JPH08137219A - Dry developing device - Google Patents

Abstract

PURPOSE: To carry toner much enough to maintain image density to a developing area by uniformly coating a developing sleeve with non-magnetic toner without pressurizing the non-magnetic toner, magnetic material particles and the sleeve. CONSTITUTION: This device is provided with developer having the non-magnetic toner and the magnetic material particles, a toner carrier 1a, a permanent magnet 1b and a toner layer thickness regulating body 6a having a rotatable component member, and the toner layer thickness regulating body is arranged near the toner carrier and near at least one magnetic pole of the permanent magnet 1b disposed inside the toner carrier, and the rotating direction of the rotatable component member is made the same as the rotating direction of the toner carrier, and flux density is made higher as going from the toner carrier to the toner layer thickness regulating body side. A DC power source 7 impressing voltage between the toner carrier and the toner layer thickness regulating body is provided so as to peel the non-magnetic toner sticking to the magnetic material particles by mirroring force and make it fly to the toner carrier side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in electrophotography, electrostatic recording devices and the like.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, a number of methods are known as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. However, generally, an electric latent image is formed on a photoconductor of a photoconductive material by various means, and then the latent image is developed by using a toner, and if necessary, a transfer material such as paper. After the toner image is transferred onto the sheet, it is heated or fixed by solvent vapor or the like to obtain a copy. Various methods for visualizing an electric latent image using toner are also known.

For example, a magnetic brush developing method described in US Pat. No. 2,870,643, and No. 221776.
Many developing methods such as the powder cloud method, the fur brush developing method, and the liquid developing method described in the specification are known.

Among these developing methods, in particular, a magnetic brush method using a developer mainly containing toner and carrier,
The cascade method, the liquid development method and the like have been widely put into practical use.
All of these methods are excellent methods in which a good image can be obtained relatively stably, but on the other hand, they have the common drawbacks associated with two-component developers, such as carrier deterioration and variation in the mixing ratio of toner and carrier.

In order to avoid such drawbacks, various developing methods using a one-component developer consisting of only toner have been proposed. For example, US Pat. No. 3,909,258 proposes a method of developing using a magnetic toner having electrical conductivity. This supports the conductive magnetic developer in a cylindrical conductive sleeve having magnetism inside,
This is developed by bringing it into contact with an electrostatic image. At this time, a conductive path is formed between the surface of the recording body and the surface of the sleeve by the toner particles in the developing section, and the electric charge is introduced from the sleeve to the toner particles through the conductive path, and the Coulomb force between the electrostatic image section As a result, toner particles adhere to the image area and are developed. The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method, but on the other hand, since the toner is conductive,
It has a drawback that it is difficult to electrostatically transfer a developed image from a recording medium to a final supporting member such as plain paper.

In order to solve this problem, as a developing method using a high resistance toner capable of being electrostatically transferred, Japanese Patent Application Laid-Open No. 52-94140 discloses a developing method utilizing dielectric polarization of toner particles. It is shown. However, such a method has a drawback that the developing speed is slow and the density of a developed image cannot be sufficiently obtained, and it is practically difficult. As another method using a high-resistance magnetic toner, there is known a method in which toner particles are triboelectrically charged by friction between the toner particles, friction between the toner particles and a sleeve, and the toner particles are brought into contact with an electrostatic holding member to develop. Has been. However, in these methods, the number of contact between the toner particles and the friction member is small, and triboelectric charging is apt to be insufficient, or when the Coulomb force between the charged toner particles and the sleeve is strong, the toner particles are not attached on the sleeve. Easy to aggregate,
It has been pointed out that it has many drawbacks such as the above, and there are many practically difficult points.

On the other hand, in Japanese Patent Laid-Open No. 54-4O36, there is proposed a new developing method which eliminates the above-mentioned drawbacks. In this method, toner is applied very thinly on a sleeve, it is triboelectrically charged, then it is brought very close to an electrostatic image under the action of a magnetic field, and it is made to face without being brought into contact with the electrostatic image for development. .

According to this method, the magnetic toner is applied very thinly to increase the chances of contact between the magnetic toner and the sleeve, and to give the toner a triboelectric charge amount necessary for development. Makes it possible.

However, in such a one-component developing method using a magnetic toner, the fixing property is poor at the time of thermally fixing the toner image transferred onto the transfer paper, and the color toner is used because the magnetic substance is internally added to the toner itself. There are some drawbacks such as being impossible to use.

