JPH08202152A - Developing device - Google Patents

Abstract

PURPOSE: To prevent the leakage of a developer from both end parts of a developer carrier by setting the part facing the developer carrier of a toner sealing member, so as to be in an inner part in the longitudinal direction of the developer carrier, as it goes to the upstream side in the rotational direction of the developer carrier. CONSTITUTION: The face facing a developing sleeve 3 of a magnetic body 6 is magnetized by the magnetic force of a magnet roller 4 arranged inside the developing sleeve 3, a magnetic circuit is formed between the magnet roller 4 and the magnetic body 6 and a magnetic field is concentrated between the magnetic body 6 and the developing sleeve 3, to form a magnetic brush with toner between the magnetic body 6 and the sleeve 3. Then, the magnetic brush therebetween is formed to go inward in the longitudinal direction of the sleeve 3 as well. Therefore, the toner moved to both ends of the sleeve 3 is brought back to the inner part in the longitudinal direction of the sleeve 3, to be guided by the magnetic brush.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing a latent image formed on an image bearing member with a dry developer, and more particularly to a one-component developer or magnetic carrier comprising a magnetic toner. And a developing device using a two-component developer having

[0002]

2. Description of the Related Art Currently, electrophotographic copying machines and laser beam printers are widely used as office equipment. In order to visualize the latent image formed on the image bearing member, fine particles of a developer, particularly a dry developer, are used in these electrophotographic image forming apparatuses. The developer is accommodated in the developer accommodating chamber of the developing device, conveyed by the stirring means in the developer accommodating chamber to the developing sleeve which is a rotatable developer carrier, and is carried by the developing sleeve.

A developer layer thickness regulating member is provided near the developing sleeve to regulate the layer thickness of the developer on the developing sleeve to a predetermined thickness. After that, the developer is conveyed by the rotation of the developing sleeve to a position facing the latent image forming portion on the image carrier, and the potential difference formed between the developing sleeve and the image carrier causes the developer to be formed on the image carrier. It flies to the electrostatic latent image forming section to visualize the latent image on the image carrier.

The developer layer thickness control method is mainly described below.
There are a method of providing the non-magnetic plate member with a constant distance from the developing sleeve, a method of providing the magnetic plate member with a constant distance from the developing sleeve, and the like.

Further, in order to prevent the developer from leaking out of the developing device, seal members are provided at both ends of the developing sleeve and the developer layer thickness regulating member. When the sealing property of this sealing member is insufficient, the following problems occur.

For example, if the developer leaks in the image forming apparatus, the output image may be contaminated with the developer, or if it adheres to the transfer roller, a transfer failure image may result. In addition, when the developing device is detached for maintenance, the developer may leak from the developing device and spill onto the floor, or clothes and hands of humans who have performed maintenance may be soiled.

Therefore, the developer must not leak from the developing device or the developer accommodating chamber, and various measures have been taken to prevent the developer from leaking. For example, there is a method in which a sponge-like elastic body is brought into contact with both ends of the developing sleeve to eliminate a gap through which the developer leaks to the outside. This method has the advantages that the structure is simple and the elastic body is inexpensive, and since there is no space for the developer to pass through at both ends of the developing sleeve, the developer leakage prevention effect is extremely high. High, developer type (1 component, 2
It is widely used regardless of the components and the presence or absence of magnetic substances.

However, this method has the following problems. When the elastic body rubs against the developing sleeve for a long time, the elastic body itself is torn, and the torn elastic body is clogged between the developing sleeve and the developer layer thickness regulating member, and streaks occur in the image. The developer on both end surfaces of the developing sleeve comes into contact with the elastic body as a seal member and rubs strongly against it, so that the developer is fused to the developing sleeve and the developer aggregates. And the developer layer thickness regulating member are clogged, and streaks occur in the image.
Since the elastic body is worn or torn by rotation and rubbing against the developing sleeve, the sealing property is significantly deteriorated when the developing sleeve passes a certain number of rotations. For this reason,
It is very difficult to recycle and use. The rotational torque of the developing sleeve may increase, the load on the drive motor may increase, and so-called pitch-like image unevenness may occur that does not provide image accuracy.

