JPH10123817A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain an excellent image having sufficient image density by feeding a developer on a developer carrier, and entirely recovering the developer after developing from the developer carrier to a first transporting part. SOLUTION: This device is provided with a magnet member 12 arranging plural fixed magnets N and S... on the peripheral side of the developer carrier 11 in a cylindrical shape disposed opposite to the image carrier 1. Then, the device is respectively provided with the first transporting part 13a in a bottom part side of the device main body 10 inside, and the second transporting part 13b, in the upper part of the first transporting part 13a across a partition wall 14 corresponding to the first transporting part 13a. In a section opposite to the first transporting part 13a, the fixed magnets N... and N provided in same polarity is disposed on the magnet member 12 so as to adjoin each other with a specific space, the developer after developing is entirely detached from the developer carrier 11 by the repulsive magnetic force between the fixed magnets N... and N, and recovered in the first transporting part 13a. Moreover, the developer is circulated between first and second transporting parts 13a and 13b by providing first and second circulation ports in the partition wall 14.

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 for developing a latent image formed on an image carrier in an image forming apparatus such as a copying machine or a printer, and more particularly to a developing device using a developer carrier. In a developing device that transports a developer to a development area facing the image carrier and develops a latent image formed on the image carrier, a first transport unit that is juxtaposed to face the developer carrier. And a second transport section.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a developing device that transports a developer to a developing area facing an image carrier to develop a latent image formed on the image carrier is used. Various types were used.

As one of such developing devices, as shown in FIG. 1, an inner peripheral side of a cylindrical developer carrier 2 which rotates and guides the developer to the image carrier 1 is provided. A plurality of fixed magnetic poles N, S... Are provided with a magnet member 3 arranged in a circumferential direction thereof, and a developer is mixed and stirred in an apparatus main body 4 so as to face the developer carrier 2 along the axial direction thereof. Transport section 4a and second transport section 4 for transporting
b are arranged at upper and lower positions via a partition wall 6 and feed members 5a and 5b are respectively provided to the first transport section 4a and the second transport section 4b.
b, and by rotating these feed members 5a and 5b,
It has been known that the developer is transported in the opposite direction between the first transport unit 4a and the second transport unit 4b along the axial direction of the developer carrier 2 while mixing and stirring the developer.

In this developing device, the developer is conveyed along the axial direction of the developer carrier 2 while being mixed and stirred by a rotating feeding member 5a in a first conveying section 4a located above. The developer is supplied to the rotating developer carrier 2, and while the developer supplied by the magnet member 3 provided on the inner peripheral side of the developer carrier 2 is held on the developer carrier 2, The developer is conveyed to the image carrier 1 by the rotation of the developer carrier 2, and the amount of the developer conveyed in this way is regulated by the regulating member 7, and then the developer faces the image carrier 1. It was guided to a development area to perform development.

After the developer is guided by the developer carrier 2 to the development area facing the image carrier 1 and development is performed, the developer after development is removed by the rotating developer carrier 2. The magnet member 3 is returned to the inside of the apparatus main body 4 and returns to the above-described position by a repulsive magnetic force of the magnet member 3 magnetized to the same polarity of N and N poles at a portion facing the second transport portion 4b at a required interval. The collected developer is separated from the developer carrier 2 and collected in the second transport unit 4b, and the collected developer is sent to the first transport unit 5b provided in the second transport unit 4b. The developer D is transported in a direction opposite to the transporting section 4a, and the developer D is passed through the circulation ports 7a and 7b provided at both ends of the partition 6 as shown in FIG.
It circulates between the transport section 4a and the second transport section 4b.

However, when the developer D is supplied to the developer carrier 2 in the first transport section 4a as described above, the developer D after development is collected in the second transport section 4b. As shown in FIG. 2, the developer D in the first transport unit 4a gradually decreases from the upstream side to the downstream side in the transport direction, and the developer D in the first transport unit 4a is downstream in the transport direction of the developer D. Developer carrier 2
The developer D is hardly supplied to the developer carrier 2 in a portion of the first transport unit 4a on the downstream side in the transport direction of the developer D. There is a problem that the image is blurred. On the other hand, in the second transport section 4b for collecting the developer D, the amount of the developer D gradually increases from the upstream side to the downstream side in the transport direction of the developer D, and the developer D And the developer D spills out of the developing device.

In the above-described developing apparatus, when the developer is guided to the developing area facing the image carrier 1 by the developer carrier 2 and the development is performed, the toner concentration in the developer decreases. To supply toner to the developer in the developing device.

