JP2012173637A - Image forming apparatus and developing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause a plurality of rotating developing parts to stop at a predetermined position of an image forming apparatus main body when installing the replaceable developing apparatus having the plurality of developing parts that rotate with a shaft as a center, on an image forming apparatus main body.SOLUTION: An image forming apparatus includes: an image forming apparatus main body; a plurality of developing devices that are detachably provided for the image forming apparatus main body and rotatably provided with a rotating shaft 14A as a center; a lock member 260 that is provided on the image forming apparatus main body side; and a rotating disk 220 that is provided on a plurality of developing device sides, causes rotation of the plurality of rotating developing devices to stop by being engaged with the lock member 260, and disposes any one of the developing devices on a predetermined position for the image forming apparatus main body.

Description

  The present invention relates to an image forming apparatus and a developing device.

As a prior art described in the publication, a plurality of process cartridges in which a developing unit and a developer container are integrated and removable from the main body of the image forming apparatus are provided, the plurality of process cartridges are supported, and the electrostatic latent image In a color image forming apparatus having a rotary type developing device that performs development by sequentially rotating and moving each process cartridge to a position where the electrostatic latent image on the electrostatic latent image carrier is developed facing the carrier. A brake unit (brake mechanism) that applies a brake to a rotating body that supports a plurality of process cartridges when the process cartridge is attached / detached, a gear provided on a side plate of the rotating body to rotate the rotating body, and the gear A gear train for driving and a brake gear that is elastically pressed against and separated from one gear of the gear train. Color image forming apparatus is present to (Patent Document 1).
In addition, as a prior art described in the publication, in conjunction with a rotation operation in the mounting direction of the handle member in a state where the photosensitive member receiving direction tip of the photosensitive unit constituting the process cartridge is placed on the photosensitive unit receiving part, Then, the sliding member slides on the support plate, and thereby the positioning pin penetrating into the positioning hole provided in the main body housing is fixed to the support plate, and the photosensitive unit and the intermediate transfer member are fixed to the main body housing. There is an image forming apparatus that positions a photoreceptor unit with respect to an intermediate transfer body unit at the same time as positioning with respect to a body (Patent Document 2).

JP 2003-15502 A JP-A-2005-37634

  According to the present invention, when a replaceable developing device having a plurality of developing units that rotate about a shaft portion is mounted on an image forming apparatus main body, the plurality of developing units that rotate are predetermined in the image forming apparatus main body. The purpose is to stop at a certain position.

According to a first aspect of the present invention, there is provided an image forming apparatus main body, a plurality of developing units provided detachably with respect to the image forming apparatus main body, and provided rotatably about a shaft portion, and the image forming apparatus main body. A regulating portion provided on the side, and provided on the plurality of developing portions side, and stops rotation of the plurality of developing portions rotating by engaging with the regulating portion, and develops any one of the plurality of developing portions An image forming apparatus comprising: a restricted portion arranged at a predetermined position with respect to the image forming apparatus main body.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the plurality of developing units are detachably provided to the main body of the image forming apparatus, with the plurality of developing units integrated. is there.
According to a third aspect of the present invention, the main body of the image forming apparatus includes an image holding body that is rotatably arranged and holds an image on an outer peripheral surface, and the restricting portion is a developing portion of any of the plurality of developing portions. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed at a predetermined position with respect to the image holding member provided in the image forming apparatus main body.

According to a fourth aspect of the present invention, the plurality of developing units are provided in the plurality of developing units, elastically deformed in response to receiving a driving force from the image forming apparatus main body, and the elastic deformation is restored. The image forming apparatus according to claim 1, further comprising a rotating unit that rotates the image forming unit.
According to a fifth aspect of the present invention, in the main body of the image forming apparatus, the plurality of developing units include a driving source that supplies a driving force that rotates about the shaft portion. An image forming apparatus.
According to the sixth aspect of the present invention, there are provided a plurality of developing units provided detachably with respect to the main body of the image forming apparatus and rotatably provided about the shaft portion, and a regulating section provided on the image forming apparatus main body side. A restricted portion that stops rotation of the plurality of developing portions that rotate, and places any one of the plurality of developing portions at a predetermined position with respect to the image forming apparatus main body. Is a developing device.

According to the first aspect of the present invention, when the replaceable developing device having a plurality of developing units rotating around the shaft portion is mounted on the image forming apparatus main body, the plurality of rotating developing units are formed as images. The apparatus main body can be stopped at a predetermined position.
According to the second aspect of the present invention, it is possible to more easily position the plurality of developing units with respect to the image forming apparatus main body than in the case where the present configuration is not provided.
According to the third aspect of the present invention, it is possible to suppress the image quality defect of the image developed by the developing unit as compared with the case where this configuration is not provided.

According to the fourth aspect of the present invention, it is possible to rotate the plurality of developing units with a simpler configuration than in the case where the present configuration is not provided.
According to the fifth aspect of the present invention, it is possible to configure a plurality of developing units with a simpler configuration as compared with the case where the present configuration is not provided.
According to the sixth aspect of the present invention, when the replaceable developing device having a plurality of developing units that rotate about the shaft portion is mounted on the image forming apparatus main body, the plurality of rotating developing units are formed as images. The apparatus main body can be stopped at a predetermined position.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. FIG. 2 is a schematic configuration diagram of a drive system around a developing device. It is a perspective view of a developing device. It is a disassembled perspective view of a transmission mechanism. It is a schematic block diagram of a rear plate. It is a disassembled perspective view of a position plate. It is a schematic block diagram of a rotation disc. It is a schematic block diagram of a raising member. It is a schematic block diagram of a torsion spring. It is a schematic block diagram of a gear plate. It is a schematic block diagram of a locking member. It is a schematic block diagram of a transmission mechanism. 6 is a timing chart illustrating a transmission mechanism switching operation in a four-color image forming operation. It is a schematic block diagram of the transmission mechanism in a 2nd state. It is a schematic block diagram of the transmission mechanism in a 3rd state. It is a schematic block diagram of the transmission mechanism in a 4th state. It is a schematic block diagram of the transmission mechanism in a 5th state. It is a schematic block diagram of the transmission mechanism in a 6th state. 3 is an exploded perspective view of a transmission mechanism 200. FIG. 3 is a front view of a transmission mechanism 200. FIG. It is a figure explaining operation | movement of the transmission mechanism. It is a figure explaining operation | movement of the transmission mechanism.

Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings.
<Overall Configuration of Image Forming Apparatus 1>
First, each configuration of the image forming apparatus 1 to which the exemplary embodiment is applied will be described with reference to FIG. Here, FIG. 1 is a schematic configuration diagram showing an image forming apparatus 1 to which the exemplary embodiment is applied.

  The image forming apparatus 1 includes an image forming unit 10 on which a toner image is formed, a paper supply unit 40 that supplies and conveys paper S, and the image forming unit 10 that holds and holds the supplied paper S. And a transfer device 20 for transferring the toner image. The image forming apparatus 1 also includes a fixing device 30 that fixes the toner image on the paper S released from the transfer device 20 and a control unit 50 that controls the entire image forming device 1. Here, each component of the image forming apparatus 1 is accommodated in the housing 2, and a paper discharge stacking unit 3 on which the paper S discharged from the fixing device 30 is stacked is provided on the top of the housing 2. ing.

<Configuration of each member>
First, the image forming unit 10 includes a photosensitive drum 11. Further, the image forming unit 10 includes a charging device 12 that charges the photosensitive drum 11, an exposure device 13 that exposes the charged photosensitive drum 11, a developing device 14 that performs development using a developer, and the photosensitive drum 11. A cleaning device 15 for cleaning the developer remaining in the printer is included. Each member will be described below.

  A photosensitive drum 11, which is an example of an image carrier, includes a photosensitive layer 11 </ b> A having a negative charging polarity on its surface and is attached so as to rotate in the direction of arrow A. The charging device 12, the exposure device 13, the developing device 14, and the cleaning device 15 are installed around the photosensitive drum 11 in this order along the direction of the arrow A. Here, the outer diameter of the photosensitive drum 11 is, for example, 30 mm.

The charging device 12 is a contact roller type discharging device in the present embodiment, and is configured to charge the photosensitive drum 11 while rotating together with the photosensitive drum 11.
The exposure device 13 is configured to form an electrostatic latent image by irradiating the charged surface of the photosensitive drum 11, and includes a plurality of LEDs (not shown) arranged in the present embodiment.

The developing device 14 is detachably attached to the housing 2. Further, the developing device 14 includes a so-called rotary developing device 14R. Although details will be described later, the rotary developing unit 14R includes a rotating shaft (shaft portion) 14A and yellow (Y), magenta (M), cyan (C), and black (K) installed around the rotating shaft 14A. Development units (development units) 14Y, 14M, 14C, and 14K, which rotate in the direction of arrow C about the rotation shaft 14A.
Further, in the rotary developing device 14R, any one of the developing devices 14Y, 14M, 14C, and 14K is stopped at a position (developing position) facing the photosensitive drum 11.
When only a single color image is formed instead of a multicolor image, the developing device 14 may be replaced with a developing device having only a single color developing device (for example, only the black (K) developing device 14K).

The developing device 14 develops the electrostatic latent image formed on the photosensitive drum 11 by the exposure device 13 using toner. The outer diameter of the developing device 14 is 100 mm, for example.
These developing units 14Y, 14M, 14C, and 14K contain a one-component developer made of only toner. Here, in the present embodiment, a one-component developer is used, but a two-component developer including a toner and a carrier may be used.

  The cleaning device 15 removes the developer remaining on the surface of the photosensitive drum 11 and the deposits other than the developer. The cleaning device 15 of the present embodiment is a blade type cleaner.

Next, the transfer device 20 will be described. The transfer device 20 includes a transfer drum 21 that transfers the toner image on the photosensitive drum 11 onto the paper S. The transfer device 20 also includes a leading edge gripper 23 that holds the leading edge of the paper S on the transfer drum 21, and a trailing edge gripper 27 that holds the trailing edge of the paper S on the transfer drum 21. Further, the transfer device 20 includes a paper detection sensor 25 that detects the passage of the paper S.
The transfer device 20 is detachably attached to the housing 2. Here, the transfer device 20 according to the present embodiment is configured to fix the leading end and the trailing end of the paper S and rotate around the transfer drum 21, but is not limited thereto. For example, when only a single color image is formed instead of a multicolor image, the transfer drum 21 may be replaced with a roll that applies a transfer bias without fixing the paper S (so-called transfer roll).

