JP2003307936A - Electrostatic latent image development method, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic developing method in which an area where a latent image is developed with toner is increased by using the entire developing sleeve as a developing area for development, in which image density in a solid part is high and in which a high quality image having a satisfactory solid ground in a solid part is obtained. <P>SOLUTION: A developer carrier disposed opposite an image carrier and incorporating a magnet holds thereon two-component developer containing toner having a number mean particle diameter of 3 to 7 μm by number and magnetic carrier having a weight mean particle diameter of 25 to 45 μm. The developer carrier transports the developer to a developing area between an image carrier and itself. Within the developing area, the magnetic carrier and toner are separated from each other when the gathering naps of the magnetic carrier rise, and development is carried out with the thus obtained free toner. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developing method provided in an image forming apparatus such as a copying machine, a printer or a facsimile, and more specifically, a two-component magnetic brush developing method capable of expanding a developing area. The present invention relates to a developing method capable of obtaining a high-quality image with a high density of solid parts together with a specific carrier.

[0002]

2. Description of the Related Art At present, in an image forming apparatus such as a copying machine, a printer or a facsimile, an image carrier (hereinafter referred to as "photoreceptor") provided with a photoconductive photosensitive layer on its surface and a developer are stored. A toner image is formed by the developing device.

A two-component developer mainly composed of toner and a magnetic carrier (hereinafter simply referred to as "developer") is widely used in a developing device because it can be easily colored. The developer is frictionally charged by stirring and mixing in the developing device, and the electrostatic charge causes the toner to electrostatically adhere to the surface of the magnetic carrier. The magnetic carrier to which the toner is attached is attracted by a magnetic force to the surface of a developer carrying member (hereinafter, referred to as "developing sleeve") having a magnet arranged therein, and is conveyed on the rotating developing sleeve.

In the prior art of the present invention, a magnet for development (hereinafter, referred to as
The term "developing main magnet" is used. ) Is disposed inside the developing sleeve. As the conveyed developer approaches the developing main magnet, a large number of magnetic carriers in the developer gather along the magnetic lines of force of the developing main magnet to form a chain or a chain. Since the large number of ears look like brushes, they are generally called magnetic brushes, and the developing method utilizing the state of the magnetic brushes is called magnetic brush developing. In this magnetic brush development, it is considered that the magnetic carrier, which is a dielectric, increases the electric field strength between the photoconductor and the developing sleeve, so that the toner is developed from the surface of the magnetic carrier at the tip of the brush of the magnetic brush. .

Therefore, until now, the portion without the magnetic brush formed by the spikes of the magnetic carrier has not been used for developing the toner. Therefore, the area where the toner can be developed is limited, so that it is very difficult to increase the amount of toner to be developed under other conditions.

However, in this limited area,
A developing method for obtaining a high-density image has been proposed. For example, Japanese Patent No. 2668781 discloses a developing method in which a two-component developer is used to develop the toner particles carried by the ears of the magnetic particles and the toner particles carried on the developer carrier by an alternating electric field. It is disclosed.

[0007]

However, in the developing method proposed above, the developing area is an area where the magnetic particles are rubbing against each other, and the developing process is performed with the toner particles held by the ears of the magnetic particles in this area. It is difficult to obtain a sufficiently high density image only with toner particles on the agent carrier. In addition, since the magnetic particles have few ears, it is difficult to obtain a smooth high-quality image in which the solid portion is well filled with solids due to the electrode effect.

Therefore, the present invention has been made to solve the above-mentioned problems, and the entire developing sleeve contributes to the development as a developing area, thereby increasing the area where the latent image is developed by the toner. In addition, by appropriately controlling the particle size and particle size distribution of the supply carrier, a high-quality image with high image density in the solid part, good solid filling, and excellent uniformity in the highlight part can be obtained. An object is to provide a developing method that can be obtained.

[0009]

In order to achieve the above object, in the invention (electrostatic latent image developing method) according to claim 1,
A developer bearing member, which is arranged facing the image bearing member and has a magnet inside, carries a two-component developer containing a toner having a number average particle diameter of 3 to 7 μm and a magnetic carrier having a weight average particle diameter of 25 to 45 μm. The developer is conveyed to a developing area formed between the image carrier and the magnetic carrier and the toner are separated from each other when the spikes of the magnetic carrier rise in the developing area. Developing with toner is the most important feature.

According to another aspect of the present invention, a developer carrying member, which is arranged so as to face the image carrying member and has a magnet inside, carries a two-component developer containing toner and a magnetic carrier holding the toner. The developer is conveyed to a development area formed between the image carrier and the electrostatic latent image on the image carrier is developed by the free toner separated from the magnetic carrier surface in the development area. In the developing method described in 1, the magnetic carrier and the toner are separated when the spikes in which the magnetic carriers are gathered rise, and an electric field is formed to move the free toner separated from the magnetic carrier to the image carrier side for development. The main feature is to do.

According to a third aspect of the present invention, in the developing method according to the first or second aspect, the toner used has a number average particle diameter of 3 to 7 μm, and the toner has a coverage of 50 on the carrier. The main feature is that it is between 80% and 80%.

In a fourth aspect of the present invention, in the developing method according to any one of the first to third aspects, the carrier used has a weight average particle diameter Dw of 25 μm to 45 μm, and a particle diameter larger than 62 μm. The content of the carrier is 1 wt% or less, the content of the carrier having a particle size smaller than 22 μm is 3 wt% or less, and 1K.
The main feature is that the magnetic moment in Oe is 76 emu / g or more.

In the invention described in claim 5, claims 1 to 4
In the developing method described in any one of 1 above, the main feature is that the core material of the carrier used is a ferrite selected from MnMgSr ferrite, Mn ferrite, and magnetite.

According to the invention described in claim 6, claims 1 to 4
In the developing method described in any one of 1 above, the main feature is that the carrier used has a resistance of 10 ¹² Ω · cm or more.

According to the invention of claim 7, claims 1 to 4
In the developing method described in any one of 1 above, the main feature is that the resin layer forming the carrier surface to be used is a resin layer containing a silicone resin containing aminosilane as a main component.

According to the invention of claim 8, the inventions of claims 1 to 7
In the developing method according to any one of items 1, the resin layer forming the carrier surface used contains fine particles in the layer,
The main feature is that the silicone resin layer has irregularities derived from fine particles.

According to the invention of claim 9, claims 1 to 7
In the developing method according to any one of items 1 to 3, a resin layer forming a carrier surface to be used is a silicone resin layer containing conductive fine particles and non-conductive fine particles, and the fine particles have irregularities derived from the respective fine particles. The main feature is that there is.

According to a tenth aspect of the present invention, in the developing method according to any one of the first to ninth aspects, the developing method removes toner from the magnetic carrier when the spikes in which the magnetic carrier has gathered stand up. The main feature is to develop by developing an electric field for separating the separated toner from the magnetic carrier and moving the separated toner to the image carrier side.

According to an eleventh aspect of the invention, in the developing method according to the tenth aspect, in the developing method, the powder characteristic and magnetic characteristic of the magnetic carrier and the magnetic characteristic and morphological characteristic of the developing main magnet are determined. The main feature is to set the toner so that the toner is released from the magnetic carrier when the ears that have gathered together stand up.

According to a twelfth aspect of the present invention, in the developing method according to the tenth aspect, the developing method includes the morphological characteristics and electrical characteristics of the developer carrier and the morphological characteristics and electrical characteristics of the image carrier, and The main feature is to set so as to form an electric field for moving the toner separated from the image carrier to the image carrier side.

According to a thirteenth aspect of the present invention, in the developing method according to the tenth aspect, the developing main magnet causes the magnetic brush of the magnetic brush to move by the developing main magnet when the magnetic carrier aggregated ears rise on the developer carrier. The main feature is that the tip is separated from the developer layer in which the magnetic carriers are aggregated on the image carrier.

According to a fourteenth aspect of the invention, in the developing method according to any one of the tenth to thirteenth aspects, a magnetic carrier having a toner on the surface is brought into contact with the latent image carrier in the developing area, The main feature is that the toner is released from the surface of the magnetic carrier, and the released free toner is sprinkled on the image carrier and developed.

According to a fifteenth aspect of the present invention, in the developing method according to any one of the tenth to thirteenth aspects, in the developing method, the magnetic brush formed in the developing area is brought into contact with the image carrier. The main feature is that the toner already developed is released from the image carrier.

According to a sixteenth aspect of the present invention, in the developing method according to any one of the first to fifteenth aspects, a magnetic carrier having toner particles on the surface thereof is gathered in the developing area, and the magnetic carrier surface is formed. A magnetic brush containing free toner to be released is formed, and the toner is released and developed when the spikes of the magnetic carrier rise, and
Development characterized in that a free toner that makes a magnetic brush come into contact with and separates from an image carrier is sprinkled on the image carrier for development, and that the magnetic brush is rubbed or brought close to the image carrier for development. Let's say

According to a seventeenth aspect of the invention, in the developing method according to the sixteenth aspect, in the developing method, the magnetic brush formed in the developing area is brought into contact with the image carrier to release the toner from the image carrier. The main feature is that the toner that has already been developed is released from the image carrier by rubbing or bringing the magnetic brush into contact with or close to the image carrier.

According to an eighteenth aspect of the present invention, in the developing method according to the sixteenth aspect or the seventeenth aspect, in the developing method, the center of the magnetic pole inside the developer carrying member is within the developing area, and the developer carrying direction is set. The main feature is to incline to the downstream side of.

According to a nineteenth aspect of the present invention, in the developing method according to any one of the sixteenth to eighteenth aspects, the developing method is a developer carrier (Vs) and an image carrier (Vp).
And the linear velocity ratio (Vs / Vp) is 0.9 <Vs / Vp <4
The main feature is to be in the range.

According to a twentieth aspect of the invention, in the developing method according to any one of the sixteenth to nineteenth aspects, in the developing method, the free toner that is released from the surface of the magnetic carrier in the developing area is used as an image carrier. The main feature is to develop by an electric field applied between the developer carrier and the developer carrier.

