JP2001092241A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming device, where each developing gear ca be surely and correctly meshed with a drive gear. SOLUTION: A drive gear 111 on a device main body side is constituted to rotate by a prescribed angle with respect to a drive shaft 110. Even when the addenda of both gears butt against each other when a developing unit 1 is rotated and the developing gear 14 of a developing device is meshed with the driving gear 111, the drive gear 111 is rotated so as to relax impact by butting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color developing apparatus having a revolver type developing device in which a developing unit having a plurality of developing units rotates to move a developer conveying member of each developing unit to a position facing a latent image carrier. The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art A color image forming apparatus having a revolver type developing device in which a developing unit having a plurality of developing devices rotates and a developer conveying member of each developing device moves to a position facing a latent image carrier is well known. is there. In this type of color image forming apparatus, a plurality of developing devices are mounted on a rotatable revolver to form one developing device, and when developing each color, the revolver is rotated to move each developing device to a developing position. Things.

In the case of a revolver type developing device, it is necessary to rotate and drive a developer conveying member (developing roller or the like) at a developing position.
When the gears are driven by the respective driving gears meshing with the gears, not only the structure becomes complicated, but also the apparatus becomes large.

Accordingly, each developing gear is arranged around the rotation center of the developing unit, and one drive gear is provided in a portion other than the developing unit, for example, in the main body of the image forming apparatus.
It is known that a developing gear of a developer conveying member brought to a developing position by rotation of a developing unit meshes with a driving gear (gear of a main body driving unit). With such a configuration, advantages such as a simple structure and a reduction in the size of the developing device can be obtained.

[0005]

However, in the case of a configuration in which the developing gear of each color developing device is meshed with the driving gear of the main body, when the developing gear revolving around the rotation center of the developing unit starts to engage with the driving gear. However, there is a risk that both tooth tips will abut each other. If the developing gear is revolved while being left as it is, the teeth of the gear may be cut off, or the developing gear may stop revolving, making it impossible to properly engage both gears. Further, the same problem may occur between the supply gear of the toner supply member provided for each color developing device and the main body driving gear.

The present invention solves the above-mentioned problem in a color image forming apparatus provided with a conventional revolver type developing apparatus, and provides a color image forming apparatus capable of reliably engaging each developing gear with a driving gear. The task is to It is also an object of the present invention to correctly engage a replenishing portion gear of a toner replenishing member provided for each color developing device with a main body driving gear.

[0007]

According to the present invention, there is provided a color image forming apparatus comprising a revolver type developing unit for integrally supporting a plurality of developing units so as to be rotatable. In a color image forming apparatus having a developer conveying member for conveying a developer to a developing area, a developing gear provided for each of the developing devices for driving the developer conveying member, A driving gear provided on the image forming apparatus main body side, which meshes with the developing gear at a position to transmit a driving force, wherein one of the developing gear and the driving gear is fixed with respect to an axis of the gear. This is solved by being configured to be rotatable by an angle of.

According to another aspect of the present invention, there is provided a color image forming apparatus including a revolver type developing unit for integrally supporting a plurality of developing units so as to be rotatable. In a color image forming apparatus having a developer transport member for transporting a developer to a development area,
A replenishing portion gear for driving a developer replenishing member for replenishing the developer to the developing chamber provided for each of the developing devices; and transmitting a driving force by meshing with the replenishing portion gear at a developing position of each developing device. A drive gear provided on the image forming apparatus main body side, and one of the replenishment unit gear and the drive gear is configured to be rotatable by a predetermined angle with respect to an axis of the gear. suggest.