In order to solve these problems, in a developing device which uses a one-component magnetic developer or a two-component developer containing a magnetic carrier and has a magnet roller inside the developing sleeve, a predetermined interval is provided at both ends of the developing sleeve. However, by providing a magnetic material or magnet as the seal member, concentrating the magnetic field in the gap between the seal member and the developing sleeve, forming a magnetic circuit, and forming a dense magnetic brush with the developer, the leakage of the developer is prevented. A so-called magnetic seal method has been proposed.

In the magnetic seal method, since the seal member does not come into contact with the developing sleeve, it is possible in principle to avoid all the problems that occur when the elastic body is used. In addition, a magnetic body having a proper magnetic permeability or a magnet having a proper magnetic force density is used as a seal member, and the magnetic body or the magnet is arranged at an appropriate distance from the developing sleeve to maintain good sealing performance. You can Further, since the magnetic substance or the magnet is not in contact with the developing sleeve, it is not worn or damaged, so that its life is semi-permanent, which is very suitable for recycling.

[0011]

However, in the above-mentioned conventional example, the developer layer thickness is regulated in order to reduce the developer layer thickness in order to improve the image quality and to efficiently and uniformly apply the charge to the developer. As a method, if a method that strongly regulates the developer, for example, a method in which an elastic blade such as urethane rubber is brought into contact with the developing sleeve with a predetermined linear pressure,
In the developing device in which this and the above-mentioned magnetic seal system are combined, the following problems occur.

In the above developer layer thickness regulating method, since the elastic blade comes into contact with the developer at a predetermined linear pressure, the developing sleeve and the elastic blade are different from those in the case where the non-contact developer layer thickness regulating member is used. The force acting on the developer passing between the two is large. As a result, among the developers that enter the abutting portion of the developing sleeve and the elastic blade, the developer that cannot pass through the abutting portion of the developing sleeve and the elastic blade, especially the developers at the both ends of the developing sleeve, are That is, the force of leaking out of the developing device is strongly received.

Further, since the amount of the developer that enters the contact portion between the developing sleeve and the elastic blade is constant regardless of the regulating force of the developer layer thickness regulating member against the developer, the developer layer thickness regulating member. The greater the regulation force of the above, the greater the amount of developer that is moved outward in the longitudinal direction of the developing sleeve.

Therefore, by repeating the image formation, that is, by repeating the rotation of the developing sleeve, the developer gradually accumulates in the magnetic brush forming portion, and the magnetic binding force cannot prevent the developer from leaking out, and the magnetic seal. The developer leaked to the outside, and finally the developer leaked out of the developing device.

An object of the first invention according to the present application is to solve the above problems and obtain a high quality image while always maintaining a good sealing property regardless of the developer layer thickness regulating method. It is an object of the present invention to provide a developing device that can be used and can prevent image defects caused by developer agglomerates and the like that are generated due to the developer rubbing between the seal member and the developing sleeve, and that is suitable for recycling.

The second object of the present invention is to:
It is an object of the present invention to provide a developing device capable of improving the developer leakage prevention capability as compared with the first invention.

A third object of the present invention is to provide a developing device capable of improving the developer leakage preventing ability as compared with the second invention.

[0018]

According to the first invention of the present application, the above objects are at least a developer having a magnetic agent, a developer carrier having a magnet therein, and the developer carrier. And a toner seal member disposed at both ends of the body so as to face the peripheral surface of the developer carrier with a predetermined gap, and the toner seal member and the developer carrier. In the developing device in which a magnetic circuit is formed in the space between the toner seal member, the toner seal member has a portion facing the developer carrying member, the upstream side in the rotation direction of the developer carrying member, the longitudinal direction of the developer carrying member. It is achieved by being set inside.

According to the second invention of the present application,
The above-mentioned object is, in the above-mentioned first invention, the toner seal member comprises a magnetic body or a magnet and a seal auxiliary member,
This is achieved by providing the sealing auxiliary member so as to project in the radial direction of the developer carrying member more than the magnetic body or the magnet so as to be close to the surface of the developer carrying member.

Further, according to the third invention of the present application, in the above-mentioned second invention, the sealing auxiliary member is provided inside the longitudinal direction of the developer carrier along the rotational direction of the developer carrier. It is achieved by providing it toward.

