JP2001066862A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a compact and high-speed color image forming device by using plural developing devices taking different posture. SOLUTION: In this developing device, an electrostatic latent image formed on a latent image carrier 140 is developed with dry developer supplied from the developing device. The device is constituted by arranging plural developing devices 10M and 10C taking the different posture in parallel up and down. In such a case, the respective devices 10M and 10C are provided with main hoppers 15M and 15C provided with one or more agitators 16M and 16C and developing chambers 14M and 14C rotatably supporting a developer carrier 140. In the developing device 10C in which the main hopper 15c is positioned lower than the developing chamber 14C in the up-and-down relation in the gravity direction of the developing chambers 14M and 14C and the main hoppers 15M and 15C, the agitator 16C is provided with a developer carrying means 19 and the diameter of the shaft 169 of the agitator 16C is made larger than the shaft of the agitator 16M in the other developing device 10M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copier, a facsimile or a printer, and more particularly to a developing apparatus using a plurality of developing units having different postures.

[0002]

2. Description of the Related Art Conventionally, as a method of arranging developing units in an electrophotographic color image forming apparatus, four developing units corresponding to four colors are arranged rotatably in a rotary manner with respect to a photosensitive member. A type in which the rotary is rotated to bring the developing units of each color into contact with the photoconductor in order (for example, Japanese Patent Application Laid-Open No. 7-27121).
No. 0) and a type in which the same four developing units having the same posture are arranged in parallel with respect to a photosensitive body that moves linearly, and the developing units of each color are sequentially brought into contact with the photosensitive body (for example, Japanese Patent Laid-Open No. 10-1489).
No. 89) is known.

[0003]

When a small-sized and high-speed color image forming apparatus is constructed using such a developing device of the type described above, it is necessary to switch the developing device at a high speed in the case of a rotary type. There are difficult problems. In the case of a type in which four developing units having the same attitude are arranged in parallel, there is a problem that the apparatus becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to enable a compact and high-speed color image forming apparatus using a plurality of developing units having different postures. It is to provide a developing device.

[0005]

According to the present invention, there is provided a developing device for developing an electrostatic latent image formed on a latent image carrier with a dry developer supplied from a developing device. In a developing device in which a plurality of developing devices having different postures are vertically arranged in parallel, each developing device includes a main hopper having one or more agitators and a developing chamber rotatably supporting a developer carrier. Having a vertical relationship between the developing chamber and the main hopper in the direction of gravity, in a developing device in which the main hopper is located below the developing chamber, a developer conveying means is provided in the agitator, Further, the diameter of the shaft of the agitator is made larger than that of the agitator of another developing device.

Another developing device of the present invention is a developing device for developing an electrostatic latent image formed on a latent image carrier with a dry developer supplied from a developing device, and includes a plurality of developing devices having different postures. In a developing device in which developing devices are arranged in parallel one above the other, each developing device rotatably supports a main hopper having a developer supply port and one or more agitators for supplying a developer, and a developer carrier. And a partition wall separating the main hopper and the developing chamber from each other. The vertical relationship between the partition wall, the rotation center of the agitator, and the developer supply port in the direction of gravity is determined by the partition. In a developing device in which the rotation center of the agitator is located below the wall and the rotation center of the agitator is located below the developer supply port, the agitator The developer conveying means is provided, and is characterized in that it has a larger diameter with respect to the axis of the agitator other developing devices the axis of the agitator.

[0007] In these, it is desirable that the shaft of the agitator having a large diameter be a hollow shaft.

Further, it is desirable that the developer conveying means is configured to contact the inner wall of the main hopper.

Further, it is desirable that the developer conveying means is constituted by a thin resin film.

[0010] At least one end of the agitator is sealed to the bearing via a ring-shaped sealing member so as to prevent the developer from entering, and the agitator has a movable range of 1 mm or more in the axial direction. It is desirable to be attached to the bearing.