According to another aspect of the present invention, there is provided a color image forming apparatus including a revolver-type developing unit for integrally supporting a plurality of developing units so as to be rotatable. In a color image forming apparatus having a developer transport member for transporting a developer to a development area,
A developing gear provided for each of the developing devices for driving a developer conveying member; and a developing device provided on a main body of the image forming apparatus for transmitting a driving force by meshing with the developing gear at a developing position of each developing device. A drive gear, a replenishing portion gear provided for each of the developing devices, for driving a developer replenishing member for replenishing the developer to the developing chamber, and driven by meshing with the replenishing portion gear at a developing position of each developing device. And a replenishing unit driving gear provided on the image forming apparatus main body side for transmitting a force, wherein either the developing gear or the developing driving gear is rotatable by a predetermined angle with respect to an axis of the gear. It is proposed that one of the replenishing unit gear and the replenishing unit drive gear is configured to be rotatable by a predetermined angle with respect to the axis of the gear.

Further, in order to solve the above-mentioned problem, the present invention is directed to a gear which is configured to be rotatable by the predetermined angle, when the gear meshes with a gear of a meshing partner, the gear is driven by the rotational force of the revolver type developing unit. It is proposed that it be rotatable in the direction rotated by the gear of the meshing partner.

According to another aspect of the present invention, a gear configured to be rotatable by the predetermined angle rotates with respect to an axis of the gear by an angle equal to or more than one tooth of the gear. Suggest what is possible.

Further, in order to solve the above-mentioned problem, the present invention is configured to be rotatable by the predetermined angle when an external force for rotating the gear configured to be rotatable by the predetermined angle is lost. It is proposed to provide an elastic member for restoring the gear in the initial state.

In order to solve the above-mentioned problems, the present invention proposes that the elastic member is a torsion spring.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the entire structure of a developing device in a color image forming apparatus according to the present invention.

In FIG. 1, a developing unit 1 of a rotary developing device supported by an image forming apparatus main body 2 has three developing devices 3C, 3Y, and 3M in this embodiment. The 3Y, 3M developer chambers 4C, 4Y, 4M have three partition walls 6C, 6Y, 6M of a casing member 5 made of a non-magnetic material such as aluminum, and 2 fixed to both ends thereof.
Two end walls 7, 8 (see FIG. 2).

The developer chambers 4C, 4Y, and 4M accommodate developers 9C, 9Y, and 9M having different colors, respectively. In this embodiment, the developers have cyan, yellow, and magenta colors, respectively. . In addition, a carrier-free -component developer can be used as a developer, but in the example shown in the figure, a two-component developer having a carrier and a toner is used, and at least a part of the developer is a magnetic material. A magnetic developer is used.

The first to third developing units 3C, 3Y, 3
Although M is radially arranged around the rotation center O of the developing unit 1, the structures thereof are all the same. Therefore, in the following description, the configuration of the first developing device 3 </ b> C will be mainly described, and other components will be described. The description of the developing units 3Y and 3M is omitted because they are duplicated.

As will be described later, the developing unit 1 is rotatably supported around its rotation center O, and each developing unit rotates to a predetermined developing position to perform a developing operation. The state where the developing device 3C occupies the developing position is shown.

In FIG. 1, a developer conveying member provided in a first developing unit 3C, in the illustrated example, a developing roller 10 partially exposes through an opening formed by two partition walls 6C and 6Y. The developing roller 10 includes a photosensitive drum 1 as a latent image carrier rotatably supported by the image forming apparatus main body 2.
1 occupies a predetermined developing position. Developing unit 1
Is rotatably supported facing the photosensitive drum 11. A latent image carrier composed of a photoreceptor belt may be used instead of the photoreceptor drum, or a latent image carrier composed of a dielectric belt or a dielectric drum may be used depending on the type of the image forming apparatus. Is well known. The developing roller 10 is located parallel to the photosensitive drum 11 with a predetermined minute gap.

As can be seen from FIG. 2, both support shafts 12 and 13 of the developing roller 10 are rotatably supported by both end walls 7 and 8 of the developing roller 10, respectively. A developing gear 14 is fixed to the end of the end wall 8. An impeller 16 having a number of blades 15 is arranged inside the developer chamber 4C, and the impeller 16 is driven to rotate counterclockwise in FIG.

As a result, the developer in the developer chamber 4C, that is, the toner and the carrier are agitated while the developing roller 10 is being stirred.
And the toner is frictionally charged to a predetermined polarity by stirring the toner and the carrier.

