JPH08152733A - Image forming device - Google Patents

Abstract

PURPOSE: To always excellently form image by keeping image density, the fogging of a photoreceptor and toner left without being transferred in a good state and preventing the toner from being flocculated. CONSTITUTION: The surface of a photoreceptor drum 11 is electrified by an electrifying brush 12, the electrified surface of the photoreceptor is exposed with a light beam 13 to form an electrostatic latent image, and the toner is stuck to the electrostatic latent image from a developing roller 17 to form a toner image, then the toner image is transferred to transfer paper 23 by a transfer device 22. A toner layer thickness regulating blade 20 is provided in press-contact with the developing roller, the toner to be used is one-component non-magnetic toner 16, and fluidized particulates are externally added to the toner 16. When it is assumed that the average particle size of the toner is D1, the specific gravity thereof is ρ1, the average particle size of the fluidized particulates is D2, the specific gravity thereof is ρ2, and the wet.% of additive quantity is Y2, they are set to satisfy 1.21<Y2/100.ρ1/ρ2.D1/D2<=3.63.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which uses a one-component non-magnetic toner for development and forms an image by electrophotography.

[0002]

2. Description of the Related Art An image forming apparatus of this type using a one-component non-magnetic toner for development is disclosed in, for example, JP-A-4-152.
As described in Japanese Patent No. 354, a binder resin having a fixing property and a triboelectrification characteristic, carbon black and a dye,
A mixture of a colorant such as a pigment, a charge control agent such as a metal dye or a surfactant, and a wax that controls the adhesion to a fixing roll is used as a base material, and silica or the like is externally added as a fluidity improver to the base material. The toner is generally used as a toner.

However, depending on the amount of silica added externally, sufficient fluidity and transportability cannot always be obtained, and the developing characteristics deteriorate with time and the image quality is impaired, or silica floats from the surface of the toner base material and becomes a developer. Occurs, and further, the charging characteristics of the toner are affected and the charging characteristics are deteriorated.

Therefore, in this publication, the amount of silica added externally and the particle size are regulated so that the fluidity and transportability of the developer can be stably maintained.

Further, in JP-A-64-10269 and JP-A-2-151872, development characteristics are obtained by externally adding two kinds of fine particles having different particle sizes to a toner base in a one-component non-magnetic developer. It is described that the improvement of

According to these publications, in order to deal with image unevenness, bleeding, fog and the like due to insufficient charging of toner or uneven charging, inorganic fine particles having a particle diameter of less than 10 nm are externally added to the toner base. As a result, high triboelectrification performance and fluidity are obtained, and image unevenness, bleeding, fog, etc. are improved.

On the other hand, when the chargeability of the toner is increased, the adhesive force between the photosensitive drum and the toner particles is increased, and the transferability is lowered. Therefore, by further externally adding inorganic fine particles having a particle diameter of less than 30 nm and twice or more the particle diameter of the small particles, the inorganic fine particles serve as a spacer to enhance the transfer efficiency.

Further, JP-A-4-34566 discloses a contact charging / cleanerless type image forming apparatus using a one-component non-magnetic toner. In this method, a charging brush is used to uniformly charge the photoconductor and residual toner remaining on the photoconductor after transfer is collected by a developing roller of a developing device.

Further, Japanese Unexamined Patent Publication (Kokai) No. 5-188637 discloses a cleanerless type image forming apparatus of a one-component non-magnetic developing type using spherical toner produced by a polymerization method. In this publication, it is stated that the use of spherical toner makes it possible to obtain a clear image free from fog on white background, dust, unevenness, and ghost images. That is, the toner produced by the polymerization method has a spherical shape and is uniform,
The spread of the particle size distribution is also small, the spread of the charge amount is smaller than that of the irregular toner produced by the pulverization method, and the developing roller and the toner layer regulating blade that regulates the thickness of the toner layer attached to the developing roller. It is said that the generation of fine powder toner due to the pressure and the collision of toner particles can be suppressed to be small because the toner is spherical, and stable image quality can be obtained by these.

[0010]

In the case of developing using one-component non-magnetic toner, a method of regulating the toner layer thickness with respect to the toner holding member (developing roller) and a method of replenishing the toner,
In addition, the development characteristics due to the charging ability and fluidity of the toner differ depending on the toner shape, the handling method of the untransferred toner, the charging method of the photoconductor, etc., and the good development characteristics common to all of the one-component non-magnetic developing methods are obtained. The formulation of the externally added fine particles and the particle size shown were not specified.

Further, in JP-A-4-34566, since there is no cleaner, paper powder adhered to the photoconductor in the transfer step and a component of paper called filler (talc: hydrous magnesium silicate, calcite: calcium carbonate, Kaolin:
Hydrous aluminum silicate, etc.) is recovered in the developing device in the developing process. Therefore, for example, when a sheet containing a large amount of talc is used as a transfer medium, in a high temperature and high humidity environment (for example, 30 ° C. and 85% RH), talc acts as a core of toner in the nip portion between the developing roller and the toner layer regulating blade. Aggregation occurs. As a result, the formation of the toner layer on the developing roller becomes defective, the toner charging becomes insufficient, and the oppositely charged toner adheres to the unexposed portion. As a result, a fog phenomenon occurs in which the white background on the paper becomes black. Further, the amount of toner adhering to the developing roller per unit area, that is, the amount of toner conveyed decreases. As a result, print fading occurs.

Further, in the case where toner is replenished in order to prolong the life of the developing device, a large amount of toner in the vicinity of the average particle size is used in the particle size distribution of the toner, and the toner is pulverized due to collision between the toner particles. Therefore, the toner charge amount distribution in the developing device changes as the number of printed sheets increases.

For example, FIG. 7 shows a toner charge amount distribution measuring device (E-SPAR manufactured by Hosokawa Micron Co., Ltd.).
T ANALYZER), graph a shows the toner charge amount distribution in the initial state, graph b shows the toner charge amount distribution immediately before toner replenishment, and graph c shows the toner charge amount distribution immediately after toner replenishment. There is. That is,
When the toner is consumed and the toner amount becomes smaller than in the initial state, the charge amount distribution of the negatively charged toner is closer to the positive side, that is, the oppositely charged side, and the number of the positively charged oppositely charged toner also increases. .

When new toner is replenished, immediately after the replenishment, toner having a higher charge amount (large negative value) than in the initial state is generated. This is because the positively charged toner (reversely charged toner) and the negatively charged toner are aggregated by the electrostatic force, the fluidity of the toner is temporarily deteriorated, and the toner slip is deteriorated at the nip portion between the toner layer regulating blade and the developing roller. Therefore, it is considered that the toner charge amount due to friction is increasing.

