JP2002132046A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent developer such as a toner and a carrier, etc., from leaking and dropping through a gap between a developer carrying member and the inside wall of a carrying path, to prevent the developer from firmly sticking to the rubbed inside wall in the case of carrying the developer by the carrying member, and moreover to prevent the developer which changed into a liquid from flowing into a developing unit at replenishing of the replenishment developer to a developer replenishment unit, in an image forming device. SOLUTION: As for the image forming device provided with the carrying path 9 for carrying the developer, and the carrying member 10 for carrying the developer inside the carrying path 9, the device is provided with a magnetic field generating means 1 inside or outside of the carrying path 9, and a magnetic brush like chain M formed of magnetic powder is generated between the carrying member 10 and the magnetic field generating means 1 inside the carrying path 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for transporting a developer using a transport member in a transport path, and more particularly, to a developing device for developing an image using the developer, and a developer to the developing device. The present invention relates to an image forming apparatus such as a copying machine or a printer, which has a developer replenishing unit for transporting the toner.

[0002]

2. Description of the Related Art In an image forming apparatus utilizing an electrophotographic method, a developing device (toner) attracts a developer (toner) to an electrostatic latent image formed on the surface of an image carrier such as a photoreceptor to develop the image. Exists. At this time, since the toner in the developing device is constantly consumed by an amount adsorbed on the photoreceptor, when the toner in the developing device falls below a certain amount or a certain concentration,
It is necessary to supply toner to the developing device.

In an image forming apparatus for forming a chromatic image, a two-component developing system in which a toner and a carrier are mixed and used as a developer, and the consumed toner is supplied as a replenishing developer is widely used.

[0004] The two-component developing method has advantages such as stability of image quality and durability of the apparatus as compared with other developing methods currently proposed. In particular, carrier deterioration is inevitable. Although the technology for extending the life of the developer is gradually progressing, it is still insufficient at present. Therefore, it is necessary to perform an operation of replacing the developer with the long-term use of the image forming apparatus.

Some solutions to this problem have been proposed. For example, Japanese Patent Publication 2-21
No. 591 describes that when the deteriorated developer (carrier) is gradually replaced with a new one, the apparent progress of deterioration of the carrier is stopped, and the characteristics of the developer as a whole are stabilized. An image forming apparatus using this principle is:
A mechanism for gradually discharging the deteriorated developer from the developing device and gradually replenishing the toner and / or carrier as a replenishing developer is provided, eliminating the need to replace the developer by a service person or the like. , And maintainability is improved.

Conventionally, in an image forming apparatus using such a two-component developer, as a method of replenishing a replenishing developer to a developing device, one of a method for replenishing a replenishing developer with a developer container and a developing device is described. There is a method of carrying and replenishing by gravity between them. The method of performing the transfer by gravity has an advantage that the structure is simplified and the cost is relatively small because the transfer member is not used. However, since the developer is replenished by gravity, the container needs to be provided above the developer, which may be a great obstacle in the layout of the entire image forming apparatus.

Therefore, as another method, for example, a coil spring or the like is provided in a transport path provided between the container and the developing device.
It is well known that a conveying member such as a screw having a spiral blade formed on a shaft is provided, and the conveying member is used to replenish the replenishment developer in the storage container to the developing device as needed. .

This method is an object of the present invention, in which the replenishment developer in the container can be transported to a place distant from the container. In other words, it is possible to arrange the devices in the image forming apparatus, for example, in the side of the developing device, below the developing device, or the like, thereby contributing to downsizing of the image forming device. Due to the advantages described above, the method of transporting the replenishment developer such as toner and / or carrier using the transport member has been widely applied in spite of the disadvantage that the configuration is complicated.

A method of transporting and supplying a replenishing developer to the developing device through a transport path provided with a transport member in the developing method using the two-component developing method will be described in detail with reference to FIG.

FIG. 10 shows a developing device 100 containing a two-component developer containing a toner and a carrier in a developing container 2 and a developer replenishing unit 6 as a developer replenishing means without a photosensitive drum as an image carrier. FIG. 10 is a cross-sectional view of the conventional example viewed from the side, and the right side in FIG. 10 is the front direction of the image forming apparatus main body. The developer replenishing unit 6 is disposed on the back side of the developing container 2 of the developing device 100 when viewed from the front of the image forming apparatus main body, and is connected at the back end of the developing container 2 on the side of the housing portion 2a. There is a developer supply port 11 that passes through.

The replenishment developer is replenished to the developer replenishment unit 6, and the replenishment developer is conveyed from the replenishment developer into the developing container 2 constituting the developing device 100. In this example, the developing device 1
The developer supply unit 6 is disposed above the developer supply unit 00.

The developer replenishing unit 6 includes a developer accommodating chamber 7 for accommodating a replenished developer, and has a built-in stirring member 8 for agitating the replenished developer supplied therein. The stirring member 8 is a member formed by spirally rotating a resin film or the like with a rigid shaft, and is rotated appropriately to stir the replenishing developer in the developer accommodating chamber 7 and replenish the replenishing developer. To assist in the transport of

The replenishment developer corresponding to the amount consumed by the developing device 100 during image formation is transferred from the developer accommodating chamber 7 to the cylindrical member provided below the developer accommodating chamber 7 by the rotational force and the gravity of the stirring member 8. Is transported to the developer transport path 9. In the developer conveying path 9, a developer conveying screw 10 as a developer conveying member including a shaft body 10a and a screw member 10b having a spiral blade is provided. The replenishment developer is transported in the transport path 9 in the direction toward the developing container 2 constituting the developing device 100 (in the direction of the arrow in the drawing), and the transport path 9 and the developing container 2
Is supplied to the inside of the developing container 2 from the developer supply port 11 at the contact point. In this way, the developing device 10 is
At 0, the replenishment developer such as toner and carrier is replenished as the amount consumed in the developing device 100.

In this example, the developer supply port 11 is connected to the developing device 1
When viewed from the front of the image forming apparatus main body No. 00, the accommodation portion 2
a, the replenishment developer enters the developer container 2 from the developer replenishment port 11 by gravity, and is rotated by the first developer circulation screw 3a. The developer is caught in the circulation of the developer, mixed with the two-component developer in the developing container 2 and circulated in the developing container 2.

When the replenishment developer is taken in the flow circulating in the developer container 2, the conveying path 9 is located above the developer container 2 in this case, and thus is a communication port. There is almost no backflow toward the developer supply port 11.