According to the twenty-first aspect of the invention, there is provided the sixteenth aspect.
20. The developing method according to any one of 1 to 19, wherein the developing method is characterized in that the applied electric field is an alternating electric field.

In the twenty-second aspect of the present invention, a two-component developer, which is arranged so as to face the image bearing member and which has a magnet inside and which contains a toner and a magnetic carrier holding the toner, is formed on the surface. Development in which a latent image formed on the surface of an image carrier is developed with toner, which includes a developer carrier that carries the toner and conveys it to the developing area, and an application unit that applies an electric field between the developer carrier and the image carrier. In the apparatus, the main feature is that the developing device includes the carrier and the toner according to any one of claims 1 to 3 to 9.

According to a twenty-third aspect of the invention, an image carrier having photoconductivity and forming a latent image on the surface, a charging device for charging the image carrier, and a device arranged to face the image carrier, An image having a developing device that stores toner and a magnetic carrier that holds the toner on the surface and forms a toner image on the surface of the image carrier, and a transfer device that transfers the toner image formed on the surface of the image carrier to a recording member. A main feature of the image forming apparatus is that the image forming apparatus includes the developing device according to claim 22.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. According to the developing method of the present invention, as shown in each of the following drawings, a magnetic brush is formed in the developing area, which includes the ears of the magnetic carrier C having the toner T and the free toner T to be separated from the surface of the magnetic carrier C. It is a developing method.

FIG. 1 is a schematic view schematically showing the state of the two-component developer in the developing area in the developing method of the present invention. Here, the developing area means that the ears where the magnetic carriers C gather form a magnetic brush or the developing sleeve 1
The area in which the toner T in the developer is developed toward the photoconductor 100 regardless of whether or not a thin developer layer is formed on the surface 11. As shown by A in FIG. 1, the front area of the developing area means that the magnetic carrier C in the developer approaching the vicinity of the main developing magnet has a plurality of magnetic carriers C while having the toner T on the surface. The region where the ears of the magnetic carrier C begin to rise along the magnetic lines of force by gathering to form ears.

Inside the developing sleeve 111, a plurality of magnets are provided. Specifically, a developing main magnet and a developing sleeve 111 for forming a magnetic brush of a two-component developer at a substantially central position where the photoreceptor 100 and the developing sleeve 111 face each other.
Drawing-up magnet, drawing sleeve 1 for drawing up developer on top
A magnet for transporting the developer pumped up onto 11;
Further, a carrying magnet for arranging the developer after the development in the developing device 110 is arranged. These magnets
The developing sleeves 111 are arranged at intervals in the circumferential direction.

FIG. 2 is a schematic diagram showing a situation in which the spikes of the magnetic carrier C rise in the front area A of the developing area in the developing method of the present invention. At the position where the magnet is arranged, a magnetic brush is formed regardless of the polarity of the magnet, and a thin layer is formed between the magnetic poles. As shown in FIG. 2, since the magnetic carriers C that have been confined in the developer layer of the group of the magnetic carriers C have magnetic forces to each other, the magnetic force lines in the normal direction are small between the magnets. Since the magnets adjacent to each other have opposite polarities, the magnetic lines of force in the circumferential direction are large. This causes a force that forms a developer layer, which is a group of thin magnetic carriers C, between the magnets as compared with those on the magnetic poles. And the magnetic carrier C is kept in the group of developer layers.

When this developer layer comes to the position of the developing main magnet, some magnetic carriers C gather to form a spike and rise up. The number of magnetic carriers C gathered to form the ears is generally the developer regulating member 11 shown in FIG.
It is determined by the amount of the developer passing through No. 4, but besides that, the magnetic properties of the magnetic carrier C, the magnitude of the magnetic force of the developing main magnet, the shape of the developing main magnet, and the magnitude of the magnetic force line depending on the arrangement method. And the slope.

Further, since the developing main magnet is fixed, but the developing sleeve 111 is rotating, the angle and the size of the magnetic force line at the position of the spike that starts to rise are also changed. At this time, since the magnetic responsiveness of the magnetic carrier C is delayed, the magnetic brushes are not immediately aligned in the shape along the lines of magnetic force.
Although the magnetic field of the developing main magnet acts, the magnetic polarities of all the magnetic carriers C are directed in the same direction, and the repulsive forces act on each other, though the magnetic field of the developing main magnet acts on the magnetic field. Because of these, the magnetic carrier C
The developer layer is suddenly cracked, and the ears of the magnetic carrier C stand up as a magnetic brush.

Therefore, when the magnetic carrier C forms ears and rises, the toner T trapped in the group of magnetic carriers C is released into the space and is further adsorbed on the surface of the magnetic carrier C. When a large centrifugal force acts on the toner T, the toner T is released from the surface of the magnetic carrier C and released into the developing space to become free toner T.
In addition, the free toner T separated from the surface of the magnetic carrier C
Can be easily moved by a developing electric field or the like, because no electrostatic or physical adhesion with the magnetic carrier C acts.

That is, by forming the magnetic brush having the free toner T, it is possible to increase the amount of the toner T attached to the latent image L on the photoconductor 100, and obtain a so-called developing method having high developability. it can. Further, in the developing method of the present invention, in the first front area A of the developing area, free toner T which can be developed even in a low electric field is generated, so that a developing method having a high developing property can be obtained.

Therefore, the powder characteristics and magnetic characteristics of the magnetic carrier C and the presence state of the toner in the developer are appropriately controlled, and the magnetic characteristics such as the strength of saturation magnetization of the developing main magnet, the width and the magnetic characteristics. By appropriately selecting the morphological characteristics such as the shape, the force acting on the toner T on the surface of the magnetic carrier C can be controlled, and the generation of the free toner T can be optimized.

That is, since the free toner T is generated from the ruptured surface of the developer layer or the surface of the spike-shaped carrier as described above, the free toner T can be delicately ruptured.
Can be increased. By making the carrier particle diameter small, the breakage of the carrier when it stands up is further subdivided, and the amount of toner that faces the space can be increased per unit time, and the amount of free toner generated increases. Although depending on the particle diameter of the toner used, the weight average particle diameter Dw of the carrier is preferably 25 μm to 45 μm. When the carrier diameter is larger than 45 μm, in order to compensate for the amount of free toner T generated, a large moving linear velocity ratio between the developer carrier and the latent image carrier, a large developing electric field, or an alternating electric field is provided. Will be required. When the particle size is smaller than 25 μm, the amount of generated free toner increases, but the magnetic moment per carrier particle decreases, so that the impact force when the developer layer is ruptured and the centrifugal force due to the rotational movement of the magnetic spikes cannot be fully resisted. Carrier particles are often scattered, so-called increase in carrier adhesion and accompanying increase in background stain are observed.

Further, the holding amount for holding the toner on the surface of the carrier needs to be within an appropriate range. The number average particle diameter of the toner must be in the range of 3 to 7 μm in order to smoothly convey the toner and evenly stir the developer while obtaining the sharpness and dot reproducibility of the image. Further, the coverage of the toner on the carrier in the developer is preferably in the range of 50% to 80%.
The coverage on the carrier is obtained as follows.

That is, the particle diameters of the toner and the carrier are subdivided into predetermined particle diameter ranges and calculated in each of these areas (total projected area of the toner) / (total surface area of the carrier), and the sum thereof. Is (total actual projected area of toner) /
The ratio is calculated from (total actual surface area of carrier). By this method, a value close to a substantial coverage can be calculated regardless of the particle size distribution of the toner or carrier.

The particle size distribution of the toner is measured using a Coulter counter to obtain 256 ch histogram data. Using the toner representative diameter Rt for each channel (average value of the particle diameters at the upper and lower ends of the channel) and the number of toner particles included in the channel area nt, the projected area x number of spheres having the representative particle diameter is calculated, and the value is calculated. Is the sum of all channels
_Set to ₁ . s ₁ = Σ (π (Rt / 2) ² × n _t ). Next, the particle mass x number of the representative particle size of each channel is calculated, and the total is set to w ₁ . w ₁ = Σ (4 / 3π (Rt / 2) ³ × σ _t
× n _t ). Here, σ _t represents the true specific gravity of the toner. From the above, s ₁ and w ₁ are used to derive (total projected area per 1 g of toner) = s ₁ × (1 g / w ₁ ).

Similarly, the total surface area of the carrier is also collected as histogram data in which the particle size of the carrier is measured by Microtrac and divided into particle size distributions of 2 μm. Similarly, using the carrier representative diameter Rc for each channel (average value of particle diameters at the upper and lower ends of the channel) and the number of carriers n _c contained in the channel region, the surface area x number of spheres having a representative particle diameter is obtained, Let that value be the sum of all channels s ₂ . s ₂
= Σ (4π (Rc / 2) ² × n _c ) × n _c .

Next, the particle mass of the representative particle size of each channel ×
The number is calculated and the total sum is set to w ₂ . w ₂ = Σ (4 / 3π (R
c / 2) ³ × σ _c × n _c ). Here, σ _c represents the true specific gravity of the carrier. From the above, using s ₂ and w ₂ , (total surface area per 1 g of carrier) = s ₂ × 1 g / w ₂ ) is derived.

The coverage Tn is expressed as Tn = (total projected area per 1 g of toner) × Mt / (total projected area per 1 g of carrier) × Mc, where Mt is the total mass of the toner and Mc is the total mass of the carrier. Therefore, when the toner density is C (%), the following equation (1) is obtained by using the above two equations. (C = Mt / (Mt + Mc)) Coverage Tn = C.St / (1-C) .Sc × 100 (1) St = Total projected area per 1 g of toner Sc = Total surface area per 1 g of carrier C = Toner concentration

If the coverage obtained here exceeds 80%,
Excess toner is generated in the developer. This is because the occupation area of the surface of the carrier with respect to the toner is insufficient, and when observing the developer having a coverage of more than 80%, it is confirmed that the toner in the developer is often not in contact with the carrier. When the developer is used in such a state, a dramatic increase in free toner is observed, but on the other hand, when there is a rapid change in toner concentration such as during toner replenishment, low-charged toner is generated, which causes background stains on the image and However, problems such as contamination of the inside of the machine due to toner scattering are likely to occur. On the other hand, when it is less than 50%, the toner content in the carrier is low, so that the charge amount is apt to increase, the toner and the carrier are strongly electrostatically adhered to each other, or the toner is excessively stressed. Deformation occurs, and the amount of free toner generated decreases.

