JPH05289519A - Developing device - Google Patents

Abstract

PURPOSE:To prevent developer from being leaked to the outside of a developing device without causing the sticking of the developer in the vicinity of the peripheral surface of a cylindrical sleeve and the increase of driving torque in the developing device which is provided with the cylindrical sleeve which approaches to be opposed to an electrostatic latent image holding body where a latent image by the difference of electrostatic charging potential is formed and transfers the developer adhering to the surface of the sleeve on the electrostatic latent image holding body so as to visualize an image. CONSTITUTION:A 1st side seal magnet 3 is provided near both ends in the shaft direction of the sleeve 1 in the peripheral direction inside the sleeve 1. On the outside of the sleeve 1, a 2nd side seal magnet 4 is provided at a position where it is opposed to the 1st magnet 3 so that it may approach and separate along the outer peripheral surface of the sleeve 1. The 1st and the 2nd magnets 3 and 4 have N and S poles in the radial direction of the cylindrical sleeve 1 and are magnetized so that repulsive magnetic poles may be opposed to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device which is used in an image forming apparatus such as an electrophotographic copying machine or a printer and which makes a developer adhere to an electrostatic latent image for visualization.

[0002]

2. Description of the Related Art Conventionally, a developing device shown in FIG. 5, for example, is known as a developing device which visualizes an electrostatic latent image by attaching a developer thereto. The electrostatic latent image holder 117 is capable of forming an electrostatic latent image due to a difference in charging potential by irradiating image light after being uniformly charged. The developing device is provided so as to face the electrostatic latent image holding member 117, and is in the housing 116 so as to face the electrostatic latent image holding member 117 in close proximity to the surface of the developing device so that the developer can be adsorbed and conveyed. A developer carrier 118, a developer regulating member 105 that regulates the amount of developer on the developer carrier 118 to form a thin layer of developer, and a developer that is supplied to the developer carrier 118 while stirring. The agent supply member 115 is included. Further, in the housing 116, the first member is provided along the developer supplying member 115.
The developer stirring chamber 109 and the partition wall 113 of the first
And a second developer stirring chamber 110 that is partitioned from the first developer stirring chamber 109.
The second developer stirring chamber 110 has a first screw auger 111 and a second screw auger 112 that convey the developer while stirring.

The developer carrying member 118 is provided inside with a magnet roll 102 in which a plurality of magnets are arranged in a fixed position, and a cylindrical sleeve 101 is rotatably supported on the outside thereof. The developer is attracted to the surface of the sleeve 101 by the magnetic force of the magnet roll, and is conveyed by the rotation of the sleeve. The first screw auger 111 and the second screw auger 11
Reference numeral 2 respectively conveys the developer in the opposite direction, and stirs the developer in the first developer stirring chamber 109 and the second developer stirring chamber 110 which are partitioned by the partition wall 113 and communicate with each other at both ends. While being transported, it is circulated in a fixed direction.

In such a developing device, the developer agitated in the first developer agitating chamber 109 and the second developer agitating chamber 110 is supplied to the surface of the developer carrier 118 by the developer supplying member 115. To be done. The developer adsorbed on the surface of the developer carrier 118 is regulated by the developer regulation member 105 to form a uniform thin layer, and the sleeve 101 of the developer carrier 118 rotates, so that the developer carrier 118 and the electrostatic latent image. It is conveyed to the developing area A, which is close to and faces the holder 117. In the developing area A, a bias voltage is applied between the developer carrying member 118 and the electrostatic latent image holding member 117, and the oscillating electric field generated here causes the developer to adhere to the electrostatic latent image to perform development. Be done.

In the developing device as described above, the housing 116 is opened in order to make the developer carrying member 118 face the electrostatic latent image holding member 117, and the developing agent is developed near both axial ends of the developer carrying member. It is necessary to prevent the developer from leaking out of the housing 116 through the gap between the agent carrier 118 and the housing 116. In order to prevent this developer leakage, generally, an elastic sealing material made of urethane, felt, or the like is brought into contact with both the developer carrying member 118 and the housing 116 so as to close the gap.