The replenishing amount of the replenishing developer is roughly determined by the number of revolutions of the developer conveying screw 10,
This rotation speed is determined by a developer supply amount control unit (not shown). There are various methods of controlling the amount of developer replenishment, such as a method of optically or magnetically detecting the toner concentration of a two-component developer, and a method of developing a reference latent image on a photosensitive drum and detecting the toner image concentration. Since any method is known, any one of the methods can be appropriately selected.

When the toner consumption due to the image formation and the replenishment of the replenishment developer by the toner replenishment amount control means are repeated, when the replenishment developer is a two-component developer of toner and carrier, the replenishment developer is contained in the developing container 2. The number of carriers replenished together during toner replenishment increases. Further, since the carrier deteriorates due to long-term use, the two-component developer in the developing container 2 must be periodically replaced.

[0018]

However, the following problems also exist in the method of transporting a replenishment developer such as toner and / or carrier using the transport member 10 as described above.

In these methods, as described above, the developer supply unit 6 periodically sends the developer 10
It is necessary to replenish a certain amount of developer such as toner and / or carrier which becomes a replenishing developer for the amount transported to zero.

Hereinafter, only the case where toner is replenished as a replenishing developer will be described. However, a similar problem may occur when replenishing a replenishing developer in which toner and carrier are mixed when the ratio of carrier to toner is small.

Conventionally, when the amount of toner in the developing unit 100 becomes less than a predetermined amount, the supply unit 6
Toner is supplied as a replenishing developer to the replenishing unit 6, but when the amount of toner stored in the replenishing unit 6 is reduced, the toner must be replenished to the replenishing unit 6 from outside. The replenishment means can be roughly divided into two forms.

One of them has a configuration in which the developer accommodating container 7 itself for accommodating the toner is replaced when the toner is replenished. The other configuration is such that the developer accommodating container 7 is replaced from the outside by using another container (toner bottle).

When replacing the developer container 7 itself,
When the developer container 7 is replaced, the powder toner in the new container is sufficiently stirred to be in a liquefied state including air, so that the toner is transferred to the transport path 9 between the developer container 7 and the developing device 100. Then, the liquefied toner becomes movable.

When the toner is replenished using the toner bottle, the toner is sufficiently stirred in the toner bottle when the toner is completely new in the developer container 7 and when the toner is in the toner end state where the toner is almost completely removed. Is supplied to the developer container 7 of the replenishment unit 6, so that the liquefied toner can be moved to the transport path 9 between the developer container 7 and the developing device 100. become.

In these two methods, when the liquefied toner containing fresh air flows out into the conveying path 9,
When the developer accommodating container 7 is arranged above or beside the developing device 100 (FIG. 10), the liquefied toner in the developer accommodating container 7 passes through the developer conveying path 9 in a liquefied state. A large amount flows out to the developing device 100 side. Developing device 10
If a large amount of toner flows into the image forming apparatus, there is a problem that toner scattering into the inside of the image forming apparatus is increased and a front surface background stain is generated on an image.

The above-mentioned problem is caused by, for example, providing a toner end sensor (not shown) in the toner container.
At the stage when the sensor detects the toner end state, a certain amount of toner still exists at the entrance of the toner conveying path. Acts as a barrier to prevent the passage of the liquefied toner. In this case, the problem that a large amount of the liquefied toner flows into the developing device 100 occurs only when the product is new.

However, there is a case where the toner end sensor is not provided for cost reduction, so that the user cannot know the toner end state, and the developer container 7 is used up to a state where there is almost no toner. In this case, there is a problem that the liquefied toner flows out to the developing device 100 not only when the toner is new, but also in the toner end state.

On the other hand, in the method of transporting the replenishment developer using the transport member, the replenishment developer in the storage container can be transported to a place away from the storage container, and the layout can be freely set in the image forming apparatus. This method is widely used because it increases the degree of reduction and contributes to downsizing of the image forming apparatus. However, there is a disadvantage that the configuration is complicated.

In an image forming apparatus having such a complicated structure, the developer supply unit 6 is often arranged below the developing device 100.

When the developer replenishment unit 6 containing the replenishment developer is disposed below the developing device 100, the replenishment developer is constituted by a screw 10, a coil spring or the like, as shown in FIG. It is necessary to ascend and transport using a transport member.

At this time, the conveying screw 1 as a conveying member
0 and the outer peripheral portion of the coil spring and the conveying path 9 facing this.
If the distance between the inner walls of the transfer roller 9 is large, the replenishment developer in the form of fine powder may leak from the gap between the transport screw 10 or the coil spring and the inner wall of the transport path 9 due to the effect of gravity. The transportability of certain toner and / or carrier is reduced.

When the gap between the inner walls of the conveying path 9 is narrowed to prevent the inner wall of the conveying path 9 from leaking from the gap, the replenishment developer is rubbed in the narrow gap, and the conveying screw 10 or the inner wall of the conveying path 9 is rubbed by frictional heat. The toner sticks. As a result, not only does the carrying capacity decrease, but also the toner that has solidified into a fine coagulated body is peeled off, and when the toner is carried to the developing device 100, the image is adversely affected, resulting in image white spots and the like. Problems arise.

In order to effectively use the limited space in the recent trend of miniaturization of copiers and printers, the transport path 9 may be long. In this case, since the transport screw 10 is also long, there is a possibility that a part where the gap between the transport path 9 and the transport screw 10 of the transport member is particularly narrow may be formed by bending the transport screw 10. Remarkably appears.

Further, as shown in FIG. 10, there is a similar problem when the container 7 for replenishment developer is disposed above or on the side of the developing device 100, and there is a similar problem. If the gap between the inner walls is small, the toner is fixed by frictional heat. However, if the gap between the transport member 10 and the inner wall of the transport path 9 is increased, the transportability may be affected.

Accordingly, an object of the present invention is to solve the above problems and to prevent the developer such as toner and carrier from leaking from the gap between the transport member and the inner wall of the transport path when the developer is transported by the transport member. An image forming apparatus capable of preventing sticking to a rubbing inner wall or the like, and further preventing a liquefied developer from flowing into a developing device at the time of replenishment of a replenishment developer for replenishing a replenishment developer to a developer replenishment unit. It is to provide.

[0036]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A transport path for transporting the developer, and a transport member for transporting the developer inside the transport path, in an image forming apparatus having a magnetic field generating means inside or outside the transport path, An image forming apparatus is provided, wherein a magnetic brush-like chain made of magnetic powder is formed between the transport member in the transport path and the magnetic field generating means.