Such electrostatic agglomeration of toner grows to a larger toner agglomeration at the nip portion between the toner layer regulating blade and the developing roller, which causes defective toner layer formation and uneven density in the transferred image.

Further, toner agglomeration grows and a part of the toner is melted to become a complete solid matter, which is fixed to the toner layer regulating blade. Then, the toner adhered matter is rubbed against the developing roller with a large pressure, so that the toner component is filmed on the developing roller. At the filmed portion, the toner is not sufficiently charged, and vertical black stripes appear on the transferred image. Occurs.

Further, in JP-A-4-152354, when silica externally added to the toner is liberated, the silica is likely to adhere to the photosensitive drum. The silica thus attached further adheres to the charging brush.

Further, in the case of contact charging / cleanerless as in JP-A-4-34566, when the transfer residual toner passes through the charging brush or when the transfer residual toner adheres to the charging brush. In addition, silica is separated from the toner and adheres to the charging brush. When silica adheres to the charging brush, the charging performance of the charging brush is deteriorated because silica is an insulator, which causes charging failure. Then, vertical black streaks occur on the transferred image due to poor charging.

Even in a contact charging type image forming apparatus equipped with a cleaner, since the particle size of silica is much smaller than that of toner and the fluidity thereof is good, the silica is not sufficiently removed by the cleaner. Adhesion also causes defective charging, and vertical black streaks occur on the transferred image as in the case of cleanerless.

Further, in the one-component non-magnetic developing type cleanerless type image forming apparatus using the spherical toner manufactured by the polymerization method as disclosed in JP-A-5-188637, since the toner is spherical, pressure is applied to the toner. When it is added, the hexagonal close packing becomes easy. At this time, the fluidity of the toner is also small, and the toner is easily condensed. Therefore, toner agglomeration occurs in the nip portion between the developing roller and the toner layer regulating blade, and the toner layer thickness on the developing roller becomes uneven, which adversely affects the transferred image.

According to the first aspect of the invention, development is performed using a one-component non-magnetic toner, and the toner layer thickness regulating member is pressed against the surface of the toner retaining body to regulate the toner layer thickness on the toner retaining body. In this case, by using fluidized fine particles as fine particles to be externally added to the toner, and by optimizing the average particle diameter of the toner and the fluidized fine particles, the specific gravity, and the blending amount of the fluidized fine particles, the image density, photoconductor fogging, transfer (EN) An image forming apparatus capable of keeping the rest in a good state, preventing filming of a toner holder and agglomeration of toner even when toner is replenished, and always realizing good image formation. To do.

According to a second aspect of the present invention, development is performed using a one-component non-magnetic toner, and a toner layer thickness regulating member is pressed against the surface of the toner holding body to regulate the toner layer thickness on the toner holding body. Further, in the one in which the transfer residual toner is recovered and reused in the developing means, fluidized fine particles and second fine particles are used as fine particles externally added to the toner, and the average of the toner, the fluidized fine particles and the second fine particles is used. By optimizing the particle size, specific gravity, fluidized fine particles, and second fine particle content, the image density, photoconductor fogging, and transfer residue can be maintained in good condition. You can prevent the body from filming and the toner from agglomerating.
Further, the present invention provides an image forming apparatus which can prevent toner from aggregating due to paper components such as talc that are mixed in during toner recovery and can always realize good image formation.

According to a third aspect of the present invention, development is performed using a one-component non-magnetic toner, and a toner layer thickness regulating member is pressed against the surface of the toner holding body to regulate the toner layer thickness on the toner holding body. Further, in the case where the surface of the electrostatic latent image carrier is uniformly charged by contact charging, fluidized fine particles and second fine particles are used as fine particles externally added to the toner, and the average of the toner, the fluidized fine particles and the second fine particles is used. By optimizing the particle size, specific gravity, fluidized fine particles, and second fine particle content, the image density, photoconductor fogging, and transfer residue can be maintained in good condition. You can prevent the body from filming and the toner from agglomerating.
Further, the present invention provides an image forming apparatus capable of preventing externally added fine particles from being detached and adhering to a contact charging means, and always realizing good image formation.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second or third aspect, the toner shape is spherical, and the average particle diameter, specific gravity and blending amount of the externally added fine particles with respect to the toner are optimized. Thus, an image forming apparatus is provided which can reliably prevent toner aggregation and realize better image formation.

[0025]

The invention according to claim 1 is
An electrostatic latent image carrier that holds the electrostatic latent image, a charging unit that uniformly charges the surface of the electrostatic latent image carrier, and a part of the charge on the surface of the electrostatic latent image carrier that is charged by the charging unit. A unit for attenuating to form an electrostatic latent image, a developing unit for adhering toner to the electrostatic latent image formed by this unit to develop it to form a toner image, and a toner image formed by this developing unit. The developing means includes a transfer means for transferring to a transfer medium, and the developing means includes a toner holding body for supplying the toner to the surface of the electrostatic latent image holding body, and a toner layer for pressing the surface of the toner holding body to supply the surface of the electrostatic latent image holding body. In an image forming apparatus provided with a toner layer thickness regulating member for regulating the thickness, a one-component non-magnetic toner is used as the toner supplied from the developing means to the surface of the electrostatic latent image carrier, and fluidized as fine particles externally added to this toner. Uses fine particles and The Hitoshitsubu径 D1, the specific gravity and .rho.1, when the average particle size of the fluidizing particles D2, a specific gravity [rho] 2, the weight percent of the amount was Y2, 1.21 <Y2 / 100 · ρ1
/ Ρ 2 · D 1 / D 2 ≦ 3.63, D
The values of 1, D2, ρ1, ρ2, and Y2 are set.