However, when the toner is replenished in this manner, the toner is circulated between the first transporting section 4a and the second transporting section 4b to be dispersed throughout the developer in the developing device, so that much toner is required. It takes time, uneven density occurs in the formed image, the replenished toner is used for development in a state where it is not sufficiently charged, and the formed image fogs or the toner scatters outside. And so on.

For this reason, in recent years, Japanese Patent Laid-Open No.
As shown in Japanese Patent No. 33691, the amount of the developer transported in each of the first and second transport units is increased with respect to the amount of the developer transported to the image carrier by the developer carrier, One in which the bias of the developer in each transport section is suppressed, Japanese Patent Publication No. 5-82942 and Japanese Patent Publication No.
As disclosed in Japanese Patent Application Laid-Open No. 82944, there has been proposed an apparatus in which a developer is supplied to a developer carrier from a first transport section and a second transport section disposed above and below, respectively.

However, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-333691, the amount of the developer conveyed to the image carrier by the developer carrier is determined based on the amount of the developer conveyed in the first and second conveyors. Even when the amount of the agent is increased,
It is difficult to sufficiently suppress the above-described bias of the developer in the first transport unit and the second transport unit. Particularly, when performing image formation at high speed, the image carrier is The amount of the developer transported to the first transport unit and the second transport unit is very difficult to be increased than the amount of the developer. .

Further, as disclosed in Japanese Patent Publication No. 5-82942 and Japanese Patent Publication No. 5-82944, the first transport unit and the second transport unit supply the developer to the developer carrying member, respectively. In such a case, the developer returned to the apparatus main body after the development is not sufficiently separated from the developer carrier, and the developer once used for the development is directly guided to the development area by the developer carrier and is again subjected to the development. However, there has been a problem that the density of an image to be formed is lowered.

[0012]

SUMMARY OF THE INVENTION According to the present invention, when a developer is transported by a developer carrier to a development area facing the image carrier and development is performed, the developer is arranged so as to face the developer carrier. To solve the above-described various problems in a developing device configured to supply a developer to a developer carrier while circulating the developer between a first transport unit and a second transport unit provided. Is the subject.

That is, according to the present invention, in the above-described developing apparatus, the developer is supplied to the developer carrier while circulating the developer between the first transport section and the second transport section. When the developer is later collected from the developer carrying member, it is possible to suppress the occurrence of bias in the developer in the first transport unit and the second transport unit, and to cause unevenness in the density of the formed image, The developer does not spill out from the developing device, and the developer after development is surely detached from the developer carrier, so that new developer is supplied to the developer carrier. It is an object of the present invention to ensure that a good image having a sufficient image density can be stably obtained without reducing the density of an image to be formed by using the developer in the development again. is there.

Further, according to the present invention, when toner is supplied to the developing device, the toner is promptly dispersed throughout the developer in the developing device, so that the density unevenness of an image formed as in the prior art is improved. It is an object to suppress occurrence of fogging and scattering of toner to the outside.

[0015]

In the developing device according to the present invention, in order to solve the above-described problems, the developer is transported by a developer carrier to a developing area facing the image carrier to perform development. In the developing device, the developer is supplied to the developer carrier and the developer after the development is collected from the developer carrier while collecting the developer from the axial center of the developer carrier at both ends or in the axial direction. A first transport unit that transports the developer from both ends to the center, and a developer that is separated by the first transport unit and the partition and that transfers the developer from both ends in the axial direction of the developer carrier opposite to the first transport unit to the center or the shaft. By arranging the second transport section that transports from the center in the direction to both ends so as to face the developer carrier, the developer is circulated between the first transport section and the second transport section. A circulation port was provided.

In the developing device according to the present invention, the developer is supplied to the developer carrier in the first transport section, and the supplied developer is opposed to the image carrier by the developer carrier. The developer is transported to the developing area, and the developer after the development is recovered from the developer carrier to the first transport section. The first transport section and the second transport section perform the development as described above. The developer is transported, and the developer is circulated between the first transport unit and the second transport unit through a circulation port.

As described above, in the developing device of the present invention, the developer is supplied to the developer carrier while the developer is transported in the first transport section, and the developer after the development is transported to the first transport section. To collect all of the developer from the developer carrier in the section, the developer in the first transport section gradually decreases from the upstream side to the downstream side in the transport direction of the developer and decreases as the developer in the first transport section as in the related art. Deviation does not occur, a stable amount of developer is always supplied to the entire axial direction of the developer carrier, and density unevenness does not occur in the formed image. In addition, the developer in the second transport section does not gradually increase from the upstream side to the downstream side in the developer transport direction, thereby preventing the developer from being biased. Also eliminated that spill out.