According to another aspect of the present invention, an image carrier on which an electrostatic latent image is formed, and a toner image is formed by developing the electrostatic latent image on the image carrier using a developer. A developing device, and a developer replenishing means for replenishing the developing device with a replenishing developer which is a developer for compensating for the amount consumed in the developing device, and further comprising the developer replenishing means, A developer accommodating chamber for accommodating a replenished developer, a transport path for transporting the replenished developer from the developer accommodating chamber to the developing device, and a transport for transporting the replenished developer inside the transport path An image forming apparatus having a magnetic field generating means inside or outside the conveyance path, and forming a magnetic brush-like chain of magnetic powder between the conveyance member and the magnetic field generation means in the conveyance path. I do.

According to one embodiment of the present invention, the developer in the developing device is a two-component developer containing a toner and a magnetic carrier. Form a magnetic brush-like chain. At this time, the replenishment developer may be toner, or
The replenishment developer may be a two-component developer containing a toner and a magnetic carrier.

According to another embodiment of the present invention, the developer in the developing device is a one-component magnetic toner, and the magnetic toner is used as the magnetic powder, and the magnetic brush-like chain is provided in the transport path. Form. At this time, the replenishment developer can be a magnetic toner.

According to another embodiment of the present invention, the front developer in the developing device is a one-component non-magnetic toner, and the magnetic powder is any one of iron powder, ferrite powder, and magnetite powder. The magnetic brush-like chain can be formed in the transport path by using a body or a powder having a saturation magnetization of 190 emu / cm ³ (CTS unit system) or more under a magnetic flux density of 1000 G.

According to another embodiment of the present invention, the magnetic field generating means is a ring having an S pole and an N pole in the thickness direction, and the S pole and the N pole are arranged along the traveling direction of the transport path. Provision is made for poles to be present.

According to another embodiment of the present invention, a magnetic member is provided on a part of the transfer member, or the transfer member is formed of a magnetic material, and the transfer member is a coil blade. Alternatively, it may be a screw in which a blade of a magnetic material is formed on a shaft.

According to another embodiment of the present invention, the magnetic field generating means includes an S pole and an N pole in a part of the transport member in the traveling direction.
Either the pole is present or the magnetic field generating means is formed as the transport member having an S pole and an N pole in the traveling direction.

In the present invention, the distance between the transport member and the developer transport path is 1 mm or more and 20 mm or less, preferably 1 mm or less.
mm or more and 10 mm or less, and the magnetic force of the magnetic field generating means is 100 mT or more and 2500 mT or less, preferably 100 mT or less.
It is 0 mT or more and 2500 mT or less.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 shows an embodiment of a developing device provided with a developing device 100 used in an image forming apparatus according to the present invention and a developer replenishing unit 6 as a developer replenishing means. 2 shows a full-color image forming apparatus A provided with each of the stations SY, SM, SC, and SK having the developing device 100 shown in FIG. 1 and the photosensitive drum 4 as an image carrier.

Each of the stations SY, SM, SC, and SK has almost the same configuration. In a full-color image, the stations are respectively yellow (Y), magenta (M), cyan (C), and cyan (C).
A black (K) image is formed. In the following description, for example, if there is a developing device 100, each station S
The developing device 100Y, the developing device 100M, the developing device 100C, and the developing device 100K in Y, SM, SC, and SK are commonly used.

First, the operation of the entire image forming apparatus A will be described. In FIG. 2, an electrostatic latent image is formed on the photosensitive drum 4 by exposing the surface of the photosensitive drum 4 charged by the charger 21 with a laser 22. The latent image is developed by the developing device 100 to form a toner image on the photosensitive drum 4. After this toner image is transferred to the recording paper 27 conveyed by the transfer belt 24 by the transfer bias by the transfer charger 23, the recording paper 2
7 is peeled from the transfer belt 24 and is pressed / heated by the fixing device 25 to obtain a permanent image. Further, the residual toner remaining on the photosensitive drum 4 after the transfer is removed by the cleaner 26 to prepare for the next image formation.

In such an image forming apparatus A, FIG.
As can be understood from the above, the developer replenishing unit 6 which is a normal developer replenishing means is located above the developing device 100. The developer used in the image forming apparatus A is a two-component developer containing a carrier and a toner.

The operation of the developing device 100 using the two-component developing method will be described with reference to FIG.

The developing container 2 of the developing device 100 contains a two-component developer containing a non-magnetic toner and a magnetic carrier, and the mixing ratio thereof is about 1: 9 by weight.
This ratio should be appropriately adjusted depending on the charge amount of the toner, the carrier particle size, the configuration of the image forming apparatus, and the like, and does not necessarily have to follow this numerical value.

The developing device 100 is composed of a developing container 2 having an opening in a developing area facing the photosensitive drum 4 as an image carrier. A certain developing sleeve 5 is rotatably arranged. The developing sleeve 5 enclosing a fixed magnet 5 'which is a magnetic field generating means is made of a non-magnetic material. During the developing operation, the two-component developer in the developing container 2 facing the photosensitive drum 4 is held in a layered manner. The two-component developer is carried and conveyed to the developing area, and is supplied to the developing area facing the photosensitive drum 4,
The electrostatic latent image formed on the photosensitive drum 4 is developed. The developer after developing the electrostatic latent image is transported according to the rotation of the developing sleeve 5 and is collected in the developing container 2.

The inside of the developing container 2 is divided into a housing portion 2a (closer to the developing sleeve 5) parallel to the photosensitive drum 4 and a housing portion 2b (farther from the developing sleeve 5). Reference numeral 3a is provided in the storage section 2a, and a second developing circulation screw 3b is provided in the storage section 2b in parallel with the photosensitive drum 4. The storage portions 2a and 2b are open at the front and the rear, and are connected so that the developer T can be circulated inside the storage portions 2a and 2b.

The developer T in the developing container 2 is circulated in the developing container 2 by the developer circulation screws 3a and 3b, and is mixed and stirred. In this embodiment, the direction of the development circulation is, as viewed from the front of the image apparatus main body, a direction from the back side of FIG. 1 to the front side on the first developer screw 3a side, and FIG. The direction is from the near side to the far side.

FIG. 3 is a cross-sectional view of this embodiment when the developing device 100 and the developer replenishing unit 6 of FIG. 1 are viewed from the side where the photosensitive drum 4 is not disposed.