In the present invention, the vertical relationship between the developing chamber and the main hopper in the direction of gravity depends on the rotation of the developing unit in which the main hopper is located below the developing chamber or the rotation center of the partition wall and the agitator. The vertical relationship between the developer and the developer supply port in the direction of gravity is such that the rotation center of the agitator is located below the partition wall and the rotation center of the agitator is below the developer supply port. In the located developing device, the agitator is provided with a developer conveying means and the agitator shaft is enlarged in diameter with respect to the agitator shaft of the other developing devices. In spite of having, the amount of toner around it is reduced, so that the driving torque of the agitator can be prevented from increasing.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of an example of an image forming apparatus to which a developing device of the present invention is applied will be described with reference to FIG.

This image forming apparatus is capable of forming a full-color image using a developing device using four color toners of yellow (Y), magenta (M), shiashi (C) and black (K). It is a printer.

In FIG. 1, reference numeral 100 denotes an image carrier cartridge in which an image carrier unit is incorporated. In this example, the image carrier cartridge is configured as a photoconductor cartridge, and the photoconductor 140 is driven by appropriate driving means (not shown). Is driven to rotate in the direction of the arrow shown in FIG. The photoconductor 140 has a thin cylindrical conductive substrate and a photosensitive layer formed on the surface thereof.

Around the photoreceptor 140, a charging roller 160 as a charging unit, an exposure unit 40, and a developing unit 10 (Y, M, C,
K), the intermediate transfer device 30, and the cleaning unit 17
0 is arranged.

The charging roller 160 contacts the outer peripheral surface of the photoconductor 140 and uniformly charges the outer peripheral surface. On the outer peripheral surface of the uniformly charged photoconductor 140, a selective exposure L1 according to desired image information is performed by the exposure unit 40,
By the exposure L1, an electrostatic latent image is formed on the photoconductor 140.

The electrostatic latent image is developed with, for example, a one-component non-magnetic toner by a developing unit 10. As a developing device, a developing device 10Y for yellow and a developing device 1 for magenta
0M, a developing device 10C for cyan, and a developing device 10K for black are vertically arranged on the outer peripheral surface of the photoconductor 140 in different postures. These developing units 10Y, 10M,
10C and 10K are each configured to be swingable,
Optionally, only the developing roller 11 of one developing device is
40 can be contacted. Therefore, these developing devices 10 apply any one of yellow, magenta, cyan, and black toners to the surface of the photoconductor 140 to develop the electrostatic latent image on the photoconductor 140. Developing roller 1
Reference numeral 1 denotes a hard roller, for example, a metal roller having a roughened surface or a hard resin roller.

The developed toner image is transferred onto an intermediate transfer belt 36 of an intermediate transfer device.

The cleaning means 170 includes a cleaner blade for scraping off the toner remaining on and adhering to the outer peripheral surface of the photoreceptor 140 after the transfer, and a receiving portion for receiving the toner scraped off by the cleaner blade. I have.

The intermediate transfer device 30 includes a driving roller 31 and
Four driven rollers 32, 33, 34, 35 and an endless intermediate transfer belt 36 stretched around these rollers.
And

The driving roller 31 is driven to rotate at substantially the same peripheral speed as that of the photoconductor 140 because a gear (not shown) fixed to the end of the driving roller 31 meshes with a driving gear of the photoconductor 140. The transfer belt 36 is driven to circulate at substantially the same peripheral speed as the photosensitive member 140 in the direction of the arrow shown in the figure.

The driven roller 35 is disposed at a position where the intermediate transfer belt 36 is pressed against the photosensitive member 140 by its own tension with the driving roller 31.
A primary transfer portion T1 is formed at a pressure contact portion between the intermediate transfer belt 36 and the intermediate transfer belt 36. The driven roller 35 is disposed near the primary transfer portion T1 on the upstream side in the circulation direction of the intermediate transfer belt 36.

The driving roller 31 has an intermediate transfer belt 36
A primary transfer voltage is applied to the conductive layer of the intermediate transfer belt 36 via the electrode roller (not shown).

The driven roller 32 is a tension roller, and urges the intermediate transfer belt 36 in the direction of its tension by urging means (not shown).