[0021]

According to the first invention of the present application, the portion of the toner seal member facing the developer carrying member is set at the upstream side in the rotational direction of the developer carrying member and inside the longitudinal direction of the developer carrying member. Therefore, the magnetic brush formed in the gap between the toner seal member and the developer carrying member is directed toward the inner side in the longitudinal direction of the developer carrying member from upstream to downstream in the rotation direction of the developer carrying member. The developer that has been formed and has moved to both ends of the developer carrier by the regulation force of the developer layer thickness regulating member is guided to the magnetic brush formed between the toner seal member and the developer carrier by the rotation of the developer carrier. Then, the developer carrier is pulled back inward in the longitudinal direction.

According to the second invention of the present application,
In the first invention, the seal member is composed of a magnetic body or a magnet and a seal auxiliary member, and the seal auxiliary member is projected on the developer carrying body radial direction side of the magnetic body or the magnet and is on the surface of the developer carrying body. Because it was set up in close proximity,
Even if there is a developer that is not guided by the magnetic brush, it is possible to reliably prevent the developer from leaking.

Further, according to the third invention of the present application, in the above-mentioned second invention, the seal auxiliary member is provided inside the developer carrier in the longitudinal direction along the rotational direction of the developer carrier. Since the developer is not directed to the magnetic brush, the developer is pulled back to the inner side in the longitudinal direction of the developer carrier, and leakage of the developer is surely prevented.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the process cartridge in which at least the developing device, the charging member, and the image carrier are compactly integrated will be described as an example, but the invention can be applied to developing devices of other forms.

First, the structure of the process cartridge according to this embodiment will be described with reference to FIGS.

The process cartridge according to this embodiment is
Charging roller 1 serving as charging means, image carrier 2, developing device 1
7. The cleaning device 15 is included. An opening is provided between the charging roller 1 and the developing device 17 for exposing the image carrier 2 by the exposing means 18.

The charging roller 1 is in contact with the image carrier 2 and rotates in the direction of the arrow c in the drawing following the rotation of the image carrier 2 in the direction of the arrow a in the drawing, and DC and AC are superposed on the charging roller 1. By applying a voltage, the surface of the image carrier 2 can be uniformly charged to a predetermined potential.

The image carrier 2 has a photosensitive layer coated on the surface thereof, and is rotated in the direction of arrow a by a drive system (not shown) provided on the main body of the image forming apparatus.
As described above, the surface is charged by the charging roller 1 and then exposed by the exposure unit 18, so that an electrostatic latent image is formed on the surface.

The developing device 17 rotates in the direction of arrow b in the figure, together with a one-component magnetic developer 8 (hereinafter referred to as toner) for visualizing the electrostatic latent image formed on the image carrier 2. , A developing sleeve 3 as a hollow cylindrical developer carrying member which is arranged at a constant distance from the image carrier 2 and which rotates in the direction of the arrow b to convey the toner 8, and both ends are fixed inside the developing sleeve 3. And a cylindrical magnet roller 4 having a plurality of magnetic poles inside, which is stationary without rotating, and a developer which abuts the developing sleeve 3 and regulates the coating layer thickness of the toner 8 on the developing sleeve 3. Elastic rubber blade 5 serving as a layer thickness regulating member, and a metal member 7 supporting the elastic rubber blade 5.
And a developer storage chamber 13 for storing the toner 8. Inside the developer accommodating chamber 13, there is provided a stirring means 12 for stirring the toner 8 and carrying the toner 8 to the developing sleeve 3.

Below the developing sleeve 3, a thin plate member such as polyethylene terephthalate is used as the toner leakage prevention member 1.
As shown in FIG. 1, the toner is brought into contact with the developing sleeve 3 with a very light pressure. At both ends of the developing sleeve 3, a magnetic material 6 serving as a toner seal member is arranged along the peripheral surface of a part of the developing sleeve 3 at a constant distance from the developing sleeve 3. Details of the structure around the magnetic body 6 and the toner sealing method will be described later.

The cleaning device 15 includes a cleaning blade 14 for scraping off the toner 8 remaining on the surface of the image carrier 2 after transfer, and the scraped toner 8 (hereinafter,
A cleaner container 14 for storing waste toner) and a squeeze sheet 10 that comes into contact with the image carrier 2 with a light pressure so that the waste toner does not leak out of the process cartridge.
Consists of.

