JPS61151578A - Developing device - Google Patents

Abstract

PURPOSE:To obtain stable and good images when a high-resistance, one-component magnetic toner is used, by providing a rotatable sleeve with many magnetic poles on which plural N and S magnetic poles are arranged alternately in the peripheral direction, a developing main pole arranged fixedly in the sleeve, and a magnetic material arranged near the developing main pole. CONSTITUTION:An attracted developer 6 forms bristles in accordance with lines of the magnetic force of a sleeve 11a with many magnetic poles. The chain of the developer 6 formed in bridged shapes on the sleeve 11a with many magnetic poles is controlled to a certain quantity by a bristle cutting plate 7 in accordance with the rotation of the sleeve 11a with many magnetic poles and is carried under a triboelectrifying member 5 and is triboelectrified with a prescribed polarity and is carried to a developing area furthermore. When the developer enters into the range of lines of the magnetic force of a main pole magnet 12 after passing the position of a magnetic body 13a, the bridged state is released by the action of the magnetic force. Then, sufficiently high bristles are formed quickly in magnetic pole positions, where the inside is S poles, on the sleeve 11a with many magnetic poles in accordance with the distribution of lines of the magnetic force and are brought into contact with the surface of a photosensitive body 8. The developer electrified by friction with the triboelectrifying member 5 is stuck to an electrostatic latent image on the photosensitive body 8 and develops it.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device used in an electrophotographic copying machine or a printer using electrophotographic technology.

[Conventional technology]

Conventionally, nine different developing methods have been proposed as methods for developing an electrostatic latent image formed on an image carrier such as a photoreceptor or dielectric. For example, magnetic brush development method, cascade development method, powder cloud development method, fur brush development method, liquid development method, etc.
A large number of developing methods are known.

Among these developing methods, a two-component magnetic brush developing method using a developer mainly consisting of a non-magnetic toner and a magnetic carrier can provide relatively stable and good images.

However, on the other hand, it has drawbacks such as the magnetic carrier deteriorating due to long-term use and the need for a highly accurate toner concentration control mechanism.

As a solution to these drawbacks, there is a one-component magnetic brush development method that uses a developer made only of magnetic toner particles, and various developing devices that basically do not require a toner concentration control mechanism have been proposed.

It has been put into practical use.

For example, a developing device using a single-component magnetic toner that is electrically conductive has been proposed.

Among them, developing devices for use when the resistance of magnetic toner is very low (the volume resistivity of the toner is about 10'' to 10'Ω) are well known. One example will be explained with reference to the attached drawings.Second. The diagram is.

FIG. 1 is a configuration diagram showing an example of a conventional developing device. The developing device is a magnetic roll 2a provided at a lower end of the inside of the flopper 4a that opens toward the image carrier 1a.

It is composed of a non-magnetic sleeve 3a, a cutting plate 7a, etc., and a low-resistance magnetic toner 6a is contained in the hopper 4a.

In the developing device configured as described above, the low-resistance magnetic toner 6a is attracted onto the circumference of the non-magnetic sleeve 3a by the magnetic force of the magnetic roll 2a, and the rotation of the magnetic roll 2a causes the low-resistance magnetic toner 6a to be attracted to the circumference of the non-magnetic sleeve 3a in a direction opposite to the rotational direction of the magnetic roll 2a. transported to. In this way, the low resistance magnetic toner 6a is transferred to the non-magnetic sleeve 3.
Development is performed by contacting an image carrier 1a provided close to a and transferring the electrostatic latent image on the photoreceptor la.

That is, in the developing section, the electrostatic latent image on the surface of the image carrier 1a and the non-magnetic sleeve 3 are formed by the particle chains of the low-resistance magnetic toner 6a.
A conductive path is formed between the a surface and the a surface.

Charges having a polarity opposite to that of the electrostatic latent image are induced from the non-magnetic sleeve 3a side to the low-resistance magnetic toner particles 6a through the conductive path, and the Coulomb force generated between the electrostatic latent image and the image area causes a low resistance. The magnetic toner 6a particles adhere to the image area and development is performed.

[Problems with conventional technology]

Such conventional developing methods are good when the image bearing member is a supporting member for the final toner image, but when the image bearing member is an intermediate recording member such as a photoreceptor drum and the toner image formed thereon is transferred to plain paper. When electrostatically transferring to, etc., the transferability is extremely poor due to its low resistance.

Further, in a developing device that uses a high resistance component magnetic toner with good transferability as a developer, a sufficient conductive path cannot be formed.

Furthermore, as is common to developing devices that use -component developers, in order to make the toner layer on the non-magnetic sleeve very thin, it is necessary to maintain the distance between the image carrier and the sleeve with extremely high precision, which makes the structure difficult. It has the drawbacks of being complex, requiring high precision, and being expensive.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a developing device that can produce stable and good images when using a high-resistance component magnetic toner.

