JPH06295130A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device stably and sufficiently imparting electrostatic charge to magnetic toner. CONSTITUTION:As for the magnetic toner brought into contact with the surface of a developer carrier 1a, the relation between the carrying force F1S thereof received from the carrier 1a and the carrying force F2 thereof received from a developer quantity regulation member 6 is F1S>F2. As for the magnetic toner which is not brought into contact with the surface of the carrier 1a, the relation between the carrying force F1 thereof received from the carrier 1a and the carrying force F2 thereof received from the regulation member 6 is F1hF2. Besides, the satulation magnetization (sigmas) of the magnetic toner which contains a magnetic material and whose average grain size by weight is Rmum in a magnetic field 10e is <=(42.0-1.85R)emu/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic device and an electrostatic recording device.

[0002]

2. Description of the Related Art Conventionally, many electrophotographic methods are known, as described in US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. However, in general, an electric latent image is formed on a photoconductor using a photoconductive substance by various means, and then the latent image is formed by using a toner. After the toner image is transferred onto the transfer material, it is heated or fixed by solvent vapor or the like to obtain a copy.

Various methods for visualizing an electric latent image using toner are also known.

For example, the magnetic brush developing method described in US Pat. No. 2,870,463, No. 221776.
Developing methods such as the powder cloud method, the fur brush developing method, and the liquid developing method described in the specification are known.

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

In order to avoid such drawbacks, various developing methods using a one-component developer consisting of only toner have been proposed. For example, US Pat. No. 3,909,258 proposes a method of developing using a magnetic toner having electrical conductivity.

In this method, a cylindrical conductive developing sleeve having a magnet inside is used as a developer carrying member, the conductive magnetic developer is supported on the developing sleeve, and this is brought into contact with an electrostatic image. It is to develop. At this time, a conductive path is formed between the surface of the recording body and the surface of the sleeve by the toner particles in the developing section, and the electric charge is introduced from the sleeve to the toner particles through the conductive path, and the Coulomb force between the electrostatic image section is formed. As a result, toner particles adhere to the image area and are developed. The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method.

However, in the developing method using the magnetic one-component toner, since the toner is conductive, the developed image is electrostatically transferred from the recording medium to the final supporting member such as plain paper. Was difficult.

In order to solve this problem, as a developing method using a high resistance toner capable of being electrostatically transferred, Japanese Patent Laid-Open No. 52-94140 discloses a developing method utilizing dielectric polarization of toner particles. It is shown. However, such a method has a drawback that the developing speed is slow and the density of a developed image cannot be sufficiently obtained, and it is practically difficult.

As another method using a high-resistivity magnetic toner, the toner particles are triboelectrically charged by friction between the toner particles, friction between the toner particles and the sleeve, and the like, and the toner particles are brought into contact with the electrostatic latent image carrier. A method of developing is known.
However, according to this method, the number of contact between the toner particles and the friction member is small, and triboelectric charging is apt to be insufficient, or when the Coulomb force between the charged toner particles and the sleeve is strong, the toner particles are not attached on the sleeve. It has been pointed out that it has many drawbacks such as easy aggregation and is difficult in practical use.

On the other hand, Japanese Patent Application Laid-Open No. 54-43036 proposes a new developing method which eliminates the above-mentioned drawbacks. In this method, toner is applied very thinly on a sleeve, it is triboelectrically charged, then it is brought very close to an electrostatic image under the action of a magnetic field, and it is made to face without being brought into contact with the electrostatic image for development. .

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

[0013]

However, according to the developing method of obtaining a triboelectric charge by forming a thin layer of magnetic one-component toner as in the above-mentioned conventional example, there are the following problems. .

First, in this system as well, the chances of contact between the developing sleeve and the magnetic toner are smaller than the chances of contact between the toner and the carrier in the two-component system, and the triboelectric charge required for the magnetic toner to be used for development. The required number of contacts with the developing sleeve for obtaining the amount varies depending on the composition of the magnetic toner and the like, and there is a drawback that a phenomenon associated with unstable charging tends to occur.

Further, as described above, the copied image by the magnetic one-component method is a method of developing under the action of a magnetic field. Therefore, due to the influence of the magnetic field, the toner is chained (generally, "brush"). The resolution in the horizontal direction of the image tends to be worse than that in the vertical direction as compared with the above-described two-component system. There is a tendency for the phenomenon of poor resolution due to Also, when trying to develop a solid black image, it is difficult to close-pack the ears, and depending on how the ears overlap, a gap may be created in the developed solid black image, resulting in a uniform solid black image. There was a tendency not to get.

As a result, the inventors of the present invention have examined the behavior of the toner in the charge imparting portion of the above-mentioned one-component developing system. As a result, it has been clarified that the instability of charging is as follows.

First, the developing device used in the examination will be described with reference to FIG. FIG. 7 shows a developing device for an image forming apparatus using the above-mentioned magnetic one-component toner. In the figure, reference numeral 1a denotes a developing sleeve which is a developer carrying member using a non-magnetic member and is rotatably installed in a direction of an arrow shown in the drawing. Has been done. Further, 1b is a permanent magnet fixed inside the sleeve 1a, 2 is a magnetic blade as a developer amount regulating member using a magnetic member, 3 is a developing device, and 4 is a conveying member. The magnetic blade 2 is arranged on the developing sleeve 1a so that the distance becomes a constant value W. Generally, the distance W is 100 [μ
It is often set to a value within the range of [m] to 1 [mm].

Next, the behavior of the magnetic toner in the charge applying section of the developing device will be described with reference to FIGS. 8 and 9.
As shown in FIG. 8, the developing sleeve 1 a and the magnetic blade 2
Considering the plane perpendicular to the straight line connecting the two, S ₁ is the surface close to the magnetic blade 2 and S ₂ is the surface close to the developing sleeve 1 a. Generally, the width of the magnetic blade 2 is smaller than that of the permanent magnet 1 b. The magnetic flux density on the S ₁ surface is larger than that on the S ₂ surface. Therefore, the magnetic toner T
Receives a force between the developing sleeve 1a and the magnetic blade 2 in the direction of the arrow in FIG. 8 according to the strength of magnetization of the magnetic toner, that is, a force toward the magnetic blade 2.

Therefore, the magnetic toner T forms ears in the state shown by B in FIG. 9, and the ears are formed from the magnetic blade 2 toward the developing sleeve 1a. The magnetic toner T is charged by the developing sleeve 1a and the toner t _{1 at} the tip of the brush formed by the magnetic blade 2 contacting each other, so that the toner t ₁ at the tip is finally charged. Will be done.

As described above, when electric charge is applied to the toner t ₁ at the tip of the brush that comes into contact with the developing sleeve 1a, a force in the direction of the developing sleeve 1a due to the mirroring force is exerted, and the frictional force with the developing sleeve 1a causes , The conveying force in the rotating direction of the developing sleeve 1a is given.

Since the toners have a certain amount of cohesive force acting on each other, the toner t ₂ in contact with the toner t ₁ also has a conveying force with the intervening cohesive force. Similarly, the toner t ₃ in the upper layer portion also has a transporting force with the cohesive force interposed.

However, as described above, the magnetic force in the direction of the magnetic blade 2 acts on the toner between the developing sleeve 1a and the magnetic blade 2. Therefore, where the conveying force applied to the toner overcomes the magnetic force, that is,
At the cut line L in FIG. 9, the toner spikes are torn off,
The toner remaining on the developing sleeve 1a is
It is conveyed in the rotation direction of a.

That is, in the above conventional example, the developing sleeve 1
Only the toner in the vicinity of a can be charged,
In this state, the toner is transported to the developing area,
The above-mentioned problems have occurred.

It was also found that, near the tip of the magnetic blade 2, as shown by A in FIG. 9, there is a toner accumulation portion to which no electric charge is applied. When the toner accumulation portion becomes large, the toner is magnetically attracted to the magnetic blade 2 by the magnetic force.
The force for continuing to hold to the side is weakened, so that part of the toner in the toner accumulation portion is conveyed in the rotation direction of the developing sleeve 1a.