The driven roller 33 is a backup roller that forms the secondary transfer portion T2. A secondary transfer roller 38 is opposed to the backup roller 33 via an intermediate transfer belt 36. The secondary transfer roller 38
It can be moved toward and away from the intermediate transfer belt 36 by a contacting / separating mechanism (not shown). A secondary transfer voltage is applied to the secondary transfer roller 38.

The driven roller 34 is a backup roller for the belt cleaner 39. Belt cleaner 39
Is a cleaner blade 39 which comes into contact with the intermediate transfer belt 36 and scrapes off the toner remaining and adhering to the outer peripheral surface thereof.
a, and a receiving portion 39b for receiving the toner scraped off by the cleaner blade 39a. The belt cleaner 39 can be moved toward and away from the intermediate transfer belt 36 by a contact / separation mechanism (not shown).

In the process of circulating the intermediate transfer belt 36, the toner image on the photosensitive member 140 is transferred onto the intermediate transfer belt 36 in the primary transfer portion T1, and the toner image transferred onto the intermediate transfer belt 36 is Is transferred to a sheet (recording material) S, such as a sheet, supplied between the secondary transfer roller 38 and the secondary transfer unit T2.

The sheet S is fed from the sheet feeding device 50,
The toner is supplied to the secondary transfer station T2 at a predetermined timing by the gate roller pair G. 51 is a paper feed cassette, and 52 is a pickup roller.

The sheet S to which the toner image has been transferred in the secondary transfer section T2 passes through the fixing device 60, where the toner image is fixed, and is formed on the case 80 of the apparatus main body through the paper discharge path 70. The sheet is discharged onto the received sheet receiving portion 81. In this image forming apparatus, as a paper discharge path 70,
It has two paper discharge paths 71 and 72 independent of each other, and the sheet that has passed through the fixing device 60 is discharged through one of the paper discharge paths (71 or 72). The paper discharge paths 71 and 72 also constitute a switchback path. When an image is formed on both sides of the sheet, the sheet once entering the paper discharge path 71 or 72 passes through the return path 73. Then, the sheet is fed again to the secondary transfer portion T2.

With such a configuration, the entire image forming apparatus operates in the following order.

When a drawing command signal (image forming signal) from a not-shown host computer or the like (a personal computer or the like) is input to the control section 90 of the image forming apparatus, the photosensitive member 140, the rollers 11 of the developing device 10, and , The intermediate transfer belt 36 is driven to rotate.

The outer peripheral surface of the photosensitive member 140 is
Is charged uniformly. Photoreceptor 14 uniformly charged
On the outer peripheral surface of 0, selective exposure L1 is performed by the exposure unit 40 according to the image information of the first color (for example, yellow), and an electrostatic latent image for yellow is formed.

Only the developing roller of the developing device 10Y for the first color (for example, yellow) comes into contact with the photosensitive member 140, whereby the electrostatic latent image is developed, and the toner image for the first color (for example, yellow) is formed. Is formed on the photoconductor 140.

A primary transfer voltage having a polarity opposite to that of the toner is applied to the intermediate transfer belt 36.
The toner image formed thereon is transferred onto the intermediate transfer belt 36 at the primary transfer portion T1. At this time, the secondary transfer roller 38 and the belt cleaner 39 are separated from the intermediate transfer belt 36.

After the toner remaining on the photoreceptor 140 is removed by the cleaning means 170, the photoreceptor 140 is neutralized by static elimination light from a static elimination means (not shown).

The above operation is repeated for the second color plane, the third color plane, and the fourth color plane in accordance with the contents of the drawing command signal, and the toner image corresponding to the contents of the drawing command signal is transferred to the intermediate transfer belt. The intermediate transfer belt 36 is formed on the intermediate transfer belt 36 by being superposed on the intermediate transfer belt 36.