S and N in FIG.
A magnet 21 having a magnetic pole composed of an S pole and an N pole is fixedly disposed on the casing member 5 of the developing unit 1 as indicated by the symbol. As a result, when the developing roller 10 is driven to rotate in the counterclockwise direction in FIG. 1 through the developing gear 14, the developer 9C supplied to the developing roller 10
Is carried on the surface of the developing roller 10 and is conveyed counterclockwise.

The transported developer is scraped by a doctor blade 22 fixed to the casing member 5, and a predetermined amount of the developer passing through the blade 22 is regulated to a layer thickness and directed toward the photosensitive drum 11. Sent.

On the other hand, the photosensitive drum 11 is driven to rotate clockwise in FIG. 1, and an electrostatic latent image corresponding to the original image is formed on its surface by a charging / exposure means (not shown) in a manner known per se. Have been. When this latent image reaches the developing area D where the photosensitive drum 11 and the developing roller 10 are opposed to each other, the charged toner in the developer conveyed to the area D also electrostatically transfers to an electrostatic latent image, and The image is visualized. This visible image is transferred to a transfer paper (not shown) by a transfer unit (not shown), and the transferred visible image is fixed by a fixing device (not shown). The developer that has passed through the developing area D is returned to the inside of the developer chamber 4C again, mixed with other developers in this chamber, and used again.

As shown in FIG. 2, a positioning pin 78 is provided on the end wall 8 on the rear side of the developing unit 1 on the center O of rotation of the unit 1 and this is a side plate 79 on the rear side of the main body of the image forming apparatus. The developing unit 1 is rotatably supported via a bearing 81, and the front end wall 7 of the developing unit 1 is rotatably supported by a support arm 71 of a unit carrier 62 as shown in FIG. The entire unit 1 is positioned at a predetermined position in the image forming apparatus main body and is rotatably supported. By pulling the unit carrier 62 forward, the developing unit 1 can be taken out of the image forming apparatus main body while being supported by the carrier 62.

When a visible image is formed with the yellow or magenta developer contained in the second or third developing units 3Y and 3M, the developing unit 1 set at a predetermined position in the main body of the image forming apparatus is used. The driving roller 10 of the second or third developing device 3Y or 3M is driven to rotate clockwise in FIG.
Y and 10M are brought to the developing position where the developing roller 10C of the first developing device 3C shown in FIG. 1 is located to perform the developing operation.

The developing device brought to the developing position, for example, the developing gear 14 of the developing device 3C shown in FIG. 1 rotates counterclockwise in FIG. 1 as described above.
As shown in FIG. 4, the rotation of the drive gear 111 fixedly supported on the independent drive shaft 110 is engaged with the developing gear 14 of the developing roller 10 brought to the developing position and transmitted thereto. When the developing unit 1 is rotated by the driving motor 88 to bring the developing rollers 10Y and 10M of the other developing units 3Y and 3M to the developing position, similarly, the developing gears 14Y and 14M mesh with the driving gear 111 and rotate. Driven.

The centers of the developing gears 14C, 14Y, and 14M attached to the shafts 13 of the developing rollers 10C, 10Y, and 10M are located around the rotation center O of the developing unit 1 as shown in FIGS. They are arranged at equal intervals and at equal distances from the center. Further, the rotation center O 'of the development gear at the development position, the rotation center O of the development unit 1, and the rotation center O "of the drive gear 111 that is immovable on the same straight line L or substantially on this straight line L. When the developing gears 14C, 14Y, and 14M revolve around the center O by rotation of the developing unit 1 about the center O, the developing gears 14
11 can be engaged in a predetermined state without interference.

As described above, each of the developing rollers 10C, 10C
Y, 10M, developing gears 14C, 14Y, 14M
Is provided around a rotation center O of the developing unit 1 so as to be rotatable with respect to the unit 1, and further, a driving gear 111 with which the developing gears 14 </ b> C, 14 </ b> Y, and 14 </ b> M selectively mesh with the rotation of the developing unit 1 is It is supported by a part other than 1 in a fixed position.

