JP2000019842A - Developing device, process cartridge equipped with the same and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device having improved sealability whereby the slipping off and the leakage of a magnetic developer are prevented, to provide a process cartridge equipped with it and to provide an image forming device. SOLUTION: On the internal peripheral face of a magnet seal member 34, projections 34a of the magnet seal member 34 are formed. The magnetic force lines are drawn perpendicular to a sleeve while concentrated on the projections 34a of the magnet seal member 34 and magnetic toner T is arrayed along the magnetic force lines. Therefore, by concentrating the magnetic force lines onto the projections 34a of the magnet seal member 34, the napping of a magnetic-brush can be formed and satisfactory sealability is exhibited to effectively prevent the slipping off, the leakage or the like of the developer against impact.

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 forming an image by an electrophotographic recording method or the like, and more particularly, to a developing device using a magnetic developer and a process cartridge having the developing device. is there.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus for forming an image by an electrophotographic method or the like, an electrophotographic photosensitive member as an image bearing member and a process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge. A process cartridge system in which a cartridge is detachable from an image forming apparatus main body is employed.

According to this process cartridge system,
Since the maintenance of the apparatus can be performed by the user himself without relying on a service person, the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

In a developing device built in such a process cartridge, the developer as a magnetic developer is prevented from flowing out of the developing area to both ends of a developing sleeve as a rotating developer carrier. Sealing member is provided.

Heretofore, elastic materials such as felt and foam rubber have been widely used as seal members for preventing the developer from flowing out. Representative examples are shown in FIGS.

FIG. 15 is a front sectional view showing a main part of a developing device incorporated in a conventional process cartridge, and FIG. 16 is a side sectional view showing a main part of the developing device.

[0007] As shown in FIG.
Has a magnet roller 32 inside thereof, and is rotatably supported by the developing container 30 via a sleeve bearing 35 as shown in FIG.

Accordingly, the developer supplied from the developing container 30 adheres to the surface of the developing sleeve 31 by the magnetic force of the magnet roller 32, and after the layer thickness is regulated to be constant by the developing blade 33, the rotation of the developing sleeve 31 is performed. Accordingly, at a position opposed to the latent image on the photosensitive drum 1, the latent image is attached to the latent image for development.

An elastic seal member 36 is attached to both ends in the longitudinal direction outside the developing region of the developing sleeve 31 and at the back opposite to the opening of the developing sleeve 31 mounted on the developing container 30. The elastic seal member 36 is pressed against the outer peripheral surface of the developing sleeve 31 to prevent the developer from flowing out.

However, in the developing device having such a configuration,
An elastic seal member 36 is provided on half of the outer peripheral surface of the developing sleeve 31.
Are pressed against each other, so that the load on the developing sleeve 31 that rotates during the developing operation is large, and the elastic seal member 36 is deteriorated due to the contact with the developing sleeve 31, so that the sealing property is deteriorated.

Further, a small amount of the developing material may enter between the developing sleeve 31 and the elastic seal member 36. As a result, the torque increases or the fluctuation of the torque increases, resulting in uneven rotation. Was produced, which could adversely affect image formation.

Therefore, in order to solve these problems, a method has been proposed in which magnet seal members are arranged at both ends of the developing sleeve 31 at regular intervals to thereby prevent the developer from flowing out.

FIG. 17 is a front sectional view showing a developing device using a magnet seal member, and FIG. 18A is a schematic diagram showing a magnetization pattern of the magnet seal member.

As shown in FIG. 18A, the magnet seal member 34 is made of a magnet, and has NS poles magnetized on its inner peripheral surface into multiple magnetic poles. As shown in FIG. 17, the magnet seal member 34 is disposed at both ends of the developing sleeve 31 so as to be spaced apart from the outer peripheral surface of the developing sleeve 31 having the magnet roller 32 by a predetermined gap g. It is wound and attached to the developing container 30 together with the developing sleeve 31 in this state.

FIG. 18 shows another example of the prior art.
(B), a configuration using a magnet seal member 34 magnetized in a magnetic pole pattern as shown in FIG. 18 (c) is also known.

As a result, the developing sleeve 31 and the magnet seal member 34 can be brought into non-contact with each other.
Is extremely small, the drive motor may be small and inexpensive, the fluctuation of the rotation torque is small, and the rotation unevenness of the developing sleeve 31 and the photosensitive drum 1 hardly occurs. The use is semi-permanent because wear and the like are eliminated, and recycling is possible.