On the other hand, as a one-component developing method using a non-magnetic toner, a powder cloud method, an impression developing method and the like are known. Among these, for example, a fur brush developing method in which soft bristles such as beaver are made into a cylindrical brush and a developer is attached to the brush to develop, or an impression in which a developer is attached to a roller such as a velvet is used. The developing method and the like are well known.
These developing methods do not use a toner to which a magnetic material is internally added when developing an electrostatic latent image, and use a carrier particle to form a complicated device for maintaining a constant ratio of the toner and the carrier particle. Is a developing method that does not require.

In the developing method using the magnetic toner, the toner on the developing sleeve is uniformly and predeterminedly formed by the magnetic field formed between the sleeve and the magnetic doctor blade arranged to face the magnet inside the developing sleeve. It is possible to regulate the toner layer thickness (see Japanese Patent Laid-Open No. 54-43036). On the other hand, in the developing method using a non-magnetic toner, it is not possible to obtain a uniform toner layer thickness even if a similar magnetic blade is used, resulting in uneven coating of toner on the sleeve surface, which causes uneven image density. Appears.

Although it is possible to regulate the toner layer thickness by using an elastic blade as the doctor blade, the latitude of the pressing pressure of the elastic blade against the developing sleeve is very narrow, and when it is too low, it is uniform. A predetermined toner layer thickness cannot be obtained, and if it is too high, the toner and the sleeve are damaged.

In order to solve such a problem, a developing method as disclosed in Japanese Patent Publication No. 58-90668, Japanese Patent Publication No. 58-143360, etc. has been proposed.

FIG. 5 shows an example of a developing device of the above-mentioned developing method. In the figure, 1a is a developing sleeve using a non-magnetic member,
Reference numeral b is a permanent magnet fixed in the developing sleeve 1a, 2 is a blade made of a magnetic material or magnet, and 3 is a developing device. The gap between the magnetic blade 2 and the developing sleeve 1a is 2
It is set to about 50 μm.

In the developing device shown in FIG. 5, the magnetic particles 12 form a magnetic brush along the magnetic field between the magnetic blade 2 and the permanent magnet 1b, and are restrained in the magnetic field. Here, the non-magnetic toner 11 moves while being dragged by the developing sleeve 1a having a rough surface, and at the same time, is charged by friction between the magnetic particles and the surface of the developing sleeve 1a, and the magnetic particles and the developing sleeve 1a are reflected by a mirroring force. However, since the magnetic particles 12 cannot move due to the above magnetic field constraint,
Only the non-magnetic toner attached to the developing sleeve 1a can pass through the magnetic brush, and the rotation of the developing sleeve 1a forms a uniform thin layer of the non-magnetic toner on the surface of the developing sleeve 1a.

In the above-mentioned conventional system, the magnetic particles 12 are used.
Forms a magnetic brush in a system with a large amount of toner,
Toner must be applied on the developing sleeve and the function of regulating the amount must be fulfilled. At the same time, it must have the function of supplying toner while circulating.
Further, it is not preferable that the magnetic particles pass between the magnetic blade and the developing sleeve. Therefore, in order to satisfy these functions, the magnetic brush has an appropriate restraining force generated by a magnetic field, yet exhibits appropriate circulation property, and the state of the formed magnetic brush enables uniform application. Therefore, it must have a suitable hardness and density.

For example, a relatively sparse magnetic brush tends to cause underregulated streaks on the developing sleeve,
On the contrary, when the toner density is high, the toner layer on the developing sleeve tends to be extremely thin.

If the circulation of the magnetic particles is too good, the toner layer may become thick and fog may occur on the image, or the magnetic particles may pass through the magnetic blade. On the other hand, when the circulation property is poor, the toner cannot be sufficiently charged, so that a so-called ghost image defect in which the image around the sleeve 1 is dark and thin after that tends to occur.

That is, there is a problem that the latitude of the magnetic brush in the proper state, which fulfills the function of the magnetic particles, is very narrow.

In order to solve the above problems, the inventors of the present invention uniformly coat the surface of the non-magnetic toner, the magnetic particles or the non-magnetic toner on the sleeve without applying pressure to the sleeve, and the magnetic particles are applied. Proposal of a developing device with a wide latitude in which the brush of magnetic particles is in an appropriate state, which can improve the circulation without being conveyed to the developing area and can sufficiently charge the toner by sufficiently stirring it with the toner. did.