According to a second aspect of the present invention, an electrostatic latent image holding member holding an electrostatic latent image, a charging unit for uniformly charging the surface of the electrostatic latent image holding unit, and a static charging unit charged by the charging unit. A means for attenuating a part of the charges on the surface of the electrostatic latent image carrier to form an electrostatic latent image; and a developing means for adhering toner to the electrostatic latent image formed by this means to develop and form a toner image. , A transfer means for transferring the toner image formed by the developing means to a transfer medium, and the developing means supplies the toner to the surface of the electrostatic latent image holding body, and the developing means is in pressure contact with the surface of the toner holding body. In an image forming apparatus in which a toner layer thickness regulating member that regulates the thickness of the toner layer supplied to the surface of the electrostatic latent image carrier is provided, and the untransferred toner is collected and reused in the developing unit, the electrostatic latent image is developed from the developing unit. One-component non-magnetic toner as the toner supplied to the surface of the holder The fluidized fine particles and the second fine particles having an average particle diameter larger than that of the fluidized fine particles are used as the fine particles to be externally added to the toner, and the average particle diameter of the one-component non-magnetic toner is D1 and the specific gravity is ρ1. When the average particle diameter of the fluidized fine particles is D2, the specific gravity is ρ2, the weight% of the added amount is Y2, the average particle diameter of the second fine particles is D3, the specific gravity is ρ3, and the weight% of the added amount is Y3, 1.21 <Y2 / 100
・ Ρ1 / ρ2 ・ D1 / D2 ≦ 3.63 and D2 <D3 <
0.155 · D1 and 1 <Y3 / 100 · ρ1 / ρ3 ・
^{(D1 / D3) 3 ≦ 3} , so as to satisfy, D1, D2
, D3, ρ1, ρ2, ρ3, Y2, Y3.

According to a third aspect of the present invention, the electrostatic latent image holding member holding the electrostatic latent image and the electrostatic latent image holding member are arranged in contact with each other, and the electrostatic latent image holding member surface is made uniform. Contact charging means for charging, means for forming an electrostatic latent image by attenuating a part of the charges on the surface of the electrostatic latent image holding member charged by the contact charging means, and an electrostatic latent image formed by this means. The developing means is provided with a developing means for forming a toner image by applying toner to the developing means, and a transferring means for transferring the toner image formed by the developing means onto a transfer medium. In an image forming apparatus provided with a toner holder to be supplied and a toner layer thickness regulating member which is brought into pressure contact with the surface of the toner holder to regulate the thickness of the toner layer to be supplied to the surface of the electrostatic latent image holder, an electrostatic latent image from a developing unit is provided. One-component non-magnetic toner is used as the toner to be supplied to the surface of the image carrier. Then, as the fine particles to be externally added to the toner, fluidized fine particles and second fine particles having an average particle diameter larger than that of the fluidized fine particles are used, and the average particle diameter of the one-component non-magnetic toner is D1 and the specific gravity is ρ1, The average particle size of the fluidized fine particles is D2, the specific gravity is ρ2, and the weight% of the added amount is Y2.
When the average particle size of the second fine particles is D3, the specific gravity is ρ3, and the weight% of the added amount is Y3, 1.21 <Y2 / 100ρ
1 / ρ 2 · D 1 / D 2 ≦ 3.63 and D 2 <D 3 <0.
155 · D1 and 1 <Y3 / 100 · ρ1 / ρ3 ・ (D
1 / D3) ³ ≦ 3, D1, D2, D
The values of 3, ρ1, ρ2, ρ3, Y2, and Y3 are set.

According to a fourth aspect of the invention, in the image forming apparatus according to the first, second or third aspect, the toner shape of the one-component non-magnetic toner is spherical.

[0029]

The invention corresponding to claim 1 will be described.

First, the minimum adhered amount of the fluidized fine particles will be described below. The minimum adhered amount of the fluidized fine particles is the minimum amount at which the toner particles do not directly contact each other, and the adhered state of the fluidized fine particles B on the surface of the toner base A is shown. As shown in (a) and (b) of FIG. 1, the hexagonal closest packing is in a state in which the minimum amount of particles is removed so that the particles do not contact each other.

If the particles are slightly denser than this state, as shown in FIG. 2 (a), the fluidized fine particles B come into contact with each other and repel each other, whereby the toner layer thickness regulating member and the toner holding member are contacted. The fluidity of the toner base A is ensured even under the pressure at the contact point with.

If the particles are a little coarser than this state, as shown in FIG. 2B, the toner base A and the fluidized fine particles B are contacted with the toner layer thickness regulating member and the toner holder. Under the pressure, the fluidized fine particles t and the toner base A are brought into contact with each other to easily cause toner aggregation.

Therefore, the toner base A in the state of FIG.
If the coverage of the fluidized fine particles B on the surface is γ min,

[Equation 1]

It becomes

Next, the maximum adhered amount of fluidized fine particles will be described.

The adhering state of the particles in the maximum adhering amount of the fluidized fine particles B is hexagonal closest packing, as shown in FIG. In a state in which the particles are slightly denser than this state, the fluidized fine particles B adhere to the toner base A in two or more stages, and
The state becomes as shown in (b) of. At this time, since the fluidized fine particles B are in contact with each other, the fluidized fine particles B that do not directly contact the toner base A collide with each other due to the pressure at the contact portion between the toner layer thickness regulating member and the toner holder.
Since friction is generated, the toner is easily released from the toner base A.

Therefore, when the coverage of the fluidized fine particles B on the surface of the toner base A in the state of FIG.

[Equation 2]

[0038]

Next, the weight ratio of the fluidized fine particles will be described.

First, the number of adhering fluidized fine particles B is set to n2, and this is determined. If the surface area of the toner base A is S1, the projected area of the fluidized fine particles B is S2, and the coverage of the fluidized fine particles B on the surface of the toner base A is γ, then γ · S1 =
The relationship of n2 and S2 is established. Therefore, the toner base A
And when regarded as a sphere fluidization particles B, n2 = S1 / S2 · γ = 4π (D1 / 2) 2 / π (D2 / 2) 2 · γ = 4 (D1 / D2) 2 · γ ... ( 3)

Here, D1 is the average particle size of the toner base A,
D2 is the average particle size of the fluidized fine particles B. The relation of the above equation (3) is established when the particle size of the fluidized fine particles B is sufficiently smaller than the particle size of the toner base A, and D1 / D2> 1.
00 is desirable.

Next, assuming that the specific gravity of the toner base A is ρ1 and the specific gravity of the fluidized fine particles B is ρ2, the total weight of the toner base A is M.
1, the total weight of fluidized fine particles B is M2, and the total number of toner particles is α
Then, M2 / M1 = [ρ2 ・ 4π / 3 ・ (D2 / 2) ³・ n2 ・ α] / [ρ1 ・ 4π / 3 ・ (D1 / 2) ³・ α] = ρ2 / ρ1 ・ (D2 / D1) ³ · n2 (4) Here, from the above equations (3) and (4), M2 / M1 = ρ2 / ρ1D2 / D14γ (5) If Y2 is the weight percentage of the fluidized fine particles B with respect to the total toner, then Y2 = M2 / (M1 + M2) .100, but since M1 / M2 is in the range of about 100, Y2 = M2 / M1.multidot. It does not matter as 100 (6).