In this embodiment, the image forming apparatus A uses a two-component developer system, and the developer supply unit 6 is connected to the developing device 100 similarly to the conventional example described with reference to FIG.
Is located above. The operation mode of supplying the replenishing developer in the developer accommodating chamber 7 to the developing container of the developing device 100 is the same as that of the conventional example described with reference to FIG. The replenishment of the toner as the replenishing developer, which is a characteristic part of the present embodiment, to the developing container 2 will be described in detail with reference to FIG. The same applies to the case where the replenishment developer in which the toner and the carrier are mixed is supplied.

When the toner is completely new in the developer accommodating chamber 7 or when the toner is almost out of toner, the toner accommodated in the toner bottle (not shown) is supplied from the outside to the developer accommodating chamber. Work to refill 7 At this time, when the toner in the toner bottle is agitated by applying vibration to the toner bottle or shaking the toner bottle, air is inserted between the powder toners to liquefy the toner, and the toner is easily replenished. Become.

However, when the liquefied powder toner is replenished into the developer accommodating chamber 7 of the replenishing unit 6, the liquefied toner is transported to the transport path 9 between the replenished developer accommodating chamber 7 and the developing device 100. Passes through the transport path 9 in which a transport screw 10 as a transport member is installed in a liquefied state.
A large amount of toner flows into the developing device 100 side, and the toner scatters inside the apparatus, and a front surface background stain on an image occurs. This always poses a problem when the developer supply unit 6 is arranged above or beside the developing device 100 as in this embodiment.

Therefore, in this embodiment, as shown in FIG. 3, a ring-shaped magnet 1 serving as a magnetic field generating means is disposed on the inner wall of a cylindrical transport path 9 for transporting the toner in order to avoid the above-mentioned problem. Has been established. FIG. 4 is an enlarged view of a state in which the magnet 1 is provided in the transport path 9. In this embodiment, as shown in FIG. 4, the outer peripheral side surface of the ring of the magnet 1 is disposed along the inner wall of the transport path 9 so that a transport screw 10 as a transport member is passed through the ring hole. The ring-shaped magnet 1 is magnetized to S, N or N, S in its thickness direction (the same direction as the axial direction of the screw shaft 10a).
A magnetic field m as shown in FIG.

Here, if a magnetic carrier is attached as a magnetic powder to the ring-shaped magnet 1 in advance, a magnetic brush-like chain (carrier chain) M in which the carriers are connected and raised by the magnetic field m is formed. Although only one typical magnetic brush chain is shown between the magnets in the figure, there are many actual magnetic brush chains not only between the magnets but also from the magnet to the position of the conveying screw. Thus, the space between the inner wall of the toner conveying path 9 and the conveying screw 10 is sealed by the curtain of the carrier chain M generated by the magnet 1. If the magnetic carrier is the same as the magnetic carrier of the two-component developer stored in the developing device, the magnet 1
Even if the carrier is peeled off, foreign matter is not mixed into the two-component developer of the developing device 100 and does not affect the image.
Since this sealing mechanism is a soft sealing mechanism using the carrier chain M, it seals the toner to some extent, but by appropriately adjusting the surface magnetic flux density of the magnet 1,
There is no possibility that the toner is not completely conveyed. However, even if the length of the carrier chain M is short, a length that seals the gap between the transport screw 10 and the transport path 9 or the magnet 1 is good. This is because if it is shorter, the seal will be incomplete. That is, the distance between the inner wall of the conveyance path 9 and the conveyance member 10 is 1 mm or more and 20 mm or less,
It is preferably 1 mm or more and 10 mm or less. At this time, the magnetic force acting between the inner wall of the conveyance path of the magnet 1 and the conveyance member is 100 mT or more and 2500 mT or less, preferably 10 mT or less.
It is preferable that the value is not less than 00 mT and not more than 2500 mT.

By using such a sealing mechanism, it is possible to softly seal the liquefied toner. Even in a configuration in which a toner end sensor or the like is not used for cost reduction, the liquefied toner can be A large amount can be prevented from flowing into the 100. Further, since this sealing mechanism is a soft sealing mechanism using the carrier chain M, the toner does not melt and adhere to the transport screw 10 or the inner wall of the transport path 9 due to the rubbing between the developers.

Further, the carrier chain M restrains the toner to some extent, so that the toner is transferred from a small gap in the conveyance path 9 such as a gap between the conveyance path 9 and the developing device 100 or a gap generated when the toner is assembled. Spattering out of 100 can also be reduced. Also, in the event that magnetic foreign matter is mixed in the toner, the carrier chain M restrains the magnetic foreign matter, and the magnetic foreign matter can be prevented from entering the developing device 100 and affecting the image.

The ring-shaped magnet 1 does not necessarily need to be mounted on the inner wall of the toner transport path 9, but can be mounted on the outer wall of the toner transport path 9 as shown in FIG. 5 by appropriately adjusting the surface magnetic flux density of the magnet 1. You may.

By arranging a plurality of magnets 1 as shown in FIG. 3, the liquefied toner can be more completely sealed. When a plurality of magnets 1 are provided, if the distance between the magnets 1 is small, a strong magnetic field is generated between the plurality of magnets 1, and a magnetic field is generated in a direction inward of the transport path 9, that is, in a direction to seal between the transport path 9 and the transport screw 10. m does not spread, and a carrier chain is formed in a direction along the inner wall of the transport path 9, and there is a possibility that sealing is not performed well.

It is considered that a carrier chain perpendicular to a carrier chain parallel to the inner wall of the conveyance path 9 has higher sealing performance. However, when the conveyance screw 10 is not a magnetic material, a magnetic field is mainly generated between the adjacent magnets 1. Is formed, the carrier chain M is easily formed in the direction along the inner wall of the transport path 9 as a whole, and the carrier chain M is slightly laid along the transport path 9.
This does not mean that all the carrier chains M are formed in the direction along the inner wall of the transport path 9 but means that there are many carrier chains M in the direction along the inner wall as a whole. . However, it is not preferable that the magnetic field in the direction parallel to the inner wall of the transport path 9 is too strong and the number of the carrier chains M in the vertical direction decreases.

In this case, a shaft of a magnetic material is used for the shaft 10a of the conveying screw, or the shaft 10a of the conveying screw is used.
It is preferable to embed a magnetic material in “a” and attract the magnetic field “m” toward the inside of the transport path 9.

For example, when the shaft 10a of the transport screw is a magnetic material, the magnetic field m is applied between the adjacent magnets 1 and in the direction toward the shaft 10a of the screw (that is, the direction perpendicular to the inner wall of the transport path 9). Are strongly formed. Therefore, by forming more carrier chains M extending in the direction perpendicular to the inner wall of the transport path 9, the space between the screw 10 and the inner wall is more effectively sealed.

