JPH10240013A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of stably obtaining a high- quality image over a long term by preventing the fusion and the aggregate of developer and preventing the soiling of the image and contamination in an image forming device. SOLUTION: This developing device has a developer carrier 10 having a developer container in which developer including magnetic particles is stored and a magnetic field generating means provided at the aperture part of the developer container and forming repulsive magnetic field inside and rotating while carrying the developer, and a magnet (magnetic member) 25 disposed at the end of the developer carrier 10 with a specified gap at least at a part on the peripheral surface of the developer carrier. In such a case, the direction (a) of the magnetic flux of the magnetic field formed on the magnet 25 has a specified tilt angle θ to the rotating direction (b) of the developer carrier 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device for developing an electrostatic latent image formed on an image carrier by electrophotography or electrostatic recording.

[0002]

2. Description of the Related Art An electrostatic latent image formed on an image carrier by an electrophotographic system or an electrostatic recording system is formed by a one-component developer or a two-component developer.
Various types of developing devices for developing using a component developer have been conventionally proposed, and typical ones are shown in FIGS.

FIG. 4 is a sectional view of a conventional developing device 1.
FIG. 5 is a partially enlarged sectional view of an end portion of the developing device 1. The developing device 1 includes a developing container 2, and screws 4 and 6 are provided in the developing container 2. , 6 recirculates the developer 8 in the developing container 2.

The developing device 1 has a developer carrier 10 at an opening of the developing container 2. The developing device 1 has a developing device 10 for developing an electrostatic latent image formed on the image carrier 100. The developer 8 is transported to the image carrier 100 by the developer carrier 10. Usually, the developer carrier 10 includes a magnetized fixed magnet roller 10a and a developing sleeve 10b rotatably mounted around the magnet roller 10a in a direction indicated by an arrow in the figure. As shown in FIG. 5, the developing sleeve 10b has a shaft 10c rotatably supported on both side walls 2a (only one side wall 2a is shown in FIG. 5) of the developing container 2 via a bearing 12. I have.

[0005] In Thus, the developer 8 drawn up by N ₂ poles by rotation of the developing sleeve 10b is S _2-pole → N ₁ pole →
The developer is conveyed to the S ₁ pole, and its thickness is regulated by the regulating blade 30 to form a thin developer layer. Here, S ₁ pole is a developing main pole, the developer 8 napped in the S ₁ pole develops the electrostatic latent image on the image bearing member 100, then, the developer 8 on the developing sleeve 10b is It falls into the developing container 2 by the repulsive magnetic poles of the N ₃ pole and the N ₂ pole.

By the way, the developing device 1 having the above configuration
As described above, the developer 8 circulating in the developing container 2 as described above is transferred to the bearing 12 along the surface of the developing sleeve 10b, and flows out of the developing container 2 through the bearing 12. Or accumulate in the bearing 12
Therefore, the smooth rotation of the developing sleeve 10b becomes impossible.

Therefore, as shown in FIGS. 4 and 5, a plate-like magnetic member 21 forming a magnetic brush at both ends of the developing sleeve 10b and a sealing means for the developer 8 such as a magnet 25 are provided around the developing sleeve 10b. It is provided to cover.

[0008]

In the conventional developing device 1 shown in FIGS. 4 and 5, the developer 8 slightly enters between the magnet 25 and the peripheral surface of the developing sleeve 10b. This developer 8 is captured by the magnetic force of the magnet 25. Therefore, when the developing device 1 has been used for a long period of time, the captured and accumulated developer 8 may cause fusion or aggregation between the magnet 25 and the rotating developing sleeve 10b.

Thus, a part of the fused body or the aggregate of the developer 8 may be taken in the circulating developer 8 again, and when such a fused body or the aggregate is large, In some cases, these stagnate in the regulating blade 30 portion, hinder the coating of the developer 8 on the developing sleeve 10b, and generate white stripes on the image in some cases.

When the fused body or aggregate of the developer 8 is small, the fused body or aggregate is developed together with the developer 8, and particularly when a high density image is formed, the developed body is not developed. In some cases, transfer loss occurs mainly on the fused body or aggregate, and white spot-like defects occur on the image, resulting in a significant decrease in image quality.