[0017]

However, in the above-mentioned prior art, when the developing device is used, the developer held on the developing sleeve moves to the longitudinal end of the developing sleeve with the rotation of the developing sleeve, and the magnet seals. In some cases, problems such as slipping through the member and developer leakage caused by impact or the like may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a developing device for improving a sealing property for preventing a magnetic developer from slipping through or leaking, a process cartridge provided with the developing device, and an image. It is an object to provide a forming device.

[0019]

In order to achieve the above object, a developing device according to the present invention comprises a developer carrier rotatably supported and carrying a magnetic developer by arranging a magnet therein. And a magnet seal member arranged at both ends in the longitudinal direction of the developer carrier with a predetermined gap from the outer peripheral surface of the developer carrier, wherein the magnet seal member comprises the developer A magnetic field line concentration means for concentrating magnetic lines of force perpendicular to the outer peripheral surface of the carrier is provided.

Therefore, the magnetic developers are arranged along the concentrated lines of magnetic force, so that the magnetic developer can be prevented from slipping through and leaking to both ends in the longitudinal direction of the developer carrier, and the sealing property can be improved. Can be.

It is preferable that the magnetic field concentration means is a plurality of projections formed on the inner peripheral surface of the magnet seal member.

Thus, the lines of magnetic force perpendicular to the outer peripheral surface of the developer carrier can be concentrated, and the magnetic developer can be stored in the groove between the plurality of convex portions.
It is possible to prevent the magnetic developer from slipping or leaking to both ends in the longitudinal direction of the developer carrier.

It is preferable that the plurality of projections are formed along the rotation direction of the developer carrier.

Thus, the groove between the plurality of convex portions is also formed along the rotation direction of the developer carrier, and the movement of the magnetic developer toward both ends in the longitudinal direction of the developer carrier is prevented. Can be stored in the groove to prevent the magnetic developer from slipping or leaking to both ends in the longitudinal direction of the developer carrying member.

The plurality of protrusions are inclined with respect to the rotation direction of the developer carrier so that the groove between the plurality of protrusions guides the magnetic developer to the longitudinal center of the developer carrier. Is preferably formed.

Accordingly, the groove between the plurality of convex portions is also formed obliquely to the rotation direction of the developer carrier, and the magnetic developer stored in the groove at the longitudinal center of the developer carrier. Can be prevented, and the magnetic developer can be prevented from slipping or leaking to both ends in the longitudinal direction of the developer carrying member.

Preferably, the plurality of projections are formed in a continuous mesh.

This makes it possible to prevent the magnetic developer from slipping or leaking to both ends in the longitudinal direction of the developer carrying member.

Preferably, the plurality of projections are formed such that grooves between the plurality of projections are meshed.

Thus, it is possible to prevent the magnetic developer from slipping or leaking to both ends in the longitudinal direction of the developer carrier.

It is preferable that the inner peripheral surface of the magnet seal member is alternately magnetized with multiple NS poles at predetermined intervals along the rotation direction of the developer carrier.

Thus, the magnetic developer can be restrained over the entire inner peripheral surface of the magnet seal member.

It is preferable that the protrusions on both sides of the groove between the plurality of protrusions are magnetic poles of the same polarity.

Accordingly, the groove cannot hold the magnetic developer due to the action of the repulsive magnetic field, and the magnetic developer can easily move in the groove.

It is preferable that the protrusions on both sides of the groove between the plurality of protrusions have magnetic poles of different polarities.

Thus, the magnetic developer can be better restrained over the entire inner peripheral surface of the magnet seal member.

It is preferable that a magnetic member is disposed in a groove between the plurality of projections.

Thus, the lines of magnetic force perpendicular to the outer peripheral surface of the developer carrier can be more concentrated.

The process cartridge of the present invention preferably includes at least the developing device described above and an image carrier.

Accordingly, it is possible to prevent the magnetic developer of the provided developing device from slipping through or leaking, and to improve the sealing property.

The image forming apparatus of the present invention includes the above-mentioned developing device, and supplies a magnetic developer to the image carrier to form an image on a sheet.

Accordingly, the magnetic developer in the provided developing device can be prevented from slipping through or leaking, and the sealing performance can be improved.

An image is formed on a sheet by providing the above process cartridge.

As a result, the magnetic developer in the provided developing device can be prevented from slipping through or leaking, and the sealing performance can be improved.

[0045]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However,
The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to them unless otherwise specified. .