  The transfer drum 21 is disposed so as to face the photosensitive drum 11 and to be rotatable about a rotation shaft 21D. The transfer drum 21 includes a drum-shaped base 21A and an elastic layer 21B formed on the outer peripheral surface of the base 21A. More specifically, the elastic layer 21B extends along the outer periphery of the drum-shaped base 21A from the elastic layer front end 21BL that is the front end of the paper S in the transport direction to the elastic layer rear end 21BT that is the rear end of the paper S in the transport direction. Stretched. On the other hand, the elastic layer 21B does not cover a part of the outer peripheral surface of the base portion 21A along the axial direction of the base portion 21A (between the elastic layer rear end 21BT and the elastic layer front end 21BL). The part is an exposed portion 21C where the base portion 21A is exposed.

The transfer drum 21 is provided to rotate in the direction of arrow B in synchronization with the rotation of the photosensitive drum 11 in a state where the elastic layer 21B is elastically deformed to form a nip portion with the photosensitive drum 11. Further, the exposed portion 21 </ b> C of the transfer drum 21 is not in contact with the photosensitive drum 11. Further, the outer diameter of the transfer drum 21 is larger than the outer diameter of the photosensitive drum 11.
The base 21A is applied with a transfer bias composed of a voltage having a polarity opposite to that of the toner from a high voltage power source (not shown). The toner constituting the toner image on the photosensitive drum 11 is transferred to the paper S on the elastic layer 21B at the transfer portion Tr.

The paper detection sensor 25 is disposed to face the outer peripheral surface of the transfer drum 21 and detects the passage of the paper S that is wound around the transfer drum 21 and conveyed. Further, the paper detection sensor 25 measures the phase of the rotating transfer drum 21 by detecting a mark (not shown) provided on the transfer drum 21.
The fixing device 30 includes a heating roll 31 having a heating source (not shown) and rotatably arranged, and a pressure roll 32 pressed against the heating roll 31.

  The paper supply unit 40 includes a paper storage unit 41 that is provided below the transfer drum 21 and stores the paper S therein, and a paper size sensor (not shown) that is provided in the take-out roll 42 and detects the size of the stored paper. Prepare. Further, the paper supply unit 40 includes a take-out roll 42 that takes out the paper S from the paper storage unit 41, a separating roll 43 that separates the closely contacted paper S, and a transport roll 44 that transports the paper S.

  The control unit 50 receives a signal from a user interface (not shown) that receives an instruction from the user. In addition, an image signal is input to the control unit 50 from an image output instruction unit (not shown) provided inside or outside the image forming apparatus 1. Further, the control unit 50 is supplied with a paper S passing signal and a phase signal of the photosensitive drum 11 sent from the paper detection sensor 25.

And the control part 50 outputs a control signal to each following part. That is, the control unit 50 outputs a control signal to the photosensitive member driving unit (the photosensitive drum driving motor M2 and the photosensitive drum gear G2 in FIG. 2), the charging device 12, and the exposure device 13 that rotationally drives the photosensitive drum 11. To do. In addition, the control unit 50 is connected to a developing bias setting unit (not shown) that sets a developing bias to be supplied to the developing devices 14Y, 14M, 14C, and 14K disposed at the developing position that is the position facing the photosensitive drum 11. Output a control signal.
Further, the control unit 50 outputs a control signal to a transfer drum drive unit (see transfer drum drive motor M1 and transfer drum gear G1 in FIG. 2) that rotationally drives the transfer drum 21. Furthermore, a rear end gripper driving unit (not shown) for rotationally driving the rear end gripper 27, a transfer bias setting unit (not shown) for setting a transfer bias to be supplied to the transfer drum 21, a front end gripper 23, a rear end gripper 27, a control signal is output to the paper supply unit 40 and the fixing device 30.

Here, the image forming apparatus 1 includes a supply path 51 for supplying the sheet S from the sheet storage unit 41 to the transfer portion Tr. Further, the image forming apparatus 1 includes a discharge path 52 for discharging the paper S on which the toner image is transferred via the fixing device 30 to the paper discharge stacking unit 3.
Further, in the present embodiment, the sheet S supplied toward the transfer drum 21 rotates in a state where it is wound around the transfer drum 21 by the leading edge gripper 23 and the trailing edge gripper 27. At this time, a path through which the sheet S passes is referred to as a rotation path 53.

<Drive system>
Now, with reference to FIG. 2, a drive system such as the developing device 14 will be described. Here, FIG. 2 is a schematic configuration diagram of a drive system around the developing device 14.
First, the developing device 14 in the present embodiment does not have a dedicated drive motor for driving the developing device 14. The developing device 14 in the present embodiment is driven by a transfer drum drive motor (drive source) M1 that drives the transfer drum 21 and a photoconductor drum drive motor M2 that rotates the photoconductor drum 11. This configuration will be described in detail below.

As shown in FIG. 2, the transfer device 20 includes a transfer drum drive motor M <b> 1 that drives the transfer drum 21. The transfer device 20 is provided integrally with the rotation shaft 21D of the transfer device 20, and has a transfer drum gear G1 that rotates the rotation shaft 21D under the drive of the transfer drum drive motor M1.
The photoconductor drum 11 has a photoconductor drum drive motor M <b> 2 that drives the photoconductor drum 11. The photoconductor drum 11 is coaxial with the photoconductor drum 11 and is provided integrally with the photoconductor drum 11, and is a photoconductor drum gear that rotates the photoconductor drum 11 by being driven by the photoconductor drum drive motor M2. G2.

  On the other hand, the developing device 14 is provided integrally with the rotating shaft 14A and has a developing device gear G3 that rotates the rotary developing device 14R. The developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided in the rotary developing device 14R rotate and drive the developing rolls and the like provided in the developing devices 14Y, 14M, 14C, and 14K, respectively. Developer gears G4Y, G4M, G4C, and G4K are provided.

  Here, the developing device gear G3 that rotates the rotary developing device 14R about the rotating shaft 14A is configured to rotate by receiving the driving of the transfer drum driving motor M1 via the intermediate gears G5 and G6. Further, the developing device gears G4Y, G4M, G4C, and G4K that rotate the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) are disposed at positions facing the photosensitive drum 11 when performing development. The photosensitive drum drive motor M2 is driven via the photosensitive drum gear G2 to rotate.

<Developing device 14>
Next, the detailed structure of the developing device 14 will be described with reference to FIGS. 1, 2, and 3. Here, FIG. 3 is a perspective view of the developing device 14.
First, the developing device 14 includes the rotary developing device 14R, the developing device gear G3, and the gears G4Y, G4M, G4C, and G4K (see FIG. 2) as described above. Further, the developing device 14 includes a frame body 90 that rotatably supports the rotary developing device 14R. Furthermore, the developing device 14 includes a transmission mechanism 100 that transmits the driving of the transfer drum driving motor M1 to the rotary developing device 14R and cuts off the transmission of the driving.

The rotary developing device 14R includes a rotating shaft 14A and yellow (Y), magenta (M), cyan (C), and black (K) developing devices 14Y, 14M, 14C, and 14K (around the rotating shaft 14A). 1). The rotary developing unit 14R includes a developing rack 80 that is fixedly attached to the rotating shaft 14A, holds the developing units 14Y, 14M, 14C, and 14K, and rotates integrally with the rotary developing unit 14R. In the rotary developing device 14R, the developing devices 14Y, 14M, 14C, and 14K rotate in the direction of arrow C around the rotation shaft 14A.
Here, as shown in FIG. 3, the developing rack 80 includes holding plates 61 and 63 that hold the developing devices 14Y, 14M, 14C, and 14K from outside in the longitudinal direction, and holding plates 61 and 63. And a reinforcing member (not shown) for connecting and reinforcing the gaps.

  The frame 90 has a front plate 91 and a rear plate that hold the developing rack 80 that holds the developing units 14Y, 14M, 14C, and 14K so as to be sandwiched from the outside in the longitudinal direction of the developing units 14Y, 14M, 14C, and 14K. 93 and a bottom plate 95 that connects the front plate 91 and the rear plate 93. Although the developing device 14 is detachable from the housing 2 as described above, here, for convenience, the state where the developing device 14 is mounted on the housing 2 is used as a reference, and the image forming apparatus 1 in FIG. The configuration will be described using the expressions “front” and “rear” in association with the front side (the side disposed on the front side in FIG. 1) and the rear side (the side disposed on the back side in FIG. 1). .

The developing device 14 is fixed in the image forming apparatus 1 by the frame 90. In the present embodiment, the frame 90 has an attachment / detachment mechanism for fixing the developing device 14 to the image forming apparatus 1 so that the removal is easy. Although not described above, the image forming apparatus 1 also has an attachment / detachment mechanism for fixing the developing device 14. Each of these attachment / detachment mechanisms is configured, for example, by providing a hook and a pin (not shown) provided on the image forming apparatus 1 side and a bottom plate 95 for receiving the hook and the pin on the developing apparatus 14 side. .
The configuration of the transmission mechanism 100 will be described later.

Here, as shown in FIGS. 1 and 3, the developing units 14Y, 14M, 14C, and 14K are provided such that the rotation center axes of the developing units 14Y, 14M, 14C, and 14K are along the rotation axis 14A. Yes. The developing units 14Y, 14M, 14C, and 14K are provided around the rotating shaft 14A in this order.
The developing rack 80 is fixed with respect to the rotating shaft 14A, and is provided rotatably with the rotating shaft 14A and the developing devices 14Y, 14M, 14C, and 14K.
In addition, the frame body 90 rotatably supports the rotating shaft 14 </ b> A and is fixed to the housing 2 of the image forming apparatus 1. Here, in the frame 90, the front plate 91 is the front side of the image forming apparatus 1 (the left front side in FIG. 3), and the rear plate 93 is the rear side of the image forming apparatus 1 (the right rear side in FIG. 3). Are arranged respectively.

<Transmission mechanism 100>
Next, the transmission mechanism 100 will be described with reference to FIGS. Here, FIG. 4 is an exploded perspective view of the transmission mechanism 100.
As shown in FIG. 3, the transmission mechanism 100 is provided on one side of the developing device 14 (on the right back side in FIG. 3). Specifically, the transmission mechanism 100 is disposed between the holding plate 63 of the developing rack 80 and the rear plate 93 of the frame body 90. Moreover, the transmission mechanism 100 is provided so that the rotating shaft 14A may penetrate the center part.

  Here, the transmission mechanism 100 includes a position plate 110 that rotates integrally with the rotating shaft 14A and arranges the developing devices 14Y, 14M, 14C, and 14K at predetermined positions. Further, the transmission mechanism 100 is rotated by receiving the drive of the transfer drum driving motor M1 via the intermediate gears G5 and G6 (see FIG. 2), and is engaged with the position plate 110 to rotate the position plate 110. Have Furthermore, the transmission mechanism 100 includes a lock member (regulator) 160 that stops the position plate 110 that rotates together with the rotating shaft 14A. Furthermore, the transmission mechanism 100 includes guide ribs 170 that maintain the transmission of the drive of the gear plate 150 to the position plate 110 by engaging with the position plate 110 and cut the transmission of the drive. Each will be described below.