The behaviors of the magnetic carrier C and the toner T in the front area A of the developing area described here will be explained by the inventors of the present application by a stereoscopic microscope (Olympus SZH10) and a high speed camera (Photron). : FASTCAM-
ULtima-I2) and 9000-4050
This is confirmed by the images taken at a shooting speed of 0 frames / sec. Further, the same is confirmed for the middle area B and the rear area C of the developing area described below.

The magnetic moment of the carrier is also important for the formation of carrier ears. As described above, the formation of the magnetic brush is based on the fact that the carrier layer carried on the sleeve reaches the magnetic pole portion, so that the surface of the carrier layer is magnetized to the same pole and repelled. Further, the generation of the free toner T is due to the impact force at the time of forming the ears and opening of a new developer surface. That is,
By reducing the carrier magnetic moment, the magnetic repulsion force at the tip of the carrier becomes smaller, so the ear can be delicately torn and more free toner can be released to the developing space, but carrier scattering occurs. There is also a problem that the amount increases. The preferable magnetic moment of the carrier is 76 emu / g or more for 1 KOe.

In order to control the breakage of the magnetic spikes, it is necessary that the carrier be magnetized rapidly with respect to the change in the magnetic field and that a desired magnetic moment be obtained. That is, it is necessary to make the magnetic moment of the carrier appropriate and at the same time reduce the residual magnetization of the carrier. Examples of materials having such a high magnetic moment include ferromagnetic materials such as iron and cobalt, magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Cu-Zn-based ferrite, Ni-Zn-based ferrite, and Ba-based ferrite. , Mn-based ferrite, and the like.

Ferrite is generally a sintered body represented by the following formula. (MO) x (NO) y (Fe ₂ O ₃ ) z where x + y + z = 100 mol% and M, N
Are Ni, Cu, Zn, Li, Mg, Mn and S, respectively.
r, Ca, etc., and is composed of a complete mixture of a divalent metal oxide and a trivalent iron oxide. Among them, Mn
MgSr ferrite and Mn ferrite have small residual magnetization and are preferably used. Further, magnetite is also preferably used because it can obtain higher magnetization.

When the carrier thus obtained is used as a two-component developer, the measured electric resistance is 10 ⁷ to 10 ¹⁶ Ω.
It is preferably in the range of cm, more preferably 10
It preferably has an electric resistance of ¹² Ωcm or more. The resistance of the carrier must be properly selected according to the developing process.However, when the resistance value is small, the shape of the spikes of the brush (magnetic brush) of the carrier held on the developer carrying member causes the density of image density to change. It becomes more noticeable and causes problems such as inductive carrier adhesion.

The electric resistance of the carrier is a value obtained from a current value and an applied voltage when the carrier is filled between two parallel electrodes and a potential difference is provided between the electrodes. In particular,
A container having electrodes arranged in parallel at intervals of 2 mm was filled with a carrier, and the DC resistance at a potential difference of 500 V between both electrodes was measured by Yokogawa Hewlett Packard Co. 4329AHi.
It is measured with a gh Resistance Meter.

In order to increase the generation amount of the free toner T, it is effective to provide the carrier surface with irregularities sufficiently small with respect to the toner particle size. The resin layer provided on the surface of the carrier has a form in which fine and uniform irregularities are provided on the surface of a substantially spherical core material. The surface of each part of the unevenness is covered with a resin layer having a uniform composition, and this resin layer prevents toner spent, and has good chargeability, toner retention, and toner development. It is preferable to have both properties. Among them, as the silicone polymer, a silicone resin having appropriate electric resistance and low surface energy is preferably used.

The silicone resin referred to here is a resin having Si-O as a basic repeating unit as described below.

[0057]

[Chemical 1] (In the formula, R is a hydrogen atom, a halogen atom, a hydroxy group,
It represents a methoxy group, a C1-C4 lower alkyl group or a phenyl group. )

As an example of this silicone resin, for example, straight silicone is used, and KR271, KR272,
There are KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406 (manufactured by Toray Dow Corning Silicone Co., Ltd.), and a modified silicone obtained by substituting or adding an organic compound to a part of them. Examples thereof include epoxy-modified silicone, acrylic-modified silicone, phenol-modified silicone, urethane-modified silicone, polyester-modified silicone and alkyd-modified silicone. As an example, epoxy modification: ES-1001N, acrylic modification: KR-5208, polyester modification: KR-
5203, alkyd modified: KR-206, urethane modified: KR-305 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), epoxy modified: SR2115, alkyd modified: SR2110.
(Toray Dow Corning Silicone Co., Ltd.) and the like are typical.

As the carrier resin layer which gives a suitable negatively charged toner, for example, it is preferable that the resin layer contains an organic silicone compound containing nitrogen in its structure. A so-called aminosilane coupling agent having an amino group in X is preferably used.

[Chemical 2] (In the formula, n is an integer of 1 to 3, X is various functional groups having reactivity or adsorptivity with an organic or inorganic substance, and a saturated or unsaturated hydrocarbon chain having a functional group is represented by R
¹ represents an alkyl group, and OR ² represents an alkoxy group. )

[0060]

[Chemical 3]

As a method for forming the coating resin, a known method such as a spray drying method, a dipping method, or a powder coating method can be used.

Further, the irregularities on the carrier are preferably irregularities formed in units of 1/10 or less of the toner average weight diameter, and when the developer is agitated, the chances of contact between the carrier and the toner are increased. However, when the toner is held on the sleeve, since the curvature of the convex portion that is the contact point between the carrier and the toner is small, the physical adhesion to the carrier is reduced, and the toner is uniformly charged and quickly charged. It has developability and is effective in promoting the generation of the toner T free from the carrier.

The formation of such irregularities can be formed by a conventionally known film forming method as described above. That is, a resin solution is applied onto a carrier, or a solution of a monomer, an oligomer, or a polymer that constitutes a resin is applied, and then dried and solidified, or a high molecular weight is obtained by a corresponding chemical reaction, or a chemical film is formed on the surface of the core material. It is possible to intentionally deposit and cure a part of the film-forming material when the film is formed by precipitation, lamination or the like. Most easily, it can be obtained by dispersing a particulate substance in a coating material solution, coating this on a carrier core material, and curing it.
That is, by containing fine particles having a composition different from that of the material forming the carrier surface inside the convex portion, it is possible to arbitrarily form the shape and presence state of the irregularities on the film.

As the fine particles inside the convex portion used here, conventionally known fine particles can be arbitrarily used. Among them, the organic resin fine particles prepared by a dispersion method such as an emulsion polymerization method, a suspension polymerization method, a polymerization method such as a dispersion polymerization method or a phase inversion emulsification method can control the uniformity of the shape and the particle diameter arbitrarily. It is preferably used.

In addition, metal fine particles and inorganic fine particles such as various metal oxide particles can also be used, and among them, metal oxide particles such as silicon oxide, titanium oxide and alumina are easily formed into particles having a uniform fine particle diameter. Various electrical properties and mechanical strength can be obtained depending on the particles obtained and used. It is also important that the fine particles are thermally stable even if the carrier is heated to a high temperature during the condensation curing of the silicone resin.

Further, for the purpose of adjusting the electric resistance, the material constituting the carrier surface may contain the following substances. If necessary, one or more kinds may be used in an appropriate amount. Conductive ZnO, metal powder such as Al, SnO ₂ made by various methods, and Sn doped with various elements
O _2, borides, eg _{TlB 2, ZnB 2, MoB 2} , silicon and conductive polymers carbide (polyacetylene, polyparaphenylene, poly (para - phenylene sulfide), polypyrrole), and carbon black.

It is known that the most suitable silicone compound for the film has a high electric resistance, and the carrier obtained by providing these resin layers also generally has a high resistance. Therefore, as a resistance adjusting agent for film resistance, its volume resistance is 1
It is preferable to use at least one kind of particles having a particle size of 06 or less.

Further, it is important that the conductive fine particles introduced for the purpose of adjusting electric resistance have a sufficiently small particle diameter with respect to the coating and can be uniformly dispersed in the coating. This is because it is not preferable to disturb the uneven morphology of the coating by the introduction of these conductive fine particles, and depending on the coating morphology,
It is important in order to obtain the effects expected for uniform charging, toner retention and developing properties. As a material satisfying those conditions, fine particles of metal oxide subjected to conductive treatment, carbon black and the like are preferably used.

On the other hand, when an extremely low resistance substance such as carbon black is dispersed and used in the silicone film, the electrical characteristics of the film sensitively change with respect to the carbon black content. Need attention. For example, it is difficult to handle such that the electric resistance between carriers is likely to be nonuniform, and the characteristics of the obtained carrier are difficult to stabilize due to slight process variations in the manufacturing process. This can be avoided by accurately controlling the content and homogenizing the dispersibility in the film, but the electrical resistance control material contained in the film is a mixture of conductive carbon particles and non-conductive metal oxide particles. It is also possible to use.

In the developing method of the present invention, as shown by B in FIG. 1, the toner T is sprinkled on the photoconductor 100 from the magnetic carrier C having the toner T on the surface in the middle area of the developing area for development. It is a thing. The scattering of the toner T on the photoconductor 100 occurs when the ears of the magnetic brush come into strong contact with the photoconductor 100. FIG. 3 shows that the ears of the magnetic carrier C in the middle area B of the developing area in the developing method of the present invention are the photoreceptor 100.
It is a schematic diagram which shows the situation which strongly contacts.

