JPH07253712A - Developing device - Google Patents

Abstract

PURPOSE:To use, in the case of replenishing a developing device with fresh taner, the replenishment toner in development after its sufficient electrification, to prevent surface fog of a formed image and scatter of the toner from the developing device, resulting in soil of the inside of an image-forming device, and to steadily carry out satisfactory image formation. CONSTITUTION:While stirring the developing device circulates it between a first carry part 13 and a second carry part 15, which are separated from each other by a partition wall 16, and also replenishes the second carry part with the fresh toner from a toner replenishment part. At least one end of the partition 16 extends to the ends of the first carry part 13 and second carry part 15 without making a hole in it, and the height of the partition wall 16, the position of the partition end on the side of the ends of the carry parts, is such that the developers in the first carry part 13 and the second carry part 15 can be moved over it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer,
In particular, a first transport unit that transports the developer while stirring the developer along the axial direction of the developing sleeve that sends the developer to the image carrier,
The developer is circulated between the first transport unit and the second transport unit by separating the first transport unit and the second transport unit that transports the developer in the opposite direction while stirring the developer by a partition wall. At the same time, the present invention relates to a developing device in which toner is replenished from the toner replenishing portion to the second conveying portion side.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a developing device supplies toner to an electrostatic latent image formed on an image carrier to develop the electrostatic latent image. As such a developing device, in addition to a one-component developing system using only toner as a developer, a two-component developing system using a developer containing toner and carrier has been known.

Here, in the case of a two-component developing system using a developer containing a toner and a carrier, when toner is supplied to the image carrier to perform development, the toner concentration in the developer gradually increases. Therefore, when the toner concentration in the developer decreases to some extent, it becomes necessary to supply new toner.

When replenishing new toner in this manner, a developing device that replenishes toner along a line along the axial direction of the developing sleeve, and FIGS.
As shown in FIG. 3, a partition wall 16 is provided in the housing 10 of the developing device, and the partition wall 16 mixes and stirs the developer 2 on the side of the developing sleeve 11 that sends the developer 2 to the image carrier 1. The first transport unit 13 for transporting along the axial direction of 11 and the second transport unit 15 for transporting the developer 2 in the opposite direction while mixing and stirring the developer 2 are separated, A developing device is used in which the developer 2 is supplied to the developing sleeve 11 in the first transport unit 13 and new toner is supplied from the toner replenishing unit 17 to the second transport unit 15 side. It had been.

Here, in the case of the developing device for replenishing the toner in the line along the axial direction of the developing sleeve as described above,
Since the toner is uniformly supplied in the axial direction of the developing sleeve, the toner concentration in the developer does not become uneven when the toner is supplied, but the size of the device becomes large, and the toner is partially dispersed. When an image that consumes a lot is formed, only the toner in the developer in that portion is consumed in a large amount, and the toner density in that portion lowers. If images are continuously formed, the image density in that portion significantly decreases. There was a problem.

On the other hand, in the case of the developing device shown in FIGS. 1 to 3,
Although there is no such problem, there is a problem that when the toner is supplied contrary to the case of the developing device that replenishes the toner in a line, the toner concentration in the developer becomes uneven. Explained.

Here, in the developing device shown in FIGS. 1 to 3, the stirring / conveying blade 12b and the scraping member 12c for scraping up the developer 2 are provided around the rotary shaft 12a in the first conveying section 13. Arrange the first stirring and conveying member 12 provided,
The first transporting member 1 is rotated to rotate the first transporting member 1.
While the developer 2 in 3 is conveyed along the axial direction of the developing sleeve 11, a part of the developer 2 is supplied to the developing sleeve 11, and at the same time, in the second conveying portion 15 around the rotary shaft 14a. Spiral stirring blade 1
The second stirring / transporting member 14 provided with 4b is arranged, and the second stirring / transporting member 14 is rotated to mix and stir the developer 2 in the second transporting unit 15 while rotating in the opposite direction to the first transporting unit 13. I was supposed to carry it.