(First Embodiment) FIG. 14 is a schematic diagram showing an embodiment of a laser beam printer as an image forming apparatus utilizing a transfer type electrophotographic process of a process cartridge detachable type to which the present invention is applied. is there.

Reference numeral 1 denotes a rotating photosensitive drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image carrier, which is driven to rotate clockwise as indicated by arrow a.

Around the photosensitive drum 1, a charging device 2, an image exposure device E, a developing device 3, a transfer device 4, and a cleaning device 6 are provided.

After the photosensitive drum 1 is uniformly charged by the charging device 2, image exposure is performed by a laser beam E in accordance with an image information signal, an electrostatic latent image is formed on the photosensitive drum 1, and development is performed. The electrostatic latent image is developed by the device 3.

This visible image is transferred to a transfer material P by a transfer roller 4 as a transfer means at a transfer portion T by an electrostatic force and a pressing force.
The transferred image is transferred to a fixing device such as a heat fixing method (not shown), and the visible image on the transfer material P is fixed, and is discharged out of the device as an image formed product (print, copy).

After the transfer of the toner image to the transfer material P, the photosensitive drum surface is cleaned by the cleaning device 6 to remove the adhered contaminants such as residual toner, and is repeatedly used for image formation.

In the image forming apparatus of this embodiment, the photosensitive drum 1, the charging device 2, the developing device 3, and the cleaning device 6
The four process devices are collectively provided as a process cartridge 10 which can be freely attached to and detached from the image forming apparatus main body.

Reference numeral 9 denotes a photosensitive drum 1, a charging device 2, a developing device 3, and a cleaning device 6 which are the four process devices.
At a predetermined position. Reference numeral 8 denotes a process cartridge insertion / removal guide / holding unit on the image forming apparatus main body side.

When the process cartridge 10 is mounted in the image forming apparatus main body in a predetermined manner, the process cartridge 10 and the image forming apparatus main body are mechanically and electrically coupled to each other. The lower surface of the photosensitive drum 1 is brought into contact with the transfer roller 4 on the image forming apparatus main body side in a predetermined manner, and an image forming executable state is established.

The process cartridge 10 is a cartridge in which a charging device, a developing device or a cleaning device, and a photosensitive drum are integrally formed as a cartridge, and this cartridge is detachably mountable to an image forming apparatus main body. In addition, at least one of the charging device, the developing device, and the cleaning device and the photosensitive drum are integrally formed as a cartridge so that the cartridge can be attached to and detached from the image forming apparatus main body. Further, it refers to a device in which at least the developing device and the photosensitive drum are integrally formed as a cartridge so as to be detachable from the image forming apparatus main body.

Next, the developing device 3 will be described with reference to FIGS. 1 is a central sectional view of the developing device, FIG. 2 is an end sectional view of the developing device, FIG. 3 is a perspective view of a developer carrier and a magnet seal member, and FIG. 4 is a longitudinal sectional view of a main part of the developing device. FIG. 5 is a perspective view for explaining the magnetization pattern of the magnet seal member.

Reference numeral 30 denotes a developing container containing a magnetic toner T as a magnetic developer. Reference numeral 31 denotes a non-magnetic sleeve such as aluminum or stainless steel as a developer carrier, in which a roller-shaped magnet 32 is fixedly disposed, and is rotatable in a developing container 30 via a sleeve bearing (not shown). Installed.

The magnet roller 32 has two N poles N on its surface.
1, N2, and two south poles S1 and S2.

The sleeve 31 rotates counterclockwise as indicated by the arrow, and the magnetic toner T supplied in the developing container 30 adheres to the surface by the magnetic force of the magnet roller 32 and is conveyed.

Reference numeral 33 denotes a regulating blade (elastic blade) as a developer layer thickness regulating means, which presses the sleeve 31 at the outlet of the developing container 30 in the presence of the N2 pole, and carries the sleeve 31 to the developing area. It regulates the thickness of the developer layer.

The magnetic toner T carried and conveyed visualizes a latent image formed on the photosensitive drum 1 moving in the direction of the arrow (the developing magnetic pole S1) in the developing area.

A vibration bias voltage obtained by superimposing a DC voltage on an AC voltage is applied to the sleeve 31 from a power supply (not shown). Incidentally, a rectangular wave, a sine wave or the like is used as the waveform of the vibration bias voltage.