On the developing sleeve 111, the size of the spikes formed by the aggregation of the magnetic carriers C in the middle area B of the developing area, particularly the height thereof, is determined by the particle size of the magnetic carrier C as described above. It is determined by powder characteristics, magnetic characteristics such as strength of saturation magnetization, magnetic characteristics such as strength of saturation magnetization of the developing main magnet, and morphological characteristics such as width and shape. Therefore, in the middle area B of the developing area, the ears of the magnetic carrier C on the developing sleeve 111 are moving at substantially the same speed as the developing sleeve 111 except when slipping on the developing sleeve 111. Therefore, when the height of the bristles of the magnetic carrier C is higher than the distance between the developing sleeve 111 and the photoconductor 100, both the speed of rising along the magnetic line of force of the developing main magnet and the peripheral speed of the developing sleeve 111. Holding photoreceptor 10
Contact 0 strongly.

Before making strong contact with the photoreceptor 100,
Even if the ears of the magnetic carrier C are completely raised, the distance between the developing sleeve 111 and the center of the developing area of the photoconductor 100 is the shortest, so that the ears of the magnetic carrier C are gradually narrowed. If the height of the magnetic carrier C is larger than that of the closest portion between the developing sleeve 111 and the photoconductor 100, the magnetic carrier C will be moved toward the developing sleeve 111. It strongly contacts the photoconductor 100 at a speed that cancels the peripheral speed of the photoconductor 100 from the peripheral speed of. At this time, the toner T electrostatically adhered to the magnetic carrier C is separated from the surface of the magnetic carrier C by an impact, and the inertial force of the motion due to the centrifugal force and the electric field due to the latent image L on the surface of the photoconductor 100 are generated. Development is performed on the photoconductor 100 by the electric field applied between the developing sleeve 111 and the photoconductor 100.

In the developing method of the present invention, the toner T is developed from the magnetic carrier C by rubbing or bringing the magnetic brush into contact with the photosensitive member 100 in the rear area of the developing area indicated by C in FIG. Is. Here, the rear area C of the developing area is an area where the magnetic brush of the magnetic carrier C is conveyed on the developing sleeve 111 while rubbing against or close to the photoconductor 100.

FIG. 4 is a schematic view showing a situation in which the toner T is developed in the rear area C of the developing area in the developing method of the present invention. An electric field for developing the toner T is normally applied between the developing sleeve 111 and the photoconductor 100.

FIG. 5 is a schematic diagram showing a state in which a DC electric field is applied in the reversal development method. In the organic photoreceptor 100 that uses an organic pigment as a carrier generating material, generally, a negative charge is often added.

In the developing system, the polarity of the charged charges on the photosensitive member 100 is not a big problem. Further, when writing with a laser beam, the character portion is exposed in order to reduce the writing amount. Therefore, the charged charges in this portion are neutralized by the holes generated from the carrier generation material, and as shown in FIG. , The potential of the character part decreases. A negative electric field is applied to the developing sleeve 111 to the character portion to develop the negative toner T. In the rear area C of the developing area, the photoconductor 1
The toner T on the magnetic carrier C having a space opened to the 00 side is statically charged on the photoconductor 100 by the electric field between the photoconductor 100 and the developing sleeve 111 and the electric field generated between the photoconductor 100 and the magnetic carrier C. The latent image L is developed.

On the other hand, since the toner T has been developed in the front area A of the developing area or the middle area B of the developing area, the amount of the toner T present on the surface is reduced and the magnetic carrier C having an excessive charge amount is exposed. In order to move while rubbing the body 100,
The toner T, which has been previously developed, catches up with the toner T and comes into strong contact with the toner T, and the electrostatic Coulomb force generated by being charged with opposite polarities causes the magnetic carrier C to be attracted to the surface of the photoconductor. Remove from 100. In this case, mainly in the non-image portion on the photoconductor 100, since the electrostatic charge by the charging device is small, the electric field for attracting the toner T to the photoconductor 100 is small, so that the toner T in the non-image portion is small.
Often leave. Therefore, it is possible to prevent background stains in the non-image portion and obtain a high-quality image.

Further, the developing method of the present invention is applied to the photoconductor 100.
And a developing sleeve 111 having a magnet inside, carries on its surface a two-component developer containing a toner T and a magnetic carrier C holding the toner T.
The developing sleeve is conveyed to a developing area formed between
11 In the developing method of developing the latent image L formed on the surface with the toner T, the developing sleeve 111 is
A magnetic brush is formed which includes a pair of magnetic carriers C having the toner T on the surface and free toner T which is separated from the surface of the magnetic carrier C, and separates the toner T when the pair of the magnetic carrier C stands up. The magnetic brush formed in the developing area is brought into strong contact with the photoconductor 100 to cause the toner T to be scattered on the photoconductor 100 to develop the magnetic carrier C in the developing area. It is a developing method of developing by rubbing against or adhering to.

In the front area A in the developing area, the magnetic carriers C aggregate to form ears, and the toner T is separated from the magnetic carriers C when rising. By applying an electric field for development to this, it is possible to develop directly toward the photoconductor 100. Further, in the middle area B in the developing area, the ears of the magnetic carrier C further contact the photoconductor 100, and the toner T on the magnetic carrier C is scattered on the photoconductor 100 to form the latent image L of the photoconductor 100. To develop. further,
Due to this contact, the toner T on the photoconductor 100 which has been previously developed is adsorbed and collected again on the magnetic carrier C. As a result, the toner T developed in the non-image area or the low-potential image area by the development in the front area A and the middle area B is pulled back, so that a high-quality image is obtained. Further, in the rear area C, the magnetic carrier C at the tip of the magnetic brush rubs or approaches the photoconductor 100, and the toner T develops the latent image L on the photoconductor 100 by the applied electric field.

Further, due to this rubbing or proximity, the toner T is detached from the previously developed photoconductor 100 and adhered onto the magnetic carrier C again. As a result, in the development in the rear area C, the developed toner T is pulled back to the non-image area or the low-potential image area, so that a high-quality image is obtained. Therefore, in the developing method of the present invention, the developing sleeve 11
The entire surface of the first photoconductor 100 facing the photoconductor 100 can be used as a development area. Among them, by controlling the movement mode of the magnetic carrier C focusing on the three regions where the movement mode of the magnetic carrier C is characteristic, the amount of toner on the photoconductor 100 can be increased and a high-quality image can be obtained. .

In the developing method of the present invention, the center of the magnetic pole inside the developing sleeve 111 is within the developing area.
A developing method in which the developer is inclined to the downstream side in the developer conveying direction is preferable. As a result, the front area A of the developing area can be widened, and the amount of toner T to be separated and developed when the spikes of the magnetic carrier C rise can be increased.

Further, in the developing method of the present invention, the linear velocity (Vs) of the developing sleeve 111 and the linear velocity (V
p), the linear velocity ratio (Vs / Vp) is 0.9 <Vs / Vp
The developing method is within the range of <4. Development sleeve 111
The photoconductor 100 and the photoconductor 100 rotate in the same direction in the facing portions. Even if the linear velocity of the developing sleeve 111 is lower than that of the photoconductor 100, that is, the linear velocity ratio (Vs / Vp) is 1
Even below, since there is sufficient toner T to be released from the surface of the magnetic carrier C, it becomes possible to maintain a large amount of toner adhered to be developed. The linear velocity ratio (Vs / Vp) is set to a linear velocity ratio larger than 0.9, and the toner T developed by the rotation of the developing sleeve 111 is increased to obtain an image with high image density. Depending on the amount of the free toner T, there is still a possibility that the linear velocity ratio can be further reduced.

When the linear velocity ratio (Vs / Vp) is increased, the impact of contacting the photoconductor 100 in the middle area B of the developing area becomes large, and the amount of toner adhered to be scattered and developed increases. However, the toner T released from the photoconductor 100 due to the impact increases. Further, when the magnetic brush rubs or approaches the photoconductor 100 in the rear area C of the developing area, the number of times the magnetic brush comes into contact with the ears of the magnetic carrier C is increased, so
The amount of toner to be released from 00 increases. In particular, when the linear velocity ratio (Vs / Vp) is 4 or more, the trailing edge white spots in the halftone portion and the blurring of the horizontal thin line image increase, so that the linear velocity ratio (V
s / Vp) is preferably less than 4. The applied electric field is particularly preferably an alternating electric field generated by superimposing direct current and alternating current.

FIG. 6 is a schematic diagram showing a state in which an alternating electric field of direct current and alternating current is applied in the reversal development method. As with the DC electric field described above, for example, the negative polarity toner T
Are developed by an electric field applied between the developing sleeve 111 and the photoconductor 100. In this case as well, since the magnetic carrier C on the developing sleeve 111 is a dielectric, an electric field in which the electric field is further emphasized is generated in the ears where the photoconductor 100 and the magnetic carrier C are gathered. The adhered toner T develops the electrostatic latent image L on the photoconductor 100. Further, since the alternating electric field is applied, the toner T on the photoconductor 100 is developed and moves so as to vibrate, and the toner T is gradually aligned with the latent image L to obtain a high-quality image. Also here, when the brush of the magnetic brush is close to the photoconductor 100, an electric field emphasized by the magnetic carrier C is generated, so that the toner T violently moves to vibrate in this portion, and the latent image is further generated. It is possible to obtain a high-quality image that is faithfully aligned with L.

[0085]

EXAMPLES Next, examples of the developing method of the present invention will be described. Parts herein are by weight.

Production Example of Developer: The carrier and toner applied to the present invention will be described below. As the carrier core material, the coating resin dispersion liquid is applied to the ferrite and magnetite powder shown in Table 1 to provide the resin coating layer.

[0087]

[Table 1]

A specific manufacturing example of the carrier will be shown. (Production Example of Carriers A to F) Silicone Resin (SR24
11: To the solid content of Toray Dow Corning Silicone Co., Ltd., 2.5 wt% of conductive carbon (Lion Akzo Co., Ketjen Black EC-DJ600) and 3 wt% of aminosilane coupling agent having the following structure were added,
A homogenizer was used for dispersion for 30 minutes, and the dispersion was diluted to a solid content of 10 wt% to obtain a dispersion.