That is, as shown in FIG. 6, a non-magnetic toner, magnetic particles, a rotatably arranged toner carrier for carrying the non-magnetic toner on the surface, and a toner carrier provided inside the toner carrier. A permanent magnet and a toner layer thickness regulator for regulating the application of toner on the toner carrier, the toner layer thickness regulator being rotatably disposed near the toner carrier, and The arrangement position is in the vicinity of at least one magnetic pole of a permanent magnet arranged inside the toner carrier, and the rotation direction is the same as the rotation direction of the toner carrier, and By increasing the magnetic flux density from the toner carrier to the opposite side of the toner layer thickness regulation, the non-magnetic toner is uniformly coated on the sleeve surface without applying pressure to the non-magnetic toner, magnetic particles or the sleeve, and Magnetic particles It is possible to improve the circulatory property without transporting the toner to the developing area, sufficiently charge the toner by sufficiently stirring it with the toner, and widen the latitude of the magnetic particle brush in an appropriate state. It was

[0022]

However, in the above-mentioned conventional example, depending on the combination of the non-magnetic toner and the magnetic particles and the environment, etc., the sufficiently charged non-magnetic toner adheres to the magnetic particles by the mirroring force and is developed. In some cases, the amount of non-magnetic toner that has been conveyed in the container together with the magnetic particles to the developing area on the toner carrier becomes insufficient, and the density of the output image may become insufficient.

The present invention is intended to solve the above problems.

That is, it is an object of the present invention to provide a developing device capable of always obtaining a proper developed image regardless of the combination of magnetic particles and non-magnetic toner, environment and the like.

[0025]

To solve the above problems, the present invention provides a developer having a non-magnetic toner and magnetic particles, and a rotatably arranged toner carrier for carrying the non-magnetic toner on the surface. A permanent magnet disposed inside the toner carrier, and a toner layer thickness regulator that regulates the application of the non-magnetic toner on the toner carrier, and the toner layer thickness regulator is a rotatable component member. The rotation of the rotatable component provided in the vicinity of at least one magnetic pole of the permanent magnet disposed inside the toner carrier In the developing device in which the direction is the same as the rotation direction of the toner carrier, and the magnetic flux density increases from the toner carrier toward the toner layer thickness regulator, the toner carrier and toner layer thickness Between regulatory bodies And configured to have a DC power source for applying a voltage.

[0026]

According to the present invention, the toner layer thickness regulating member having a rotatable component is arranged in the vicinity of the toner carrier, and the position of the permanent magnet is arranged inside the toner carrier. In the vicinity of at least one magnetic pole, and the rotational direction of the rotatable constituent member of the toner layer thickness regulating body is the same as the rotational direction of the toner carrying body, and the toner layer thickness regulating body is regulated from the toner carrying body. By increasing the magnetic flux density toward the body side, it becomes possible to return the magnetic particles to the inside of the developing device and coat only the sufficiently charged non-magnetic toner on the toner carrier surface. By applying a voltage between the body and the toner layer thickness control body so that the normally charged non-magnetic toner receives a force in the sleeve direction, the non-magnetic toner adhered to the magnetic particles due to the mirroring force etc. is removed. It can be peeled off from the magnetic particles and can be made to fly to the side of the toner carrier. As a result, a sufficient amount of non-magnetic material to maintain the image density is maintained regardless of the combination of magnetic particles and non-magnetic toner, environment, etc. It has become possible to coat the surface of the toner carrier with toner.

Therefore, it is possible to obtain an output image having a proper density without any image defect due to poor charging and regardless of the combination of the non-magnetic toner and the magnetic particles and the environment.

[0028]

【Example】

(Embodiment 1) FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, 1a is a developing sleeve formed of a non-magnetic metal member which is a toner carrier that rotates in the direction of arrow b2, 1b is a permanent magnet disposed inside the developing sleeve 1a, 3 is a developing unit, 4 Are conveying members for agitating the developer in the developing device 3 and conveying it in the direction of the developing sleeve 1a, and 5 are scrapers.

Further, 6a is a toner layer thickness regulating member composed of a non-magnetic metal member, 6b is a permanent magnet disposed inside the toner layer thickness regulating member 6a, and 7 is a DC power source.

The toner layer thickness regulator 6a is the developing sleeve 1
In the vicinity of a, the developing sleeve 1a is arranged so as to be rotatable in the direction of an arrow b1 which is the same as the rotating direction b2 of the developing sleeve 1a.