In the present embodiment, the guide rib 170 is provided integrally with the rear plate 93 on the surface 93a of the rear plate 93 that faces the position plate 110. In the following description, the transmission mechanism 100 will be described as a configuration including the rear plate 93.
Further, the developing device gear G3 is provided on the surface of the gear plate 150 opposite to the side facing the position plate 110 (see FIG. 10, described later). In the following description, the transmission mechanism 100 will be described as including a developing device gear G3.

<Rear plate 93>
First, the rear plate 93 will be described with reference to FIG. Here, FIG. 5 is a schematic configuration diagram of the rear plate 93. More specifically, FIG. 5A is a perspective view of the rear plate 93 viewed from the front side of the developing device 14, and FIG. 5B is a front view of the rear plate 93.
The rear plate 93 includes the guide rib 170 as described above. The guide rib 170 protrudes from the surface 93a on the side facing the position plate 110, and extends along the circumferential direction of the rotating shaft 14A. The guide rib 170 has a specific height (described later) in the direction protruding from the surface 93a (the direction along the arrow E direction).

Further, the same number of guide ribs 170 as the developing devices 14Y, 14M, 14C, and 14K provided in the developing device 14 are provided. In the illustrated example, four guide ribs 170 are provided every 90 degrees in the circumferential direction of the rotating shaft 14A (see FIG. 4).
Further, each guide rib 170 has an inclined portion 171 at an end portion in the circumferential direction and at an end portion on the rear end side in the arrow C direction in which the rotary developing device 14R (see FIG. 1) rotates. The inclined portion 171 is inclined with respect to the surface 93 a of the rear plate 93. Here, the hooking portion 173 that is the end opposite to the side where the inclined portion 171 is provided and on which the torsion spring 140 is hung (details will be described later) is not inclined. In the illustrated example, the hanging portion 173 has a surface substantially orthogonal to the surface 93 a of the rear plate 93.
Furthermore, the rear plate 93 has a through hole 94 into which the rotating shaft 14A is inserted at the center of the surface.

<Position plate 110>
Next, the position plate 110 will be described with reference to FIGS. 4 and 6. Here, FIG. 6 is an exploded perspective view of the position plate 110.
As shown in FIG. 4, the position plate 110 has a rotating disk 120 that rotates integrally with the rotating shaft 14A. The position plate 110 includes a push-up member 130 that is provided on the surface of the rotating disk 120 and pushes up a torsion spring 140 (described later) from the surface of the rotating disk 120. Furthermore, the position plate 110 has a torsion spring 140 that is provided on the surface of the rotating disk 120 and receives the drive from the transfer drum drive motor M1 (see FIG. 2) when the posture changes.
In the example shown in FIG. 6, the rotating disk 120, the push-up member 130, and the torsion spring 140 are arranged in this order from the rear side to the front side of the image forming apparatus 1 (see arrow E). Each will be described below.

<Rotating disc 120>
The rotating disk 120 will be described with reference to FIG. Here, FIG. 7 is a schematic configuration diagram of the rotating disk 120. More specifically, FIG. 7A is a perspective view of the rotating disk 120 as viewed from the front side of the developing device 14, and FIG. 7B is a front view of the rotating disk 120.
The rotating disk 120 is a circular metal plate. The rotating disk 120 has a through hole 121 into which the rotating shaft 14A is inserted at the center of the surface. Further, the rotating disk 120 protrudes from the periphery of the through hole 121 on the front side surface (the surface disposed on the front side of the paper in FIG. 1) 120a in the direction along the rotating shaft 14A (see arrow E). The projection 123 is provided.

Furthermore, the rotating disk 120 that is an example of the regulated portion has a protrusion 125 that engages with the lock member 160 (see FIG. 4) on the outer periphery of the rotating disk 120. The protrusion 125 is formed on the outer periphery of the rotating disk 120 so as to extend in a direction away from the center of rotation. In the present embodiment, the same number of protrusions 125 as the developing devices 14Y, 14M, 14C, and 14K provided in the developing device 14 are provided. Further, the same number of protrusions 125 as the above-described guide ribs 170 are provided. In the illustrated example, four protrusions 125 are provided every 90 degrees in the circumferential direction of the rotating shaft 14A.
In the present embodiment, the protrusion 125 is described, but the present invention is not limited to this. Any structure that engages with the lock member 160 (see FIG. 4) may be used. For example, a notch provided on the outer periphery of the rotating disc 120 or a convex portion provided on the surface of the rotating disc 120. Good.

<Push-up member 130>
Next, the push-up member 130 will be described with reference to FIG. Here, FIG. 8 is a schematic configuration diagram of the push-up member 130. More specifically, FIG. 8A is a perspective view of the push-up member 130 as viewed from the front side of the developing device 14, and FIG. 8B is a front view of the push-up member 130.
The push-up member 130 is an arc-shaped plate member provided coaxially with the rotating disk 120. The push-up member 130 has a specific thickness in the direction along the arrow E direction.
The push-up member 130 has a holding surface 130a that is a surface that holds the arm portion 147 (see FIG. 9) of the torsion spring 140 in a state where the arm portion 147 is moved toward the gear plate 150 side. In the illustrated example, the holding surface 130a is a flat surface disposed on the front side of the push-up member 130 (the surface disposed on the front side in FIG. 1). Therefore, the holding surface 130 a has a specific height from the surface of the rotating disk 120.

  In addition, the tip of the push-up member 130 in the rotational direction (see arrow C) is formed with an inclined portion 133 that is inclined toward the rear side. The inclined portion 133 moves the arm portion 147 (see FIG. 9) of the torsion spring 140 that moves in a direction opposite to the arrow C (see FIG. 8) relative to the inclined portion 133 to the surface of the rotating disk 120. Push up from.

<Torsion spring 140>
Next, the torsion spring (torsion spring) 140 will be described with reference to FIG. Here, FIG. 9 is a schematic configuration diagram of the torsion spring 140. More specifically, FIG. 9A is a perspective view of the torsion spring 140 viewed from the front side of the developing device 14, FIG. 9B is a front view of the torsion spring 140, and FIG. 9C is a torsion spring. FIG.
The torsion spring 140, which is an example of the rotating part, is made of a metal wire. The torsion spring 140 has a winding part 145 wound in a circular shape a plurality of times. One end of the torsion spring 140 extends from the winding portion 145 as an arm portion 147, and the other end extends from the winding portion 145 as a fixing portion 149.

Here, the tip of the arm portion 147 is a free end 141 that is not fixed, whereas the tip of the fixed portion 149 is a fixed end 143 that is fixed to the rotating disk 120 (see FIG. 4). is there. In the illustrated example, the fixed end 143 is fixed on the push-up member 130.
As shown in FIG. 9C, when viewed from the side, the arm portion 147 of the torsion spring 140 extends from the winding portion 145 so as to be inclined toward the rotating disc 120 side (upstream side of the arrow E). More specifically, the free end 141 of the torsion spring 140 is on the rotating disc 120 side (upstream side of the arrow E) from the base of the arm portion 147.

  Note that the free end 141 of the torsion spring 140 moves in the circumferential direction around the winding portion 145, so that the torsion spring 140 is opened and narrowed (see the broken line in FIG. 9B). ). Further, as shown by a broken line in FIG. 9B, in a state where the torsion spring 140 is contracted due to the torsional moment, the torsion spring 140 is in a state where elastic energy (biasing force) is accumulated. is there. In other words, energy is stored as the torsion angle of the torsion spring 140.

<Gear plate 150>
Next, the gear plate 150 will be described with reference to FIG. Here, FIG. 10 is a schematic configuration diagram of the gear plate 150. More specifically, FIG. 10A is a perspective view of the gear plate 150 as viewed from the front side of the developing device 14, and FIG. 10B is a perspective view of the gear plate 150 as viewed from the back side of FIG. 10A. FIG. 10C is a front view of the gear plate 150.

The gear plate 150 is a resin disk-shaped member. The gear plate 150 has a through hole 151 into which the rotation shaft 14A is inserted at the center of the surface.
As shown in FIG. 10A, the front side surface (the surface disposed on the front side of the paper in FIG. 1) 150a of the image forming apparatus 1 in the gear plate 150 is fed from the transfer drum drive motor M1 (see FIG. 2). A developing device gear G <b> 3 that rotates by being driven is fixed coaxially with the gear plate 150.
Further, as shown in FIG. 10B, a claw portion 153 protruding from the rear side surface 150b is provided on the rear side surface (the surface disposed on the back side of the paper surface in FIG. 1) 150b of the image forming apparatus 1 in the gear plate 150. Have. Eight claw portions 153 are provided at substantially equal intervals in the circumferential direction of the rotating shaft 14A. Here, the claw portions 153 are provided more than the number of the guide ribs 170 (that is, the number of the protrusions 125). In the present embodiment, the claw portions 153 are provided as many times as the guide ribs 170 (or the protrusions 125).

<Lock member 160>
Next, the lock member 160 will be described with reference to FIG. Here, FIG. 11 is a schematic configuration diagram of the lock member 160.
In the present embodiment, the lock member 160 is supported by the housing 2 (see FIG. 1) so that the support shaft 163 can swing (see arrow F). More specifically, as described above, the developing device 14 is detachably disposed with respect to the image forming apparatus 1. When the developing device 14 is detached from the image forming apparatus 1, the lock member 160 is left on the image forming apparatus 1 side (image forming apparatus main body side).

The lock member 160 is a plate-like metal member. And it has the protrusion receiving part 161 which hooks with the protrusion 125 of the rotating disc 120 in one edge part.
Although not described above, the transfer drum 21 (see FIG. 1) is provided with a cam (not shown) that rotates together with the transfer drum 21. A cam follower (not shown) pushed by a cam (not shown) provided on the transfer drum 21 is opposite to the side where the projection receiving portion 161 of the lock member 160 is provided with the support shaft 163 interposed therebetween. It is provided at the end.

Each time the transfer drum 21 rotates once, a cam (not shown) pushes a cam follower (not shown). As a result, the lock member 160 swings, and the protrusion receiving portion 161 provided at one end of the lock member 160 moves. Then, the protrusion 125 of the rotating disk 120 that engages with the protrusion receiving portion 161 is released.
The configuration for swinging the lock member 160 is not limited to this. For example, it may be configured to be swung by a solenoid, a motor, or the like.

<Structure of transmission mechanism 100>
Next, the structure of the transmission mechanism 100 will be described with reference to FIGS. 4 and 12. Here, FIG. 12 is a schematic configuration diagram of the transmission mechanism 100. More specifically, FIG. 12A is a front view of the transmission mechanism 100, and FIG. 12B is a cross-sectional view of the transmission mechanism 100 as viewed from an arrow XIIB in FIG. 12A and 12B, the developing device gear G3 of the gear plate 150 is omitted. Further, in FIG. 12A, the portion hidden behind the gear plate 150 is also shown by a solid line.