[0089]

[Chemical 4]

As the carrier core material, the core material A described in Table 1 is used.
5 kg of the above, the coating resin dispersion was applied in an atmosphere of 100 ° C. using a fluidized bed type coating apparatus.
Further, the obtained coated carrier was heated at 220 ° C. for 2 hours to obtain carrier A. The film thickness was adjusted by the amount of coating liquid. Similarly, coatings were similarly formed on the core materials BF to obtain carriers BF.

(Production Example of Carrier G) In the production examples of Carriers A to F, the core material particles D were used, and conductive carbon (Ketjen Black EC manufactured by Lion Akzo Co., Ltd.) was used in the dispersion.
-DJ600) 2.5 wt% and further alumina fine powder (Sumiko Random AA-04 manufactured by Sumitomo Chemical Co., Ltd. 0.
4 μm) 2 wt% was used, and a film was formed in the same manner except that the aminosilane coupling agent was 5 wt% to obtain a carrier G.

(Production Example of Carrier H) In the production examples of Carriers A to F, the core material particles D were used and conductive carbon (Ketjen Black EC manufactured by Lion Akzo Co., Ltd.) was used in the dispersion liquid.
-DJ600) 0.5 parts and conductive titanium oxide (ET-300W manufactured by Ishihara Sangyo Co., Ltd.) 5 parts were added, and a coating was similarly formed using 5 wt% of the addition amount of aminosilane.
Got

As the toner, all the toners prepared by the conventionally known method are used, and an example thereof is shown here. (Production Example of Toner) Polyester resin 92 parts Carnauba wax No. 1 product 5 parts Chromium-containing azo compound 3 parts After thoroughly mixing the above substances with a blender, melt-kneading them with a twin-screw extruder and letting them cool. Coarse pulverization was performed with a cutter mill, followed by fine pulverization with a jet airflow type fine pulverizer, and further, base particles having a desired particle size distribution were obtained with an air classifier. Further, the hydrophobic silica fine particles (R9
72 Nippon Aerosil Co., Ltd.) 0.7 part and hydrophobic acid value titanium (MT150A isobutyltrimethoxysilane treated product hydrophobizing treatment Teika Co., Ltd.) 0.1 part were added, mixed with a Henschel mixer and similarly air-combed. Toners A to C were obtained. The respective particle size distributions are as follows: Toner A, number average diameter 6.2 μm weight average diameter 7.1 μm toner B, number average diameter 4.1 μm weight average diameter 5.2 μm toner C, number average diameter 5.1 μm weight average diameter 7. It was 3 μm.

Examples of Developing Means: Embodiments of developing means will be illustrated below. FIG. 7 shows an embodiment of an image forming apparatus to which the developing method of the present invention is applied. Around the photoconductor 100, a charging device for charging the surface of the photoconductor 100, exposure including a laser beam for forming a latent image L on the uniformly charged surface, and toner charged on the latent image L on the surface of the photoconductor 100. T
Developing device 110 that forms a toner image by attaching
A transfer device for transferring the formed toner image on the photoconductor 100 to a recording sheet, a cleaning device for removing the residual toner T on the photoconductor 100, and a charge removal for removing the residual potential on the photoconductor 100. The devices are arranged in order (other than the developing device 110, not shown). Developing device 110
Is arranged on the left side of the photoconductor 100.

In such a structure, the surface of the photosensitive member 100 is uniformly charged by the charging roller of the charging device.
Form an electrostatic latent image L by exposure, and the developing device 11
0 forms a toner image. The toner image is transferred from the surface of the photoconductor 100 to a recording paper conveyed from a paper feed tray (not shown) by a transfer device such as a transfer belt. The recording paper electrostatically attached to the photoconductor 100 during this transfer is separated from the photoconductor 100 by the separation claw. Then, the toner image on the unfixed recording paper is fixed on the recording paper by a fixing device (not shown). On the other hand, the toner T not transferred and remaining on the photoconductor 100 is removed and collected by the cleaning device. The photoconductor 100 from which the residual toner T has been removed is initialized by a charge eliminating lamp and is subjected to the next image forming process.

In the developing device 110, the developing sleeve 11
1 is arranged close to the photoconductor 100, and a developing region is formed in both facing portions. In the developing sleeve 111, a non-magnetic material such as aluminum, brass, stainless steel, or conductive resin is formed into a cylindrical shape, and the developing sleeve 111 is rotated clockwise by a rotation driving mechanism (not shown). .

In this embodiment, the diameter of the photosensitive member 100 is 90 mm, the linear velocity of the photosensitive member 100 is set to 156 mm / sec, and the sleeve diameter of the developing sleeve 111 is 18 mm.
Thus, the linear velocity of the developing sleeve 111 is set to 214 mm / sec. Therefore, the ratio of the sleeve linear velocity to the photoconductor linear velocity is 1.4. In the present embodiment, the required image density can still be obtained even if the ratio (Vs / Vp) of the linear velocity of the developing sleeve 111 to the linear velocity of the photoconductor 100 is lowered to 0.9 at the minimum.

Further, the photosensitive member 100 and the developing sleeve 111
The developing gap, which is the interval between the and, is set to 0.6 mm. In the conventional development gap, the carrier particle size is 50μ.
If m, it is preferably set to 0.65 mm or less, in other words, set to 13 times or less the magnetic carrier C diameter. If the developing gap becomes too narrow, the magnetic brush will move to the photoreceptor 10.
Since it comes into contact with 0 in a wide range, direction dependency such as horizontal line thinning and trailing edge whiteout is likely to occur. On the contrary, if the development gap is widened, a sufficient electric field cannot be obtained, and image defects such as unevenness occur in isolated dots or solid portions. Although it is possible to increase the applied voltage in order to maintain the electric field strength, an abnormal image such as a so-called white spot in a solid portion due to discharge is likely to occur.

At the upstream side of the developing area in the developer conveying direction (clockwise direction in the figure), the height of the chain of the developer chain, that is, the layer thickness that regulates the thickness of the developer layer on the developing sleeve 111. A doctor blade is provided as a regulating member. The doctor gap, which is the distance between the doctor blade and the developing sleeve 111, is
It is set to 0.65 mm. Conventionally, as the doctor blade, a plate-shaped one made of only a non-magnetic material was used, but the doctor blade in the present embodiment is
It has a structure in which a plate made of a magnetic material is joined to a conventional non-magnetic plate. The use of the magnetic material facilitates formation of magnetic ears having a uniform height, as will be described later.

A stirring screw for pumping up the developer in the developing casing to the developing sleeve 111 while stirring the developer is provided in a region of the developing sleeve 111 on the side opposite to the photosensitive member 100. The developer in the developing casing is a developer composed of the toner T and the magnetic carrier C, and the developer is mixed and stirred by a stirring screw rotating at a rotation speed of 152 rpm by a driving unit (not shown), and the developing sleeve 11
As shown in FIG. 7, a magnetic roller body that forms a magnetic field so as to make the developer stand on the peripheral surface of the developing sleeve 111 is fixedly provided in the inside of the apparatus 1. The magnetic carrier C of the developer forms a bristles of the magnetic carrier C on the developing sleeve 111 so as to follow the magnetic force lines in the normal direction emitted from the magnet roller body, and the magnetic carrier C forming the bristles.
The charged toner T is attached to the magnetic brush. The magnetic brush is conveyed in the same direction as the developing sleeve 111 by the rotation of the developing sleeve 111. The magnet roller body has a plurality of magnetic poles (magnets). Main developing magnet P ₁ for developing the developer in the developing area, developing sleeve 1
A magnet P ₃ for drawing up the developer, magnets P ₄ , P _{5 for} carrying the drawn up developer to the developing area, and a magnetic pole P ₂ for carrying the developer in the area after development are provided on the surface 11.
The magnets P ₁ , P ₃ , P ₄ , P ₅ and P ₂ are arranged in the radial direction of the developing sleeve 111.

Particularly, the main magnet P ₁ forming the developing main pole is
Although it is composed of a magnet having a small cross-section, it is also possible to use a samarium alloy magnet, particularly a samarium cobalt alloy magnet. Among the rare earth metal alloy magnets, a typical iron neodymium boron alloy magnet has a maximum energy product of 35.
It is 8 kJ / m ³ , and the maximum energy product of the iron neodymium boron alloy bonded magnet is around 80 kJ / m ³ .
With such a magnet, unlike the conventional magnet, the required surface magnetic force of the developing sleeve 111 can be secured even if the size is considerably reduced. The maximum energy product of conventional ferrite magnets and ferrite bonded magnets is around 36 kJ / m ³ , 2
It is around 0 kJ / m ³ . If it is permissible to increase the sleeve diameter, a ferrite magnet or ferrite bonded magnet can be used to increase the shape, or the magnet tip facing the sleeve can be made finer to reduce the half-value central angle. It is possible.

In the present embodiment, the magnet P ₃ for drawing up the developer on the developing sleeve 111, the magnet P ₅ for carrying the drawn up developer to the developing area, and the developer for carrying the developer in the area after the development. The magnet P ₂ forms an N pole, and the developing main magnet P 1 and the magnet P ₄ that conveys the drawn up developer form an S pole. The downstream magnet P ₂ forming the developer carrying magnetic pole has a function of assisting formation of the magnetic force of the main magnetic pole, and if it is too small, carrier adhesion occurs. The magnetic brush is transported in the same direction as the developing sleeve 111, that is, in the clockwise direction by the rotation of the developing sleeve 111.

As shown in FIG. 8, the peak position M1 of the magnetic force in the normal direction of the main developing magnetic pole P _{1 on} the developing sleeve 111 is from the closest position M0 between the photosensitive member 100 and the developing sleeve 111 to the photosensitive member 100. The respective magnets of the magnet roller body are arranged so as to be located on the downstream side in the moving direction (counterclockwise direction) of the magnets. In other words, the peak position M1 of the magnetic force is 0 to 30 with respect to the closest position M0. I am trying to shift only the angle. This is because the generation portion of the free toner T in the initial stage when the magnetic brush is formed is
Is located as much as possible in a region where the latent image L of the photoconductor 100 can be moved to the image portion. Desirably, the portion where the free toner T is generated in the developing region front area A is the closest position M0. To be opposed to. The polar angle between the magnets P ₁ and P ₅ is 60 degrees, and the point at which the magnetic force becomes 0 in the middle of both magnets is 30 degrees. Further in other words, as the magnetic brush rises at closest position M0 or near, or foot part of the magnetic field lines of the main developing magnetic pole P ₁ in the upstream side in the movement direction of the photosensitive member 100 is closest position M0 or near the It is intended to be located.

