JP3156887B2 - Development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method in an electrophotographic system, an electrostatic recording system, an electrostatic printing system or the like.

[0002]

2. Description of the Related Art In recent years, as an example of developing an electrostatic latent image, a system using a developing magnet roller having a sleeve provided with a magnetic field generating means therein and a magnetic one-component toner has been popular. However, the magnetic toner has a disadvantage that it is not suitable for colorization because the magnetic substance mixed therein is black. The developing operation of the electrostatic latent image in the system using the magnetic one-component toner is performed by rotating the sleeve, rotating the internal magnet, or rotating both of them. When developing by rotating the magnet, the moving speed of the magnetic toner is set to 2 to 4 of the latent image so that the magnetic pole pitch does not appear in the image.
The rotation speed of the sleeve or magnet is selected so as to double the rotation speed. However, if we try to ensure sufficient image density uniformity, the number of rotations of the magnet will be very high, causing a problem that a powerful motor is required for driving the magnet, and in addition, naturally increasing the size of the mechanical device. Will be.

[0003] From these circumstances, Japanese Patent Publication No. 41-9475.
As described in Japanese Patent Application Laid-Open Publication No. H10-209, a donor member having a thin layer of a one-component developer (toner) on its surface is disposed close to a latent image holding member, and the toner is applied to only an electrostatic latent image in a non-contact relationship. It is considered to fly. In this example, the toner is retained by suctioning and adsorbing the toner to a web having a proper tackiness or a film sheet which has been charged in advance. However, in this method, the lengths of sheets and webs are limited, and are not suitable for continuous copying and printing. However, if the toner carrier is made endless so that it can be used repeatedly, the above problem can be solved. A system using such a non-magnetic one-component toner is disclosed in Japanese Patent Application Laid-Open No. 60-229065. I have. In this example, a thin layer of toner is formed by contacting an elastic homogenizing member with a developing carrier roller, and an AC and DC developing bias is applied to develop a latent image. JP 5
Japanese Patent Laid-Open No. 0-30537 discloses a method for increasing image density by a pulse bias method. Further, JP-A-47-12635 and JP-A-50-10
No. 143 discloses a structure of a developer carrier having an insulating and conductive fine pattern on the surface. These methods use a minute electric field to form peaks and valleys of the toner according to the minute pattern and cause the toner to adhere in accordance with the potential level of the latent image. In any case, the amount of development on the photoconductor changes depending on the state in which the toner is applied to the development carrier, so that the characteristics of the toner on the developer carrier are important.

With respect to the characteristics of the toner on the developer carrier,
JP-B-2-6059, JP-A-61-133951
Japanese Patent Application Laid-Open Publication No. Hei 11 (1995) discloses that the packing density is limited to a non-magnetic non-contact developing method. The method described in Japanese Patent Publication No. 2-6059 discloses that the toner carrier has a packing density of 0.19.
~0.46g / cm ³ at but is intended to non-contact developing by alternating a non-magnetic one-component toner of the true specific gravity of 1.2 or less, or a magnetic or because the true specific gravity of 1.2 or less is free of magnetic material Even if a small amount of the toner is contained, it is only a criterion indicating that the properties are comparable to those of a non-magnetic toner. JP-A-61-1309
No. 62 and JP-A-61-133951, in order to prevent toner scattering, non-contact development of a non-magnetic toner having a true specific gravity of 1.2 g / cm ³ or more by intentionally containing a substance having a large specific gravity. However, as described above, the true specific gravity of 1.2 g / cm ³ has no deep reason,
If iron oxide is contained as a substance having a large specific gravity, the effect of its own color is so strong that it is not suitable for colorization.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to use a non-magnetic one-component toner as a one-component developer particularly for developing an electrostatic latent image so that the toner sufficiently adheres to a developer carrier and It is an object of the present invention to provide a developing method which develops efficiently and, as a result, obtains an image having a high image density and a good image with high resolution.

[0006]

According to the present invention, toner particles having a shape factor of 50 to 85% are supplied in a thin layer onto a developer carrying member, and electrostatically charged with or without contacting the latent image holding member. In a developing method for visualizing a latent image, the electrostatic latent image is developed by setting the porosity of the toner layer in the developing area to be 60 to 75%.

The present inventors thinly supply a toner having a shape factor of 50 to 85% onto a developer carrying member, and contact or non-contact with the latent image holding member to make the electrostatic latent image visible. It has been found that the intended purpose can be achieved by visualizing the electrostatic latent image by setting the porosity of the toner layer to be 60 to 75% in the developing method for forming an image. The present invention has been made based on this.