Therefore, from the above equations (5) and (6), 4γ = Y2 / 100ρ1 / ρ2D1 / D2, so that Y2 falls within the range satisfying the above equations (1) and (2). When the value of is determined, 4 · γmin <Y2 / 100 · ρ1 / ρ2 · D1 / D2 ≦
4 · γmax, and by substituting the numerical values of γmin and γmax into this, 1.21 <Y2 / 100 · ρ1 / ρ2 · D1 / D2 ≤3.63 (7). The average particle diameter D1 and specific gravity ρ1 of the one-component non-magnetic toner and the average particle diameter D2 and specific gravity ρ2 of the fluidized fine particles and the addition amount Y2 can be properly set by the equation (7).

Next, the invention corresponding to claim 2 will be described.

In the present invention, the fluidizing fine particles and the second fine particles having a larger particle size than the fluidizing fine particles are externally added to the toner.

When a stronger pressure contact force is generated in the pressure controlling portion between the toner layer thickness regulating member and the toner holding member, or when stronger aggregation is generated with respect to the toner due to a paper component such as talc, fluidization Due to the embedding of the fine particles in the toner base, the fluidity cannot be secured even if the fluidized fine particles are properly added, and toner aggregation occurs. In addition, the resin component of the toner base may be melted and a toner sticking substance may be generated.

In such a case, the agglomeration of the toner is prevented by attaching the second fine particles to the toner base.

The minimum adhered amount of the second fine particles will be described. Since the fluidized fine particles have already adhered to the surface of the toner base, the second fine particles are on the fluidized fine particles or between the fluidized fine particles. Existing. In order to play the role of a cushioning material for direct contact between toners, it is necessary that a minimum amount of one second fine particle is present for each toner base.

The maximum adhered amount of the second fine particles will be described. The toner moves while receiving pressure between the fixed toner layer thickness regulating member and the toner holding member, and the toner is 2 at the outlet of the toner layer thickness regulating member. Layers are uniformly formed to about 3 layers. At this time, the toner is arranged in a nearly hexagonal closest packed state.

In this process, the fine particles adhering to the toner base serve as a buffer material to prevent the toner from aggregating.
If the number of the adhered particles is too large, the second fine particles are released from the toner base, which adversely affects the toner layer formation and the toner charging.

Since the particle size of the second fine particles is larger than that of the fluidized fine particles, it is impossible to apply a planar distribution to the surface of the toner base as in the case of the fluidized fine particles. Placement must be considered.

The toner moves in the space sandwiched between the toner layer thickness regulating member and the toner holding member while receiving a strong pressure and is arranged in a hexagonal closest packing state, so that the second fine particles are adjacent to each other. The toner base itself is rotated or moved so that the second fine particles are moved or separated and reattached on the toner base so that the second base particles are arranged in the holes formed in 1.

The number and size of the holes in the hexagonal closest packing are described in "Shigeo Miwa, General Theory of Powder Engineering, Nikkan Kogyo Shimbun, 1
981, pp. 48-49 ", there are eight T-holes formed from four toner bases A1 to A4 shown in FIG. 4 (a) around one toner base, that is, one toner base. Two pieces are formed per one. Further, there are six R holes formed around the toner base A5 to A9 (the front toner base is omitted) shown in FIG. That is, one toner base is formed.

The diameter of the maximum inscribed circle of the T hole and the R hole is
Assuming that the diameter of the toner base is D1, the diameter of the T holes is Dt, and the diameter of the R holes is Dr, Dt = 0.155D1 and Dr =
It becomes 0.414D1.

Therefore, the number of fine particles having a size of Dt or less is three per toner base, that is, T holes and R holes.
Up to the total number of pores can be attached on the toner base. Since four or more holes cannot be arranged in the T hole and the R hole, they are repelled by the toner and released, or embedded in two adjacent toner bases to become a nucleus of toner aggregation. Therefore, assuming that the average particle diameter of the second fine particles is D3, the condition of D3 is D2 <D3 ≤ 0.155D1 (8). Further, the equation (4) as well as a second specific gravity of fine particles [rho] 3, the total weight M3, when the deposition number and n3, M3 / M1 = ρ3 / ρ1 · (D3 / D1) 3 · n3 ... (9 ).

If the weight% of the second fine particles to the total toner is Y3, then there is no problem that Y3 = M3 / M1.100 (10), as in the above equation (6). Therefore, the above equations (9) and (10) and condition 1
By ≦ n3 ≦ 3, 1 ≦ Y3 / 100ρ1 / ρ3 (D1 / D3) ³ ≤3 (11) In this way, the particle diameter and the addition amount of the second fine particles can be properly set by the expressions (8) and (11).

Next, the invention corresponding to claim 3 will be described.

In the invention corresponding to claim 3, the contact charging means is used as the charging means. In this invention as well, the second fine particles are externally added, and the conditions of the particle size and the addition amount are the same as those in claim 2. It is similar to the invention.

Next, the invention corresponding to claim 4 will be described.

When the toner shape is spherical, the toner shape is approximated as a spherical shape in the inventions corresponding to the respective claims, and therefore the range of the numerical values defined by the equations (7), (8) and (11) is There is almost no difference between the actual particle diameter of toner and the amount of adhered toner, and the amount of toner added to the actual toner can be accurately determined.

[0061]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment will be described as applied to a contact charging / cleanerless type image forming apparatus.

In FIG. 5, reference numeral 11 denotes a photosensitive drum which is an electrostatic latent image holder, and the photosensitive drum 11 is an organic material in which a photoconductive layer made of an organic photoconductive material is formed on the surface of a metal tube such as aluminum. It is a photoconductor.

In the charging step, the photosensitive drum 11 is uniformly negatively charged by the conductive charging brush 12 which is a contact charging means. The charging brush 12 is made of conductive rayon having a fiber thickness of 3 denier, a flocking density of 100,000 fibers / cm ² , a fiber length of about 4 to 8 mm and a resistance value of 10 ⁵ to 10 ⁶ Ωcm. There is.

As the charging brush, one obtained by subjecting polyamide, acrylic, tetrafluoropolyethylene or the like to conductive treatment may be used. As the charging brush, a fixed type brush is used in this embodiment, but other types such as a type that vibrates the fixed brush or a type that is composed of a brush roller and rotates the brush roller can be used. Besides the brush, a rubber roller blade made of urethane, NBR, silicone, SBR, EPD, or the like, or a roller blade made of a foam material can be used. However, it is required as a condition that conductivity is imparted, that the photosensitive drum is not contaminated, and that toner and toner components are not filmed.

