JP2729372B2 - Rotary developing device for image forming apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a case in which developers of different colors are stored, respectively.
And a plurality of developing units, and rotate facing the latent image carrier
It has a freely supported developing unit, and each developing unit has:
The developer in the developer chamber is transferred to the electrostatic image formed on the latent image carrier.
Conveys the latent image as a toner image to the development area where it is visualized
A developer conveying member, which rotates by rotation of the developing unit.
Each developer transport member to the developing position facing the latent image carrier
A rotary type image forming apparatus that performs a developing operation while being positioned
The present invention relates to an imaging device. Conventional technology Used in image forming apparatuses such as copiers and printers
In a rotary developing device of the type described above, the rotation of the developing unit
Rotates the developer transport member brought to the development position by rotation
Each developer transport member is rotationally driven because it needs to be driven
Developing gear is provided. At that time, individual
When the development gear is driven by separate drive gears,
Not only becomes complicated, but also the structure becomes large,
Is arranged around the rotation center of the developing unit.
In addition, the drive gear is fixed to a position other than the developing unit.
Is brought to the developing position by the rotation of the developing unit.
The developing gear of the developer transport member meshes with the drive gear.
This is advantageous. However, if this configuration is adopted, the rotation of the developing unit
The developing gear revolving around the center correctly meshes with the drive gear.
Interference with each other, and the developing gear may not be able to revolve.
You. To eliminate this drawback, each developing gear must be
Orbit around the center of rotation
With the drive gear retracted to the outside, the developer transport member moves to the developing position.
When it reaches, the drive gear is moved from the retracted position to
It engages with the developing gear of the developer conveying member that has reached the position.
You can do it. However, in this case, the driving gear
Between the retracted position and the operating position that engages the developing gear.
Requires a mechanism to operate, complicating the structure of the device
And the disadvantage of increased costs is inevitable. In a conventional rotary developing device, a developing unit
When the developer transport member reaches the developing position due to the rotation of
Or the developer transport member that had occupied the developing position until then,
When leaving the development position by rotation of the development unit,
Toner on developer transport member adheres to latent image carrier surface
There is a risk. When such toner adhesion occurs,
The adhering toner is mixed into other developing devices, causing color mixing in the developer.
This may cause deterioration of the image quality of the toner image. Object of the present invention is to solve the above-mentioned problems at once.
A developing device of the type described at the beginning can be provided.
And there. Configuration In order to achieve the above object, the present invention has been described at the beginning.
Drive each developer transport member in a rotary type
The developing gear for moving is kept at the center of rotation of the developing unit.
Instead, it is rotatable with respect to the casing of each developing unit.
The developing gear of the developer conveying member occupying the developing position.
Matching drive gears do not move to parts other than the development unit
Of the developer conveying member brought to the developing position.
The rotation center of the developing gear, the rotation center of the drive gear, and the developing unit
The center of rotation of the knit is arranged on almost the same straight line,
The unit starts to rotate and the development position
The developing gear of the developer conveying member rotates around the rotation center of the developing unit.
When the revolution starts, the drive that meshes with the developing gear
While the gear is rotating, the rotation of the developing unit
When each developer conveying member is positioned at the developing position,
Before the developer conveying member reaches the developing position, the developer
The developing gear of the conveying member is engaged with the rotating drive gear,
The rotation of the drive gear is performed so that the development gear starts rotating.
A drive control means for controlling rotation
A roller developing device is proposed. Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. To understand the present invention, first, the image forming apparatus in the present embodiment
Will be clarified from the overall configuration of the rotary developing device. Fig. 1
The rotary developing device shown in FIG.
(The copier main unit)
FIG. 4 shows a state in which the developing unit 1 is pulled out from the body 2.
See). The developing unit 1 includes a plurality,
It has three developing units 3, 3R and 3B embedded therein, as shown in FIG.
The developing unit 1 loaded in the copier body 2 carries a latent image.
Body, in this example, rotatably supported opposite the photosensitive drum 11.
Is held. The developer chambers 4, 4R, 4B of the developing units 3, 3R, 3B are made of aluminum.
Partition walls of the casing member 5 made of a non-magnetic material such as
6, 6R, 6B and two end walls 7, 8 (second
(See FIGS. 3, 3 and 4).