With this structure, most of the cloud-like or smoke-like free toner T generated in the front area A of the developing area where the magnetic brush is formed easily moves to the image portion of the photoconductor 100 due to the developing electric field. Become. This development situation will be described step by step with reference to FIG. FIG. 9 is a schematic diagram showing a situation in which the developing method according to the first embodiment develops the toner T in the developing area.

First, as shown in FIG. 9A, in the developing area front area A where the magnetic brush is formed, that is,
At the position where the magnetic brush rises from the state of being pressed against the developing sleeve 111, a space where the toner T can move due to impact force, centrifugal force, etc. is formed, and the ears and ears where the toner T on the magnetic carrier C and the magnetic carrier C gather. The toner T sandwiched between and is released. As a result, many free toners T are generated in a cloud shape or a smoke shape.

As shown in FIG. 9B, the free toner T group is attracted to the image portion of the photoconductor 100 by the developing electric field and developed. In the non-image portion, the electric field is directed to the developing sleeve 111 side, and the loose toner T returns to the magnetic carrier C or moves onto the developing sleeve 111. As a result, it is possible to improve the use efficiency of the toner T and prevent the inside of the device from being contaminated due to toner scattering. Further, in the present embodiment, an alternating electric field is applied by an alternating electric field applying unit (not shown) at a portion where the photoconductor 100 and the developing sleeve 111 face each other.

Further, in the present embodiment, the developing area middle region B
Since the magnetic brush is in contact with the photoconductor 100 in the rear area C, the magnetic carrier C at the tip of the magnetic brush (photoconductor 10
The electrode effect works between the carrier (close to 0) and the photoconductor 100, and the toner layer in the image area can be made more uniform, and the scumming toner T in the non-image area can be efficiently scavenged.
This effect is also effective when a DC bias is applied. Further, as compared with the conventional two-component contact developing method, the time during which the magnetic brush is in contact with the photoconductor is shorter, so that the direction dependency such as the thinning of the horizontal line and the trailing edge white spot does not occur.

As described above, due to the alternating electric field and the two-component contact development, the toner T reciprocates (vibrates) between the magnetic carrier C at the tip of the magnetic brush and the photosensitive member, as shown in FIG. 9C. To do. The reciprocating movement of the toner T promotes uniformization of the toner layer in the image portion to bring about high image quality with good dot reproducibility, and brings a skiving effect to the background toner T in the non-image portion.

Further, the results of carrying out image evaluation by loading the carrier prepared in the manufacturing example of the carrier, the carrier prepared in the manufacturing example of the toner, and the developer composed of the toner into the copying machine having the exemplified construction, will be shown as an example. Here, the developing sleeve 11 for the photosensitive member
The linear velocity ratio of 1 was set to 1.4. The developing conditions are a belt potential of −700 V, an image portion potential of −100 V, and a non-image portion potential of −6.
An alternating electric field was used in which a rectangular wave having a Vp-p of 1000 V as an AC component and a frequency of 2 kHz was superimposed on 50 V, a developing electric field: a DC component of -500 V.

Image evaluation was carried out as follows. Saturated ID:
A black solid image is output, the image density is measured by a Macbeth reflection densitometer at arbitrary three points on the paper surface, and the average value is obtained. ◎: 1.4 or more (very good) ○: 1.3 to 1.4 (good) △: 1.2 to 1.3 (somewhat bad) ×: less than 1.2 (bad) (x is unacceptable) Level).

Halftone uniformity: 600 dot / inch and 150 line / inch halftone dot image patterns (16 gradations) are output for both main scanning and sub-scanning, and dot dropout, gradation and density uniformity are visually observed in four stages. evaluated. ⊚: Very good ○: Good Δ: Slightly bad ×: Poor (x is an unacceptable level). Background stain: A blank image is output and toner contamination on the background is 4
It was visually evaluated in stages. ⊚: Very good ○: Good Δ: Slightly bad ×: Poor (x is an unacceptable level).

The results of the examples are shown in Table 2 below.

[Table 2]

Specific examples of the image forming apparatus of the present invention will be described below. The image forming apparatus of the present invention is an image forming apparatus including the above developing method. FIG. 10 is a schematic diagram showing the configuration of the image forming apparatus of the present invention. In the color copying machine of the present embodiment, the writing optical unit 400 as an exposing means.
Converts the color image data from the color scanner 200 into an optical signal and performs optical writing corresponding to the original image,
An electrostatic latent image L is formed on the photoconductor 402, which is an image carrier. The writing optical unit 400 includes a laser diode 404, a polygon mirror 406, a rotation motor 408 for the polygon mirror 406, an f / θ lens 410, a reflection mirror 412, and the like. The photoconductor 402 is rotated in the counterclockwise direction as indicated by the arrow, and around the photoconductor cleaning unit 414, the charge eliminating lamp 416, the potential sensor 420, and the rotary developing device 422, selected development is performed. An apparatus 438, a development density pattern detector 424, an intermediate transfer belt 426, etc. are arranged.

The rotary developing device 422 has a black developing device 428, a cyan developing device 430, a magenta developing device 432, a yellow developing device 434, and a rotation driving unit (not shown) for rotating each developing device. There is. Each developing device has a configuration similar to that of the developing device 4 shown in the above embodiment. The same applies to the conditions and specifications of the magnetic carrier C. In the standby state, the rotary developing device 422 is set to the black developing position, and when the copy operation is started, the color scanner 200 starts reading the black image data at a predetermined timing. Based on the above, the optical writing by the laser beam and the formation of the electrostatic latent image L (black latent image L) are started.

In order to develop from the tip of the black latent image L, the latent image L is placed at the developing position of the black developing device 428.
Before the leading end reaches, the developing sleeve 111 starts rotating to develop the black latent image L with the black toner T. Then, after that, the developing operation of the black latent image L area is continued, but when the trailing edge of the latent image L passes the black developing position, the developing position for black immediately rotates to the developing position of the next color. The developing device 422 rotates. The operation is completed at least before the leading end of the latent image L formed by the next image data arrives. When the image forming cycle is started, first, the photoconductor 402 is rotated in the counterclockwise direction as indicated by the arrow, and the intermediate transfer belt 426 is rotated in the clockwise direction by a drive motor (not shown). With the rotation of the intermediate transfer belt 426, black toner image formation, cyan toner image formation, magenta toner image formation, and yellow toner image formation are performed, and finally black (B
k), cyan (C), magenta (M), yellow (Y)
In this order, the toner images are formed by being superposed on the intermediate transfer belt 426.

The intermediate transfer belt 426 is stretched around a drive roller, a transfer opposing roller, a cleaning opposing roller and a driven roller group, and is driven and controlled by a drive motor (not shown). The black, cyan, magenta, and yellow toner images sequentially formed on the photoconductor 402 are accurately aligned on the intermediate transfer belt 426, thereby forming a four-color belt transfer image. The belt transfer image is collectively transferred to a sheet by a transfer corona discharger.

Each recording paper cassette 4 in the paper supply bank 456
58, 460 and 462 are cassettes 464 in the main body of the apparatus.
Various sizes of paper different from the size of the paper accommodated in the paper are stored in the paper storage roller 46.
The sheet 6 is fed and conveyed in the direction of the registration roller pair 470. In FIG. 6, reference numeral 468 indicates a manual paper feed tray for OHP paper, thick paper, and the like. At the time when image formation is started, the paper is fed from the paper feed port of any one of the above cassettes and stands by at the nip portion of the registration roller pair 470. Then, when the front end of the toner image on the intermediate transfer belt 426 reaches the corona discharger, the registration roller pair 470 is driven so that the front end of the paper coincides with the front end of the image, and the registration of the paper and the image is performed. .

In this way, the paper is transferred to the intermediate transfer belt 4
26 and is passed over a corona discharger connected to a positive potential. At this time, the sheet is positively charged by the corona discharge current, and the toner image is transferred to the sheet. Subsequently, the sheet is destaticized when passing through a portion of a destaticizing brush (not shown) arranged on the left side of the corona discharger in the figure, and is separated from the intermediate transfer belt 426 and transferred to the sheet conveying belt 472. The sheet on which the four-color superimposed toner images have been collectively transferred from the intermediate transfer belt 426 is conveyed by the sheet conveying belt 472 to the fixing device 470 of the belt fixing system, and the fixing device 4
At 70, the toner image is fixed by heat and pressure. The fixed paper is ejected to the outside of the apparatus by the ejection roller pair 480 and is stacked on a tray (not shown). This gives a full color copy.

In this embodiment, the rotary developing device 422 is arranged beside the photoconductor 402, but if it is arranged on the lower side, the toner scattering prevention function in the developing device 4 in the above embodiment can be improved.

[0120]

As described above, according to the first aspect of the invention, the developer carrying member, which is arranged so as to face the image carrying member and has a magnet therein, is a toner having a number average particle diameter of 3 to 7 μm. A two-component developer containing a magnetic carrier having a weight average particle diameter of 25 to 45 μm is carried, the developer is conveyed to a developing area formed between the carrier and the magnetic carrier, and the magnetic carrier is aggregated in the developing area. By separating the magnetic carrier and the toner when the spikes rise and developing with the obtained free toner, the developing area is set in a wider range than the conventional developing area, and the toner in the developing area is It is possible to provide a developing method in which an image having a high solid density in a solid portion is obtained by increasing the amount of development. Carrier diameter is 4
When it is larger than 5 μm, the amount of free toner generated is small and the developability is low, and when it is smaller than 25 μm, the amount of free toner generated is large, but carrier particles are scattered and so-called carrier adhesion is increased. It is possible to prevent such a defect that an increase in background soiling is observed.