The sheet S is supplied from the sheet feeding device 50 at a predetermined timing, and immediately before or after the leading end of the sheet S reaches the secondary transfer portion T2 (that is, the intermediate transfer is performed at a desired position on the sheet S at a desired position). At the timing when the toner image on the belt 36 is transferred, the secondary transfer roller 38 is pressed against the intermediate transfer belt 36 and a secondary transfer voltage is applied, and the toner image on the intermediate transfer belt 36 (basically, A full-color image in which four color toner images are superimposed) is transferred onto the sheet S. Further, the belt cleaner 39 contacts the intermediate transfer belt 36, and after the secondary transfer, the intermediate transfer belt 3
6 is removed.

When the sheet S passes through the fixing device 60, the toner image is fixed on the sheet S, and thereafter, the sheet S is directed to a predetermined position (in the case of non-double-side printing, the sheet S is directed to the sheet receiving portion 81, and the double-sided printing is performed). In the case of (1), the sheet is conveyed via the switchback path 71 or 72 to the return path 73).

FIG. 2 is an enlarged view of the developing device 1 of FIG. As described above, in the developing device 1 according to the present invention, the developing device 10Y for yellow, the developing device 10M for magenta, the developing device 10C for cyan, and the developing device 10K for black are exposed in order from top to bottom in the direction of gravity. They are arranged side by side around the body 140 in different postures. Each developing unit 10Y, M, C, K
Are basically composed of the same basic components, and for the time being, the following description will be made by omitting Y, M, C, and K after the numerals indicating the respective members. However, as shown in FIG. 10Y, 1
Y, M, C, and K are added after the numerals to distinguish them from the members constituting 0M, 10C, and 10K.

Each developing unit includes a developing chamber 14, a main hopper 15, and a toner cartridge 20.
Reference numeral 4 denotes a developing roller (developer carrying member) 11, a supply roller (developer supplying member) 12 for supplying a developer (toner) to the surface of the developing roller 11, and a toner carried on the surface of the developing roller 11. A regulating member 13 for regulating the thickness of the layer is arranged, and is rotated in the illustrated direction.
, A supply bias voltage is applied to the supply roller 12, and the toner frictionally charged by the rotation of the supply roller 12 is supplied from the supply roller 12 to the development roller 11, and is carried on the surface thereof. The thickness of the toner layer is regulated by the regulating member 13, and the toner carried on the surface of the developing roller 11 is subjected to further triboelectric charging.

In the main hopper 15, one or more agitators 16 for stirring the toner supplied from the toner cartridge 20 through the toner supply port 17 to maintain a high fluidity state are disposed (the illustrated example). In this case, two agitators 16 are disposed.), And the toner is conveyed to the developing chamber 14 while maintaining the fluidity of the toner.

Between the main hopper 15 and the developing chamber 14,
Partition wall 18 that separates both rooms from below
Is disposed, and only the toner that has passed over the upper side is transported from the main hopper 15 to the developing chamber 14.

As is clear from FIG. 2, a developing device (for example, 10K) arranged on the downstream side of the developing device (for example, 10Y) arranged on the upstream side of the photosensitive member 140 has a main The position of the hopper 15 is low. This is inevitable in a configuration in which a plurality of developing devices are arranged around the cylindrical photoconductor 140. When the main hopper 15 is higher than the developing chamber 14, the toner can be transported from the main hopper 15 to the developing chamber 14 by gravity. Conversely, when the main hopper 15 is lower than the developing chamber 14, the toner is It is difficult to transport the toner from the developing chamber 15 to the developing chamber 14.

Therefore, in a developing device in which a plurality of developing units 10 (Y, M, C, K) having different postures as in the present invention are vertically arranged in parallel, the developing chamber 14 (Y, M,
Main hopper 15 (Y, M, C, K) for C, K)
The structure of the agitator 16 (Y, M, C, K) in the main hopper according to the vertical relationship of the
It is necessary to provide an optimum toner conveying capacity according to the attitude of the developing device 10 (Y, M, C, K).
With this configuration, the agitator 16 (Y,
M, C, K) can be reduced.

Further, for example, like the developing unit 10Y, the main hopper 15Y applies toner such as fins to the agitator 16Y of the developing unit 10Y higher than the developing room 14Y.
If a member forcibly transporting the toner is provided, excessive toner transporting ability is provided, so that the toner is pushed into the developing chamber (powder powder), toner leaks, and regulation defects by the regulation member are caused. Become.