Thus, the casing of the developing unit 1 of this embodiment is
Lacing member 5 and two end walls 7, 8
You. A latent image composed of a photoreceptor belt instead of the photoreceptor drum 11
In some cases, a carrier is used, and the image forming apparatus
Depending on the type, a latent belt consisting of a dielectric belt or a dielectric drum
An image carrier is used. The developer chambers 4, 4R, 4B of the developing units 3, 3R, 3B have different colors from each other.
Developers 9, 9R, and 9B are stored, and in this example, each of these
Assume that the image agents are black, red, and blue, respectively. Each current
Development of cyan, yellow and magenta toners in the image agent chamber
To form a full-color image
You may comprise. Also contains no carrier as developer
Although a one-component developer can be used, in the example shown in FIG.
A two-component developer having a carrier and a toner.
At least a part of a magnetic developer is used
Shall be The first to third developing units 3, 3R, 3B are
Although radially arranged with respect to the rotation center O,
Since the structures are all the same, in the following description, mainly
The structure of the first developing unit 3 is clarified, and the other developing units 3R and 3B
Are attached to each element of the first developing device 3
R and B are attached to the reference numerals, and the duplicate description will be omitted. The developing unit 1 rotates around its rotation center O.
Each developing unit (more precisely, the developing
Roller) is rotated to a predetermined developing position to perform a developing operation.
However, FIG. 1 shows a state in which the first developing device 3 occupies the developing position.
Is shown. In FIG. 1, a developer provided in a first developing device 3
The transport roller, in the illustrated example, the developing roller 10 has two partition walls 6, 6R.
A part is exposed from the opening formed by the step (see also FIG. 4).
The developing roller 10 is rotatable with respect to the copying machine body 2.
Occupies a predetermined developing position with respect to the supported photosensitive drum 11.
I'm worried. At this time, the developing roller 10 faces the photosensitive drum 11
Are positioned in parallel with a predetermined minute gap. As can be seen from FIG. 3, both support shafts 12 and 13 of the developing roller 10 are provided.
Are rotatably supported on both end walls 7 and 8 of the developing unit 1, respectively.
At the back of the copying machine body 2 (left side in FIGS. 2 and 3)
One of the support shafts 13 penetrates the end wall 8 and has a developing gear
A 14 is fixed. Thus, the developing gear 14
Along with the roller 10, the end wall 7 of the casing of the developing unit 1,
8 rotatably supported. As shown in FIG. 1, a large number of
An impeller 16 having an impeller 15 is arranged, and the impeller 16 is
And is parallel to the developing roller 10.
Integral with the feed screw shaft 17 and the impeller 16
1 by the rotation of the screw shaft 17.
It is driven to rotate clockwise. This allows the developer chamber 4
While the developer, i.e., toner and carrier, are agitated,
To the toner 10 and stirred by the toner and carrier.
Is triboelectrically charged to a predetermined polarity. Feed screw
A screw 18 is formed on the shaft 17 over almost the entire length thereof.
ing. One end of the feed screw shaft 17, that is, a copy machine
The left end of FIG. 2, which corresponds to the back side of the body 2, is the developing unit.
Rotatably penetrates the casing end wall 8 of the
A feed gear 19 is fixed to the end, and through this gear 19
The shaft 17 is driven to rotate together with the impeller 16. In addition,
The other end of the screw shaft 17, that is, the front end of the copier body 2.
Is fixed to a hole in the casing end wall 7 of the developing unit.
Penetrated through the supply pipe 20, and was rotatably supported by the pipe 20.
I have. The inside of the developing roller 10 is shown by adding S and N to FIG.
As described above, the magnet 21 having the magnetic pole composed of the S pole and the N pole is developed.
It is fixed to the casing of the unit 1.
As a result, the developing roller 10 is moved via the developing gear 14 described above.
When the developing roller 10 is driven to rotate counterclockwise in FIG.
The magnetic developer 9 supplied to the developing device is developed by the magnetic force of the magnet 21.
The sheet is carried on the surface of the roller 10 and is conveyed counterclockwise. Carrying
The developer to be sent is a doctor fixed to the casing member 5.
-After being scraped by the blade 22, the blade 22
A predetermined amount of developer that has passed through the
Sent to Ram11. On the other hand, the photosensitive drum 11 rotates clockwise in FIG.