Further, in the developing device of the present invention, as described above, all of the developer after the development is recovered from the developer carrier in the first transport section. Since the developer is supplied from the first transport section, the developer used for development is not used again as it is in the related art, and the density of the formed image is not reduced. An image having an image density can be obtained stably.

Further, in the developing device according to the present invention, when the developer is circulated between the first transport section and the second transport section, as described above, the developer is transferred to the developer carrying member in the first transport section. While the developer is conveyed from the center in the axial direction to both ends or from the center in the axial direction to both ends, the developer is conveyed in the second conveying portion from both ends in the axial direction of the developer carrier to the central portion or the shaft, opposite to the first conveying portion. The developer is transported from the center in the direction to both ends, and the developer is circulated between the first transport unit and the second transport unit through the respective circulation ports. Therefore, the developer is transported between the first transport unit and the second transport unit. The amount of time required for the developer to circulate is reduced due to the shorter distance circulated between the developing device, and when toner is supplied to the developing device, the supplied toner is quickly dispersed throughout the developer in the developing device. It will be charged properly To become the image or cause density unevenness and head to be formed, toner is less likely that scattered to the outside.

Here, the position at which the first transport section and the second transport section are juxtaposed is not particularly limited, but the first transport section is provided below the second transport section via a partition wall. In this case, a developer feeding unit that feeds the developer from the first transport unit located below to the second transport unit located above through the circulation ports provided at both ends or the center in the axial direction of the developer carrier is provided. To be provided. On the other hand, when the first transport unit is provided above the second transport unit via the partition wall, the second transport unit located below through the circulation ports provided at the axial center or at both ends of the developer carrier. And a developer feeding means for feeding the developer to the first transporting unit located above.

Here, as described above, when the developer is fed from the lower transport section to the upper transport section by the developer feeding means through the circulation port, stress such as pressure is applied to the developer. Not to
It is preferable to feed the developer, for example,
It is preferable that the developer is sent to a transport unit located above using a magnetic force or the like of a magnet member. The magnet member includes a developer carrying member that holds the developer on a developer carrying member. It is also possible to use one provided on the inner peripheral side of the body or use another magnet member.

[0022]

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

(Embodiment 1) In a developing device according to this embodiment, as shown in FIGS.
Are provided on the inner peripheral side of a cylindrical developer carrier 11 provided opposite to the magnet member 12 and a plurality of fixed magnetic poles N, S...
And the device main body 10 so as to face each other along the axial direction.
The first transport unit 13a is provided on the lower side of the first transport unit 13a.
a second transport unit 13b is provided above the first transport unit 13a via the first transport unit 13a and the partition wall 14, and a feed member that transports the developer to the first transport unit 13a and the second transport unit 13b while mixing and stirring the respective developers. 15a and 15b are provided.

The feed members 15a, 15a
As shown in FIG. 4, the developer is conveyed from the central portion in the axial direction of the developer carrier 11 to both ends while the first carrier 13a is rotated while mixing and stirring the developer. In the second transport section 13b, the developer carrier 11 is transported from both ends in the axial direction to the central section, in reverse to the first transport section 13a.

Here, in the developing device according to this embodiment, the first transport unit 1 on the lower side of the apparatus main body 10 is used.
In 3a, the developer is supplied to the developer carrier 11, and the developer after development is all recovered in the first transport unit 13a. Thus, the first transport unit 13a In order to collect all the developer after development from the developer carrier 11,
At a portion facing the first transport portion 13a, fixed magnetic poles N, N having the same polarity as the magnet member 12 provided on the inner peripheral side of the developer carrier 11 are adjacent to each other with a required interval. And the developer after development is applied to the developer carrier 1 by the repulsive magnetic force between the fixed magnetic poles N, N.
1, and are collected in the first transport unit 13a.

On the other hand, in the second transport section 13b, the partition 14 is extended between the second transport section 13b and the developer carrier 11, so that the second transport section 13b and the developer carrier 11 is separated.