As a result, a part of the toner conveyed on the developing sleeve 1a becomes a toner to which no electric charge is applied, and causes the phenomenon associated with unstable charging as described above.

On the other hand, as to another problem of the magnetic one-component developing system, the poor image reproducibility, as a result of the examination, the following has been revealed.

In other words, in order to solve the image reproducibility, it is conceivable to make the ears of the toner short and dense, and as a means therefor, a method of reducing the ratio of the amount of magnetic material in the toner is easy. I can imagine.

This is because when the magnetic toner has a high magnetization intensity, the ears formed by the magnetic toner are long and coarse,
This is because one ear becomes thin, and conversely, if the magnetic toner has a low magnetization intensity, the ear becomes short and dense.

However, if the ears are too dense, the binding between the magnetic toners cannot be released, so that one ears are thick,
It will be in a state of aggregation, but if this toner aggregation occurs,
This causes a problem that an image defect easily occurs due to a defective charging of the magnetic toner such as fog.

The relationship between the magnetic strength of the magnetic toner and the shape of the ears, and the relationship between the aggregation of the magnetic toner and the fog can be qualitatively understood as follows.

That is, an attractive force along the magnetic field direction and a repulsive force along the direction perpendicular to the magnetic field are generated between the magnetic toners magnetized under the magnetic field. Therefore, when the magnetic toner has a large magnetization, the attractive and repulsive forces between the magnetized magnetic toners are strong, so that the ears formed by the magnetic toner are long and coarse, and one ears are thin. Become. On the other hand, when the magnetic toner has a small magnetization, the above-mentioned attractive force and repulsive force are weak, so that the ears are short and dense, and
One ear becomes thick and aggregated.

Therefore, when the ratio of the amount of magnetic material in the magnetic toner is reduced to decrease the magnetization intensity of the magnetic toner, the ears are thick and agglomerated, so that they are inside the ears. The magnetic toner has a very small chance of coming into contact with the developing sleeve, and cannot sufficiently obtain the electric charge due to frictional electrification, resulting in deterioration of image quality such as fogging due to poor electrification of the toner.

Further, the force shown in FIG. 9A for holding the toner accumulation portion to which electric charge is not applied also depends on the strength of the magnetization of the magnetic toner. When the strength of the magnetization is small, the holding force is weak. Therefore, as is clear from the above-mentioned process of imparting toner charge, a phenomenon associated with unstable charging is caused.

Therefore, if the ratio of the amount of magnetic material in the toner is simply reduced to shorten the ears, the above-mentioned method causes deterioration of image quality such as fog due to defective charging of the toner. There was a problem that it was easy.

As a method for solving the problem associated with unstable charging caused by weakening the magnetic strength of the magnetic toner, an elastic developer layer thickness regulating member is brought into contact with the developing sleeve. A mechanical method is conceivable.

According to a study made by the present inventors, a developing device having a structure in which the above-mentioned magnetic toner having a weakened magnetization intensity and the above-mentioned elastic developer layer thickness regulating member are brought into contact with a developing sleeve. The image obtained by the image forming apparatus used is the magnetic 1
Poor resolution in the lateral direction of the image due to development of component toner while forming ears, and poor uniformity of solid black image due to the effect of gaps of overlapping ears that occur when trying to develop a solid black image. I confirmed that the problem would be resolved.

However, in the above structure, there is a problem that the developer layer thickness regulating member formed of an elastic body is liable to be worn and lacks durability stability.

Therefore, as described above, even when the layer thickness of the developer on the developing sleeve is regulated in a non-contact state with the developing sleeve and the magnetic strength of the magnetic toner is reduced, There has not been a sufficient image forming apparatus capable of sufficiently charging the toner and improving the image reproducibility.

The first invention according to the present application solves the above-mentioned problems and makes it possible to stabilize the charging of the magnetic toner even when the magnetic strength of the magnetic toner is reduced. An object of the present invention is to provide a developing device capable of stably coating only a sufficiently charged magnetic toner on the surface of the developing sleeve in a thin layer and transporting it to the developing area.

In order to achieve the above-mentioned object, the second invention of the present application is, in particular, the number density of chain-like aggregates of magnetic toner on the developer carrying member in the developing area and the chain-like aggregates. It is an object of the present invention to provide a developing device having an appropriate length.

Further, in order to achieve the above-mentioned object, the third invention of the present application aims to provide a developing device, in particular, in which the amount of the developer in the developing region is set to an appropriate value.

A fourth invention of the present application is, among other objects, to provide a developing device capable of stabilizing the charge amount of the magnetic toner conveyed to the developing area.

Further, the fifth invention of the present application aims to provide, among the above-mentioned objects, a developing device which does not convey the magnetic toner having insufficient electric charge to the developing area.

In addition to the above object, the sixth invention of the present application aims at providing a developing device capable of improving the durability stability of the developer amount regulating member.

[0045]

According to the first invention of the present application, the above object is to provide a latent toner on a latent image carrier by a magnetic toner containing a magnetic material and a developer containing the magnetic toner. In a developing device for developing an image, the developing device includes a magnetic toner containing a magnetic material, a rotatably arranged developer carrier for carrying a developer containing the magnetic toner on a surface, and the developer carrying material. A permanent magnet disposed inside the body, and a developer amount regulating member for regulating the application of the developer on the developer carrying body, wherein the magnetic toner is at least the developer carrying body and the developing body. The amount of conveyance force F _{1S of the} magnetic toner which is in contact with the surface of the developer carrier and which is received from the developer carrier, and the developer amount regulation member. the size of the transport force received from member F ₂ and is, F _1S Have a relationship of F _2, of the magnetic toner that is not in contact with the surface of the developer carrying member, the conveying force received from the developer carrying member and the magnitude F _1, the conveying force received from the developer amount regulating member size And F ₂ is F ₁ ≦ F ₂
And the saturation magnetization σs in the magnetic field 1 [KOe] of the magnetic toner containing the magnetic material and having the weight average particle diameter R [μm] is σs ≦ (42.0-1.85R) [e
[mu / g].

In the present invention, the binder resin for the toner includes polystyrene, poly-p-chlorostyrene,
Homopolymers of styrene and its substitution products such as polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrenevinyl-toluene copolymers and their copolymers; styrene-methyl acrylate copolymers, styrene-acrylic acid Copolymers of styrene and acrylic ester such as ethyl copolymer, styrene-n-butyl acrylate copolymer; styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid Copolymer of styrene and methacrylic acid ester such as n-butyl copolymer; Multi-component copolymer of styrene and acrylic acid ester and methacrylic acid ester; Other styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Coalesce, styrene-butadiene copolymer,
Styrene-based copolymers of styrene and other vinyl-based polymerizable monomers such as styrene-vinyl methyl ketone copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid ester copolymers; polymethyl methacrylate , Polybutyl methacrylate, polyvinyl acetate,
Polyester, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid, phenol resin, aliphatic or alicyclic hydrocarbon resin, petroleum resin, chlorinated paraffin, etc. can be used alone or in combination.

In particular, as a binder resin for toner to be subjected to a pressure fixing system, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, higher fatty acid, polyamide resin, Polyester resins and the like can be used alone or in combination.

If the polymer, copolymer or polymer blend used contains a vinyl aromatic or acrylic monomer represented by styrene in an amount of 40% by weight or more, more desirable results can be obtained.

Any suitable pigment or dye can be used as a colorant in the toner. For example, there are known dyes and pigments such as carbon black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

As a method for producing the toner containing the magnetic material used in the present invention, a conventionally known method may be used. That is,
Binder resin, charge control agent, colorant, magnetic material, and other additives are powder-mixed in advance with a Henschel mixer, and then,
This is kneaded with a roll mill heated to about 140 [° C.] to 150 [° C.] for about 30 minutes to obtain a kneaded product, which is cooled, pulverized and, if necessary, classified to obtain a toner composition.