It is driven to rotate, and a charging / exposure
An electrostatic latent image corresponding to the original (not shown) image
Are formed. This latent image is transferred to the photosensitive drum 11 and the developing drum.
When the roller 10 reaches the opposing development area D, the area D
Charged toner in the developer transported to the electrostatic latent image
And the latent image is visualized as a toner image. This toner image is printed on a transfer paper (not shown).
Transferred toner by non-transfer device
The image is fixed by a fixing device (not shown). Development area
The developer that has passed through D is returned to the inside of the developer chamber 4 again.
Mixed with other developers in this room and ready for use again.
Is done. The developer scraped by the doctor blade 22 is
Guided by guide member 23 in the direction indicated by arrow B,
Feed screw shaft 24 parallel to the screw screw shaft 17
To a screw, as described below.
The developer is conveyed out of the developer chamber by the shaft 24, and the other developer is
In FIG. 3 and FIG.
And flows down to an impeller 16 located at the bottom of the developer chamber 4,
Receives stirring action. As can be seen from FIGS. 1 to 3, the guide member 23
It has a gutter-like part 25 that covers almost the lower half of the extension screw shaft 24.
Each end of the guide member 23 is
Are fixed to the end walls 7 and 8 of the housing. Sending out
One end of the screw shaft 24 (the left end in FIG. 2) is the back side
Is rotatably supported by the end wall 8 and penetrates the end wall 8
At the foremost point, the feed screw shaft 24 is driven.
Delivery gear 26 is fixed. Also send out
The other end of the screw shaft 24 (the right end in FIG. 2) is
Penetrates the inside of the discharge pipe 27 fitted and fixed in the hole of the side end wall 7
The tube 27 is rotatably supported. Sending out
A screw 28 is also formed on the screw shaft 24, and this screw
The screw 28 may be formed over the entire length of the screw shaft 24.
However, in the example of the figure, the shaft portion fitted to the discharge pipe 27 and the
The screw 28 is formed only on a part of the shaft inside the developer chamber.
Has been established. Also, the screw shaft 24 sent out from the doctor blade 22
The developer that has flowed into the portion of the screw 28
The feed screw shaft 24, which is rotationally driven via
By the screw 28, the right side of FIG.
Towards the front side, transport while being guided by the gutter-shaped part 25 and the discharge pipe 27
The developer is sent to the outside of the developing unit end wall 7. As shown in FIG. 2, the discharge pipe 27 and the aforementioned supply pipe 20 are connected.
It communicates via the pipe 31 and conveys through the discharge pipe 27 as described above.
The sent developer passes through a connecting pipe 31 as shown by an arrow E.
After flowing into the supply pipe 20, the rotation is driven by the feed gear 19.
The screw 18 of the feed screw shaft 17
2 while being guided through the boss portion 32 of the impeller 16
, That is, toward the back side of the copying machine main body 2. Back side
The developer sent to the opening at the back end of the impeller 16 and the
The developer is discharged into the developer chamber 4 through an exit hole 33 formed in the vicinity.
You. As the developing operation proceeds, the toner in the developer
Then, the toner is sequentially consumed. Therefore, the developer chamber 4
First, the toner supply device 44 shown in FIG.
The toner is supplied through the supply pipe 20. Other developer chambers 4R, 4
B is also supplied with toner from toner supply devices 44R and 44B
Is done. Next, for understanding of the present invention, the support of the developing unit 1 will be described.
The configuration to be performed will be described. As shown in FIGS. 1 and 4, the slider 62
The hand of the copier body 2 is operated by a well-known slide guide device 61.
Pulled forward (in the direction of arrow G in FIG. 4) or vice versa
To be pushed to the back (also in the direction of arrow H)
It is slidably supported by the machine body 2. This sly
The developing unit housing 63 is supported by the die 62. The slider 62 includes a front support plate 64 and a rear support plate 65 (the
FIG. 5), and a board 66 connecting them.
The support plates 64 and 65 are flat on the slider 62 in the sliding direction.
Each end of the first to third connecting rods 67, 68, 69 extending in a row is
The connecting rods 67, 68, and 69 fix each other.