In the developing device of this embodiment, when the developer is circulated between the first transport section 13a and the second transport section 13b, the first transport section 1
When the developer is fed from 3a to the second transport section 13b, as shown in FIGS. 4 and 5, the second transport section 13b and the developer carrier 11 A first circulation port 16a
And the arrangement of the fixed magnetic poles in the magnet member 12 provided on the inner peripheral side of the developer carrier 11 is changed, and as shown in FIG.
In a portion close to 6a, fixed magnetic poles S, S having the same polarity are provided so as to be adjacent to each other with a required interval.

Then, the developer is supplied from the first transport section 13 a to the developer carrier 11, and the developer is rotated by the rotation of the developer carrier 11 so that the first carrier at both ends in the axial direction of the developer carrier 11 is supplied. Through the circulation port 16a, the developer is separated from the developer carrier 11 by the repulsive magnetic force between the fixed magnetic poles S, and the developer is transported through the first circulation port 16a for the second conveyance. This is supplied to the section 13b. In this way, the developer is first
Second transport unit 13b located above transport unit 13a
When the developer is fed to the developer, the developer is not aggregated due to pressure applied to the developer.

On the other hand, from the second transport section 13b to the first transport section 1
When feeding the developer into the developer carrier 3a, as shown in FIGS. 4 and 6, a slit is formed in the partition wall 14 between the first transport unit 13a and the second transport unit 13b at the axial center of the developer carrier 11. A second circulation port 16b in the shape of a circle is provided, and the second transport section 13 is passed through the second circulation port 16b.
b, the developer is fed into the first transport section 13a.

In developing the latent image formed on the image carrier 1 by the developing device of this embodiment,
A fixed magnetic pole provided at a position close to the regulating member 17 in the magnet member 12 on the inner peripheral side of the developer carrier 11 by supplying the developer from the first transport section 13 a to the rotating developer carrier 11. The developer is held on the developer carrier 11 by the magnetic force of N, and the amount of the developer thus held on the developer carrier 11 is controlled by the regulating member 1.
7, the amount of the developer conveyed by the developer carrier 11 is adjusted.

After the amount of the developer conveyed by the developer carrier 11 is adjusted by the regulating member 17 as described above, the developer is conveyed to the image carrier 1 by the rotation of the developer carrier 11. After the developer is transported to the area and the latent image formed on the image carrier 1 is developed by the developer, the developer on the developer carrier 11 is transferred to the first transport unit 13 a with the rotation of the developer carrier 11. Return to

The fixed magnetic poles N, N provided on the magnet member 12 so as to be adjacent to each other with a required interval in the portion facing the first transport section 13a as described above.
All the developer returned by the repulsive magnetic force is removed from the developer carrier 11 and collected in the first transport unit 13a, and then the new developer is developed from the first transport unit 13a as described above. The developer is supplied to the agent carrier 11, and the operation is repeated to perform the development. This way,
A new developer is always supplied to the developer carrier 11, and the density of an image formed by using the developer used for development again as it is in the conventional art is reduced. Therefore, an image having a sufficient image density can be stably obtained.

In the developing device of this embodiment, the developer is supplied to the developer carrier 11 in the first transport section 13a as described above, and the developer after the development is completely removed from the developer carrier 11. Since the developer is collected, the amount of the developer does not gradually decrease toward the downstream side in the developer transport direction in the first transport unit 13a. A constant amount of the developer is stably supplied in the entire axial direction of the toner, and the formed image does not have density unevenness and the like. The developer does not spill out of the developing device by gradually increasing the amount of the developer as going toward.

Further, in the developing device of this embodiment, the developer is transported between the first transport portion 13a and the second transport portion 13b between the axial center portion of the developer carrier 11 and both end portions in the axial direction. Since the developer is circulated between the first transport unit 13a and the second transport unit 13b, the distance for circulating the developer is shortened, and the time required for the developer to circulate is reduced. Even when toner is replenished to the developing device, the replenished toner is promptly dispersed throughout the developer in the developing device and is appropriately charged, resulting in uneven density and fogging of a formed image. Thus, scattering of the toner to the outside is reduced.

In the developing device of this embodiment, when the developer is fed from the first transport section 13a to the second transport section 13b located above the first transport section 13a, the shaft of the developer carrier 11 is moved as described above. At both ends in the direction, a first circulation port 16a is provided in each of the partition walls 14 between the second transport portion 13b and the developer carrier 11, and the magnet provided on the inner peripheral side of the developer carrier 11 is provided. Member 1
The arrangement of the fixed magnetic poles in 2 was changed,
The second transport unit 1 located above the first transport unit 13a
The developer feeding means for feeding the developer to 3b is not particularly limited to the above.