When the transport path is very long, it is sufficient to seal the section in a part of the transport path, and it is preferable to attach at least one magnet 1 near the developer supply port 11.

As described above, the image forming apparatus A provided with the transport member 10 for transporting the toner from the space 7 containing the toner to the developing device 100 into the transport path 9 for transporting the toner as the replenishing developer. , The magnetic field generating means 1 is provided inside or outside the transport path 9, and a chain (magnetic brush) M made of magnetic powder is formed in the transport path 9,
Even in a configuration that does not use a toner end sensor or the like for cost reduction. When the toner is replenished or the like, it is possible to prevent the liquefied toner from flowing into the developing device 100 and prevent the toner from sticking to the inner wall of the rubbing path, thereby achieving the object of the present invention.

The developer supply unit 6 is connected to the developing device 10
0, the developing device 1
By attaching the magnetic field generating means 1 to the developer transport path 9 between the toner supply chamber 00 and the developer accommodating chamber 7, the liquefied toner replenished as the replenishment developer is transported by the ascending transport unit 9 to the transport member 10 and the transport path 9. It is possible to prevent the paper from being conveyed due to leakage from the gap in the inner wall.

Example 2 Using the principle described in Japanese Patent Publication No. Hei 2-21591 as described in the prior art, a two-component developing method is used to collect the deteriorated developer little by little and simultaneously to add a new developer. An image forming apparatus that has a developing unit with a replenishing mechanism and saves the trouble of exchanging the developer such as a service person while maintaining the performance of the developer to some extent, and transports the replenished developer from the developer replenishing unit to the developing device. Provided with a conveying member such as a coil spring or a screw having a helical blade formed on a shaft body in the conveying path to be provided, and provided with a mechanism for replenishing the replenishing developer to the developing device as needed. In the forming apparatus, the replenishing unit 6 can be arranged below the developing device 100 instead of above.

On the other hand, in recent years, as the market for full-color copying machines and printers has expanded and various functions have been required, for example, in order to provide high productivity, a tandem system in which a plurality of photosensitive drums are arranged and multiple transfer is performed. Many image forming apparatuses have been commercialized and are expected to become one of the mainstream markets in the future.

JP-A-9-218575, JP-A-10-218575
These techniques proposed in Japanese Patent No. 63074 or the like have a configuration using a rotary developing device or provide a complicated developer collecting mechanism.

However, in the tandem system, the developing units of each color are fixedly arranged on each photosensitive drum.
The simple structure proposed in 218575 could not be used. For this reason, in order to adopt a system in which the developer is gradually replaced in the tandem system, Japanese Patent Laid-Open No.
A complicated configuration as shown in Japanese Patent Application No. 0-63074 had to be adopted. The same applies to an image forming apparatus that forms a single-color image.

That is, in the prior art, in a single-color image forming apparatus, a tandem system that produces high productivity, and a full-color image forming apparatus of various configurations that do not employ a rotary developing device to take advantage of various features. On the other hand, if the developer is automatically replaced gradually to improve maintainability, on the contrary, the configuration becomes complicated, leading to an increase in the cost of the main body.

For example, as shown in FIG. 7, the developer replenishment unit 6 of the first embodiment is connected to a developer accommodating chamber 7, a developer transport path 9 provided with a developer transport screw 10, and a developing device. A developer collecting chamber 62 for storing the developer collected from the inside of the developing device 100 is added, and the developer is transported upward as an integrated developer cartridge 60 so that the developing device 10
By adopting a configuration in which the image forming apparatus is replenished with 0, the degree of freedom in layout is increased, and it is possible to realize and provide an image forming apparatus with high maintainability with a simple configuration.

In the present embodiment, as an image forming apparatus provided with such a developer replenishing cartridge 60, a full-color replenishing cartridge 60 is provided below the developing unit 100 using an intermediate transfer member 24 'shown in FIG. The image forming apparatus B will be described. In the following description, for example, if there is a developing device 100, each station SY, SM, S
The developing units 100Y, 100M, 100C, and 100K included in C and SK are commonly referred to.

In the image forming apparatus B of this embodiment, SY stations, SM stations, SC stations, and SK stations for forming toner images of respective colors are arranged in a horizontal direction. The yellow, magenta, cyan, and black toner images formed at each station are transferred to the intermediate belt 24 ′ by the transfer charger 23 at each station.
The toner image is sequentially transferred onto the upper portion, and then transferred to the secondary transfer charger 23 ′.
Thus, the image transferred onto the transfer paper 27 at one time is transferred, and then the image transferred onto the transfer paper 27 is fixed by the fixing device 25. Developing units 100Y, 100M, 100C for each color
The configuration of 100K is basically similar to that of the developing device 100 of the image forming apparatus A described in the first embodiment.

Next, the recovery of the developer in the image forming apparatus B of this embodiment will be described in detail.

Inside the intermediate transfer belt 24 ', the developer supply cartridge 6 shown in FIG.
0 is arranged, and the space of the image forming apparatus can be used efficiently. At this time, the supply unit 60 is
It will be located below the developing device 100 arranged outside of 4 '.

The developer supply cartridge 60 shown in FIG. 7 has stations SY, SM, SC, S
A is installed below each developing unit 100 corresponding to A. The developer supply cartridge 60 includes a supply developer storage section 61 and a collected developer storage section 62, and is easily detachable from the main body of the image forming apparatus B.

The replenishment developer accommodating section 61 and the collected developer accommodating section 62 are formed in a coaxial cylindrical shape.
Reference numeral 1 denotes a front side of the main body of the image forming apparatus B, and a collected developer accommodating portion 62 is located at a rear side. A developer conveying path 9 is provided so as to pass through the collected developer accommodating section 62, and a developer conveying screw 10 is rotatably installed in the developer conveying path 9. That is, the developer transport path 9 is built in the developer cartridge 60. Alternatively, a stirring member 8 for stirring the replenished developer to be replenished is built in the developer container 61,
By appropriately rotating, the replenishment of the developer is assisted, and the replenishment developer in the replenishment developer accommodating portion 61 is gradually conveyed to the back side, that is, the developer conveyance path 9.

The developer cartridge 60 is connected to the image forming apparatus B
Then, by twisting the handle 63 on the near side to the right, the replenishment developer accommodating portion 61 and the collected developer accommodating portion 62 rotate, and the developer replenishing port 11 and the developer collecting port 14 are opened. When the developer cartridge 60 is detached from the image forming apparatus B, the opening 63 is closed by twisting the handle 63 to the left, and the powder contained therein does not leak to the outside.