However, since the above-mentioned elastic seal material is constantly in contact with the surface of the circulating developer carrier, there are problems such as temperature rise due to friction and increase in driving torque of the developer carrier due to friction. .. Therefore, a developing device has been proposed in which magnetic force is used to seal the developer so as not to apply a load on the peripheral surface of the developer carrier. As such a developing device, for example, Japanese Utility Model Publication No. 62-143968 and Japanese Utility Model Publication No.
There is one disclosed in Japanese Patent Publication No. 3-60168.

In the developing device disclosed in Japanese Utility Model Laid-Open No. 62-143968, a magnetic material is provided on the inner surface of the side seal member which covers a part of the peripheral surface of the end portion of the developer carrier.
A magnetic field is formed between the magnetic body and the magnet fixed inside the developer carrying body. The magnetic developer is restrained by the magnetic force in the magnetic field, and leakage to the outside of the developing device is prevented. Also,
In the developing device disclosed in Japanese Utility Model Laid-Open No. 63-60168, as shown in FIG.
01 and the developer carrying member 218 provided with 01 are provided with non-contact arc magnets 203 for sealing along the peripheral surface. This seal magnet 20
N and S poles 3 are magnetized in parallel with the axis of the developer carrier 201, and form a magnetic field near the surface of the sleeve 201 via the magnetic body 220. The magnetic developer is restrained in this magnetic field, and leakage to the outside of the developing device is prevented.

[0008]

However, the developing device as described above has the following problems. In the developing device disclosed in Japanese Utility Model Laid-Open No. 62-143968, the developer enters and condenses between the developer carrying member and the magnetic members facing each other at the peripheral surfaces of both ends thereof. Further, the surface of the developer carrying member is rubbed by the rotation and fixed by frictional heat to increase the driving load of the developer carrying member. Also, the actual development 6
In the developing device disclosed in Japanese Laid-Open Patent Publication No. 3-60618, the sealing magnet 20 to which the magnetic bodies 220 and 220 are mounted is used.
3, a magnetic field as shown in FIG. 7A is generated near the surface of the sleeve, and the magnetic developer is adsorbed by following the direction of the magnetic force lines. Therefore, as shown in FIG. 7B, the developer is deposited between the magnetic body 220 and the sleeve 201, and is constantly in contact with the sleeve 201 and the magnetic body 220 to be fixed by frictional heat when the sleeve 201 rotates. Cause When this becomes severe, the surface of the sleeve 201 or the electrostatic latent image holder 2
This may damage the surface of 17 or cause a bias leak. Further, if the developer is fixed between the sleeve 201 and the magnetic body 220, there is a problem that the driving load of the sleeve 201 is increased, and the rotation speed varies or stops.

The present invention has been made in view of the above problems, and provides a developing device capable of preventing leakage of a developer without causing condensation or sticking of the developer. With the goal.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a non-magnetic cylindrical shape which is rotatably supported and closely faces an electrostatic latent image carrier. In a developing device including a sleeve and a magnet roll having a plurality of magnetic poles, which is located inside the sleeve, a first roller provided along the circumferential direction on the surface near the both ends in the axial direction of the sleeve or inside the sleeve. Side seal magnets,
An outer peripheral surface of the sleeve, which faces the first side seal magnet, and a second side seal magnet which is provided closely spaced along the peripheral surface of the sleeve,
The first side seal magnet and the second side seal magnet both have an N pole and an S pole in a radial direction of a cylindrical sleeve, and are supported so that mutually repulsive poles face each other. To do.