Holding plates 64 and 65 are reinforced. The storage base 63 is also a support arm 70 on the near side, a support arm on the back side
71 (FIG. 5), and the lower covers 7
2 is fixed. Both support arms 70, 71 and lower cover 72
The third connecting rod 69 of the slider 62 is rotatable in the direction of arrow I
It is pivoted. In addition, the storage table 63 is
The upper cover 75 is pivotably supported in the direction of arrow J,
This upper cover 75 is normally in the closed position shown in FIGS.
(A position indicated by a chain line in FIG. 4). On the other hand, the end wall 7 on the front side of the casing of the developing unit 1
Is formed in a cylindrical shape, and the outer peripheral surface of the end wall 8 on the back side is also
Similarly, it is cylindrical. Both support arms 70, 71
The upper parts 70a and 71a are arc shaped to fit the outer peripheral surfaces of these end walls 7 and 8.
Is formed. The support arm 70 on the near side has two
The supporting rollers 76 and 77 are rotatably supported, and the developing unit
The outer peripheral surface of the end wall 7 on the front side of the slot 1 is
Supported in two places by 76,77. The slider 62
When the developing unit 1 is pulled out from the copying machine main body 2,
As shown in FIG. 5, a cylindrical end on the back side of the developing unit 1
The wall 8 rotates on the arc-shaped upper portion 71a of the support arm 71 on the back side.
It is supported. With these configurations, the developing unit 1
Around the rotation center O while being supported by the storage table 63
Can be rotated. The developing unit 1 supported by the storage table 63 includes a slider 62
Pull out or push in the direction of arrow G as described above.
Pulled out of the copier body 1 by the
1 is set at a predetermined position. When setting the developing unit 1, as shown in FIG.
While holding the developing unit 1 on the storage table 63, the slider 62
Only in the direction of arrow H (FIG. 4). This push
Immediately before the completion of the setting operation, the rear end wall of the developing unit 1
8, which protrudes above the rotation center O of the unit 1.
As shown in FIG. 3, the positioning pin 78 is
Positioning hole 80 drilled in the side plate 79 on the side
The developing unit is fitted to the fitted bearing 81, thereby
1 is located on the main body 2 of the copying machine, and
Positioned with respect to the photosensitive drum 11 supported at the position.
You. At this time, as can be seen from FIG.
It slightly rises from the support arm 71 of the table 63. Therefore
The back side of the image unit 1 is a copying machine
Rotatably supported by the body 2, the position with respect to the photosensitive drum 11
A decision is made. On the other hand, the end wall 7 on the front side remains after the developing unit 1 is set.
While being rotatably supported by the two support rollers 76 and 77
However, it protrudes from the support arm 70 on the near side of the storage table 63
A pin 82 (FIG. 4) is drilled in the front side plate 83 of the copying machine body 2.
Positioning hole or receiving member fitted in it
85 is fitted into the center hole, and the photosensitive drum is
Positioned relative to 11. Also, the back side of the storage table 63 is protruded from the support arm 71.
Pin 86 (Fig. 5) is formed in the side plate 79 on the back side of the main body.
(Not shown) and the back side of the storage table 63 is the copier body 2
Is fixedly supported. In this example, a side plate on the front side of the copying machine main body 2 will be described later.
The movable support roller 87 (the
4) to press the upper part of the front end wall 7
It is configured. For this reason, the
The casing end wall 7 of the set developing unit 1 has 3
Supported from three sides by two support rollers 76, 77, 87,
Image unit 1 is rotating while maintaining its position correctly
It is possible to rotate around the heart O. Development unit
The support roller 87 is moved to the developing unit 1
Run away to avoid interference. The developing operation of the first developing device 3 is as described above.
But the red stored in the second or third developing device 3R, 3B
When forming a visible image with a color or blue developer, use a copier
The developing unit 1 set at a predetermined position in the main body is moved to the first position.
The second or third developing device is driven to rotate clockwise in the drawing.
The developing rollers 10R or 10B of the developing devices 3R and 3B are the same as those shown in FIG.
To the developing position where the developing roller 10 of the developing device 3 is located.
Then, the developing operation is performed. Thus, each developing unit 3, 3R, 3B has its developer chamber 4, 4R,
The 4B developer 9, 9R, 9B is applied to the latent image
Visualizes the electrostatic latent image formed on the carrier as a toner image
As developing rollers 10, 10R and 10B for transporting to developing area D
And a developing unit 1 having the formed developer conveying member.