Hereinafter, this point will be described in more detail with reference to FIG. FIG. 3 corresponds to the embodiments of FIG. 2, and the magenta developing device 10M and the cyan developing device 1M of those embodiments.
Only 0C is shown as a representative example. The structures of the other developing units 10Y for yellow and 10K for black will be apparent from the illustration of FIG. 2 and the description of FIG. Note that, in FIG.
The toner cartridges 20M and 20C of the M and 10C are shown in a detached state.
M is oscillated and the developing roller 1 of the developing device 10M is selectively rotated.
Only 1M is shown in contact with the photoconductor 140.

As is apparent from FIG. 3, in the developing device 10M, the main hopper 15M is higher than the developing chamber 14M, and the center of the agitator 16M is higher in the direction of gravity than the upper side of the partition wall 18M.
As described above, when the main hopper 15M is higher than the developing chamber 14M and the center of the agitator 16M is higher than the upper side of the partition wall 18M in the direction of gravity, the agitator 16M is not configured to have a toner conveying capability. It is configured to have only the stirring ability.

FIG. 4 shows an agitator 1 having only a stirring ability.
1 shows a partially omitted perspective view of an example. This agitator has a configuration in which a rib 162 having an opening 163 is provided around a shaft 161 having an improved rigidity. By rotating the agitator 16M having such a configuration, the toner is loosened and flows, and gravity is applied. The toner is moved (conveyed) from the main hopper 15M to the developing chamber 14M.

As described above, when the main hopper 15M is higher than the developing chamber 14M and the center of the agitator 16M is higher in the direction of gravity than the upper side of the partition wall 18M, the agitator 16M having only the stirring ability without the toner conveying ability is used. When used, in particular, the driving torque applied to the agitator 16M during settling due to tapping of the toner is greatly reduced. Also, dust in the developing chamber 14M due to excessive toner carrying capacity is prevented, image quality is degraded due to toner deterioration, toner leaks from each part of the developing chamber 14M due to excessive pressure, image density is increased due to poor regulation by the regulating member, and regulation is increased. It is possible to prevent the image quality from deteriorating due to toner leakage from the unit.

On the other hand, in the cyan developing unit 10C disposed below, the main hopper 15C is lower than the developing chamber 14C, and the center of the agitator 16C is lower in the direction of gravity than the upper side of the partition wall 18C. It has become. In particular, the center of the agitator 16C on the side of the toner supply port 17C is lower than the toner supply port 17C from the toner cartridge 20C, so that toner is conveyed from the toner cartridge 20C into the main hopper 15C by gravity. It has become. As described above, when the main hopper 15C is lower than the developing chamber 14C, the center of the agitator 16C is lower than the upper side of the partition wall 18C, and the center of the agitator 16C is lower than the toner supply port 17C, the toner is stirred by the agitator 16C. A configuration that has transport capacity in addition to capacity.

For this reason, the agitator 16C includes:
A hollow shaft 1 having a large outer diameter as shown in FIG.
68, and a fin 19 as a toner conveying means made of a thin resin film such as PET is attached to the outer surface thereof by bonding or welding with a double-sided adhesive tape. When the agitator 16C having such a configuration is rotated in the direction of the arrow in FIG. 3 in the main hopper 15C, the fins 19 rotate, so that the toner in the flowing state exceeds the upper side of the partition wall 18C against the gravity against the developing chamber. It can be transported to 14C. In addition, fin 1
When the rotating member 9 rotates while contacting the inner wall surface of the main hopper 15C, the amount of dead toner can be reduced and the transporting ability can be improved. Further, the fin 19 made of a thin resin film is used.
Is attached to the hollow thick shaft 168, so that an agitator having toner agitation capability + transport capability can be easily configured.