Further, even if the fused material or aggregate of the developer 8 is not taken in the circulating developer 8 again, the fused material or aggregate accumulated over a long period of time is not If the amount exceeds the allowable amount that can be held in the gap between the developing sleeve 10 and the developing sleeve 10, they overflow from the developing container 2 in the direction of the image carrier 100 and fall on the recording paper, resulting in image contamination. In addition, various problems such as contamination of the inside of the image forming apparatus may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent generation of a fused or aggregated developer and prevent image contamination and contamination in an image forming apparatus. An object of the present invention is to provide a developing device capable of stably obtaining a quality image for a long period of time.

[0013]

In order to achieve the above object, the invention according to claim 1 provides a developing container for containing a developer containing magnetic particles, and a developing container provided at an opening of the developing container to generate a repulsive magnetic field. A developer carrying member which has a magnetic field generating means formed therein and carries and rotates the developer, and is disposed at an end of the developer carrying member with a predetermined gap at least at a part of a peripheral surface of the developer carrying member. In the developing device having the provided magnetic member,
It is characterized in that the direction of the lines of magnetic force of the magnetic field formed on the magnetic member has a predetermined inclination angle with respect to the rotation direction of the developer carrying member.

According to a second aspect of the present invention, in the first aspect, the magnetic member is a multi-pole magnetized magnet in which N poles and S poles are alternately arranged on a surface facing the developer carrier. The magnetic poles are arranged so that the direction of arrangement of the magnetic poles has a predetermined inclination angle with respect to the rotation direction of the developer carrying member.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the inclination angle is set to an acute angle in a direction inclining toward the inside of the developing container toward a rotation direction downstream of the developer carrier. It is characterized by setting.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, at least a part of the magnetic member is configured to reduce a repulsive magnetic field of the magnetic field generating means with respect to a peripheral surface of the developer carrier. It is characterized in that it is arranged at a position facing a region to be formed.

The fifth aspect of the present invention provides the first, second, and third aspects.
Alternatively, in the invention described in Item 4, the developer is a two-component developer including a magnetic carrier and a toner.

The invention according to claim 6 is the invention according to claims 1, 2, 3
Alternatively, in the invention described in Item 4, the developer is a one-component developer composed of a magnetic toner.

[0019]

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

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention, FIG. 2 is an enlarged partial sectional view of an end of the developing device, and FIG. 3 is a developed view of an end magnet of the developing device.

The developing device 1 according to the present embodiment is provided in a color image forming apparatus. The developing device 1 includes a developer (a one-component magnetic developer in which magnetic particles are kneaded with a resin or a main component comprising magnetic particles). Developer container 2 containing a two-component developer in which a magnetic carrier and a toner are mixed.
Screws 4 and 6 for circulating the developer (not shown) in the developing container 2 are provided in the developing container 2.

The developing device 1 has a developer carrier 10, and the developer in the developing container 2 is used to develop an electrostatic latent image formed on the image carrier 100. By 10, it is conveyed in the direction of the image carrier 100. The developer carrier 10 has a fixed magnet roller 10a that is magnetized.
And a developing sleeve 10b which is rotatably mounted around the magnet roller 10a in the direction of the arrow and transports the developer toward the image carrier 100. The developing sleeve 10b has a shaft 10c as shown in FIG.
Are rotatably supported on both side walls 2a (only one side wall 2a is shown in FIG. 2) of the developing container 2 via a bearing 12.

As shown in FIG. 2, a plate-like magnetic member 21 surrounding the developing sleeve 10b is attached to the side wall 2a of the developing container 2. The magnetic member 21 is preferably made of a ferromagnetic material such as an iron plate, a nickel plate, a cobalt plate, or an alloy plate thereof having a thickness (t) of about 0.2 to 1 mm. The gap (g1) between the magnetic member 21 and the developing sleeve 10b is not particularly limited, but is appropriately set in the range of 0.3 to 2 mm.