As for the partition wall 16 which separates the inside of the housing 10 into the first transport section 13 and the second transport section 15 as described above, the height of the partition wall 16 is increased,
The developer 2 is prevented from moving beyond the partition wall 16 between the first transport unit 13 and the second transport unit 15, while one end of the partition wall 16 is provided with the second transport unit 15 to the first transport unit. 1
3, the supply port 16a for sending the developer 2 is opened, and the return port 16b for returning the developer 2 from the first carrying unit 13 to the second carrying unit 15 is opened at the other end of the partition wall 16.

In this developing device, the developer 2 in the second transport section 15 is transported while being mixed and stirred by the second stirring transport member 14 provided in the second transport section 15 as described above. The developer 2 thus conveyed is sent to the first conveying portion 13 through the supply port 16a provided at one end of the partition wall 16.

On the other hand, in the first transport section 13 into which the developer 2 is fed in this way, the first stirring and transporting member 1 described above is used.
2 is rotated, the developer 2 is scraped by the scraping member 12c provided on the first stirring and conveying member 12, and a part of the developer 2 is supplied to the developing sleeve 11 having the magnet roller 18 provided therein. Then, the toner in the developer 2 is supplied to the image carrier 2 to perform development, and the developer 2 is transferred to the first stage by the stirring and carrying blade 12b provided in the first stirring and carrying member 12. The developer 2 conveyed in the opposite direction to the second conveying section 15 and the developer 2 conveyed in this way is provided with a return port 16 b provided at the other end of the partition wall 16.
The developer 2 is circulated between the second transporting section 15 and the first transporting section 13 by returning the developer 2 to the second transporting section 15.

When the toner in the developer 2 is supplied from the developing sleeve 11 to the image carrier 1 as described above to develop the toner, the toner concentration in the developer 2 is lowered. As described above, new toner is supplied from the toner replenishing unit 17 to the second transport unit 15, and the toner thus supplied is combined with the developer 2 returned to the second transport unit 15 through the return port 16b. The toner is mixed and stirred with the developer 2 by the second stirring and conveying member 14 and is conveyed.

When the toner newly replenished through the toner replenishing section 17 as described above is mixed with the developer 2 in the second conveying section 15, the developer 2 in the newly replenished portion of the toner 2 is mixed. Only the toner density becomes high,
Partial unevenness occurs in the toner density in the developer 2,
Particularly, when a large amount of toner is consumed, when a large amount of toner is replenished at one time from the toner replenishing unit 17, only the toner concentration in the developer 2 in the portion to which the toner is replenished becomes extremely high.

As a result, in the case of the developing device shown in FIGS. 1 to 3, the newly replenished toner is conveyed without being sufficiently mixed and stirred with the developer 2, and the toner is not sufficiently charged to the supply port 16a. The developer 2 containing the poorly charged toner that is not sufficiently charged.
Is fed to the first transport portion 13 through the supply port 16a, and this developer is fed to the developing sleeve 11 and used for development, and a background fog occurs in the formed image. There is a problem that the toner with poor charging is scattered from the developing device and the inside of the image forming device is soiled.

Further, in order to sufficiently charge the newly replenished toner in the second conveying section 15, it has been considered that the stirring condition of the developer 2 by the second stirring and conveying member 14 is strengthened. If the stirring condition of the developer 2 by the second stirring / transporting member 14 is strengthened, a large load is applied to the developer 2 and the developer 2 is deteriorated, or a large load is applied to the second stirring / transporting member 14. Problem occurred.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided a first conveying section for conveying a developer while stirring it along an axial direction of a developing sleeve for feeding the developer to the image carrier, and the above-mentioned constitution while stirring the developer. The first transporting section and the second transporting section for transporting in the opposite direction are separated by a partition wall, and the developer is circulated between the first transporting section and the second transporting section, and the second transporting section is also transported. It is an object of the present invention to solve the above-mentioned problems in a developing device in which toner is replenished from a toner replenishing unit.

That is, according to the present invention, in the developing device as described above, the toner is replenished from the toner replenishing portion to the second conveying portion side, and the thus replenished toner is mixed and stirred with the developer in the second conveying portion. When the toner is conveyed while being conveyed, the toner concentration in the developer partially increases and the newly replenished toner does not cause charging failure, and the newly replenished toner is well dispersed in the developer. , The developer is not deteriorated and the replenished toner is sufficiently charged to be used for development.
An object of the present invention is to make it possible to stably perform good image formation without causing a background fog in an image to be formed or causing toner to be scattered from a developing device to stain the inside of the image forming device. Is.

