JP2000206791A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a magnetic developer from entering a gap between a magnet of an end sealing means provided at both ends of a developer carrying member and a developer carrying member, and to perform development. It is possible to stably produce good quality images for a long period of time without causing the formation of aggregates or fused materials of the agent, the contamination of the recording paper due to the overflow of these developing containers, and the contamination in the image forming apparatus. It is an object of the present invention to provide a developing device capable of obtaining the same. SOLUTION: A magnetic plate 3 which constitutes another end seal member provided at both ends of a developing sleeve is connected to an end portion of a developing container near an upstream N3 pole among repulsive magnetic poles of a magnet roller in the sleeve. The developer 8 that has been bent in the direction toward the end and pushed toward the end can be accommodated in front of the bent portion 3a. At this time, in order to allow the contained developer 8 to be constrained by a magnetic force, the bending portion 3a is bent so that the maximum value of the magnetic flux density of the magnetic force from the magnetic pole N3 exceeds 200 gauss. The dimensions of the part 3a were controlled.

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 carrier by electrophotography or electrostatic recording.

[0002]

2. Description of the Related Art Conventionally, there are various developing devices for developing an electrostatic latent image formed on an image carrier by an electrophotographic method or an electrostatic recording method using a one-component developer or a two-component developer. FIG. 5 shows a typical developing device.

The developing device 1 includes a developing container 2 containing a magnetic developer (two-component developer or one-component magnetic developer). In the developing container 2, a developer stirring and conveying screw separated by a partition 7 is provided. 5 and 6 are arranged. The developer in the developing container 2 is circulated by stirring and transporting the developer by the screws 5 and 6. The partition 7 is provided with developer passages (not shown) at the front and rear ends in the vertical direction of the paper surface of FIG.

An opening is provided in the developing container 2 at a position facing the photosensitive drum 100, and a developing sleeve 10 is rotatably mounted in the opening as a developer carrier in the direction of an arrow. The magnet roller 11 serving as a magnetic field generating means is non-rotatably arranged, and a regulating blade 13 made of a magnetic member is arranged substantially on the top of the developing sleeve 10. As shown in FIG. 6, the developing sleeve 10 has a rotating shaft 10 a supported on each side wall 2 a on both sides of the developing container 2 via a bearing 12.

The developer in the developing container 2 is pumped on the surface of the rotating developing sleeve 10 by the magnetic pole N2 of the magnet roller 11, and the pumped developer is transferred to the developing sleeve 1
By rotation of 0, S2 pole of magnet roller 11 → N1 pole → S
It is transported with one pole. In the transport process, the regulating blade 13
And is coated on the developer thin layer. Magnetic pole S1
Is a main developing pole, and the developer conveyed to the developing region where the S1 pole is located is raised by the magnetic force of the S1 pole to be formed on a magnetic brush. The electrostatic latent image formed on the surface of the drum 100 is developed.

After the development, the developer is supplied to the developing sleeve 10.
Is returned to the inside of the developing container 2 by the rotation of the magnet roller 11, and is dropped and collected from the developing sleeve 10 into the developing container 2 by the repelling magnetic field formed by the magnetic poles N3 and N2 of the magnet roller 11.

In the developing device having such a configuration, when the developer circulated in the developing container 2 is transferred to the bearing 12 along the surface of the developing sleeve 10, the developer is transferred to the bearing 12. , Or out of the container 2 or accumulates in the bearing 12 to reduce the function of the bearing, thereby hindering the smooth rotation of the developing sleeve 10.

In order to prevent such inconvenience, as shown in FIGS. 5 and 6, a magnetic plate is provided on the inside of the developing container 2 of the developing sleeve 10 so as to surround both ends of the developing sleeve 10. 3 and a magnet 4 are provided to constitute an end sealing means for sealing the developer with a magnetic brush of the developer.

[0009]

However, there are the following problems. FIG. 7 shows the developing sleeve 10.
FIG. 9 is a view showing the behavior of the developer near the magnetic pole N3 at the end of FIG.

The magnetic developer 8 conveyed from the lower side of FIG.
And fall off the developing sleeve 10 due to the repelling magnetic field between the N3 pole and the N2 pole. The transporting force of the developing sleeve 10 acts on the accumulated developer 8, and the developing sleeve 1
At the end of the developing roller 8, the developer 8 is pushed rightward, that is, toward the end of the developing container 2, and the developer 8 slightly passes over the magnetic plate 3, and the magnet 4 and the peripheral surface of the developing sleeve 10 Invade between. For this reason, when the developing device has been used for a long period of time, the developer is accumulated between the magnet 4 and the rotating developing sleeve 10, which may cause aggregation and further fusion.