The residual magnetic toner T after the development is applied to the developing container 30 at the take-in pole N1 at the entrance of the developing container 30.
The toner is collected into the developer container 30, and is stirred and mixed with the magnetic toner in the developing container 30 via the pumping pole S2.

As shown in FIG. 5, reference numeral 34 denotes a magnet seal member in which the NS pole is magnetized into multiple magnetic poles on the inner peripheral surface, and the magnet seal member 34 is curved on the inner peripheral surface along the rotation direction of the sleeve 31. A plurality of convex portions 34a of the magnet are formed,
A groove 34b is formed between the magnet 34a and the magnet 34a.
As shown in FIGS. 1 to 4, they are provided at both ends of the sleeve 31.

This magnet seal member 34 is
And is attached to the developing container 30 with a gap g from the outer peripheral surface. This magnet seal member 34 has three S poles S11, S12, S13 and three N poles N1 on its inner peripheral surface.
1, N12 and N13 are alternately arranged. Since the NS poles are alternately arranged, the magnetic toner T can be effectively restrained by the magnet seal member 34 over the entire inner peripheral surface.

FIG. 6 is a model diagram showing the state of the lines of magnetic force due to the configuration of the magnet seal member. FIG. 6 (a) shows a flat planar configuration in which there is no convex portion of the magnet seal member 34 on the inner peripheral surface as in the prior art. FIG. 6B shows a case where the convex portion of the magnet seal member 34 is formed on the inner peripheral surface as in the case of the present embodiment.

As shown in FIG. 6A, when the inner peripheral surface is flat without the convex portion of the magnet seal member 34, the lines of magnetic force are directed almost perpendicular to the sleeve 31, but are slightly diffused. The magnetic toner T is arranged and sealed along the lines of magnetic force.

On the other hand, when a plurality of protrusions 34a of the magnet seal member 34 are formed on the inner peripheral surface as shown in FIG. 6B, the lines of magnetic force are applied to the plurality of protrusions 34 of the magnet seal member 34.
Since the magnetic toner T is directed more perpendicularly to the sleeve 31 while being concentrated at a, and the magnetic toner T is arranged along the lines of magnetic force, the sealing property is further improved. It should be noted that even if a non-magnetic member is arranged between the plurality of convex portions 34a of the magnet seal member 34, the lines of magnetic force show the same shape.

From the above, in the present embodiment,
Since the magnetic brush can be formed by concentrating the lines of magnetic force on the protrusions 34a of the magnet seal member 34, good sealing properties can be exhibited, and the developer can pass through and the developer leaks against an impact. Can be prevented.

FIG. 7A is a model diagram for explaining the shape of the magnet sealing member 34, and the dotted line indicates the position of the sleeve 31.

A plurality of convex portions 34a of the magnet seal member 34 are arranged in order from the inside in the longitudinal direction of the sleeve so as to face the sleeve 31.
1, 34a2, 34a3 are formed, and the convex portions 34a
Magnetic poles (N poles in the illustrated example) are magnetized on the (projections 34a1, 34a2, 34a3), and a groove 34b is formed between each of the projections 34a.

W1 is the width of the projection 34a in the sleeve longitudinal direction, and W2 is the width of the groove 34b. The width W of the projection 34a
If the value of 1 is small, the effective part for concentrating the magnetic field lines becomes narrow,
If the width W2 of the groove 34b is small, it is not possible to effectively concentrate the magnetic force lines. In order to concentrate the lines of magnetic force on the convex portion 34a and obtain good sealing properties, the width W1 of the convex portion 34a and the groove 34b
Of the width W2 is 0.5 ≦ W1 / (W1 + W2) ≦
0.8 is preferred.

Generally, when the sleeve 31 is rotated, a force is exerted on the magnetic toner T on the sleeve 31 to move to the end in the longitudinal direction of the sleeve due to the diffusion action. The movement toward the end (the passage of the developer) is prevented by the magnet seal member 34. The magnetic toner T on the sleeve 31 moves to the end in the longitudinal direction of the sleeve due to the diffusion action.
It is held and sealed at 1.

Further, the magnetic toner, which has been moved by the diffusion action, extrudes the magnetic toner held by the convex portion 34a1 toward the end, and is held and sealed by the next-stage convex portion 34a2. Alternatively, a part of the magnetic toner held by the protrusion 34a1 on the side of the protrusion 34a2 is held and sealed by the next-stage protrusion 34a2 to which the protrusion 34a2 is attracted.