[0017]

According to the present invention, in order to solve the above-mentioned problems, a developer is conveyed while being stirred along the axial direction of a developing sleeve for sending the developer to the image carrier. The transport section and the second transport section that transports the developer in the opposite direction to the first transport section while stirring the developer are separated by a partition wall, and the developer is separated from the first transport section and the second transport section. In a developing device in which the toner is replenished from the toner replenishing portion to the second conveying portion side while circulating between the first and second conveying portions without opening at least one end portion of the partition wall. The height of the partition wall at the portion that reaches the end portions of the first and second transport portions without being opened is determined by the developer in the first transport portion and the second transport portion. To a height that can exceed Than it is.

Here, in the developing device of the present invention, the height of the partition wall in the portion which reaches the end portions of the first and second conveying sections without being opened as described above is determined by the first conveying section and the second conveying section. When adjusting the height of the developer in the transport section so that it can pass over this partition wall, an appropriate amount of developer is sequentially passed over the partition wall on the end side where the partition wall is not opened, and then the first transport section. From the first transport unit to the second transport unit and from the second transport unit to the first transport unit, and the developer does not deviate between the first transport unit and the second transport unit. It is necessary to set so that the sheet is smoothly conveyed and circulated between the second conveying section and the second conveying section.

Therefore, for example, the height of the partition wall that reaches the end portions of the first and second conveying portions without being opened is inclined such that the height gradually decreases toward the end portion side, or When the height of the partition wall in this portion is set to be a constant height, the transport speed of the developer transported in the first transport section and the second transport section is increased toward the end side where the opening is not opened. It is preferable to slow down.

[0020]

In the developing device according to the present invention, the developer is agitated by the partition wall as described above, and the developer is agitated in the first transport section and the second transport section, while the developer is stirred in the first transport section and the second transport section. And in the reverse direction to circulate the developer in the first and second transport sections, and at the same time, a part of the developer transported as described above is supplied to the developing sleeve to perform development. It is like this.

Then, as a result of supplying a part of the developer conveyed as described above to the developing sleeve and performing the development, the toner in the developer is consumed and the toner concentration in the developer is lower than a predetermined concentration. When the toner amount decreases, new toner is replenished from the toner replenishing unit to the second conveying unit side.

Here, in the developing device according to the present invention, at least one end of the partition wall is provided up to the end of the first and second conveying portions without opening as described above, and the end side is provided. Since the height of the partition wall at is such that the developer in the first transport section and the second transport section can pass over this partition wall, the end of the partition wall is opened to increase the height. As in the case of the above, not all of the developer is sent from the first transport section to the second transport section and from the second transport section to the first transport section through the opened end portion of the partition wall, but the partition wall is On the side of the lower end that is not opened, the developer sequentially crosses the partition wall before reaching the end and from the first transport unit to the second transport unit and from the second transport unit to the first transport unit. Will be sent.

Therefore, for example, when the partition wall reaches the end on the downstream side in the developer transport direction of the second transport unit, when new toner is supplied to the second transport unit as described above. While the replenished toner is being mixed and stirred with the developer in the second transport section and being guided to the downstream end, a part of this toner is distributed over the partition wall and sent to the first transport section. As a result, the replenished toner is rapidly dispersed throughout the developer, the toner concentration in the whole developer is quickly made constant, and the replenished toner is sufficiently mixed and stirred with the developer to be appropriately charged. .

On the other hand, in the case where the partition wall reaches the end portion on the downstream side in the developer conveying direction in the first conveying portion, the developer in the first conveying portion is mixed and agitated to the downstream end portion thereof. During the course of being guided, the developer gradually passes through the partition wall and is fed to the second transport section, and the toner replenished in the second transport section is transported while being mixed and stirred with the developer as described above. In the middle of the process, the developer sent from the first transport unit to the second transport unit over the partition wall is mixed, and the replenished toner is quickly dispersed in the entire developer, so that the toner concentration in the entire developer is increased. The toner is quickly stabilized, and the replenished toner is sufficiently mixed and stirred with the developer so that it is appropriately charged.