First, the transmission mechanism 100 includes the rear plate 93, the position plate 110, the gear plate 150, and the lock member 160 as described above. Further, the rotary development is performed in the through hole 94 (see FIG. 5) of the rear plate 93, the through hole 121 (see FIG. 7) of the rotating disk 120 in the position plate 110, and the through hole 151 (see FIG. 10) of the gear plate 150. The rotating shaft 14A of the container 14R is inserted.
As shown in FIG. 12B, the rotating disc 120 in the position plate 110 is fixed to the rotating shaft 14A so as to rotate together with the rotating shaft 14A. On the other hand, the rear plate 93 and the gear plate 150 are provided without being fixed to the rotating shaft 14A.

  Here, as shown in FIG. 12A, guide ribs 170 of the rear plate 93 are provided on the outer periphery of the position plate 110. The guide rib 170 is provided at a position where the guide rib 170 does not come into contact with the protrusion 125 provided on the rotating disk 120 and the arm portion 147 of the torsion spring 140 reaches.

As shown in FIG. 12A, the lock member 160 is disposed on the outer periphery of the position plate 110 and between the two guide ribs 170 provided on the rear plate 93. Further, the lock member 160 is disposed such that a cam follower (not shown) of the lock member 160 is positioned on a moving path of a cam (not shown) provided on the transfer drum 21.
The lock member 160 is provided so as to swing around a support shaft 163 (see FIG. 11) (see arrow F in FIG. 11). In other words, as the lock member 160 swings, the protrusion receiving portion 161 of the lock member 160 advances and retreats with respect to the movement path of the protrusion 125 provided on the rotating disk 120. Therefore, depending on the position of the protrusion 125 of the rotating disk 120, the protrusion 125 hits the protrusion receiving portion 161 of the lock member 160 so as to prevent the rotation of the rotating disk 120. The protrusion receiving portion 161 of the lock member 160 is configured to advance and retract with respect to the movement path of the protrusion 125 by moving in the radial direction of the rotating disk 120 or moving in the tangential direction of the rotating disk 120, for example. It may be.

Further, when the protrusion receiving portion 161 of the lock member 160 engages with the protrusion 125 provided on the rotating disk 120, the rotary developer 14R that rotates together with the rotating disk 120 via the rotating shaft 14A also stops. . In the stopped rotary developing unit 14R, any of the developing units 14Y, 14M, 14C, and 14K included in the rotary developing unit 14R is disposed at a developing position that is a position facing the photosensitive drum 11.
Furthermore, while the protrusion receiving portion 161 of the lock member 160 is engaged with the protrusion 125 provided on the rotating disk 120, the protrusion 125 is released, and while the protrusion 125 is again engaged with the protrusion 125, the rotary development is performed. The container 14R rotates 90 degrees.

  When the arm portion 147 of the torsion spring 140 is in contact with the claw portion 153 of the gear plate 150, the drive from the transfer drum drive motor M1 (see FIG. 2) is driven by the torsion spring 140, the rotating disk 120, and the rotation. It is transmitted to the rotary developer 14R via the shaft 14A. When the arm portion 147 of the torsion spring 140 does not contact the claw portion 153 of the gear plate 150, the drive from the transfer drum drive motor M1 (see FIG. 2) is not transmitted to the rotary developer 14R.

  The winding portion 145 of the torsion spring 140 is wound around the convex portion 123 provided on the rotating disc 120 and is provided coaxially with the rotating shaft 14A. The fixed end 143 of the torsion spring 140 is fixed to the push-up member 130 provided on the rotating disk 120 as described above. The free end 141 of the torsion spring 140 extends outward from the movement path of the protrusion 125 provided on the rotating disk 120 with respect to the rotating shaft 14 </ b> A, and can contact the guide rib 170.

  Here, as shown in FIG. 12B, the free end 141 of the torsion spring 140 is on the rotating disk 120 side (upstream side of the arrow E) from the root of the arm portion 147.

<Function of transmission mechanism 100>
Next, the function of the transmission mechanism 100 will be described with reference to FIGS. 1, 12, and 14 to 18. Here, the operation in which the transmission mechanism 100 rotates the rotary developing device 14R by 90 degrees is divided into a first state to a sixth state (details will be described later), and some of them will be described. Here, the function of the transmission mechanism 100 will be described by focusing on the function of the torsion spring 140 and the function of the rotating disk 120. Note that the transmission mechanism 100 shown in FIG. 12 is in the first state. 14 to 18 are schematic configuration diagrams of the transmission mechanism 100 in the second state to the sixth state, respectively.

<Function of torsion spring 140>
The function of the torsion spring 140 in the first state shown in FIG. 12 will be described. Here, the state of the torsion spring 140 and the force acting on the torsion spring 140 will be described separately.
First, the state of the torsion spring 140 will be described.
The torsion spring 140 shown in FIG. 12 is in a state of being squeezed by accumulating elastic energy. In addition, the arm portion 147 of the torsion spring 140 is about to rotate in the direction opposite to the arrow C direction, and the fixed end 143 of the torsion spring 140 is about to rotate in the arrow C direction.
12B, the free end 141 of the torsion spring 140 is at a position where the height from the rear plate 93 in the direction of arrow E is low. This is because the arm portion 147 of the torsion spring 140 extends while being inclined from the winding portion 145 toward the rotating disc 120 side. Further, the arm portion 147 of the torsion spring 140 is not in contact with the claw portion 153 of the gear plate 150 because the arm portion 147 is located at a low height from the rear plate 93.

Next, the force acting on the torsion spring 140 will be described.
As shown in FIG. 12A, the arm portion 147 of the torsion spring 140 receives a force in the arrow C direction from the hook portion 173 of the guide rib 170 in the circumferential direction of the rotating shaft 14A. Further, the arm portion 147 of the torsion spring 140 is not in contact with the claw portion 153 of the gear plate 150, and therefore does not receive a force from the claw portion 153 of the gear plate 150. Further, the fixed end 143 of the torsion spring 140 receives a force in the direction opposite to the arrow C direction from the push-up member 130 in the circumferential direction of the rotating shaft 14A. The force from the push-up member 130 is a reaction force received from the push-up member 130 fixed to the rotating disk 120 that has stopped rotating. As a result, the torsion spring 140 is squeezed and stopped.
On the other hand, as shown in FIG. 12B, the arm portion 147 of the torsion spring 140 does not receive force from the inclined portion 133 and the guide rib 170 of the push-up member 130 in the direction along the rotation shaft 14A.

Next, the function of the torsion spring 140 in the third state shown in FIG. 15 will be described.
First, the state of the torsion spring 140 will be described.
The torsion spring 140 shown in FIG. 15 is not in a squeezed state but in an open state. Furthermore, as shown in FIG. 15B, the free end 141 of the torsion spring 140 is at a position where the height from the rear plate 93 in the direction of arrow E is high. This is because the arm portion 147 of the torsion spring 140 receives a force pushed in the direction of arrow E from the inclined portion 133 of the push-up member 130. Further, since the arm portion 147 of the torsion spring 140 is at a position where the height from the rear plate 93 in the arrow E direction is high, the arm portion 147 is in contact with the claw portion 153 of the gear plate 150.
The specific height of the push-up member 130 is a height at which the push-up member 130 can bring the arm portion 147 into contact with the claw portion 153 of the gear plate 150 by pushing the arm portion 147 of the torsion spring 140 in the arrow E direction. Say that.

Next, the force acting on the torsion spring 140 will be described.
As shown in FIG. 15A, the arm portion 147 of the torsion spring 140 does not receive a force from the hook portion 173 of the guide rib 170 in the circumferential direction of the rotating shaft 14A. Further, the arm portion 147 of the torsion spring 140 receives a force in the direction of arrow C from the claw portion 153 of the gear plate 150. Further, the fixed end 143 of the torsion spring 140 does not receive a force from the push-up member 130. As a result, the torsion spring 140 is rotated around the rotating shaft 14A.
On the other hand, as shown in FIG. 15B, the arm portion 147 of the torsion spring 140 receives a force pushed in the direction of arrow E from the inclined portion 133 of the push-up member 130 in the direction along the rotation shaft 14A. Note that the arm portion 147 of the torsion spring 140 does not receive a force from the guide rib 170.

Next, the function of the torsion spring 140 in the fifth state shown in FIG. 17 will be described.
First, the state of the torsion spring 140 will be described.
The torsion spring 140 shown in FIG. 17 is not in a squeezed state but in an open state. Further, as shown in FIG. 17B, the free end 141 of the torsion spring 140 is at a position where the height from the rear plate 93 in the direction of arrow E is high. This is because the arm portion 147 of the torsion spring 140 receives a force pushed from the guide rib 170 in the arrow E direction. The arm portion 147 of the torsion spring 140 is in contact with the claw portion 153 of the gear plate 150 because the free end 141 is at a position where the height from the rear plate 93 in the direction of arrow E is high.
The specific height of the guide rib 170 described above is such a height that the guide rib 170 can bring the arm portion 147 into contact with the claw portion 153 of the gear plate 150 by pushing the arm portion 147 of the torsion spring 140 in the arrow E direction. Say that.

Next, the force acting on the torsion spring 140 will be described.
As shown in FIG. 17A, the arm portion 147 of the torsion spring 140 does not receive a force from the hook portion 173 of the guide rib 170 in the circumferential direction of the rotating shaft 14A. Further, the arm portion 147 of the torsion spring 140 receives a force in the direction of arrow C from the claw portion 153 of the gear plate 150. Further, the fixed end 143 of the torsion spring 140 receives a force in the direction opposite to the arrow C direction from the push-up member 130 in the circumferential direction of the rotating shaft 14A. The force from the push-up member 130 is a reaction force received from the push-up member 130 fixed to the rotating disk 120 that has stopped rotating.
In addition, in the torsion spring 140, the fixed end 143 receives a force in the direction opposite to the arrow C direction from the push-up member 130, and the arm portion 147 of the torsion spring 140 receives a force in the arrow C direction from the claw portion 153. Therefore, it is in a state where it is receiving force in the direction of being squeezed.

  On the other hand, as shown in FIG. 17B, the arm portion 147 of the torsion spring 140 does not receive a force from the inclined portion 133 of the push-up member 130 in the direction along the rotation shaft 14A. On the other hand, the arm portion 147 of the torsion spring 140 receives a force pushed in the direction of arrow E from the guide rib 170.

<Function of the rotating disk 120>
The function of the rotating disk 120 in the first state shown in FIG. 12 will be described. Here, the state of the lock member 160 and the force acting on the rotating disk 120 will be described separately.
First, the state of the lock member 160 will be described.
The lock member 160 shown in FIG. 12 is in an on state. In other words, the protrusion receiving portion 161 of the lock member 160 enters the movement path of the protrusion 125 provided on the rotating disk 120.

Next, the force that acts on the rotating disk 120 will be described.
The front side surface 120a of the rotating disk 120 receives a force in the direction of arrow C from the push-up member 130 to which the fixed end 143 of the torsion spring 140 is fixed. The force received from the push-up member 130 is due to a force that causes the fixed end 143 provided on the push-up member 130 to rotate in the direction of arrow C by the elastic force of the torsion spring 140 that is in the squeezed state.
Further, the protrusion 125 of the rotating disk 120 receives a force in the direction opposite to the arrow C direction by contacting the protrusion receiving portion 161 of the lock member 160.
The rotating disk 120 is stopped by these forces without rotating around the rotating shaft 14A.

The function of the rotating disk 120 in the second state shown in FIG. 14 will be described.
The lock member 160 shown in FIG. 14 is in an off state. That is, the protrusion receiving portion 161 of the lock member 160 is retracted with respect to the movement path of the protrusion 125 provided on the rotating disk 120.

Next, the force that acts on the rotating disk 120 will be described.
The front side surface 120a of the rotating disk 120 receives a force in the direction of arrow C from the push-up member 130 to which the fixed end 143 of the torsion spring 140 is fixed. The force received from the push-up member 130 causes the torsion spring 140, which is changing from the throttled state to the released state, to rotate the fixed end 143 provided on the push-up member 130 in the direction of arrow C by the elastic force. It is due to the power to do.
Further, the protrusion 125 of the rotating disk 120 is not receiving a force from the protrusion receiving portion 161 of the lock member 160.
The rotating disk 120 rotates around the rotating shaft 14A by these forces.

The function of the rotating disk 120 in the fourth state shown in FIG. 16 will be described.
The lock member 160 shown in FIG. 16 is in an on state. In other words, the protrusion receiving portion 161 of the lock member 160 enters the movement path of the protrusion 125 provided on the rotating disk 120.

Next, the force that acts on the rotating disk 120 will be described.
The front side surface 120a of the rotating disk 120 receives a force in the direction of arrow C from the push-up member 130 to which the fixed end 143 of the torsion spring 140 is fixed. The force received from the push-up member 130 is that the fixed end 143 of the torsion spring 140 is moved in the arrow C direction as the arm portion 147 of the torsion spring 140 receives the force that the claw portion 153 of the gear plate 150 rotates in the arrow C direction. This is to receive a rotating force.
Further, the protrusion 125 of the rotating disk 120 is not receiving a force from the protrusion receiving portion 161 of the lock member 160. This is a state in which the protrusion receiving portion 161 of the lock member 160 has entered the movement path of the protrusion 125 of the rotating disk 120 as described above, but is not in contact with the protrusion 125 of the rotating disk 120. Because.
Then, by receiving the rotational driving force via the torsion spring 140, the rotating disk 120 rotates around the rotating shaft 14A.

<Operation of Image Forming Apparatus 1>
Next, the overall operation of the image forming apparatus 1 will be described with reference to FIGS. 1 and 2. Here, a case where a plurality of color images are formed on one sheet S by the image forming apparatus 1 will be described.

  First, a color material reflected light image of a document read by a document reading device (not shown), and color material image data formed by a personal computer (not shown) or the like are, for example, R (red), G (green). , B (blue) data is input to an image signal processing device (not shown) and subjected to predetermined image processing. The image data subjected to the image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the exposure device 13.

  With the start of the image forming operation, the photosensitive drum 11 and the transfer drum 21 start to rotate in synchronization. At this time, the front end gripper 23 rotates together with the transfer drum 21, whereas the rear end gripper 27 does not rotate together with the transfer drum 21 and is stationary at the standby position (the peripheral speed is zero).

  Then, after the photosensitive layer 11 </ b> A of the rotating photosensitive drum 11 is charged by the charging device 12, an electrostatic latent image of the first color (for example, yellow) corresponding to the image information is formed by the exposure device 13. Further, as the transfer drum 21 starts to rotate, the paper detection sensor 25 measures the phase of the transfer drum 21. The measured phase is sent to the control unit 50.

On the other hand, in the developing device 14, a developing device (for example, yellow developing device 14 Y in the case of yellow) having a color component toner corresponding to the electrostatic latent image formed on the photosensitive drum 11 is connected to the photosensitive drum 11. It has been rotated in advance so as to be placed at the opposite position, and stopped.
Then, for example, the electrostatic latent image on the photosensitive drum 11 is developed by the developing device 14 </ b> Y, and a toner image is formed on the photosensitive drum 11. Then, the toner image (here, a yellow toner image) is sent toward the transfer portion Tr facing the transfer device 20 as the photosensitive drum 11 rotates.

  Also, the paper S is supplied in response to the start of the recording image forming operation. Specifically, the paper S taken out from the paper storage unit 41 by the take-out roll 42 is sent out to the supply path 51 using the transport roll 44 through the separation roll 43. Then, the conveyance is controlled so that the sheet S reaches the position where the leading edge gripper 23 reaches the position (supply position) where the sheet S is supplied to the transfer drum 21.

  And in the supply position, it transfers from the state where the front-end | tip gripper 23 was open to the closed state. Accordingly, the leading edge of the sheet S in the transport direction is gripped by the leading edge gripper 23. At this time, the rear end gripper 27 is at the outer periphery of the transfer drum 21 and is stationary at the standby position. The leading edge gripper 23 holding the sheet S passes between the stationary trailing edge gripper 27 and the rotation center of the transfer drum 21.

The leading edge gripper 23 that has passed between the trailing edge gripper 27 and the elastic layer 21 </ b> B passes through the transfer portion Tr while holding the sheet S. The sheet S that has been gripped by the leading edge gripper 23 and passed through the transfer portion Tr is wound around the transfer drum 21 while being gripped by the leading edge gripper 23 and is conveyed along the rotation path 53 (see FIG. 1).
Then, after the first color (for example, yellow) electrostatic latent image corresponding to the image information is formed by the exposure device 13, the paper detection sensor 25 detects that the rear end of the paper S in the transport direction has passed. Then, the control unit 50 receiving the signal from the paper detection sensor 25 issues an instruction to the rear end gripper 27. Receiving the instruction, the rear end gripper 27 shifts from an open state to a closed state.

  Now, the closed rear end gripper 27 starts to rotate in synchronization with the transfer drum 21. In other words, the sheet S rotates with the transfer drum 21 while the leading end in the transport direction is held by the leading end gripper 23 and the trailing end is held by the trailing end gripper 27. The toner image of the first color (for example, yellow) formed on the photosensitive drum 11 is transferred onto the sheet S on the transfer drum 21 at a transfer portion Tr where the photosensitive drum 11 and the transfer drum 21 face each other. The toner remaining on the photosensitive drum 11 after the transfer is removed by a cleaning device 15 (see FIG. 1).

Then, from the second color, latent image formation (for example, magenta, cyan) before the final color (for example, black), development and transfer are similarly repeated according to the above-described procedure. However, when the toner images of the respective colors are formed, the developing device 14 performs a rotation operation, and the corresponding developing devices 14M and 14C are arranged at the stop position.
Meanwhile, the sheet S is rotated and conveyed while being wound around the transfer drum 21 by the leading edge gripper 23 and the trailing edge gripper 27, and the toner images of the second and subsequent colors are overlapped each time the sheet S passes the transfer portion Tr. Sequentially transferred. As a result, for example, when full-color image formation is performed, toner images of each color of yellow (Y), magenta (M), and cyan (C) excluding black (K) are multiple-transferred onto the sheet S on the transfer drum 21. Is done.

  When the final color is transferred, unlike the transfer before the final color (for example, black), the leading edge gripper 23 shifts from the closed state to the open state at the transfer site Tr. As a result, the sheet S on which the gripping by the leading edge gripper 23 is released and a full-color image is formed is discharged after the leading edge in the transport direction of the sheet S is peeled off from the transfer drum 21 by the nip between the elastic layer 21B and the photosensitive drum 11. Enter the route 52.

  Thereafter, as the paper S is transported, the rear end gripper 27 that holds the rear end in the transport direction of the paper S shifts from a closed state to an open state. Note that the transition from the closed state to the opened state of the trailing edge gripper 27 is after the electrostatic latent image of the final color (for example, black) corresponding to the image information has already been formed by the exposure device 13. . Then, the rear end gripper 27 in the opened state stops at the standby position.

Then, the rear end in the transport direction of the paper S released from being held by the rear end gripper 27 is peeled off from the transfer drum 21 and enters the discharge path 52. The sheet S that has entered the discharge path 52 is sent to the fixing device 30. Then, the toner image on the paper S is fixed by the heating roll 31 and the pressure roll 32 of the fixing device 30.
The sheet S after completion of fixing is discharged out of the image forming apparatus 1 by the transport roll 44 and is stacked on the paper discharge stacking unit 3.

<Timing of transmission mechanism 100 operation>
Next, the timing at which the transmission mechanism 100 operates will be described with reference to FIGS. 1 and 13. Here, FIG. 13 is a timing chart showing the switching operation of the transmission mechanism 100 in the four-color image forming operation.

As shown in FIG. 13, in the present embodiment, when the image forming apparatus 1 forms an image, a developing operation is performed by the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) of the developing device 14.
Here, when the developing operations of the developing devices 14Y, 14M, 14C, and 14K are completed, the moving operations (switching operations) of the developing devices 14Y, 14M, 14C, and 14K are performed for the development cycle of the next color. . The switching operation of the developing units 14Y, 14M, 14C, and 14K is performed by rotating the rotary developing unit 14R (see FIG. 1) by the transmission mechanism 100 (see arrow C in FIG. 1). Hereinafter, the timing of the switching operation of the transmission mechanism 100 will be described in detail.

First, in a state before the image forming operation of the image forming apparatus 1 is started, the transmission mechanism 100 is in an off state (a state where the free end 141 of the torsion spring 140 is not rotating around the rotation shaft 14A). At this time, the lock member 160 of the transmission mechanism 100 is in an ON state (a state in which the protrusion receiving portion 161 has entered the movement path of the protrusion 125). Further, a developing device 14Y corresponding to the first color (herein described as yellow (Y)) is disposed at the development position.
Then, with the start of the image forming operation of the image forming apparatus 1, a yellow (Y) electrostatic latent image is formed by the exposure device 13. Then, after development by the developing device 14Y is started, transfer by the transfer device 20 is performed.

After the transfer of yellow (Y) is completed, the lock member 160 of the transmission mechanism 100 is turned from on to off (a state in which the protrusion receiving portion 161 is retracted from the movement path of the protrusion 125) (see reference numeral 13a). As the lock member 160 is turned off, the transmission mechanism 100 is turned on (the free end 141 of the torsion spring 140 is rotating around the rotation shaft 14A) (see reference numeral 13b). Then, the transmission mechanism 100 rotates the rotary developing device 14R around the rotation shaft 14A (see FIG. 1) (see arrow C in FIG. 1). By this rotation, the developing device 14M corresponding to the second color (described here as magenta) is arranged at the developing position.
On the other hand, the locking member 160 is turned on again after a predetermined time has elapsed after being turned off. Then, after the lock member 160 is turned on again, the transmission mechanism 100 is turned off. After the transmission mechanism 100 is turned off, the next magenta (M) exposure is started (see reference numeral 13c).