Each developer transport member faces the latent image carrier by the rotation of
The developing operation is performed by being positioned at the developing position. Developing unit set in copier body as described above
For the purpose of rotating one, it is specified in FIG. 5 and in FIG.
A drive motor 88 is supported on the storage table 63 as schematically shown.
The gear 89 driven by this is located at the back of the developing unit 1.
Meshes with a unit gear 90 formed on the peripheral surface of the side end wall 8
ing. The gear 89 is also supported by the storage stand. Push the developing unit 1 into the copier body 2 and set it.
The color conversion key switch (not shown)
When a switch is selected and pressed, the drive motor 88 operates.
Then, a clutch interposed between the motor 88 and the gear 89 is turned off.
And the developing unit 1 replenishes the toner attached thereto.
Rotate around its center of rotation O together with the devices 44, 44R, 44B
You. The developing device selected thereby, for example, the first developing device
The third developing roller 10 reaches the developing position, where
Switch turns off, the developing unit 1 stops, and the current
An image operation is performed. Also, the developing roller 10 brought to the developing position,
The screw shaft 24 and the feed screw shaft 17 are
Drive via the gears 14, 26, 19 fixed respectively.
Be moved. In this case, as shown in FIG. 5 and FIG.
The image gear 14 is connected to the delivery gear 26 of the delivery screw shaft 24.
The gear 26 meshes with the feed screw shaft 17
And the developing gear 14 is rotationally driven.
As a result, the other two gears 26 and 19 are rotationally driven.
You. The same applies to the gears of the other developing units. At this time, the developing gears of the individual developing units are driven by individual driving sources.
Drives can increase the size of equipment and increase costs
Is not preferred. Therefore, FIG. 3 and FIG.
As shown in FIG.
Drive gear 111 is rotatable around the shaft 110 of the photosensitive drum 11
Although it was supported in a stationary position, it was brought to the development position,
For example, the gear 14 of the developing roller 10 of the first developing device 3 is driven by a driving gear.
A by engaging a motor (not shown)
Therefore, the developing roller 1 is moved through these gears 111, 14, 26 and 19.
0 and the screw shafts 24, 17 are rotationally driven. Each developing gear 1
The center of 4, 14R, 14B is around the rotation center O of the developing unit 1.
At equal intervals and at the same distance from the center O.
Is placed. FIG. 6 shows the developing row of the first developing unit 3 as in FIG.
Gear 10 occupies the developing position, and its gear 14 meshes with the drive gear 111.
It shows the state of matching, but the development of other developing units 3R and 3B
To engage the gears 14R and 14B with the drive gear 111,
The gear 89 and the unit of the developing unit 1 are
The developing unit 1 in the clockwise direction (the arrow
(Q direction). Thereby, each developing gear 14,
R and 14B are public around the rotation center O of the developing unit 1.
And the other developing gears 14R and 14B are moved to the developing gears shown in FIG.
A) to selectively engage the drive gear 111
I can make it. The drive gear 111 is moved to the photosensitive drum 11
May be supported on a portion other than the shaft 110 of the developing unit 1.
It can be supported at any other suitable position. As described above, each developing roller 10, 10 R, and 10 B
Developing gears 14, 14R, and 14B for driving the developer conveying member
Around the rotation center O of the image unit 1, each of the developing devices 3, 3R, 3
It is arranged rotatable with respect to the casing of B, and the developing position
Meshed with the developing gears 14, 14R, 14B of the developer conveying member
The drive gear 111 is not positioned in a part other than the developing unit 1.
It is supported by movement. According to such a configuration,
Image gears 14, 14R, 14B around the rotation center of developing unit 1.
, And selectively mesh with the drive gear 111,
One for each developing roller 10, 10R, 10B brought to the developing position
Can be driven. Here, as shown in FIG. 6 and FIG.
The rotation center of the developing gear 14 is O ', and the rotation of the driving gear 111 is
Assuming that the center is O ", as shown in FIG.
The centers O, O ', O "of the gears 111, 14, 90 are not aligned
In addition, ∠OO'O ”= β forms an angle that is significantly smaller than 180 °.