An electrostatic latent image is formed by exposing the surface of the photosensitive drum 11 uniformly negatively charged by the charging brush 12 with a light beam 13 such as a laser beam in an exposure process. That is, the light beam attenuates a part of the charges on the surface of the photosensitive drum 11 based on the image information to form an electrostatic latent image.

The electrostatic latent image thus formed is developed by adhering toner from the developing device 14 in the next developing step.

In the developing device 14, the one-component non-magnetic toner 16 is contained in the toner hopper 15, the developing roller 17 as a toner holder is arranged at the outlet of the toner hopper 15, and the toner is supplied to the rear of the developing roller 17. Roller 18
Is arranged in contact with the developing roller 17. Further, an agitator 19 is provided at the center of the toner hopper 15.
Is provided to agitate the toner 16 in the hopper.

A toner layer thickness regulating blade 20 which is a toner layer thickness regulating member is arranged on the upper surface of the developing roller 17. The toner layer thickness regulating blade 20 is a spring 2
1, the tip portion is brought into pressure contact with the surface of the developing roller 17.

The developing roller 17 has a conductive urethane rubber layer provided around a metal shaft and a conductive urethane resin layer formed on the surface thereof.
Resistance value of 0 ⁵ Ω · m ² or less, hardness 30 degrees (JIS A type)
Has become a roller. The diameter of the developing roller 17 is 1
2 mm, and the thickness of the urethane resin layer is 20 to 50 μm.

In addition, as the developing roller, it is possible to use, in addition to silicone rubber, ethylene propylene rubber, NBR, chloroprene rubber, butyl rubber, etc., conductive carbon particles or metal fibers dispersed in rubber. Further, the surface layer of rubber is not always necessary, but may be covered with silicone resin or fluororesin.

The toner layer thickness regulating blade 20 is made of silicone rubber whose tip is processed into a cylindrical shape, a curved surface shape or a flat shape, and has a rubber hardness of 30 to 100 degrees. Developing roller 1 of the toner layer thickness regulating blade 20
The pressing force against 7 is 200 g / cm ^{2 to} 1000 g / cm ²
It is set to a degree. This toner layer thickness regulation blade 2
The material of 0 may be a rubber material such as urethane rubber and NBR, or a metal material such as stainless steel, phosphor bronze and aluminum.

The toner supply roller 18 is made of a conductive foam material, and has carbon or metal filler added to urethane to set a resistance value of 10 ³ to 10 ⁶ Ω · cm.
A blade-shaped roller may be used instead of the toner supply roller.

A toner layer is formed on the surface of the developing roller 20 by pressure contact with the toner layer thickness regulating blade 20, and the toner layer is formed by the developing roller 20 and the photosensitive drum 11.
A toner image is formed by adhering to the electrostatic latent image formed on the photoconductor drum 11 at the contact portion with.

In the next transfer step, this toner image is transferred onto a transfer medium, for example, transfer paper 23, which is supplied by the operation of the scorotron transfer device 22 having a grid. In addition,
As the transfer device, a corotron charger without a grid or a conductive roller made of rubber or foam material such as urethane, NBR, silicone, EPDM may be used.

The one-component non-magnetic toner 16 is made of various thermoplastic resins such as styrene resin, acrylic resin, polyester resin, epoxy resin, carbon, pigment,
A toner base is used in which a coloring material such as a dye, a wax such as polyethylene or polypropylene, or a polarity control material such as a metal-containing azo dye is dispersed.

As a method for producing the toner, there are a pulverization method and a polymerization method. In this embodiment, the toner produced by the polymerization method is used. Further, in order to improve the fluidity of the toner, fine particles of silica, alumina, barium titanate, zinc oxide or the like are externally added to the toner base as fluidizing fine particles.

The toner base used in this example is a spherical toner because it is produced by a polymerization method. A styrene-acrylic resin in which carbon black, a metal-containing azo dye and polypropylene are dispersed is used. The particle diameter D1 is 9 μm and the specific gravity ρ1 is about 1.1.

This toner base has an average particle diameter D2 of 11n.
Hydrophobic silica having m and a specific gravity ρ2 of about 2.3 was used as fluidized fine particles, and alumina silica having an average particle diameter D3 of 1 μm and a specific gravity ρ3 of about 2.2 was externally added as second fine particles. It is used as a finished toner. The external addition treatment of the fluidized fine particles and the second fine particles was performed simultaneously in this embodiment, but either one may be performed first.

In the embodiment having such a structure, the photosensitive drum 11 is uniformly negatively charged by the charging brush 12 in the charging step, and is exposed by the light beam 13 in the next exposure step to form an electrostatic latent image. It is formed and developed in the nip portion with the developing roller 17 in the next developing process. At this time, the toner 16 adheres only to the portion of the surface of the photosensitive drum exposed by the light beam 13 (the portion where a part of the electric charge is attenuated) by the so-called reversal development method.

In this way, a toner image is formed on the surface of the photosensitive drum. This toner image is transferred to the transfer paper 23 by the scorotron transfer device 22 in the next transfer process. In this transfer step, not all the toner is transferred, and the untransferred toner 16a is image-wise distributed on the surface of the photosensitive drum 11 after the transfer.

The untransferred toner 16a is charged to the same polarity as the surface of the photosensitive drum 11 by the charging brush 12 in the next charging step. In the exposure step, as long as the transfer residual toner 16a is not dense, the light beam 13 can expose the photosensitive drum surface without being blocked by the transfer residual toner 16a.

In the next developing step, the electric field formed by the photoconductor drum 11 and the developing roller 17 in the exposed portion acts in the direction in which the toner 16 is attached to the photoconductor drum 11. Further, in the unexposed portion, the electric field formed by the photoconductor drum 11 and the developing roller 17 causes the toner to move to the developing roller 17
It acts in the direction of adhering to the toner, and as a result, the transfer residual toner 1
6a is collected by the developing roller 17.

Thus, in the developing process, cleaning is performed at the same time as development.

In the developing device 14, the toner 16 is agitated by the agitator 19 and supplied to the developing roller 17 by the toner supply roller 18. In addition, the toner supply roller 18
Removes the toner 16 remaining on the developing roller 17 without being attached to the photoconductor drum 11 and the transfer residual toner 16a collected from the photoconductor drum 11 by rotational friction with the developing roller 17. The toner layer thickness regulating blade 20 is pressed against the developing roller 17 with a predetermined pressure to regulate the thickness of the toner layer supplied to the photosensitive drum 11 to a uniform thin layer and to charge the toner.