The aggregates and the fused body of the developer may be taken in the developer 8 circulating in the developing container 2 again. When the aggregates and the fused body are large, the aggregated body and the fused body are taken in. The fused body stays in the portion of the regulating blade 13 and hinders the coating of the developer 8 on the developing sleeve 10, and as a result,
In some cases, white streaks were generated in the image.

When the aggregates and the fused body of the developer are small, the taken-in aggregates and the fused body are conveyed to the developing area in one place together with the developer 8 and subjected to the development, and are obtained by the development. At the time of transfer of the image, a transfer omission occurs around the aggregate and the fused body,
Particularly, in the case of a high-density image, a white spot-like image defect may occur, and the image quality may be significantly reduced.

Even if the aggregates and the fused body are not taken into the circulating developer 8 again, the aggregates and the fused body may be accumulated between the magnet 4 and the developing sleeve 10 due to long-term accumulation. If the amount exceeds the allowable amount that can be held in the gap, the toner overflows from the developing container 2 toward the photosensitive drum 100 and falls on a recording sheet below, causing image contamination or contaminating the inside of the image forming apparatus. Causes various inconveniences.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a magnetic developer from entering a gap between a magnet of an end sealing means provided at both ends of a developer carrying member and the developer carrying member so as to prevent development. It is possible to stably produce good quality images for a long period of time without causing the formation of aggregates or fused materials of the agent, the contamination of the recording paper due to the overflow of these developing containers, and the contamination in the image forming apparatus. It is an object of the present invention to provide a developing device which can obtain the developing device.

[0015]

The above object is achieved by a developing apparatus according to the present invention. In summary, the present invention provides a developer container in which a magnet is non-rotatably mounted at an opening of a developing container containing a magnetic developer, wherein the magnet is rotatably mounted on a portion other than the opening side. A magnetic plate is provided at least at a pair of repelling magnetic poles in a portion corresponding to the above, and a magnetic plate is arranged at both ends of the developer carrier so as to surround the surface of a portion other than the opening side of the developer carrier. A developing device in which a second magnet is disposed so as to surround a surface of a portion of the developer carrier that includes a region corresponding to the pair of repelling magnetic poles of the magnet; In the developing device, the magnetic plate is bent outward in the axial direction of the developer carrier near the magnetic pole on the upstream side in the rotation direction of the developer carrier. According to the present invention, preferably, the bent portion of the magnetic plate is located in a region where the maximum value of the magnetic flux density of the magnetic pole on the upstream side in the rotation direction exceeds 200 Gauss.

[0016]

Embodiments of the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the developing device of the present invention. A feature of the present invention is that the end sealing means of the developing device 1 is improved, and the basic configuration of the developing device itself is the same as that of the conventional developing device shown in FIG. This will be briefly described with reference to FIG.

As shown in FIG. 1, a developing device 1 includes a magnetic developer (a one-component magnetic developer (magnetic toner) in which resin is mixed with magnetic particles, or a magnetic carrier containing magnetic particles as a main component and a non-magnetic material). A developer agitating / conveying screws 5 and 6, which are separated by a partition 7 having a developer passage, are arranged in the developing container 2. The developer in the developing container 2 is circulated by the stirring and transport of the developer by the and.

At the opening of the developing container 2 facing the photosensitive drum 100, a developing sleeve 10 of a developer carrier is rotatably installed in the direction of an arrow, and a magnet roller 11 of a magnetic field generating means is non-rotatably disposed therein. In addition, a regulating blade 13 made of a magnetic member is disposed substantially on the top of the developing sleeve 10.

The developing sleeve 10 is, as shown in FIG.
The rotating shaft 10a is supported on each side wall 2a on both sides of the developing container 2 via a bearing 12, and the developing sleeve 10 is provided on the inner side of the developing container 2 so as to surround both ends of the developing sleeve 10. A magnetic plate 3 and a magnet 4 which constitute an end sealing member using a magnetic brush of the agent are provided.