By the way, as described above, the drive gear 111 is fixedly arranged, and the developing gear is revolved so that the drive gear 111 is revolved.
1 is selectively meshed with one of the developing gears 14 </ b> C, 1 </ b> C with the rotation of the developing unit 1.
When 4Y or 14M starts to engage with drive gear 111, as shown in FIG. 7, the teeth of developing gear 14C, 14Y or 14M and drive gear 111 abut against each other, and these gears stop and stop. Or the gear teeth may be cut.

Therefore, in one embodiment according to the present invention, in order to solve such inconvenience, the following configuration is provided. 3 and 4, an input shaft 51 to which an input gear 52 is fixed is rotatably supported by side plates 102 and 104 of the apparatus main body. Drive power is transmitted to the input shaft 51 from a main body of the apparatus by a timing belt or the like (not shown). Drive shaft 110 holding drive gear 111 at the end
Is rotatably supported by side plates 102 and 104 in parallel with the input shaft 51. The drive shaft 110 is provided with a clutch (developing clutch) 60, and the clutch 60 is provided with a gear 101. This gear 101
Are meshed with the input gear 52 described above. Therefore,
When the clutch 60 is turned on, the rotational power of the input shaft 51 is transmitted to the developing drive shaft 110 via the gear 52 and the gear 101.

When a developing device of a certain color performs a developing operation, a drive motor 88 for rotating the developing unit 1 is turned on,
In the example of FIG. 3, the developing unit 1 is rotated counterclockwise by the drive gear rotating clockwise. And
By stopping the developing device of a predetermined color at the developing position and thereafter turning on the developing clutch 60 at a predetermined timing, the rotational power of the input shaft 51 is transmitted to the developing drive shaft 110 as described above, and the developing As the drive gear 111 rotates, rotational power is transmitted to the developing device (to the developing gear 14).

FIG. 5 is an exploded perspective view showing the structure of the engaging portion between the developing drive gear 111 and the developing drive shaft 110 in this embodiment. As shown in FIG. 5, the engaging portion between the developing drive gear and the developing drive shaft includes a drive shaft 110, a drive gear 111, a joint member 112, an elastic member 113, and a retaining ring 114.

The drive shaft 110 has a flat portion 110a formed near one end thereof. In addition, the flat portion 11
0a has a small diameter portion 110b. The joint member 112 has a predetermined thickness (the thickness of the drive shaft 110 in the axial direction)
And a shaft hole 112a is formed at the center thereof. The shaft hole 112a fits into the drive shaft 110, and is adapted to correspond to the flat portion 110a.
A part of the shaft hole 112a is a flat part. Thus, when the joint member 112 is fitted on the drive shaft 110, the drive shaft 110 and the joint member 112 rotate integrally. A plurality of (four in this embodiment) projections 112b are provided on the outer end surface of the joint member 112. The four protrusions 112b are arranged so that the elastic member 113 can be fitted to the outside (outer periphery). A notch 112c for locking the elastic member 113 is formed.

The elastic member 113 is a torsion spring whose both ends are bent to form locking portions 113a and 113b. The engaging portion 113a is engaged with the notch 112c of the joint member 112, and the engaging portion 113b is engaged with one of the protrusions 111b of the drive gear 111, which will be described later.

The shaft hole 111a of the developing drive gear 111 has a circular shape. When the gear 111 is fitted to the drive shaft 110, the drive gear 111 alone can rotate freely.
That is, the drive gear 111 alone is not fixed to the drive shaft 110 and can rotate with respect to the drive shaft 110.

As shown in FIG. 4, the developing drive gear 111 has an indented concave shape as shown in a side sectional view of FIG.
Four projections 111b are formed in the recess. The projection 112b of the joint member 112 can enter the space between the four projections 111b. Further, a space is provided on the outer peripheral side of the four protrusions 111b so that the elastic member 113 can fit therein.