Hereinafter, the method of the present invention will be described in more detail. The toner particles used in the present invention have a shape factor of 50.
-85%, preferably 60-80%. Here, the “shape factor” of the toner is defined as follows. Shape factor = (specific surface area of sphere having the same volume as particles / specific surface area of particles) × 100 (%) The “specific surface area of particles” in the denominator is, for example, an air-permeable specific surface area measuring device (WTT- manufactured by Sankyo Dengyo Co., Ltd.). It is measured in 2). In this measurement, a sample is filled into a measurement cell and air is allowed to permeate, and the specific surface area of the powder is determined based on the pressure loss at that time.The specific surface area depends on the porosity of the toner layer filled in the cell. I do. In this specification, the specific surface area is determined by unifying the porosity to 50%. The “specific surface area of a sphere having the same volume as a particle” of a molecule is measured by a Coulter counter (TA-II). The shape factor of the toner, that is, the sphericity of the particles, is determined by the toner manufacturing method. If a method in which the toner kneaded material collides with the collision plate by airflow pulverization or the like is employed, the shape factor becomes small. When mechanical pulverization is performed, hot air treatment is performed after pulverization, or processing is performed by a high-speed airflow impact method, a toner having a relatively large shape factor can be obtained. In addition, if the toner is produced by a polymerization method, a substantially spherical toner can be obtained.

On the other hand, the force received from the developing electric field of the toner particles, the force received from the developer carrier, and the adhesion force between the toners vary depending on the porosity of the toner layer on the developer carrier. Although the porosity varies depending on the prescription of the toner and the like, it is adjusted by the process conditions such as the contact pressure of a regulating blade for thinning the toner. Here, the “toner porosity” means the porosity of the toner layer immediately after the toner on the developer carrier is pressed by the regulating blade. The porosity of the toner layer on the developer carrying member was determined as follows. The thickness of the toner layer on the developer carrier is measured using a laser outer diameter measuring device LS-3100 (manufactured by KEYENCE CORPORATION), and the weight of the toner on the developer carrier per unit area is measured. Determine the bulk density of the toner on the body, divide it by the true specific gravity (by pneumatic hydrometer), and
This value was subtracted from, and the value obtained by multiplying by 100 was defined as the porosity. Porosity = [1- (bulk specific gravity / true specific gravity)] × 100 (%)

FIG. 1 shows the relationship between the porosity and the amount of toner adhered to the developer carrier, and FIG. 2 shows the relationship between the porosity and the development efficiency. As the porosity increases, the amount of toner adhesion tends to decrease. When the porosity increases, the developing efficiency also tends to decrease because the adhesive force between the developer carrier and the toner (the toner holding force of the carrier) increases, but when the porosity is less than 60%, the adhesive force between the toners decreases. When it is increased, the developing efficiency tends to decrease drastically. As described above, it is understood that the porosity of the toner layer on the developer carrier needs to be set to an optimal region.

FIG. 3 shows the relationship between the shape factor and the amount of toner adhering on the developer carrier, and FIG. 4 shows the relationship between the shape factor and development efficiency. It can be said that the larger the shape factor, that is, the closer the toner is to a spherical shape, the larger the toner adhesion amount. It can be seen that the development efficiency has an optimum region as well as the porosity. If the shape factor is too large, the toner is liable to be non-uniform, and the transferability is reduced, and the image density is apt to be reduced. If it is too small, the adhesive force between the developer carrier and the toner is reduced, and the phenomenon that the toner is scattered or the toner adheres to the background portion of the image by rotating the carrier is likely to occur.

FIG. 5 shows the relationship between the porosity and the amount of development depending on the difference in the shape factor of the toner. When the porosity is 60 to 75% and the shape factor is 50 to 85%, the development amount is 1.0.
It can be seen that a sufficient development amount exceeding mg / cm ² can be secured. Furthermore, it has been found that the characteristics are more excellent especially when it is in the range of 60% to 80%, which can be produced by performing mechanical pulverization or sphering treatment.
The results are not limited to non-contact development under an AC bias as shown in Japanese Patent Publication No. 2-6059, but are not limited to JP-A-61-130962 and JP-A-61-130962.
It is not limited by the true specific gravity as shown in JP-A-133951. Good results are obtained when the porosity on the developer carrier and the shape factor of the toner are in the above-mentioned ranges.