The developer in the developing container 2 is pumped up by the magnetic pole N2 of the magnet roller 11 on the surface of the rotating developing sleeve 10, and the pumped up developer is
By rotation of 0, S2 pole of magnet roller 11 → N1 pole → S
It is transported with one pole. In the transport process, the regulating blade 13
And is coated on the developer thin layer. The developer transported to the development area where the S1 pole of the main development pole is located is
Ears are formed by the magnetic force of the S1 pole and are formed on the magnetic brush,
The electrostatic latent image formed on the surface of the photosensitive drum 100 is developed by contacting the photosensitive drum 100.

After the development, the developer is supplied to the developing sleeve 10.
Is returned to the inside of the developing container 2 by the rotation of the magnet roller 11, and is dropped and collected from the developing sleeve 10 into the developing container 2 by the repulsive magnetic field of the magnetic poles N3 and N2 of the magnet roller 11.

In the developing device having such a configuration, when the developer circulated in the developing container 2 is transferred to the bearing 12 along the surface of the developing sleeve 10, the developer is transferred to the portion of the bearing 12. , Or out of the container 2 or accumulates in the bearing 12 to reduce the function of the bearing, thereby hindering the smooth rotation of the developing sleeve 10.

Therefore, in order to prevent such inconvenience, as described above, the magnetic plate 3 and the magnet 4 are provided, and an end sealing means for sealing the developer with a magnetic brush of the developer is constituted. I have.

The magnetic plate 3 is provided at both ends of the developing sleeve 10 so as to surround the surface of the portion of the developing sleeve 10 other than the opening of the developing container 2 with a gap g1 from the developing sleeve 10. Attached to the side wall 2a.

The magnetic plate 3 is preferably formed of a ferromagnetic material such as iron, nickel, cobalt or an alloy thereof, and has a thickness of about 0.2 to 1 mm. The gap g1 between the magnetic plate 3 and the developing sleeve 10 is not limited, but is selected as desired within a range of 0.3 to 2 mm.

In this embodiment, the magnetic plate 3 is formed as a plate having a concentric annular portion at a distance w from the center of the developing sleeve 10, but the shape of the magnetic plate 3 is not limited to this. Any shape can be used as long as it can be arranged in a non-contact state with a constant gap g1 along the peripheral surface of.

By arranging the magnetic plates 3 at both ends of the developing sleeve 3 as described above, the magnetic plate 3 is magnetized by the magnetic force of the magnet roller 11 in the developing sleeve 10 and the magnet roller 11 and the magnetic plate 3 And a magnetic brush of developer is formed in the gap g1 between the magnetic plate 3 and the developing roller 10. Thereby, the developing sleeve 10
Is stopped at the gap g1 and is prevented from entering the bearing 12 through the gap g1 to prevent the developer from flowing out of the developing container 2.

Further, in the magnetic pole arrangement as in the present embodiment, the magnetic brush of the developer formed in the gap g1 is applied to the gap g1 particularly in the portion adjacent to the portion where the repelling magnetic field is formed between the N3 pole and the N2 pole. , Tend to be weaker than other parts. Therefore, as described above, the magnet 4 is disposed near the magnetic plate 3 as an auxiliary seal member.

The magnet 4 is spaced apart from the developing sleeve 10 by a predetermined gap g2 at both ends of the developing sleeve 10 so as to surround the surface of a region including a region facing the N3 pole and the N2 pole of the developing sleeve 10. Is arranged. This magnet 4
Captures the developer in the gap g2 and forms a magnetic brush of the developer in the gap g2. At the end of the developing sleeve 10, the developer is transferred from the region between the N3 pole and the N2 pole to the gap g2. The developer is prevented from entering, and the developer is prevented from flowing out of the developing container 2.

However, the magnetic developer 8 conveyed from the lower side of FIG.
Due to the repulsive magnetic field between the N3 pole and the N2 pole of the magnet roller 11, the magnet roller 11 drops from the developing sleeve 10 and stays there, and the conveying force of the developing sleeve 10 acts on the staying developer 8;
At the end of the developing sleeve 10, the developer 8 is pushed rightward, that is, toward the end of the developing container 2, and the developer 8 slightly tries to pass over the magnetic plate 3.

As a countermeasure, in the present invention, as shown in FIG. 3, the magnetic plate 3 is bent in the direction toward the end of the developing container 2 near the N3 pole, and the developer extruded toward the end of the developing container 2 is bent. 8 can be accommodated in front of the bent portion 3a.
Since the magnet 4 was bent, the lower end of the magnet 4 was cut off in accordance with the bent portion 3a in order to eliminate interference with the bent portion 3a.