The retaining ring 114 is a so-called E-ring, and three projections at both ends and a central portion thereof fit into the small diameter portion 110b at the tip of the drive shaft 110. And the driving gear 11
1 (and the joint member 112 and the elastic member 113) are prevented from coming off.

Now, the joint member 112 and the elastic member 1
13, the driving gear 111 is fitted into the driving shaft 110 in this order,
FIG. 4 shows a state where the retaining ring 114 is used to prevent the retaining ring. As can be seen from FIG. 4, the inner (upper in FIG. 4) end face of the joint member 112 abuts on the inner end face of the drive shaft flat portion 110 a, thereby restricting the movement inward in the axial direction.

When each member is fitted to the drive shaft 110,
The protrusion 112b of the joint member 112 is
1 into the space between the protrusions 111b, and the protrusions 11b
The joint member 112 and the drive gear 111 contact each other in a state where the protrusions 2b and the protrusions 111b are staggered (see FIGS. 4 and 6). At this time, the elastic member 113 is held inside (inner circumference) of the joint member 112 and the drive gear 111 (see FIG. 4), and the locking portion 113a of the elastic member 113 is notched 112 of the joint member 112.
c, the engaging portion 113b is engaged with the projection 111b of the drive gear 111 (or the engaging portion 113b may be engaged by providing an engaging groove in the drive gear 111).

The joint member 112, the elastic member 113,
The drive gear 111 is fitted into the drive shaft 110 to
When the retaining is performed in step 4, the protrusion 112b of the joint member 112 and the protrusion 111b of the drive gear 111 are staggered as shown in FIG. At this time, the elastic member 113 urges the drive gear 111 in the counterclockwise direction in FIG. 6, and as a result, in FIG. 6A, the left side surface of the protrusion 111 b of the drive gear 111 and the protrusion of the joint member 112 The right side surface of the portion 112b is in contact. The state in FIG. 6A is an initial state due to the action of the elastic member 113.

As described above, a flat portion is formed in the shaft hole 112a of the joint member 112, and the flat portion matches the flat portion 110a of the drive shaft 110.
The joint member 112 cannot rotate with respect to the drive shaft 110. On the other hand, the shaft hole 111a of the drive gear 111
Has a circular shape, and the drive gear 111 can rotate with respect to the drive shaft 110. In FIG. 6, as can be seen from the white space on the circumference where the protrusions 112 b of the joint member 112 and the protrusions 111 b of the drive gear 111 are alternately arranged, The portion 111b is movable in the circumferential direction,
As shown in FIG. 6B, the drive gear 111 can rotate by the angle θ until the right side of the protrusion 111b contacts the left side of the protrusion 112b.

That is, when any external force such as rotating the drive gear 111 clockwise acts on the drive gear 111 in the initial state shown in FIG.
As shown in (b), the drive gear 111 can rotate clockwise (clockwise in FIG. 6) by the angle θ. When the external force rotating the drive gear 111 disappears, the drive gear 111 is actuated by the action of the elastic member 113 interposed between the joint member 112 and the drive gear 111.
Is rotated counterclockwise (counterclockwise in FIG. 6),
It quickly returns to the initial state of FIG.

As described above, the driving gear 111 is
With reference to FIG. 3, description will be given of an operation resulting from relative rotation by a predetermined angle.

As described above, when the developing device of a certain color performs the developing operation, the driving motor 88 for rotating the developing unit 1 is turned on, and in the example of FIG. 1 is rotated counterclockwise. Then, the developing device of a predetermined color is stopped at the developing position. At this time, as shown in FIG. 3, the developing gear 14 attached to the developing roller rotates counterclockwise, and the developing gear 14 meshes with the main body side driving gear 111 at the developing position.

When the developing gear 14 meshes with the driving gear 111, the driving gear 111 rotates clockwise in FIG. 3, that is, the teeth of the developing gear 14 moved by the rotation of the developing unit 1 come into contact with the teeth of the driving gear 111. Drive gear 1
11 is rotatable in the direction in which it rotates (in this embodiment, it is rotatable by an angle θ), so that even if the teeth of the developing gear 14 and the teeth of the drive gear 111 abut, the drive gear 111 rotates. By doing so, the impact at the time of abutment can be reduced.