As described above, the agitator 16C having the toner conveying ability in addition to the toner stirring ability has a main hopper higher than the developing chamber, such as the agitator 16M of the developing unit 10M, and has a higher agitator height than the agitator shaft from the upper side of the partition wall. The reason for using the shaft 168 having a large diameter will be described.
When the center of the agitator having the toner conveying means or the entire agitator is buried in the toner, the pressure applied from the toner to the agitator increases. In addition, the driving torque of the agitator greatly depends on the amount of toner existing around the agitator (particularly during tapping sedimentation). Even when the toner is in a state close to a fluid at the time of flow, the state is close to a solid at the time of tapping when vibration is applied during transportation or operation of a machine.

Therefore, the driving torque of the agitator is increased, and the load on the agitator during rotation is increased. As a result, the load on the driving motor is increased, the shaft of the agitator bends, the gear meshes poorly, and the sliding resistance at the bearing portion is increased. Driving faults may occur due to the increase.

Then, the main hopper 1 is moved from the developing chamber 14C.
5C, the center of the agitator 16C is lower than the upper side of the partition wall 18C, and the agitator 16C
In particular, in an agitator that is easily buried in toner, such as the agitator 16C of the developing device 10C in which the center of the agitator 16C on the side of the toner supply port 17C is lower than the toner supply port 17C, the shaft 168 having a hollow outer diameter is used. It is desirable to use an agitator having such a large-diameter shaft to reduce the amount of surrounding toner so as to prevent an increase in the driving torque of the agitator.

When such an agitator is used, a stable toner supply by stable agitator driving without tooth breakage and vibration can be achieved. A large-diameter shaft agitator is advantageous in a layout in which the distance from the toner supply port to the developing roller is long (the degree of freedom in layout is high). Although it is possible to reduce the amount of toner around the agitator even if the radius of the inner wall of the main hopper is reduced, in this case, it is necessary to shorten the distance from the toner supply port to the developing roller. I lose my degree.

If the shaft 168 having a large diameter is a solid shaft that is not hollow but solid, the total weight of the entire developing device 10C increases, and the impact when the developing device 10C comes into contact with the photosensitive member 140 is increased. When the photosensitive member 140 momentarily vibrates and the exposure position shifts momentarily, streaks (banding, color misregistration) perpendicular to the printing direction occur, and the image quality deteriorates. Therefore, a shaft 16 having a large outer diameter is used.
With the hollow structure of 8, the increase in the weight of the entire developing device 10C can be prevented, and the deterioration of the image quality can be prevented.

In order to form a hollow shaft 168 having a large outer diameter as shown in FIG. 5 by resin molding, a resin in a molten state is poured into a mold and, at the same time, gas injection molding is performed by blowing gas as indicated by an arrow 169. Alternatively, it can be produced by blow molding.

When the agitator center position is buried in the toner, the drive torque is 1.3 in the state where the toner is loosened, compared with the case where the agitator is not buried, depending on the shape. 1.5 to 1.5 times, with toner settled by vibration or the like (during tapping)
5 times, sometimes more. By increasing the diameter of the shaft as shown in FIG.
m), the agitator drive torque is 3/5 in a normal flowing state
In the case of tapping, there is an effect of reducing the driving torque by 1/3 to 1/2.

A specific example will be described. For example, the developing device 10
M main hopper 15M and its agitator 16M
A conventional developing device in which fins 19 are attached to
When the developing device 10C of the present invention as described above is compared, the ratio of the diameter of the shaft of the agitator is 6:15, and the volume ratio between the toner and the agitator in the main hopper is 12:
1. The example of the present invention is 2: 1. As a result, the amount of toner around the agitator is 50 to 60 g in the conventional example and 30 to 40 g in the example of the present invention (in the case of A3 width), and the agitator driving torque is 1 in the example of the present invention compared to the conventional example. /
1.3 to 1 / 1.5 (with toner loosened), 1 /
3 to 1.5 (with toner settled).

Next, a configuration in which the end of the agitator is sealed to a bearing and rotatably mounted will be described. In this description, since the items are common to the developing units 10Y, 10M, 10C, and 10K, Y, M, C, and K after the numbers indicating the members constituting the developing units are omitted.