If necessary, a fluidity imparting agent, a lubricant, an abrasive, a cleaning aid, a resistance adjusting agent, a charge control agent and the like may be added internally or externally.

If the charge amount of the toner is not proper, a good image cannot be obtained. The toner charge amount was determined by the blow-off measurement method. The measuring instrument used was that manufactured by Toshiba Chemical Corporation. EFV200 / 300 (manufactured by Nippon Iron Powder Co., Ltd.) was used as a carrier, the toner concentration was 2 [wt%], and the mixing time was about 2 minutes. In order to obtain a good image, the measured value at this time is preferably 5 to 50 [μc / g] in absolute value, and preferably 5 to 40 [μc / g]. If it is less than 5 [μc / g], the sharpness of the image is deteriorated and the background portion is fogged. Further, in a high temperature and high humidity environment, a problem such as a decrease in image density becomes a problem. If it is larger than 50 [μc / g], the electrostatic cohesive force becomes large, the ears are less likely to be loosened, and the image quality is deteriorated. In particular, under a low-temperature and low-quality environment, the mirror power with the toner carrier becomes larger than necessary, so that the image density is lowered.

Considering the transportability of the magnetic toner due to the magnetic force, the transportability becomes unstable unless the magnetic toner has a certain level of magnetization. There is a correlation between the transportability and the particle size and magnetization strength of the magnetic toner. In the configuration of the present invention, the saturation magnetization σs of the magnetic toner in the magnetic field of 1 [KOe] is (30.0-1. 85R) ≤ σ
It was found that when the condition of s [emu / g] was satisfied, stable transportability was obtained.

Although the reason for this is not clear, since the magnetic force is generally proportional to the volume of the magnetic substance, the strength of the magnetic force acting on the magnetic toner depends on the particle size of the magnetic toner. Therefore, it is considered that when the particle size is reduced, it is necessary to increase the saturation magnetization of the magnetic toner.

Next, the coating state of the magnetic toner carried on the developer carrying member in the constitution of the present invention will be described in detail below.

According to the study by the present inventors, between the state of the spikes of the magnetic toner on the developer carrying member and the strength of magnetization of the magnetic toner in the developing area of the conventional example,
It was confirmed that there is a correlation that the length of the ears becomes longer according to the magnetization intensity of the magnetic toner, and the density of the ears becomes coarser depending on the magnetization intensity of the magnetic toner.

In addition, between the state of the magnetic toner ears and the charged state of the magnetic toner, the length of the ears becomes short in inverse proportion to the absolute value of the average charged charge amount of the magnetic toner, resulting in the density of the ears. Is coarser in inverse proportion to an increase in the amount of toner charged to a desired charge polarity, that is, the opposite polarity to the normal polarity in the distribution of the charge amount of the magnetic toner. It was confirmed that there is a correlation that the toner becomes thicker with an increase in the amount of toner charged.

Further, there is a correlation between the state of the magnetic toner ears and the average particle size of the magnetic toner that the length of the ears becomes shorter as the average particle size of the magnetic toner is made smaller. It was confirmed.

More specifically, in the developing area portion formed between the developer carrying member and the latent image carrying member,
It has been found that good image reproducibility can be obtained by setting the appropriate condition of the chain-like aggregate of the magnetic toner carried on the developer carrying body, that is, the ears, as follows.

That is, in the second aspect of the present invention, the length of the spikes is set to 180 [μm] or less, thereby eliminating the poor resolution due to the protrusion of the spikes in the non-image portion in the latter half of the developed image. The density of the number of ears per unit area is 8
By setting it to be 10 ⁴ [lines / cm ² ] or more, the problem of fog due to unstable charging was solved.

Particularly preferably, the length of ears of the magnetic toner is 160 [μm] or less, and the number density of ears is 10 × 10 ^4.
It has been found that adjusting the number to [book / cm ² ] or more is a condition for making the image reproducibility more stable and good.

In the third invention of the present application, the weight average particle diameter R [μm] and the true density of the magnetic toner are ρ.
When [g / cm ³ ] is set, the amount of the developer conveyed to the developing area portion formed between the developer carrying body and the latent image carrying body is defined as the developing area surface of the latent image carrying body. The surface area was adjusted to 0.06 Rρ [mg / cm ² ] or more.

In the structure of the present invention, the saturation magnetization σs of the magnetic toner in the magnetic field of 1 [KOe] is (42.
It was found that the above condition of the panicle can be achieved to 10 parts when it is 0 to 1.85 R) [emu / g] or less.

Further, it is known that the amount of magnetic toner required to obtain the same image density generally depends on the particle size of the magnetic toner, as shown in FIG. It is known that smaller magnetic toners require less toner. According to the study by the present inventors, the relationship between the image density and the amount of magnetic toner can be standardized by the particle size and density of the magnetic toner, and the standardization constant is 0.06 Rρ.
[Mg / cm ² ] and a value obtained by dividing the amount of developing toner on the latent image carrier by the above-mentioned normalization constant is taken as a standardized toner amount, as shown in FIG. It has been confirmed that the relationship with and is on almost the same straight line regardless of the particle size and density of the magnetic toner. Further, it has been found that the condition that the amount of developing toner on the latent image carrier is 0.06 ρ [mg / cm ² ] or more is a condition for obtaining a sufficient image density.

Further, the magnetization intensity of the magnetic toner used in the present invention, that is, the saturation magnetization σs, is the value when the magnetic field is 1 [KOe]. The reason for this is as follows.

As described above, the length of the spike depends on the magnetic characteristics of the magnetic substance and the strength of the magnetic field. Therefore, in the developing device used in the present invention, the magnetic field generated by the magnet disposed inside the developer carrying member is 1 at maximum on the surface of the developer carrying member.
Since it is about [KOe], the strength of the magnetization in the magnetic field 1 [KOe] is the most suitable value in consideration of the magnetic characteristics of the magnetic toner in the developing device, and the magnetic toner is the same. Since the intensity of the magnetization of the magnetic field reaches a saturation value at the magnitude of the magnetic field, the value of the magnetic field of 1 [KOe] was adopted.

Further, the magnetic force is measured by V manufactured by Toei Industry Co., Ltd.
SM was used. The particle size distribution of the toner can be measured by various methods, but in the present invention, it was measured using a Coulter counter. That is, a TA-II type machine manufactured by Coulter Counter Co., Ltd. is used as a measuring device, an interface for outputting a number distribution and a volume distribution and a personal computer are connected, and a primary sodium chloride is used as an electrolytic solution for measurement. What was prepared in [%] NaCl aqueous solution was used. As the measuring method, a surfactant as a dispersant, preferably an alkylbenzene sulfonic acid salt of 0.1 to 0.1 ml in the electrolytic aqueous solution of 100 to 150 [ml] is used.
5 [ml], and 0.5 to 50 [mg] of measurement sample
Add. The electrolytic solution in which the sample is suspended is about 1 with an ultrasonic disperser.
Dispersion treatment is performed for 3 minutes, and 100 is used as an aperture by the above TA-II type machine manufactured by Coulter Counter.
2-40 [μm] based on the number
m] of the particle size distribution, and then the value according to the present invention, that is, the particle size is the weight average diameter, and the variation coefficient is the standard deviation of the volume distribution divided by the volume average diameter, and multiplied by 100. did.

Further, in the present invention, with respect to the weight average particle diameter R [μm] of the above-mentioned magnetic toner by the above-mentioned measuring method, in the developing region portion of the developer carrying member, about 4 R [on the developer carrying member]. The aggregate of the magnetic toner existing above the upper part of [μm] is defined as a ears, and the density of the ears existing in the upper part of about 4R [μm] on the developer carrying member is defined as the ears per unit area of the ears. It was defined as the number density.

The reason for this definition is as follows. Even if the magnetic properties of the magnetic toner are the same, there is a distribution in the length of the ears, and as described above, since the length of the ears differs depending on the particle size of the magnetic toner, if the measurement position is constant,
Inevitably, a toner having a small particle diameter has a low density of ears. Therefore, the measurement position needs to be corrected in proportion to the particle size. The reason for setting the above measurement position is that when the magnetic toner is carried on the developer carrying member substantially alone (one or several adjacent states), no ears are formed. This is in order to avoid measuring the magnetic toner carried substantially alone as the number density of the ears as described above.