[Key points of the invention]

According to the present invention, the above object is to provide a rotatable multi-magnetic pole sleeve in which a plurality of N and S multi-magnetic poles are arranged alternately in one circumferential direction;
This is achieved by providing a developing device characterized by having a main developing pole fixedly disposed within the multi-magnetic pole sleeve and a magnetic material disposed close to the main developing pole.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to eight drawings. FIG. 1 is a configuration diagram showing a developing device of the present invention; FIG.
Figure 4 is a configuration diagram for explaining the present invention in detail;
The figure is a sectional view of a main part of a magnetic roll used in the developing device of the present invention.

The developing device includes a magnetic roll 10 provided at the lower end of the hopper 4 at a portion opening toward the photoreceptor 8, and a frictional charging member 5. The hopper 4 is composed of a cutting plate 7 and the like, and a developer 6, which is a magnetic toner having high and low anti-component properties, is contained in the hopper 4.

The magnetic roll 10 holds a multi-magnetic pole sleeve lla, in which N and S poles are arranged alternately in the circumferential direction, from the inside with a non-magnetic support roll llb made of aluminum or the like. A pole magnet 12 is fixedly disposed, and magnetic bodies 13a and 13b are disposed above and below the main pole magnet 12 in parallel to the magnetic pole arrangement.

Also, a multi-magnetic pole sleeve lla in which the frictional charging member 5 rotates nine times.
It is fixed to the ear cutting plate 7 with a slight gap from the ear. Further, the ear cutting plate 7 is placed on the rotation center of the rotating multi-magnetic pole sleeve 11a and the support roll Ilb,
They are provided with a predetermined gap.

FIG. 6 is a schematic diagram showing the distribution of magnetic lines of force in the vicinity of the main developing pole of the magnetic roll 10 configured as described above.

In the figure, the N pole of the main pole magnet 12 (main development pole)
When the multi-pole sleeve lla is located close to the multi-pole sleeve lla, the inside of the multi-pole sleeve lla is the south pole.

Lines of magnetic force are concentrated on the magnet whose surface is N-pole, and lines of magnetic force are generated in a direction perpendicular to the surface of the multi-pole sleeve lla.

FIG. 3 and FIG. 4 are configuration diagrams showing a stage before the invention of the magnetic roll of the present invention.

As shown in the figure, as a means to strengthen the magnetic flux density in the developing section, a multi-magnetic pole sleeve lla having a large number of N and S poles alternately in the circumferential direction of one revolution of the magnetic roll 10b and the multi-magnetic pole sleeve lla are held. A configuration has been considered in which a non-magnetic support roll Ilb made of aluminum or the like and a main pole magnet 12b are fixedly arranged inside the support roll Ilb.

With this configuration, ears of sufficient height can be formed in the developing section, so that the development gap accuracy can be significantly reduced.

However, in the magnetic roll 10b having a configuration of 9 or more.

As shown in Figure 4, which shows the distribution of magnetic lines of force, the main pole magnet)
At both ends of the magnetic field 12b, the lines of magnetic force spread, making it impossible to achieve rapid rise and suction of the spikes in the development area.

Therefore, since the spikes of developer gradually rise and fall at the position of the main pole magneto 12b, scattering of the developer is likely to occur particularly when the spikes fall.

Therefore, a magnetic roll 10 of the present invention as shown in FIG. 5 was invented.

According to the magnetic roll 10 of the present invention, magnetic bodies 13a and 13b are provided on both sides of the main pole magnet nod 12, as shown in FIG. 6, which shows the distribution of magnetic lines of force.

When the multi-pole sleeve lla side of the main pole magnet 12 is the N pole, in the region affected by the magnetic force of the N pole, which is the main developing pole, the inside of the multi-pole sleeve lla is the S pole (the outside is the N pole).
The lines of magnetic force are concentrated on the magnet of the multi-pole sleeve 11.
8. Lines of magnetic force are generated in the direction perpendicular to the surface.

On the other hand, in a region where the inside of the multi-pole sleeve lla is N-pole, the magnetic field lines are almost not produced on the sleeve surface because the polarity is the same as the main developing pole.

Here, the inside of the multi-pole sleeve lla is the S pole (the outside is the N pole).
A part or most of the lines of magnetic force exit from the magnet (pole) to the surface of the multi-pole sleeve 113.

The inside of the multi-pole sleeve lla enters the magnetic bodies 13a and 13b through the magnet whose N pole (outer S pole).

In this way, the presence of the magnetic bodies 1'3a and 13b can prevent the lines of magnetic force of the main pole magnet 12 from spreading.