By the above operation, the toner image is transferred onto the transfer paper 23 to form an image.

By the way, the used one-component non-magnetic toner 1
6, image evaluation when fluidized fine particles (hydrophobic silica, average particle size D2 = 11 nm) and second fine particles (alumina silica, average particle size D3 = 1 μm) were externally added to the toner base in various weight percentages. The results are shown in Tables 1 and 2.

K2 and K3 in Tables 1 and 2 are defined as follows. K2 is defined as a value corresponding to the above-mentioned expression (7), and K2 = Y2 / 100ρ1 / ρ2D1 / D2 (12) Substituting the values of particle size and specific gravity into the above formula (12), K2 = Y2 /100×1.1/2.3×9.0/11×
10 ^-3, that is, K2 = 3.9Y2, and 1.21 <3.9.
Weight% of fluidized fine particles to satisfy Y2 ≤3.63
, Which is Y2.

Further, regarding the above equation (8), D1 =
Substituting 9, D3 = 1, 1 <0.155 × 9, that is, 1 <1.395, and the particle size of the second fine particles is
(8) is satisfied.

Therefore, as a value corresponding to the equation (11), K3
Is defined as follows, and K3 = Y3 / 100ρ1 / ρ3 (D1 / D3) ³ (13) Substituting the values of particle size and specific gravity into the above equation (13), K3 = Y3 / 100 x 1.1 / 2.2 x (9/1) ^3, that is, K3 = 3.6Y3, and 1≤3.6Y3 ≤
Y3, which is the weight percentage of the second fine particles, is determined so as to satisfy 3.

[0090]

[Table 1]

[0091]

[Table 2]

Next, each image evaluation in Tables 1 and 2 will be described. The image density a is a Macbeth reflection densitometer (RD-
920) is used to measure the solid black portion on the transfer paper 23.

The photoconductor fog was obtained by transferring the fog on the photoconductor drum 11 (non-image area, white background area) to Scotch mending tape (# 810, made by 3M), attaching it to paper, and measuring the reflectance with a color difference meter ( It is the value obtained by subtracting the reflectance when the Scotch Mendeg tape is simply pasted on the paper from the value measured by Minolta, CR-221). Therefore, the smaller this value is, the less fog occurs and the better image formation can be performed.

The transfer residual b is obtained by performing solid black printing, transferring the transfer residual toner on the photosensitive drum 11 after transfer to Scotch mending tape, adhering it to paper, and measuring the reflectance with a colorimeter. , The value obtained by simply subtracting the reflectance when the Scotch Mendegu tape is pasted on the paper. Therefore, the smaller this value is, the less the transfer residual toner is and the better the transfer is.

In the toner layer formation failure c, toner agglomeration occurs in the nip portion formed by the toner layer thickness regulating blade 20 and the developing roller 17, the toner layer cannot be made uniform, and vertical stripes (transfer paper) are formed on the image. This is a phenomenon in which density unevenness occurs in the (conveying direction of). Even when the amount of liberated fine particles is too large, the toner is poorly charged and the same phenomenon occurs.

In Tables 1 and 2, the following rankings are made. A: Good toner layer formation, no density unevenness.
B: Toner layer formation is slightly defective, and there is no density unevenness. C: Toner layer formation is slightly defective, density unevenness is slightly present (acceptable level on image). D: Poor toner layer formation, uneven density.

In the developing roller filming d, toner agglomeration occurs in the nip portion formed by the toner layer thickness regulating blade 20 and the developing roller 17, and this further develops to fix the toner particles to each other, and as a result, the developing roller 17 This is a phenomenon in which the toner is filmed in the circumferential direction of the developing roller 17 because the toner is pressed with a strong pressure. This is a phenomenon that occurs when old and new toners are mixed when new toner is supplied to the toner hopper 15. Vertical black streaks occur on the image.

In Tables 1 and 2, the following rankings are made. A: No filming, no image defect.
B: There is a small number of filming and there is no image defect. C: There is a small amount of filming, and black streaks are lightly generated (acceptable level on the image). D: There are many filmings, and black streaks occur.

Talc paper photoreceptor fog e: When printing is performed using talc-containing paper as the transfer paper 23 in a high temperature and high humidity environment (30 ° C., 80% RH), the toner layer thickness regulating blade 20 and the developing roller 17 This is a phenomenon in which talc accumulates in the formed nip portion, and the talc serves as a core to cause aggregation of toner, which adversely affects the fluidity of the toner. When this phenomenon occurs, the chargeability of the toner is deteriorated and the oppositely charged toner is generated, and the non-image portion (white background portion) of the photosensitive drum 11 is generated.
This reversely charged toner adheres to the surface and causes fog. In addition, the toner layer may not be formed uniformly, which may cause faint printing.

In Tables 1 and 2, a binary evaluation was made as to whether or not there was fogging.

Charging brush adhesion f: Hydrophobic silica, which is a fluidized particle externally added to the toner, and alumina-silica, which is a second particle, are released from the toner base, and the charging brush 1
It is a phenomenon that adheres to 2. Since these deposits are insulators, the charging ability of the charging brush 12 is significantly reduced,
As a result, a charging failure occurs and appears as vertical black streaks on the image.

In Tables 1 and 2, a binary evaluation was made as to whether black streaks exist or not.

FIG. 6 is a graph showing Tables 1 and 2, in which the horizontal axis represents the weight% of the fluidized fine particles and the vertical axis represents the weight% of the second fine particles.
O. 1-NO. 19 is arranged at a corresponding position on the graph, and the image density a, transfer residual b, toner layer formation defect c, developing roller filming d, talc paper photosensitive member fog e and charging brush adhesion f are set to a hexagonal hexagon. Each of the divided pieces is expressed in three stages. That is, white indicates good,
The shaded lines are a little good and show an acceptable level, and the black lines are bad. It should be noted that the photoconductor fogging is omitted because all samples have good values of 1% or less.

Table 3 shows the range of the three-level evaluation levels of image density a, transfer residual b, toner layer formation failure c, developing roller filming d, talc paper photoconductor fog e, and charging brush adhesion f. ing.

[0105]

[Table 3]

Y2min, Y2max, Y3min, Y3m in the graph
ax represents the minimum value and the maximum value of Y2 and Y3, respectively, and is expressed by the equations (7) and (11) and K2 = 3.9Y2, K.
Calculated from the relation of 3 = 3.6Y3, 0.31
(Y2min) <Y2 ≤ 0.93 (Y2max), 0.28 (Y
3 min) <Y3 ≤0.83 (Y3max).