Next, the image forming method in this embodiment will be described in detail with reference to FIG. The toner 8 is conveyed to the developing sleeve 3 by the stirring means 12, and is carried on the surface of the developing sleeve 3 by the magnetic force of the conveying pole of the magnet roller 4. The toner 8 is conveyed to the contact surface between the developing sleeve 3 and the elastic blade 5 as the developing sleeve 3 rotates in the direction of the arrow b in the figure, and is rubbed by the developing sleeve 3 and the elastic blade 5 to be given a desired charge. It

After that, the laser beam reaches a position facing the image bearing member 2 and flies to a latent image forming portion on the image bearing member 2 by an alternating electric field formed between the developing sleeve 3 and the image bearing member 2 to cause a latent image. Visualize the image.

The visualized toner image on the image carrier 2 is
The image is transferred onto the transfer material P by the transfer roller 16 (rotational direction is the arrow d direction in the drawing) which is a transfer unit. The toner image on the transfer material P is pressed and heated by a fixing device (not shown), and the toner 8 is fused and fixed on the transfer material P, and is discharged as an output image to the outside of the image forming apparatus.

Next, the structure around the seal member in this embodiment will be described in detail with reference to FIGS.
2 is a longitudinal view of the periphery of the developing sleeve viewed from the direction of arrow X in FIG. 1, and FIG. 3 is a view of the ZZ ′ cross section viewed from the direction of arrow A in FIG.

The developing sleeve 3 has a hollow cylindrical non-magnetic metal such as aluminum as a base, and has a surface blasted to have roughness (for example, average roughness Ra = 1.5 μm). A toner leakage prevention member 11 made of polyethylene terephthalate having a thickness of 50 μm is provided below the developing sleeve 3.
In order to allow the toner on the developing sleeve 3 to pass therethrough and to prevent the toner from leaking due to an impact at the time of mounting the process cartridge, the contact is made with an extremely light pressure to cover at least the toner coat width on the developing sleeve 3. To set up. Inside the developing sleeve 3, at least a S1 pole serving as a developing pole at a position facing the image carrier 2, a S2 pole serving as a carrying pole toward the developer accommodating chamber 13, and N1 poles and N2 poles are magnetized as shown. It has a magnet roller 4 which is formed. S
The magnetic densities of 1 pole, S2 pole, N1 pole and N2 pole are all 6
00G (Gauss) or more. It is preferable that the magnetic material 6 serving as the toner seal member is made of a ferromagnetic material such as an iron plate, a nickel plate, a cobalt plate, or an alloy thereof. In this embodiment, the shape is thickness t = 2 mm, width w
= 4 mm, the cross-sectional shape was approximately a semicircle. This magnetic body 6 is attached to both ends of the developing sleeve 3 and
The developing sleeve 3 and at least the contact surface N (hereinafter referred to as a nip portion) between the developing sleeve 3 and the elastic blade 5 are separated from the surface by a certain distance (g in the figure: 0.3 to 2 mm, for example).
And the toner leakage prevention member 11 is arranged along the peripheral surface including the contact surface H. At this time, as shown in FIG. 2, the end surface of the magnetic body 6 is not perpendicular to the longitudinal direction of the developing sleeve 3 at least downstream of the nip portion N in the rotating direction of the developing sleeve 3 (direction of arrow b in the drawing), and the developing sleeve 3 is not From the upstream side to the downstream side in the rotating direction (the direction of arrow b in the drawing), the developing sleeve 3 is directed toward the center in the longitudinal direction.

Next, the toner sealing method in this embodiment will be described with reference to FIGS. The toner 8 is conveyed toward the developing sleeve 3 by the stirring means 12, and is carried on the surface of the developing sleeve 3 by the magnetic force of the S2 pole which is the conveying pole of the magnet roller 4. The toner 8 carried on the surface of the developing sleeve 3 enters the portion E in the drawing and reaches the nip portion N by the rotation of the developing sleeve 3 (the rotation direction is the direction of the arrow b in the drawing). However, since the toner 8 is regulated to have a desired thickness by the elastic blade 5, the toner 8 that has entered the portion E in the figure naturally includes the toner 8 that cannot pass through the nip portion N. The toner 8 that cannot pass through the nip portion N receives a force in the longitudinal direction both ends of the developing sleeve 3, that is, in the direction of leaking to the developing device 17 side, and at both ends of the developing sleeve 3, more specifically, the magnetic body 6 as the toner seal member and the developing sleeve. It moves to a portion close to the nip portion N between the three.