As described above, since the seal member 34 is configured in multiple stages, the seal can be effectively performed.

Further, since the magnetic toner which is going to move from the convex portion 34a1 to the convex portion 34a2 can be stored in the groove 34b, the amount of the magnetic toner which can be held by the magnet seal member 34 increases, so that the developer slips through. Can be further prevented.

Next, numerical examples will be described.

In this embodiment, the peripheral speed of the photosensitive drum 1 is 9
4 mm / sec, outer diameter is 30 mm, peripheral speed of sleeve 31 is 111 mm / sec, outer diameter of sleeve 31 is 16 mm
And

The rotation direction of the sleeve 21 is set to the forward direction with respect to the photosensitive drum 1. The distance h between the photosensitive drum 1 and the sleeve 31 was 0.3 mm.

At this time, the peak value of the magnetic flux density in the direction normal to the sleeve surface on the sleeve surface of each magnetic pole of the magnet roller 32 fixed in the sleeve 31 is 400 to 9
It was 00 × 10 ⁻⁴ T (tesla). Magnet seal member 3
Reference numeral 4 denotes an injection-molded article provided with a nylon binder containing a magnetic powder of Nd-Fe-B. Magnet seal member 3
4 had a width of 2.5 mm, and the groove 34b between the protrusions 34a was 1.5 mm.

The distance g between the magnet seal member 34 and the sleeve 31 was 0.1 to 0.7 mm. At this time, the peak value of the magnetic flux density on the sleeve surface of each magnetic pole of the magnet seal member 34 in the direction normal to the sleeve surface is 1000 to 1000.
It was 2200 × 10 ⁻⁴ T (tesla).

According to the present embodiment described above, it is possible to prevent the developer from passing through both ends in the longitudinal direction of the developing sleeve, even though the developing device is compact.
In addition, even when a user applies an impact when the process cartridge is attached to or detached from the image forming apparatus main body, good sealing properties can be obtained in which the developer does not leak.

FIG. 7B shows the magnet sealing member 34.
The same effect can be obtained even with the shape shown in FIG.
FIG. 7B and FIG. 7C are model diagrams for explaining the shape of the magnet seal member 34.
a when the non-magnetic member 34c is arranged between
The dotted line indicates the position of the sleeve 31.

FIG. 7 (b) shows that the non-magnetic member 34c is arranged only on the surface layer of the magnet seal member 34 on the side facing the sleeve, and the groove 34b in FIG. 7 (a) is a non-magnetic member. FIG. 7 (c) shows that the non-magnetic member 34c is arranged in the entire area of the magnet seal member 34 in the thickness direction.
Since the magnetic brush can be formed by concentrating the lines of magnetic force on the convex portions 34a of the magnetic head, good sealing properties can be exhibited, and the developer can be effectively prevented from slipping over the developer or leaking due to an impact. Can be.

FIG. 8 (a) shows the structure of the magnet seal member 34.
Similar effects can be obtained with the shape shown in FIG.
FIGS. 8A and 8B are model diagrams for explaining the shape of the magnet seal member 34. The convex portion 34a and the convex portion 34 are shown.
The case where the magnetic member 34d is arranged between the positions a is shown, and the dotted line shows the position of the sleeve 31.

That is, FIG. 8A shows a non-magnetic member 34c shown in FIG. 7B replaced with a magnetic member 34d, and FIG. 8B shows a non-magnetic member 34c shown in FIG. Member 3
4d. When the non-magnetic member 34c was replaced with the magnetic member 34d, the sealing performance was slightly improved. Since the magnetic member 34d is arranged between the magnet portions 34a of the magnet seal member 34, the lines of magnetic force are more concentrated only on the magnet portion 34a, and the sealing performance is improved.

(Second Embodiment) FIG. 9 is a model diagram for explaining the position of the magnet seal member with respect to the developer carrier, and FIG. FIG. 10B is a model diagram showing a pattern, and FIG.
It is AA sectional drawing of 0 (a). In this embodiment, the first
The configuration of the magnet seal member 34 is different from the embodiment of
Other configurations are the same as those of the first embodiment.

That is, in the first embodiment, the groove 34b of the magnet seal member 34 is formed along the rotation direction of the sleeve 31, but in the present embodiment, the groove 34b is formed with respect to the rotation direction of the sleeve 31. It is formed diagonally.