Further, the method for measuring the number density on the developer carrying member is as follows: at a position of about 4 R [μm] above the developer carrying member,
A method of measuring the density of the number of ears existing at the position per unit area by focusing on an optical microscope with a magnification of 100 times was adopted.

Further, the length of the spikes of the magnetic toner was measured by setting the magnification of the optical microscope to 200 times, setting the depth of field to a shallow state, and scanning the focus of the microscope upward from above the developer carrying member. It was carried out by measuring the moving distance of the focused portion until the tip of the ear was focused.

Next, according to the fourth invention of the present application,
The above-mentioned purpose is that the main force of the carrying force of the magnetic toner, which is in contact with the surface of the developer carrier, from the developer carrier is
This is achieved by a force that depends on the charge amount of the magnetic toner.

Further, according to the fifth invention of the present application, the above-mentioned object is the direction of the conveying force given to the magnetic toner from the surface of the developer carrying member, and the conveyance given to the magnetic toner from the developer amount regulating member. This is achieved by the fact that the directions of force are different.

Further, according to the sixth invention of the present application, the above-mentioned object is that the developer amount regulating member is formed of a non-magnetic member having a permanent magnet therein and is rotatably supported by the developer carrying member. This is achieved by being placed in the vicinity.

[0075]

According to the first invention of the present application, among the magnetic toners present in the developer amount regulating portion, the magnetic toner in contact with the developer carrying member is the charged charge amount of the magnetic toner. The carrier force F _1S received from the developer carrying member and the carrier force F ₂ from the developer amount regulating member are given as main forces of the carrier force. Further, even for the magnetic toner which is not in contact with the developer carrying member, the carrying force F ₁ from the developer carrying member and the carrying force from the developer amount regulating member are caused by interposing the cohesive force between the magnetic toners. F ₂ is given as the main force of the carrying force. Since F _1S , F ₁ and F ₂ have the relationship of F _1S > F ₂ and F ₁ ≦ F _2, the magnetic toner conveyed to the developing area is only the sufficiently charged toner. . Further, the saturation magnetization σs in the magnetic field 1 [KOe] of the magnetic toner having the weight average particle diameter R [μm] is σs ≦ (42.0
-1.85R) [emu / g] makes the chain aggregate of the magnetic toner formed on the developer carrier have an appropriate length and density, and the magnetic toner does not aggregate. A sufficient triboelectrification charge is given, and the relationship of the above-mentioned carrying force is maintained.

According to the second invention of the present application,
Particularly, in the developing area formed between the latent image carrier and the developer carrier, the number density of the chain-like aggregates of the magnetic toner formed on the developer carrier is 8 × 10 ⁴ [lines / cm ² ] or more, the length of the chain-like aggregate of the magnetic toner is 180 [μm]
By the following, without causing aggregation of the toner, to prevent the resolution failure due to protrusion of the chain-like aggregate,
It was confirmed that good image reproducibility was obtained.

Further, according to the third invention of the present application, when the weight average particle diameter of the magnetic toner is R [μm] and the true density is ρ [g / cm ³ ], the latent image carrier is particularly preferable. And the amount of the developer conveyed to the developing area formed between the developer carrying member and the developing surface of the latent image carrying member is 0.06 Rρ [mg / cm ² ] or more with respect to the unit surface area of the developing area surface of the latent image carrying member. It was confirmed that, by doing so, the closest packing can be easily carried out without causing toner aggregation, and good image reproducibility and stable image density can be obtained.

According to the fourth invention of the present application,
Since the main force of the carrying force that the magnetic toner receives from the developer carrying member depends on the charge amount of the magnetic toner, only the magnetic toner having a sufficient charge amount is carried to the developing area. The amount of charge of the magnetic toner is stable.

Further, according to the fifth invention of the present application, the direction of the carrying force applied to the magnetic toner from the surface of the developer carrying member and the direction of the carrying force applied to the magnetic toner from the developer amount regulating member are determined. Since they are in different directions, only the magnetic toner having a sufficient triboelectric charge amount is conveyed to the developing area by the conveying force received from the developer carrier, and the magnetic toner having an insufficient triboelectric charge amount is a developer amount regulating member. It is returned to the developing container side by the conveying force from.

According to the sixth invention of the present application,
Magnetic toner has a magnetic force of a permanent magnet, a frictional force between a non-magnetic member, and a frictional force between magnetic toners.
The developer amount regulating member is provided with a conveying force in the inward direction of the developing container, and the developer amount regulating member and the developer carrier do not come into contact with each other, so that the durability stability of the developer amount regulating member is improved.
It

[0081]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Table 1 below shows the magnetic toners used in the following examples and comparative examples.

[0083]

[Table 1]

Further, Table 2 below shows the evaluation results of images in the following Examples and Comparative Examples.

[0085]

[Table 2]

(First Embodiment) FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, reference numeral 1a denotes a developing sleeve which is a non-magnetic metal member developing agent carrier that rotates in the direction of the arrow, 1b denotes a permanent magnet disposed inside the developing sleeve 1a, 3 denotes developing units, 4a and 4b. Is the developing device 3
It is a conveying member rotatably arranged in the direction of the arrow for conveying the magnetic toner inside in the direction of the developing sleeve 1a. Further, 6 is a developer amount regulating member, which will be described later, and 7 is a scraper.

The developer amount regulating member 6 is a non-magnetic member 6
a rotates in the direction of the arrow in the figure, and the permanent magnet 6b is arranged inside the non-magnetic member 6a. Further, the developer amount regulating member 6 is arranged in the vicinity of the developing sleeve 1a on the upstream side in the rotating direction of the developing sleeve 1a with respect to the developing area, and the rotating direction of the non-magnetic member 6a is
The direction of the arrow is the same as the direction of rotation of the developing sleeve 1a.

Further, the permanent magnet 6b corresponds to the developing sleeve 1
At least one magnetic pole having a heteropolar relationship with at least one magnetic pole among the magnetic poles of the permanent magnet 1b arranged in a is provided. In this embodiment, the magnetic pole N ₁ in the permanent magnet 1b arranged in the developing sleeve 1a and the magnetic pole S _{4 of the} permanent magnet 6b having a different polarity from the magnetic pole N ₁ closely face each other. It is arranged as follows.

[0089] Further, it disposed to be adjacent opposite to the magnetic pole N ₁ of the developing sleeve 1a, the width of the magnetic pole S ₄ of the permanent magnet 6b, to narrow the width of the magnetic pole N ₁ of the developing sleeve 1a As a result, the change in the magnetic flux density of the magnetic field formed between the magnetic poles N ₁ and S ₄ becomes large as it goes from the developing sleeve 1a to the developer regulating member 6 side. With such a structure, for the same reason as described above with reference to FIG. 8, the magnetic toner T existing between the developer regulating member 6 and the developing sleeve 1a is
A force due to a magnetic force acts from the developing sleeve 1a to the developer regulating member 6 side.

Further, in the present embodiment, the non-magnetic member 6
As shown in FIG. 1, a is rotated in the direction of the arrow in the drawing, which is the same direction as the developing sleeve 1a, so that the magnetic toner T has the force due to the magnetic field and the non-magnetic member 6a. And the frictional force between the magnetic toners gives a conveying force from the developer regulating member 6 to the inside of the developing container.

Further, as described above, the magnetic toner T which is in contact with the developing sleeve 1a is charged with an electric charge by frictional charging with the developing sleeve 1a, and the magnetic toner T which has obtained the electric charge is a mirror image. The force in the direction of the developing sleeve 1a due to the image force acts, and the frictional force with the developing sleeve 1a gives the conveying force in the rotating direction of the developing sleeve 1a. Therefore, in the developing device configured as shown in FIG. 1, as shown in FIG. 4, among the magnetic toners T existing in the developer amount regulating portion, the magnetic toner t ₁ that is in contact with the developing sleeve 1a. The main force of the conveying force is the conveying force F _1S received from the developing sleeve 1 a depending on the charged amount of the magnetic toner and the conveying force F ₂ from the developer amount regulating member 6.