In the present invention, the magnetic pole (S61) in the permanent magnet 6b is arranged so as to closely face the magnetic pole (N11) in the permanent magnet 1b at the position where the developing sleeve 1a and the toner layer thickness regulating member 6a face each other. Of the magnetic flux density of 800 Gauss, the magnetic flux density of the magnetic pole N11 is 900 Gauss, and the width of the region showing a value of 50% or more with respect to the peak value of the magnetic flux density of each magnetic pole (for convenience, it will be referred to as a 50% value hereinafter). The ratio of (named) is (50% value of magnetic pole S61) / (50% value of magnetic pole N11)
≈O. 8 and narrowing the width of the magnetic pole S61 with respect to the width of the magnetic pole N11 changes the magnetic flux density of the magnetic field formed between the magnetic pole S61 and the magnetic pole N11 from the developing sleeve 1a to the toner layer thickness regulator 6a. The magnetic flux density increases toward the side, and the developing sleeve 1a and the toner layer thickness regulating member 6
The distance W of a is in the range of 100 μm to 2 mm, and
Absolute value of peripheral speed of developing sleeve 1a and toner layer thickness regulator 6
a, the absolute value of the peripheral speed of the toner layer thickness regulating member 6a / (the absolute value of the peripheral speed of the developing sleeve 1a)> O. It was set to be 5.

As the non-magnetic toner, a negatively chargeable toner having a weight average diameter of 5 μm or more is used, and as the magnetic particles,
A normal magnetic carrier having a weight average diameter of 20 to 100 μm was used.

A DC power source was used as the power source 7, and the negatively charged non-magnetic toner was biased so that a Coulomb force was applied from the toner layer thickness regulator 6a toward the developing sleeve 1a.

In the developing device constructed as shown in FIG. 1, since the magnetic flux density increases from the developing sleeve 1a toward the toner layer thickness regulating body 6a, the developing sleeve 1a and the toner layer thickness regulating body 6a. A magnetic force from the developing sleeve 1a to the toner layer thickness regulating body 6a side acts on the magnetic particles existing between and. As a result, the magnetic poles N11 to S6
A brush of magnetic particles is formed along the magnetic field between the magnetic particles.

Further, since the toner layer thickness regulating member 6a is configured to rotate in the same direction as the developing sleeve 1a, that is, the direction of the arrow b1 in the figure, the magnetic force retained by the magnetic force on the surface of the toner layer thickness regulating member 6a. The body particles are given a conveyance force from the toner layer thickness regulating body 6a to the inside of the developing device 3 by the force of the magnetic field and the frictional force between the body layer and the surface of the toner layer thickness regulating body 6a. Therefore, the magnetic particles do not pass through the position where the developing sleeve 1a and the toner layer thickness regulating member 6a face each other and are not conveyed to the developing area.

The magnetic particles returned to the developing device 3 are scraped off from the surface of the toner layer thickness regulating member 6a by the scraper 5. The magnetic particles returned to the inside of the developing device 3 in this way are agitated with the toner by the carrying member 4, again carried on the surface of the developing sleeve 1a, and carried to a position where the magnetic pole N11 and the magnetic pole S61 face each other. The circulation path of the magnetic particles in the developing device 3 at this time is as shown by an arrow a in the figure.

The non-magnetic toner is charged in the developing device 3 by friction between the magnetic particles and the surface of the developing sleeve 1a. The charged non-magnetic toner adheres to the surface of the developing sleeve 1a and the magnetic particles due to the mirroring force of the electric charge of the toner itself, and is conveyed to the position where the developing sleeve 1a and the toner layer thickness regulator 6a face each other. When the developer is conveyed to the facing position, the magnetic particles are moved from the facing position of the developing sleeve 1a and the toner layer thickness regulating member 6a to the developing device 3 for the above-mentioned reason.
Return to inside. In addition, the non-magnetic toner that has been insufficiently charged and has been conveyed to the facing position due to cohesive force or the like is magnetic pole N1.
1 and a magnetic force in the direction of the toner layer thickness regulating body 6a between the magnetic pole S61 and the frictional force with the surface of the toner layer thickness regulating body 6a and the cohesive force between the non-magnetic toners, the rotation direction of the toner layer thickness regulating body 6a ( A conveyance force in the developing device 3 direction) is obtained.

In the present invention, the power source 7
The non-magnetic toner negatively charged by frictional charging with the magnetic particles is biased so as to receive the Coulomb force from the toner layer thickness regulator 6a toward the developing sleeve 1a. Therefore, the non-magnetic toner that is negatively charged by frictional charging with the magnetic particles and adheres to the magnetic particles due to the mirroring force is generated by the power source 7 in the vicinity of the toner layer thickness regulating body 6a and the developing sleeve 1a. The bias applied causes the magnetic particles to separate from the magnetic particles and fly to the developing sleeve 1a.