Image evaluation results shown in Tables 1 and 2 and FIG. 6 [Effect of second fine particles on fogging e of talc paper photoreceptor] Sample No. 1, NO. 2 and NO. No. 11 shows that the talc paper photoconductor fog e is generated, and the talc paper photoconductor fog e is generated when the addition amount of the second fine particles is 0.28% by weight or less. This indicates that the occurrence of toner agglomeration with talc as a core cannot be prevented when the addition amount of the second fine particles is small.

Therefore, in this case, the type of paper used as the transfer paper 23 (for example, paper with less talc) and the use environment are restricted.

When an image forming apparatus provided with a cleaner is separately used as the image forming apparatus, the filler such as paper dust and talc is removed from the photosensitive drum 11 by the cleaning performed by the cleaner after the transfer. , Sample No. if toner is not recycled. 1 and N
O. Even with the toner of 2, good image quality can be obtained.

[Effects of Fluidized Fine Particles and Second Fine Particles on Developing Roller Filming] The developing roller filming d occurs when toner is replenished and mixed with an oppositely charged toner to cause toner aggregation. The fluidized fine particles improve the fluidity of the toner and prevent aggregation of the toner.

Sample No. 1-NO. 8, sample N
O. 11, NO. 14, NO. 16, NO. As shown in 17, when the addition amount of the fluidized fine particles exceeds the minimum amount of 0.31% by weight, the developing roller filming becomes difficult to occur.

On the other hand, the released second fine particles are liable to become nuclei for toner aggregation, so sample NO. 15, NO.
18, NO. As shown in 19, when the addition amount of the fluidized fine particles is 0.5% and the addition amount of the second fine particles exceeds the maximum amount of 0.83% by weight, developing roller filming occurs.

Even if the amount of fluidized fine particles added is 0.5%, developing roller filming does not occur when toner is replenished little by little to alleviate the mixing with the oppositely charged toner.

[Effect of Excess of Fluidized Fine Particles and Second Fine Particles on Image] When the added amount of fluidized fine particles exceeds the maximum value of 0.93% by weight, or when the added amount of the second fine particles is maximum When the value exceeds 0.83% by weight, the liberated fluidized fine particles or the second fine particles increase. The liberated particles adhere to the surface of the developing roller 17, and as a result, the toner does not come into direct contact with the developing roller 17, which adversely affects the charging of the toner. That is, sample NO. 1
4, NO. 16, NO. 17, NO. 18, NO. 19
As shown in, the toner layer formation becomes defective. In addition, sample NO. 11, NO. 14, NO. 16, NO. 17
As shown in, the image density also decreases. Further, the sample No. 11, NO. 14, NO. 15, NO. 16, N
O. 17, NO. 18, NO. As shown in FIG. 19, the released fine particles adhere to the charging brush 12 to cause an image defect.

[When the Fluidized Fine Particles are Very Small] Sample NO. 12 is the minimum amount of fluidized fine particles added is 0.3
It is 0.25%, which is smaller than 1%. At this time, the toner layer is not sufficiently formed and the image density is low. This is because the amount of fluidized fine particles is too small, resulting in poor fluidity and easy toner aggregation.

Further, in the measurement of the developing roller filming, the adhesion of the charging brush, and the fogging of the talc paper photoreceptor, the toner layer formation rapidly deteriorated, and it was impossible to print up to the predetermined number of prints required for the measurement, and the evaluation was impossible. It was

From the above, contact charging can be achieved by setting the conditions of the addition amount, particle size and specific gravity of the fluidized fine particles and the second fine particles so as to satisfy the equations (7), (8) and (11). A good image can be formed in a cleanerless type image forming apparatus.

Further, by setting so as to satisfy these three expressions, even in a cleanerless type image forming apparatus which performs corona charging, a cleaner is provided, but the toner collected by the cleaner is returned to the toner hopper. Similarly, a good image can be formed in a so-called toner recycling type image forming apparatus.

In an image forming apparatus that is not toner-recycle type and is equipped with a cleaner and is also equipped with corona charging, paper particles and talc are not mixed in the toner hopper, so only fluidized particles are used as particles. Good image formation can be achieved by setting the conditions for the addition amount of the finely divided particles, the particle size, and the specific gravity so as to satisfy the expression (7).

[0120]

According to the first aspect of the invention, the development is performed by using the one-component non-magnetic toner, and the toner layer thickness regulating member is brought into pressure contact with the surface of the toner holding body to form the toner layer on the toner holding body. In the case of controlling the thickness, fluidized fine particles are used as fine particles to be externally added to the toner, and by adjusting the average particle diameter of the toner and the fluidized fine particles, the specific gravity and the blending amount of the fluidized fine particles, Body fogging and transfer residue can be kept in a good state, and even when toner is replenished, it is possible to prevent filming of the toner holding body and aggregation of toner, and always achieve good image formation.

According to the second aspect of the invention, the development is performed using the one-component non-magnetic toner, and the toner layer thickness regulating member is brought into pressure contact with the surface of the toner holding body to adjust the toner layer thickness on the toner holding body. In a case where the toner is regulated and the transfer residual toner is collected and reused in the developing means, fluidized fine particles and second fine particles are used as fine particles externally added to the toner, and the toner, the fluidized fine particles, and the second fine particles are used. By optimizing the average particle size, specific gravity, fluidized fine particles, and second fine particles, the image density, photoreceptor fogging, and transfer residue can be maintained in good condition, and even if toner is replenished. It is possible to prevent filming of the toner holding member and aggregation of the toner, and further it is possible to prevent aggregation of the toner due to paper components such as talc that are mixed in during toner recovery, so that good image formation can always be realized.

According to the third aspect of the invention, the development is carried out by using the one-component non-magnetic toner, and the toner layer thickness regulating member is pressed against the surface of the toner holding body so that the toner layer thickness on the toner holding body is adjusted. In the case of regulating and further uniformly charging the surface of the electrostatic latent image carrier by contact charging, fluidized fine particles and second fine particles are used as fine particles externally added to the toner, and the toner, the fluidized fine particles, and the second fine particles are used. By optimizing the average particle size, specific gravity, fluidized fine particles, and second fine particles, the image density, photoreceptor fogging, and transfer residue can be maintained in good condition, and even if toner is replenished. It is possible to prevent the toner holder from causing filming and to prevent the toner from aggregating, and also to prevent the externally added fine particles from separating and adhering to the contact charging means, thereby always realizing good image formation.