FIG. 6 is a plan view of the developing unit 10 with the cover removed, and the agitator 16 is mounted between the developing chamber 14 and the opposing wall surface 21 of the housing constituting the main hopper 15. As shown in FIG. 7, both ends of the shaft 161 of each agitator 16 have a small-diameter introduction portion 165 for insertion into the bearing 22, a large-diameter fitting portion 167 at the base, and the introduction portion 165 and the fitting portion 167. And a taper portion 166 for connecting the shaft to the shaft end insertion portion of the bearing 22 to seal the toner in the main hopper 15 so that the toner in the main hopper 15 does not enter the bearing 22.
A seal member 23 called a seal is attached. This seal member 23 has a ring shape,
As shown in the figure, the shaft 161 is made of an elastic material such as rubber having a small diameter on the side that receives the tip and a large diameter on the opposite side, and an inner surface having a conical shape.

The tip of the shaft 161 of the agitator 16 is
7, the introduction portion 165 having a smaller diameter than the smaller hole diameter of the seal member 23 first enters the hole of the seal member 23, and passes through the tapered portion 166 to form the smaller one of the seal member 23. The fitting portion 167 having a diameter larger than the hole diameter of the bearing 2 fits into the hole of the seal member 23 and
The fitting portion 167 is fitted and attached in the inside 2. FIG. 8 (a) shows that the seal member 23 is normally fitted to the fitting portion 1 of the shaft 161.
67, the seal member 23 is normally fitted to prevent the toner from entering the bearing 22 when the seal member 23 is fitted in such a form. Without giving extra resistance to rotation,
And it has a sufficient life.

However, when the mounting is performed as shown in FIG. 7, the smaller hole diameter portion of the seal member 23 is pulled by the fitting portion 167, and is turned up as shown in FIG. 8B. In this state, not only does the sealing function of the sealing member 23 become defective, but also an extra resistance is given to the rotation of the shaft 161 to increase the driving torque. Will be done.

Therefore, as shown in FIG. 6, a movable range (play) of Δ is positively provided in the axial direction between the wall surface 21 and the root of the shaft 161 of the agitator 16. When such a play Δ is provided, the agitator 16 and the bearing 2
After the setting of 2, the agitator 16 is reciprocated two or three times in the thrust direction by the amount of the play Δ, so that the turning of the seal member 23 as shown in FIG. 8B when the agitator 16 and the shaft 161 are assembled. Then, the state becomes normal as shown in FIG.

Here, if the movable range of the agitator 16 in the axial direction is 1 mm or more, it is sufficient to perform the above-described operation. The length of the introduction portion 165 of the tip of the shaft 161 of the agitator 16 into the seal member 23 may be 1 mm or more.

Although the developing device of the present invention has been described based on the embodiments, the present invention is not limited to these embodiments, and various modifications are possible.

[0067]

As is apparent from the above description, according to the developing device of the present invention, the vertical relationship between the developing chamber and the main hopper in the direction of gravity is such that the main hopper is located below the developing chamber. The vertical relationship between the rotation center of the partition wall and the agitator and the developer supply port in the direction of gravity is such that the rotation center of the agitator is positioned below the partition wall and In the case of a developing device in which the rotation center of the agitator is located below the developer supply port, the agitator is provided with developer conveying means, and the diameter of the agitator shaft is increased with respect to the agitator shaft of another developing device. As a result, despite the fact that the agitator has not only the toner stirring ability but also the conveying ability, the amount of toner around the agitator is reduced, thereby preventing the drive torque of the agitator from increasing. It can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of an image forming apparatus to which a developing device of the present invention is applied.

FIG. 2 is an enlarged view of the developing device of FIG.

FIG. 3 is a diagram showing only a magenta developing device and a cyan developing device of FIG. 2 as representative examples.

FIG. 4 is a partially omitted perspective view of an example of an agitator having only a stirring ability.

FIG. 5 is a cross-sectional view of a shaft of a hollow and large-diameter agitator according to the present invention.

FIG. 6 is a plan view illustrating a configuration in which an end of an agitator is sealed to a bearing to be rotatably mounted and viewed with a cover of a developing unit removed.