Therefore, the non-magnetic toner which passes through the opposing position of the toner layer thickness regulator 6a and the developing sleeve 1a and is conveyed to the developing area is a mirror of the developing sleeve 1a which exceeds the conveying force in the developing device 3 inward direction. Sufficiently charged due to frictional charging between fully charged non-magnetic toner that obtains visual power and magnetic particles,
The non-magnetic toner flies to the developing sleeve 1a by the bias from the power source 7.

That is, according to this structure, the non-magnetic toner can be sufficiently charged by mixing the magnetic particles with the non-magnetic toner, and the magnetic particles are not leaked to the developing area. Regardless of the combination of magnetic particles and non-magnetic toner, the environment, etc., only the sufficiently charged non-magnetic toner sufficient to maintain the image density should be coated on the surface of the developing sleeve and transported to the developing area. Became possible.

(Embodiment 2) FIG. 2 is a sectional view showing a second embodiment of the present invention. In FIG. 2, 1a is an arrow b2
Developing sleeve 1b composed of a non-magnetic metal member that is a toner carrier that rotates in the direction of 1
A permanent magnet 3 disposed inside the developing device, 3 is a developing device, 4 is a conveying member for stirring the developer in the developing device 3 and conveying the same in the direction of the developing sleeve 1a, and 5 is a scraper. And 6a
Is a toner layer thickness regulator made of a non-magnetic metal member, 6b
Is a permanent magnet disposed inside the toner layer thickness regulator 6a,
Reference numeral 7 is a DC power supply, and 8 is an AC power supply.

The toner layer thickness regulator 6a is the developing sleeve 1
In the vicinity of a, the developing sleeve 1a is arranged so as to be rotatable in the direction of an arrow b1 which is the same as the rotating direction b2 of the developing sleeve 1a.

Developing sleeve 1a and toner layer thickness regulator 6a
The magnetic pole (S6) in the permanent magnet 6b, which is arranged so as to closely face the magnetic pole (N11) in the permanent magnet 1b at the facing position of
The magnetic flux density of 1) is 800 gauss, the magnetic flux density of the magnetic pole N11 is 900 gauss, and the ratio of 50% value of each magnetic pole is (50% value of magnetic pole S61) / (50% value of magnetic pole N11).
≈O. 8 and narrowing the width of the magnetic pole S61 with respect to the width of the magnetic pole N11 changes the magnetic flux density of the magnetic field formed between the magnetic pole S61 and the magnetic pole N11 from the developing sleeve 1a to the toner layer thickness regulator 6a. The magnetic flux density increases toward the side, and the developing sleeve 1a and the toner layer thickness regulating member 6
The distance W of a ranges from 100 μm to 2 mm, and
Absolute value of peripheral speed of developing sleeve 1a and toner layer thickness regulator 6
a, the absolute value of the peripheral speed of the toner layer thickness regulating member 6a / (the absolute value of the peripheral speed of the developing sleeve 1a)> O. It was set to be 5.

As the non-magnetic toner, a negatively chargeable toner having a weight average diameter of 5 μm or more is used, and as the magnetic particles,
A normal magnetic carrier having a weight average diameter of 20 to 100 μm was used.

Toner layer thickness regulator 6a and developing sleeve 1a
In the meantime, the AC bias from the power supply 8 is superimposed on the non-magnetic toner negatively charged with the DC bias from the power supply 7 so that the Coulomb force from the toner layer thickness regulator 6a toward the developing sleeve 1a is applied.

In the developing device constructed as shown in FIG. 2, since the magnetic flux density increases from the developing sleeve 1a toward the toner layer thickness regulating body 6a, the developing sleeve 1a and the toner layer thickness regulating body 6a. A magnetic force from the developing sleeve 1a to the toner layer thickness regulating body 6a side acts on the magnetic particles existing between and. As a result, the magnetic poles N11 to S6
A brush of magnetic particles is formed along the magnetic field between the magnetic particles.

Further, since the toner layer thickness regulating member 6a is configured to rotate in the same direction as the developing sleeve 1a, that is, the direction of the arrow b1 in the figure, the magnetic force retained by the magnetic force on the surface of the toner layer thickness regulating member 6a. The body particles are given a conveyance force from the toner layer thickness regulating body 6a to the inside of the developing device 3 by the force of the magnetic field and the frictional force between the body layer and the surface of the toner layer thickness regulating body 6a. Therefore, the magnetic particles do not pass through the position where the developing sleeve 1a and the toner layer thickness regulating member 6a face each other and are not conveyed to the developing area.