In the method of the present invention, as shown in FIG. 6, a dielectric portion and a conductor portion (electrode) are used as a developer carrier.
By using a material that is mixed in a very small area, the multi-layer thinning can be performed stably and the object can be sufficiently achieved. A small area of a size of 10 to 500 μm is randomly or dispersed according to a certain rule,
As the area ratio, the area of the insulating portion is preferably in the range of 20 to 60%.

The adhesion of the toner to the developer carrier is as follows. First, the developer carrier having completed the development rotates and comes into contact with the toner supply member. Here, the remaining toner in the non-image area that has not been developed is mechanically scraped off by the toner supply member, and the dielectric part is charged by friction. At this time, the charges of the developer carrier and the toner by the previous development are fixed and initialized by friction. Next, the toner carried by the supply member is charged by friction and electrostatically adheres to the dielectric portion of the developer carrier. At this time, the polarity of the toner is opposite to the charge of the electrostatic holding member, and the dielectric portion of the developer carrying member has the same polarity. At this time, the electric field on the developer carrier becomes a microfield (closed electric field), and the electric field has a large electric field gradient, so that the toner can be attached to multiple layers. Further, since the adhered toner has a closed electric field, it is strongly pulled toward the developer carrying member and is hardly separated. The thickness of the toner layer is controlled by the blade shown in FIG. 6 and reaches the developing area. The electric field between the developer carrier and the latent image holder in the developing area has an electrode effect, so that the toner on the developer carrier becomes an electric field that easily adheres to the electrostatic holder, and development is performed.

The volume average particle diameter of the toner is preferably 4 to 10 μm. As described above, by reducing the particle size as compared with the related art, the resolution is improved, and the image quality can be improved. In particular, when this toner is used as a color toner, the difference in image quality such as color reproducibility due to the particle size is remarkable. The volume average particle size of the toner is measured by a Coulter Multisizer.

The absolute value of the charge amount of the toner on the developer carrier is preferably 2 to 20 μC / g. That is,
By being in the range of the absolute value, the multilayering of the toner on the developer carrying member is stabilized, and at the same time, the scattering of the toner at the time of development, the fogging of the background portion on the image, and the decrease of the image density are reduced. I do. If the absolute value is lower than 2 μC / g, the toner easily scatters from the developer carrying member and fog tends to occur on the image. The measurement of the charge amount of the toner on the developer carrier is performed as follows. The toner adhering to the developer carrier is sucked through a Faraday cage having a filter layer on the outlet side, and the charge amount (Q / M) is calculated from the weight and charge amount of the toner trapped in the Faraday cage.

Examples of the binder resin used in the toner include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and substituted products thereof; styrene-p-chlorostyrene copolymer and styrene-propylene copolymer. Polymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-
Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Indene copolymer,
Styrene-based copolymers such as styrene-maleic acid copolymer and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, Epoxy resin, polyvinyl butyral, polyacrylic resin,
Rosin, modified rosin, terpene resin, phenolic resin,
Aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like,
They can be used alone or in combination. Particularly, as examples of binder resins suitable for pressure fixing, the following can be used alone or in combination. Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-butadiene copolymer (monomer ratio 5-30: 95-70), olefin copolymer (ethylene -Acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer resin ), Polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenolic resin, phenol-modified terpene resin.

The charge control agent used in the toner may be a positive charge control agent, such as a quaternary ammonium salt or an organic substance having a basic electron donating property. Examples thereof include metal complexes of monoazo dyes and tetraphenylboron derivatives such as sodium and potassium tetraphenylboron. An appropriate amount to be contained in the toner is 1 to 10 parts by weight based on 100 parts by weight of the binder resin.

As an additive used in the toner, a fluidity-imparting agent such as colloidal silica and aluminum oxide is effective. In addition, a caking inhibitor or a conductive agent such as carbon black and tin oxide is effective. An imparting agent or a fixing aid such as a low molecular weight polyolefin may be added. In addition, fatty acid metal salts such as barium stearate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, lithium stearate, lead stearate, barium laurate, and lauric acid are used as lubricants for preventing the blade from sticking to the developing section. Calcium phosphate, zinc laurate, magnesium laurate, lithium laurate,
Lead laurate, calcium palmitate, magnesium palmitate, dibasic lead stearate and the like may be added. The fatty acid metal salt is desirably contained in an amount of 0.01 to 5% by weight.

[0020]

Next, the method of the present invention will be described more specifically with reference to examples.

