JPH08305075A - Toner and noncontact developing method using that - Google Patents

Abstract

PURPOSE: To provide a toner which can realize stable jet development and to provide a noncontact developing method using this toner by suppressing the intergranular force of a toner to <5nN except for the image force generating on the toner which is carried by a toner carrying body. CONSTITUTION: When a toner is deposited on a toner carrying body 2, the intergranular force Fv calculated by Fv=q.E-Fi is controlled to <5nN. In formula, q.E is the Coulomb force calculated by q.E=q. Vb+Q/ M).δ.P.dt1 <2> /(2εoεT)}/(εT.g+dt1 ), and Fi is the image force calculated by Fi= (W1 .πd<3> .δ)/(6εoεT)}.(Q/M)<2> . In formula, q is the charge amt. of toner particles to be developed, E is the intensity of the electric field effecting on the toner layer, Q/M is the specific charge of the toner, W1 is the toner amt. separated by development from the toner deposited on the carrying body, εT is the apparent relative dielectric const, of the toner layer P is the toner packing rate, d is the toner particle size, and dt1 is the thickness of the toner layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner of an image forming apparatus such as a copying machine, a laser printer and a facsimile and a non-contact developing method using the same, and particularly, it is opposed to a toner on a toner carrier with a gap. The present invention relates to a toner applied to a non-contact developing device that visualizes an electrostatic latent image by causing toner to fly to an electrostatic latent image holder by an electrostatic force, and a non-contact developing method using the toner.

[0002]

2. Description of the Related Art Conventionally, a charged toner is carried on a toner carrier, and the toner and the electrostatic latent image carrier are arranged in non-contact with each other by an electrostatic force acting between the toner and the electrostatic latent image. An electrostatic copying machine for developing is known (Japanese Patent Publication No. 41-9475).
According to the Japanese Patent Publication No. 41-9475, the toner adheres only to the location corresponding to the image portion of the electrostatic latent image in the non-contact developing method, so that a copy image free from background stain can be obtained. It is described that it is possible.

However, when the non-contact developing method is compared with the contact developing method, the contact developing can mechanically convey the toner to the electrostatic latent image portion, whereas the non-contact developing causes the toner to fly by electrostatic force. It is necessary to secure a sufficient amount of development unless the electrical properties of the toner and the development conditions of the developing device are adequately optimized. Therefore, Japanese Patent Publication 4
Japanese Patent Laid-Open No. 1-9475 only describes the basic idea of the non-contact developing method, and does not disclose the above-mentioned toner physical properties and developing conditions, so that practical application is difficult.

As an example of applying a non-magnetic one-component toner to color development in which a DC electric field is fly-developed, a paper (1) of "one-drum color superposition process-DC electric field fly-development method-" has been published (Electrophotographic Society). Vol. 29, No. 1, 1990,
reference). According to the above-mentioned paper (1), the mirror image force, which is the adhesive force acting on the toner laminated on the toner carrier, is reduced, and the flight property of the toner from the toner carrier to the electrostatic latent image carrier is increased. Have put into practical use color development in which non-magnetic one-component toner is fly-developed with a DC electric field. Further, in order to obtain sufficient flight properties, a non-magnetic one-component toner having a relatively large particle diameter of 12 μm is used, and the specific charge, which is the charge amount per unit mass of the toner, is reduced to a low value of 1 to 5 μC / g. It is set.

This is because when the specific charge of the toner increases,
Since the image force Fi, which is the electrostatic adhesion force of the toner, increases in proportion to the square of the specific charge, it is considered that the image force Fi increases, the flight property decreases, and the developing property decreases significantly. . Therefore, if the toner particle size is reduced, the specific surface area of the toner increases, and accordingly, the toner specific charge increases, so that it is necessary to increase the toner particle size. Further, when the small particle size toner is applied to the non-contact development, the non-contact development requires a larger Coulomb force than the contact development, so that the flying property of the small particle size toner is significantly reduced. For this reason, there is a problem in that a toner having a small particle diameter, which is originally extremely effective in improving image quality, cannot be used in the non-contact developing method. In the non-contact developing method, the particle size of the toner is large and the specific charge of the toner is small. Further, the non-magnetic one-component toner is used in the DC electric field flight developing method because toner images of a plurality of colors can be superposed without color mixture, which is suitable for colorization.

Further, as a method for reducing the toner adhesion force on the toner carrier, a method has been proposed in which mechanical vibration other than electrostatic force is applied to the developing section to promote the flying property of the toner. In the developing device described in Japanese Patent Application Laid-Open No. 5-232802, a method is disclosed in which a vibrating member that comes into contact with a belt-shaped toner carrier is provided to reduce the toner adhesion force on the toner carrier to promote flight performance. There is. Japanese Patent Laid-Open No. 5-
In the color image forming apparatus described in Japanese Patent No. 297711,
At the start of toner flight, a small impact toner is made to fly easily by applying a mechanical shock to the developing device.

Further, in the case of a non-magnetic one-component toner, the toner cannot be conveyed by the magnetic force, so that the conveyability becomes insufficient unless the fluidity of the toner is good. For this reason, a method is known in which other particles are added to the toner for the purpose of improving the charging and fluidity of the non-magnetic one-component toner (Japanese Patent Publication No. Sho 5).
No. 9-7098, electrostatic latent image developing method, Japanese Patent Publication No. 2-4
5191, development method).

In Japanese Examined Patent Publication No. 59-7098, a toner is charged with a one-component developer containing hydrophobic silica as a component by triboelectric charging, and then supplied to a developing section. It improves the fluidity of the toner and prevents aggregation. Tokuhei 2
In Japanese Patent Laid-Open No. -45191, 1 part of granulated silica powder having a particle size of 1 to 100 μm is added to 100 parts by weight of insulating toner particles.
The content of 50 parts by weight improves the triboelectrification performance of the toner.

Further, a layer thickness of about 15 to 10 is formed on the toner carrier.
0 .mu.m, packing density 0.1 to 0.6 g / cm ³ of carrying the toner, a method of flying developed by the developing distance 100~500μm is known (U.S. Pat Nanba4,666,814, JP 60 -87347 gazette, reference). Further, a layer thickness of about 15 to 80 μm and a packing density of 0.1 to 0.
6g / cm ³ , charge density Q (C / m ² ) is 3 × 10 ^-10 ≦ | Q |
≤10 ^-7 toner is carried, development interval is 100-500μ
A method of fly-developing with m is known (US Patent No.
4,666,815, JP-A-60-87343,
reference).

In addition, "ELECTROSTATIC INFLUENCE OF THE
As announced in the paper (2) of "TONER LAYER ON THE PHOTOCONDUCTOR", the layer thickness is about 30μ on the toner carrier.
m, a toner with a specific charge of 3 μC / g, and a developing interval of 100-
A method of fly-developing at 500 μm is known (Sixth In
ternational Congress on Advances in Non-ImpactPrin
ting Technologies, p.34 (1990)).

[0011]

However, as described in the above-mentioned paper (1), in the flight developing method using a toner having a large particle size and a low specific charge in order to improve the flight property, There is a problem in that toner of opposite charge (non-polar toner) that does not contribute to development is likely to be generated, and the background fog and the sharpness of the edge are deteriorated and the image quality is deteriorated.

This problem is particularly remarkable in the case of a one-component toner. This is because in the two-component toner, the toner itself is easily charged to the normal polarity because it is charged by the friction between the carrier having the opposite charging polarity to the toner and the toner, but in the one-component toner, the carrier is not used. This is because toner is likely to be generated. In particular, when a low-charge one-component toner is used, the reverse polarity toner ratio may reach 30% of the developed toner.

Further, the method of developing a non-magnetic one-component toner with a DC electric field has a problem of toner layer scattering common to non-magnetic toners. Unlike magnetic toner, non-magnetic toner cannot be stacked and carried on the toner carrier by the force of the magnet, so toner is mainly an image force (electrostatic adhesion force).
However, if the specific charge of the toner is small, the mirror image force becomes small, so that the toner tends to scatter and the developability deteriorates.

As described above, the method of developing a non-magnetic single-component toner with a DC electric field is suitable for colorization,
In terms of image quality, there are many points that are inferior to conventional development methods such as two-component magnetic brush development. As a practical means for commercialization, black toner uses a two-component magnetic brush development method using toner with a small particle size. However, the color toner alone may be developed by a non-contact developing method using a non-magnetic one-component toner having a relatively large particle diameter, which causes a problem of complicating the apparatus. If the toner particle size is large, the distance between the center of gravity of the toner on the uppermost surface of the toner carrier and the electrostatic latent image is large even though the development gap is constant, so the electric field pattern of the latent image that acts on the toner is large. Is attenuated and the resolution of the image after development is reduced. In addition, in the non-contact development, there is a problem that the edge density is emphasized by the development pattern due to the peripheral speed relationship between the toner carrier and the electrostatic latent image carrier.

JP-A-5-232802 and JP-A-5-232802
In the method of Japanese Patent Publication No. 297711, a toner having a small particle diameter can be used, but there are problems that the toner carrier is limited to the belt, and a means for applying mechanical vibration or impact is additionally required. However, there is also a problem that the complexity and cost of the device increase. According to the methods of Japanese Patent Publication No. 59-7098 and Japanese Patent Publication No. 2-45191, silica is externally added to the toner to improve the chargeability and fluidity of the non-magnetic one-component toner, but it is non-contact. No correlation is described with respect to the adhesive force acting on the toner, which is an important point in developing.