Further, when the partition wall reaches the end portions on both sides, the above two actions are combined, and the replenished toner is rapidly dispersed by the entire developer, and the toner concentration in the entire developer is increased. Quickly settles,
The replenished toner is sufficiently mixed and stirred with the developer to be appropriately charged.

Then, the developer is supplied to the developing sleeve in a state where the toner replenished as described above is appropriately charged, and the developer is guided to the image carrier by the developing sleeve and is used for development. The toner charged to the image carrier is supplied to the image carrier.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

(Embodiment 1) Also in the developing device in this embodiment, as shown in FIGS. 4 to 6, as in the conventional developing device, the developing sleeve 11 having the magnet roller 18 therein is image-carried. While being rotatably provided in the opening portion of the housing 10 so as to face the body 1, a partition wall 16 is provided in the housing 10 along the axial direction of the developing sleeve 11, and the interior of the housing 10 is defined by the partition wall 16. On the side of the developing sleeve 11, the developer 2 is mixed and agitated to be conveyed along the axial direction of the developing sleeve 11, and the first conveyer 13 and the developer are mixed and agitated. The second transport unit 15 that transports 2 in the opposite direction is separated.

The rotary shaft 12a is also provided in the first transfer section 13 as in the conventional developing device.
A first stirring and conveying member 12 provided with a stirring and conveying blade 12b and a scraping member 12c for scraping up the developer 2 around the
The first stirring / transporting member 12 is rotated, and the developer 2 in the first transporting section 13 is transferred to the developing sleeve 11.
Part of the developer 2 is supplied to the developing sleeve 11 while being conveyed along the axial direction of.

Also in the second conveying section 15, the second stirring and conveying member 14 is provided with a spiral stirring and conveying blade 14b around the rotary shaft 14a in the second conveying section 15 in a constant state. The second stirring and conveying member 14
Is rotated so that the developer 2 in the second transport unit 15 is mixed and stirred, and the developer 2 is transported in the direction opposite to that of the first transport unit 13 described above. A toner replenishing section 17 for replenishing toner is provided on the upstream side in the conveying direction of the developer 2, and new toner is replenished to the toner replenishing section 17 from a toner bottle (not shown) or the like, and the newly replenished toner is supplied. This toner supply unit 1
The second agitating / conveying member 14 feeds the sheet from 7 to the second conveying section 15.

Here, in the developing device of this embodiment, as shown in FIGS. 4 and 6, the partition wall 16 reaches the side walls 10a on both sides of the housing 10 and the first transfer portion 13 and the second transfer portion. The partition wall 16 is provided up to both end portions, and the height of the partition wall 16 is lowered from the center thereof toward the end portions on both sides, and development is performed in a portion where the height of the partition wall 16 is lowered in this way. Agent 2 is this partition wall 1
It is configured such that the developer 2 is sent to the first transport unit 13 from the second transport unit 15 and from the second transport unit 15 from the first transport unit 13 to pass the developer 2 to the first transport unit 13 and the first transport unit 13. It is arranged to circulate between the two conveyors 15. In addition, if the height of the partition wall 16 is lowered from the center toward the end portions on both sides as described above, the partition wall 1
Amount of the developer 2 sent from the center of 6 to the end portion over the partition wall 16 from the second transport unit 15 to the first transport unit 13 and from the first transport unit 13 to the second transport unit 15. Is gradually increased, and a sufficient amount of the developer 2 is supplied to the end portions of the first transport unit 13 and the second transport unit 15, and the developer 2 is supplied to either the first transport unit 13 or the second transport unit 15. There is no deviation to the side, and it becomes possible to smoothly circulate between the first transport unit 13 and the second transport unit 15.

In the developing device of this embodiment,
When the toner is supplied to the image carrier 1 to perform the development, the first and second agitating / conveying members 12 and 14 provided in the first conveying unit 13 and the second conveying unit 15 are rotated respectively. Agitating / conveying blades 12b, 14 provided on each agitating / conveying member 12, 14 by rotating them via shafts 12a, 14a.
While the developer 2 is mixed and stirred by b, the second transport unit 15 and the first transport unit 13 transport the developer in opposite directions.

Here, when the developer 2 is conveyed while being mixed and stirred in the second conveying portion 15 as described above, the height of the partition wall 16 of the developer 2 starts to decrease as described above. When the developer 2 is guided to the downstream side of the second transport unit 15 in the transport direction, the developer 2 is gradually fed from the second transport unit 15 over the partition wall 16 to the first transport unit 13.

On the other hand, in the first transport portion 13 into which the developer 2 is fed in this way, the developer 2 is transported in the opposite direction to the second transport portion 15 as described above, and the developer 2 is also transported. The developer 2 is scraped up by the scraping member 12c of the first agitating / conveying member 12, and a part of the developer 2 is supplied to the developing sleeve 11 having the magnet roller 18 therein and guided to the image carrier 2. After the toner in the developer 2 is supplied to the image carrier 2 and used for development, the developer 2 is returned to the inside of the first transport unit 13.

Further, as described above, the developer 2 is transported in the first transport unit 13 in the direction opposite to that of the second transport unit 15,
When the developer 2 is guided to the downstream side in the transport direction of the first transport unit 13 where the height of the partition wall 16 starts to decrease, the developer 2 gradually crosses the partition wall 16 from the first transport unit 13. And is sent to the second transport section 15, whereby the developer 2
Are circulated between the first transport unit 13 and the second transport unit 15.

When the toner in the developer 2 is supplied to the image carrier 1 as described above to develop the toner, the toner density in the developer 2 becomes lower than a predetermined value. The toner is supplied into the second conveying unit 15 through the toner replenishing unit 17 provided on the upstream side in the conveying direction of the second conveying unit 15, and the toner thus supplied is supplied to the second conveying unit 1.
The second agitating / conveying member 14 together with the developer 2 in the container 5 conveys them while mixing and stirring.

When new toner is replenished from the toner replenishing section 17 to the second conveying section 15 in this way, the toner concentration in the developer 2 becomes high at the beginning of the replenishment of the toner. Developer 2 with high toner density
While being mixed and stirred by the second stirring and conveying member 14 as described above, the second conveying unit 15 is crossed over the partition wall 16 from the first conveying unit 13 as described above while being conveyed through the second conveying unit 15. The developer 2 is fed into the developer 2, the toner concentration in the developer 2 is gradually reduced, and the developer 2 is provided downstream of the partition wall 16 in the transport direction of the second transport unit 15.
When the developer 2 is guided to the lower portion, the developer 2 is gradually fed from the second transport unit 15 over the partition wall 16 to the first transport unit 13.

For this reason, the developer 2 having a high toner concentration can be quickly dispersed over the partition wall 16 and circulated in the second transport section 15 and the first transport section 13 to be replenished. The toner is quickly dispersed throughout the developer 2,
The toner concentration in the developer 2 is quickly made constant, and the newly replenished toner is sufficiently mixed and stirred with the developer 2 to be appropriately charged.

As a result, in the developing device of this embodiment, even when new toner is replenished from the toner replenishing section 17, the newly replenished toner is quickly charged appropriately in the developer 2 and developed. As a result, a good image can be obtained without causing fogging in an image to be formed, uneven toner due to toner scattering, and uneven density in the formed image. It has become stable.

(Embodiment 2) The developing device of this embodiment is also the same as the developing device of the above-mentioned embodiment 1, and the partition wall 16 is also used.
7 is provided up to the end portions on both sides of the first transport portion 13 and the second transport portion 15 so as to reach the side walls 10a on both sides of the housing 10. However, in the developing device of this embodiment, as shown in FIG.
(A), the height of the partition wall 16 is set to a constant height, while as shown in (B) of the same figure, the first transfer unit 13 and the second transfer unit 15 One stirring transport member 1
2 and the second agitating / conveying member 14, the agitating / conveying blades 12 provided around the respective rotary shafts 12a, 14a.
The pitches of b and 14b are made smaller toward the downstream side from the central portion of the developer 2 in the transport direction, and the developer 2 is respectively fed in the first transport unit 13 and the second transport unit 15.
The transport speed of the item is slowed down toward the downstream side.

As described above, the first transfer section 13 and the second transfer section 1
5, when the transport speed of the developer 2 is slowed down toward the downstream side, the amount of developer is increased up to the end of the first transport unit 13 and the second transport unit 15 on the downstream side in the transport direction of the developer 2. 2 is introduced, and the partition wall 16 is formed in the same manner as in the developing device of the first embodiment.
The amount of the developer 2 which is sent from the second transport unit 15 to the first transport unit 13 and from the first transport unit 13 to the second transport unit 15 goes to the downstream side in the transport direction of the developer 2. As the developer 2 is gradually increased, a sufficient amount of the developer 2 is supplied to the end portions of the first transport unit 13 and the second transport unit 15, and the developer 2 is supplied to the first transport unit 13 and the second transport unit 15. It will not be biased to any of the above, and will be smoothly circulated between the first carrying section 13 and the second carrying section 15.

Also in the developing device of this embodiment, as in the case of the developing device of the first embodiment, the developer 2 carried by the first carrying section 13 and the second carrying section 15 is used.
While being guided from the central portion in the transport direction to the downstream side, they gradually pass over the partition wall 16 to the first transport portion 13 from the second transport portion 15 and from the first transport portion 13 to the second transport portion 15. Will be sent.

Therefore, also in the developing device of this embodiment, as in the developing device of the above-described first embodiment, the toner replenishing section 1 is used.
When new toner is replenished to the second transport unit 15 from 7, the replenished toner is quickly dispersed over the partition wall 16 to the second transport unit 15 and the first transport unit 13, and the developer 2 The toner density in the inside quickly becomes constant, and the newly replenished toner is sufficiently mixed and stirred with the developer 2, and is appropriately charged and used for development, so that fogging occurs in the formed image. As a result, it is possible to stably obtain a good image without causing unevenness of charge due to toner scattering and unevenness of density in the formed image.

(Third Embodiment) In the developing device of this embodiment, similarly to the developing devices of the first and second embodiments, the partition wall 16 and the first conveying portion 13 are provided so as to reach the side walls 10a on both sides of the housing 10. (2) Provide up to both ends of the transport section 15,
As shown in FIG. 8A, the partition wall 16 has a constant height, as in the developing device of the second embodiment.

Here, in the developing device of this embodiment, like the developing device of the second embodiment, the stirring and conveying blades 12 in the first stirring and conveying member 12 and the second stirring and conveying member 14 are used.
As shown in FIG. 8B, the pitch 2 of the stirring and conveying blades 12b and 14b of the first stirring and conveying member 12 and the second stirring and conveying member 14 is changed without changing the pitch of b and 14b.
While maintaining a constant value, the first stirring / transporting member 12 and the second stirring / transporting member 14 are axially arranged between the respective stirring / transporting blades 12b and 14b in the downstream side portion from the central portion of the developer 2 in the transporting direction. Along with the retention blades 12d and 14c, which protrude in the radial direction, are provided.

The agitating and conveying blades 12b and 14b are provided by the staying blades 12d and 14c thus provided.
And the height of the retaining blades 12d and 14c protruding in the radial direction is increased toward the downstream side of the developer 2 in the conveying direction.
In the first transport unit 13 and the second transport unit 15, the transport speed of the developer 2 is set to be slower toward the downstream side.

By doing so, as in the case of the developing device of Embodiment 2, the first carrying section 13 and the second carrying section 15 are provided.
A large amount of the developer 2 is guided to the downstream end portion of the developer 2 in the transport direction, passes the partition wall 16 to the second transport unit 15 to the first transport unit 13, and the first transport unit 1
The amount of the developer 2 sent from the No. 3 to the second transport unit 15 is
The developer 2 gradually increases toward the downstream side in the transport direction of the developer 2, and a sufficient amount of the developer 2 is supplied to the end portions of the first transport unit 13 and the second transport unit 15.
Does not deviate to either the first transport unit 13 or the second transport unit 15, and the first transport unit 13 and the second transport unit 15
It is smoothly circulated between and.