The surface of the magnetic body 6 facing the developing sleeve 3 is a magnet roller 4 arranged in the developing sleeve 3.
Is magnetized by the magnetic force of the magnetic roller 4 and a magnetic circuit is formed between the magnet roller 4 and the magnetic body 6, and the magnetic field is concentrated between the magnetic body 6 and the developing sleeve 3. Therefore, between the magnetic body 6 and the developing sleeve 3. , The toner 8 forms a dense magnetic brush. In this embodiment, as described above, the magnetic body 6 is located downstream of the nip portion N in the rotational direction of the developing sleeve 3 (direction of arrow b in the drawing) and from the upstream side to the downstream side of the rotational direction of the developing sleeve 3. 3 is arranged so as to face the inner side in the longitudinal direction of 3, the dense magnetic brush between the magnetic body 6 and the developing sleeve 3 is also formed so as to face the inner side in the longitudinal direction of the developing sleeve 3.

Therefore, the toner having moved to both ends of the developing sleeve 3 receives a force to be returned to the inside of the developing sleeve 3 in the longitudinal direction by being guided by the magnetic brush, and the toner 8 is pulled back to the inside of the developing sleeve 3 in the longitudinal direction. By repeating this process, it is possible to prevent the toner 8 from staying in a portion close to the nip portion N between the magnetic body 6 serving as the toner seal member and the developing sleeve 3 and concentrating the toner 8 so that it cannot be restrained by the magnetic brush. Since it is possible to always hold the magnetic brush stable, it is possible to reliably prevent the toner 8 from leaking out of the developing device 17.

Using the developing device of this embodiment, a verification experiment was conducted under the following conditions in order to prove the effect of the present invention.

Process speed (drum peripheral speed) = 24
mm / sec (equivalent to A4 paper length 4 / min) -Sleeve peripheral speed = drum peripheral speed-Durability number = 4000 sheets-Image printing rate = 4%

The above experiment was conducted under high temperature and high humidity (30 ° C./85° C.).
%) And low temperature and low quality (15 ° C./10%), and the toner was refilled in the developing device, and this was repeated 10 times. As a result, toner was not leaked to the outside of the developing device, and toner aggregates were not generated between the seal portion and the developing sleeve, even though the image formation of 40000 A4 vertical sheets was performed.

Therefore, according to the present invention, it is possible to provide a developing device capable of reliably preventing toner leakage from both ends of the developing sleeve and obtaining a high-quality image regardless of the developer layer thickness regulating method. . Further, since the toner sealing member does not rub against the developing sleeve, it is possible to prevent the generation of toner agglomerates at the edges of the developing sleeve, avoid image defects due to the toner agglomerates, and wear and seal performance. Since it does not deteriorate, it is possible to provide a developing device that can be used by recycling.

In this embodiment, the developer layer thickness regulating member is the elastic blade that contacts the developing sleeve. However, the invention is not limited to this, and the magnetic plate blade may be provided in the developing sleeve in a non-contact manner. And other methods for controlling the developer layer thickness do not impair the effects of the present invention.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. 4 of the accompanying drawings. The structure of the process cartridge according to the present embodiment and the image forming process are the same as those in the first embodiment described above, and thus the description thereof will be omitted.

The present embodiment is different from the above-mentioned first embodiment in that the toner seal member provided with a predetermined gap at both ends of the developing sleeve is a magnet. Therefore, only the structure of the both ends of the developing sleeve and the sealing method will be described in detail with reference to FIG. 4 of the accompanying drawings.

FIG. 4 is a sectional view of only the developing sleeve, the magnet roller and the magnet as the toner seal member according to this embodiment. The other structure is similar to that of the first embodiment.

Inside the developing sleeve 3, the S1 pole which is a developing pole at a position facing the image carrier, the S2 pole which is a conveying pole to the developer accommodating chamber side, the N1 pole which is an elastic blade side, and the N1 pole which is a lower side of the developing sleeve. It has a magnet roller 4 having a total of four N2 poles. The toner seal portion 6 is a magnet, and the S3 pole and N
A magnet 6-1 having a 3 ′ pole, a magnet 6-2 having a N3 pole and an S3 ′ pole, and a magnet 6-3 having an S4 pole and an N4 ′ pole are adhered and integrated as shown in FIG. Reverse poles S3 pole, N3 pole, and S4 pole are arranged at positions facing the N1 pole, S2 pole, and N2 pole, respectively. At this time, the magnetic density of the N1, S2 and N2 poles of the magnet roller is
The magnetic densities of the S3 pole, N3 pole, and S4 pole of the magnet are 400 G, respectively. The shape of the magnet 6 is t
= 2 mm, width w = 4 mm, and the cross-sectional shape was approximately a semicircle.