  Here, in the present embodiment, the switching operation of the developing units 14Y, 14M, 14C, and 14K by the transmission mechanism 100 is performed while the developing units 14Y, 14M, 14C, and 14K are not performing development. More specifically, the switching operation of the developing devices 14Y, 14M, 14C, and 14K by the transmission mechanism 100 forms a toner image by developing any of the developing devices 14Y, 14M, 14C, and 14K (for example, the developing device 14Y). The toner image is started after the toner image is transferred by the transfer device 20. Then, the switching operation of the developing devices 14Y, 14M, 14C, and 14K by the transmission mechanism 100 ends before the exposure device 13 starts to form the next electrostatic latent image (for example, a magenta electrostatic latent image). Accordingly, it is possible to suppress the image quality from being affected by the occurrence of vibration, impact, or the like in the image forming unit 10, the transfer device 20, or the like with the switching operation of the transmission mechanism 100.

<Operation of Transmission Mechanism 100>
Next, the operation of the transmission mechanism 100 will be described with reference to FIGS. 1, 12, and 14 to 18. Here, the developing units 14Y, 14M, 14C, and 14K provided in the rotary developing unit 14R are switched from one developing unit (for example, the developing unit 14Y) to another developing unit (for example, the developing unit 14M) adjacent in the circumferential direction. Accordingly, it rotates 90 degrees around the rotating shaft 14A. By rotating 90 degrees about the rotating shaft 14A four times, the rotary developer 14R rotates 360 degrees about the rotating shaft 14A.

(A) First State With reference to FIGS. 1 and 12, the transmission mechanism 100 in the first state will be described.
In the first state, the transmission mechanism 100 has stopped operating, and the rotary developer 14R has stopped rotating. In addition, any of the developing devices 14Y, 14M, 14C, and 14K provided in the developing device 14 is disposed at the developing position. Here, description will be made assuming that the developing device 14Y is disposed at the developing position.

  Here, the driving force is transmitted from the transfer drum driving motor M1 to the developing device gear G3 via the intermediate gears G5 and G6 (see FIG. 2). As a result, the gear plate 150 rotates in the direction of arrow C in FIG. Note that, in any of the second state to the sixth state, which will be described later, the gear plate 150 continues to rotate in the direction of arrow C under the driving of the transfer drum drive motor M1.

In the first state, the lock member 160 is in an on state, and the protrusion receiving portion 161 of the lock member 160 has entered the movement path of the protrusion 125 provided on the rotating disk 120. .
Further, when the protrusion 125 of the rotating disk 120 contacts the protrusion receiving portion 161 of the lock member 160, the position plate 110 is stopped from rotating. The rotating disk 120 receives a force to rotate it in the direction of arrow C by the elastic force of the torsion spring 140 in a squeezed state.

  Here, as shown in FIG. 12B, the arm portion 147 of the torsion spring 140 is in a position where the height from the rear plate 93 in the direction of arrow E is low, so that it contacts the claw portion 153 of the gear plate 150. Not. Therefore, when the claw portion 153 of the gear plate 150 rotates around the rotation shaft 14A, the arm portion 147 of the torsion spring 140 is not pushed. In the first state, the gear plate 150 is idle.

(B) Second State The transmission mechanism 100 in the second state will be described with reference to FIGS. 1 and 14.
In the second state, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotation shaft 14A start to rotate.

  In the second state, the lock member 160 is turned off from on, and the protrusion receiving portion 161 of the lock member 160 is retracted from the movement path of the protrusion 125. Then, as the torsion spring 140 that has been squeezed is changed to an open state, the rotating disk 120 is rotated in the direction of arrow C. Then, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) are rotated through the rotating shaft 14A that rotates together with the rotating disk 120.

Here, as the fixed end 143 of the torsion spring 140 rotates in the direction of arrow C with the portion of the arm portion 147 of the torsion spring 140 in contact with the hook 173 of the guide rib 170 as a fulcrum, the fixed end 143 and the arm portion 147 The relative position of changes. The arm portion 147 of the torsion spring 140 is in contact with the inclined portion 133 provided on the push-up member 130 and moves along the inclined portion 133. As a result, the arm portion 147 of the torsion spring 140 is pushed in the direction from the rear side toward the front side by the inclined portion 133 and moves to the gear plate 150 side (see arrow E).
In the state shown in FIG. 14, the arm portion 147 of the torsion spring 140 is not yet in contact with the claw portion 153 provided on the gear plate 150. Therefore, the gear plate 150 in the second state is in a state of continuing idling.

(C) Third State The transmission mechanism 100 in the third state will be described with reference to FIGS.
In the third state, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotation shaft 14A continue to rotate.

  In the third state, the lock member 160 is kept off. Further, the relative position between the fixed end 143 of the torsion spring 140 and the arm portion 147 further changes (the torsion spring 140 is further opened). The arm portion 147 of the torsion spring 140 is further pushed in the direction from the rear side toward the front side (see arrow E) by the inclined portion 133 of the push-up member 130. As a result, the arm portion 147 of the torsion spring 140 is disposed at a position where the height from the rear plate 93 in the direction of arrow E is high.

  Then, the claw portion 153 of the rotating gear plate 150 comes into contact with the arm portion 147 of the torsion spring 140, and the arm portion 147 is pushed in the direction of arrow C. More specifically, when the claw portion 153 of the gear plate 150 presses the arm portion 147 of the torsion spring 140, the drive of the transfer drum drive motor M1 (see FIG. 2) is transmitted to the torsion spring 140 via the gear plate 150. This is a state.

(D) Fourth State The transmission mechanism 100 in the fourth state will be described with reference to FIGS. 1 and 16.
In the fourth state, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotation shaft 14A continue to rotate.

  In the fourth state, the lock member 160 is turned on from off, and the protrusion receiving portion 161 of the lock member 160 enters the movement path of the protrusion 125 provided on the position plate 110. Here, in the fourth state, the protrusion receiving portion 161 of the lock member 160 and the protrusion 125 of the position plate 110 are not in contact with each other. That is, it is a state before the lock member 160 locks the rotating disk 120.

  Further, as the torsion spring 140 rotates around the rotating shaft 14A, the free end 141 of the torsion spring 140 passes through the inclined portion 171 of the guide rib 170 and rides on the guide rib 170 (FIG. 16B). )reference). As a result, the free end 141 of the torsion spring 140 is maintained at a position where the height from the rear plate 93 in the arrow E direction is high. Accordingly, the arm portion 147 of the torsion spring 140 maintains a state where the arm portion 147 is pushed by the claw portion 153 of the gear plate 150 (see arrow C).

(E) Fifth State The transmission mechanism 100 in the fifth state will be described with reference to FIGS. 1 and 17.
In the fifth state, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotating shaft 14A are stopped. In the fifth state, the developing device 14M is disposed at the developing position. In addition, the fifth state shown in FIG. 17 is a state in which the position plate 110 is rotated 90 degrees in the direction of arrow C in FIG. 17A with reference to the first state shown in FIG.

In the fifth state, the lock member 160 remains on. Then, as the protrusion 125 of the position plate 110 rotates, the protrusion receiving portion 161 of the lock member 160 comes into contact with the protrusion 125. As a result, the protrusion receiving portion 161 of the lock member 160 stops the rotation of the position plate 110 (the lock member 160 locks the rotary disc 120).
Here, in the fifth state, the protrusion receiving part 161 of the lock member 160 contacts the protrusion 125 adjacent to the protrusion 125 that the protrusion receiving part 161 of the lock member 160 was in contact in the first state in the circumferential direction. 125.

As the position plate 110 stops rotating, the fixed end 143 of the torsion spring 140 connected to the position plate 110 also stops rotating. On the other hand, the arm portion 147 of the torsion spring 140 continues to be pressed by the claw portion 153 provided on the gear plate 150 (see arrow C).
As a result, the relative position between the free end 141 and the fixed end 143 of the torsion spring 140 changes. More specifically, in the fifth state, the posture of the torsion spring 140 starts to change (starting to accumulate urging force), and is in a state of being narrowed from the released state.

(F) Sixth State The transmission mechanism 100 in the sixth state will be described with reference to FIGS. 1 and 18.
In the sixth state, the operation of the transmission mechanism 100 is stopped.

  In the sixth state, the lock member 160 remains on. The protrusion receiving portion 161 of the lock member 160 is in contact with the position plate 110 and stops rotating.

  Further, in the sixth state, the arm portion 147 of the torsion spring 140 that rides on the guide rib 170 and rotates in the direction of arrow C passes through the guide rib 170 and is hooked on the hook portion 173. In other words, the arm portion 147 of the torsion spring 140 is not pushed by the guide rib 170 in the direction from the rear side to the front side (see arrow E). As a result, the free end 141 of the torsion spring 140 moves in the direction from the front side toward the rear side (see arrow D), and the height from the rear plate 93 in the direction of arrow E is low. Note that the movement of the free end 141 of the torsion spring 140 is due to the arm portion 147 of the torsion spring 140 extending from the winding portion 145 to the rotating disk 120 side as seen from the side as described above. (See FIG. 9C).

  The free end 141 of the torsion spring 140 moves in the direction from the front side toward the rear side (see arrow D), so that the arm portion 147 of the torsion spring 140 does not come into contact with the claw portion 153 provided on the gear plate 150. It becomes. As a result, the claw portion 153 of the gear plate 150 does not press the arm portion 147 of the torsion spring 140 (end of accumulation of the urging force). Therefore, the gear plate 150 is idled.

  As described above, the transmission mechanism 100 according to the present embodiment switches the lock member 160 between on and off, so that the developing units 14Y, 14M, 14C, and 14K (see FIG. 1) are sequenced by the mechanical mechanism. Switching operation is performed. In addition, the transmission mechanism 100 of the present embodiment does not require an electrical control circuit or the like for the switching operation of the developing devices 14Y, 14M, 14C, and 14K. Further, there is no need for an electrical drive source that is driven when the developing devices 14Y, 14M, 14C, and 14K are switched.