For example, as shown in FIGS. 7 and 8, the magnet member 12 provided on the inner peripheral side of the developer carrier 11 is provided.
, The positions of the fixed magnetic poles N, S,.
Without changing at both axial ends of the first
In the vicinity of the circulation port 16a, a magnet 18 having the same S pole is arranged on the outer peripheral side of the developer carrier 11 so as to face the fixed magnetic pole S of the magnet member 12, respectively. Developer carrier 11 due to the repulsive magnetic force of the fixed magnetic pole S of the
The developer conveyed by the developer carrier 11
The developer is removed from above, and the developer is sent to the second transport section 13b through the first circulation ports 16a. Alternatively, as shown in FIGS.
In the vicinity of the circulation port 16a, a scraper 19 is provided so as to be in contact with the surface of the developer carrier 11, and the developer conveyed by the developer carrier 11 by each scraper 19 is placed on the developer carrier 11. , And the developer can be sent to the second transport section 13b through the first circulation ports 16a.

Further, instead of providing the first circulation port 16a in the partition wall 14 between the second transport portion 13b and the developer carrier 11 as described above, as shown in FIGS. At both ends in the axial direction of the agent carrier 11, first circulation ports 16 a are respectively provided in the partition walls 14 between the first conveyance section 13 a and the second conveyance section 13 b, and these first circulation ports 16 a are provided in the first circulation ports 16 a. A sleeve-shaped developer feed member 20 is provided, and a magnet roller 21 provided with fixed magnetic poles N, N, S is provided on the inner peripheral side of each developer feed member 20. The developer in the first transport section 13a is held on the surface of each developer feeding member 20 by the magnetic force, and each developer feeding member 20 is rotated so that each of the first circulation ports 16 is rotated.
a, and the developer is guided to the second transport portion 13b located above, and the developer is fed to each developer feed member 20 by the repulsive magnetic force of the fixed magnetic poles N, N of the magnet roller 21.
It is also possible to separate from the second transport unit 13b.

In the developing device according to this embodiment, the developer is transported between the first transport portion 13a and the second transport portion 13b between the central portion in the axial direction of the developer carrier 11 and both end portions in the axial direction. When the developer is circulated, the developer is transported from the axial center of the developer carrier 11 to both ends in the first transport unit 13a, while the second transport unit 13b
In the first embodiment, the developer is conveyed from both axial ends to the center of the developer carrier 11 in the opposite direction to the first carrier 13a. Conversely, the developer is conveyed in the first carrier 13a. While the developer carrier 11 is transported from both axial ends to the center, the second carrier 13b can transport the developer carrier 11 from the axial center to both ends. In this case, Is provided with a first circulation port 16a at the center and a developer feeding means for feeding developer from the first conveyance section 13a to the second conveyance section 13b located above the first circulation port 16a through the first circulation port 16a. Agent carrier 1
1 at the center in the axial direction.

(Embodiment 2) In the developing device of this embodiment, similarly to the developing device of Embodiment 1 described above, as shown in FIGS. A plurality of fixed magnetic poles N, S... Are provided on the inner peripheral side of the cylindrical developer carrier 11 in a circumferential direction.

On the other hand, in the developing device according to this embodiment, the developer is applied to the developer carrier 11 on the upper side in the apparatus main body 10 so as to face the developer carrier 11 along the axial direction thereof. The first transport unit 1 that supplies and collects all of the developer after development from the developer carrier 11
3a, the first transport unit 13a and the partition 14
The second transport unit 13b is disposed below the developer carrier 1 via
1 is provided along the axial direction.

The first transport section 13a and the second transport section 13b are respectively provided with feed members 15a and 15b for transporting the developer while mixing and agitating the developer. These feed members 15a and 15b are rotated. While mixing and stirring the developer, as shown in FIG.
a, the developer is conveyed from the axial center of the developer carrier 11 to both ends, while the second carrier 13b is opposite to the first carrier 13a.
Are transported from both axial ends to the center.

Here, in the developing device in this embodiment, in order to collect all the developer after the development in the first transport section 13a, the above-mentioned developer carrying portion is provided in a portion opposed to the first transport section 13a. Fixed magnetic poles N, N having the same polarity are provided adjacent to a magnet member 12 provided on the inner peripheral side of the body 11 with a required interval therebetween, and the repulsive magnetic force between the fixed magnetic poles N, N causes the magnetic pole after development to be formed. The first developer is released from the developer carrier 11 and the first
At the transport section 13a, the partition 14 is extended between the second transport section 13b and the developer carrier 11, and the second transport section 13b and the developer carrier 1 are extended.
1 is separated.