According to the second aspect of the present invention, the developer carrier, which is arranged so as to face the image carrier and has a magnet therein, carries the two-component developer containing the toner and the magnetic carrier holding the toner. Then, the developer is conveyed to a developing area formed between the developer and the image carrier, and in the developing area, the electrostatic latent image on the image carrier is developed by the free toner separated from the surface of the magnetic carrier. In the developing method according to Item 1, when the spikes in which the magnetic carriers are gathered rise, the magnetic carrier and the toner are separated from each other, and an electric field is formed to move the free toner separated from the magnetic carrier to the image carrier side. By developing, the toner developed on the photoreceptor is separated by the magnetic carrier at the tip of the magnetic brush,
It is possible to provide a developing method for obtaining a high-quality image in which the solid portion is well filled with solid, the non-image portion is less fogged, and the horizontal fine lines and the sharpness of characters are excellent. Further, by making the magnetic brush and the photoconductor non-contact with each other, it is possible to provide a developing method for obtaining an image which is free from roughness in the halftone portion and has excellent sharpness of horizontal fine lines and characters.

According to the invention of claim 3, claim 1 or 2
In the developing method described above, the number average particle diameter of the toner used is 3 to 7 μm, and the coverage of the toner on the carrier in the developer is 50% to 80%. The amount of toner to be retained on the surface of the toner can be set in an appropriate range, while toner sharpness and dot reproducibility are obtained, the toner is smoothly conveyed, the developer is evenly stirred, and the solid portion It is possible to provide a developing method for obtaining an image having high solid density and less background stain.

According to the invention of claim 4, claims 1 to 3
In the developing method according to any one of items 1 to 5, the weight average particle diameter Dw of the carrier used is 25 μm to 45 μm,
The content of carriers having a particle size larger than 62 μm is 1
wt% or less, the content of carriers having a particle size smaller than 22 μm is 3 wt% or less, and 1 KOe
By the developing method characterized in that the magnetic moment at 76 emu / g or more, the magnetic moment of the carrier becomes a preferable value for the formation of carrier spikes, the generation of the free toner T is moderated, and the carrier scattering is suppressed.
It is possible to provide a developing method for obtaining an image in which the solid portion has a high solid density.

According to the invention of claim 5, claims 1 to 4
In the developing method described in any one of 1, the core material of the carrier used is a ferrite selected from MnMgSr ferrite, Mn ferrite, and magnetite. It is possible to provide a developing method for obtaining a high image.

According to the invention of claim 6, claims 1 to 4
In the developing method described in any one of 1 above, the carrier used has a resistance of 10 ¹² Ω · cm or more, and when the resistance value is small, the carrier retained on the developer carrier is It is possible to provide a developing method for obtaining a high image by preventing a phenomenon in which the shape of the ears of a brush becomes dark and light to make the image more conspicuous and causes problems such as inductive carrier adhesion.

According to the invention of claim 7, claims 1 to 4
In the developing method according to any one of 1 to 3, a resin layer forming a carrier surface to be used is a resin layer containing a silicone resin containing aminosilane as a main component, and a suitable electrical resistance is obtained by the developing method. This is a silicone resin having a low surface energy, and the carrier surface has irregularities that are sufficiently small relative to the toner particle size, can increase the amount of free toner T generated, prevent toner spent, and achieve good charging. Properties, toner retention, and toner developability can be combined, and a development method for obtaining a high image can be provided.

According to the invention of claim 8, claims 1 to 7
In the developing method according to any one of items 1, the resin layer forming the carrier surface used contains fine particles in the layer,
By the developing method characterized by being a silicone resin layer having irregularities derived from fine particles, by containing fine particles of a composition different from the material forming the carrier surface inside the convex portions, the morphology of irregularities on the film The existence state can be arbitrarily formed, the carrier can be controlled in a wide range, and high image quality can be obtained.

According to the invention of claim 9, claims 1 to 7
In the developing method according to any one of items 1 to 3, a resin layer forming a carrier surface to be used is a silicone resin layer containing conductive fine particles and non-conductive fine particles, and the fine particles have irregularities derived from the respective fine particles. According to the developing method characterized by the above, the resistance of the silicone resin layer can be adjusted and it can be used as a means for obtaining high image quality.

According to a tenth aspect of the present invention, in the developing method according to any one of the first to ninth aspects, the developing method is characterized in that when the spikes in which the magnetic carriers are gathered stand up. The toner is separated from the magnetic carrier, and the toner is separated from the magnetic carrier to form an electric field for moving the toner toward the image carrier to develop the toner. The toner is applied to develop the toner, and in the rear area of the developing area, the toner on the magnetic carrier having a space open to the side of the photoconductor is separated from the electric field between the photoconductor and the developing sleeve and between the photoconductor and the magnetic carrier. The magnetic carrier, which has been developed into an electrostatic latent image on the photoconductor by an electric field generated between them and has an excessive amount of charge, moves while rubbing the photoconductor, so it strongly contacts the previously developed toner. As a result, the impact force and the electrostatic Coulombic force charged in opposite polarities cause the toner to be adsorbed on the carrier surface and the toner in the non-image area to be released, thus removing the background stain. It is possible to prevent and obtain a high-quality image.

According to the eleventh aspect of the present invention, in the developing method according to the tenth aspect, the developing method is characterized in that the powder characteristic and magnetic characteristic of the magnetic carrier and the magnetic characteristic and morphological characteristic of the developing main magnet are magnetic. A high density and high quality image can be obtained by the developing method characterized in that the toner is set to be released from the magnetic carrier when the spikes in which the carriers are gathered stand up.

According to the twelfth aspect of the present invention, in the developing method according to the tenth aspect, in the developing method, the morphological characteristics and electrical characteristics of the developer carrying member and the morphological characteristics and electrical characteristics of the image carrying member are By the developing method characterized by setting the electric field for moving the toner released from the carrier to the image carrier side, it is possible to obtain high image quality with less background stain.

According to the thirteenth aspect of the present invention, in the developing method according to the tenth aspect, the developing method comprises:
By the developing main magnet, the tip of the magnetic brush is separated from the developer layer in which the magnetic carriers are aggregated on the image carrier, by the developing method, the toner is developed on the image carrier and a high quality image is obtained. Can be obtained.

According to a fourteenth aspect of the present invention, in the developing method according to any one of the tenth to thirteenth aspects, a magnetic carrier having a toner on the surface is brought into contact with the latent image carrier in the developing area. A high-density image can be obtained by a developing method characterized in that the toner is released from the surface of the magnetic carrier, the released free toner is scattered on the image carrier, and development is performed.

According to the fifteenth aspect of the present invention, in the developing method according to any one of the tenth to thirteenth aspects, the developing method comprises contacting a magnetic brush formed in a developing area with an image carrier. Then, a developing method characterized in that the toner which has already been developed is released from the image carrier can provide an image with less background stain.

According to a sixteenth aspect of the present invention, in the developing method according to any one of the first to fifteenth aspects, the ears of magnetic carriers having a toner on the surface are gathered in the developing area, and the magnetic carrier surface. To form a magnetic brush containing free toner to be separated from the magnetic carrier, to separate and develop the toner when the spikes of the magnetic carrier rise, and
By a developing method characterized in that a free toner, which is brought into contact with the image carrier and released therefrom, is scattered and developed on the image carrier, and the magnetic brush is rubbed or brought close to the image carrier to develop. An image with high density and less background stain can be obtained.

According to the seventeenth aspect of the present invention, in the developing method according to the sixteenth aspect, in the developing method, the magnetic brush formed in the developing area is brought into contact with the image carrier to remove the toner from the image carrier. An image with high density and less background stain is obtained by a developing method characterized in that the toner that has already been developed is separated from the image carrier by rubbing or bringing the magnetic brush into contact with or rubbing against the image carrier. be able to.

According to the eighteenth aspect of the present invention, in the developing method according to the sixteenth aspect or the seventeenth aspect, in the developing method, the center of the magnetic pole inside the developer carrying member is within the developing area, and the developer is conveyed. By the developing method characterized by inclining to the downstream side in the direction, the portion where the free toner T is generated in the initial stage of forming the magnetic brush can be moved to the image portion as the latent image L of the photoconductor 100. Most of the cloud-like or smoke-like free toner T generated in the front area A of the developing area where the magnetic brush is formed is located in the area of the photoconductor 100 due to the developing electric field. It becomes easier to move to the image portion, the use efficiency of the toner T can be improved, and
It is possible to prevent the inside of the device from being soiled due to toner scattering.

According to the nineteenth aspect of the present invention, in the developing method according to any one of the sixteenth to eighteenth aspects, the developing method is the developer bearing member (Vs) and the image bearing member (Vp). ) Linear velocity ratio (Vs / Vp) is 0.9 <Vs
By the developing method characterized by being in the range of / Vp <4, the required image density can be obtained even if the linear velocity ratio is lowered to 0.9.

According to a twentieth aspect of the present invention, in the developing method according to any one of the sixteenth to nineteenth aspects, the developing method is an image bearing method for releasing the free toner which is released from the surface of the magnetic carrier in the developing area. By a developing method characterized by developing with an electric field applied between the body and the developer carrying body, adjustment of the electric field allows cloud-like or smoke-like free toner to easily move to the photoconductor and high-quality development is possible. become.

According to a twenty-first aspect of the present invention, in the developing method according to any one of the sixteenth to nineteenth aspects, in the developing method, the applied electric field is an alternating electric field. As a result, the reciprocating motion of the toner T promotes the uniformization of the toner layer in the image portion to bring about high image quality with good dot reproducibility, and brings a skiving effect to the background toner T in the non-image portion. You can

According to the twenty-second aspect of the invention, the surface of the two-component developer is disposed so as to face the image bearing member, has a magnet inside, and includes a toner and a magnetic carrier holding the toner. The latent image formed on the surface of the image carrier is developed with toner, which is composed of a developer carrier that is carried on the image carrier and conveyed to the developing area, and an application unit that applies an electric field between the developer carrier and the image carrier. In a developing device, the developing device comprises the carrier and toner according to claim 1 or any one of claims 3 to 9, and the amount of toner developed in a developing area by the developing device. It is possible to provide a developing device that obtains an image having a high solid density in the solid portion by increasing the number of the toner.