Assuming that the gears are positioned as described above, the developing gears 14 and 1
When 4R and 14B revolve around the center O in the direction of arrow Q,
These gears hit the drive gear 111, and their revolutions are not correct.
It becomes possible. To eliminate this inconvenience, the development gear must be
During rotation, the drive gear 111 is revolved along the orbital path of the developing gears 14, 14R and 14B.
When the developing gear reaches the developing position,
Moved gear 111 from the retracted position to reach the developing position
It is sufficient to engage with the developing gear.
, The drive gear 111 is engaged with the retracted position and the developing gear.
No mechanism is required to operate between matching operating positions.
This complicates the configuration. Therefore, in the rotary developing device of this example, FIG.
As shown, the developing roller 10 is brought to the developing position.
The developing gear 14 of the developer conveying member (other developing gears 14R, 14B
The same applies to the case of
111 and the rotation center O of the developing unit 1
Are arranged on substantially the same straight line l. Like this
If the developing unit 1 rotates around its center O
And the developing gears 14, 14R, 14B
Meshes with the drive gear 111 while moving almost in the tangential direction
The developing gear projects from the driving gear 111 as shown in FIG.
The collision can be prevented. As shown in FIG. 8, the drive gear 111 is in the developing position.
Can be arranged inside the gear 14 of the developing roller 10
However, also in this case, the center O ′, O ″ of the two gears 14, 111 is
The rotation center O of the image unit 1 is arranged substantially on a straight line l.
As a result, each developing gear strikes the drive gear 111 and appears.
The rotation of the image unit 1 can be prevented from being disabled. As described above, the developing roller 10 located at the developing position is
The rotation center O 'of the developing gear 14 to be driven and the developing unit 1
The rotation center O ″ of the drive gear 111 is located between the rotation centers O.
When the drive gear 111 is arranged as shown in FIG.
As illustrated, the developing unit 1 is removed from the copying machine main body 2.
When it comes out, you can touch the drive gear 111 as it is
Easy maintenance work such as replacement
Can be done. As shown in FIG.
When the drive gear 111 is mounted on the shaft 110 of the ram 11, the photosensitive drum
If the gear 11 also does not separate from the copying machine body 2,
Maintenance work cannot be performed on
The work becomes somewhat complicated. By the way, the rotation of the developing unit 1
When the developing roller is brought to the developing position,
Developer toner adheres to the surface of the photosensitive drum 11
The adhering toner is mixed into the developer of other developing units
However, color mixture occurs in the developer, and the image quality of the toner image deteriorates.
Further, the developing unit 1 starts rotating, and the developing position
When the developing roller occupying the position leaves the developing position,
Of the developer on the developing roller of the photosensitive drum 11
Similar phenomena occur even if they adhere to the surface. Therefore, in the rotary developing device of the present embodiment, the developing unit
When the developing unit 1 starts rotating and the developing unit occupying the developing position is
The developing gear of the developer transport member consisting of the roller
When the revolution starts around the rotation center of No. 1
While the drive gear 111 meshing with
The rotation of the image unit 1 moves each developer conveying member to the developing position.
When the developer conveying member is positioned at the developing position,
Before the developer reaches the developer gear,
The developing gear starts rotating.
To control the rotation of the drive gear.
Steps are provided. The timing of the rotation start of the drive gear 111 is determined by the color conversion key described above.
When the developing unit 1 starts rotating by pressing the switch,
The drive gear 111 may be started to rotate at the same time,
The drive gear 111 rotates whenever the power of the
You may keep it. In short, the current development position was occupied.
The image roller revolves around the rotation center of the developing unit 1.
When started, the drive gear 111 is rotating,
The developing gear of the developing roller rotates,
May be driven to rotate. In the illustrated example, the developing gear 14, 14R or 14B
By the time immediately before starting to mesh with the drive gear 111, the drive
The gear 111 is already set in the clockwise direction (direction of arrow R) in FIG.
Has started to rotate. Each rotation of the developing unit 1
The developing gear revolves around the rotation center O of the developing unit 1
And one of the developing gears engages with the driving gear 111.
Sometimes, as if this drive gear 111 is already rotating,
Drive control means for controlling the rotation of the drive gear 111 is provided.
It is being done. The aforementioned mode for driving the drive gear 111
And a control unit (not shown) of the drive control means.