The magnetic particles returned to the developing device 3 are scraped off from the surface of the toner layer thickness regulating member 6a by the scraper 5. The magnetic particles returned to the inside of the developing device 3 in this way are agitated with the toner by the carrying member 4, again carried on the surface of the developing sleeve 1a, and carried to a position where the magnetic pole N11 and the magnetic pole S61 face each other. The circulation path of the magnetic particles in the developing device 3 at this time is as shown by an arrow a in the figure.

The non-magnetic toner is charged in the developing device 3 by friction between the magnetic particles and the surface of the developing sleeve 1a. The charged non-magnetic toner adheres to the surface of the developing sleeve 1a and the magnetic particles due to the mirroring force of the electric charge of the toner itself, and is conveyed to the position where the developing sleeve 1a and the toner layer thickness regulator 6a face each other. When the developer is conveyed to the facing position, the magnetic particles are moved from the facing position of the developing sleeve 1a and the toner layer thickness regulating member 6a to the developing device 3 for the above-mentioned reason.
Return to inside. Further, the non-magnetic toner that has been conveyed to the facing position due to cohesive force or the like and is insufficiently charged is
The magnetic force in the direction of the toner layer thickness regulating body 6a between the magnetic pole 11 and the magnetic pole S61 receives the frictional force with the surface of the toner layer thickness regulating body 6a and the cohesive force between the non-magnetic toners to rotate the toner layer thickness regulating body 6a ( A conveying force toward the developing device 3) is obtained.

In the present invention, the power source 7
The non-magnetic toner negatively frictionally charged by the magnetic particles is biased so as to receive the Coulomb force from the toner layer thickness regulator 6a toward the developing sleeve 1a. An AC bias is applied between the toner layer thickness regulator 6a and the developing sleeve 1a by a power source 8. Therefore,
The adhesion between the non-magnetic toner and the magnetic particles is large, and the toner layer thickness regulator 6a and the developing sleeve 1 can be formed only by the DC bias.
Even if the bias leaks between a and the non-magnetic toner cannot be peeled off from the magnetic particles, an AC bias is applied to bias the toner layer thickness regulator 6a and the developing sleeve 1a. It is possible to apply a large electrostatic force to the non-magnetic toner as compared with the case where only the DC bias is applied without leaking the toner.

Therefore, even when the adhesion between the non-magnetic toner and the magnetic particles is large, the non-magnetic toner is negatively charged by frictional charging with the magnetic particles and adheres to the magnetic particles due to the mirroring force. In the vicinity of the toner layer thickness regulator 6a and the developing sleeve 1a, the toner is separated from the magnetic particles by the bias applied by the power sources 7 and 8 and flies to the developing sleeve 1a. Therefore, the non-magnetic toner that passes through the opposing position of the toner layer thickness regulator 6a and the developing sleeve 1a and is transported to the developing area has a mirroring force with respect to the developing sleeve 1a that exceeds the transporting force toward the inside of the developing device 3. The obtained sufficiently charged non-magnetic toner is triboelectrically charged with the magnetic particles to be sufficiently charged, and the non-magnetic toner is ejected to the developing sleeve 1a by the bias from the power sources 7 and 8.

That is, according to this structure, it is possible to sufficiently charge the non-magnetic toner by mixing the magnetic particles with the non-magnetic toner, and the magnetic particles are not leaked to the developing area. Regardless of the combination of magnetic particles and non-magnetic toner, the environment, etc., only the sufficiently charged non-magnetic toner sufficient to maintain the image density should be coated on the surface of the developing sleeve and transported to the developing area. Became possible.

(Third Embodiment) FIG. 3 is a sectional view showing a third embodiment of the present invention. In FIG. 3, 1a is an arrow b2
Developing sleeve 1b composed of a non-magnetic metal member that is a toner carrier that rotates in the direction of 1
3 is a developing device, and 4 is a conveying member for agitating the developer in the developing device 3 and conveying it in the direction of the developing sleeve 1a. Further, 6b is a permanent magnet disposed inside the toner layer thickness regulating body 6a, 6c is a driving roller, 7 is a DC power source, 9 is a roller rotatably arranged in the direction of arrow d, 10 is roller 9 and toner. It is a conductive belt member hung between the layer thickness regulators 6a.

The driving roller 6c is located near the developing sleeve 1a, and has an arrow b1 in the same direction as the rotating direction of the developing sleeve 1a.
The conductive belt 10 is arranged to be driven in the direction.