The above-mentioned first side seal magnet may be arranged either on the surface of the sleeve or on the inside thereof, and even if it is supported so as to rotate together with the sleeve, it is fixedly supported so as not to rotate. But it's okay. Second above
The side seal magnet is fixedly supported at a position facing the first side seal magnet, and is supported in a non-contact manner with the sleeve and a member rotating together with the sleeve. The fixedly supported first side seal magnet and second fixed side seal magnet may be provided in a range where it is necessary to prevent leakage of the developer on the outer peripheral portion of the developer carrier. For example, it can be from the vicinity of the entrance to the housing to the vicinity of the position where the developer regulating member is provided in the rotation direction of the developer carrier, which is partially exposed outside the housing. Further, when the first side seal magnet is mounted so as to rotate together with the sleeve, the first side seal magnet is provided in the entire area of the developer carrying member in the circumferential direction. The first side seal magnet and the second side seal magnet are integrally formed as long as the S pole and the N pole are magnetized in the radial direction at any position in the circumferential direction of the sleeve. It may be a magnet or a combination of a plurality of magnets. It is desirable that the gap between the second side seal magnet and the peripheral surface of the sleeve be even in the circumferential direction and be in the range of 0.2 to 2 mm.

[0012]

In the developing device having the above-mentioned structure, the first side seal magnet and the second side seal magnet, which are provided close to each other in the vicinity of both ends in the axial direction of the sleeve, are provided with the radius of the cylindrical sleeve. Since there are N poles and S poles in the direction and the repulsive poles are supported so as to face each other,
The developer does not enter the magnetic field where the magnetic lines of force of the two magnets repel, but concentrates in the vicinity of the corners of the first side seal magnet and the second side seal magnet according to the lines of magnetic force connecting the N pole and S pole of each magnet. And be adsorbed. In addition, the developer adsorbed on the first side seal magnet and the developer adsorbed on the second side seal magnet repel between the two magnets, and the developer is absorbed near both ends in the axial direction of the sleeve. Prevents condensation. Therefore, the developer is prevented from leaking out of the developing device due to the magnetic field repelled by the magnetic lines of force between the first side seal magnet and the second side seal magnet, and the developer is prevented from leaking from the gap between the side seal magnets. Stable development is performed without condensation or sticking.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are schematic cross-sectional views showing the structure of a developing device according to a first embodiment of the present invention. FIG. 1A is a line II-II shown in FIG. 1B, and FIG. ) A sectional view taken along the line I-I shown in the drawing. This developing device is provided in a housing 16 for accommodating a developer so as to face the electrostatic latent image holding member 17, and a developer carrier 18 capable of adsorbing and transporting the developer on the surface thereof. A developer regulating member 5 that regulates the amount of developer on the agent carrier 18 to form a thin layer of developer.
A developer supply member 15 for supplying a developer to the surface of the developer carrier 18, a first side seal magnet 3 arranged along the peripheral surface at both ends of the developer carrier, and a developer. It has a second side seal magnet 4 supported at a position facing the first side seal magnet from the outside of the carrier. Further, a first developer stirring chamber 9 is provided in a position adjacent to the developer supply member 15 in the housing 16, and a second developing device partitioned by the partition wall 13 and the first developer stirring chamber 9 is provided. An agent stirring chamber 10 is provided.

The electrostatic latent image carrier 17 is an organic photoconductor, S
An e-type photosensitive member or the like is used, the entire surface is uniformly charged by a charging device (not shown), and then an electrostatic latent image is formed on the surface by irradiation of image light. The developer carrier 1
8 is a magnet roll 2 fixed so that its position is immovable.
And a cylindrical sleeve 1 rotatably supported on the outer periphery of the sleeve 1, and the magnetic force of the magnet roll 2 attracts a magnetic developer onto the peripheral surface of the sleeve 1 to rotate the sleeve 1. By doing so, the developer on the surface is conveyed. A DC superimposing AC voltage is applied between the developer carrying member 18 and the electrostatic latent image holding member 17 from a bias power source (not shown). Development area A facing 18
An alternating electric field is generated at.