In the present embodiment, the magnetic member 21 is formed into an annular shape having the same width (w) as that of the developing sleeve 10b, and a uniform gap (between the magnetic member 21 and the outer periphery of the developing sleeve 10b). g1), but the magnetic member 21
Is not limited to the shape shown in the drawing, and may have various shapes as desired as long as the magnetic member 21 is arranged along the peripheral surface of the developing sleeve 10b in a non-contact state. be able to. The angle formed by the side surface of the magnetic member 21 with respect to the normal to the peripheral surface of the developing sleeve 10b is preferably 45 ° or less from the viewpoint of more reliably preventing the outflow of the developer. Further, the magnetic member 21 is preferably disposed over the entire peripheral surface of the developing sleeve 10b. However, as shown in FIG. 1, the magnetic member 21 is partially disposed within the range of the developing container 2. Has a sufficient effect.

As described above, by disposing the magnetic members 21 on both sides of the developing sleeve 10b, the developing sleeve 10b is provided.
b, the magnetic member 21 is magnetized by the magnetic force of the magnet roller 10a provided therein, and a magnetic circuit is formed between the magnet roller 10a and the magnetic member 21 to form a gap between the magnetic member 21 and the developing sleeve 10b. A magnetic brush made of the developer is formed in the portion (g1). The magnetic brush functions to prevent the developer from entering the bearing 12 through the gap between the side wall 2a of the current container 2 and the surface of the developing sleeve 10b along the developing sleeve 10b. That is, the magnetic member 21
The magnetic brush made of the developer formed in the gap (g1) between the developing sleeve 10b and the developing sleeve 10b functions as an end seal for preventing the developer from flowing out of the developing container 2.

The developer pumped at the N ₂ pole by the rotation of the developing sleeve 10b is changed from the S ₂ pole → the N ₁ pole → S
_The developer is transported as _one pole, and the thickness of the developer is regulated by the regulating blade 30 to form a thin developer layer. Here, S ₁ pole is a developing main pole, developer ears in this S ₁ pole develops the electrostatic latent image on the image bearing member 100, then, the developer on the developing sleeve 10b is N ₃ It falls into the developing container 2 by the repelling magnetic poles of the pole and the N ₂ pole.

In the magnetic pole arrangement of the magnet roller 10a of the developer carrier 10 in the developing device 1 according to the present embodiment, in particular, a gap (g1) adjacent to the repulsive magnetic field forming portion between the N ₃ pole and the N ₂ pole. , The magnetic brush formation by the developer tends to be weaker than others. Therefore, N ₃ pole and N
_In a region opposed between the _two poles, a magnet 25 as an auxiliary seal member is provided near the magnetic member 21 with a predetermined gap (g2) with respect to the developing sleeve 10b. As shown in a developed view of FIG. 3, the magnet 25 is formed of a multipolar magnetized magnet in which N poles and S poles are alternately magnetized on a surface facing the developing sleeve 10b.

The developer caught by the magnet 25 forms a magnetic brush in the gap (g2), and prevents the developer that has entered the region between the N ₃ pole and the N ₂ pole from flowing out. Functions as an end seal for blocking.

The magnet 25 is arranged at an inclination angle (θ) such that the arrangement direction (a) of the magnetic poles is inclined inward of the developing container 2 with respect to the rotation direction (b) of the developing sleeve 10b. Therefore, the movement of the developer captured by the magnet 25 in the gap (g2) is restricted mainly by magnetic lines of force between the N pole and the S pole formed in the width direction (c) of the magnetic pole. Under such circumstances, the developer trapped in the gap (g2) causes the rubbing force (F) due to the rotation of the developing sleeve 10b.
b), the component force (Fc) in the width direction (c) of the magnetic pole is canceled by the line of magnetic force of the magnet 25, and the component force (F) in the arrangement direction (a) of the magnetic poles is derived.
Only a) will act, and the developer will receive a conveying force in the direction of pushing back again into the developing container 2 along the magnetic pole arrangement.

Therefore, the developer that has entered the gap (g2) between the magnet 25 and the developing sleeve 10b does not stagnate and accumulate in the gap (g2) due to the conveying force (Fa) along the magnetic pole arrangement. Since the developer is quickly pushed back into the developing container 2, it is possible to prevent the formation of a fused or aggregated developer.