The replenishment developer T ′ corresponding to the amount consumed by the image formation is transported from the replenishment developer accommodating section 61 side to the replenishment developer transport path 9 by the agitating agent 8, and is supplied to the replenishment developer transport path 9. The toner is conveyed upward by a rotation of the conveying screw 10 and enters the developing container 2 from the developer supply port 11.

In the image forming apparatus B of the present embodiment, a method of recovering excess developer while supplying replenishing developer to the developing device 100 is adopted as a two-component developing method.
The replenishing developer T ′ such as new toner and / or carrier is gradually replenished into the developing container 2 of the developing device 100, and is replaced with the developer T in the developing container 2.

FIG. 8 is a cross-sectional view from above showing a state near the developer supply port 11 in the developing device 100 when the supply developer T 'is supplied. FIG. 9 is a diagram viewed from the near side. FIG. 8 shows each station SY, SM, SC, S of the image forming apparatus B using the intermediate transfer member 24 'shown in FIG.
K shows the developing device 100 provided in the image forming apparatus B and the photosensitive drum 4 serving as an image carrier when viewed from the front of the image forming apparatus B in accordance with the rotation direction of the intermediate transfer member 24 '.
1 is left-right reversed with respect to the image forming apparatus A, so that the position of the developing sleeve 5 is also left-right reversed with respect to FIG. .

In this example, the developer supply port 11 is connected to the developing device 1
8, the container 2b is located on the left side, and the developer supply port 11 is located on the left side in FIG.
Is shown at the upper end of the right housing portion 2a.

The replenishment developer T ′ that has entered the developer container 2 from the developer replenishment port 11 is pressed by the conveying screw 10 from below to supply the developer replenishment port 11 of the developer container 2.
The raised portion in the vicinity is the first developer circulation screw 3
By the rotation of a, the image forming apparatus main body B is conveyed to the near side (the lower side in FIG. 8). The flow (arrow B) of the replenished developer T ′ that has been replenished thereafter is similar to the example in which the replenishing unit is located above (FIG. 3), the developer T circulating in the container 2 near the developer circulation guide member 15. It merges with the flow (arrow A) and is mixed and stirred as the two-component developer T in the developing container 2.

As shown in FIG. 8 showing the developer T circulating in the developing container 2 with the back side of the image forming apparatus B facing upward, the developing container 2 has a storage portion left 2b to a storage portion right 2a and an upper portion. The developer T ′ circulates clockwise as viewed from above, and the developer T ′ enters the developing device 2 and makes a round, and is guided to the developer circulation guide port 15,
As soon as the sheet is conveyed in the vicinity of the supply port 11 of the container 2a, that is, from the container 2b in FIG.
The container 2a is transported downward in FIG. 8 by the developer circulation screw 3a. That is, in most cases, the developer circulating in the developing container 2 does not fall out of the developer supply port 11 into the supply cartridge 60. If such a problem is likely to occur due to the configuration, the height of the upper end of the developer supply port 11 may be higher than the inner bottom surface of the developer container 2, or the developer supply port 11 may be placed inside the developer container 2 so as to surround the developer supply port 11. It is only necessary to take measures such as providing a circumferential projection.

Thus, the developer supply cartridge 6
The replenishment developer is replenished from 0 to the developing device 100. The replenishment amount of the replenishment developer is roughly determined by the number of revolutions of the developer conveying screw 10, and the number of revolutions is determined by a developer replenishment amount control unit (not shown). Can be There are various methods for controlling the amount of developer replenishment, such as a method of optically or magnetically detecting the toner density of the two-component developer, a method of developing a reference latent image on the photosensitive drum 4 and detecting the density of the toner image. Since any method is known, any one of the methods can be appropriately selected.

When the toner consumption due to the image formation and the replenishment of the replenishment developer by the developer replenishment amount control means are repeated, the amount of the carrier replenished together with the replenishment developer in the developer container 2 at the time of toner replenishment increases. Since the toner concentration of the two-component developer is kept substantially constant by the developer supply amount control means, the amount of the developer in the developing container 2 increases. The excess two-component developer in the developing container 2 is supplied to the developer outlet 1 shown in FIG.
2 is dropped, passes through the developer collection port 14, and is collected in the collection developer accommodating portion 62.

The developer discharge port 12 and the developer recovery port 14 are located on the upstream side of the developer supply port 11 with respect to the direction of circulation of the developer in the developer container 2, and the replacement of the developer is performed gradually. .

Developer supply port 11 and developer recovery port 14
Both transfer the supply / recovery developer on the back side of the intermediate transfer belt 24 '.
It does not hinder the running of 4 '.

As described above, in the full-color image forming apparatus having the structure as in the present embodiment, the developer can be automatically changed gradually with a simple structure. That is, it is possible to realize and provide an image forming apparatus which is inexpensive and has high maintainability.

Here, the method of transporting the replenishment developer, which is the most characteristic part of the present embodiment, will be described in more detail.

An important feature of the image forming apparatus B is that the replenishment developer is transported in the ascending direction.

As described above, when powder such as toner, which is a replenishing developer, is transported upward, the transport path 9 is conventionally used.
In the present embodiment, the developer supply cartridge 60 shown in FIG. 7 is provided as a transport member inside the developer transport path 9. A transport screw 10 is provided. However, only by providing the transport screw 10, as described in the conventional example of FIG. 11, when the gap between the outer peripheral portion of the transport screw 10 and the inner wall of the transport path 9 is large, the transport screw 10 and the transport screw 10 are not affected by gravity. The toner contained in the replenishment developer leaks from the gap on the inner wall of the transport path 9, resulting in a decrease in the transportability of the replenishment developer and the transport screw 1.
In the case where the gap between the outer periphery of the transfer screw 9 and the inner wall of the transfer path 9 is small, the toner contained in the replenishment developer is fixed to the transfer screw 10 and the inner wall of the transfer path 9 by frictional heat, resulting in reduced transferability. Further, problems such as image deterioration such as white spots due to peeling of the aggregated toner may occur.

Therefore, in this embodiment, in order to avoid such a problem, the inner wall of the conveyance path 9 of the supply cartridge 60 is provided with
A ring-shaped magnet 1, which is the same magnetic field generating means as in the first embodiment, is provided. The magnet 1 here is also magnetized to S, N or N, S in the direction of travel of the transport screw shaft 10a in the thickness direction, as in the first embodiment. With such a configuration, the magnetic carrier, which is a magnetic powder in the replenishment developer, is attracted to the magnetic field of the magnet 1 to form a carrier chain M in which the magnetic carrier is restrained. As a result, the space between the inner wall of the developer conveyance path 9 and the conveyance screw 10 is sealed by the curtain of the carrier chain M.