Example 1 Binder resin (styrene-acrylic copolymer) 100 parts by weight Release agent (low molecular weight polypropylene) 5.5 parts by weight Charge control agent (zinc salicylate) 4 parts by weight Colorant (azo dye) ) After thoroughly mixing the mixture consisting of 6 parts by weight with a blender, 12
Melt kneading was performed by two rolls heated to 0 to 140 ° C. The kneaded product was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and adjusted to a volume average particle size of about 8 μm by air classification to obtain a base toner. Further, silica fine powder was added to the base toner 100 by 0.5
And mixed by a mixer to prepare a toner having a shape factor of 55%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. When the porosity of the toner layer on the developer carrying member was set to 70% and subjected to development, the development amount was as high as 1.20 mg / cm ^2, and the reflection density by a Macbeth densitometer was sufficiently high as 1.21. The resolution using the bamboo shoot chart was 9 lines / mm.

Example 2 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized with a cutter mill, finely pulverized with a Kryptron pulverizer manufactured by Kawasaki Heavy Industries, and then subjected to volume classification using an air classifier. With a diameter of about 8 μm, a base toner was obtained. Further, silica fine powder was added to the base toner 100 at a ratio of 0.5 and mixed with a mixer to prepare a toner having a shape factor of 67%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. As a result, when the porosity of the toner layer on the developer carrying member was set to 68% and subjected to development, the development amount was 1.38.
mg / cm ^2, and the reflection density measured by a Macbeth densitometer was 1.35, which was sufficiently high.

Example 3 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then subjected to hot air treatment. Average particle size about 8
μm to obtain a base toner. Further, silica fine powder was added at a ratio of 0.5 to the base toner 100 and mixed with a mixer to prepare a toner having a shape factor of 76%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. As a result, when the porosity of the toner layer on the developer carrying member was set to 71% and subjected to development, the development amount was as high as 1.44 mg / cm ² and the reflection density by a Macbeth densitometer was sufficiently high as 1.38. .

Comparative Example 1 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then subjected to air classification to obtain a volume average particle size of about kneaded. 8 μm to obtain a base toner. Further, silica fine powder was added to the base toner 100 at a ratio of 0.5 and mixed with a mixer to prepare a toner having a shape factor of 55%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated.
When the porosity of the toner layer on the developer carrying member was set to 58% and subjected to development, the development amount was as low as 0.85 mg / cm ^2, and the reflection density by a Macbeth densitometer was as low as 0.97.

Comparative Example 2 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then subjected to air classification to obtain a volume average particle size of about 30%. 8 μm to obtain a base toner. Further, silica fine powder was added to the base toner 100 at a ratio of 0.5 and mixed with a mixer to prepare a toner having a shape factor of 55%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated.
When the toner layer on the developer carrying member was subjected to development with the porosity of 80%, the developed amount was as low as 0.78 mg / cm ² and the reflection density measured with a Macbeth densitometer was as low as 0.83.

Comparative Example 3 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then subjected to air classification to obtain a volume average particle size of about 30%. 8 μm to obtain a base toner. Further, silica fine powder was added at a ratio of 0.5 with respect to the base toner 100 and mixed with a mixer to prepare a toner having a shape factor of 35%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated.
When the porosity of the toner layer on the developer carrying member was set to 70% and subjected to development, the development amount was as low as 0.75 mg / cm ^2, and the reflection density as measured by a Macbeth densitometer was as low as 0.88.

Comparative Example 4 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then subjected to air classification to obtain a volume average particle size of about 40%. 8 μm to obtain a base toner. Further, silica fine powder was added to the base toner 100 at a ratio of 0.5 and mixed with a mixer to prepare a toner having a shape factor of 90%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated.
When the porosity of the toner layer on the developer carrier was set to 70% and subjected to development, the amount of development was as low as 0.72 mg / cm ^2, and the reflection density by a Macbeth densitometer was as low as 0.83.

Example 4 The same toner as in Example 1 was used in a laser printer PC-6000 manufactured by Ricoh Co., Ltd. using a developer carrying member in which a microfield electric field was formed under the same mechanical conditions. The amount increased to 1.35 mg / cm ² ,
The reflection density measured by the Macbeth densitometer also increased to 1.31.

Example 5 A kneaded product having the same formulation as in Example 1 was allowed to cool naturally, coarsely pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and then subjected to air classification to obtain a volume average particle size of about 5%. It was 12 μm to obtain a base toner. Further, silica fine powder was added to the base toner 100 at a ratio of 0.5 and mixed with a mixer to prepare a toner having a shape factor of 58%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. When the porosity of the toner layer on the developer carrying member was set to 72% and subjected to development, the development amount was 1.15 mg / cm ² and the reflection density measured by a Macbeth densitometer was 1.21. The resolution using the bamboo shoot chart was 6 lines / mm.

Comparative Example 5 Binder resin (styrene-acrylic copolymer) 100 parts by weight Release agent (low molecular weight polypropylene) 5.5 parts by weight Charge control agent (zinc salicylate) 10 parts by weight Colorant (azo dye) ) After thoroughly mixing the mixture consisting of 6 parts by weight with a blender, 12
Melt kneading was performed by two rolls heated to 0 to 140 ° C. The kneaded product was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and adjusted to a volume average particle size of about 8 μm by air classification to obtain a base toner. Further, silica fine powder was added to the base toner 100 by 0.5
And mixed by a mixer to prepare a toner having a shape factor of 55%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. The charge amount of the toner on the developer carrier was as high as −26 μC / g. However, when the toner layer was subjected to development with a porosity of 67%, the development amount was as low as 0.94 mg / cm ^2. The reflection density was as low as 0.89.

Comparative Example 6 Binder resin (styrene-acrylic copolymer) 100 parts by weight Release agent (low molecular weight polypropylene) 5.5 parts by weight Charge control agent (zinc salicylate) 0.2 part by weight Colorant (azo After mixing the mixture consisting of 6 parts by weight sufficiently with a blender, 12
Melt kneading was performed by two rolls heated to 0 to 140 ° C. The kneaded product was allowed to cool naturally, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and adjusted to a volume average particle size of about 8 μm by air classification to obtain a base toner. Further, silica fine powder was added to the base toner 100 by 0.5
And mixed by a mixer to prepare a toner having a shape factor of 55%. This was placed in a laser printer PC-6000 manufactured by Ricoh and evaluated. The charge amount of the toner on the developer carrier was as low as −1.56 μC / g, and the toner layer was subjected to development with a porosity of 69%.
It was as low as 83 mg / cm ^2, and the reflection density measured with a Macbeth densitometer was as low as 0.79. Further, fogging occurred in the non-image area.

[0032]

According to the first aspect of the present invention, a non-magnetic one-component toner is used as a one-component developer particularly for developing an electrostatic latent image, so that the toner sufficiently adheres to the developer carrying member and is efficiently used. Development, and as a result, a good image with high image density and high resolution is obtained. According to the second aspect of the present invention, the toner adhesion on the developer carrying member becomes better, so that a higher quality image can be obtained. According to the third aspect of the present invention, the resolution is improved, and the image quality is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a porosity of a toner layer on a developer carrying member and a toner adhesion amount.

FIG. 2 is a diagram showing a relationship between a porosity of a toner layer on a developer carrying member and development efficiency.

FIG. 3 is a diagram illustrating a relationship between a toner shape coefficient and a toner adhesion amount.

FIG. 4 is a diagram illustrating a relationship between a toner shape factor and a development efficiency.

FIG. 5 is a diagram illustrating a relationship between a porosity of a toner layer on a developer carrying member and a development amount.

FIG. 6A is a schematic cross-sectional view of an example of a developing device that forms a microfield electric field on a developer carrying member useful for carrying out the present invention, focusing on a developer carrying portion.
FIG. 2B is a schematic cross-sectional view illustrating a state in which a closed electric field is generated by a microfield on the developer carrying member in the device illustrated in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 electrostatic latent image holder 20 toner carrier member (toner transport member) 30 toner layer thickness regulating member 40 toner supply member 50 stirring blade 60 toner 70 toner tank 80 development area

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kanjiro Kawasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-4-212174 (JP, A) JP 60-158470 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08

Claims (3)

(57) [Claims] 1. A developer carrying member having a shape factor of 50 to 85.
% Of toner particles in a thin layer and supplied, and a latent image holding member is contacted or non-contacted to visualize an electrostatic latent image.
% To develop the electrostatic latent image. 2. The toner carrier according to claim 1, wherein the developer carrier has a substantially smooth surface, and the conductive portion and the dielectric portion are mixed in a small area to form a microfield electric field, thereby applying the toner in multiple layers. Development method. 3. The volume average particle diameter of the toner is 4 to 10 μm.
3. The developing method according to claim 1, wherein m is m.