Next, regarding the toner sealing method in this embodiment, since it is almost the same as that in the first embodiment, the description of the overlapping portions will be omitted.

A dense magnetic brush is formed between the magnet 6 and the developing sleeve 3 as in the first embodiment. However, in this embodiment, since the magnet 6 is used as the seal member, the first embodiment is different from the first embodiment. In comparison, the magnetic field concentration between the developing sleeve 3 and the magnet 6, which is the seal member, becomes stronger, and a magnetic brush with higher density is formed. Therefore, the toner 8 moved to a portion near the nip portion N between the magnet 6 serving as the seal member and the developing sleeve 3 by the regulation force of the elastic blade 5 is guided to the magnetic brush as the developing sleeve 3 rotates. As described above, the toner 8 is pulled back inward in the longitudinal direction of the developing sleeve 3 in response to the force returned inward in the longitudinal direction of the developing sleeve 3. By repeating this process, it is possible to prevent the toner 8 from staying in a portion near the nip portion N between the magnet 6 serving as the seal member and the developing sleeve 3 and concentrating so that it cannot be constrained by the magnetic brush. Since a high magnetic brush can be held, the developing device 17 for the toner 8
It is possible to reliably prevent leakage to the outside.

As a result, according to the present invention, the toner sealing property is higher than that of the first embodiment, and the first
It is possible to obtain the same effect as that of the embodiment. In this embodiment, the developer layer thickness regulating member is an elastic blade that contacts the developing sleeve, but the invention is not limited to this, and a method of providing a magnetic plate blade in a non-contact manner with the developing sleeve and other The method of controlling a developer does not impair the effects of the present invention.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. 5 and 6 of the accompanying drawings.
5 is a longitudinal view of the periphery of the developing sleeve viewed from the direction of arrow X in FIG. 1, and FIG. 6 is a view of the ZZ ′ cross section viewed from the direction of arrow A in FIG.

The present embodiment is different from the above-described first and second embodiments in that the developing sleeve is provided on the outer side in the longitudinal direction of the developing sleeve of the toner seal member provided with a predetermined gap at both ends of the developing sleeve. That is, the seal auxiliary member protruding to the side is provided. Therefore, the structure of the process cartridge and the image forming process according to this embodiment are the same as those of the first embodiment and the second embodiment described above, and thus the description thereof will be omitted, and the structure around the seal member and the sealing method will be described.
Only parts different from the first and second embodiments described above will be described in detail with reference to FIGS. 5 and 6 of the accompanying drawings.

In this embodiment, the toner seal member 6 is composed of a magnetic body 6a and a thin plate member 6b. The magnetic material 6 is preferably made of a ferromagnetic material such as an iron plate, a nickel plate, a cobalt plate, or an alloy thereof. The shape of the magnetic body 6a is such that the thickness t = 2 mm and the width w = 4 mm, and the cross-sectional shape is approximately a semicircle. The thin plate member 6b is a polyethylene terephthalate sheet having a thickness of 50 μm, has a semicircular shape concentric with the magnetic body 6a, and is made substantially perpendicular to the developing sleeve 3 as shown in FIG.
It is affixed to the end surface of the developing sleeve 3 a on the outside in the longitudinal direction. At this time, the distance between the magnetic body 6a and the developing sleeve 3 (g in the figure)
Is 2 mm, and the distance (g 'in the figure) between the thin plate member 6b and the developing sleeve 3 is about 0.5 mm.