FIG. 7 is a diagram showing a state where an end of a shaft of an agitator is attached to a bearing.

FIG. 8 is a view showing a state in which the seal member is normally fitted into the fitting portion of the shaft of the agitator and a state in which the seal member is turned up.

[Explanation of symbols]

Reference Signs List 1: developing device 10Y: developing device for yellow (Y developing unit) 10M: developing device for magenta (M developing unit) 10C: developing device for cyan (C developing unit) 10K: developing device for black (K developing unit) 11, 11Y, 11M, 11C, 11K ... developing roller 12, 12Y, 12M, 12C, 12K ... supply roller (developer supply body) 13, 13Y, 13M, 13C, 13K ... regulating member 14, 14Y, 14M, 14C, 14K ... Developing chamber 15, 15Y, 15M, 15C, 15K: Main hopper 16, 16Y, 16M, 16C, 16K: Agitator 17, 17Y, 17M, 17C, 17K: Toner supply port 18, 18Y, 18M, 18C, 18K: Partition wall 19 fins (toner conveying means) 20, 20Y, 20M, 20C, 20K ... toner Cartridge 21 ... Wall surface of housing of developing chamber and main hopper 22 ... Bearing 23 ... Seal member (G seal) 30 ... Intermediate transfer device 31 ... Drive roller 32,33,34,35 ... Driving roller 36 ... Intermediate transfer belt 38 ... 2 Next transfer roller 39 Belt cleaner 39a Cleaner blade 39b Receiver 40 Exposure unit 50 Paper feeder 51 Paper feed cassette 52 Pickup roller 60 Fixing device 70, 71, 72 Paper discharge path 73 Return path 80 case 81 sheet receiving section 90 control section 100 image carrier cartridge 140 photosensitive member 160 charging roller 161 agitator shaft 162 rib 163 opening 165 introduction section 166 taper section 167 fitting section 168: Shaft of a hollow agitator with a large outside diameter 169: Gas blowing direction 1 70: Cleaning means L1: Exposure light T1: Primary transfer part T2: Secondary transfer part S: Sheet (recording material) G: Gate roller pair

Claims (6)

[Claims] 1. A developing device for developing an electrostatic latent image formed on a latent image carrier with a dry developer supplied from a developing device, wherein a plurality of developing devices having different postures are vertically arranged in parallel. In the developing device, each developing unit has a main hopper having one or more agitators, and a developing chamber rotatably supporting a developer carrier, and the developing chamber and the main hopper in a gravity direction. In the developing device in which the main hopper is located below the developing chamber, the developer conveying means is provided in the agitator, and the axis of the agitator is connected to the axis of the agitator of another developing device. A developing device having a larger diameter. 2. A developing device for developing an electrostatic latent image formed on a latent image carrier with a dry developer supplied from a developing device, wherein a plurality of developing devices having different postures are vertically arranged in parallel. In the developing device, each developing device has a main hopper having a developer supply port capable of supplying a developer and one or more agitators, a developing chamber rotatably supporting a developer carrier, and the main hopper. And a partition wall separating the developing chamber from each other. The vertical relationship between the partition wall, the rotation center of the agitator, and the developer supply port in the direction of gravity is the rotation center of the agitator with respect to the partition wall. Is located on the lower side, and
In a developing device in which the rotation center of the agitator is located below the developer supply port, the agitator is provided with developer conveying means, and the axis of the agitator is aligned with the axis of the agitator of another developing device. A developing device having a large diameter. 3. The developing device according to claim 1, wherein the shaft of the large diameter agitator comprises a hollow shaft. 4. The developing device according to claim 1, wherein said developer conveying means is configured to contact an inner wall of a main hopper. 5. The developing device according to claim 1, wherein said developer conveying means is formed of a thin resin film. 6. At least one end of the agitator is sealed to a bearing via a ring-shaped seal member so as to prevent developer from entering, and the agitator has a movable range of 1 mm or more in the axial direction. The developing device according to claim 1, wherein the developing device is attached to the bearing.