermediate transfer medium 34. This series of processing is repeatedly executed corresponding to the second color, the third color, and the fourth color of the image formation signal, so that yellow Y, black K, cyan C, Four color (N = 4) toner images of magenta M are sequentially superimposed and transferred from the photoconductor 23 onto the intermediate transfer medium 34 to form a full color image.
[0029]
Then, at the timing when the full color image reaches the secondary transfer device 38, the recording medium (paper or the like) on the paper feed tray 9 is conveyed from the conveyance path to the secondary transfer device 38 through the paper feed roller 40 and the registration roller 41. The apparatus 38 is pressed against the intermediate transfer medium 34 and a secondary transfer voltage is applied, and the four color full-color toner images on the intermediate transfer medium 34 are transferred onto the recording medium by the secondary transfer apparatus 38. When the recording medium to which the full color toner image is transferred in this manner is conveyed to the fixing unit 43 by the paper conveying unit 42, the full color toner image on the recording medium is heated and pressed by the fixing unit 43 and fixed, and discharged. The paper is discharged to the tray 44.
[0030]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the elastic member is disposed between the positioning pin and the wall surface of the positioning hole, and the annular elastic member is fixed to the positioning pin. However, the annular elastic member is fixed to the wall surface of the positioning hole. May be. Since the developing device is replaced with a fixed life with respect to the rotating body composed of the rotary frame, when the annular elastic member is fixed on the positioning pin side, a longer life is required than the developing device, and at the time of deterioration Maintenance such as replacement is also required, but when an annular elastic member is fixed on the developing device side, the life of the developing device may be equal and maintenance-free. In addition, a positioning hole is provided on the developer side, and it is fitted to a positioning pin provided on the rotary frame side and the rotation center shaft of the rotary idler gear. On the contrary, a positioning pin is provided on the developer side and provided on the rotary frame side. Positioning holes may be provided to fit these.
[0031]
【The invention's effect】
As is apparent from the above description, according to the present invention, a rotating body comprising a rotary frame and a plurality of developing devices detachably mounted along the outer periphery of the cylinder of the rotating body are provided and selectively developed. In a rotary developing device for developing a latent image on a photosensitive member by rotating the developing device to a developing position facing the photosensitive member, or in an image forming apparatus equipped with the rotary developing device, the rotating member and the developing device are connected to positioning pins and positioning holes. Positioning means for positioning by fitting, swinging biasing means for swinging and biasing the developing device toward the photosensitive member with the positioning pin as a swinging fulcrum, and a piece for bringing the swinging fulcrum of the developer toward one of the positioning holes Since the shifting means is provided, it is possible to eliminate the fitting backlash between the positioning pin at the swinging fulcrum that supports the developing device so as to be swingable and the positioning hole that is the fitting hole, and a drive source generated during development driving From Due to the vibration, or failure to resonate or rage developing device itself occurs, it is possible to make the image defects such as banding does or occur.
[0032]
The biasing means is provided in the vicinity of the positioning means, and is offset in the direction perpendicular to the line connecting the rotating shaft of the rotating body and the rotating shaft of the photosensitive member, in the direction of the positioning pin of the positioning means. It is an elastic member that is provided between and biased in the side-shift direction, or is an elastic member that is provided between the positioning pin and the positioning hole and biases in the side-shift direction. Therefore, it is possible to maintain a stable pressure applied to the developing roller and the photosensitive member.
[0033]
The positioning pin of the positioning means is provided at the rotation center axis of the idler gear on the rotating body that meshes with the drive output gear at the development position, and the positioning hole is provided at a position where it fits with the positioning pin of the developing device. At this time, an idler gear that meshes with the developing device input gear on the developing device side is provided in the positioning portion, and the gear can be smoothly meshed and introduced by reducing positional deviation and vibration.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an embodiment of a rotary developing device according to the present invention.
FIG. 2 is a diagram illustrating a driving wheel train of the developing device and a swinging biasing mechanism of the developing device.
FIG. 3 is a view showing another embodiment in which a squeezing member is disposed as a fitting backlash elastic member.
FIG. 4 is a view showing another embodiment in which a fitting back-filling member is provided as a fitting back-stop elastic member.
FIG. 5 is a diagram illustrating a state in which the developing device is mounted on a rotary developing device.
FIG. 6 is a diagram illustrating an enlarged detail of a developing device cover portion.
FIG. 7 is a diagram illustrating a member and a structure for realizing positioning and swinging of a developing device in a rotary developing device, and a state in which a rotary idler gear and a drive output gear are meshed with each other.
FIG. 8 is a diagram showing an embodiment of an image forming apparatus equipped with a rotary developing device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotary developing device, 2 ... Rotary idler gear, 3 ... Developing device input gear, 4 ... Developing roller gear, 6 ... Rotary frame, 16 ... Positioning pin, 18 ... Engaging backlash elastic member, 19 ... Positioning hole, 21 ... Developer, 22 ... Developer roller

Claims (8)

A rotating body comprising a rotary frame, and a plurality of developing devices detachably mounted along the outer periphery of the rotating body, and selectively rotating the developing device to a developing position facing the photosensitive member. In the rotary developing device for developing a latent image on the photosensitive member, positioning means for positioning the rotating member and the developing device by fitting a positioning pin and a positioning hole, and the developing device using the positioning pin as a swing fulcrum A rotary developing device comprising: a swinging biasing unit that swings and biases the photosensitive member toward the photosensitive member; and a biasing unit that shifts the swinging fulcrum of the developing unit toward one of the positioning holes. 2. The rotary developing device according to claim 1, wherein the biasing means is provided in the vicinity of the positioning means. 3. The rotary developing device according to claim 1, wherein the biasing unit is biased in a direction perpendicular to a line connecting a rotation axis of the rotating body and a rotation axis of the photosensitive member. 4. The rotary developing device according to claim 1, wherein the biasing unit is biased in a direction of a positioning pin of the positioning unit. 5. 4. The rotary developing device according to claim 1, wherein the biasing unit is an elastic member that is provided between the rotating body and the developing device and biases in the biasing direction. 5. . 4. The rotary developing device according to claim 1, wherein the biasing unit is an elastic member that is provided between the positioning pin and the positioning hole and biases in the biasing direction. 5. A positioning pin of the positioning means is provided at a rotation center axis of the idler gear on the rotating body side that meshes with a drive output gear at the development position, and the positioning hole is provided at a position to be fitted with the positioning pin of the developing device. The rotary developing device according to claim 1, wherein An image forming apparatus comprising the rotary developing device according to claim 1.

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