Make up an example. Before a certain developing roller reaches the developing position
Then, the developing gear of the developing roller starts rotating, and the current
The configuration is such that the image roller rotates. According to the above configuration, the developing roller occupying the developing position
When the developer leaves the developing position, the developing roller
1 and is driven to rotate on the developing roller.
The toner is agitated by the rotation of the developing roller,
Is charged. Therefore, the toner is held on the developing roller.
As a result, it is difficult to adhere to the surface of the photosensitive drum 11. Similarly,
When a certain developing roller is positioned at the developing position,
Since the developing roller starts rotating before reaching the developing position,
The toner on the developing roller is stirred by the rotation of the developing roller.
Receiving agitation, it is positively charged and kept on the side of the developing roller.
So that it hardly adheres to the surface of the photosensitive drum. like this
To prevent color mixing of the developer and form it on the photosensitive drum 11.
The image quality of the formed toner image can be improved. The developing roller moves away from or reaches the developing position
When the developing roller stops rotating (rotating)
And the charge amount of the toner on the developing roller decreases,
The toner easily adheres to the surface of the photoconductor drum and develops.
Although color mixing occurs in the developer, such a developing device
Defects can be effectively suppressed. Moreover, when the developing unit 1 rotates, the developing unit 1 is completely moved from the developing position.
The developing roller that is completely away does not rotate (rotate),
This prevents the toner on the developing roller from scattering.
Can be effectively suppressed. In the illustrated example, the driving gear 111 is engaged with the developing gear.
The direction of rotation R is the clockwise direction in FIG.
The direction in which the developing gear revolves around the center O is also indicated by an arrow.
Clockwise as indicated by Q. That is, the developing gear and the drive
When the gear 111 engages with each other, the gear 111
The direction of movement of both is reversed, and the engagement of both
Direction of the developing unit
The direction of rotation is set. For this reason, the tip of both gears
However, as shown in FIG. 9, the problem of interference is reliably avoided.
Yes, both gears are immediately suitable without major impact
It will be in a good meshing state. The drive gear 111 is arranged as shown in FIG.
When the developing roller is driven counterclockwise, the driving gear 11
The direction of rotation of 1 is clockwise.
Rotate the knit 1 counterclockwise, and move each developing gear
Orbit, and this is the drive gear 111 that has started to rotate.
On the other hand, a large speed difference
If you do, you will get the same effect as above.
You. Further, as shown in FIG. 10, the developing gears 14, 14R, 14B and the driving gear
A slightly change the shape of the teeth of 111
Even if it is configured that the tooth tips of the
Inconveniences due to interference can be eliminated. That is, both gears 14, 14R, 14B
And 111 teeth are cut out from the normal tooth shape by the dotted line
It is formed in the form which was done. In this way, the development
The gear 14, 14R or 14B rotates around the rotation center O of the developing unit.
Engages with the drive gear 111 while revolving in the direction of arrow Q.
Sometimes, even if the tips of both gears touch each other,
Since the tips 118 contact each other, the contact between the tooth tips is immediately released.
It turns off and it becomes a normal meshing state. The teeth of both gears
One side is cut and the other flank is a regular tooth
Since the shape is the same, the drive gear 11
1 can be transmitted to the developing gear without any trouble.
This is especially true if the configuration shown in FIG.
It is profitable. The present invention is applicable to a plurality of developing devices such as the illustrated developing device.
Are integrally formed by one casing,
The whole is not limited to the developing device that constitutes the developing unit,
Each developer has a separate casing, which is
Developing device with developing unit assembled to rotary unit
Naturally, it can also be applied to. In this case,
A plurality of unit casings are provided. The present invention
The same applies to developing devices in image forming devices such as printers.
It can be applied in various ways. Further, the developer conveying member comprises a developer conveying belt.
Or rotatably mounted on a belt or roller
The present invention can be applied to the case of
In these cases, the
The gear or gear attached to the magnet roller
It becomes gear. According to the present invention, it is possible to drive each developer conveying member.
The developing gear moves around the center of rotation of the developing unit.
It is arranged rotatably with respect to the casing of the image
Drive gear that meshes with the developing gear of the developer conveying member
Is fixedly supported by a part other than the developing unit,
The rotation of the developing gear of the developer conveying member brought to the developing position.