Thus, when the developing gear 14 is revolved by the rotation of the developing unit 1 to selectively mesh with the driving gear 111, the developing gear 14 when the developing gear 14 starts to be engaged with the driving gear 111. There is no problem such as stoppage of these gears or breakage of the gear teeth due to abutment between the tip of the drive gear 111 and the tip of the drive gear 111.

In the present embodiment, the angle at which the drive gear 111 can rotate (the angle at which the drive gear 110 can rotate) θ is set to be larger than the angle of one peak of the teeth of the drive gear 111. Is set. Therefore, even when the developing gear 14 and the driving gear 111 collide, the impact of the collision can be reliably absorbed and reduced.

Then, the developing unit 1 is rotated to switch the developing color, and the developing gear 14 meshed with the driving gear 111 moves, and the driving gear 111 and the developing gear 14
Is released, the drive gear 111 is in the initial state (the state of FIG. 6A) by the action of the elastic member 113 interposed between the joint member 112 and the drive gear 111.
Quickly return to Accordingly, it is possible to prepare for a collision between the developing gear 14 and the driving gear 111 when the next developing device moves to the developing position. Since the drive gear 111 is quickly returned to the initial state, it is possible to cope with a high-speed (fast switching of the developing device) color copier or the like.

In the present embodiment, the drive gear 111 on the main body is provided with a structure in which the gear can be rotated by a predetermined angle with respect to the drive shaft.
Alternatively, the developing gear 14 may be configured to be rotatable by a predetermined angle with respect to its drive shaft. In that case, the developing gear 1
At the time of collision between the drive gear 4 and the drive gear 111, the impact is reduced by the rotation of the developing gear 14. Also,
In this configuration, when the developing unit 1 rotates counterclockwise in FIG. 3, the developing gear 14 rotates clockwise (by rotation of the developing unit 1) when the developing gear 14 and the drive gear 111 abut. The developing gear that can rotate by a predetermined angle is rotated (in a direction in which the developing gear is rotated by the driving gear of the partner).

In the present embodiment, the joint member 1
Although the elastic member 113 interposed between the drive gear 12 and the drive gear 111 is a torsion spring, another elastic member may be used. That is, since it is an elastic member for returning the drive gear 111 to the initial state, an elastic member other than the torsion spring can be used as long as the drive gear 111 can be returned to the initial state. However, since it is a member arranged on the gear and its drive shaft, etc.,
By using a helical spring-shaped torsion spring, it is possible to make the configuration for enabling the drive gear to rotate with respect to the drive shaft and the configuration for returning the drive gear to the initial state simpler.

Some developing units have an auger-shaped toner replenishing member (or conveying member, hereinafter collectively referred to as a toner replenishing member). Of course, in a developing device having such a toner supply member, it is necessary to drive the toner supply member. The driving method of the toner replenishing member includes a method of rotating a gear (hereinafter, referred to as a replenishing portion gear) of the toner replenishing member by interposing an intermediate gear or the like from a developing gear driven by a driving gear of the main body, and a method of driving the developing gear. There is a type in which the supply unit gear is driven by a main body driving gear separate from a type in which the driving unit is driven.

Therefore, a color image having a revolver type developing device having a structure in which a toner replenishing member is provided for each color developing device and in which the replenishing portion gear is driven by a main body driving gear separate from that for driving the developing gear. In the forming apparatus, when the revolver is rotated to stop the developing device at the developing position, the replenishing portion gear and the main body driving gear may collide with each other. In this case, breakage of the gear teeth may occur, or correct engagement between the supply gear and the main body drive gear may not be achieved.

Therefore, as another embodiment of the present invention, the developing gear and the main body driving gear in the above embodiment are disposed between the supply section gear of the toner replenishing member provided for each color developing device and the main body driving gear. It is proposed to provide a configuration that allows one of the gears to rotate by a predetermined angle with respect to its axis, as provided.