As a result, also in the developing device of this embodiment, the developer 2 carried by the first carrying section 13 and the second carrying section 15 is guided to the downstream side from the central portion of the developer 2 in the carrying direction. On the way, the toner is gradually fed over the partition wall 16 from the second transport unit 15 to the first transport unit 13, and from the first transport unit 13 to the second transport unit 15, and a new toner is fed from the toner replenishing unit 17. Toner is transferred to the second transport unit
5 is replenished, the replenished toner is
The toner density in the developer 2 is quickly made constant by being rapidly dispersed over the second transport unit 15 and the first transport unit 13, and the replenished toner is sufficiently mixed and stirred with the developer 2, Since it is charged to the surface and used for development, fogging does not occur in the formed image, toner is scattered and uneven charge occurs, and uneven density occurs in the formed image. , A good image can be stably obtained.

In each of the developing devices of Embodiments 1 to 3 described above, the partition walls 16 are located on both sides of the first carrying section 13 and the second carrying section 15 so as to reach the side walls 10a on both sides of the housing 10. The end portions are provided so that the supply port 16a and the return port 16b at both ends of the partition wall 16 are closed, but it is not always necessary to close both ends of the partition wall 16, and either one of the end portions may be closed. You may make it open.

For example, as shown in FIGS. 9 (A) and 9 (B), the partition wall 16 is opened at the end of the first transporting section 13 on the downstream side in the transporting direction of the developer 2, and the developer 2 is transferred to the first side. While providing a return port 16b for returning from the one carrying unit 13 to the second carrying unit 15, the partition wall 16 is provided up to the end of the second carrying unit 15 on the downstream side in the carrying direction of the developer 2, and the height of the partition wall 16 is increased. Is lowered from the central portion of the second transport portion 15 in the transport direction of the developer 2 toward the downstream side, and the developer 2 is transported to the second transport portion 15 at the portion where the height of the partition wall 16 is lowered in this way. From above to the partition wall 16 to be fed to the first transport section 13, or as shown in FIGS. 10A and 10B, on the downstream side in the transport direction of the developer 2 in the second transport section 15. Partition wall 16 at the end
And a supply port 16a for supplying the developer 2 from the second transport unit 15 to the first transport unit 13 is provided, while the partition wall 1 is provided.
6 is provided up to the end of the first transport unit 13 on the downstream side in the transport direction of the developer 2, and the height of the partition wall 16 is from the central portion of the first transport unit 13 in the transport direction of the developer 2 toward the downstream side. The developer 2 may be fed from the first transport section 13 over the partition wall 16 to the second transport section 15 at the portion where the height of the partition wall 16 is lowered.

Even in the developing device in which one of the ends of the partition wall 16 is opened as described above, the developer 2 conveyed in the first conveying section 13 or the second conveying section 15 is the same. While being guided from the central portion in the transport direction to the downstream side, it is gradually fed over the partition wall 16 from the second transport unit 15 to the first transport unit 13 or from the first transport unit 13 to the second transport unit 15. Therefore, the developer 2 is supplied to the supply port 16a and the return port 1 at both ends of the partition wall 16.
Compared with the conventional developing device that circulates through 6b,
The toner newly replenished from the toner replenishing unit 17 is quickly supplied to the developer 2 in the second conveying unit 15 and the first conveying unit 13.
When the toner is dispersed in the toner, the toner concentration becomes constant, and the replenished toner is sufficiently mixed and stirred with the developer 2 to be appropriately charged and used for the development, and fogging occurs in the formed image. It is possible to stably obtain a good image without causing toner unevenness and uneven charge, and uneven density in a formed image.

In the developing device shown in FIGS. 9A and 9B and FIGS. 10A and 10B, the partition wall 1 is used.
In providing 6 to the end portion, the height of the partition wall 16 is lowered from the central portion toward each closed end portion side, but this is shown in the second and third embodiments. When the partition wall 16 is provided to the end like a developing device, the height is made constant from the central part of the partition wall 16 to each closed end, while the first agitating / conveying member 12 and the second stirring / transporting member 12 are provided. The pitch of the stirring / transporting blades 12b, 14b provided on the stirring / transporting member 14 becomes smaller from the central portion toward the closed end portion,
Stirring blades 12d and 14c on the stirring and conveying blades 12b and 14b
May be provided, and the height of the retention blades 12d and 14c protruding in the radial direction may be increased from the central portion toward the closed end portion.