US Patent No. 4,666,814 (JP-A-60-87347), U.S. Pat. 4,66
6,815 (JP-A-60-87343) and the 6th International Conference on Non-Impact Printing Technology (6)
th NIP) paper (2) is characterized in that a toner having a lower specific charge or charge density is carried on a toner carrier with a lower packing density and a thicker toner layer thickness. However, it has been experimentally found that the conventional developing method which does not take the interparticle force of the toner into consideration is remarkably inferior in developability and is not practical.

Practically, the adhesive force acting on the toner stacked and carried on the toner carrier includes an electrostatic adhesive force called the image force Fi and an electrostatic force other than the electrostatic force called the interparticle force Fv. It was found from the physical properties of the toner, the adhesion formula and the flight experiment that suppressing the interparticle force Fv other than the image force Fi acting on the toner is an important point for non-contact development. Therefore, it has been experimentally found that if the adhesion force Fv other than the electrostatic force is reduced, it is possible to sufficiently perform flight development regardless of the particle size of the toner, and even with a toner having a large specific charge. Therefore,
By suppressing the inter-particle force and clarifying its size, it is possible to adopt a small particle size toner, which is originally extremely effective for improving image quality, in the non-contact developing method, and the above-mentioned problems in the prior art are solved.

The present invention has been made in view of the above circumstances, and a toner capable of obtaining excellent image quality by suppressing the interparticle force Fv which is an adhesive force other than the electrostatic force Fi acting on the toner. And a non-contact developing method using the same. Another object of the present invention is to set the interparticle force of the toner to be 0.01 μN to 5 nN and
An object of the present invention is to provide a toner capable of non-contact development even with a toner having a particle diameter of m or less. Another object of the present invention is to provide a toner capable of non-contact development with an average particle diameter of the toner of 5 μm to 11 μm and a specific charge of 5 μC / g to 15 μC / g. is there.

As another object of the present invention, the specific charge of the toner is 5 μC / g to 15 μC / g, the thickness of the toner layer laminated on the toner carrier is about 5 μm to 20 μm, and the packing density is there is to provide a toner which is capable of non-contact development in the range of about ^{0.4g / cm 3 ~0.85g / cm 3} . Another object of the present invention is to suppress the interparticle force Fv, which is an adhesive force other than the electrostatic force Fi acting on the toner, to 5 nN or less,
It is an object of the present invention to provide a non-contact developing method that realizes stable flight development only by controlling electrostatic force acting on toner and electric field strength.

Further, another object of the present invention is to control the specific charge within a predetermined range by controlling the inter-particle force of toner other than the electrostatic force acting on the toner laminated on the toner carrier to 5 nN or less. It is to provide a contact developing method. Also,
Another object of the present invention is to provide a non-contact developing method capable of avoiding edge enhancement which is a problem peculiar to non-contact developing. Still another object of the present invention is to avoid edge enhancement even under the condition that the toner having a large specific charge and a small amount of toner separated by development among toners stacked and carried on a toner carrier and avoiding necessary development. It is to provide a non-contact developing method that can secure the amount.

[0021]

According to the present invention, when the toner is stacked and carried on the toner carrier, the interparticle force calculated by the following formula (1) is 5 nN or less, and Fv = q.E-Fi. (1) [In the formula, Fv is the interparticle force, q · E is the Coulomb force calculated by the formula (2), q · E = q · {Vb + (Q / M) · δ · P · dt ₁ ² / (2ε o ε _T } / (ε _T · g + d t ₁ ) ... (2) In the formula, Fi is the image force calculated by the formula (3), and Fi = {(W ₁ · πd ³ · δ) / ( 6 ε o ε _T )} · (Q / M) ² ··· (3) (In the above formula, q is the charge amount [C] of the toner particles to be developed,
E is the electric field strength [V / m] acting on the toner layer, Q / M is the specific charge of the toner [μC / g], and W ₁ is the toner separated by the development among the toners stacked and carried on the toner carrier. Amount [mg / c
m ² ], ε o is the vacuum permittivity [C / (V · m)], ε _T is the apparent relative permittivity [C / (V · m)] of the toner layer, and d is the toner particle size [μ
m] and δ are true toner densities [g / cm ³ ], g is a gap [mm] between the toner uppermost surface on the toner carrier and the electrostatic latent image carrier, and dt ₁ is a toner layer on the toner carrier. Thickness [μm], Vb is a developing bias voltage [V], and P is a toner filling rate)].

The developer in the present invention may be either a one-component developer or a two-component developer. The one-component developer is composed only of toner, while the two-component developer is composed of toner and carrier (for example, iron powder, ferrite powder, magnetite powder, etc.). In the case of a two-component developer, the electric adhesion force includes the image force and the clonal force between the toner and the carrier. Therefore, if this resultant force is newly defined as Fi, then Fv = q.E-Fi Can be calculated. Among them, the one-component developer is preferable from the viewpoint that toner images can be overlaid with each other without color mixture and maintenance is easy. Hereinafter, the one-component developer will be described. The one-component developer that can be used in the present invention consists of toner only. Here, the toner generally contains a binder resin as a main component, and includes a colorant, an internal additive and an external additive which are optionally contained.

The binder resin that can be used in the present invention is not particularly limited, and any known material can be used.
Styrene-based homopolymers such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, styrene-p-
Chlorostyrene copolymer, styrene-propylene copolymer, 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,
Examples thereof include styrene-based copolymers such as styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, and styrene-based terpolymers such as styrene-acrylonitrile-indene terpolymer.

In addition, polymethylmethacrylate,
Polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic Hydrocarbon resins, aromatic petroleum resins and the like are also included.
These binder resins may be used alone, or may be mixed.

The colorant that can be used in the present invention is not particularly limited and any known material can be used. Examples thereof include carbon black, phthalocyanine blue, indanthrene blue, pegok blue, permanent red, lake red and rhodamine lake. , Hansa Yellow, Permanent Yellow, Benzidine Yellow and the like. Examples of internal additives that can be used in the present invention include charge control agents and fillers. Of these, the charge control agent is not particularly limited, and any known material can be used. For example, a negatively chargeable charge control agent such as a metal complex salt compound, a positive chargeability such as an azine dye or an alkylammonium compound. Examples of charge control agents include

Further, examples of the external additive that can be used in the present invention include fluidizing agents (for example, aliphatic carboxylic acid salts and the like), cleaning agents (for example, higher fatty acids) and the like. Further, the interparticle force between the toners is weakened, and the interparticle force (adhesive force) Fv of the flying portion cross section of the toner layer on the toner carrier is set to 5
In order to control the nN or less, inactive fine particles may be dispersed in the toner as a spacer between the toners. Examples of the inactive fine particles include silica powder. The fine particles are preferably particles having a diameter of 0.01 to 1 μm. If it is smaller than 0.01 μm, the effect of weakening the interparticle force between toner particles is low, and if it is larger than 1 μm, the size is close to that of the toner and the image is adversely affected. The external additive may be dispersed in the toner in advance, or may be dispersed in the toner in the developing stage.

The toner used in the present invention can be manufactured by using a known method. That is, a uniform dispersion is formed by subjecting the binder resin, the colorant and the internal additive to the melt-kneading step. Next, after cooling the above dispersion, it is subjected to a pulverizing step so as to have a predetermined average particle diameter. Further, by passing through a classification step, coarse particles and fine particles can be removed to obtain a toner having a predetermined average particle diameter. Here, the average particle diameter of the toner is
It is preferably 5 to 11 μm. When it is less than 5 μm, the Coulomb force acting on the toner is reduced and the image force is increased, so that the flight force of the toner is reduced and the developability is lowered, which is not preferable, and when it is more than 11 μm, the resolution and the gradation reproducibility are lowered. It is not preferable.

Therefore, the following toners are preferable as the toner of the present invention. The toner has an interparticle force of 0,
It is preferably from 01nN to 5nN. The toner preferably has an average particle size of 5 to 11 μm. It is preferable that the toner contains inert fine particles having an average particle diameter of 0.01 to 1 μm as a spacer. The toner preferably has a specific charge in the range of 5 to 15 μC / g. The toner preferably has an average particle size of 5 μm to 11 μm and a specific charge of 5 to 15 μC / g.

[0029] The toner in the toner layer thickness stacked carried on the toner carrying member is about 5Myuemu～20myuemu, it is preferable and its packing density in the range of about 0.4g / cm ³ ~0.85g / cm ³ . The toner has a specific charge of 5 μC / g to 15 μC / g,
The thickness of the toner layer stacked on the toner carrier is about 5
μm to 20 μm, and its packing density is about 0.4 g / cm ^{3 to} 0.85 g / cm
It is preferably in the range of ³ . The toner is preferably an image-forming toner which contains a binder resin as a main component and optionally contains a colorant, an internal additive and an external additive. The toner is preferably a non-magnetic one-component toner. It is preferable that the toner is formed into a predetermined average particle size by a melt-kneading pulverization process.

In another invention, a toner carrier for laminating and carrying charged toner as a developer, an electrostatic latent image carrier arranged opposite to the toner carrier with a gap, and an electrostatic latent image carrier for the toner carrier. In a developing device equipped with at least an electric field application control means for controlling the application of an electric field between latent image holding bodies, the interparticle force of the toner is 5 nN or less when the toner is stacked and carried on the toner carrying body. This is a non-contact phenomenon method in which any one of the toners is used to fly and develop on the electrostatic latent image holding member.