In the present invention, the permanent magnet 6b is arranged so as to closely face the magnetic pole (N11) in the permanent magnet 1b at the position where the developing sleeve 1a and the drive roller 6c face each other.
The magnetic flux density of the inner magnetic pole (S61) is 800 gauss, and the magnetic pole N
The magnetic flux density of No. 11 is 900 gauss, and the ratio of 50% value of each magnetic pole is (50% value of magnetic pole S61) / (50% value of magnetic pole N11)
≈O. 8 and narrowing the width of the magnetic pole S61 with respect to the width of the magnetic pole N11 changes the magnetic flux density of the magnetic field formed between the magnetic pole S61 and the magnetic pole N11 from the developing sleeve 1a to the toner layer thickness regulator 6a. The magnetic flux density increases toward the side, the distance W between the developing sleeve 1a and the conductive belt 10 is in the range of 100 μm to 2 mm, and the absolute value of the peripheral speed of the developing sleeve 1a and the conductive belt 10 are equal to each other. The ratio of the absolute values of the peripheral speed is expressed by (the absolute value of the peripheral speed of the conductive belt 10) / (the absolute value of the peripheral speed of the developing sleeve 1a)> O. It was set to be 5.

As the non-magnetic toner, a negatively chargeable toner having a weight average diameter of 5 μm or more is used, and as the magnetic particles,
A normal magnetic carrier having a weight average diameter of 20 to 100 μm was used.

A DC power source is used as the power source 7, and the negatively charged non-magnetic toner is transferred from the conductive belt 10 to the developing sleeve 1a.
It was biased to exert a Coulomb force in the direction.

In the developing device constructed as shown in FIG. 3, the magnetic particles forming the brush by the magnetic field between the magnetic pole N11 and the magnetic pole S61 are indicated by the arrow b1 in the figure due to the frictional force with the conductive belt 10. It is conveyed in the rotational direction, returned to the inside of the developing device 3, and falls into the developing device 3 due to gravity.

Further, in the present invention, due to the effect of the bias from the power source 7, the non-magnetic toner adhered to the magnetic particles due to the mirroring force or the like is generated at the developing sleeve 1a and the conductive belt 10 in the close position. Fly to.

As a result, the same effect as described in Example 1 was obtained.

(Embodiment 4) FIG. 4 is a sectional view showing a fourth embodiment of the present invention. In FIG. 4, 1a is an arrow b2
Developing sleeve 1b composed of a non-magnetic metal member that is a toner carrier that rotates in the direction of 1
3 is a developing device, and 4 is a conveying member for agitating the developer in the developing device 3 and conveying it in the direction of the developing sleeve 1a. 6b is a permanent magnet disposed inside the toner layer thickness regulating member 6a, 6c is a driving roller, 7 is a DC power source, 8 is an AC power source, 9 is a roller rotatably disposed in the direction of arrow d, 10 Is a conductive belt member hung between the roller 9 and the toner layer thickness regulator 6a.

The driving roller 6c is provided in the vicinity of the developing sleeve 1a with an arrow b1 in the same direction as the rotating direction of the developing sleeve 1a.
The conductive belt 10 is arranged to be driven in the direction.

In the present invention, the permanent magnet 6b is disposed so as to closely face the magnetic pole (N11) in the permanent magnet 1b at the position where the developing sleeve 1a and the driving roller 6c face each other.
The magnetic flux density of the inner magnetic pole (S61) is 800 gauss, and the magnetic pole N
The magnetic flux density of No. 11 is 900 gauss, and the ratio of 50% value of each magnetic pole is (50% value of magnetic pole S61) / (50% value of magnetic pole N11)
≈O. 8 and narrowing the width of the magnetic pole S61 with respect to the width of the magnetic pole N11 changes the magnetic flux density of the magnetic field formed between the magnetic pole S61 and the magnetic pole N11 from the developing sleeve 1a to the toner layer thickness regulator 6a. The magnetic flux density increases toward the side, the distance W between the developing sleeve 1a and the conductive belt 10 is in the range of 100 μm to 2 mm, and the absolute value of the peripheral speed of the developing sleeve 1a and the conductive belt 10 are equal to each other. The ratio of the absolute values of the peripheral speed is expressed by (the absolute value of the peripheral speed of the conductive belt 10) / (the absolute value of the peripheral speed of the developing sleeve 1a)> O. It was set to be 5.

As the non-magnetic toner, a negatively chargeable toner having a weight average diameter of 5 μm or more is used, and as the magnetic particles,
A normal magnetic carrier having a weight average diameter of 20 to 100 μm was used.