Further, in each of the above embodiments,
Although the example of the developing device in which both the first transporting portion 13 and the second transporting portion 15 are horizontally provided has been shown, the type of the developing device is not limited to such a type, and for example, the second transporting portion 15 may be used. May be inclined upward toward the downstream side in the conveying direction of the developer 2.

[0054]

As described above in detail, in the developing device according to the present invention, while stirring the developer in the first transport section and the second transport section separated by the partition wall,
At least one end of the partition wall is caused to flow in the opposite direction between the first transport section and the second transport section and to circulate the developer between the first transport section and the second transport section. Provided up to the end portions of the first and second conveying portions without opening, and lowering the height of the partition wall on this end portion side,
Before the developer reaches this end, the developer is sequentially passed over the partition wall to be sent from the first transport unit to the second transport unit and from the second transport unit to the first transport unit. As compared with the conventional developing device that circulates through the supply port and the return port in the sheet feeding unit, when the toner is newly replenished from the toner replenishing unit to the second conveying unit side, the replenished toner is quickly supplied to the second conveying unit By being dispersed in the developer in the first transporting section, the toner concentration in the developer quickly becomes constant at an appropriate concentration.

As a result, in the developing device according to the present invention, when new toner is replenished from the toner replenishing portion to the second conveying portion side, the replenished toner is quickly dispersed in the developer and becomes a developer. After sufficient mixing and stirring, the developer is not deteriorated and the replenished toner is quickly and properly charged and used for development, and the formed image has background fog or toner from the developing device. It is possible to stably perform good image formation without scattering and soiling the inside of the image forming apparatus to cause charge unevenness or density unevenness in the formed image.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which the inside of a conventional developing device is viewed from a side surface side.

FIG. 2 is a schematic cross-sectional view showing a state in which the inside of the conventional developing device is viewed from the upper surface side.

FIG. 3 is a schematic cross-sectional view showing a state on the side of a second transport unit in a conventional developing device.

FIG. 4 is a schematic cross-sectional view showing a state in which the inside of the developing device according to the first embodiment of the present invention is viewed from the side surface side.

FIG. 5 is a schematic cross-sectional view showing a state of the inside of the developing device of Embodiment 1 of the present invention as viewed from the upper surface side.

FIG. 6 is a schematic cross-sectional view showing a state of the developing device according to the first embodiment of the present invention on the side of the second transport unit.

FIG. 7 is a schematic cross-sectional view showing a state of the developing device according to the second embodiment of the present invention on the side of the second transport portion and a state of the inside of the developing device seen from the upper surface side.

FIG. 8 is a schematic cross-sectional view showing a state of the developing device according to the third embodiment of the present invention on the side of the second transport unit and a state of the inside viewed from the upper surface side.

FIG. 9 is a view showing a state of the second transport portion side in the developing device in which only a return port for returning the developer from the first transport portion to the second transport portion is opened at the end portion of the partition wall in the embodiment of the present invention, and its state. It is a schematic sectional drawing which showed the state which looked at the inside from the upper surface side.

FIG. 10 is a view showing a state of the second transport unit side in the developing device in which only the supply port for supplying the developer from the second transport unit to the first transport unit is opened at the end of the partition wall in the embodiment of the present invention. It is the schematic sectional drawing which showed the state which looked at the inside from the upper surface side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developer 11 Development sleeve 12 1st stirring conveyance member 13 1st conveyance part 14 2nd stirring conveyance member 15 2nd conveyance part 16 Partition wall 17 Toner supply part

Claims (1)

[Claims] 1. A first transport section for transporting the developer while stirring the developer along the axial direction of a developing sleeve that transports the developer to the image carrier, and a direction opposite to the first transport section while stirring the developer. The second transport unit to be transported to the second transport unit is separated by a partition wall, the developer is circulated between the first transport unit and the second transport unit, and the toner is supplied from the toner replenishing unit to the second transport unit side. In a developing device configured to replenish the toner, at least one end of the partition wall is provided to the end of the first and second transport units without opening, and the first and second transports are not opened. A developing device, characterized in that the height of the partition wall at the portion reaching the end of the section is set to a height at which the developer in the first transport section and the second transport section can pass over the partition wall.