According to a fourth aspect of the invention, in the image forming apparatus according to the first, second or third aspect, the toner shape is spherical, and the average particle diameter, specific gravity and blending amount of the externally added fine particles to this toner are optimized. As a result, toner aggregation can be reliably prevented, and better image formation can be realized.

[Brief description of drawings]

FIG. 1 is a view for explaining the adhered state of fluidized fine particles on the surface of a toner base according to the present invention.

FIG. 2 is a diagram for explaining a minimum adhered state of fluidized fine particles on the surface of a toner base according to the present invention.

FIG. 3 is a view for explaining the maximum adhesion state of fluidized fine particles to the surface of the toner base according to the present invention.

FIG. 4 is a diagram for explaining the number and size of holes in hexagonal closest packing of the toner base according to the present invention.

FIG. 5 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 6 is a graph showing the weight percentage of fluidized fine particles and the second amount in the same embodiment.
6 is a graph showing a sample example of various evaluation elements with respect to the weight% of the fine particles of FIG.

FIG. 7 is a graph showing the number distribution of toner charge / particle diameter in the initial state, immediately before toner replenishment, and immediately after toner replenishment in an image forming apparatus of the type that replenishes toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Photosensitive drum (electrostatic latent image holder) 12 ... Charging brush (contact charging means) 13 ... Light beam (means for forming electrostatic latent image) 14 ... Developing device 16 ... One-component non-magnetic toner 17 ... Development Roller (toner holder) 21 ... Toner layer thickness regulating blade 22 ... Scorotron transfer device 23 ... Transfer paper

Claims (4)

[Claims] 1. An electrostatic latent image holder for holding an electrostatic latent image,
Charging means for uniformly charging the surface of the electrostatic latent image holding member, means for attenuating a part of the charges on the surface of the electrostatic latent image holding member charged by the charging means to form an electrostatic latent image, and The electrostatic latent image formed by the developing device is provided with a developing device that develops a toner image by applying toner to the electrostatic latent image, and a transferring device that transfers the toner image formed by the developing device to a transfer medium. A toner holding member for supplying toner to the surface of the electrostatic latent image holding member, and a toner layer thickness regulating member for pressing the toner holding member surface to regulate the thickness of the toner layer supplied to the surface of the electrostatic latent image holding member. In the image forming apparatus, the one-component non-magnetic toner is used as the toner supplied from the developing unit to the surface of the electrostatic latent image holding member, and the fluidized fine particles are used as the fine particles externally added to the toner. Average particle size of magnetic toner Where D1 is the specific gravity, ρ1 is the average particle diameter of the fluidized fine particles, D2 is the specific gravity, and Y2 is the weight percentage of the added amount, 1.21 <Y2 / 100.ρ1 / ρ2
An image forming apparatus characterized in that the values of D1, D2, ρ1, ρ2, and Y2 are set so as to satisfy 3.63. 2. An electrostatic latent image holding member holding an electrostatic latent image,
Charging means for uniformly charging the surface of the electrostatic latent image holding member, means for attenuating a part of the charges on the surface of the electrostatic latent image holding member charged by the charging means to form an electrostatic latent image, and The electrostatic latent image formed by the developing device is provided with a developing device that develops a toner image by applying toner to the electrostatic latent image, and a transferring device that transfers the toner image formed by the developing device to a transfer medium. A toner holding member for supplying toner to the surface of the electrostatic latent image holding member, and a toner layer thickness regulating member for pressing the toner holding member surface to regulate the thickness of the toner layer supplied to the surface of the electrostatic latent image holding member. In the image forming apparatus for collecting and reusing the transfer residual toner in the developing unit, the one-component non-magnetic toner is used as the toner supplied from the developing unit to the surface of the electrostatic latent image carrier, and As fine particles to be added externally Using fluidized fine particles and second fine particles having an average particle diameter larger than the fluidized fine particles, the average particle diameter of the one-component non-magnetic toner is D1, and the specific gravity is ρ1,
When the average particle size of the fluidized fine particles is D2, the specific gravity is ρ2, the weight% of the added amount is Y2, the average particle size of the second fine particles is D3, the specific gravity is ρ3, and the weight% of the added amount is Y3. , 1.21 <Y2 / 100.rho1 / rho2.D1 / D2≤
3.63 D2 <D3 <0.155 · D1 1 <Y3 / 100 · ρ1 / ρ3 · (D1 / D3) ³ ≤ 3 so that D1, D2, D3, ρ1, ρ2, ρ
An image forming apparatus characterized in that the values of 3, Y2 and Y3 are set. 3. An electrostatic latent image holding member holding an electrostatic latent image,
A contact charging unit that is arranged in contact with the surface of the electrostatic latent image holding member to uniformly charge the surface of the electrostatic latent image holding member, and one of the charges on the surface of the electrostatic latent image holding member charged by the contact charging unit. Means for attenuating a portion to form an electrostatic latent image, developing means for adhering toner to the electrostatic latent image formed by this means to develop it to form a toner image, and toner formed by this developing means The developing means includes a transfer means for transferring an image to a transfer medium, and the developing means supplies a toner to the surface of the electrostatic latent image holding body, and a surface of the electrostatic latent image holding body pressed against the surface of the toner holding body. In the image forming apparatus provided with the toner layer thickness regulating member for regulating the toner layer thickness to be supplied to the toner, the one-component non-magnetic toner is used as the toner to be supplied from the developing unit to the surface of the electrostatic latent image holding member. Fluidized fine particles as externally added fine particles Particles and second fine particles having an average particle diameter larger than that of the fluidized fine particles are used, the average particle diameter of the one-component non-magnetic toner is D1, and the specific gravity is ρ1,
When the average particle size of the fluidized fine particles is D2, the specific gravity is ρ2, the weight% of the added amount is Y2, the average particle size of the second fine particles is D3, the specific gravity is ρ3, and the weight% of the added amount is Y3. , 1.21 <Y2 / 100.rho1 / rho2.D1 / D2≤
3.63 D2 <D3 <0.155 · D1 1 <Y3 / 100 · ρ1 / ρ3 · (D1 / D3) ³ ≤ 3 so that D1, D2, D3, ρ1, ρ2, ρ
An image forming apparatus characterized in that the values of 3, Y2 and Y3 are set. 4. The image forming apparatus according to claim 1, wherein the toner shape of the one-component non-magnetic toner is spherical.