In this embodiment, the main body drive gear may be provided with a structure in which the drive gear can be rotated by a predetermined angle with respect to its axis, or the supply section gear and the supply section gear may be provided on its axis. Alternatively, a configuration that allows rotation by a predetermined angle may be provided. As for the configuration in which each gear is rotatable by a predetermined angle with respect to its axis, the same configuration as the configuration in which the drive gear 111 in the above-described embodiment is rotatable can be used. I do.

According to this embodiment, even when the replenishing portion gear and the main body driving gear abut against each other, breakage of the gear teeth can be prevented, and the replenishing portion gear and the main body driving gear can be properly engaged. .

Another embodiment of the present invention is to provide a structure in which the gears of the respective parts can be rotated by a predetermined angle with respect to their axes in both the developing gear part and the replenishing part gear part. I do.

In this embodiment, in the developing gear section,
Either the developing gear or the main body driving gear is provided with a configuration that allows the gear to rotate by a predetermined angle with respect to its axis. , The gear is rotatable by a predetermined angle with respect to the shaft. Since a specific configuration can be the same as that of the first embodiment, the description is omitted.

According to this embodiment, even when the developing gear and the main body driving gear abut against each other, breakage of the gear teeth can be prevented, and the developing gear and the main body driving gear can be properly engaged. In addition, even when the replenishment portion gear and the main body drive gear abut against each other, breakage of the gear teeth can be prevented, and correct engagement between the replenishment portion gear and the main body drive gear can be achieved.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to these embodiments. For example, the rotation direction of the revolver, the rotation direction of each gear, and the like in the embodiment are merely examples, and can be set as appropriate. Further, the structure of the developing device is only an example, and the present invention can be applied to a developing device having a structure different from that of the embodiment. Further, a configuration in which the developing gear, the replenishing unit gear, the main body driving gear, and the like can be rotated by a predetermined angle with respect to the axis is also an example. A configuration can also be employed.

[0061]

As described above, according to the color image forming apparatus of the present invention, one of the developing gear and the driving gear is configured to be rotatable by a predetermined angle with respect to the axis of the gear. Therefore, even when the tooth tips of the gears abut against each other, problems such as breakage of the tooth tips or rotation stop due to rotation of one gear can be prevented.

According to the second aspect of the present invention, either the replenishing portion gear or the drive gear is configured to be rotatable by a predetermined angle with respect to the gear shaft. Even in this case, it is possible to prevent problems such as breakage of the tooth tip and rotation stop due to rotation of one gear.

According to the third aspect of the invention, either the developing gear or the developing drive gear is configured to be rotatable by a predetermined angle with respect to the axis of the gear, and the replenishing unit gear or the replenishing unit driving gear is rotated. Is configured to be rotatable by a predetermined angle with respect to the shaft of the gear, so that even when the tips of the gears abut against each other, the breakage of the tips is caused by the rotation of one of the gears. Troubles such as rotation stoppage and the like can be prevented.

According to the fourth aspect of the present invention, the gear rotatable by a predetermined angle is rotated by the gear of the meshing partner due to the rotational force of the revolver type developing unit when meshing with the gear of the meshing partner. , It is possible to receive the impact force of the gear of the meshing partner. Therefore, problems such as breakage of the tooth tip and stop of rotation can be prevented.

According to the fifth aspect of the present invention, a gear rotatable by a predetermined angle is rotatable with respect to the gear shaft by an angle equal to or more than one tooth of the gear. Even if a collision occurs, it is possible to reliably avoid an impact.

According to the configuration of claim 6, when the external force for rotating the gear rotatable by a predetermined angle is lost, the gear rotatable by the predetermined angle is restored to the initial state. Since the elastic member is provided, it is possible to cope with meshing with the gear of the next developing unit when the developing unit is rotated and the next developing unit comes to the developing position. In addition, since it can be quickly returned to the initial state, it is possible to cope with a high-speed color image forming apparatus.