Between the conductive belt 10 and the developing sleeve 1a, the AC bias generated by the power supply 8 and the DC bias generated by the power supply 7 are applied to the non-magnetic toner charged negatively.
Superimposition was performed so that a Coulomb force from 0 to the developing sleeve 1a was applied.

In the developing device configured as shown in FIG. 4, the magnetic particles forming the brush by the magnetic field between the magnetic pole N11 and the magnetic pole S61 are indicated by the arrow b1 in the figure due to the frictional force with the conductive belt 10. It is conveyed in the rotational direction, returned to the inside of the developing device 3, and falls into the developing device 3 due to gravity.

Further, in the present invention, due to the effect of the AC bias from the power source 8, the nonmagnetic toner is easily peeled off from the magnetic particles even when the adhesive force between the nonmagnetic toner and the magnetic particles is large. Due to the bias effect of 7, the non-magnetic toner attached to the magnetic particles due to the mirroring force or the like is removed from the developing sleeve 1a and the conductive belt 10.
At a position close to the developing sleeve 1a.

As a result, the same effect as described in Example 1 was obtained.

[0069]

As described above, according to the present invention,
A toner layer thickness regulating body having a rotatable constituent member having a permanent magnet having at least two poles arranged therein is disposed in the vicinity of the toner carrying body, and the magnetic flux density increases from the toner carrying body toward the toner layer thickness regulating body. Since it becomes higher, it becomes possible to form a brush of magnetic particles for coating the non-magnetic toner on the surface of the toner carrier, and the rotation direction of the toner layer thickness regulating body is the same as the rotation direction of the toner carrier. By setting the direction, it becomes possible to return the magnetic particles having the brush formed at the position where the toner layer thickness control member and the toner carrier face each other and the non-charged non-magnetic toner to the developing device, and By applying a voltage between the body and the toner layer thickness regulator, the non-magnetic toner adhered to the magnetic particles by the mirroring force or the like is moved from the magnetic particles to the toner carrier. Doo is possible, as a result, the combination of magnetic particles and non-magnetic toner, regardless of the environment,
It has become possible to coat the surface of the toner carrier with only a sufficiently charged non-magnetic toner sufficient to maintain the image density and convey it to the developing area.

As a result, there is an effect that an image defect and a decrease in image density due to the charging defect are less likely to occur.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a second embodiment of the developing device of the invention.

FIG. 3 is a sectional view showing a third embodiment of the developing device of the invention.

FIG. 4 is a sectional view showing a developing device according to a fourth embodiment of the invention.

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

FIG. 6 is a cross-sectional view showing an example of a conventional developing device including a toner layer thickness regulator having a rotatable component.

[Explanation of symbols]

1a ... Development sleeve, 1b ... Permanent magnet, 2 ... Magnetic blade, 3 ... Developer, 4 ... Conveying member, 5 ... Scraper, 6a ... Toner layer thickness regulator, 6b ... Permanent magnet, 6c drive roller, 7 ... DC Power source, 8 ... AC power source, 9 ... Roller, 10 ... Conductive belt, 11 ... Non-magnetic toner, 12 ... Magnetic particles.

Claims (4)

[Claims] 1. A developer having a non-magnetic toner and magnetic particles, a rotatably arranged toner carrier carrying the non-magnetic toner on a surface thereof, and a permanent magnet arranged inside the toner carrier. And a toner layer thickness regulator that regulates the application of the non-magnetic toner on the toner carrier, the toner layer thickness regulator having a rotatable component and arranged near the toner carrier. In addition, the arrangement position thereof is in the vicinity of at least one magnetic pole of the permanent magnet arranged inside the toner carrier, and the rotation direction of the rotatable component is the rotation direction of the toner carrier. In a developing device that is configured to be in the same direction and has a higher magnetic flux density from the toner carrier to the toner layer thickness regulator side, between the toner carrier and the toner layer thickness regulator. DC power supply to apply voltage Dry developing apparatus, characterized by. 2. The developing device according to claim 1, wherein a permanent magnet having at least two poles is arranged inside the toner layer thickness regulating body, and one of permanent magnets arranged inside the toner layer thickness regulating body. One magnetic pole and one magnetic pole of the permanent magnet disposed inside the toner carrier are disposed substantially opposite to each other,
Further, the dry developing device is characterized in that the two magnetic poles disposed opposite to each other have polarities different from each other. 3. The dry developing device according to claim 1, further comprising an AC power supply that forms an alternating electric field between the toner carrier and the toner layer thickness regulator. 4. The dry developing device according to claim 2, further comprising an AC power supply that forms an alternating electric field between the toner carrier and the toner layer thickness regulator.