According to the twenty-third aspect of the invention, the image carrier having photoconductivity and forming a latent image on the surface, the charging device for charging the image carrier, and the image carrier are disposed so as to face the image carrier. A developing device that stores toner and a magnetic carrier that holds the toner on the surface and forms a toner image on the surface of the image carrier, and a transfer device that transfers the toner image formed on the surface of the image carrier to a recording member. In an image forming apparatus, the image forming apparatus includes the developing device according to claim 22, and the developing sleeve is set by setting a developing area wider than a conventional developing area by the image forming apparatus. It is possible to provide a developing device that increases the supply amount of toner to be developed without increasing the number of rotations of the developing device. Further, in the image forming apparatus of the present invention, by setting the developing area in a wide range to increase the supply amount of the toner to be developed, the developing gap, the rotating speed of the developing sleeve, etc. in designing the machine can be improved. It is possible to provide an image forming apparatus capable of widening the allowable range and obtaining an image with high reproducibility of a halftone portion in a high-quality image of a solid portion or a horizontal thin line, particularly a color image.

[Brief description of drawings]

FIG. 1 is a schematic view schematically showing a state of a two-component developer in a developing area of the present invention.

FIG. 2 is a schematic view showing the rising state of the ears of the magnetic carrier in the front area of the developing area of the present invention.

FIG. 3 is a schematic diagram in which the ears of the magnetic carrier come into contact with the photoconductor in the middle region of the developing region of the present invention.

FIG. 4 is a schematic diagram showing a situation in which toner is developed in the rear area of the development area of the present invention.

FIG. 5 is a schematic view showing a state in which a DC electric field is applied by the reversal development method of the present invention.

FIG. 6 is a schematic diagram showing a state in which a DC and AC electric field is applied in the reversal development method of the present invention.

FIG. 7 is an embodiment of an image forming apparatus to which the developing method of the present invention is applied.

FIG. 8 is a configuration diagram schematically showing the arrangement of magnets in the developing sleeve of the present invention.

FIG. 9 is a schematic diagram showing a situation in which toner is developed in a developing area by the developing method of the present invention.

FIG. 10 is a schematic diagram showing a configuration of an image forming apparatus of the present invention.

[Explanation of symbols]

100 photoconductor 110 developing device 111 Development sleeve 112 Stirring screw 113 stirring screw 114 developer regulating member 200 color scanner 400 optical unit 402 photoconductor 404 laser diode 406 polygon mirror 408 rotation motor 410 f / θ lens 412 reflective mirror 414 Cleaning unit 422 rotary developing device 426 Intermediate transfer body A Development Area Battle Area B Development area Middle area C Development area Rear area L latent image C magnetic carrier T toner

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/06 101 G03G 15/08 507L 15/08 501 9/10 321 507 352 361 311 (72) Inventor Shigekazu Enomoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Riki Imai 1-3-6 Nakamagome, Nakamagome Ota-ku, Tokyo (72) Inventor Kimitoshi Yamaguchi Tokyo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Naoki Imahashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Hiroaki Takahashi Nakata, Ota-ku Tokyo Magome 1-chome 3-6 F-term in Ricoh Co., Ltd. (reference) 2H005 BA02 BA06 BA07 BA15 CA12 CB04 CB18 EA01 EA02 EA05 EA07 2H031 AA01 AA17 AB02 AC08 AC15 AC19 AC20 AC30 AD01 AD03 AD15 BA08 BA09 CA11 FA01 2H073 AA02 BA04 BA13 BA43 CA03 CA14 CA22 2H077 AA15 AB02 AC02 AD02 AD06 AD13 AD18 AD36 EA03 GA13

Claims (23)

[Claims] 1. A two-component developer-bearing member, which is disposed so as to face the image-bearing member and has a magnet inside, contains a toner having a number average particle diameter of 3 to 7 μm and a magnetic carrier having a weight average particle diameter of 25 to 45 μm. It carries a developer and conveys the developer to a developing area formed between the developer and the image carrier, and in the developing area, separates the magnetic carrier and the toner when the gathered magnetic carriers stand up. , A developing method comprising developing with the obtained free toner. 2. A developer carrying member, which is arranged so as to face the image carrying member and has a magnet inside, carries a two-component developer containing toner and a magnetic carrier holding the toner, and carries the image carrier with the developer. 2. The developing method according to claim 1, wherein the electrostatic latent image on the image carrier is conveyed to a developing area formed between the image carrier and the developing area, and the free toner released from the surface of the magnetic carrier is developed in the developing area. The magnetic carrier and the toner are separated from each other when the bristles gathered by the magnetic carrier rise, and an electric field that moves the separated toner separated from the magnetic carrier to the image carrier side is formed for development. Development method. 3. The developing method according to claim 1, wherein the toner used has a number average particle diameter of 3 to 7 μm.
In addition, the coverage of the toner on the carrier in the developer is 5
0% -80%, The developing method characterized by the above-mentioned. 4. The weight average particle diameter Dw of the carrier used in the developing method according to claim 1.
Is 25 μm to 45 μm, and the content of carriers having a particle size larger than 62 μm is 1 wt% or less, 22
The content of the carrier having a particle size smaller than μm is 3 wt.
%, And the magnetic moment at 1 KOe is 76 emu / g or more. 5. The core material of a carrier used in the developing method according to claim 1, wherein the core material is MnMg.
A developing method, which is a ferrite selected from Sr ferrite, Mn ferrite, and magnetite. 6. The developing method according to claim 1, wherein the carrier used has a resistance of 10 ¹² Ω.multidot.
A developing method characterized in that it is at least cm. 7. The developing method according to claim 1, wherein the resin layer forming the carrier surface to be used is a resin layer containing an aminosilane-containing silicone resin as a main component. Developing method. 8. The development method according to claim 1, wherein the resin layer forming the carrier surface to be used contains fine particles in the layer and has irregularities derived from the fine particles. Is a developing method. 9. The developing method according to claim 1, wherein the resin layer forming the carrier surface to be used contains conductive fine particles and non-conductive fine particles, and each fine particle contains fine particles. A developing method, which is a silicone resin layer having irregularities derived from. 10. The developing method according to claim 1, wherein the developing method removes the toner from the magnetic carrier when the spikes of the magnetic carrier rise, and the magnetic carrier A developing method, which comprises developing by forming an electric field for moving free toner separated from the image carrier to the image carrier side. 11. The developing method according to claim 10, wherein in the developing method, the powder characteristic and the magnetic characteristic of the magnetic carrier and the magnetic characteristic and the morphological characteristic of the developing main magnet are raised by the magnetic carrier. Sometimes, the developing method is characterized in that the toner is set to be released from the magnetic carrier. 12. The developing method according to claim 10, wherein the developing method is a toner in which the morphological characteristics and electrical characteristics of a developer carrier and the morphological characteristics and electrical characteristics of an image carrier are separated from a magnetic carrier. A developing method characterized by setting so as to form an electric field to be moved to the image carrier side. 13. The developing method according to claim 10, wherein the developing main magnet causes the tip of the magnetic brush to move onto the image carrier when the ears of magnetic carriers gather on the developer carrier. 2. The developing method, characterized in that the magnetic carrier is separated from the developer layer in which the magnetic carriers are assembled. 14. The developing method according to claim 10, further comprising contacting a latent image carrier with a magnetic carrier having a toner on the surface in the developing area.
A developing method characterized in that the toner is released from the surface of the magnetic carrier, the released free toner is scattered on the image carrier, and development is performed. 15. The developing method according to claim 10, wherein the developing method has already been performed by bringing a magnetic brush formed in a developing area into contact with an image carrier. A developing method characterized in that the toner is released from the image carrier. 16. The developing method according to claim 1, further comprising: in the developing area, a pair of ears of magnetic carriers having toner on the surface and free toner to be released from the surface of the magnetic carrier. A magnetic brush containing a magnetic carrier is formed, and when the spikes of the magnetic carrier rise, the toner is released and developed, and the magnetic brush is brought into contact with the image carrier to release it. Further, a developing method characterized by developing by rubbing or bringing a magnetic brush on or near the image carrier. 17. The developing method according to claim 16, wherein in the developing method, a magnetic brush formed in a developing area is brought into contact with an image carrier to separate toner from the image carrier, and the magnetic brush is used. A method of developing, wherein the toner already developed is released from the image carrier by rubbing or bringing the toner into contact with the image carrier. 18. The developing method according to claim 16, wherein in the developing method, the center of the magnetic pole inside the developer carrying member is tilted to the downstream side in the developer conveying direction within the developing area. And a developing method. 19. The developing method according to claim 16, wherein the developing method is a linear velocity ratio (Vs / V) between a developer carrier (Vs) and an image carrier (Vp).
p) is in the range of 0.9 <Vs / Vp <4. 20. The developing method according to claim 16, wherein in the developing method, free toner that is released from the surface of the magnetic carrier in the developing area is used as an image carrier and a developer carrier. A developing method comprising developing with an electric field applied between the two. 21. The developing method according to claim 16, wherein the applied electric field is an alternating electric field. 22. A two-component developer, which is arranged to face the image carrier, has a magnet inside, and includes a toner and a magnetic carrier that holds the toner, is carried on the surface. Development in which a latent image formed on the surface of an image carrier is developed with toner, which comprises a developer carrier conveyed to a developing area and an application unit for applying an electric field between the developer carrier and the image carrier. In the apparatus, the developing device further includes the carrier and the toner according to claim 1 or any one of claims 3 to 9. 23. An image carrier having photoconductivity and forming a latent image on the surface, a charging device for charging the image carrier, and a toner arranged on the surface of the image carrier, the toner being disposed on the surface of the image carrier. An image forming apparatus comprising: a developing device that accommodates a magnetic carrier for holding and forms a toner image on the surface of an image carrier; and a transfer device that transfers the toner image formed on the surface of the image carrier to a recording member. An image forming apparatus, wherein the forming apparatus uses the developing apparatus according to claim 22 as a developing apparatus.