Further, the magnetic toner t ₂ not in contact with the developing sleeve 1a also has a cohesive force between the magnetic toners, so that the conveying force F ₁ from the developing sleeve 1a and the developer amount regulating member 6 are generated. The transporting force F ₂ from is given as the main force of the transporting force. Therefore,

[0093]

[Equation 1] F _1S > F ₂ ... F ₁ ≤F ₂ ...

If the above relationship exists, the magnetic toner conveyed to the developing area is only the sufficiently charged toner.

The configuration satisfying the above relational expression varies depending on the characteristics of the magnetic toner, but in the present embodiment, the magnetic pole S _{4 of the} permanent magnet 6b arranged so as to closely face the magnetic pole N ₁ in the developing sleeve 1a. Magnetic flux density of 800 [Gauss],
The magnetic flux density of the magnetic pole N ₁ in the developing sleeve 1a is set to 900 [Gauss], and the width of a region showing a value of 50% or more with respect to the peak value of the magnetic flux density of each magnetic pole (for convenience, hereinafter, referred to as 5
0% value)),

[0096]

(2) (50% value of magnetic pole S ₄ ) / (50% of magnetic pole N ₁ )
Value) ≈ 0.8

[0097] and then, the width of the magnetic pole N _1, by narrowing the width of the magnetic pole S _4, the change in the magnetic field of the magnetic flux density is formed between the magnetic poles N ₁ and S ₄ are developing sleeve 1a The magnetic flux density is increased from the developer regulating member 6 side to the developer regulating member 6 side and the developing sleeve 1a.
The distance W between and is about 0.5 [mm], and the absolute value of the peripheral speed of the developing sleeve 1a and the absolute value of the peripheral speed of the non-magnetic member 6a are the same.

Further, the magnetic toner used in this example is No. 1 shown in Table 1. It is one toner, and the prescription and manufacturing method of the magnetic toner are as follows.

[0099]

[Table 3]

Powders obtained by mixing the powders shown in Table 3 above were mixed with two roll mills set at 140 ° C. for about 30 minutes.
Heat-kneading, cooling, coarse crushing, fine crushing (jet mill)
did. Furthermore, fine powder,
The coarse powder was cut to obtain a toner composition. The particle size of the obtained toner has a weight average particle diameter of 11.8 [μm] and a change coefficient of 30.
[%] And true density were 1.33 [g / cm ³ ]. To this, 0.4 [wt%] of negatively chargeable colloidal silica was externally added to obtain a developer.

Further, the magnetic material used in this example has a horizontal ferret diameter of 0.42 [μm] and BET of 8.8 [m ² / m ² .
g], the saturation magnetization σs at a magnetic field of 1 [KOe] is 59.
3 [emu / g], coercive force Hc is 110 [Oe], and residual magnetization is 10.0 [emu / g].

The magnetic field of the magnetic toner is 1 [KOe].
Has a saturation magnetization σs of 18.3 [emu / g], and when the weight average particle diameter of the magnetic toner is R [μm], σs ≦ (42.0-1.85R) [emu / g] A magnetic toner that satisfies the conditions is used.

In this embodiment, the magnetic pole N ₂ of the permanent magnet 1b is used as a developing magnetic pole near the developing area formed between the latent image carrier (not shown) and the developing sleeve 1a.
And the magnetic flux density of the magnetic pole N ₂ is 1000 [Gauss].

In the case of the above constitution, it is confirmed that the above conditions are satisfied, and as a result, only the magnetic toner having a stable charge is formed in the developing area between the latent image carrier and the developing sleeve. It was confirmed to be transported to.
Moreover, in the developing area, the chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the density of the number of ears per unit area is 8 × 10 ⁴ to
The length of the ears was 10 × 10 ⁴ [lines / cm ² ] or more, and the length of the ears was 180 [μm] or less, and good image reproducibility without influence of the ears was obtained.

In this embodiment, the amount of developer per unit area on the developing sleeve in the developing area is 1.0 to
It was 1.1 [mg / cm ² ], and the obtained image had a sufficient image density. The developer amount is 0.0 when the true density of the magnetic toner is ρ [g / cm ³ ].
The condition of 6 Rρ [mg / cm ² ] or more is satisfied.

The present invention is not limited to the constitution of this embodiment, and the magnetic flux density of the magnetic pole, the 50% value, the developer regulating member are satisfied so as to satisfy the above conditions according to the characteristics of the magnetic toner. 6, the distance W between the developing sleeve 1a and
It is preferable to appropriately adjust the peripheral speed and the like of the developing sleeve 1a and the non-magnetic member 6a.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted so that the image is formed between the latent image carrier and the developing sleeve 1a. The amount of the developer conveyed to the developing area is 0.06 Rρ with respect to the unit surface area of the developing area surface of the latent image carrier.
The constitution may be [mg / cm ² ] or more.

With the above structure, even when the magnetization intensity of the magnetic toner is reduced, the process of imparting charge to the magnetic toner can be stabilized, and the image reproducibility can be improved. It became so.

(Second Embodiment) The present invention is not limited to the magnetic toner of the first embodiment. N shown in Table 1
o. A magnetic toner of No. 2 may be used.

No. The magnetic toner of No. 2 was produced by using the magnetic substance of the first embodiment and the following formulation.

[0111]

[Table 4]

The obtained toner has a weight average diameter of 8.3 [μ
m] and the coefficient of change was 32%. 0.6 [wt%] of negatively chargeable colloidal silica was externally added thereto to obtain a developer.

When this magnetic toner and the developing device of the first embodiment were used, the magnetic field of the magnetic toner was 1 [K
The saturation magnetization σs in Oe] is 21.9 [emu /
g], and σs ≦ (42.0-1.85R) [emu
/ G] is used as the magnetic toner.

In the case of the above-mentioned constitution, it was confirmed that the above conditions were satisfied, and as a result, only the magnetic toner having a stable charge was formed between the latent image carrier and the developer carrier. It was confirmed that the paper was transported to the developing area. Furthermore, in the developing area, a chain-like aggregate of magnetic toner carried and formed on the developer carrying body,
That is, the number density of ears per unit area is 8 × 10.
^{It was 4} to 10 × 10 ⁴ [lines / cm ² ] or more and the length of the ears was 170 [μm] or less, and good image reproducibility without influence of the ears could be obtained.

In this embodiment, the amount of the developer per unit area on the developing sleeve in the developing area is 0.7 to.
It was 0.8 [mg / cm ² ], and the obtained image had a sufficient image density. Further, the developer amount satisfies the above condition of 0.06 Rρ [mg / cm ² ] or more.

The present invention is not limited to the structure of this embodiment, and the magnetic flux density of the magnetic pole, the 50% value, the developer regulating member are satisfied so as to satisfy the above conditions according to the characteristics of the magnetic toner. 6, the distance W between the developing sleeve 1a and
It is preferable to appropriately adjust the peripheral speed and the like of the developing sleeve 1a and the non-magnetic member 6a.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted so that the image is formed between the latent image carrier and the developing sleeve. The amount of the developer conveyed to the developing area is 0.06 Rρ [mg / per unit surface area of the developing area surface of the latent image carrier.
cm ² ] or more.

With the above structure, even when the magnetization intensity of the magnetic toner is reduced, it is possible to stabilize the charge applying process to the magnetic toner and improve the image reproducibility. Became.

(Third Embodiment) The present invention is not limited to the magnetic toner of the first embodiment. N shown in Table 1
o. The magnetic toner of No. 3 may be used.