Further, in the non-contact developing method in which the inter-particle force of the toner is 5 nN or less when the toner is stacked and carried on the toner carrier, the electric field application control means has a specific charge of the toner represented by the following formula: (4), 5 μC / g ≤ Q / M ≤ (εo ε _T / W ₁ ) · E (4) (Equation (4) above, E is the electric field strength [V / m] acting on the toner layer.
, Q / M is the specific charge of the toner [μC / g], W ₁ is the toner amount [mg / cm ² ] separated by development among the toners stacked and carried on the toner carrier, and εo is the vacuum dielectric constant. [C / (V ・ m)],
It is preferable to control ε _T so as to satisfy the apparent relative dielectric constant [C / (V · m)] of the toner layer.

For example, when the amount of toner separated by development is W ₁ = 0.3 (mg / cm ² ), the electric field strength E = 2.5 × 10 ⁶ (V / V) in the toner layer having an apparent relative permittivity ε _T = 2. When the electric field of m) is applied, the range of the toner specific charge Q / M is calculated according to the equation (4), the result is 5 ≦ Q / M ≦ 14.8 (μC / g). (Physical properties) and toner charging mechanism are designed. Alternatively, the toner composition or the charging mechanism may be set to previously determine the toner specific charge, and the toner layer electric field strength E that satisfies Expression (4) may be set. The electric field strength E acting on the toner layer depends on the latent image potential, the potential of the toner carrier, the thickness of the toner layer stacked on the toner carrier, and the developing conditions such as the gap between the toner carrier and the electrostatic latent image carrier. Therefore, the electric field strength E can be controlled by controlling these quantities.
To be set.

Further, in the non-contact developing method in which the inter-particle force of the toner is 5 nN or less when the toner is laminated and carried on the toner carrier, the peripheral speed ratio between the toner carrier and the electrostatic latent image carrier is set. The peripheral speed ratio control means further includes a peripheral speed ratio control means for controlling the peripheral speed ratio, and the peripheral speed ratio of the peripheral speed ratio control means is represented by the following formula (5): W _D ≦ W ₁ · k ≦ W _R (5) (formula (5)) Among them, the toner carrier and the electrostatic latent image carrier move in the same direction, k is the peripheral speed ratio of the electrostatic latent image carrier to the toner carrier, and W _R is the toner carrier on the toner carrier. toner adhesion amount ^{[mg / cm 2], W} 1 is among the toner laminated carried on the toner carrying member, the amount of toner to be separated by development ^{[mg / cm 2], W} D is needed development amount [mg / cm ² ]) is preferably controlled to satisfy the above condition.

The relationship of W ₁ <W _D means that the amount W _{1 of} toner separated from the toner carrier by development is less than the required amount W _D of development, and the average specific charge Q / M of the toner is large. This occurs when a toner or a toner having a large adhesive force and poor developability is used. For example, when considering a toner having a large toner specific charge in Expression (4), the right side of Expression (4) = ε o ε _T
It is necessary to increase E / W ₁ , but there is a limit to increase the relative permittivity ε _T of the toner and the electric field strength E that acts on the toner on the right side of Expression (4), and the amount of toner separated by development is limited. W ₁ is inevitably small.

Therefore, the toner amount W ₁ separated from the toner carrier is insufficient to secure the required development amount using the toner having a large specific charge, and the peripheral speed of the toner carrier is changed to the electrostatic latent amount. It is necessary to make it faster than the image carrier to increase the total development amount. When the peripheral speed of the toner carrying member is faster than the peripheral speed of the electrostatic latent image holding member (that is, when the peripheral speed ratio k> 1), the peripheral speed ratio must be set in order to prevent the edge enhancement and ensure the development density. It is necessary to set k and the toner adhesion amount W _R on the toner carrier to satisfy the equation (5).
And a developing device that simultaneously satisfies the expression (5) is essential.

Further, in the non-contact developing method in which the interparticle force of the toner is 5 nN or less when the toner is stacked and carried on the toner carrier, the electric field application control means determines the specific charge of the toner by the above formula (4). It is preferable that the peripheral speed ratio control means controls the peripheral speed ratio between the toner carrier and the latent image carrier to satisfy the above expression (5) at the same time. As the electric field application control means, for example,
It is composed of a DC or AC high voltage generation circuit, an electric field control circuit, and the like. The electric field applied between the toner carrier and the electrostatic latent image carrier by the electric field application controller may be either direct current or alternating current. Further, as the peripheral speed ratio control means,
For example, it is composed of a motor drive circuit, a speed control circuit (including a speed detection circuit and a peripheral speed ratio setting circuit), and is controlled by a microcomputer.

According to the toner of the present invention, the toner is a toner.
When laminated and supported on a carrier, the following formula (1)
Formed on toner with calculated interparticle force of 5nN or less
It Fv = q.E-Fi (1) In the equation, Fv is the interparticle force, and q.E is the equation calculated by the equation (2).
-Long force, q ・ E = q ・ {Vb + (Q / M) ・ δ ・ P ・ dt₁ ²/ (2ε o ε_T} / (Ε_T・ G + dt ₁ ) (2) In the formula, Fi is the image force calculated by the formula (3), and Fi = {(W₁・ Πd³・ Δ) / (6 εo ε_T)} ・ (Q / M)²(3) In the above formula, q is the charge amount [C], E of the toner particles to be developed.
Is the electric field strength [V / m] that acts on the toner layer, and Q / M is the specific electric charge of the toner
Load [μC / g], W₁Is a stack of toner on the toner carrier.
Of toner, the amount of toner separated by development [mg / c
m²], Ε o is the vacuum permittivity [C / (V · m)], ε_TOf the toner layer
Apparent relative permittivity [C / (V m)], d is toner particle size [μ
m] and δ are true densities of toner [g / cm³], G is on the toner carrier
Gap between the top surface of the toner and the electrostatic latent image holder [mm], dt₁Is
The toner layer thickness [μm] on the toner carrier, Vb is the development bias.
As voltage [V], P is the toner filling rate, and
Since it is a constant ε o, based on these measured values, the equation
Particles represented by formula (1) when substituted into (2) to (3)
The force Fv can be calculated.

For non-contact development, a toner having the following physical properties is preferable. The toner has an interparticle force of 0.01 nN to 5
If it is nN, the flight performance is improved. If the average particle size of the toner is 5 to 11 μm, a fine latent image pattern can be reproduced even in non-contact development. If the toner contains inert fine particles having an average particle diameter of 0.01 to 1 μm as a spacer, the interparticle force is reduced. When the specific charge of the toner is in the range of 5 to 15 μC / g, the optimum Coulomb force is obtained without the generation of reverse polarity toner, so that a sufficient developing density can be secured. The toner has an average particle size of 5 μm.
When the specific charge is ˜11 μm and the specific charge is in the range of 5 to 15 μC / g, both reproduction of a fine latent image pattern and securing of the development density can be achieved at the same time.

[0039] If the range of the toner is the toner layer thickness laminated carried to a toner carrying member at approximately 5Myuemu～20myuemu, and ³ the packing density of about 0.4g / cm ~0.85g / cm ^3, a developing The property is improved. The toner has a specific charge of 5 μC / g to 15
μC / g, the thickness of the toner layer laminated on the toner carrier is about 5 μm to 20 μm, and the packing density is about 0.4 g / cm ³ to
Within the range of 0.85 g / cm ³ , the developability is improved. The toner can be produced by a known method as long as it is an image-forming toner containing a binder resin as a main component and optionally containing a colorant, an internal additive and an external additive. If the toner is a non-magnetic one-component toner, the toner images can be overlaid on each other without color mixing, and maintenance is easy. The toner can be formed into a predetermined average particle size by a melt-kneading pulverization process.

Between the toner carrying member and the electrostatic latent image holding member, the toner carrying member carrying the stacked layers of charged toner as a developer, the electrostatic latent image holding member opposed to the toner carrying member with a gap. In a developing device having at least an electric field application control means for controlling the application of the electric field, when the toner is stacked and carried on the toner carrier, the interparticle force of the toner shows 5 nN or less, If a non-contact developing method is used, in which two toners are used for fly-development on the electrostatic latent image carrier, stable fly-development can be achieved, for example, by only controlling the electrostatic force acting on the toner and the electric field strength. Image quality with good reproduction and reproducibility.

Further, in the non-contact developing method in which the inter-particle force of the toner is 5 nN or less when the toner is stacked and carried on the toner carrier, the electric field application control means has a specific charge of the toner represented by the following formula: If the structure is controlled so as to satisfy (4), for example, the optimum Coulomb force can be obtained and the developability can be improved. 5 μC / g ≦ Q / M ≦ (ε o ε _T / W ₁ ) · E (4) In the formula (4), E is the electric field strength [V / m] acting on the toner layer,
Q / M is the specific charge of the toner [μC / g], W ₁ is the toner amount [mg / cm ² ] separated by development among the toners stacked on the toner carrier, and εo is the vacuum dielectric constant [ C / (V · m)], ε
_T is the apparent relative permittivity [C / (V · m)] of the toner layer.

In the non-contact developing method in which the inter-particle force of the toner is 5 nN or less when the above toner is stacked and carried on the toner carrier, the peripheral speed ratio between the toner carrier and the latent electrostatic image carrier is controlled. If peripheral speed ratio control means is further provided and the peripheral speed ratio control means controls the peripheral speed ratio to satisfy the following expression (5), it is possible to secure development density while preventing edge enhancement. _D ≦ W ₁ · k ≦ W _R (5) In the formula (5), the toner carrier and the electrostatic latent image carrier move in the same direction, and k represents the electrostatic latent image carrier to the toner carrier. The peripheral speed ratio with the body, W _R is the toner adhesion amount [mg / cm ² ] on the toner carrying body carrying the toner, and W ₁ is separated by development among the toners carried on the toner carrying body in a laminated manner. The toner amount [mg / cm ² ] and W _D are the required developing amount [mg / cm ² ].

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the embodiments shown in the drawings. The present invention is not limited to this. FIG. 1 is a sectional view showing a schematic configuration of an embodiment of a developing device applied to the toner of the present invention and a non-contact developing method using the toner. Further, in the present invention, FIG.
The developing device shown in is used as a flight developing experiment machine. In FIG. 1, the non-magnetic one-component toner 1 is put into a hopper 7, and while being stirred by a toner stirring member 5,
Toner carrier (developing roller) by toner supply member 6
2 on top. The toner carrier 2 is formed of an aluminum metal sleeve having a diameter of 31.4 mm and a length of 315 mm,
It is sandblasted with spherical particles and has a surface roughness of center line average roughness Ra = 1 μm.

The non-magnetic one-component toner 1 is charged by the contact and rubbing between the supply member 6 and aluminum,
The toner is carried on the toner carrier 2 and is charged again when passing through the blade 4 for charging and regulating the toner to regulate the layer. A load of 1 kgf to 3 kgf is applied to the blade 4 and is brought into contact with the toner carrier 2. The specific charge of the toner is determined by the inherent charging performance of the toner, the sleeve material of the toner carrier 2, and the degree of friction between the toner and the roller. For example, the larger the load applied to the blade 4 is, the larger the specific charge is. Become.

A drum 3, which is like an electrostatic latent image holder, is arranged opposite to the toner carrier 2. Drum 3 is 80m in diameter
It has a length of m and a length of 320 mm, and has a certain gap (the size of the gap is 0.1 to 0.2 mm) with the toner carrier 2, and the toner on the toner carrier 2 is also kept in non-contact with the drum 3. Is dripping The toner carrier 2 and the drum 3 rotate clockwise at the peripheral speed of 175 mm / sec as shown by the arrow. The toner carrier 2 is grounded, and a bias voltage Vb = -700 V corresponding to the latent image potential is applied to the drum 3 by an electric field control means (not shown) for one rotation of the drum 3. At this time,
The developing bias voltage is 0-(-700) V = 700V.

The experimental machine includes a toner carrier 2 and a drum 3.
And an electric field control means for applying a DC electric field between the two and a toner charging means (blade 4, toner supply member 6) for charging the non-magnetic one-component toner. Further, as means for charging the toner, means such as charge injection from a conductive electrode or corona discharge may be used. Further, a peripheral speed ratio setting means (not shown) for setting the peripheral speed ratio k between the toner carrier 2 and the drum 3, and the toner carrier 2 and the drum 3 are respectively rotated clockwise or counterclockwise at the set peripheral speed ratio. It further comprises a motor speed control circuit (not shown) that drives the motor to rotate at a constant speed in a clockwise direction. Further, it is also provided with an adjusting means (not shown) for finely adjusting the gap between the toner carrier 2 and the drum 3.

FIG. 2 is an enlarged view showing the toner of the present invention and the non-contact developing section applied to the non-contact developing method using the toner. In FIG. 2, the force in the flight direction is the Coulomb force q · E at the dividing plane X inside the toner layer 1 having a thickness dt ₁ formed on the toner carrier 2 which is a metallic sleeve, and hinders the flight. The forces are the image force Fi and the interparticle force Fv at the dividing plane X. The dividing plane X can be known by measuring the toner layer thickness on the developing roller after the flight or the flying amount (developing amount). For example, if a scanning laser microscope manufactured by Lasertec Co., Ltd. is used, the toner layer thickness before and after the flight on the developing roller can be measured, and the dividing plane X can be obtained. If the cross-section X is known, the image force F acting on this plane
i can be calculated.

Therefore, the interparticle force Fv is calculated as follows:
Of the toner stacked on the
Toner amount W₁mg / cm²Toner loading based on actual measurements such as
Coulomb q · E and image force in cross section of toner layer on body
Obtain the difference of Fi from the following equations (1) to (3)
Can be. Fv = q.E-Fi ... (1) q.E = q. {Vb + (Q / M) .delta.P.dt₁ ²/ (2ε o ε_T)} / (Ε_T・ G + dt ₁ ) (2) Fi = {(W₁・ Πd³・ Δ) / (6 εo ε_T)} ・ (Q / M)²(3) In the above equation, Fv is the interparticle force, and q · E is the equation (2).
Coulomb force, where Fi is the mirror image calculated by equation (3)
Power.

Further, q is the charge amount of the toner particles to be developed.
[C] and E are electric field strengths [V / m] that act on the toner layer, Q / M are specific charges of the toner [μC / g], and W ₁ is _one of the toners stacked and carried on the toner carrier by development. Amount of toner separated
[mg / cm ² ], ε o is the vacuum permittivity [C / (V · m)], ε _T is the apparent relative permittivity [C / (V · m)] of the toner layer, and d is the toner particle size.
[μm], δ is the true density of the toner [g / cm ³ ], g is the gap [mm] between the top surface of the toner on the toner carrier and the electrostatic latent image carrier, d
t ₁ is the toner layer thickness [μm] on the toner carrier, Vb is the developing bias voltage [V], and P is the toner filling rate. The toner filling rate P and the apparent relative dielectric constant ε _T of the toner layer can be obtained by using the following equations (6) to (9).

Here, the apparent relative permittivity ε _T of the toner layer is
The method of obtaining In order to obtain the apparent relative permittivity ε _T of the toner layer, it is necessary to know the filling rate P of the toner layer having voids. The filling rate P can be obtained as follows using the measured values of the surface potential Vt, the toner specific charge Q / M, and the toner adhesion amount w. In the experimental machine as shown in FIG. 1, the surface potential Vt of the toner layer 1a on the toner carrier 2 after passing through the blade 4 and the toner average specific charge Q / M.
The toner adhesion amount w was measured.

First, the toner layer surface potential Vt is expressed by the following equation. Vt = w ² · (Q / M) / [2 εo {1 + P (εt −1)} δ · P] (6) When formula (14) is rearranged with respect to P, the following equation is obtained as a quadratic equation of P. Is obtained. (Εt −1) P ² + P−w ² · (Q / M) / (2 εo δVt) = 0 (7) When equation (7) is solved for P, P = [{1 + 2 (εt −1) · W ² · (Q / M) / (εo δVt)} ^1/2 −1] / {2 (εt−1)} (8) Therefore, by substituting the measured values of Vt, Q / M, and w into the equation (8), the filling rate P is obtained, and the apparent relative permittivity ε _T is obtained from the following equation (9). ε _T = 1 + P (εt-1) (9)

From the measured values and the relational expressions described above, it can be confirmed from the equations (1) to (3) and the measured values whether the inter-particle force of the toner stacked on the toner carrier is 5 nN or less. Therefore, it is possible to screen a toner having a small interparticle force Fv by a toner flying experiment on a test bench without performing a copy test, and it is possible to obtain a toner physical property that reaches non-contact development of a small particle non-magnetic one-component toner. The prescription can be efficiently found.
Although the developing bias voltage is set to the same value as the latent image potential in this embodiment, the developing bias voltage may be different from the latent image potential. That is, since the interparticle force Fv can be obtained from the toner separation amount W _{1 with} respect to the developing bias voltage Vb, the developing bias voltage Vb can take a voltage value between the developing start voltage and the developing saturation voltage. In the above experimental machine, the inter-particle force of the toner, which is an adhesive force other than the electrostatic force, was adjusted to 5 nN or less, and as a result of an experiment of non-contact development, it was found that regardless of the particle size of the toner, a large specific charge We found that there is a solution that can be developed with toner (Fig. 12).
Table, see).

Specific charge Q / M in which contactless development is possible
It was found that the range can be controlled only by the electrostatic force so as to satisfy the following formula (4). 5 μC / g ≦ Q / M ≦ (ε o ε _T / W ₁ ) · E (4) In the formula (4), E is the electric field strength [V / m] acting on the toner layer,
Q / M is the specific charge of the toner [μC / g], W ₁ is the toner amount [mg / cm ² ] separated by development among the toners stacked on the toner carrier, and εo is the vacuum dielectric constant [ C / (V ・ m)],
ε _T is the apparent relative permittivity [C / (V · m)] of the toner layer.

The process of deriving equation (4) will be described below. As a result of conducting an electric field analysis that acts on the toner layer and the development gap g (the gap between the toner uppermost surface on the toner carrier and the electrostatic latent image carrier), the flying amount (developing amount) M / A per unit area is It was found to be expressed by equation (10). M / A = {6 ε o ・ ε _T / (πd ³ δ)} ・ [{(πd ³ δ / 6) ・ (Q / M) ・ E−Fv} / (Q / M) ² ] ・ ・ ・ (10 ) equation (10) in E represents the electric field intensity acting on the toner layer, E = {Vb + (Q / M) · δ · P · dt 1 2 / (2εo ε T)} / (ε T・ G + dt ₁ ) (11)

Here, in the formula (10), ε o: vacuum permittivity (8.85 × 10 ⁻¹² C / (V · m)) ε _T : apparent relative permittivity of toner layer d: toner particle size δ: toner True density Q / M: Toner specific charge (charge amount per unit mass) Fv: Interparticle force of toner; Flight restraining force other than mirror image force in flight cross section dt ₁ : Toner layer thickness on toner carrier Vb: Development Bias voltage P: Toner filling rate g: Gap between the uppermost toner surface on the toner carrier and the electrostatic latent image carrier

Ε _{T in} equations (10) and (11) is the apparent relative permittivity of the toner layer, and the relative permittivity ε _t peculiar to the toner.
From the filling rate P of the toner layer, the above equation (9) ε _T = 1 + P (ε _t −1) (9) Now, the condition that the developing amount M / A is W ₁ or more is W ₁ ≦ M / A = {6 εo ε _T / (πd ³ δ)} ・ [{(πd ³ δ / 6) ・ (Q / M) · E−F v} / (Q / M) ² ] ... (12) Here, when the inter-toner particle force F _V is sufficiently small, it can be considered that F _V ≈0.
= 0 and when put, minimum requirements development amount M / A is W ₁ or more, (Q / M) · { W 1 (Q / M) -εo ε T · E} ≦ 0 ‥‥ (13) Becomes Accordingly, the scope of the Q / M satisfying the formula (13), 0 ≦ Q / M ≦ ( εo ε T / W 1) · E ‥‥ (14) is obtained. Formula (14) is the development amount M /
This is a necessary condition for obtaining A.

[0057] Furthermore, the electric field E acting on the toner layer shown by the formula (11), compared to the gap g, when the toner layer thickness dt1 is _{smaller, E ≒ Vb / (ε T} · g) = Eg / ε T (15) (Eg in the formula is a void electric field; Eg = Vb / g), so formula (14) is expressed as 0 ≤ Q / M ≤ εo · Eg / W ₁・ ・ ・ (16) It can also be simplified. The formula described above can be applied regardless of the toner polarity. When negatively charged toner is used, its size (absolute value) may be set so as to satisfy the above inequality.

Next, the specific charge (Q / M
) And the reverse polarity toner ratio will be described. The toner laminated on the toner carrier has a charge amount distribution. FIG. 3 is a graph showing the distribution of the charge amount of the toner.
In FIG. 3, the horizontal axis represents the specific charge (q / m) _k of the toner particles, and the vertical axis represents the frequency ratio p (k) of the toner particles having the specific charge (q / m) _k . Here, the half-width b of the distribution is considered as a measure showing the spread of the charge distribution. The half-width b is the specific charge value (q / when the frequency ratio p becomes half the maximum frequency ratio pmax.
The difference between (m) ₁ and (q / m) ₂ is (q / m) ₂ − (q / m) ₁ .

Now, the average value Q / M of the specific charges (q / m) _k of the toner
Half-width b when (Q / M = (Σ (q / m) _k · p (k)) changes
Does not change significantly, and the distribution when Q / M changes is X
The shape is shifted in the axial direction. In such a distribution, the reverse polarity toner number ratio _RN is the total number of toner particles having an opposite charge / total number of all toner particles, and the reverse polarity toner volume ratio Rv is the total volume of toner particles having an opposite charge /
It is the total volume of all toner particles. The Q / M is 5 (μC / g) or less of the toner, the reverse polarity toner number ratio R _N, the reverse polarity toner fraction Rv is will both reached nearly 10%, the image of poor sharpness occurs background fog. On the other hand, Q / M is 5
With a toner larger than (μC / g), both R _N and Rv are smaller than 10%, and the deterioration of image quality is small. Therefore, Q / M
The lower limit of is 5 (μC / g).

From the above, when the toner is stacked and carried on the toner carrier, the interparticle force of the toner is adjusted to 5 nN or less, and the specific charge Q / M of the toner is expressed by the formula (4) 5 (μC / g). By setting the range of ≦ Q / M ≦ (ε o ε _T / W ₁ ) · E, the desired toner amount out of the toner stacked on the toner carrier will leave the toner carrier by electrostatic force. , Can be developed without contact,
Provided is a non-contact developing device having a small ratio of reverse polarity toner and an excellent sharpness even when the specific charge is higher than in the past.

In the case of non-contact development, since the toner carried on the toner carrier in a stacked manner does not fly 100% to the electrostatic latent image carrier, the toner can be used as a means for increasing the amount of development on the electrostatic latent image carrier. There is a method of increasing the peripheral speed of the carrier (developing roller) more than the peripheral speed of the electrostatic latent image holder (photoconductor). However, if the peripheral speed of the toner carrier is increased, the density of the edge portion is emphasized depending on the development pattern, so it is necessary to appropriately control the peripheral speed ratio between the toner carrier and the latent electrostatic image carrier.

In this case, the range of the peripheral speed ratio k in which non-contact development is possible is such that if the speed is controlled so as to satisfy the following equation (5), the predetermined development amount (toner amount) can be obtained without emphasizing the edge density. Was obtained. W _D ≦ W ₁ · k ≦ W _R (5) In the formula (5), the toner carrier and the electrostatic latent image carrier move in the same direction, and k represents the electrostatic latent image on the toner carrier. The peripheral speed ratio with the holding body, W _R is the toner adhesion amount [mg / cm ² ] on the toner carrying body carrying the toner, and W ₁ is separated by development among the toners carried on the toner carrying body in a laminated manner. The toner amount [mg / cm ² ], and W _D are the required developing amount [mg / cm ² ].

Usually, the amount of toner W ₁ [mg / cm 2 which is separated by development among the toners stacked and carried on the toner carrier.
² ] shows that when the moving speed of the toner carrying member is twice as fast as the moving speed of the electrostatic latent image carrying member, about 2 W ₁ [m
g / cm ² ] can be obtained, but when the toner is a non-magnetic one-component toner, the amount of toner that can be attached to the toner carrier is smaller than that of the magnetic toner or the two-component toner. The toner on the carrier is easily exhausted.

In particular, when the latent image pattern changes from the non-developing portion to the developing portion as viewed from the toner carrier side, the developing portion to be developed first (particularly the boundary area between the non-developing portion and the developing portion;
In the latent image edge portion), since the toner is sufficiently present on the toner carrier, the development density is high, and in the other areas, the edge density is low. As a result of experiments, it was found that the location and the degree of such edge enhancement depend on the direction and magnitude of the relative speed of the electrostatic latent image carrier with respect to the toner carrier. The mechanism will be described below.

Here, FIG. 4 is an explanatory view showing an area where an edge-enhanced image is generated. FIG. 5 is an explanatory diagram showing an edge-emphasized image on a recording sheet. FIG. 6 is an explanatory diagram showing the magnitude relationship between the rotational direction and the peripheral speed of the toner carrier and the electrostatic latent image carrier. In FIG. 4, the image portion (developing portion) on the electrostatic latent image carrier 3 is designated as Si, and the non-image portion (non-developing portion) is designated as A and B, and this development pattern is transferred onto the recording paper 50 shown in FIG.
The toner adhered portion when fixed is designated as S _D. As shown in FIG. 4, when the electrostatic latent image holder 3 rotates in the clockwise direction and the toner carrier 2 rotates in the counterclockwise direction, the moving directions of the both are downward in the developing unit, and the moving directions are the same. is there.

Next, as shown in FIG. 6, when the peripheral speed ratio k> 1, that is, the peripheral speed V _{D of} the electrostatic latent image carrier 3 <the peripheral speed V _R of the toner carrier 2 and the static speed is static. the orientation of the relative velocity V _D -V _R with respect to the toner carrying member 2 of the latent image holding member 3 is counterclockwise ((1-b in FIG. 6), reference). As a result, the non-image part B1
The edge B1 that is the boundary between the image portion Si and the image portion Si first encounters the toner on the developing roller, and the developing density of the edge B1 increases. Therefore, the edge B2 on the recording paper 50 is emphasized.

On the other hand, the electrostatic latent image holder 3 and the toner carrier 2
V is the same and the peripheral speed ratio k <1 and the electrostatic latent image holder 3 and the toner carrier 2 are opposite in the moving direction.
_D -V _R becomes clockwise (in FIG. 6 (2-b), reference), so that the boundary edge A1 of the non-image area A and the image portion Si is the first development. Therefore, the development density of the edge A1 is increased and the edge A2 on the recording paper 50 is emphasized.

In order to prevent the edge emphasis, it is necessary to set the developing conditions satisfying the expression (5). For example, the required development amount W _D
0.5 mg / cm ² , of the toner carried on the toner carrier in a laminated manner, the toner amount W ₁ separated by development is 0.3 mg / cm 2.
^{2. When} the toner adhesion amount W _R on the toner carrier is 0.8 mg / cm ² , 0.5 ≦ 0.3 · k ≦ 0.8 and 1.67 ≦ k ≦ 2.67. Therefore, the peripheral speed ratio may be set between 1.67 and 2.67. As described above, the toner adhesion amount W _{R on} the toner carrier, the toner amount separated by the development among the toners stacked and carried on the toner carrier W ₁ , and the toner carrier and the electrostatic latent image holding Edge emphasis can be prevented by defining a relational expression among the moving direction with the body, the peripheral speed ratio k, and the required development amount W _D.

FIG. 7 is a graph for setting the range of the specific charge Q / M of the toner. In FIG. 7, the Y axis is W ₁ [mg /
cm ² ] and the X axis are expressed as Q / M [μC / g]. _{Q / M = (εo ε T} / W 1) · E ≒ (εo / W 1) · (Vb / g) ‥‥ (1-1) Vb = 700V ( developing bias voltage), g = 0.15 mm (gap)
The formula of the graph is as follows: Q / M = 4.13 / W ₁・ ・ ・ (1-2
) When Vb = 900V and g = 0.1mm, the formula of the graph is Q / M = 7.97 / W ₁ ... (1-3) (1-2) In the formula, W ₁ is 0.5mg / cm ² When the value of Q / M is
This is 8.4 μC / g, and the allowable range of the specific charge is in the range of 5 ≦ Q / M ≦ 8.4 μC / g shown in (7a) of FIG. Requires development amount is so ^{0.5mg / cm 2 ~0.6mg / cm 2} , a non-contact developing method which satisfies the equation (4) is provided.

Next, the parameter setting for setting the specific charge to 10 μC / g or more will be described. From the graph (1-2), it can be seen from the graph (1-2) that the toner amount W1 separated from the toner carrier by the development under the condition that the specific charge is 10 μC / g or more is 0.4 mg / cm ² or less. Considering the non-contact development method with W ₁ of 0.3 mg / cm ² , the upper limit of Q / M is 13.5 μC / g.
Since the toner in the range of 5 ≦ Q / M ≦ 13.5 shown in (7b) can be used, a developing device having a wide tolerance can be realized. In this case, since the required development amount is not satisfied, it is essential to satisfy the formula (5).

FIG. 8 is a graph for setting the range of the peripheral speed ratio k. In FIG. 8, Y axis is W ₁ [mg / cm ² ], X
Denote the axis as the value of k. When the _{W D / W 1 ≦ k ≦} W R / W 1 ‥‥ (2-1) W D = 0.5mg / cm 2, W R = 0.8mg / cm 2, k = W D / W 1 = 0.5 / W ₁ (2-2) k = W _R / W ₁ = 0.8 / W ₁ (2-3) For W ₁ = 0.3 mg / cm ² , 1.67 ≦ k ≦ 2.67. Therefore, by satisfying the developing conditional expression of the expression (5), it can be applied to a developing device that can use toner having a large specific charge.

Therefore, if the toner amount W ₁ separated by the development among the toners stacked and carried on the toner carrier reaches the required development amount W _D , it is sufficient to satisfy the formula (4). When the amount W ₁ is smaller than the required development amount W _D , it is necessary to satisfy the formula (5) at the same time. That is, by satisfying the formulas (4) and (5) at the same time, the required developing amount can be secured even for the toner having a large average specific charge or the toner having a relatively large adhesive force and poor developability. It is possible to provide a developing device capable of avoiding edge enhancement and ensuring a required development amount even under a condition where the development amount per toner carrier is small.

In the non-contact developing method of the formula (4), as a method for increasing the specific charge Q / M, the amount of the charge control agent added to the toner is controlled, or the degree of friction in the toner frictional charging mechanism is controlled. There is a method of increasing the charge or forcibly injecting an electric charge into the toner from the outside. To increase the upper limit of Q / M by increasing the electric field strength, there is a method of increasing Vb (developing bias voltage: photoconductor charging potential-developing roller potential) or decreasing the development gap g. For example, in FIG. 7, Vb = 900V, g =
The graph of formula (1-3) when 0.1mm is Vb = 700V
(Development bias voltage), g = 0.15 mm (gap) From the graph of formula (1-2), the specific charge is shifted to the larger one. Therefore, it is possible to configure a developing device having a wider allowable range of specific charges.

The present invention is to provide a method capable of developing a toner having a small particle diameter of 11 μm or less in a non-contact manner. As described above, the developability of the small particle size toner is lowered, but the reason will be described below. The condition necessary for the above-mentioned flight development is a condition in which the interparticle force Fv other than the image force acting on the toner is set to 0, and the formula (11) does not depend on the toner particle size. Since the inter-particle force Fv has a value, the flying property of the toner depends on the particle size.

For example, when the developing amount M / A is calculated using the equation (10), it becomes as shown in FIG. 9, and the smaller the particle size, the lower the flight property. FIG. 9 is a graph showing the relationship between the toner particle diameter d and the development amount Q / A with respect to the toner particle force Fv. Further, when the allowable range of the developable specific charge with respect to the toner particle force Fv value is calculated, it becomes as shown in FIG. FIG. 10 is a graph showing the allowable range of the toner specific charge Q / M with respect to the toner particle force Fv.

In FIG. 10, the force between toner particles Fv = 0,
The permissible range of specific charge at 2, 5nN is A, B, C (A> B
> C), and it is understood that when the value of the inter-toner particle force Fv increases, the toner flying force for securing the required development amount decreases and the specific charge allowable range narrows. This hinders the improvement of the development image quality as described above. As described above, it is important to reduce the interparticle force Fv of the toner in order to make it possible to develop the toner having a small particle diameter and a relatively high electric charge.

FIG. 11 is a graph showing the relationship between the toner specific charge and the development amount with respect to the toner particle diameter / interparticle force. For example, as shown in FIG. 11, a toner having a particle size of 12 μm can secure a developing amount M / A of 0.25 mg / cm ² even if the toner particle force Fv is 6 nN, but in the case of a toner having a particle size of 7 μm, Fv is 6 nN, The amount of development is greatly reduced. On the other hand, under the condition of Fv = 1nN, even a toner having a particle diameter of 7 μm can have a flight property equivalent to or more than that of a 12 μm toner. From FIGS. 10 and 11, the particle size 11
0.25 mg of toner separated by development, out of toner that is stacked and carried on the toner carrier with toner of μm or less
It is understood that Fv needs to be 5 nN or less to secure / cm ² or more.

Decreasing the interparticle force Fv, which is the toner adhesion force, means that the control can be performed only by the electrostatic force. Originally, the toner interparticle force Fv value is easily affected by the environment such as temperature and humidity, and therefore the flight property of the toner is affected, so that stable flight development cannot be obtained, but a toner with a small Fv value is originally used. By using, it is possible to use a toner having a relatively high specific charge, and it is possible to facilitate electrical control. Therefore, the object is to provide a non-magnetic one-component toner having a small interparticle force Fv.
The following non-magnetic one-component toners were variously manufactured and F
When v was evaluated, it was found that the effect of reducing the Fv value was great when fine particles having a diameter of 0.01 to 1 μm were added.

The method of adding other particles to the toner for the purpose of improving the characteristics of the toner is described in JP-B-59-7098.
And Japanese Patent Publication No. 2-45191. Japanese Patent Office Sho 59
JP-A-7098 discloses that a toner contains hydrophobic silica to improve the fluidity of the toner and prevent aggregation. Tokufair 2
In Japanese Patent Laid-Open No. 45191, a granulated silica powder having a particle size of 1 to 100 μm is contained to improve the triboelectric charging performance of the toner. In the present application, regarding the charging performance of the toner, CC
It is controlled by adding A (toner charge control agent), and fine particles having a diameter of 0.01 to 1 μm are contained as a factor for controlling the adhesive force of the toner.

Diameter of toner having an average particle size of 11 μm or less
When particles of 0.01 to 1 μm are contained, the inter-particle force between the toners can be weakened, and the inter-particle Fv in the flying surface of the toner layer on the toner carrier can be set to 5 nN or less. As a result, the development amount can be secured by the flight development even for the small particle diameter toner of 11 μm or less. If particles with a diameter of less than 0.01 μm are included in a toner with an average particle size of 11 μm or less, the effect of reducing the adhesive force is low, and if particles with a diameter of more than 1 μm are included, the size is close to that of toner particles. , Adversely affect the image quality. As described above, the interparticle force Fv other than the image force Fi acting on the divided surface of the toner layer on the toner carrier is determined, and by setting this value to 5 nN or less, even small-sized toner particles with a diameter of 11 μm or less are not The amount of development can be secured by contact.

FIG. 12 is a table showing the results of the flight test of the toner of the present invention. As shown in FIG. 12, toners having different average particle diameter d, average specific charge Q / M, and interparticle force Fv (toners A to
The results of the toner flight experiment for F) are shown in the table. In FIG. 12, in the items [1] to [21],
The measured values of the items [7] to [13] represent average values when the same measurement was performed three times. Toner A has an average particle size of 1
The toner has a size of 2.3 μm and a small specific charge of 2.1 μC / g. No external additive is added to this toner. Therefore, the interparticle force Fv is a relatively large value of 6.77nN.

Toner B has a small average particle size of 7.3 μm,
It is a highly charged toner with a specific charge of 31.9 μC / g, and no external additive was added to this toner either. The interparticle force Fv at this time is 8.28 nN. Toner C has the same average particle size as toner B, 7.3 μm, and specific charge of 14 μC / g.
And has an intermediate value between A and B. Silica particles having an average particle diameter of 0.02 μm are externally added as an external additive. The interparticle force Fv at this time is 0.79 nN. Toner D has an average particle size of 7.3
μm, specific charge 5.1 μC / g, average particle size as external additive
0.5 μm conductive particles were added. The interparticle force Fv at this time is 0.47 nN. The toners E and F are as shown in the table.

With respect to Toner A to Toner E, the required amount of development was 0.3 mg / cm ² , and the upper limit of the specific charge calculated from equation (14) was 17.3, 14.3, 20.0, 21.8, 20.6 μm, respectively.
It is C / g, and it is understood from the table that the toners A, C, D, and E are within the range of the formula (14), but the specific charge of the toner B is outside the proper range. In the experiment, the flying amount W _{1 of} toner A is 0.36 mg / cm ² , and the flying amount W _{1 of} toner C is 0.30 mg / c.
m ^2, the toner D flying amount W ₁ is 0.28 mg / cm ² of a flight weight W ₁ is 0.30 mg / cm ² of toner E, the value close to the required amount of development is obtained, jumping of toner B The amount W ₁ is 1/100 of the target and almost undeveloped. From the above, the validity of equation (14) was verified.

Next, the reverse polarity toner ratio was analyzed. The single-oscillation air flow method using the laser Doppler method for the charge distribution of the toner flying on the drum 3 as if it were an electrostatic latent image holder (Hosokawa Micron E-SPART ANALYZER)
The volume ratio Rv of the opposite polarity toner of the toner A having an average specific charge Q / M of 2.1 μC / g is 28.5%, while the R of the toner D having a Q / M of 5.1 μC / g is measured by _V is 9.8
%, Q / M is 7.3 μC / g, Rv of toner E is 5.2%, Q / M
Of toner F having a viscosity of 8.2 μC / g was 3.0%. With respect to Toner B, the flying amount was too small to measure. From the above, it was possible to set the reverse polarity toner ratio to less than 10% for the toner having an average specific charge Q / M of more than 5 μC / g. It was also confirmed that the larger the Q / M, the smaller the ratio of the reverse polarity toner in the toner after development.

From the above-mentioned toner flight experiment result, 11 μm
By setting the interparticle force Fv of the following toner to 5 nN or less,
It was demonstrated that the required amount of development W1 (the amount of toner that is separated by development among the toners stacked and supported on the toner carrier) can be secured. Further, the interparticle force Fv can be obtained by substituting the measured values into the equations (1) to (3).
It has been proved that the interparticle force Fv can be further reduced by adding the fine particles of 0.01 to 1 μm to the toner of 11 μm or less. The validity of the lower limit and the upper limit of the specific charge (Q / M) in the formula (4): 5 μC / g ≦ Q / M ≦ (ε o ε _T / W ₁ ) · E was proved.

Conventionally, the point of non-contact development is as follows.
For example, lower specific charge Q / M (3μC / g) or charge density
Toner bearing Q / A (3 × 10 ^-10 ≦ | Q / A (C / m ² ) | ≦ 10 ⁻⁷ ) with a lower packing density δP (0.1 g / cm ^{3 to} 0.6 g / cm ³ ). On the body, a thick toner layer thickness dt ₁ (15 μm to 100 μm
It was thought that the toner was carried by m), but for example, as shown in the flight test results of the toner A close to this phenomenon condition, the reverse polarity toner ratio is large and it is not practical. However, as shown in the flight test results using the toners C to F, for example, the interparticle force Fv of the toner is 0.79nN to 2.79nN by means of controlling the electrostatic force and electric field strength acting on the toner.
By suppressing the specific charge Q / M (5.1 μC / g ~ 1
4.0 μC / g) toner with higher packing density δP (0.51 g / cm
^{3 to} 0.82 g / cm ³ ) and a thin toner layer thickness dt ₁ (8.5 μm to ₁
5.5 μm), the toner can be carried on the toner carrier, and the toner can be fly-developed, and an excellent image quality with a small reverse polarity toner volume ratio R _v can be obtained. Here, filling density (δP) = true density (δ) × filling ratio (P) toner layer thickness (dt ₁ ) = toner adhesion amount (M / A) ÷ filling density (δP).

Among the toners shown in the table of FIG. 12, the toner having the largest flying amount is the toner F having the second largest average particle size after the toner A, and the developing amount per one rotation of the toner carrier (developing roller) is , 0.5 mg / cm ² was obtained. Development amount 0.5
In the case of mg / cm ² or more, an optical reflection density of 1.3 or more can be obtained, so that for the toner F, the desired performance can be secured in the developing device with the peripheral speed ratio k = 1 of the developing roller. On the other hand, considering a developing device using the toner C, the toner C is a toner having the smallest particle size and a high specific charge, and the reverse polarity toner volume ratio Rv is 1.4%, which is sufficiently small. Therefore,
For toner C, the image quality with sharpness can be expected due to the synergistic effect of improving the image quality by reducing the particle size, but the developing amount per one rotation of the developing roller is 0.3 mg / cm ² , and the required developing amount is 0.5 mg. / cm ² has not been reached.

Therefore, it is necessary to increase the peripheral speed ratio k of the developing roller to be larger than 1 to increase the total amount of development on the electrostatic latent image holding member. However, since the edge enhancement occurs as described above under the condition that the peripheral speed ratio is large, in order to realize the developing device in which the edge enhancement does not occur, the formula (5): W _D
It is necessary to satisfy ≦ W ₁ · k ≦ W _R. Therefore, it is important to have a configuration having both the developing conditions of the formula (4) and the developing condition of the formula (5). In order to confirm the effectiveness of the formula (5) of the present invention, a developing unit having the same structure as that of the experimental machine of the developing device shown in FIG. As a copier, copying speed is 20 sheets / min, process speed is 175m
A m / sec model was used.

When the required developing amount W _D is 0.5 mg / cm ² , the developing amount W _{1 of} the toner C per revolution of the developing roller is 0.3 mg / c.
Substituting m ² and the toner adhesion amount W _R on the developing roller to 0.6 mg / cm ² in the equation (5), 0.5 ≦ 0.3 · k ≦ 0.6 and 1.67 ≦ k ≦ 2.00. Therefore, the peripheral speed ratio k was set to 1.7. That is,
The drum 3, which is an electrostatic latent image holder, has a peripheral speed of 175 mm / clockwise.
Rotate for sec, developing roller 2 rotates counterclockwise at a peripheral speed of 300 m
Rotated at m / sec. The gap between the drum 3 and the developing roller 2 was 0.13 mm. The latent image potential of the image part of the drum 3 is -700
V and the developing roller 2 were grounded. A copied image is taken under the above developing conditions, the image is picked up by a CCD camera, moved on the recording paper 50 shown in FIG. 5 in the y-axis direction, and the output level i of the CCD camera is taken in as data of 256 gradations per pixel. It is.

This data is used as a reflection density D = -ln (i /
When converted into density information using the relationship of (256), a density distribution as shown in FIG. 13 was obtained. FIG. 13 is a graph showing an actual measurement example 1 of the density distribution of a copy image which has been flight-developed by the developing method of the present invention. As shown in FIG. 13, the peripheral speed ratio k
It can be seen that when the (developing roller peripheral speed / drum peripheral speed) is set to 1.7, there is no edge enhancement and a good image quality without fog in the background distribution is obtained at a solid density of 1.4 or more.
Further, when a repeating pattern of black and white stripes was copied to examine the resolution and the copied image was evaluated by a CCD camera, a resolution sufficient to reproduce 5 lp / mm was obtained.

Further, as a comparative example, in order to verify the effectiveness of the equation (5), a copying test was conducted by using the same device and toner as the developing device used in the example and changing the peripheral speed ratio k of the developing roller. I tried. FIG. 14 is a graph showing an actual measurement example 2 of the density distribution of the copy image which is flight-developed by the developing method of the present invention.
As shown in FIG. 14, in the case of k = 3 and k = 0.5, the density distribution of the toner adhering portion S _D on the recording paper 50 was examined in the y-axis direction (direction from edge A2 to edge B2). is there. When k = 3, the density of the edge B2 was emphasized, and when k = 0.5, the edge A2 was emphasized, and a uniform density distribution could not be obtained. In addition,
As shown in (3-b) of FIG. 6, when the developing roller is moved in the opposite direction to the drum, the density distribution is such that the edge A2 is very emphasized.

According to the above copying test, the developing amount per one rotation of the developing roller, the developing roller peripheral speed ratio, and the required developing amount satisfy the expression (5), so that it is possible to provide the developing device in which the developing amount is increased without edge enhancement. I was able to prove it. In the present embodiment, in the case of a toner having a small particle size such as the toner C, which has a relatively large specific charge and a small development amount, the invention configuration for setting the development condition of the formula (4) and the formula (5). Although it has been explained that a desired developing device can be realized by an invention in which the invention configuration for setting the developing conditions is combined, if the developing amount per one rotation of the developing roller is exceeded, the formula can be obtained without combining the two inventions. A developing device that satisfies the individual developing conditions of (4) or (5) is possible.

That is, a developing device satisfying the developing condition of the equation (4) can be constructed with the peripheral speed ratio k being 1, or,
A configuration (means of setting the peripheral speed ratio k to a value smaller than 1) which is included in the invention satisfying the developing condition of the expression (5) but does not satisfy the two developing condition expressions at the same time is also possible. In the non-magnetic one-component non-contact development of the present invention, there is no magnetic binding force in the developing portion, development can be performed only by controlling the electrostatic force and charge strength acting on the toner, and the mechanical adhesion of the toner is small. Due to the points, there was no offset in the development start potential, and a linear γ characteristic (gradation / reproducibility) was obtained. Therefore, it is possible to realize development that is faithful to the latent image potential, and it is possible to satisfactorily copy an image including a halftone such as a photograph.

In the embodiment of the present invention, as shown in FIG. 1, the toner supply member 6 which comes into contact with the toner carrier 2 is used as means for charging and supplying the non-magnetic one-component toner 1, and the toner supply member 6 is used. The non-magnetic one-component toner is charged by the friction between the supply member 6 and the toner carrier 2 and is applied on the toner carrier 2. As a means for charging the non-magnetic one-component toner, a charge from a conductive electrode is used. Means such as injection or corona discharge may be used.

When the toner charging / applying means is changed, the specific charge of the toner and the toner adhesion amount on the developing roller are changed even if the same toner is used. However, by controlling the electrostatic force acting on the toner and the electric field strength, the reverse It is possible to provide a developing device in which the ratio of polar toner is small, an excellent image quality without background fog can be obtained, and edge enhancement can be avoided. Also,
In the present invention, the developing roller is provided as the toner carrier, but means other than the roller can be used. For example, even when a rotating developing belt or the like is used as the toner carrier, the developing device applied to the embodiment of the present invention can be provided.

[0096]

According to the present invention, stable non-contact development is achieved only by means of controlling the electrostatic force acting on the toner and the electric field strength by suppressing the interparticle force of the toner other than the image force acting on the toner to 5 nN or less. To realize. As a result, a) stable flight development with a sufficiently large allowable range of the specific charge of the toner can be realized. b) It is possible to provide a non-contact developing method in which the ratio of the reverse polarity toner is small, there is no background fog, and the sharpness is excellent. c) A toner having a small particle size of 11 μm or less can be developed in a non-contact manner, and a non-contact developing method excellent in resolution and gradation can be provided. Therefore, unlike the conventional case, it is not necessary to selectively use monochrome development by contact development to secure resolution, and only color development, non-contact development for the convenience of gradation and color superposition. By controlling the peripheral speed ratio of the toner carrying member and the electrostatic latent image holding member, the applicable range of the invention is further expanded. That is, d) The development density can be ensured even with the toner having a low development amount per one rotation of the development roller. e) At that time, it is possible to prevent edge enhancement due to the setting of the peripheral speed ratio and obtain a uniform density distribution. f) As a result, it is possible to positively utilize a toner having a high specific charge, which has not been practically available due to its low developability. That is,
The toner having a high specific charge can be retained on the developing roller even when the developing roller rotates at a high speed, and can be applied to a high speed process. As described above, according to the present invention, specific contact development can be applied without any special restriction on toner specific charge and toner particle size, and it is possible to realize from low speed process to high speed process in the same device regardless of monochrome or color. It is possible to provide a developing device that can be widely used as an image forming device of a copying machine or a printer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an embodiment of a developing device applied to a toner of the present invention and a non-contact developing method using the toner.

FIG. 2 is an enlarged view showing a toner of the present invention and a non-contact developing section applied to a non-contact developing method using the toner.

FIG. 3 is a graph showing toner charge amount distribution.

FIG. 4 is an explanatory diagram showing an area where an edge-enhanced image occurs.

FIG. 5 is an explanatory diagram showing an edge-emphasized image on a recording sheet.

FIG. 6 is an explanatory diagram showing a magnitude relationship between a rotation direction and a peripheral speed of a toner carrier and an electrostatic latent image carrier.

FIG. 7 is a graph for setting the range of the specific charge Q / M of toner.

FIG. 8 is a graph for setting the range of the peripheral speed ratio k.

FIG. 9 is a graph showing the relationship between toner particle diameter d and developing amount M / A with respect to toner particle force Fv.

FIG. 10: Toner specific charge with respect to toner particle force Fv value
It is a graph which shows the permissible range of Q / M.

FIG. 11 is a graph showing a relationship between a toner specific charge and a developing amount with respect to toner particle diameter / interparticle force.

FIG. 12 is a table showing the flight test results of the toner of the present invention.

FIG. 13 is a graph showing an actual measurement example 1 of the density distribution of a copy image that has undergone flight development by the developing method of the present invention.

FIG. 14 is a graph showing an actual measurement example 2 of the density distribution of a copy image that has been flight-developed by the developing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic one-component toner 2 Toner carrier (developing roller) 3 Electrostatic latent image carrier drum (drum) 4 Blade 5 Toner stirring member 6 Toner supply member 7 Hopper 1a Toner layer on toner carrier

Front page continued (72) Inventor Nobuyuki Higashi 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka

Claims (14)

[Claims] 1. A toner is laminated and carried on a toner carrier.
The inter-particle force calculated by the following equation (1) is 5
nN or less, Fv = q · E−Fi (1) [where Fv is the interparticle force and q · E is calculated by the formula (2)]
Coulomb force, q ・ E = q ・ {Vb + (Q / M) ・ δ ・ P ・ dt₁ ²/ (2ε o ε_T)} / (Ε_T・ G + dt ₁ ) (2) In the formula, Fi is the image force calculated by the formula (3), and Fi = {(W₁・ Πd³・ Δ) / (6 εo ε_T)} ・ (Q / M)²(3) (where, q is the charge amount [C] of the toner particles to be developed,
E is the electric field strength [V / m] acting on the toner layer, Q / M is the toner ratio
Charge [μC / g], W₁Is a stack of toner on the toner carrier.
Of toner, the amount of toner separated by development [mg / c
m²], Ε o is the vacuum permittivity [C / (V · m)], ε_TOf the toner layer
Apparent relative permittivity [C / (V m)], d is toner particle size [μ
m] and δ are true densities of toner [g / cm³], G is on the toner carrier
Gap between the top surface of the toner and the electrostatic latent image holder [mm], dt₁Is
The toner layer thickness [μm] on the toner carrier, Vb is the development bias.
As voltage [V], P is the toner filling rate)]
Toner. 2. The toner has an interparticle force of 0,01 nN to 5
The toner according to claim 1, which is nN. 3. The toner has an average particle diameter of 5 μm to 11 μm.
The toner according to claim 1, wherein the toner has a size of μm. 4. The toner as a spacer has an average particle size of
4. Inert fine particles having a size of 0.01 μm to 1 μm are contained.
The toner described in the above. 5. The toner has a specific charge of 5 .mu.C / g.about.15.
The toner according to claim 1, which is in the range of μC / g. 6. The toner has an average particle diameter of 5 μm to 11 μm.
The toner according to claim 1, which has a specific charge of 5 μC / g to 15 μC / g. In wherein said toner is stacked carrying toner layer thickness of about 5μm~20μm on that toner carrying member, and the packing density is in the range of about 0.4g / cm ³ ~0.85g / cm ³ according Item 1. The toner according to Item 1. 8. The toner has a specific charge of 5 μC / g to 1
5 μC / g, the thickness of the toner layer laminated on the toner carrier is about 5 μm to 20 μm, and the packing density is about 0.4 g / cm ^3.
2. The toner according to claim 1, which is in the range of 0.85 g / cm ³ . 9. The toner according to claim 1, wherein the toner is an image forming toner which contains a binder resin as a main component, and optionally contains a colorant, an internal additive and an external additive. 10. The toner according to claim 1, wherein the toner is a non-magnetic one-component toner. 11. The toner according to claim 1, wherein the toner is formed into a predetermined average particle size by a melt-kneading and pulverizing process. 12. A toner carrier for laminating and carrying a charged toner as a developer, an electrostatic latent image carrier opposed to the toner carrier with a gap, and a toner carrier and an electrostatic latent image carrier. 2. A developing device comprising at least an electric field application control means for applying and controlling an electric field between bodies, wherein the toner is stacked and carried on the toner carrier.
The interparticle force described is 5 nN or less, claims 1 to 1.
1. A non-contact phenomenon method in which the electrostatic latent image holding member is fly-developed using the toner according to any one of 1. 13. The electric field application control means has a toner having a specific charge of the following formula (4): 5 μC / g ≦ Q / M ≦ (ε o ε _T ) / W ₁ ) · E (4) (said In the formula (4), E is the electric field strength [V / m] acting on the toner layer.
, Q / M is the specific charge of the toner [μC / g], W ₁ is the toner amount [mg / cm ² ] separated by development among the toners stacked and carried on the toner carrier, and εo is the vacuum dielectric constant. [C / (V ・ m)]
, Ε _T is controlled so as to satisfy the apparent relative dielectric constant [C / (V · m)]) of the toner layer. 14. A peripheral speed ratio control means for controlling a peripheral speed ratio between the toner carrying member and the electrostatic latent image holding member, wherein the peripheral speed ratio controlling means has a peripheral speed ratio represented by the following formula (5): W _{D ≦ W 1 · k ≦ W} R ‥‥ (5) ( the (5) wherein, to move in the same direction as the toner carrier and the electrostatic latent image holding member, k is the electrostatic latent image to the toner carrying member The peripheral speed ratio with the holding body, W _R is the toner adhesion amount [mg / cm ² ] on the toner carrying body carrying the toner, and W ₁ is separated by development among the toners carried on the toner carrying body in a laminated manner. The non-contact phenomenon method according to claim 12 or 13, wherein the toner amount [mg / cm ² ] and W _D are controlled so as to satisfy the required developing amount [mg / cm ² ]).