The first side seal magnet 3 is a ring-shaped magnet which is arranged inside the cylindrical sleeve 1 so that the central axes thereof coincide with each other and is supported so as to rotate integrally with the sleeve 1. Yes, the outer circumference is S over the entire circumference
The magnetic poles are set so that the poles and the inner peripheral side are N poles.
The second side seal magnet 4 is a cylindrical sleeve 1
The outer side of the first sleeve along the circumferential direction of the sleeve 1.
The arc-shaped magnet is arranged so as to face the side seal magnet 3. The second side seal magnet 4 is provided with magnetic poles so that the inner side of the arc is the S pole and the outer side is the N pole, and the second side seal magnet 4 is supported close to and spaced from the peripheral surface of the sleeve 1.
The gap with the sleeve 1 is set to be within 3 mm. Further, in the region of the developer carrying member 18 in the circumferential direction, the developer carrying member 18 is not provided in the portion facing the electrostatic latent image holding member 17, and the second side seal magnet 4 is provided.
At least 1 m from the edge of the electrostatic latent image carrier 17
A gap of about m or more is maintained. The first side seal magnet may have an N pole on the outer peripheral side and an S pole on the inner peripheral side. At that time, the second side seal magnet and the first side seal magnet may be magnetized so that magnetic poles having the same polarity face each other. Therefore, the second side seal magnet has an N pole inside and an S pole outside. Further, both the first side seal magnet 3 and the second side seal magnet 4 are rubber magnets or sintered (ferrite).
A magnet or the like can be used, and a magnet using another material may be used.

The first developer agitating chamber 9 and the second developer agitating chamber 10 are communicated with each other at both ends in the axial direction of the developer carrying member 18, and the agitating of the developer and the axial direction thereof are performed. A first screw auger 11 and a second screw auger 12 are provided for carrying the developer to. These two screw augers 11 and 12 are set in the rotation directions so as to convey the developer in mutually opposite directions, and the developer causes the developer to flow between the first developer stirring chamber 9 and the second developer stirring chamber 10. It circulates. The developer used in such a developing device can be a one-component developer consisting of only a magnetic toner or a two-component developer obtained by mixing a non-magnetic toner and a magnetic carrier, but in the present embodiment, a negative charging system is used. A one-component magnetic developer containing magnetic powder is used.

With such a developing device, the electrostatic latent image on the electrostatic latent image holder is developed as follows. The developer supplied into the housing 16 is conveyed while being circulated in the first developer stirring chamber 9 and the second developer stirring chamber 10 and is uniformly stirred. The agitated developer is supplied to the developer carrier 18 by the rotation of the developer supply member 15 adjacent to the first screw auger 11, and is attracted to the surface of the sleeve 1 by the magnetic force of the magnet roll 2. This developer is regulated by the developer regulation member 5 as the sleeve 1 rotates to form a uniform thin layer, and is further conveyed to the development area A facing the electrostatic latent image carrier 17. In the developing area A, a DC superimposed AC voltage is applied between the developer carrying member 18 and the electrostatic latent image holding member 17, and the alternating electric field generated here causes the developer to adhere to the electrostatic latent image. Development is performed.

In such a developing device, the developer carrier 1
As shown in FIG. 2, the first side seal magnet 3 and the second side seal magnet 4 disposed near both ends of the shaft 8 in the axial direction are supported so that the S poles repelling each other face each other. Thus, a magnetic field is formed so that the lines of magnetic force connect the S pole and N pole of each magnet. Therefore, a magnetic field that repels magnetic force lines is formed in the gap between the two magnets, and the developer accommodated in the housing 16 is near the axial ends of the developer carrier 18 as shown in FIG. 2B. It cannot be inserted between the two side seal magnets, and is attracted along the magnetic lines of force extending from the corners of the first side seal magnet 3 and the second side seal magnet 4. Further, since the developer adsorbed on the side of the first side seal magnet and the developer adsorbed on the side of the second side seal magnet repel each other, condensation and sticking of the developer do not easily occur.

Table 1 shows the results of an investigation of the state of the developer adhering to the facing portion when the distance between the second side seal magnet 4 and the peripheral surface of the sleeve 1 was changed.

[0020]

[Table 1]

From this table, it is recognized that the developer does not enter the gap if the gap between the second side seal magnet 4 and the peripheral surface of the sleeve 1 is 3 mm or less. Thus, by setting the gap between the second side seal magnet 3 and the peripheral surface of the sleeve 1 to 3 mm or less, the housing 16
The leakage of the developer to the outside can be prevented, and the developer does not condense or stick between the second side seal magnet 4 and the sleeve 1 due to the rotation of the sleeve 1. Images can be obtained. In addition, the second side seal magnet 4 and the electrostatic latent image holder 17 are set to 1 m.
By separating them by m or more, the bias voltage applied between the developer carrying member 18 and the electrostatic latent image holding member 17 becomes the second bias voltage.
It is prevented from discharging through the side seal magnet.