In the developing device according to this embodiment, when the developer is circulated between the first transport section 13a and the second transport section 13b, the developer is transferred from the first transport section 13a to the second transport section 13b. When feeding the developer, as shown in FIGS. 14 and 15, the first transport portion 13 a and the second transport portion 13 a are provided at both ends in the axial direction of the developer carrier 11.
A first circulation port 16a is opened in each of the partition walls 14 between the first conveyance section 13b and the conveyance section 13b, and the developer in the first conveyance section 13a is supplied to the second conveyance section 13b through these first circulation ports 16a. I have.

On the other hand, from the second transport section 13b to the first transport section 1
14 and FIG.
As shown in FIG. 6, a second circulation port 16b having a required width is provided in the partition wall 14 between the second transport section 13b and the developer carrier 11 at the central portion in the axial direction of the developer carrier 11. Then, the developer in the second transport unit 13b is held by the developer carrier 11, and the developer is guided to the first transport unit 13a through the second circulation port 16b by the rotation of the developer carrier 11, and In the portion opposed to the first transport portion 13a, the developer is separated from the developer carrier 11 by the repulsive magnetic force between the fixed magnetic poles N provided on the magnet member 12 with a predetermined interval as described above. It is sent to one transport section 13a.

Thus, the developer is supplied to the second transport section 13b.
From the first transport unit 13a to the second transport unit 13b located above the first transport unit 13a in the first embodiment. The pressure does not cause the developer to aggregate.

In developing the latent image formed on the image carrier 1 by the developing device of this embodiment,
The developer is supplied from the first transport unit 13 a to the rotating developer carrier 11, and is fixed to the magnet member 12 on the inner peripheral side of the developer carrier 11 at a position close to the regulating member 17. The developer is held on the developer carrier 11 by the magnetic force of the magnetic pole N, and the amount of the developer thus held on the developer carrier 11 is regulated by the regulating member 17 and transported. The amount of the developer is adjusted, and the developer is conveyed to a development area facing the image carrier 1 by rotating the developer carrier 11 to develop the latent image formed on the image carrier 1.

After the development is performed in this manner, the developer on the developer carrier 11 is returned to the first transport section 13a with the rotation of the developer carrier 11, and the developer is transferred as described above. In the portion facing the first transport portion 13a, the developer is entirely separated from the developer carrier 11 by the repulsive magnetic force between the fixed magnetic poles N provided at a predetermined interval on the magnet member 12, and the first transport portion Then, the developer is supplied from the first transport unit 13a to the developer carrier 11 as described above, and the operation is repeated to perform the development.

In this way, as in the case of the developing device of the first embodiment, a new developer is always supplied to the developer carrier 11, and an image having a sufficient image density is stabilized. And the first transport unit 13a
In the first embodiment, the amount of the developer does not gradually decrease toward the downstream side in the developer transport direction, and a constant amount of the developer is supplied from the first transport unit 13a to the entirety of the developer carrier 11 in the axial direction. It will be supplied stably, and there will be no density unevenness etc. in the formed image,
Further, in the second transport section 13b, the amount of the developer gradually increases toward the downstream side in the developer transport direction, so that the developer does not spill out of the developing device.

Further, in the developing device of this embodiment, as in the case of the developing device of the first embodiment, the developer is provided between the central portion in the axial direction of the developer carrier 11 and both end portions. To the first transport unit 13a and the second transport unit 13
b, the distance for circulating the developer between the first transport section 13a and the second transport section 13b is shortened, and the time required for the developer to circulate is reduced. Thus, even when toner is supplied to the developing device, the supplied toner is promptly dispersed throughout the developer in the developing device and appropriately charged,
The occurrence of uneven density and fogging in the formed image and the scattering of toner to the outside are reduced.

In the developing device according to this embodiment, the first transport unit 13b is located above the first transport unit 13b.
When the developer is fed into the transport section 13a, the partition 14 between the second transport section 13b and the developer carrier 11 at the axial center portion of the developer carrier 11 has a second width having a required width as described above. Although the circulation port 16b is provided, the width of the second circulation port 16b can be further increased as shown in FIG.