No. No. 3 magnetic toner is In the preparation of the magnetic toner No. 2, the pulverization / classification conditions are changed and the particle size is changed. No. The magnetic toner of No. 3 had a weight average diameter of 5.2 [μm] and a coefficient of change of 34%. Negatively chargeable colloidal silica was externally added to this in an amount of 1.0% by weight to obtain a developer.

The magnetic toner and the magnetic pole S ₄ of the permanent magnet 6b arranged so as to closely face the magnetic pole N ₁ in the developing sleeve 1a in the developing device of the first embodiment have a magnetic flux density of 1000 [Gauss]. ], The magnetic pole N in the developing sleeve 1a
The magnetic flux density of ₁ is 800 [Gauss], and the ratio of the value of the area showing 50% or more of the magnetic flux density peak value of each magnetic pole (hereinafter referred to as 50% value for convenience) is

[0122]

[Formula 3] (50% value of magnetic pole S ₄ ) / (50% of magnetic pole N ₁ )
Value) ≒ 0.7

The developing device having the above structure was used.

In the case of the above structure, it is confirmed that the above conditions are satisfied, and as a result, only the magnetic toner having a stable charge is formed in the developing area between the latent image carrier and the developing sleeve. It was confirmed to be transported to.
Further, in the developing area, the chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the number density of the ears per unit area is 9 × 10 ⁴ to
It was 11 × 10 ⁴ [lines / cm ² ] or more and the length of the ears was 160 [μm] or less, and good image reproducibility without influence of the ears could be obtained.

In this embodiment, the amount of the developer per unit area on the developing sleeve in the developing area is 0.4 to 0.4.
0.5 [mg / cm ² ], which is approximately 0.06 described above.
The amount of developer was equivalent to the condition of Rρ [mg / cm ² ]. Further, the obtained image had a sufficient image density.

The present invention is not limited to the constitution of this embodiment, and the magnetic flux density of the magnetic pole, the 50% value, the developer regulating member are satisfied so as to satisfy the above conditions according to the characteristics of the magnetic toner. It is preferable to appropriately adjust the distance W between the developing sleeve 1 and the developing sleeve 1, the developing sleeve 1a, and the peripheral speed of the non-magnetic member 6a.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted, and the image is formed between the latent image carrier and the developing sleeve. The amount of the developer conveyed to the developing area is 0.06 Rρ [mg / per unit surface area of the developing area surface of the latent image carrier.
cm ² ] or more.

With the above arrangement, even when the magnetic strength of the magnetic toner is reduced, it is possible to stabilize the process of applying the electric charge to the magnetic toner and improve the image reproducibility. Became.

(Fourth Embodiment) The present invention is not limited to the magnetic toner of the first embodiment. N shown in Table 1
o. Magnetic toner No. 4 may be used. No. The magnetic toner of No. 4 was prepared by using the magnetic material of the first embodiment and the following formulation.

[0130]

[Table 5]

The obtained toner has a weight average diameter of 6.5 [μ
m] and the coefficient of change was 30%. 0.8 [wt%] of negatively chargeable colloidal silica was externally added to this to obtain a developer.

When this magnetic toner and the developing device of the third embodiment were used, the magnetic field of the magnetic toner was 1 [K
The saturation magnetization σs in Oe] is 19.8 [emu /
g], and σs ≦ (42.0-1.85R) [emu
/ G] is used as the magnetic toner.

In the case of the above structure, it is confirmed that the above conditions are satisfied, and as a result, only the magnetic toner having a stable charge is formed in the developing area between the latent image carrier and the developing sleeve. It was confirmed to be transported to.
Further, in the developing area, the chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the number density of the ears per unit area is 9 × 10 ⁴ to
It was 11 × 10 ⁴ [lines / cm ² ] or more and the length of the ears was 150 [μm] or less, and good image reproducibility without influence of the ears could be obtained.

In this embodiment, the amount of developer per unit area on the developing sleeve in the developing area is 0.5 to
0.6 [mg / cm ² ], which is approximately 0.06 described above.
The amount of developer was equivalent to the condition of Rρ [mg / cm ² ]. Further, the obtained image had a sufficient image density.

The present invention is not limited to the constitution of this embodiment, and the magnetic flux density of the magnetic pole, the 50% value, the developer regulating member are satisfied so as to satisfy the above conditions according to the characteristics of the magnetic toner. 6, the distance W between the developing sleeve 1a and
It is preferable to appropriately adjust the peripheral speeds of the developing sleeve 1a and the non-magnetic member 6a.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted so that the image is formed between the latent image carrier and the developing sleeve. The amount of the developer conveyed to the developing area is 0.06 Rρ [mg / per unit surface area of the developing area surface of the latent image carrier.
cm ² ] or more.

With the above arrangement, even when the magnetic strength of the magnetic toner is reduced, it is possible to stabilize the process of applying the electric charge to the magnetic toner and improve the image reproducibility. Became.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIG.

In FIG. 2, reference numeral 1a denotes a developing sleeve composed of a developer carrying member made of a non-magnetic metal member that rotates in the direction of the arrow, and 1b denotes at least two poles disposed inside the developing sleeve 1a. Permanent magnets having magnetic poles 3, developing devices 4a and 4b are conveying members rotatably arranged in the arrow direction for conveying the magnetic toner in the developing devices 3 toward the developing sleeve 1a. Further, 61 is a developer amount regulating member which will be described later, and 71 is a scraper composed of a magnetic member.

The developer amount regulating member 61 is arranged close to the magnetic poles of the permanent magnet 1b arranged inside the developing sleeve 1a.

The developer amount regulating member 61 is a permanent magnet having at least two magnetic poles, and is located near the developing sleeve 1a on the upstream side of the developing area in the rotation direction of the developing sleeve 1a. And the rotation amount of the developer amount regulating member 61 is rotatably arranged in the arrow direction which is the same as the rotation direction of the developing sleeve 1a.

According to the above structure, the magnetic toner T existing between the developer regulating member 61 and the developing sleeve 1a is
Similar to the first embodiment, the developer regulating member 61 and the developing sleeve 1a apply a carrying force similar to that of the first embodiment.

Therefore, depending on the characteristics of the magnetic toner, the number of magnetic poles of the developer amount regulating member 61, the magnetic flux density of each magnetic pole, and the 50% value, the developer regulating member 61 and the developing sleeve 1a. The distance W between them, the rotation amount of the developer amount regulating member 61 and the developing sleeve 1a,

[0144]

[Equation 4] F _1S > F ₂ ... F ₁ ≤ F ₂ ...

The same effect as that of the above-described first embodiment can be obtained by appropriately adjusting so that the above relationship exists.

The constitution satisfying the above relational expression differs depending on the characteristics of the magnetic toner, but in the present embodiment, No. 1 used in the first embodiment is used. No. 1 magnetic toner is used, the developer regulating member 61 has a 4-pole structure, and the magnetic flux density of each magnetic pole is
00 [Gauss] or more, 50% value of each magnetic pole has an angle of 30 [degrees] or more, and the distance W between the developer regulating member 61 and the developing sleeve 1a is about 0. When the absolute value of the peripheral speed of the developing sleeve 1a is the same as the absolute value of the peripheral speed of the developer amount regulating member 61, it is confirmed that the above conditions are satisfied. .

In this embodiment, the magnetic pole N ₂ of the permanent magnet 1b is used as a developing magnetic pole near the developing area formed between the latent image carrier (not shown) and the developing sleeve 1a.
And the magnetic flux density of the magnetic pole N ₂ is 1000 [Gauss].

In this embodiment, in the developing area,
The chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the density of the number of ears per unit area is 8 × 10 ⁴ to 10 × 10 ⁴ [lines / cm ² ] and The length of the ears was 180 [μm] or less, and good image reproducibility without the influence of the ears could be obtained as in the first embodiment.

In this embodiment, the amount of developer per unit area on the developing sleeve in the developing area is 1.0 to
It was 1.1 [mg / cm ² ], and the obtained image had a sufficient image density. Further, the developer amount satisfies the above condition of 0.06 Rρ [mg / cm ² ] or more.