<Modification>
Next, a transmission mechanism 200 that is a modification of the above-described transmission mechanism 100 will be described with reference to FIGS. 19 and 20. Here, FIG. 19 is an exploded perspective view of the transmission mechanism 200. FIG. 20 is a front view of the transmission mechanism 200. In FIG. 20, the portion hidden behind the gear G30 is also indicated by a solid line.
Here, the transmission mechanism 200 includes a position plate 210 that rotates integrally with the rotating shaft 14A and arranges the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) at predetermined positions. Further, the transmission mechanism 200 includes a gear G30 that rotates around the rotation shaft 14A and supplies a driving force for rotating the position plate 210 by engaging with the position plate 210. Furthermore, the transmission mechanism 200 includes a lock member (regulator) 260 that stops the position plate 210 that rotates together with the rotating shaft 14A. Furthermore, the transmission mechanism 200 includes a gear driving unit M3 (see FIG. 20) that supplies driving force to the gear G30.

Note that the lock member 260 and the gear driving unit M3 are supported by the housing 2 (see FIG. 1) on the image forming apparatus 1 side. More specifically, as described above, the developing device 14 is detachably disposed with respect to the image forming apparatus 1. When the developing device 14 is detached from the image forming apparatus 1, the lock member 260 and the gear driving unit M3 are left on the image forming apparatus 1 side.
Each will be described below.

<Position plate 210>
As shown in FIG. 19, the position plate 210 has a rotating disc 220 that rotates integrally with the rotating shaft 14A. As described above, the rotary shaft 14A is connected to the rotary developing device 14R (see FIG. 1), and the rotary developing device 14R (see FIG. 1) also rotates as the rotating disk 220 rotates. It is configured.
Further, the position plate 210 has a moving pin 230 that engages with the rotating disk 220 and rotates the rotating disk 220. Furthermore, the position plate 210 includes a coil spring 240 that is connected to the moving pin 230 and supplies a driving force for rotating the rotating disk 220 via the moving pin 230.
In this modification, a moving pin 230 and a coil spring 240 are arranged on the front side of the rotating disk 220 (the front side in FIG. 1).

<Rotating disc 220>
First, the rotating disk 220 will be described. The rotating disk 220, which is an example of the regulated portion, is a circular metal plate that is fixed to the rotating shaft 14A and rotates together with the rotating shaft 14A. The rotating disk 220 has a through hole 221 into which the rotating shaft 14A is inserted at the center of the surface.
Further, the rotating disk 220 has a protrusion 225 that engages with the lock member 260 on the outer periphery of the rotating disk 220. The protrusion 225 is configured to extend in the direction away from the center of rotation on the outer periphery of the rotating disk 220. Further, four protrusions 225 are provided every 90 degrees in the circumferential direction of the rotating shaft 14A. Here, in the present embodiment, the same number of protrusions 225 as the number of the developing devices 14Y, 14M, 14C, and 14K provided in the developing device 14 is provided.

Further, the rotating disk 220 has a pin guide portion 227 provided so as to protrude from a gear side surface (surface disposed on the front side in FIG. 1) 220a of the rotating disk 220 on the gear G30 side.
Here, the pin guide portion 227 has a pin receiving portion 229 that receives the moving pin 230 by hooking the moving pin 230. Four pin receiving portions 229 are provided every 90 degrees in the circumferential direction of the rotating shaft 14A. The same number of pin receiving portions 229 as the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided in the developing device 14 are provided.
Between each pin receiving part 229, the outer peripheral side surface 227c which is a surface which guides the moving pin 230 received by the pin receiving part 229 to the adjacent moving pin receiving part 229 is formed continuously with the pin receiving part 229. ing.
More specifically, in the example shown in FIG. 19, the pin receiving portion 229 is formed by projecting (or indenting) a part of the outer peripheral side surface 227 c away from the rotation center of the rotating disk 220.

<Moving pin 230>
The moving pin 230 is a cylindrical member. The moving pin 230 is arranged such that one end 230a is in contact with the gear G30 and the other end 230b is in contact with the rotating disk 220. Moreover, the moving pin 230 has a main body side surface 230c located between one end 230a and the other end 230b.

<Coil spring 240>
The coil spring 240, which is an example of a rotating part, is arranged with one end 243 connected to a fixed pin 270 provided on the rear plate 93 and the other end 245 connected to a moving pin 230.
In this modification, the coil spring 240 is used, but other elastic members such as rubber may be used.

<Gear G30>
The gear G30 is connected to the gear drive unit M3 (see FIG. 20), and is configured to rotate around the rotation shaft 14A under the drive of the gear drive unit M3. This gear G30 has a through hole 251 into which the rotary shaft 14A is inserted at the center of the surface. Here, the gear G30 is rotatably arranged around the rotation shaft 14A without being fixed to the rotation shaft 14A. More specifically, the gear G30 is configured to rotate in both the forward direction and the reverse direction (see arrow H) with respect to the rotation direction (see arrow C) of the rotating shaft 14A.

As shown in FIG. 19, the gear G30 has a pin groove 253 that is a recess formed in a surface G30b facing the rotating disk 220. The pin groove 253 is formed with such a dimension that the moving pin 230 is inserted and the inserted moving pin 230 can be displaced in the radial direction of the gear G30 in the pin groove 253. More specifically, the pin groove 253 is configured to move the moving pin 230 inserted in the pin groove 253 on the gear side surface 220a of the rotating disk 220 without the gear G30 rotating. .
Unlike the above-described embodiment, the gear G30 is not connected to the transfer drum drive motor M1, and is not driven by the transfer drum drive motor M1. More specifically, the gear G30 is not connected to the photosensitive drum driving motor M2, and is not driven by the photosensitive drum driving motor M2.

<Lock member 260>
The lock member 260 is a plate-shaped metal member. And, at one end, there is a protrusion receiving portion 261 that engages with the protrusion 225 of the rotating disk 220.
Further, a cam follower (not shown) that is pressed by a cam (not shown) provided on the transfer drum 21 (see FIG. 1) is provided at the end opposite to the side on which the projection receiving portion 261 is provided. It has been. Further, the lock member 260 has a support shaft 263 at the center. The support shaft 263 is supported by the housing 2 (see FIG. 1) on the image forming apparatus 1 side. The lock member 260 is configured to swing around the support shaft 263 (see arrow F). Each time the transfer drum 21 rotates once, a cam (not shown) provided on the transfer drum 21 presses a cam follower (not shown) provided on the lock member 260. As a result, the lock member 260 swings around the support shaft 263 to move the protrusion receiving part 261 at the tip, and the protrusion of the rotating disk 220 that engages with the protrusion receiving part 261 is released. ing.

<Gear drive unit M3>
A gear drive unit M3, which is an example of a drive source, is connected to the gear G30 via a gear train (not shown). This gear drive part M3 consists of a stepping motor, for example.
As described above, the gear driving unit M3 is supported by the housing 2 (see FIG. 1) on the image forming apparatus 1 side, but is not limited thereto. For example, the image forming apparatus 1 may be supported by a detachable device or member (for example, the transfer drum 21) arranged on the image forming apparatus 1 side. Alternatively, the gear driving unit M3 may be supported on the developing device 14 side (for example, the frame body 90).

<Structure of transmission mechanism 200>
Next, the structure of the transmission mechanism 200 will be described with reference to FIGS. 19 and 20.

  First, as shown in FIG. 19, the transmission mechanism 200 includes the rear plate 93, the position plate 210, the gear G30, the lock member 260, and the gear driving unit M3 as described above. The rotary shaft 14A of the rotary developing device 14R (see FIG. 1) is inserted into the through hole 94 of the rear plate 93, the through hole 221 of the rotating disk 220 in the position plate 210, and the through hole 251 of the gear G30. Yes. Here, the rotating disc 220 in the position plate 210 is fixed to the rotating shaft 14A so as to rotate together with the rotating shaft 14A. On the other hand, the rear plate 93 and the gear G30 are provided without being fixed to the rotating shaft 14A.

  As shown in FIG. 20, a fixing pin 270 for the rear plate 93 is provided outside the position plate 210. The fixing pin 270 is disposed at a position where it does not come into contact with the protrusion 225 provided on the rotating disk 220.

  The lock member 260 is provided so as to swing around the support shaft 263 (see arrow F in FIG. 19). In addition, as the lock member 260 swings, the protrusion receiving portion 261 of the lock member 260 moves in a direction intersecting the surface of the rotating disk 220. Accordingly, the protrusion receiving portion 261 of the lock member 260 is configured to advance and retract with respect to the movement path of the protrusion 225 provided on the rotating disc 220. The protrusion receiving portion 261 of the lock member 260 is configured to advance and retreat with respect to the movement path of the protrusion 225 by moving in the radial direction of the rotating disk 220 or moving in the tangential direction of the rotating disk 220, for example. It may be.

The moving pin 230 in the position plate 210 is disposed such that both ends of the cylinder are sandwiched between the gear G30 and the rotating disk 220.
One end 230a of the moving pin 230 is inserted into the pin groove 253 of the gear G30 so as to engage with the gear G30.

On the other hand, the other end 230 b of the moving pin 230 is disposed in contact with the gear side surface 220 a of the rotating disk 220. Here, the other end 230b of the moving pin 230 is not fixed to the gear side surface 220a of the rotating disk 220, and is configured to move on the gear side surface 220a of the rotating disk 220 as described above. Has been.
More specifically, the main body side surface 230c of the moving pin 230 is disposed so as to contact the outer peripheral side surface 227c of the pin guide portion 227. Accordingly, the moving pin 230 moves along the outer peripheral side surface 227c of the pin guide portion 227.

The coil spring 240 in the position plate 210 has one end 243 fixed to a fixed pin 270 provided on the rear plate 93 and the other end 245 fixed to the moving pin 230. Here, as the gear G30 or the rotating disk 220 rotates around the rotating shaft 14A (details will be described later), the distance between the fixed pin 270 and the moving pin 230 varies. As the distance between the fixed pin 270 and the moving pin 230 changes, the coil spring 240 expands and contracts.
The gear G30 rotates in the direction opposite to the rotation direction of the rotary shaft 14A (see arrow H in FIG. 19) when receiving drive from the gear drive unit M3 (see FIG. 19).

<Operation of Transmission Mechanism 200>
Next, the operation of the transmission mechanism 200 will be described with reference to FIGS. Here, the operation in which the transmission mechanism 200 rotates the rotary developing device 14R by 90 degrees will be described in each stage from the first state to the fourth state. 21A and 21B are diagrams for explaining the operation of the transmission mechanism 200. FIG. More specifically, FIGS. 21A and 21B are schematic configuration diagrams of the transmission mechanism 200 in the first state to the fourth state, respectively.

(A) First State With reference to FIGS. 1 and 21A, the transmission mechanism 200 in the first state will be described.
First, in the first state, the transmission mechanism 200 has stopped operating, and the rotary developer 14R has stopped rotating. In the first state, any of the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided in the developing device 14 is disposed at the developing position. Here, description will be made assuming that the developing device 14Y is disposed at the developing position.
Furthermore, the gear drive unit M3 (see FIG. 20) is not driven, and the gear G30 connected to the gear drive unit M3 stops rotating.