The bending dimension of the bent portion 3a is preferably set such that the magnetic force from the magnetic pole N3 is applied to the bent portion 3a so that the developer 8 accommodated in front of the bent portion 3a can be restrained by the magnetic force. Preferably, control is achieved. Specifically, it is preferable that the bent portion 3a be located in a region where the maximum value of the magnetic flux density of the magnetic force from the magnetic pole N3 exceeds 200 Gauss.

In this embodiment, the bent portion 3a of the magnetic plate 3 is
As shown in FIG. 3, the amount x of protrusion of the bent portion 3a outward from the magnetic plate 3 was 2 mm, and the vertical distance y of the lower end was 4 mm.

The bending dimensions x, y, and the shape of the bent portion 3a can be appropriately selected according to the specific configuration of each developing device.

According to the present invention, since the tip of the magnetic plate 3 is bent toward the end of the developing container 2 as the bent portion 3a, even if the developer 8 is pushed out toward the end, As shown in FIG. 4, the developer 8 can be accommodated in front of the bent portion 3a of the magnetic plate 3 so as not to go outside the magnetic plate 3,
The extruded developer 8 can be kept stopped in the developing container 2.

Therefore, the extruded developer 8 does not enter the gap g2 between the magnet 4 and the peripheral surface of the developing sleeve 10, and does not cause aggregation or fusion between them. No agglomerates or fused bodies of the developer are generated. Therefore, the aggregates and the fused body of the developer are not mixed with the developer circulating in the developing container 2, the transfer missing on the image and the white stripe are not generated, and the aggregates and the fused body are not generated. Does not overflow from the developing container 2 in the direction of the photosensitive drum 100 and fall onto the recording paper below, thereby causing stains on the image and not contaminating the inside of the image forming apparatus.

[0038]

As described above, according to the present invention,
The magnetic plate constituting the end sealing means provided at both ends of the developer carrier is placed near the magnetic pole on the upstream side in the developer carrier rotation direction among the pair of repulsive magnetic poles of the magnet in the developer carrier. Since the developer is bent outward in the axial direction of the developer carrier, the magnetic developer that has fallen from the developer carrier due to the repelling magnetic field and stays there is pushed out toward the end of the developing container by the conveying force of the developer carrier. However, the developer can be contained in front of the bent portion of the magnetic plate and can be prevented from passing over the magnetic plate, and the developer can be stored in the gap between the magnet forming the end seal member and the developer carrier. Intrusion can be prevented. Therefore, the coagulation and fusion of the developer do not occur, the recording paper is not stained by the overflow from the developing container, and the contamination in the image forming apparatus does not occur. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a developing device of the present invention.

FIG. 2 is a sectional view showing the vicinity of an end of a developing sleeve of the developing device of FIG. 1;

FIG. 3 is an explanatory diagram showing dimensions of a bent portion of a magnetic plate provided at an end of the developing sleeve of FIG. 2;

FIG. 4 is an explanatory diagram showing a behavior of a magnetic developer at an end of a developing sleeve in FIG. 2;

FIG. 5 is a cross-sectional view illustrating a conventional developing device.

6 is a cross-sectional view showing the vicinity of an end of a developing sleeve of the developing device of FIG.

FIG. 7 is an explanatory diagram showing the behavior of the magnetic developer at the end of the developing sleeve in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing device 2 Developing container 2a Side wall 3 Magnetic plate 3a Bending part 4 Magnet 8 Magnetic developer 10 Developing sleeve 11 Magnet roller

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Fumitake Hirobe 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H031 AC19 AC20 AC40 AE01 BA03 BA04

Claims (2)

[Claims] 1. A developer carrier having a non-rotating magnet is installed in an opening of a developing container containing a magnetic developer so as to be rotatable. The magnet corresponds to a portion other than the opening. A magnetic plate having at least a pair of repelling magnetic poles in a portion, and a magnetic plate disposed at both ends of the developer carrier so as to surround a surface of a portion other than the opening side of the developer carrier; In a developing device in which a second magnet is arranged so as to surround a surface of a portion of the developer carrying member that includes a region corresponding to the pair of repelling magnetic poles of the magnet, the developer carrying member of the pair of repelling magnetic poles is provided. A developing device characterized in that the magnetic plate is bent outward in the axial direction of the developer carrier near the magnetic pole on the upstream side in the rotation direction of the body. 2. The developing device according to claim 1, wherein the bent portion of the magnetic plate is located in a region where the maximum value of the magnetic flux density of the magnetic pole on the upstream side in the rotation direction exceeds 200 Gauss.