Further, as in the developing device of this embodiment, the second transport unit 1 is provided at the axial center of the developer carrier 11.
The partition 14 between the developer carrier 11 and the developer carrier 11
Instead of providing the circulation port 16b of FIG.
As shown in (2), a second circulation port 16b is provided in the partition wall 14 between the second transport section 13b and the first transport section 13a at the central portion in the axial direction of the developer carrier 11, and the second circulation port 16b is provided. A developer feeding member 20 in the form of a sleeve is arranged at a portion 16b, and fixed magnetic poles N, N, S are provided on the inner peripheral side of the developer feeding member 20.
1, the developer in the second transport section 13b is held on the surface of the developer feeding member 20 by the magnetic force of the magnet roller 21, and the developer feeding member 20 is rotated to rotate the second circulation port 16b. The developer is guided to the first transporting portion 13a located above, and the developer is separated from the developer feeding member 20 by the repulsive magnetic force of the fixed magnetic poles N, N of the magnet roller 21 so that the first transporting portion 13a
It is also possible to send it to a.

Further, in the developing device of this embodiment, the developer is transported between the first transport portion 13a and the second transport portion 13b between the central portion in the axial direction of the developer carrier 11 and both end portions. In circulating the developer, the developer is transported from the axial center of the developer carrier 11 to both ends in the first transport section 13a, while the second transport section 13b
In the first embodiment, the developer is conveyed from both axial ends to the center of the developer carrier 11 in the opposite direction to the first carrier 13a. Conversely, the developer is conveyed in the first carrier 13a. While the developer carrier 11 is transported from both axial ends to the center, the second carrier 13b can transport the developer carrier 11 from the axial center to both ends. In this case, Is provided with a second circulation port 16b at both ends, and a developer feeding means for feeding the developer from the second conveyance section 13b to the first conveyance section 13a located above the second circulation port 16b through the second circulation port 16b. Agent carrier 1
1 at both ends in the axial direction.

[0052]

As described above in detail, in the developing device according to the present invention, the developer is supplied between the first transport section and the second transport section which are arranged side by side so as to face the developer carrier. Supplying the developer to the developer carrier while circulating,
When the developer is transported by the developer carrier to a development area facing the image carrier to develop the latent image formed on the image carrier, the developer is transported to the developer carrier in the first transport unit. In addition to supplying the developer, all the developer after the development is collected from the developer carrier in the first transport unit. Therefore, as in the conventional case, the developer in the first transport unit is downstream from the upstream side in the developer transport direction. The developer in the first transport portion is not deviated gradually, and the amount of the developer is always supplied to the developer carrier in the axial direction. As a result, a good image without density unevenness can be stably obtained, and the developer in the second transport section gradually increases from the upstream side to the downstream side in the developer transport direction, so that the developer becomes Body Also no longer be called out is.

Further, in the developing device of the present invention, since the developer after the development is completely recovered from the developer carrier in the first transport section as described above, a new development is performed on the developer carrier. Since the developer is supplied from the first transport section, the developer used for development is not used again as it is in the related art, and the density of the formed image is not reduced. An image having an image density can be obtained stably.

Further, in the developing device of the present invention,
In the first transport section, the developer is transported from the central portion in the axial direction to both ends or in the axial direction from both ends to the central portion of the developer carrier, while the developer is transported in the second transport section in the opposite direction to the first transport section. The developer carrying member is conveyed from both ends in the axial direction to the central portion or from the central portion in the axial direction to both ends, and the developer is circulated between the first conveying portion and the second conveying portion through each circulation port. In addition, when the developer is circulated between the first transport section and the second transport section, the distance required to circulate the developer is reduced, and when the developer is replenished with toner, The resulting toner is promptly dispersed throughout the developer in the developing device and is appropriately charged, so that the formed image is less likely to have uneven density and fogging and the toner is scattered to the outside. Was.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a conventional developing device in which a first transport unit and a second transport unit are vertically arranged via a partition so as to face a developer carrier.

FIG. 2 is an explanatory cross-sectional view showing a state in which a developer is biased in a first transport unit and a second transport unit in the conventional developing device shown in FIG. 1;

FIG. 3 is a schematic cross-sectional view of a portion of the developing device according to the first embodiment of the present invention in which a circulation port is not provided between a first transport unit and a second transport unit.

FIG. 4 is a cross-sectional explanatory view showing a state in which a developer is circulated by providing first and second circulation ports in a partition wall between a first conveyance unit and a second conveyance unit in the developing device of the first embodiment. It is.

FIG. 5 is a schematic cross-sectional view of a portion of the developing device according to the first embodiment, in which a first circulation port for feeding a developer from a first transport unit located below to a second transport unit located above is provided. .