In the present embodiment, the magnet 25 is formed of, for example, a sheet-like rubber magnet obtained by kneading ferrite magnetic powder and rubber. However, if the magnet 25 is formed of a material having a high elasticity, the present embodiment will be described. Since the magnet 25 can be easily disposed on the developing container 2 having the curvature surface as in the above embodiment, it is also possible to form various magnetized patterns according to the use with high accuracy. The configuration according to the present embodiment can be realized relatively inexpensively.

In the magnet 25, an appropriate transfer force (F
In order to generate a), the inclination angle (θ) of the magnetic pole is 10 °.
The angle should be set to an acute angle of about 60 °, the magnetic pole pitch (p) should be set to a range of about 1 to 5 mm, and the shape of the magnet 25 should be the magnetic pole arrangement of the developing sleeve 10a, the magnetic flux density. It is preferable to select an appropriate one according to conditions such as the outer diameter and the like.

Further, the gap (g2) between the magnet 25 and the developing sleeve 10b is not limited, but at least the vertex of the developer rising on the magnet 25 comes into contact with the outer periphery of the developing sleeve 10b to perform development. It is preferable that the amount is set in the range of 0.3 to 2 mm as a degree to which the agent can receive the rubbing force (Fb).

The magnet 25 may be provided over the entire peripheral surface of the developing sleeve 10b, but as shown in FIG.
A sufficient effect can be obtained even if the magnetic member 21 is at least partially disposed in the range of the developing container 2 so as to face the region where the magnetic member 21 is weakly formed by the magnetic member 21 near the formation of the repulsive magnetic field between the N ₃ and N ₂ poles. Is obtained.

[0035]

As is apparent from the above description, according to the present invention, a developing container containing a developer containing magnetic particles,
A developer carrier that is provided at an opening of the developing container and has a magnetic field generating means for forming a repulsive magnetic field therein and that rotates while carrying the developer; and a developer carrier at an end of the developer carrier. In a developing device having a magnetic member disposed with a predetermined gap in at least a part of a body peripheral surface, a direction of a magnetic field line of a magnetic field formed on the magnetic member is a predetermined direction with respect to a rotation direction of the developer carrying member. Because of the configuration having the inclination angle, the generation of a fused body or an agglomerate of the developer can be prevented, the image stain and the contamination in the image forming apparatus can be prevented, and a high-quality image can be stably obtained for a long period of time. .

[Brief description of the drawings]

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

FIG. 2 is an enlarged partial cross-sectional view of an end of a developing device according to the embodiment of the present invention.

FIG. 3 is a development view of an end magnet of the developing device according to the embodiment of the present invention.

FIG. 4 is a sectional view of a conventional developing device.

FIG. 5 is a partially enlarged cross-sectional view of an end of a conventional developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing device 2 Developing container 10 Developer carrier 10a Magnet roller (magnetic field generating means) 10b Developing sleeve 21 Magnetic member 25 Magnet (magnetic member)

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumitake Hirobe 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (6)

[Claims] 1. A developing container containing a developer containing magnetic particles, and a magnetic field generating means provided at an opening of the developing container for generating a repulsive magnetic field, and rotatably carries the developer. A developing device having a developer carrying member and a magnetic member disposed at an end portion of the developer carrying member at a predetermined gap in at least a part of a peripheral surface of the developer carrying member, wherein the developing device is formed on the magnetic member A developing device, wherein a direction of a magnetic field line of a magnetic field has a predetermined inclination angle with respect to a rotation direction of a developer carrying member. 2. The multi-pole magnet according to claim 1, wherein said magnetic member is a multi-pole magnetized magnet in which N poles and S poles are alternately arranged on a surface facing said developer carrier. 2. The developing device according to claim 1, wherein the developing device has a predetermined inclination angle with respect to the rotation direction of the developer carrier. 3. The developing device according to claim 1, wherein the inclination angle is set to an acute angle in a direction inclined inward of the developing container toward a downstream side in a rotation direction of the developer carrier. apparatus. 4. The magnetic member according to claim 1, wherein at least a part of the magnetic member is disposed at a position facing a region of the magnetic field generating unit where a repulsive magnetic field is formed. The developing device according to claim 1. 5. The developer according to claim 1, wherein the developer is a two-component developer comprising a magnetic carrier and a toner.
5. The developing device according to 3 or 4. 6. The developing device according to claim 1, wherein the developer is a one-component developer composed of a magnetic toner.