As shown in FIG. 9, the magnet seal members 34 are provided at both ends of the sleeve 31. In FIG. 10A, reference numeral 34b denotes a groove 34b in a direction in which the developer is guided toward the developing area of the developing container. The sleeve 31 is rotationally moved upward from below the illustrated magnet seal member 34, and the groove 34 b is formed obliquely to the rotational direction of the sleeve 31.

The magnet seal members 34 provided at both ends of the sleeve 31 have convex portions 34 as in the first embodiment.
Since the magnetic brush can be formed by concentrating the lines of magnetic force on a, it is possible to exhibit a better sealing property, and it is possible to effectively prevent the developer from slipping out or the developer leaking due to an impact. .

When the sleeve 31 is rotated, the sleeve 3
The magnetic toner T carried and conveyed on 1 moves to the end in the longitudinal direction of the sleeve by the diffusion action, and is held by the magnet seal member 34.

Since the magnetic toner T held by the magnet seal member 34 moves to the development area side of the developing container along the groove 34b, the magnetic toner T that is more than necessary is provided in the gap g between the magnet seal member 34 and the sleeve 31. Does not accumulate, it is possible to always exhibit good sealing properties, and it is possible to more effectively prevent the developer from slipping out or the developer leaking due to impact.

The magnet seal member 34 and the sleeve 31
Since the magnetic toner T does not accumulate more than necessary in the interval g, the rotational torque of the sleeve 31 can be reduced, and the cost of the apparatus can be reduced.

(Third Embodiment) FIG. 11 is a model diagram showing a magnetization pattern on the inner peripheral surface of the magnet seal member 34. This embodiment is different from the second embodiment in the configuration of the magnet seal member 34, and the other configuration is the same as that of the second embodiment.

That is, in the second embodiment, the magnetic poles of the protrusions 34a of the magnet seal member 34 are alternately magnetized to the NS poles along the rotation direction of the sleeve 31, but in the present embodiment, the grooves are formed by the grooves. 34b alternately with the NS pole and along the groove 34b
Are magnetized to the same pole.

In the present embodiment, since the same polarity is magnetized across the groove 34b, the groove 34b cannot hold the magnetic developer due to the action of the repulsive magnetic field.
It becomes easy to move along 4b.

That is, the magnetic developer held by the magnet seal member 34 can easily move to the developing area side of the developing container along the groove 34b, so that the gap g between the magnet seal member 34 and the sleeve 31 is reduced. The magnetic toner T does not accumulate more than necessary, so that good sealing properties can be always exhibited, and the developer can be more effectively prevented from slipping out of the developer and leakage of the developer due to impact.

(Fourth Embodiment) FIG. 12 is a model diagram showing a magnetization pattern on the inner peripheral surface of the magnet seal member 34. This embodiment is different from the second embodiment in the configuration of the magnet seal member 34, and the other configuration is the same as that of the second embodiment.

That is, in the second embodiment, the magnetic poles of the projections 34a of the magnet seal member 34 are alternately magnetized to the NS poles along the rotation direction of the sleeve 31, but in this embodiment, The magnetic poles are alternately magnetized to the NS poles along the grooves 34b between the protrusions 34a, and alternately to the NS poles with the groove 34b interposed therebetween.

In the present embodiment, the magnetic pole structure of the magnet seal member 34 is arranged alternately in an N-pole / S-pole matrix.
Since the adjacent magnetic poles have different polarities in any part, the magnetic toner T can be effectively restrained over the entire inner peripheral surface of the magnet seal member 34.

Further, since the groove 34b is provided in the direction in which the developer is guided to the developing area side of the developing container in the same manner as in the second embodiment, the gap g between the magnet seal member 34 and the sleeve 31 is more than necessary. The toner T does not accumulate, so that good sealing properties can always be exhibited, and the developer can be more effectively prevented from slipping through the developer and leaking from the developer.

(Fifth Embodiment) FIG. 13A is an explanatory view of a main part of a magnet seal member 34. This embodiment is different from the first embodiment in the configuration of the magnet seal member 34, and the other configuration is the same as that of the first embodiment.

That is, in the first embodiment, the plurality of protrusions 34a of the magnet seal member 34 are configured such that the magnetic poles extend along the rotation direction of the sleeve 31, but in this embodiment, the plurality of protrusions 34a The portion 34a is formed in a mesh shape.

In this embodiment, as in the first embodiment, since the magnet seal member 34 is divided into the convex portions 34a and the grooves 34b, the lines of magnetic force are concentrated on the convex portions 34a in the perpendicular direction. As in the first embodiment, the sealing performance is improved.

Further, since the developer can be stored in the groove 34b, it is possible to prevent the developer from passing through as in the first embodiment.

With such a configuration, the magnetic brush can be formed by concentrating the lines of magnetic force on the convex portions of the magnet, so that a good sealing property can be exhibited, and the developer can be prevented from slipping off and impact. It is possible to effectively prevent developer leakage and the like.

Further, the magnet seal member 34 is
The same effects can be obtained by using the shapes shown in FIGS. 13B and 13C. FIGS. 13B and 13C are views for explaining the shape of the magnet seal member 34. FIG. FIG. 13 (b)
In FIG. 13C, the convex portion 34a is formed in a mesh shape.
The groove 34b has a mesh-like ellipse.

Even with such a configuration, since the magnetic brush can be formed by concentrating the lines of magnetic force on the convex portions of the magnet, a good sealing property can be exhibited, and the development of the developer against slip-through or impact of the developer can be achieved. Agent leakage can be effectively prevented.

In the above-described embodiment, the case where the magnetic toner is used as the magnetic developer has been described. However, the magnetic developer includes a non-magnetic toner and magnetic particles (carrier).
The same effect can be obtained by using a component magnetic developer.

[0110]

As described above, the magnet seal member is provided with the magnetic force line concentrating means for concentrating the magnetic force lines directed perpendicularly to the outer peripheral surface of the developer carrying member. Are arranged, so that the magnetic developer can be prevented from slipping through or leaking to both ends in the longitudinal direction of the developer carrying member, and the sealing property can be improved.

Since the magnetic field concentration means is a plurality of convex portions formed on the inner peripheral surface of the magnet seal member, it is possible to concentrate the magnetic force lines perpendicular to the outer peripheral surface of the developer carrying member. The magnetic developer can be stored in the groove between the plurality of convex portions, and it is possible to prevent the magnetic developer from slipping or leaking to both ends in the longitudinal direction of the developer carrier.

Since the plurality of projections are formed along the direction of rotation of the developer carrier, grooves between the plurality of projections are also formed along the direction of rotation of the developer carrier. The movement of the magnetic developer to both ends in the longitudinal direction of the body can be prevented by storing the magnetic developer in the groove to prevent the magnetic developer from slipping and leaking to both ends in the longitudinal direction of the developer carrier. .

The plurality of projections are arranged such that the groove between the plurality of projections guides the magnetic developer to the central portion in the longitudinal direction of the developer carrier.
By being formed obliquely with respect to the rotation direction of the developer carrier, grooves between the plurality of convex portions are also formed obliquely with respect to the rotation direction of the developer carrier, and the center of the developer carrier in the longitudinal direction is formed. The magnetic developer stored in the groove can be guided to the portion, and slip-through and leakage of the magnetic developer to both ends in the longitudinal direction of the developer carrier can be prevented.

Since the plurality of projections are formed in a continuous mesh shape, it is possible to prevent the magnetic developer from passing through or leaking to both ends in the longitudinal direction of the developer carrier.

The plurality of protrusions are formed so that the grooves between the plurality of protrusions are formed in a mesh shape, thereby preventing the magnetic developer from slipping through or leaking to both ends in the longitudinal direction of the developer carrier. can do.

The inner peripheral surface of the magnet seal member is alternately magnetized with multiple magnetic poles at predetermined intervals along the rotation direction of the developer carrier, so that magnetic development is performed over the entire inner peripheral surface of the magnet seal member. Agents can be restrained.

Since the protrusions on both sides of the groove between the plurality of protrusions are magnetic poles of the same polarity, the groove cannot hold the magnetic developer due to the action of the repulsive magnetic field, and the magnetic developer can be easily stored in the groove. It can be moved.

Since the protrusions on both sides of the groove between the plurality of protrusions have magnetic poles of different polarities, the magnetic developer can be better restrained over the entire inner peripheral surface of the magnet seal member.

By arranging the magnetic member in the groove between the plurality of projections, it is possible to concentrate the lines of magnetic force directed perpendicularly to the outer peripheral surface of the developer carrier.

The process cartridge of the present invention includes at least the above-described developing device and an image bearing member.
The magnetic developer in the provided developing device can be prevented from slipping through or leaking, and the sealing property can be improved.

The image forming apparatus of the present invention includes the above-described developing device, and supplies a magnetic developer to the image carrier to form an image on a sheet, thereby preventing the magnetic developer from slipping through the provided developing device. Leakage can be prevented, and sealing performance can be improved.