Although the one-component magnetic developer is used in this embodiment, a two-component developer in which a non-magnetic toner and a magnetic carrier are mixed can be used between the second side seal magnet and the sleeve. Since the magnetic carrier does not enter and the non-magnetic toner is adsorbed to the magnetic carrier by the electric coupling force, the two-component developer can be sealed in the same manner as the one-component magnetic developer.

FIG. 3 is a schematic sectional view showing the structure of the developing device according to the second embodiment of the present invention. In this developing device, the sleeve 1 of the developer carrier 18 in the above embodiment is used.
Instead of the first side seal magnet 3 which is provided on the inner side of and rotates with the sleeve 1, a first side seal magnet 23 on a disc fixed to the support shaft of the magnet roll 2 is provided. Both the first side seal magnet 23 and the magnet roll 2 do not rotate and are fixedly supported so that their positions are immovable. The other structure of this developing device is the same as that of the above-mentioned embodiment. In this embodiment, the same developer sealing effect as in the above-described embodiments can be obtained, and the occurrence of image quality defects due to developer sticking can be prevented.

FIG. 4 is a schematic sectional view showing the structure of a developing device according to the third embodiment of the present invention. In this developing device, a circumferential groove-shaped recess is provided on the surface near the end of the sleeve 21, and a ring-shaped first side seal magnet 33 is fitted into the recess. The other structure of this developing device is the same as that of the first embodiment. In this embodiment, the same developer sealing effect as in the above-described embodiments can be obtained, and the occurrence of image quality defects due to the adherence of the developer can be prevented.

[0025]

As described above, in the developing device of the present invention, the first side seal magnet and the second side seal magnet are near the surface of the sleeve near both ends of the developer carrying member in the axial direction. Since the magnetic force lines are provided to face each other so as to form a repulsive magnetic field, the developer is concentrated and adsorbed in the vicinity of the corners of the first and second side seal magnets in the housing, and the two side seals are attached. It does not enter the gap where the magnets face each other. Therefore, the developer can be prevented from leaking out of the housing, and the developer is not condensed or fixed in the gap, so that a good image having no image quality defect can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a developing device that is a first embodiment of the present invention.

FIG. 2 is a diagram showing an operation of a side seal magnet in the developing device of the above embodiment.

FIG. 3 is a schematic cross-sectional view showing a configuration of a developing device that is a second embodiment of the present invention.

FIG. 4 is a schematic sectional view showing the configuration of a developing device that is a third embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an example of a conventional developing device.

FIG. 6 is a schematic sectional view showing another example of a conventional developing device.

FIG. 7 is a diagram showing an operation of a sealing magnet in the developing device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sleeve 2 Magnet roll 3 1st side seal magnet 4 2nd side seal magnet 5 Developer regulation member 9 1st developer stirring chamber 10 2nd developer stirring chamber 11 1st screw auger 12 2nd Screw auger 13 partition wall 15 developer supply member 16 housing 17 electrostatic latent image carrier 18, 28, 38 developer carrier 21 sleeve 23, 33 first side seal magnet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Kimura 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. A non-magnetic cylindrical sleeve rotatably supported in close proximity to the electrostatic latent image carrier, and a magnet roll located inside the sleeve and having a plurality of magnetic poles. In a developing device, the first side seal magnet is provided on a surface near or inside both ends of the sleeve in the axial direction or along the circumferential direction, and the first side seal magnet is provided outside the circumferential surface of the sleeve. And a second side seal magnet provided close to and spaced apart from each other along the circumferential surface of the sleeve, wherein both the first side seal magnet and the second side seal magnet are cylindrical sleeves. A developing device, which has N poles and S poles in a radial direction and is supported so that mutually repelling poles face each other.