On the other hand, in a region hardly affected by the magnetic force of the main pole magnet 12, lines of magnetic force are concentrated between adjacent magnets of the multi-pole sleeve lla.

The operation will be explained below with reference to FIG.

The multi-pole sleeve lla rotates counterclockwise.

The developer 6 in the hopper 4 is attracted by the magnetic force on its surface.

The attracted developer 6 forms ears according to the lines of magnetic force of the multi-pole sleeve lla.

The developer 6 attracted to the multi-pole sleeve lla in a region relatively unaffected by the magnetic force of the main pole magnet 12 forms a bridge-like chain of developer 6 by the adjacent magnets.

The chains of developer 6 formed in the form of bridges on the multi-magnetic sleeve lla are regulated to a constant amount by the cutting plate 7 as the multi-magnetic sleeve lla rotates, and are conveyed below the frictional charging member 5. It is triboelectrically charged to a predetermined polarity and further conveyed to the development area.

The chain of the developer 6 on the multi-pole sleeve lla is connected to the magnetic body 13
The bridge continues to maintain its state until it is transported near a, but when it passes the position of the magnetic body 13a and enters the range of the magnetic field lines of the main pole magnet 12, the main pole magnet 12 and the multi-pole sleeve lla The state of the bridge is released by the magnetic force between the bridge and the bridge. Then, according to the distribution of magnetic lines of force, ears of sufficient height are suddenly formed at the magnetic pole position where the inside of the multi-pole sleeve 11a is the S pole (the outside is the N pole), and the photoreceptor 8
contact the surface.

The developer charged by friction with the frictional charging member 5 adheres to the electrostatic latent image on the photoreceptor 8 and development is performed.
- Next, when reaching the position of the magnetic body 13b, the ear is rapidly attracted onto the multi-pole sleeve lla again according to the lines of magnetic force. This rapid rise and suction of the ears is caused by the installation of the magnetic bodies 13a and 13b, as shown in FIG.

, FIG. 7 is a block diagram showing another embodiment of the present invention.

In the figure, a magnetic material 13b is fixed to only one side of a main pole magnet (12c) disposed inside a magnetic roll LOc.

When the main pole magnet is provided on only one side of the main pole magnet 12c as in this embodiment, as mentioned above, developer scattering is particularly likely to occur when the ears fall, so it is provided on the downstream side of the developer as shown in FIG. This is desirable.

Further, as another embodiment, as shown in FIG. 8, the main pole magnet 12d disposed inside the magnetic roll 10d may be covered in three directions with magnetic bodies 13a, 13b, and 13c.

Even with the above configuration, it is possible to obtain rapid spike formation and rapid adhesion in the developing section of the magnetic roll 10d. Accordingly, the developing device of the present invention using one or more such magnetic rolls can provide a magnetic brush of developer of sufficient height in the developing area.

〔Effect of the invention〕

According to the developing device of the present invention configured as described above, it is possible to obtain rapid spike formation in the developing area, so there is no need to set the gap between the photoreceptor and the developing roll with high precision.
Accuracy can be relaxed.

This effect is particularly remarkable when a -component developer is used.

Furthermore, since the spikes rise and fall rapidly in the developing area, it is possible to prevent the developer from scattering in the developing area.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of the developing device of the present invention, and FIG.
The figures are a configuration diagram showing an example of a conventional developing device, FIG. 3 is a sectional view showing the configuration of a magnetic roll that is the basis of the present invention, and FIG.
Figure 1 is a distribution diagram of magnetic lines of force of the magnetic roll which is the basis of the present invention, Figure 5 is a sectional view of the magnetic roll used in the developing device of the present invention, Figure 6 is a distribution diagram of lines of magnetic force of the magnetic roll, Figure 7 is. FIG. 8 is a sectional view showing another embodiment of the magnetic roll used in the present invention. FIG. 8 is a sectional view showing another embodiment of the magnetic roll used in the present invention. 1a... Image carrier, 2a... Magnetic roll, 3a... Non-magnetic sleeve. 4.4a... Hopper, 5... Frictional charging member, 6... Developer + 6a... Low resistance magnetic toner, 7.7a... Spikes cutting plate,
8... Photoreceptor, 10. LOb. 10c, 10d-magnetic roll, 11a...multi-magnetic pole sleeve, 11b...support roll,
12, 12b, 12c, 12d...main pole magnet, 13.13a. 13b, 13c...magnetic material. Patent Applicant Casio Computer Co., Ltd. Same as above
Casio Electronic Industries Co., Ltd. Patent Attorney Dai
Yoshi Suga 2 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A rotatable multi-magnetic pole sleeve in which a plurality of N and S magnetic poles are arranged alternately in the circumferential direction, a main developing pole fixedly disposed within the multi-magnetic pole sleeve, and a magnetic material disposed close to the main developing pole. A developing device comprising: