JPH07181810A - Developing device - Google Patents

Abstract

PURPOSE:To prevent generation of white lines in the circumferential direction without applying large driving load on a developer carrying member by forming magnetic lines of force in a gap as well by a magnetic field generating means, thereby forming magnetic brushes by a developer along the magnetic lines of force. CONSTITUTION:A magnetic shielding member 1 is provided with a projection 1b in its lower part and is fitted into a hole of a developing container 6. Further, the magnetic shielding member is fixed to the developing container 6 by a method of sticking a double coated adhesive tape to its outer peripheral surface or other suitable methods. The magnetic shielding member 1 in this constitution is arranged along at least a part of the peripheral surface of the developer carrying member 3 and has a specific gap g1 from the peripheral surface of the developer carrying member 3 and the magnetic lines of force are formed in the gap g1 as well by the magnetic field generating means 4 arranged within the developer carrying member 3 to form the magnetic brushes by the developer along the magnetic lines of force. As a result, the infiltration of the developer, the pieces broken by sliding friction of the magnetic shielding member 1, etc., between the magnetic shielding member 1 and the peripheral surface of the developer carrying member 3 is prevented and the generation of the white lines in the circumferential direction is prevented without applying the large driving load on the developer carrying member 3.

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 an electrostatic latent image formed on an image bearing member by an electrophotographic method or an electrostatic recording method, and in particular, it contains magnetic particles. The present invention relates to a developing device using a developer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus or the like for forming an image by an electrophotographic system or an electrostatic recording system, an image carrier such as a photosensitive drum for carrying an electrostatic latent image formed through a predetermined process. The developer carrying member 3 of the developing device is arranged at a constant interval with respect to the body 100, and an appropriate developing bias voltage is applied between the two to develop the electrostatic latent image on the image carrying member.

The parts which best show the characteristics of the typical developing device are shown in FIGS.

In this example, four magnetic poles, namely N1, S2,
A magnetic field generating means 4 having N2 and S1 and a developer layer forming member 2 whose free end projects from the center of the pressure contact portion between the developer carrying body 3 and the developer layer forming member 2 to the upstream in the rotation direction of the developer carrying body 3. Although the developing device having the above is taken up, it is needless to say that it is not limited to this.

In order to perform the above-mentioned development, as one of the methods for forming a developer layer on the developer carrying member 3, the elastic member 2 is brought into contact with the developer carrying member 3 at an appropriate pressure to develop the developer. A method of forcibly applying the developer to the developer carrier 3 by sending the developer t to the contact portions of these two has been widely used as the agent carrier 3 rotates.

Here, as the above-mentioned developer layer forming member 2, rubber, a metal plate or the like is used.

Further, for the purpose of preventing the developer from wrapping around the back surface of the developer layer forming member 2 and disturbing the behavior of the developer layer forming member 2, a developer circulation regulation made of a non-magnetic material such as plastic is regulated. The member 5 is often provided.

In the above developer layer forming method, the developer is forcibly sandwiched between the developer layer forming member 2 and the developer carrying member 3 and rubbed, so that the developer can be efficiently charged. .

Therefore, there is an advantage that high-quality image output can be maintained for a long period of time, and in particular, the output image density and the background fog which are likely to occur after replenishment of the developer can be reduced.

Further, the developer is generated by the developer carrying member 3 and the magnetic field generating means 4 arranged inside the developer carrying member 3.
It is conveyed and thinned by the developer layer forming member 2. Then, the developer that has risen up to develop the electrostatic latent image is returned to the developing container 6 again.

The developer thus circulated and moved moves axially outward along the surface of the developer carrying member 3 and leaks to the outside of the bearing 9 or accumulates in the bearing 9 to accumulate in the bearing. The function is reduced, thereby hindering the smooth rotation of the developer carrier 3.

As described above, in the case of the developing device having the developer layer forming member 4 which is in pressure contact with the developer carrier 3, the developer leaks to the outside of the bearing 9 and the developer carrier 3 rotates smoothly. In order to prevent the inhibition of the above, conventionally, an end shield member 1'of an elastic body, a non-woven fabric or the like is provided at both ends of the developer carrying member, and a space between the peripheral surface of the developer carrying member 3 and the developing container inner side wall 6a is mechanically provided. It has been exclusively closed.

[0013]

However, in such a conventional structure, the end shield member 1'and the developer carrying member 3 are provided.
The developer invades between the peripheral surface and causes fusion and cohesion.

When the agglomerates are taken into the developer and caught by the developer layer forming member 2, white streaks in the circumferential direction on the developer layer (a portion where the background of the developer carrier is exposed) are caused. Sometimes (see FIG. 7).

Further, the fragments of the end shield member 1'generated by the rubbing against the developer carrying member 3 may cause the same adverse effect.

However, if the adhesion of the end shield member 1'with the developer carrying member 3 is increased for the purpose of improving the developer leakage preventing performance, a great stress is applied to the developer carrying member 3 and the developer is As a result, the driving load of the carrier 3 is increased.

The present invention has been made in order to solve the above problems, and an object of the present invention is to perform development capable of preventing the occurrence of white streaks in the circumferential direction without increasing the driving load of the developer carrying member. To provide a device.

[0018]

In order to achieve the above object, in the present invention, a magnetic field generating means is rotatably supported in a developing container containing a developer containing magnetic particles and has a magnetic field generating means inside thereof. A developer carrier that carries and conveys a developer. In a developing device having a developer layer forming member that is in pressure contact with the developer carrier, and magnetic shield members disposed at both ends of the developer carrier, the magnetic shield member is the developer carrier. Is arranged along the peripheral surface of at least a part of the developer carrying body with a predetermined gap with the peripheral surface of the developer carrying body, and magnetic field lines are also formed in the space by the magnetic field generating means arranged inside the developer carrying body. Thus, a magnetic brush made of a developer is formed along the lines of magnetic force.

The distance between the inner surface of the magnetic shield member and the end of the developer layer forming member is preferably 0.1 mm or less.

[0020]

In the present invention having the above-mentioned structure, the magnetic shield member is disposed along the peripheral surface of the developer carrying member along a peripheral surface of at least a part of the developer carrying member with a predetermined gap, and By forming a magnetic brush of the developer along the magnetic field lines so that magnetic field lines are also formed in the gap by the magnetic field generating means arranged inside the agent carrier, the magnetic shield member and the peripheral surface of the developer carrier are formed. It is possible to prevent the developer, the scraped pieces of the magnetic shield member, and the like from entering between them.

As a result, it is possible to prevent the generation of white stripes in the circumferential direction without applying a large driving load to the developer carrying member.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view best showing the features of the present invention, as viewed from a direction perpendicular to the rotation axis of a developer carrying member.

FIG. 2 is an enlarged view of a part of FIG.

The developer carrying member 3 has a rotary support shaft 3 at both ends thereof.
a, and is rotatably supported on the side wall 6a of the developing container 6 via a bearing 9.

With the above structure, the magnetic field generating means 4 disposed inside the developer carrying member 3 is rotated by the rotation of the developer carrying member 3.
The developer t drawn up by the drawing-up pole S2 is regulated by the developer layer forming member 2 to be a thin layer. Then, the developer that has risen up to develop the electrostatic latent image is returned to the developing container 6 again.

According to the present invention, the magnetic shield member 1 is arranged at the end of the developer carrier 3 in such a manner that the developer carrier 3 is surrounded by the surface of the developer carrier 3 and a predetermined gap g _1. 6 Attached to the side wall.

It has been found that the shielding ability is necessary and sufficient if the distance g ₂ between the inner surface 1a of the magnetic shielding member 1 and the end 2a of the developer layer forming member is 0.1 mm or less.

The magnetic shield member 1 is preferably made of a ferromagnetic material such as iron, nickel, cobalt or alloys thereof having a thickness t = 1 to 2 mm, and the developer carrier 3 is roughened. It should be formed with a width that covers the area that has not been exposed to light.

FIG. 3 is a view best showing the features of the present invention, and is seen from the direction of the rotation axis of the developer carrying member 3.

As can be seen from the figure, the magnetic shield member 1
Has an inner circumference and an outer circumference that form an arc concentric with the developer carrying member 3, and its central angle θ varies depending on the diameter of the developer carrying member 3, but it is easy to use 180 ° to 270 °.

Good results are obtained when the magnetic shield member 1 is formed so as to cover all magnetic poles except the developing pole of the magnetic field generating means 4 arranged inside the developer carrying member 3.

A protrusion 1b is provided on the lower portion of the magnetic shield member 1 and is fitted in the hole of the developing container 6. Further, it is fixed to the developing container 6 by a method such as sticking a double-sided tape on the outer peripheral surface.

In this embodiment having the above-mentioned structure, the magnetic shield member 1 is provided along the peripheral surface of the developer carrying member 3 and at least part of the peripheral surface of the developer carrying member 3 with a predetermined gap g _1. A magnetic brush is formed along the magnetic lines of force by the magnetic field generating means 4 arranged inside the developer carrying member 3 so that magnetic lines of force are also formed in the gap g ₁ and the magnetic shield is formed. It is possible to prevent the developer, sliding scraps of the magnetic shield member, and the like from entering between the member 1 and the peripheral surface of the developer carrier 3.

As a result, it is possible to prevent the occurrence of white stripes in the circumferential direction without applying a large driving load to the developer carrying member 3.

[0035]

As described above, according to the present invention,
The magnetic shield member is arranged along the peripheral surface of the developer carrier along a peripheral surface of at least a part of the developer carrier with a predetermined space, and a magnetic field is generated by the magnetic field generating means arranged inside the developer carrier. By forming a magnetic brush of the developer along the magnetic lines of force so that the magnetic lines of force are also formed, the developer and the rubbing debris of the magnetic shielding member between the magnetic shield member and the peripheral surface of the developer carrying member, etc. Are prevented from entering.

As a result, it is possible to prevent the occurrence of white stripes in the circumferential direction without applying a large driving load to the developer carrying member.

[Brief description of drawings]

FIG. 1 is a front view of a main part of a developing device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a side view of a main part of the apparatus.

FIG. 4 is a front view of a main part of a conventional developing device.

FIG. 5 is an enlarged view of a main part of FIG.

FIG. 6 is a side view of the main part of the apparatus.

FIG. 7 is a diagram illustrating a problem of the device.

[Explanation of symbols]

1 Magnetic Shielding Member 2 Developer Layer Forming Member 3 Developer Carrier 4 Magnetic Field Generating Means 6 Developer Container g ₁ Void

Claims (2)

[Claims] 1. A developer carrier for rotatably carried in a developer container containing a developer containing magnetic particles, and having a magnetic field generating means therein to carry and carry the developer on the surface. A developer layer forming member that comes into pressure contact with the developer carrying member, and magnetic shielding members disposed at both ends of the developer carrying member,
In the developing device having the above-mentioned magnetic shield member, the magnetic shield member is arranged along at least a part of the peripheral surface of the developer carrying body with a predetermined space between the magnetic carrier and the developer carrying body. A developing device, characterized in that magnetic field lines are formed in the gap by a magnetic field generating means disposed inside so that a magnetic brush made of a developer is formed along the magnetic field lines. 2. The distance between the inner surface of the magnetic shielding member and the end of the developer layer forming member is 0.1 mm or less.
The developing device described.