The present invention is not limited to the above configuration,
Depending on the characteristics of the magnetic toner, the magnetic flux density of the magnetic pole, the 50% value, the distance W between the developer regulating member 61 and the developing sleeve 1a, the developing sleeve 1a, and the above so as to satisfy the above conditions. It is preferable to appropriately adjust the peripheral speed and the like of the developer regulating member 61.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted so that the image is formed between the latent image carrier and the developing sleeve. The amount of the developer conveyed to the developing area is 0.06 Rρ [mg] with respect to the unit surface area of the developing area surface of the latent image carrier.
/ Cm ² ] or more.

With the above structure, even when the magnetization intensity of the magnetic toner is reduced, it is possible to stabilize the charge applying process to the magnetic toner and improve the image reproducibility. Became.

(Sixth Embodiment) A sixth embodiment of the present invention will be described with reference to FIG.

In FIG. 3, reference numeral 1a designates a developing sleeve which is a non-magnetic metal member developing agent carrier which rotates in the direction of the arrow.
1b is a permanent magnet having at least two magnetic poles disposed inside the developing sleeve 1a, 3 is a developing unit, 4
a and 4b denote the magnetic toner in the developing device 3 and the developing sleeve 1
The transport member is rotatably disposed in the arrow direction for transporting in the a direction. And 62 is a developer amount regulating member which will be described later.

The developer amount regulating member 62 is a permanent magnet 6 having at least two magnetic poles rotatably arranged.
2a and a non-magnetic member 62b arranged between the developing sleeve 1a and the permanent magnet 62a so as to isolate them from each other. The developer amount regulating member 62 is arranged in the developing sleeve 1a. The permanent magnets 1b are arranged close to each other.

Further, the developer amount regulating member 62 is provided on the upstream side in the rotation direction of the developing sleeve 1a with respect to the developing area.
The permanent magnet 6 is arranged in the vicinity of the developing sleeve 1a.
The rotation direction of 2a is rotatably arranged in the arrow direction opposite to the rotation direction of the developing sleeve 1a.

According to the above construction, the magnetic toner T existing between the developer regulating member 62 and the developing sleeve 1a is
Similar to the first embodiment, the same conveying force as in the above embodiment is applied from the permanent magnet 62a of the developer regulating member 62 and the developing sleeve 1a.

Therefore, depending on the characteristics of the magnetic toner, the number of magnetic poles of the permanent magnet 62a, the magnetic flux density of each of the magnetic poles, and the 50% value, and the distance between the permanent magnet 62a and the developing sleeve 1a. W, the rotation speed of the permanent magnet 62a and the developing sleeve 1a,

[0159]

[Formula 5] F _1S ＞ F ₂・ ・ ・ ・ ・ ・ F ₁ ≦ F ₂・ ・ ・ ・

The same effect as that of the above-described first embodiment can be obtained by appropriately adjusting so that the above relationship exists.

The constitution satisfying the above relational expression differs depending on the characteristics of the magnetic toner, but in the present invention, No. 1 used in the first embodiment is used. Using the magnetic toner No. 1, the permanent magnet 6
2a has a 4-pole structure, and the magnetic flux density of each magnetic pole is 400
[Gauss] or more, and the 50% value of each magnetic pole is
The angle is 30 degrees or more, and the distance W between the permanent magnet 62a and the developing sleeve 1a is about 0.5 m.
It has been confirmed that the above conditions are satisfied when m is m and the absolute value of the peripheral speed of the permanent magnet 62a is twice or more the absolute value of the peripheral speed of the developing sleeve 1a.

In this embodiment, the magnetic pole N ₂ of the permanent magnet 1b is used as a developing magnetic pole near the developing area formed between the latent image carrier (not shown) and the developing sleeve 1a.
And the magnetic flux density of the magnetic pole N ₂ is 1000 [Gauss].

In this embodiment, the chain density of magnetic toner formed on the developing sleeve in the developing area, that is, the number density of ears per unit area was 8 ×.
10 ⁴ to 10 × 10 ⁴ [lines / cm ² ] and the length of the ears is 180 [μm] or less, and similar to the first embodiment,
It was possible to obtain good image reproducibility without the effect of ears.

In this embodiment, the amount of developer per unit area on the developing sleeve in the developing area is 1.0 to
It was 1.1 [mg / cm ² ], and the obtained image had a sufficient image density. Further, the developer amount satisfies the above condition of 0.06 Rρ [mg / cm ² ] or more.

The present invention is not limited to the constitution of this embodiment, and the magnetic flux density of the magnetic pole, the 50% value, the developer regulating member are satisfied so as to satisfy the above conditions according to the characteristics of the magnetic toner. It is preferable to appropriately adjust the distance W between the developing sleeve 1a and 62, the peripheral speeds of the developing sleeve 1a and the permanent magnet 62a, and the like.

Further, in order to stabilize the image density, the peripheral speed of the developing sleeve 1a and the peripheral speed of the latent image carrier are appropriately adjusted so that the latent image carrier is formed between the latent image carrier and the developing sleeve. The amount of the developer conveyed to the developing area is 0.06 Rρ [mg / per unit surface area of the developing area surface of the latent image carrier.
cm ² ] or more.

With the above structure, even when the magnetization intensity of the magnetic toner is reduced, it is possible to stabilize the process of applying the electric charge to the magnetic toner and improve the image reproducibility. Became.

(First Comparative Example) The magnetic toners used in the above examples are No. 1 shown in Table 1. The magnetic toner shown in No. 5 was prepared by the following formulation. The magnetic material used was the same as in the first embodiment.

[0169]

[Table 6]

Powders shown in Table 6 were mixed, and the mixture was heat-kneaded for about 30 minutes by two roll mills set to 140 [° C.], cooled, coarsely pulverized and finely pulverized (jet mill). . Further, fine powder and coarse powder were cut by an elbow jet classifier to obtain a toner composition. The particle size of the obtained toner has a weight average diameter of 11.5 [μm] and a variation coefficient of 33.
[%] And true density were 1.48 [g / cm ³ ]. To this, 0.4 [wt%] of negatively chargeable colloidal silica was externally added to obtain a developer.

The magnetic field of the magnetic toner is 1 [KOe].
Has a saturation magnetization σs of 24.4 [emu / g] and satisfies the condition of σs ≦ (42.0-1.85R) [emu / g].

When the image properties were confirmed by using the above magnetic toner and the developing device shown in FIG. 7 of the above-mentioned conventional example, the image was affected by the spikes, and good image reproducibility could not be obtained.

Here, in the permanent magnet 1b arranged in the developing device shown in FIG. 7, the magnetic flux density of the magnetic poles arranged in the vicinity of the developing area of the permanent magnet 1b is 10 on the developing sleeve 1a.
A permanent magnet having a diameter of 00 [Gauss] or more was used.

Further, in the case of the above-mentioned constitution, in the developing area, the chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the density of the number of ears per unit area is 5 × 10 5. ^{4 to} 7 × 10 ⁴ [pieces / cm
² ] and the length of the ears was 220 to 240 [μm].

(Second Comparative Example) Instead of the magnetic toner used in the above examples, No. 1 shown in Table 1 was used. The magnetic toner shown in No. 6 was produced with the following formulation. The magnetic material used was the same as in the first embodiment.

[0176]

[Table 7]

Powders shown in Table 7 were mixed, and the mixture was heat-kneaded for about 30 minutes with two roll mills set to 140 ° C., cooled, and then coarsely pulverized and finely pulverized (jet mill). . Further, fine powder and coarse powder were cut by an elbow jet classifier to obtain a toner composition. The particle size of the obtained toner has a weight average diameter of 6.8 [μm] and a variation coefficient of 35.
[%] And true density were 1.72 [g / cm ³ ]. 0.8 [wt%] of negatively chargeable colloidal silica was externally added to this to obtain a developer.

The magnetic field of the magnetic toner is 1 [KOe].
Has a saturation magnetization σs of 31.1 [emu / g] and satisfies the condition of σs ≦ (42.0-1.85R) [emu / g].