In the first state, the lock member 260 is in an on state. Here, the state in which the lock member 260 is on is a state in which the lock member 260 locks the rotating disk 220.
Specifically, the protrusion receiving portion 261 of the lock member 260 enters the movement path of the protrusion 225 of the rotating disk 220 and prevents the protrusion 225 from moving. As a result, the protrusion receiving portion 261 of the lock member 260 stops the rotation of the position plate 210. In addition, at this time, the protrusion receiving portion 261 receives a force to rotate in the direction of arrow C from the position plate 210.

The force to rotate the position plate 210 is applied by the coil spring 240. First, in the first state, the coil spring 240 is arranged in an extended state (a state in which elastic energy is accumulated).
The coil spring 240 is fixed to a fixing pin 270 provided on the rear plate 93 whose one end 243 does not rotate, and the other end 245 is a moving pin that is applied to the pin receiving portion 229 of the rotating disk 220. 230 is fixed.
Furthermore, the moving pin receiving portion 229 is in a state that prevents the moving pin 230 from moving toward the fixed pin 270 side.
As a result, the moving pin 230 receives a force in a direction in which the moving pin 230 is pulled toward the fixed pin 270 by the coil spring 240. The moving pin receiving portion 229 receives a force from the moving pin 230 and applies a force for rotating the rotating disk 220 provided with the moving pin receiving portion 229.

(B) Second State The transmission mechanism 200 in the second state will be described with reference to FIGS. 1 and 21B.
In the second state, the developing shafts 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotating shaft 14A and the rotating shaft 14A start rotating together with the rotating shaft 14A.

More specifically, first, in the second state, the lock member 260 is turned off from on. Here, the state in which the lock member 260 is off is a state in which the lock member 260 releases the lock on the rotating disk 220.
Specifically, a cam follower (not shown) provided on the lock member 260 is pressed by a cam (not shown) provided on the transfer drum 21 (see FIG. 1), and the lock member 260 swings. . As a result, the protrusion receiving portion 261 of the lock member 260 is retracted from the movement path of the protrusion 225 of the rotating disk 220.
Then, the position plate 210 locked by the protrusion receiving portion 261 of the lock member 260 starts to rotate.

That is, in the coil spring 240 that has been extended in the first state, the other end 245 fixed to the moving pin 230 is attracted to the one end 243 fixed to the fixed pin 270 by an elastic force. (Releases elastic energy). Thus, the coil spring 240 rotates the rotating disk 220 in the rotating direction of the rotating shaft 14A (see arrow C) via the moving pin 230 and the pin receiving portion 229.
By the rotation of the rotating disk 220, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) are rotated through the rotating shaft 14A to which the rotating disk 220 is fixed. Further, as the moving pin 230 is attracted by the coil spring 240, the gear G30 is rotated in the rotation direction of the rotating shaft 14A (see arrow C) through the pin groove 253 in which the moving pin 230 is inserted. .

(C) Third State The transmission mechanism 200 in the third state will be described with reference to FIGS. 1 and 21C.
In the third state, the rotating shaft 14A and the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotating shaft 14A stop rotating. At this time, the developing device 14M is disposed at the developing position. In addition, the third state is a state in which the rotating disk 220 is rotated 90 degrees counterclockwise from the first state shown in FIG.

In the third state, the lock member 260 is turned on again. Specifically, the cam follower (not shown) provided on the lock member 260 is pressed by the cam (not shown) of the transfer drum 21 (see FIG. 1), and the lock member 260 swings. To do. Then, the protrusion receiving part 261 of the lock member 260 enters the movement path of the protrusion 225 of the rotating disk 220, and the protrusion receiving part 261 of the locking member 260 contacts the protrusion 225 of the rotating disk 220. As a result, the lock member 260 stops (locks) the rotation of the rotating disk 220. Here, in the third state, the protrusion receiving portion 261 of the lock member 260 comes into contact with the protrusion 225 that is in contact with the protrusion receiving portion 261 of the lock member 260 in the first state in the circumferential direction. 225.
In the coil spring 240, the other end 245 fixed to the moving pin 230 is pulled toward the one end 243 fixed to the fixing pin 270 and contracted.

(D) Fourth State With reference to FIGS. 1 and 21D, the transmission mechanism 200 in the fourth state will be described.
In the fourth state, the rotating shaft 14A and the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided around the rotating shaft 14A are stopped.

First, in the fourth state, the rotating disk 220 is stationary without rotating.
On the other hand, in the fourth state, the gear drive unit M3 (see FIG. 20) is driven. As a result, the gear G30 rotates in the direction opposite to the rotation direction of the rotating shaft 14A (see arrow H).
As described above, the gear G30 is not fixed to the rotating shaft 14A. Therefore, when the gear G30 rotates under the driving of the gear driving unit M3, the rotating shaft 14A maintains a stationary state.

As the gear G30 rotates in the direction opposite to the rotation direction of the rotary shaft 14A (see arrow H), the moving pin 230 disposed in the pin groove 253 of the gear G30 is placed on the outer peripheral side surface 227c of the pin guide portion 227. Along the surface of the rotating disk 220 along the surface.
More specifically, the moving pin 230 is detached from the pin receiving portion 229 that has received the moving pin 230 during the first state to the third state, and rotates along the outer peripheral side surface 227c of the pin guide portion 227. Move in the opposite direction (see arrow H). And it is received by the pin receiving part 229 which received the movement pin 230 between the 1st state thru | or the 3rd state, and the pin receiving part 229 adjacent in the circumferential direction. Note that the moving pin 230 inserted as described above is formed in a dimension that can be displaced in the radial direction of the gear G30 in the pin groove 253. As a result, the moving pin 230 can move to the pin receiving portion 229 beyond a portion formed by protruding from the outer peripheral side surface 227c in a direction away from the rotation center of the rotating disk 220.
As the moving pin 230 moves, the moving pin 230 is pulled away from the fixed pin 270, so that the coil spring 240 connecting the moving pin 230 and the fixed pin 270 expands.

  And after the moving pin 230 is received by the adjacent pin receiving part 229, the gear drive part M3 stops. This state is the same state as the first state.

  In the present embodiment, the developing device 14 having the rotary developing device 14R can be attached / detached and replaced from the image forming apparatus 1 side. This makes it possible to simplify the components with the image forming apparatus 1 or improve the operability for the user.

Here, the position of the developing device 14 relative to the image forming apparatus 1 may change as the developing device 14 is attached or detached. On the other hand, as described above, the lock member 260 is supported by the housing 2 (see FIG. 1) on the image forming apparatus 1 side, and the position of the lock member 260 is maintained even when the developing device 14 is detached. There is no change with respect to the image forming apparatus 1.
More specifically, since the position of the lock member 260 does not change, the position of the protrusion receiving portion 261 that engages with the protrusion 225 of the rotating disk 220 provided in the developing device 14 also does not change.

  This improves the positioning accuracy of the rotary developer 14R provided in the developing device 14. More specifically, for example, the accuracy of arranging the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) provided in the rotary developing device 14R at the developing position is improved. Therefore, the image quality of the toner image developed on the photosensitive drum 11 (see FIG. 1) is suppressed from being deteriorated as the developing device 14 is attached / detached.

Further, since the gear drive unit M3 is supported by the housing 2 (see FIG. 1) on the image forming apparatus 1, the developing device 14 can be downsized / simplified.
Furthermore, as described above, the developing units 14Y, 14M, 14C, and 14K (see FIG. 1) are positioned and switched to the developing position as a mechanical mechanism, except for the gear driving unit M3. By providing this mechanical mechanism in the developing device 14, when the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) are positioned and switched to the developing position, they are not affected by other units. Therefore, the positional accuracy is improved by reducing the number of intervening parts for positioning to the development position. Further, except for the gear drive unit M3, a control means using an electric member is unnecessary, and the developing device 14 can be downsized / simplified.

  More specifically, the developing devices 14Y, 14M, 14C, and 14K (see FIG. 1) are switched by a simple mechanical mechanism such as accumulation / release of elastic energy of the torsion spring 140 or the coil spring 240, and the electric drive except for the gear drive unit M3. It is possible to realize downsizing / simplification / cost reduction of the apparatus without providing any parts or its control function.

  In the above description, the rear plate 93, the position plate 210, and the gear G30 are arranged in this order along the arrow E shown in FIG. 19, but the present invention is not limited to this. For example, the rear plate 93, the gear G30, and the position plate 210 may be arranged in this order along the arrow E shown in FIG. In this case, a fixed pin 270 and a coil spring 240 are provided between the gear G30 and the position plate 210, and a pin guide portion 227 is arranged on the surface of the position plate 210 on the gear G30 side.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Housing, 10 ... Image forming part, 11 ... Photosensitive drum, 12 ... Charging device, 13 ... Exposure device, 14 ... Developing device, 14A ... Rotating shaft, 20 ... Transfer device, 21 ... Transfer Drum, 23 ... leading end gripper, 27 ... rear end gripper, 30 ... fixing device, 40 ... paper supply unit, 50 ... control unit, 51 ... supply path, 52 ... discharge path, 93 ... rear plate, 200 ... transmission mechanism, 210 ... Position plate, 220 ... Rotating disk, 230 ... Moving pin, 240 ... Coil spring, 260 ... Lock member, G30 ... Gear, S ... Paper

Claims (6)

An image forming apparatus main body;
A plurality of developing portions provided detachably with respect to the image forming apparatus main body, and provided rotatably about a shaft portion;
A regulating portion provided on the image forming apparatus main body side;
The rotation of the plurality of developing units, which are provided on the side of the plurality of developing units and rotate by engaging with the regulating unit, is stopped, and any one of the plurality of developing units is attached to the image forming apparatus main body. An image forming apparatus comprising: a regulated portion arranged at a predetermined position.   The image forming apparatus according to claim 1, wherein the plurality of developing units are detachably provided to the main body of the image forming apparatus by integrating the plurality of developing units. The image forming apparatus main body has an image holding body that is rotatably arranged and holds an image on an outer peripheral surface;
3. The restriction unit arranges a developing unit of any of the plurality of developing units at a predetermined position with respect to the image carrier provided in the image forming apparatus main body. The image forming apparatus described.   A rotating unit that is provided in the plurality of developing units and elastically deforms in response to receiving a driving force from the image forming apparatus main body, and rotates the plurality of developing units as the elastic deformation is restored; The image forming apparatus according to claim 1, wherein the image forming apparatus includes:   5. The image forming apparatus according to claim 1, wherein the image forming apparatus main body includes a driving source that supplies a driving force for rotating the plurality of developing units around the shaft portion. 6. A plurality of developing units provided detachably with respect to the main body of the image forming apparatus and provided to be rotatable about a shaft part;
By engaging with the restriction portion provided on the image forming apparatus main body side, the rotation of the plurality of developing portions rotating is stopped, and any one of the plurality of developing portions is connected to the image forming device main body. And a regulated portion arranged at a predetermined position.

Images