FIG. 6 is a schematic cross-sectional view of a portion of the developing device according to the first embodiment, in which a second circulation port for feeding a developer from a second transport unit located above to a first transport unit located below is provided. .

FIG. 7 is a first modification of the developing device according to the first embodiment, in which a first circulation port for feeding a developer from a first transport unit located below to a second transport unit located above is provided. FIG.

FIG. 8 is a perspective view of a developing device according to a first modification shown in FIG. 7, in which first and second circulation ports are provided in a partition wall between a first conveyance section and a second conveyance section to circulate the developer; It is sectional explanatory drawing which showed the state.

FIG. 9 is a second modification of the developing device according to the first embodiment, in which a first circulation port that feeds a developer from a lower first transport unit to an upper second transport unit is provided. FIG.

FIG. 10 illustrates a developing device according to a second modification shown in FIG. 9, in which first and second circulation ports are provided in a partition wall between a first conveyance unit and a second conveyance unit to circulate the developer. It is sectional explanatory drawing which showed the state.

FIG. 11 is a third modification of the developing device according to the first embodiment, in which a first circulation port for feeding the developer from a first transport unit located below to a second transport unit located above is provided. FIG.

FIG. 12 is a diagram illustrating a developing device according to a third modification shown in FIG. 11, in which first and second circulation ports are provided in a partition wall between a first conveyance unit and a second conveyance unit to circulate the developer. It is sectional explanatory drawing which showed the state.

FIG. 13 is a schematic cross-sectional view of a developing device according to a second embodiment of the present invention, in which a circulation port is not provided between a first conveying unit and a second conveying unit.

FIG. 14 is a cross-sectional explanatory view showing a state in which first and second circulation ports are provided in a partition wall between a first conveyance unit and a second conveyance unit to circulate the developer in the developing device of the second embodiment. It is.

FIG. 15 is a schematic cross-sectional view of a portion of the developing device according to the second embodiment, in which a first circulation port for feeding a developer from a first transport unit located above to a second transport unit located below is provided. .

FIG. 16 is a schematic cross-sectional view of a portion of the developing device according to the second embodiment in which a second circulation port for feeding a developer from a lower second transport unit to an upper first transport unit is provided; .

FIG. 17 is a perspective view of the developing device according to the second embodiment, in which a second circulation port for feeding the developer from the second transport unit located below to the first transport unit located above is positioned from the axial center of the developer carrier It is a schematic sectional drawing of the 1st modification provided in the partition so that it might reach the edge part.

FIG. 18 is a diagram illustrating a second modification of the developing device according to the second embodiment, in which a second circulation port that feeds a developer from a lower second transport unit to an upper first transport unit is provided. FIG.

FIG. 19 illustrates a developing device according to a second modification shown in FIG. 18, in which first and second circulation ports are provided in a partition wall between a first conveyance unit and a second conveyance unit to circulate the developer. It is sectional explanatory drawing which showed the state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 11 Developer carrier 12 Magnet member 13a 1st conveyance part 13b 2nd conveyance part 14 Partition wall 15a, 15b Sending member 16a, 16b Circulation port 18 Magnet 19 Scraper 20 Developer sending member 21 Magnet roller

Claims (3)

[Claims] An image forming apparatus comprising: a developing device that transports a developer to a development area facing an image carrier by a developer carrier and performs development, wherein the developer is supplied to the developer carrier; Transporting the developer from the central portion in the axial direction to both ends or both ends in the axial direction to the central portion of the developer carrying member while collecting all of the developer from the developer carrying member; and the first transporting portion and the partition wall. A second transporting unit that transports the developer separated from the first transporting unit to the central portion from both ends in the axial direction or the central portion in the axial direction from both ends in the opposite direction to the first transporting unit faces the developer carrying unit. And a circulation port for circulating the developer between the first transport unit and the second transport unit. 2. The developing device according to claim 1, wherein
The first transporting section is provided below the second transporting section via a partition, and the developer is passed through circulation ports at both axial ends or an axial center of the developer carrier in the first transporting section. A developing device provided with a developer feeding means for feeding the developer to an upper second transport section. 3. The developing device according to claim 1, wherein
The first transport section is provided above the second transport section via a partition, and the developer is passed through circulation ports at the axial center or at both axial ends of the developer carrier in the second transport section. A developing device comprising a developer feeding means for feeding the developer to an upper first transport unit.