According to the configuration of this embodiment, the developing sleeve 3
While the toner is being rotated, the toner 8 is moved to both ends of the developing sleeve 3 and the seal member 6 in the vicinity of the nip portion N by the regulating force of the elastic blade 5, the first embodiment and the second embodiment described above. Similar to the example, the magnetic body 6a and the developing sleeve 3
By the magnetic brush formed between the developing sleeve 3
With the rotation of, the developing sleeve 3 is pulled back inward in the longitudinal direction. By repeating this process, it is possible to prevent the toner 8 from staying in both ends of the developing sleeve and the seal member 6 in the vicinity of the nip portion N and concentrating to the extent that it cannot be constrained by the magnetic brush, so that a stable magnetic Since the brush can be held, it is possible to reliably prevent the toner 8 from leaking out of the developing device 17. Further, since the thin plate member 6b is provided on the outer side in the longitudinal direction of the developing sleeve 3 made of a magnetic material so as to project to the developing sleeve 3, the toner leakage is further increased as compared with the first and second embodiments described above. The prevention effect becomes good. Therefore, regardless of the amount of the magnetic substance contained in the toner, that is, the magnitude of the magnetic binding force, a good sealing property can always be maintained. Therefore, the present invention includes the magnetic substance regardless of the one component and the two components. It can be easily applied to a developing device using many types of developing agents.

In this embodiment, the thin plate member is taken as an example, but a brush member or an elastic body such as foam or rubber may be used. Further, the developer layer thickness regulating member is the elastic blade that comes into contact with the developing sleeve, but the invention is not limited to this, and a method of providing a magnetic plate blade in a non-contact manner with the developing sleeve and other developer layers Even the thickness control method does not impair the effects of the present invention.

[0058]

As described above, the first aspect of the present application
According to the invention, since the portion of the toner seal member facing the developer carrying member is set to the inner side in the longitudinal direction of the developer carrying member as it goes to the upstream side in the rotation direction of the developer carrying member, the developer layer thickness It is possible to provide a developing device capable of reliably preventing the developer from leaking from both ends of the developer carrier and obtaining a high-quality image regardless of the regulation method. Furthermore, since the toner seal member does not rub against the developer carrying member, it is possible to prevent the generation of agglomerates of the developer at the end portion of the developer carrying member, which results in image defects, for example, the agglomerates and the developer carrying member. It is possible to avoid white streak images, etc. that occur due to being pinched between the developer layer thickness control member, and also because the seal performance does not deteriorate even when used for a long period of time. It is possible to provide a developing device that can be used.

According to the second invention of the present application,
In the first invention, the seal member is composed of a magnetic body or a magnet and a seal auxiliary member, and the seal auxiliary member is projected on the developer carrying body radial direction side of the magnetic body or the magnet and is on the surface of the developer carrying body. Because it was set up in close proximity,
The sealability of the developer can be improved more than in the first aspect.

Further, according to the third invention of the present application, in the above-mentioned second invention, the seal auxiliary member is provided inside the developer carrier in the longitudinal direction along the rotational direction of the developer carrier. The sealability of the developer can be improved more than that of the second aspect of the invention because the sealant is provided so as to face the above.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a process cartridge according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a longitudinal direction around a developer carrier as seen from a developer accommodating chamber according to the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a developing sleeve and a seal member according to a second embodiment of the present invention.

FIG. 5 is a view showing a longitudinal direction around a developer carrier as seen from a developer accommodating chamber according to a third embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of a developing device according to a third embodiment of the present invention.

[Explanation of symbols]

 3 developing sleeve (developer carrying member) 4 magnet roller (magnet) 6 toner seal member 6a magnetic body 6b thin plate member (auxiliary seal member) 8 developer 17 developing device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanobu Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A developer having at least a magnetic agent,
A developer carrying member having a magnet inside, and a toner seal member arranged at both ends of the developer carrying member so as to face the peripheral surface of the developer carrying member with a predetermined gap therebetween. A developing device having a magnetic circuit formed in a gap between the toner seal member and the developer carrying member, the toner seal member is configured such that a portion facing the developer carrying member has the developer carrying member. The developing device is set so as to be located inward in the longitudinal direction of the developer carrying member on the upstream side in the rotational direction of. 2. The toner seal member is composed of a magnetic material or magnet and a seal auxiliary member, and the seal auxiliary member protrudes to the developer carrying member radial direction side of the magnetic material or magnet and is on the surface of the developer carrying member. The developing device according to claim 1, wherein the developing devices are provided so as to be close to each other. 3. The developing device according to claim 2, wherein the seal auxiliary member is provided so as to extend inward in the longitudinal direction of the developer carrying member along the rotation direction of the developer carrying member.