Here, when the ratio of the carrier in the replenishment developer is small and the carrier chain M is not formed well, it is preferable to attach a magnetic carrier as a magnetic powder to the ring-shaped magnet 1 in advance. With this sealing mechanism, even if the gap between the transport screw 10 and the inner wall of the transport path 9 is somewhat large, it is possible to prevent the gap from leaking from the gap,
Allows good transport.

Further, since this sealing mechanism is a soft sealing mechanism using the carrier chain M, the toner is not melted and fixed by the rubbing between the developers.

As described above, the transport member 10 for transporting toner, for example, into the transport path 9 for transporting the replenishment developer from the space containing the replenishment developer such as toner and / or carrier to the developing device 100. Intermediate transfer body 2 as in the present embodiment, including a developer supply cartridge 60 provided with
In the full-color image forming apparatus B having a configuration using 4 ', the magnetic field generating means 1 is provided inside or outside the transport path 9, and the chain (in the transport path 9) made of a magnetic powder such as a magnetic carrier in a replenishment developer is used. By forming the magnetic brush (M), it is possible to prevent the toner from leaking from the gap between the transport member 10 and the inner wall of the transport path 9 and the sticking to the inner wall of the rubbing when the developer is gradually and automatically replaced. Can achieve the object of the present invention.

Also, in this embodiment, as described in the first embodiment, the same effects as those in the case where the developer supply unit 6 is provided above the developing device 100 can be obtained.

As described above, in the full-color image forming apparatus having the configuration as in this embodiment, the developer can be gradually and automatically replaced with a simple configuration. That is, an image forming apparatus having high maintainability can be realized and provided. Further, if a transport screw is provided in the supply path of the replenishment developer so that the transport can be carried up, the entire apparatus can be downsized by efficiently using the space of the image forming apparatus main body.

Further, in the intermediate transfer member system as in this embodiment, troubles such as paper jams are less likely to occur because the transfer mechanism of the transfer paper 27 is simplified, and it is easy to use various materials such as plain paper and HP film. There are features such as being able to respond to.

Further, by providing the transport screw 10 and the magnet 1 in the replenishment developer transport path 9 so as to be capable of ascending transport, the degree of freedom of layout is increased and the image forming apparatus B
By efficiently utilizing the space of the main body, the entire apparatus can be downsized. Therefore, it is possible to realize and provide an image forming apparatus with a simple configuration at low cost and with high maintainability.

When a two-component developer is used as the replenishing developer, the mixing ratio of the toner and the carrier of the replenishing developer is about 9: 1 by weight, but is not particularly limited to this value. That is, the amount of toner is overwhelmingly larger than the ratio of the two-component developer in the developing container 2, and considering the volume ratio, it can be considered that a small amount of carrier is mixed in the toner. That is, when supplementing the toner consumed by image formation, a small amount of carrier is gradually supplied. If the ratio of the carrier of the developer to be replenished is increased, the replacement amount of the carrier is increased by the same amount of toner replenishment, and the two-component developer in the developing device 100 approaches a fresh state. Increase.
For this reason, it is preferable to determine an appropriate mixing ratio separately for each device.

Embodiment 3 In Embodiments 1 and 2, in the image forming apparatus using the two-component developing system, the replenishment developing chamber 7 in the empty replenishing unit 6 and the replenishing developer chamber 61 in the replenishing cartridge 60 are replenished. When a new toner as a developer is supplied to the developing container 2 containing a two-component developer composed of a toner and a carrier, the magnet 1 is disposed in the developer transport path 9 and the inner wall of the developer transport path 9 and the transport screw 10 The mechanism that seals the space between them with a curtain of a magnetic carrier chain, which is a magnetic powder, was described.

This technique can be applied to a case where a magnetic toner is supplied to a developing device in an image forming apparatus using a magnetic one-component developing system. At this time, the magnetic toner, which is a magnetic powder, is attracted to the magnetic field of the magnet 1 to form a chain of the constrained magnetic toner. As a result, the space between the inner wall of the toner conveying path and the conveying screw is sealed by the curtain of the magnetic toner chain.

In an image forming apparatus using a non-magnetic one-component developing system, the present invention can be applied to a case where non-magnetic toner is supplied to a developing device. At this time, it is necessary to attach magnetic powder such as iron powder, ferrite powder, and magnetite powder to the magnet 1 in advance. A magnetic chain confined by being attracted to the magnetic field of the magnet 1 is formed to seal between the inner wall of the toner conveying path and the conveying screw. It is harder to peel off if it is strongly attracted to the magnet. For example, the saturation magnetization under 1000 G is 190 em.
It is preferable to use a powder of about u / cm ³ (CTS unit system) or more.

When the magnetic powder separates from the magnet, the developing device 1
If it is mixed with 00, the image may be adversely affected. Therefore, by appropriately adjusting the surface magnetic flux density of the magnet 1,
It is preferable to provide a plurality of magnets 1 and take measures such as using the magnets 1 close to the developing device 100 for collecting the separated magnetic powder.

Although the magnet is used as the magnetic field generating means in the first to third embodiments, other magnetic field generating means such as an electromagnet may be used.

As still another configuration, the transport screw shaft 1
A similar effect can be obtained if the blade 0a or the blade 10b itself is formed of a magnet and magnetized to S, N or N, S in the traveling direction. In this case, there is no need to use the ring-shaped magnet 1 and the configuration is simplified. For example, when the blade portion 10b of the transport screw is made of a magnetic field generating means, a carrier or the like adheres to the blade portion 10b and a carrier chain is formed toward the inner wall of the transport path 9, so that the carrier between the screw and the inner wall is formed. Sealed with a chain.