According to the seventh aspect of the present invention, since the elastic member is a torsion spring, a gear configured to be rotatable by a predetermined angle with a simple configuration can be restored to the initial state.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall structure of a developing unit in a color image forming apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view of the developing unit of FIG.

FIG. 3 is a side view illustrating a configuration of a drive transmission unit to the developing unit in FIG. 1;

FIG. 4 is a partial plan view showing the configuration of the drive transmission unit.

FIG. 5 is an exploded perspective view showing a configuration of an engaging portion between a developing drive gear and a developing drive shaft in the embodiment.

FIGS. 6A and 6B are cross-sectional views illustrating a state in which a developing drive gear rotates by a predetermined angle with respect to a developing drive shaft in the present embodiment, wherein FIG. 6A illustrates an initial state, and FIG. It is.

FIG. 7 is an explanatory view showing a state in which the tooth tips of the gear are in contact with each other.

[Explanation of symbols]

 Reference Signs List 1 developing unit 3C, 3Y, 3M developing device 14 developing gear 110 drive shaft 111 drive gear 112 joint member 113 elastic member (torsion spring)

Claims (7)

[Claims] 1. A color image forming apparatus comprising a revolver type developing unit for integrally supporting a plurality of developing units so as to be rotatable, wherein each of the developing units transports the developing agent to a developing area. In a color image forming apparatus having a conveying member, a developing gear provided for each of the developing units for driving a developer conveying member, and transmitting a driving force by meshing with the developing gear at a developing position of each developing unit. A drive gear provided on the image forming apparatus main body side, wherein one of the developing gear and the drive gear is configured to be rotatable by a predetermined angle with respect to an axis of the gear. Color image forming apparatus. 2. A color image forming apparatus comprising a revolver-type developing unit that supports a plurality of developing units so as to be integrally rotatable, wherein each of the developing units transports the developing agent to a developing area. In a color image forming apparatus having a transport member, a replenishing unit gear for driving a developer replenishing member that is provided for each of the developing units and replenishes a developer to a developing chamber, and the replenishing unit is provided at a developing position of each of the developing units. A drive gear provided on the image forming apparatus main body side that meshes with an external gear to transmit a driving force, wherein one of the replenishment unit gear and the drive gear has a predetermined angle with respect to an axis of the gear. A color image forming apparatus configured to be rotatable only by rotation. 3. A color image forming apparatus comprising a revolver type developing unit integrally rotatably supporting a plurality of developing units, wherein each of the developing units carries a developer to a developing area. In a color image forming apparatus having a conveying member, a developing gear provided for each of the developing units for driving a developer conveying member, and transmitting a driving force by meshing with the developing gear at a developing position of each developing unit. A developing drive gear provided on the image forming apparatus main body side; a replenishing unit gear provided for each of the developing devices for driving a developer replenishing member for replenishing a developer to a developing chamber; A replenishing unit drive gear provided on the image forming apparatus main body side that transmits a driving force by meshing with the replenishing unit gear at a position, and either one of the developing gear or the developing drive gear is
While being configured to be rotatable by a predetermined angle with respect to the axis of the gear, one of the replenishment unit gear and the replenishment unit drive gear is rotatable by a predetermined angle with respect to the axis of the gear. A color image forming apparatus comprising: 4. The gear configured to be rotatable by the predetermined angle is rotatable in a direction rotated by the gear of the meshing partner due to the rotational force of the revolver type developing unit when meshing with the gear of the meshing partner. 4. The color image forming apparatus according to claim 1, wherein: 5. The gear configured to be rotatable by the predetermined angle is rotatable with respect to an axis of the gear by an angle equal to or more than one tooth of the gear. 4. The color image forming apparatus according to any one of items 1 to 3. 6. An elasticity for restoring a gear configured to be rotatable by the predetermined angle to an initial state when there is no external force for rotating the gear configured to be rotatable by the predetermined angle. 4. The color image forming apparatus according to claim 1, further comprising a member. 7. The color image forming apparatus according to claim 6, wherein said elastic member is a torsion spring.