When the image properties were confirmed by using the above magnetic toner and the developing device of the first comparative example, it was found that the image was affected by the spikes and good image reproducibility could not be obtained.

Further, in the case of the above-mentioned constitution, in the developing area, the chain-like aggregate of the magnetic toner carried and formed on the developing sleeve, that is, the number density of the ears per unit area is 5 ×. 10 ^{4 to} 7 × 10 ⁴ [pieces / cm ²
] And the length of the ears was 190 to 220 [μm].

(Third Comparative Example) Above No. When the image quality was confirmed using the magnetic toner of No. 4 and the developing device of the first comparative example, the image was not affected by the ears, but image fogging occurred due to poor charging, and a good image was obtained. I couldn't. When the developing device shown in FIG. 4 was evaluated, image fog occurred due to poor charging of the magnetic toner.

The length of the ears in the developing area is 1
Although it was 60 [μm] or less, the density of the number of magnetic toner ears per unit area in the developing region formed between the latent image carrier and the developing sleeve was 4 × 10 ^{4 to} 6 × 10 ^4.
It was [books / cm ² ].

(Fourth Comparative Example) No. 4 used in the first embodiment. Instead of the magnetic toner of No. 1 magnetic toner, No. 1 shown in Table 1 was used.
The magnetic toner shown in No. 7 was produced with the following formulation. The magnetic material used was the same as in the first embodiment.

[0184]

[Table 8]

Powders shown in Table 8 were mixed, and the mixture was heat-kneaded with two roll mills set at 140 [° C.] for about 30 minutes. After cooling, coarse pulverization and fine pulverization (jet mill) were performed. . Further, fine powder and coarse powder were cut by an elbow jet classifier to obtain a toner composition. The particle size of the obtained toner has a weight average diameter of 8.3 [μm] and a variation coefficient of 34.
[%] And true density were 1.15 [g / cm ³ ]. 0.6 [wt%] of negatively chargeable colloidal silica was externally added thereto to obtain a developer.

The magnetic field of the magnetic toner is 1 [KOe].
Has a saturation magnetization σs of 9.8 [emu / g] and satisfies the condition of σs ≧ (30.0-1.85R) [emu / g].

When the above magnetic toner and the developing device of the first comparative example were used, defective conveyance of the developer occurred.

[0188]

As described above, the first aspect of the present application
According to the invention, the magnetic strength of the magnetic one-component toner is reduced to a predetermined value, and the carrying force for carrying the magnetic toner to the developing area is the same as the carrying force received from the developer carrier and the developing force. Since it is determined by the magnitude of the force received from the agent amount regulating member, it is possible to carry only the sufficiently charged magnetic toner on the developer carrier and convey it to the developing area. Qualitative can be eliminated. Further, since it becomes possible to eliminate the influence of the ears, it is possible to improve the image reproducibility in the developing area.

According to the second invention of the present application,
In the developing area, the number density of the magnetic toner ears formed on the developer carrying member is set to 8 × 10 ⁴ [lines / cm ² ] or more and the length of the ears is set to 180 [μm] or less. It is possible to prevent poor resolution due to the protrusion of the image and obtain good image reproducibility.

Further, according to the third invention of the present application, when the weight average particle diameter of the magnetic toner is R [μm] and the true density is ρ [g / cm ³ ], the latent image carrier is used. The amount of the developer conveyed to the developing area formed between the developer carrying member and the unit surface area of the developing area surface of the latent image carrying member,
By setting 0.06 Rρ [mg / cm ² ] or more,
The ears can be thickened to stabilize the image reproducibility and the image density.

According to the fourth invention of the present application,
By developing the magnetic toner in contact with the surface of the developer carrying member with a main force of the carrying force received from the developer carrying member depending on the charge amount of the magnetic toner, development carried to the developing area is performed. The agent has a sufficient amount of electrified charge and can prevent deterioration of image quality such as fog due to poor charging.

Further, according to the fifth invention of the present application, the direction of the carrying force applied to the magnetic toner from the surface of the developer carrying member and the direction of the carrying force applied to the magnetic toner from the developer amount regulating member. Since the magnetic toner having an insufficient charge amount is pulled back in the opposite direction without being conveyed to the developing area, the developer having an unstable charge amount is not mixed in the developing area. It is possible to stabilize the charged state and prevent deterioration of image quality such as fogging.

According to the sixth invention of the present application,
Since the developer amount regulating member is formed of a non-magnetic member having a permanent magnet inside and is rotatably arranged near the developer bearing member, the developer amount regulating member by sliding contact with the developer bearing member is regulated. It is possible to provide a developing device that has excellent durability and stability by preventing abrasion of members.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a fifth embodiment of the present invention.

FIG. 3 is a sectional view showing a sixth embodiment of the present invention.

FIG. 4 is an explanatory diagram of a force applied to a magnetic toner in a developer regulating portion of the apparatus shown in FIG.

FIG. 5 is a relationship diagram between image density and toner particle size.

FIG. 6 is a diagram showing the relationship between image density and normalized toner amount.

FIG. 7 is a cross-sectional view of a conventional developing device, which uses a magnetic blade fixed to a developer amount regulating member.

FIG. 8 is an explanatory diagram of a magnetic flux density at a developer regulating portion of the apparatus shown in FIG.

FIG. 9 is an explanatory diagram of toner behavior in a developer regulating unit of the apparatus shown in FIG.

[Explanation of symbols]

 1a Developing sleeve (developer carrying member) 1b Permanent magnet 6,61,62 Developer amount regulating member 6a Non-magnetic member 6b Permanent magnet T Magnetic toner

Claims (6)

[Claims] 1. A developing device for developing a latent image on a latent image carrier with a magnetic toner containing a magnetic substance and a developer containing the magnetic toner, wherein the developing device is a magnetic toner containing a magnetic substance. A developer carrying member carrying on its surface a developer containing the magnetic toner, a permanent magnet disposed inside the developer carrying member, and regulating the application of the developer on the developer carrying member. A developer amount regulating member, wherein the magnetic toner is
At least, the magnitude F _{1S of the} carrying force of the magnetic toner, which receives the carrying force from the developer carrying member and the developer amount controlling member and is in contact with the surface of the developer carrying member, from the developer carrying member. And the magnitude F _{2 of the} conveying force received from the developer amount regulating member are in a relation of F _1S > F ₂ , and the developer carrying member of the magnetic toner not in contact with the surface of the developer carrying member. The magnitude of the carrying force F ₁ received more and the magnitude of the carrying force F ₂ received from the developer amount regulating member are F ₁
≦ F is on the _second relationship, the saturation magnetization [sigma] s in field 1 [kOe] of the magnetic toner with a weight average particle containing the magnetic substance diameter R [[mu] m] is, σs ≦ (42.0-1.85R) [e
[mu] / g]. 2. The number density of chain aggregates of magnetic toner formed on the developer carrier is 8 × in a developing area formed between the latent image carrier and the developer carrier. 10 ⁴ [Book /
cm ² ] or more, and the length of the chain-like aggregate of the magnetic toner is 180 [μm] or less, and the developing device according to claim 1. 3. The weight average particle diameter of the magnetic toner is R [μ
m], and the true density is ρ [g / cm ³ ], the amount of the developer conveyed to the developing area formed between the latent image carrier and the developer carrier is the latent image carrier. ^2. The developing device according to claim 1, wherein the developing surface area is 0.06 Rρ [mg / cm ² ] or more per unit surface area. 4. The main force of the carrying force of the magnetic toner in contact with the surface of the developer bearing member, which is received from the developer bearing member, is a force depending on the amount of charge of the magnetic toner. 1. The developing device according to 1. 5. The direction of the carrying force applied to the magnetic toner from the surface of the developer carrying member and the direction of the carrying force applied to the magnetic toner from the developer amount regulating member are different directions. The developing device according to 1. 6. The developer amount regulating member is formed of a non-magnetic member having a permanent magnet therein, and is rotatably disposed near the developer carrying member. Development device.