[0113]

As described above, the image forming apparatus of the present invention has (A) the transport path for transporting the developer, and the transport member for transporting the developer inside the transport path. In the image forming apparatus, a magnetic field generating means is provided inside or outside the conveying path, and a magnetic brush-like chain made of magnetic powder is formed between the conveying member and the magnetic field generating means in the conveying path, or (B) an image carrier on which an electrostatic latent image is formed, a developing device for developing the electrostatic latent image on the image carrier using a developer to form a toner image, and a component consumed by the developing device. Developer replenishing means for replenishing the replenishing developer for supplementing the developer, wherein the developer replenishing means transports the replenished developer to the developing device from the developer accommodating chamber for accommodating the replenished developer and the developer accommodating chamber. And a transport member for transporting the replenishment developer inside the transport path In the image forming apparatus having,
Since the magnetic field generating means is provided inside or outside the transport path and a magnetic brush-like chain made of magnetic powder is formed between the transport member and the magnetic field generating means in the transport path, (1) toner and / or When a developer such as a carrier is transported by the transport member, leakage of the developer from the gap between the transport member and the inner wall of the transport path and prevention of sticking to the sliding inner wall and the like are improved, and the transportability of the developer is improved. (2) A large amount of liquefied replenishment developer can be prevented from flowing into the developing device side when replenishing the replenishment developer, and the image forming apparatus can be prevented. Scattering of the developer inside, background contamination on the image, furthermore, toner scattered outside the developing device from a fine gap in the developing device or the transport path, or magnetic foreign matter mixed in the replenishment developer by any chance Can be prevented from entering the developing device, and (3) developing Be placed developer supply means in any direction from the supply developer is capable conveyed to the developing device, handed freedom of layout of the developer supply means, can be provided an image forming apparatus with a simple structure. Such an effect can be achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a developing device 100 and an image carrier 4 in an image forming apparatus A according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a configuration of an image forming apparatus A according to the first exemplary embodiment of the present invention.

FIG. 3 is a side sectional view showing a configuration of a developer supply unit 6 and a developing device 100 according to the first embodiment of the present invention.

FIG. 4 is an enlarged perspective view of the magnet 1 in the transport path 9 according to the first embodiment of the present invention.

FIG. 5 is an enlarged view of a replenishment developer conveyance path 9 according to the first embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an image forming apparatus B according to a second embodiment of the present invention.

FIG. 7 is a perspective view of a supply cartridge 60 according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a developing device 100 illustrating supply and recovery of a developer according to a second embodiment.

FIG. 9 is a front view of the developing device 100 for explaining replenishment and recovery of the developer according to the second embodiment.

FIG. 10 is a side sectional view of a developer supply unit 6 and a developing unit 100 in a conventional image forming apparatus.

11 is a side cross-sectional view in which a developer supply unit 6 is provided below the developing device 100. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet (magnetic field generation means) 2 Developing container 3 Developer circulating screw 4 Photosensitive drum 5 Developing sleeve 6 Developer replenishing unit 7 Replenished developer accommodating chamber 8 Stirring member 9 Developer transport path 10 Transport screw 11 Developer replenishing port 12 Developing Developer discharge port 14 developer recovery port 24 ′ intermediate transfer member 60 supply cartridge 61 developer storage section 62 developer recovery section 100 developer T, T ′ developer

Continued on the front page (72) Inventor Keiko Igarashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masahiro Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Mochizuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Motohide Shiozawa 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term inside Canon Inc. Reference) 2H077 AA12 AA20 AB02 AC02 AC07 AC12 DB02 EA03 EA13 FA19

Claims (14)

[Claims] 1. An image forming apparatus comprising: a transport path for transporting a developer; and a transport member for transporting the developer inside the transport path, wherein a magnetic field is generated inside or outside the transport path. Means for forming a magnetic brush-like chain of magnetic powder between said conveying member and said magnetic field generating means in said conveying path. 2. An image carrier on which an electrostatic latent image is formed, a developing device for developing the electrostatic latent image on the image carrier using a developer to form a toner image, and the developing device Developer replenishing means for replenishing the developing device with a replenishing developer which is a developer for replenishing the amount consumed in the developer, wherein the developer replenishing means comprises a developer accommodating the replenished developer. An image forming apparatus comprising: a storage chamber; a transport path that transports the replenished developer from the developer storage chamber to the developing device; and a transport member that transports the replenished developer inside the transport path. The image forming method according to claim 1, further comprising: a magnetic field generating means inside or outside the conveyance path, and forming a magnetic brush-like chain of magnetic powder between the conveyance member and the magnetic field generation means in the conveyance path. apparatus. 3. The developer in the developing device is a two-component developer containing a toner and a magnetic carrier, and the magnetic brush is used as the magnetic powder to form the magnetic brush-like chain in the transport path. 3. The image forming apparatus according to claim 2, wherein: 4. The image forming apparatus according to claim 3, wherein said replenishment developer is a toner. 5. The image forming apparatus according to claim 3, wherein said replenishment developer is a two-component developer containing a toner and a magnetic carrier. 6. The method according to claim 1, wherein the developer in the developing device is a one-component magnetic toner, and the magnetic brush-like chain is formed in the transport path using the magnetic toner as the magnetic powder. Item 2. The image forming apparatus according to Item 2. 7. The image forming apparatus according to claim 6, wherein said replenishment developer is a magnetic toner. 8. The fore developer in the developing device is a one-component non-magnetic toner, and as the magnetic powder, any one of iron powder, ferrite powder, and magnetite powder is used,
3. The image forming apparatus according to claim 2, wherein said magnetic brush-like chain is formed in said transport path. 9. The fore developer in the developing device is a one-component non-magnetic toner.
The saturation magnetization under 0 G is 190 emu / cm ³ (CT
3. The magnetic brush-like chain is formed in the conveyance path using powder of S unit system or more.
Image forming apparatus. 10. The magnetic field generating means is a ring having an S pole and an N pole in a thickness direction, and is provided so that an S pole and an N pole exist along a traveling direction inside the transport path. The image forming apparatus according to claim 1, wherein: 11. The image forming apparatus according to claim 10, wherein a magnetic member is provided on a part of the conveying member, or the conveying member is formed of a magnetic member. 12. The image forming apparatus according to claim 11, wherein the conveying member is a coil blade or a screw in which a magnetic blade is formed on a shaft. 13. The magnetic field generating means is disposed on a part of the transport member so that an S pole and an N pole are present in a traveling direction, or the magnetic field generating means is arranged in an S pole in a traveling direction. The image forming apparatus according to any one of claims 1 to 9, wherein the image forming apparatus is formed as the transport member having an N pole and an N pole. 14. The distance between the transport member and the developer transport path is 1 mm or more and 20 mm or less, preferably 1 mm or more and 10 mm or less, and the magnetic force of the magnetic field generating means is 100 mm or less.
It is mT or more and 2500 mT or less, preferably 1000 mT or more and 2500 mT or less.
14. The image forming apparatus according to any one of the thirteenth aspect.