By providing the process cartridge and forming an image on a sheet, it is possible to prevent the magnetic developer of the provided developing device from slipping through or leaking, and to improve the sealing property.

[Brief description of the drawings]

FIG. 1 is a central sectional view of a developing device.

FIG. 2 is an end sectional view of the developing device.

FIG. 3 is a perspective view of a developer carrier and a magnet seal member.

FIG. 4 is a longitudinal sectional view of a main part of the developing device.

FIG. 5 is a perspective view showing a magnetization pattern of the magnet seal member according to the first embodiment.

FIG. 6 (a) is a model diagram showing a state of a conventional magnetic field line, and FIG. 6 (b) is a model diagram showing a state of a magnetic field line of the first embodiment.

FIG. 7 is a model diagram showing a shape of a magnet sealing member.

FIG. 8 is a model diagram showing a shape of a magnet seal member.

FIG. 9 is a model diagram for explaining a position of a magnet seal member.

FIG. 10A is a model diagram showing a magnetization pattern on an inner peripheral surface of a magnet seal member, and FIG. 10B is a cross-sectional view taken along line AA of FIG. 10A.

FIG. 11 is a model diagram showing a magnetization pattern on the inner peripheral surface of the magnet seal member.

FIG. 12 is a model diagram showing a magnetization pattern on an inner peripheral surface of a magnet seal member.

FIG. 13 is a model diagram showing a magnetization pattern on the inner peripheral surface of the magnet seal member.

FIG. 14 is a schematic configuration diagram illustrating an image forming apparatus.

FIG. 15 is a cross-sectional view illustrating a main part of a conventional developing device.

FIG. 16 is a longitudinal sectional view of a main part of a conventional developing device.

FIG. 17 is a cross-sectional view showing a developing device using a conventional magnet seal member.

FIG. 18 is a perspective view showing a magnetization pattern of a conventional magnet seal member.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum 3 developing device 10 process cartridge 30 developing container 31 sleeve 32 magnet roller 33 elastic blade regulating blade () 34 magnet seal member 34a convex portion 34b groove 34c nonmagnetic member 34d magnetic member g Distance between magnet seal member and sleeve N1 , N2, S2, N2 Magnetic poles of magnet roller N1, N2, N3, S1, S2, S3 Magnetic poles of magnet seal member T Magnetic toner

Claims (13)

[Claims] 1. A developer carrier that is rotatably supported and carries a magnetic developer by arranging a magnet therein, and an outer peripheral surface of the developer carrier at both longitudinal ends of the developer carrier. A magnet seal member arranged with a predetermined gap, wherein the magnet seal member includes magnetic field line concentration means for concentrating magnetic lines of force perpendicular to the developer carrier outer peripheral surface. Characteristic developing device. 2. The developing device according to claim 1, wherein said magnetic field concentration means is a plurality of convex portions formed on an inner peripheral surface of said magnet seal member. 3. The developing device according to claim 2, wherein the plurality of protrusions are formed along a rotation direction of the developer carrier. 4. The developer carrier rotation direction such that a groove between the plurality of protrusions guides a magnetic developer to a central portion in a longitudinal direction of the developer carrier. The developing device according to claim 2, wherein the developing device is formed obliquely. 5. The developing device according to claim 2, wherein the plurality of protrusions are formed in a continuous mesh. 6. The developing device according to claim 2, wherein the plurality of convex portions are formed such that grooves between the plurality of convex portions are formed in a mesh shape. 7. An inner peripheral surface of the magnet seal member is magnetized with multiple magnetic poles of NS poles alternately at predetermined intervals along a rotation direction of the developer carrier. The developing device according to any one of the above. 8. The projections on both sides of a groove between the projections are magnetic poles of the same polarity.
The developing device according to any one of the above. 9. The developing device according to claim 2, wherein the protrusions on both sides of the groove between the plurality of protrusions are magnetic poles having different polarities. 10. The developing device according to claim 2, wherein a magnetic member is disposed in a groove between the plurality of convex portions. 11. A process cartridge comprising at least the developing device according to claim 1 and an image carrier. 12. An image forming apparatus comprising the developing device according to claim 1, wherein an image is formed on a sheet by supplying a magnetic developer to the image carrier. 13. An image forming apparatus comprising the process cartridge according to claim 11, wherein an image is formed on a sheet.