Center of rotation, center of rotation of drive gear, and rotation of developing unit
The center is configured so that they are almost co-linear
The developing gear is almost tangent to the drive gear.
The drive gear meshes while moving in the direction. Because of this, drive
Even if a mechanism to retract the gear is not provided, the developing gear
It can be engaged with a. Moreover, according to the present invention, the developing unit starts rotating.
And the developing gear of the developer conveying member occupying the developing position.
Started revolving around the rotation center of the developing unit
At this time, the drive gear meshing with the developing gear is rotating.
At the same time, each developer transport member is rotated by the rotation of the developing unit.
When the developer conveying member is positioned at the developing position,
Before reaching the developing position, the developing gear of the developer conveying member
Engages with the rotating drive gear, and the developing gear rotates.
Drive control to control the rotation of the drive gear to start
Control means provided to transport the developer occupying the development position
When the member leaves the developing position, the developer conveying member is driven.
The developer is driven to rotate by the gear, and the
The toner is positively charged. As a result, the toner
It is held on the developer transport member side and adheres to the latent image carrier surface.
It becomes difficult. Similarly, the developer conveying member is positioned at the developing position.
Before the developer transport member reaches the developing position
In addition, since the developer conveying member starts rotating, the developer
The toner on the conveying member is positively charged, and the toner is
It becomes difficult to adhere to the surface of the latent image carrier. In this way each current
The occurrence of color mixture between imagers can be effectively suppressed. Also, the developer conveying member completely separated from the developing position is rotated.
The developer on the developer transport member will not fly.
Dispersions can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of a developing device when a developing unit is set in a copying machine main body, and FIG. 2 is II-II in FIG.
FIG. 3 is a cross-sectional view taken along the line, and FIG. 3 is a cross-sectional view of the portion of the toner supply device taken along the line II′-II ′.
FIG. 4 is a cross-sectional view taken along the line III-III, FIG. 4 is a perspective view showing a state where the storage unit is pulled out of the copier body and the developing unit is removed from the storage unit, and FIG. FIG. 6 is an explanatory view for explaining the rotation operation of the developing unit, and FIG. 7 is a problem when the centers of the gears are not arranged substantially in a straight line. , FIG. 8 is an explanatory diagram showing another arrangement of gears, FIG. 9 is an explanatory diagram showing interference between tooth tips, and FIG. 10 is an explanatory diagram showing an embodiment of a gear with a changed tooth profile. FIG. 1. Developing unit, 3, 3R, 3B Developing device 4, 4R, 4B Developing agent chamber, 9, 9R, 9B Developing agent 14, 14R, 14B Developing gear, 111 Drive gear D: developing area, l: straight line, O, O ', O "... center of rotation

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-61-77873 (JP, A)                 JP-A-55-54753 (JP, A)                 Actual opening 58-182049 (JP, U)                 Actual opening 58-62468 (JP, U)

Claims (1)

(57) [Claims] It has a plurality of developing units each containing a developer of a different color from each other, and includes a developing unit rotatably supported opposite to the latent image carrier, and each developing unit is provided with a developing unit in its developer chamber. A developer transport member for transporting the developer to a developing area where the electrostatic latent image formed on the latent image carrier is visualized as a toner image, and each developer transport member is rotated by rotation of the developing unit. In a rotary developing device of an image forming apparatus that performs a developing operation by being positioned at a developing position facing an image carrier, a developing gear for driving each developer conveying member is provided around a rotation center of the developing unit. A drive gear rotatably arranged with respect to the casing of the developing device and meshing with the developing gear of the developer conveying member occupying the developing position is supported at a position other than the developing unit and is brought to the developing position. Developer transport The center of rotation of the developing gear of the feeding member, the center of rotation of the drive gear, and the center of rotation of the developing unit are arranged on substantially the same straight line, and the developing unit starts to rotate, and the developer conveyance occupying the developing position is started. When the developing gear of the member starts revolving around the rotation center of the developing unit, the driving gear meshing with the developing gear is rotating, and each developer transport member is positioned at the developing position by the rotation of the developing unit. Before the developer conveying member reaches the developing position, the developing gear of the developer conveying member is engaged with the rotating drive gear, and the driving gear is rotated so that the developing gear starts rotating. And a drive control means for controlling the rotation of the rotary developing device.